Research ArticleExperimental Studies

Combinatorial Cytotoxic Effects of 2,3-Dichloro-5,8-dimethoxy-1,4-naphthoquinone and 4-hydroxytamoxifen in Triple-negative Breast Cancer Cell Lines

ANASTASIA G.J. ROBINSON, YASMINE M. KANAAN and ROBERT L. COPELAND
Anticancer Research December 2020, 40 (12) 6623-6635; DOI: https://doi.org/10.21873/anticanres.14687

Abstract

Background/Aim: Triple-negative breast cancer (TNBC) is a highly aggressive form of breast cancer (BC) and lacks targeted therapy and alternate therapeutic combinations. There is a necessity to increase disease-free survival in patients particularly within the first 5 years of diagnosis. 2,3-dichloro-5,8-dimethoxy-1,4-naphthoquinone (Z285), a novel 1,4 naphthoquinone analog, has been shown to have cytotoxic activity in BC cell lines and in combination with 4-hydroxytamoxifen (4-OHT). A known metabolite of tamoxifen, was postulated to decrease cell proliferation. Thus, this study investigates the use of Z285 and 4-OHT alone or in combination as a novel therapeutic alternative for TNBC. Materials and Methods: Cell proliferation assays were performed on MDA-MB-231, Hs578T, MCF7 and HCC1806 cell lines at varying time points with Z285 and 4-OHT alone and in combination. Furthermore, ROS activity was measured to determine the changes in oxidative stress caused by both drugs. Results: The results showed dose- and time-dependent decreases in proliferation for all cell lines when treated with Z285, 4-OHT and their combination. Combinatorial analysis performed at 72 h using Synergyfinder® showed additive effects in MCF7, HCC1806 and Hs578T and an antagonistic response in MDA-MB-231. Z285 caused a significant increase in ROS production in three cell lines after 8 h, but HCC1806 showed no change in effect. Conclusion: These promising results suggest the independent ability of each compound as a stand-alone chemotherapeutic agent, or in combinatorial therapy for the treatment of TNBC.

Key Words:

Triple-negative breast cancer (TNBC) lacks the expression of estrogen receptor α (ERα), progesterone receptor (PR) and human epidermal growth factor receptor 2 (HER2). The loss of these therapeutic targets limits the treatment options to chemotherapy, surgery, and radiation. This subtype accounts for 10-15% of diagnosed breast cancers (BC) but approximately 35% of metastatic BC-related deaths are attributed to TNBC (1). It is an aggressive phenotype and disproportionately effects African American (AA) women where the diagnosis of this disease is twice as likely than in European American (EA) women (2). In the AA population, there is also a higher incidence in premenopausal women with this disease (3, 4). Studies of Sub-Saharan and West African women indicate increased frequency and younger age of diagnoses of TNBC when compared to AA women (5). The five- and ten-year survival rates are lower for TNBC patients when compared to other breast cancer subtypes thus novel therapies are needed to increase survival especially in stage IV (6-8).

Over the years, several therapeutic targets have been purported in vitro and in vivo to be effective in TNBC treatment such as EGFR, PI3K/mTOR, PARP, Src and RAS/RAF/MEK inhibitors but in clinical trials many have failed to be efficacious (9, 10). Recently, a new class of drugs has been approved that target BRCA1/2-mutated TNBC patients. This class of drugs, PARP inhibitors, demonstrate synthetic lethality (11, 12). However, this class of drugs only targets approximately 15% of diagnosed TNBC (13). Topoisomerase I antibody drug conjugate, sacituzumab govitecan-hizy, has recently been approved for metastatic TNBC (14-16). In general, monotherapy for cancer treatment has been proven to be ineffective due to heterogeneity of cells within a tumor and development of drug resistance (17). Thus, novel compounds and innovative therapeutic combinations are needed for the treatment of breast cancer, particularly TNBC (18, 19).

Z285 is a member of the 1,4 naphthoquinones class of compounds that have been shown to have anticancer, antibacterial, and antimalarial function (20-22). Similarly, Z285 has demonstrated cytotoxic effects in androgen-dependent and -independent prostate cancer cell lines as well as BC cell lines (23, 24). 4-OHT is an active metabolite of tamoxifen, a drug routinely used as BC prophylaxis as well as treatment of ERα-positive BC (25, 26). Therefore, this study examines the use of 2,3-dichloro-5,8-dimethoxy-1,4-naphthoquinone (Z285) and 4-hydroxytamoxifen (4-OHT) alone or in combination as a novel therapeutic alternative for TNBC.

Materials and Methods

Materials. CellTiter 96® AQueous One Solution Cell Proliferation Assay was obtained from Promega (Madison, WI, USA) and DMSO was purchased from Sigma-Aldrich (St. Louis, MO, USA). 4-hydroxytamoxifen was acquired from Fisher Scientific (Hanover Park, IL, USA) and PBS from Gibco (Gaithersburg, MD, USA). 2,3-Dichloro-5,8-dimethoxy-1,4-naphthoquinone was synthesized in house (23). CM-H2DCFDA was purchased from Invitrogen (Carlsbad, CA, USA). All drugs were made up as 10 mM stock dissolved in DMSO.

Cell culture. Stock cultures of the human ERα-positive BC (MCF7) and TNBC (HCC1806 obtained from AA patient and MDA-MB 231, Hs578T both taken from EA patients) cell lines were obtained from the American Type Culture Collection (ATCC) (Rockville, MD, USA). The cells were grown in 75 cm3 flasks in RPMI-1640 from ATCC (Rockville, MD, USA) medium supplemented with 10% fetal bovine serum (FBS) obtained from ATCC (Rockville, MD, USA) and 1% penicillin/streptomycin from Gibco (Gaithersburg, MD, USA) and incubated in humidified atmosphere 5% CO2 at 37°C. Upon reaching 80-90% confluency, the cells were trypsinized, and quantified with T10 cell counter from Bio-Rad (Hercules, CA, USA). For all experiments, cells were starved by plating in phenol free RPMI 1640, 1% charcoal stripped FBS and 1% penicillin/streptomycin for 24 h to achieve cell cycle synchronization and limit estrogenic exposure. Drugs were diluted to appropriate concentrations in this media.

Cell proliferation. All cell lines were plated at 8×103 cells/well in 96-well plate. Cells were allowed to attach overnight in growth media. The media was aspirated, and cells were further incubated in starvation media for 24 h. Relevant concentrations of the compounds were diluted in starvation media.

Single drug: Cells were treated in a concentration- and time-dependent manner with Z285 and 4-OHT at 0.1, 0.2, 0.5, 1, 2, 5, 10, 20 and 50 μM for 24, 72 and 120 h, respectively.

Combinatorial drug treatment: Cells were treated with Z285 for final concentrations of 2 or 5 μM and 1, 3, 6, 12, 15 μM of 4-OHT for 24, 72 and 120 h.

At the end of the respective time periods, 20 μl MTS was added to all the wells for 2 h and read at 495 nm using Perkin Elmer Wallac Victor 3 1420 plate reader (Waltham, MA, USA).

Data analysis: Graphpad v8 was used to calculate the IC50 for each cell line with each compound and its combination through nonlinear regression analysis. Combinatorial synergy study. Cells were treated with Z285 with final concentrations of 1, 2, 4, 8, 16 μM and with 4-OHT 3, 6, 12, 24, 48 μM for 72 h. After 72 h, 20 μL of MTS was added to the wells for 2 hours and read at 495 nm using Perkin Elmer Wallac Victor 3 1420 plate reader (Waltham, MA, USA).

Data analysis: Synergistic analysis was performed using Synergyfinder®, utilizing the Bliss Independence Reference model.

ROS assay. According to the manufacturers guidelines (Invitrogen), media was aspirated, cells were then washed with room temperature PBS and incubated in 10 μM CM-H2DCFA for 45 min. The cells were additionally washed twice in PBS followed by treatment with Z285 at final concentrations of 2, 4, 8, and 16 μM and at 4-OHT 3, 6, 12 and 24 μM and their combination for 8 h. Plate was read at 492-495 nm excitation and 517-527 nm emission using Biotek Cytation 3 imaging reader (Winooski, VT, USA).

Data analysis: One-way Anova followed by post-hoc Dunnetts test compared each mean to the control (untreated cells incubated with dye) was used to determine significance.

Results

In this study, three TNBC cell lines and one ERα expressing cell line were evaluated to determine the efficacy of Z285 and 4OHT alone and in combination on cell proliferation.

Z285 treatment. The cell line which was most susceptible to Z285 was Hs578T at 24 and 120 h with an IC50 of 5.21 and 1.63 μM, respectively. At 72 h, HCC1806 showed the most sensitivity with an IC50 of 4.26 μM as shown in Table I. MCF7 was least susceptible to Z285 at 72 h and 120 h with IC50 values of 9.43 and 5.50 μM, whereas HCC1806 showed the least sensitivity at 24 h with, respectively; IC50 of 22 μM as shown in Figure 1A-C.

Figure 1.
Figure 1.

Cell viability assay of Z285 alone and 4-OHT alone treated cells at 24, 72 and 120 h. (A) 24 h Z285, (B) 72 h Z285, (C) 120 h Z285, (D) 24 h 4-OHT, (E) 72 h 4-OHT,(F) 120 h 4-OHT. After starving cells for 24 h, A-D were treated with 0.1-50 μM of Z285 and D-F were treated with 0.1-50 μM of 4-OHT. IC50 was calculated by non-linear regression for each cell line at every time point. Each group analysis was performed in triplicate.

View this table:
Table I.

IC50 values of cells treated with Z285 alone at 24, 72 and 120 h.

4-OHT treatment. MDA-MB-231 exhibited the highest susceptibility at 14.8, 4.83 and 2.65 μM for 24, 72 and 120 h, respectively as shown in Figure 1D-F. Whereas, the IC50 for HCC1806 decreased from 16.2 to 6.83 μM and Hs578T showed a reduction in the IC50 from 12.6 to 7.16 μM between 24 h and 120 h. Interestingly, MCF7 was least sensitive to 4-OHT at every time point reaching an IC50 of approximately 20 μM at 24 h and decreasing to 8.5 μM by 120 h as shown in Table II.

View this table:
Table II.

IC50 values of cells treated with 4-OHT alone at 24, 72 and 120 h.

Z285 and 4-OHT combination treatment. Each cell line demonstrated a reduction in cell proliferation following combination treatment. Z285 was given at 2 and 5 μM in combination with 4-OHT at concentrations between 1 and 30 μM (Figure 2). When compared to the IC50 of 4-OHT alone, combination treatment with Z285 and 4-OHT showed decrease in the IC50 for HCC1806, Hs578T and MCF7 at concentrations of Z285 2 and 5 μM and 5 μM Z285 for MDA-MB-231 (Table III). HCC1806 showed a 14% decrease in IC50 for at both concentrations of Z285 at 24 h. A further 39% reduction was observed at 2 μM of Z285 at 72 h and a 62 and 99% at 120 h was shown at 2 and 5 μM Z285 when compared to 4-OHT-treated cells, respectively. MDA-MB-231 demonstrated a 15 and 41% decrease in IC50 at 24 and 72 h respectively after 5 μM Z285 and 4-OHT combination when compared to 4-OHT alone. In Hs578T, the IC50 decreased by 48, 42 and 56% for 2 μM combination at 24, 72 and 120 h, respectively. Furthermore, a 92, 98 and 99% decrease in IC50 was observed with 5 μM combination at 24, 72 and 120 h, respectively. MCF7 showed approximately 33% decrease in IC50 for all time points in 2 μM combination while at 5 μM combination a 95% decrease in IC50 was seen at all times. It should be noted that the combination treatment at 2 μM for MDA-MB-231 showed an increase in the IC50 values when compared with 4-OHT by itself there was a 225, 165 and 188% increase in IC50 at 24, 72 and 120 h, respectively.

Figure 2.
Figure 2.

Cell viability assay of cells treated with Z285 and 4-OHT at 24, 72 and 120 h. After starving cells for 24 h. All cells were treated with either 2 or 5 μM of Z285 and 1-15 μM of 4-OHT combined. Column 1 is 24 h, Column 2 is 72 h and column 3 is 120 h (A-C) are HCC1806, (D-F) are MDA-MB-231, (G-I) are Hs578T and (J-L) are MCF7. Non-linear regression is perfored on every cell line at every time point. Each group analysis was performed in triplicate.

View this table:
Table III.

Percentage change from 4-OHT treated cells alone.

Combinatorial analysis. Analysis of drug combination by Synergyfinder® indicated Bliss δ scores of 0.9, 4.9, and 5.6 for HCC1806, MCF7 and Hs578T respectively, thereby showing an additive effect for decreased cell proliferation. MDA-MB-231 showed a score of -10 indicating an antagonistic effect (Figure 3). Bliss independence reference model in this software compares the observed versus predicted inhibition response and where less than -10 is considered antagonistic, between -10 and 10 is considered to be additive and above 10 is synergistic.

Figure 3.
Figure 3.

Combinatorial analysis of cell lines treated with Z285 and 4-OHT. (A) HCC1806, (B) MDA-MB-231, (C) Hs578T, (D) MCF7. Synergyfinder using Bliss Independence reference model determined that an additive effect was produced with δ scores of HCC1806, Hs578T and MCF7 and MDA-MB-231 treated cells resulted with an antagonsitic effect.

ROS generation. Z285 demonstrated a significant increase in oxidative stress in Hs78T, MCF7 and MDA-MB-231 at 8 and 16 μM after 8 h exposure. Hs578T demonstrated the most significant increases in ROS with p-value ≤0.0001 at both 8 and 16 μM (Figure 4C). MDA-MB-231 and MCF7 showed p-values of ≤0.01 and ≤0.0001 at 8 and 16 μM, shown respectively in Figure 4B and D. HCC1806 showed a trend increase in ROS levels without significance. HCC1806 treated with 4-OHT produced a significant increase in ROS levels at 24 μM with a p-value of ≤0.05. The other cell lines treated with 4-OHT showed no significant changes in ROS production (Figure 5A-D).

Figure 4.
Figure 4.

ROS assay of cells treated with Z285. (A) HCC1806, (B) MDA-MB-231, (C) Hs578T, (D) MCF7. Cells were washed with PBS after starving for 24h. A total of 10 μM CM-H2DCFA was added for 45 min, then the cells were washed with PBS twice before treatments were added. All cell lines were treated with Z285 at 2, 4, 8, and 16 μM for 8 h. One-way ANOVA followed by post-hoc Dunnetts test comparing each mean to the control (untreated cells with incubated with dye) was used to determine significance. Each group was performed in triplicate. **p≤0.01, ****p≤0.0001.

Figure 5.
Figure 5.

ROS assay of cells treated with 4-OHT. (A) HCC1806, (B) MDA-MB-231, (C) Hs578T, (D) MCF7. Cells were washed with PBS after starving for 24 h. A total of 10 μM CM-H2DCFA was added for 45 min, then the cells were washed with PBS twice before treatments were added. A-D were treated with 3, 6, 12 and 24 μM for 8 h. One-way ANOVA followed by post-hoc Dunnetts test comparing each mean to the control (untreated cells with incubated with dye) was used to determine significance. Each group analysis was performed in triplicate, *p≤0.05.

When Z285 and 4-OHT were combined, MDA-MB-231 and MCF7 showed some combinations with significant increases in ROS production. In comparison to the MDA-MB-231 control, 16 μM Z285 and 6 μM 4-OHT combination caused an increase in ROS with a statistical significance of p≤0.01. MCF7 demonstrated significant increases in ROS levels at 4 μM Z285 and 6 μM, 8 μM Z285 and 3 μM 4-OHT and 8 μM Z285 and 6 μM 4-OHT with p-values of ≤0.05, ≤0.01, ≤0.05, respectively. No statistical changes in ROS was observed in HCC1806 and MCF7 (Figure 6).

Figure 6.
Figure 6.

ROS assay of combination treatment with Z285 and 4-OHT. (A) HCC1806, (B) MDA-MB-231, (C) Hs578T, (D) MCF7. Cells were washed with PBS after starving for 24 h. 10 μM CM-H2DCFA was added for 45 min, then the cells were washed with PBS twice before treatments were added. A-D were treated with a combintion of Z285 at 2, 4, 8, and 16 μM and 3, 6, 12 and 24 μM for 8 h. One-way ANOVA followed by post-hoc Dunnetts test comparing each mean to the control (untreated cells with incubated with dye) was used to determine significance. Each group was performed in triplicate. *p≤0.05, **p≤0.01.

Discussion

TNBC loss of ERα, PR and HER2 receptors make it difficult to treat due to lack of receptor targets. Though treatment options for TNBC have improved in recent years with targeted therapy such as PARP and topoisomerase I, there is still a significant number of patients who are unresponsive to these drugs (27, 28). Data show a 73% five-survival rate of TNBC to a 96% five-survival rate for non-TNBC counterparts. This is based on the grade of tumor, stage of cancer, age of patient, and overall health status. Stage IV diagnoses of TNBC has a general survival rate as low as 26.7% (29, 30).

This disease disproportionately effects premenopausal AA women, with twice as many AA women being diagnosed with this subtype when compared to EA women. Up to 40% of BC diagnoses in premenopausal AA women can be attributed to TNBC (31). In comparison to EA women, AA women demonstrate enhanced genetic risk factors like BRCA1, Aurora A and B, EZH2 and p53 mutations; as well as, increased rates of obesity and lower socioeconomic factors (32). TNBC in young women is more likely to be of a more aggressive subtype, and is more likely to present at an advanced stage, either because of its biological aggressive nature or because of delayed diagnosis (33). Young age was seen as an independent prognostic factor. According to these findings, patients diagnosed with BC at ≤35 years of age had a worse prognosis compared to premenopausal women above this age (34). Therefore, it is essential that innovative therapies are presented to increase the survivability of diagnosed patients.

This study investigated the efficacy of Z285 and 4-OHT as possible therapy for TNBC. Z285, is a 1,4 naphthoquinone with many therapeutic effects including antibacterial, antifungal, anti-inflammatory, antiviral and antitumor, specifically in prostate and breast cancer cell lines (35). In our previous study, it was shown that this compound causes inhibition of topoisomerase I, an enzyme responsible for producing single-strand breakage and relegation by unwinding supercoiled DNA to allow DNA replication and transcription. Thus inhibition of this enzyme can lead to apoptosis in BC cells (24, 36). Also, it significantly increases retinoblastoma, a tumor suppressor, levels in these cells. The cell proliferation inhibitory effects of Z285 has been previously observed in TNBC, ERα positive and androgen-dependent and - independent prostate cancer cell lines. The compound was observed to cause cell-cycle arrest in the S phase in all BC cell lines as well as androgen-independent prostate cancer cell lines (23, 24).

In the present investigation, four BC cell lines were used including HCC1806, Hs578T, MDA-MB-231and MCF7. HCC1806 was used specifically to evaluate an AA TNBC cell line in comparison to EA cells. As described by Lehmann et al., TNBC can be subdivided into seven categories: basal-like 1 (BL1), basal-like (BL2), Mesenchymal (M), Mesenchymal stem-like (MSL), immunomodulatory (IM), luminal androgen receptor (LAR) and unstable (UNS) (9). BL1 and BL2 are described as basal-like with BL1 exhibiting greater DNA damage response and cell-cycle gene expression and BL2 is enriched in growth factor signaling and myoepithelial markers. Whereas LAR, expresses a 9-fold increase of AR expression compared to other subtypes and has luminal gene expression. M shows increased gene expression of epithelial-mesenchymal-transition and growth factor pathways. MSL though similar to M shows reduced expression of proliferative genes. IM has immune signaling transduction pathways most likely due to a mixture of tumor cells and infiltrating lymphocytes. UNS tumors do not fall into any of the aforementioned categories. Thus, HCC1806 is classified as BL2 and MDA-MB-231 and Hs578T are categorized as MSL (9).

The evaluation did corroborate prior results as well as demonstrate the compounds ability to decrease cell proliferation in the multiple TNBC cell lines. Prior data indicate topoisomerase I inhibition as a mechanism for inhibition of cell viability, it is important to note that other mechanisms can be suggested for this compound’s action especially as the androgen dependent cells were not arrested in the S-phase similar to the other cell lines. Further, topoisomerase II is responsible for recombination, the separation of daughter chromosomes, and proper chromosome structure, condensation, and decondensation and inhibition of this enzyme is associated with other compounds in this class (37).

It may be suggested that BC cells treated with Z285 in the current study causes an increased generation of ROS resulting in alterations in cell signaling leading to cell damage thereby causing decreased cell proliferation. This cellular damage could be caused by hydroxyl radicals binding to cysteine-rich proteins and lipids, resulting in lipid peroxidation of cellular membrane and leading to apoptosis (38-42).

Concentration-response of the cell lines with 4-OHT produced interesting results with MCF7 in that they were the least sensitive to the drug as compared to the TNBC cell lines. These cell lines do not express the ERα target commonly associated with this drug so they should not be more susceptible to 4-OHT. Studies by Lin et al., (39) and Yaacob and Ismail (40) corroborated the MCF data from the current study in that high concentrations above 10 μM of 4-OHT failed to produce a 50% reduction in cell proliferation in MCF7 cells.

Tamoxifen and its active metabolites, endoxifen and 4-OHT are ligands for ERα; as well as, ERβ, GPER1, Estrogen Related Receptor β and Estrogen Related Receptor γ (43-45). 4-OHT has a similar relative binding affinities (RBA) to both ERα and Erβ (46) when compared to tamoxifen. On its own, 4-OHT decreased proliferation in MCF7 as expected but it also decreased proliferation in all three TNBC cell lines with greater sensitivity. Studies by Manna and Holz showed that 5-10% of ERα-negative cells are susceptible to tamoxifen (47). This can be attributed to the varying levels of expression of ERβ in these cell lines (48-51). 4-OHT is an agonist for ERβ inhibiting cell proliferation, migration, and invasion in TNBC cell lines (52). ERs have ER/ligand independent activity that can lead to activation of cytoplasmic proteins or phosphorylation of transcription factors (53).

Synergyfinder® using Bliss independence reference model was used to identify the relationship between the two compounds when combined (54). The effects of the drug combination showed an additive relationship in decreasing cell proliferation in HCC1806, Hs578T and MCF7. The additive relationship demonstrated in these cell lines maybe due to the changes in ROS production or DNA damage caused by Z285 thus increasing the susceptibility of the cells to 4-OHT. Though this combination demonstrates additivity in most of these cell lines, the methods of cell death may vary.

MDA-MB-231 demonstrated an antagonistic response with the compound combination. Lin et al., also observed some antagonistic responses when treating this cell line with shikonin and 4-OHT, shikonin being a naphthoquinone (55). This response may indicate a functional independence of the two compounds on cell proliferation. MDA-MB-231 cells have hypermethylation of CpG island in the promoter region of ESR1 thus effectively silencing the gene (56). Moreover, it has been proposed that the loss of ERα expression is due to the hyperactivation of MAPK (57, 58). Therefore, ROS production may modulate MAPK thus altering ERα expression in the other cell lines, but this would be ineffective in MDA-MB-231 (59).

CM-H2DCFDA indirectly reacts with H2O2 to produce a fluorescent molecule that is used to measure ROS levels (60). The increase in oxidative stress after 8 h corresponds to the decrease in cell proliferation seen at 24 h with HCC1806 being the least responsive and Hs578T showing increased susceptibility to Z285. It has been shown that 1,4 naphthoquinone derivatives can increase ROS levels and modulate the three major MAPK pathways ERK, JNK and p38 as well as the PI3K/AKT and JAK/STAT3 (61-64). These cellular stressors can cause a reduction in cell proliferation and an induction of apoptosis. In the current study, treatment with 4-OHT produced an increased trend in ROS production, whereas, at high concentration there was a slight decrease in ROS levels in MDA-MB-231 and Hs578T. Bekele et al., reported that incubation of MCF7 at 24h shows a significant increase in ROS (65). Therefore, a longer incubation period maybe required to achieve statistically significant increases in ROS production in the other cell lines. The combination treatment of the two compounds demonstrated an increase trend in the ROS production in HCC1806 and Hs578T.

The additive effect observed in the synergy analysis maybe due to other mechanisms independent of increased ROS generation. Kawiak et al., suggested that glucose regulated protein 78 (GRP78) down-regulation and Bcl-2-interacting killer (Bik) up-regulation by plumbagin was shown to increase the sensitivity of MCF7 and T47D to tamoxifen. Bik is a proapoptotic protein and increased Bik forms a complex with Bcl-2 on the endoplasmic reticulum activating apoptotic process (66). In addition, the activation of c-jun by JNK signaling is needed for 4-OHT induced cell death and 1,4 napthoquinones have demonstrated an increase in JNK activation and thus potentially enhancing the effect when the compounds are combined (67, 68).

Future studies with an expanded number of AA TNBC cell lines would be needed to improve comparison between the two ethnicities. Also, expansion into increased molecular subtypes of TNBC cell lines (i.e. LAR and BL1) would further the knowledge of the efficacy of Z285 and 4OH-T combination for all TNBC. This information may be translated into a molecular subytpe-specific therapeutic modality for TNBC.

Conclusion

The present study demonstrated a beneficial relationship between Z285 and 4-OHT. However, the mechanisms that are associated with the additive effect have not been fully elucidated. Therefore, combination of these two compounds may be an alternative therapy for TNBC patients who are unresponsive to other treatments.

Acknowledgements

This work was supported by funding from the Charles and Mary Latham Foundation Fund. The Authors would like to thank Dr. O. Bakare from the Department of Chemistry at Howard University for generously providing Z285.

Footnotes

  • Authors’ Contributions

    Experimental design was performed by AGJR and RLC. Experiments and statistical analysis were performed by AGJR. AGJR, YMK and RLC were responsible for manuscript writing and editing.

  • This article is freely accessible online.

  • Conflicts of Interest

    The Authors have no conflicts of interest to declare.

  • Received October 1, 2020.
  • Revision received October 26, 2020.
  • Accepted November 1, 2020.

References

  1. ↵
    1. Singh J,
    2. Asad S,
    3. Zhang Y,
    4. Nock W,
    5. Adams E,
    6. Damicis A,
    7. Ramaswamy B,
    8. Williams N,
    9. Parsons HA,
    10. Adalsteinsson VA,
    11. Winer EP,
    12. Lin NU,
    13. Partridge AH,
    14. Overmoyer B and
    15. Stover DG
    : Aggressive subsets of metastatic triple negative breast cancer. Clin Breast Cancer 20: e20-e26, 2020. PMID: 31631016. DOI: 10.1016/j.clbc.2019.06.012
    OpenUrlCrossRef
  2. ↵
    1. Purrington KS,
    2. Knight J,
    3. Dyson G,
    4. Ali-Fehmi R,
    5. Schwartz AG,
    6. Boerner JL and
    7. Bandyopadhyay S
    : CLCA2 expression is associated with survival among African American women with triple negative breast cancer. PLoS One 15: e0231712, 2020. PMID: 32298355. DOI: 10.1371/journal.pone.0231712
    OpenUrlCrossRef
  3. ↵
    1. Ma H,
    2. Ursin G,
    3. Xu X,
    4. Lee E,
    5. Togawa K,
    6. Duan L,
    7. Lu Y,
    8. Malone KE,
    9. Marchbanks PA,
    10. McDonald JA,
    11. Simon MS,
    12. Folger SG,
    13. Sullivan-Halley J,
    14. Deapen DM,
    15. Press MF and
    16. Bernstein L
    : Reproductive factors and the risk of triple-negative breast cancer in white women and African-American women: a pooled analysis. Breast Cancer Res 19: 6, 2017. PMID: 28086982. DOI: 10.1186/s13058-016-0799-9
    OpenUrlCrossRef
  4. ↵
    1. Dolle JM,
    2. Daling JR,
    3. White E,
    4. Brinton LA,
    5. Doody DR,
    6. Porter PL and
    7. Malone KE
    : Risk factors for triple-negative breast cancer in women under the age of 45 years. Cancer Epidemiol Biomarkers Prev 18: 1157-1166, 2009. PMID: 19336554. DOI: 10.1158/1055-9965.EPI-08-1005
    OpenUrlAbstract/FREE Full Text
  5. ↵
    1. Dietze EC,
    2. Sistrunk C,
    3. Miranda-Carboni G,
    4. O’Regan R and
    5. Seewaldt VL
    : Triple-negative breast cancer in African-American women: disparities versus biology. Nat Rev Cancer 15: 248-254, 2015. PMID: 25673085. DOI: 10.1038/nrc3896
    OpenUrlCrossRefPubMed
  6. ↵
    1. Reddy SM,
    2. Barcenas CH,
    3. Sinha AK,
    4. Hsu L,
    5. Moulder SL,
    6. Tripathy D,
    7. Hortobagyi GN and
    8. Valero V
    : Long-term survival outcomes of triple-receptor negative breast cancer survivors who are disease free at 5 years and relationship with low hormone receptor positivity. Br J Cancer 118: 17-23, 2018. PMID: 29235566. DOI: 10.1038/bjc.2017.379
    OpenUrlCrossRef
    1. James M,
    2. Dixit A,
    3. Robinson B,
    4. Frampton C and
    5. Davey V
    : Outcomes for Patients with Non-metastatic Triple-negative breast cancer in New Zealand. Clin Oncol (R Coll Radiol) 31: 17-24, 2019. PMID: 30274766. DOI: 10.1016/j.clon.2018.09.006
    OpenUrlCrossRef
  8. ↵
    1. Doepker MP,
    2. Holt SD,
    3. Durkin MW,
    4. Chu CH and
    5. Nottingham JM
    : Triple-negative breast cancer: A comparison of race and survival. Am Surg 84: 881-888, 2018. PMID: 29981619. DOI: 10.1177/000313481808400636
    OpenUrlCrossRef
  9. ↵
    1. Lehmann BDB,
    2. Bauer J a J,
    3. Chen X,
    4. Sanders ME,
    5. Chakravarthy a B,
    6. Shyr Y and
    7. Pietenpol J a
    : Identification of human triple-negative breast cancer subtypes and preclinical models for selection of targeted therapies. J Clin Invest 121: 2750-2767, 2011. PMID: 21633166. DOI: 10.1172/JCI45014DS1
    OpenUrlCrossRefPubMed
  10. ↵
    1. Uscanga-Perales GI,
    2. Santuario-Facio SK and
    3. Ortiz-López R
    : Triple negative breast cancer: Deciphering the biology and heterogeneity. Med Univ 18: 105-114, 2016. DOI: 10.1016/j.rmu.2016.05.007
    OpenUrlCrossRef
  11. ↵
    1. Yadav BS,
    2. Sharma SC,
    3. Chanana P and
    4. Jhamb S
    : Systemic treatment strategies for triple-negative breast cancer. World J Clin Oncol 5: 125-133, 2014. PMID: 24829859. DOI: 10.5306/wjco.v5.i2.125
    OpenUrlCrossRefPubMed
  12. ↵
    1. Anders CK,
    2. Winer EP,
    3. Ford JM,
    4. Dent R,
    5. Silver DP,
    6. Sledge GW and
    7. Carey LA
    : Poly(ADP-ribose) polymerase inhibition: “Targeted” therapy for triple-negative breast cancer. Clin Cancer Res 16: 4702-4710, 2010. PMID: 20858840. DOI: 10.1158/1078-0432.CCR-10-0939
    OpenUrlAbstract/FREE Full Text
  13. ↵
    1. Ellsworth DL,
    2. Turner CE and
    3. Ellsworth RE
    : A review of the hereditary component of triple negative breast cancer: High- and moderate-penetrance breast cancer genes, low-penetrance loci, and the role of nontraditional genetic elements. J Oncol 2019: 4382606, 2019. PMID: 31379942. DOI: 10.1155/2019/4382606
    OpenUrlCrossRef
  14. ↵
    1. Cyprian FS,
    2. Akhtar S,
    3. Gatalica Z and
    4. Vranic S
    : Targeted immunotherapy with a checkpoint inhibitor in combination with chemotherapy: A new clinical paradigm in the treatment of triple-negative breast cancer. Bosn J Basic Med Sci 19: 227-233, 2019. PMID: 30915922. DOI: 10.17305/bjbms.2019.4204
    OpenUrlCrossRef
    1. Marra A,
    2. Viale G and
    3. Curigliano G
    : Recent advances in triple negative breast cancer: the immunotherapy era. BMC Med 17: 90, 2019. PMID: 31068190. DOI: 10.1186/s12916-019-1326-5
    OpenUrlCrossRef
  16. ↵
    1. Bardia A,
    2. Mayer IA,
    3. Vahdat LT,
    4. Tolaney SM,
    5. Isakoff SJ,
    6. Diamond JR,
    7. O’Shaughnessy J,
    8. Moroose RL,
    9. Santin AD,
    10. Abramson VG,
    11. Shah NC,
    12. Rugo HS,
    13. Goldenberg DM,
    14. Sweidan AM,
    15. Iannone R,
    16. Washkowitz S,
    17. Sharkey RM,
    18. Wegener WA and
    19. Kalinsky K
    : Sacituzumab govitecan-hziy in refractory metastatic triple-negative breast cancer. N Engl J Med 380: 741-751, 2019. PMID: 30786188. DOI: 10.1056/NEJMoa1814213
    OpenUrlCrossRef
  17. ↵
    1. Palmer AC and
    2. Sorger PK
    : Combination cancer therapy can confer benefit via patient-to-patient variability without drug additivity or synergy. Cell 171: 1678-1691.e13, 2017. PMID: 29245013. DOI: 10.1016/j.cell.2017.11.009
    OpenUrlCrossRefPubMed
  18. ↵
    1. Isakoff SJ
    : Triple Negative Breast Cancer: Role of specific chemotherapy agents. cancer J 16: 53-61, 2010. PMID: 20164691. DOI: 10.1097/PPO.0b013e3181d24ff7.Triple
    OpenUrlCrossRefPubMed
  19. ↵
    1. Bayat Mokhtari R,
    2. Homayouni TS,
    3. Baluch N,
    4. Morgatskaya E,
    5. Kumar S,
    6. Das B and
    7. Yeger H
    : Combination therapy in combating cancer. Oncotarget 8: 38022-38043, 2017. PMID: 28410237. DOI: 10.18632/oncotarget.16723
    OpenUrlCrossRefPubMed
  20. ↵
    1. Ravichandiran P,
    2. Sheet S,
    3. Premnath D,
    4. Kim AR and
    5. Yoo DJ
    : 1,4-naphthoquinone analogues: Potent antibacterial agents and mode of action evaluation. Molecules 24: 1437, 2019. PMID: 30979056. DOI: 10.3390/molecules24071437
    OpenUrlCrossRef
    1. Verma R
    : Anti-cancer activities of 1,4-naphthoquinones: A QSAR study. Anticancer Agents Med Chem 6: 489-499, 2006. PMID: 17017857. DOI: 10.2174/187152006778226512
    OpenUrlCrossRefPubMed
  22. ↵
    1. Belorgey D,
    2. Lanfranchi DA and
    3. Davioud-Charvet E
    : 1,4-naphthoquinones and other NADPH-dependent glutathione reductase-catalyzed redox cyclers as antimalarial agents. Curr Pharm Des 19: 2512-28, 2013. PMID: 23116403. DOI: 10.2174/1381612811319140003
    OpenUrlCrossRefPubMed
  23. ↵
    1. Copeland RL,
    2. Das JR,
    3. Bakare O,
    4. Enwerem NM,
    5. Berhe S,
    6. Hillaire K,
    7. White D,
    8. Beyene D,
    9. Kassim OO and
    10. Kanaan YM
    : Cytotoxicity of 2,3-dichloro-5,8-dimethoxy-1,4-naphthoquinone in androgen-dependent and -independent prostate cancer cell lines. Anticancer Res 27: 1537-1546, 2007. PMID: 17595773.
    OpenUrlAbstract/FREE Full Text
  24. ↵
    1. Kanaan YM,
    2. Das JR,
    3. Bakare O,
    4. Enwerem NM,
    5. Berhe S,
    6. Beyene D,
    7. Williams V,
    8. Zhou Y and
    9. Copeland RL
    : Biological evaluation of 2,3-dichloro-5,8-dimethoxy-1,4-naphthoquinone as an anti-breast cancer agent. Anticancer Res 29: 191-199, 2009. PMID: 19331150.
    OpenUrlAbstract/FREE Full Text
  25. ↵
    1. Nazarali SA and
    2. Narod SA
    : Tamoxifen for women at high risk of breast cancer. Breast Cancer (Dove Med Press) 6: 29-36, 2014. PMID: 24648767. DOI: 10.2147/BCTT.S43763
    OpenUrlCrossRef
  26. ↵
    1. Cuzick J,
    2. Forbes JF,
    3. Sestak I,
    4. Cawthorn S,
    5. Hamed H,
    6. Holli K,
    7. Howell A and 5International Breast Cancer Intervention Study I Investigators
    : Long-term results of tamoxifen prophylaxis for breast cancer—96-month follow-up of the randomized IBIS-I trial. J Natl Cancer Inst 99: 272-282, 2007. PMID: 17312304. DOI: 10.1093/jnci/djk049
    OpenUrlCrossRefPubMed
  27. ↵
    1. Shao B,
    2. Li C-W,
    3. Lim S-O,
    4. Sun L,
    5. Lai Y-J,
    6. Hou J,
    7. Liu C,
    8. Chang C-W,
    9. Qiu Y,
    10. Hsu J-M,
    11. Chan L-C,
    12. Zha Z,
    13. Li H and
    14. Hung M-C
    : Deglycosylation of PD-L1 by 2-deoxyglucose reverses PARP inhibitor-induced immunosuppression in triple-negative breast cancer. Am J Cancer Res 8: 1837-1846, 2018. PMID: 30323975.
    OpenUrl
  28. ↵
    1. D’Andrea AD
    : Mechanisms of PARP inhibitor sensitivity and resistance. DNA Repair (Amst) 71: 172-176, 2018. PMID: 30177437. DOI: 10.1016/j.dnarep.2018.08.021
    OpenUrlCrossRef
  29. ↵
    1. Urru SAM,
    2. Gallus S,
    3. Bosetti C,
    4. Moi T,
    5. Medda R,
    6. Sollai E,
    7. Murgia A,
    8. Sanges F,
    9. Pira G,
    10. Manca A,
    11. Palmas D,
    12. Floris M,
    13. Asunis AM,
    14. Atzori F,
    15. Carru C,
    16. D’Incalci M,
    17. Ghiani M,
    18. Marras V,
    19. Onnis D,
    20. Santona MC,
    21. Sarobba G,
    22. Valle E,
    23. Canu L,
    24. Cossu S,
    25. Bulfone A,
    26. Rocca PC,
    27. De Miglio MR and
    28. Orrù S
    : Clinical and pathological factors influencing survival in a large cohort of triple-negative breast cancer patients. BMC Cancer 18: 56, 2018. PMID: 29310602. DOI: 10.1186/s12885-017-3969-y
    OpenUrlCrossRef
  30. ↵
    1. Podo F,
    2. Santoro F,
    3. Di Leo G,
    4. Manoukian S,
    5. de Giacomi C,
    6. Corcione S,
    7. Cortesi L,
    8. Carbonaro LA,
    9. Trimboli RM,
    10. Cilotti A,
    11. Preda L,
    12. Bonanni B,
    13. Pensabene M,
    14. Martincich L,
    15. Savarese A,
    16. Contegiacomo A and
    17. Sardanelli F
    : Triple-negative versus nontriple-negative breast cancers in high-risk women: Phenotype features and survival from the HIBCRIT-1 MRI-including screening study. Clin Cancer Res 22: 895-904, 2016. PMID: 26503945. DOI: 10.1158/1078-0432.CCR-15-0459
    OpenUrlAbstract/FREE Full Text
  31. ↵
    1. Lindner R,
    2. Sullivan C,
    3. Offor O,
    4. Lezon-Geyda K,
    5. Halligan K,
    6. Fischbach N,
    7. Shah M,
    8. Bossuyt V,
    9. Schulz V,
    10. Tuck DP and
    11. Harris LN
    : Molecular phenotypes in triple negative breast cancer from African American patients suggest targets for therapy. PLoS One 8: e71915, 2013. PMID: 24260093. DOI: 10.1371/journal.pone.0071915
    OpenUrlCrossRefPubMed
  32. ↵
    1. Siddharth S and
    2. Sharma D
    : Racial disparity and triple-negative breast cancer in African-American women: A multifaceted affair between obesity, biology, and socioeconomic determinants. Cancers (Basel) 10: 514, 2018. PMID: 30558195. DOI: 10.3390/cancers10120514
    OpenUrlCrossRef
  33. ↵
    1. Dubsky PC,
    2. Gnant MFX,
    3. Taucher S,
    4. Roka S,
    5. Kandioler D,
    6. Pichler-Gebhard B,
    7. Agstner I,
    8. Seifert M,
    9. Sevelda P and
    10. Jakesz R
    : Young age as an independent adverse prognostic factor in premenopausal patients with breast cancer. Clin Breast Cancer 3: 65-72, 2002. PMID: 12020397. DOI: 10.3816/CBC.2002.n.013
    OpenUrlCrossRefPubMed
  34. ↵
    1. Owrang M,
    2. Copeland RL,
    3. Ricks-Santi LJ,
    4. Gaskins M,
    5. Beyene D,
    6. Dewitty RL and
    7. Kanaan YM
    : Breast cancer prognosis for young patients. In Vivo 31: 661-668. PMID: 28652435. DOI: 10.21873/invivo.11109
    OpenUrlCrossRef
  35. ↵
    1. Kanaan YM,
    2. White DF,
    3. Das JR,
    4. Berhe S,
    5. Bakare O,
    6. Kenguele H,
    7. Beyene D,
    8. Zhou Y,
    9. Day AA and
    10. Copeland RL
    : Cytotoxic effects of N-(3-chloro-1,4-dioxo 1,4-dihydro-naphthalen-2-yl)-benzamide on androgen-dependent and -independent prostate cancer cell lines. Anticancer Res 30: 519-527, 2010. PMID: 20332464.
    OpenUrlAbstract/FREE Full Text
  36. ↵
    1. Li M and
    2. Liu Y
    : Topoisomerase I in human disease pathogenesis and treatments. genomics proteomics bioinformatics 14: 166-171, 2016. PMID: 27181710. DOI: 10.1016/j.gpb.2016.02.004
    OpenUrlCrossRef
  37. ↵
    1. McClendon AK and
    2. Osheroff N
    : DNA topoisomerase II, genotoxicity, and cancer. Mutat Res 623: 83-97, 2007. PMID: 17681352. DOI: 10.1016/j.mrfmmm.2007.06.009
    OpenUrlCrossRefPubMed
  38. ↵
    1. Klaus V,
    2. Hartmann T,
    3. Gambini J,
    4. Graf P,
    5. Stahl W,
    6. Hartwig A and
    7. Klotz L-O
    : 1,4-Naphthoquinones as inducers of oxidative damage and stress signaling in HaCaT human keratinocytes. Arch Biochem Biophys 496: 93-100, 2010. PMID: 20153715. DOI: 10.1016/j.abb.2010.02.002
    OpenUrlCrossRefPubMed
  39. ↵
    1. Coelho-Cerqueira E,
    2. Netz PA,
    3. do Canto VP,
    4. Pinto AC and
    5. Follmer C
    : Beyond topoisomerase inhibition: antitumor 1,4-naphthoquinones as potential inhibitors of human monoamine oxidase. Chem Biol Drug Des 83: 401-410, 2014. PMID: 24165164. DOI: 10.1111/cbdd.12255
    OpenUrlCrossRef
  40. ↵
    1. Widhalm JR and
    2. Rhodes D
    : Biosynthesis and molecular actions of specialized 1,4-naphthoquinone natural products produced by horticultural plants. Hortic Res 3: 16046, 2016. PMID: 27688 890. DOI: 10.1038/hortres.2016.46
    OpenUrlCrossRefPubMed
    1. Barrera G
    : Oxidative stress and lipid peroxidation products in cancer progression and therapy. ISRN Oncol 2012: 137289, 2012. PMID: 23119185. DOI: 10.5402/2012/137289
    OpenUrlCrossRefPubMed
  42. ↵
    1. Schieber M and
    2. Chandel NS
    : ROS function in redox signaling and oxidative stress. Curr Biol 24: R453-462, 2014. PMID: 24845678. DOI: 10.1016/j.cub.2014.03.034
    OpenUrlCrossRefPubMed
  43. ↵
    1. Li Y,
    2. Chen Y,
    3. Zhu Z-X,
    4. Liu X-H,
    5. Yang L,
    6. Wan L,
    7. Lei T-W and
    8. Wang X-D
    : 4-Hydroxytamoxifen-stimulated processing of cyclin E is mediated via G protein-coupled receptor 30 (GPR30) and accompanied by enhanced migration in MCF-7 breast cancer cells. Toxicology 309: 61-65, 2013. PMID: 23624423. DOI: 10.1016/j.tox.2013.04.012
    OpenUrlCrossRefPubMed
    1. Tremblay GB,
    2. Bergeron D and
    3. Giguere V
    : 4-Hydroxytamoxifen is an isoform-specific inhibitor of orphan estrogen-receptor-related (ERR) nuclear receptors beta and gamma. Endocrinology 142: 4572-4575, 2001. PMID: 11564725. DOI: 10.1210/endo.142.10.8528
    OpenUrlCrossRefPubMed
  45. ↵
    1. Coward P,
    2. Lee D,
    3. Hull MV and
    4. Lehmann JM
    : 4-Hydroxytamoxifen binds to and deactivates the estrogen-related receptor gamma. Proc Natl Acad Sci USA 98: 8880-8884, 2001. PMID: 11447273. DOI: 10.1073/pnas.151244398
    OpenUrlAbstract/FREE Full Text
  46. ↵
    1. Weatherman RV,
    2. Clegg NJ and
    3. Scanlan TS
    : Differential SERM activation of the estrogen receptors (ERalpha and ERbeta) at AP-1 sites. Chem Biol 8: 427-436, 2001. PMID: 11358690. DOI: 10.1016/s1074-5521(01)00025-4
    OpenUrlCrossRefPubMed
  47. ↵
    1. Manna S and
    2. Holz MK
    : Tamoxifen action in ER-negative breast cancer. Sign Transduct Insights 5: 1-7, 2016. PMID: 26989346. DOI: 10.4137/STI.S29901
    OpenUrlCrossRef
  48. ↵
    1. Al-Bader M,
    2. Ford C,
    3. Al-Ayadhy B and
    4. Francis I
    : Analysis of estrogen receptor isoforms and variants in breast cancer cell lines. Exp Ther Med 2: 537-544, 2011. PMID: 22977537. DOI: 10.3892/etm.2011.226
    OpenUrlCrossRefPubMed
    1. Hinsche O,
    2. Girgert R,
    3. Emons G and
    4. Gründker C
    : Estrogen receptor β selective agonists reduce invasiveness of triple-negative breast cancer cells. Int J Oncol 46: 878-884, 2015. PMID: 25420519. DOI: 10.3892/ijo.2014.2778
    OpenUrlCrossRefPubMed
    1. Schüler-Toprak S,
    2. Häring J,
    3. Inwald EC,
    4. Moehle C,
    5. Ortmann O and
    6. Treeck O
    : Agonists and knockdown of estrogen receptor β differentially affect invasion of triple-negative breast cancer cells in vitro. BMC Cancer 16: 951, 2016. PMID: 28003019. DOI: 10.1186/s12885-016-2973-y
    OpenUrlCrossRef
  51. ↵
    1. Rizza P,
    2. Barone I,
    3. Zito D,
    4. Giordano F,
    5. Lanzino M,
    6. De Amicis F,
    7. Mauro L,
    8. Sisci D,
    9. Catalano S,
    10. Dahlman Wright K,
    11. Gustafsson J and
    12. Andò S
    : Estrogen receptor beta as a novel target of androgen receptor action in breast cancer cell lines. Breast Cancer Res 16: R21, 2014. PMID: 24552459. DOI: 10.1186/bcr3619
    OpenUrlCrossRefPubMed
  52. ↵
    1. Austin D,
    2. Hamilton N,
    3. Elshimali Y,
    4. Pietras R,
    5. Wu Y and
    6. Vadgama J
    : Estrogen receptor-beta is a potential target for triple negative breast cancer treatment. Oncotarget 9: 33912-33930, 2018. PMID: 30338035. DOI: 10.18632/oncotarget.26089
    OpenUrlCrossRef
  53. ↵
    1. Mun MJ,
    2. Kim J-H,
    3. Kim T-H,
    4. Hwang J-Y and
    5. Jang W-C
    : Associations between Estrogen Receptor Gene Polymorphisms and Endometriosis. J Korean Soc Menopause 19: 64, 2013. DOI: 10.6118/jksm.2013.19.2.64
    OpenUrlCrossRef
  54. ↵
    1. Ianevski A,
    2. He L,
    3. Aittokallio T and
    4. Tang J
    : SynergyFinder: a web application for analyzing drug combination dose-response matrix data. Bioinformatics 33: 2413-2415, 2017. PMID: 28379339. DOI: 10.1093/bioinformatics/btx162
    OpenUrlCrossRefPubMed
  55. ↵
    1. Lin H-Y,
    2. Han H-W,
    3. Wang Y-S,
    4. He D-L,
    5. Sun W-X,
    6. Feng L,
    7. Wen Z-L,
    8. Yang M-K,
    9. Lu G-H,
    10. Wang X-M,
    11. Qi J-L and
    12. Yang Y-H
    : Shikonin and 4-hydroxytamoxifen synergistically inhibit the proliferation of breast cancer cells through activating apoptosis signaling pathway in vitro and in vivo. Chin Med 15: 23, 2020. PMID: 32175001. DOI: 10.1186/s13020-020-00305-1
    OpenUrlCrossRef
  56. ↵
    1. Herman JG and
    2. Baylin SB
    : Gene silencing in cancer in association with promoter hypermethylation. N Engl J Med 349: 2042-2054, 2003. PMID: 14627790. DOI: 10.1056/NEJ Mra023075
    OpenUrlCrossRefPubMed
  57. ↵
    1. Bayliss J,
    2. Hilger A,
    3. Vishnu P,
    4. Diehl K and
    5. El-Ashry D
    : Reversal of the estrogen receptor-negative phenotype in breast cancer and restoration of antiestrogen response. Clin Cancer Res 13: 7029-7036, 2007. PMID: 18056179. DOI: 10.1158/1078-0432.CCR-07-0587
    OpenUrlAbstract/FREE Full Text
  58. ↵
    1. Oh AS,
    2. Lorant LA,
    3. Holloway JN,
    4. Miller DL,
    5. Kern FG and
    6. El-Ashry D
    : Hyperactivation of MAPK induces loss of ERalpha expression in breast cancer cells. Mol Endocrinol 15: 1344-1359, 2001. PMID: 11463858. DOI: 10.1210/mend.15.8.0678
    OpenUrlCrossRefPubMed
  59. ↵
    1. Sharma D,
    2. Saxena NK,
    3. Davidson NE and
    4. Vertino PM
    : Restoration of tamoxifen sensitivity in estrogen receptor-negative breast cancer cells: Tamoxifen-bound reactivated ER recruits distinctve corepressor complexes. Cancer Res 66: 6370-6378, 2006. PMID: 16778215. DOI: 10.1158/0008-5472.CAN-06-0402
    OpenUrlAbstract/FREE Full Text
  60. ↵
    1. Dikalov SI and
    2. Harrison DG
    : Methods for detection of mitochondrial and cellular reactive oxygen species. Antioxid Redox Signal 20: 372-382, 2014. PMID: 22978713. DOI: 10.1089/ars.2012.4886
    OpenUrlCrossRefPubMed
  61. ↵
    1. Son Y,
    2. Kim S,
    3. Chung H-T and
    4. Pae H-O
    : Reactive oxygen species in the activation of MAP kinases. Methods Enzymol 528: 27-48, 2013. PMID: 23849857. DOI: 10.1016/B978-0-12-405881-1.00002-1
    OpenUrlCrossRefPubMed
    1. Zhang J,
    2. Wang X,
    3. Vikash V,
    4. Ye Q,
    5. Wu D,
    6. Liu Y and
    7. Dong W
    : ROS and ROS-mediated cellular signaling. Oxid Med Cell Longev 2016: 4350965, 2016. PMID: 26998193. DOI: 10.1155/2016/4350965
    OpenUrlCrossRefPubMed
    1. Wen C,
    2. Wang H,
    3. Wu X,
    4. He L,
    5. Zhou Q,
    6. Wang F,
    7. Chen S,
    8. Huang L,
    9. Chen J,
    10. Wang H,
    11. Ye W,
    12. Li W,
    13. Yang X,
    14. Liu H and
    15. Peng J
    : ROS-mediated inactivation of the PI3K/AKT pathway is involved in the antigastric cancer effects of thioredoxin reductase-1 inhibitor chaetocin. Cell Death Dis 10: 809, 2019. PMID: 31649256. DOI: 10.1038/s41419-019-2035-x
    OpenUrlCrossRef
  64. ↵
    1. Kim J-H,
    2. Choi TG,
    3. Park S,
    4. Yun HR,
    5. Nguyen NNY,
    6. Jo YH,
    7. Jang M,
    8. Kim J,
    9. Kim J,
    10. Kang I,
    11. Ha J,
    12. Murphy MP,
    13. Tang DG and
    14. Kim SS
    : Mitochondrial ROS-derived PTEN oxidation activates PI3K pathway for mTOR-induced myogenic autophagy. Cell Death Differ 25: 1921-1937, 2018. PMID: 30042494. DOI: 10.1038/s41418-018-0165-9
    OpenUrlCrossRef
  65. ↵
    1. Bekele RT,
    2. Venkatraman G,
    3. Liu R-Z,
    4. Tang X,
    5. Mi S,
    6. Benesch MGK,
    7. Mackey JR,
    8. Godbout R,
    9. Curtis JM,
    10. McMullen TPW and
    11. Brindley DN
    : Oxidative stress contributes to the tamoxifen-induced killing of breast cancer cells: implications for tamoxifen therapy and resistance. Sci Rep 6: 21164, 2016. PMID: 26883574. DOI: 10.1038/srep21164
    OpenUrlCrossRef
  66. ↵
    1. Kawiak A,
    2. Domachowska A,
    3. Jaworska A and
    4. Lojkowska E
    : Plumbagin sensitizes breast cancer cells to tamoxifen-induced cell death through GRP78 inhibition and Bik upregulation. Sci Rep 7: 43781, 2017. PMID: 28287102. DOI: 10.1038/srep43781
    OpenUrlCrossRef
  67. ↵
    1. Madeo A,
    2. Vinciguerra M,
    3. Lappano R,
    4. Galgani M,
    5. Gasperi-Campani A,
    6. Maggiolini M and
    7. Musti AM
    : c-Jun activation is required for 4-hydroxytamoxifen-induced cell death in breast cancer cells. Oncogene 29: 978-991, 2010. PMID: 19935718. DOI: 10.1038/onc.2009.400
    OpenUrlCrossRefPubMed
  68. ↵
    1. Zhang Y,
    2. Luo Y-H,
    3. Piao X-J,
    4. Shen G-N,
    5. Wang J-R,
    6. Feng Y-C,
    7. Li J-Q,
    8. Xu W-T,
    9. Zhang Y,
    10. Zhang T,
    11. Wang C-Y and
    12. Jin C-H
    : The design of 1,4-naphthoquinone derivatives and mechanisms underlying apoptosis induction through ROS-dependent MAPK/Akt/STAT3 pathways in human lung cancer cells. Bioorg Med Chem 27: 1577-1587, 2019. PMID: 30846406. DOI: 10.1016/j.bmc.2019.03.002
    OpenUrlCrossRef
Back to top

In this issue

Print
Download PDF
Article Alerts
Email Article
Citation Tools
Reprints and Permissions
Combinatorial Cytotoxic Effects of 2,3-Dichloro-5,8-dimethoxy-1,4-naphthoquinone and 4-hydroxytamoxifen in Triple-negative Breast Cancer Cell Lines
ANASTASIA G.J. ROBINSON, YASMINE M. KANAAN, ROBERT L. COPELAND
Anticancer Research Dec 2020, 40 (12) 6623-6635; DOI: 10.21873/anticanres.14687
del.icio.us logo Digg logo Reddit logo Twitter logo Facebook logo Google logo Mendeley logo

Jump to section

Keywords