Research ArticleExperimental Studies

miR-3188 Enhances Sensitivity of Breast Cancer Cells to Ionizing Radiation by Down-regulating Rictor

SUNG-EUN HONG, HYEON-OK JIN, SEUNG-MI KIM, SE-KYEONG JANG, CHAN SUB PARK, MIN-KI SEONG, HYUN-AH KIM, WOO CHUL NOH and IN-CHUL PARK
Anticancer Research December 2021, 41 (12) 6169-6176; DOI: https://doi.org/10.21873/anticanres.15436

Abstract

Background/Aim: Rictor is an adaptor protein essential for mTORC2, which regulates cell growth and survival. The aim of this study was to identify microRNAs (miR) that down-regulate Rictor and investigate their function on breast cancer cell survival. Materials and Methods: Trypan blue assay, MTT assay, polymerase chain reaction analysis, luciferase reporter assay and western blot analysis were carried out in breast cancer cell lines HCC1954, MDA-MB-231, SK-BR-3, and BT474. Results: miR-3188 overexpression suppressed the expression of Rictor and inhibited cell viability in HCC1954 and MDA-MB-231, highly Rictor-expressing breast cancer cells. In addition, miR-3188 overexpression decreased the protein level of p-AKT at Ser473, a substrate of mTORC2. Moreover, miRNA-3188 overexpression sensitized breast cancer cells to ionizing radiation (IR) by down-regulating Rictor and p-AKT. Conclusion: miR-3188 enhances IR sensitivity by affecting the mTORC2/AKT signalling pathway by altering the expression of Rictor, which could be a promising therapeutic strategy for the future treatment of breast cancer.

Key Words:

Breast cancer is the most frequently diagnosed cancer, and its incidence is rapidly increasing in women worldwide (1). Despite significant advancements in the diagnosis and treatment of breast cancer, it remains the leading cause of death from cancer (1-3). Breast cancer is a heterogeneous disease, as many distinct genes are overexpressed and act as key players in its progression (4). Activation of the mechanistic target of rapamycin (mTOR) pathway has been estimated to be present in as many as 70% of all breast cancers, and pathway activation promotes tumour growth and progression (5-8). mTOR exists in two signalling complexes, mTORC1 and mTORC2, which are composed of distinct protein binding partners (9-11). mTORC1, which contains mTOR, Raptor, mLST8, and PRAS40, promotes cell growth and metabolism by phosphorylating S6K and 4EBP1 (9, 10, 12). mTORC2, which contains mTOR, Rictor, Sin1, and mLST8, is rapamycin-insensitive and has been reported to regulate cell proliferation and survival by phosphorylating AKT, SGK1, and PKCα (11). Rictor, a key component of mTORC2, has been found to be amplified in various cancers, including breast cancer (13-17), in which Rictor amplification is significantly related to poor prognosis and short survival (18-20). Genetic Rictor inhibition has been reported to eliminate mTORC2 signalling, block AKT Ser473 phosphorylation, and ultimately, decrease tumour cell survival (19). In cultured breast cancer cells, knockdown of Rictor also reduces cell motility and survival (19). Thus, Rictor is becoming a valuable therapeutic target in breast cancer. miRNAs are a class of 18- to 24-nucleotide non-coding regulatory RNAs that can modulate multiple cell behaviours through the RNA interference mechanism (21, 22). miRNAs interact with the 3’ untranslated region (3’ UTR) of target mRNAs to induce mRNA degradation and translational repression (23). Emerging evidence indicates that miRNAs might be regarded as oncogenes or tumour suppressors (24, 25), and their abnormal expression is highly correlated with the progression and pathology of breast cancer (26, 27), supporting their diagnostic, prognostic, and therapeutic potential in breast cancer (28). The aim of this study was to identify miRNAs that down-regulate Rictor and investigate their function on breast cancer cell survival.

Materials and Methods

Cell cultures and reagents. The breast cancer cell lines HCC1954, MDA-MB-231, SK-BR-3, and BT474 were obtained from the American Type Culture Collection (Manassas, VA, USA) and cultured in the recommended medium with 10% foetal bovine serum (#FBS-52A; Capricorn Scientific, Hessen, Germany) in an incubator at 37°C with 5% CO2. 3-(4,5-Dimethylthiazolyl-2)-2,5-diphenyltetrazolium bromide (MTT) was purchased from Sigma–Aldrich (Merck KGaA, Darmstadt, Germany). 137Cesium (137Cs) was used as a source of γ-radiation (Atomic Energy of Canada Limited, Chalk River, ON, Canada).

Trypan blue assay of cell viability. Cells (1×105 per well) were seeded in 6-well plates. At the end of treatment, the cells were gently harvested and mixed with 0.4% trypan blue solution (Welgene, Daegu, Republic of Korea). The cell number was determined by counting trypan blue-negative cells.

MTT assay of cell viability. Cells were seeded in a 60-mm dish and grown overnight until they reached approximately 50% cell confluence. Cell viability was assessed by measuring the mitochondrial conversion of MTT. The proportion of converted MTT was calculated by measuring the absorbance at 570 nm. The results are expressed as the percentage reduction in MTT, assuming that the absorbance of the control cells was 100%. The MTT experiments were repeated 3 times.

Transient transfection. Rictor (5’-TTAATTGTAGCAATAGAGGGTd TdT-3’) (29) and control (5’-CCUACGCCACCAAUUUCGUdTdT-3’) siRNAs were synthesized by Genolution (Seoul, Republic of Korea). miR-3188 mimic (#C-301753-00) and miR-control (#CN-001000-01) were purchased from Dharmacon (Horizon Discovery, Lafayette, CO, USA). Transfections with siRNAs or miRNAs were performed using Lipofectamine RNAiMAX according to the manufacturer’s instructions (Invitrogen; Thermo Fisher Scientific, Waltham, MA, USA).

miRNA extraction and quantitative real-time polymerase chain reaction. miRNAs were extracted using the mirVana miRNA isolation kit (#AM1561; Invitrogen; Thermo Fisher Scientific). Reverse transcription of miRNA was performed using the TaqMan miRNA reverse transcription kit (#4366596; Applied Biosystems; Thermo Fisher Scientific) and individual TaqMan miRNA assays. The following primers were used: hsa-miR-3188 (Assay ID: 464645_mat) and U6 snRNA (Assay ID: 001973). The expression levels of miR-3188 were normalized to the expression of U6 and were calculated using the 2–ΔΔCT method with triplicate samples.

RNA extraction and reverse transcription polymerase chain reaction. RNA was isolated from cells using TRIzol Reagent according to the manufacturer’s instructions (Invitrogen; Thermo Fisher Scientific). cDNA primed with oligo dT was prepared from 1 μg total RNA using M-MLV Reverse Transcriptase (Invitrogen; Thermo Fisher Scientific). The following specific primers were used: Rictor; 5’-ACCAGC GTTATCCCACCTTG-3’ and 5’-CCGATATTTCCCAAG GCCCA-3’, 429 bp product; β-actin: 5’-GGATTCCTATGTGGGCGA CGA-3’ and 5’-CGCTCGGTGAGGATCTTCATG-3’, 438 bp product (30). Amplication of Rictor was performed for 30 cycles at 95°C for 30 sec, 55°C for 30 sec, and 72°C for 30 sec. Amplication of β-Actin was performed for 26 cycles at 95°C for 30 s, 55°C for 30 s, and 72°C for 30 s. The PCR products were visualized on a 2% agarose gel containing ethidium bromide.

Dual-luciferase reporter assay. The wild-type (WT) 3’- or mutated-type (MUT) 3’-UTRs of the Rictor gene containing the miR-3188 binding site were synthesized by Genolution. A 60-bp synthesized WT 3’ UTR (5’-CAUAUUUGUGGAUUUCCUAAAAGCCUCAGAAA AUACGACUGACUAGGCAGCAAAGACAGG-3’) and MUT 3’ UTR fragment (5’-AUAUUUGUGGAUUUCCUAUUUCGGAG AGAAAATUACGACUGACUAGGCAGCAAAGACAGG-3’) of the Rictor gene were cloned into the pmirGLO dual-luciferase miRNA target expression vector (Promega, Madison, WI, USA) downstream of the firefly luciferase coding region between the NheI and SalI sites. Luciferase activity was measured by a dual-luciferase reporter assay kit (#E1910; Promega) and normalized to Renilla luciferase.

Western blot analysis. Cells were lysed in RIPA buffer [50 mM Tris (pH 7.5), 150 mM NaCl, 1% Triton X-100, 0.1% SDS, 1% sodium deoxycholate, 5 mM EDTA, 100 mM NaF, and 1 mM Na3VO4] containing protease inhibitor cocktail (Roche Diagnostics GmbH, Penzberg, Germany) for 30 min at 4°C. Cell lysates were cleared by centrifugation at 13,000 × g for 20 min at 4°C, and the protein concentrations were measured by Bradford reagent (Bio–Rad Laboratories, Hercules, CA, USA). Protein samples (15-30 μg) were separated using 6-12% SDS–PAGE gels and transferred onto nitrocellulose membranes. The primary antibodies were incubated overnight at 4°C. The following antibodies were used: anti-Rictor (#2114), anti-AKT (#9272), and anti-p-AKT at Ser473 (#9271), which were obtained from Cell Signaling Technology (Beverly, MA, USA); anti-β-actin (#A5316), which was obtained from Sigma–Aldrich (Merck KGaA). After 3 washes in TBS-T buffer, the membranes were incubated for 2 h at room temperature with horseradish peroxidase-conjugated anti-rabbit IgG (#sc-2030; Santa Cruz Biotechnology, Dallas, TX, USA) or anti-mouse IgG (#sc-2005; Santa Cruz Biotechnology). Immunoreactive bands were visualized with SuperSignal West Pico chemiluminescent substrate (Pierce; Thermo Fisher Scientific).

Survival analysis. To determine the role of Rictor in breast cancer, we analysed the Human Protein Atlas database (https://www.proteinatlas.org/ENSG00000164327-RICTOR/pathology/breast+cancer/, accessed 14 August 2021). The overall survival of 1,075 breast cancer patients was assessed for the Rictor gene. Breast cancer patients were divided into high and low expression groups by using the best cut-off of Rictor mRNA expression (low expression: n=818 and high expression: n=257). Survival curves were estimated for each group, considered separately, using the Kaplan–Meier method, and compared statistically using the log rank test.

Statistical analysis. The data are presented as the means±standard deviation. Statistical differences were made by the Student’s t-test of two groups or one-way ANOVA for multiple groups, followed by Tukey’s test, using GraphPad Prism software (version 5.0, San Diego, CA, USA); differences at p<0.05 were considered statistically significant.

Results

Knockdown of Rictor inhibits breast cancer cell viability. Rictor overexpression has been reported in invasive breast cancer and was associated with a decrease in overall survival in breast cancer patients (19). First, we investigated Rictor protein levels in invasive and non-invasive breast cancer cell lines. As expected, Rictor protein levels were high in the invasive breast cancer cell lines HCC1954 and MDA-MB-231 compared to the non-invasive breast cancer cell lines SK-BR-3 and BT474 (Figure 1A). Next, we assessed the survival rates of breast cancer patients according to Rictor expression using the Human Protein Atlas database. Breast cancer patients with high Rictor expression showed worse outcomes than those with low Rictor expression (Figure 1B). It has been reported that Rictor is a component of mTORC2, which regulates cancer cell survival and proliferation by AKT Ser473 phosphorylation (31). We assessed the effects of Rictor knockdown on AKT phosphorylation and cell viability in HCC1954 and MDA-MB-231 breast cancer cells. Rictor siRNA abrogated Rictor expression in these cells (Figure 1C). Rictor knockdown cells showed a marked decrease in AKT phosphorylation at Ser473 and cell viability (Figure 1C and D). These data suggest that Rictor deficiency led to reduced AKT activation and cell viability.

Figure 1.
Figure 1.

Knockdown of Rictor inhibits breast cancer cell viability. (A) HCC1954, MDA-MB-231, SK-BR-3, and BT474 cells were harvested when grown to 60~70% confluence. Rictor protein expression was measured by western blot analysis. (B) Assessment of survival probability in breast cancer patients according to Rictor expression levels using the Kaplan–Meier method and online resources (Human Protein Atlas database, https://www.proteinatlas.org/ENSG00000164327-RICTOR/pathology/breast+cancer. Accessed on 14 August 2021). (C) HCC1954 and MDA-MB-231 cells were transfected with control siRNA or Rictor siRNA for 48 h. The indicated protein levels were detected by western blot. (D) HCC1954 and MDA-MB-231 cells were transfected with control siRNA or Rictor siRNA for 24 h. The cells were reseeded at a density of 1×105 cells per well in a 6-well plate and then incubated for the indicated times. The cell number was determined by counting trypan blue-negative cells. Data are presented as the means±SD relative to the control (n=3). Significantly different at *p<0.05, **p<0.01 or ***p<0.001 versus the control siRNA-treated group. CTL: Control.

miR-3188 suppresses Rictor expression. To examine the molecular mechanism underlying the down-regulation of Rictor expression, putative miRNA target sites in the 3’ untranslated region (3’UTR) of Rictor were analysed using TargetScan and miRDB algorithms. Of the top 10 miRNAs predicted by the two algorithms respectively, miR-3188 was the only overlap between two algorithms (data not shown). miR-3188 was one of the highest ranking predicted miRNAs with context++ score=-0.28 and miRDB score=99 (Figure 2A). The potential matching positions of miR-3188 within in the 3’UTR of Rictor mRNA are depicted in Figure 2B. To investigate the effect of miR-3188 on Rictor regulation, specific mimics were transfected into HCC1954 and MDA-MB-231 cells. The miR-3188 mimic significantly elevated miR-3188 levels, confirming effective cell transfection (Figure 2C). Transfection with the miR-3188 mimic significantly down-regulated the mRNA and protein levels of Rictor (Figure 2D). To further confirm Rictor as a direct target of action of miR-3188, the wild-type (WT) or mutated-type (MUT) sequences in the 3’UTR of Rictor that miR-3188 targets were designed to construct luciferase reporter and co-transfected with either miR-3188 mimic or miR-control. As shown in Figure 2E, miR-3188 overexpression markedly inhibited the luciferase activity of Rictor 3’UTR-WT in HCC1954 and MDA-MB-231 cells but did not affect Rictor 3’UTR-MUT, which suggested that this site in the Rictor 3’UTR was the exact regulatory site of miR-3188. These results suggest that miR-3188 directly targeted Rictor 3’UTR and suppressed Rictor expression.

Figure 2.
Figure 2.

miR-3188 down-regulates Rictor expression. (A) The prediction scores of miR-3188-Rictor interaction gained from TargetScan and miRDB. (B) The putative miR-3188 targeted sequence in the Rictor gene. TargetScan predicted four binding sites in Rictor 3’UTR. (C, D) HCC1954 and MDA-MB-231 cells were transfected with miR-control or miR-3188 mimic for 48 h. miR-3188 expression levels were measured by real-time PCR (C). Data were normalized to U6 expression and presented as the log10-fold-change relative to the miRNA control-treated group. Rictor mRNA and protein expression levels were measured by RT–PCR and western blot analysis, respectively (D). (E) Luciferase reporter constructs containing WT or MUT Rictor 3’UTR were co-transfected with miR-control or miR-3188 mimic. Firefly luciferase activity was evaluated at 48 h after transfection and normalized relative to the Renilla luciferase activity. Data are presented as the means±SD relative to the control (n=3). Significantly different at ***p<0.001 versus the miR-control treated group. ns: Not significantly different; CTL: control; miR: microRNA; MUT: mutated; WT: wild-type.

miR-3188 inhibits AKT activation and cell viability. Next, we investigated whether miR-3188 inhibits AKT activation and cell viability. As shown in Figure 3A, the protein levels of phosphorylated AKT were significantly decreased by miR-3188 overexpression. HCC1954 and MDA-MB-231 cells transfected with miR-3188 mimic showed lower cell viability than those transfected with miR-control (Figure 3B). These results suggest that miR-3188 decreased AKT activation and cell viability in breast cancer cells.

Figure 3.
Figure 3.

miR-3188 inhibits AKT activation and cell viability. (A) HCC1954 and MDA-MB-231 cells were transfected with miR-control or miR-3188 mimic for 48 h. The protein expression levels were measured by western blot analysis. (B) HCC1954 and MDA-MB-231 cells were transfected with miR-control or miR-3188 mimic for 24 h. The cells were reseeded at a density of 1×105 cells per well in a 6-well plate and then incubated for the indicated times. The cell viability was determined by counting trypan blue-negative cells. Data are presented as the means±SD relative to control (n=3). Significantly different at *p<0.05 or **p<0.01 versus the miR-control treated group. CTL: Control.

Rictor knockdown or miR-3188 overexpression enhances cell sensitivity to ionizing radiation. To explore whether Rictor knockdown could potentiate cell sensitivity to ionizing radiation (IR), HCC1954 cells were transfected with Rictor siRNA, followed by treatment with 7.5 Gy of IR. As shown in Figure 4A and B, in control cells, 7.5 Gy IR slightly induced AKT phosphorylation at Ser473 and suppressed 20% cell viability. However, in Rictor-knockdown cells, the same dose of IR greatly inhibited AKT phosphorylation and suppressed 60% cell viability. Indeed, treatment with Rictor siRNA increased PARP cleavage, and IR further increased PARP cleavage under Rictor siRNA treatment (Figure 4A). We next investigated whether miR-3188 could potentiate cell sensitivity to IR. In miR-3188-overexpressing HCC1954 cells, IR further suppressed the protein expression of Rictor and p-AKT and markedly increased PARP cleavage (Figure 4C and D). These results suggest that Rictor knockdown or miR-3188 overexpression sensitizes breast cancer cells to IR.

Figure 4.
Figure 4.

Rictor knockdown or miR-3188 overexpression enhances cell sensitivity to ionizing radiation. (A, B) HCC1954 cells were transfected with control siRNA or Rictor siRNA for 8 h and then exposed to 7.5 Gy of IR for 48 h. (C, D) HCC1954 cells were transfected with miR-control or miR-3188 mimic for 8 h and then exposed to 7.5 Gy of IR for 48 h. The indicated protein levels were determined by western blot (A, C). Cell viability was measured using an MTT assay (B, D). The data are presented as the mean±SD relative to the control. Significantly different at **p<0.01 or ***p<0.001 versus the control. IR: Ionizing radiation.

Discussion

Recent studies have reported that Rictor has critical oncogenic roles in regulating cell proliferation and metastasis in a variety of cancer cells, such as melanoma (13), pheochromocytoma (14), colorectal cancer (15), breast cancer (16), and renal cell carcinoma (17). Clinical studies have shown that Rictor expression in invasive breast cancer specimens was significantly up-regulated compared to that in non-malignant tissues (19). Moreover, Rictor amplification was associated with decreased overall survival in invasive breast cancer patients (19). Genetic Rictor ablation has been previously reported to eliminate mTORC2 signalling, block AKT Ser473 phosphorylation, and ultimately, decrease tumour cell survival (19). In line with these findings, we observed that invasive breast cancer-derived HCC1954 and MDA-MB-231 cells expressed increased levels of Rictor compared to the non-invasive breast cancer cell lines SK-BR-3 and BT474. The Human Protein Atlas database revealed that breast cancer patients with high Rictor expression had shorter overall survival than those with low Rictor expression. In Rictor-overexpressing HCC1954 and MDA-MB-231 cells, siRNA-mediated knockdown of Rictor decreased AKT Ser473 phosphorylation and inhibited cell viability. These data indicated that Rictor may serve as a prognostic biomarker and therapeutic target.

To investigate the mechanism underlying the down-regulation of Rictor expression, putative miRNA target sites in the 3’ untranslated region (3’UTR) of Rictor were analysed using TargetScan and miRDB algorithms. Of the top 10 miRNAs predicted by the two algorithms respectively, miR-3188 was the only overlap between two algorithms. TargetScan was predicted to have four miR-3188 binding sites in the 3’UTR of Rictor mRNA. We demonstrated that miR-3188 directly targets the 3’UTR of Rictor, as its overexpression was associated with suppression of luciferase activity in a reporter plasmid. Rictor mRNA and protein levels were down-regulated in miR-3188-overexpressing cells. Importantly, miR-3188 decreased AKT Ser473 phosphorylation and inhibited breast cancer cell viability. Recent miRNA microarray data identified that miR-3188 expression level was up-regulated in acquired radioresistant glioblastoma cells compared to its parent cells (32). However, in this study, miR-3188 expression levels were down-regulated in ionizing radiation (IR)-treated HCC1954 breast cancer cells. And, in these cells, AKT Ser473 phosphorylation was slightly increased. miR-3188 overexpression suppressed Rictor expression and AKT phosphorylation and enhanced the sensitivity of breast cancer cells to IR.

In conclusion, these results suggest that miR-3188 inhibits the mTORC2/AKT pathway by suppressing Rictor, leading to sensitization of breast cancer cells to IR. miR-3188 may serve as a potential effective therapeutic agent to treat breast cancer.

Acknowledgements

This research was supported by Grants from the Korea Institute of Radiological and Medical Sciences (KIRAMS), which were funded by the Ministry of Science and ICT (MSIT), Republic of Korea (Nos. 50531-2021; 50544-2021 and 50548-2021).

Footnotes

  • ↵# These Authors contributed equally to this study.

  • Authors’ Contributions

    In-Chul Park and Woo Chul Noh developed the concept and designed the study. Sung-Eun Hong, Hyeon-Ok Jin, Seung-Mi Kim and Se-Kyeong Jang carried out the experiments. Chan Sub Park, Min-Ki Seong and Hyun-Ah Kim provided technical support and conceptual advice. Hyeon-Ok Jin, In-Chul Park and Woo Chul Noh wrote the manuscript. All Authors read and approved the final manuscript.

  • Conflicts of Interest

    The Authors have no conflicts of interest to declare.

  • Received September 16, 2021.
  • Revision received October 10, 2021.
  • Accepted October 27, 2021.

References

  1. ↵
    1. Sung H,
    2. Ferlay J,
    3. Siegel RL,
    4. Laversanne M,
    5. Soerjomataram I,
    6. Jemal A and
    7. Bray F
    : Global cancer statistics 2020: GLOBOCAN estimates of incidence and mortality worldwide for 36 cancers in 185 countries. CA Cancer J Clin 71(3): 209-249, 2021. PMID: 33538338. DOI: 10.3322/caac.21660
    OpenUrlCrossRefPubMed
    1. Azamjah N,
    2. Soltan-Zadeh Y and
    3. Zayeri F
    : Global trend of breast cancer mortality rate: a 25-year study. Asian Pac J Cancer Prev 20(7): 2015-2020, 2019. PMID: 31350959. DOI: 10.31557/APJCP.2019.20.7.2015
    OpenUrlCrossRefPubMed
  3. ↵
    1. Borg A,
    2. Fernö M and
    3. Peterson C
    : Predicting the future of breast cancer. Nat Med 9(1): 16-18, 2003. PMID: 12514712. DOI: 10.1038/nm0103-16
    OpenUrlCrossRefPubMed
  4. ↵
    1. Polyak K
    : Heterogeneity in breast cancer. J Clin Invest 121(10): 3786-3788, 2011. PMID: 21965334. DOI: 10.1172/JCI60534
    OpenUrlCrossRefPubMed
  5. ↵
    1. Miller TW,
    2. Rexer BN,
    3. Garrett JT and
    4. Arteaga CL
    : Mutations in the phosphatidylinositol 3-kinase pathway: role in tumor progression and therapeutic implications in breast cancer. Breast Cancer Res 13(6): 224, 2011. PMID: 22114931. DOI: 10.1186/bcr3039
    OpenUrlCrossRefPubMed
    1. Engelman JA
    : Targeting PI3K signalling in cancer: opportunities, challenges and limitations. Nat Rev Cancer 9(8): 550-562, 2009. PMID: 19629070. DOI: 10.1038/nrc2664
    OpenUrlCrossRefPubMed
    1. She QB,
    2. Gruvberger-Saal SK,
    3. Maurer M,
    4. Chen Y,
    5. Jumppanen M,
    6. Su T,
    7. Dendy M,
    8. Lau YK,
    9. Memeo L,
    10. Horlings HM,
    11. van de Vijver MJ,
    12. Isola J,
    13. Hibshoosh H,
    14. Rosen N,
    15. Parsons R and
    16. Saal LH
    : Integrated molecular pathway analysis informs a synergistic combination therapy targeting PTEN/PI3K and EGFR pathways for basal-like breast cancer. BMC Cancer 16: 587, 2016. PMID: 27484095. DOI: 10.1186/s12885-016-2609-2
    OpenUrlCrossRefPubMed
  8. ↵
    1. Li J,
    2. Zhang C,
    3. Jiang H and
    4. Cheng J
    : Andrographolide inhibits hypoxia-inducible factor-1 through phosphatidylinositol 3-kinase/AKT pathway and suppresses breast cancer growth. Onco Targets Ther 8: 427-435, 2015. PMID: 25709476. DOI: 10.2147/OTT.S76116
    OpenUrlCrossRefPubMed
  9. ↵
    1. Bhaskar PT and
    2. Hay N
    : The two TORCs and Akt. Dev Cell 12(4): 487-502, 2007. PMID: 17419990. DOI: 10.1016/j.devcel.2007.03.020
    OpenUrlCrossRefPubMed
  10. ↵
    1. Zoncu R,
    2. Efeyan A and
    3. Sabatini DM
    : mTOR: from growth signal integration to cancer, diabetes and ageing. Nat Rev Mol Cell Biol 12(1): 21-35, 2011. PMID: 21157483. DOI: 10.1038/nrm3025
    OpenUrlCrossRefPubMed
  11. ↵
    1. Saxton RA and
    2. Sabatini DM
    : mTOR signaling in growth, metabolism, and disease. Cell 168(6): 960-976, 2017. PMID: 28283069. DOI: 10.1016/j.cell.2017.02.004
    OpenUrlCrossRefPubMed
  12. ↵
    1. Laplante M and
    2. Sabatini DM
    : mTOR signaling in growth control and disease. Cell 149(2): 274-293, 2012. PMID: 22500797. DOI: 10.1016/j.cell.2012.03.017
    OpenUrlCrossRefPubMed
  13. ↵
    1. Laugier F,
    2. Finet-Benyair A,
    3. André J,
    4. Rachakonda PS,
    5. Kumar R,
    6. Bensussan A and
    7. Dumaz N
    : RICTOR involvement in the PI3K/AKT pathway regulation in melanocytes and melanoma. Oncotarget 6(29): 28120-28131, 2015. PMID: 26356562. DOI: 10.18632/oncotarget.4866
    OpenUrlCrossRefPubMed
  14. ↵
    1. Zhang X,
    2. Wang X,
    3. Xu T,
    4. Zhong S and
    5. Shen Z
    : Targeting of mTORC2 may have advantages over selective targeting of mTORC1 in the treatment of malignant pheochromocytoma. Tumour Biol 36(7): 5273-5281, 2015. PMID: 25666752. DOI: 10.1007/s13277-015-3187-7
    OpenUrlCrossRefPubMed
  15. ↵
    1. Gulhati P,
    2. Bowen KA,
    3. Liu J,
    4. Stevens PD,
    5. Rychahou PG,
    6. Chen M,
    7. Lee EY,
    8. Weiss HL,
    9. O’Connor KL,
    10. Gao T and
    11. Evers BM
    : mTORC1 and mTORC2 regulate EMT, motility, and metastasis of colorectal cancer via RhoA and Rac1 signaling pathways. Cancer Res 71(9): 3246-3256, 2011. PMID: 21430067. DOI: 10.1158/0008-5472.CAN-10-4058
    OpenUrlAbstract/FREE Full Text
  16. ↵
    1. Zhang F,
    2. Zhang X,
    3. Li M,
    4. Chen P,
    5. Zhang B,
    6. Guo H,
    7. Cao W,
    8. Wei X,
    9. Cao X,
    10. Hao X and
    11. Zhang N
    : mTOR complex component Rictor interacts with PKCzeta and regulates cancer cell metastasis. Cancer Res 70(22): 9360-9370, 2010. PMID: 20978191. DOI: 10.1158/0008-5472.CAN-10-0207
    OpenUrlAbstract/FREE Full Text
  17. ↵
    1. Sun B,
    2. Chen L,
    3. Fu H,
    4. Guo L,
    5. Guo H and
    6. Zhang N
    : Upregulation of RICTOR gene transcription by the proinflammatory cytokines through NF-κB pathway contributes to the metastasis of renal cell carcinoma. Tumour Biol 37(4): 4457-4466, 2016. PMID: 26500094. DOI: 10.1007/s13277-015-4296-z
    OpenUrlCrossRefPubMed
  18. ↵
    1. Cheng H,
    2. Zou Y,
    3. Ross JS,
    4. Wang K,
    5. Liu X,
    6. Halmos B,
    7. Ali SM,
    8. Liu H,
    9. Verma A,
    10. Montagna C,
    11. Chachoua A,
    12. Goel S,
    13. Schwartz EL,
    14. Zhu C,
    15. Shan J,
    16. Yu Y,
    17. Gritsman K,
    18. Yelensky R,
    19. Lipson D,
    20. Otto G,
    21. Hawryluk M,
    22. Stephens PJ,
    23. Miller VA,
    24. Piperdi B and
    25. Perez-Soler R
    : RICTOR amplification defines a novel subset of patients with lung cancer who may benefit from treatment with mTORC1/2 inhibitors. Cancer Discov 5(12): 1262-1270, 2015. PMID: 26370156. DOI: 10.1158/2159-8290.CD-14-0971
    OpenUrlAbstract/FREE Full Text
  19. ↵
    1. Morrison Joly M,
    2. Hicks DJ,
    3. Jones B,
    4. Sanchez V,
    5. Estrada MV,
    6. Young C,
    7. Williams M,
    8. Rexer BN,
    9. Sarbassov dos D,
    10. Muller WJ,
    11. Brantley-Sieders D and
    12. Cook RS
    : Rictor/mTORC2 drives progression and therapeutic resistance of HER2-amplified breast cancers. Cancer Res 76(16): 4752-4764, 2016. PMID: 27197158. DOI: 10.1158/0008-5472.CAN-15-3393
    OpenUrlAbstract/FREE Full Text
  20. ↵
    1. Balko JM,
    2. Giltnane JM,
    3. Wang K,
    4. Schwarz LJ,
    5. Young CD,
    6. Cook RS,
    7. Owens P,
    8. Sanders ME,
    9. Kuba MG,
    10. Sánchez V,
    11. Kurupi R,
    12. Moore PD,
    13. Pinto JA,
    14. Doimi FD,
    15. Gómez H,
    16. Horiuchi D,
    17. Goga A,
    18. Lehmann BD,
    19. Bauer JA,
    20. Pietenpol JA,
    21. Ross JS,
    22. Palmer GA,
    23. Yelensky R,
    24. Cronin M,
    25. Miller VA,
    26. Stephens PJ and
    27. Arteaga CL
    : Molecular profiling of the residual disease of triple-negative breast cancers after neoadjuvant chemotherapy identifies actionable therapeutic targets. Cancer Discov 4(2): 232-245, 2014. PMID: 24356096. DOI: 10.1158/2159-8290.CD-13-0286
    OpenUrlAbstract/FREE Full Text
  21. ↵
    1. Nikitina EG,
    2. Urazova LN and
    3. Stegny VN
    : MicroRNAs and human cancer. Exp Oncol 34(1): 2-8, 2012. PMID: 22453141.
    OpenUrlPubMed
  22. ↵
    1. Robertson NM and
    2. Yigit MV
    : The role of microRNA in resistance to breast cancer therapy. Wiley Interdiscip Rev RNA 5(6): 823-833, 2014. PMID: 25044299. DOI: 10.1002/wrna.1248
    OpenUrlCrossRefPubMed
  23. ↵
    1. Ha M and
    2. Kim VN
    : Regulation of microRNA biogenesis. Nat Rev Mol Cell Biol 15(8): 509-524, 2014. PMID: 25027649. DOI: 10.1038/nrm3838
    OpenUrlCrossRefPubMed
  24. ↵
    1. Iorio MV,
    2. Ferracin M,
    3. Liu CG,
    4. Veronese A,
    5. Spizzo R,
    6. Sabbioni S,
    7. Magri E,
    8. Pedriali M,
    9. Fabbri M,
    10. Campiglio M,
    11. Ménard S,
    12. Palazzo JP,
    13. Rosenberg A,
    14. Musiani P,
    15. Volinia S,
    16. Nenci I,
    17. Calin GA,
    18. Querzoli P,
    19. Negrini M and
    20. Croce CM
    : MicroRNA gene expression deregulation in human breast cancer. Cancer Res 65(16): 7065-7070, 2005. PMID: 16103053. DOI: 10.1158/0008-5472.CAN-05-1783
    OpenUrlAbstract/FREE Full Text
  25. ↵
    1. Farazi TA,
    2. Horlings HM,
    3. Ten Hoeve JJ,
    4. Mihailovic A,
    5. Halfwerk H,
    6. Morozov P,
    7. Brown M,
    8. Hafner M,
    9. Reyal F,
    10. van Kouwenhove M,
    11. Kreike B,
    12. Sie D,
    13. Hovestadt V,
    14. Wessels LF,
    15. van de Vijver MJ and
    16. Tuschl T
    : MicroRNA sequence and expression analysis in breast tumors by deep sequencing. Cancer Res 71(13): 4443-4453, 2011. PMID: 21586611. DOI: 10.1158/0008-5472.CAN-11-0608
    OpenUrlAbstract/FREE Full Text
  26. ↵
    1. Andorfer CA,
    2. Necela BM,
    3. Thompson EA and
    4. Perez EA
    : MicroRNA signatures: clinical biomarkers for the diagnosis and treatment of breast cancer. Trends Mol Med 17(6): 313-319, 2011. PMID: 21376668. DOI: 10.1016/j.molmed.2011.01.006
    OpenUrlCrossRefPubMed
  27. ↵
    1. Melo SA and
    2. Esteller M
    : Dysregulation of microRNAs in cancer: playing with fire. FEBS Lett 585(13): 2087-2099, 2011. PMID: 20708002. DOI: 10.1016/j.febslet.2010.08.009
    OpenUrlCrossRefPubMed
  28. ↵
    1. Piva R,
    2. Spandidos DA and
    3. Gambari R
    : From microRNA functions to microRNA therapeutics: novel targets and novel drugs in breast cancer research and treatment (Review). Int J Oncol 43(4): 985-994, 2013. PMID: 23939688. DOI: 10.3892/ijo.2013.2059
    OpenUrlCrossRefPubMed
  29. ↵
    1. Breuleux M,
    2. Klopfenstein M,
    3. Stephan C,
    4. Doughty CA,
    5. Barys L,
    6. Maira SM,
    7. Kwiatkowski D and
    8. Lane HA
    : Increased AKT S473 phosphorylation after mTORC1 inhibition is rictor dependent and does not predict tumor cell response to PI3K/mTOR inhibition. Mol Cancer Ther 8(4): 742-753, 2009. PMID: 19372546. DOI: 10.1158/1535-7163.MCT-08-0668
    OpenUrlAbstract/FREE Full Text
  30. ↵
    1. Jin HO,
    2. Park IC,
    3. An S,
    4. Lee HC,
    5. Woo SH,
    6. Hong YJ,
    7. Lee SJ,
    8. Park MJ,
    9. Yoo DH,
    10. Rhee CH and
    11. Hong SI
    : Up-regulation of Bak and Bim via JNK downstream pathway in the response to nitric oxide in human glioblastoma cells. J Cell Physiol 206(2): 477-486, 2006. PMID: 16158421. DOI: 10.1002/jcp.20488
    OpenUrlCrossRefPubMed
  31. ↵
    1. Guertin DA,
    2. Stevens DM,
    3. Thoreen CC,
    4. Burds AA,
    5. Kalaany NY,
    6. Moffat J,
    7. Brown M,
    8. Fitzgerald KJ and
    9. Sabatini DM
    : Ablation in mice of the mTORC components raptor, rictor, or mLST8 reveals that mTORC2 is required for signaling to Akt-FOXO and PKCalpha, but not S6K1. Dev Cell 11(6): 859-871, 2006. PMID: 17141160. DOI: 10.1016/j.devcel.2006.10.007
    OpenUrlCrossRefPubMed
  32. ↵
    1. Ondracek J,
    2. Fadrus P,
    3. Sana J,
    4. Besse A,
    5. Loja T,
    6. Vecera M,
    7. Radova L,
    8. Smrcka M,
    9. Slampa P and
    10. Slaby O
    : Global microRNA expression profiling identifies unique microRNA pattern of radioresistant glioblastoma cells. Anticancer Res 37(3): 1099-1104, 2017. PMID: 28314270. DOI: 10.21873/anticanres.11422
    OpenUrlAbstract/FREE Full Text
Back to top

In this issue

Print
Download PDF
Article Alerts
Email Article
Citation Tools
Reprints and Permissions
miR-3188 Enhances Sensitivity of Breast Cancer Cells to Ionizing Radiation by Down-regulating Rictor
SUNG-EUN HONG, HYEON-OK JIN, SEUNG-MI KIM, SE-KYEONG JANG, CHAN SUB PARK, MIN-KI SEONG, HYUN-AH KIM, WOO CHUL NOH, IN-CHUL PARK
Anticancer Research Dec 2021, 41 (12) 6169-6176; DOI: 10.21873/anticanres.15436
Twitter logo Facebook logo Mendeley logo

Jump to section

Keywords