Research ArticleExperimental Studies

17-Allylamino-17-demethoxygeldanamycin-induced Changes in [18F]Fluorothymidine Uptake

HANG JUNG LEE, DO HYUNG KIM and SEUNG JIN LEE
Anticancer Research June 2017, 37 (6) 2993-2999;

Abstract

The proliferation status of tumor cells can be imaged using [18F]fluorothymidine ([18F]FLT), which is trapped by cell cycle-dependent thymidine kinase 1 (TK1). Targeting of heat shock protein 90 (HSP90) disrupts multiple client proteins, leading to heterogeneous cell-cycle phenotypes. To investigate whether [18F]FLT uptake reflects the growth arrest caused by various mechanisms of HSP90 inhibition, we used HCT116 cells that were arrested at G0/G1 phase, and Hep3B cells at G2/M phase, by the HSP90 inhibitor 17-AAG. In HCT116 cells, 17-AAG did not induce significant changes in [18F]FLT uptake despite the decreased expression of TK1, cyclin A, and cyclin B. The mRNA level of 5’3’-deoxynucleotidase 1 (NT5C), which antagonizes TK1 by de-phosphorylating [18F]FLT monophosphate, was also decreased in 17-AAG-treated HCT116 cells by 55.3±18.1% compared to vehicle-treated cells. In Hep3B cells, 17-AAG treatment did not induce TK1 expression, TK1 activity nor [18F]FLT uptake. Nucleoside transporter activity in the plasma membrane was unchanged in both cell lines. These results showed that a HSP90 inhibitor exerts multifaceted effects on [18F]FLT uptake before inducing cell death in a cell-cycle-independent manner. Therefore, the use of [18F]FLT-positron emission tomography for monitoring treatment by HSP90 inhibitor would be more appropriate when tumor cell death is induced after growth arrest.

Early monitoring of the therapeutic response in individual patients can facilitate selection of those likely to benefit from treatment and eventually contribute to tailored therapy. Cell proliferation is an attractive biological process as an indicator of therapeutic response, because it eventually reflects tumor growth (1, 2). Currently, immunohistochemical analysis of cell proliferation requires invasive biopsy, which is difficult to perform repeatedly, does not reflect tumor heterogeneity and lacks analytical validity (3). [18F]Fluorothymidine ([18F]FLT) is a promising tracer for positron emission tomography (PET) for non-invasive imaging of proliferation status preceded by a reduction in tumor size (4). A search in August 2015 of clinicaltrials.gov using the keywords “FLT”, “PET” and “cancer” returned 61 ongoing or recently completed studies involving [18F]FLT PET evaluation.

The primary factor mediating [18F]FLT uptake and retention in tumors in response to proliferation status is thymidine kinase 1 (TK1) (5, 6). TK1 enzyme can salvage nucleotide biosynthesis and phosphorylate [18F]FLT which is then trapped inside the cell. TK1 is dramatically activated at the transcriptional level at late G1-S phase when it shows maximal catalytic efficiency (7). TK1 catalytic activity is reduced during G2/M phase and TK1 protein levels are very low upon mitotic exit until the G1 phase of the next cycle. Drug-induced changes in TK1 activity is usually correlated with [18F]FLT uptake. Decreased TK1 activity during gefitinib-induced G0/G1-phase arrest is accompanied by reduced [18F]FLT uptake (8), whereas increased TK1 activity during 5-FU–induced S-phase arrest (9) or anti-tubulin-agent-induced G2/M arrest (10) were correlated with enhanced [18F]FLT uptake. Other mediators that determine intracellular [18F]FLT uptake include equilibrative nucleoside transporter 1 (ENT1) which mediates intracellular transport, and 5’3’-deoxyribonucleotidase 1 (NT5C), which dephosphorylates FLT monophosphate to FLT, thus antagonizing phosphorylation by TK1 (6, 11, 12). Therefore, therapy-induced early changes in [18F]FLT uptake in tumors can be influenced by pharmacodynamic effects on these mediators, which vary according to the tumor subtype.

Targeted heat shock protein 90 (HSP90) inhibition is regarded as an effective strategy for cancer treatment (13). Several compounds, such as ganetespib, are currently undergoing evaluation in human trials (14). 17-Allylamino-17-demethoxygeldanamycin (17-AAG) is a prototypical HSP90 inhibitor, and the extensive preclinical characterization of this compound has delivered critical proof-of-concept evidence for subsequent HSP90 inhibitors (15). Many oncogenes are HSP90 clients, for example, human epidermal growth factor receptor 2, mutant epidermal growth factor receptor, and anaplastic lymphoma kinase (13). HSP90 is involved in various cellular processes and its inhibition can generate complex cellular phenotypes. The heterogeneous phenotypes resulting from suppression of cellular proliferation include arrest in G1, G2+M or a combination thereof, depending on cellular genotype or drug dosage (16). Therefore, cell cycle-dependent events caused by HSP90 inhibitors should be examined with this consideration in mind.

Previous studies have evaluated the cellular response to HSP90 inhibitors using [18F]FLT utilized tumor spheroid models of MCF7, BT474, U87MG and HCT116 cells (17, 18). Evaluation was performed after 3 days treatment with the NVP-AUY 922 HSP90 inhibitor and showed a dose-dependent decrease in [18F]FLT uptake together with a significant reduction in spheroid growth (17). Considering that an imaging study is usually performed before the tumor mass decreases (19), it is required to evaluate the early changes of [18F]FLT uptake in response to HSP90 inhibitor treatment and to determine whether [18F]FLT uptake is affected by tumor type or drug dose. Moreover, the influence of cell type-dependent heterogeneous growth arrest mechanisms on [18F]FLT uptake is unclear. In this study, we aimed to evaluate the 17-AAG-induced changes in [3H]FLT uptake that occur prior to significant cell death in HCT116 and Hep3B cells, each arrested at different phases of the cell cycle and analyze the corresponding mechanisms of [3H]FLT uptake regulation.

Materials and Methods

Materials. 17-AAG was provided by LegoChemBio (Daejeon, Korea). Anti-TK1 antibody was purchased from Abnova (Walnut, CA, USA) and other antibodies from Cell Signaling Technology (Danvers, MA, USA). Other reagents were purchased from Sigma–Aldrich (St. Louis, MO, USA).

Cell culture and preparation. HCT116 (human colorectal carcinoma) and Hep3B (human hepatocellular carcinoma) cells were obtained from the American Type Culture Collection (Manassas, VA, USA) and Korea Cell Line Bank (Seoul, Korea), respectively. Cells were maintained in RPMI-1640 containing 10% fetal bovine serum, 10 U/ml penicillin and 10 μg/ml streptomycin at 37°C in a humidified atmosphere with 5% CO2. Viable cell number was calculated by trypan blue exclusion assay. Cell lysates were prepared as described previously and protein content was determined using the Bio-Rad protein assay (Hercules, CA, USA) (20).

3-(4,5-Dimethylthiazol-2-yl)-5-(3-carboxymethoxyphenyl)-2-(4-sulfophenyl)-2H-etrazolium (MTS) assay. Cells were plated at a density of 2×103 per well in 96-well plates, incubated for 24 h and then treated with 17-AAG for 72 h. Cell viability was examined using 3-(4,5-dimethylthiazol-2-yl)-5-(3-carboxymethoxyphenyl)-2-(4-sulfophenyl)-2H-tetrazoliu (MTS) (Promega, Madison, WI, USA) according to the manufacturer's instructions. Three independent experiments were performed, each in triplicate.

Flow cytometric analysis. Cells treated with vehicle or 17-AAG were trypsinized, fixed in 70% ethanol, stained with propidium iodide and subjected to flow cytometry analysis (Becton Dickinson, San Jose, CA, USA). Data obtained from the Particle Analysis System were processed using the ModFit LT software (Verity Software House). All experiments were independently repeated three times.

[3H]FLT uptake assay. Twenty-four hours after seeding 3×105 cells per well in six-well plates, exponentially growing cells were treated with 17-AAG for 24 h. Then, culture medium was removed and replaced with fresh 1 ml medium containing [methyl-3H]FLT (9.5 Ci/mmol) (Moravek Biochemical, Brea, CA, USA) for 2 h (0.001 μCi/ml medium). The radioactivities in cells and supernatants were measured using a liquid scintillation counter (Perkin-Elmer, Waltham, MA, USA). An aliquot of the cell fraction was used for enumerating cells. [3H]FLT uptake was calculated as 100×CPMcell/(CPMcell + CPMsup) per 1×105 viable cells. All experiments were independently repeated five times.

Immunoblot analysis. SDS-polyacrylamide gel electrophoresis and immunoblot analysis were performed as described previously (21). Multiple analyses were performed using different sets of samples. Changes in expression level normalized to β-actin level were determined by scanning densitometry of immunoblots using a Universal Hood II (Bio-Rad, Hercules, CA) and the Quantity One software.

Measurement of TK1 activity. TK1 activity was measured as described previously (17). The slope of the time-activity curve was used to calculate the number of picomoles of phosphorylated thymidine generated per min per microgram protein (pmol/min/μg). All experiments were repeated independently four times.

ENT1 activity in the plasma membrane. ENT1 activity was measured by equilibrium binding of 3H-S-(p-nitrobenzyl)-6-thioinosine ([3H]NBTI) (37 TBq/mmol, Moravek Biochemicals, Brea, CA, USA), as described previously (20, 21). Preliminary analysis estimated the Kd and Vmax values for [3H]NBTI binding in HCT116 cells (21). Cells were trypsinized, counted and incubated with 3.75 nM [3H]NBTI with or without 20 μM S-(4-nitrobenzyl)-6-thioguanosine in 400 μl medium for 1 h under gentle rocking to measure specific binding. After washing with Na+-containing buffer, cells were re-suspended in lysis buffer. The radioactivities of lysates were then measured using a liquid scintillation counter (Perkin-Elmer).

Reverse transcription-quantitative polymerase chain reaction (qPCR). Total RNA was isolated using the TRIzol reagent (Invitrogen, Carlsbad, CA, USA), according to the manufacturer's instructions. Aliquots (2 μg) were reverse-transcribed in mixtures containing AMV-reverse transcriptase, OligodT, dNTP and RNasin (Promega). The resulting cDNAs were used for real-time PCR analysis with Solaris qPCR Gene Expression Master Mix and specific primers for human 5’3’-deoxyribonucleotidase1 (NM_014595) and glyceraldehyde 3-phosphate dehydrogenase (GAPDH, NM_002046) (Dharmacon Inc., Lafayette, CO, USA) using a LightCycler 480 System (Roche, Indianapolis, IN, USA) according to the manufacturer's instructions. All experiments were repeated four times independently.

Figure 1.
Figure 1.

The phenotypes of growth inhibition induced by 17-AAG in HCT116 and Hep3B cells. (A) HCT116 and (B) Hep3B cells were treated with 17-AAG doses of 0, 0.1, 0.3, 1, 3, 10, 30, or 100 μM for 3 days and cell viability was measured by MTS assay analysis. Data are expressed as means±SD (n=3). Cells were treated with vehicle or 17-AAG at 1 μM in HCT116 cells (C) or at 100 μM in Hep3B cells (D) for 36 h and analyzed by flow cytometry. Representative results (left) and fractions of cells at G0/G1 phase (middle) and G2/M phase (right) are shown. Data are expressed as means±SD (n=3). Asterisk indicates p<0.05 compared to cells treated with vehicle at corresponding time points.

Statistical analysis. Data were expressed as means and standard deviation (SD). p<0.05 was considered to indicate statistical significance. Comparisons of two groups were performed using Student's t-test and the Friedman test. All statistical analyses were conducted using IBM SPSS Statistics for Windows software (v19.0; SPSS Inc., IBM Corp., Somers, NY, USA).

Figure 2.
Figure 2.

Effect of 17-AAG on [3H]FLT uptake. (A) HCT116 cells were treated with 17-AAG at 0, 0.1, 0.3, or 1 μM and (B) Heb3B cells with 1, 3, or 10 μM for 24 h. Cells were then further incubated with [3H]FLT for 2 h in fresh medium and uptake was analyzed as a percentage of [3H]FLT uptake per 1×105 cells. Data are expressed as means±SD (n=5).

Results

17-AAG–induced viability and growth arrest in HCT116 and Hep3B cells. To investigate the early effects of 17-AAG on [3H]FLT uptake under different types of cell-cycle arrest, we used the HCT116 and Hep3B cell lines which are known to exhibit representative phenotype for cell cycle arrest at G0/G1 and G2/M phase by 17-AAG, respectively (16, 22). We confirmed a dose-dependent inhibition of cell growth and time-dependent changes in growth status to determine the optimal conditions for subsequent assays. Treatment with 17-AAG for 72 h decreased significantly the viability in both cell lines (p<0.05). The growth of HCT116 cells treated with 0.3-30 μM 17-AAG was 50% lower than that of vehicle-treated cells (Figure 1A). Hep3B cells were more resistant to 17-AAG than HCT116 cells, as evidenced by a 50% growth delay at up to 30 μM (Figure 1B). 17-AAG was used at a dose of 1 μM for HCT116 cells and 10 μM for Hep3B cells in subsequent experiments.

Next, the time-dependent changes in cell cycle distribution were examined following 17-AAG treatment. The cell fraction in S-phase was decreased beginning at 18 h of 17-AAG treatment in both cell lines. The majority of HCT116 cells treated with 17-AAG were accumulated in G0/G1 phase while Hep3B cells accumulated mostly in G2/M phase at 24 h (Figure 1C and D).

17-AAG-induced changes in [3H]FLT uptake. Dose-dependent changes in [3H]FLT uptake were analyzed but the changes in cellular [3H]FLT uptake capacity (the percentage [3H]FLT uptake per 1×105 cells) induced by 17-AAG were not statistically significant both in HCT116 and Hep3B cells (Figure 2).

17-AAG-induced changes in TK1 expression and activity. To investigate why [3H]FLT uptake was unaffected despite growth arrest, TK1 expression was measured which is considered the gold standard of FLT uptake assessment. 17-AAG treatment significantly decreased the protein levels of TK1, cyclin A and cyclin B in HCT116 cells (Figure 3A). The decrease in TK1 expression was observed between 18 h to 36 h of treatment and was correlated with G0/G1 phase arrest (Figure 1C). In Hep3B cells, TK1, cyclin A and cyclin B expression was not significantly affected by 17-AAG treatment (Figure 3B). This suggests that the transcriptional machinery inducing TK1 and cyclin A during S-phase was impaired by 17-AAG in Hep3B cells. The possibility of post-translational modification-induced changes in TK1 activity was also tested but TK1 activity was not affected by 17-AAG treatment (Figure 3C). We verified a 17-AAG-induced inhibition of HSP90 by the reciprocal induction of HSP70 expression from 6 to 36 h in both cell lines (Figure 3A and B) (23).

The impact of 17-AAG treatment on nucleoside transporter and 5’3’-deoxyribonucleotidase 1 activities. To further elucidate the reason 17-AAG had no effect on [3H]FLT uptake by cytostatic HCT116 cells, we examined the cellular uptake and metabolic machinery for [3H]FLT. ENT1 is the main transporter of FLT into the intracellular space. The number of [3H]NBTI binding sites per cell which reflects the ENT1 activity, was 31,895±16,037 and 32,188±18,832 at 24 h in vehicle- and 1 μM 17-AAG–treated HCT116 cells, respectively (Figure 4A). Changes in ENT1 activity following 17-AAG treatment were not significantly different in HCT116 (Figure 4A) and Hep3B cells compared to control cells (data not shown). 5-FU is a positive regulator of ENT1 activity and was used as control (9).

Figure 3.
Figure 3.

Changes in TK1 expression during 17-AAG-induced growth arrest. TK1, Cyclin A, and cyclin B protein levels were analyzed in (A) HCT116 and (B) Hep3B cells treated with vehicle or 17-AAG for 0, 6, 18, 24 or 36 h. HSP70 induction was used as the positive control to verify 17-AAG-induced inhibition of HSP90. (C) TK1 activity was measured in Hep3B cells following treatment with vehicle or 10 μM 17-AAG for 24 h. Data are expressed as means±SD (n=4).

5’3’-Deoxyribonucleotidase1 dephosphorylates FLT monophosphate to FLT and promotes FLT excretion from cells in competition with TK1 activity (6, 12). The mRNA level of 5’3’-deoxyribonucleotidase1 was reported to be negatively correlated with [3H]FLT uptake (24). In-house quantitative analysis revealed that treatment of 1 μM 17-AAG in HCT116 cells decreased the mRNA levels of 5’3’-deoxyribonucleotidase1 by 44.7% at 24 h (p<0.05) (Figure 4B).

Discussion

Studies in [3H]FLT uptake have demonstrated its correlation with the cell's proliferative status, as assessed by the cell fraction in S-phase or the Ki67 index (25, 26), but also suggested the need for proper interpretation based on the retention mechanism (27). In this study, the [3H]FLT uptake was used to examine whether it could reflect the cytostatic effects of 17-AAG treatment. Since treatment with 17-AAG decreased TK1 expression, but also the expression of 5’3’-deoxyribonucleotidase1 during G0/G1 arrest in HCT116 cells, the effects of 17-AAG on [3H]FLT uptake may lead to no net change in [3H]FLT uptake. 17-AAG–induced G2/M arrest in Hep3B cells did not affect TK1 expression and activity, ENT1 activity nor [3H]FLT uptake. These results showed that 17-AAG may induce cell-specific and heterogeneous effects on the regulators of [3H]FLT uptake independent of growth arrest.

Suppression of proliferation is a common effect of HSP90 inhibitors but the underlying mechanisms are diverse because HSP90 is involved in multiple cellular pathways (13-16). We found that 17-AAG exerted heterogeneous effects on TK1 and 5’3’-deoxyribonucleotidase1 in two cell lines that exhibit representative cell-cycle arrest at G0/G1 phase or G2/M phase by 17-AAG. These cell models were based on a previous report of altered cell-cycle profiles resulting from HSP90 inhibition in a genetically diverse cancer cell panel (16, 22). Lyman et al. demonstrated that a lower dose of 17-AAG results in G1-phase accumulation due to disruption of client proteins, such as CDK2, CDK4/6 and cyclin D, which function during the G1/S transition. Accumulation of G0/G1-phase was also observed in this study using HCT116 cells. The p53 status is another determinant of M-phase accumulation (16), since mutant p53 is a target of HSP90. Application of an HSP90 inhibitor can destabilize the mutant p53 leading to subsequent loss of p21 activity. The lack of checkpoint surveillance at the G1/S and G2/M transitions leads to inappropriate entry to M-phase. Because Heb3B cells are deficient in p53 (28), their cell-cycle arrest phenotype may resemble that of a p53-mutant cell line. In addition, the decrease in cdc2 caused by 17-AAG leads to the functional loss of cdc2–cyclin B complex and G2/M-phase arrest in Hep3B cells (22).

Figure 4.
Figure 4.

The effect of 17-AAG on ENT1 and 5’3’-deoxynucleotidase1 in HCT116 cells. (A) HCT116 cells were treated with 0, 0.1, or 1 μM 17-AAG for 24 h and incubated with [3H]NBTI; ENT1-specific [3H]NBTI binding was then measured. 5-Fluorouracil was used as the positive control for ENT1 activity. (B) HCT116 cells treated with vehicle or 1 μM 17-AAG for 24 h were subjected to determination of 5’3’-deoxynucleotidase1 mRNA level by reverse transcription-real time PCR. Data are expressed as means±SD (n=4). Asterisk indicates p<0.05 compared to cells treated with vehicle only.

5’3’-Deoxynucleotidase1 catabolically antagonizes TK1 for regulation of the deoxythymidine versus deoxythymidine monophosphate pool in the cytosol (29). Although TK1 has been investigated most extensively as an S-phase-specific salvage enzyme, the biochemical pathway of 5’3’-deoxyribonucleotidase1 is poorly understood. In this study, we found for the first time that 17-AAG treatment decreased the mRNA levels of 5’3’-deoxynucleotidase1 in HCT116 cells. Our previous study demonstrated that the mRNA levels of 5’3’-deoxynucleotidase1 were negatively correlated with [3H]FLT uptake across 20 asynchronously growing lung and colon cancer cell lines (24). Therefore, the decrease in 5’3’-deoxynucleotidase1 expression by 17-AAG treatment could contribute to the increase in [3H]FLT uptake. However, the concomitant decrease in TK1 expression by 17-AAG treatment may result in decreased [3H]FLT uptake which may antagonize the effect of 5’3’-deoxynucleotidase1 and may lead to no net change in [3H]FLT uptake.

TK1 expression and activity is regulated at the transcriptional and post-transcriptional level during the cell cycle (30, 31). Transcription of TK1 is dramatically activated during late G1-S phase. Excess TK1 can be deactivated by cdc2 kinase phosphorylation during G2/M phases and subsequently degraded by the anaphase promoting complex/cyclosome (APC/C) in mitosis. In our study, TK1 protein levels were reduced by 17-AAG in HCT116 cells accompanied by cell cycle arrest at G0/G1 phase. On the contrary, 17-AAG treatment of Hep3B cells did not cause accumulation of TK1 protein nor changes in TK1 activity, despite cellular arrest at G2/M phase. This was unexpected based on our previous report that an anti-tubulin agent increased TK1 expression and cellular [3H]FLT uptake during G2/M phase arrest (10). TK1 may fail to be transcriptionally activated during G1-S phase due to HSP90 inhibition but in p53-mutant cells, like Hep3B, absence of G1-phase checkpoint surveillance may cause an abnormal progression to G2/M phase independent of TK1 induction and eventually cell death. Not only 17-AAG treatment didn't altered TK1 activity but it did not affect cellular [3H]FLT uptake as well.

In conclusion, our study showed that 17-AAG-induced cell-cycle arrest was accompanied by concomitant decrease in the expression of two antagonizing enzymes, TK1 and 5’3’-deoxynucleotidase1, in HCT116 cells. However, p53-mutant Hep3B cells underwent abnormal progression to G2/M phase without TK1 induction. These heterogeneous events failed to affect [3H]FLT uptake in relation to proliferation status. Thus, evaluation of tumor response to HSP90 inhibitors using [18F]FLT PET could be more appropriate once tumor cell death is induced after growth arrest.

Acknowledgements

This study was financially supported by a research fund of Chungnam National University (2014-2071-01).

  • Received September 20, 2016.
  • Revision received May 2, 2017.
  • Accepted May 5, 2017.

References

  1. ↵
    1. Hanahan D,
    2. Weinberg RA
    : Hallmarks of cancer: the next generation. Cell 144: 646-674, 2011.
    OpenUrlCrossRefPubMed
  2. ↵
    1. Colozza M,
    2. Azambuja E,
    3. Cardoso F,
    4. Sotiriou C,
    5. Larsimont D,
    6. Piccart MJ
    : Proliferative markers as prognostic and predictive tools in early breast cancer: where are we now? Ann Oncol 16: 1723-1739, 2005.
    OpenUrlAbstract/FREE Full Text
  3. ↵
    1. Polley MY,
    2. Leung SC,
    3. McShane LM,
    4. Gao D,
    5. Hugh JC,
    6. Mastropasqua MG,
    7. Viale G,
    8. Zabaglo LA,
    9. Penault-Llorca F,
    10. Bartlett JM,
    11. Gown AM,
    12. Symmans WF,
    13. Piper T,
    14. Mehl E,
    15. Enos RA,
    16. Hayes DF,
    17. Dowsett M,
    18. Nielsen TO,
    19. International Ki67 in Breast Cancer Working Group of the Breast International Group,
    20. North American Breast Cancer Group
    : An international Ki67 reproducibility study. J Natl Cancer Inst 105: 1897-1906, 2013.
    OpenUrlAbstract/FREE Full Text
  4. ↵
    1. Mankoff DA,
    2. Shields AF,
    3. Krohn KA
    : PET imaging of cellular proliferation. Radiol Clin North Am 43: 153-167, 2005.
    OpenUrlCrossRefPubMed
  5. ↵
    1. Bading JR,
    2. Shields AF
    : Imaging of cell proliferation: status and prospects. J Nucl Med 49(Suppl 2): 64S-80S, 2008.
    OpenUrlCrossRefPubMed
  6. ↵
    1. Grierson JR,
    2. Schwartz JL,
    3. Muzi M,
    4. Jordan R,
    5. Krohn KA
    : Metabolism of 3’-deoxy-3’-[F-18]fluorothymidine in proliferating A549 cells: validations for positron emission tomography. Nucl Med Biol 31: 829-837, 2004.
    OpenUrlCrossRefPubMed
  7. ↵
    1. Hu CM,
    2. Chang ZF
    : Mitotic control of dTTP pool: a necessity or coincidence? J Biomed Sci 14: 491-497, 2007.
    OpenUrlCrossRefPubMed
  8. ↵
    1. Lee SJ,
    2. Kim EJ,
    3. Lee HJ,
    4. Kim SY,
    5. Oh SJ,
    6. Ryu JS,
    7. Moon DH,
    8. Ahn JH,
    9. Kim SW
    : A pilot study for the early assessment of the effects of BMS-754807 plus gefitinib in an H292 tumor model by [(18)F]fluorothymidine-positron emission tomography. Invest New Drugs 31: 506-515, 2013.
    OpenUrlPubMed
  9. ↵
    1. Lee SJ,
    2. Kim SY,
    3. Chung JH,
    4. Oh SJ,
    5. Ryu JS,
    6. Hong YS,
    7. Kim TW,
    8. Moon DH
    : Induction of thymidine kinase 1 after 5-fluorouracil as a mechanism for 3’-deoxy-3’-[18F]fluorothymidine flare. Biochem Pharmacol 80: 1528-1536, 2010.
    OpenUrlCrossRefPubMed
  10. ↵
    1. Lee SJ,
    2. Kang HY,
    3. Kim SY,
    4. Chung JH,
    5. Oh SJ,
    6. Ryu JS,
    7. Kim SB,
    8. Kang JS,
    9. Park SK,
    10. Kim HM,
    11. Kim MH,
    12. Moon DH
    : Early assessment of tumor response to JAC106, an anti-tubulin agent, by 3’-deoxy-3’-[18F]fluorothymidine in preclinical tumor models. Eur J Nucl Med Mol Imaging 38: 1436-1448, 2011.
    OpenUrlCrossRefPubMed
  11. ↵
    1. Paproski RJ,
    2. Ng AM,
    3. Yao SY,
    4. Graham K,
    5. Young JD,
    6. Cass CE
    : The role of human nucleoside transporters in uptake of 3’-deoxy-3’-fluorothymidine. Mol pharmacol 74: 1372-1380, 2008.
    OpenUrlAbstract/FREE Full Text
  12. ↵
    1. Höglund L,
    2. Reichard P
    : Cytoplasmic 5’(3’)-nucleotidase from human placenta. J biol chem 265: 6589-6595, 1990.
    OpenUrlAbstract/FREE Full Text
  13. ↵
    1. Trepel J,
    2. Mollapour M,
    3. Giaccone G,
    4. Neckers L
    : Targeting the dynamic HSP90 complex in cancer. Nat Rev Cancer 10: 537-549, 2010.
    OpenUrlCrossRefPubMed
  14. ↵
    1. Proia DA,
    2. Bates RC
    : Ganetespib and HSP90: translating preclinical hypotheses into clinical promise. Cancer Res 74: 1294-1300, 2014.
    OpenUrlAbstract/FREE Full Text
  15. ↵
    1. Usmani SZ,
    2. Bona R,
    3. Li Z
    : 17 AAG for HSP90 inhibition in cancer – from bench to bedside. Curr Mol Med 9: 6546-6564, 2009.
    OpenUrl
  16. ↵
    1. Lyman SK,
    2. Crawley SC,
    3. Gong R,
    4. Adamkewicz JI,
    5. McGrath G,
    6. Chew JY,
    7. Choi J,
    8. Holst CR,
    9. Goon LH,
    10. Detmer SA,
    11. Vaclavikova J,
    12. Gerritsen ME,
    13. Blake RA
    : High-content, high-throughput analysis of cell cycle perturbations induced by the HSP90 inhibitor XL888. PLoS One 6: e17692, 2011.
    OpenUrlCrossRefPubMed
  17. ↵
    1. Monazzam A,
    2. Razifar P,
    3. Ide S,
    4. Rugaard Jensen M,
    5. Josephsson R,
    6. Blomqvist C,
    7. Langström B,
    8. Bergström M
    : Evaluation of the Hsp90 inhibitor NVP-AUY922 in multicellular tumour spheroids with respect to effects on growth and PET tracer uptake. Nucl Med Biol 36: 335-342, 2009.
    OpenUrlCrossRefPubMed
  18. ↵
    1. Bergstrom M,
    2. Monazzam A,
    3. Razifar P,
    4. Ide S,
    5. Josephsson R,
    6. Langstrom B
    : PET tracer uptake, and treatment effects of the Hsp90 inhibitor NVP-AUY922. J Nucl Med 49: 1204-1210, 2008.
    OpenUrlAbstract/FREE Full Text
  19. ↵
    1. Mankoff DA,
    2. Eary JF,
    3. Link JM,
    4. Muzi M,
    5. Rajendran JG,
    6. Spence AM,
    7. Krohn KA
    : Tumor-specific positron emission tomography imaging in patients: [18F] fluorodeoxyglucose and beyond. Clin Cancer Res 13: 3460-3469, 2007.
    OpenUrlAbstract/FREE Full Text
  20. ↵
    1. Lee SJ,
    2. Yeo JS,
    3. Lee HJ,
    4. Lee EJ,
    5. Kim SY,
    6. Jang SJ,
    7. Lee JJ,
    8. Ryu JS,
    9. Moon DH
    : Thymidine phosphorylase influences [18F]fluorothymidine uptake in cancer cells and patients with non-small cell lung cancer. Eur J Nucl Med Mol Imaging 41: 1327-1335, 2014.
    OpenUrl
  21. ↵
    1. Lee EJ,
    2. Lee SJ
    : Etoposide increases equilibrative nucleoside transporter 1 activity and fluorothymidine uptake: screening of 60 cytotoxic agents. Oncol Rep 29: 763-770, 2013.
    OpenUrl
  22. ↵
    1. Watanabe G,
    2. Behrns KE,
    3. Kim JS,
    4. Kim RD
    : Heat shock protein 90 inhibition abrogates hepatocellular cancer growth through cdc2-mediated G2/M cell cycle arrest and apoptosis. Cancer Chemother Pharmacol 64: 433-443, 2009.
    OpenUrlCrossRefPubMed
  23. ↵
    1. Banerji U,
    2. Walton M,
    3. Raynaud F,
    4. Grimshaw R,
    5. Kelland L,
    6. Valenti M,
    7. Judson I,
    8. Workman P
    : Pharmacokinetic-pharmacodynamic relationships for the heat shock protein 90 molecular chaperone inhibitor 17-allylamino, 17-demethoxygeldanamycin in human ovarian cancer xenograft models. Clin Cancer Res 11: 7023-7032, 2005.
    OpenUrlAbstract/FREE Full Text
  24. ↵
    1. Lee SJ,
    2. Lee HJ,
    3. Moon DH
    : Quantitative analysis of thymidine kinase 1 and 5’(3’)-deoxyribonucleotidase mRNA expression: the role of fluorothymidine uptake. Anticancer Res 31: 2135-2139, 2011.
    OpenUrlAbstract/FREE Full Text
  25. ↵
    1. Chalkidou A1,
    2. Landau DB,
    3. Odell EW,
    4. Cornelius VR,
    5. O'Doherty MJ,
    6. Marsden PK
    : Correlation between Ki-67 immunohistochemistry and 18F-fluorothymidine uptake in patients with cancer: A systematic review and meta-analysis. Eur J Cancer 48: 3499-3513, 2012.
    OpenUrlCrossRefPubMed
  26. ↵
    1. Rasey JS1,
    2. Grierson JR,
    3. Wiens LW,
    4. Kolb PD,
    5. Schwartz JL
    : Validation of FLT uptake as a measure of thymidine kinase-1 activity in A549 carcinoma cells. J Nucl Med 43: 1210-1217, 2002.
    OpenUrlAbstract/FREE Full Text
  27. ↵
    1. Shields AF
    : PET imaging of tumor growth: not as easy as it looks. Clin Cancer Res 18: 1189-1191, 2012.
    OpenUrlAbstract/FREE Full Text
  28. ↵
    1. Liu K,
    2. Shi Y,
    3. Guo XH,
    4. Ouyang YB,
    5. Wang SS,
    6. Liu DJ,
    7. Wang AN,
    8. Li N,
    9. Chen DX
    : Phosphorylated AKT inhibits the apoptosis induced by DRAM-mediated mitophagy in hepatocellular carcinoma by preventing the translocation of DRAM to mitochondria. Cell Death Dis 5: e1078, 2014.
    OpenUrl
  29. ↵
    1. Rampazzo C,
    2. Johansson M,
    3. Gallinaro L,
    4. Ferraro P,
    5. Hellman U,
    6. Karlsson A,
    7. Reichard P,
    8. Bianchi V
    : Mammalian 5’(3’)-deoxyribonucleotidase, cDNA cloning, and overexpression of the enzyme in Escherichia coli and mammalian cells. J Biol Chem 275: 5409-5415, 2000.
    OpenUrlAbstract/FREE Full Text
  30. ↵
    1. Hu CM,
    2. Chang ZF
    : Mitotic control of dTTP pool: a necessity or coincidence? J Biomed Sci 14: 491-497, 2007.
    OpenUrlCrossRefPubMed
  31. ↵
    1. Ke PY,
    2. Kuo YY,
    3. Hu CM,
    4. Chang ZF
    : Control of dTTP pool size by anaphase promoting complex/cyclosome is essential for the maintenance of genetic stability. Genes Dev 19: 1920-1933, 2005.
    OpenUrlAbstract/FREE Full Text
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17-Allylamino-17-demethoxygeldanamycin-induced Changes in [18F]Fluorothymidine Uptake
HANG JUNG LEE, DO HYUNG KIM, SEUNG JIN LEE
Anticancer Research Jun 2017, 37 (6) 2993-2999;
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