Prevention of BMS-777607-induced polyploidy/senescence by mTOR inhibitor AZD8055 sensitizes breast cancer cells to cytotoxic chemotherapeutics.
Targeted inhibition of MET/RON signaling by tyrosine kinase inhibitor BMS-777607 for cancer treatment is currently under clinical trials. We have previously shown that BMS-777607 induces chemoresistance in vitro by causing polyploidy, which hampers therapeutic efficacy. Here, we studied polyploidy-associated senescence induced by BMS-777607 in breast cancer cells and its prevention by mTOR inhibitor AZD8055, leading to increased chemosensitivity. In breast cancer T-47D and ZR-75-1 cells, BMS-777607 induced phenotypic changes including enlarged cellular size, flattened morphology, increased DNA content, and activity of senescence-associated β-galactosidase. These changes were accompanied by increased p21/WAF1 expression and decreased Retinoblastoma Ser(780) phosphorylation, indicating that BMS-777607 induces not only polyploidy but also senescence. The appearance of senescence was associated with polyploidy in which β-galactosidase is exclusively expressed in polyploid cells. Survivin expression was increased in polyploid/senescent cells as analyzed by Western blotting. Increased survivin accumulated both in the nucleus and cytoplasm and dissociated with condensed DNA and mitotic spindle at the metaphase. Abnormal accumulation of survivin also rendered polyploid/senescent cells insensitive to cytotoxic activities of YM155, a DNA damaging agent with a suppressive effect on survivin gene transcription. AZD8055, a specific mTOR inhibitor, effectively prevented BMS-777607-induced polyploidy and senescence and restored survivin expression and its nuclear localization to normal levels. Although a synergism was not observed, BMS-777607 plus AZD8055 increased cancer cell sensitivity toward different cytotoxic chemotherapeutics. In conclusion, BMS-777607-induced chemoresistance is associated with cell polyploidy and senescence. Inhibition of mTOR signaling by AZD8055 prevents BMS-777607-induced polyploidy/senescence and increases breast cancer cell chemosensitivity.
Cancer Biology Research Center, School of Pharmacy, Texas Tech University Health Sciences Center, Amarillo, TX 79106, USA; Department of Biomedical Sciences, School of Pharmacy, Texas Tech University Health Sciences Center, Amarillo, TX 79106, USA. Electronic address: sharad.sharama@ttuhsc.edu.
Sharad
S
Sharma
State Key Laboratory for Diagnosis & Treatment of Infectious Diseases and Department of Neurosurgery, First Affiliated Hospital of Zhejiang University School of Medicine, Hangzhou, Zhejiang 310003, PR China. Electronic address: yaohangping@zju.edu.cn.
Hang-Ping
HP
Yao
State Key Laboratory for Diagnosis & Treatment of Infectious Diseases and Department of Neurosurgery, First Affiliated Hospital of Zhejiang University School of Medicine, Hangzhou, Zhejiang 310003, PR China. Electronic address: zhouyq56@hotmail.com.
Yong-Qing
YQ
Zhou
Department of Molecular Cell Biology and Toxicology, School of Public Health, Nanjing Medical University, Nanjing, Jiangsu 210029, PR China. Electronic address: jwzhou@njmu.edu.cn.
Jianwei
J
Zhou
Cancer Biology Research Center, School of Pharmacy, Texas Tech University Health Sciences Center, Amarillo, TX 79106, USA; Department of Pharmaceutical Sciences, School of Pharmacy, Texas Tech University Health Sciences Center, Amarillo, TX 79106, USA. Electronic address: Ruiwen.zhang@ttuhsc.edu.
Ruiwen
R
Zhang
Cancer Biology Research Center, School of Pharmacy, Texas Tech University Health Sciences Center, Amarillo, TX 79106, USA; Department of Biomedical Sciences, School of Pharmacy, Texas Tech University Health Sciences Center, Amarillo, TX 79106, USA. Electronic address: minghai.wang@ttuhsc.edu.
Ming-Hai
MH
Wang
D000375:Aging / Q000187:drug effects; D000631:Aminopyridines / Q000494:pharmacology*; D001940:Breast / Q000187:drug effects / Q000378:metabolism / Q000473:pathology; D001943:Breast Neoplasms / Q000188:drug therapy* / Q000378:metabolism / Q000473:pathology; D045744:Cell Line, Tumor; D019008:Drug Resistance, Neoplasm / Q000187:drug effects; D005260:Female; D006801:Humans; D009025:Morpholines / Q000494:pharmacology*; D011123:Polyploidy; D047428:Protein Kinase Inhibitors / Q000494:pharmacology*; D011728:Pyridones / Q000494:pharmacology*; D015398:Signal Transduction / Q000187:drug effects; D058570:TOR Serine-Threonine Kinases / Q000037:antagonists & inhibitors* / Q000378:metabolism
D000631:Aminopyridines; D009025:Morpholines; C550356:N-(4-(2-amino-3-chloropyridin-4-yloxy)-3-fluorophenyl)-4-ethoxy-1-(4-fluorophenyl)-2-oxo-1,2-dihydropyridine-3-carboxamide; D047428:Protein Kinase Inhibitors; D011728:Pyridones; C546624:(5-(2,4-bis((3S)-3-methylmorpholin-4-yl)pyrido(2,3-d)pyrimidin-7-yl)-2-methoxyphenyl)methanol; D058570:TOR Serine-Threonine Kinases
Breast cancer; Chemosensitivity; Polyploidy; Receptor tyrosine kinase; Senescence; Small molecule inhibitor; mTOR signaling