sirolimus and sepantronium

YM155, a small molecule inhibitor of survivin, has been studied in many tumors. It has been shown that YM155 inhibited oral squamous cell carcinoma through promoting apoptosis and autophagy and inhibiting proliferation. It was found that YM155 also inhibited the oral squamous cell carcinoma-mediated angiogenesis through the inactivation of the mammalian target of rapamycin pathway. Rapamycin, a mammalian target of rapamycin inhibitor, played an important role in the proliferation and angiogenesis of oral squamous cell carcinoma cell lines. In our study, cell proliferation assay, transwell assay, tube formation assay, and western blot assay were used to investigate the synergistic effect of rapamycin on YM155 in oral squamous cell carcinoma. Either in vitro or in vivo, rapamycin and YM155 exerted a synergistic effect on the inhibition of survivin and vascular endothelial growth factor through mammalian target of rapamycin pathway. Overall, our results revealed that low-dose rapamycin strongly promoted the sensitivity of oral squamous cell carcinoma cell lines to YM155.

Topics: Animals; Antineoplastic Combined Chemotherapy Protocols; Apoptosis; Autophagy; Carcinoma, Squamous Cell; Cell Line, Tumor; Cell Proliferation; Gene Expression Regulation, Neoplastic; Humans; Imidazoles; Inhibitor of Apoptosis Proteins; Mice; Mouth Neoplasms; Naphthoquinones; Neovascularization, Pathologic; Sirolimus; Survivin; Vascular Endothelial Growth Factor A; Xenograft Model Antitumor Assays

Elevated expression of the antiapoptotic factor survivin has been implicated in cancer cell survival and disease progression. However, its specific contribution to renal cell carcinoma (RCC) pathogenesis is not well defined. We investigated the roles of survivin in RCC tumor progression, resistance to mTOR inhibitors, and evaluated the therapeutic activity of the survivin suppressant YM155 in RCC models. Here, we report that survivin expression levels were significantly higher in RCC cell lines compared with normal renal cells. Stable targeted knockdown of survivin completely abrogated the ability of 786-O RCC tumors to grow in mice, thus demonstrating its importance as a regulator of RCC tumorigenesis. We next explored multiple strategies to therapeutically inhibit survivin function in RCC. Treatment with the mTOR inhibitor temsirolimus partially diminished survivin levels and this effect was augmented by the addition of YM155. Further analyses revealed that, in accordance with their combined anti-survivin effects, YM155 significantly improved the anticancer activity of temsirolimus in a panel of RCC cell lines in vitro and in xenograft models in vivo. Similar to pharmacologic inhibition of survivin, shRNA-mediated silencing of survivin expression not only inhibited RCC tumor growth, but also significantly sensitized RCC cells to temsirolimus therapy. Subsequent experiments demonstrated that the effectiveness of this dual survivin/mTOR inhibition strategy was mediated by a potent decrease in survivin levels and corresponding induction of apoptosis. Our findings establish survivin inhibition as a novel approach to improve RCC therapy that warrants further investigation.

Topics: Animals; Antineoplastic Combined Chemotherapy Protocols; Apoptosis; Carcinoma, Renal Cell; Cell Proliferation; Cell Survival; Disease Progression; Drug Synergism; Female; Gene Expression Regulation, Neoplastic; Imidazoles; Immunoblotting; Immunohistochemistry; Inhibitor of Apoptosis Proteins; Kidney Neoplasms; Mice, Inbred BALB C; Mice, Nude; Naphthoquinones; Proliferating Cell Nuclear Antigen; Reverse Transcriptase Polymerase Chain Reaction; RNA Interference; Sirolimus; Survivin; Xenograft Model Antitumor Assays

Survivin is overexpressed in transitional cell carcinoma (TCC), the most common type of bladder cancer. Previous reports demonstrated that knockdown of survivin by siRNA induced apoptosis of TCC cells. The present study evaluated the therapeutic effects of sepantronium bromide (YM155), a novel small molecule survivin inhibitor under clinical trials, on TCC cells in vitro. BFTC905, a grade III TCC cell line derived from a patient of blackfoot disease in Taiwan, was the most gemcitabine-resistant cell line when compared to BFTC909, TSGH8301 and T24 in cytotoxicity assay, resulting from upregulation of securin and bcl-2 after gemcitabine treatment. YM155 caused potent concentration‑dependent cytotoxicity in 4 TCC cell lines (IC50s ≤20 nM), but exhibited no cytotoxicity in survivin-null primary human urothelial cells. For BFTC905 cells, addition of gemcitabine and/or cisplatin, the standard TCC chemotherapy regimen, to YM155 did not exert additive cytotoxic effects. Molecular analyses indicated that YM155 inhibited the proliferation of BFTC905 cells by increasing p27kip1, suppressing Ki-67, and inducing quiescence. In addition, YM155 elicited apoptosis manifested with DNA fragmentation through suppressing the expression of survivin, securin and bcl-2. Furthermore, YM155 induced autophagy in BFTC905 cells as autophagic inhibitor, 3-methyladenine, attenuated YM155-induced LC3B-II levels and reversed the cytotoxicity of YM155. mTOR inhibitors sirolimus and everolimus did not increase YM155-induced expression of LC3B-II nor augment YM155-induced cytotoxicity. These results indicate that YM155 exerts its lethal effect on BFTC905 cells via apoptotic and autophagic death pathways and suggest that YM155 may be a potential drug for the therapy of gemcitabine-resistant bladder cancer.

Topics: Adenine; Antimetabolites, Antineoplastic; Apoptosis; Autophagy; Carcinoma, Transitional Cell; Cell Line, Tumor; Cell Proliferation; Cyclin-Dependent Kinase Inhibitor p27; Deoxycytidine; DNA Fragmentation; Drug Resistance, Neoplasm; Everolimus; Gemcitabine; Humans; Imidazoles; Inhibitor of Apoptosis Proteins; Ki-67 Antigen; Microtubule-Associated Proteins; Naphthoquinones; Proto-Oncogene Proteins c-bcl-2; Securin; Sirolimus; Survivin; TOR Serine-Threonine Kinases; Urinary Bladder Neoplasms; Urothelium

Mammalian target of rapamycin inhibitor has exhibited promising anticancer activity for the treatment of renal cell carcinoma (RCC). However, many patients acquire resistance to therapeutic agents leading to treatment failure. The objective of this study was to determine whether treatment with YM155, a novel small molecule inhibitor of survivin, could reverse rapamycin resistance in a rapamycin-resistant RCC.. We induced a rapamycin-resistant clear cell carcinoma cell line (Caki-1-RapR). We showed that survivin gene expression was significantly up-regulated in Caki-1-RapR compared with that in its parent cells (Caki-1). Therefore, we hypothesized that targeting of survivin in Caki-1-RapR could reverse the resistant phenotype in tumor cells, thereby enhancing the therapeutic efficacy of rapamycin. We used both in vitro and in vivo models to test the efficacy of YM155 either as a single agent or in combination with rapamycin.. In Caki-1-RapR cells, YM155 significantly decreased survivin gene and protein expression levels and cell proliferation in a dose-dependent manner in vitro. In addition, YM155 treatment significantly reversed rapamycin resistance in cancer cells. In a nude mouse tumor xenograft model, YM155 significantly inhibited the growth of Caki-1-RapR tumor. In addition, YM155 significantly enhanced the antitumor effects of rapamycin in Caki-1-RapR tumor.. Our results suggest a potentially novel strategy to use YM155 to overcome the resistance in tumor cells, thereby enhancing the effectiveness of molecular target therapy in RCC.

Topics: Animals; Antibiotics, Antineoplastic; Apoptosis; Blotting, Western; Carcinoma, Renal Cell; Cell Line, Tumor; Cell Proliferation; Dose-Response Relationship, Drug; Drug Resistance, Neoplasm; Gene Expression Regulation, Neoplastic; Humans; Imidazoles; Immunohistochemistry; Inhibitor of Apoptosis Proteins; Kidney Neoplasms; Mice; Mice, Nude; Naphthoquinones; Real-Time Polymerase Chain Reaction; Sirolimus; Survivin; Up-Regulation; Xenograft Model Antitumor Assays