Role And Mechanism Of Cancer Stem-like Cells In The Progression And Chemotherapy Resistance Of Bladder Cancer

?Background?Bladder cancer is one of the most common malignant tumors in the world.Although surgical resection is the first choice for patients with bladder cancer,some tumors will recur and progress to muscle-invasive bladder cancer and metastatic bladder cancer.In addition,chemotherapy resistance is prone to systemic chemotherapy.These factors are associated with poor prognosis of patients with bladder cancer.Cancer stem cell-like cells are a subset of cancer cells,which have strong stem cell properties,including self-renewal and tumor-initiating ability.Cancer stem cell-like cells are closely related to the heterogeneity,progression and chemoresistance of various tumors,including bladder cancer.Therefore,revealing the molecular mechanisms that regulate cancer stem cell-like cells may help to discover new therapies for advanced and chemotherapy-resistant bladder cancer and improve the prognosis of patients with bladder cancer.Many studies have reported that bladder cancer stem cell-like cells can be isolated and sorted by certain markers and many signaling pathways are involved in the regulation of bladder cancer stem cell-like cells' self-renewal,chemoresistance and tumor initiation characteristics.However,the underlying molecular mechanisms that maintain the stem cell properties of bladder cancer stem-like cells have not been fully elucidated.Studies have shown that YAP--the key molecule of the Hippo pathway,plays a crucial role in tumor initiation and self-renewal in stem cells and various cancer stem cell-like cells,but the role of YAP in bladder cancer stem cell-like cells and its related molecular mechanism is not yet clear.Previous studies have shown that the epithelial marker OV6 can be used as a marker for epithelial-derived malignant cancer stem cell-like cells.We found that OV6 positive bladder cancer cells have strong stem cell characteristics,while YAP can promotes the self-renewal,invasion,migration and drug resistance of OV6-positive bladder cancer stem-like cells through the YAP/TEAD1/PDGF-BB/PDGFR autocrine loop.?Objectives?1.To investigate the correlation between OV6 expression level in bladder cancer tissues and the heterogeneity and prognosis of patients with bladder cancer.2.To investigate whether OV6 positive bladder cancer cells possess cancer stem cell-like cell characteristics.3.To investigate the intrinsic molecular mechanism of maintaining the characteristics of bladder cancer stem cell-like cells,providing a new basis for reversal of chemotherapy resistance of bladder cancer.?Methods and Results?1.The expression of epithelial marker OV6 in human bladder cancer samples was detected by immunohistochemical staining and the correlation between OV6 expression level and clinicopathological information and prognosis of bladder cancer patients was analyzed.The results showed that high expression of OV6 was positively correlated with disease progression and poor prognosis in patients with bladder cancer.Univariate and multivariate cox regression analysis showed that OV6 expression was an independent risk factor for prognosis in patients with bladder cancer.2.OV6-positive and OV6-negative bladder cancer cells were separated by magnetic separation(MACS).The characteristics of cancer stem cells of the two groups were analyzed by sphere-forming experiments,tumor-forming experiments,and drug resistance experiments.The results showed that compared with OV6-negative cells,OV6-positive bladder cancer cells had significant cancer stem cell characteristics,including self-renewal,tumor initiation and chemotherapy resistance abilities.3.The intrinsic molecular mechanism of OV6-positive bladder cancer stem cell-like cells was further confirmed by transcriptome sequencing,cytokine antibody microarray detection,co-immunoprecipitation(co-IP),chromatin immunoprecipitation(ChIP)and other experiments.An orthotopic transplantation model of bladder cancer was established to evaluate the reversal effect of YAP inhibitors(Verteporfin)and PDGFR inhibitors(CP-673451)on cisplatin resistance in OV6-positive bladder cancer stem cell-like cells.The results indicated that the key molecule YAP of Hippo pathway plays an important role in maintaining the stem cell characteristics of OV6-positive bladder cancer stem cell-like cells.YAP promotes PDGFB transcription by recruiting transcription factor TEAD1.Meanwhile,through its receptor PDGFR,the autocrine PDGF-BB factor of cancer cells can further stabilize YAP and promote the transcriptional regulation of YAP.In addition,verteporfin or CP-673451 can block the YAP/TEAD1/PDGF-BB/PDGFR autocrine signaling loop,thereby inhibiting cisplatin resistance in OV6-positive bladder cancer stem-like cells in the orthotopic transplantation model of bladder cancer.?Conclusion?In this study,we found that high expression of OV6 is positively associated with disease progression and poor prognosis in patients with bladder cancer.OV6 may be an important predictor of disease progression and prognosis in patients with bladder cancer.OV6-positive bladder cancer cells have significant cancer stem-like cell characteristics.The YAP/TEAD1/PDGF-BB/PDGFR autocrine loop is an important molecular mechanism to maintain the cancer stem-like cell characteristics of OV6-positive bladder cancer stem cell-like cells.Target the autocrine loop can reverse the resistance of OV6-positive bladder cancer cells to cisplatin in bladder cancer orthotopic transplantation model,providing a theoretical basis for improving efficacy of cisplatin in bladder cancer and ultimately improving the prognosis of patients.