Cisplatin induces protective autophagy through activation of BECN1 in human bladder cancer cells

Abstract

PurposeCisplatin-based chemotherapy is the first line treatment for several cancers including bladder cancer (BC). Autophagy induction has been implied to contribute to cisplatin resistance in ovarian cancer; and a high basal level of autophagy has been demonstrated in human bladder tumors. Therefore, it is reasonable to speculate that autophagy may account for the failure of cisplatin single treatment in BC. This study investigated whether cisplatin induces autophagy and the mechanism involved using human BC cell lines.Materials and methodsHuman BC cells (5637 and T24) were used in this study. Cell viability was detected using water soluble tetrazolium-8 reagents. Autophagy induction was detected by monitoring the levels of light chain 3 (LC3)-II and p62 by Western blot, LC3-positive puncta formation by immunofluorescence, and direct observation of the autophagolysosome (AL) formation by transmission electron microscopy. Inhibitors including bafilomycin A1 (Baf A1), chloroquine (CQ), and shRNA-based lentivirus against autophagy-related genes (ATG7 and ATG12) were utilized. Apoptosis level was detected by caspase 3/7 activity and DNA fragmentation.ResultsCisplatin decreased cell viability and induced apoptosis of 5637 and T24 cells in a dose-and time-dependent manner. The increased LC3-II accumulation, p62 clearance, the number of LC3-positive puncta, and ALs in cisplatin-treated cells suggested that cisplatin indeed induces autophagy. Inhibition of cisplatin-induced autophagy using Baf A1, CQ, or ATG7/ATG12 shRNAs significantly enhanced cytotoxicity of cisplatin toward BC cells. These results indicated that cisplatin induced protective autophagy which may contribute to the development of cisplatin resistance and resulted in treatment failure. Mechanistically, upregulation of beclin-1 (BECN1) was detected in cisplatin-treated cells, and knockdown of BECN1 using shRNA attenuated cisplatin-induced autophagy and subsequently enhanced cisplatin-induced apoptosis.ConclusionCollectively, the study results indicated that cisplatin-induced autophagy is mediated by BECN1 in BC cells. Therefore, combinative treatment using cisplatin and autophagy inhibitors could potentially overcome cisplatin resistance related to autophagy induction.

Silencing circular RNA UVRAG inhibits bladder cancer growth and metastasis by targeting the microRNA‐223/fibroblast growth factor receptor 2 axis

“…Recent studies have reported that UVRAG not only promotes Beclin‐1‐mediated autophagy, but it also facilitates endosome/autophagosome maturation . Activation of autophagy can increase chemo‐ and radiotherapy resistance in bladder cancer . We also found that high expression of UVRAG predicted poor prognosis, which was consistent with the role of circUVRAG.…”

“…18,19 Activation of autophagy can increase chemo-and radiotherapy resistance in bladder cancer. [20][21][22] We also found that high expression of UVRAG predicted poor prognosis, which was consistent with the role of circUVRAG.…”

Dual Inhibition of PIK3C3 and FGFR as a New Therapeutic Approach to Treat Bladder Cancer

“…Cell culture, antibodies, and reagents Cisplatin-resistant bladder cancer cell line, N/P (14), was a gift from Dr. Tzyh-Chyuan Hour (Kaohsiung Medical University) (25), and CWR22Rv1-GFP-LC3 cells was from Dr. Hsing-Jien Kung in 2015 (Taipei Medical University) (26). RT-112 and RT-4 cells were purchased and cultured as previously described (24), and were not further authenticated by us.…”

“…Importantly, autophagy is reportedly related to bladder cancer grade, and inhibition of high basal level of autophagy results in apoptotic cell death (12,13). Meanwhile, autophagy also contributes to cisplatin resistance in bladder cancer cells (14). Therefore, the discovery of novel autophagy inhibitors should provide therapeutic potential to patients with bladder cancer.…”

ERas Enhances Resistance to Cisplatin-Induced Apoptosis by Suppressing Autophagy in Gastric Cancer Cell

“…In addition to apoptosis, cisplatin has been reported to induce autophagy in lung, esophageal, and ovarian cancer cells (Xu et al, 2012;Yu et al, 2014;Wu et al, 2015). Moreover, low dose of cisplatin also could induce autophagy in lung-cancer cells (5 µM) and bladder cancer cells (6.25 µM) (Cho et al, 2014;Lin et al, 2017). However, inhibitor of autophagy promotes cisplatininduced apoptosis (Xu et al, 2012;Chen et al, 2018).…”