ABSTRACT
OBJECTIVE: Cisplatin (CDDP)-based chemotherapy is a first-line, drug regimen for muscle-invasive bladder cancer (BC) and metastatic bladder cancer. Clinically, resistance to CDDP restricts the clinical benefit of some bladder cancer patients. AT-rich interaction domain 1A (ARID1A) gene mutation occurs frequently in bladder cancer; however, the role of CDDP sensitivity in BC has not been studied. METHODS: We established ARID1A knockout BC cell lines using CRISPR/Cas9 technology. IC50 determination, flow cytometry analysis of apoptosis, and tumor xenograft assays were performed to verify changes in the CDDP sensitivity of BC cells losing ARID1A. qRT-PCR, Western blotting, RNA interference, bioinformatic analysis, and ChIP-qPCR analysis were performed to further explore the potential mechanism of ARID1A inactivation in CDDP sensitivity in BC. RESULTS: It was found that ARID1A inactivation was associated with CDDP resistance in BC cells. Mechanically, loss of ARID1A promoted the expression of eukaryotic translation initiation factor 4A3 (EIF4A3) through epigenetic regulation. Increased expression of EIF4A3 promoted the expression of hsa_circ_0008399 (circ0008399), a novel circular RNA (circRNA) identified in our previous study, which, to some extent, showed that ARID1A deletion caused CDDP resistance through the inhibitory effect of circ0008399 on the apoptosis of BC cells. Importantly, EIF4A3-IN-2 specifically inhibited the activity of EIF4A3 to reduce circ0008399 production and restored the sensitivity of ARID1A inactivated BC cells to CDDP. CONCLUSION: Our research deepens the understanding of the mechanisms of CDDP resistance in BC and elucidates a potential strategy to improve the efficacy of CDDP in BC patients with ARID1A deletion through combination therapy targeting EIF4A3.
Subject(s)
Cisplatin , Drug Resistance, Neoplasm , Urinary Bladder Neoplasms , Humans , Cell Line, Tumor , Cisplatin/pharmacology , Cisplatin/therapeutic use , DEAD-box RNA Helicases/genetics , DEAD-box RNA Helicases/metabolism , DEAD-box RNA Helicases/pharmacology , DNA-Binding Proteins/genetics , DNA-Binding Proteins/metabolism , Drug Resistance, Neoplasm/genetics , Epigenesis, Genetic , Eukaryotic Initiation Factor-4A/genetics , Eukaryotic Initiation Factor-4A/metabolism , Eukaryotic Initiation Factor-4A/pharmacology , Transcription Factors/genetics , Transcription Factors/metabolism , Transcription Factors/pharmacology , Urinary Bladder Neoplasms/drug therapy , Urinary Bladder Neoplasms/geneticsABSTRACT
Circular RNAs (circRNAs) have been reported to play an important role in the progression of numerous types of human cancer. The aim of the present study was to determine the effects of circRNA_0074027 (circ_0074027) in gastric cancer (GC), and to elucidate the underlying mechanisms of action. For this purpose, the expression of circ_0074027 in GC cell lines was detected using reverse transcription-quantitative PCR. The effects of circ_0074027 on the proliferation and migration of GC cells were investigated using Cell Counting Kit-8 (CCK-8) and Transwell assays, respectively. The Circular RNA Interactome was used to predict that eukaryotic translation initiation factor 4A3 (EIF4A3) could bind to circ_0074027, which was confirmed using an RNA immunoprecipitation assay. The expression and function of EIF4A3 in GC cells were also determined using western blot analysis, as well as CCK-8, colony formation, wound-healing and Transwell assays. The results revealed that circ_0074027 was highly expressed in GC cell lines in the form of a closed loop. In addition, circ_0074027-knockdown inhibited cellular proliferation and motility. Furthermore, EIF4A3 was predicted to be targeted by circ_0074027 and a positive association was identified between them. The overexpression of EIF4A3 reversed the effects of circ_0074027 on the proliferation and motility of GC cells. In conclusion, the findings of the present study demonstrated that circ_0074027 bound to EIF4A3 and promoted the proliferation and migration capacities of GC cells.