Identification of the circRNA-miRNA-mRNA Regulatory Network in Bladder Cancer by Bioinformatics Analysis

Circ_0000758 Facilitates Bladder Cancer Cell Growth, Migration and Angiogenesis Via Severing as miR-1236-3p Sponge

Circular RNA (circRNA) has been reported to regulate the development of bladder cancer (BCa). However, the role of circ_0000758 in BCa progression is unknown. Circ_0000758 and miR-1236-3p expression, as well as ZEB2 mRNA expression were determined by qRT-PCR. BCa cell biological functions were determined by MTT assay, EdU assay, flow cytometry, wound healing assay and tube formation assay. Protein expression was detected by western blot analysis. RNA pull-down assay and dual-luciferase reporter assay were used to confirm RNA interaction. Xenograft mice models were constructed to assess the effect of circ_0000758 on BCa tumor growth. Circ_0000758 had increased expression in BCa tissues and cells. Circ_0000758 silencing could inhibit BCa cell growth, migration, angiogenesis in vitro, and tumor growth in vivo. Circ_0000758 served as a molecular sponge for miR-1236-3p, and miR-1236-3p inhibitor reversed circ_0000758 knockdown-mediated the inhibition effect on BCa cell progression. ZEB2 was targeted by miR-1236-3p, and its overexpression also revoked the suppressive effect of miR-1236-3p on BCa cell growth, migration, and angiogenesis. Besides, circ_0000758 knockdown also restrained BCa tumor growth. Circ_0000758 might promote BCa cell growth, migration, and angiogenesis by regulating the miR-1236-3p/ZEB2 axis.

Genetic variants of antioxidant enzymes and environmental exposures as molecular biomarkers associated with the risk and aggressiveness of bladder cancer

Bladder cancer (BC) is one of the top 10 most common tumours worldwide; however, no molecular markers are currently available for tumour management and follow-up. BC could benefit from molecular biomarkers in environmental disease, which provide mechanistic understanding of individual susceptibility to exposure-related cancers and allow characterizing genetic alterations in the molecular pathway for malignancy. This case-control study performed a molecular analysis in 99 BC and 125 controls. Buccal swabs were collected to assess SNPs in eleven genes coding for xenobiotic detoxification enzymes, cellular antioxidant defences, and hormone synthesis and signalling (NAT2 (rs1801280), GPX1 (rs1050450 and rs17650792), TXNRD1 (rs7310505), PRDX3 (rs3740562), PON1 (rs662), SOD1 (rs10432782), SOD2 (rs4880), CAT (rs1001179), CYP17A1 (rs743572) and ESR1 (rs746432)). A structured questionnaire was administered to study participants to assess environmental and dietary chemical exposures. Several miRNAs associated with BC and detoxification/antioxidant pathways were analysed in a subsample of the study population, including miR-93-5p, miR-221-3p, miR-126, miR-27a-3p, miR-193b, and miR-193a-5p. Levels of selected environmental pollutants (polycyclic aromatic hydrocarbons and endocrine disrupting chemicals) were determined in urine from a subsample of BC cases and controls. We found that CYP17A1, CAT, SOD1, ESR1, PON1, and GPX1 (rs17650792) were associated with BC risk. Furthermore, exposure to smoke and/or dust, and alcohol intake were identified as risk factors for BC. Increased urinary levels of benzo[a]pyrene and bisphenol A were observed in BC patients relative to controls, along with an increased expression of miR-193b, miR-27a and miR-93-5p in BC. Nevertheless, further studies with a larger sample size are warranted to confirm these exploratory results. This study also shows that the combination of genetic markers (PON1 and CYP17A1) and miRNA (miR-221-3p and miR-93-5p) open a new scenario in the use of non-invasive biomarkers in the stratification of BC to guide personalized medicine, which is extremely urged in the current clinical setting.