Role of miRNAs, miR-135b-5p & miR-21-5p in metastasis of cervical cancer

Background & objectivesPersistent infection with high-risk human papillomaviruses (HPV) is a major cause of cervical cancer, inducing the hypoxic response by stabilising hypoxia inducing factor-1 alpha (HIF-1α). Under normoxia, HIF-1α is regulated by tumour suppressors genes, LIMD1 and VHL. This study aimed to elucidate the functional roles of two microRNAs, miR-135b-5p and miR-21-5p, in regulating LIMD1/ VHL and their impact on various cellular phenotypes relevant to progression of cervical cancer. MethodsExpressions of miR-135b-5p, miR-21-5p, LIMD1, and VHL was assessed using quantitative real-time polymerase chain reaction (qRT-PCR). Target validation was performed via dual-luciferase assays. Functional assays (proliferation, migration, invasion, apoptosis, and cell cycle analysis) were conducted in SiHa cells following individual and combined miRNA inhibition. ResultsInhibition of miR-135b-5p and miR-21-5p significantly restored LIMD1 (P=0.019) and VHL (P=0.025), respectively, leading to reduced HIF-1α expression (P<0.03). Dual miRNA inhibition had a profound impact on reducing proliferation, migration, invasion and enhancing apoptosis compared to individual knockdowns, whereas G0/G1 arrest was more profound in individual knockdown compared to control cells. Interpretation & conclusionsmiR-135b-5p and miR-21-5p act synergistically as oncomiRs by suppressing LIMD1 and VHL, promoting HIF-1α-mediated cervical cancer progression. This study demonstrated the synergistic oncogenic role of miR-135b-5p and miR-21-5p in cervical cancer via co-regulation of the LIMD1-VHL-HIF-1α axis.