Role of miRNAs, miR-135b-5p & miR-21-5p in metastasis of cervical cancer
Background & objectives
Persistent 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.
Methods
Expressions 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.
Results
Inhibition 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 & conclusions
miR-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.