Cervical cancer (CC) is the second most common cancer in females in developing countries. The two viral oncoproteins E6 and E7 mediate the oncogenic activities of high-risk human papillomavirus (HR-HPV), and HR-HPV, especially HPV16 or/and HPV18 (HPV16/18) play critical roles in CC through different pathways. microRNAs (miRNAs) may be associated with CC pathogenesis. Researches have indicated that human papillomavirus (HPV) may regulate cellular miRNA expression through viral E6 and E7. The purpose of a recent study by researchers from Qingdao University sought to identify the relationship between HPV infection and aberrantly expressed miRNAs and to investigate their pathogenic roles in CC.

In their study, miRNA expression was assessed using microRNA microarray service in HPV16 E6- and E7-integrated HPV-negative HT-3 cell lines and mock vector-transfected HT-3 cells. The microarray results were validated, and the expression of miR-3156-3p was identified in HPV-positive and -negative CC cell lines as well as primary CC and normal cervical epithelium tissues using quantitative reverse-transcription polymerase chain reaction (qRT-PCR). Cell Counting Kit-8 (CCK8), flow cytometry, transwell analysis, tube formation, and Western blotting were used to identify the functional role of miR-3156-3p in CaSki, SiHa, and HeLa cell lines.

Researchers consistently identified six underexpressed microRNAs (miR-3156-3p, 6779-3p, 4779-3p, 6841-3p, 454-5p and 656-5p) in HPV16 E6- and E7-integrated HT-3 cells. Further investigation confirmed a significant decrease of miR-3156-3p in HPV16/18 positive CC lesions. CCK8, flow cytometry, transwell analysis, tube formation assays, and Western blotting of the CC cell lines with miR-3156-3p over/under-expression in vitro showed that miR-3156-3p was involved in cell proliferation, apoptosis, migration, neovascularization, and SLC6A6 regulation.

These findings indicate that miR-3156-3p plays a suppressor-miRNA role in CC and that its expression is associated with HR-HPV infection.

 

SLC6A6 expression in cervical cancer tissues. a SLC6A6 mRNA level was examined by qRT-PCR in cervical cancer and normal cervical tissue. b Immunohistochemical staining of the anti-SLC6A6 antibody in cervical cancer and normal cervical tissues. Strong SLC6A6 immunoreactivity was found in both the cytomembrane and cytoplasm in tumor tissues but not in the normal cervix tissues (scale bar, 100 μm). (**p < 0.01, *p < 0.05)

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Reference
Wang YK et al. (2017) miR-3156-3p is downregulated in HPV-positive cervical cancer and performs as a tumor-suppressive miRNA Virol. J. 14: 20. doi: 10.1186/s12985-017-0695-7 [article]

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