Synergetic Effects of Intronic Mature miR-944 and ΔNp63 Isoforms on Tumorigenesis in a Cervical Cancer Cell Line

Abstract

miR-944 is located in an intron of the tumor protein p63 gene (TP63). miR-944 expression levels in cervical cancer tissues are significantly higher than in normal tissues and are associated with tumor size, International Federation of Gynecology and Obstetrics (FIGO) stage, lymph node metastasis, and survival. However, associations of miR-944 with its host gene, TP63, which encodes TAp63 and ΔNp63, in cervical cancer have not been fully investigated. A positive correlation between miR-944 and ΔNp63 mRNA expression was identified in cervical cancer tissues. Furthermore, when the expression of miR-944 and ΔNp63 was simultaneously inhibited, cell proliferation-, differentiation- epithelial–mesenchymal transition (EMT)-, transcription-, and virus-associated gene clusters were shown to be significantly more active according to functional annotation analysis. Cell viability and migration were more reduced upon simultaneous inhibition with anti-miR-944 or ΔNp63 siRNA than with inhibition with anti-miR-944 or ΔNp63 siRNA alone, or scramble. In addition, Western blot analysis showed that the simultaneous inhibition of miR-944 and ΔNp63 reduced EMT by increasing the expression of epithelial markers such as claudin and by decreasing mesenchymal markers such as N-cadherin and vimentin. Slug, an EMT transcription factor, was also decreased by the simultaneous inhibition of miR-944 and ΔNp63. Thus, associations between miR-944 and ΔNp63 in cervical cancer could help to elucidate the function of this intronic microRNA and its role in carcinogenesis.

How MicroRNAs Command the Battle against Cancer

“…However, emerging evidence suggests that miRNAs may play an important role in modulating p63 expression and activity in various cellular processes, including development, differentiation, and cancer. Several miRNAs, such as miR-203, miR-130b, miR-205, and miR-944, have been implicated in regulating p63 expression or activity [ 136 , 137 , 138 , 139 , 140 , 141 , 142 ]. These miRNAs can target different isoforms of p63 and modulate its transcriptional activity, protein stability, or subcellular localization.…”

Novel Insights into miR-944 in Cancer

“…N-terminal truncated isoform of p63 (ΔNp63), which is transcribed from an alternative promoter in intron 3 of TP63, can regulate the epithelial properties of cells and play an important role in the terminal differentiation and stemness maintenance of basal epidermal cells [ 18 ]. miR-944 was significantly positively correlated with ΔNp63 expression in cervical cancer (CxCa) and jointly exerted a cancer-promoting effect [ 19 ]. During the differentiation of human epidermal keratinocytes, ΔNp63 can recruit the transcription factor AP-2 to the promoter region of the miR-944 gene, thereby promoting the expression of miR-944 and inducing epidermal differentiation [ 17 ].…”

“…miR-944 is located in the TP63. Previous studies have shown that ΔNp63, but not TAp63, can directly regulate the expression level of miR-944 by recruiting the transcription factor AP-2 [ 19 ]. The high correlation between the expression of TAp63 and miR-944 may be due to the common upstream regulators of TAp63 and ΔNp63, resulting in a significant positive correlation between TAp63 and ΔNp63.…”