MicroRNA-34a suppresses invasion through downregulation of Notch1 and Jagged1 in cervical carcinoma and choriocarcinoma cells

Abstract

MicroRNAs (miRNAs) are small non-coding RNAs that regulate the expression of other genes by transcriptional inhibition or translational repression. miR-34a is a known tumor suppressor gene and inhibits abnormal cell growth. However, its role in other tumorigenic processes is not fully known. This study aimed to investigate the action of miR-34a on cell invasion. We found that miR-34a is expressed at various levels in cervical cancer (HeLa, SiHa, C4I, C33a and CaSki) and trophoblast (BeWo and JAR) cell lines. Transient forced expression of miR-34a did not affect the proliferation of these cell lines. Computational miRNA target prediction suggested that Notch1 and Jagged1 were targets of miR-34a. By using functional assays, miR-34a was demonstrated to bind to the 3' untranslated regions of Notch1 and Jagged1. Forced expression of miR-34a altered the expression of Notch1 and Jagged1 protein as well as Notch signaling as shown by the response of Hairy Enhancer of Split-1 protein to these treatments using western blot analysis. Forced expression of miR-34a suppressed the invasiveness of HeLa and JAR cells. By using gamma-secretase inhibitor (N-[N-(3,5-difluorophenacetyl)-l-alanyl]-S-phenylglycine t-butyl ester) that interfered Notch signaling and RNA interference that knockdown Notch1 expression, we confirmed that downregulation of Notch1 reduced the invasiveness of the cells. Transfection of intracellular domain of Notch nullifies the effect of miR-34a on the invasiveness of the cells. Besides, we identified that miR-34a affected cell invasion by regulating expression of urokinase plasminogen activator through Notch. Our results provide evidence that miR-34a inhibits invasiveness through regulation of the Notch pathway and its downstream matrix degrading enzyme.

miR-143 is downregulated in cervical cancer and promotes apoptosis and inhibits tumor formation by targeting Bcl-2

“…In addition, HeLa cells that stably overexpressed miR-214 downregulated the expression of MEK3 and JNK1 at both the mRNA and protein levels by targeting the 3'UTRs of these genes (22). Finally, it has been reported that miR-34a inhibits invasiveness through regulation of the Notch pathway and its downstream matrix degrading enzyme in cervical cancer (23). In our study, we found that miR-143 was underexpressed in 86.7% of the cancerous cervical tissues compared with their non-tumor counterparts.…”

Epigenetic regulation of proMMP-1 expression in the HT1080 human fibrosarcoma cell line

“…Indeed the MMP mRNA transcripts harbor specific sequences in their 5' or 3' untranslated regions (UTRs) which are potential targets of regulatory proteins involved in mRNA stability (39). On the other hand, HDI treatment may activate miRNA expression and modulate tumor cell invasiveness (42)(43)(44)(45). For instance, miR22 was shown to be upregulated by TSA treatment but not by 5-azadC (42).…”

miRNA biogenesis: Biological impact in the development of cancer

“…miR-124 and miR-34, well defined tumor suppressors, are subject to epigenetic silencing by aberrant DNA hypermethylation affecting cell cycle pathways in tumors 54,57,58 ; while down-regulation of miR-34 affects the Notch pathway involved in cell invasion and apoptosis. 59 Furthermore, DNA methylation profiles in miRNA promoter regions can be useful as a diagnostic and prognostic marker. For example, miR-23b, a miRNA with tumor suppressor activity in prostate cancer, is down-regulated through DNA hypermethylation of its promoter region and its expression level is correlated with overall survival and recurrence-free survival.…”