Human Melanoma Cells Differentially Express RNASEL/RNase-L and miR-146a-5p under Sex Hormonal Stimulation

• Published in: Current Issues in Molecular Biology Vol. 44; no. 10; pp. 4790 - 4802
• Main Authors: Orlandi, Elisa, De Tomi, Elisa, Campagnari, Rachele, Belpinati, Francesca, Rodolfo, Monica, Vergani, Elisabetta, Malerba, Giovanni, Gomez-Lira, Macarena, Menegazzi, Marta, Romanelli, Maria Grazia
• Format: Journal Article
• Language: English
• Published: MDPI AG 01.10.2022; MDPI
• Subjects: 17β-estradiol; Analysis; Estrogen; gene regulation; Genetic aspects; Genetic polymorphisms; Genetic transcription; Melanoma; melanoma cells; mRNA/miR-146a interaction; Ribonuclease; RNA; Scientific equipment and supplies industry; Testosterone; United States
• ISSN: 1467-3045; 1467-3037; 1467-3045
• DOI: 10.3390/cimb44100326

Polymorphisms in the ribonuclease L (RNASEL) coding gene and hsa-miR-146a-5p (miR-146a) have been associated with melanoma in a sex-specific manner. We hypothesized that RNASEL and miR-146a expression could be influenced by sex hormones playing a role in the female advantages observed in melanoma incidence and survival. Thus, we explored the effects of testosterone and 17β-estradiol on RNASEL and miR-146a expression in LM-20 and A375 melanoma cell lines. Direct targeting of miR-146a to the 3′ untranslated region (3′UTR) of RNASEL was examined using a luciferase reporter system. Our results indicate that RNASEL is a direct target of miR-146a in both melanoma cell lines. Trough qPCR and western blot analyses, we explored the effect of miR-146a mimic transfection in the presence of each hormone either on RNASEL mRNA level or on protein expression of RNase-L, the enzyme codified by RNASEL gene. In the presence of testosterone or 17β-estradiol, miR-146a overexpression did not influence RNASEL transcript level in LM-20 cell line, but it slightly induced RNASEL mRNA level in A375 cells. Remarkably, miR-146a overexpression was able to repress the protein level of RNase-L in both LM-20 and A375 cells in the presence of each hormone, as well as to elicit high expression levels of the activated form of the extracellular signal-regulated kinases (ERK)1/2, hence confirming the pro-tumorigenic role of miR-146a overexpression in melanoma. Thereafter, we assessed if the administration of each hormone could affect the endogenous expression of RNASEL and miR-146a genes in LM-20 and A375 cell lines. Testosterone exerted no significant effect on RNASEL gene expression in both cell lines, while 17β-estradiol enhanced RNASEL transcript level at least in LM-20 melanoma cells. Conversely, miR-146a transcript augmented only in the presence of testosterone in either melanoma cell line. Importantly, each hormone acted quite the opposite regarding the RNase-L protein expression, i.e., testosterone significantly decreased RNase-L expression, whereas 17β-estradiol increased it. Overall, the data show that, in melanoma cells treated with 17β-estradiol, RNase-L expression increased likely by transcriptional induction of its gene. Testosterone, instead, decreased RNase-L expression in melanoma cell lines with a post-transcriptional mechanism in which miR-146a could play a role. In conclusion, the pro-tumor activity of androgen hormone in melanoma cells could be exacerbated by both miR-146a increase and RNase-L downregulation. These events may contribute to the worse outcome in male melanoma patients.