Abstract 5442: Down-regulation of miRNA-214 expression by bioactive molecules mitigates invasive potential of melanoma cells through ALCAM/TFAP2 signaling

Melanoma is responsible for 80% of skin cancer related deaths in the United States and represents fifth most common neoplasia in humans. Over the past decades, the incidence of melanoma has increased by 3% to 8% per year in western countries. Therefore, it is essential to understand the molecular regulatory pathways that contribute to melanoma aggressiveness and metastatic dissemination. MicroRNAs (miRNAs) are small noncoding regulatory RNAs that contribute to tumor formation and progression, for their ability to regulate gene expression post-transcriptionally by either inhibiting protein translation or degrading target mRNAs. miR-214 is overexpressed in various types of cancers and is associated with the regulation of numerous carcinogenic processes including cell differentiation, senescence, angiogenesis and cell migration/invasion, etc. In the present study, we demonstrated that miR-214 shows distinct over expression in melanoma cell lines (A375, Hs294t, SK-Mel119, and SK-Mel28) as compared to its expression in normal human epidermal melanocytes (NHEM), and this overexpression of miR-214 in melanoma cells was associated with the invasive potential than NHEM. Treatment of melanoma cells with an inhibitor of miR-214 (50 nM) resulted in inhibition of cell invasion ability. We also determined the effects of bioactive phytochemical grape seed proanthocyanidins (GSPs) on the expression levels of miRNA-214 in melanoma cell lines (A375 and Hs294t) and its underlying molecular targets. Treatment of A375 and Hs294t cells with GSPs resulted in suppression of the levels of miRNA-214, which leads to decrease in migration potential of melanoma cell lines. By using 3D melanoma progression model, we also verified this suppressive effect of GPSs on melanoma invasion. The transition from the non-invasive to the invasive and metastatic stage is accompanied by the loss of AP-2 transcription factors (TFAP-2) and expression of activated leukocyte cell adhesion molecule (ALCAM) and those are associated with miRNA-214 overexpression. Here, we observed that the treatment of GSPs decreases ALCAM expression and restore TFAP-2 levels in melanoma cell lines. Further, dietary administration of GSPs significantly reduce the metastasis potential of A375 cells in different vital organs such as lung, liver, kidney, and spleen, and this suppressive effect of GSPs on invasive potential of A375 cells was associated with the reduction in the levels of miRNA-214 and ALCAM. Our results indicate that modulation of miR-214 influences in vitro cell movement and extravasation from blood vessels in vivo. Together, these studies suggest that an identification of metastasis related miRNAs may provide potential diagnostic biomarkers and better understanding of the complex functions of miRNAs, as well as therapeutic targets for clinical application. Note: This abstract was not presented at the meeting. Citation Format: Ram Prasad, Santosh K. Katiyar. Down-regulation of miRNA-214 expression by bioactive molecules mitigates invasive potential of melanoma cells through ALCAM/TFAP2 signaling [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2017; 2017 Apr 1-5; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2017;77(13 Suppl):Abstract nr 5442. doi:10.1158/1538-7445.AM2017-5442