Year: 2017
Type: dissertation
Abstract: Melanoma is the deadliest form of skin cancer when discovered in advanced stages. Early detection with surgical tumor removal is still the most effective treatment option. Novel treatment options such as small molecular inhibitors (e.g. Vemurafenib) and immunotherapy (CTLA-4 and PD-1 inhibitors) have prolonged patient survival of individuals with metastatic disease. However, drug resistance and subsequent relapse, together with non-responders are still barriers that need to be overcome. Understanding the signaling pathways leading to melanoma development and progression is important to improve therapeutic options. Tumor suppressors are a group of genes whose function when absent may lead to tumor formation. The CDKN2A gene encodes two distinct tumor suppressors (p16INK4A and p14ARF) that regulates the cell cycle and is involved in vital processes such as aging, cellular senescence, and apoptosis. The CDKN2A gene is frequently lost or deregulated in human cancers, especially in melanoma, emphasizing the importance of CDKN2A within melanoma development. Another high susceptibility gene within melanoma is MITF-M (microphthalmia-associated transcription factor). MITF-M is the master regulator of melanocyte development, function and survival. Interestingly, MITF-M has been reported to regulate cell-cycle progression through the up-regulation of genes such as p16INK4A and p21Cip1. In this study, we aimed to investigate the role of MITF-M in the regulation of the CDKN2A transcripts p16INK4A/p14ARF in immortalized melanocytes and melanoma cell lines spanning different disease stages and genetic backgrounds. Further, we investigated the implications of modulating p16INK4A expression in different melanoma backgrounds. Our data suggest that depletion of MITF-M results in a minor up-regulation of both p16INK4A and p14ARF expression in the majority of the cell lines tested. However, one exception was found showing a decrease in p16INK4A and p14ARF expression after MITF-M depletion. When modulating p16INK4A in various melanoma cell lines by using p16 mRNA or p16 siRNA molecules we observed no significant change in cell viability or cell growth rates compared to negative controls. Together, our results suggest that the regulation of p16INK4A and p14ARF expression by MITF-M is cell line specific, and that further studies are required to fully elucidate the role of MITF-M upon the regulation of CDKN2A in melanocytes and melanoma.
Author: Randi Christel Andreassen
Language: English
Topic: Melanoma and MAPK Pathways
Subfield: Molecular Biology
Domain: Life Sciences
Open Access status: green
OpenAlex ID: W2752874076