Potential markers and epigenetic relatioship in primary and metastatic melanomas

Author(s)

Camilla Borges Ferreira Gomes

• Document type: Doctoral Thesis
• Press: Campinas, SP.
• Institution: Universidade Estadual de Campinas (UNICAMP). Faculdade de Odontologia de Piracicaba
• Defense date: 2016-01-22

Examining board members

Karina Gottardello Zecchin; Andreia Bufalino; Marianne de Vasconcelos Carvalho; Maria Letícia Cintra; Aparecida Machado de Moraes

• Advisor: Karina Gottardello Zecchin

Abstract

Melanoma development has been associated with ultraviolet radiation exposure, but a variety of genetic and epigenetic changes might be also involved in its pathogenesis. Previous studies has shown that fatty acid synthase enzyme (FASN) inhibition reduces melanoma cells proliferation through changes in the proteins involved in the transition cell cycle phases G0 / G1 to S. Recently, it has been verified that the loss of the epigenetic marker 5-hydroxymethylcytosine (5-hmC), regulated by the TET family (ten-eleven translocation), results in a higher expression of nestin, an intermediate filament protein, involved in tumor progression and melanoma virulence. The aims of this work were: (i) evaluate the expression of the proteins FASN, cell cycle proteins, CD34 (a vascular marker), Ki-67 (a proliferation cell marker) in primary cutaneous melanoma (PCM) and metastatic melanoma (MM) and correspond these results with clinicopathological parameters and survival rates of the patients; (ii) access the epigenetic regulation of nestin through TET/5-hmC pathway, correlating it with progression and prognosis of the melanoma patients. PCM and MM were organized in tissue microarrays and submitted to immunohistochemical reactions (IHC) against FASN, Cdk-4, p16Ink4a, p21WAF1/Cip1, p27Kip1, Rb, CD34 and Ki-67. IHC and immunofluorescence (IF) against nestin and 5-hmC were also realized. The impact of 5-hmC in nestin expression by overexpression of TET2 in melanomas in vitro and through genome-wide mapping using Hydroxymethylated DNA Immunoprecipitation Sequencing (hMeDIP-seq) of 5-hmC in nevi and melanomas was also evaluated. For PCM, the overall survivor (OS) was significantly lower in the presence of elevated prognosis factors such as mitotic index, clinical stage and marginally significant to Breslow. It was also found relevancy for higher expression of Cdk-4, FASN and CD34; and a positive correlation was observed between FASN and CD34. The OS for MM was reduced in the presence of high levels of Cdk-4, p21WAF1/Cip1, p27Kip1, Rb and slightly to p16 Ink4a. Expressive increased values of FASN, p21WAF1/Cip1 and Rb were found in MM compared to the reciprocals PCM. A negative correlation of nestin expression and 5hmC was observed. We created a reduction in nestin expression in melanoma by reintroduction of TET2 in vitro restoring 5-hmC. Hence, our results suggest that FASN, p16 Ink4a, Cdk-4 and CD34 are possible critical prognostic factors in melanoma progression. Besides, FASN expression shown a positive correlation with CD34, suggesting that of FASN expression is related with angiogenesis in melanoma. Epigenetic regulation of nestin expression in melanoma tumorigenic growth may relate in part to effects of TET2-mediated 5-hmC. Further studies are indicated to define additional virulence pathways affected by loss of 5-hmC, including those related to melanoma stem cell function (AU)

• FAPESP's process: 12/14008-0 - Correlation between fatty acid synthase, and proteins involved in cell cycle and angiogenesis with human malignant melanoma prognosis
• Grantee: Camilla Borges Ferreira Gomes
• Support Opportunities: Scholarships in Brazil - Doctorate