CDC42 downregulates ID4 expression trough methylation in the Triple Negative breast cancer cell line MDA-MB231

NASIF DANIELA; LAURITO SERGIO; ROQUÉ MARIA; BRANHAM MARIA T

Nassau

Conferencia; Biological and Clinical Frontiers in Epigenetics; 2018

EpiCypher

Inhibitor of differentiation proteins 1, 2, 3 and 4 (ID1?4), are dominant negative regulators of the basic helix-loop helix (bHLH) family of transcription factors. In human tumors, an increased expression of ID proteins has been associated with reversion to an embryonic-like state, with loss of differentiation, high rates of proliferation, migration and neo-angiogenesis. In breast cancer there are apparently controversial findings regarding the role of ID4 in tumorigenesis. For instance, ID4 silencing by promoter hypermethylation is a frequent event in ER+ (estrogen receptor) breast tumors and is associated with an increased risk of lymph node metastasis. However, in ER- breast tumors ID4 increased expression has been associated with an aggressive phenotype such as the ability of breast cancer cells to exhibit anchorage-independent growth. Our group has previously shown that ID4 promoter hypomethylation is associated with the aggressive Triple Negative Breast cancer (TNBC) subtype. We also demonstrated that ID4 hypomethylation is associated with BRCAness phenotype and downregulation of BRCA1 gene. Here we show that the overexpression of CDC42, a plasma membrane-associated small GTPase, induced ID4 promoter methylation in the TNBC cell line MDA-MDA231. Briefly, MDA-MB321 cell lines were transfected with a CDC42-GFP or control-GFP vector. After 72hs of transfection ID4 methylation was measured by droplet digital and conventional Methyl Specific PCR and MS-MLPA assay. Our results show that ID4 methylation increased significantly after CDC42 transfection (p