DNMT3A and DNMT3B mediate autocrine hGH repression of plakoglobin gene transcription and consequent phenotypic conversion of mammary carcinoma cells

Abstract

Directed by microarray analyses, we report that autocrine human growth hormone (hGH) increased the mRNA and protein expression of DNA methyltransferase 1 (DNMT1), DNMT3A and DNMT3B in mammary carcinoma cells. Autocrine hGH stimulation of DNMT3A and DNMT3B expression was mediated by JAK2 and Src kinases, and treatment of mammary carcinoma cells with the DNMT inhibitor, 5 0 -aza-2 0 -deoxycytidine (AZA), abrogated autocrine hGH-stimulated cellular proliferation, apoptosis and anchorage-independent growth. AZA reversed the epitheliomesenchymal transition of mammary carcinoma cells induced by autocrine hGH, to an epithelioid morphology and abrogated cell migration stimulated by autocrine hGH. Autocrine hGH-stimulated hypermethylation of the first exon of the PLAKOGLOBIN gene and AZA abrogated the ability of autocrine hGH to repress plakoglobin gene transcription. Small interfering RNA (siRNA)-mediated depletion of the individual DNMT molecules did not release autocrine hGH repression of PLAKOGLOBIN promoter activity nor did individual DNMT depletion affect autocrine hGH-stimulated migration. However, concomitant siRNA-mediated depletion of both DNMT3A and DNMT3B abrogated hypermethylation of the PLAKO-GLOBIN gene stimulated by autocrine hGH and subsequent repression of plakoglobin gene transcription and increased cell migration. Thus, the autocrine hGHstimulated increases in DNMT3A and DNMT3B expression mediate repression of plakoglobin gene transcription by direct hypermethylation of its promoter and consequent phenotypic conversion of mammary carcinoma cells. Autocrine hGH, therefore, utilizes DNA methylation as a mechanism to exert its oncogenic effects in mammary carcinoma cells.

Autocrine/Paracrine Human Growth Hormone-stimulated MicroRNA 96-182-183 Cluster Promotes Epithelial-Mesenchymal Transition and Invasion in Breast Cancer

“…Determination of the precise role of STAT5 in human breast cancer progression requires significant further study. We had previously reported that autocrine hGH stimulated epithelial to mesenchymal transition and invasion of mammary carcinoma cells through repression of plakoglobin and relocalization of E-cadherin without alteration in E-cadherin expression (6,40). However, in the present study, we now observe autocrine hGH repression of E-cadherin, albeit slight.…”

High Motility of Triple-negative Breast Cancer Cells Is Due to Repression of Plakoglobin Gene by Metastasis Modulator Protein SLUG

“…Motility of the transformed epithelial cancer cells is increased through the trigger of formation of membrane ruffles known as invadopodia (25)(26)(27). Among the proteins that are attributed to control the motility of epithelial cells, the catenin protein plakoglobin is implicated as having the central role (17)(18)(19)(20)(21)(22)(23). A high plakoglobin level in the cells is translated to lower motility and vice versa (17)(18)(19)(20)(21)(22)(23).…”

“…Tissues-As mentioned above, the armadillo motif-containing protein plakoglobin is known to negatively regulate the motility of epithelial cells (17)(18)(19)(20)(21)(22)(23). Because SLUG in the breast cancer cells regulates the motility of these cells, we hypothesized that SLUG represses plakoglobin gene in these cells to increase their motility.…”

“…Out of several epithelial cell molecules implicated in the direct or indirect regulation of cellular motility, the catenin molecule plakoglobin stands out as a major player in negatively regulating the motility of these cells (17)(18)(19)(20)(21)(22)(23). Plakoglobin (also known as junction plakoglobin (JUP)) is a member of the armadillo family of proteins and a close relative of ␤-catenin (24).…”

MTSS1, a novel target of DNA methyltransferase 3B, functions as a tumor suppressor in hepatocellular carcinoma

“…Mouse studies have shown that both Dnmt3a and Dnmt3b are required for the establishment and maintenance of genomic methylation patterns and proper murine development (Bachman et al, 2001;Gowher and Jeltsch, 2002;Kaneda et al, 2004). DNMT3A and DNMT3B are upregulated in certain types of hematological malignancies and solid tumors, including leukocythemia (Mizuno et al, 2001;Claus and Lubbert, 2003), colorectal cancer Takeshima et al, 2006), lung cancer, breast cancer (Girault et al, 2003;Shafiei et al, 2008) and HCC (Saito et al, 2002;Choi et al, 2003). Specifically, DNMT3B contributes to oncogenic phenotypes (Linhart et al, 2007) and tumorigenesis in vivo by gene-specific de novo methylation and transcriptional silencing (Wang et al, 2007).…”