DNMT3A and DNMT3B mediate autocrine hGH repression of plakoglobin gene transcription and consequent phenotypic conversion of mammary carcinoma cells.
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'-aza-2'-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 PLAKOGLOBIN gene stimulated by autocrine hGH and subsequent repression of plakoglobin gene transcription and increased cell migration. Thus, the autocrine hGH-stimulated 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.
Shafiei
F
F
National Research Centre for Growth and Development and the Liggins Institute, University of Auckland, Auckland, New Zealand.
Rahnama
F
F
Pawella
L
L
Mitchell
M D
MD
Gluckman
P D
PD
Lobie
P E
PE
D000964:Antimetabolites, Antineoplastic / Q000494:pharmacology; D017209:Apoptosis / Q000187:drug effects / Q000235:genetics; D019898:Autocrine Communication / Q000187:drug effects / Q000235:genetics; D001943:Breast Neoplasms / Q000235:genetics / Q000378:metabolism* / Q000473:pathology; D045744:Cell Line, Tumor; D002465:Cell Movement / Q000187:drug effects / Q000235:genetics; D049109:Cell Proliferation / Q000187:drug effects; D003568:Cytidine Monophosphate / Q000031:analogs & derivatives / Q000494:pharmacology; D000076123:DNA (Cytosine-5-)-Methyltransferase 1; D004248:DNA (Cytosine-5-)-Methyltransferases / Q000096:biosynthesis* / Q000235:genetics; D019175:DNA Methylation / Q000187:drug effects; D000090205:DNA Methyltransferase 3A; D004273:DNA, Neoplasm / Q000235:genetics / Q000378:metabolism; D005260:Female; D015972:Gene Expression Regulation, Neoplastic / Q000187:drug effects / Q000235:genetics; D013006:Growth Hormone / Q000037:antagonists & inhibitors / Q000235:genetics / Q000378:metabolism*; D006801:Humans; D009363:Neoplasm Proteins / Q000096:biosynthesis* / Q000235:genetics; D010641:Phenotype; D011401:Promoter Regions, Genetic / Q000235:genetics; D012333:RNA, Messenger / Q000096:biosynthesis / Q000235:genetics; D012334:RNA, Neoplasm / Q000096:biosynthesis / Q000235:genetics; D034741:RNA, Small Interfering / Q000235:genetics; D051185:gamma Catenin / Q000096:biosynthesis* / Q000235:genetics; D000097584:DNA Methyltransferase 3B
D000964:Antimetabolites, Antineoplastic; D003568:Cytidine Monophosphate; D000076123:DNA (Cytosine-5-)-Methyltransferase 1; D004248:DNA (Cytosine-5-)-Methyltransferases; D000090205:DNA Methyltransferase 3A; D004273:DNA, Neoplasm; D013006:Growth Hormone; D009363:Neoplasm Proteins; D012333:RNA, Messenger; D012334:RNA, Neoplasm; D034741:RNA, Small Interfering; D051185:gamma Catenin; D000097584:DNA Methyltransferase 3B; C000717967:DNMT3A protein, human; C012201:5'-azacytidine 5'-monophosphate; C000619380:DNMT1 protein, human