title: STAT3 induces transcription of the DNA methyltransferase 1 gene (DNMT1) in malignant T lymphocytes.
abstract: In this study, we demonstrated that STAT3, a well-characterized transcription factor expressed in continuously activated oncogenic form in the large spectrum of cancer types, induces in malignant T lymphocytes the expression of DNMT1, the key effector of epigenetic gene silencing. STAT3 binds in vitro to 2 STAT3 SIE/GAS-binding sites identified in promoter 1 and enhancer 1 of the DNMT1 gene. STAT3 also binds to the promoter 1 region and induces its activity in vivo. Treatment of the malignant T lymphocytes with STAT3 siRNA abrogates expression of DNMT1, inhibits cell growth, and induces programmed cell death. In turn, inhibition of DNMT1 by a small molecule inhibitor, 5-aza-2-deoxy-cytidine, and 2 DNMT1 antisense DNA oligonucleotides inhibits the phosphorylation of STAT3. These data indicate that STAT3 may in part transform cells by fostering epigenetic silencing of tumor-suppressor genes. They also indicate that by inducing DNMT1, STAT3 facilitates its own persistent activation in malignant T cells. Finally, these data provide further rationale for therapeutically targeting STAT3 in T-cell lymphomas and, possibly, other malignancies.
authors.affiliation: Department of Pathology and Laboratory Medicine, University of Pennsylvania Medical Center, 7.103 Founders, Philadelphia, 19104, USA. qian2@mail.med.upenn.edu
authors.forename: Qian
authors.initials: Q
authors.lastname: Zhang
authors.forename: Hong Y
authors.initials: HY
authors.lastname: Wang
authors.forename: Anders
authors.initials: A
authors.lastname: Woetmann
authors.forename: Puthiyaveettil N
authors.initials: PN
authors.lastname: Raghunath
authors.forename: Niels
authors.initials: N
authors.lastname: Odum
authors.forename: Mariusz A
authors.initials: MA
authors.lastname: Wasik
mesh_terms: D017209:Apoptosis; D045744:Cell Line, Tumor; D049109:Cell Proliferation; D002471:Cell Transformation, Neoplastic; D000076123:DNA (Cytosine-5-)-Methyltransferase 1; D004248:DNA (Cytosine-5-)-Methyltransferases / Q000235:genetics* / Q000502:physiology; D044127:Epigenesis, Genetic; D020868:Gene Silencing; D006801:Humans; D016399:Lymphoma, T-Cell / Q000201:enzymology / Q000378:metabolism* / Q000473:pathology; D010766:Phosphorylation; D050796:STAT3 Transcription Factor / Q000378:metabolism / Q000502:physiology*; D013601:T-Lymphocytes / Q000201:enzymology / Q000378:metabolism / Q000473:pathology; D014158:Transcription, Genetic; D025521:Tumor Suppressor Proteins / Q000235:genetics
chemical_list: D050796:STAT3 Transcription Factor; C494086:STAT3 protein, human; D025521:Tumor Suppressor Proteins; D000076123:DNA (Cytosine-5-)-Methyltransferase 1; D004248:DNA (Cytosine-5-)-Methyltransferases; C000619380:DNMT1 protein, human