title: Epigenetically upregulated WIPF1 plays a major role in BRAF V600E-promoted papillary thyroid cancer aggressiveness.
abstract: How the BRAF V600E mutation promotes the pathogenesis and aggressiveness of papillary thyroid cancer (PTC) is not completely understood. Here we explored a novel mechanism involving WASP interacting protein family member 1 (WIPF1). In PTC tumors, compared with the wild-type BRAF, BRAF V600E was associated with over-expression and hypomethylation of the WIPF1 gene. In thyroid cancer cell lines with wild-type BRAF, WIPF1 expression was robustly upregulated upon introduced expression of BRAF V600E (P=0.03) whereas the opposite was seen upon BRAF knockdown or treatment with BRAF V600E or MEK inhibitors in cells harboring BRAF V600E. Methylation of a functionally critical region of the WIPF1 promoter was decreased by expressing BRAF V600E in cells harboring the wild-type BRAF and increased by BRAF knockdown or treatment with BRAF V600E or MEK inhibitors in cells harboring BRAF V600E mutation. Under-expression and hypermethylation of WIPF1 induced by stable BRAF knockdown was reversed by DNA demethylating agent 5'-azadeoxycytidine. Knockdown of WIPF1 robustly inhibited anchorage-independent colony formation, migration, and invasion of thyroid cancer cells and suppressed xenograft thyroid cancer tumor growth and vascular invasion, mimicking the effects of BRAF knockdown. In human PTC tumors, WIPF1 expression was associated with extrathyroidal invasion (P=0.01) and lymph node metastasis (P=2.64E-05). In summary, BRAF V600E-activated MAP kinase pathway causes hypomethylation and overexpression of WIPF1; WIPF1 then functions like an oncoprotein to robustly promote aggressive cellular and tumor behaviors of PTC. This represents a novel mechanism in BRAF V600E-promoted PTC aggressiveness and identifies WIPF1 as a novel therapeutic target for thyroid cancer.
authors.affiliation: Laboratory for Cellular and Molecular Thyroid Research, Division of Endocrinology, Diabetes & Metabolism, Department of Medicine, Johns Hopkins University School of Medicine, Baltimore, MD 21287, USA.
authors.forename: Tao
authors.initials: T
authors.lastname: Zhang
authors.affiliation: Laboratory for Cellular and Molecular Thyroid Research, Division of Endocrinology, Diabetes & Metabolism, Department of Medicine, Johns Hopkins University School of Medicine, Baltimore, MD 21287, USA.
authors.forename: Xiaopei
authors.initials: X
authors.lastname: Shen
authors.affiliation: Laboratory for Cellular and Molecular Thyroid Research, Division of Endocrinology, Diabetes & Metabolism, Department of Medicine, Johns Hopkins University School of Medicine, Baltimore, MD 21287, USA.
authors.forename: Rengyun
authors.initials: R
authors.lastname: Liu
authors.affiliation: Laboratory for Cellular and Molecular Thyroid Research, Division of Endocrinology, Diabetes & Metabolism, Department of Medicine, Johns Hopkins University School of Medicine, Baltimore, MD 21287, USA.
authors.forename: Guangwu
authors.initials: G
authors.lastname: Zhu
authors.affiliation: Department of Pathology, Johns Hopkins University School of Medicine, Baltimore, MD 21287, USA.
authors.forename: Justin
authors.initials: J
authors.lastname: Bishop
authors.affiliation: Laboratory for Cellular and Molecular Thyroid Research, Division of Endocrinology, Diabetes & Metabolism, Department of Medicine, Johns Hopkins University School of Medicine, Baltimore, MD 21287, USA.
authors.forename: Mingzhao
authors.initials: M
authors.lastname: Xing
mesh_terms: D000818:Animals; D002291:Carcinoma, Papillary / Q000235:genetics* / Q000473:pathology*; D045744:Cell Line, Tumor; D002465:Cell Movement / Q000235:genetics; D049109:Cell Proliferation; D003598:Cytoskeletal Proteins / Q000235:genetics*; D019175:DNA Methylation; D004195:Disease Models, Animal; D018450:Disease Progression; D044127:Epigenesis, Genetic; D005260:Female; D015870:Gene Expression; D015972:Gene Expression Regulation, Neoplastic; D055785:Gene Knockdown Techniques; D017930:Genes, Reporter; D064593:Heterografts; D006801:Humans; D047908:Intracellular Signaling Peptides and Proteins / Q000235:genetics*; D051379:Mice; D008954:Models, Biological; D009154:Mutation; D011401:Promoter Regions, Genetic; D048493:Proto-Oncogene Proteins B-raf / Q000235:genetics* / Q000378:metabolism; D000077273:Thyroid Cancer, Papillary; D013964:Thyroid Neoplasms / Q000235:genetics* / Q000473:pathology*; D047368:Tumor Burden
chemical_list: D003598:Cytoskeletal Proteins; D047908:Intracellular Signaling Peptides and Proteins; C109903:WIPF1 protein, human; D048493:Proto-Oncogene Proteins B-raf
keywords: BRAF V600E; WIPF1; oncogenesis; thyroid cancer; tumor aggressiveness