title: All Trans-Retinoic Acid Mediates MED28/HMG Box-Containing Protein 1 (HBP1)/β-Catenin Signaling in Human Colorectal Cancer Cells.
abstract: Vitamin A is required for normal body function, including vision, epithelial integrity, growth, and differentiation. All trans-retinoic acid (ATRA), a family member of vitamin A, has been explored in treating acute promyelocytic leukemia and other types of cancer. Dysregulated Wnt/β-catenin signaling and disrupted cadherin-catenin complex often contribute to colorectal malignancy. MED28, a mammalian Mediator subunit, is found highly expressed in breast and colorectal cancers. Our laboratory has also reported that MED28 regulates cell growth, migration, and invasion in human breast cancer cells. In the current study we investigated the effect of ATRA on MED28 and Wnt/β-catenin signaling in colorectal cancer. HCT116, HT29, SW480, and SW620, four human colorectal cancer cell lines representing different stages of carcinogenesis and harboring critical genetic changes, were employed. Our data indicated that regardless of genetic variations among these cells, suppression of MED28 reduced the expression of cyclin D1, c-Myc, and nuclear β-catenin, but increased the expression of E-cadherin and HMG box-containing protein 1 (HBP1) where HBP1 has been described as a negative regulator of the Wnt/β-catenin signaling. The reporter activity of an HBP1 promoter increased upon MED28 knockdown, but decreased upon MED28 overexpression. ATRA reduced the expression of MED28 and mimicked the effect of MED28 suppression in down-regulating Wnt/β-catenin signaling. Taken together, ATRA can reverse the suppressive effect of MED28 on HBP1 and E-cadherin and inactivate the Wnt/β-catenin pathway in colorectal cancer, suggesting a protective effect of ATRA against colorectal cancer. J. Cell. Physiol. 231: 1796-1803, 2016. © 2015 Wiley Periodicals, Inc.
authors.affiliation: Department of Nutrition and Health Sciences, Chang Jung Christian University, Tainan, Taiwan, R.O.C.
authors.forename: Ming-Fen
authors.initials: MF
authors.lastname: Lee
authors.affiliation: Department of Nutrition, China Medical University, Taichung, Taiwan, R.O.C.
authors.forename: Nien-Tsu
authors.initials: NT
authors.lastname: Hsieh
authors.affiliation: Department of Nutrition, China Medical University, Taichung, Taiwan, R.O.C.
authors.forename: Chun-Yin
authors.initials: CY
authors.lastname: Huang
authors.affiliation: Department of Nutrition and Health Sciences, Chang Jung Christian University, Tainan, Taiwan, R.O.C.
authors.forename: Chun-I
authors.initials: CI
authors.lastname: Li
mesh_terms: D015703:Antigens, CD; D000970:Antineoplastic Agents / Q000494:pharmacology*; D015820:Cadherins / Q000235:genetics / Q000378:metabolism; D002470:Cell Survival / Q000187:drug effects; D015179:Colorectal Neoplasms / Q000188:drug therapy* / Q000235:genetics / Q000378:metabolism / Q000473:pathology; D019938:Cyclin D1 / Q000235:genetics / Q000378:metabolism; D004305:Dose-Response Relationship, Drug; D015972:Gene Expression Regulation, Neoplastic; D045325:HCT116 Cells; D019073:HT29 Cells; D006609:High Mobility Group Proteins / Q000235:genetics / Q000378:metabolism*; D006801:Humans; D056892:Mediator Complex / Q000235:genetics / Q000378:metabolism*; D011401:Promoter Regions, Genetic; D016271:Proto-Oncogene Proteins c-myc / Q000235:genetics / Q000378:metabolism; D034622:RNA Interference; D012097:Repressor Proteins / Q000235:genetics / Q000378:metabolism*; D015398:Signal Transduction / Q000187:drug effects*; D014162:Transfection; D014212:Tretinoin / Q000494:pharmacology*; D051176:beta Catenin / Q000235:genetics / Q000378:metabolism*
chemical_list: D015703:Antigens, CD; D000970:Antineoplastic Agents; C530104:CCND1 protein, human; C513384:CDH1 protein, human; C495270:CTNNB1 protein, human; D015820:Cadherins; C486328:HBP1 protein, human; D006609:High Mobility Group Proteins; C496877:MED28 protein, human; C489427:MYC protein, human; D056892:Mediator Complex; D016271:Proto-Oncogene Proteins c-myc; D012097:Repressor Proteins; D051176:beta Catenin; D019938:Cyclin D1; D014212:Tretinoin