title: CD82 suppresses CD44 alternative splicing-dependent melanoma metastasis by mediating U2AF2 ubiquitination and degradation.
abstract: Melanoma is one of the most lethal forms of skin cancer because of its early metastatic spread. The variant form of CD44 (CD44v), a cell surface glycoprotein, is highly expressed on metastatic melanoma. The mechanisms of regulation of CD44 alternative splicing in melanoma and its pathogenic contributions are so far poorly understood. Here, we investigated the expression level of CD44 in a large set of melanocytic lesions at different stages. We found that the expression of CD44v8-10 and a splicing factor, U2AF2, is significantly increased during melanoma progression, whereas CD82/KAI1, a tetraspanin family of tumor suppressor, is reduced in metastatic melanoma. CD44v8-10 and U2AF2 expression levels, which are negatively correlated with CD82 levels, are markedly elevated in primary melanoma compared with dysplastic nevi and further increased in metastatic melanoma. We also showed that patients with higher CD44v8-10 and U2AF2 expression levels tended to have shorter survival. By using both in vivo and in vitro assays, we demonstrated that CD82 inhibits the production of CD44v8-10 on melanoma. Mechanistically, U2AF2 is a downstream target of CD82 and in malignant melanoma facilitates CD44v8-10 alternative splicing. U2AF2-mediated CD44 isoform switch is required for melanoma migration in vitro and lung and liver metastasis in vivo. Notably, overexpression of CD82 suppresses U2AF2 activity by inducing U2AF2 ubiquitination. In addition, our data suggested that enhancement of melanoma migration by U2AF2-dependent CD44v8-10 splicing is mediated by Src/focal adhesion kinase/RhoA activation and formation of stress fibers, as well as CD44-E-selectin binding reinforcement. These findings uncovered a hitherto unappreciated function of CD82 in severing the linkage between U2AF2-mediated CD44 alternative splicing and cancer aggressiveness, with potential prognostic and therapeutic implications in melanoma.
authors.affiliation: Key Laboratory of Luminescence and Real-Time Analytical Chemistry (Southwest University),Ministry of Education, College of Pharmaceutical Sciences, Southwest University, Chongqing, China, 400715.|Department of Physiology, University of Alberta, Edmonton, Alberta, Canada, AB T6G 2S2.
authors.forename: Pu
authors.initials: P
authors.lastname: Zhang
authors.affiliation: Key Laboratory of Luminescence and Real-Time Analytical Chemistry (Southwest University),Ministry of Education, College of Pharmaceutical Sciences, Southwest University, Chongqing, China, 400715.
authors.forename: Shan
authors.initials: S
authors.lastname: Feng
authors.affiliation: Shanghai Pulmonary Hospital, Tongji University School of Medicine, 507 Zhengmin Rd, Shanghai 200433, People's Republic of China.
authors.forename: Gentao
authors.initials: G
authors.lastname: Liu
authors.affiliation: Shanghai Pulmonary Hospital, Tongji University School of Medicine, 507 Zhengmin Rd, Shanghai 200433, People's Republic of China.
authors.forename: Heyong
authors.initials: H
authors.lastname: Wang
authors.affiliation: Key Laboratory of Luminescence and Real-Time Analytical Chemistry (Southwest University),Ministry of Education, College of Pharmaceutical Sciences, Southwest University, Chongqing, China, 400715.
authors.forename: Ailing
authors.initials: A
authors.lastname: Fu
authors.affiliation: Key Laboratory of Luminescence and Real-Time Analytical Chemistry (Southwest University),Ministry of Education, College of Pharmaceutical Sciences, Southwest University, Chongqing, China, 400715.
authors.forename: Huifeng
authors.initials: H
authors.lastname: Zhu
authors.affiliation: Key Laboratory of Luminescence and Real-Time Analytical Chemistry (Southwest University),Ministry of Education, College of Pharmaceutical Sciences, Southwest University, Chongqing, China, 400715.
authors.forename: Qiao
authors.initials: Q
authors.lastname: Ren
authors.affiliation: College of Bioengineering, Chongqing University, Chongqing, China, 400030.
authors.forename: Bochu
authors.initials: B
authors.lastname: Wang
authors.affiliation: Key Laboratory of Luminescence and Real-Time Analytical Chemistry (Southwest University),Ministry of Education, College of Pharmaceutical Sciences, Southwest University, Chongqing, China, 400715.
authors.forename: Xingran
authors.initials: X
authors.lastname: Xu
authors.affiliation: Key Laboratory of Luminescence and Real-Time Analytical Chemistry (Southwest University),Ministry of Education, College of Pharmaceutical Sciences, Southwest University, Chongqing, China, 400715.
authors.forename: Huiyuan
authors.initials: H
authors.lastname: Bai
authors.affiliation: Department of Biomedical Engineering, Pennsylvania State University, University Park, PA, US 16802.
authors.forename: Cheng
authors.initials: C
authors.lastname: Dong
mesh_terms: D017398:Alternative Splicing / Q000235:genetics; D000818:Animals; D045744:Cell Line, Tumor; D015972:Gene Expression Regulation, Neoplastic; D006801:Humans; D018960:Hyaluronan Receptors / Q000235:genetics*; D051861:Kangai-1 Protein / Q000235:genetics*; D008544:Melanocytes / Q000473:pathology; D008545:Melanoma / Q000235:genetics* / Q000473:pathology; D051379:Mice; D009362:Neoplasm Metastasis; D010766:Phosphorylation; D011379:Prognosis; D020033:Protein Isoforms / Q000235:genetics; D059748:Proteolysis; D000072668:Splicing Factor U2AF / Q000235:genetics*; D054875:Ubiquitination / Q000235:genetics; D023041:Xenograft Model Antitumor Assays
chemical_list: C497688:CD82 protein, human; D018960:Hyaluronan Receptors; D051861:Kangai-1 Protein; D020033:Protein Isoforms; D000072668:Splicing Factor U2AF; C000607494:U2AF2 protein, human