Collagen binding integrins and cancer testis antigens in prostate cancer and melanoma

Camilla Pelo Collagen Binding Integrins and Cancer Testis Antigens in Prostate Cancer and Melanoma Department of Biochemistry, MediCity Research Laboratory, University of Turku, Finland Annales Universitatis Turkuensis, Painosalama Oy, Turku, Finland 2016 ABSTRACT Prostate cancer is the second most common cancer in men worldwide. The incidence of melanoma, in turn, is increasing faster than any other cancer incidences. In Finland, more than 5000 prostate cancer and 1200 new melanoma cases are diagnosed each year. One approach to further understand the cellular processes involved in prostate cancer and melanoma is to gain better knowledge about alterations in gene expression and their potential impact on the progression of the diseases. This thesis is focused on expression studies in two gene families; integrins and cancer testis antigens (CT antigens), in human prostate adenocarcinoma and advanced human melanoma. Integrins are heterodimeric transmembrane receptors which regulate many important cellular processes such as cell proliferation, migration and survival. CT antigens are frequently expressed in different types of cancers, but are only expressed in testis in healthy individuals. CT antigens are also highly immunogenic proteins. Due to the properties mentioned above, integrins and CT antigens can function as target molecules for the development of cancer diagnostics and drugs. One of the main purposes of this thesis was to study the expression of the four collagen binding integrins α1β1, α2β1, α10β1, α11β1 and the cancer testis antigen 16 (CT16) in cancer cell lines and human tissues of prostate cancer and metastatic melanoma. Additional aims included studies on the biological role of CT16 and the abundance of CT16 in sera of advanced melanoma patients. The prognostic and diagnostic significance of CT16 and the collagen binding integrins were also evaluated. Expression studies on collagen binding integrins and the CT antigen CT16 in melanoma and prostate cancer were limited and the biological role of CT16 was unknown. In this thesis, the expression levels of α2β1 and α11β1 were found to be significantly altered in prostate cancer tissues. Integrin α2β1 decreased gradually during disease progression while α11 was elevated in prostate carcinoma compared to healthy tissues. In advanced melanoma, enhanced levels of α2 were associated with a significant shorter overall survival in advanced melanoma. In this thesis, CT16 was identified as a frequently expressed melanoma CT antigen with an anti-apoptotic function. To conclude, this thesis presents α2β1 and CT16, as potential and promising biomarkers for advanced melanoma. This thesis reports also the first functional study of CT16. Keywords: Collagen binding integrins, α1β1, α2β1, α10β1, α11β1, Cancer Testis antigens, CT16, melanoma, prostate cancer, expression