Association of CTLA4 and CD28 Gene Variants and Circulating Levels of Their Proteins in Patients with Breast Cancer

Background/Aim: Breast cancer is one of the most common and lethal types of cancer among women. We focused on the importance of the immune system in the etiology of breast cancer by investigating critical polymorphisms of cytotoxic T-lymphocyte-associated protein 4 (CTLA4) and cluster of differentiation 28 (CD28) gene, and circulating levels of these proteins. Materials and Methods: A total of 79 patients with breast cancer and 76 healthy controls were enrolled. Molecular assessment of CTLA4 (rs231775& rs5742909) and CD28 (rs3116496) variants were determined with polymerase chain reaction restriction fragment length polymorphism techniques. Circulating levels of soluble forms of CTLA4 and CD28 were analyzed by ELISA. Results: Although no significant association was found between study groups, CTLA4 +49AA genotypic frequency, and sCTLA4 and sCD28 levels were higher in patients. Some clinicopathological features were also related with CTLA4 and CD28 variants and blood levels. Conclusion: While CTLA4 +49AA genotype is increased in patients with breast cancer, the CTLA4 -318T allele may have a prognostic value. In addition, sCTLA4 and sCD28 can be used for diagnostic purposes in patients with breast cancer.