Investigation of survivin gene polymorphisms with breast cancer susceptibility

Breast cancer is the most common malignancy in woman worldwide. It is reported that hormone and environmental factors, chemicals, external estrogen intake, late menopause, late birth of the first birth, family history, increased body-mass index, post-menopausal obesity, ionizing radiation exposure and smoking / alcohol use etc. has increased breast cancer risk. Also, the studies previously performed has shown that the accumulation of genetic damage in onset of cancer causes to activation of proto-oncogenes or inactivation of tumor supressor genes and so, cause to distruption of the balance between cell proliferation and programmed cell death. Gene polymorphism studies, which are one of the parameters that determine cancer risk, are used in many studies related to increased cell proliferation and impaired apoptosis. Pathways leading to apoptotic cell death are highly conserved in the evolution and controlled by apoptotic proteins. Apoptosis inhibitor proteins (IAP) are known to suppress apoptosis more than other apoptotic inhibitor family including Bcl2. It has been asserted that survivin exerts its effect via the inhibition of caspases and is also involved in cell control. Survivin gen has been expressed in many cancer types such as lung, stomach, colon, brain, prostate, non-Hodgkin lymphoma. One of the single nucleotide polymorphisms in the Survivin gene is located within the promoter region of the localized gene at the CDE / CHR repressor binding site. This polymorphism (G / C) has been shown to be associated with overexpression of the gene of survivin. This polymorphism has also been shown to alter cell cycle-dependent transcription by functional degradation of binding in the CDE / CHR repressor motifs in the cancer cell line. Another single nucleotide polymorphism of Survivin gene, the -625G / C has been shown that it might be cause to change in expression level of the survivin gene in many cancer types. In our study, it is aimed to analysis of critical gene polymorphisms which occurs in the genes encoding Survivin protein in breast cancer patients belonging to public of Turkey and to determine the genotype and allele frequencies of these polymorphisms in Turkish population.