72P - Survivin gene expression in the primary tumor and circulating tumor cells – a new biomarker of tumor progression of breast cancer

Abstract

Breast cancer is a leading cause of morbidity and mortality of the female population from malignant tumors. Distant metastases are the main cause of death of patients, a substrate for the development of which are circulating tumor cells (CTCs). However, the search for these cells alone is not sufficient to provide full information about the nature and course of tumor in a single patient. Determination of the expression of tumor-genes responsible for the different processes of tumor progression allows a more complete picture. Such genes include the gene survivin (BIRC5) family of inhibitors of apoptosis (IAP). Using real-time PCR we investigated the expression of the survivin gene in 36 samples of primary invasive ductal carcinoma of the breast, 10 samples of benign tumors - fibroadenoma of the breast, as well as 36 samples of peripheral blood of patients with breast cancer at various stages of tumor and stage specific treatment, and 10 healthy people as controls. In primary breast carcinoma we determined a high expression of survivin gene in all 36 samples with the average value (M ± m) 1.58 ± 0.31 (min – 1.19; max – 4.41). The highest figures were found in tumors of medium and high grade (G II-III) with lymphovenous invasion (LVSI +). In 2 of 3 samples of benign tumor expression of survivin was not found, and one was 0.015. In CTCs, isolated from peripheral blood of breast cancer patients, all 36 samples as determined by the gene expression of survivin with an average value (M ± m) 1.10 ± 0.19 (min – 0.36; max – 3.79). The level of expression of the control samples did not exceed 0.003. It should be noted that the maximum volume of expression was obtained in samples of tumor patients with stage N +, and especially M1, on TNM classification. Any legitimate expression of survivin, depending on the size of the tumor had been received. In patients, receiving chemotherapy average expression of survivin gene was obswerved, but it never approached the indicators of control. Determination of expression of the survivin gene in primary tumor and in CTCs may be one of the most promising markers of tumor progression and for monitoring of breast cancer therapy.