A51: Immunologic microenvironment and some molecular biological characteristics of breast cancer

The purpose of the study was to assess parameters of local cellular immunity, expression of apoptosis-controlling proteins and some other receptors in various molecular subtypes of breast cancer (BC) with different clinical course and prognosis. Materials and methods 100 BC patients aged 30–76 years (59 ± 3.4) were recruited. Tissues of tumor and peritumoral area were homogenized by MediMachine, subset contents of T, B, NK-lymphocytes were estimated by flow cytometer FACS CantoII. Percentage of lymphocytes expressing CD3, CD4, CD8, CD19, CD16/56, were counted from total amount of CD45+ lymphocytes. Sections of paraffin-embedded blocks were studied by immunohistochemical method with polyvalent HRP-DAB detection system. Staining was performed using Thermo Scientific autostainer. Tumor was considered p53-positive when >25% of tumor cell nuclei were positively stained, and bcl-2-positive when >25% of cells showed specific cytoplasmic staining. Expression of E-cadherin was assessed by the number of cells with positive membrane expression of this marker, taking into account intensity of the reaction. Expression of topoisomerase 2 α and androgen receptors was assessed by the number of tumor cells with positive nuclear expression of these markers; number of stained nuclei per 100 nuclei in 3 fields of view was counted. Results Some differences characterizing tumor cells of molecular breast cancer subtypes were found. Tumor tissue contained higher amount of T-lymphocytes than blood (85.9 ± 2.36% vs 60.1 ± 4.5%, P P p53 overexpression was equally often recorded in luminal B and Her2+ subtypes of BC and slightly less frequently in triple-negative subtype. Accumulation of p53 was 2 times less frequently detected in luminal A subtype in comparison with triple -negative cancer and 2.5 and 2.7 times less frequently in comparison with luminal B and Her2+ BC, respectively. Study of bcl-2 expression showed reducing the frequency of positive tumor cell staining in dependence on the receptor status of tumor: positive cases were several times less frequent in triple-negative and Her2+ subtypes in comparison with luminal A and B subtypes. Luminal A subtype was characterized by the minimal p53, topoisomerase 2 α and androgen receptor expression and maximal expression of bcl-2 and E-cadherin. Luminal B subtype showed a high expression of p53, bcl-2 and androgen receptors and moderate expression of topoisomerase 2 α and E-cadherin. High expression of topoisomerase 2 α , low expression of androgen receptors and moderate expression of E- cadherin were registered in triple-negative BC. The maximal expression of topoisomerase 2 α and p53, as well as low expression of bcl-2 and E-cadherin, was observed in Her2+ subtype. Conclusions CD8+ T-lymphocytes dominate in tumor tissue of BC. Besides, tumor tissue of luminal A BC contains more NK-cells than other subtypes. A number of differences in expression of apoptosis-controlling proteins was observed in various molecular subtypes of breast cancer. Luminal A BC was noted for the minimal p53 expression and maximal bcl-2expression. Luminal B subtype had a high p53 and bcl- 2 expression. In Her2+ BC p53 expression was maximal and bcl-2 expression was low. The described differences allow assessing molecular subtypes of breast cancer and predicting the disease course from previously unexplored perspectives.