Evaluation of PIK3CA Status in Breast Cancer and their Correlation with ER, PR, and HER-2 expressions in Iraqi female patients

Abstract

The present study revealed that the PIK3CA, catalytic subunit of phosphatidylinositol 3-kinase (PI3K), is mutated in breast cancer. This study was carried out in the laboratory of molecular biology in the Department of Biology in the College of Science – Kufa University, during the period from July 2013 through March 2014. Paraffin blocks of thirty one patients with breast carcinoma were included in this study. These samples were collected from laboratory of histopathology in Alsader Teaching Hospital in Al-Najaf governorate. Six samples with normal breast tissues were considered as control group for this study. Their ages ranged from 30 to 65 years, with a mean age of 49.9 years. Carcinoma tissue samples were evaluated previously for ER, PR and HER-2 by Immunohistochemical analysis. The diagnosis was under the supervision of pathologist in the hospital. The clinicopathological assessment revealed that 14 (45.16%) were hormone dependent carcinoma: ER+PR+, 3 (9.67 %) and 9 (16.12%) were probably hormone dependent carcinoma: ER+PR-; ER-PR+, and 5 (29.03%) were hormone independent carcinoma: ER-PR-. HER-2 expression was found in 7(22.58%) of cases. Mutational analysis of PIK3CA was done in 31 breast cancers and, finally, 11 (35.48%) mutations were identified in total. The frequency of PIK3CA mutations in ER-positive tumors was significantly (p < 0.05) higher than that in ER- negative tumors , and the frequency of PIK3CA mutations in PR-positive tumors tended to be higher than that in PR-negative tumors. HER2 expression was not significantly associated with PIK3CA mutations.