Background: PIK3CA and GSK-3β have important role(s) in the resistance of estrogen receptor positive (+ER) breast cancer (BC) patients to hormonal therapy. The aim of the current study was to assess the role of PIK3CA and GSK-3β in predicting response to Tamoxifen in BC patients.
Methods: PIK3CA and GSK-3β expression levels were assessed in formalin fixed paraffin embedded tissue (FFPE) sections of 58 hormonal positive BC females, using quantitative real time PCR (RT-qPCR). The data were correlated to clinico-pathological features of the patients, response to Tamoxifen and survival outcome.
Results: The median PIK3CA expression increased significantly in non-responders to tamoxifen compared to responders [2.94 (IQR=7.5) and 0.72 (IQR=0.9); respectively, P= 0.017]. However, there was no significant difference in GSK-3β expression between responders and non-responders BC patients [1.5 (IQR=3.8) and 1.2 (IQR=2.8); respectively, P= 0.27]. PIK3CA expression associated with low ER expression, presence of distant metastasis and shorter disease free survival (DFS) rate (P=0.032, 0.026 and 0.043; respectively). GSK-3β expression increased significantly in negative LN metastasis and low-expression of progesterone receptors (P=0.01 and 0.006; respectively). There was significant correlation between the expression levels of GSK-3B and PIK3CA in BC patients (r=0.88, P