PTEN mutations prevalence in HER2-positive breast cancer patients

Abstract

Introduction: HER2-positive tumors is one of the aggressive subtypes of breast cancer that indicate bad prognosis. Trastuzumab is one of the targeted therapy which inhibit HER2 receptors. Mutations/expression deregulations of the downstream of HER2 receptors could cause resistance to trastuzumab. PTEN is a tumor suppressor gene which directly regulates PI3K pathway which renders it one of the predictive markers of trastuzumab. Methods: In the present study, PTEN mutations were screened in 51 patients with HER2-positive breast cancer. Also, 16 patients were further analyzed for protein expression. Results: The mutations were detected in 3 out of 51 patients (5.9%). In addition, 56.3% of the 16 patients showed downregulation/loss of PTEN protein expression. The loss of PTEN was found in 75% of estrogen-receptor negative patients (p = 0.130). Conclusions: The downregulation/loss of PTEN protein has the tendency to be associated with ER-negative reflecting its value as a treatment prediction marker.