Purpose: HER2 depended signalling pathway is dereg-ulated in a subset of non small cell lung carcinoma (NSCLC). The tumor suppressor gene PTEN (10q21) regulates the HER2/PI3K/Akt signalling pathway. Our aim was to evaluate PTEN protein expression in NSCLC based on a quantitative analysis method correlating also the results with clinicopathological parameters.
Methods: Protein expression was determined by immunohistochemistry (IHC) in 61 paraffin-embedded cases of patients with NSCLC. Digital image analysis (staining intensity levels) was performed in the corresponding immunostained slides.
Results: Loss of PTEN expression was observed in 24 (39.34%) cases, low expression in 29 (47.54%) and overexpression in 8 (13.12%) cases. Multivariate analysis determined that PTEN overexpression was associated with lower risk to develop metastases (p=0.05).
Conclusion: PTEN deregulation is a relatively frequent genetic event in NSCLC, associated with progressive metastatic process in those patients. Because of binding to the ErbB2 receptor, trastuzumab stabilizes and activates PTEN gene, and loss of its expression negatively affects the response rates in such patients.