Analysis of expression of PTEN/PI3 K pathway and programmed cell death ligand 1 (PD-L1) in malignant pleural mesothelioma (MPM)

Background: Malignant pleural mesothelioma (MPM) frequently express elevated AKT/mTOR activity. Previous reports in gliomas, colon, breast and prostate cancer suggest that PTEN/PI3 K pathway may be important for the induction of PD-L1 expression. This study explored the expression of PTEN/PI3 K pathway and PD-L1 in MPM and its relationship with the patient's prognosis. Material and methods: Twenty seven consecutive MPM patients were reviewed. Formalin-fixed, paraffin-embedded tissue biopsies were used for immunohistochemical analysis of PTEN/PI3 K pathway and PD-L1. Results: Expression of PTEN, mTOR, pAKT, p4EBP1, peif4E, pS6 and FOXO3a was found in 88.5%, 92.3%, 78.3%, 38.5%, 100%, 52.2% and 100% of tumors and PD-L1 in 23%. We found a significant correlation between pAKT, FOXO3a and PD-L1 expression and longer overall survival (p < 0.05). We did not identify significant association between the level of PD-L1 expression and alterations in PI3 K pathway. Conclusions: This study shows PTEN/PI3 K pathway and PD-L1 in MPM are frequently activated. Our results suggests that there is not association between PD-L1 and the involvement of the PI3 K pathway in MPM.