Expression of Activated and Latent Signal Transducer and Activator of Transcription 3 in 303 Non-Small Cell Lung Carcinomas and 44 Malignant Mesotheliomas Possible Role for Chemotherapeutic Intervention

Abstract

Abstract Context.—Signal transducer and activator of transcription 3 (STAT3) is constitutively activated in diverse human cancers and plays a critical role in tumor cell survival, proliferation, migration, invasion, angiogenesis, and inhibition of apoptosis. The phosphorylated active form of STAT3 (pSTAT3) mediates its effects via nuclear transcriptional activity. However, it was recently observed that the nonphosphorylated, cytoplasmic, inactive form of STAT3 is involved in cell motility and consequently tumor invasion. It appears that, although STAT3 is not absolutely required for tumor formation, tumors that develop in the presence of STAT3 become dependent on its expression for their survival, making it a potential therapeutic target. Objective.—To investigate the possible utility of STAT3 as a future therapeutic target in non–small cell lung carcinoma (NSCLC) and malignant mesothelioma (MM). Design.—Immunohistochemical expression of MIB-1, STAT3, and pSTAT3 was assessed in 303 NSCLC and 44 MM archiva...