Differential express-ion of STAT5 and Bcl-xL, and high expression of Neu and STAT3 in non-small-cell lung carcinoma

Experimental evidence suggests that in lung cancer, development, progression and an increased proliferation rate can be linked to apoptosis-related factors. The objective of this study is to evaluate the status of Neu, signal transducer and activator of transcription (STAT)-3, STAT5 and Bcl-x(L) expression in non-small-cell lung cancer. We investigated the immunohistochemical expression of these proteins in 92 non-small-cell lung cancer specimens to establish their rote in lung cancer pathogenesis. Neu was overexpressed in 65% of cases, and although STAT3 was overexpressed in 52.1% in cytoplasm, it was expressed in nucleus (activated) in 60.8%. Meanwhile, STAT5 was found overexpressed in 41.3% in cytoplasm and 32.6% in nucleus. Thus, Bcl-x(L) was overexpressed in cytoplasm in 81.5%. Interestingly, we found nuclear expression of Bcl-x(L) in 30.4% of cases. Finally, we found correlation among histological types of lung cancer and nuclear expression of both STAT5 (P = 0.005) and nuclear Bcl-x(L) (P = 0.003). Besides, nuclear expression of Bcl-x(L) was correlated with TNM stage IV (distant metastasis) (P=0.02). These results suggest for the first time, a relevant role for STAT5 and Bcl-x(L) as apoptosis-regulatory proteins in the pathogenesis of lung cancer, and overexpression of both Neu and activated STAT3, could be related with the proliferation rate in lung carcinoma cells. (C) 2006 Elsevier Ireland Ltd. All rights reserved.