Expression of c-met/HGF receptor in human non-small cell lung carcinomas in vitro and in vivo and its prognostic significance

The expression of c-met/HGF receptor was evaluated in non-small cell lung cancers (NSCLC) by western blot analysis of 11 established cell lines and 104 surgically resected tissues. All cancer cell lines (eight adenocarcinomas, two squamous cell carcinomas and a large cell carcinoma) showed strong c-met protein bands of 145 kDa and 170 kDa. Moreover, c-met protein was demonstrated in 34 (72.3%) of 47 surgically resected adenocarcinomas, 20 (38.5%) of 52 squamous cell carcinomas and 3 of 5 others, and the results were mostly confirmed immunohistochemically in formalin-fixed and paraffin-embedded tumors of the same case. Although squamous cell carcinomas showed relatively high c-met protein expression in established cell lines, more adenocarcinomas than squamous cell carcinomas showed c-met protein expression in the original cancers. Furthermore, two cell lines used in this study originated from primary cancers negative for c-met protein expression, suggesting that c-met protein expression might be influenced by cultivation. Furthermore, clinicopathological study revealed that NSCLC with c-met protein expression tended to be in a higher pathological tumor stage and to have a worse outcome than those without such expression. In conclusion, c-met protein is expressed in cell lines and primary tumors of NSCLC, and this phenomenon is probably closely related to the aggressive behavior or progression of NSCLC, especially of adenocarcinomas.