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.