Expression of neuron-specific enolase, chromogranin A, synaptophysin and Leu-7 in lung cancer cell lines.

Recent reports indicate that Small Cell Lung Cancer (SCLC) responds favorably to chemotherapy, and this response is associated with the expression of neuroendocrine (NE) markers. However, the currently available reports on the expression of NE markers in SCLC and Non-Small Cell Lung Cancer (NSCLC) are highly inconsistent and need to be reevaluated. Therefore, we have undertaken the current study to clearly define the expression of NE markers in SCLC and NSCLC using representative cell lines. We studied the NE markers, chromogranin A, Neuron specific enolase (NSE), Leu-7 and synaptophysin using various immunochemical and molecular biological methods. By employing Western blotting method, we found that both SCLC and NSCLC cells express large amounts of NSE and chromogranin A. The natural killer cell surface associated antigen (Leu-7) was expressed specifically only by SCLC cell lines. This finding was further confirmed by immunofluorescence staining of the SCLC cells. We could not detect any synaptophysin levels in any of the above cell types by Western blotting technique. Therefore, we employed reverse transcription polymerase chain reaction (RT.PCR) to study the expression of synaptophysin mRNA and found that both SCLC and NSCLC cells express it, albeit in different amounts.