Human complement factor H is a novel diagnostic marker for lung adenocarcinoma
Background Human complement factor H (CFH), a central complement control protein, is a member of the regulators of complement activation family. Recent studies suggested that CFH may play a key role in resistance of complement mediated lysis in various cancer cells. In this study, we investigated the role of CFH in human lung cancer. Methods Expression of CFH in lung cancer cells was analyzed by RT-PCR, western blotting, and immunofluorescence. Binding of CFH to lung cancer cells was detected by flow cytometry. In primary lung tumors, the protein expression of CFH was evaluated by IHC on tissue microarray. Results We found, mRNA expression of CFH was detected in six out of ten NSCLC cell lines, but not in SCLC cell lines. Consistence with the western blotting result, immunofluorescence analysis demonstrated CFH protein expression in three NSCLC cell lines, and the immunoreaction was mainly associated with cell cytoplasm and membrane. In primary lung tumors, 54 out of 101 samples exhibited high expression of CFH, and high expression was significantly correlated with lung adenocarcinoma (p=0.009). Also, in ADC of lung, Kaplan-Meier survival analysis showed a tendency that CFH-positive tumors had worse prognosis in comparison to CFH-negative tumors (p=0.082). Additionally, shorter survival time of patients with ADC (less than 20 months) was associated with higher protein expression of CFH (p=0.033). Conclusion Our data showed that non-small cell lung cancer cells expressed and secreted CFH. CFH might be a novel diagnostic marker for human lung adenocarcinoma.