BACKGROUNDIt is urgently necessary to research an effective method to prevent and treat lung cancer since its incidence has increased sharply. The aim of this study is to investigate the regulated effects of retinoic acid (RA) on IL-1β and IFN-γ induced C3 and factor B secretion in human lung cancer cell line A549.

METHODSC3 and factor B in cultured medium were measured in lung cancer cell line A549 by ELISA and Western blot, and their cellular mRNA levels were measured by RT-PCR analysis.

RESULTSELISA, Western blot and RT-PCR results showed that IL-1β and IFN-γ could significantly increase C3 and factor B secretion and their mRNA levels in A549 cells. RA alone did not affect C3 and factor B level in A549 cells, but it could potentiated C3 and factor B secretion and their mRNA expression induced by IL-1β, as well as factor B secretion and its mRNA expression induced by IFN-γ.

CONCLUSIONSRA can up-regulate C3 and factor B secretion induced by IL-1β and IFN-γ in human lung cancer cell A549. It may stabilize the balance between stimulator cytokines and inhibitor cytokines in complement system, and play a certain role in killing tumor cells. The results suggest that combination of RA and cytokines might be effective in the treatment of lung cancer.