OBJECTIVETo determine the modulating effect of CD40 ligand (CD40L, CD154) on CD40-transfected human lung carcinomas and to assess the potential of CD40 as a therapeutic target.

METHODSTumor cells of a CD40-negative lung cancer cell lines (GLC-82) were transfected with a vector expressing CD40 cDNA. The transfected cell line, GLC-82/CD40, was shown to express high levels of CD40. GLC-82/CD40 cells after being exposed to 0.1 micro g/ml CD40L were examined for their surface expression, cell cycle, apoptosis and cell growth by flow cytometry and MTT assay.

RESULTSThe expression of MHC-I, ICAM-1 and Fas in GLC-82/CD40 cells was significantly increased, whereas that of EGFR was decreased. Cell proliferation was significantly inhibited by CD40L with an inhibition rate of 30% on day 5, but no change in cell cycle. All of the changes disappeared after 48 h incubation with CD40L. More significant changes were observed in Calu-3 cell lines which expressed high levels of CD40, but the CD40-negative GLC-82 cells were unresponsive to CD40L. None of the 3 cell lines showed significant changes in apoptosis upon CD40L treatment.

CONCLUSIONCD40, if over-expressed in tumor cells, could be considered as a potential therapeutic target.