Heterogeneous expression and regulation of CD40 in human hepatocellular carcinoma

Objective CD40, a member of the tumour necrosis factor receptor family, plays a major role in adaptive immune responses and contributes to cancer surveillance. Conflicting results have been reported recently on the expression and function of CD40 in carcinomas. The aim of the present study was to investigate the role of CD40 in human hepatoma. Design/methods CD40 expression was examined in hepatomas in situ and derived cell lines by immunohistochemistry, flow cytometry and reverse transcriptase polymerase chain reaction. We investigated in hepatoma cell lines the regulation of CD40 by proinflammatory cytokines and the effects of its ligation with soluble CD40L on the expression of co-stimulatory and pro-apoptotic cell-surface molecules and survival. Results CD40 was detected with a similar frequency of about 40% in hepatoma specimens and derived cell lines but not in normal hepatocytes. Tumour necrosis factor alpha and its combination with interferon gamma upregulated CD40 only in intrinsically positive cell lines. CD40 ligation had no effect on cell viability or surface expression of CD54, CD80, CD86 or CD95. Conclusions CD40 is expressed variably in human hepatoma and enhanced by distinct pro-inflammatory cytokines. The lack of detectable effects of CD40 ligation does not support a major role of this molecule in hepatocellular carcinoma biology.