Abstract
The CD40 protein on the surface of B cells has several functions: induction of isotype switching in the presence of cytokine; proliferation, association with apoptosis, et al. In this study, we investigated whether head and neck cancer cell lines have CD40 on the surface of tumor cells and what would be induced by the signal of CD40. In only HTC/C3 cell line derived from thyroid cancer, CD40 was detected by a flowcytometry among five cell lines (KB, IMC-2, IMC-3, CA-19.9). The addition of anti-CD40 Ab inhibited the colony formation by HTC/C3 cell line, but not inhibited that of other four cell lines. No cytotoxicity of CD40 signal to HTC/C3 cell line was observed by MTT assay. CD40 signal enhanced the expression of Bcl-2 in HTC/C3 cell line, suggesting the Bcl-2 is associated with slow-growth of the tumor cells by CD40 stimulation. Further study concerning the inhibition of cell growth in HTC/C3 by anti-CD40 Ab is required to clarify the role of CD40 signal.
