OBJECTIVETo detect the presence of ion channel protein and its role in cell growth and proliferation in human head and neck squamous carcinoma cells (SCC).

METHODSHuman head and neck squamous carcinoma SCC-25 cell line was tested with transient receptor potential melastatin 7 (TRPM7) antibody using the method of immunocytochemistry. The role of TRPM7 in cell growth and proliferation was evaluated through its blockade by ion channel blockers and specific siRNA using lactate dehydrogenase (LDH) assay technique.

RESULTSClear immunoreactivity against TRPM7 was detected in almost all SCC-25 cells tested, whereas no immunoreactivity was observed in negative control. The inhibitory effect of Gd3+, a non-specific ion channel blocker, on cell growth and proliferation was potent. Addition of 10 micromol/L Gd3+ (n = 16) and 100 micromol/L Gd3+ (n = 16) in the culture medium significantly inhibited the growth of SCC-25 cells, as compared with control cells growing in normal medium (t was 4.1414 and 6.2661, P was 0.0256 and 0.0082 respectively). However, the effect of 2-APB was striking. Cell proliferation was almost totally suppressed in the presence of 100 micromol/L 2-APB (t = 13.4493, P = 0.0008, n = 16) compared with cells growing in normal medium. Suppression of TRPM7 expression by siRNA also significantly inhibited the growth and proliferation of these cells (t = 4.3446, P = 0.0002, n = 32, compared with nontransfected cells),whereas cells transfected with negative control siRNA showed no difference in cell proliferation compared with nontransfected cells.

CONCLUSIONSAll of those results strongly suggest the existence of TRPM7 channel in human head and neck squamous carcinoma cells. Ion channel blockers serve as a potent inhibitor of SCC-25 cell proliferation. The striking inhibitory effect of 2-APB on cell growth and proliferation may promise clinical workers an inspiring remedy for fighting against carcinoma.