Inhibition of melanoma growth by hemocyanin occurs via early apoptotic pathways

Background We hypothesized that keyhole limpet hemocyanin (KLH) would reduce cellular proliferation and effect apoptosis of melanoma cell lines in vitro. Methods Two human melanoma cell lines (HTB68 and HTB72) were subjected to a dose-response treatment regimen of KLH (0.4 μg to 100 μg/well). Cell viability was tested by MTT assay (SIGMA, St Louis, MO) at 72 hours. Apoptosis and necrosis were measured by the Annexin V FITC assay (Biovision Inc, Mountain View, CA). Results Melanoma cell proliferation was significantly reduced in the HTB68 cell line treated with 6.3 μg or higher doses of KLH. A significant reduction in cell growth was also observed in the HTB72 cells at 50 and 100 μg of KLH. KLH increased early apoptotic activity, whereas both late apoptosis and necrosis were decreased by the addition of KLH. Conclusions KLH significantly reduces cellular proliferation in vitro in melanoma, via early apoptotic pathways. The results warrant in vivo studies into the effects of KLH in melanoma.