Tumstatin induces apoptosis mediated by Fas signaling pathway in oral squamous cell carcinoma SCC-VII cells

Oral squamous cell carcinoma is a cancer originating in the tissues lining the mouth and lips. The present study investigated the effects of recombinant tumstatin, an anti-angiogenic agent with distinct antitumor activity, on oral squamous cell carcinoma SCC-VII cells. Apoptosis was characterized by YO-PRO-1 staining, sub-G1 population, and DNA fragmentation analysis. Apoptotic mechanism of tumstatin was also investigated. The antitumor activity of tumstatin was further evaluated using an SCC-VII animal model. Recombinant tumstatin was found to decrease the viability of SCC-VII cells in a dose-dependent manner. The number of cells stained with the apoptotic marker YO-PRO-1, the sub-G1 cell population and the level of apoptotic DNA fragmentation increased in the SCC-VII cells following treatment with recombinant tumstatin. In addition, recombinant tumstatin treatment increased the expression of the Fas gene at the transcript and protein levels, and the inhibition of cell viability by recombinant tumstatin was suppressed by a neutralizing anti-Fas antibody. Furthermore, treatment with recombinant tumstatin decreased the volume and weight of tumors in C3H/HeJ mice implanted with SCC-VII cells. In conclusion, the results indicated that tumstatin induced apoptosis that is mediated by the Fas signaling pathway in SCC-VII cells and inhibited tumor growth in an SCC-VII animal model.