Induction of non-apoptotic cell death by sodium 5,6-benzylidene-L-ascorbate in a human salivary gland tumor cell line

We investigated whether sodium 5,6-benzylidene-L-ascorbate (SBA) induces ap optotic cell death in a human salivary gland tumor cell line HSG, using two different cytochemical methods. Millimolar concentrations of SBA dose-depe ndently reduced the viable cell number of HSG cells, accompanied by the det achment of dying cells from the culture plates. The nuclei of the dying cel ls were not stained with TUNEL reagent, indicating the lack of DNA nicks or fragments. On the other hand, the nuclei of epigallocatechin gallate (EGCG )-treated cells (positive control) were TUNEL-positive, demonstrating the p roduction of DNA nicks or fragments. Furthermore, the cytoplasms of SBA-tre ated cells were not stained with M30 monoclonal antibody, which reacts with the degradation products of cytokeratin 18 by the activated caspases, in c ontrast to those of EGCG-treated cells. These results suggest that SBA indu ces non-apoptotic cell death, possibly necrosis, in HSG cells.