Phytohemagglutinin isoforms as inducers of apoptosis in tumor cells in vitro
Aim. To study the effect of phytohemagglutinin (PHA) and its specific isoforms on the frequency of apoptosis in cell culture of larynx cancer (Hep-2), and explore possible ways for apoptosis inducing by lectins studied. Methods. Evaluation of the apoptotic cells frequency was performed using specific fluorescent staining dyes. The level of expression for mediators of apoptosis (caspase-3 and caspase-8) and Bax proapoptotic protein was studied using Western blot analysis. Results. The total PHA drug and its isoforms were shown to be able to induce apoptosis in larynx cancer cell culture under experimental conditions. Both the total PHA drug and its individual isoforms were found to cause apoptosis in human tumor cells, inducing caspase-3 and - 8 as well as proapoptotic Bax protein. Most effective inducer of both caspase 3 and morphological changes of the nucleus, typical for apoptosis proved to be the glycoprotein-specific erythrocytic isoform (PHA-E). Conclusions. Total PHA drug and its individual isoforms may cause increased frequency of apoptosis in human larynx cancer cell culture indirectly involving caspase-dependent and mitochondrial mechanisms.
Key words: phytohemagglutinin, isolectins, apoptosis, caspase-3, caspase-8, Bax protein.