Abstract
OBJECTIVES: Sclerotium rolfsii lectin (SRL), isolated from soil born phytopathogenic fungus Sclerotium rolfsii, exhibits exquisite binding specificity to the oncofoetal Thomsen-Friedenreich (Galβ1,3GalNAcα-O-Ser/Thr, T or TF) antigen and associated glycans. In the present study, we report anti-proliferative activity of SRL and investigate underlying mechanisms of SRL-induced apoptosis, in the human ovarian cancer cell line PA-1. MATERIALS AND METHODS: SRL-induced anti-proliferative effects were determined using MTT assay and induction of apoptosis was determined by flow cytometry, confocal microscopy and western blot analysis. RESULTS: SRL inhibited population growth of PA-1 cells in a dose- and time-dependent manner with maximum inhibition (71.3 ± 1.9%) occurring at concentration of 50 μg/ml after 72 h incubation. Observed effects of SRL could be blocked by competing glycoproteins, asialomucin, mucin and fetuin. Treatment with SRL resulted in increase in hypodiploid cell population as determine by cell cycle analysis. Increase in numbers of annexin V-PI positive cells, and cleavage of PARP confirmed apoptosis-inducing activity of SRL. Involvement of caspases in SRL-mediated apoptosis was determined by cleavage of caspases-3, -8 and -9 in a time-dependent manner, thereby suggesting possible involvement of both intrinsic and extrinsic caspase-dependent pathways. CONCLUSION: The present study demonstrates anti-proliferative and apoptosis-inducing activity of SRL that can be exploited for potential application in ovarian cancer research.