Methods: Using the MTT assay to assess the effects of HNP-1 on breast epithelial cell lines in vitro, we observed a selective cytotoxic effect on tumour cells. We now aim to determine the effects of HNP-1 on oral tumour and non-tumour cells. The level of expression of sialic acid on oral cell lines will be assessed using lectin blotting with a sialic acid specific lectin. To further investigate the role of sialic acid, we plan to remove sialic acid residues from the tumour cells enzymatically with neuramindase. We will then challenge neuraminidase treated cells with HNP-1 and determine differences in HNP-1 mediated cytotoxicity using the MTT assay.
Results: The data generated from these experiments will provide us with an insight into the role of aberrant glycosylation in conferring susceptibility of oral tumour cells to cationic HNP-1.
Conclusions: Our preliminary data suggests a role for over-expressed sialic acid residues in mediating HNP-1 susceptibility in breast cancer cells. A more extensive study on oral cell lines could lend support to the view that the initial electrostatic interaction between HNP-1 (or other cationic antimicrobial peptides) with the negatively charged oral tumour cell membrane is essential in mediating defensin cytotoxicity.