Inhibition of SK-Mel 28 cell proliferation by recombinant mojastin (r-moj) disintegrins

Integrin receptors are transmembrane proteins that contain α and β subunits. This molecular structure allows integrins to bind to the extracellular matrix (ECM). As a consequence, integrins undergo signal transduction that result in various cellular behaviors. Disintegrins, small molecular weight peptides found in viper venom, bind to integrins via a RGD binding motif and trigger a variety of cellular responses. Previous research has shown that the recombinant mojastin (r-Moj-DM) disintegrin inhibits cell proliferation, migration and induces apoptosis of SK-Mel-28 cells. We hypothesize that different mutated versions of r-Moj peptides will inhibit cell proliferation of SK-Mel-28 cells. Six r-Moj peptides containing mutations immediately carboxyl to the RGD were tested. A colorimetric WST-1 cell proliferation assay was used to determine cellular proliferation inhibition of SK-Mel-28 cells. r-Moj peptides were purified using GST batch purification followed by thrombin cleavage. Once the peptides were purified, 32,000 SK-Mel-28 cells/well were seeded into 27 well of a 96-well plate and grown for 24 hrs. Cells were treated with purified peptide, in triplicate, at 3.5 μM and incubated for 24 hrs. Preliminary results indicated that r-Moj-WM (46%) and r-Moj-WP (33%) peptides inhibited cell proliferation significantly (p<0.05), while the other r-Moj peptides failed to do so.  Our results may suggest a role for the W amino acid immediately carboxyl of the RGD motif on r-Moj peptides.  This research was funded by NSF-REU #DBI 1004350 grant.