Disintegrins are low molecular weight peptides derived from viper venom. Previous studies have shown

that disintegrins induce anti-cancer effects in multiple cancer cell lines through interactions with integrin

receptors. Ligand interactions cause integrin clustering and inside-out integrin-signaling, which affects many

cell functions, such as: cell adhesion, cytoskeletal organization, cell growth, differentiation, migration,

angiogenesis, and apoptosis. Our studies have shown that recombinant (r) Mojastin disintegrins exert anti-

cancer effects in multiple cell lines at varying degrees dependent upon their amino acid (AA) composition, in

which site-directed mutagenesis was utilized to manipulate the AA sequence carboxyl to the integrin-binding

motif. Interestingly, r-Mojastin D-mutant disintegrins (r-Moj-D_) evoke the most prominent phenotypes in

apoptotic induction (TUNEL assay), cell proliferation inhibition (WST-1 assay), and cell migration inhibition

(wound-healing assay) of SK-Mel-28 cells (a highly invasive human melanoma cell line). However, the key

signaling cascades, transcriptional targets, and cell-specific integrin receptors utilized in the cells’ responses are

not known.

To illuminate critical integrin-dependent signal transduction pathways important in the anti-cancer

effects of r-Moj-D_ disintegrins and the cell-specific integrin receptors that interact with r-Moj-D_ mutants, we

utilized a functional genomics approach, including: whole transcriptome RNA sequencing (RNA-SEQ), qRT-

PCR gene expression studies, RNAi, and immunocytochemistry. Our results indicate functional roles of the αv

integrin subunit in cell migration and proliferation of SK-Mel-28 cells, due to the lack of wound closure (n=2)

and obliteration of cell-proliferation inhibition in αv knockdown cells treated with r-Moj-D_ peptides for 24, 36,

or 48hrs compared to scrambled controls. Furthermore, RNA-SEQ results aligned with Bowtie and further

analyzed using Cuffdiff, edgeR, and DESq algorithms identified 37 genes as differentially expressed (p≤

0.00015) in SK-Mel-28 cells after treatment with r-Moj-DM for 6 hrs. Utilizing the Database for Annotation,

Visualization and Integrated Discovery (DAVID) tool, we found that many of the genes identified in our RNA-

SEQ data are involved in the regulation of cell migration, proliferation and apoptosis. Our gene list will be

validated by qRT-PCR. Future studies will include protein analysis of the focal adhesion complex and related

integrin-dependent signaling networks. These results will elucidate the signal transduction pathways affected by

Mojastin disintegrins and may be instrumental in the development of alternative cancer therapeutics.