Pathological and functional significance of Semaphorin-5A in pancreatic cancer progression and metastasis.

Semaphorin-5A (SEMA5A) has differential cell surface expression between normal and cancer cells and represents an attractive target for therapeutic intervention in pancreatic cancer (PC). In this study, we delineated the pathological expression and significance of SEMA5A during PC progression and metastasis. We utilized human tissue microarrays and different PC mouse models (Pdx1-cre; LSL- Kras(G12D) , Pdx1-Cre; LSL-Kras(G12D) ; LSL-p53(R172H) and RIP1-Tag2) to analyze SEMA5A expression during PC progression. Using human patients and different mouse models, we demonstrated that SEMA5A expression was highest in liver metastases, followed by primary pancreatic tumors, and the lowest expression was found in the normal pancreas. SEMA5A expression was localized on tumor cells with no staining in the surrounding stroma. To understand the functional significance of SEMA5A, we treated PC cell lines with recombinant SEMA5A. We observed an increase in migration, chemotaxis, and scattering of PC cells. To delineate the signaling axis of SEMA5A, we generated SEMA5A receptor-Plexin-B3 knockdown in T3M-4 and CD18/HPAF PC cell lines and observed that the effect of SEMA5A treatment was absent in the Plexin-B3 knockdown counterparts of T3M-4 and CD18/HPAF cells. SEMA5A treatment leads to phosphorylation of cMET in Plexin-B3 dependent manner. Our data demonstrate that there is an increase in SEMA5A expression during PC progression and the elevation of this expression takes place at metastatic sites especially the liver in both exocrine and endocrine tumors. SEMA5A can elicit a migratory response in cells by activating cMET through the Plexin-B3 receptor. In conclusion, SEMA5A signaling represents a potential molecule for targeting metastasis in pancreatic cancer.