Abstract 425: Alteration of ADAM9 and integrin interaction regulated cancer invasion and metastasis potential

Alteration of integrin composition is highly correlated with cancer malignancy and metastasis. Recent evidence demonstrated the metastasis activities involved the interaction of integrin and ADAM gene family, such as ADAM8, ADAM9, ADAM10 and ADAM17. These may either stabilized or cleavage of integrin-matrice interaction at the lamellipodia of cancer cell. Mahimakar et al., recently demonstrated the interaction of ADAM9 with integrins alpha3, alpha6 and beta1 by pull down assay, suggests ADAM9 might work together with β1 class integrins. To further analyze their roles and possible downstream regulatory proteins, we perform knockdown of ADAM9 using shRNA and determine its role in cancer metastasis both in vitro and in vivo. Western blotting confirmed the knockdown of ADAM9 in prostate cancer, and oral cell carcinoma. Cell migration assay was performed using micro-slide Chemotaxis chambers either with or without collagen coating. Time-Lapse microscope analysis of cell migration was plotted and analyzed. Interestingly, we observed the opposite cell migration behavior in which faster and longer cell migration activities was observed in cancer cell with knockdown of ADAM9 expression in the chamber coated with collagen, whereas less migration activities was observed in chamber without collagen coating. This may reflect the possible role of ADAM9 in alteration of integrin composition or function. Flow Cytometry analyses of integrin composition on the surface of prostate cancer cells revealed no integrin composition change in knockdown strain compared to parental. We also notice highly expression of integrin alpha2beta1 and alpha6beta4 in C4-2 and PC3 cells. Analyses of signaling pathways demonstrated no significant changes in p-FAK, p-Erk and p-Akt, suggesting not through beta1 downstream signal regulation. Immunoprecipitation of ADAM9 demonstrated the highly associated with integrin beta4 but not beta1. Intra-cardiac injection of prostate cancer cell line, PC3-pSM2C, PC3-siADAM9 demonstrated 100% metastasis activities in PC3-pSM2C, and no any metastasis in mice with PC3-siADAM9. In summary, we notice ADAM9 may associated with the activation/stabilization of integrin complex. Knockdown of ADAM9 demonstrated decreased of cell migration on dish and metastasis when inoculated in mice, suggests hemidesmosome-ADAM9 interaction may involved in cancer migration and metastasis potential. Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 102nd Annual Meeting of the American Association for Cancer Research; 2011 Apr 2-6; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2011;71(8 Suppl):Abstract nr 425. doi:10.1158/1538-7445.AM2011-425