ADAM9 is a member of the metalloprotease protein family with a disintegrin domain that plays key roles in many physiological processes such as in fertilization, migration, and cell survival, and in diseases as well, including cancer (1). ADAM9 is highly expressed in metastatic cancer tissues and so it was suggested to be involved in metastatic spreading (2). We have previously demonstrated that the recombinant disintegrin domain of ADAM9 (ADAM9D) inhibited the adhesion of both platelets and MDA-MB-231 breast tumor cells to type I collagen, a major component of the extracellular matrix (3). Here we provide additional evidence for a role of ADAM9D in metastatic spreading. ADAM9 silencing inhibited MDA-MB-231 tumor cell invasion in matrigel in approximately 72% when compared to control, without affecting the rate of cell proliferation. For transmigration endothelial assay, MDA-MB-231 cells (7x104 cells/chamber) were placed in the upper chamber covered with a monolayer of HMEC (Human Dermal Microvascular Endothelial Cells) or HUVEC (Human Umbilical Vein Endothelial Cells) and incubated for 16 hours at 37oC and 5% CO2. The effect of siADAM9 and ADAM9D on the adhesion of tumor cells was also analyzed by flow adhesion assay. 2x106 MDA-MB-231 cells (siADAM9 or control) were stimulated in a dynamic flow (5 dynes - 5 minutes) through a monolayer of HMEC cells. Transient ADAM9 silencing reduced MDA-MB-231 cells transmigration through HUVEC or HMEC. In addition, ADAM9D (1000nM) inhibited tumor cells transmigration through endothelial cells. These results suggested that ADAM9 can be involved in the processes of adhesion and transmigration and also that its disintegrin domain could be an important target for anti-metastatic therapy.
Financial Support: FAPESP, CNPq and CAPES (Brazil).
1- SEALS, D. F.; COURTNEIDGE, S. S. The ADAMs family of metalloproteases: multidomain proteins with multiple functions. Gen. Dev., 17: 7-30, 2003.
2- PEDUTO, L.; REUTER, V. E.; SHAFFER, D. R.; SCHER, H. I.; BLOBEL, C. P. Critical Function for ADAM9 in Mouse Prostate Cancer. Cancer Research, 65: 9312-9319, 2005.
3- COMINETTI, M. R.; MARTIN, A. C.; RIBEIRO, J. U.; DJAAFRI, I.; FAUVEL-LAFÈVE, F.; CRÉPIN, M.; SELISTRE-DE-ARAUJO, H. S. Inhibition of platelets and tumor cell adhesion by the disintegrin domain of human ADAM9 to collagen I under dynamic flow conditions. Biochimie., 91 (8): 1045-1052, 2009.