Data from Monoclonal antibody 14C5 targets integrin αvβ5

This study identifies and characterizes the antigen recognized by monoclonal antibody (mAb) 14C5. We compared the expression of antigen 14C5 with the expression of eight integrin subunits (α1, α2, α3, αv, β1, β2, β3, and β4) and three integrin heterodimers (αvβ3, αvβ5, and α5β1) by flow cytometry. Antigen 14C5 showed a similar expression to αvβ5 in eight different epithelial cancer cell lines (A549, A2058, C32, Capan-2, Colo16, HT-1080, HT-29, and SKBR-3). Specific binding of P1F6, an anti-αvβ5 specific antibody, was blocked by mAb 14C5. After transient expression of αvβ5 in 14C5-negative Colo16 cells, mAb 14C5 was able to bind a subpopulation of αvβ5-positive cells. We evaluated the tissue distribution of the 14C5 antigen in colon (n = 20) and lung (n = 16) cancer tissues. The colon carcinoma cells stained positive for 14C5 in 50% of tumors analyzed, whereas bronchoalveolar lung carcinoma and typical carcinoid were not positive for the antigen. More common types of non–small cell lung cancer, i.e., squamous (n = 5) and adenocarcinoma (n = 3), stained positive in 2 of 5 squamous carcinomas and in 1 of 3 investigated adenocarcinoma. Colon (95%) and lung (50%) carcinoma tissues showed extensive expression of antigen 14C5 in the stroma surrounding the tumor cells and on the membrane of the adjacent fibroblasts. We show for the first time that mAb 14C5 binds the vascular integrin αvβ5, suggesting that mAb 14C5 can be used as a screening agent to select colon and lung cancer patients that are eligible for anti-αvβ5–based therapies. [Mol Cancer Ther 2008;7(12):3771–9]