Bone Metastasis Inhibition of Cell Adhesion by a Cadherin-11 Antibody Thwarts

Cadherin-11 (CDH11) is a member of the cadherin superfamily mainly expressed in osteoblasts but not in epithelial cells. However, prostate cancer cells with a propensity for bone metastasis express high levels of cadherin11 and reduced levels of E-cadherin. Downregulation of cadherin-11 inhibits interaction of prostate cancer cells with osteoblasts in vitro and homing of prostate cancer cells to bone in an animalmodel ofmetastasis. These findings indicate that targeting cadherin-11may prevent prostate cancer bonemetastasis. To explore this possibility, a panel of 21 monoclonal antibodies (mAb) was generated against the extracellular (EC) domain of cadherin-11. Two antibodies, mAbs 2C7 and 1A5, inhibited cadherin-11–mediated cell–cell aggregation in vitro using L-cells transfected with cadherin-11. Both antibodies demonstrated specificity to cadherin-11, and neither antibody recognized E-cadherin or N-cadherin on C4-2B or PC3 cells, respectively. Furthermore, mAb 2C7 inhibited cadherin-11–mediated aggregation between the highly metastatic PC3-mm2 cells and MC3T3-E1 osteoblasts. Mechanistically, a series of deletion mutants revealed a unique motif, aa 343-348, in the cadherin-11 EC3 domain that is recognized by mAb 2C7 and that this motif coordinated cell–cell adhesion. Importantly, administration of mAb 2C7 in a prophylactic setting effectively prevented metastasis of PC3-mm2 cells to bone in an in vivomouse model. These results show that targeting the extracellular domain of cadherin-11 can limit cellular adhesion and metastatic dissemination of prostate cancer cells. Implications: Monotherapy using a cadherin-11 antibody is a suitable option for the prevention of bone metastases. Mol Cancer Res; 11(11); 1401–11. 2013 AACR.