Abstract 2608: MMP-7 increases migration by decreasing intercellular E-cadherin and F-actin localization in prostate cancer micro-tumors formed by perlecan/HSPG2

Introduction: Polarized epithelium is maintained by cell-cell interactions via cadherins and cell adhesion molecules (CAMs). Interactions are stabilized further by cell-matrix interactions on the basement membrane where perlecan/HSPG2 is a major component that controls signaling in resting tissues with unperturbed matrices. Proteolytic cleavage of perlecan increases cell-matrix interactions and dysregulates cell signaling, permitting migration. Previous studies showed perlecan domain IV-3 (DmIV-3) drives cell cohesion and, when digested with matrix metalloproteinase-7 (MMP-7), drives cell dyscohesion. In vivo, prostate cancer (PCa) patients with bone metastases have circulating DmIV fragments, with negative correlation between MMP-7 staining and loss of perlecan in tissue samples. MMP-7 can cleave cadherins and other CAMs disrupting cell-cell adhesions. Also, DmIV-3 fragments generated by MMP-7 cleavage may further induce cell dyscohesion by disrupting interactions between CAMs and/or cadherins. Methods: To evaluate the impact of MMP-7 and DmIV-3 fragments on cell migration or cluster dyscohesion, uniformly sized PCa cell clusters were pre-formed using a microwell system, enabling control of cluster size and cellularity. Pre-formed cell clusters were transferred to DmIV-3 coated wells for 16-24 hours. Clusters then were treated with MMP-7 alone or MMP-7 plus DmIV-3 fragments during live cell imaging and cell tracking. Immunofluorescent staining and Imaris analysis of fixed cell clusters at different stages of cohesion and dyscohesion was performed to determine cytoskeletal architecture and stability. The alignment of E-cadherin and F-actin served as a quantitative measure of cohesion. Results: PCa cell clusters maintained strong cell-cell contacts with intact DmIV-3. In contrast, pre-formed PCa cell clusters cultured in the presence of DmIV-3 cleaved by MMP-7 showed dyscohesion and increased cell migration initiated at the cluster edges where migratory velocity was highest. Pre-formed PCa cell clusters treated with MMP-7 had increased F-actin reorganization during various stages of PCa cell cluster dyscohesion. E-cadherin and F-actin co-alignment at cell-cell contacts was reduced in PCa cell clusters treated with MMP-7 and DmIV-3 fragments, particularly at the edges where cell-cell adhesion was lowest and cell-matrix interactions were highest. Conclusion: Following patterns of dyscohesion of pre-formed PCa micro-tumors provides a good model to study dynamic changes in protein components involved in cell-cell interactions and quantitate cell migration patterns as they can occur in metastasis and circulating tumor cell formation. Actin reorganization promotes a migratory cell phenotype in PCa cell clusters treated with MMP-7 and DmIV-3 fragments. Future studies aim to identify DmIV3 fragment(s) positively associated with tumor dyscohesion that may play key roles in secondary metastasis formation. Citation Format: Lissette A. Cruz, Tristen V. Tellman, Brian J. Grindel, Daniel D. Carson, Mary C. Farach-Carson. MMP-7 increases migration by decreasing intercellular E-cadherin and F-actin localization in prostate cancer micro-tumors formed by perlecan/HSPG2 [abstract]. In: Proceedings of the Annual Meeting of the American Association for Cancer Research 2020; 2020 Apr 27-28 and Jun 22-24. Philadelphia (PA): AACR; Cancer Res 2020;80(16 Suppl):Abstract nr 2608.