Interleukin 13 (IL-13)-regulated expression of the chondroprotective metalloproteinase ADAM15 is reduced in aging cartilage

Objective

The adamalysin metalloproteinase 15 (ADAM15) has been shown to protect against development of osteoarthritis in mice. Here, we have investigated factors that control ADAM15 levels in cartilage.

Design

Secretomes from wild-type and Adam15^−/− chondrocytes were compared by label-free quantitative mass spectrometry. mRNA was isolated from murine knee joints, either with or without surgical induction of osteoarthritis on male C57BL/6 mice, and the expression of Adam15 and other related genes quantified by RT-qPCR. ADAM15 in human normal and osteoarthritic cartilage was investigated similarly and by fluorescent immunohistochemistry. Cultured HTB94 chondrosarcoma cells were treated with various anabolic and catabolic stimuli, and ADAM15 mRNA and protein levels evaluated.

Results

There were no significant differences in the secretomes of chondrocytes from WT and Adam15^−/− cartilage. Expression of ADAM15 was not altered in either human or murine osteoarthritic cartilage relative to disease-free controls. However, expression of ADAM15 was markedly reduced upon aging in both species, to the extent that expression in joints of 18-month-old mice was 45-fold lower than in that 4.5-month-old animals. IL-13 increased expression of ADAM15 in HTB94 ​cells by 2.5-fold, while modulators of senescence and autophagy pathways had no effect. Expression of Il13 in the joint was reduced with aging, suggesting this cytokine may control ADAM15 levels in the joint.

Conclusion

Expression of the chondroprotective metalloproteinase ADAM15 is reduced in aging human and murine joints, possibly due to a concomitant reduction in IL-13 expression. We thus propose IL-13 as a novel factor contributing to increased osteoarthritis risk upon aging.

A surgical orthotopic approach for studying the invasive progression of human bladder cancer

The invasion of bladder cancer into the sub-urothelial muscle and vasculature are key determinants leading to lethal metastatic progression. However, the molecular basis is poorly understood, partly because of the lack of uncomplicated and reliable models that recapitulate the biology of locally invasive disease. We developed a surgical grafting technique, characterized by a simple, rapid, reproducible and high-efficiency approach, to recapitulate the pathobiological events of human bladder cancer invasion in mice. This technique consists of a small laparotomy and direct implantation of human cancer cells into the bladder lumen. Unlike other protocols, it does not require debriding of the urothelial lining, injection into the bladder wall, specialized imaging equipment, bladder catheterization or costly surgical equipment. With minimal practice, the procedure can be executed in <10 min. Tumors develop with a high take rate, and most cell lines exhibit local invasion within 4 weeks of implantation.

Abstract LB-B08: Validation of ADAM15 as a therapeutic target in invasive bladder cancer cells

Introduction: Advanced bladder cancer is a deadly and costly disease with locally invasive tumors carrying the worst prognosis for progression and mortality. The ADAM15 membrane disintegrin is key regulator in the invasive processes. Our previous studies demonstrated that increased expression of ADAM15 mRNA and protein is significantly associated with the local submucosal and lymphovascular invasion (LVI) and metastatic progression of human bladder cancer. Additionally, ADAM15 mediates integrin binding and has specifically been linked to the tumor-associated β1 integrins. This study aims to understand the ADAM15 disintegrin function and its potential as target in invasive bladder cancer. Methods: Collagen I represents the bulk of the submucosal matrix in the bladder and likely contributes to bladder cancer progression. Here, we developed a 3-dimensional (3D) culture system in collagen I to evaluate the phenotype of a panel of invasive bladder cancer cells. Furthermore, we developed a cyclic hexapeptide based on ADAM15 structure (adamatide), which can bind to the β1 integrin binding site; a rabbit polyclonal antibody against ADAM15 disintegrin domain (anti-A15DD); and, human recombinant ADAM15 disintegrin domain (hrA15DD) to compete with the endogenous protein. The effect of these inhibitors was evaluated on our 3D systems and compared to previously stablished ADAM15 knockdowns (shADAM15) in bladder cancer cell lines. Results: We assessed ADAM15 expression by Western blotting and immunofluorescence imaging in a panel of invasive bladder cancer cells. ADAM15 was highly expressed in the invasive cell lines, including UM-UC6 and UM-UC9. However, when cells were grown on plastic, ADAM15 was exclusively localized in cytoplasmic vesicles. On the contrary, when using 3D collagen cultures, ADAM15 translocated to filopodium-like protrusions (FLPs) on the cell membrane. Confocal imaging showed both co-expression and localization of ADAM15 and integrin β1, at the cellular level in collagen systems. These findings were validated by IHC of novel orthotopic models of bladder cancer, showing that both molecules localized at the muscle invasive front of the tumors as well as tumor emboli (LVI). Cells grown in collagen also presented increased FLP formation, invasion and proliferation rate when compared with those in plastic. Pharmacological inhibition of ADAM15 disintegrin activity or shADAM15 decreased cell attachment to collagen, invasion and FLPs in our 3D systems. Cells proliferation was also inhibited. Decreased cell viability was observed after treatment with the inhibitors on the 3D cultures. Early intracellular signaling events associated with these observations included inhibition of the FAK-Akt pathway. Conslusions: Our results show that ADAM15 has a key role in the invasive phenotype of bladder cancer cells via integrin β1 and FAK-Akt pathway. Thus, inhibition of ADAM15 activity represents a novel in vitro targeting strategy for bladder cancer

Citation Format: Guadalupe Lorenzatti Hiles, Angelica L. Cates, John R. Rubin, Matthew C. Winkler, Hannah L. Briggs, Mark L. Day. Validation of ADAM15 as a therapeutic target in invasive bladder cancer cells [abstract]. In: Proceedings of the AACR-NCI-EORTC International Conference: Molecular Targets and Cancer Therapeutics; 2017 Oct 26-30; Philadelphia, PA. Philadelphia (PA): AACR; Mol Cancer Ther 2018;17(1 Suppl):Abstract nr LB-B08.

ADAM15 Is Functionally Associated with the Metastatic Progression of Human Bladder Cancer

ADAM15 is a member of a family of catalytically active disintegrin membrane metalloproteinases that function as molecular signaling switches, shed membrane bound growth factors and/or cleave and inactivate cell adhesion molecules. Aberrant metalloproteinase function of ADAM15 may contribute to tumor progression through the release of growth factors or disruption of cell adhesion. In this study, we utilized human bladder cancer tissues and cell lines to evaluate the expression and function of ADAM15 in the progression of human bladder cancer. Examination of genome and transcriptome databases revealed that ADAM15 ranked in the top 5% of amplified genes and its mRNA was significantly overexpressed in invasive and metastatic bladder cancer compared to noninvasive disease. Immunostaining of a bladder tumor tissue array designed to evaluate disease progression revealed increased ADAM15 immunoreactivity associated with increasing cancer stage and exhibited significantly stronger staining in metastatic samples. About half of the invasive tumors and the majority of the metastatic cases exhibited high ADAM15 staining index, while all low grade and noninvasive cases exhibited negative or low staining. The knockdown of ADAM15 mRNA expression significantly inhibited bladder tumor cell migration and reduced the invasive capacity of bladder tumor cells through Matrigel^TM and monolayers of vascular endothelium. The knockdown of ADAM15 in a human xenograft model of bladder cancer inhibited tumor growth by 45% compared to controls. Structural modeling of the catalytic domain led to the design of a novel ADAM15-specific sulfonamide inhibitor that demonstrated bioactivity and significantly reduced the viability of bladder cancer cells in vitro and in human bladder cancer xenografts. Taken together, the results revealed an undescribed role of ADAM15 in the invasion of human bladder cancer and suggested that the ADAM15 catalytic domain may represent a viable therapeutic target in patients with advanced disease.