ABSTRACT
Elevated expression of the cell adhesion molecule N-cadherin (cadherin 2, type 1, N-cadherin (neuronal); CDH2) is associated with poor prognosis in newly-diagnosed multiple myeloma (MM) patients. In this study, we investigated whether targeting of N-cadherin represents a potential treatment for the ~50% of MM patients with elevated N-cadherin. Initially, we stably knocked-down N-cadherin in the mouse MM plasma cell (PC) line 5TGM1 to assess the functional role of N-cadherin in MM pathogenesis. When compared with 5TGM1-scramble-shRNA cells, 5TGM1-Cdh2-shRNA cells had significantly reduced adhesion to bone marrow endothelial cells. However, N-cadherin knock-down did not affect 5TGM1 cell proliferation or adhesion to bone marrow stromal cells. In the C57BL/KaLwRij murine MM model, mice intravenously inoculated with 5TGM1-Cdh2-shRNA cells showed significantly decreased tumour burden after 4 weeks, compared with animals bearing 5TGM1-scramble-shRNA cells. Finally, the N-cadherin antagonist ADH-1 had no effect on tumour burden in the established disease setting, whereas up-front ADH-1 treatment resulted in significantly reduced tumour burden after 4 weeks. Our findings demonstrate that N-cadherin may play a key role in the extravasation of circulating MM PCs promoting bone marrow homing. Moreover, these studies suggest that N-cadherin may represent a viable therapeutic target to prevent the dissemination of MM PCs and delay MM disease progression.
Subject(s)
Cadherins/antagonists & inhibitors , Cell Proliferation/drug effects , Multiple Myeloma/drug therapy , Neoplasm Proteins/antagonists & inhibitors , Neoplasms, Experimental/drug therapy , Oligopeptides/pharmacology , Peptides, Cyclic/pharmacology , Animals , Cadherins/genetics , Cadherins/metabolism , Cell Adhesion/drug effects , Cell Adhesion/genetics , Cell Line, Tumor , Cell Proliferation/genetics , Gene Knockdown Techniques , Humans , Mice , Multiple Myeloma/genetics , Multiple Myeloma/metabolism , Multiple Myeloma/pathology , Neoplasm Proteins/genetics , Neoplasm Proteins/metabolism , Neoplasms, Experimental/genetics , Neoplasms, Experimental/metabolismABSTRACT
BACKGROUND: Increased expression of the tetraspanin TSPAN7 has been observed in a number of cancers; however, it is unclear how TSPAN7 plays a role in cancer progression. METHODS: We investigated the expression of TSPAN7 in the haematological malignancy multiple myleoma (MM) and assessed the consequences of TSPAN7 expression in the adhesion, migration and growth of MM plasma cells (PC) in vitro and in bone marrow (BM) homing and tumour growth in vivo. Finally, we characterised the association of TSPAN7 with cell surface partner molecules in vitro. RESULTS: TSPAN7 was found to be highly expressed at the RNA and protein level in CD138(+) MM PC from approximately 50% of MM patients. TSPAN7 overexpression in the murine myeloma cell line 5TGM1 significantly reduced tumour burden in 5TGM1/KaLwRij mice 4 weeks after intravenous adminstration of 5TGM1 cells. While TSPAN7 overexpression did not affect cell proliferation in vitro, TSPAN7 increased 5TGM1 cell adhesion to BM stromal cells and transendothelial migration. In addition, TSPAN7 was found to associate with the molecular chaperone calnexin on the cell surface. CONCLUSION: These results suggest that elevated TSPAN7 may be associated with better outcomes for up to 50% of MM patients.
Subject(s)
Multiple Myeloma/metabolism , Nerve Tissue Proteins/genetics , Tetraspanins/genetics , Animals , Calnexin/genetics , Calnexin/metabolism , Cell Adhesion , Cell Line, Tumor , Cell Movement , Cell Proliferation , Coculture Techniques , Gene Expression , Humans , Mice, Inbred C57BL , Multiple Myeloma/mortality , Multiple Myeloma/pathology , Neoplasm Transplantation , Nerve Tissue Proteins/metabolism , Proportional Hazards Models , Tetraspanins/metabolism , Up-RegulationABSTRACT
N-cadherin (cadherin 2, type 1, N-cadherin (neuronal); CDN2) is a homotypic adhesion molecule that is upregulated in breast, prostate and bladder cancer. Here we investigated the prognostic significance of upregulated N-cadherin expression in multiple myeloma (MM). Our results indicate that N-cadherin protein and gene expression is abnormally increased in trephine biopsies and CD38(++) /CD138(+) plasma cells from MM patients, when compared with those of normal donors. In addition, levels of circulating N-cadherin were elevated in a subset of patients with MM (n = 81; mean: 14·50 ng/ml, range: 0-146·78 ng/ml), relative to age-matched controls (n = 27; mean: 2·66 ng/ml, range: 0-5·96 ng/ml), although this did not reach statistical significance. Notably, patients with abnormally high levels of N-cadherin (>6 ng/ml) had decreased progression-free survival (P = 0·036; hazard ratio: 1·94) and overall survival (P = 0·002; hazard ratio: 3·15), when compared with patients with normal N-cadherin levels (≤6 ng/ml). Furthermore, multivariate analyses revealed that the combination of N-cadherin levels and International Staging System (ISS) was a more powerful prognostic indicator than using ISS alone. Collectively, our studies demonstrate that circulating N-cadherin levels are a viable prognostic marker for high-risk MM patients.
