Metastasis Suppressor-1, MTSS1, Acts as a Putative Tumour Suppressor in Human Bladder Cancer

Background: Metastasis suppressor 1 (MTSS1) is proposed to function as a cytoskeletal-associated protein, which may play a role in the aggressiveness of cancer cells. Recent studies have demonstrated a clinical significance of MTSS1 in certain types of cancer, but its role in bladder cancer remains unknown. We investigated the expression of MTSS1 in normal and malignant human bladder tissues and its molecular interaction within bladder cancer cells. Materials and Methods: The expression of MTSS1 in human bladder tissues and bladder cancer cell lines was assessed at both the mRNA and protein levels using reverse transcription-PCR (RT-PCR) and immunohistochemistry, respectively. Full-length MTSS1 cDNA was amplified from normal mammary tissues. The effect of MTSS1 overexpression on cellular functions was examined in bladder cancer cells using a variety of in vitro assays. Results: Transitional cells of bladder tissues stained positively for MTSS1. However, cancer cells from tumour tissues did not stain for MTSS1. Similarly, in bladder cancer cell lines, MTSS1 was almost absent from T24 and RT112 cells, and the EJ138 cell line expressed a very low level of MTSS1. Overexpression of MTSS1 reduced the growth and adhesion of bladder cell lines in vitro. However, overexpression of MTSS1 had no bearing on the invasion and migration of bladder cell lines in vitro. Conclusion: MTSS1 is expressed at low levels or is absent from human bladder cancer cells. MTSS1 levels are inversely correlated with the growth and adhesion of bladder cancer cells in vitro. MTSS1 appears to be a potential tumour suppressor in human bladder cancer.