Effects of a KiSS-1 peptide, a metastasis suppressor gene, on the invasive ability of renal cell carcinoma cells through a modulation of a matrix metalloproteinase 2 expression

Although effects of a metastasis suppressor gene, KiSS-1, have been postulated to be mediated by its receptor, hOT7T175, the mechanism of such effects remains unknown. This study was designed to evaluate the mechanism of how KiSS-1 works and to assess effects of a synthesized truncated KiSS-1 protein on the invasive ability of renal cell carcinoma (RCC) cells. Four RCC cell lines, Caki-1, KU19-20, RSP and RSM, were investigated to determine mRNA expressions of KiSS-1, its receptor, hOT7T175, matrix metalloproteinases (MMPs) and MMP inhibitors. While all cell lines demonstrated hOT7T175 mRNA expressions, only Caki-1 had KiSS-1 transcripts. A synthesized truncated KiSS-1 peptide, metastin (45–54), produced a marked suppression of the invasive ability in KU19-20 cells, which were deficient for KiSS-1 transcripts, but not in Caki-1 cells. Metastin (45–54) also increased the ability of KU19-20 cells to attach to collagen 4. Both MMP-2 mRNA levels and protein production were significantly decreased only in KU19-20 cells by metastin (45–54). In conclusion, metastin (45–54) may have potential therapeutic use by suppressing the motility and invasive ability of RCC cells which possess hOT7T175 with either a negative expression or very low expression level of KiSS-1 through, at least in part, the down-regulation of MMP-2.