Human colon carcinoma (HCT-8) cells show metastatic phenotype when cultured on appropriately soft substrates. Here, we studied the surface non-specific adhesion in HCT-8 cells throughout the in vitro metastasis process. A novel bio-MEMS force sensor was used to measure the cell-probe nonspecific adhesion. The adhesion characteristics are analyzed using classical Johnson-Kendall- Roberts (JKR) theory. Our results indicate that the post-metastatic HCT-8 cells (dissociated R cells) display remarkably diminished surface adhesion and are potentially more invasive than original pre-metastatic HCT-8 cells (E cells). To the best of our knowledge, this is the first quantitative data on cancer cells adhesion change as in vitro metastasis proceeds.