Figure 5From: CD44 enhances invasion of basal-like breast cancer cells by upregulating serine protease and collagen-degrading enzymatic expression and activityHighly invasive breast cancer cells exhibit increased expression of collagen-degrading enzymes. (A) Bar graph illustrating the comparable invasion of parental MDA-MB-231 and MDA-MB-231Hi cells through a collagen I matrix. (B) Bar graph illustrating the retardation of MDA-MB-231Hi cell invasion through collagen I after transfection of the cells with a CD44 RNAi SMARTPool. (C) Bar graph presenting the respective collagenolytic activity of MDA-MB-231 parental and MDA-MB-231Hi cells, determined by using the Enzchek Collagenase assay. Bar graphs showing the results of quantitative real-time PCR analysis to determine mRNA transcript expression for (D) cathepsin K and (E) MT1-MMP in parental MDA-MB-231 and MDA-MB-231Hi cells. MDA-MB-231Hi cells demonstrated a 3.98- and 1.98-fold increase in cathepsin K and MT1-MMP, respectively, compared with their parental counterparts. (F) Immunoblot demonstrating elevated CD44, MT1-MMP, and cathepsin K protein expression in MDA-MB-231Hi cells relative to MDA-MB-231 parental cells. Membranes were reprobed with β-tubulin as a loading control. (G) Enzyme-linked immunosorbent assay (ELISA) showing elevated cathepsin K secretion in the MDA-MB-231Hi cells (6,170 ± 1,148 pmol/L/106 cells) relative to MDA-MB-231 parental cells (2,164 ± 553.3 pmol/L/106 cells; P < 0.01; n = 6). Statistically significant differences were determined by using a Student two-tailed t test (*P < 0.05; **P < 0.01; ***P < 0.001)Back to article page