Thrombospondin-1 (TSP-1) Stimulates Expression of Integrin 6 in Human Breast Carcinoma Cells: A Downstream Modulator of TSP-1-Induced Cellular Adhesion
Figure 2
TSP-1 induces integrin 6 mRNA expression in human breast cancer cells. Two breast cancer cell lines (a) stably transfected TSP- 1 MDA-MB-435 cell lines with variable TSP-1 expression and (b) MDA-MB-231 cells treated with either buffer or TSP-1 (60 g/mL) were analyzed by northern blot analysis for integrin 6 expression. TSP-1 dose dependent response of integrin was then assessed in the MDA-MB-231 (c). Blots were normalized to a 2.4 -actin probe. A pancreatic carcinoma cell line, BxPC3, was used as a positive control. (a) TSP-1 stably transfected TSP-1 cells. 1: BxPC3 cell line, 2: TH5 cells (vector control), 3: TH29 cells (intermediate TSP-1 producer), and 4: TH26 cells (high TSP-1 producer). (b) MDA-MB-231 cells. 1: BxPC3 cell line, 2: buffer treatment, 3: TSP-1 (1 hour), 4: TSP-1 (6 hours), 5: TSP-1 (12 hours), and 6: TSP-1 (24 hours). Experiments were repeated three times and the results of a representative experiment are shown in the figure. (c) MDA-MB-231 cells. 1: Buffer treatment, 2: TSP-1 (20 g/mL), 3: TSP-1 (40 g/mL), and 4: TSP-1 (60 g/mL).
