Figure 9.

SPARC antagonizes IL-6-induced chemotaxis and invasion of ovarian cancer cells. The chemotactic activity of SKOV3 (A) and OVCAR3 (B) cells toward IL-6 was tested as described previously. The indicated concentrations of IL-6 were used to attract ovarian cancer cells either alone or after pretreatment of cells with SPARC (10 µg/ml) for 2 hours. As control, the IL-6-neutralizing antibody (50 µg/ml) was mixed with SFM containing IL-6 (50 ng/ml) for 30 min before use in chemotaxis assay. *P < .05, from PBS-treated (control) cells. **P < .05, from matched control or IL-6-stimulated cells. FN invasion by SKOV3 (C) and OVCAR3 (D) cells was studied under the same conditions as described for the chemotaxis assay, with the exception that IL-6 was added to the cells in the upper chamber of the transwell inserts and cells were allowed to migrate toward a complete growth medium. Pretreatment of either SKOV3 or OVCAR3 cells with the IL-6-neutralizing antibody (50 µg/ml) for 30 minutes was used as control. *P < .05, from control PBS-treated cells. **P < .05, from matched control or IL-6-stimulated cells. Results are expressed as the mean ± SEM of the number of cells per field that migrated to and/or invaded the lower surface of the inserts. Experiments were performed in triplicate per experimental condition and were repeated thrice with similar results.