Effects of Growth Factors and FFAR Agonists on CCN1 Expression in Breast and Prostate Cancer Cells

Abstract

CCN1/Cyr61 is a secreted extracellular matrix‐associated “matricellular” protein capable of regulating a broad range of cellular activities. Several studies have established that CCN1/Cyr61 is rapidly induced at the transcriptional level when cancer cells are incubated with growth factors that facilitate adhesion signaling, thereby enhancing cancer cell migration and survival. However, the role of CCN1 induction in the proliferative responses to growth factors has not been fully delineated. In this study, we examined the changes in expression levels of CCN1 in response to lysophosphatidic acid (LPA) and epidermal growth factor (EGF) in human prostate and breast cancer cell lines. We also studied the role of free fatty acid receptors (FFARs) in this context. FFAR agonists have been previously reported to show inhibitory effects on growth factor‐mediated proliferation and migration in human prostate and breast cancer cells. PC‐3 and MDA‐MB‐231 cells were serum‐starved for 24 hours and treated with 10uM LPA, 10nM EGF, and +/‐ 1uM TUG‐891. Following the incubation, whole‐cell lysates were collected, and subsequent immunoblotting was performed. LPA and EGF induced CCN1 protein by 4 hours. TUG‐891, an FFA4 agonist, inhibited CCN1 induction by LPA. In parallel, the cells were fixed with 4% paraformaldehyde and CCN1 was visualized using confocal immunofluorescence microscopy. The localization of CCN1 following its induction is consistent with its secretion and subsequent binding to ECM components. These results suggest that CCN1 plays roles in the sequence of downstream responses to growth factors in breast and prostate cancer cells.Support or Funding InformationSupported by the ASPET David Lehr Award and by the WSU College of Pharmacy and Pharmaceutical Sciences.