Indeed, inhibition of CRF2 receptors had no effect at least in the induction of cell invasion by CRF. These observa tions warrant further analysis of the CRF receptor system in selleck chemical primary breast cancer tissues that will support the sig nificance of these receptors in Inhibitors,Modulators,Libraries breast cancer. Earlier studies had shown that CRF suppressed breast can cer cell proliferation while it promoted proliferation in melanoma cells. Our studies confirmed the suppres sive effect of CRF on MCF7 proliferation. We further investigated the role of CRF on MCF7 cell apoptosis and found that CRF inhibited apoptosis. The effect of CRF on apoptosis varies depending on the cell type and the time detected. Thus, in PC12 rat pheochromocytoma cells CRF promoted apoptosis while in neuroblastoma and in melanoma cells it inhibited apoptosis.

An ear lier study in MCF7 cells showed no effect of CRF on apop tosis using a less sensitive method, this of visualizing fragmented DNA. Differences between cell types may Inhibitors,Modulators,Libraries be attributed to different factors that the cells may pro duce. i. e in Y79 neuroblastoma cells CRF Inhibitors,Modulators,Libraries inhibited cas pase 3 activity, while PC12 cells undergo apoptosis in response to CRF due to production of FasL, which is not expressed in MCF7 cells. The fact that CRF affected apoptosis and at the same time it inhibited cell proliferation may indicate changes in the cellular physiology that could contribute to a metastatic phenotype. Reduced cell proliferation, at least temporary, is required for cells to reorganize their cytoskeleton and promote motility. Indeed, CRF induced motility in MCF7 cells as demonstrated by a wound healing assay.

Cell motility is facilitated Inhibitors,Modulators,Libraries by cytoskeletal rearrangements that are Inhibitors,Modulators,Libraries characterized by actin polymerization. Our results indicated that CRF promoted polymerization of actin as determined by measuring the ratio of the monomeric ver sus the polymeric actin, as well as visualizing polymerized actin by immunofluorescence using confocal laser scan ning microscopy. Increased actin polymerization is asso ciated with dynamic changes in cytoskeletal structures that allow cells to migrate and metastasize. Focal Adhesion Kinase is a cytoskeleton associated kinase that is activated by phosphorylation and mediates signals to pro mote cell adhesion and migration. FAK also seems to play a role in tumor development since it has been shown that primary human cancer cells or cell lines overexpress the protein as well as its phosphorylated form.

In particular, FAK was found to overexpressed and to be highly activated in tumorigenic DU145 and selleck chemicals llc PC 3 cells as well as in prostate cancer tissues from patients with metas tasis whereas in LNCaP cells that have a lower tumorigenic ability FAK was observed to be much lower. We found that CRF promoted phosphorylation of FAK providing a potential mechanism for the actin reorganization and increased migration observed in response to CRF.