Anticarcinogenic effect of FTY720 in human prostate carcinoma DU145 cells: Modulation of mitogenic signaling, FAK, cell‐cycle entry and apoptosis

Abstract

Despite the high frequency of prostate cancer, therapeutic options for advanced disease are limited to chemotherapy, radiation or hormonal therapy and eventually fail in all patients. Therefore, alternative approaches need to be developed. We previously reported that FTY720, a metabolite from Isaria sinclarii, is a unique antitumor agent for an androgen-independent prostate cancer cell line and requires caspase-3 activation in apoptosis. In our study, we have evaluated the effect of FTY720 on a family of mitogen-activated protein kinases (MAPKs), focal adhesion kinase (FAK), mitochondrial transmembrane potential, caspase-9 and caspase-8 and analyzed the expression of some cell-cycle regulator proteins in DU145 cells in order to understand the various antitumor effects of FTY720. Apoptosis was quantified by phosphatidylserine exposure. Activation of MAPKs, cleavage of caspase-9 and caspase-8, status of cyclin-dependent kinases (CDKs) and Cip1/p21, a cyclin-dependent kinase inhibitor, were evaluated by Western blot analysis, in addition to FAK and phospho-FAK immunoprecipitation and cell-cycle analysis by FACScan. We found that in DU145 cells, 40 M FTY720 caused activation of p38 MAPK and the upstream kinase MKK3/MKK6 but not SAPK/JNK. Mitochondrial transmembrane potential, FAK and ERK1/2 were reduced while caspase-9 and caspase-8 were cleaved. The p38-specific inhibitor had no effect on apoptosis induced by FTY720, whereas z-VAD.FMK, a broad-spectrum caspase inhibitor, did not inhibit the p38 MAPK activation. An amount of 20 M FTY720 resulted in G 1 arrest and a decrease of CDK2 as well as CDK4, whereas it induced Cip1/p21. FTY720 may exert anticarcinogenic effects against prostate cancer cells possibly involving modulation of mitogenic signaling, cell-cycle regulators, induction of G 1 arrest and apoptotic death in DU145 cells. © 2002 Wiley-Liss, Inc. Key words: FTY720; apoptosis; MAPKs; FAK; caspase-9; CDKsProstate cancer (PCA) is the most common nonskin malignancy and the second-leading cause of cancer deaths in United States males. 1 Unfortunately, after radical prostectomy, chemotherapy, radiation therapy or androgen ablation treatments, a portion of patients will suffer from recurrent or residual cancer. The awareness of the limitations of current therapies is increasing, and alternative approaches need to be developed. One practical and translational approach to control PCA is to develop a mechanismbased anticarcinogenic agent(s). Recently, we have shown that FTY720, a metabolite from Isaria sinclairi, is a unique and potential strong antitumor agent for cell line DU145 and provided the first evidence for involvement of caspase-3 in a dose-related apoptosis of an androgen-independent prostate cancer cell line. 2 But the cellular mechanisms of the action of FTY720 on cancer cells are not completely understood.Apoptosis, or programmed cell death, is a regulated physiologic process leading to cell death characterized by cell shrinkage, membrane blebbing and DNA fragmentation. Caspases, a family of cysteine pr...

Celecoxib induces anoikis in human colon carcinoma cells associated with the deregulation of focal adhesions and nuclear translocation of p130Cas

“…6a). The IC 50 for celecoxib, in CAS-FL transfectants, (55.66 6 5.47 lM) was significantly higher than the IC 50 in cells transfected with the empty vector (33.58 6 5.05 lM) (p < 0.05, U Mann Whitney test). In contrast, Myr-FAK transfectants had sensitivity to celecoxib similar to control cells (IC 50 of 35.85 6 3.10 lM).…”

“…Values of IC 50 were compared by the U-Mann Whitney test and statistically significant differences were considered at p < 0.05.…”

“…As shown in Figure 1a, celecoxib inhibited the viability (reduction of metabolically active cells, as measured by the XTT test) of all 4 cell lines, in a concentration-dependent manner, after 60 hr exposure. To evaluate the differences in the sensitivity of the cell lines to celecoxib, we determined and compared the IC 50 1.96 lM. Interestingly, celecoxib had a similar effect in all cell lines despite their levels of COX-2 expression were significantly different.…”

“…48 Moreover, there is evidence suggesting that some antitumor drugs can modulate signaling through focal adhesion proteins. 49,50 Thus, deregulation of FAK expression and induction of anoikis has been proposed as a mechanism of antitumor action for quinazoline derivatives in prostate cancer cells. 51,52 Nevertheless, none of these drugs are chemically related to celecoxib.…”

Effects of Phosphorylation of Immunomodulatory Agent FTY720 (Fingolimod) on Antiproliferative Activity against Breast and Colon Cancer Cells

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