Effects of the Antiandrogen Flutamide on the Expression of Protein Kinase C Isoenzymes in LNCaP and PC3 Human Prostate Cancer Cells

Abstract

Flutamide is a nonsteroidal antiandrogen that is frequently used for total androgen blockage in the treatment of advanced prostate cancer. We investigated the effect of this antiandrogen on the expression of protein kinase C (PKC) isoenzymes (a, b1, e, f) that are involved in cell growth, apoptosis and neoplastic transformation. Androgen-dependent (LNCaP) and independent (PC3) human prostate cancer cells were cultured in a medium that contained fetal bovine serum (FBS) or charcoal-stripped serum (CSS) and treated with 10 lM flutamide. The expression of PKC isoenzymes and the androgen receptor (AR) were analyzed by Western blot and RT-PCR, respectively. Serum steroids differentially regulate the expression of PKC isoenzymes in LNCaP and PC3 cells. Flutamide up-regulated the expression of a, b1 and f, but not e, PKC isoenzymes in CSS-LNCaP cells. These results were not homogeneously reproduced in the presence of androgens. We observed an opposite effect of flutamide, compared to CSS, on PKCb1 isoform expression in CSS-LNCaP suggesting that this antiandrogen exerts an agonistic effect. In PC3 cells flutamide potentiated the expression of the four PKC isoenzymes in almost all conditions tested (FBS-and CSScultured cells). Such effect of flutamide in PC3 cells is independent of AR since no expression of AR was detected. These results provide new evidence on antagonistic/agonistic responses of prostate cancer cells to antiandrogen drugs that are widely used in therapy and show that flutamide can elicit responses in prostate cancer cells that do not express AR.

KLF9, a transcription factor induced in flutamide-caused cell apoptosis, inhibits AKT activation and suppresses tumor growth of prostate cancer cells

“…Of note, the flutamide-induced KLF9 expression can be efficiently attenuated by DHT, indicating that the activation of KLF9 expression by flutamide was due to its capability in blocking the action of androgen in cells. Interestingly, it has been reported that flutamide can behave as an AR agonist in certain circumstances [3,23]. The bi-directional effects of flutamide on cell survival may be related to the different status of AR in cells, the dose of the drug and the cultured medium used in the experiments [23,24].…”

“…The growth of PCa is initially androgen-dependent, and anti-androgens (flutamide, nilutamide, bicalutamide, etc. ), as one type of the androgen deprivation therapy, are capable of inducing apoptosis of tumor cells and thus constitute the basis of endocrine therapy for PCa [2][3][4][5]. However, most PCa cells eventually become androgen-independent, which results in the failure of androgen deprivation therapy.…”

Dentatin Induces Apoptosis in Prostate Cancer Cells via Bcl-2, Bcl-xL, Survivin Downregulation, Caspase-9, -3/7 Activation, and NF-κB Inhibition

“…Androgen ablation therapy using luteinizing hormone-releasing hormone agonists (LH-RH) has become a primary treatment for metastatic prostate cancer [22]. LH-RH antagonist Cetrorelix inhibits the growth of PC-3 through downregulation of EGF receptors whereas antiandrogen Flutamide affects the expression of protein kinase C (PKC) which is important for prostate cancer cell growth [23, 24]. Anti-androgens are frequently used in conjunction with androgen ablation therapy as a combined androgen blockade to improve therapeutic outcome [25].…”

Up-regulation of circadian clock gene Period 2 in the prostate mesenchymal cells during flutamide-induced apoptosis

“…However, if our present data resulted from the agonistic action of FL in PMCs, both T and DHT should be expected to up-regulate circadian Per2 gene oscillations. Recent studies also reported the AR-independent action of FL [40,41]. FL activates the expression of protein kinase C isoenzymes in CSS-LNCaP cells and can elicit responses in prostate cancer cells that do not express AR [40].…”

“…Recent studies also reported the AR-independent action of FL [40,41]. FL activates the expression of protein kinase C isoenzymes in CSS-LNCaP cells and can elicit responses in prostate cancer cells that do not express AR [40]. In the rat prostate, apoptosis is suppressed by binding of decoy receptor DcR2 to TNF--related apoptosis-inducing ligand and is induced through the decoy receptor inhibited by FL [41].…”