Growth of human prostate cancer cells is significantly suppressed in vitro with sodium butyrate through apoptosis

Histone deacetylase inhibitors (HDACis) have shown significant antiproliferative and apoptotic properties in various types of cancer cells, including prostate cancer cells, and are therefore being evaluated as a treatment modality. However, the mechanism by which sodium butyrate (SB) induces apoptosis is not completely understood. We focused on SB which exists in the intestine and is therefore expected to have less adverse effects. In this study, three prostate cancer cell lines (LNCaP, DU145 and PC-3) were treated in vitro with different concentrations of SB. Cell proliferation was studied by the XTT assay; cell cycle analysis and induction of apoptosis were studied by laser scanning cytometry. Western blot analysis was used to study p21, p27, CDK2, CDK4, CDK6, caspase-3, caspase-7, Fas, FADD, TRADD, Bcl-2 and Bax protein expression. SB inhibited cell growth and induced apoptosis in a concentration-dependent manner in human prostate cancer cells (LNCaP, DU145 and PC-3). Western blot analysis showed dose-dependent increases of p21 levels in DU145 and PC-3 cells, and dose-dependent decreases of CDK2, CDK4, CDK6 and procaspase-3 protein levels in all three prostate cancer cell lines. Bcl-xL was significantly down-regulated in DU145 cells, and Bcl-2 was significantly down-regulated in PC-3 and LNCaP cells. No significant changes were observed in procaspase-7, TRADD and Bax expression, although slight decreases in Fas and FADD expression were seen in all three prostate cancer cell lines. Analysis of cell morphology using laser scanning microscopy detected condensed and fragmented nuclei. In conclusion, SB induces G1 and G2 arrest by increasing p21 expression resulting in CDK2, CDK4 and CDK6 down-regulation. SB potently induced apoptosis, which was accompanied by DNA fragmentation, down-regulated Bcl-2 in LNCaP and PC-3 cells, Bcl-xL in DU145 cells, and down-regulated procaspase-3, but not procaspase-7, in these human prostate cancer cell lines. These results suggest that SB may serve as a new modality for the treatment of hormone refractory prostate cancer.     

A concentrated aglycone isoflavone preparation (GCP) that demonstrates potent anti-prostate cancer activity in vitro and in vivo.

PURPOSE: Isoflavones have anticancer activities, but naturally occurring isoflavones are predominantly glycosylated and poorly absorbed. Genistein combined polysaccharide (GCP; Amino Up Chemical Co., Sapporo, Japan), is a fermentation product of soy extract and basidiomycetes mycillae that is enriched in biologically active aglycone isoflavones. This study analyzes GCP in vitro and in vivo for potential utility as a prostate cancer chemopreventative agent. EXPERIMENTAL DESIGN: Androgen-sensitive LNCaP and androgen-independent PC-3 cells were grown with various concentrations of GCP. In vitro cell growth was analyzed by the WST-1 assay, and apoptosis was assessed by fluorescence-activated cell sorting and detection of poly(ADP-ribose) polymerase cleavage using Western blot techniques. Effects of GCP on expression of cell cycle-regulatory proteins p53 (LNCaP only), p21, and p27 and the protein kinase Akt were considered using Western blot techniques. An in vivo LNCaP xenograft model was used to study the effects of a 2% GCP-supplemented diet on tumor growth in comparison with a control diet. RESULTS: GCP significantly suppressed LNCaP and PC-3 cell growth over 72 h (89% and 78% in LNCaP and PC-3, respectively, at 10 microg/ml; P < 0.0001). This reduction was associated with apoptosis in LNCaP cells, but not in PC-3 cells. GCP induced p27 and p53 (LNCaP only) protein expression within 6 h and suppressed phosphorylated Akt in both cell lines. The 2% GCP-supplemented diet significantly slowed LNCaP tumor growth, increasing apoptosis (P < 0.001), and decreasing proliferation (P < 0.001) over 4 weeks. CONCLUSIONS: GCP has potent growth-inhibitory effects against prostate cancer cell lines in vitro and in vivo. These data suggest GCP has potential as an effective chemopreventive agent against prostate cancer cell growth.     

Differential expression and regulation of p53 in human prostatic cells

Although genetic analysis has convincingly shown the association possibly existing between alterations in p53 tumor suppressor gene and a broad spectrum of human tumors including prostate cancer, surprisingly little is known about ways in which p53 at the protein level is controlled. To determine factors that may play a role in its regulation and expression, changes in p53 protein was investigated by using the androgen-insensitive JCA-1, DU-145, PC-3 and the androgen-responsive LNCaP cells. With the exception of PC-3 cells in which p53 is missing, multiple distinct forms of p53 were found in the other 3 prostate cell lines. A single p53 band was detected in the JCA-1 cell extracts, whereas two and three p53 immunoreactive bands were correspondingly observed in the DU-145 and LNCaP cells. The relative abundance and distribution of the different forms of p53 in the latter two cell types varied with proliferation of cells in culture. In the presence of charcoal-stripped fetal bovine serum (cFBS), LNCaP took on the morphology of neuroendocrine cells, a phenotypic change which was accompanied by a greater than 80% reduction in p53 expression, concurrent with elimination of the two slow migrating forms of p53. Induction of apoptosis in JCA-1 cells by treatment with the retinoid 4-HPR caused the virtual disappearance of p53, which coincided with specific processing of p53 into lower molecular weight 28 kD fragments. We propose that rapid and dynamic posttranslational changes in p53 may actively participate in determining mutually exclusive functional cellular events such as proliferation, differentiation, and apoptosis.     

Guggulsterone-induced apoptosis in human prostate cancer cells is caused by reactive oxygen intermediate dependent activation of c-Jun NH2-terminal kinase

Guggulsterone, a constituent of Indian Ayurvedic medicinal plant Commiphora mukul, causes apoptosis in cancer cells but the sequence of events leading to cell death is poorly understood. We now show that guggulsterone-induced cell death in human prostate cancer cells is caused by reactive oxygen intermediate (ROI)-dependent activation of c-Jun NH(2)-terminal kinase (JNK). Exposure of PC-3 and LNCaP cells to apoptosis inducing concentrations of guggulsterone resulted in activation of JNK and p38 mitogen-activated protein kinase (p38 MAPK) in both cell lines and activation of extracellular signal-regulated kinase 1/2 (ERK1/2) in LNCaP cells. The guggulsterone-induced apoptosis in PC-3/LNCaP cells was partially but statistically significantly attenuated by pharmacologic inhibition (SP600125) as well as genetic suppression of JNK activation. On the other hand, pharmacologic inhibition of p38 MAPK activation in PC-3 or LNCaP cells (SB202190) and ERK1/2 activation in LNCaP cells (PD98059) did not protect against guggulsterone-induced cell death. The guggulsterone treatment caused generation of ROI in prostate cancer cells but not in a normal prostate epithelial cell line (PrEC), which was also resistant to guggulsterone-mediated JNK activation. The guggulsterone-induced JNK activation as well as cell death in prostate cancer cells was significantly attenuated by overexpression of catalase and superoxide dismutase. In addition, guggulsterone treatment resulted in a decrease in protein level and promoter activity of androgen receptor in LNCaP cells. In conclusion, the present study reveals that the guggulsterone-induced cell death in human prostate cancer cells is regulated by ROI-dependent activation of JNK and guggulsterone inhibits promoter activity of androgen receptor.     

Cyclooxygenase-2 is up-regulated in proliferative inflammatory atrophy of the prostate, but not in prostate carcinoma.

Cyclooxygenase-2 (COX-2) is the inducible isoform of the rate-limiting enzymes that convert arachidonic acid to proinflammatory prostaglandins as well as a primary target for nonsteroidal anti-inflammatory drugs. Accumulating evidence suggests that up-regulation of COX-2 is associated with carcinogenesis in multiple organ systems including the large bowel, lung, breast, and prostate. In this report, we examine the expression of COX-2 protein and mRNA in prostate tissue containing various lesions and in prostate cancer cell lines. In the cell lines, LNCaP, DU145, PC-3, and TSU, COX-2 protein expression was undetectable under basal conditions but could be induced transiently by phorbol ester treatment in PC-3 and TSU cells, but not in DU145 and LNCaP cells. Immunohistochemical analysis of 144 human prostate cancer cases suggested that, in contrast to several previous reports, there was no consistent overexpression of COX-2 in established prostate cancer or high-grade prostatic intraepithelial neoplasia, as compared with adjacent normal prostate tissue. Positive staining was seen only in scattered cells (<1%) in both tumor and normal tissue regions but was much more consistently observed in areas of proliferative inflammatory atrophy, lesions that have been implicated in prostatic carcinogenesis. Staining was also seen at times in macrophages. Western blotting and quantitative RT-PCR analyses confirmed these patterns of expression. These results suggest that if nonsteroidal anti-inflammatory drugs are indeed chemopreventive and/or chemotherapeutic for prostate cancer, their effects are likely to be mediated by modulating COX-2 activity in non-PCa cells (either inflammatory cells or atrophic epithelial cells) or by affecting a COX-2-independent pathway.     

CBX7 controls the growth of normal and tumor-derived prostate cells by repressing the Ink4a/Arf locus

Control of cell proliferation by Polycomb group proteins (PcG) is an important facet of cellular homeostasis and its disruption can promote tumorigenesis. We recently described CBX7 as a novel PcG protein controlling the growth of normal cells. In an attempt to identify a putative role of CBX7 in tumorigenesis, we analysed CBX7 expression in a panel of cancer cell lines and primary tissues. CBX7 was highly expressed in three different prostate cancer cell lines and present at elevated levels in normal prostate. Ablation of CBX7 expression using short hairpin RNAs (shRNA) resulted in upregulation of p16Ink4a and p14Arf in both LNCaP and PC-3 prostate cell lines. CBX7 knockdown caused an impairment of cell growth that was dependent on the status of the p14Arf/p53 and p16Ink4a/Rb pathways in both normal and cancer prostate cells. CBX7 overexpression in LNCaP cells resulted in a slight growth advantage in both androgen-dependent and -independent conditions. Moreover, CBX7 expression cooperated with c-Myc in rendering LNCaP cells insensitive to growth arrest by androgen receptor inhibition. Together, these data suggest that CBX7 represses p16Ink4a and p14Arf expression in normal and tumor-derived prostate cells, affecting their growth depending on the status of the p16Ink4a/Rb and the p14Arf/p53 pathways.     

Dual effects of glutathione-S-transferase pi on As2O3 action in prostate cancer cells: enhancement of growth inhibition and inhibition of apoptosis

To determine the effects of glutathione-S-transferase pi (GSTpi) on the actions of As2O3, As2O3-induced growth inhibition and apoptosis was studied in three prostate cancer cell lines: DU-145, PC-3 and LNCaP cells. As2O3 inhibited cell proliferation of DU-145 and PC-3 cells (both cells express GSTpi), but not of LNCaP cells (which lack GSTpi expression) at concentrations below 1 microM. LNCaP cells stably transfected and expressed GSTpi (LNCaP/GSTpi) became sensitive to As2O3 growth inhibition. As2O3 arrested cell growth of DU-145, PC-3 and LNCaP/GSTpi cells in the G2/M phase of the cell cycle at low concentrations (<2 microM), but did not induce apoptosis. At higher concentrations (10-20 microM), As2O3 induced apoptosis in LNCaP cells, but not in DU-145 or PC-3 cells. The apoptosis induction due to As2O3 treatment of LNCaP cell correlated with the activation of JNK and p38 and induction of p53 protein. LNCaP/GSTpi cells became insensitive to As2O3-induced apoptosis with reduced JNK activition. These data indicate that GSTpi increases growth inhibition due to As2O3 treatment and prevents As2O3-induced apoptosis in prostate cancer cells. Therefore, it appears that As2O3 inhibits cell growth and induces apoptosis through different mechanisms.     

The expression of inducible cAMP early repressor (ICER) is altered in prostate cancer cells and reverses the transformed phenotype of the LNCaP prostate tumor cell line

Inducible cAMP early repressor (ICER) has been shown to be an important mediator of cAMP antiproliferative activity. In this report, it was found that cAMP retards LNCaP cell growth; in contrast, cAMP inhibits the growth of PC-3 and DU-145 cells. ICER protein levels were markedly reduced in prostate cancer epithelial cells and undetectable and uninducible by cAMP in LNCaP and DU 145 cells. Forced expression of ICER in LNCaP cells caused inhibition of cell growth and thymidine incorporation and halted cells at the G(1) phase of the cell cycle. These ICER-bearing LNCaP cells were rendered unable to grow in soft agar and unable to form tumors in nude mice. These results suggest that deregulation of ICER expression may be related to carcinogenesis of the prostate gland.     

PC-1基因表达对前列腺癌细胞迁移能力的影响

背景与目的:PC-1基因在雄激素非依赖和高转移能力的前列腺癌C4-2细胞中高表达,在雄激素依赖及不转移的前列腺癌LNCaP细胞中低表达。本实验旨在研究PC-1对前列腺癌细胞迁移能力的影响。方法:构建PC-1稳定高表达的LNCaP细胞株和反义核酸调低内源性PC-1表达的C4-2细胞株。利用体外迁移系统检测PC-1表达对LNCaP和C4-2细胞迁移运动能力的影响。结果:体外迁移实验表明稳定转染提高PC-1的表达水平并未使LNCaP迁移细胞数增多(P>0.05),而反义核酸降低PC-1表达则使C4-2迁移细胞数降低(P<0.05)。PC-1蛋白水平升高不能提高LNCaP细胞迁移能力,但降低内源性PC-1表达则使C4-2细胞迁移能力明显降低。结论:PC-1可能在前列腺癌细胞侵袭过程中起一定作用。     

2-Chloroethyl-3-sarcosinamide-1-nitrosourea (SarCNU) inhibits prostate carcinoma cell growth via p53-dependent and p53-independent pathways

BACKGROUND: Prostate carcinoma is the most commonly occurring malignancy in men. Although 2-chloroethyl-3-sarcosinamide-1-nitrosourea (SarCNU), an analog of the chloroethylnitrosoureas, has been used in the treatment of advanced solid tumors, the molecular mechanisms underlying the antineoplastic activity of this agent are not well understood. In the current study, the authors sought to investigate the effects of SarCNU on prostate carcinoma cell growth in vivo and in vitro. METHODS: Male SCID mice underwent subcutaneous implantation (on both flanks) of human CWR-22 and CWR-22R prostate carcinoma xenografts. Mice were treated with either vehicle or 60 or 80 mg SarCNU per kg body weight for 5 days, with tumor growth being assessed every 3 days. Animals were sacrificed 21 days after the final injection, and tumors subsequently were collected, weighed, and processed for analysis. Immunohistochemical analyses were performed to obtain data on the localization of p53 and p21Cip1/Waf1. Cell counting, terminal deoxynucleotidyltransferase-mediated deoxyuridine triphosphate nick end-labeling (TUNEL) assays, cell cycle analyses, Western blotting, and in vitro kinase assays were performed to determine the effects of SarCNU on growth, apoptosis, cell cycle arrest, cell cycle-regulated protein levels, and Cdc-2 activity, respectively. RESULTS: SarCNU reduced tumor incidence and inhibited the growth of CWR-22 and CWR-22R xenografts. In addition, treatment with this agent led to increases in p21Cip1/Waf1 levels and p53 phosphorylation at Ser15. In vitro administration of SarCNU to cells with wild-type p53 (LNCaP and primary CWR-22 cells) and cells with mutant p53 (PC-3 cells) resulted in G2/M arrest and the reduction of cellular Cdc-2 activity. Up-regulation of p53 levels, p53 phosphorylation at Ser15, and p21Cip1/Waf1 levels in primary CWR-22 and LNCaP cells, as well as up-regulation of Cdc-2 phosphorylation at Tyr15 in PC-3 cells, was detected. CONCLUSIONS: SarCNU induced G2/M arrest in prostate carcinoma cells via p53-dependent up-regulation of p21Cip1/Waf1 and p53-independent phosphorylation of Cdc-2 at Tyr15. These findings suggest a potential role for SarCNU in the treatment of prostate malignancies.     

Gene expression of angiogenic factors correlates with metastatic potential of prostate cancer cells

We hypothesize that expression of proangiogenic genes correlates with the metastatic potential of prostate cancer cells. LNCaP, DU-145, and PC-3 are prostate cancer cell lines with low, moderate, and high metastatic potential, respectively, as we demonstrated by their capacity to invade an extracellular matrix, an established tumor invasion assay. The constitutive gene expression of the proangiogenic factors, vascular endothelial growth factor, intercellular adhesion molecule-1, interleukin-8, and transforming growth factor-beta2, was significantly greater in the more metastatic DU-145 and PC-3 cells as compared with LNCaP cells. Matrix metalloproteinase (MMP)-9 is thought to contribute to the invasive phenotype of tumor cells. PC-3 cells showed increased expression of MMP-9 and membrane type 4-MMP as compared with LNCaP and DU-145. Tissue inhibitors of metalloproteinase 1 and 4 gene expression were elevated in DU-145 and PC-3 cells, but paradoxically, LNCaP cells had undetectable levels of these genes. We transfected and overexpressed MMP-9 in poorly metastatic LNCaP cells and measured their invasive activity. Transient expression of human MMP-9 in LNCaP cells produced a 3-5-fold increase in MMP-9 activity with a comparable increase in invasiveness. Antisense ablation of the expression of MMP-9 in DU-145 and PC-3 cells produced concomitant inhibition of the gene expression of the proangiogenic factors, vascular endothelial growth factor, and intercellular adhesion molecule-1 (ICAM-1). Treatment of DU-145 and PC-3 cells with a selective chemical inhibitor of MMP-9 proteinase activity also inhibited their invasive activity. These results support our hypothesis that metastatic potential of prostate cancer cells correlates with expression of proangiogenic factors.     

Allyl isothiocyanate,a constituent of cruciferous vegetables,inhibits proliferation of human prostate cancer cells by causing G2/M arrest and inducing apoptosis

Dietary isothiocyanates (ITCs) are highly effective in affording protection against chemically induced cancers in laboratory animals. In the present study, we demonstrate that allyl isothiocyanate (AITC), a constituent of cruciferous vegetables, significantly inhibits proliferation of cultured PC-3 (androgen-independent) and LNCaP (androgen-dependent) human prostate cancer cells in a dose-dependent manner with an IC(50) of approximately 15-17 micro M. On the other hand, survival of a normal prostate epithelial cell line (PrEC) was minimally affected by AITC even at concentrations that were highly cytotoxic to the prostate cancer cells. Reduced proliferation of PC-3 as well as LNCaP cells in the presence of AITC correlated with accumulation of cells in G(2)/M phase and induction of apoptosis. In contrast, AITC treatment failed to induce apoptosis or cause G(2)/M phase arrest in PrEC cells. A 24 h treatment of PC-3 and LNCaP cells with 20 micro M AITC caused a significant decrease in the levels of proteins that regulate G(2)/M progression, including Cdk1 (32-50% reduction), Cdc25B (44-48% reduction) and Cdc25C (>90% reduction). A significant reduction in the expression of cyclin B1 protein (approximately 45%) was observed only in LNCaP cells. A 24 h exposure of PC-3 and LNCaP cells to an apoptosis-inducing concentration of AITC (20 micro M) resulted in a significant decrease (31-68%) in the levels of anti-apoptotic protein Bcl-2 in both cell lines, and approximately 58% reduction in Bcl-X(L) protein expression in LNCaP cells. In conclusion, it seems reasonable to hypothesize that AITC, and possibly other ITCs, may find use in the treatment of human prostate cancers.     

Deregulation of the Rho GTPase, Rac1, suppresses cyclin-dependent kinase inhibitor p21(CIP1) levels in androgen-independent human prostate cancer cells

Abnormally suppressed levels of cyclin-dependent kinase inhibitors (CKIs) are associated with aggressive androgen-independent prostate cancer and contribute to uncontrolled proliferation. The androgen-independent human prostate cancer cell lines, LNCaP-104R1, ALVA31 and PC-3, express low levels of the CKI, p21(CIP1), compared to the less-malignant, androgen-dependent LNCaP cells. We investigated the mechanism underlying this suppression by examining the role of Rho GTPases, signaling proteins that play important roles in cell cycle progression, at least in part through regulation of CKIs. Inhibition of Rac1 induced p21 expression in androgen-independent lines but had no effect on the higher p21 levels characteristic of LNCaP cells. This induction of p21 was functionally significant as evidenced by inhibition of cyclin-dependent kinase 2 activity and decreased cell proliferation. Conversely, overexpression of constitutively active Rac1 suppressed the higher p21 levels seen in LNCaP cells. Thus, Rac1 activity is both necessary and sufficient for suppression of p21 in prostate cancer cells. Furthermore, Rac1 activity was significantly higher in all three androgen-independent cell lines compared to LNCaP cells. Thus in three models of aggressive human prostate cancer, hyperactivity of Rac1 corresponds to suppressed levels of p21. These results are unique in describing a role for Rac1 in p21 regulation and may implicate the Rac1 signaling pathway as a potential therapeutic target for controlling prostate cancer cell growth following progression to androgen independence.     

miR-335-5p靶向调控Galectin-3调节前列腺癌细胞免疫逃逸的机制研究

目的:探讨miR-335-5p靶向调控半乳糖凝集素-3（Galectin-3）对前列腺癌细胞免疫逃逸的影响。方法:qRT-PCR检测正常前列腺上皮细胞WPMY-1及前列腺癌细胞LNCaP、PC-3、DU145中miR-335-5p的表达;将PC-3细胞分为:NC组、mimics NC组、miR-335-5p mimics组、miR-335-5p mimics+pcDNA组、miR-335-5p mimics+pcDNA-Galectin-3组,qRT-PCR检测各组细胞中miR-335-5p表达;western blot检测各组细胞中Galectin-3蛋白表达。将上述5组细胞分别与自然杀伤细胞NK-92MI共培养后,ELISA法检测共培养细胞上清液中肿瘤坏死因子α（TNF-α）、干扰素γ（IFN-γ）水平;CCK-8法检测NK-92MI细胞的免疫杀伤率;流式细胞术检测NK-92MI细胞凋亡率;双荧光素酶报告基因、RNA下拉、RNA结合蛋白免疫沉淀（RIP）实验验证miR-335-5p与Galectin-3的靶向关系。结果:与正常前列腺上皮细胞WPMY-1比较,前列腺癌细胞LNCaP、PC-3、DU145中miR-335-5p的表达水平显著降低（P＜0.05）,且PC-3细胞中miR-335-5p的表达水平最低,因此选用PC-3细胞为后续研究对象;与NC组比较,miR-335-5p mimics组PC-3细胞中miR-335-5p表达水平显著升高,Galectin-3蛋白表达显著降低（P＜0.05）;与NC共培养组比较,miR-335-5p mimics共培养组细胞上清液中TNF-α、IFN-γ水平及NK-92MI细胞免疫杀伤率显著升高,NK-92MI细胞凋亡率降低（P＜0.05）;与miR-335-5p mimics组比较,miR-335-5p mimics+pcDNA-Galectin-3组PC-3细胞中miR-335-5p表达水平差异无统计学意义（P＞0.05）,Galectin-3蛋白表达显著升高（P＜0.05）;与miR-335-5p mimics共培养组比较,miR-335-5p mimics+pcDNA-Galectin-3共培养组细胞上清液中TNF-α、IFN-γ水平及NK-92MI细胞免疫杀伤率显著降低,NK-92MI细胞凋亡率升高（P＜0.05）;miR-335-5p靶向负调控Galectin-3表达。结论:过表达miR-335-5p通过靶向下调Galectin-3表达来抑制PC-3细胞免疫逃逸。     

Antiproliferative effects of AVN944, a novel inosine 5-monophosphate dehydrogenase inhibitor, in prostate cancer cells

Inosine 5-monophosphate dehydrogenase II, a key enzyme in the de novo synthesis of purine nucleotides, is expressed in prostate tumors and prostate cancer cells. AVN944 is a new, specific, noncompetitive IMPDH inhibitor. In this study, we investigated the effects of IMPDH inhibitor AVN944 on LNCaP, CWR22Rv1, DU145 and PC-3 human prostate cancer cells. AVN944 inhibited proliferation of these 4 prostate cancer cell lines and was associated with cell cycle G1 arrest of LNCaP cells and S-phase block of androgen-independent CWR22Rv1, DU145 and PC-3 cells. AVN944 induced caspase-dependentand caspase-independent cell death in LNCaP, CWR22Rv1, and DU145 cells. AVN944 induced expression of p53-target proteins Bok, Bax and Noxa in androgen-responsive cell lines and suppressed expression of survivin in prostate cancer cells regardless of their androgen sensitivity. AVN944 also induced differentiation of androgen-independent prostate cancer cells as indicated by morphological changes and increased expression of genes coding for prostasomal proteins, keratins and other proteins, including tumor suppressor genes MIG-6 and NDRG1. AVN944-differentiated androgen-independent DU145 and PC-3 cells are sensitized to TRAIL-induced apoptosis as demonstrated by induction of caspases and PARP cleavage. In summary, AVN944 inhibited the growth of human prostate cancer cells by inducing cell cycle arrest, cell death as well as differentiation. AVN944 is a novel, promising therapeutic agent that might be combined with other agents for treatment of human prostate cancer.