Adaptive and non-adaptive gene expression responses in prostate cancer during androgen deprivation.

Androgen deprivation therapy is the cornerstone treatment of advanced prostate cancer. Eventually prostate cancer cells overcome androgen deprivation therapy, giving rise to castration resistant prostate cancer (CRPC) characterized by increased androgen receptor (AR) activity. Understanding the cellular mechanisms leading to CRPC is needed for development of novel treatments. We used long-term cell cultures to model CRPC; a testosterone-dependent cell line (VCaP-T) and cell line adapted to grow in low testosterone (VCaP-CT). These were used to uncover persistent and adaptive responses to testosterone level. RNA was sequenced to study AR-regulated genes. Expression level changed due to testosterone depletion in 418 genes in VCaP-T (AR-associated genes). To evaluate significance for CRPC growth, we compared which of them were adaptive i.e., restored expression level in VCaP-CT. Adaptive genes were enriched to steroid metabolism, immune response and lipid metabolism. The Cancer Genome Atlas Prostate Adenocarcinoma data were used to assess the association with cancer aggressiveness and progression-free survival. Expressions of 47 AR-associated or association gaining genes were statistically significant markers for progression-free survival. These included genes related to immune response, adhesion and transport. Taken together, we identified and clinically validated multiple genes being linked with progression of prostate cancer and propose several novel risk genes. Possible use as biomarkers or therapeutic targets should be studied further.

Additive inhibitory effects of simvastatin and enzalutamide on androgen-sensitive LNCaP and VCaP prostate cancer cells.

We evaluated the effects of simvastatin and antiandrogen enzalutamide on growth and androgen signaling in androgen-sensitive LNCaP and VCaP prostate cancer cells. Simvastatin alone abolished androgen-induced growth in both cell lines but decreased androgen receptor (AR) and prostate-specific antigen protein expression only in LNCaP, indicating that statin-induced growth inhibition is beyond AR transcriptional activity in VCaP. Combination of simvastatin and enzalutamide exerted additive growth inhibition in both cell lines accompanied with strong induction of autophagy in LNCaP. The data provide new insight into statins' effects on androgen signaling and their proposed role in enhancing androgen deprivation therapy in prostate cancer.

The effects of metformin and simvastatin on the growth of LNCaP and RWPE-1 prostate epithelial cell lines.

The anti-diabetic drug metformin and cholesterol-lowering statins inhibit prostate cancer cell growth in vitro and have been linked with lowered risk of prostate cancer in epidemiological studies. We evaluated the effects of these drugs on cancerous and non-cancerous prostate epithelial cell lines. Cancer (LNCaP) and normal (RWPE-1) prostate epithelial cell lines were treated with pharmacologic concentrations of metformin and simvastatin alone and in combinations. Relative changes in cell number were measured with crystal violet staining method. Drug effects on apoptosis and cell cycle were measured with flow cytometry. We also measured changes in the activation and expression of a set of reported target proteins of metformin and statins with Western blotting. Metformin decreased the relative cell number of LNCaP cells by inducing G1 cell cycle block, autophagy and apoptosis, and slightly increased cytosolic ATP levels, whereas RWPE-1 cells were resistant to metformin. However, RWPE-1 cells were sensitive to simvastatin, which induced G2 cell cycle block, autophagy and apoptosis, and increased cytosolic ATP levels in these cells. Combination of metformin and simvastatin synergistically decreased cytosolic ATP levels, increased autophagy and instead of apoptosis, induced necrosis in LNCaP cells. Synergistic effects were not observed in RWPE-1 cells. These results suggest, that prostate cancer cells may be more vulnerable to combined growth-inhibiting effects of metformin and simvastatin compared to normal cells. The data presented here provide evidence for the potency of combined metformin and statin, also at pharmacologic concentrations, as a chemotherapeutic option for prostate cancer.

The importance of LDL and cholesterol metabolism for prostate epithelial cell growth.

Cholesterol-lowering treatment has been suggested to delay progression of prostate cancer by decreasing serum LDL. We studied in vitro the effect of extracellular LDL-cholesterol on the number of prostate epithelial cells and on the expression of key regulators of cholesterol metabolism. Two normal prostatic epithelial cell lines (P96E, P97E), two in vitro immortalized epithelial cell lines (PWR-1E, RWPE-1) and two cancer cell lines (LNCaP and VCaP) were grown in cholesterol-deficient conditions. Cells were treated with 1-50 µg/ml LDL-cholesterol and/or 100 nM simvastatin for seven days. Cell number relative to control was measured with crystal violet staining. Changes in mRNA and protein expression of key effectors in cholesterol metabolism (HMGCR, LDLR, SREBP2 and ABCA1) were measured with RT-PCR and immunoblotting, respectively. LDL increased the relative cell number of prostate cancer cell lines, but reduced the number of normal epithelial cells at high concentrations. Treatment with cholesterol-lowering simvastatin induced up to 90% reduction in relative cell number of normal cell lines but a 15-20% reduction in relative number of cancer cells, an effect accompanied by sharp upregulation of HMGCR and LDLR. These effects were prevented by LDL. Compared to the normal cells, prostate cancer cells showed high expression of cholesterol-producing HMGCR but failed to express the major cholesterol exporter ABCA1. LDL increased relative cell number of cancer cell lines, and these cells were less vulnerable than normal cells to cholesterol-lowering simvastatin treatment. Our study supports the importance of LDL for prostate cancer cells, and suggests that cholesterol metabolism in prostate cancer has been reprogrammed to increased production in order to support rapid cell growth.

Comparative effects of high and low-dose simvastatin on prostate epithelial cells: the role of LDL.

Epidemiological studies have linked statin use with a decreased risk of advanced prostate cancer and an improved recurrence-free survival after radical therapy. It is unclear, however, whether statins could have direct effects against prostate cancer in a clinical setting, as their growth-inhibiting effects on prostate cancer cells have been demonstrated at drug concentrations which exceed the level in plasma during standard clinical dosing. We compared responses to high-dose and therapeutic-dose simvastatin in normal and cancerous prostate epithelial cells. Simvastatin was more effective at inhibiting the growth of normal prostate epithelial cells than of cancer cells. At therapeutic 100 nM concentration simvastatin had a cytostatic effect on normal cells: apoptosis was only slightly induced, but a decrease in cell cycle activity and an increase in senescence were observed. At therapeutic concentrations, lipophilic simvastatin caused a stronger growth inhibition than did hydrophilic rosuvastatin. In contrast, 10 µM simvastatin had a cytotoxic effect both on normal and cancer cells. Addition of LDL-cholesterol effectively reversed the cytostatic effect in all cell lines, but overcoming the cytotoxicity of 10 µM simvastatin required a combination of LDL-cholesterol and mevalonate. As LDL-cholesterol completely prevented the growth-inhibiting effect of therapeutic-dose simvastatin already at low, subphysiological concentrations it is unlikely that statins have direct effects on growth of prostate epithelial cells in vivo. Statins' possible benefits against prostate cancer could be due to systemic cholesterol-lowering, as suggested by epidemiological studies. Future clinical studies evaluating the effects of statins on prostate cancer prevention should monitor serum LDL and should probably administer statins at higher concentrations than those currently used in the treatment of hypercholesterolemia.

Inhibition of FOSL1 overexpression in antiestrogen-resistant MCF-7 cells decreases cell growth and increases vacuolization and cell death.

Elevated activator protein-1 (AP-1) activity in breast cancer cells has been linked to Tamoxifen (TAM) resistance. Fos-like antigen-1 (FOSL1) is a member of the AP-1 transcription factor and is overexpressed in a variety of human cancers including breast tumors. We have previously established an estrogen-independent and antiestrogen Toremifene (TOR)-resistant subline of MCF-7 breast cancer cells. In these cells, the expression of FOSL1 is upregulated when compared to the parental cells. In the present study, partial inhibition of FOSL1 expression in these cells by small interfering RNA resulted in a marked decrease of cell growth. The inhibition of cell growth paralleled with changes in cell morphology such as increased formation of vacuoles followed by an increase in the number of dead cells. The inhibition of FOSL1 expression in these cells also restored sensitivity to TOR. Our results suggest that chemotherapy targeting overexpression of FOSL1 could be a potent strategy for treating endocrine resistant breast cancers.

Gene expression changes during the development of estrogen-independent and antiestrogen-resistant growth in breast cancer cell culture models.

We have established estrogen-independent and antiestrogen-resistant cell lines from hormone-dependent MCF-7 breast cancer cells by long-term culture in the absence of estrogen, or in the presence of antiestrogen toremifene, respectively. By using a cDNA microarray we compared gene expression profiles among estrogen-independent, antiestrogen-resistant and long-term estrogen-treated MCF-7 cells. We also determined how the expression of the differentially expressed genes has developed during the long-term culture of the cell lines. Of the screened 1176 cancer-related genes, FOSL1, TIMP1, L1CAM, GDF15, and MYBL2 were found to be differentially expressed between the cell lines. A change in FOSL1 and TIMP1 expression could be attributed to the development of antiestrogen resistance, whereas induced L1CAM expression was implicated in the development of estrogen-independent growth of the cells. Estrogen regulated genes GDF15 and L1CAM became regulated by toremifene in the later passage number of toremifene-resistant cells, which might be an indication of the developed estrogen-agonistic activity of toremifene in these cells. Our findings suggest a pattern where the hormone-responsive cancer cells, which survive E2 deprivation and/or antiestrogen treatment, first acquire necessary changes in gene expression for transition to maximal growth in the new hormonal environment. Then, after prolonged treatment with antiestrogen, the antiestrogen-resistant cells may eventually generate an E2-agonistic response to antiestrogen, probably acquiring additional growth advantage.

Effects of simvastatin, acetylsalicylic acid, and rosiglitazone on proliferation of normal and cancerous prostate epithelial cells at therapeutic concentrations.

BACKGROUND: Non-steroidal anti-inflammatory drugs and cholesterol-lowering statins have been reported to inhibit prostate cancer cell growth suggesting their chemopreventive potential within the prostate. However, the effect has been demonstrated only with advanced prostate cancer cell lines and with drug concentrations above the clinical therapeutic range. In this study we compared the effect of therapeutic concentrations of acetylsalicylic acid, simvastatin and rosiglitazone on the growth of a set of prostatic primary cultures and various prostate epithelial cell lines. METHODS: Two primary epithelial cell lines isolated from surgical resecates of normal prostate tissue (P96E, P97E), a primary cell line isolated from untreated prostate carcinoma (ESTO1), two transformed prostate epithelial cell lines (PWR1-E, RWPE-1) and advanced cancer cell lines LNCaP and VCaP were used in the study. Cells were treated for seven days with therapeutic concentrations of acetylsalisylic acid, simvastatin, rosiglitazone or their combination. Cellular growth rate was measured by crystal violet staining method. RESULTS: Acetylsalicylic acid (0.5 mM) and simvastatin (10 nM) inhibited the growth of prostate epithelial cells of normal and primary cancer origin, whereas advanced cancer cell lines were resistant to the effect. Rosiglitazone at the therapeutic level of 1 microM did not reduce the growth of any cell type studied. CONCLUSIONS: Our results demonstrate that acetylsalicylic acid and simvastatin inhibit prostate epithelial cell growth at clinically relevant doses. This should be acknowledged when designing possible prostate cancer chemopreventive trials.

Changes in protein tyrosine phosphatase type IVA member 1 and zinc finger protein 36 C3H type-like 1 expression demonstrate altered estrogen and progestin effect in medroxyprogesterone acetate-resistant and estrogen-independent breast cancer cell models.

Estrogen stimulates proliferation in hormone-responsive breast cancer cells. Progestins inhibit the estrogen-mediated growth in these cells and are used in the treatment of mammary carcinomas. We applied cDNA microarray and real-time RT-PCR methods to reveal 17beta-estradiol- and medroxyprogesterone acetate (MPA)-regulated genes in MCF-7 breast cancer cells. We identified six genes, two of which were novel MPA and/or 17beta-estradiol-regulated genes: protein tyrosine phosphatase type IVA, member 1 (PTP4A1) and zinc finger protein 36, C3H type-like 1 (ZFP36L1). PTP4A1 expression was upregulated by 17beta-estradiol and this was opposed by MPA treatment of the cells. ZFP36L1 proved to be a direct target of MPA. Since MPA has also been shown to bind to glucocorticoid- and androgen receptors, we studied the regulation of the genes with progesterone, synthetic progestin R5020, dexamethasone and dihydrotestosterone. We also assessed the expression and hormonal regulation of PTP4A1 and ZFP36L1 mRNA in MCF-7-derived MPA-resistant and estrogen-independent sublines. The regulation of PTP4A1 expression upon 17beta-estradiol and combined 17beta-estradiol and MPA treatment was completely reversed in the estrogen-independent and MPA-resistant sublines, respectively. This study suggests an important role for PTP4A1 in cell growth, and shows that MPA may potentiate the effect of 17beta-estradiol in the MPA-resistant breast cancer cells.

Progestins regulate genes that can elicit both proliferative and antiproliferative effects in breast cancer cells.

Sex steroid hormone progesterone is known to have profound effects on the growth and differentiation of the normal mammary gland and malignant breast epithelial cells. In vitro progesterone and synthetic progesterone-like compounds (progestins) inhibit breast cancer cell growth. Medroxyprogesterone acetate (MPA) is a synthetic hormone widely used in the adjuvant treatment of advanced breast cancer, hormone replacement therapy and in oral contraceptives. It is a paradoxical hormone, since it inhibits breast cancer cell proliferation, but has also been implicated in increased breast cancer risk. To better understand the molecular mechanism by which cell proliferation and differentiation are regulated by progesterone and MPA in human breast cancer, we utilized cDNA microarray and quantitative real-time RT-PCR methods to identify their target genes. This study describes novel progestin/progesterone target genes in breast cancer cells and, notably, novel target genes that elucidate the underlying molecular mechanism of the dual role progestins play in the breast. A cDNA microarray containing 3000 genes showed notable regulation in 30 and 27 genes by MPA and progesterone, respectively. Only 6 out of the 30 genes regulated by MPA are down-regulated, but no progesterone down-regulation was observed. Overlapping in gene regulation by progesterone and MPA occurred, but the majority of genes regulated by these hormones were distinct. Given that progestins both stimulate and inhibit cancer cell growth, we report our findings on novel progestin and progesterone targets, which could explain the paradoxical actions of progestins in the breast.

Inhibition of fatty acid synthase expression by 1alpha,25-dihydroxyvitamin D3 in prostate cancer cells.

1alpha,25-dihydroxyvitamin D(3) (1alpha,25(OH)(2)D(3)) and its derivatives are a potential treatment of human prostate cancer. The antiproliferative action of 1alpha,25(OH)(2)D(3) is mainly exerted through nuclear vitamin D receptor (VDR)-mediated control of target gene transcription. To explore the target genes which are regulated by 1alpha,25(OH)(2)D(3) in human prostate cancer LNCaP cells, cDNA microarray was performed by using a chip that contains 3000 gene probes. The results showed that 24 genes were regulated by 1alpha,25(OH)(2)D(3). Five of them encode proteins which belong to metabolic enzymes and fatty acid biosynthesis. Fatty acid synthase (FAS) was found to be down-regulated by 1alpha,25(OH)(2)D(3), and the regulation was confirmed by real-time quantitative RT-PCR analysis. Inhibition of FAS expression by 1alpha,25(OH)(2)D(3) in LNCaP cells was more than 50% at 6h. Inhibitory effect of 1alpha,25(OH)(2)D(3) on FAS expression was completely blocked in the presence of protein synthesis inhibitor cycloheximide, indicating that the down-regulation of FAS gene expression by 1alpha,25(OH)(2)D(3) was indirect in LNCaP cells. An inhibition of FAS activity by cerulenin resulted in a strong inhibition of LNCaP cell proliferation. The inhibition of FAS expression and cell proliferation by 1alpha,25(OH)(2)D(3) seemed to be androgen-dependent, since antiandrogen, casodex and DCC-treatment of serum blocked the vitamin D action. The findings suggest that FAS is involved in the antiproliferative effect of 1alpha,25(OH)(2)D(3) in presence of androgens on prostate cancer LNCaP cells.

HDLG5/KIAA0583, encoding a MAGUK-family protein, is a primary progesterone target gene in breast cancer cells.

The steroid hormone progesterone is known to have profound effects on growth and differentiation of normal and malignant breast epithelial cells. The biologic actions of progesterone are exerted through the nuclear progesterone receptor-mediated control of target gene transcription. We utilized differential display polymerase chain reaction (DD-RT-PCR) to identify genes whose expression is altered in response to progestins in cultured breast cancer cells. Here we report identification of a gene encoding a member of the MAGUK protein family, hDlg5 (also known as KIAA0583 and P-dlg), as being the primary progestin target gene in MCF-7 breast cancer cells. Quantitative real-time RT-PCR analysis showed a rapid and strong upregulation of hDlg5 mRNA in cells treated with synthetic progestin medroxyprogesterone acetate (MPA) in the presence of estrogen in MCF-7, T47D and ZR-75-1 cells. The induction was abrogated by antiprogestin RU486. hDlg5 mRNA was also upregulated by progesterone, R5020 and dexamethasone. Protein synthesis inhibitor cycloheximide failed to block progestin-mediated induction of the hDlg5 gene. hDlg5 is a member of the growing family of MAGUKs (membrane-associated guanylate kinase homologs) and is to our knowledge the first member of the family reported to be hormonally regulated. hDlg5 is one of the human homologs of the Drosophila gene dlg [lethal(1)discs-large], which was initially identified as a tumor suppressor gene. The Dlg has a well-established role in cell growth control and maintenance of cell adhesion and cell polarity. Domain profile analysis revealed that hDlg5 has 2 additional PDZ domains than previously reported.

Progestin upregulates G-protein-coupled receptor 30 in breast cancer cells.

A differential display method was used to study genes the expression of which is altered during growth inhibition induced by medroxyprogesterone acetate (MPA). A transcript of G-protein-coupled receptor 30 (GPR30) was upregulated by MPA in estrogen-treated MCF-7 breast cancer cells. Northern-blot analysis showed a progestin-specific primary target gene, which was enhanced by progesterone and different progestins, but not by dihydrotestosterone or dexamethasone, and which was abrogated by antiprogestin RU486. The dose-dependent and time-dependent increase in GPR30 mRNA expression correlated with MPA-induced growth inhibition in MCF-7 cells. Additionally, GPR30 upregulation by progestin correlated with growth inhibition when a comparison was made between different breast cancer cell lines. The ERK1/ERK2 pathway is capable of inducing progesterone receptor-dependent and ligand-dependent transcription. Thus we sought to establish whether different MAPK pathway inhibitors affect progestin-induced GPR30 mRNA regulation. The regulation of GPR30 was independent of ERK pathway activation, but the p38 pathway inhibitor induced GPR30 expression, which suggested a potential gene regulation pathway. These data demonstrate a new progestin target gene, the expression of which correlates with growth inhibition.

Antiproliferative action of vitamin D.

During the past few years, it has become apparent that vitamin D may play an important role in malignant transformation. Epidemiological studies suggest that low vitamin D serum concentration increases especially the risk of hormone-related cancers. Experimentally, vitamin D suppresses the proliferation of normal and malignant cells and induces differentiation and apoptosis. In the present review we discuss the mechanisms whereby vitamin D regulates cell proliferation and whether it could be used in prevention and treatment of hyperproliferative disorders like cancers.