PNT1A Cells Research Articles

Clusterin enhances migration and invasion of prostate cancer cells through an isoform-specific Akt2/miR-190/PHLPP1 circuit.

During prostate cancer progression cancer cells undergo a variety of molecular alterations that lead to the acquisition of uncontrolled growth properties. One such set of molecular alterations is mediated by the PI3K/Akt signaling pathway. Here, we describe a regulatory system that modulates the phosphoinosited 3-kinase/Akt (PI3K/Akt) pathway downstream of secreted Clusterin (sCLU) in normal and cancer prostate cells. The overexpression of sCLU is very frequent in prostate cancer, and can lead to Akt-activation. This prompted us to investigate how sCLU overexpression influences PI3K/Akt signaling network in a study model represented by human epithelial prostate PNT1A cells stably transfected with sCLU or with empty vector alone. We found that CLU cells show a marked differential phosphorylation of several members of the PI3K/Akt cascade, and in particular of Akt2. Moreover, we found that the phosphatase PHLPP1, known to dephosphorylate Akt2 at S473, is severely downregulated in CLU compared to MOCK cells. We thus investigated whether sCLU alters PHLPP1 protein stability or expression. Our results indicate that sCLU indeed stimulates PHLPP1 degradation by β-TrCP. Interestingly, we further demonstrated that sCLU alters also PHLPP1 through the negative regulator miR-190. Next, because sCLU has been reported to inhibit or to stimulate the aggressive behavior of cancer cells depending on the cell model, we investigated the effects of CLU overexpression or addition of recombinant Clusterin to the medium on cell migration and invasion in PNT1A cell line, which is not expected to display an invasive phenotype, and in the cancer prostate epithelial cell lines LNCaP and PC3. The result was extremely clear: not only CLU overexpression gives PNT1A cells the same behavior of wild-type PC3 cells, but also increases the migration and invasion index of all the above cell models by two to four times, compared to controls. As a confirmation, in the same model silencing of Clusterin abrogates migration of CLU cells. Next, the effect of Akt single-isoform silencing on cell migration was explored. While silencing of Akt1 affected migration only slightly, silencing of Akt2 prevented migration of both MOCK and CLU cells completely. The same result was obtained by pharmacological inhibition of Akt2. All together our results, clearly demonstrate for the first time that Clusterin can switch the low migration phenotype of normal prostate cells towards a high migration phenotype through the modulation of the expression of the PHLPP1 and, in turn, the activity of Akt2.

The Zinc-Schiff Base-Novicidin Complex as a Potential Prostate Cancer Therapy.

Prostate cancer cells control energy metabolism by chelating intracellular zinc. Thus, zinc delivery has been a popular therapeutic approach for prostate cancer. Here, we propose the use of the membrane-penetrating peptide Novicidin connected to zinc-Schiff base as a carrier vehicle for the delivery of zinc to prostate cells. Mass spectrometry, electrochemistry and spectrophotometry confirmed the formation/stability of this complex and provided insight regarding the availability of zinc for complex interactions. This delivery system showed minor toxicity in normal PNT1A cells and high potency towards PC3 tumor cells. The complex preferentially penetrated PC3 tumor cells in contrast to confinement to the membranes of PNT1A. Furthermore, zinc uptake was confirmed in both cell lines. Molecular analysis was used to confirm the activation of zinc stress (e.g., ZnT-1) and apoptosis (e.g., CASP-1). Our results strongly suggest that the zinc-Schiff base-Novicidin complex has great potential as a novel anticancer drug.

Accumulation of Palmitoylcarnitine and Its Effect on Pro‐Inflammatory Pathways and Calcium Influx in Prostate Cancer

BACKGROUNDAcylcarnitines are intermediates of fatty acid oxidation and accumulate as a consequence of the metabolic dysfunction resulting from the insufficient integration between β‐oxidation and the tricarboxylic acid (TCA) cycle. The aim of this study was to investigate whether acylcarnitines accumulate in prostate cancer tissue, and whether their biological actions could be similar to those of dihydrotestosterone (DHT), a structurally related compound associated with cancer development.METHODSLevels of palmitoylcarnitine (palcar), a C16:00 acylcarnitine, were measured in prostate tissue using LC‐MS/MS. The effect of palcar on inflammatory cytokines and calcium (Ca2+) influx was investigated in in vitro models of prostate cancer.RESULTSWe observed a significantly higher level of palcar in prostate cancerous tissue compared to benign tissue. High levels of palcar have been associated with increased gene expression and secretion of the pro‐inflammatory cytokine IL‐6 in cancerous PC3 cells, compared to normal PNT1A cells. Furthermore, we found that high levels of palcar induced a rapid Ca2+ influx in PC3 cells, but not in DU145, BPH‐1, or PNT1A cells. This pattern of Ca2+ influx was also observed in response to DHT. Through the use of whole genome arrays we demonstrated that PNT1A cells exposed to palcar or DHT have a similar biological response.CONCLUSIONSThis study suggests that palcar might act as a potential mediator for prostate cancer progression through its effect on (i) pro‐inflammatory pathways, (ii) Ca2+ influx, and (iii) DHT‐like effects. Further studies need to be undertaken to explore whether this class of compounds has different biological functions at physiological and pathological levels. Prostate 76:1326–1337, 2016. © 2016 The Authors. The Prostate published by Wiley Periodicals, Inc.

Anti-tumor activity of the TRPM8 inhibitor BCTC in prostate cancer DU145 cells

The present study investigated the anti-tumor activity of N-(4-tertiarybutylphenyl)-4-(3-chloropyridin-2-yl)tetrahydropyrazine-1(2H)-carbox-amide (BCTC), a potent and specific inhibitor of transient receptor potential cation channel subfamily M member 8 (TRPM8) in prostate cancer (PCa) DU145 cells. TRPM8 expression in DU145 and normal prostate PNT1A cells was detected by reverse transcription polymerase chain reaction and western blot analysis. The effect of BCTC on DU145 cells was analyzed by flow cytometry analysis, and MTT, scratch motility and Transwell invasion assays. The molecular mechanism through which BCTC acts was investigated by western blot analysis. TRPM8 expression was increased in DU145 cells compared with PNT1A cells at the mRNA and protein levels. The present study provided evidence that inhibition of TRPM8 by BCTC reduced the viability of DU145 cells, but not PNT1A cells. In addition, BCTC inhibited cell cycle progression, migration and invasion in DU145 cells. Cell cycle-associated proteins, including phosphorylated protein kinase B, cyclin D1, cyclin dependent kinase (CDK) 2 and CDK6 were downregulated by BCTC, while phosphorylated glycogen synthase kinase 3β was upregulated. However, investigations in the present study revealed that BCTC failed to trigger apoptosis in DU145 cells. In addition, in BCTC-treated DU145 cells, phosphorylated extracellular signal-regulated kinase 1/2 was downregulated substantially while phosphorylated p38 (p-p38) and phosphorylated c-Jun N-terminal kinases (p-JNK) were upregulated. The anti-proliferative activity of BCTC on DU145 cells was attenuated by p38 and JNK-specific inhibitors, suggesting that MAPK pathways are involved. Overall, the TRPM8 specific antagonist BCTC demonstrated excellent anti-tumor activity in PCa DU145 cells, and therefore has the potential to become a targeted therapeutic strategy against PCa.

Effect of extracellular calcium on regucalcin expression and cell viability in neoplastic and non-neoplastic human prostate cells

Extracellular calcium (Ca2+o) and its receptor, the Ca2+-sensing receptor (CaSR), play an important role in prostate physiology, and it has been shown that the deregulation of Ca2+ homeostasis and the overexpression of CaSR are involved in prostate cancer (PCa). Regucalcin (RGN), a Ca2+-binding protein that plays a relevant role in intracellular Ca2+ homeostasis, was identified as an under-expressed protein in human PCa. Moreover, RGN was associated with suppression of cell proliferation, suggesting that the loss of RGN may favor development and progression of PCa. This work aims to unveil the role of Ca2+o on RGN expression and viability of non-neoplastic (PNT1A) and neoplastic (LNCaP) prostate cell lines. It was demonstrated that Ca2+o up-regulates RGN expression in both cell lines, but important differences were found between cells for dose- and time-responses to Ca2+o treatment. It was also shown that high [Ca2+]o triggers different effects on cell proliferation of neoplastic and non-neoplastic PCa cells, which seems to be related with RGN expression levels. This suggests the involvement of RGN in the regulation of cell proliferation in response to Ca2+o treatment. Also, the effect of Ca2+o on CaSR expression seems to be dependent of RGN expression, which is strengthened by the fact that RGN-knockdown in PNT1A cells increases the CaSR expression, whereas transgenic rats overexpressing RGN exhibit low levels of CaSR. Overall, our results highlighted the importance of RGN as a regulatory protein in Ca2+-dependent signaling pathways and its deregulation of RGN expression by Ca2+o may contribute for onset and progression of PCa.

Down-regulated CFTR During Aging Contributes to Benign Prostatic Hyperplasia.

Benign prostatic hyperplasia (BPH) is a hyper-proliferative disease of the aging prostate; however, the exact mechanism underlying the development of BPH remains incompletely understood. The present study investigated the possible involvement of the cystic fibrosis transmembrane conductance regulator (CFTR), which has been previously shown to negatively regulate nuclear factor-κB (NF-κB)/cyclooxygenase 2 (COX2)/prostaglandin E2 (PGE2) pathway, in the pathogenesis of BPH. Our results showed decreasing CFTR and increasing COX2 expression in rat prostate tissues with aging. Furthermore, suppression of CFTR led to increased expression of COX2 and over-production of PGE2 in a normal human prostate epithelial cell line (PNT1A) with elevated NF-κB activity. PGE2 stimulated the proliferation of primary rat prostate stromal cells but not epithelial cells, with increased PCNA expression. In addition, the condition medium from PNT1A cells after inhibition or knockdown of CFTR promoted cell proliferation of prostate stromal cells which could be reversed by COX2 or NF-κB inhibitor. More importantly, the involvement of CFTR in BPH was further demonstrated by the down-regulation of CFTR and up-regulation of COX2/NF-κB in human BPH samples. The present results suggest that CFTR may be involved in regulating PGE2 production through its negative regulation on NF-κB/COX2 pathway in prostate epithelial cells, which consequently stimulates cell growth of prostate stromal cells. The overstimulation of prostate stromal cell proliferation by down-regulation of CFTR-enhanced PGE2 production and release during aging may contribute to the development of BPH.

Function of phosphorylation of NF-kB p65 ser536 in prostate cancer oncogenesis.

Majority of prostate cancer (PCa) patients carry TMPRSS2/ERG (T/E) fusion genes and there has been tremendous interest in understanding how the T/E fusion may promote progression of PCa. We showed that T/E fusion can activate NF-kB pathway by increasing phosphorylation of NF-kB p65 Ser536 (p536), but the function of p536 has never been studied in PCa. We report here that active p536 can significantly increase cell motility and transform PNT1a cells (an immortalized normal cell line), suggesting p536 plays a critical role in promoting PCa tumorigenesis. We have discovered a set of p536 regulated genes, among which we validated the regulation of CCL2 by p536. Based on all evidence, we favor that T/E fusion, NF-kB p536 and CCL2 form a signaling chain. Finally, PNT1a cells (not tumorigenic) can form tumors in SCID mice when overexpressing of either wild type or active p65 in the presence of activated AKT, demonstrating synergistic activities of NF-kB and AKT signals in promoting PCa tumorigenesis. These findings indicate that combination therapies targeting T/E fusion, NF-kB, CCL2 and/or AKT pathways may have efficacy in T/E fusion gene expressing PCa. If successful, such targeted therapy will benefit more than half of PCa patients who carry T/E fusions.

Cell Survival and DNA Damage in Normal Prostate Cells Irradiated Out-of-Field

Interest in out-of-field radiation dose has been increasing with the introduction of new techniques, such as volumetric modulated arc therapy (VMAT). These new techniques offer superior conformity of high-dose regions to the target compared to conventional techniques, however more normal tissue is exposed to low-dose radiation with VMAT. There is a potential increase in radiobiological effectiveness associated with lower energy photons delivered during VMAT as normal cells are exposed to a temporal change in incident photon energy spectrum. During VMAT deliveries, normal cells can be exposed to the primary radiation beam, as well as to transmission and scatter radiation. The impact of low-dose radiation, radiation-induced bystander effect and change in energy spectrum on normal cells is not well understood. The current study examined cell survival and DNA damage in normal prostate cells after exposure to out-of-field radiation both with and without the transfer of bystander factors. The effect of a change in energy spectrum out-of-field compared to in-field was also investigated. Prostate cancer (LNCaP) and normal prostate (PNT1A) cells were placed in-field and out-of-field, respectively, with the PNT1A cells being located 1 cm from the field edge when in-field cells were being irradiated with 2 Gy. Clonogenic and γ-H2AX assays were performed postirradiation to examine cell survival and DNA damage. The assays were repeated when bystander factors from the LNCaP cells were transferred to the PNT1A cells and also when the PNT1A cells were irradiated in-field to a different energy spectrum. An average out-of-field dose of 10.8 ± 4.2 cGy produced a significant reduction in colony volume and increase in the number of γ-H2AX foci/cell in the PNT1A cells compared to the sham-irradiated control cells. An adaptive response was observed in the PNT1A cells having first received a low out-of-field dose and then the bystander factors. The PNT1A cells showed a significant increase in γ-H2AX foci formation when irradiated to 20 cGy in-field in comparison to out-of-field. However, no significant difference in cell survival or colony volume was observed whether the PNT1A cells were irradiated in-field or out-of-field. Out-of-field radiation dose alone can have a damaging effect on the proliferation of PNT1A cells when a clinically relevant dose of 2 Gy is delivered in in-field. Out-of-field radiation with the transfer of bystander factors induces an adaptive response in the PNT1A cells.

Clinical evaluation of inter-fractional organ motion using 3D ultrasound image-guided radiotherapy for positioning prostate cancer patients

Clinical evaluation of inter-fractional organ motion using 3D ultrasound image-guided radiotherapy for positioning prostate cancer patients

Expression of STEAP1 and STEAP1B in prostate cell lines, and the putative regulation of STEAP1 by post-transcriptional and post-translational mechanisms

STEAP1 gene is overexpressed in several kinds of tumors, particularly in prostate cancer. Besides STEAP1, there is another related gene, STEAP1B, which may encode two different transcripts. Although several studies have been pointing STEAP1 as a putative immunotherapeutic target and biomarker, the mechanisms underlying its regulation are not fully understood. In silico analysis allowed us to show that STEAP1 and STEAP1B share high homology, but with slight differences at structural level. Experiments with prostate cells showed that STEAP1B2 is overexpressed in cancer cells. Regarding STEAP1 regulation, it is demonstrated that the stability of mRNA and protein is higher in LNCaP than in PNT1A cells. Of note, serum triggered opposite effects in LNCaP and PNT1A in relation to STEAP1 stability, e.g., increasing it in PNT1A and decreasing in LNCaP. These results suggest that STEAP1 may be regulated by post-transcriptional and post-translational modifications (PTM), which may differ between non-neoplastic and neoplastic cells. These PTM are supported through in silico analysis, where several modifications such as N-glycosylation, N-Glycation, Phosphorylation and O-linked β-N-acetylglucosamine, may occur in STEAP1 protein. In conclusion, these data indicate that STEAP1B2 is overexpressed in neoplastic cells, and PTM may be involved in regulation of STEAP1 expression in prostate cells.

AKT and AMPK activation after high-fat and high-glucose in vitro treatment of prostate epithelial cells.

Considering the increasing consumption of saturated fat and glucose in diets worldwide and its possible association to carcinogenesis, this investigation analysed the proliferation profile of nonmalignant human prostate epithelial cells after exposure to elevated levels of fat and glucose. PNT1A cells were cultured with palmitate (100 or 200 μM) and/or glucose (450 mg/dl) for 24 or 48 h. Treated cells were evaluated for viability test and cell proliferation (MTS assay). AKT and AMPK phosphorylation status were analysed by Western blotting. After 24 h of high-fat alone or associated with high-glucose treatment, there was an increase in AMPK and AKT activation associated to unchanged MTS-cell proliferation. Following 48 h of high-fat but not high-glucose alone, cells decreased AMPK activation and maintained elevated AKT levels. These data were associated to increased cell proliferation after further high-fat treatment. After longer high-fat exposure, MTS revealed that cells remained proliferating. High-glucose alone or associated to high-fat treatment was not able to increase cell proliferation and AKT activation. A high-fat medium containing 100 μM of palmitate stimulates proliferation in PNT1A cells by decreasing the activation of AMPK and increasing activation of AKT after longer exposure time. These findings improve the knowledge about the negative effect of high levels of this saturated fatty acid on proliferative disorders of prostate.

Polyphenon E®, a standardized green tea extract, induces endoplasmic reticulum stress, leading to death of immortalized PNT1a cells by anoikis and tumorigenic PC3 by necroptosis

Increasing doses of Polyphenon E®, a standardized green tea extract, were given to PNT1a and PC3 prostate epithelial cells mimicking initial and advanced stages of prostate cancer (PCa), respectively. Cell death occurred in both cell lines, with PNT1a being more sensitive [half-maximal inhibitory concentration (IC50) = 35 μg/ml] than PC3 (IC50 = 145 μg/ml) to Polyphenon E®. Cell cycle arrest occurred at G0/G1 checkpoint for PNT1a, and G2/M for PC3 cells. Endoplasmic reticulum stress (ERS) and unfolded protein response (UPR) occurred in both cell lines, with each exhibiting different timing in response to Polyphenon E®. Autophagy was transiently activated in PNT1a cells within 12 h after treatment as a survival response to overcome ERS; then activation of caspases and cleavage of poly (ADP ribose) polymerase 1 occurred, committing cells to anoikis death. Polyphenon E® induced severe ERS in PC3 cells, causing a dramatic enlargement of the ER; persistent activation of UPR produced strong upregulation of GADD153/CHOP, a key protein of ERS-mediated cell death. Thereafter, GADD153/CHOP activated Puma, a BH3-only protein, committing cells to necroptosis, a programmed caspase-independent mechanism of cell death. Our results provide a foundation for the identification of novel targets and strategies aimed at sensitizing apoptosis-resistant cells to alternative death pathways.

Diallyl Trisulfide Is More Cytotoxic to Prostate Cancer Cells PC-3 than to Noncancerous Epithelial Cell Line PNT1A: A Possible Role of p66Shc signaling Axis

Diallyl trisulfide (DATS) is an organosulfur compound isolated from garlic, and has been shown to have anticancer activity both in vitro and in vivo. The aim of this study was to compare cytotoxic effects of DATS on prostate cancer cells PC-3 and noncancerous human prostate epithelial cells PNT1A. PC-3 prostate cancer and noncancerous human prostate epithelial cells PNT1A were used in the study. We observed that PNT1A cells had higher resistance to DATS-induced cell death than PC-3 cells. Investigating signaling pathways involved in the cell death we observed that p66Shc phosphorylation at serine 36 and extracellular signal-regulated kinase 1/2 activation induced by DATS, were significantly attenuated in PNT1A cells as compared to PC-3 cells. Moreover, DATS-induced Akt inactivation was also significantly reduced in PNT1A cells. In addition to that, DATS-induced reactive oxygen species generation was nearly completely abolished in PNT1A cells. Interestingly, DATS induced only slight decrease in the level of ferritin H, whereas ferritin L was elevated. These data suggest that cytotoxicity of DATS toward PNT1A cells is strongly reduced as opposed to PC-3 cancer cells, which corresponds to the lower activation of prodeath signaling pathway mediated by the adaptor protein p66Shc in the noncancerous PNT1A cells.

The over-expression of Pim-2 promote the tumorigenesis of prostatic carcinoma through phosphorylating eIF4B

Cell experiments have found Pim-2 may take part in the tumorigenesis of prostatic carcinoma (PCA). More direct evidences are needed, and the detailed anti-apoptotic mechanism of Pim-2 in PCA cells is still unknown. Pim-2 expression levels were compared between benign prostatic hyperplasia (BPH) tissues and PCA tissues using real time PCR and Western blot, respectively. Then Pim-2 expression levels were detected in PCA cell lines DU-145 and LNCaP, as well as in nontumorous prostatic epithelial cell lines RWPE-1 and PNT1a, using real time PCR and Western blot, respectively. The co-expression of Pim-2 and eukaryotic initiation factor 4B (eIF4B) was examined by immunofluorescence cytochemistry using laser scanning confocal microscope. Finally, Pim-2 SiRNA was transfected into DU-145 cells and Pim-2 was transfected into RWPE-1 cells, and the level of Pim-2 and phosphorylated eukaryotic initiation factor 4B (p-eIF4B) were detected, as well as the apoptosis rate. The Pim-2 mRNA and protein level were significantly higher in PCA tissues than those in BPH tissues. The Pim-2 mRNA and protein level in DU-145 and LNCaP cells were significantly higher than those in RWPE-1 and PNT1a cells. Pim-2 and eIF4B could co-express in DU-145 cells. Pim-2 level determined the phosphorylation level of eIF4B and the apoptosis rate of prostatic cells. The higher Pim-2 expressed, the more eIF4B phosphorylated, then the less cell got apoptosis, and vice versa. Pim-2 was over-expressed in PCA cell lines and tissues. It may inhibit the apoptosis of PCA cells through phosphorylating eIF4B, thus promote the tumorigenesis of PCA.

Flavanols from Evening Primrose (Oenothera paradoxa) Defatted Seeds Inhibit Prostate Cells Invasiveness and Cause Changes in Bcl-2/Bax mRNA Ratio

In this study, we assessed the influence of an evening primrose flavanol preparation (EPFP) on proliferation and invasiveness of human prostate cancer cells (DU 145) and immortalized prostate epithelial cells (PNT1A). We report for the first time that EPFP reduces DU 145 cell proliferation (IC50 = 97 μM GAE for 72 h incubation) and invasiveness (by 24% versus control at 75 μM GAE). EPFP strongly inhibited PNT1A invasiveness in a concentration-dependent manner (by 67% versus control at 75 μM GAE) and did not cause a reduction in their proliferation. Furthermore, EPFP inhibited the activities of MMP-2 and MMP-9 secreted to culture medium by PNT1A cells by 84% and 34% versus control at 100 μM GAE, respectively. In the case of DU 145, MMP-9 activity at 100 μM GAE was reduced by 37% versus control. Moreover, the evening primrose seed flavanols suppressed the expression of selected genes (MMP-1, MMP-9, MMP-14, c-Fos, c-Jun, and VEGF) and also caused favorable changes in Bcl-2/Bax mRNA ratio which render DU 145 cells more sensitive to apoptosis-triggering agents. An additional confirmation of the proapoptotic activity of EPFP toward DU 145 was visualization of characteristic apoptotic bodies by DAPI staining. In conclusion, this study suggests that EPFP may increase apoptosis and reduce angiogenesis of prostate cancer cells.

Effectiveness of the Histone Deacetylase Inhibitor (S)-2 against LNCaP and PC3 Human Prostate Cancer Cells

Histone deacetylase inhibitors (HDACi) represent a promising class of epigenetic agents with anticancer properties. Here, we report that (S)-2, a novel hydroxamate-based HDACi, shown previously to be effective against acute myeloid leukemia cells, was also a potent inducer of apoptosis/differentiation in human prostate LNCaP and PC3 cancer cells. In LNCaP cells (S)-2 was capable of triggering H3/H4 histone acetylation, H2AX phosphorylation as a marker of DNA damage and producing G0/G1 cell cycle arrest. Consistently, (S)-2 led to enhanced expression of both the protein and mRNA p21 levels in LNCaP cells but, contrary to SAHA, not in normal non-tumorigenic prostate PNT1A cells. Mechanistic studies demonstrated that (S)-2-induced apoptosis in LNCaP cells developed through the cleavage of pro-caspase 9 and 3 and of poly(ADP-ribose)-polymerase accompanied by the dose-dependent loss of mitochondrial membrane potential. Indeed, the addition of the pan-caspase inhibitor Z-VAD-fmk greatly reduced drug-mediated apoptosis while the antioxidant N-acetyl-cysteine was virtually ineffective. Importantly, preliminary data with nude mice xenografted with LNCaP cells showed that (S)-2 prompted a decrease in the tumor volume and an increase in H2AX phosphorylation within the cancer cells. Moreover, the highly metastatic prostate cancer PC3 cells were also sensitive to (S)-2 that: i) induced growth arrest and moderate apoptosis; ii) steered cells towards differentiation and neutral lipid accumulation; iii) reduced cell invasiveness potential by decreasing the amount of MMP-9 activity and up-regulating TIMP-1 expression; and iv) inhibited cell motility and migration through the Matrigel. Overall, (S)-2 has proven to be a powerful HDACi capable of inducing growth arrest, cell death and/or differentiation of LNCaP and PC3 prostate cancer cells and, due to its low toxicity and efficacy in vivo, might also be of clinical interest to support conventional prostate cancer therapy.

Expression of orexin A and its receptor 1 in the human prostate.

The peptides orexin A (OXA) and orexin B, deriving from the cleavage of the precursor molecule prepro-orexin, bind two G-coupled transmembrane receptors, named as receptor 1 (OX1R) and receptor 2 for orexin, showing different affinity-binding properties. First discovered in the rat hypothalamus, orexins and their receptors have been also found in many peripheral tissues where they exert neuroendocrine, autocrine and paracrine functions. Because inconclusive data on their localization in the mammalian prostate are reported, the aim of this study was to investigate the presence of prepro-orexin, OXA and OX1R in the human normal and hyperplastic gland. Immunohistochemistry revealed the localization of both OXA and OX1R in the cytoplasm of the follicular exocrine epithelium of all tested normal and hyperplastic prostates. Positive immunostaining was mainly observed in the basal cells of the stratified epithelium, and only rarely in the apical cells. The expression of mRNAs coding for prepro-orexin and OX1R and of proteins in the tissues was also ascertained by polymerase chain reaction and Western blotting analysis, respectively. In order to gain insights into the functional activity of OXA in the prostate, we administered different concentrations of OXA to cultured prostatic epithelial cells PNT1A. We first demonstrated that PNT1A cells express OX1R. The addition of OXA did not affect PNT1A cell proliferation, while it enhanced cAMP synthesis and Ca(2+) release from intracellular storage. Overall, our results definitely demonstrate the expression of OXA and OX1R in the human prostate, and suggest an active role for them in the metabolism of the gland.

Prostate cancer cells metabolize d-lactate inside mitochondria via a d-lactate dehydrogenase which is more active and highly expressed than in normal cells

Although d-lactate metabolism has been shown to occur in a variety of mitochondria, the metabolic fate of d-lactate in cancer cells has never been investigated, as it is believed to be exported to the extracellular phase. We show that mitochondria from both cancer (PC-3) and normal (PNT1A) prostate cells can metabolize d-lactate in an energy competent manner. This is due to the mitochondrial d-lactate dehydrogenase, a membrane flavoprotein, the activity and protein level of which are higher in PC-3 than in PNT1A cells, as detected by both kinetic and immunological analysis. d-Lactate can enter prostate mitochondria and cause the export of newly synthesized malate in a carrier-mediated manner, with the rate of malate efflux from mitochondria twofold higher in cancer.

Androgen receptor CAG repeat length modifies the effect of 2,3,7,8-tetrachlorodibenzo-p-dioxin on receptor activity in human prostate cells

Increased incidence of prostate cancer has been reported in men exposed to 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD). TCDD acts through the aryl hydrocarbon receptor (AhR), which interacts with the androgen receptor (AR). The AR gene contains a polymorphic CAG repeat that influences its transcriptional activity. We investigated the influence of TCDD on prostate cancer cells (PC-3) and non-tumor prostate cells (PNT1A) on 5α-dihydrotestosterone-activated ARs containing CAG repeats within normal length range (16, 22, and 28). The AhR target gene CYP1A1 mRNA expression was induced by TCDD, but was not affected by the AR CAG length. TCDD had no effect on AR activity in PC-3 cells, whereas the shortest AR variant was induced by TCDD in PNT1A cells. In conclusion, the CAG length dependent effect of TCDD on AR activity in PNT1A, but not in PC-3 cells, indicates as a cell-specific effect of TCDD on AR activity.

Targeting Fibroblast Growth Factor Receptor Signaling Inhibits Prostate Cancer Progression

Extensive correlative studies in human prostate cancer as well as studies in vitro and in mouse models indicate that fibroblast growth factor receptor (FGFR) signaling plays an important role in prostate cancer progression. In this study, we used a probe compound for an FGFR inhibitor, which potently inhibits FGFR-1-3 and significantly inhibits FGFR-4. The purpose of this study is to determine whether targeting FGFR signaling from all four FGFRs will have in vitro activities consistent with inhibition of tumor progression and will inhibit tumor progression in vivo. Effects of AZ8010 on FGFR signaling and invasion were analyzed using immortalized normal prostate epithelial (PNT1a) cells and PNT1a overexpressing FGFR-1 or FGFR-4. The effect of AZ8010 on invasion and proliferation in vitro was also evaluated in prostate cancer cell lines. Finally, the impact of AZ8010 on tumor progression in vivo was evaluated using a VCaP xenograft model. AZ8010 completely inhibits FGFR-1 and significantly inhibits FGFR-4 signaling at 100 nmol/L, which is an achievable in vivo concentration. This results in marked inhibition of extracellular signal-regulated kinase (ERK) phosphorylation and invasion in PNT1a cells expressing FGFR-1 and FGFR-4 and all prostate cancer cell lines tested. Treatment in vivo completely inhibited VCaP tumor growth and significantly inhibited angiogenesis and proliferation and increased cell death in treated tumors. This was associated with marked inhibition of ERK phosphorylation in treated tumors. Targeting FGFR signaling is a promising new approach to treating aggressive prostate cancer.