Ellagic acid, a component of pomegranate fruit juice, suppresses androgen-dependent prostate carcinogenesis via induction of apoptosis.

BACKGROUND: Ellagic acid (EA), a component of pomegranate fruit juice (PFJ), is a plant-derived polyphenol and has antioxidant properties. PFJ and EA have been reported to suppress various cancers, including prostate cancer. However, their chemopreventive effects on development and progression of prostate cancer using in vivo models have not been established yet. METHODS: The transgenic rat for adenocarcinoma of prostate (TRAP) model was used to investigate the modulating effects of PFJ and EA on prostate carcinogenesis. Three-week-old male transgenic rats were treated with EA or PFJ for 10 weeks. In vitro assays for cell growth, apoptosis, and Western blot were performed using the human prostate cancer cell lines, LNCaP (androgen-dependent), PC-3 and DU145 (androgen-independent). RESULTS: PFJ decreased the incidence of adenocarcinoma in lateral prostate, and both EA and PFJ suppressed the progression of prostate carcinogenesis and induced apoptosis by caspase 3 activation in the TRAP model. In addition, the level of lipid peroxidation in ventral prostate was significantly decreased by EA treatment. EA was able to inhibit cell proliferation of LNCaP, whereas this effect was not observed in PC-3 and DU145. As with the in vivo data, EA induced apoptosis in LNCaP by increasing Bax/Bcl-2 ratio and caspase 3 activation. Cell-cycle related proteins, p21(WAF) , p27(Kip) , cdk2, and cyclin E, were increased while cyclin D1 and cdk1 were decreased by EA treatment. CONCLUSIONS: The results indicate that PFJ and EA are potential chemopreventive agents for prostate cancer, and EA may be the active component of PFJ that exerts these anti-cancer effects.

TANK-binding kinase 1 (TBK1) controls cell survival through PAI-2/serpinB2 and transglutaminase 2.

The decision between survival and death in cells exposed to TNF relies on a highly regulated equilibrium between proapoptotic and antiapoptotic factors. The TNF-activated antiapoptotic response depends on several transcription factors, including NF-κB and its RelA/p65 subunit, that are activated through phosphorylation-mediated degradation of IκB inhibitors, a process controlled by the IκB kinase complex. Genetic studies in mice have identified the IκB kinase-related kinase TANK-binding kinase 1 (TBK1; also called NAK or T2K) as an additional regulatory molecule that promotes survival downstream of TNF, but the mechanism through which TBK1 exerts its survival function has remained elusive. Here we show that TBK1 triggers an antiapoptotic response by controlling a specific RelA/p65 phosphorylation event. TBK1-induced RelA phosphorylation results in inducible expression of plasminogen activator inhibitor-2 (PAI-2), a member of the serpin family with known antiapoptotic activity. PAI-2 limits caspase-3 activation through stabilization of transglutaminase 2 (TG2), which cross-links and inactivates procaspase-3. Importantly, Tg2(-/-) mice were found to be more susceptible to apoptotic cell death in two models of TNF-dependent acute liver injury. Our results establish PAI-2 and TG2 as downstream mediators in the antiapoptotic response triggered upon TBK1 activation.

Establishment of a syngeneic orthotopic model of prostate cancer in immunocompetent rats.

We previously established 3 cell lines (PLS10, PLS20 and PLS30) from a chemically-induced prostate carcinoma in F344 rats, and demonstrated high potential for metastasis in nude mice. In the present study, we investigated the feasibility of establishing an orthotopic model using the 3 rat prostate cancer cell lines in immunocompetent rats with the aim of resolving species-mismatch problems and defects of immune systems. The PLS10, PLS20 and PLS30 cell lines were injected into the ventral prostates of 6-week-old rats, which were then sacrificed at experimental weeks 4 and 8. Tumor mass formation was found in rats with PLS10, but not in those with PLS20 or PLS30. Additionally, metastatic carcinomas could be detected in lymph nodes and lungs of PLS10-inoculated rats. Genetic analysis demonstrated K-ras gene mutations in PLS10 and PLS20, but not in PLS30 cells. There were no mutations in p53 and KLF6. In conclusion, we established a syngeneic orthotopic model for prostate cancer in immunocompetent rats simulating human castration-resistant prostate cancer (CRPC), which should prove useful for development and validation of therapeutic agents, especially with immunotherapy.

GPX2 overexpression is involved in cell proliferation and prognosis of castration-resistant prostate cancer.

There is a need for exploration of new therapeutic strategies that target distinct molecular mechanisms of castration-resistant prostate cancer (CRPC) because its emergence following androgen deprivation therapy is a major clinical problem. In this report, we investigated the role of glutathione peroxidase 2 (GPX2) in CRPC. GPX2 expression was analyzed in rat and human CRPC cells. Next, we determined the proliferation rate and level of reactive oxygen species (ROS) in GPX2-small interfering RNA (siRNA)-transfected CRPC cells. For in vivo analysis, siRNA-transfected cells were subcutaneously implanted into normal and castrated nude mice. Further, immunohistochemical and prognostic analyses of GPX2 were performed using human specimens. Silencing of GPX2 caused significant growth inhibition and increased intracellular ROS in both rat (PCai1) and human (PC3) CRPC cells. Flow cytometry and western blot analyses revealed that the decrease in proliferation rate of the GPX2-silenced cells was due to cyclin B1-dependent G2/M arrest. Furthermore, knockdown of Gpx2 inhibited tumor growth of PCai1 cells in castrated mice. Immunohistochemical analyses indicated that expression of GPX2 was significantly higher in residual cancer foci after neoadjuvant hormonal therapy than in hormone naive cancer foci. Moreover, patients with high GPX2 expression in biopsy specimen had significantly lower prostate-specific antigen recurrence-free survival and overall survival than those with no GPX2 expression. These findings suggest that GPX2 is a prognostic marker in CRPC and affects proliferation of prostate cancer under androgen depletion partially through protection against ROS signaling.

Cooperative functions of Chk1 and Chk2 reduce tumour susceptibility in vivo.

Although the linkage of Chk1 and Chk2 to important cancer signalling suggests that these kinases have functions as tumour suppressors, neither Chk1+/- nor Chk2-/- mice show a predisposition to cancer under unperturbed conditions. We show here that Chk1+/-Chk2-/- and Chk1+/-Chk2+/- mice have a progressive cancer-prone phenotype. Deletion of a single Chk1 allele compromises G2/M checkpoint function that is not further affected by Chk2 depletion, whereas Chk1 and Chk2 cooperatively affect G1/S and intra-S phase checkpoints. Either or both of the kinases are required for DNA repair depending on the type of DNA damage. Mouse embryonic fibroblasts from the double-mutant mice showed a higher level of p53 with spontaneous DNA damage under unperturbed conditions, but failed to phosphorylate p53 at S23 and further induce p53 expression upon additional DNA damage. Neither Chk1 nor Chk2 is apparently essential for p53- or Rb-dependent oncogene-induced senescence. Our results suggest that the double Chk mutation leads to a high level of spontaneous DNA damage, but fails to eliminate cells with damaged DNA, which may ultimately increase cancer susceptibility independently of senescence.

Multigenerational effects of whole body exposure to 2.14 GHz W-CDMA cellular phone signals on brain function in rats.

The present experimental study was carried out with rats to evaluate the effects of whole body exposure to 2.14 GHz band code division multiple access (W-CDMA) signals for 20 h a day, over three generations. The average specific absorption rate (SAR, in unit of W/kg) for dams was designed at three levels: high (<0.24 W/kg), low (<0.08 W/kg), and 0 (sham exposure). Pregnant mothers (4 rats/group) were exposed from gestational day (GD) 7 to weaning and then their offspring (F1 generation, 4 males and 4 females/dam, respectively) were continuously exposed until 6 weeks of age. The F1 females were mated with F1 males at 11 weeks old, and then starting from GD 7, they were exposed continuously to the electromagnetic field (EMF; one half of the F1 offspring was used for mating, that is, two of each sex per dam and 8 males and 8 females/group, except for all offspring for the functional development tests). This protocol was repeated in the same manner on pregnant F2 females and F3 pups; the latter were killed at 10 weeks of age. No abnormalities were observed in the mother rats (F0 , F1 , and F2 ) and in the offspring (F1 , F2 , and F3 ) in any biological parameters, including neurobehavioral function. Thus, it was concluded that under the experimental conditions applied, multigenerational whole body exposure to 2.14 GHz W-CDMA signals for 20 h/day did not cause any adverse effects on the F1 , F2 , and F3 offspring.

Mutational analysis of FOXL2 p.C134W and expression of bone morphogenetic protein 2 in Japanese patients with granulosa cell tumor of ovary.

AIM: To assess whether FOXL2 p.C134W mutation may play a role in the development of human ovarian tumors in the Japanese, we investigated the FOXL2 codon 134 mutation and protein expression of inhibin-α, bone morphogenetic protein 2 (BMP2) and follistatin (FST) in Japanese patients with granulosa cell tumor (GCT) of the ovary and other ovarian tumors. METHODS: We analyzed 114 tumor tissues from ovarian tumors, including 44 adult-type and two juvenile-type GCT of the ovary and 68 ovarian tumors by DNA sequencing. Immunohistochemistry was also performed in the adult and juvenile GCT tissues by immunostaining inhibin-α, BMP2 and FST. RESULTS: We found the FOXL2 p.C134W mutation in 27 out of 44 (61.4%) adult-type GCT of the ovary, but none in other ovarian tumors. Histologically, all of the adult-type GCT sections were positive for inhibin-α, and the expression of BMP2 and FST was detected in 14 of 44 (31.8%) and zero of 47 (0%), respectively. No significant differences regarding the diagnosed age, preoperative serum carbohydrate antigen 125 levels, or BMP2 immunopositivity between the FOXL2 p.C134W mutation-positive and mutation-negative were found in the adult-type GCT patients. CONCLUSION: Our findings suggest that FOXL2 p.C134W mutation-positive adult-type GCT of the ovary may not be common in the Japanese as compared to the previous data.

Establishment of an invasive prostate cancer model in transgenic rats by intermittent testosterone administration.

We have established a transgenic rat for adenocarcinoma of the prostate (TRAP) model that features uniform adenocarcinoma development in prostatic lobes at high incidence within a short experimental period. However, no invasive carcinomas with reactive stroma characteristics similar to those in man were observed. We therefore have focused on a new model for invasive carcinoma of the prostate using TRAP rats. In experiment 1, male TRAP rats in groups 1 and 2 were treated with orchiectomy at day 0 of the experiment. Rats in groups 1-3 underwent testosterone propionate (TP) implantation from weeks 1 to 4 and from weeks 6 to 16. Rats in groups 1 and 3 were given 3,2'-dimethyl-4-aminobiphenyl (DMAB) after TP implantation. The rats of group 4 served as controls. In experiment 2, the rats were divided into three groups, none of which received DMAB or orchiectomy, treated with TP continuously or with the treatment withdrawn once or twice. In experiment 1, invasive adenocarcinomas with abundant collagenous stroma were found in the dorsolateral and anterior prostate, some of which showed perineural space invasion at week 16. The number of invasive carcinoma foci was most frequent in group 3. In experiment 2, invasive adenocarcinoma development in the lateral prostates was correlated with the number of TP administration/withdrawal cycles. In conclusion, our newly established rat model for invasive adenocarcinoma of the prostate could serve as a useful preclinical model for evaluating the in vivo efficacy of preventive and therapeutic agents targeting of the tumor microenvironment.

Long-term phase angle muscle imaging under electrical muscle stimulation (EMS) by phase angle electrical impedance tomography.

Objectives. Phase angle muscle imaging has been proposed by phase angle electrical impedance tomography (ΦEIT) under electrical muscle stimulation (EMS) for long-term monitoring of muscle quality improvement, especially focusing on calf muscles.Approach. In the experiments, twenty-four subjects are randomly assigned either to three groups: control group (CG,n= 8), low voltage intensity of EMS training group (LG,n= 8), and optimal voltage intensity of EMS training group (OG,n= 8).Main results. From the experimental results, phase angle distribution imagesФare cleared reconstructed by ФEIT as four muscle compartments over five weeks experiments, which are called theM1muscle compartments composed of gastrocnemius muscle,M2muscle compartments composed of soleus muscle,M3muscle compartments composed of tibialis-posterior muscle, flexor digitorum longus muscle, and flexor pollicis longus muscle, andM4muscle compartment composed of the tibialis anterior muscle, extensor digitorum longus muscle, and peroneus longus muscle.Фis inversely correlated with age, namely theФdecreases with increasing age. A paired samplest-test was conducted to elucidate the statistical significance of spatial-mean phase angle in all domain <Ф>Ωand in each muscle compartment <Ф>Mwith reference to the conventional phase angle Ф by bioelectrical impedance analysis, muscle grey-scaleGmuscleby ultrasound, and maximal dynamic strengthSMaxby one-repetition maximum test.Significance. From thet-test results, <Ф>Ωhave good correlation with Ф andSMax. In the OG, <ФW5>Ω,ФW5, and (SMax)W5were significantly higher than in the first week (n= 8,p< 0.05). A significant increase in the phase angle of bothM1andM4muscle compartments is observed after five weeks in LG and OG groups. Only the OG group shows a significant increase in the phase angle ofM2muscle compartment after five weeks. However, no significant changes in the spatial-mean phase angle ofM3compartment are observed in each group. In conclusion, ФEIT satisfactorily monitors the response of each compartment in calf muscle to long-term EMS training.

2-Amino-1-methyl-6-phenylimidazo[4,5-b]pyridine (PhIP)-DNA adducts in benign prostate and subsequent risk for prostate cancer.

Despite convincing evidence that 2-amino-1-methyl-6-phenylimidazo[4,5-b]pyridine (PhIP)--a heterocyclic amine generated by cooking meats at high temperatures--is carcinogenic in animal models, it remains unclear whether PhIP exposure leads to increased cancer risk in humans. PhIP-DNA adduct levels were measured in specimens from 534 prostate cancer case-control pairs nested within a historical cohort of men with histopathologically benign prostate specimens. We estimated the overall and race-stratified risk of subsequent prostate cancer associated with higher adduct levels. PhIP-DNA adduct levels in benign prostate were significantly higher in Whites than African Americans (0.274 optical density units (OD) ±0.059 vs. 0.256 OD ±0.054; p<0.0001). Prostate cancer risk for men in the highest quartile of PhIP-DNA adduct levels was modestly increased [odds ratio (OR) = 1.25; 95% confidence interval (CI) = 0.76-2.07]. In subset analyses, the highest risk estimates were observed in White patients diagnosed more than 4 years after cohort entry (OR = 2.74; 95% CI = 1.01-7.42) or under age 65 (OR = 2.80; 95% CI = 0.87-8.97). In Whites, cancer risk associated with high-grade prostatic intraepithelial neoplasia combined with elevated PhIP-DNA adduct levels (OR = 3.89; 95% CI = 1.56-9.73) was greater than risk associated with either factor alone. Overall, elevated levels of PhIP-DNA adducts do not significantly increase prostate cancer risk. However, our data show that White men have higher PhIP-DNA adduct levels in benign prostate tissue than African American men, and suggest that in certain subgroups of White men high PhIP-DNA adduct levels may predispose to an increased risk for prostate cancer.

Apocynin, an NADPH oxidase inhibitor, suppresses rat prostate carcinogenesis.

Recent evidence suggests that oxidative stress contributes to the pathogenesis of prostate cancer. The present study focused on the effect of apocynin, an inhibitor of NADPH oxidase, on prostate carcinogenesis using the transgenic rat for adenocarcinoma of prostate (TRAP) model. There were no toxic effects with apocynin treatment. The percentages and numbers of carcinomas in both the ventral and lateral prostate were significantly reduced by apocynin treatment, with dose dependence. Reduction of reactive oxygen species by apocynin was confirmed by immunohistochemistry of 8-OHdG and dihydroethidium staining. Positivity of Ki67 was significantly reduced by apocynin treatment, and downregulation of clusterin expression, as well as inactivation of the MEK-ERK1/2 pathway, was a feature of the apocynin treated groups. In human prostate cancer cell line LNCaP, apocynin also inhibited reactive oxygen species production and blocked cell growth by inducing G0/G1 arrest with downregulation of clusterin and cyclin D1. These data suggest that apocynin possesses chemopreventive potential against prostate cancer.

Purple corn color inhibition of prostate carcinogenesis by targeting cell growth pathways.

Purple corn color is a widely used food colorant that was reported to have attenuating effects on hypertension, diabetes, and to have anti-cancer effects on colon and breast cancer. Our study is the first on its possible chemoprevention effects against prostate cancer. For this purpose an androgen-dependent prostate cancer cell line, LNCaP, was used to examine effects in vitro. Purple corn color inhibited the proliferation of LNCaP cells by decreasing the expression of Cyclin D1 and inhibiting the G1 stage of the cell cycle. Thirty-six male transgenic rats for adenocarcinoma of prostate were fed basic diet or diet with purple corn color for 8 weeks. Purple corn color decreased the incidence of adenocarcinoma in the lateral prostate and slowed down the progression of prostate cancer. A lower Ki67 positive rate, a decrease of the expression of Cyclin D1, and downregulation of the activation of Erk1/2 and p38 MAPK were observed in the group consuming purple corn color in the diet. Since purple corn color is a mixture, determining its active component should help in the understanding and usage of purple corn color for prostate cancer chemoprevention. Therefore, the three major anthocyanins in purple corn color, cyanidin-3-glucoside, pelargonidin-3-glucoside and peonidin-3-glucoside, were tested with LNCaP cells. The results suggested that cyanidin-3-glucoside and pelargonidin-3-glucoside are the active compounds.

MMP-7 promotes prostate cancer-induced osteolysis via the solubilization of RANKL.

We developed a rodent model that mimics the osteoblastic and osteolytic changes associated with human metastatic prostate cancer. Microarray analysis identified MMP-7, cathepsin-K, and apolipoprotein D as being upregulated at the tumor-bone interface. MMP-7, which was produced by osteoclasts at the tumor-bone interface, was capable of processing RANKL to a soluble form that promoted osteoclast activation. MMP-7-deficient mice demonstrated reduced prostate tumor-induced osteolysis and RANKL processing. This study suggests that inhibition of MMP-7 will have therapeutic benefit in the treatment of prostate cancer-induced osteolysis.

Organ differences in the impact of p27(kip1) deficiency on carcinogenesis induced by N-methyl-N-nitrosourea.

To evaluate the impact of p27 on carcinogenesis in various organs, N-methyl-N-nitrosourea (MNU), a direct-acting alkylating agent, was given to p27 knock-out mice. Groups of 20-40 male and female mice with null, hetero- or wild-type p27 alleles were given drinking water containing 240 ppm MNU or distilled water every other week for five cycles. The incidence and multiplicity of the induced proliferative lesions were then histologically evaluated at weeks 14 and 20. MNU treatment induced various lesions including squamous hyperplasia and squamous cell carcinoma in the forestomach, atypical hyperplasia and adenocarcinomas in the fundic and pyloric glands, adenomas and adenocarcinomas in the duodenum, malignant lymphomas in the thymus, liver, kidney and spleen and alveolar hyperplasia, adenomas, adenocarcinomas and malignant lymphomas in the lung. Although the incidences of the lesions in the forestomach, fundic and pyloric glands did not differ among the p27 genotypes, those of alveolar hyperplasia of the lung and malignant lymphoma of the thymus were significantly increased in p27-null males as compared with both wild- and hetero-type animals. Moreover, in both p27(+/+) and p27(+/-) cases, the rates for p27-positive cells were obviously increased in proliferative lesions of the pyloric gland and the lung. However, an increased rate of p27-positive cells was not observed in malignant lymphoma of the thymus. These findings suggest that p27 does not control the cell cycle equally in all organs affected by MNU-induced carcinogenesis.

Physiological-induced conductive response evaluation in specific muscle compartments under hybrid of electrical muscle stimulation and voluntary resistance training by electrical impedance tomography.

Objective: The physiological-induced conductive response has been visualised for evaluation in specific muscle compartments under hybrid (hybridEMS) of electrical muscle stimulation (EMS) and voluntary resistance training (VRT) by electrical impedance tomography (EIT). Methods: In the experiments, tendency of conductivity distribution images σ over time was clearly detected for three specific muscle compartments, which are called AM 1 compartment composed of biceps brachii muscle, AM 2 compartment composed of triceps brachii muscle, and AM 3 compartment composed of brachialis muscle, under three training modalities. Results: From the experimental results, the tendency of physiological-induced conductive response are increased in all three training modalities with increasing training time. Correspondingly, the spatial-mean conductivity <σ>AM1,AM2,AM3 increased with the conductance value G and extracellular water ratio ß of right arm by bio-impedance analysis (BIA) method. In addition, hybridEMS has the greatest effect on physiological-induced conductive response in AM 1, AM 2, and AM 3. Under hybridEMS, the spatial-mean conductivity increased from <σ pre > AM1 = 0.154 to <σ 23mins > AM1 = 0.810 in AM 1 muscle compartment (n = 8, p < 0.001); <σ pre > AM2 = 0.040 to <σ 23mins > AM2 = 0.254 in AM 2 muscle compartment (n = 8, p < 0.05); <σ pre > AM3 = 0.078 to <σ 23mins > AM3 = 0.497 in AM 3 muscle compartment (n = 8, p < 0.05). Conclusion: The paired-samples t-test results of <σ>AM1,AM2,AM3 under all three training modalities suggest hybridEMS has the most efficient elicitation on physiological induced conductive response compared to VRT and EMS. The effect of EMS on deep muscle compartment (AM 3) is slower compared to VRT and hybridEMS, with a significant difference after 15 min of training.

Silencing of connexin 43 suppresses invasion, migration and lung metastasis of rat hepatocellular carcinoma cells.

To reduce cancer mortality, understanding of mechanisms of cancer metastasis is crucial. We have established six rat hepatocellular carcinoma (HCC) cell lines, which exhibit differing metastatic potential to the lung after inoculation into the tail veins of nude mice. In the present experiment, we investigated the process of cell attachment to metastatic sites and possible regulating factors. One hour after inoculation, two of two HCC cell lines with high metastatic potential and one of two HCC cell lines with low metastatic potential exhibited many attached cells in the lung. One day after inoculation, lung metastatic foci were observed only with highly-metastatic cells with elevated connexin 43 (Cx43) expression as assessed by cDNA array analysis. Furthermore, 24 or 48 h after transfection of an siRNA targeting Cx43, in vitro invasion and migration were suppressed by 68% (P < 0.001) and 36% (P < 0.05) compared with control-siRNA transfected cells, despite no differences in cellular morphology, cell proliferation or apoptotic activity. Moreover, the number of metastatic nodules per lung area in nude mice was significantly (P < 0.01) reduced. In conclusion, suppression of Cx43 expression in tumor cells reduced in vitro migration and invasion capacity and in vivo metastatic ability so that Cx43 has potential as a molecular target for prevention of cancer metastasis with Cx43 overexpressing tumors.

Organ specific Gst-pi expression of the metastatic androgen independent prostate cancer cells in nude mice.

BACKGROUND: Elucidating the mechanisms of metastasis in prostate cancer, particularly to the bone, is a major issue for treatment of this malignancy. We previously reported that an androgen-independent variant had higher expression of glutathione S-transferase pi (Gst-pi) compared with a parent androgen-dependent transplantable rat prostate carcinoma which was established from the transgenic rat for adenocarcinoma of the prostate (TRAP). METHODS: A new cell line, PCai1, was established from the androgen-independent tumor and investigated its metastatic potential in nude mice. The tumorigenesis of PCai1 cells in vivo was studied by subcutaneous transplantations into nude mice. The growth in the microenvironment of the prostate was studied by orthotopic transplantation of PCai1 cells into nude mice. The metastatic potential of PCai1 cells was studied by tail vein injections. Effects of Gst-pi knocked down were analysis in PCai1 cells. RESULTS: PCai1 frequently formed metastatic lesions in the lung and lymph nodes after orthotopic implantation in the prostate. Intravenous injections of PCai1, metastasis to lung and bone were obvious. PCai1 had strong expression for Gst-pi, therefore we tried knocked down Gst-pi. Gst-pi-siRNA in vitro significantly suppressed cell proliferation rate. In addition, high levels of intracellular reactive oxygen species (ROS) were recognized in the Gst-pi knockout. CONCLUSIONS: Gst-pi expression of the prostate cancers are dependent on metastatic site, and that Gst-pi has an important role in adapting prostate cancer for growth and metastasis involving an alteration of ROS signals.

Therapeutic targeting of angiotensin II receptor type 1 to regulate androgen receptor in prostate cancer.

BACKGROUND: With the limited strategies for curative treatment of castration-resistant prostate cancer (CRPC), public interest has focused on the potential prevention of prostate cancer. Recent studies have demonstrated that an angiotensin II receptor blocker (ARB) has the potential to decrease serum prostate-specific antigen (PSA) level and improve performance status in CRPC patients. These facts prompted us to investigate the direct effects of ARBs on prostate cancer growth and progression. METHODS: Transgenic rat for adenocarcinoma of prostate (TRAP) model established in our laboratory was used. TRAP rats of 3 weeks of age received ARB (telmisartan or candesartan) at the concentration of 2 or 10 mg/kg/day in drinking water for 12 weeks. In vitro analyses for cell growth, ubiquitylation or reporter gene assay were performed using LNCaP cells. RESULTS: We found that both telmisartan and candesartan attenuated prostate carcinogenesis in TRAP rats by augmentation of apoptosis resulting from activation of caspases, inactivation of p38 MAPK and down-regulation of the androgen receptor (AR). Further, microarray analysis demonstrated up-regulation of estrogen receptor ß (ERß) by ARB treatment. In both parental and androgen-independent LNCaP cells, ARB inhibited both cell growth and AR-mediated transcriptional activity. ARB also exerted a mild additional effect on AR-mediated transcriptional activation by the ERß up-regulation. An intervention study revealed that PSA progression was prolonged in prostate cancer patients given an ARB compared with placebo control. CONCLUSION: These data provide a new concept that ARBs are promising potential chemopreventive and chemotherapeutic agents for prostate cancer.

Age-dependent carcinogenic susceptibility in rat liver is related to potential of gap junctional intercellular communication.

Connexin 32 (Cx32) is a major gap junction protein in the liver. The authors previously demonstrated that transgenic rats carrying a dominant negative mutant of Cx32 (Cx32ΔTg) have much decreased capacity for gap junctional intercellular communication (GJIC) and increased susceptibility to diethylnitrosamine (DEN)-induced hepatocarcinogenesis as compared to littermate wild-type (wt) rats. To evaluate the age-dependent susceptibility to DEN-induced hepatocarcinogenesis and alteration of GJIC function, male Cx32ΔTg and wt rats at 10, 30, or 85 weeks old were given a single intraperitoneal administration of DEN (40 mg/rat) and sacrificed 12 weeks later. The number and area of glutathione S-transferase placental form (GST-P)-positive preneoplastic foci were significantly increased in the liver of 10- and 30-wk-old Cx32ΔTg rats compared with age-matched wt. However, in the 85-wk-old rats, both Cx32ΔTg and wt rats had similarly large number and area of GST-P-positive foci, and the difference was not significant. Interestingly, function of hepatic GJIC was reduced and protein and mRNA expression of Cx32 were decreased with aging in wt rats. These results suggest that a decline of hepatic intercellular communication through gap junction results in increased susceptibility to DEN-induced hepatocarcinogenesis in aged rats.

Histone H1 expression in human prostate cancer tissues and cell lines.

Histone H1, one of the histone superfamilies, is known to determine chromatin structure and alter gene expression. It also contributes to regulation of cell proliferation in breast cancer. We hypothesized a similar association in prostate cancer, and therefore examined relationships between histone H1 expression and Gleason pattern, Ki-67 and androgen receptor levels in a series of prostate cancer tissues and cell lines. Histone H1 positive cancer cells increased with the Gleason pattern. Gleason pattern 3 tumors were divided into two groups, one with high histone H1 positivity (H1-high cases, 60-100% positivity) and the other with low histone H1 positivity (H1-low cases, 0-20% positivity). Ki-67 or androgen receptor positivity in H1-high cases was significantly higher than in H1-low cases. PC3 cells demonstrated more frequent histone H1 and Ki-67 positivity as compared to LNCaP cells. Silencing of histone H1 by siRNA transfection significantly reduced cell proliferation in LNCaP and PC3. These findings suggest that histone H1 expression is associated with the Gleason pattern, cell proliferation and androgen receptor expression in prostate cancers.