Search PubMed⌕ Search

Biomedical subjects

Atsushi Mizokami

Publications and source records attributed to Atsushi Mizokami.

At least 19 recordsLinked to original sources
PubMed2007

Global update on defining and treating high-risk localized prostate cancer with leuprorelin: an Asian perspective.

Data from the Japanese Urological Society showed that, in Japan, almost half of patients with localized prostate cancer are treated with hormone therapy (HT), regardless of disease stage, and that radiation therapy (RT) is also widely used to treat high-risk patients. A retrospective study was undertaken in Japan to evaluate the potential benefits of using primary HT in locally advanced prostate cancer. Of 628 patients in the study, 63.5% were treated with combined androgen blockade (CAB; luteinizing hormone-releasing hormone agonists plus an antiandrogen) and 36.5% with medical or surgical castration. CAB treatment was significantly better than hormone monotherapy for disease-specific survival. The results also showed that, even if a patient is classified as 'high-risk', a good prognosis could normally be predicted based on certain variables: if their initial prostate-specific antigen (PSA) level was < or = 20 ng/mL, their Gleason score was < or = 6, and their nadir PSA decreased to < or = 0.2 ng/mL within 6 months of HT. In this subgroup of 'good responders', any treatment, be it prostatectomy, RT or CAB, is likely to be effective. However, in 'poor responders', combined therapies with CAB and high-dose rate brachytherapy are likely to be needed for a clinical response. While HT is effective, it might be associated with a reduction in the patient's quality of life (QoL) due to adverse effects, e.g. a reduction in sexual function. Results from the analysis of QoL questionnaires completed by men of different ages with prostate cancer found that only sexual function, and not other QoL variables, in men aged 50-59 years appeared to be reduced in men who had HT, compared to age-matched controls.

Antineoplastic Agents, Hormonal↗
PubMed2006

Metastasis suppressor gene Raf kinase inhibitor protein (RKIP) is a novel prognostic marker in prostate cancer.

BACKGROUND: Diminished expression of Raf kinase inhibitor protein (RKIP), an inhibitor of the Raf signaling cascade, promotes prostate cancer (PCa) metastasis in a murine model, suggesting that it is a metastasis suppressor gene. However, the prognostic significance of RKIP expression and its association with metastasis in PCa patients is unknown. METHODS: To investigate RKIP protein expression is a prognostic marker in PCa we performed immunohistochemical staining for RKIP expression in tissue microarrays consisting of 758 non-neoplastic prostate tissues, primary tumors and metastases from 134 PCa patients. The Cox proportional-hazards model was used to adjust for covariates including Gleason score, tumor volume, tumor weight, clinical stage, digital rectal exam findings, serum PSA level and surgical margins. RESULTS: RKIP expression was low in approximately 5%, 48%, and 89% of non-neoplastic prostate, primary tumors and metastases, respectively. Low RKIP expression in primary tumors was a strong positive predictive factor for PCa recurrence based on PSA levels. In patients whose primary tumors expressed high RKIP levels, the 7-year PSA recurrence rate was <10%; whereas in patients with tumors with low RKIP expression the recurrence rate was 50% (P<0.001). Multivariate analysis revealed RKIP was an independent prognostic factor (P<0.001). CONCLUSION: In contrast to increased expression of pro-tumorigenic genes, these results demonstrate decreased protein expression of a gene, for example, RKIP, can serve as a prognostic marker in PCa patients.

Biomarkers, Tumor↗
PubMed2006

Four year clinical statistics of iridium-192 high dose rate brachytherapy.

BACKGROUND: We evaluated the efficacy and complications of high dose rate (HDR) brachytherapy using iridium-192 (192Ir) combined with external beam radiotherapy (EBRT) in patients with prostate cancer. METHODS: Ninety-seven patients underwent 192Ir HDR brachytherapy combined with EBRT at our institution between February 1999 and December 2003. Of these, 84 patients were analysed in the present study. 192Ir was delivered three times over a period of 2 days, 6 Gy per time, for a total dose of 18 Gy. Interstitial application was followed by EBRT at a dose of 44 Gy. Progression was defined as three consecutive prostate-specific antigen (PSA) rises after a nadir according to the American Society for Therapeutic Radiology and Oncology criteria. The results were classified into those for all patients and for patients who did not undergo adjuvant hormone therapy. RESULTS: The 4-year overall survival of all patients, the nonadjuvant hormone therapy group (NAHT) and the adjuvant hormone therapy group (AHT) was 87.2%, 100%, and 70.1%, respectively. The PSA progression-free survival rate of all patients, NAHT, and AHT was 82.6%, 92.0%, and 66.6%, respectively. Of all patients, the 4-year PSA progression-free survival rates of PSA<20 and PSA>or=20 groups were 100%, and 46.8%, respectively. According to the T stage classification, PSA progression-free survival rates of T1c, T2, T3, and T4 were 100%, 82.8%, 100%, and 12.1%, respectively. Prostate-specific antigen progression-free survival rates of groups with Gleason scores (GS)<7 and GS>or=7 were 92.8% and 60.1%, respectively. Of NAHT, PSA progression-free survival of PSA<20 was 100% vs 46.8% for PSA>or=20, that of T1c was 100% vs 75% for T2, and that of GS<7 was 100% vs 75% for GS>or=7. No significant intraoperative or postoperative complications requiring urgent treatment occurred except cerebellum infarction. CONCLUSIONS: 192Ir HDR brachytherapy combined with EBRT was as effective as radical prostatectomy and had few associated complications.

Aged↗
PubMed2006

Novel HER2 selective tyrosine kinase inhibitor, TAK-165, inhibits bladder, kidney and androgen-independent prostate cancer in vitro and in vivo.

PURPOSE: TAK-165 is a new potent inhibitor of human epidermal growth factor receptor 2 (HER2) tyrosine kinase. Several reports suggest HER2 expression in bladder cancer, renal cell carcinoma (RCC) and androgen-independent prostate cancer. We therefore investigated the antitumor effect of TAK-165 on these urological cancer cells. MATERIALS AND METHODS: Western blot analysis was performed to confirm HER2 expression in cell lines. To study in vitro efficacy, cells were treated with TAK-165 at various concentrations for 72 h and then counted using a hemocytometer. Then the IC50 value was calculated. In the xenograft model, after the tumor reached 200-300 mm3 in volume, mice were orally administered TAK-165 10 mg/kg per day or 20 mg/kg per day or saline for 14 consecutive days (n=6-8). RESULTS: HER2 expression was observed in HT1376, UMUC3, T24 (bladder), ACHN (kidney), DU145, LNCaP, LN-REC4 (prostate), although the expression level in these cells was weak compared with BT474 (a breast cancer cell line which expresses HER2 strongly). IC50 was varied from 0.09 to greater than 25 micromol/L in the bladder cancer cell line. ACHN cells were less sensitive in vitro. The prostate cancer cell lines studied were all sensitive (IC50 0.053-4.62 micromol/L). In the xenograft model, treatment with TAK-165 significantly inhibited growth of UMUC-3, ACHN, and LN-REC4. The antitumor effect (T/C [%]=growth of TAK-165 treated tumor/average growth of control tumorx100) after 14 days treatment were 22.9%, 26.0%, and 26.5% in UMUC3, ACHN and LN-REC4, respectively. CONCLUSIONS: TAK-165 may be a hopeful new agent for bladder, kidney and androgen-independent prostate cancer.

Androgens↗
PubMed2006

Bisphosphonate induces apoptosis and inhibits pro-osteoclastic gene expression in prostate cancer cells.

AIM: Bisphosphonates are well established for the management of cancer-induced skeletal complications. Recent studies suggest that bisphosphonates promote apoptosis of cancer cells as well as osteoclasts in bone metastatic sites. To determine the direct effects of bisphosphonate on prostate cancer, we examined the effects of minodronate on prostatic cancer cell growth and the expression of apoptosis-related proteins and osteoclastogenic factors. METHODS: PC-3, DU145 and LNCaP cells were treated with amino-bisphosphonate minodronate. Then proliferation, apoptosis and expression of bcl-2, bax, poly (ADP)-ribose polymerase (PARP), caspase-3, receptor activator of nuclear factor-kappaB ligand (RANKL), osteoprotegerin (OPG), matrix metalloproteinases-2 (MMP-2), and parathyroid hormone related protein (PTHrP) were assessed. RESULTS: The proliferation of prostatic cancer cells was inhibited by minodronate. DNA fragmentation and TUNEL-positive nuclei were observed in minodronate-treated PC-3 cells. Minodronate decreased bcl-2 expression and induced bax expression, caspase-3 activity and degradation of PARP in DU145 and PC-3 cells. Minodronate decreased expression of RANKL, PTHrP and MMP-2 in PC-3 cells. CONCLUSIONS: Our results suggest that bisphosphonate not only promotes apoptosis directly but also decreases pro-osteoclastic gene expression in prostate cancer cells.

Apoptosis↗
PubMed2005

The bisphosphonate YM529 inhibits osteolytic and osteoblastic changes and CXCR-4-induced invasion in prostate cancer.

Bisphosphonates are useful for the treatment of prostate cancer bone metastasis. However, the role of bisphosphonate on the development of the osteoblastic component of prostate cancer bone metastases is not defined. In the present study, the third-generation bisphosphonate, YM529 (minodoronate), was tested for its effects on the osteolytic PC-3 and novel osteoblastic LNCaP-SF cell lines. YM529 inhibited both osteolytic and osteoblastic changes in an intratibial tumor injection murine model. In vitro, YM529 inhibited both the proliferation and the invasion of both prostate cancer cell lines. The stromal cell-derived factor-1 (or CXCL12)/CXCR-4 pathway is believed to play an important role in the development of prostate cancer bone metastases. Thus, we determined if YM529 affected this pathway. YM529 suppressed CXCR-4 expression in PC-3 and LNCaP-SF in vitro and in vivo and this was associated with decreased in vitro invasion. These results suggest that YM529 may inhibit cancer cell invasion into the bone matrix by repressing the expression of CXCR-4 in bone metastasis lesions.

Animals↗
PubMed2005

Determination of prostatic androgens in 10 mg of tissue using liquid chromatography-tandem mass spectrometry with charged derivatization.

A practical liquid chromatography-tandem mass spectrometric (LC-MS-MS) method for the determination of prostatic 5alpha-dihydrotestosterone (DHT) and testosterone (T) has been developed. The prostatic androgens were extracted with MeOH-H2O (3:7, v/v), purified with an Oasis HLB cartridge, derivatized with the permanently charged reagent 2-hydrazino-1-methylpyridine (HMP), and subjected to LC-MS-MS analysis using electrospray ionization (ESI) operated in the positive ion mode. The derivatization with HMP was very effective at increasing the detectability using the positive-ESI-MS. The method allowed the reproducible and accurate quantification of ng g(-1) tissue levels of prostatic androgens in 10 mg of tissue. That is, the intra- and inter-assay coefficients of variation were below 8.1 and 9.3%, respectively, and the analytical recoveries of the androgens were quantitative. The limits of quantitation for DHT and T were both 1.0 ng g(-1) tissue. The developed method was used to determine DHT and T in the prostates of patients with benign prostatic hyperplasia and prostate cancer, and satisfactory results were obtained.

Chromatography, Liquid↗
PubMed2005

Determination of sulfates of androsterone and epiandrosterone in human serum using isotope diluted liquid chromatography-electrospray ionization-mass spectrometry.

A promising liquid chromatography-electrospray ionization-mass spectrometry (LC-ESI-MS) for analysis of the sulfates of 5alpha-androgen, androsterone and epiandrosterone (A-S and EpiA-S) in human serum was developed. The method was used to assess one of the markers of 5alpha-reductase activity of males including patients with prostate cancer (PC). After deproteinization with acetonitrile, the androgen sulfates and the internal standard, [7,7,16,16-2H4]dehydroepiandrosterone-S, were extracted from human serum using a solid-phase extraction cartridge and washed with hexane. The extract was reconstituted and applied to the LC/ESI-MS system operated in the selected ion monitoring mode. The method was validated over the range 0.02-5 microg/mL (A-S) and 0.005-1.5 microg/mL (EpiA-S) using 10 microL of human serum. The method was a concise procedure without chemical or enzymatic hydrolysis of the conjugates, purification by high-performance liquid chromatography and/or derivatization, and proved to be satisfactory in its reproducibility and accuracy. The levels of these androgen sulfates tended to decrease during aging, and the A-S levels in the sera obtained from both healthy males and patients with PC were correlated with their EpiA-S levels.

Adult↗
PubMed2005

In vitro chemosensitivity test for human genito-urinary tumors using collagen gel matrix.

BACKGROUND: Although the aim of chemosensitivity tests is to predict the efficacy of anticancer agents for individual patients, no generally accepted assay has been established. METHODS: A chemosensitivity test was conducted for solid tumors with an organ culture system using collagen gel matrix (CGM). Seventy-five samples of transitional cell carcinoma (TCC), 20 of germ cell tumor (GCT) and 13 of renal cell carcinoma (RCC) were used for the chemosensitivity test, and 20 patients were treated with anticancer drugs on the basis of the test results. RESULTS: Positive rates of anticancer drugs for the 75 TCC samples were 64.9% for carboplatin, 63.4% for cisplatin, 32.1% for etoposide, 19.7% for THP-adriamycin, 16.7% for vinblastine, and 12.3% for methotrexate, indicating that positive rates of the latter three agents consisting of an MVAC regimen were unexpectedly low. The GCT had higher positive rates than the other cancers while RCC had the lowest. In 20 eligible patients (seven patients with bladder tumors and 13 with GCT), the true positive and true negative rates were 42% (5/12) and 75% (6/8), respectively, and the sensitivity and specificity were 71% (5/7) and 46% (6/13), resulting in a 55% (11/20) accurate predictive value. CONCLUSION: Although predictive accuracy was moderate when combination chemotherapy was used, information about chemosensitivity may have some beneficial effect on the treatment of patients with invasive bladder cancer or advanced GCT, because insensitive drugs detected by the test could be deleted or replaced with more sensitive ones.

Antineoplastic Agents↗
PubMed2004

Antiandrogenic activity of extracts of diesel exhaust particles emitted from diesel-engine truck under different engine loads and speeds.

To clarify the alteration of androgenic and antiandrogenic activities by diesel engine conditions, we collected diesel exhaust particles (DEP) samples emitted from a diesel-engine truck under different conditions of engine loads and vehicle speeds, and DEP extract (DEPE) samples were prepared from each. The androgenic and antiandrogenic activities of the DEPE samples were examined using a prostate specific antigen (PSA) promoter-luciferase reporter gene assay in PC3/AR human prostate cancer cells. While all DEPE samples did not exhibit androgenic effects, the antiandrogenic effects were enhanced by higher engine load but not by higher vehicle speed. In this study, significant correlations between antiandrogenic and aryl hydrocarbon receptor (AhR) agonistic activities were demonstrated in PC3/AR cells by 16 polycyclic aromatic compounds and beta-naphthoflavone. Yeast two-hybrid assay and cytochrome P450 (CYP) 1A1 promoter-luciferase reporter gene assay showed that the antiandrogenic constituents acting as androgen receptor (AR) antagonists and AhR agonists were increased by only the higher engine load. In conclusion, the antiandrogenic effects of DEPE samples were enhanced by a higher engine load which resulted in DEPC samples with elevated AhR agonistic and AR antagonistic activities.

Adenocarcinoma↗
PubMed2004

Vascular endothelial growth factor contributes to the prostate cancer-induced osteoblast differentiation mediated by bone morphogenetic protein.

Human prostate cancer has a high predisposition to metastasize to bone, resulting in the formation of osteoblastic metastases. The mechanism through which prostate cancer cells promote osteoblastic lesions is undefined. Vascular endothelial growth factor (VEGF) has been implicated as a mediator of osteoblast activity. In the present study, we examined if prostate cancer cells promote osteoblastic activity through VEGF. We found that LNCaP and C4-2B prostate cancer cell lines and primary tumor and metastatic prostate cancer tissues from patients expressed VEGF. Bone morphogenetic proteins (BMPs), which are normally present in the bone environment, induced VEGF protein and mRNA expression in C4-2B cells. Furthermore, BMP-7 activated the VEGF promoter. Noggin, a BMP inhibitor, diminished VEGF protein expression and promoter activity in C4-2B cells. Conditioned media (CM) from C4-2B cells induced pro-osteoblastic activity (increased alkaline phosphatase, osteocalcin, and mineralization) in osteoblast cells. Both noggin alone and anti-VEGF antibody alone diminished C4-2B CM-induced pro-osteoblastic activity. Transfection of C4-2B cells with VEGF partially rescued the C4-2B CM-induced pro-osteoblastic activity from noggin inhibition. These observations indicate that BMPs promote osteosclerosis through VEGF in prostate cancer metastases. These results suggest a novel function for VEGF in skeletal metastases. Specifically, VEGF promotes osteoblastic lesion formation at prostate cancer bone metastatic sites.

Bone Morphogenetic Proteins↗
PubMed2004

The adrenal androgen androstenediol is present in prostate cancer tissue after androgen deprivation therapy and activates mutated androgen receptor.

Despite an initial response to androgen deprivation therapy, prostate cancer (PCa) progresses eventually from an androgen-dependent to an androgen-independent phenotype. One of the mechanisms of relapse is antiandrogen withdrawal phenomenon caused by mutation of 877th amino acid of androgen receptor (AR). In the present study, we established a method to measure the concentration of androstenediol (adiol) in prostate tissue. We found that adiol maintains a high concentration in PCa tissue even after androgen deprivation therapy. Furthermore, adiol is a stronger activator of mutant AR in LNCaP PCa cells and induces more cell proliferation, prostate-specific antigen (PSA) mRNA expression, and PSA promoter than dihydrotestosterone (DHT). Because antiandrogen, bicalutamide, blocked adiol activity in LNCaP cells, it was suggested that adiol effect was mediated through AR. However, high concentration of bicalutamide was necessary to block completely adiol activity. These effects were specific to LNCaP cells because adiol had less effect in PC-3 PCa cells transfected with wild-type AR than DHT and had similar effect in PC-3 cells transfected with mutant AR. The mechanism that adiol activates mutant AR in LNCaP cells did not result from the increased affinity to mutant AR or from AR's association with coactivator ARA70. However, low concentration of adiol induced more AR nuclear translocation than DHT in LNCaP cells and not PC-3 cells transfected with AR. These results indicate that adiol may cause the progression of PCa even after hormone therapy.

Androgen Antagonists↗
PubMed2004

Osteoblasts induce prostate cancer proliferation and PSA expression through interleukin-6-mediated activation of the androgen receptor.

Prostate cancer (CaP) metastases selectively develop in bone as opposed to other sites through unknown mechanisms. Interleukin-6 (IL-6) is considered to contribute to CaP progression and is produced at high levels in osteoblasts. We hypothesized that osteoblast-derived IL-6 in the bone microenvironment contributes to the fertile soil for CaP growth. Accordingly, human CaP cells, LNCaP, C4-2B and VCaP, were treated with conditioned medium (CM) collected from human osteoblast-like HOBIT cells grown in androgen-depleted medium. We found that CM induced proliferation, prostate-specific antigen (PSA) protein and mRNA expression in a dose-dependent manner in these cell lines as determined by ELISA and real-time PCR, respectively. CM also activated the PSA promoter in these cells. Both HOBIT and primary osteoblast (POB) cells produced high levels of IL-6 measured by bioassay. LNCaP, C4-2B and VCaP cells expressed IL-6, but at much lower levels then the HOBIT and POB and they also expressed the IL-6 receptor mRNA, indicating they can respond to IL-6. Anti-IL-6 antibody added to HOBIT or POB CM dose-dependently inhibited the CM-induced cell proliferation and PSA expression in these CaP cell lines. HOBIT CM induced nuclear translocation of the AR and this was inhibited by anti-IL-6 antibody. Additionally, the antiandrogen bicalutamide inhibited HOBIT CM-induced cell proliferation. These results demonstrate that osteoblasts promote CaP growth through IL-6-mediated activation of the AR. Furthermore, these data underscore the importance of cross-talk between tumor and the bone microenvironment in the development of CaP bone metastases.

Androgens↗
PubMed2004

Comparison of two in vivo models for prostate cancer: orthotopic and intratesticular inoculation of LNCaP or PC-3 cells.

BACKGROUND: The critical events in the clinical course of prostate cancer are the occurrence of metastasis and the induction of the hormone-refractory status of the disease. In order to investigate the factors responsible for these events, we need appropriate in vivo models. MATERIALS AND METHODS: Orthotopic and intratesticular models were created by the injection of LNCaP cells or PC-3 cells into the prostate or testis of severe combined immunodeficient mice. RESULTS: LNCaP cells in the intratesticular model showed a higher incidence of tumor formation and lymph node metastasis when compared with those in the orthotopic model, while PC-3 cells were highly tumorigenic and metastastic in both models. A high concentration of androgens might play a role in tumor aggressiveness of LNCaP cells, given that enhanced mRNA expressions of integrin alphaV and vascular endothelial growth factor was induced by dehydrotestosterone administration in vitro. The high expression of metastasis-related genes, including the urokinase plasminogen activator system, metalloproteinases and vascular endothelial growth factor-C, might be attributed to the high metastatic potential in both models. Interestingly, testicular xenografts of LNCaP cells were able to survive on the subcutis back of castrated male mice as well female mice. CONCLUSIONS: Intratesticular models of prostate cancer appear to be suitable for studying the mechanisms of metastasis and for evaluating various treatment strategies.

Animals↗
PubMed2004

A new luciferase reporter gene assay for the detection of androgenic and antiandrogenic effects based on a human prostate specific antigen promoter and PC3/AR human prostate cancer cells.

We developed a new mammalian cell-based luciferase reporter gene assay for androgenic and antiandrogenic activities of chemicals and environmental samples. Environmental samples usually have a complex matrix that may contain the constituents acting as androgen receptor (AR) agonists, AR antagonists or aryl hydrocarbon receptor (AhR) agonists. AhR agonists are known to elicit the antiandrogenic effect through cross-talk between AR and AhR signal transduction pathways. In this study, PC3/AR human prostate carcinoma cells were transiently transfected with a prostate-specific antigen (PSA) promoter-driven luciferase expression plasmid. The cells were treated with a test compound or an environmental sample for 24 h at 37 degrees C and then measured for luciferase activity. The luciferase activity was induced by dihydrotestosterone (DHT) in a concentration-dependent manner in a concentration range from 10 fM to 1 nM. R1881, a synthetic androgen receptor agonist, induced luciferase activity and its inductive effects was additive to that of DHT. The luciferase activity was not induced by cortisol, a glucocorticoid, progesterone, a progestin, and 17beta-estradiol, an estrogen in a concentration range of up to 1 microM. DHT-induced luciferase activity was reduced by bicalutamide and cyproterone acetate, AR antagonists, and also by benzo[a]pyrene, an aryl hydrocarbon receptor agonist, through AhR-mediated pathways. All of these findings indicate that the present assay system correctly responds to AR agonists, AR antagonists and AhR agonist and, therefore, it is a powerful tool for the sensitive and selective screening of chemicals and environmental samples for their androgenic and antiandrogenic activities. We developed the first assay system, in which the expression of luciferase was driven by the promoter of a prostate-specific antigen gene, a typical human androgen-regulated gene.

Androgen Antagonists↗
PubMed2003

Simultaneous determination of androstenediol 3-sulfate and dehydroepiandrosterone sulfate in human serum using isotope diluted liquid chromatography-electrospray ionization-mass spectrometry.

A simple method for simultaneous determination of androstenediol 3-sulfate (Adiol-3S) and dehydroepiandrosterone sulfate (DHEA-S) in human serum using isotope diluted liquid chromatography-electrospray ionization-ion trap-mass spectrometry (LC-ESI-ion trap-MS) was developed. After addition of deuterated internal standards ([2H5]Adiol-3S and [2H4]DHEA-S), human serum (100 microl) was deproteinized with acetonitrile and then applied to a solid-phase extraction cartridge, Oasis HLB. The obtained steroid sulfates fraction was washed with hexane and then analyzed by LC-ESI-MS operated in the negative ion mode. The quantification ranges of Adiol-3S and DHEA-S were 10-400 ng/ml and 0.05-8 microg/ml, respectively. The method does not require the chemical or enzymatic hydrolysis of the conjugates and purification with high-performance liquid chromatography, and shows satisfactory reproducibility and accuracy. The concentrations of these sulfates in the sera of healthy male volunteers (n=14) were 19.2-245.3 mg/ml (Adiol-3S) and 0.175-5.16 microg/ml (DHEA-S), and those of patients with prostate cancer (n=19) were 15.3-182.7 ng/ml (Adiol-3S; four samples, not detectable) and 0.110-2.421 microg/ml (DHEA-S).

Aged↗
PubMed2003

Antiandrogenic activities of diesel exhaust particle extracts in PC3/AR human prostate carcinoma cells.

We collected diesel exhaust particles (DEPs) emitted from three diesel-engine vehicles--a car, a bus, and a truck--in daily use, and prepared DEP extracts (DEPEs), designated as EC, EB, or ET, respectively. The androgenic and antiandrogenic effects of the DEPE samples were examined by a luciferase reporter assay in human prostate carcinoma PC3/AR cells transiently transfected with a prostate specific antigen gene promoter-driven luciferase expression vector pGLPSA5.8. PC3/AR is a subline of human prostate carcinoma PC3 transformed to stably express wild-type human androgen receptor (AR). While DEPE samples did not exhibit any androgenic effect, they exerted antiandrogenic effect, inhibiting dihydrotestosterone (10 pM) -induced luciferase activity by 24 to 52% at an extract concentration of 10 microg/ml. The antiandrogenic effect was greater in the following order: ET > EB > EC. Co-treatment of PC3/AR cells with SKF-525A, a nonselective inhibitor of cytochrome P450 (CYP) enzymes, enhanced the antiandrogenic effect, indicating that the antiandrogenic effect is caused by intact species of DEPE constituents. The antiandrogenic effect of DEPE samples was reversed by alpha-naphthoflavone, an aryl hydrocarbon receptor (AhR) antagonist. The antiandrogenic activity of a DEPE sample correlated with its AhR agonist activity assayed in PC3/AR cells transiently transfected with CYP1A1 gene promoter-driven luciferase expression vector pLUC1A1. Equimolar mixtures of ten polycyclic aromatic hydrocarbons (PAHs) having four or more rings, structures found in the DEPEs, showed significant antiandrogenic effects and AhR agonist activity at concentrations equivalent to those found in DEPE samples. Further, DEPE samples elicited only antiandrogenic effects in recombinant yeast cells, which express beta-galactosidase in response to androgen. A competitive AR binding assay showed that AR-binding constituents exist in DEPE samples, indicating that greater part of AR-binding constituents in DEPEs are AR antagonists. All these findings show that DEPE samples exhibit significant antiandrogenic effect in cell-based transcription assay and that this effect is due in part to the constituents with AhR agonist activity including PAHs and to the constituents with AR antagonist activity.

Adenocarcinoma↗