Time Trends in Histological Features of Latent Prostate Cancer in Japan.

PURPOSE: The incidence of prostate cancer is reported to be increasing in Asia, including Japan. Although this trend has been attributed partly to a more Western diet, this assumption may involve variable confounders. Thus, we examined the histological features of contemporary vs historical latent prostate cancer. MATERIALS AND METHODS: Prostate specimens from a consecutive autopsy series (127, present study, 2008 to 2013) were examined. Each prostate gland was fixed and sliced in step sections. The findings were compared to those from another autopsy series (501 subjects, 1983 to 1987) at our institution. RESULTS: The mean age of subjects in the present study was 68.9 years while the mean age was not available from the earlier study. However, the mean age of the 566 entrants in the expanded database (1983 to 1989) was 63.5 years (p=0.0001). Prostate weight was significantly greater in the present study (p <0.0001). Latent prostate cancer was found more frequently in the present study than in the previous study (43.3% and 20.8%, respectively, p <0.0001). No distinct difference was seen in the proportion of tumor grade between the groups. An increasing trend of moderately to poorly differentiated tumors with advancing age was more evident in the present study. Index cancer volume was greater in the present study with 25.5% measuring 500 mm(3) or greater vs only 9.6% of cancers in the previous study (p=0.008). CONCLUSIONS: Chronological changes in the histological characteristics of Japanese latent prostate cancer were noted as it is more prevalent in the contemporary series. Our data may reflect a worldwide trend in increasingly aging societies.

Immunohistochemical ETS-related gene detection in a Japanese prostate cancer cohort: diagnostic use in Japanese prostate cancer patients.

Chromosomal rearrangements that result in high expression levels of the ETS-related gene (ERG) present in approximately 50% of prostate cancer (PCa) patients, making this one of the most common oncogenic alterations in PCa. However, ERG overexpression at the protein level has not been rigorously evaluated in Japanese PCa patients. In this study, we evaluated ERG expression using antibody-based detection in 230 prostate specimens in a Japanese PCa cohort. Overall, we identified 20.1% ERG-positive PCa cases. ERG was not detected in benign glands. The specificity of ERG staining for detecting PCa was almost 100%; all of the ERG-positive samples were also diagnosed as PCa. The expression level of the ERG protein correlated with clinicopathological variables, including grade (P= 0.038), stage (P= 0.005), and metastatic status (P= 0.014). No correlation was observed with age (P= 0.196) or with preoperative prostate-specific antigen level (P= 0.322). Although the frequency of ERG-positive cases in Japanese PCa patients (20.1%) was lower than that reported in a PCa cohort in Western countries (approximately 50%), our study demonstrates that the clinical utility of ERG detection at the protein level can serve as an ancillary tool for diagnosing PCa in the Japanese population.

Sertoli-Leydig cell tumor of the testis in a Sprague-Dawley rat.

A rare intratubular gonadal stromal tumor was present in the testis of a 7-wk-old male Sprague-Dawley rat. The tumor comprised an intratubular mixture of 2 types of tumor cells with intercellular junctions: the predominant tumor cells were consistent with a Sertoli cell origin, and cells comprising the minor population were situated on basolateral side of the tubuli, consistent with a Leydig cell origin. The neoplastic Sertoli cells had large pleomorphic nuclei and clear cytoplasm with many tubulovesicular cristae and free ribosomes, whereas the neoplastic Leydig cells showed relatively small pleomorphic nuclei, dark cytoplasm with rich smooth endoplasmic reticulum, numerous mitochondria, and lipid droplets. Occasionally, a few transitional type neoplastic cells were observed. The presence of a thick or multilayered basement membrane was confirmed except in tumor-infiltrative lesions. The present case was considered to be a testicular mixed tubular Sertoli-Leydig cell tumor in a Sprague-Dawley rat.

Prediction of clinically insignificant prostate cancer by detection of allelic imbalance at 6q, 8p and 13q.

The criterion tumor volume (TV) for clinically insignificant prostate cancer has been reported, but it differs from study to study: some have reported TV < 200 mm(3); others, < 500 mm(3). The aim of the present study was to distinguish clinically insignificant cancers from significant ones using molecular biological methods. A total of 184 microscopic cancers (MC) defined as limited within a 3 mm circle and 82 main tumor (MT) nodules were selected. Thirteen microsatellite loci at 6q22, 8p23.2-23, 13q14 and 13q33 were evaluated for loss of heterozygosity (LOH). MT were subgrouped as TV > or = 500 mm(3) or < 500 mm(3); TV > or = 200 mm(3) or < 200 mm(3); and TV < 200 mm(3), 200 mm(3) < or = TV < 500 mm(3) or TV > or = 500 mm(3); and frequencies of LOH were compared between these three groups. Frequencies of LOH at 6q16-21, 6q22, 8p23.1, 8p23.2, 13q14 were significantly lower in MC (1.0%, 2.7%, 1.9%, 1.1% and 5.4%) than in MT (30.9%, 40.4%, 12%, 8.7% and 20.6%), but no significant differences in LOH frequency were found within each of the three TV groups, between each cut-off. When insignificant tumor is defined as TV < 200 mm(3) or < 500 mm(3), it should include tumors with malignant potential equivalent to larger tumors. It is suggested that in order to identify insignificant tumor within a strict safety range, TV should be set lower.

Localization of Ang-1, -2, Tie-2, and VEGF expression at endothelial-pericyte interdigitation in rat angiogenesis.

Endothelial cells and pericytes play critical role in angiogenesis, which is controlled, in part, by the angiopoietin (Ang)/Tie-2 system and vascular endothelial growth factor (VEGF). Here, we investigated Ang, Tie-2, and VEGF expression within endothelial cells and pericyte interdigitations (EPI), which consist of cytoplasmic projections of pericytes and corresponding endothelial indentations. After subcutaneous implantation of a thermoreversible gelation polymer disc in rats, the capillary density was low on day 5, increased to a peak on day 7, and then decreased on days 10-20. A small number of EPI were observed on day 5, then increased sharply to a peak on day 10, but had decreased on day 20. Light and electron microscopy immunohistochemical and RNA in situ hybridization analyses revealed that Tie-2 localized at endothelial cells, and Ang-2 localized at endothelial cells and pericytes, while Ang-1 and VEGF localized at pericytes, and Ang-1 was most intensely observed at EPI of pericytes. Conventional quantitative RT-PCR and Western blot analyses revealed that the level of Ang-1 was low on days 5-7, then increased on days 10-20, while the level of VEGF was high on days 5-10, but had decreased on day 20. The level of Ang-2 remained high and Tie-2 remained at the level of the control on days 5-20. The present study showed that the angiogenic phase might be initiated by increases in Ang-2 and VEGF, while the microvessel maturation phase might be initiated by a relative increase in Ang-1 and a decrease in VEGF. Moreover, EPI might serve as a pathway for the Ang-1/Tie-2 system, with VEGF promoting pericyte recruitment for microvascular integrity.

Allelotyping analysis at chromosome 13q of high-grade prostatic intraepithelial neoplasia and clinically insignificant and significant prostate cancers.

BACKGROUND: Loss of heterozygosity (LOH) at 13q is one of the most common chromosomal alterations in high-stage prostate cancer, yet little is known about genetic changes in earlier-stage prostate cancer. METHODS: We used five microsatellite markers at 13q14, 21, and 33 to compare LOH frequencies in 51 lesions of high-grade prostatic intraepithelial neoplasia (HGPIN), 21 cases of incidental prostate cancers (IPCs), 31 cases of latent prostate cancers (LPCs), and 102 cases of clinical prostate cancers (CPCs). RESULTS: The frequency of LOH at 13q with at least 1 marker was 0%, 38%, 56%, and 49% in HGPIN, IPCs, LPCs, and CPCs, respectively. No statistically significant difference was found between the types of prostate cancer. Allelic loss at 13q14 was significantly more frequent in pT4 tumors than in earlier-stage tumors (P=0.011). CONCLUSIONS: Allelic loss at 13q is not only an important event in the metastasis of prostate cancer, but also associated with the initiation of the tumor.

Prenatal 3,3',4,4',5-pentachlorobiphenyl exposure modulates induction of rat hepatic CYP 1A1, 1B1, and AhR by 7,12-dimethylbenz[a]anthracene.

We previously reported the finding that prenatal exposure to a relatively low dose of PCB126 increases the rate of DMBA-induced rat mammary carcinoma, while a high dose decreased it. One of the most important factors determining the sensitivity to mammary carcinogenesis is the metabolic stage at administration of the carcinogenic agent. DMBA is a procarcinogen that recruits the host metabolism to yield its ultimate carcinogenic form, and CYP1A1 and CYP1B1 (CYP1) conduct this metabolism. We investigated the hepatic expression of CYP1 and AhR following oral administration of DMBA (100 mg/kg b.w.) (i.g.) to 50-day-old female Sprague-Dawley rats whose dams had been treated (i.g.) with 2.5 ng, 250 ng, 7.5 microg of PCB126/kg or the vehicle on days 13 to 19 post-conception. Real-time quantitative RT-PCR analysis revealed that the prenatal exposure to a relatively low dose of PCB126 (the 250 ng group) prolonged the higher expression of CYP1A1, CYP1B1, and AhR mRNA, while prenatal exposure to a high dose of PCB126 (the 7.5 microg group) prolonged the higher expression of CYP1A1 and AhR mRNA. Western blotting and immunohistochemical analyses were consistent with mRNAs changes. Because DMBA oxidation produces a highly mutagenic metabolite and is finally catalyzed by CYP1B1, a relatively low PCB126 dose might produce the biological character to potentially increase the risk of DMBA-induced mammary carcinoma.

The possibility of 'de novo' cancer in the prostate.

BACKGROUND: To investigate the possibility of 'de novo' prostate cancer by analyzing the relationship between high grade prostatic intraepithelial neoplasia (HGPIN) and latent prostate cancer. MATERIALS AND METHODS: Latent prostate cancers found at autopsy were examined and 55 cancer foci with a poorly (Gleason grade 4 and 5) or moderately (Gleason grade 3) differentiated component were selected. The 55 foci were separated into two groups: (i) foci with either a poorly or moderately differentiated component only (single differentiation group, SDG); and (ii) mixed foci with two or more types of differentiation components (mixed differentiation group, MDG). High grade intraepithelial neoplasia was defined as positive if it was observed within 2 mm from the edge of the cancer focus and the relationship between HGPIN and the two groups was investigated. RESULTS: The MDG had 39 cancer foci (71.0%) and there were 16 in the SDG (29.0%). There were 31 foci that were small-volume cancers (<0.2 mL). In the MDG, 13 small-volume cancer foci were HGPIN positive, but in the SDG, none of the small-volume cancers were HGPIN positive. CONCLUSIONS: Small-volume cancer foci without HGPIN in the SDG may be candidates for de novo prostate cancers.

CYP1 and AhR expression in 7,12-dimethylbenz[a]anthracene-induced mammary carcinoma of rats prenatally exposed to 3,3',4,4',5-pentachlorobiphenyl.

We previously reported the finding that prenatal exposure to a relatively low dose of 3,3',4,4',5-pentachlorobiphenyl (PCB126) acted as an enhancing agent for 17-beta-estradiol (E2)-dependent 7,12-dimethylbenz[a]anthracene (DMBA)-induced rat mammary carcinoma, while a high dose decreased it. E2 is a known risk factor for mammary carcinoma, and CYP1A1 and 1B1 (CYP1) are the major enzymes catalyzing 2- and 4-hydroxylation of E2, respectively. We investigated the induction of CYP1 and aryl hydrocarbon receptor (AhR) in DMBA-induced mammary carcinoma using female Sprague-Dawley rats whose dams had been treated (i.g.) with 2.5 ng, 250 ng, 7.5 microg of PCB126/kg or the vehicle on days 13-19 post-conception. Immunohistochemical analysis revealed that the mammary carcinoma of the 250 ng group showed a significantly higher number of nuclei expressing estrogen receptor alpha (ER) and proliferating cell nuclear antigen (PCNA) compared to those of the other groups. Quantitative real-time RT-PCR analysis revealed that the 7.5 microg group showed a significantly higher level of CYP1A1 mRNA, and that the 250 ng group showed significantly higher levels of CYP1B1 mRNA. The level of AhR mRNA was significantly higher in both the 7.5 microg and 250 ng groups. Western blotting analysis was consistent with mRNA changes. It has been revealed that CYP1B1 catalyzes a step in the formation of 4-hydroxylated E2 metabolites, which show quite high mammary carcinogenicity. This study indicates that the enhancement of DMBA-induced mammary carcinogenicity in a relatively low PCB126 dose group might partially involve the higher expression of CYP1B1 and AhR in these carcinomas.

Ser217Leu polymorphism of the HPC2/ELAC2 gene associated with prostatic cancer risk in Japanese men.

The HPC2/ELAC2 gene may be associated with hereditary/familial prostate cancer (PCa). Two common missense variants (Ser217Leu and Ala541Thr) have been reported in the gene. We performed mutational, allelotyping and expression analyses and a molecular epidemiological study to clarify the relations between this gene and prostatic diseases, including PCa and benign prostatic hyperplasia (BPH) in Japanese men. We screened for mutations in 109 patients with PCa including 11 patients from 1 hereditary and 9 familial PCa. Loss of heterozygosity and expression were analyzed. An epidemiological study was done in sporadic PCa (n=98) and BPH (n=143) using 1 novel (Ser627Leu) and 2 previously described polymorphisms of the HPC2/ELAC2 gene. Somatic or germline mutations were not confirmed in any cases of PCa. Loss of heterozygosity at 2 microsatellites, D17S1289 and D17S520, was detected in 1 of 38 and 1 of 35 cases, respectively. Expression analysis revealed decreased or absent mRNA expression in 6 of 38 tumors. Epidemiologic analysis showed that a Leu allele at codon 217 was significantly more frequent in patients with PCa than in controls (10.2% vs. 3.5%, odds ratio = 3.11; 95% confidence interval, 1.22-7.90). At codon 541, all patients with PCa or BPH and all control subjects had the Ala/Ala genotype. At codon 627, the incidence of the Leu variant was slightly, but not significantly, higher in patients with BPH than in controls (7.0% vs. 2.8%, odds ratio = 2.59, 95% confidence interval, 0.94-7.13, not statistically significant). We concluded that germline/somatic mutations of HPC2/ELAC2 are uncommon in PCa. Similarly, allelic imbalances at the gene locus and changes in expression are rare. Although no difference in allele frequency at Ser217Leu between patients with PCa and controls has been reported in a Western population, this polymorphism is a potential indicator of PCa risk in Japanese men and it should be examined in other ethnic groups.

Accuracy of gleason grading by practicing pathologists and the impact of education on improving agreement.

The aims of this study were to evaluate the accuracy of Gleason grading for prostatic adenocarcinoma among practicing pathologists in Japan and to determine the influence of education on this accuracy. Using a case-oriented approach, 16 hematoxylin and eosin-;stained glass slides with consensus scores established by 4 urologic pathologists were reviewed by 91 pathologists, divided into 2 groups. In group A, average agreements with consensus scores before and after an educational lecture were 55.7% (n = 17) and 68.4% (n = 25), and average kappa values were 0.43 and 0.67, respectively. Twelve pathologists reviewed slides twice in a different order, with average agreements of 59.5% and 77.6%, and average kappa values of 0.48 and 0.69 before and after the lecture, yielding a statistically significant improvement. In group B, the average agreement before providing an atlas with a tutorial was 61.3% (n = 61), and the kappa value was 0.44. In the second round, the average agreement was 74.5% (n = 39), and the kappa value was 0.68. Among 39 pathologists who reviewed slides twice, the average agreement in the first round was 58.8%, and the kappa value was 0.42. Improvement of both the average agreement and the kappa value were statistically significant. The average improvement in kappa values among participants who reviewed slides twice was 0.22 in group A and 0.27 in group B, a difference that is not statistically significant. Combining both groups, the incidence of concordant scores for 16 cases rose from 58.9% to 75.4%, an average increase of 16.5%. The undergrading of score 5-7 lesions was significantly reduced, from 36.3% to 14.2%. With respect to demographic factors, pathologists signing out more than 5000 cases per year showed a better agreement than those with more than 1000 cases per year (48.9% versus 78.8%; P = 0.031). These results indicate that the general agreement of Gleason scores among practicing pathologists in Japan was comparable with those in the Western countries as reported in the literature. Although this requires further improvement, both the lecture and the printed material had a similar influence on the degree of improvement.

Estrous cyclicity and ovarian follicles in female rats after prenatal exposure to 3,3',4,4',5-pentachlorobiphenyl.

Alterations of estrous cyclicity and ovarian follicles following prenatal exposure to PCB126 were examined. Female SD rats were given (i.g.) 25 pg, 2.5, 250 ng and 7.5 microg of PCB126/kg or the vehicle on days 13-19 postconception. Vaginal opening (VO) in the 250 ng and 7.5 microg offspring was significantly delayed. All groups showed irregular estrous cyclicity following VO, but it became normal after a few days. However, the start of normal estrous cyclicity following VO in the 2.5, 250 ng and 7.5 microg groups was significantly delayed. At 30 and 50 days old, the 2.5, 250 ng and 7.5 microg groups showed significantly fewer antral follicles and a higher number of atretic follicles. The 7.5 microg group at 50 days old revealed significantly fewer corpus luteums. In 50-day-old offspring, the 2.5, 250 ng and 7.5 microg groups showed a significant reduction in serum 17beta-estradiol and progesterone levels and significantly higher levels of PCB126 in the fatty tissue compared with the vehicle group. Thus, while the prenatal dose of PCB126 used in this study did not induce malformation of the external genitalia or persistent ovarian disruption, disruption of ovarian function at puberty was found in the 2.5 ng group of pups born to dams exposed to 17.5 ng/kg PCB126. The present study suggests that PCB126, at least in part, exerted direct effects on the ovary as shown by the disruption of estrous cyclicity.

Mammary gland differentiation in female rats after prenatal exposure to 3,3',4,4',5-pentachlorobiphenyl.

Recently we reported finding that prenatal exposure to a relatively low dose of 3,3',4,4',5-pentachlorobiphenyl (PCB126) increases the rate of 7,12-dimethylbenz(a)anthracene (DMBA)-induced rat mammary carcinoma, while a high dose decreases it. One of the most important factors determining sensitivity of the mammary gland to neoplastic stimuli is its stage of differentiation at the time of exposure to the carcinogenic agent. Hence, to verify a biphasic dose-response relationship (enhancement of carcinogenesis at low dose, and inhibition at high dose), we investigated the effects of prenatal exposure to PCB126 on mammary gland differentiation. Female SD rats were injected (i.g.) with 25 pg, 2.5 ng, 250 ng, 7.5 microg of PCB126/kg, or the vehicle, on days 13-19 postconception. In 50-day-old offspring, regardless of the day of exposure to DMBA, only the 7.5 microg group showed statistically significant high levels of PCB126 in the fatty tissue of their mammary glands. Fifty-day-old female offspring of the 250 ng group showed apparent inhibition of the normal differentiation of terminal end buds (TEB) to alveolar buds and lobules (ABL), while those of the 7.5 microg group showed mammary gland hypoplasia. Expression levels of the estrogen receptor-alpha (ER) in TEBs and the ER mRNA in mammary glands were higher in the 7.5 microg, 250 ng, 2.5 ng groups. Proliferating cell nuclear antigen (PCNA) expression in TEBs of 50-day-old rats was statistically significantly higher in the 250 ng group and lower in the 7.5 microg group. In the developing mammary gland, TEBs are considered the most susceptible to mammary carcinogenesis, while ABLs are relatively protected from mammary carcinogenesis. Thus, prenatal exposure to a relatively low dose of PCB126 induced an alteration of mammary gland differentiation that might potentially increase the risk of DMBA-induced mammary carcinoma.