Concordance of tumor differentiation among brothers with prostate cancer

Background

Genetic factors seem to be of greater importance in prostate cancer than in other forms of cancer. Studies have suggested familial concordance in survival, but the extent to which that is due to tumor characteristics is not known.

Objective

We hypothesized that a brother of an index case with prostate cancer is at particularly increased risk of prostate cancer with the same tumor differentiation as the index case.

Design, setting and participants

We identified 21 930 brothers of index cases with prostate cancer in the Prostate Cancer Data Base Sweden and followed them up for incidence of prostate cancer.

Outcome measurements and statistical analysis

The relative risk of Gleason score–specific prostate cancer in the cohort of brothers was estimated by using the standardized incidence ratio (SIR) stratified by Gleason score of the index case. We estimated 95% confidence intervals (CIs) assuming a Poisson distribution.

Results and limitations

Among brothers of index cases with Gleason score 8–10 cancer, the SIR was 2.53 (95% CI, 1.97–3.21) for a Gleason score 2–6 cancer and 4.00 (95% CI, 2.63–5.82) for a Gleason score 8–10 cancer. SIR for Gleason score 2–6 cancer among brothers decreased with time since the date of the index cases’ diagnoses, whereas the risk of Gleason 8–10 cancer increased over time for brothers of index cases with Gleason 8–10 cancer (p for trend = 0.009).

Conclusions

Brothers of men with high-grade prostate cancer are at particularly increased risk of high-grade prostate cancer. Likewise, there is a concordance of less malignant prostate cancers within families. These findings may have direct clinical relevance for counseling men with a family history of prostate cancer.     

Neuroendocrine differentiation in the progression of prostate cancer

Neuroendocrine (NE) cells originally exist in the normal prostate acini and duct, regulating prostatic growth, differentiation and secretion. Clusters of malignant NE cells are found in most prostate cancer (PCa) cases. NE differentiation (NED) is the basic character of the prostate, either benign or malignant. NE cells hold certain peptide hormones or pro-hormones, which affect the target cells by endocrine, paracrine, autocrine and neuroendocrine transmission in an androgen-independent fashion due to the lack of androgen receptor. NED is accessed by immunohistochemical staining or measurement of serum levels of NE markers. The extent of NED is associated with progression and prognosis of PCa. Chromogranin A (CGA) is the most important NE marker. In metastatic PCa, pretreatment serum CGA levels can be a predictor for progression and survival after endocrine therapy. It is recommended to measure longitudinal change in serum CGA. The NE pathway can also be a therapeutic target.     

Neuroendocrine cell differentiation in the CWR22 human prostate cancer xenograft: association with tumor cell proliferation prior to recurrence

BACKGROUND: Neuroendocrine (NE) cell differentiation is proposed to facilitate prostate cancer (CaP) recurrence following androgen deprivation through secretion by NE cells of growth factors and neuropeptides that support survival and proliferation of CaP cells and vasculature. METHODS: The effect of androgen deprivation on NE differentiation and tumor cell proliferation in the CWR22 model of human CaP was determined by immunohistochemical analysis of the NE cell marker synaptophysin and the cell proliferation marker Ki67. RESULTS: A significant increase in the number of NE cells was observed in CWR22 tumors between 28 and 66 days after castration compared to intact mice, that preceded the increase in tumor cell proliferation that began 70 days after androgen deprivation heralding recurrence. There was a significant positive correlation between the number of tumor-associated NE cells and proliferating CaP cells in tumors from mice after 28-34 days of androgen withdrawal. CONCLUSION: In the CWR22 model, androgen deprivation induces an increase in tumor-associated NE cells prior to increased tumor cell proliferation, with NE cells possibly promoting tumor survival and recurrent disease.     

Hypermethylation of MCAM gene is associated with advanced tumor stage in prostate cancer

BACKGROUND: DNA methylation has emerged as a promising biomarker for prostate cancer detection. In this report, we screened 36 candidate genes generated by a bioinformatic analysis of the human genome, and found that the melanoma cell adhesion molecule (MCAM) was an excellent candidate for cancer-specific methylation in prostate cancer. METHODS: Direct sequencing of bisulfite-treated genomic DNA, conventional methylation-specific PCR (MSP), real-time quantitative methylation-specific PCR, immunohistochemistry, colony formation assay, and statistical analysis. RESULTS: We found that the melanoma cell adhesion molecule (MCAM) gene promoter was specifically methylated in prostate cancer cell lines and primary prostate cancer (PCa) but not in non-neoplastic prostate (BPH) tissues by direct sequencing of bisulfite-treated genomic DNA and conventional methylation-specific PCR (MSP). Further analysis with quantitative MSP showed greater hypermethylation of the MCAM promoter (80%, 70/88) in primary prostate cancer compared to 12.5% (3/24) in BPH. Prostatic intraepithelial neoplasias (PIN), potential precursors of prostate carcinoma, showed an intermediate methylation rate of 23% (7/30). We further observed that MCAM promoter methylation was directly correlated with tumor stage (pT3+pT4) (P = 0.001) and Gleason score (P = 0.018) in primary prostate carcinoma. CONCLUSIONS: Our results suggest that MCAM promoter hypermethylation deserves further attention as a potential diagnostic prostatic DNA marker in human prostate cancer.     

Down-regulation of the human kallikrein gene 5 (KLK5) in prostate cancer tissues

BACKGROUND: Kallikreins are a subgroup of serine proteases with diverse physiological functions. Many kallikrein genes are differentially expressed in various malignancies and prostate specific antigen (PSA; encoded by the KLK3 gene) is the best tumor marker for prostate cancer. Human glandular kallikrein (hK2; encoded by the KLK2 gene) is an emerging tumor marker for prostate cancer. KLK5 is a newly discovered human kallikrein gene which shares a high degree of homology and is located adjacent to KLK2 and KLK3 genes on chromosome 19q13.4. Like KLK2 and KLK3, the KLK5 gene is regulated by steroid hormones in the BT-474 breast cancer cell line. We have previously shown that KLK5 is differentially expressed in ovarian and breast cancer. METHODS: We compared the expression of KLK5 in 29 pairs of histologically confirmed normal and prostate cancer tissues by quantitative RT-PCR using the LightCycler technology. RESULTS: KLK5 expression was significantly lower in cancer tissues compared to their normal counterparts. Lowest levels of expression were found in T3 stage tumors compared with T1 and T2. Also, a significant negative correlation was found between Gleason score and KLK5 expression. CONCLUSIONS: KLK5 should be further studied as a potential new prognostic marker in prostate cancer, whose expression is negatively correlated with cancer aggressiveness.     

Down-regulation of human X-box binding protein 1 (hXBP-1) expression correlates with tumor progression in human prostate cancers

BACKGROUND: In our previous study, the gene encoding the human X-box binding protein 1 (hXBP-1) was isolated as a down-regulated gene in advanced prostate cancers using cDNA-representational difference analysis (RDA). In the present investigation, we characterized alterations of hXBP-1 in prostate cancer specimens. METHODS: Expression patterns of hXBP-1 in a series of human prostate cancers were examined by Northern blotting, mRNA in situ hybridization or immunohistochemistry. Loss of heterozygosity (LOH) analysis using microsatellite markers and gene mutation analysis in the hXBP-1 region were also performed. RESULTS: Expression of hXBP-1 was localized in epithelial and adenocarcinoma cells of the prostate. An inverse correlation between hXBP-1 expression and histological differentiation was found in a series of prostate cancers without hormonal therapy. Majority of refractory cancer cases exhibited weak hXBP-1 expression. No allelic loss or gene mutations were found in the hXBP-1 region and its open reading frame, respectively, in the prostate cancer examined. CONCLUSIONS: These results suggest that reduction of hXBP-1 expression may be a useful marker for prostate adenocarcinoma differentiation and progression.     

9-顺维甲酸对前列腺癌细胞系LNCaP中同源盒基因NKX3.1表达的影响(英文)

目的:研究9-顺维甲酸对前列腺癌细胞系 LNCaP 中同源盒基因 NKX3.1表达的调节作用。方法:采用流式细胞术、反转录 PCR 和 Western Blot 技术检测9-顺维甲酸对 LNCaP 细胞周期及 NKX3.1表达的影响;构建和转染 NKX3.1启动子-报告基因质粒及其缺失突变体,通过报告基因活性测定,鉴定 NKX3.1启动子中受9顺-维甲酸调控的区域。结果:通过转染及报告基因检测,发现9-顺维甲酸在 LNCaP 细胞中可明显提高 NKX3.1启动子的活性:RT-PCR 和 Western Blot 结果显示,9-顺维甲酸可提高 NKX3.1mRNA 和蛋白的表达,并呈剂量依赖性;通过启动子缺失突变分析,发现 NKX3.1基因上游-936至-921区明显受9-顺维甲酸诱导调节;流式细胞术分析细胞周期的结果显示,9-顺维甲酸可阻止 LNCaP 细胞于 G_1期,减少 G_2/M 期细胞。结论:9-顺维甲酸作为诱导分化剂可阻止 LNCaP 细胞于 G_1期,减少细胞有丝分裂,并明显上调前列腺特异的抑癌基因 NKX3.1的表达。     

Validation of molecular targets in prostate cancer

As prostate cancer is not a single disease, it is important to identify the pivotal pathway in the patient being treated. The molecular environment is the site of current oncological research to define new therapeutic targets for hormone-refractory disease, offering the potential to eventually individualize treatment through stratification of pathways. Targets may be validated either phenotypically (e.g. androgen receptor, cadherin) or functionally (e.g. prostate cancer-specific genes). In addition, several other candidates are potentially suitable, while others await discovery. Important initial steps have been made in the search for prostate cancer stem cells; identifying stem cells and the stromal, hormonal, and other signalling molecules that influence their behaviour would have important implications for managing prostate cancer. Although individual therapeutic pathways might be ineffective in a particular molecular environment, combinations of approaches might be capable of producing synergistic effects. A multimodal approach thus might be the best solution. Determining where best to search for a molecular target, and validating whether the target is associated with a sufficiently aggressive malignant process to justify further study is difficult, but the potential benefits are enormous.     

Retinoblastoma gene mutations in primary human prostate cancer

Structural alterations in the entire coding regions (exons 1 to 27) of the retinoblastoma (RB) gene in primary human prostate cancers were investigated, using polymerase chain reaction and single strand conformational polymorphism analysis of RNA. Of 25 samples obtained from patients, four (16.4%) were found to have RB alterations. DNA sequencing of the PCR products revealed point mutations resulting in single amino-acid substitutions of exons 6 and 19 in two cases, and base deletions of exons 8 and 17 in two cases. Two of four cases with RB mutations were moderately differentiated localized tumors and other two with RB mutations were poorly differentiated tumors with metastases. Our results suggest that RB gene mutation is involved in progression steps of prostate carcinogenesis. © 1995 Wiley-Liss, Inc.     

Genistein-induced neuroendocrine differentiation of prostate cancer cells

BACKGROUND: Neuroendocrine (NE) cells are present in normal prostate and their number appears to be increased in advanced prostate cancer (PCA). In this study, we studied the effect of the phytoestrogen, genistein, on NE differentiation of LNCaP cells in vitro. METHODS: Neuroendocrine marker expression of LNCaP cells exposed to genistein was measured by immunohistochemistry, Western blot, and real-time PCR methods. Western blot analysis was used to study cell cycle and signaling pathways induced by genistein treatment. RESULTS: Six days after continuous genistein treatment, the majority of genistein-surviving cancer cells underwent transdifferentiation into a NE-like phenotype overexpressing the NE markers chromogranin A, synaptophysin, serotonin, and beta-III tubulin. This NE differentiation process was associated with upregulation of the cell cycle modulators p21, p27, and p53, and activation of the MAPK and STAT3 pathways. CONCLUSION: Our data indicate that genistein evokes not only apoptosis but also NE transdifferentiation of PCA cells.     

Androgen-deprivation therapy-induced aggressive prostate cancer with neuroendocrine differentiation

Most prostate cancers （PCas） are classified as acinar type （conventional） adenocarcinoma which are composed of tumor cells with luminal differentiation including the expression of androgen receptor （AR） and prostate-specific antigen （PSA）. There are also scattered neuroendocrine （NE） cells in every case of adenocarcinoma. The NE cells are quiesecent, do not express AR or PSA, and their function remains unclear. We have demonstrated that IL8-CXCR2-P53 pathway provides a growth-inhibitory signal and keeps the NE cells in benign prostate and adenocarcinoma quiescent. Interestingly, some patients with a history of adenocarcinoma recur with small cell neuroendocrine carcinoma （SCNC） after hormonal therapy, and such tumors are composed of pure NE cells that are highly proliferative and aggressive, due to P53 mutation and inactivation of the IL8-CXCR2-P53 pathway. The incidence of SCNC will likely increase due to the widespread use of novel drugs that further inhibit AR function or intratumoral androgen synthesis. A phase II trial has demonstrated that platinum-based chemotherapy may be useful for such therapy-induced tumors.     

Progesterone receptor expression in human prostate cancer: correlation with tumor progression

BACKGROUND: The recent discovery of the classical estrogen receptor alpha (ERalpha) in metastatic and recurrent prostatic adenocarcinoma suggests that estrogens are implicated in prostate cancer progression. METHODS: To get more insight into estrogen signaling in prostate cancer tissue, the current study has examined the immunoprofile of the estrogen-inducible progesterone receptor (PR), and evaluated its relation to ERalpha gene expression. RESULTS: In primary tumors, the PR was detectable in 36% of primary Gleason grade 3 (5 of 14 cases), 33% of primary Gleason grade 4 (5 of 15 cases), and in 58% of primary Gleason grade 5 tumors (7 of 12 cases). None of the 41 primary tumors investigated revealed significant PR expression in more than 50% of tumor cells. Conversely, moderate to strong receptor expression was observed in 60% of metastatic lesions (9 of 15 cases), and in 54% of androgen-insensitive tumors (38 of 71 cases). Irrespective of grades and stages, the presence of the PR was invariably associated with high steady state levels of ERalpha mRNA, whereas the ERalpha protein was undetectable by immunohistochemistry (IHC) in a significant number of cases (58 of 97 cases). CONCLUSIONS: The progressive emergence of the PR during tumor progression obviously reflects the ability of metastatic and androgen-insensitive tumors to use estrogens through a ERalpha-mediated pathway. The present data provide a theoretical background for studying the efficiency of antiestrogens and antigestagens in the medical treatment of advanced prostate cancer.