Germline and somatic DNA repair gene alterations in prostate cancer.

BACKGROUND: Emerging evidence has suggested that DNA repair gene alterations may be important in prostate cancer pathogenesis. In the current study, the authors sought to characterize alterations in DNA repair pathway genes in both primary and metastatic prostate tumors with attention to tissue distribution as well as specific genomic alterations. METHODS: The authors studied the distribution and type of alterations in 24 genes that are considered important for DNA repair in 944 prostate cancers harvested from localized and metastatic tumors. Tumor DNA underwent hybrid capture for all coding exons of 287 or 395 cancer-related genes plus select introns from 19 or 31 genes frequently rearranged in cancer. Captured libraries were sequenced to a median exon coverage depth of >×500. Specific genomic alterations were characterized and the frequencies of mutations by tissue site (prostate vs metastases) were compared using logistic regression. RESULTS: A total of 152 patients from the cohort of 944 men (16%) harbored a germline or somatic mutation in ≥1 DNA repair genes. The most frequently mutated genes were BRCA2 (11.4%) and ATM (5.8%), followed by MSH6 (2.5%) and MSH2 (2.1%). Mutations were identified in approximately 20.1% of primary prostate tumors compared with 18.8% of bone metastases. When stratified by tissue site, the highest rates of DNA repair mutations were found in solid organ metastases, including brain and visceral metastases, compared with prostate. CONCLUSIONS: DNA repair gene mutations are more common in metastatic than localized prostate tumors. Visceral and other solid organ metastases appear enriched for these mutations compared with localized tumors or bone and lymph node metastases.

Bioengineered Noncoding RNAs Selectively Change Cellular miRNome Profiles for Cancer Therapy.

Noncoding RNAs (ncRNAs) produced in live cells may better reflect intracellular ncRNAs for research and therapy. Attempts were made to produce biologic ncRNAs, but at low yield or success rate. Here we first report a new ncRNA bioengineering technology using more stable ncRNA carrier (nCAR) containing a pre-miR-34a derivative identified by rational design and experimental validation. This approach offered a remarkable higher level expression (40%-80% of total RNAs) of recombinant ncRNAs in bacteria and gave an 80% success rate (33 of 42 ncRNAs). New FPLC and spin-column based methods were also developed for large- and small-scale purification of milligrams and micrograms of recombinant ncRNAs from half liter and milliliters of bacterial culture, respectively. We then used two bioengineered nCAR/miRNAs to demonstrate the selective release of target miRNAs into human cells, which were revealed to be Dicer dependent (miR-34a-5p) or independent (miR-124a-3p), and subsequent changes of miRNome and transcriptome profiles. miRNA enrichment analyses of altered transcriptome confirmed the specificity of nCAR/miRNAs in target gene regulation. Furthermore, nCAR assembled miR-34a-5p and miR-124-3p were active in suppressing human lung carcinoma cell proliferation through modulation of target gene expression (e.g., cMET and CDK6 for miR-34a-5p; STAT3 and ABCC4 for miR-124-3p). In addition, bioengineered miRNA molecules were effective in controlling metastatic lung xenograft progression, as demonstrated by live animal and ex vivo lung tissue bioluminescent imaging as well as histopathological examination. This novel ncRNA bioengineering platform can be easily adapted to produce various ncRNA molecules, and biologic ncRNAs hold the promise as new cancer therapeutics.

Image-guided photo-therapeutic nanoporphyrin synergized HSP90 inhibitor in patient-derived xenograft bladder cancer model.

Photodynamic therapy is a promising and effective non-invasive therapeutic approach for the treatment of bladder cancers. Therapies targeting HSP90 have the advantage of tumor cell selectivity and have shown great preclinical efficacy. In this study, we evaluated a novel multifunctional nanoporphyrin platform loaded with an HSP90 inhibitor 17AAG (NP-AAG) for use as a multi-modality therapy against bladder cancer. NP-AAG was efficiently accumulated and retained at bladder cancer patient-derived xenograft (PDX) over 7 days. PDX tumors could be synergistically eradicated with a single intravenous injection of NP-AAG followed by multiple light treatments within 7 days. NP-AAG mediated treatment could not only specifically deliver 17AAG and produce heat and reactive oxygen species, but also more effectively inhibit essential bladder cancer essential signaling molecules like Akt, Src, and Erk, as well as HIF-1α induced by photo-therapy. This multifunctional nanoplatform has high clinical relevance and could dramatically improve management for bladder cancers with minimal toxicity.

The role of EGFR family inhibitors in muscle invasive bladder cancer: a review of clinical data and molecular evidence.

PURPOSE: Conventional platinum based chemotherapy for advanced urothelial carcinoma is plagued by common resistance to this regimen. Several studies implicate the EGFR family of RTKs in urothelial carcinoma progression and chemoresistance. Many groups have investigated the effects of inhibitors of this family in patients with urothelial carcinoma. This review focuses on the underlying molecular pathways that lead to urothelial carcinoma resistance to EGFR family inhibitors. MATERIALS AND METHODS: We performed a PubMed® search for peer reviewed literature on bladder cancer development, EGFR family expression, clinical trials of EGFR family inhibitors and molecular bypass pathways. Research articles deemed to be relevant were examined and a summary of original data was created. Meta-analysis of expression profiles was also performed for each EGFR family member based on data sets accessible via Oncomine®. RESULTS: Many clinical trials using inhibitors of EGFR family RTKs have been done or are under way. Those that have concluded with results published to date do not show an added benefit over standard of care chemotherapy in an adjuvant or second line setting. However, a neoadjuvant study using erlotinib before radical cystectomy demonstrated promising results. CONCLUSIONS: Clinical and preclinical studies show that for reasons not currently clear prior treatment with chemotherapeutic agents rendered patients with urothelial carcinoma with muscle invasive bladder cancer resistant to EGFR family inhibitors as well. However, EGFR family inhibitors may be of use in patients with no prior chemotherapy in whom EGFR or ERBB2 is over expressed.

No improvement noted in overall or cause-specific survival for men presenting with metastatic prostate cancer over a 20-year period.

BACKGROUND: Prostate cancer mortality in the United States has declined by nearly 40% over the last 25 years. However, to the authors' knowledge, the contribution of prostate-specific antigen (PSA) screening for the early detection of prostate cancer remains unclear and controversial. In the current study, the authors attempted to determine whether improvements in survival over time among patients with metastatic prostate cancer have contributed to the decline in mortality. METHODS: Men aged ≥ 45 years who presented with de novo metastatic prostate cancer from 1988 to 2009 were identified within the California Cancer Registry. Overall survival and disease-specific survival were estimated using the Kaplan-Meier method. A multivariate analysis with Cox proportional hazards modeling was performed to adjust for different distributions of variables between groups. RESULTS: A total of 19,336 men presented with de novo metastatic prostate cancer during the study period. On multivariate analysis, overall survival was found to be better for men diagnosed from 1988 through 1992 and 1993 through 1998 than for men diagnosed in the most recent era (hazards ratio, 0.78; 95% confidence interval, 0.72-0.85 [P < .001] and HR, 0.79; 95% confidence interval, 0.74-0.86 [P < .001]). There was no improvement in disease-specific survival observed when comparing the most contemporary men (those diagnosed between 2004 and 2009) with those diagnosed between 1988 and 1997. CONCLUSIONS: In this analysis of men presenting with de novo metastatic prostate cancer, no consistent improvement in overall or disease-specific survival could be demonstrated over time. These data suggest that improvements in survival for patients with advanced disease have not contributed substantially to the observed drop in prostate cancer mortality over the PSA era and that stage migration secondary to PSA screening plays a more prominent role.

Functional p53 determines docetaxel sensitivity in prostate cancer cells.

BACKGROUND: Docetaxel is the first line treatment for castration resistant prostate cancer (CRPC). However, docetaxel resistance rapidly develops. Identifying the critical mechanisms giving rise to docetaxel resistance is the major challenge in advanced prostate cancer. METHODS: The effects of docetaxel on human DU145, PC3, LNCaP, and C4-2 prostate cancer cells were examined in cell culture, and p53 expression were analyzed by Western blot analysis. The potential role of p53 in docetaxel sensitivity in prostate cancer cells was tested by either p53 silencing using shRNA or p53 overexpression by introducing wild-type p53. RESULTS: We found that DU145 (mutant p53) and PC3 (p53 null) cells were less sensitive than LNCaP and C4-2 cells expressing functional p53 in response to docetaxel. Docetaxel treatment induces considerably higher apoptosis in LNCaP and C4-2 cells than in DU145 and PC3 cells in a dose dependent manner. Docetaxel increases the levels of ser15 phosphorylation of p53 in a dose dependent manner in both LNCaP and C4-2 cells, while has no effect on the levels of ser15 phosphorylation of p53 in DU145 cells. These results suggest that p53 phosphorylation is associated with docetaxel sensitivity in prostate cancer cells. To further confirm whether p53 activation can induce cell sensitivity to docetaxel treatment, we used p53 shRNA to knock down p53 expression in C4-2 cells and determined the cells response to docetaxel treatment. Knockdown of p53 significantly down regulated p53 phosphorylation and blocked docetaxel induced apoptotic cell death compared to the vector control. To further confirm this observation, we established a stable knock out p53 in C4-2 cells. Down regulation of p53 in the stable p53 knock out C4-2 cells significantly inhibited docetaxel induced apoptotic cell death. We also used wild-type (WT) p53 to over express p53 in DU145 cells, and found that expression of WT-p53 in DU145 cells increased their sensitivity to docetaxel. CONCLUSIONS: These results demonstrate that docetaxel induces p53 phosphorylation and that p53 status is a crucial determinant of docetaxel sensitivity in prostate cancer cells.

MiR-34a chemosensitizes bladder cancer cells to cisplatin treatment regardless of p53-Rb pathway status.

MiR-34a is a downstream effector of p53 that has been shown to target several molecules associated with cell cycle and cell survival pathways. As alterations in these pathways are frequent in muscle invasive transitional cell carcinoma of the bladder (MI-TCC), for example mutation or loss of p53 and Rb, the goal of this study was to determine whether manipulation of miR-34a expression levels could abrogate the effect of these alterations and sensitize bladder cancer cells to chemotherapy. We demonstrate that transfection of T24, TCCSUP and 5637 with pre-miR-34a followed by cisplatin treatment results in a dramatic reduction in clonogenic potential and induction of senescence compared to treatment with cisplatin alone. Molecular analyses identified Cdk6 and sirtuin (SIRT)-1 as being targeted by miR-34a in MI-TCC cells, however, inhibition of Cdk6 and SIRT-1 was not as effective as pre-miR-34a in mediating chemosensitization. Analysis of 27 preneoadjuvant chemotherapy patient samples revealed many of the patients who subsequently did not respond to treatment (based on surgical resection postchemotherapy and 5-year survival data) express lower levels of miR-34a, however, a statistically significant difference between the responder and nonresponder groups was not observed (p = 0.1174). Analysis of eight sets of pre- and postneoadjuvant chemotherapy patient samples determined miR-34a expression increased postchemotherapy in only two of the eight patients. The combined data indicate that elevation of miR-34a expression levels before chemotherapy would be of benefit to MI-TCC patients, particularly in a setting of low miR-34a expression.

The phosphotyrosine-independent interaction of DLC-1 and the SH2 domain of cten regulates focal adhesion localization and growth suppression activity of DLC-1.

The tensin family member cten (C-terminal tensin like) is an Src homology 2 (SH2) and phosphotyrosine binding domain-containing focal adhesion molecule that may function as a tumor suppressor. However, the mechanism has not been well established. We report that cten binds to another tumor suppressor, deleted in liver cancer 1 (DLC-1), and the SH2 domain of cten is responsible for the interaction. Unexpectedly, the interaction between DLC-1 and the cten SH2 domain is independent of tyrosine phosphorylation of DLC-1. By site-directed mutagenesis, we have identified several amino acid residues on cten and DLC-1 that are essential for this interaction. Mutations on DLC-1 perturb the interaction with cten and disrupt the focal adhesion localization of DLC-1. Furthermore, these DLC-1 mutants have lost their tumor suppression activities. When these DLC-1 mutants were fused to a focal adhesion targeting sequence, their tumor suppression activities were significantly restored. These results provide a novel mechanism whereby the SH2 domain of cten-mediated focal adhesion localization of DLC-1 plays an essential role in its tumor suppression activity.

Secondary malignancies among nonseminomatous germ cell tumor cancer survivors.

BACKGROUND: Men on active surveillance for clinical stage I nonseminomatous germ cell tumor (NSGCT) undergo frequent computed tomography imaging to avoid delayed detection of disease. Irradiation from frequent imaging and chemotherapy upon progression may place patients at increased risk of a second malignancy. In this study, the authors sought to identify such an increased risk among men who chose initial surveillance for NSGCT. METHODS: The authors utilized data from the Surveillance, Epidemiology and End Results Program and stratified the cohort based on whether they underwent retroperitoneal lymph node dissection (RPLND). A propensity-score model was used to adjust for covariates, and a competing-risks regression analysis was performed to estimate cumulative incidence rates of second malignancy. Incidence risk ratios were predicted by using the cumulative incidence rates per 10,000 patients. RESULTS: There was no statistically significant increase in the incidence of a secondary malignancy for the entire cohort of testicular cancer survivors. However, when the analysis was restricted to patients with clinical stage I NSGCT, nonsurgical management only in those aged >45 years was an independent predictor of developing a second malignancy. For every 10,000 patients with stage I NSGCT who chose to forego RPLND, an absolute excess incidence of 22, 52, and 73 secondary malignancies would be diagnosed at 5 years, 10 years, and 15 years, respectively. CONCLUSIONS: The current results indicated that patients aged >45 years who forego RPLND for T1 or T2 clinical stage I NSGCT are more likely to develop a second malignancy than those who do undergo RPLND. Nonsurgical management of NSGCT may be associated with more long-term health risks than primary RPLND.

Effects of a high dose, aglycone-rich soy extract on prostate-specific antigen and serum isoflavone concentrations in men with localized prostate cancer.

The efficacy and safety of consuming high-dose isoflavone supplements for prostate cancer is not clear. A double-blind, placebo controlled, randomized trial was conducted in 53 men with prostate cancer enrolled in an active surveillance program. The treatment group consumed a supplement containing 450 mg genistein, 300 mg daidzein, and other isoflavones daily for 6 mo. Prostate-specific antigen (PSA) was measured in both groups at baseline, 3 mo, and 6 mo, and serum concentrations of genistein, daidzein, and equol were assessed at baseline and 6 mo in the treatment group. Following the completion of the 6-mo double-blind study, men were enrolled in a 6-mo open label trial with the same isoflavone-rich supplement, and PSA was measured at 3 and 6 mo. PSA concentrations did not change in either group after 6 mo or after 12 mo when the open-label study was included. The 6 mo serum concentrations of genistein and daidzein (39.85 and 45.59 µmol/l, respectively) were significantly greater than baseline values and substantially higher than levels previously reported in other studies. Equol levels did not change. Although high amounts of aglycone isoflavones may result in significantly elevated serum concentrations of genistein and daidzein, these dietary supplements alone did not lower PSA levels in men with low-volume prostate cancer.

The role of surveillance in the treatment of patients with muscle-invasive bladder cancer after chemotherapy.

OBJECTIVE: To determine the survival of patients at our institution who were clinically tumour-free (cT0) on re-staging transurethral resection (TUR) after treatment with chemotherapy for muscle-invasive bladder cancer. PATIENTS AND METHODS: In all, 55 patients with muscle-invasive, organ-confined transitional cell carcinoma of the bladder were treated with TUR followed by systemic chemotherapy, over a 10-year period. Patients were separated into two groups, those who were clinically T0 and those who showed persistent disease (>cT0) on re-biopsy after chemotherapy. Overall and disease-specific survival rates were calculated for the two groups. The cT0 group was further followed for tumour recurrence and clinical outcomes. RESULTS: Thirty-one patients (56%) were clinically T0 on TUR after chemotherapy; of these patients, 22 (71%) either died from other causes (with no disease recurrence) or are alive and with no evidence of disease at a mean follow-up of 53 months. Twenty of the 31 patients (65%) have retained their bladder with no evidence of cancer recurrence at a mean follow-up of 46 months. Disease-free status (cT0) at the time of TUR after chemotherapy was associated with significantly higher overall and cancer-specific survival (hazard ratio 3.40, P = 0.003; and 8.63, P = 0.001, respectively). CONCLUSION: Previous studies suggest that surveillance can be a reasonable option for patients with muscle-invasive transitional cell carcinoma of the bladder who show no evidence of disease on TUR after chemotherapy. Patients with persistent bladder cancer on re-biopsy after chemotherapy tend to fare poorly even with immediate cystectomy.

An androgen-regulated miRNA suppresses Bak1 expression and induces androgen-independent growth of prostate cancer cells.

Although prostate cancer (CaP) is the most frequently diagnosed malignant tumor and the second leading cause of cancer deaths in American men, the mechanisms explaining the development and progression of CaP remain largely unknown. Recent studies have shown that some aberrantly expressed microRNAs (miRNAs) are involved in tumorigenesis. Although aberrant expression of certain miRNAs has been discovered in CaP, their function in this disease has not yet been defined. In this study, we found differential expression of miR-125b in androgen-dependent and independent CaP cells, as well as in benign and malignant prostate tissues. Furthermore, androgen signaling was able to up-regulate the expression of miR-125b. In addition, transfection of synthetic miR-125b stimulated androgen-independent growth of CaP cells and down-regulated the expression of Bak1. Our results suggest that miR-125b acts as an oncogene, contributing to the pathogenesis of CaP.

Impairment of the DNA repair and growth arrest pathways by p53R2 silencing enhances DNA damage-induced apoptosis in a p53-dependent manner in prostate cancer cells.

p53R2 is a p53-inducible ribonucleotide reductase that contributes to DNA repair by supplying deoxynucleotide triphosphate pools in response to DNA damage. In this study, we found that p53R2 was overexpressed in prostate tumor cell lines compared with immortalized prostatic epithelial cells and that the protein was induced upon DNA damage. We investigated the effects of p53R2 silencing on DNA damage in LNCaP cells (wild-type p53). Silencing p53R2 potentiated the apoptotic effects of ionizing radiation and doxorubicin treatment as shown by increased sub-G(1) content and decreased colony formation. This sensitizing effect was specific to DNA-damaging agents. Comet assay and gamma-H2AX phosphorylation status showed that the decreased p53R2 levels inhibited DNA repair. Silencing p53R2 also reduced the levels of p21(WAF1/CIP1) at the posttranscriptional level, suggesting links between the p53-dependent DNA repair and cell cycle arrest pathways. Using LNCaP sublines stably expressing dominant-negative mutant p53, we found that the sensitizing effect of p53R2 silencing is mediated by p53-dependent apoptosis pathways. In the LNCaP sublines (R273H, R248W, and G245S) that have defects in inducing p53-dependent apoptosis, p53R2 silencing did not potentiate DNA damage-induced apoptosis, whereas p53R2 silencing was effective in a LNCaP subline (P151S) which retains the ability to induce p53-dependent apoptosis. This study shows that p53R2 is a potential therapeutic target that could be used to enhance the effectiveness of ionizing radiation or DNA-damaging chemotherapy in a subset of patients with prostate cancer.

Sociodemographic factors associated with nephrectomy in patients with metastatic renal cell carcinoma.

PURPOSE: Studies suggest that radical nephrectomy imparts a survival benefit in select patients with metastatic renal cell carcinoma. We determined the roles of patient age, gender, race and in particular marital status in the decision to pursue nephrectomy and the ensuing effect on overall survival. MATERIALS AND METHODS: Using the Surveillance, Epidemiology and End Results database we identified 11,182 patients between 1988 and 2004 who were diagnosed with metastatic renal cell carcinoma. Patients were separated into 2 groups, including those who underwent nephrectomy and those who did not, and they were stratified by the mentioned variables. Logistic regression and Kaplan-Meier analyses were used to determine the likelihood of undergoing nephrectomy and of overall survival in the cohorts. RESULTS: In the final cohort 3,443 patients (31%) underwent radical nephrectomy. These patients experienced longer median survival than those who did not undergo surgery (11 vs 4 months, p <0.001). The survival benefit was statistically similar regardless of age group, race, gender and marital status. However, nephrectomy was more commonly performed in younger age groups, and in white and married patients. While age group and race were statistically significant predictors of undergoing nephrectomy (OR 0.64, 95% CI 0.61-0.66 and OR 0.79, 95% CI 0.70-0.89, respectively), marital status was the most important predictor (OR 1.52, 95% CI 1.39-1.66). CONCLUSIONS: Patients with metastatic renal cell carcinoma who undergo radical nephrectomy experience a survival advantage over those who do not undergo surgery. Married patients are more likely to undergo nephrectomy than their unmarried counterparts. Physicians must be aware of this bias when selecting patients for nephrectomy.

Trends in pelvic lymphadenectomy at the time of radical cystectomy: 1988 to 2004.

PURPOSE: Studies suggest that patients who undergo thorough lymphadenectomy for bladder cancer benefit from improved survival. We evaluated the incidence of and trends in lymphadenectomy in conjunction with radical cystectomy for bladder cancer. MATERIALS AND METHODS: Using the Surveillance, Epidemiology and End Results registry we identified 8,072 eligible patients with bladder cancer who underwent radical cystectomy with or without lymphadenectomy from 1988 to 2004. After stratification by age group, race, stage, grade and year of diagnosis we performed logistic and linear regression to correlate variables to the mean number of lymph nodes sampled and the likelihood of undergoing lymphadenectomy (classified as 1 or more, 5 or more and 10 or more nodes removed). RESULTS: In the final cohort 1,660 patients (21%) did not have any lymph nodes sampled at radical cystectomy. This number decreased from 37% in 1988 to 16% in 2004. During this period the mean number of lymph nodes removed increased by 2.6 nodes over all definitions of lymphadenectomy and the percentage of patients undergoing any form of lymph node dissection increased by an average of 19%. Year of diagnosis was most strongly predictive of the likelihood of undergoing lymphadenectomy and most correlative with the mean number of nodes sampled. CONCLUSIONS: Over time there has been improvement in terms of the performance of lymphadenectomy and node counts obtained during radical cystectomy. If these trends continue the incidence and quality of lymphadenectomy should continue to increase, ultimately to the benefit of the patients being treated.

A sequential treatment approach to myoinvasive urothelial cancer: a phase II Southwest Oncology Group trial (S0219).

PURPOSE: We conducted a phase II trial of neoadjuvant paclitaxel, carboplatin and gemcitabine as well as transurethral resection of bladder tumor to evaluate the clinical T0 (cT0) rate with paclitaxel, carboplatin and gemcitabine, and to study cystoscopic surveillance or immediate cystectomy for patients with cT0 status following chemotherapy. MATERIALS AND METHODS: Patients with T2-T4a chemotherapy and radiation naive urothelial cancer were eligible. T2+ tumor had to be diagnosed by transurethral bladder tumor resection followed by a second transurethral bladder tumor resection to confirm persistent disease within 16 weeks of the first resection. Three cycles of paclitaxel, carboplatin and gemcitabine were administered within 8 weeks of the second transurethral bladder tumor resection. Patients with cT0 status after paclitaxel, carboplatin and gemcitabine therapy could elect immediate cystectomy or cystoscopic surveillance, and those with greater than cT0 status were to undergo immediate cystectomy. RESULTS: Of 77 patients 74 were assessable, and cT0 status after paclitaxel, carboplatin and gemcitabine was achieved in 34 of 74 patients (46%). Of the 34 patients with cT0 status 10 underwent immediate cystectomy, 6 of whom had persistent cancer. Persistent tumor at transurethral bladder tumor resection was seen in 28 patients (38%) and 21 underwent cystectomy. Thus, 35 of 74 patients underwent cystectomy. With a median followup of 22 months 2-year overall survival was 59% (95% CI 45, 72) and among cT0 cases it was 75% (95% CI 57, 93). CONCLUSIONS: Although neoadjuvant paclitaxel, carboplatin and gemcitabine had a promising 46% cT0 rate, the study failed to meet the primary objective as there was an unacceptably high rate (60%) of persistent cancer at cystectomy in patients presumed to have pT0 status. Patients completing neoadjuvant chemotherapy should strongly consider definitive local therapy rather than cystoscopic surveillance regardless of post-chemotherapy cT0 status.

MicroRNAs and their potential for translation in prostate cancer.

OBJECTIVE: Patients die of prostate cancer (CaP) because predictably after a period of response to androgen withdrawal, their CaP becomes castrate resistant. In this paper, we discuss the role that microRNAs (miRNAs) may play in this process. METHODS: miRNAs are a group of endogenous, small non-coding RNA molecules that are thought to be responsible for the regulation of up to 30% of gene expression. The miRNA expression profile between androgen responsive and castrate resistant CaP cell lines is compared. Functional studies were carried out to identify the importance of the miRNA targets in controlling this process. RESULTS: There were 17 differentially expressed miRNAs found, 10 up-regulated and 7 down-regulated. Among these, miRNA-125b was found to have the ability of rendering LNCaP cells resistant to androgen withdrawal. It was found to be androgen regulated and one of its targets, BAK1, was identified as being involved in how these CaP cells undergo apoptosis functionally. CONCLUSION: miRNA-125b, at least in the CaP cell lines tested, is involved in the development of castrate resistance. While clearly this miRNA is only part of the answer, miRNAs may lead us in a new direction in trying to solve the central problem in CaP.

Prolonged androgen receptor loading onto chromatin and the efficient recruitment of p160 coactivators contribute to androgen-independent growth of prostate cancer cells.

BACKGROUND: Growth of most ablation-resistant prostate cancers (CaPs) is dependent on androgen receptor (AR) activity in chromatin, but cancer cells in these tumors have acquired altered AR activation. It is unclear how the aberrantly activated AR loads onto regulatory regions of AR-targeted genes. The purpose of this study was to assess the AR chromatin loading in an androgen-depleted environment. METHODS: The expression of PSA in androgen-resistant CaP cells was determined using RT-PCR and Western blot analysis. In order to investigate the binding of the AR to the PSA gene regulatory regions, chromatin immunoprecipitation (ChIP) was performed in the androgen-independent cds2 cell line in the presence or absence of androgens. In addition, we examined the involvement of p160 coactivators in the chromatin loading of the AR. RESULTS: It was found that constitutive activation of PSA expression was the result of sustained occupancy by the AR at the regulatory region of this gene. This stable AR loading was not blocked by the AR antagonist bicalutamide. Furthermore, androgen-resistant CaP cells highly expressed both AR and the p160 coactivators and the AR was able to recruit TIF2. Downregulation of TIF2 using short hairpin RNA disrupted the AR loading to the PSA enhancer and subsequently inhibited AR activity. CONCLUSION: Prolonged AR localization to the regulatory regions of AR targeted genes and the recruitment of p160 coactivators are a potential mechanism leading to androgen-independent activation of the AR. Disruption of AR chromatin loading could therefore become an important therapeutic target for this disease.

Cystectomy in the elderly: does the survival benefit in younger patients translate to the octogenarians?

OBJECTIVE: To determine whether the survival benefit achieved with radical cystectomy (RC, the reference standard for treating muscle-invasive bladder cancer) in younger patients justifies its use in octogenarians. PATIENTS AND METHODS: We used the Surveillance Epidemiology and End Results data of the National Cancer Institute and identified 10 807 patients from 1992-2004 who were diagnosed with muscle-invasive bladder cancer, and were treated with either RC or radiotherapy. The data were analysed for age, gender, race, extent of lymphadenectomy and cause of death. We stratified the patients by age groups (<60, 60-69, 70-79 and >79 years), and used Kaplan-Meier survival analysis to compare treatment strategies by age group. RESULTS: In all, 8034 patients had RC and 2773 radiotherapy; RC was the primary method of treatment in all age groups except for octogenarians. Those who had RC had a sizeable overall survival advantage in all age groups, except for the octogenarians (18 vs 15 months). This small survival advantage improved only slightly (23 vs 15 months) when excluding patients having nodal or distant metastasis. The octogenarians who have RC with a limited pelvic lymph node dissection or RC alone receive little (16 vs 15 months) or no survival benefit. However, cancer-specific survival was significantly higher in those who had RC, including octogenarians. CONCLUSIONS: Octogenarians have some benefit to cancer-specific survival from RC if it includes a standard lymphadenectomy. The issue is how to better select the patients, as the overall survival advantage in these patients over radiotherapy is negligible.