The deubiquitinating enzyme USP2a has shown oncogenic properties in many cancer types by impairing ubiquitination of FASN, MDM2, MDMX or Aurora A. Aberrant expression of USP2a has been linked to progression of human tumors, particularly prostate cancer. However, little is known about the role of USP2a or its mechanism of action in bladder cancer. Here, we provide evidence that USP2a is an oncoprotein in bladder cancer cells. Enforced expression of USP2a caused enhanced proliferation, invasion, migration and resistance to several chemotherapeutic reagents, while USP2a loss resulted in slower proliferation, greater chemosensitivity and reduced migratory/invasive capability compared with control cells. USP2a, but not a catalytically inactive mutant, enhanced proliferation in immortalized TRT-HU1 normal human bladder epithelial cells. USP2a bound to cyclin A1 and prevented cyclin A1 ubiquitination, leading to accumulation of cyclin A1 by a block in degradation. Enforced expression of wild-type USP2a, but not an inactive USP2a mutant, resulted in cyclin A1 accumulation and increased cell proliferation. We conclude that USP2a impairs ubiquitination and stabilizes an important cell cycle regulator, cyclin A1, raising the possibility of USP2a targeting as a therapeutic strategy against bladder tumors in combination with chemotherapy.
USP2a; cyclin A1; bladder cancer; cisplatin resistance; deubiquitination
Fusion of the androgen receptor-regulated (AR-regulated) TMPRSS2 gene with ERG in prostate cancer (PCa) causes androgen-stimulated overexpression of ERG, an ETS transcription factor, but critical downstream effectors of ERG-mediating PCa development remain to be established. Expression of the SOX9 transcription factor correlated with TMPRSS2:ERG fusion in 3 independent PCa cohorts, and ERG-dependent expression of SOX9 was confirmed by RNAi in the fusion-positive VCaP cell line. SOX9 has been shown to mediate ductal morphogenesis in fetal prostate and maintain stem/progenitor cell pools in multiple adult tissues, and has also been linked to PCa and other cancers. SOX9 overexpression resulted in neoplasia in murine prostate and stimulated tumor invasion, similarly to ERG. Moreover, SOX9 depletion in VCaP cells markedly impaired invasion and growth in vitro and in vivo, establishing SOX9 as a critical downstream effector of ERG. Finally, we found that ERG regulated SOX9 indirectly by opening a cryptic AR-regulated enhancer in the SOX9 gene. Together, these results demonstrate that ERG redirects AR to a set of genes including SOX9 that are not normally androgen stimulated, and identify SOX9 as a critical downstream effector of ERG in TMPRSS2:ERG fusion–positive PCa.
A common treatment of advanced prostate cancer involves the deprivation of androgens. Despite the initial response to hormonal therapy, eventually all the patients relapse. In the present study, we sought to determine whether dietary polyunsaturated fatty acid (PUFA) affects the development of castration-resistant prostate cancer. Cell culture, patient tissue microarray, allograft, xenograft, prostate-specific Pten knockout and omega-3 desaturase transgenic mouse models in conjunction with dietary manipulation, gene knockdown and knockout approaches were used to determine the effect of dietary PUFA on castration-resistant Pten-null prostate cancer. We found that deletion of Pten increased androgen receptor (AR) expression and Pten-null prostate cells were castration resistant. Omega-3 PUFA slowed down the growth of castration-resistant tumors as compared with omega-6 PUFA. Omega-3 PUFA decreased AR protein to a similar extent in tumor cell cytosolic and nuclear fractions but had no effect on AR messenger RNA level. Omega-3 PUFA treatment appeared to accelerate AR protein degradation, which could be blocked by proteasome inhibitor MG132. Knockdown of AR significantly slowed down prostate cancer cell proliferation in the absence of androgens. Our data suggest that omega-3 PUFA inhibits castration-resistant prostate cancer in part by accelerating proteasome-dependent degradation of the AR protein. Dietary omega-3 PUFA supplementation in conjunction with androgen ablation may significantly delay the development of castration-resistant prostate cancer in patients compared with androgen ablation alone.
The objective here was to summarize the evidence for, and quantify the link between, serum markers of lipid metabolism and risk of obesity-related cancers. PubMed and Embase were searched using predefined inclusion criteria to conduct meta-analyses on the association between serum levels of TG, TC, HDL, ApoA-I, and risk of 11 obesity-related cancers. Pooled relative risks (RRs) and 95% confidence intervals were estimated using random-effects analyses. 28 studies were included. Associations between abnormal lipid components and risk of obesity-related cancers when using clinical cutpoints (TC ≥ 6.50; TG ≥ 1.71; HDL ≤ 1.03; ApoA-I ≤ 1.05 mmol/L) were apparent in all models. RRs were 1.18 (95% CI: 1.08–1.29) for TC, 1.20 (1.07–1.35) for TG, 1.15 (1.01–1.32) for HDL, and 1.42 (1.17–1.74) for ApoA-I. High levels of TC and TG, as well as low levels of HDL and ApoA-I, were consistently associated with increased risk of obesity-related cancers. The modest RRs suggest serum lipids to be associated with the risk of cancer, but indicate it is likely that other markers of the metabolism and/or lifestyle factors may also be involved. Future intervention studies involving lifestyle modification would provide insight into the potential biological role of lipid metabolism in tumorigenesis.
Ubiquitin-specific protease 2a (USP2a) is overexpressed in almost half of human prostate cancers and c-Myc is amplified in one third of these tumor types. Transgenic MYC expression drives invasive adenocarcinomas in the murine prostate. We show that overexpression of USP2a downregulates a set of microRNAs that collectively increase MYC levels by MDM2 deubiquitination and subsequent p53 inactivation. By establishing MYC as a target of miR-34b/c, we demonstrate that this cluster functions as a tumor suppressor in prostate cancer cells. We identify a distinct mRNA signature that is enriched for MYC-regulated transcripts and transcription factor binding sites in USP2a overexpressing prostate cancer cells. We demonstrate that these genes are associated with an invasive phenotype in human prostate cancer and that the proliferative and invasive properties of USP2a overexpressing cells are MYC-dependent. These results highlight an unrecognized mechanism of MYC regulation in prostate cancer and suggest alternative therapeutic strategies in targeting MYC.
Frizzled 8-associated Antiproliferative Factor (APF) is a sialoglycopeptide urinary biomarker of interstitial cystitis/painful bladder syndrome (IC/PBS), a chronic condition of unknown etiology with variable symptoms that generally include pelvic and/or perineal pain, urinary frequency, and urgency. We previously reported that native human APF suppresses the proliferation of normal bladder epithelial cells through a mechanism that involves increased levels of p53. The goal of this study was to delineate the regulatory mechanism whereby p53 expression is regulated by APF. Two APF-responsive cell lines (T24 bladder carcinoma cells and the immortalized human bladder epithelial cell line, TRT-HU1) were treated with asialo-APF (as-APF), a chemically synthesized form of APF. Biochemical analysis revealed that as-APF increased p53 levels in two ways: by decreasing ubiquitin specific protease 2a (USP2a) expression leading to enhanced ubiquitination of murine double minute 2 E3 ubiquitin ligase (MDM2), and by suppressing association of p53 with MDM2, thus impairing p53 ubiquitination. Biological responses to as-APF were suppressed by increased expression of wild type, but not mutant USP2a, which enhanced cell growth via upregulation of a cell cycle mediator, cyclin D1, at both transcription and protein levels. Consistent with this, gene silencing of USP2a with siRNA arrested cell proliferation. Our findings suggest that APF upregulates cellular p53 levels via functional attenuation of the USP2a-MDM2 pathway, resulting in p53 accumulation and growth arrest. These data also imply that targeting USP2a, MDM2, p53 and/or complex formation by these molecules may be relevant in the development of novel therapeutic approaches to IC/PBS.
Clinical outcomes in prostate cancer are heterogeneous and given the high prevalence of the disease, there is a pressing need to identify clinically useful markers of prognosis. Many clinical, pathologic, molecular, and genetic factors have been investigated in this capacity though relatively few are routinely used. With a growing understanding of the molecular pathogenesis of prostate cancer, there is the potential that the next generation of makers will prove sufficiently robust to guide the optimal management of men with prostate cancer. Here, we review the various clinical and molecular prognostic determinants in prostate cancer.
prognosis; prostate; gene expression signatures; immunohistochemistry
Automated scanning devices and image analysis software provide a means to overcome the limitations of manual semiquantitative scoring of immunohistochemistry. Common drawbacks to automated imaging systems include an inability to classify tissue type and an inability to segregate cytoplasmic and nuclear staining.
Immunohistochemistry for the membranous marker α-catenin, the cytoplasmic marker stathmin and the nuclear marker Ki-67 was performed on tissue microarrays (TMA) of archival formalin-fixed paraffin-embedded tissue comprising 471 (α-catenin and stathmin) and 511 (Ki-67) cases of prostate adenocarcinoma. These TMA were quantitatively analysed using two commercially available automated image analysers, the Ariol SL-50 system and the Nuance system from CRi. Both systems use brightfield microscopy for automated, unbiased and standardised quantification of immunohistochemistry, while the Nuance system has spectral deconvolution capabilities.
Overall concordance between scores from both systems was excellent (r=0.90; 0.83–0.95). The software associated with the multispectral imager allowed accurate automated classification of tissue type into epithelial glandular structures and stroma, and a single-step segmentation of staining into cytoplasmic or nuclear compartments allowing independent evaluation of these areas. The Nuance system, however, was not able to distinguish reliably between tumour and non-tumour tissue. In addition, variance in the labour and time required for analysis between the two systems was also noted.
Despite limitations, this study suggests some beneficial role for the use of a multispectral imaging system in automated analysis of immunohistochemistry.
Whole-genome copy number analysis platforms, such as array comparative genomic hybridization (aCGH) and single nucleotide polymorphism (SNP) arrays, are transformative research discovery tools. In cancer, the identification of genomic aberrations with these approaches has generated important diagnostic and prognostic markers, and critical therapeutic targets. While robust for basic research studies, reliable whole-genome copy number analysis has been unsuccessful in routine clinical practice due to a number of technical limitations. Most important, aCGH results have been suboptimal because of the poor integrity of DNA derived from formalin-fixed paraffin-embedded (FFPE) tissues. Using self-hybridizations of a single DNA sample we observed that aCGH performance is significantly improved by accurate DNA size determination and the matching of test and reference DNA samples so that both possess similar fragment sizes. Based on this observation, we developed a novel DNA fragmentation simulation method (FSM) that allows customized tailoring of the fragment sizes of test and reference samples, thereby lowering array failure rates. To validate our methods, we combined FSM with Universal Linkage System (ULS) labeling to study a cohort of 200 tumor samples using Agilent 1 M feature arrays. Results from FFPE samples were equivalent to results from fresh samples and those available through the glioblastoma Cancer Genome Atlas (TCGA). This study demonstrates that rigorous control of DNA fragment size improves aCGH performance. This methodological advance will permit the routine analysis of FFPE tumor samples for clinical trials and in daily clinical practice.
Data suggest that circulating 25-hydroxyvitamin D [25(OH)D] interacts with the vitamin D receptor (VDR) to decrease proliferation and increase apoptosis for some malignancies, although evidence for prostate cancer is less clear. How VDR expression in tumor tissue may influence prostate cancer progression has not been evaluated in large studies.
Patients and Methods
We examined protein expression of VDR in tumor tissue among 841 patients with prostate cancer in relation to risk of lethal prostate cancer within two prospective cohorts, the Physicians' Health Study and Health Professionals Follow-Up Study. We also examined the association of VDR expression with prediagnostic circulating 25(OH)D and 1,25-dihydroxyvitamin D levels and with two VDR single nucleotide polymorphisms, FokI and BsmI.
Men whose tumors had high VDR expression had significantly lower prostate-specific antigen (PSA) at diagnosis (P for trend < .001), lower Gleason score (P for trend < .001), and less advanced tumor stage (P for trend < .001) and were more likely to have tumors harboring the TMPRSS2:ERG fusion (P for trend = .009). Compared with the lowest quartile, men whose tumors had the highest VDR expression had significantly reduced risk of lethal prostate cancer (hazard ratio [HR], 0.17; 95% CI, 0.07 to 0.41). This association was only slightly attenuated after adjustment for Gleason score and PSA at diagnosis (HR, 0.33; 95% CI, 0.13 to 0.83) or, additionally, for tumor stage (HR, 0.37; 95% CI, 0.14 to 0.94). Neither prediagnostic plasma vitamin D levels nor VDR polymorphisms were associated with VDR expression.
High VDR expression in prostate tumors is associated with a reduced risk of lethal cancer, suggesting a role of the vitamin D pathway in prostate cancer progression.
Prostate-specific antigen screening has led to enormous overtreatment of prostate cancer because of the inability to distinguish potentially lethal disease at diagnosis. We reasoned that by identifying an mRNA signature of Gleason grade, the best predictor of prognosis, we could improve prediction of lethal disease among men with moderate Gleason 7 tumors, the most common grade, and the most indeterminate in terms of prognosis.
Patients and Methods
Using the complementary DNA–mediated annealing, selection, extension, and ligation assay, we measured the mRNA expression of 6,100 genes in prostate tumor tissue in the Swedish Watchful Waiting cohort (n = 358) and Physicians' Health Study (PHS; n = 109). We developed an mRNA signature of Gleason grade comparing individuals with Gleason ≤ 6 to those with Gleason ≥ 8 tumors and applied the model among patients with Gleason 7 to discriminate lethal cases.
We built a 157-gene signature using the Swedish data that predicted Gleason with low misclassification (area under the curve [AUC] = 0.91); when this signature was tested in the PHS, the discriminatory ability remained high (AUC = 0.94). In men with Gleason 7 tumors, who were excluded from the model building, the signature significantly improved the prediction of lethal disease beyond knowing whether the Gleason score was 4 + 3 or 3 + 4 (P = .006).
Our expression signature and the genes identified may improve our understanding of the de-differentiation process of prostate tumors. Additionally, the signature may have clinical applications among men with Gleason 7, by further estimating their risk of lethal prostate cancer and thereby guiding therapy decisions to improve outcomes and reduce overtreatment.
The S6K1 and S6K2 kinases are considered important mTOR signaling effectors, yet their contribution to tumorigenesis remains unclear. Aberrant mTOR activation is a frequent event in cancer, that commonly results from heterozygous loss of PTEN. Here, we show for the first time a differential protein expression between S6K1 and S6K2 in both mouse and human tissues. Additionally, the inactivation of S6k1 in the context of Pten heterozygosity (Pten+/-) suggests a differential requirement for this protein across multiple tissues. This tissue-specificity appears to be governed by the relative protein expression of S6k2. Accordingly, we find that deletion of S6k1 markedly impairs Pten+/- mediated adrenal tumorigenesis, specifically due to low expression of S6k2. Concomitant observation of low S6K2 levels in the human adrenal gland supports the development of S6K1-inhibitors for treatment of PTEN loss driven pheochromocytoma.
The most common mutation in melanoma, BRAF(V600E), activates the BRAF serine/threonine kinase and causes excessive MAPK pathway activity1,2. BRAF(V600E)mutations are also present in benign melanocytic nevi3, highlighting the importance of additional genetic alterations in the genesis of malignant tumors. Such changes include recurrent copy number variations that result in the amplification of oncogenes4,5. For certain amplifications, the large number of genes in the interval has precluded an understanding of cooperating oncogenic events. Here, we have used a zebrafish melanoma model to test genes in a recurrently amplified region on chromosome 1 for the ability to cooperate with BRAF(V600E) and accelerate melanoma. SETDB1, an enzyme that methylates histone H3 on lysine 9 (H3K9), was found to significantly accelerate melanoma formation in the zebrafish. Chromatin immunoprecipitation coupled with massively parallel DNA sequencing (ChIP-Seq) and gene expression analyses revealed target genes, including Hox genes, that are transcriptionally dysregulated in response to elevated SETDB1. Our studies establish SETDB1 as an oncogene in melanoma and underscore the role of chromatin factors in regulating tumorigenesis.
The middle T (MT) antigen of polyomavirus has provided fundamental insights into the regulation of mammalian cell growth in vitro and important animal models for the analysis of tumor induction. The mouse mammary tumor virus (MMTV)-MT model of breast cancer has been important for probing the cellular signaling pathways in mammary tumorigenesis. MT itself has no intrinsic enzymatic activity but, rather, transforms by binding to and activating key intracellular signaling molecules, phosphatidylinositol 3-kinase (PI3-kinase) being the best studied of these. Thus, MT mimics a constitutively activated receptor tyrosine kinase (RTK). Our recent work suggests that MT signaling, like that of RTKs, is often quite dependent on cellular context in vitro. Here, we examine contextual effects on signaling in animal models as well. In this study, we generated transgenic mice in which MT is expressed in the mouse prostate under the control of an (ARR)2-Probasin promoter. All male transgenic mice displayed mouse prostatic intraepithelial neoplasia (mPIN) in the ventral and dorsal/lateral prostate as early as 8 weeks of age. Notably, during the course of tumor development over time, invasive cancer, reactive stroma, and infiltration of inflammatory cells were seen. Transcriptional profiling analyses show regulation of multiple pathways, with marked upregulation of both the NF-κB and inflammatory pathways. Comparison of expression profiles of our MT prostate model with those from an MMTV-MT breast model (23) shows both tissue-specific and tissue-independent MT effects. The signature of genes regulated by MT in a tissue-independent manner may have prognostic value.
Fatty acid synthase (FASN), a key metabolic enzyme for liponeogenesis highly expressed in several human cancers, displays oncogenic properties such as resistance to apoptosis and induction of proliferation when overexpressed. To date, no mechanism has been identified to explain the oncogenicity of FASN in prostate cancer.
We generated immortalized prostate epithelial cells (iPrEC) overexpressing FASN, and found that 14C-acetate incorporation into palmitate synthesized de novo by FASN was significantly elevated in immunoprecipitated Wnt-1 when compared to isogenic cells not overexpressing FASN. Overexpression of FASN caused membranous and cytoplasmic β-catenin protein accumulation and activation, while FASN knockdown by short hairpin RNA (shRNA) resulted in a reduction in the extent of β-catenin activation. Orthotopic transplantation of iPrEC cells overexpressing FASN in nude mice resulted in invasive tumors that overexpressed β-catenin.
A strong significant association between FASN and cytoplasmic (stabilized) β-catenin immunostaining was found in 862 cases of human prostate cancer after computerized subtraction of the membranous β-catenin signal (P<0.001, Spearman’s rho=0.33). We propose that cytoplasmic stabilization of β-catenin through palmitoylation of Wnt-1 and subsequent activation of the pathway is a potential mechanism of FASN oncogenicity in prostate cancer.
β-catenin; Fatty Acid Synthase; Prostate cancer; Image analysis; Immunohistochemistry; Palmitoylation; Wnt1
Cancer cells synthesize de novo large amounts of fatty acids and cholesterol, irrespective of the circulating lipid levels and benefit from this increased lipid synthesis in terms of growth advantage, self-survival and drug resistance. Key lipogenic alterations that commonly occur in prostate cancer include over-expression of the enzyme fatty acid synthase (FASN) and deregulation of the 5-AMP-activated protein kinase (AMPK). FASN is a key metabolic enzyme that catalyses the synthesis of palmitate from the condensation of malonyl-CoA and acetyl-CoA de novo and plays a central role in energy homeostasis, by converting excess carbon intake into fatty acids for storage. AMPK functions as a central metabolic switch that governs glucose and lipid metabolism. Recent interest has focused on the potential of targeting metabolic pathways that may be altered during prostate tumorigenesis and progression. Several small molecule inhibitors of FASN have now been described or in development for therapeutic use; in addition, drugs that directly or indirectly induce AMPK activation have potential benefit in prostate cancer prevention and treatment.
prostate cancer; lipogenesis; fatty acid synthase; AMPK; inhibitors
Fatty acid synthase (FASN) is a key enzyme involved in neoplastic lipogenesis. Overexpression of FASN is common in many cancers, and accumulating evidence suggests that it is a metabolic oncogene with an important role in tumor growth and survival, making it an attractive target for cancer therapy. Early small-molecule FASN inhibitors such as cerulenin, C75 and orlistat have been shown to induce apoptosis in several cancer cell lines and to induce tumor growth delay in several cancer xenograft models but their mechanism is still not well understood. These molecules suffer from pharmacological limitations and weight loss as a side effect that prevent their development as systemic drugs. Several potent inhibitors have recently been reported that may help to unravel and exploit the full potential of FASN as a target for cancer therapy in the near future. Furthermore, novel sources of FASN inhibitors, such as green tea and dietary soy, make both dietary manipulation and chemoprevention potential alternative modes of therapy in the future.
C75; cancer; ERBB-2; fatty acid synthase; MAPK; PI3K/AKT; SREBP-1
Whereas the role of Metabolic Syndrome (MS), and a high fat diet in prostate cancer (PCa) risk is still a matter of intense debate, it is becoming increasingly clear that obesity can cause perturbations in metabolic pathways that contribute to the pathogenesis and progression of PCa. Moreover, prostate epithelial cells per se undergo a series of metabolic changes, including an increase in de-novo lipogenesis, during the process of tumor formation. These metabolic alterations, at both the cellular and organismal levels, are intertwined with genetic aberrations necessary for neoplastic tranformation. Thus, altered metabolism is currently subject to intense research efforts and might provide preventative and therapeutic opportunities, as well as a platform for biomarker development. In this article, we review evidence that the metabolic sensor 5’-AMP-activated protein kinase (AMPK), which physiologically integrates nutritional and hormonal signals and regulates cell survival and growth-related metabolic pathways to preserve intracellular ATP levels, represents a link between energy homeostasis and cancer. Thus, when AMPK is not activated, as in the setting of MS and obesity, systemic metabolic alterations permissive to the development of PCa are allowed to proceed unchecked. Hence, the use of AMPK activators and inhibitors of key lipogenic enzymes may represent a promising therapeutic strategy for PCa.
Variation in genes contributing to the host immune response may mediate the relationship between inflammation and prostate carcinogenesis. RNASEL at chromosome 1q25 encodes ribonuclease L, part of the interferon-mediated immune response to viral infection. We therefore investigated the association between variation in RNASEL and prostate cancer risk and progression in a study of 1286 cases and 1264 controls nested within the prospective Physicians’ Health Study. Eleven single-nucleotide polymorphisms (SNPs) were selected using the web-based ‘Tagger’ in the HapMap CEPH panel (Utah residents of Northern and Western European Ancestry). Unconditional logistic regression models assessed the relationship between each SNP and incident advanced stage (T3/T4, T0-T4/M1 and lethal disease) and high Gleason grade (≥7) prostate cancer. Further analyses were stratified by calendar year of diagnosis. Cox proportional hazards models examined the relationship between genotype and prostate cancer-specific survival. We also explored associations between genotype and serum inflammatory biomarkers interleukin-6 (IL-6), C-reactive protein (CRP) and tumor necrosis factor-alpha receptor 2 using linear regression. Individuals homozygous for the variant allele of rs12757998 had an increased risk of prostate cancer [AA versus GG; odds ratio (OR): 1.63, 95% confidence interval (CI): 1.18–2.25), and more specifically, high-grade tumors (OR: 1.90, 95% CI: 1.25–2.89). The same genotype was associated with increased CRP (P = 0.02) and IL-6 (P = 0.05) levels. Missense mutations R462Q and D541E were associated with an increased risk of advanced stage disease only in the pre-prostate-specific antigen era. There were no significant associations with survival. The results of this study support a link between RNASEL and prostate cancer and suggest that the association may be mediated through inflammation. These novel findings warrant replication in future studies.
Fatty acid synthase (FASN) regulates de novo lipogenesis, body weight, and tumor growth. We examined whether common germline single nucleotide polymorphisms (SNPs) in the FASN gene affect prostate cancer (PCa) risk or PCa-specific mortality and whether these effects vary by body mass index (BMI).
In a prospective nested case-control study of 1,331 white patients with PCa and 1,267 age-matched controls, we examined associations of five common SNPs within FASN (and 5 kb upstream/downstream, R2 > 0.8) with PCa incidence and, among patients, PCa-specific death and tested for an interaction with BMI. Survival analyses were repeated for tumor FASN expression (n = 909).
Four of the five SNPs were associated with lethal PCa. SNP rs1127678 was significantly related to higher BMI and interacted with BMI for both PCa risk (Pinteraction = .004) and PCa mortality (Pinteraction = .056). Among overweight men (BMI ≥ 25 kg/m2), but not leaner men, the homozygous variant allele carried a relative risk of advanced PCa of 2.49 (95% CI, 1.00 to 6.23) compared with lean men with the wild type. Overweight patients carrying the variant allele had a 2.04 (95% CI, 1.31 to 3.17) times higher risk of PCa mortality. Similarly, overweight patients with elevated tumor FASN expression had a 2.73 (95% CI, 1.05 to 7.08) times higher risk of lethal PCa (Pinteraction = .02).
FASN germline polymorphisms were significantly associated with risk of lethal PCa. Significant interactions of BMI with FASN polymorphisms and FASN tumor expression suggest FASN as a potential link between obesity and poor PCa outcome and raise the possibility that FASN inhibition could reduce PCa-specific mortality, particularly in overweight men.
Associations between Metabolic Syndrome (MetS) components and prostate cancer development have not been studied comprehensively; results have been divergent. Using the National Cholesterol Education Program Adult Treatment panel III (NCEP) and International Diabetes Federation (IDF) definitions of the MetS we investigated such associations taking competing risks of death into consideration.
In the prospective Uppsala Longitudinal Study of Adult Men (ULSAM) of 2322 Caucasian men with 34 years of follow-up baseline MetS-measurements at age 50 were used. Cumulative incidence of prostate cancer and death with/without the MetS were calculated. Competing risk of dying was taken into account by calculating the conditional probability of prostate cancer with/without the MetS.
Two-hundred-and- thirty-seven prostate cancers were identified. Prostate cancer probability by age 80 with baseline MetS compared to without the MetS was non-significantly higher, 5.2 percent-units (CI -0.8%-11.3%, (NCEP), 2.7 percent-units (CI -2.7%-8.0%) (IDF), cumulative incidence proportions of death was significantly higher, 19.3 percent-units (CI 13.4%-25.3%) (NCEP), 15.3 percent-units (CI 9.5%-21.1%) (IDF) and conditional probability of prostate cancer considering death from other causes was significantly higher, 7.3 percent-units (CI 0.2%-14.5%) odds ratio(OR) of 1.64 (CI 1.03-2.23). (NCEP), and non-significantly higher 5.0 percent-units (CI -1.6%-11.6%) OR 1.43 (CI 0.89-1.90). (IDF).
The MetS by the NCEP definition is associated with prostate cancer taking the competing risk of early death from other causes into account.
The results further highlight the public health impact of the increasing prevalence of MetS, and the importance of considering competing risks when studying risk factors for cancer.
epidemiology; prostate cancer; metabolic syndrome; competing risk; risk factors
BRCA1 functions as a tumor suppressor; recent work suggests that BRCA1 may also induce cell-cycle arrest to allow for DNA repair. We hypothesized that BRCA1 expression in prostate tumor tissue may be associated with prostate cancer progression through regulation of the cell-cycle. We used immunohistochemistry to evaluate BRCA1 protein expression in archival tumors samples from 393 prostate cancer cases in the Physicians' Health Study. The men were followed prospectively from diagnosis to development of metastases and mortality. Fifteen percent of tumors stained positive for BRCA1. BRCA1 positive tumors had substantially increased tumor proliferation index compared to negative tumors (47.0 Ki67 positive nuclei vs. 10.3, p=0.0016), and were more likely to develop lethal cancer compared to BRCA1 negative tumors (Hazard ratio=4.6; 95% Confidence interval: 2.4, 8.7). These findings strengthen the hypothesis that BRCA1 plays a role in cell-cycle control and demonstrate that BRCA1 is a marker of clinical prostate cancer prognosis.
In retrospective studies, loss of p27Kip1 (p27), a cyclin dependent kinase inhibitor, has been associated with poor prognosis following colorectal cancer treatment. In a prospective study, we validated this relationship in patients enrolled on a trial of adjuvant chemotherapy for Stage III colon cancer.
Cancer and Leukemia Group B (CALGB) protocol 89803 randomized 1264 stage III colon cancer patients to receive weekly bolus fluorouracil/leucovorin (5FU/LV) or weekly bolus irinotecan, fluorouracil, and leucovorin (IFL). The primary endpoint was overall survival (OS); disease-free survival (DFS) was a secondary endpoint. Expression of p27 and DNA mismatch repair (MMR) proteins were determined by immunohistochemistry (IHC) in primary tumor and normal tissue from paraffin blocks. Data were analyzed using logrank test.
Of 601 tumors analyzed, 207 (34.4%) demonstrated p27 loss, 377 (62.8%) retained p27, and 17 (2.8%) were indeterminate. Patients with p27 negative tumors showed reduced OS (5-year 66%; 95%CI 0.59-0.72 vs. 75%; 95%CI 0.70-0.79, logrank p=0.021). This relationship was not influenced by treatment arm. Combination of p27 status with MMR status, however, identified a small subset of patients that may benefit from IFL (n=36; 5-year DFS 81%; 95%CI 0.64-0.98 vs. 47%; 95%CI 0.21-0.72, logrank p=0.042; 5-year OS 81%; 95%CI 0.64-0.98 vs. 60%; 95%CI 0.35-0.85; logrank p=0.128).
Loss of p27 is associated with reduced survival in stage III colon cancer, but by itself does not indicate a significant difference in outcome between patients treated IFL or 5FU-LV.
Colorectal cancer; adjuvant therapy; biomarkers
PTEN (phosphatase and tensin homolog deleted on chromosome 10) is a tumor suppressor that antagonizes signaling through the phosphatidylinositol-3-kinase–Akt pathway. We have demonstrated that subtle decreases in PTEN abundance can have critical consequences for tumorigenesis. Here, we used a computational approach to identify miR-22, miR-25, and miR-302 as three PTEN-targeting microRNA (miRNA) families found within nine genomic loci. We showed that miR-22 and the miR-106b∼25 cluster are aberrantly overexpressed in human prostate cancer, correlate with abundance of the miRNA processing enzyme DICER, and potentiate cellular transformation both in vitro and in vivo. We demonstrated that the intronic miR-106b∼25 cluster cooperates with its host gene MCM7 in cellular transformation both in vitro and in vivo, so that the concomitant overexpression of MCM7 and the miRNA cluster triggers prostatic intraepithelial neoplasia in transgenic mice. Therefore, the MCM7 gene locus delivers two simultaneous oncogenic insults when amplified or overexpressed in human cancer. Thus, we have uncovered a proto-oncogenic miRNA-dependent network for PTEN regulation and defined the MCM7 locus as a critical factor in initiating prostate tumorigenesis.