[show abstract][hide abstract] ABSTRACT: Aberrations in epigenetic processes, such as histone methylation, can cause cancer. Retinoblastoma binding protein 2 (RBP2; also called JARID1A or KDM5A) can demethylate tri- and dimethylated lysine 4 in histone H3, which are epigenetic marks for transcriptionally active chromatin, whereas the multiple endocrine neoplasia type 1 (MEN1) tumor suppressor promotes H3K4 methylation. Previous studies suggested that inhibition of RBP2 contributed to tumor suppression by the retinoblastoma protein (pRB). Here, we show that genetic ablation of Rbp2 decreases tumor formation and prolongs survival in Rb1(+/-) mice and Men1-defective mice. These studies link RBP2 histone demethylase activity to tumorigenesis and nominate RBP2 as a potential target for cancer therapy.
Proceedings of the National Academy of Sciences 08/2011; 108(33):13379-86. · 9.74 Impact Factor
[show abstract][hide abstract] ABSTRACT: Renal cell carcinoma (RCC) is an aggressive malignancy with limited responsiveness to existing treatments. In vivo models of human cancer, including RCC, are critical for developing more effective therapies. Unfortunately, current RCC models do not accurately represent relevant properties of the human disease. The goal of this study was to develop clinically relevant animal models of RCC for preclinical investigations. We transplanted intact human tumour tissue fragments orthotopically in immunodeficient mice. The xenografts were validated by comparing the morphological, phenotypic and genetic characteristics of the kidney tumour tissues before and after implantation. Twenty kidney tumours were transplanted into mice. Successful tumour growth was detected in 19 cases (95%). The histopathological and immunophenotypic features of the xenografts and those of the original tumours largely overlapped in all cases. Evaluation of genetic alterations in a subset of 10 cases demonstrated that the grafts largely retained the genetic features of the pre-implantation RCC tissues. Indeed, primary tumours and corresponding grafts displayed identical VHL mutations. Moreover, an identical pattern of DNA copy amplification or loss was observed in 6/10 cases (60%). In summary, orthotopic engrafting of RCC tissue fragments can be successfully used to generate animal models that closely resemble RCC in patients. These models will be invaluable for in vivo preclinical drug testing and for deeper understanding of kidney carcinogenesis. The raw data of the SNP array analysis has been submitted to the GEO database (Accession No. GSE29062).
The Journal of Pathology 05/2011; 225(2):212-21. · 7.59 Impact Factor
[show abstract][hide abstract] ABSTRACT: Carbonic anhydrase IX (CAIX), a hypoxia-induced protein, is expressed in some renal tumors. We evaluated its immunohistochemical expression in 317 primary and 42 metastatic renal neoplasms (186 clear cell, 52 papillary, 35 chromophobe, 47 unclassified, and 15 Xp11.2 translocation renal cell carcinomas [RCCs]; 26 oncocytomas; 2 metanephric adenomas; 1 urothelial carcinoma; 1 mixed epithelial and stromal tumor; and 1 angiomyolipoma); 7 neoplasms were unknown as to whether they were primary or metastatic. We also correlated expression with tumor type and grade. Variable staining was seen in clear cell, papillary, unclassified, and Xp11.2 translocation carcinomas. One chromophobe carcinoma had focal expression. No staining was seen with other tumors. An association was found between high expression and clear cell vs non-clear cell carcinomas with all cases (P < .01) and primary (P < .01) cases. An association between CAIX expression and grade (P < .01) in primary clear cell carcinomas was found. CAIX expression is more common in clear cell RCC than other renal tumor types and is associated with grade.
American Journal of Clinical Pathology 12/2010; 134(6):873-9. · 2.88 Impact Factor
[show abstract][hide abstract] ABSTRACT: Genome-wide association studies (GWAS) have successfully identified common polymorphisms that are strongly associated with many traits, including cancer. A gene desert located on chromosome 8q24 is associated with multiple cancer types. One of the closest genes is the MYC proto-oncogene. Investigations are now turning toward a mechanistic understanding of these (and other) risk loci. Recent studies demonstrate that the 8q24 loci are enhancers and that they physically interact with MYC. A still unresolved issue is the absence of a consistent association between genotype status at the risk loci and steady-state MYC expression levels in adult human tissues. Clarifying the function of the 8q24 variants and their link to MYC regulation by further in vivo and in vitro functional studies will allow a deeper understanding of the mechanisms underlying human cancer development.
[show abstract][hide abstract] ABSTRACT: The 8q24 gene desert contains risk loci for multiple epithelial cancers, including colon, breast, and prostate. Recent evidence suggests these risk loci contain enhancers. In this study, data are presented showing that each risk locus bears epigenetic marks consistent with enhancer elements and forms a long-range chromatin loop with the MYC proto-oncogene located several hundred kilobases telomeric and that these interactions are tissue-specific. We therefore propose that the 8q24 risk loci operate through a common mechanism-as tissue-specific enhancers of MYC.
Proceedings of the National Academy of Sciences 05/2010; 107(21):9742-6. · 9.74 Impact Factor
[show abstract][hide abstract] ABSTRACT: Overexpression of the fatty acid synthase (FASN) gene has been implicated in prostate carcinogenesis. We sought to directly assess the oncogenic potential of FASN.
We used immortalized human prostate epithelial cells (iPrECs), androgen receptor-overexpressing iPrECs (AR-iPrEC), and human prostate adenocarcinoma LNCaP cells that stably overexpressed FASN for cell proliferation assays, soft agar assays, and tests of tumor formation in immunodeficient mice. Transgenic mice expressing FASN in the prostate were generated to assess the effects of FASN on prostate histology. Apoptosis was evaluated by Hoechst 33342 staining and by fluorescence-activated cell sorting in iPrEC-FASN cells treated with stimulators of the intrinsic and extrinsic pathways of apoptosis (ie, camptothecin and anti-Fas antibody, respectively) or with a small interfering RNA (siRNA) targeting FASN. FASN expression was compared with the apoptotic index assessed by the terminal deoxynucleotidyltransferase-mediated UTP end-labeling method in 745 human prostate cancer samples by using the least squares means procedure. All statistical tests were two-sided.
Forced expression of FASN in iPrECs, AR-iPrECs, and LNCaP cells increased cell proliferation and soft agar growth. iPrECs that expressed both FASN and androgen receptor (AR) formed invasive adenocarcinomas in immunodeficient mice (12 of 14 mice injected formed tumors vs 0 of 14 mice injected with AR-iPrEC expressing empty vector (P < .001, Fisher exact test); however, iPrECs that expressed only FASN did not. Transgenic expression of FASN in mice resulted in prostate intraepithelial neoplasia, the incidence of which increased from 10% in 8- to 16-week-old mice to 44% in mice aged 7 months or more (P = .0028, Fisher exact test), but not in invasive tumors. In LNCaP cells, siRNA-mediated silencing of FASN resulted in apoptosis. FASN overexpression protected iPrECs from apoptosis induced by camptothecin but did not protect iPrECs from Fas receptor-induced apoptosis. In human prostate cancer specimens, FASN expression was inversely associated with the apoptotic rate (mean percentage of apoptotic cells, lowest vs highest quartile of FASN expression: 2.76 vs 1.34, difference = 1.41, 95% confidence interval = 0.45 to 2.39, Ptrend = .0046).
These observations suggest that FASN can act as a prostate cancer oncogene in the presence of AR and that FASN exerts its oncogenic effect by inhibiting the intrinsic pathway of apoptosis.
[show abstract][hide abstract] ABSTRACT: Cancer is thought to develop from the neoplastic transformation of either stem cells that maintain the ability to self-renew
or committed progenitor cells that undergo dedifferentiation and acquire stem cell characteristics. Thus, understanding prostate
cell differentiation lineage during development as well as prostate epithelium renewal in adulthood represents a critical
step in unraveling the mechanisms involved in prostate carcinogenesis. Recent advances in the field have started to clarify
the hierarchical relationship between epithelial prostate cells. In addition, prostate cell populations with characteristics
of stem cells have been identified. Further clarification of the processes that regulate normal prostate homeostasis is likely
to shed additional light on the multistep process of prostate tumorigenesis.
Key WordsAdult–Prostate–Epithelium–Stem cells–Cancer–Development–Maintenance–Renewal
[show abstract][hide abstract] ABSTRACT: Transgenic expression of activated AKT1 in the murine prostate induces prostatic intraepithelial neoplasia (PIN) that does not progress to invasive prostate cancer (CaP). In luminal epithelial cells of Akt-driven PIN, we show the concomitant induction of p27(Kip1) and senescence. Genetic ablation of p27(Kip1) led to downregulation of senescence markers and progression to cancer. In humans, p27(Kip1) and senescence markers were elevated in PIN not associated with CaP but were decreased or absent, respectively, in cancer-associated PIN and in CaP. Importantly, p27(Kip1) upregulation in mouse and human in situ lesions did not depend upon mTOR or Akt activation but was instead specifically associated with alterations in cell polarity, architecture, and adhesion molecules. These data suggest that a p27(Kip1)-driven checkpoint limits progression of PIN to CaP.
Cancer cell 09/2008; 14(2):146-55. · 25.29 Impact Factor
[show abstract][hide abstract] ABSTRACT: The identification of stem cells and differentiation programs regulating the development and maintenance of the normal prostate epithelium is essential for the identification of the cell type(s) and molecular alterations involved in the development and propagation of prostate cancer (CaP). The p53-homologue p63 is highly expressed in normal prostate basal cells and is a clinically useful biomarker for the diagnosis of CaP. Importantly, p63 has been shown to play a critical role in prostate development. Recent experimental evidence also suggests that this gene is essential for normal stem cell function in the prostate as well as other epithelial organs. Future studies aimed at better defining the role of p63 in the renewal of the adult prostate epithelium are likely to shed new light on the mechanisms involved in prostate carcinogenesis.
Journal of Cellular Biochemistry 05/2008; 103(5):1354-68. · 3.06 Impact Factor
[show abstract][hide abstract] ABSTRACT: Germline von Hippel-Lindau tumour suppressor gene (VHL) mutations cause renal cell carcinomas, haemangioblastomas and phaeochromocytomas in humans. Mutations in VHL also occur in sporadic renal cell carcinomas. The protein encoded by VHL, VHL, is part of the ubiquitin ligase that downregulates the heterodimeric transcription factor Hif under well-oxygenated conditions. Here we show that acute VHL inactivation causes a senescent-like phenotype in vitro and in vivo. This phenotype was independent of p53 and Hif but dependent on the retinoblastoma protein (Rb) and the SWI2/SNF2 chromatin remodeller p400. Rb activation occurred through a decrease in Skp2 messenger RNA, which resulted in the upregulation of p27 in a Hif-independent fashion. Our results suggest that senescence induced by VHL inactivation is a tumour-suppressive mechanism that must be overcome to develop VHL-associated neoplasias.
[show abstract][hide abstract] ABSTRACT: Molecular mechanisms underlying prostate and urothelial development remain unclear. This situation presents major limitations in identifying the cell type(s) and molecular events involved in the development of prostate and bladder cancer. It has been shown that mice lacking the basal cell marker p63 present several epithelial defects, including epidermis and prostate buds agenesis and urothelial abnormalities. Here, we use the p63-/- mouse as a tool to define cell lineages in the prostate epithelium and urothelium. By complementing p63-/- blastocysts with p63+/+ beta-galactosidase (beta-gal)-positive ES cells, we show that secretory cells of the prostate originate from p63-positive basal progenitor cells. Importantly, our urogenital sinus transplantation studies demonstrate that p63 prevents intestinal differentiation of the urogenital sinus endoderm and is therefore required to maintain commitment to the prostate cell lineage. Finally, in contrast with the prostate findings, analysis of the urothelium from rescued p63-/- chimeras shows that umbrella (superficial) cells can develop and be maintained independently from p63-positive basal and intermediate cells.
Proceedings of the National Academy of Sciences 09/2005; 102(32):11355-60. · 9.74 Impact Factor