A histologic diagnosis of seminoma at orchiectomy with an elevation in serum alpha-fetoprotein (AFP) indicates the likelihood of unrecognized NSGCT elements. We report the retroperitoneal histology of a contemporary series of patients with pure seminoma at orchiectomy with an elevation in serum AFP that were managed as NSGCT.
We identified 22 patients between 1989 and 2009 with pure seminoma diagnosed at orchiectomy with an elevated serum AFP (> 15 ng/ml) either pre- or post-orchiectomy. Retroperitoneal histology and relapse data are reported.
Median pre-orchiectomy and pre-chemotherapy serum AFP levels were 248 ng/ml (IQR 48, 4693) and 279 ng/ml (IQR 66, 5311), respectively. Percentage of patients with clinical stage I, II, and III was 5%, 50%, and 45%, respectively. Percentage of patients with IGCCCG good, intermediate, and poor risk status was 32%, 32%, and 36%, respectively. Twenty-one patients had induction chemotherapy followed by PC-RPLND. Overall, 67% of patients had NSGCT elements in the retroperitoneum. Histologic findings were pure teratoma in 38%, malignant transformation in 14%, and viable NSGCT in 14%. Fifty-nine percent had some component of teratoma in the RP. One patient (5%) had any seminoma in the RP, but this patient also had RP teratoma. Seven patients relapsed and received salvage chemotherapy. Actuarial relapse free survival at 5 and 10 years was 76% and 61% reflecting a high percentage of patients with stage II/III disease.
Pure seminoma at orchiectomy with an elevated serum AFP portends a high likelihood of harboring NSGCT elements in the RP.
testicular cancer; seminoma; AFP; RPLND
Lymph node counts are a measure of quality assurance and are associated with prognosis for numerous malignancies. To date, investigations of lymph node counts in testis cancer are lacking.
Using the Memorial Sloan-Kettering Testis Cancer Database, we identified 255 patients treated with primary retroperitoneal lymph node dissection (RPLND) for nonseminomatous germ cell tumors (NSGCT) between 1999 and 2008. Features associated with node counts, positive nodes, number of positive nodes, and risk of positive contralateral nodes were evaluated with regression models.
Median (IQR) total node count was 38 (27–53) and was 48 (34 – 61) during the most recent 5 years. Features associated with higher node count on multivariate analysis included high volume surgeon (p=0.034), clinical stage (p=0.036), and more recent year of surgery (p<0.001) while pathologist was not significantly associated with node count (p=0.3). Clinical stage (p<0.001) and total node count (p=0.045) were significantly associated with finding positive nodes on multivariate analysis. The probability of finding positive nodes were 23%, 23%, 31%, and 48% if the total node count was <21, 21 – 40, 41 – 60, and >60, respectively. With a median follow-up of 3.0 years all patients were still alive and 16 patients relapsed while no patient relapsed in the paracaval, interaortocaval, paraaortic, or iliac regions.
Our results suggest that >40 lymph nodes removed at RPLND improves the diagnostic efficacy of the operation. These results will be useful for future trials comparing RPLND, especially when assessing the adequacy of lymph node dissection.
Testicular neoplasms; Lymph nodes; Lymph node excision; Neoplasm staging
Lymph node counts are a proposed measure of quality assurance for numerous malignancies. Investigation of patient factors associated with lymph node counts are lacking. We sought to determine if body mass index (BMI) is associated with lymph node counts in patients treated with a primary retroperitoneal lymph node dissection (RPLND).
Using the Memorial Sloan-Kettering Testis Cancer Database, we identified 255 patients treated with a primary RPLND for nonseminomatous germ cell tumors (NSGCT) from 1999–2008. The associations between BMI and node counts were evaluated using linear regression models in univariate and multivariable models adjusting for features reported to predict higher node counts (year of surgery, stage, and surgeon volume).
Median BMI (IQR) was 26.1 (23.4 – 28.7) and median (IQR) total node count was 38 (27–53). Median total node count for patients with a BMI <25, 25–<30, and >30 was 35, 42, and 44 nodes, respectively. In a univariate analysis, higher BMI was significantly associated with higher total node counts (coefficient 0.7 nodes for each 1 unit increase in BMI; p=0.026). Features associated with higher node count on multivariate analysis included high volume surgeon (p=0.047), pathologic stage (p=0.017), more recent year of surgery (p<0.001), and higher BMI (p=0.009).
Our results suggest for the first time that BMI is independently associated with higher lymph node counts during a lymph node dissection. If confirmed by others, these results may be important when using lymph node counts as a surrogate for adequacy of a lymph node dissection.
Testicular neoplasms; Lymph nodes; Lymph node excision; Neoplasm staging; Body mass index
Stem rust has become a renewed threat to global wheat production after the emergence and spread of race TTKSK (also known as Ug99) and related races from Africa. To elucidate U.S. winter wheat resistance genes to stem rust, association mapping was conducted using a panel of 137 lines from cooperative U.S. winter wheat nurseries from 2008 and simple sequence repeat (SSR) and sequence tagged site (STS) markers across the wheat genome. Seedling infection types were evaluated in a greenhouse experiment using six U.S. stem rust races (QFCSC, QTHJC, RCRSC, RKQQC, TPMKC and TTTTF) and TTKSK, and adult plant responses to bulked U.S. races were evaluated in a field experiment. A linearization algorithm was used to convert the qualitative Stakman scale seedling infection types for quantitative analysis. Association mapping successfully detected six known stem rust seedling resistance genes in U.S. winter wheat lines with frequencies: Sr6 (12%), Sr24 (9%), Sr31 (15%), Sr36 (9%), Sr38 (19%), and Sr1RSAmigo (8%). Adult plant resistance gene Sr2 was present in 4% of lines. SrTmp was postulated to be present in several hard winter wheat lines, but the frequency could not be accurately determined. Sr38 was the most prevalent Sr gene in both hard and soft winter wheat and was the most effective Sr gene in the adult plant field test. Resistance to TTKSK was associated with nine markers on chromosome 2B that were in linkage disequilibrium and all of the resistance was attributed to the Triticum timopheevii chromosome segment carrying Sr36. Potential novel rust resistance alleles were associated with markers Xwmc326-203 on 3BL, Xgwm160-195 and Xwmc313-225 on 4AL near Sr7, Xgwm495-182 on 4BL, Xwmc622-147 and Xgwm624-146 on 4DL, and Xgwm334-123 on 6AS near Sr8. Xwmc326-203 was associated with adult plant resistance to bulked U.S. races and Xgwm495-182 was associated with seedling resistance to TTKSK.
Lrf has been previously described as a powerful proto-oncogene. Here we surprisingly demonstrate that Lrf plays a critical oncosuppressive role in the prostate. Prostate specific inactivation of Lrf leads to a dramatic acceleration of Pten-loss-driven prostate tumorigenesis through a bypass of Pten-loss-induced senescence (PICS). We show that LRF physically interacts with and functionally antagonizes SOX9 transcriptional activity on key target genes such as MIA, which is involved in tumor cell invasion, and H19, a long non-coding RNA precursor for an Rb-targeting miRNA. Inactivation of Lrf in vivo leads to Rb down-regulation, PICS bypass and invasive prostate cancer. Importantly, we found that LRF is genetically lost, as well as down-regulated at both the mRNA and protein levels in a subset of human advanced prostate cancers. Thus, we identify LRF as a context-dependent cancer gene that can act as an oncogene in some contexts but also displays oncosuppressive-like activity in Pten−/− tumors.
Recent observations suggest that surgeon volume is associated with lymph node counts during retroperitoneal lymph node dissection (RPLND). We report our contemporary single-surgeon experience with lymph node counts during primary RPLND for nonseminomatous germ cell tumors (NSGCT).
Using the Memorial Sloan-Kettering Testis Cancer Database, we identified 124 consecutive patients treated with primary RPLND by a single experienced surgeon for NSGCT between 2004 and 2008. Predictors of positive nodes and number of positive nodes were evaluated with logistic and linear regression models adjusting for year of surgery and clinical stage.
Positive lymph nodes were observed in 37 (30%) while 87 (70%) patients were pN0. Mean total node count was 51 (SD= 23) during the 5 year study period. Mean node counts for the paracaval, interaortocaval, and paraaortic regions were 8 (SD= 6), 17 (SD= 9), and 26 (SD= 15), respectively. In a multivariate analysis, higher total node count was significantly associated with finding positive nodes (odds ratio 1.02 for each additional node counted; p=0.037) and finding multiple positive nodes (coefficient 0.04 for each additional node counted; p=0.004). Year of surgery (p<0.001) was associated with higher total node counts, while clinical stage and pathologist were not (p>0.5 for each).
The average total node count for a primary RPLND by an experienced surgeon is approximately 50 nodes with nearly half of the nodes originating in the paraaortic region. These results will be useful when assessing the adequacy of lymph node dissections for testis, renal, and upper tract urothelial malignancies.
Testicular neoplasms; Lymph node excision; Neoplasm staging; Retroperitoneal space; Lymph nodes
We demonstrate that the androgen receptor (AR) regulates a transcriptional program of DNA repair genes that promotes prostate cancer radioresistance, providing a potential mechanism by which androgen deprivation therapy (ADT) synergizes with ionizing radiation (IR). Using a model of castration-resistant prostate cancer, we show that second-generation antiandrogen therapy results in downregulation of DNA repair genes. Next, we demonstrate that primary prostate cancers display a significant spectrum of AR transcriptional output which correlates with expression of a set of DNA repair genes. Employing RNA-seq and ChIP-seq, we define which of these DNA repair genes are both induced by androgen and represent direct AR targets. We establish that prostate cancer cells treated with IR plus androgen demonstrate enhanced DNA repair and decreased DNA damage and furthermore that antiandrogen treatment causes increased DNA damage and decreased clonogenic survival. Finally, we demonstrate that antiandrogen treatment results in decreased classical non-homologous end joining.
Studies of ETS-mediated prostate oncogenesis have been hampered by the lack of suitable experimental systems. Here we describe a new conditional mouse model which gives robust, homogenous ERG expression throughout the prostate. When combined with homozygous Pten loss, mice developed accelerated, highly penetrant invasive prostate cancer. In mouse prostate tissue, ERG significantly increased androgen receptor (AR) binding. Robust ERG-mediated transcriptional changes, observed only in the setting of Pten loss, included restoration of AR transcriptional outut and genes involved in cell death, migration, inflammation and angiogenesis. Similarly, ETV1 positively regulated AR cistrome and transcriptional output in ETV1-translocated, PTEN-deficient human prostate cancer cells. In two large clinical cohorts, ERG and ETV1 expression correlated with higher AR transcriptional output in PTEN-negative prostate cancer specimens. We propose that ETS factors cause prostate-specific transformation by altering the AR cistrome, priming the prostate epithelium to respond to aberrant upstream signals such as PTEN loss.
The ability of seed to germinate under favorable environmental conditions is critical for seedling emergence, plant establishment, subsequent development and growth of adult plants, and it is controlled by internal genetic factors and external environmental factors. Winter wheat in the southern Great Plains is often planted six weeks before the optimal planting date to produce more biomass for cattle grazing during the winter season. A high seed germination rate in this higher soil temperature environment is required for this specific management system. In this study, a major QTL for temperature-sensitive germination was mapped on the short arm of chromosome 3A (QTsg.osu-3A) in a RIL population generated from two winter wheat cultivars. Furthermore, TaMFT-A1, previously reported to regulate seed dormancy and pre-harvest sprouting in spring wheat cultivars, was mapped tightly associated with the peak of QTsg.osu-3A. However, allelic variation in TaMFT-A1 between the two winter wheat cultivars differed from that was observed in spring wheat cultivars. There were 87 SNPs (single nucleotide polymorphisms) and 12 indels (insertions/deletions) in TaMFT-A1 between the Jagger allele for high germination and the 2174 allele for low germination in the after-ripened seeds, in comparison with 2 SNPs between the two alleles for differential pre-harvest sprouting in spring wheat cultivars. The Jagger TaMFT-A1 allele is a novel haplotype and appears extensively in winter wheat cultivars. TaMFT-A1 transcript levels were up-regulated by high temperature but down-regulated by low temperature or seed storage time. These findings suggest that TaMFT-A1 may invoke different mechanisms for controlling seed dormancy/germination among winter wheat cultivars.
Hessian fly (Mayetiola destructor) is one of the most destructive pests of wheat. The genes encoding 12-oxo-phytodienoic acid reductase (OPR) and lipoxygenase (LOX) play critical roles in insect resistance pathways in higher plants, but little is known about genes controlling resistance to Hessian fly in wheat.
In this study, 154 F6:8 recombinant inbred lines (RILs) generated from a cross between two cultivars, ‘Jagger’ and ‘2174’ of hexaploid wheat (2n = 6 × =42; AABBDD), were used to map genes associated with resistance to Hessian fly. Two QTLs were identified. The first one was a major QTL on chromosome 1A (QHf.osu-1A), which explained 70% of the total phenotypic variation. The resistant allele at this locus in cultivar 2174 could be orthologous to one or more of the previously mapped resistance genes (H9, H10, H11, H16, and H17) in tetraploid wheat. The second QTL was a minor QTL on chromosome 2A (QHf.osu-2A), which accounted for 18% of the total phenotypic variation. The resistant allele at this locus in 2174 is collinear to an Yr17-containing-fragment translocated from chromosome 2N of Triticum ventricosum (2n = 4 × =28; DDNN) in Jagger. Genetic mapping results showed that two OPR genes, TaOPR1-A and TaOPR2-A, were tightly associated with QHf.osu-1A and QHf.osu-2A, respectively. Another OPR gene and three LOX genes were mapped but not associated with Hessian fly resistance in the segregating population.
This study has located two major QTLs/genes in bread wheat that can be directly used in wheat breeding programs and has also provided insights for the genetic association and disassociation of Hessian fly resistance with OPR and LOX genes in wheat.
Hessian fly resistance; Insect resistance pathway; lipoxygenase (LOX); 12-oxophytodienoic acid reductase (OPR); Quantitative trait loci (QTL); Wheat
We evaluated clinical parameters associated with recovery of ejaculation following nerve-sparing post-chemotherapy retroperitoneal lymph node dissection (PC-RPLND) for non-seminomatous germ cell tumor.
We queried our institutional database for all patients who underwent nerve-sparing PC-RPLND between 1995 and 2005 using a bilateral template. Nerve-sparing was carried out whenever technically feasible and oncologically prudent. Antegrade ejaculation was defined as any seminal fluid expulsion and was determined by patient report. We evaluated recovery of antegrade ejaculation based on clinical and pathologic parameters and fit a logistic regression model to determine which pre-operative variables are associated with antegrade ejaculation.
A total of 341 patients had PC-RPLND during the study period, 136 (40%) with nerve sparing techniques. Post-operative antegrade ejaculation was reported by 107/136 (79%) of patients with information available. On the multivariable analysis, a right-sided primary testicular tumor (OR 0.4, 95% CI: 0.1, 1.0, p=0.044) and residual masses ≥5 cm (OR 0.1, 95% CI: 0.0, 0.7, p=0.020) were associated with retrograde ejaculation. However, 40/54 (74%) with right-sided primary tumors and 4/9 (44%) with mass ≥5 cm reported antegrade ejaculation. The 5-year relapse free survival was 98% with a median follow up of 39 months (IQR 19, 66).
Nerve-sparing PC-RPLND is associated with excellent functional return of antegrade ejaculation, is feasible in select patients with bulky disease, and has excellent oncologic outcomes.
Testicular Cancer; Chemotherapy; Surgery; Ejaculation; Retroperitoneal Lymph Node Dissection
Following the multidisciplinary management of metastatic germ cell tumor, approximately 10 to 15% of patients with the histologic finding of fibrosis or teratoma will suffer disease recurrence. We evaluated the prognostic significance of the total number of lymph nodes obtained at post-chemotherapy retroperitoneal lymph node dissection (PC-RPLND).
Materials and Methods
From 1989 to 2006, a total of 628 patients underwent PC-RPLND and were found to have either fibrosis or teratoma. Following Institutional Review Board approval, complete clinical and pathologic data were obtained from our prospective testis cancer surgical database. A Cox proportional hazards regression model was constructed to evaluate the association of the total number of lymph nodes obtained at PC-RPLND on disease recurrence.
On pathologic evaluation, 248 (57%) patients had fibrosis and 184 (43%) patients had teratoma. The median number of lymph nodes resected was 25 (IQ range 15, 37). On multivariable analysis, increasing post-chemotherapy nodal size and decreasing lymph node counts were significant predictors of disease recurrence (p=0.01, 0.04, respectively). For patients with 10 nodes removed, the predicted 2 year relapse free probability was 90%, compared to 97% when 50 nodes were removed.
Our data suggests that the total number of lymph nodes removed and analyzed is an independent predictor of disease recurrence following PC-RPLND. This has implications both for the urologist to assure completeness of resection and for the pathologist to meticulously assess the pathologic specimens.
testis cancer; surgery; chemotherapy; lymph node count
The contextual signals that regulate the expansion of prostate tumor progenitor cells are poorly defined. We found that a significant fraction of advanced human prostate cancers and castration-resistant metastases express high levels of the β4 integrin, which binds to laminin-5. Targeted deletion of the signaling domain of β4 inhibited prostate tumor growth and progression in response to loss of p53 and Rb function in a mouse model of prostate cancer (PB-TAg mice). Additionally, it suppressed Pten loss-driven prostate tumorigenesis in tissue recombination experiments. We traced this defect back to an inability of signaling-defective β4 to sustain self-renewal of putative cancer stem cells in vitro and proliferation of transit-amplifying cells in vivo. Mechanistic studies indicated that mutant β4 fails to promote transactivation of ErbB2 and c-Met in prostate tumor progenitor cells and human cancer cell lines. Pharmacological inhibition of ErbB2 and c-Met reduced the ability of prostate tumor progenitor cells to undergo self-renewal in vitro. Finally, we found that β4 is often coexpressed with c-Met and ErbB2 in human prostate cancers and that combined pharmacological inhibition of these receptor tyrosine kinases exerts antitumor activity in a mouse xenograft model. These findings indicate that the β4 integrin promotes prostate tumorigenesis by amplifying ErbB2 and c-Met signaling in tumor progenitor cells.
Hyper-activation of the PI 3-Kinase/AKT pathway is a driving force of many cancers. Here we identify the AKT-inactivating phosphatase PHLPP1 as a prostate tumor suppressor. We show that Phlpp1-loss causes neoplasia and, upon partial Pten-loss, carcinoma in mouse prostate. This genetic setting initially triggers a growth suppressive response via p53 and the Phlpp2 ortholog, and reveals spontaneous Trp53 inactivation as a condition for full-blown disease. Surprisingly, the co-deletion of PTEN and PHLPP1 in patient samples is highly restricted to metastatic disease and tightly correlated to deletion of TP53 and PHLPP2. These data establish a conceptual framework for progression of PTEN-mutant prostate cancer to life-threatening disease.
There is significant need to identify novel prostate cancer drug targets because current hormone therapies eventually fail, leading to a drug-resistant and fatal disease termed castration-resistant prostate cancer. To functionally identify genes that, when silenced, decrease prostate cancer cell proliferation or induce cell death in combination with antiandrogens, we employed an RNA interference-based short hairpin RNA barcode screen in LNCaP human prostate cancer cells. We identified and validated four candidate genes (AKT1, PSMC1, STRADA, and TTK) that impaired growth when silenced in androgen receptor positive prostate cancer cells and enhanced the antiproliferative effects of antiandrogens. Inhibition of AKT with a pharmacologic inhibitor also induced apoptosis when combined with antiandrogens, consistent with recent evidence for PI3K and AR pathway crosstalk in prostate cancer cells. Recovery of hairpins targeting a known prostate cancer pathway validates the utility of shRNA library screening in prostate cancer as a broad strategy to identify new candidate drug targets.
Numerous technical modifications to radical prostatectomy have been proposed. Such modifications are likely to lead to only slight improvements in outcomes. Although small differences would be worthwhile, an appropriately powered randomized trial would need to be very large, and thus of doubtful feasibility given the expense, complexity and regulatory burden of contemporary clinical trials. We have proposed a novel methodology, the clinically-integrated randomized trial, which dramatically streamlines trial procedures in order to reduce the marginal cost of an additional patient towards zero. We aimed to determine the feasibility of implementing such a trial for radical prostatectomy.
Patients undergoing radical prostatectomy as initial treatment for prostate cancer were randomized in a factorial design to involvement of the fascia during placement of the anastomotic sutures, urethral irrigation, both or neither. Endpoint data were obtained from routine clinical documentation. Accrual and compliance rates were monitored to determine the feasibility of the trial.
From a total of 260 eligible patients, 154 (59%) consented; 56 patients declined to participate, 20 were not approached on recommendation of the treating surgeon, and 30 were not approached for logistical reasons. Although recording by surgeons of the procedure used was incomplete (~80%), compliance with randomization was excellent when it was recorded, with only 6% of procedures inconsistent with allocation. Outcomes data was received from 71% of patients at one year. This improved to 83% as the trial progressed.
A clinically-integrated randomized trial was conducted at low cost, with excellent accrual, and acceptable compliance with treatment allocation and outcomes reporting. This demonstrates the feasibility of the methodology. Improved methods to ensure documentation of surgical procedures would be required before wider implementation.
Randomized controlled trials; surgery; research design; prostate cancer
Prostate cancer is characterized by its dependence on androgen receptor and frequent activation of PI3K signaling. We find that AR transcriptional output is decreased in human and murine tumors with PTEN deletion and that PI3K pathway inhibition activates AR signaling by relieving feedback inhibition of HER kinases. Similarly, AR inhibition activates AKT signaling by reducing levels of the AKT phosphatase PHLPP. Thus, these two oncogenic pathways cross-regulate each other by reciprocal feedback. Inhibition of one activates the other, thereby maintaining tumor cell survival. However, combined pharmacologic inhibition of PI3K and AR signaling caused near complete prostate cancer regressions in a Pten-deficient murine prostate cancer model and in human prostate cancer xenografts, indicating that both pathways coordinately support survival.
The two most frequently activated signaling pathways in prostate cancer are driven by AR and PI3K. Inhibitors of the PI3K pathway are in early clinical trials and AR inhibitors confer clinical responses in most patients. However, these inhibitors rarely induce tumor regression in preclinical models. Here we show that these pathways regulate each other by reciprocal negative feedback, such that inhibition of one activates the other. Therefore, tumor cells can adapt and survive when either single pathway is inhibited pharmacologically. Our demonstration of profound tumor regressions with combined pathway inhibition in preclinical prostate tumor models provides rationale for combination therapy in patients.
The canonical role of messenger RNA (mRNA) is to deliver protein-coding information to sites of protein synthesis. However, given that microRNAs bind to RNAs, we hypothesized that RNAs possess a biological role in cancer cells that relies upon their ability to compete for microRNA binding and is independent of their protein-coding function. As a paradigm for the protein-coding-independent role of RNAs, we describe the functional relationship between the mRNAs produced by the PTEN tumour suppressor gene and its pseudogene (PTENP1) and the critical consequences of this interaction. We find that PTENP1 is biologically active as determined by its ability to regulate cellular levels of PTEN, and that it can exert a growth-suppressive role. We also show that PTENP1 locus is selectively lost in human cancer. We extend our analysis to other cancer-related genes that possess pseudogenes, such as oncogenic KRAS. Further, we demonstrate that the transcripts of protein coding genes such as PTEN are also biologically active. Together, these findings attribute a novel biological role to expressed pseudogenes, as they can regulate coding gene expression, and reveal a non-coding function for mRNAs.
Annotation of prostate cancer genomes provides a foundation for discoveries that can impact disease understanding and treatment. Concordant assessment of DNA copy number, mRNA expression, and focused exon resequencing in 218 prostate cancer tumors identified the nuclear receptor coactivator NCOA2 as an oncogene in ~11 percent of tumors. Additionally, the androgen-driven TMPRSS2-ERG fusion was associated with a previously unrecognized, prostate-specific deletion at chromosome 3p14 that implicates FOXP1, RYBP and SHQ1 as potential cooperative tumor suppressors. DNA copy-number data from primary tumors revealed that copy-number alterations robustly define clusters of low- and high-risk disease beyond that achieved by Gleason score. The genomic and clinical outcome data from these patients is now made available as a public resource.
MYC and phosphoinositide 3-kinase (PI3K)-pathway deregulation are common in human prostate cancer. Through examination of 194 human prostate tumors, we observed statistically significant co-occurrence of MYC amplification and PI3K-pathway alteration, raising the possibility that these two lesions cooperate in prostate cancer progression. To investigate this, we generated bigenic mice in which both activated human AKT1 and human MYC are expressed in the prostate (MPAKT/Hi-MYC model). In contrast to mice expressing AKT1 alone (MPAKT model) or MYC alone (Hi-MYC model), the bigenic phenotype demonstrates accelerated progression of mouse prostate intraepithelial neoplasia (mPIN) to microinvasive disease with disruption of basement membrane, significant stromal remodeling and infiltration of macrophages, B- and T-lymphocytes, similar to inflammation observed in human prostate tumors. In contrast to the reversibility of mPIN lesions in young MPAKT mice after treatment with mTOR inhibitors, Hi-MYC and bigenic MPAKT/Hi-MYC mice were resistant. Additionally, older MPAKT mice showed reduced sensitivity to mTOR inhibition, suggesting that additional genetic events may dampen mTOR dependence. Since increased MYC expression is an early feature of many human prostate cancers, these data have implications for treatment of human prostate cancers with PI3K-pathway alterations using mTOR inhibitors.
Single nucleotide polymorphisms (SNPs) are ideally suited for the construction of high-resolution genetic maps, studying population evolutionary history and performing genome-wide association mapping experiments. Here, we used a genome-wide set of 1536 SNPs to study linkage disequilibrium (LD) and population structure in a panel of 478 spring and winter wheat cultivars (Triticum aestivum) from 17 populations across the United States and Mexico.
Most of the wheat oligo pool assay (OPA) SNPs that were polymorphic within the complete set of 478 cultivars were also polymorphic in all subpopulations. Higher levels of genetic differentiation were observed among wheat lines within populations than among populations. A total of nine genetically distinct clusters were identified, suggesting that some of the pre-defined populations shared significant proportion of genetic ancestry. Estimates of population structure (FST) at individual loci showed a high level of heterogeneity across the genome. In addition, seven genomic regions with elevated FST were detected between the spring and winter wheat populations. Some of these regions overlapped with previously mapped flowering time QTL. Across all populations, the highest extent of significant LD was observed in the wheat D-genome, followed by lower LD in the A- and B-genomes. The differences in the extent of LD among populations and genomes were mostly driven by differences in long-range LD ( > 10 cM).
Genome- and population-specific patterns of genetic differentiation and LD were discovered in the populations of wheat cultivars from different geographic regions. Our study demonstrated that the estimates of population structure between spring and winter wheat lines can identify genomic regions harboring candidate genes involved in the regulation of growth habit. Variation in LD suggests that breeding and selection had a different impact on each wheat genome both within and among populations. The higher extent of LD in the wheat D-genome versus the A- and B-genomes likely reflects the episodes of recent introgression and population bottleneck accompanying the origin of hexaploid wheat. The assessment of LD and population structure in this assembled panel of diverse lines provides critical information for the development of genetic resources for genome-wide association mapping of agronomically important traits in wheat.
One reported function of the tumor suppressor p19Arf is to stabilize p53, providing a critical checkpoint in the response to oncogenic insults. Acute loss of Pten leads to an increase in the abundance of p19Arf, p53, and p21 proteins as part of a fail-safe senescence response. Here, we report that loss of p19Arf in prostate epithelium does not accelerate—but rather partially inhibits—the prostate cancer phenotype of Pten-deficient mice. Moreover, cellular senescence and a further decrease in the number of pre-neoplastic glands were observed in prostates of the Pten-p19Arf double-mutant mice. In both prostate epithelium and primary mouse embryo fibroblasts (MEFs), the increase in p53 protein abundance found upon loss of Pten was unaffected by the simultaneous loss of p19Arf. However, in contrast to that in the prostate epithelium, p19Arf deficiency in MEFs lacking Pten abolished cell senescence and promoted hyperproliferation and transformation despite the unabated increase in p53 abundance. Consistent with the effect of p19Arf loss in Pten-deficient mouse prostate, we found that in human prostate cancers, loss of PTEN was not associated with loss of p14ARF (the human equivalent of mouse p19Arf). Collectively, these data reveal differential consequences of p19Arf inactivation in prostate cancer and MEFs upon Pten loss that are independent of the p53 pathway.
The TMPRSS2-ERG fusion, present in 50% of prostate cancers, is less common in prostatic intra-epithelial neoplasia (PIN), raising questions about whether TMPRSS2-ERG contributes to disease initiation. We identified the translational start site of a common TMPRSS2-ERG fusion and showed that transgenic TMPRSS2-ERG mice develop PIN, but only in the context of PI3-kinase pathway activation. TMPRSS2-ERG positive human tumors are also enriched for PTEN loss, suggesting cooperation in prostate tumorigenesis.
Chromosomal translocations involving the ERG locus are frequent events observed in human prostate cancer pathogenesis, however the biologic role of ERG aberrant expression is controversial.1 Here we demonstrate that the aberrant expression of ERG is a progression event in prostate tumorigenesis. We find that prostate cancer specimens containing the TMPRSS2:ERG genetic rearrangement are significantly enriched for loss of the tumor suppressor PTEN. In concordance with these findings, over-expression of ERG in the transgenic mouse prostate promotes a marked acceleration and progression of HGPIN to prostatic adenocarcinoma in a Pten heterozygous background. In vitro over-expression of ERG promotes cell migration, a property necessary for tumorigenesis, without affecting proliferation. ADAMTS1 and CXCR4, two candidate genes strongly associated with cell migration are found up-regulated in the presence of ERG over-expression. Thus, ERG plays a distinct role in prostate cancer progression and cooperates with PTEN haploinsufficiency to promote progression of HGPIN to invasive adenocarcinoma.