Citations

Abstract Purpose: Basal-like breast tumors are typically (ER/PR/HER2) triple-negative and are associated with a high incidence of brain metastases and poor clinical outcomes. The molecular chaperone αB-crystallin is predominantly expressed in triple-negative breast cancer (TNBC) and contributes to an aggressive tumor phenotype in preclinical models. We investigated the potential role of αB-crystallin in brain metastasis in TNBCs. Experimental Design: αB-crystallin expression in primary breast carcinomas and brain metastases was analyzed by immunohistochemistry among patients with breast cancer with brain metastases. αB-crystallin was overexpressed or silenced in two different TNBC cell lines. The effects on cell adhesion to human brain microvascular endothelial cells (HBMEC) or extracellular matrix proteins, transendothelial migration, and transmigration across a HBMEC/astrocyte coculture blood–brain barrier (BBB) model were examined. In addition, the effects of overexpressing or silencing αB-crystallin on brain metastasis in vivo were investigated using orthotopic TNBC models. Results: In a cohort of women with breast cancer brain metastasis, αB-crystallin expression in primary breast carcinomas was associated with poor overall survival and poor survival after brain metastasis, even among patients with TNBC. Stable overexpression of αB-crystallin in TNBC cells enhanced adhesion to HBMECs, transendothelial migration, and BBB transmigration in vitro, whereas silencing αB-crystallin inhibited these events. αB-crystallin promoted adhesion of TNBC cells to HBMECs, at least in part, through an α3β1 integrin–dependent mechanism. αB-crystallin overexpression promoted brain metastasis, whereas silencing αB-crystallin inhibited brain metastasis in orthotopic TNBC models. Conclusion: αB-crystallin is a novel regulator of brain metastasis in TNBC and represents a potential biomarker and drug target for this aggressive disease. Clin Cancer Res; 20(1); 56–67. ©2013 AACR.

Abstract Synthetic lethal interactions enable a novel approach for discovering specific genetic vulnerabilities in cancer cells that can be exploited for the development of therapeutics. Despite successes in model organisms such as yeast, discovering synthetic lethal interactions on a large scale in human cells remains a significant challenge. We describe a comparative genomic strategy for identifying cancer-relevant synthetic lethal interactions whereby candidate interactions are prioritized on the basis of genetic interaction data available in yeast, followed by targeted testing of candidate interactions in human cell lines. As a proof of principle, we describe two novel synthetic lethal interactions in human cells discovered by this approach, one between the tumor suppressor gene SMARCB1 and PSMA4, and another between alveolar soft-part sarcoma-associated ASPSCR1 and PSMC2. These results suggest therapeutic targets for cancers harboring mutations in SMARCB1 or ASPSCR1 and highlight the potential of a targeted, cross-species strategy for identifying synthetic lethal interactions relevant to human cancer. Cancer Res; 73(20); 6128–36. ©2013 AACR.

Abstract Recently, we have identified serum response factor (SRF) as a mediator of clinically relevant androgen receptor (AR) action in prostate cancer (PCa). Genes that rely on SRF for androgen-responsiveness represent a small fraction of androgen-regulated genes, but distinguish benign from malignant prostate and correlate with aggressive disease. Moreover, the SRF-AR expression signature is associated more strongly with biochemical recurrence than similarly sized sets of AREdriven AR target genes. Thus, understanding the mechanism(s) by which SRF conveys androgen effects to its target genes may provide novel opportunities to target clinically relevant androgen signaling. Here, we explore the role of the RhoA signaling axis, a well-known activating pathway upstream of SRF, in androgen activation of SRF action. PCa cells were treated with inhibitors of RhoA signaling or transfected with siRNAs targeting RhoA, the critical SRF cofactor MAL or control siRNAs in the presence or absence of the synthetic androgen R1881. Real-time RT-PCR and western blotting was done to assess effects on expression of SRF target genes. Cell fractionation experiments evaluated the cellular localization of AR, MAL and SRF. ChIP was performed to assess recruitment of MAL to SRF target genes. Wild-type, dominant-active and dominant-negative versions of RhoA were overexpressed to determine effects on androgen regulation of SRF target genes. Immunohistochemistry was done to evaluate RhoA expression in clinical PCa samples and a tissue microarray derived from a CWR22 PCa xenograft model that mimics progression from androgen-stimulated (AS) to castration-recurrent (CR) disease. Effects on AS and CR PCa cell biology were assessed using proliferation and migration assays. Here, we show that the small GTPase RhoA mediates androgen responsiveness of more than half of SRF target genes tested. Interference with expression of RhoA, activity of the RhoA effector RhoA-associated kinase (ROCK), and actin polymerization necessary for nuclear translocation of the SRF cofactor MAL, all prevented full androgen-regulation of SRF target genes. Androgen treatment increased the nuclear content of MAL and led to MAL recruitment to the promoter of the SRF target gene FHL2. Moreover, in clinical specimens RhoA expression was higher in PCa cells than benign prostate cells, and elevated RhoA expression levels were associated with aggressive disease features and decreased disease-free survival following radical prostatectomy. Overexpression of RhoA markedly increased the androgen responsiveness of select SRF target genes, in a manner that depends on its GTPase activity. Cell lines and a xenograft model that mimics the transition from AS to CR PCa indicate that RhoA levels are not altered during disease progression, suggesting that RhoA expression levels in the primary tumor determine disease aggressiveness. Silencing of RhoA, use of ROCK inhibitors or an inhibitor of SRF-MAL interaction blunted (androgen-regulated) cell viability and attenuated AS and CR PCa cell migration. Taken together, our work demonstrates that the RhoA signaling axis mediates clinically relevant AR action in PCa. In addition, these studies are the first to report on overexpression of RhoA in PCa and its association with aggressive disease and poor outcome. Note: This abstract was not presented at the conference because the presenter was unable to attend. Citation Format: Lucy Schmidt, Thomas Sebo, Donald Tindall, Hannelore Heemers, Kelly Duncan, Neelu Yadav, Kevin Regan, Christine Lohse, Elena Pop, Kristopher Attwood, Gregory Wilding, James Mohler. Androgen regulation of SRF target genes in prostate cancer cells is mediated in part by the small GTPase RhoA [abstract]. In: Proceedings of the AACR Special Conference on Advances in Prostate Cancer Research; 2012 Feb 6-9; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2012;72(4 Suppl):Abstract nr A8.

ObjectiveTo examine lipid profiles among statin‐naive patients with rheumatoid arthritis (RA) and those without RA before and after the initiation of statins.MethodsInformation regarding lipid measures and statin use was gathered in a population‐based incident cohort of patients with RA (1987 American College of Rheumatology criteria first met between January 1, 1988 and January 1, 2008) and in a cohort of non‐RA subjects from the same underlying population. Only patients with no prior history of statin use were included.ResultsThe study included 161 patients with RA (mean age 56.3 years, 57% female) and 221 non‐RA subjects (mean age 56.0 years, 66% female). Prior to the start of statins, the levels of total cholesterol and low‐density lipoprotein (LDL) cholesterol were lower in the RA versus the non‐RA cohort (P < 0.001 and P = 0.003, respectively). The absolute and percentage change in LDL cholesterol after at least 90 days of statin use tended to be smaller in the RA versus the non‐RA cohort (P = 0.03 and P = 0.09, respectively). After at least 90 days of statin use, patients with RA were less likely to achieve therapeutic goals for LDL cholesterol than the non‐RA subjects (P = 0.046). Increased erythrocyte sedimentation rate (ESR) at baseline (odds ratio 0.47, 95% confidence interval 0.26–0.85) was associated with lower likelihood of achieving therapeutic LDL goals.ConclusionPatients with RA had lower total cholesterol and LDL cholesterol levels before statin initiation and lower likelihood of achieving therapeutic LDL goals following statin use than the non‐RA subjects. Some RA disease characteristics, in particular ESR at baseline, may have an adverse impact on achieving therapeutic LDL goals.

ObjectiveTo study left ventricular (LV) geometry in patients with rheumatoid arthritis (RA) and no history of heart failure compared with that in subjects with neither RA nor a history of heart failure, and to determine the impact of RA on LV remodeling.MethodsA cross‐sectional, community‐based study was conducted among adult (age ≥50 years) patients with RA and age‐ and sex‐matched subjects with neither RA nor a history of heart failure. All participants underwent standard 2‐dimensional Doppler echocardiography. LV geometry was classified into the following 4 categories based on relative wall thickness and sex‐specific cutoffs for the LV mass index: concentric remodeling, concentric hypertrophy, eccentric hypertrophy, or normal geometry.ResultsAmong 200 patients with RA and 600 age‐ and sex‐matched subjects without RA, the mean age was 65 years, and 74% of the individuals in both cohorts were female. Compared with subjects without RA, patients with RA were significantly more likely to have abnormal LV geometry (odds ratio [OR] 1.44, 95% confidence interval [95% CI] 1.03–2.00), even after adjusting for cardiovascular risk factors and comorbidities. Among subjects with abnormal LV geometry, the odds of concentric LV remodeling were significantly increased in patients with RA (OR 4.73, 95% CI 2.85–7.83). In linear regression analyses, the LV mass index appeared to be lower in patients with RA who were currently receiving corticosteroids (β ± SE −0.082 ± 0.027, P = 0.002), even after adjusting for cardiovascular risk factors and comorbidities.ConclusionRA was strongly associated with abnormal LV remodeling (particularly concentric LV remodeling) among RA patients without heart failure. This association remained significant after adjustment for cardiovascular risk factors and comorbidities. RA disease–related factors may promote changes in LV geometry. The biologic mechanisms underlying LV remodeling warrant further investigation.

Objective. To examine the utility of the Framingham risk score (FRS) in estimating cardiovascular risk in psoriasis.Methods. We compared the predicted 10-year risk of cardiovascular events, namely, cardiovascular death, myocardial infarction, heart failure, percutaneous transluminal coronary angioplasty, and coronary artery bypass grafting using the FRS, to the observed risk of cardiovascular events in a population-based cohort of patients with psoriasis. Patients with incident or prevalent adult-onset psoriasis aged 30–79 years without prior history of cardiovascular disease were included.Results. Among the 1197 patients with predicted risk scores, the median FRS was 6.0%, while the observed 10-year cardiovascular risk was 6.9% (standardized incidence ratio (SIR): 1.14; 95% confidence interval (CI): 0.92–1.42). The SIR was not elevated for women nor for men. The differences between observed and predicted cardiovascular risks in patients <60 years (SIR: 1.01; 95% CI: 0.73–1.41) or ≥60 years (SIR: 1.26; 95% CI: 0.95–1.68) were not statistically significant.Conclusion. There was no apparent difference between observed and predicted cardiovascular risks in patients with psoriasis in our study. FRS reasonably estimated cardiovascular risk in both men and women as well as in younger and older psoriasis patients, suggesting that FRS can be used in risk stratification in psoriasis without further adjustment.

ObjectiveTo determine the incidence, time trends, risk factors, and severity of herpes zoster in a population‐based cohort of patients with newly diagnosed rheumatoid arthritis (RA) compared to a group of individuals without RA from the same population.MethodsAll residents of Olmsted County, Minnesota fulfilling for the first time the 1987 American College of Rheumatology criteria for RA between January 1, 1980 and December 31, 2007 and a cohort of similar residents without RA were assembled and followed by retrospective chart review until death, migration, or December 31, 2008.ResultsThere was no difference in the presence of herpes zoster prior to the RA incidence/index date between the cohorts (P = 0.85). During followup, 84 patients with RA (rate 12.1 cases per 1,000 person‐years) and 44 subjects without RA (rate 5.4 cases per 1,000 person‐years) developed herpes zoster. Patients with RA were more likely to develop herpes zoster than those without RA (hazard ratio [HR] 2.4 [95% confidence interval (95% CI) 1.7–3.5]). Herpes zoster occurred more frequently in patients diagnosed with RA more recently (HR 1.06 per year [95% CI 1.02–1.10]). Erosive disease, previous joint surgery, and use of hydroxychloroquine and corticosteroids were significantly associated with the development of herpes zoster in RA. There was no apparent association of herpes zoster with the use of methotrexate or biologic agents. Complications of herpes zoster occurred at a similar rate in both cohorts.ConclusionThe incidence of herpes zoster is increased in RA and has risen in recent years. There also has been an increasing incidence of herpes zoster in more recent years in the general population. RA disease severity is associated with the development of herpes zoster.

Background and objective Survival of patients with pancreatic adenocarcinoma is limited and few prognostic factors are known. We conducted a two-stage genome-wide association study (GWAS) to identify germline variants associated with survival in patients with pancreatic adenocarcinoma. Methods We analysed overall survival in relation to single nucleotide polymorphisms (SNPs) among 1005 patients from two large GWAS datasets, PanScan I and ChinaPC. Cox proportional hazards regression was used in an additive genetic model with adjustment for age, sex, clinical stage and the top four principal components of population stratification. The first stage included 642 cases of European ancestry (PanScan), from which the top SNPs (p≤10 −5 ) were advanced to a joint analysis with 363 additional patients from China (ChinaPC). Results In the first stage of cases of European descent, the top-ranked loci were at chromosomes 11p15.4, 18p11.21 and 1p36.13, tagged by rs12362504 (p=1.63×10 −7 ), rs981621 (p=1.65×10 −7 ) and rs16861827 (p=3.75×10 −7 ), respectively. 131 SNPs with p≤10 −5 were advanced to a joint analysis with cases from the ChinaPC study. In the joint analysis, the top-ranked SNP was rs10500715 (minor allele frequency, 0.37; p=1.72×10 −7 ) on chromosome 11p15.4, which is intronic to the SET binding factor 2 (SBF2) gene. The HR (95% CI) for death was 0.74 (0.66 to 0.84) in PanScan I, 0.79 (0.65 to 0.97) in ChinaPC and 0.76 (0.68 to 0.84) in the joint analysis. Conclusions Germline genetic variation in the SBF2 locus was associated with overall survival in patients with pancreatic adenocarcinoma of European and Asian ancestry. This association should be investigated in additional large patient cohorts.