Citations

Bone atrophy and its related fragility fractures are frequent, late side effects of radiotherapy in cancer survivors and have a detrimental impact on their quality of life. In another study, we showed that parathyroid hormone 1‐34 and anti‐sclerostin antibody attenuates radiation‐induced bone damage by accelerating DNA repair in osteoblasts. DNA damage responses are partially regulated by the ubiquitin proteasome pathway. In the current study, we examined whether proteasome inhibitors have similar bone‐protective effects against radiation damage. MG132 treatment greatly reduced radiation‐induced apoptosis in cultured osteoblastic cells. This survival effect was owing to accelerated DNA repair as revealed by γH2AX foci and comet assays and to the up‐regulation of Ku70 and DNA‐dependent protein kinase, catalytic subunit, essential DNA repair proteins in the nonhomologous end‐ joining pathway. Administration of bortezomib (Bzb) reversed the loss of trabecular bone structure and strength in mice at 4 wk after focal radiation. Histomorphometry revealed that Bzb significantly increased the number of osteoblasts and activity in the irradiated area and suppressed the number and activity of osteoclasts, regardless of irradiation. Two weeks of Bzb treatment accelerated DNA repair in bone‐lining osteoblasts and thus promoted their survival. Meanwhile, it also inhibited bone marrow adiposity. Taken together, we demonstrate a novel role of proteasome inhibitors in treating radiation‐induced osteoporosis.—Chandra, A., Wang, L., Young, T., Zhong, L., Tseng, W.‐J., Levine, M. A., Cengel, K., Liu, X. S., Zhang, Y., Pignolo, R. J., Qin, L. Proteasome inhibitor bortezomib is a novel therapeutic agent for focal radiation‐induced osteoporosis. FASEB J. 32, 52‐62 (2018). www.fasebj.org

Abstract Prostate cancer is the most frequently diagnosed male cancer. For prostate cancer that has progressed to an advanced or metastatic stage, androgen deprivation therapy (ADT) is the standard of care. ADT inhibits activity of the androgen receptor (AR), a master regulator transcription factor in normal and cancerous prostate cells. The major limitation of ADT is the development of castration-resistant prostate cancer (CRPC), which is almost invariably due to transcriptional re-activation of the AR. One mechanism of AR transcriptional re-activation is expression of AR-V7, a truncated, constitutively active AR variant (AR-V) arising from alternative AR pre-mRNA splicing. Noteworthy, AR-V7 is being developed as a predictive biomarker of primary resistance to androgen receptor (AR)-targeted therapies in CRPC. Multiple additional AR-V species are expressed in clinical CRPC, but the extent to which these may be co-expressed with AR-V7 or predict resistance is not known. Here we utilized long read sequencing to identify and quantify AR isoforms expressed in CRPC. To unambiguously characterize all AR isoforms, we prepared Iso-Seq™ libraries via 3’ rapid amplification of cDNA ends (RACE) with RNA isolated from prostate cancer cell lines and xenograft tissues using a forward primer anchored in AR exon 1. 3’RACE reactions were subjected to single molecule, real-time (SMRT®) long-read sequencing with a Pacific Biosciences RSII System. Our work identified AR-V9 as a truncated isoform that is frequently co-expressed with AR-V7 in CRPC. Mechanistically, our work re-annotated AR-V7 and AR-V9 mRNAs, showing these two species shared a common 3’ terminal exon containing separate splice acceptor sites. Taking into account this new information, novel siRNAs and antibodies which could distinguish between AR-V7 and AR-V9 were designed, validated and used to measure the relative expression of these two AR isoforms in CRPC cells with a view to determining the potential of AR-V9 as a predictive biomarker of primary resistance to AR-targeted therapies. Citation Format: Manish Kohli, Yeung Ho, David W. Hillman, Jamie L. Van Etten, Christine Henzler, Rendong Yang, Yingming Li, Elizabeth Tseng, Ting Hon, Tyson A. Clark, Liguo Wang, Kevin Silverstein, Liewei Wang, Scott M. Dehm. SMRT® Sequencing of full-length androgen receptor isoforms in prostate cancer reveals previously hidden drug resistant variants [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2017; 2017 Apr 1-5; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2017;77(13 Suppl):Abstract nr 425. doi:10.1158/1538-7445.AM2017-425

Abstract Purpose: Androgen receptor (AR) variant AR-V7 is a ligand-independent transcription factor that promotes prostate cancer resistance to AR-targeted therapies. Accordingly, efforts are under way to develop strategies for monitoring and inhibiting AR-V7 in castration-resistant prostate cancer (CRPC). The purpose of this study was to understand whether other AR variants may be coexpressed with AR-V7 and promote resistance to AR-targeted therapies. Experimental Design: We utilized complementary short- and long-read sequencing of intact AR mRNA isoforms to characterize AR expression in CRPC models. Coexpression of AR-V7 and AR-V9 mRNA in CRPC metastases and circulating tumor cells was assessed by RNA-seq and RT-PCR, respectively. Expression of AR-V9 protein in CRPC models was evaluated with polyclonal antisera. Multivariate analysis was performed to test whether AR variant mRNA expression in metastatic tissues was associated with a 12-week progression-free survival endpoint in a prospective clinical trial of 78 CRPC-stage patients initiating therapy with the androgen synthesis inhibitor, abiraterone acetate. Results: AR-V9 was frequently coexpressed with AR-V7. Both AR variant species were found to share a common 3′ terminal cryptic exon, which rendered AR-V9 susceptible to experimental manipulations that were previously thought to target AR-V7 uniquely. AR-V9 promoted ligand-independent growth of prostate cancer cells. High AR-V9 mRNA expression in CRPC metastases was predictive of primary resistance to abiraterone acetate (HR = 4.0; 95% confidence interval, 1.31–12.2; P = 0.02). Conclusions: AR-V9 may be an important component of therapeutic resistance in CRPC. Clin Cancer Res; 23(16); 4704–15. ©2017 AACR.

Abstract Background: Despite a large body of literature evaluating the association between recreational physical activity and epithelial ovarian cancer (EOC) risk, the extant evidence is inconclusive, and little is known about the independent association between recreational physical inactivity and EOC risk. We conducted a pooled analysis of nine studies from the Ovarian Cancer Association Consortium to investigate the association between chronic recreational physical inactivity and EOC risk. Methods: In accordance with the 2008 Physical Activity Guidelines for Americans, women reporting no regular, weekly recreational physical activity were classified as inactive. Multivariable logistic regression was utilized to estimate the ORs and 95% confidence intervals (CI) for the association between inactivity and EOC risk overall and by subgroups based upon histotype, menopausal status, race, and body mass index. Results: The current analysis included data from 8,309 EOC patients and 12,612 controls. We observed a significant positive association between inactivity and EOC risk (OR = 1.34; 95% CI, 1.14–1.57), and similar associations were observed for each histotype. Conclusions: In this large pooled analysis examining the association between recreational physical inactivity and EOC risk, we observed consistent evidence of an association between chronic inactivity and all EOC histotypes. Impact: These data add to the growing body of evidence suggesting that inactivity is an independent risk factor for cancer. If the apparent association between inactivity and EOC risk is substantiated, additional work via targeted interventions should be pursued to characterize the dose of activity required to mitigate the risk of this highly fatal disease. Cancer Epidemiol Biomarkers Prev; 25(7); 1114–24. ©2016 AACR.

Previous genome‐wide association studies among women of European ancestry identified two independent breast cancer susceptibility loci represented by single nucleotide polymorphisms (SNPs) rs13281615 and rs11780156 at 8q24. A fine‐mapping study across 2.06 Mb (chr8:127,561,724–129,624,067, hg19) in 55,540 breast cancer cases and 51,168 controls within the Breast Cancer Association Consortium was conducted. Three additional independent association signals in women of European ancestry, represented by rs35961416 (OR = 0.95, 95% CI = 0.93–0.97, conditional p = 5.8 × 10−6), rs7815245 (OR = 0.94, 95% CI = 0.91–0.96, conditional p = 1.1 × 10−6) and rs2033101 (OR = 1.05, 95% CI = 1.02–1.07, conditional p = 1.1 × 10−4) were found. Integrative analysis using functional genomic data from the Roadmap Epigenomics, the Encyclopedia of DNA Elements project, the Cancer Genome Atlas and other public resources implied that SNPs rs7815245 in Signal 3, and rs1121948 in Signal 5 (in linkage disequilibrium with rs11780156, r2 = 0.77), were putatively functional variants for two of the five independent association signals. The results highlighted multiple 8q24 variants associated with breast cancer susceptibility in women of European ancestry.

Abstract Background: A recent association study identified a common variant (rs9790517) at 4q24 to be associated with breast cancer risk. Independent association signals and potential functional variants in this locus have not been explored. Methods: We conducted a fine-mapping analysis in 55,540 breast cancer cases and 51,168 controls from the Breast Cancer Association Consortium. Results: Conditional analyses identified two independent association signals among women of European ancestry, represented by rs9790517 [conditional P = 2.51 × 10−4; OR, 1.04; 95% confidence interval (CI), 1.02–1.07] and rs77928427 (P = 1.86 × 10−4; OR, 1.04; 95% CI, 1.02–1.07). Functional annotation using data from the Encyclopedia of DNA Elements (ENCODE) project revealed two putative functional variants, rs62331150 and rs73838678 in linkage disequilibrium (LD) with rs9790517 (r2 ≥ 0.90) residing in the active promoter or enhancer, respectively, of the nearest gene, TET2. Both variants are located in DNase I hypersensitivity and transcription factor–binding sites. Using data from both The Cancer Genome Atlas (TCGA) and Molecular Taxonomy of Breast Cancer International Consortium (METABRIC), we showed that rs62331150 was associated with level of expression of TET2 in breast normal and tumor tissue. Conclusion: Our study identified two independent association signals at 4q24 in relation to breast cancer risk and suggested that observed association in this locus may be mediated through the regulation of TET2. Impact: Fine-mapping study with large sample size warranted for identification of independent loci for breast cancer risk. Cancer Epidemiol Biomarkers Prev; 24(11); 1680–91. ©2015 AACR.

Abstract A human IgM Ab, serum-derived human IgM 12 (sHIgM12), is identified that binds mouse and human dendritic cells (DC), inducing dramatic immunopotentiation following treatment of the mouse DC in vitro. Competition, transfection, and knockout studies identified the ligand on mouse DC as the costimulatory molecule family member B7-DC. Potent T cell responses are stimulated by Ag-pulsed DC treated with the sHIgM12 Ab in vitro and upon adoptive transfer of Ab-treated Ag-pulsed DC into animals. The multivalent structure of pentameric IgM provides the potential for cross-linking cell surface targets, endowing the soluble Abs with biological potential not normally associated with immune function. The ability of the sHIgM12 Ab to potentiate the immune response is dependent on the multimeric structure of IgM, as bivalent monomers do not retain this property. Furthermore, pretreatment of DC with IgM monomers blocks subsequent potentiation by intact IgM pentamers, an indication that cross-linking of B7-DC on the cell surface is critical for potentiation of Ag presentation. These findings imply that, in addition to known costimulatory roles, B7-DC can function as a receptor for signals delivered by cells expressing B7-DC ligands.

Background Cardiovascular implantable electronic device (CIED) pocket infections are often related to recent CIED placement or manipulation, but these infections are not well characterized. The clinical presentation of CIED pocket infection, based on temporal onset related to last CIED procedure, deserves further study. Methods The MEDIC (Multicenter Electrophysiologic Device Infection Cohort) prospectively enrolled subjects with CIED infection. Subjects were stratified into those whose infection occurred <12 months (early) or ≥12 months (late) since their last CIED‐related procedure. Results There were 132 subjects in the early group and 106 in the late group. There were more females (P = 0.009) and anticoagulation use (P = 0.039) in the early group. Subjects with early infections were more likely to have had a generator change or lead addition as their last procedure (P = 0.03) and had more prior CIED procedures (P = 0.023). Early infections were more likely to present with pocket erythema (P < 0.001), swelling (P < 0.001), and pain (P = 0.007). Late infections were more likely to have pocket erosion (P = 0.005) and valvular vegetations (P = 0.009). In bacteremic subjects, early infections were more likely healthcare‐associated (P < 0.001). In‐hospital and 6‐month mortality were equivalent. Conclusion A total of 45% of patients with CIED pocket infection presented >12 months following their last CIED‐related procedure. Patients with early infection were more likely to be female, on anticoagulation, and present with localized inflammation, whereas those with late infection were more likely to have CIED erosion or valvular endocarditis.