ATRX loss promotes tumor growth and impairs nonhomologous end joining DNA repair in glioma

Recent work in human glioblastoma (GBM) has documented recurrent mutations in the histone chaperone protein ATRX. We developed an animal model of ATRX-deficient GBM and showed that loss of ATRX reduces median survival and increases genetic instability. Further, analysis of genome-wide data for human gliomas showed that ATRX mutation is associated with increased mutation rate at the single-nucleotide variant (SNV) level. In mouse tumors, ATRX deficiency impairs nonhomologous end joining and increases sensitivity to DNA-damaging agents that induce double-stranded DNA breaks. We propose that ATRX loss results in a genetically unstable tumor, which is more aggressive when left untreated but is more responsive to double-stranded DNA-damaging agents, resulting in improved overall survival.

Survival and Proliferation of Neural Progenitor-Derived Glioblastomas Under Hypoxic Stress is Controlled by a CXCL12/CXCR4 Autocrine-Positive Feedback Mechanism

Purpose: One likely cause of treatment failure in glioblastoma is the persistence of glioma stem-like cells (GSLCs) which are highly resistant to therapies currently employed. We found that CXCL12 has highest expression in glioma cells derived from neural progenitor cells (NPC). The development and molecular signature of NPC-derived glioblastomas were analyzed and the therapeutic effect of blocking CXCL12 was tested.Experimental Design: Tumors were induced by injecting DNA into the lateral ventricle of neonatal mice, using the Sleeping Beauty transposase method. Histology and expression of GSLC markers were analyzed during disease progression. Survival upon treatment with pharmacologic (plerixafor) or genetic inhibition of CXCR4 was analyzed. Primary neurospheres were generated and analyzed for proliferation, apoptosis, and expression of proteins regulating survival and cell-cycle progression.Results: Tumors induced from NPCs display histologic features of human glioblastoma and express markers of GSLC. In vivo, inhibiting the CXCL12/CXCR4 signaling axis results in increased survival of tumor-bearing animals. In vitro, CXCR4 blockade induces apoptosis and inhibits cell-cycle progression, downregulates molecules regulating survival and proliferation, and also blocks the hypoxic induction of HIF-1α and CXCL12. Exogenous administration of CXCL12 rescues the drug-induced decrease in proliferation.Conclusions: This study demonstrates that the CXCL12/CXCR4 axis operates in glioblastoma cells under hypoxic stress via an autocrine-positive feedback mechanism, which promotes survival and cell-cycle progression. Our study brings new mechanistic insight and encourages further exploration of the use of drugs blocking CXCL12 as adjuvant agents to target hypoxia-induced glioblastoma progression, prevent resistance to treatment, and recurrence of the disease. Clin Cancer Res; 23(5); 1250-62. ©2016 AACR.

Neuroendocrine tumours of the small bowel: interpretation of raised circulating chromogranin A, urinary 5 hydroxy indole acetic acid and circulating neurokinin A

BACKGROUND

Neuroendocrine tumours (NETs) of the small bowel are difficult to diagnose as symptoms are non-specific and more often found in common gastrointestinal diseases. Chromogranin A (CGA), urinary 5 hydroxy indole acetic acid (U-5HIAA) and Neurokinin A (NKA) are used as laboratory diagnostic tests but results may be misleading or confusing.

AIM

To clarify the relevance of NET biomarkers for diagnosis of small bowel NETs.

DESIGN

A review of laboratory test results.

METHODS

We reviewed 500 consecutive raised plasma CGA, U-5HIAA and plasma NKA, results from patients in N Ireland. The diagnosis of NET was confirmed by the Northern Ireland Cancer Registry.

RESULTS

In 500 specimens recording raised CGA, 52.2% were from patients with NETs, 13.6% being small bowel tumours, 5.4% of specimens from patients with auto-immune atrophic gastritis and 15.4% from patients taking proton pump inhibitors. In 500 specimens with raised U-5HIAA, 87.8% were from patients with NETs, 68.2% being small bowel tumours. Lung NETs contributed 12.2% and NETs from other sites, 7.4%. Of 500 specimens with raised NKA (reference range (RR) > 20 ng/L), 72.6% were from patients with small bowel NETs and 6% specimens from patients with other NETs. In 20% of specimens NKA concentrations were 21-23 ng/L, within limits of assay precision.

CONCLUSION

CGA remains the best general circulating marker for NETs although only half of raised test results are due to an NET. U-5HIAA is an excellent marker for small bowel and lung NETs with 80% of high test results confirming these diagnoses. NKA is the most specific biomarker for small bowel NETs.

Assessing the Patient Care Implications of "Concierge" and Other Direct Patient Contracting Practices: A Policy Position Paper From the American College of Physicians

As physicians seek innovative practice models, one that is gaining ground is for practices to contract with patients to pay directly for some or all services-often called cash-only, retainer, boutique, concierge, or direct primary care or specialty care practices. Such descriptions do not reflect the variability found in practices. For the purposes of this paper, the American College of Physicians (ACP) defines a direct patient contracting practice (DPCP) as any practice that directly contracts with patients to pay out-of-pocket for some or all of the services provided by the practice, in lieu of or in addition to traditional insurance arrangements, and/or charges an administrative fee to patients, sometimes called a retainer or concierge fee, often in return for a promise of more personalized and accessible care. This definition encompasses the practice types previously described. The move to DPCPs is based on the premise that access and quality of care will be improved without third-party payers imposing themselves between the patient and the physician. Yet concerns have been raised that DPCPs may cause access issues for patients who cannot afford to pay directly for care. This ACP position paper, initiated and written by its Medical Practice and Quality Committee and approved by the Board of Regents on 25 July 2015, assesses the impact of DPCPs on access, cost, and quality; discusses principles from the ACP Ethics Manual, Sixth Edition, that should apply to all practice types; and makes recommendations to mitigate any adverse effect on underserved patients.

Abstract 3651: Natural killer cells eradicate galectin-1 deficient glioma in the absence of adaptive immunity

Natural killer (NK) cells safeguard against early tumor formation by seeking out and destroying transformed target cells in a process referred to as NK immunosurveillance. While it is clear that malignant brain tumors such as glioblastoma (GBM) evade NK-mediated tumor suppression, the precise mechanisms by which this occurs remain unknown. We now show that shRNA-mediated knockdown of the β-galactoside-binding lectin, galectin-1 (gal-1), in malignant glioma cells leads to the failure to form lethal intracranial tumors in RAG1-/- mice, a mouse strain devoid of adaptive immunity. However, gal-1 deficient glioma growth is fully restored on implantation into the brain of severely immunocompromised NOD-scid IL2Rg null mice, which lack both adaptive and innate immune function, thus implicating the innate immune response in the early rejection of gal-1 deficient glioma. Immunodepletion of NK cells in RAG1-/- or C57BL/6J mice using anti-asialo GM1 or anti-NK1.1 antibodies permit the growth of large gal-1 deficient gliomas, while macrophage depletion with clodronate liposomes only permits limited tumor growth. This combined result suggests that NK cells and macrophages may work together to achieve gal-1 deficient glioma rejection. Antigen-specific IFN-γ ELISpot assays using splenocytes from immunocompetent C57BL/6J mice indicate that gal-1 deficient glioma is cleared prior to the onset of an adaptive anti-tumor immune response. Flow cytometric analysis of brain tumor-infiltrating immune cells reveal that gal-1 deficient gliomas contain significantly more macrophages and granzyme B+ NK cells compared to gal-1 expressing gliomas. In-vitro experiments further show that gal-1 deficient glioma cells are inherently over 3-times more sensitive to NK-mediated tumor lysis, fail to suppress pro-inflammatory (M1) microglial activation, and secrete pro-inflammatory cytokines IL-1β, IL-12p70, and CXCL2. We conclude that glioma-derived gal-1 is a powerful inhibitor of NK-mediated cytotoxicity in-vivo, and predict that its suppression will be of therapeutic value in the treatment of human malignant brain tumors by dramatically heightening anti-tumor NK immunosurveillance.

Citation Format: Gregory J. Baker, Viveka Nand Yadav, Peter Chockley, Robert Doherty, Michael Ritt, Sivaraj Sivaramakrishnan, Maria G. Castro, Pedro R. Lowenstein. Natural killer cells eradicate galectin-1 deficient glioma in the absence of adaptive immunity. [abstract]. In: Proceedings of the 105th Annual Meeting of the American Association for Cancer Research; 2014 Apr 5-9; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2014;74(19 Suppl):Abstract nr 3651. doi:10.1158/1538-7445.AM2014-3651

Natural killer cells eradicate galectin-1-deficient glioma in the absence of adaptive immunity

Natural killer (NK) cells safeguard against early tumor formation by destroying transformed target cells in a process referred to as NK immune surveillance. However, the immune escape mechanisms used by malignant brain tumors to subvert this innate type of immune surveillance remain unclear. Here we show that malignant glioma cells suppress NK immune surveillance by overexpressing the β-galactoside-binding lectin galectin-1. Conversely, galectin-1-deficient glioma cells could be eradicated by host NK cells before the initiation of an antitumor T-cell response. In vitro experiments demonstrated that galectin-1-deficient GL26-Cit glioma cells are ∼3-fold more sensitive to NK-mediated tumor lysis than galectin-1-expressing cells. Our findings suggest that galectin-1 suppression in human glioma could improve patient survival by restoring NK immune surveillance that can eradicate glioma cells. Cancer Res; 74(18); 5079-90. ©2014 AACR.

Preclinical characterization of signal transducer and activator of transcription 3 small molecule inhibitors for primary and metastatic brain cancer therapy

Signal transducer and activator of transcription 3 (STAT3) has been implicated as a hub for multiple oncogenic pathways. The constitutive activation of STAT3 is present in several cancers, including gliomas (GBMs), and is associated with poor therapeutic responses. Phosphorylation of STAT3 triggers its dimerization and nuclear transport, where it promotes the transcription of genes that stimulate tumor growth. In light of this role, inhibitors of the STAT3 pathway are attractive therapeutic targets for cancer. To this end, we evaluated the STAT3-inhibitory activities of three compounds (CPA-7 [trichloronitritodiammineplatinum(IV)], WP1066 [(S,E)-3-(6-bromopyridin-2-yl)-2-cyano-N-(1-phenylethyl)acrylamide, C17H14BrN3O], and ML116 [4-benzyl-1-{thieno[2,3-d]pyrimidin-4-yl}piperidine, C18H19N3S]) in cultured rodent and human glioma cells, including GBM cancer stem cells. Our results demonstrate a potent induction of growth arrest in GBM cells after drug treatment with a concomitant induction of cell death. Although these compounds were effective at inhibiting STAT3 phosphorylation, they also displayed variable dose-dependent inhibition of STAT1, STAT5, and nuclear factor κ light-chain enhancer of activated B cells. The therapeutic efficacy of these compounds was further evaluated in peripheral and intracranial mouse tumor models. Whereas CPA-7 elicited regression of peripheral tumors, both melanoma and GBM, its efficacy was not evident when the tumors were implanted within the brain. Our data suggest poor permeability of this compound to tumors located within the central nervous system. WP1066 and ML116 exhibited poor in vivo efficacy. In summary, CPA-7 constitutes a powerful anticancer agent in models of peripheral solid cancers. Our data strongly support further development of CPA-7-derived compounds with increased permeability to enhance their efficacy in primary and metastatic brain tumors.

Marmosets as a preclinical model for testing "off-label" use of doxycycline to turn on Flt3L expression from high-capacity adenovirus vectors

We developed a combined conditional cytotoxic, i.e., herpes simplex type 1-thymidine kinase (TK), plus immune-stimulatory, i.e., fms-like tyrosine kinase ligand-3-mediated gene therapy for glioblastoma multiforme (GBM). Therapeutic transgenes were encoded within high-capacity adenoviral vectors (HC-Ad); TK was expressed constitutively, while Flt3L was under the control of the TetOn regulatable promoter. We previously assessed efficacy and safety in intracranial GBM rodent models. But, since this approach involves expression of a cytokine within the brain, we chose the nonhuman primate, i.e., Callithrix jaccus (marmoset) as it has been established that its immune response shares similarities with man. We characterized the safety, cell-type specific expression, and doxycycline (DOX)-inducibility of HC-Ad-TetOn-Flt3L delivered within the striatum. We used allometrically scaled DOX doses delivered orally, twice daily for one month, mimicking the route and duration of DOX administration planned for the GBM trial. Flt3L was effectively expressed within astrocytes, microglia, oligodendrocytes, and neurons. No evidence of brain or systemic toxicities due to the treatment was encountered. Our data indicate that DOX doses equivalent to those used in humans to treat infections can be safely used "off-label" to turn "on" therapeutic gene expression from HC-Ad-TetOn-Flt3L; providing evidence for the safety of this approach in the clinic.

New St. Jude Medical Portico™ transcatheter aortic valve: features and early results

Patients with symptomatic aortic valve disease who are inoperable or have high surgery-related risks may be treated with transcatheter aortic valve implantation devices. With this method increasingly applied, device innovations are aimed at achieving improved procedural results and therapeutic outcome. This paper describes the innovations implemented in the St. Jude Medical Portico™ system for transcatheter aortic valve implantation, the application of this system and initial clinical experience.

Epigenetic regulation of the innate immune response to LPS in bovine peripheral blood mononuclear cells (PBMC)

Epigenetic regulation of gene expression could help explain variation in responses to infection and differences in disease susceptibility in cattle. The aim of this study was to examine epigenetic mechanisms in the regulation of LPS-induced innate immune gene expression in peripheral blood mononuclear cells (PBMCs) from five healthy calves. Firstly, epigenetic enzyme gene expression (histone deacetylase (HDAC) and DNA methyltransferase (DNMT)) was measured after LPS stimulation. Secondly, the effect of the histone deacetylase inhibitor Trichostatin A (TSA) on histone H3 acetylation and on innate immune gene expression was also measured. Results showed differential expression of HDAC6, HDAC7 and DNMT3A genes in response to LPS in cells from all animals, while TSA significantly inhibited pro-inflammatory cytokine (TNF, IL2 and IFNG) expression (P<0.05), presumably by histone acetylation. These results suggest an important role for the HDAC family of enzymes in the regulation of bovine innate immune gene expression.

Targeted prostate cancer screening in men with mutations in BRCA1 and BRCA2 detects aggressive prostate cancer: preliminary analysis of the results of the IMPACT study

OBJECTIVE

To evaluate the role of targeted prostate cancer screening in men with BRCA1 or BRCA2 mutations, an international study, IMPACT (Identification of Men with a genetic predisposition to ProstAte Cancer: Targeted screening in BRCA1/2 mutation carriers and controls), was established. This is the first multicentre screening study targeted at men with a known genetic predisposition to prostate cancer. A preliminary analysis of the data is reported.

PATIENTS AND METHODS

Men aged 40-69 years from families with BRCA1 or BRCA2 mutations were offered annual prostate specific antigen (PSA) testing, and those with PSA > 3 ng/mL, were offered a prostate biopsy. Controls were men age-matched (± 5 years) who were negative for the familial mutation.

RESULTS

In total, 300 men were recruited (205 mutation carriers; 89 BRCA1, 116 BRCA2 and 95 controls) over 33 months. At the baseline screen (year 1), 7.0% (21/300) underwent a prostate biopsy. Prostate cancer was diagnosed in ten individuals, a prevalence of 3.3%. The positive predictive value of PSA screening in this cohort was 47·6% (10/21). One prostate cancer was diagnosed at year 2. Of the 11 prostate cancers diagnosed, nine were in mutation carriers, two in controls, and eight were clinically significant.

CONCLUSIONS

The present study shows that the positive predictive value of PSA screening in BRCA mutation carriers is high and that screening detects clinically significant prostate cancer. These results support the rationale for continued screening in such men.

Prostate cancer in male BRCA1 and BRCA2 mutation carriers has a more aggressive phenotype

There is a high and rising prevalence of prostate cancer (PRCA) within the male population of the United Kingdom. Although the relative risk of PRCA is higher in male BRCA2 and BRCA1 mutation carriers, the histological characteristics of this malignancy in these groups have not been clearly defined. We present the histopathological findings in the first UK series of BRCA1 and BRCA2 mutation carriers with PRCA. The archived histopathological tissue sections of 20 BRCA1/2 mutation carriers with PRCA were collected from histopathology laboratories in England, Ireland and Scotland. The cases were matched to a control group by age, stage and serum PSA level of PRCA cases diagnosed in the general population. Following histopathological evaluation and re-grading according to current conventional criteria, Gleason scores of PRCA developed by BRCA1/2 mutation carriers were identified to be significantly higher (Gleason scores 8, 9 or 10, P=0.012) than those in the control group. Since BRCA1/2 mutation carrier status is associated with more aggressive disease, it is a prognostic factor for PRCA outcome. Targeting screening to this population may detect disease at an earlier clinical stage which may therefore be beneficial.

Delivery of cancer genetics services: The Royal Marsden telephone clinic model

We have conducted a telelink telephone-led cancer genetic counselling model at The Royal Marsden NHS Foundation Trust. The study commenced in March 2004 and evaluation of the clinic was conducted over 17 months from March 2005 to the end of July 2006. A total of 612 patients had telephone consultations during this time, 228 of whom were referred from primary care with a median of 30 patients counselled per month (range of 19-63, depending on staff availability with average of two staff per clinic). Waiting times were measured for General Practitioner referrals and all 228 were counselled within the national target-stipulated 13 weeks (median 6 weeks, range 1-12). An additional 132 patients who were sent appointment letters after receipt of their family history questionnaires did not attend their appointments (18% of all potential referrals) and required recontacting by letter. After telephone counselling, 42% of patients were able to be discharged from the telephone clinic without a subsequent face-to-face appointment, thereby saving resources. The telephone clinic also had a short set-up time with flexibility on timing and day of administration, which would be an advantage in centres where outreach clinic facilities are scarce. The telelink telephone counselling model is highly efficient in triaging high risk individuals for face-to-face counselling as per the Kenilworth model, in effecting concentration of resources and in providing a flexible individual-centred approach to cancer genetic counselling delivery.

Microbial analysis of soil and groundwater from a gasworks site and comparison with a sequenced biological reactive barrier remediation process

AIMS

To investigate the distribution of a polymicrobial community of biodegradative bacteria in (i) soil and groundwater at a former manufactured gas plant (FMGP) site and (ii) in a novel SEquential REactive BARrier (SEREBAR) bioremediation process designed to bioremediate the contaminated groundwater.

METHODS AND RESULTS

Culture-dependent and culture-independent analyses using denaturing gradient gel electrophoresis (DGGE) and polymerase chain reaction (PCR) for the detection of 16S ribosomal RNA gene and naphthalene dioxygenase (NDO) genes of free-living (planktonic groundwater) and attached (soil biofilm) samples from across the site and from the SEREBAR process was applied. Naphthalene arising from groundwater was effectively degraded early in the process and the microbiological analysis indicated a dominant role for Pseudomonas and Comamonas in its degradation. The microbial communities appeared highly complex and diverse across both the sites and in the SEREBAR process. An increased population of naphthalene degraders was associated with naphthalene removal.

CONCLUSION

The distribution of micro-organisms in general and naphthalene degraders across the site was highly heterogeneous. Comparisons made between areas contaminated with polycyclic aromatic hydrocarbons (PAH) and those not contaminated, revealed differences in the microbial community profile. The likelihood of noncultured bacteria being dominant in mediating naphthalene removal was evident.

SIGNIFICANCE AND IMPACT OF THE STUDY

This work further emphasizes the importance of both traditional and molecular-based tools in determining the microbial ecology of contaminated sites and highlights the role of noncultured bacteria in the process.