Karen Boland

Paracrine control of tissue regeneration and cell proliferation by Caspase-3.

Executioner caspases such as Caspase-3 and Caspase-7 have long been recognised as the key proteases involved in cell demolition during apoptosis. Caspase activation also modulates signal transduction inside cells, through activation or inactivation of kinases, phosphatases and other signalling molecules. Interestingly, a series of recent studies have demonstrated that caspase activation may also influence signal transduction and gene expression changes in neighbouring cells that themselves did not activate caspases. This review describes the physiological relevance of paracrine Caspase-3 signalling for developmental processes, tissue homeostasis and tissue regeneration, and discusses the role of soluble factors and microparticles in mediating these paracrine activities. While non-cell autonomous control of tissue regeneration by Caspase-3 may represent an important process for maintaining tissue homeostasis, it may limit the efficiency of current cancer therapy by promoting cell proliferation in those cancer cells resistant to radio- or chemotherapy. We discuss recent evidence in support of such a role for Caspase-3, and discuss its therapeutic implication.

Systems Analysis of BCL2 Protein Family Interactions Establishes a Model to Predict Responses to Chemotherapy

Apoptotic desensitization is a hallmark of cancer cells, but present knowledge of molecular systems controlling apoptosis has yet to provide significant prognostic insights. Here, we report findings from a systems study of the intrinsic pathway of apoptosis by BCL2 family proteins and clinical translation of its findings into a model with applications in colorectal cancer (CRC). By determining absolute protein quantifications in CRC cells and patient tumor samples, we found that BAK and BAX were expressed more highly than their antiapoptotic inhibitors. This counterintuitive finding suggested that sole inhibition of effector BAX and BAK could not be sufficient for systems stability in nonstressed cells. Assuming a model of direct effector activation by BH3-only proteins, we calculated that the amount of stress-induced BH3-only proteins required to activate mitochondrial apoptosis could predict individual death responses of CRC cells to 5-fluorouracil/oxaliplatin. Applying this model predictor to protein profiles in tumor and matched normal tissue samples from 26 patients with CRCs, we found that differences in protein quantities were sufficient to model the increased tumor sensitivity to chemotherapy compared with normal tissue. In addition, these differences were sufficient to differentiate clinical responders from nonresponders with high confidence. Applications of our model, termed DR_MOMP, were used to assess the impact of apoptosis-sensitizing drugs in lowering the necessary dose of state-of-the-art chemotherapy in individual patients. Together, our findings offer a ready clinical tool with the potential to tailor chemotherapy to individual patients.

Targeting the 19S proteasomal subunit, Rpt4, for the treatment of colon cancer

Deregulation of the ubiquitin-proteasome pathway has been frequently observed in a number of malignancies. Using quantitative Western blotting of normal and matched tumour tissue, we here identified a significant increase in the 19S proteasome subunit Rpt4 in response to chemoradiation in locally advanced rectal cancer patients with unfavourable outcome. We therefore explored the potential of Rpt4 reduction as a therapeutic strategy in colorectal cancer (CRC). Utilizing siRNA to down regulate Rpt4 expression, we show that silencing of Rpt4 reduced proteasomal activity and induced endoplasmic reticulum stress. Gene silencing of Rpt4 also inhibited cell proliferation, reduced clonogenic survival and induced apoptosis in HCT-116 colon cancer cells. We next developed a cell penetrating peptide-based nanoparticle delivery system to achieve in vivo gene silencing of Rpt4. Administration of Rpt4 siRNA nanoparticles reduced tumour growth and improved survival in a HCT-116 colon cancer xenograft tumour model in vivo. Collectively, our data suggest that inhibition of Rpt4 represents a novel strategy for the treatment of CRC.

Su1405 The Safety of Biologic Use in the Pregnant IBD Patient: Analysis of Patient Characteristics, Pregnancy and Neonatal Outcomes

Background: TNF alpha inhibitors are being increasingly used in IBD in women of fertile age. Studies to date have been mainly limited to case reports and case series with the largest observational cohort from 50 centres in the US. We aimed to prospectively assess the use of anti TNF treatment during pregnancy in a large European cohort. Methods: This was an observational cohort study addressing a 5 year period between 2008-2013. Female patients with IBD who had undergone anti-TNF treatment during pregnancy were identified using the IBD databases of 2 tertiary referral centres for IBD in Dublin. Patient characteristics including disease activity scores, duration, site and concomitant medications were recorded. Pregnancy outcomes including mode of delivery, miscarriage, ante and postnatal complications, age at conception and need for escalation of IBD treatment during pregnancy were also assessed. Neonatal outcomes including low birth weight, pre-term delivery, NICU stays or perinatal infection and timing of vaccines were also recorded. Data were analysed using t testing, contingency and logistic regression analyses. Results: From an IBD population of over 2,500 patients, 31 individual females who underwent anti -TNF treatment during pregnancy from 2008-2013 were identified with a total of 36 pregnancies. Median disease duration at time of pregnancy was 12 years (IQR 3-17). 85% had Crohns Disease, 15% Ulcerative Colitis. Median Harvey Bradshaw Index pre-pregnancy was 4.5 (IQR 2-13). Median Mayo score was 1 (IQR 0-3). 57.3% received infliximab, 38% adalimumab, 4.7% certolizimab. 53.8% were on concomitant immunemodulators. The majority of patients stopped biologic treatment at the start of the third trimester. 67% had treatment reinstated in the postpartum period. Median age at conception was 30.5 (IQR 25-35). 19% had previous miscarriages. 92% had successful term pregnancies. 22% required escalation of treatment during pregnancy. 19.3% had a pregnancy complication including emergency section. 16% neonates had a low birth weight with 2 preterm deliveries and one case of NICU stay for meconium ileus. No perinatal infections were reported. 20%mothers breastfed. The majority of mothers delayed live vaccination of their children. Interestingly, there was a significant independent association between disease activity at time of conception and low birthweight (p < 0.01). There was no association between adverse outcomes or neonatal infections and anti-TNF use noted in this cohort.Conclusion: Disease control at time of conception and through pregnancy should be the main goal of treatment in this patient cohort and the use of TNF alpha antagonists to achieve this appears to warranted to improve pregnancy outcomes though definitive safety has yet to be proven.

Mo2116 Development of Institutional Guidelines for the Identification and Management of Refeeding Syndrome Among Acutely Admitted Patients

Refeeding Syndrome refers to biochemical and physical abnormalities, arising as a result of shifts in electrolytes and fluid balance in malnourished individuals following the initiation of feeding. This is an acute complication of malnutrition among hospitalised patients with the potential for significant morbidity and mortality. We audited the percentage of patients admitted over 6 days at a tertiary referral centre at high risk of Refeeding Syndrome. Analysis of identification and management centred on NICE (National Institute of Clinical Excellence) Guidelines, CG32. 102 patients were included and 22 (21.5%) patients were at a high risk for developing Refeeding Syndrome. 8 patients from the high risk group did not have electrolyte levels monitored. Of the 14 high-risk patients who had bloods assayed, their treating physician prescribed only 7 patients thiamine. Only 32% of patients at high risk of Refeeding Syndrome were managed according to best practice, and 9% of the patients at high risk progressed to develop Refeeding Syndrome with one mortality. Following these findings, we formed amultidisciplinary committee comprisingmembers from the Department of Gastroenterology and Hepatology, Department of Nutrition and Dietetics, Department of Pharmacy and Nursing Administration. We developed institutional guidelines derived from literature review and NICE Guidelines for the identification and management of Refeeding Syndrome. We also developed guidelines for repletion of electrolytes with specific reference to formulations and doses appropriate to the levels of repletion required. A programme of education for nursing and clinical staff alike was undertaken, with the addition of regular patient weights applied to nursing charts and more streamlined dietician referral practices applied throughout the hospital. Flowcharts for expedient clinical intervention were available on all wards and the accident and emergency department, as were the above-mentioned electrolyte repletion guidelines. We are pleased to report that a repeated audit after initial implementation of these guidelines revealed that 11/54 patients (20%) were at high risk of Refeeding Syndrome. 45.5% of these patients were managed according to the guidelines, receiving both thiamine and appropriate blood investigations, which is comparable to 32% in the initial audit. This demonstrates progress after only 2months of widespread implementation of these guidelines at our institution. This audit cycle highlights the importance of identification and management of patients at risk of Refeeding Syndrome. The application of formal guidelines generated in a multidisciplinary manner as demonstrated at our institution yields improvements in patient management, giving clear recommendations and improving clinical education and awareness of malnutrition.