SOCS3 regulates pathological retinal angiogenesis through modulating SPP1 expression in microglia and macrophages

Pathological ocular angiogenesis has long been associated with myeloid cell activation. However, the precise cellular and molecular mechanisms governing the intricate crosstalk between the immune system and vascular changes during ocular neovascularization formation remain elusive. In this study, we demonstrated that the absence of the suppressor of cytokine signaling 3 (SOCS3) in myeloid cells led to a substantial accumulation of microglia and macrophage subsets during the neovascularization process. Our single-cell RNA sequencing data analysis revealed a remarkable increase in the expression of the secreted phosphoprotein 1 (Spp1) gene within these microglia and macrophages, identifying subsets of Spp1-expressing microglia and macrophages during neovascularization formation in angiogenesis mouse models. Notably, the number of Spp1-expressing microglia and macrophages exhibited further elevation during neovascularization in mice lacking myeloid SOCS3. Moreover, our investigation unveiled the Spp1 gene as a direct transcriptional target gene of signal transducer and activator of transcription 3. Importantly, pharmaceutical activation of SOCS3 or blocking of SPP1 resulted in a significant reduction in pathological neovascularization. In conclusion, our study highlights the pivotal role of the SOCS3/STAT3/SPP1 axis in the regulation of pathological retinal angiogenesis.

Photoreceptors inhibit pathological retinal angiogenesis through transcriptional regulation of Adam17 via c-Fos

Pathological retinal angiogenesis profoundly impacts visual function in vascular eye diseases, such as retinopathy of prematurity (ROP) in preterm infants and age-related macular degeneration in the elderly. While the involvement of photoreceptors in these diseases is recognized, the underlying mechanisms remain unclear. This study delved into the pivotal role of photoreceptors in regulating abnormal retinal blood vessel growth using an oxygen-induced retinopathy (OIR) mouse model through the c-Fos/A disintegrin and metalloprotease 17 (Adam17) axis. Our findings revealed a significant induction of c-Fos expression in rod photoreceptors, and c-Fos depletion in these cells inhibited pathological neovascularization and reduced blood vessel leakage in the OIR mouse model. Mechanistically, c-Fos directly regulated the transcription of Adam17 a shedding protease responsible for the production of bioactive molecules involved in inflammation, angiogenesis, and cell adhesion and migration. Furthermore, we demonstrated the therapeutic potential by using an adeno-associated virus carrying a rod photoreceptor-specific short hairpin RNA against c-fos which effectively mitigated abnormal retinal blood vessel overgrowth, restored retinal thickness, and improved electroretinographic (ERG) responses. In conclusion, this study highlights the significance of photoreceptor c-Fos in ROP pathology, offering a novel perspective for the treatment of this disease.

Ocular Vascular Diseases: From Retinal Immune Privilege to Inflammation

The eye is an immune privileged tissue that insulates the visual system from local and systemic immune provocation to preserve homeostatic functions of highly specialized retinal neural cells. If immune privilege is breached, immune stimuli will invade the eye and subsequently trigger acute inflammatory responses. Local resident microglia become active and release numerous immunological factors to protect the integrity of retinal neural cells. Although acute inflammatory responses are necessary to control and eradicate insults to the eye, chronic inflammation can cause retinal tissue damage and cell dysfunction, leading to ocular disease and vision loss. In this review, we summarized features of immune privilege in the retina and the key inflammatory responses, factors, and intracellular pathways activated when retinal immune privilege fails, as well as a highlight of the recent clinical and research advances in ocular immunity and ocular vascular diseases including retinopathy of prematurity, age-related macular degeneration, and diabetic retinopathy.

A135 ENDOSCOPIC SUBMUCOSAL DISSECTION OF GASTRIC ADENOMAS AND EARLY CARCINOMAS

Background

Management of gastric adenoma and early gastric cancer requires endoscopic resection. This can often be achieved with endoscopic mucosal resection (EMR), which has been shown to be effective with a good safety profile. One disadvantage of EMR is that it is often completed piecemeal, leading to indeterminant margins and higher rates of recurrences that require additional intervention. Endoscopic submucosal dissection (ESD) is a more advanced endoscopic resection technique that has been shown to be more effective than EMR at en-bloc resection. ESD requires high technical proficiency but it is becoming more widely available in western countries.

Purpose

The purpose of this study is to report on the outcomes and rates of complications of gastric ESD completed in a tertiary centre in British Columbia.

Method

All gastric ESD was completed by a senior therapeutic endoscopist who has previously received training in Japan. Retrospective data were collected on all gastric ESD procedures done in St. Paul’s Hospital from May 7th, 2015, when the procedure first became available, to Aug 30th, 2022. Inclusion criteria were all adults who have undergone ESD for resection of a gastric lesion. Exclusion criteria were patients younger than 18. Data collected included demographic variables, polyp characteristics, procedural outcomes, and complications.

Result(s)

A total of 49 ESD procedures were completed. The mean size of the resected lesions was 25.3 mm (range: 5 – 100 mm). Technical success, defined as successful resection of all polypoid tissue, was achieved in 48/49 procedures (98.0%). En bloc resection was achieved in 42/48 (87.5%) completed ESD. The rate of R0 resection was also 42/48 (87.5%). Curative resection, defined as technically successful ESD with an R0 margin and no lymphovascular invasion, was achieved in 41/49 (83.7%) of the cases. In our cohort, 8 patients had adenocarcinoma, 5 of which had a curative resection with no evidence of recurrence. None of the ESD resulted in any intra-procedural or delayed perforation. 5/49 (10.2%) patients had clinically significant post-endoscopic resection bleeding. Out of 37 patients that completed follow-up, 3 (8.1%) had recurrence, and all of them were managed endoscopically. 4/49 (8.2%) of patients required surgery post-ESD.

Conclusion(s)

In our cohort, ESD is an effective endoscopic resection modality for gastric lesions with a high rate of technical success and curative resection. Despite a deeper plane of resection versus other endoscopic resection modalities, its complication rate remains low. Although ESD requires high technical proficiency, its favorable outcomes along with low rates of complication make ESD highly feasible for the resection of gastric lesions. Further research will be needed to study the implementation and outcomes of

ESD in a western setting.

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None

Disclosure of Interest

None Declared

A122 MINIMALLY INVASIVE ENDOSCOPIC RESECTION TECHNIQUES FOR ANORECTAL JUNCTION NEOPLASIA: A SYSTEMATIC REVIEW AND META-ANALYSIS

Background

The management of neoplastic lesions at the anorectal junction remains debated. Endoscopic submucosal dissection (ESD) and endoscopic mucosal resection (EMR) have emerged as the primary endoscopic modalities of choice.

Purpose

We sought to compare the performance of ESD and EMR in resection of anorectal neoplasia.

Method

Two authors independently searched MEDLINE, EMBASE and Cochrane Libraries (Jan 2000 – Aug 2021) for citations evaluating the performance of endoscopic resection techniques (ESD, EMR) for lesions involving the anorectal junction (defined as within 20mm of the dentate line). The frequencies and 95% confidence intervals (95% CI) of technical success (complete removal of all neoplastic tissue at index procedure), clinically significant post-endoscopic resection bleeding (CSPEB), delayed perforation, recurrence and referral to surgery were assessed using random-effects modelling.

Result(s)

We included 11 studies (total 563 patients: 414 ESD, 149 EMR) of which nine were ESD and two were EMR studies. Technical success was achieved in 97.2% overall (95% CI 94.8%-98.5%, ESD 97.5% and EMR range 93.9%-98.0%). Clinically significant post-endoscopic resection bleeding occurred in 4.3% (95% CI 1.6%-11.1%, ESD 3.0% and EMR range 8.2%-11.0%). Delayed perforation was not identified. Recurrence at first screening colonoscopy occurred in 4.8% (95% CI 1.9%-11.7%, ESD 3.0% and EMR range 15.4%-18.4%). Referral to surgery for any reason occurred in 5.9% (95% CI 4.3%-8.0%, ESD 6.9%, EMR range 2.0%-3.0%).

Conclusion(s)

ESD and EMR demonstrate high frequencies of technical success but may have different rates of adverse events and recurrence. More studies investigating lesions at the anorectal junction should be conducted including head-to-head analyses between ESD and EMR for low-risk anorectal junction neoplasia.

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None

Disclosure of Interest

None Declared

A120 ENDOSCOPIC CLOSURE TECHNIQUES FOLLOWING ACUTE IATROGENIC PERFORATION -- AN UPDATED SYSTEMATIC REVIEW

Background

Iatrogenic perforation is arguably the most feared adverse event associated with endoscopy. Current American Society for Gastrointestinal Endoscopy (ASGE) and European Society of Gastroenterology Endoscopy (ESGE) guidelines recommend endoscopic closure as the first-line treatment strategy. Historically, this has been achieved using through-the-scope clips (TTSC). Given the emergence of alternative endoscopic closure techniques including over-the-scope clips (OTSC) and endoscopic suturing, we sought to provide an updated review of the literature.

Purpose

To review endoscopic closure techniques following iatrogenic perforation during screening or therapeutic endoscopy.

Method

Based on the Preferred Reporting Items for Systematic Reviews and Meta-analyses (PRISMA) Guidelines, an electronic search of MEDLINE and EMBASE from June 1^st, 1946 – Oct 10^th, 2022 was performed. Inclusion criteria was limited to English full-text original citations, with case reports, and cohorts with < 3 patients excluded. Our primary objective was to assess complete defect closure after attempted endoscopic treatment. Outcomes were stratified by modality (TTSC, OTSC, endoscopic suturing) and chronologically based on a previous well received systematic review.

Result(s)

A total of 2549 citations were identified in our electronic search, of which 34 were included representing 830 perforations. Overall, successful endoscopic closure was achieved in 763 cases (91.9%). When stratified by endoscopic closure techniques, range estimates for successful endoscopic closure was 71% – 100%, 57% - 100%, and 100% for TTSC, OTSC and endoscopic suturing respectively. When stratifying chronologically, an improvement in TTSC closure was identified.

Conclusion(s)

Endoscopic defect closure, including TTSC, OTSC and endoscopic suturing, are effective in the management of iatrogenic perforations with increasing TTSC performance over time. It remains the primary treatment strategy for iatrogenic perforation.

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None

Disclosure of Interest

None Declared

A131 ENDOSCOPIC SUBMUCOSAL DISSECTION OF COLORECTAL ADENOMAS AND EARLY ADENOCARCINOMAS: OUTCOMES FROM BRITISH COLUMBIA

Background

Endoscopic resection is the standard of care for the management of colorectal polyps. Larger and more complex polyps require endoscopic mucosal resection (EMR). While complications have been low, EMR is often piecemeal, resulting in indeterminant margins and often a higher recurrence rate. Endoscopic submucosal dissection (ESD) is an advanced endoscopic resection technique with a higher rate of en bloc resection. While more data exist for the resection of gastric lesions with ESD, ESD is becoming more widely used in western countries for the resection of colorectal lesions.

Purpose

The purpose of this study is to report on the outcomes and rates of complications for colorectal ESD completed in a tertiary centre in British Columbia.

Method

All colorectal ESD was completed by a senior therapeutic endoscopist who has previously received training in Japan. Retrospective data were collected on all colorectal ESD procedures done in St. Paul’s Hospital from July 11th, 2016, when the procedure first became available, to Aug 30th, 2022. Inclusion criteria were all adults who have undergone ESD for resection of a colorectal lesion. Exclusion criteria were patients younger than 18. Data collected included demographic variables, polyp characteristics, procedural outcomes, and complications.

Result(s)

A total of 39 ESD procedures were completed. The mean size of the resected lesion was 30.4 mm (range: 5 – 60 mm). Technical success, defined as successful resection of all polypoid tissue, was achieved in 35/39 procedures (89.7%). En-bloc resection was achieved in 27/35 (77.1%) of the completed ESD. The rate of R0 resection was 22/35 (62.9%). Curative resection, defined as technically successful ESD with R0 margin and no lymphovascular invasion, was achieved in 23/39 (59.0%) of the cases and the majority of the patients with non-curative resection that underwent endoscopic surveillance had no recurrence on follow-up. In our cohort, 3/39 (7.7%) patients had adenocarcinoma. None of the ESD resulted in any intra-procedural or delayed perforation. 3/39 (7.7%) patients had clinically significant post-endoscopic resection bleeding. Out of 24 patients that completed follow-up, 4 (16.7%) had recurrence at the resection site that was managed endoscopically. 4/39 (10.3%) of patients required surgery post-ESD.

Conclusion(s)

In our cohort, ESD is an effective endoscopic resection modality for the management of colorectal adenomas and early adenocarcinoma with a high rate of technical success and low rates of complications. Although the rate of curative resection was low, most were the result of R1 or Rx resection and a majority of the follow-ups in this subgroup demonstrated no further recurrence. The rate of en bloc resection is high, especially given the average size of adenomas in this cohort. Although ESD requires high technical proficiency, its favorable outcomes and low complication rates make ESD highly feasible for the resection of colorectal lesions.

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None

Disclosure of Interest

None Declared

Myeloid cells regulate retinal neovascularization via SOCS3

Neovascularization is the leading cause of vision loss in retinopathy of prematurity (ROP). Inflammation and myeloid cells are involved in retinal angiogenesis. However, the underlying mechanisms of how myeloid cells control neovascularization in ROP remain unknown. We and others previously reported that suppressor of cytokine signaling 3 (SOCS3) is induced in retinopathy. To investigate whether myeloid cells regulate retinal angiogenesis via SOCS3 in ROP, we used myeloid lineage specific SOCS3 loss-of-function (conditional knockout, cKO) mice and gain-of-function (conditional overexpression, cOE) mice and generated ROP mouse model - mice with oxygen induced retinopathy (OIR) by exposing mice to 75% oxygen from postnatal day (P)7 to P12 for 5 days, and then returned to normal air until P17. Retinas were collected for analysis including quantification of retinal neovascularization, gene expression, immune cell profiling and single cell sequencing. Our results showed that mice with myeloid SOCS3 deficiency had a substantial increase in pathological retinal neovascularization, whereas overexpression of SOCS3 in myeloid cells prevented pathological retinal neovascularization in response to OIR. Our single-cell sequencing data showed that population of myeloid lineage cells including microglia, macrophages and neutrophils was changed in mice with OIR and controlled by SOCS3. Therefore, myeloid cells are involved in retinal neovascularization via SOCS3 in ROP. Manipulating SOCS3 expression in myeloid cells may provide a new way to cure neovascularization in retinas.

Supported by grants from NIH (R01EY030140, R01EY029238) and from BrightFocus Foundation

A105 ENDOSCOPIC MUCOSAL RESECTION AND ENDOSCOPIC SUBMUCOSAL DISSECTION FOR ILEOCECAL VALVE NEOPLASIA: A SYSTEMATIC REVIEW AND META-ANALYSIS

Background

Neoplastic lesions at the ileocecal valve (ICV) represent a complex lesion subgroup given the unique anatomical characteristics of this location. Both endoscopic mucosal resection (EMR) and endoscopic submucosal dissection (ESD) are established techniques for colorectal neoplasia but comparative analyses for ICV lesions are lacking.

Aims

Evaluate the performance of EMR and ESD for ICV neoplasia.

Methods

Between Jan 2000 to Aug 2021, two authors independently searched MEDLINE, EMBASE and Cochrane Libraries for relevant citations evaluating the performance of either EMR and/or ESD for ICV neoplasia; defined as lesions involving at least one component of the ICV complex. The rate of technical success (complete removal of all neoplastic tissue during index procedure of those lesions deemed amenable to endoscopic resection), clinically significant post-endoscopic resection bleeding (CSPEB), delayed perforation, and recurrence were assessed. Meta-analysis was performed using a random-effects model.

Results

Nine studies (367 patients, 252 EMR, 115 ESD) were included in the analysis. Successful removal of all visible neoplastic tissue of those deemed amenable to endoscopic resection was 98.1% (EMR 99.6%, ESD 97.4%). Of note, only 2 studies, both assessing EMR, provided data on lesions which were not considered for endoscopic resection ranging from 5.6–23.7%. Average procedure time ranged from 45–49 minutes for EMR and 52–191 minutes for ESD. Clinically significant post-endoscopic resection bleeding occurred in 6.2% (EMR 9.4%, ESD 4.4%). Delayed perforation occurred in 0.6% (EMR 0.4%, ESD 2.0%). Recurrence occurred in 3.1% (EMR 13.2%, ESD 1.9%).

Conclusions

Endoscopic resection, both with EMR and ESD, demonstrates high technical success and good adverse event profiles amongst ICV neoplasia deemed amenable for endoscopic resection.

Funding Agencies

None

A123 MINIMALLY INVASIVE ENDOSCOPIC RESECTION TECHNIQUE PERFORMANCE FOR PERI-APPENDICEAL COLORECTAL NEOPLASIA: A SYSTEMATIC REVIEW AND META-ANALYSIS

Background

Minimally invasive endoscopic resection techniques, including endoscopic mucosal resection (EMR), endoscopic submucosal dissection (ESD) and endoscopic full-thickness resection (EFTR) have revolutionized the management of peri-appendiceal colorectal neoplasia. However, questions remain about their comparative performance.

Aims

We sought to evaluate the performance of EMR, ESD and EFTR for peri-appendiceal colorectal neoplasia.

Methods

Two authors independently searched MEDLINE, EMBASE and Cochrane Libraries (Jan 2000 – Aug 2021) for citations evaluating the performance of endoscopic resection techniques (EMR, ESD, EFTR) for peri-appendiceal colorectal neoplasia (defined as those involving or in close proximity to the appendiceal orifice). The incidence rates and 95% confidence intervals (95% CI) of technical success (complete removal of all neoplastic tissue at index procedure), clinically significant post-endoscopic resection bleeding (CSPEB), delayed perforation, recurrence and referral to surgery were assessed using random-effects modelling.

Results

12 studies were included in the analysis (479 patients: 185 EMR, 171 ESD, 123 EFTR). Technical success was achieved in 93.5% (95% CI 90.9%-95.4%, EMR 93.5%, ESD 94.1%, EFTR 92.7%). Clinically significant post-endoscopic resection bleeding occurred in 1.3% (95% CI 0.4%-4.3%, EMR 3.8%, ESD 1.2%, EFTR 0%). Delayed perforation occurred in 1.9% (95% CI 0.9%-3.9%, EMR 0%, ESD 2.4%, EFTR 2.4%). Recurrence occurred in 5.7% (95% CI 2.3%-13.8%, EMR 14.3%, ESD 0.2%, EFTR 12.2–14.3%). Referral to surgery occurred in 9.0% (95% CI 6.7%-12.0%, EMR 8.1%, ESD 9.5%, EFTR 9.8%).

Conclusions

Minimally invasive endoscopic resection techniques including EMR, ESD and EFTR demonstrate high frequencies of technical success with comparable adverse event profiles. They should now be viewed as first-line therapeutic modalities for the management of peri-appendiceal colorectal neoplasia.

Funding Agencies

None

Myeloid lineage contributes to pathological choroidal neovascularization formation via SOCS3

Background

Pathological neovascularization in neovascular age-related macular degeneration (nAMD) is the leading cause of vision loss in the elderly. Increasing evidence shows that cells of myeloid lineage play important roles in controlling pathological endothelium formation. Suppressor of cytokine signaling 3 (SOCS3) pathway has been linked to neovascularization.

Methods

We utilised a laser-induced choroidal neovascularization (CNV) mouse model to investigate the neovascular aspect of human AMD. In several cell lineage reporter mice, bone marrow chimeric mice and Socs3 loss-of-function (knockout) and gain-of-function (overexpression) mice, immunohistochemistry, confocal, and choroidal explant co-culture with bone marrow-derived macrophage medium were used to study the mechanisms underlying pathological CNV formation via myeloid SOCS3.

Findings

SOCS3 was significantly induced in myeloid lineage cells, which were recruited into the CNV lesion area. Myeloid Socs3 overexpression inhibited laser-induced CNV, reduced myeloid lineage-derived macrophage/microglia recruitment onsite, and attenuated pro-inflammatory factor expression. Moreover, SOCS3 in myeloid regulated vascular sprouting ex vivo in choroid explants and SOCS3 agonist reduced in vivo CNV.

Interpretation

These findings suggest that myeloid lineage cells contributed to pathological CNV formation regulated by SOCS3.

Funding

This project was funded by NIH/NEI (R01EY030140, R01EY029238), BrightFocus Foundation, American Health Assistance Foundation (AHAF), and Boston Children's Hospital Ophthalmology Foundation for YS and the National Institutes of Health/National Heart, Lung and Blood Institute (U01HL098166) for PZ.

A83 IMPACT OF TELEHEALTH ON MEDICATION ADHERENCE IN GASTROENTEROLOGY CHRONIC DISEASE MANAGEMENT

Background

With the COVID-19 pandemic, the demand and availability of telehealth in outpatient care has increased. Although use of telehealth has been studied and validated for various medical specialties, relatively few studies have looked at its role in gastroenterology despite burden of chronic diseases such as inflammatory bowel disease (IBD).

Aims

To assess effectiveness of telehealth medicine in gastroenterology by comparing medication adherence rate for patients seen with telehealth and traditional in-person appointment for various GI conditions.

Methods

Retrospective chart analysis of patients seen in outpatient gastroenterology clinic was performed to identify patients who were given prescription to fill either through telehealth or in-person appointment. By using provincial pharmacy database, we determined the prescription fill rate.

Results

A total of 241 patients were identified who were provided prescriptions during visit with their gastroenterologists. 128 patients were seen through in-person visit during pre-pandemic period. 113 patients were seen through telehealth appointment during COVID pandemic.

The mean age of patients in telehealth cohort was 42 years (57% male). On average patients had 10 prior visits with their gastroenterologists before index appointment, used for adherence assessment. 92% of patients were seen in follow-up, while 8% were seen in initial consultation. The majority of the patients in the telehealth cohort had IBD (89%), while the remaining 11% had various diagnoses, including functional GI disorder, gastroesophageal reflux disease, viral hepatitis, or hepatobiliary disorders. Biologic therapy was the most commonly prescribed medication (66.4%). 45 patients were provided either new medication or dose change, and 68 patients had prescription refill to continue their current medications. It took a mean of 18 days (SD = 16.2) for patients to fill their prescriptions.

Prescription fill rate for patients seen through telehealth and in-person visit were 98.2% and 89.1% (P = 0.004) respectively. Patients seen through telehealth were 6.8 times more likely to fill their prescriptions compared to the in-person counterparts (OR 6.82, CI 1.51 – 30.68, P = 0.004). When we compared adherence rate while excluding biologic therapies, the prescription fill rate was 94.7% in telehealth group and 81.4% in in-person group (OR 4.11, CI 0.88 – 19.27, P = 0.056). Due to high level of adherence, statistical analysis comparing adherent and non-adherent groups was performed but yielded insignificant results.

Conclusions

Medication adherence rate for patients seen through telehealth was higher compared to patients seen through in-patient visit in this study. Telehealth is a viable alternative for outpatient care especially for patients with chronic GI conditions such as IBD.

Funding Agencies

None

Early surveillance of anthracycline induced cardiotoxicity in children using echocardiography and biomarkers: A prospective study

Funding Acknowledgements

Type of funding sources: Public grant(s) – National budget only. Main funding source(s): CIHR

Background

Anthracyclines, which are commonly used in cancer treatment can induce myocardial damage, result in heart failure during treatment and have cardiac effects even decades after treatment. Monitoring of cardiotoxicity during treatment is largely based on the use of echocardiographic functional markers like ejection fraction and more recently myocardial strain imaging. Some studies have also looked at the utility of biomarkers like troponin and BNP. The utility of this surveillance strategy remains controversial as larger prospective studies are lacking.

Purpose

The aim of this study was to prospectively describe the impact of anthracycline treatment on echocardiographic functional parameters and cardiac biomarkers (high sensitivity troponin T and NT-Pro BNP) during the treatment period and twelve months after completion of treatment. In the current study we wanted to look at whether monitoring parameters during treatment were predictive of left ventricular function 12 months after treatment.

Methods

This was a prospective multi-centre nested case-control study of 256 children diagnosed with cancer requiring anthracycline therapy. Baseline functional echocardiographic parameters  and cardiac biomarkers were obtained prior to starting anthracycline therapy, during the treatment protocol, and 12 months after treatment completion. Patients were assigned to one of two comparison groups based on the fractional shortening at the12-month echocardiogram: patients in group 1 had normal fractional shortening, (FS ³ 28%) while patients in group 2 had reduced fractional shortening (FS &lt; 28%).

Results

A total of 917 echoes were performed, 376 of these occurred during the treatment period. FS was reduced in 27 (7%) of echoes obtained during the treatment period with 22 patients developing new onset dysfunction. Twelve months after treatment completion 232 patients had normal FS (Group 1), while 24 patients showed reduced FS (Group 2). Both groups had normal systolic function and cardiac biomarkers at baseline, however patients in group 2 were older at diagnosis (13.2 years (11.8-16) vs 6.5 years (3.4-13.2), p = 0.003) and received a higher cumulative anthracycline dose (200 mg/m2 (143-318) vs 125 mg/m2 (75-200), p= 0.005). One third (8/24) of patients in group 2 had at least 1 abnormal echo during the treatment period compared to 7% (16/232) in the normal group P &lt; 0.001. The proportion of patients with at least one abnormal biomarker during this period however, was similar between groups.

 Conclusion(s)

Patients receiving higher accumulative anthracycline doses and those with abnormal FS during the treatment period are at higher risk of having reduced cardiac function 12 months after treatment. High sensitivity troponin and NT-Pro BNP levels during the treatment period fail to discriminate patients at risk of developing early reduced systolic function. The relationship of these early results to long term cardiac function remains to be demonstrated.

A82 SUCCESSFUL RESECTION OF GRADE 1 DUODENAL NEUROENDOCRINE TUMOURS USING ENDOSCOPIC TECHNIQUES IN TWO CANADIAN HOSPITALS

Background

Given the rarity of duodenal neuroendocrine tumours (dNETs), limited guidelines exist for resection of well-differentiated, ≤10 mm dNETS. As incidence rises, alternatives to surgery are valuable. We present 9 cases of endoscopic dNET resections and a literature review.

Aims

To demonstrate efficacy and safety of endoscopic resection for dNETs ≤10 mm at 2 Canadian hospitals.

Methods

We retrospectively analyzed data on 7 patients that had endoscopic dNET resection from 2013–2018. Endoscopic resection occurred if dNETs were ≤10 mm in diameter, did not extend to the muscularis propria and lymphovascular invasion was absent. WHO 2017 classification was used.

Results

All patients had biopsies and 5 (71%) had EUS prior to resection; 4 females and 3 males underwent resection of 9 dNETs; 2 via cap-assisted snare polypectomy; 4 with cap-assisted band mucosectomy; and 2 over-the-scope clip-assisted resection. The median size was 10 mm (4–11); 6 (67%) dNETS were found in the duodenal bulb, 2 at the D1/D2 junction and 1 in D2 alone. The median age was 68.5 (50–79) years.

All dNETs were submucosal and well-differentiated. The dNETs were resected en bloc, but 3 did not have clear margins. Two procedures were complicated by duodenal perforation; 1 requiring surgery and 18 days in hospital. One case was complicated by bleeding with successful endoscopic hemostasis. The majority (75%) of resections were day procedures.

Patients were followed for 6–12 months with an EGD or chromogrannin A. None of the patients had endoscopic residual disease, but 1 patient required a second procedure to remove a dNET left in situ following the initial resection of 2 dNETs 12 months earlier.

In our literature review of 178 patients, the majority of dNETs were resected by EMR 81% (150/185) versus ESD, similar to our experience. Patients were slightly younger with a mean age of 63.28, and most dNETs (46%) were found in the duodenal bulb. Complications included intraoperative bleeding, perforation and death in 17 (9.55%), 9 (5.06%) and 1 (0.06%) patient(s) respectively. The rate of recurrence was 4/178 (2.25%) and patients had a mean follow up of 26.1 months.

Conclusions

Well-differentiated dNETs ≤10 mm in diameter can be successfully resected endoscopically. Complications can be managed intraoperatively and hospital stay remains minimal.

Funding Agencies

None

A154 ASSESSING COLON SCREENING PROGRAM COLONOSCOPIES IN A NON-HOSPITAL ENDOSCOPY CLINIC

Background

Colorectal cancer is the most commonly diagnosed cancer in British Columbia, affecting 1 in 6 persons. The BC Colon Screening Program (CSP) screens individuals 50–74 years of age with biennial FIT (cut-off 10 mcg/g) with follow-up colonoscopy for positive results. In Vancouver, colonoscopies are performed in a hospital environment; however non-hospital endoscopy clinics have been used in other jurisdictions.

Aims

To investigate the quality of procedure, rate of complications and need to repeat procedures in a hospital setting for colonoscopies performed on CSP patients in a non-hospital setting.

Methods

A retrospective chart review for all CSP colonoscopies performed from 04/19 to 07/19 in a non-hospital endoscopy clinic. Data was collected from an electronic medical record system and included adenoma detection rates; any repeat procedures required in a hospital setting and adverse event rates. Criteria for a repeat in hospital colonoscopy were inadequate bowel preparation, body mass index exceeding the allowable threshold for a non-hospital colonoscopy and identification of a difficult to remove polyp such as a polyp &gt; 20 mm or in a difficult location.

Results

801 FIT positive patients (ages 50–74) underwent colonoscopy in the non-hospital endoscopy clinic. The mean age was 60 years (51% female). The mean time between referral date and procedure date was 192 days. The neoplasia detection rate was 60.2%, there was one (0.1%) adverse event (post-polypectomy bleed) and 21 (2.6%) patients required a repeat colonoscopy in a hospital setting.

Conclusions

Colonoscopy to follow-up a positive FIT in an non-hospital endoscopy clinic was safe and effective with a low number of repeat, in hospital colonoscopies required.

Funding Agencies

None

A80 ADVANCED ENDOSCOPIC RESECTION OF LARGE POLYPS & EARLY NEOPLASIA: OUTCOMES OF ENDOSCOPIC MUCOSAL RESECTION IN BRITISH COLUMBIA

Background

Recent advances have resulted in a new technique termed endoscopic mucosal resection (EMR). This procedure has been successful at removing large or complex polyps and achieving remission rates comparable to surgery. EMR can also be used to remove early, non-metastatic cancer and they are less invasive than surgery. However, they have been associated with their own complications, most serious of which being perforation. This procedure has recently become available in British Columbia for resection of both complex polyps and early established cancers in the colon.

Aims

Here we present patient outcomes of EMR procedures for the resection of colorectal polyps in British Columbia.

Methods

Retrospective data were collected on all EMR procedures done in Vancouver General Hospital and St. Paul’s Hospital (Vancouver, B.C.) from October 2012 (when procedure became available) to July 2019. Inclusion criteria were all adults who had undergone EMR for resection of polyps in the colon. Exclusion criteria were patients younger than 18 or patients who had EMR that resected polyps in the upper GI tract. Patients were referred to one of two endoscopists when one or more polyps suitable for EMR were identified during colonoscopy by other gastroenterologists. Collected data included patient demographics, polyp characteristics, procedure outcome, and complications.

Results

There were 211 EMR procedures performed on 182 patients (48.9% male). Patient age ranged from 27 to 86 (mean = 67.1). A total of 244 colon polyps were removed with an average size of 2.91 cm and ranged from 0.8 cm to 15 cm. Resected polyps had the following distribution: ascending colon (63.5%), transverse colon (10.2%), descending colon (5.7%), sigmoid colon (15.2%), and rectum (5.3%). Of those that reported resection type, 84.2% were piecemeal and 15.8% were en bloc. 40.9% of polyps were tubulovillous adenoma, 33.2% were tubular, 16.2% were sessile serrated, 6.4% were villous, and 3.4% were adenocarcinoma. Patients from 11 of the 211 EMR cases (5.2%) experienced post-procedure bleed and 4 of these 11 patients (36.4%) had been on anti-platelet or anti-coagulants (discontinued before procedure). Overall, patients from 51 (24.2%) EMR cases were on anti-platelet or anti-coagulants. 33 cases (15.6%) had residual polyps at the resection site that required additional endoscopic resection during follow-up and 14 patients (6.6%) required surgery. None of the EMR procedures resulted in perforation.

Conclusions

EMR is an effective minimally-invasive procedures that can be used to remove large, complicated colonic polyps and achieve long-term remission rate. The procedure has an acceptable risk profile, with complication and re-intervention rate similar or less than other procedures used to remove large, complicated polyps.

Funding Agencies

None

A279 EUS-GUIDED BILIARY DRAINAGE IN MALIGNANT DISTAL BILIARY OBSTRUCTION: AN INTERNATIONAL SURVEY TO IDENTIFY BARRIERS OF TECHNOLOGY IMPLEMENTATION

Background

Endoscopic ultrasound-guided biliary drainage (EUS-BD) is a promising alternative to endoscopic retrograde cholangiopancreatography (ERCP) in malignant distal biliary obstruction (MDBO). Recent small randomized controlled trials comparing EUS-BD with ERCP suggest that EUS-BD achieves a similar technical success rate and safety profile while potentially being associated with lower rates of stent dysfunction However, its application in clinical practice has been impeded by various undefined barriers.

Aims

To evaluate the current practice of EUS-BD and the determinants for its clinical implementation in MDBO.

Methods

An online survey was generated using Google Forms. Five endoscopy societies have distributed the survey as of October 10th, 2019. Survey questions measured participant characteristics, EUS-BD in different clinical scenarios, and potential barriers to implementation. Descriptive statistics were calculated using frequencies, chi-square statistics were used for inferential analysis, and a standard step-wise multivariable analysis was performed to identify independent variables for and against the use of EUS-BD.

Results

To date, 102 physicians have participated in the survey (response rate 7.97%). The majority of participants are from North America (39.2%), Asia (31.4%), and Europe (19.6%). Most participants are gastroenterologists with formal therapeutic endoscopy training (66.7%), though only 28.4% have received EUS-BD training. In unresectable cancer, 85.1% of respondents favoured EUS-BD over percutaneous biliary drainage following ERCP failure (p&lt;0.0001), while in borderline resectable disease, 72.3% preferred EUS-BD. On multivariable analysis, male gender, formal training in EUS-BD, and unresectable cancer were independent variables for the use of EUS-BD. Conversely, independent discouraging factors for EUS-BD included fear of adverse events, limited high-quality data, lack of local expertise, and inadequate access to EUS technology.

Conclusions

In this international survey, it appears that EUS-BD is gaining traction, especially in the setting of unresectable disease following ERCP failure. However, barriers to implementation include the lack of high-quality data, fear for adverse events, limited experts in the field, and inadequate access to EUS technology. This suggest the need for high-quality clinical trials, increased endoscopist training in this field, and further technology development in EUS-BD in order to increase its uptake in clinical practice.

Funding Agencies

None

A89 IMPLEMENTING ENDOSCOPIC SUBMUCOSAL DISSECTION IN A WESTERN CANADIAN SETTING: OUTCOMES, LEARNING CURVE AND LOGISTICAL CONSIDERATIONS

Background

Endoscopic submucosal dissection (ESD) is an advanced resection technique for large gastrointestinal lesions. ESD was developed in Japan and is popular in countries with gastric cancer screening and a high incidence of gastric cancer. ESD has benefits over endoscopic mucosal resection (EMR) such as increased complete resection, en bloc resection and lower recurrence. However, ESD is a longer procedure and is difficult to master in countries with low incidence of early gastric neoplasia which is the ideal anatomic location for learning. There is increasing interest in using ESD techniques including hybrid ESD/EMR in western centers. Barriers include procedure time, perforation risk and challenges accumulating sufficient experience.

Aims

To present our experience implementing an ESD program in British Columbia including outcomes and logistical considerations of interest.

Methods

All ESD procedures since implementation of the program in May 2015 to July 2019 were included. Descriptive statistics and performance indicators over time are reported. All procedures were performed by a staff endoscopist after specialized training. Procedures were performed at two hospitals in British Columbia. Cases were referred from endoscopists and were assessed with dedicated endoscopy with or without endoscopic ultrasound prior to booking ESD.

Results

40 procedures were performed, though only one procedure was performed in the first year (Mean age 70, 67.5% male). ASA class ranged from 1–4 (mean 2.08). 22 lesions were gastric, 13 were rectal, with the remainder throughout the colon. Mean lesion size was 25mm in maximum dimension (interquartile range 15-30mm). 18 procedures were performed under general anesthesia and the remainder using procedural sedation. Total surgical time ranged from 22 to 398 minutes. Mean surgical time was 104 minutes, or 126 minutes including anesthesia. 50% of procedures were performed using hybrid ESD/EMR technique. R0 resection rate across all cases was 68% (60% for hybrid procedures, 80% for strict ESD). En bloc resection rate was 60%. Recurrence rate was 10%. Complication rate was 7.5% all were post-procedure bleeds requiring hospitalization. No perforations occurred. 3 patients required surgery for incomplete resection or invasive cancer on pathology, 3 required repeat endoscopic resection. Surgical time per cm of lesion improved significantly from the first 10 cases to the last 10 (time per cm resected 75 min to 32 min p&lt;0.006).

Conclusions

ESD is an effective therapy for GI neoplasia. ESD is feasible in a Canadian setting. Hybrid techniques tend to be faster though at the expense of R0 resection. Patient centered outcomes in this sample are favorable and comparable to large ESD series. Monitoring of ESD quality is critical for comparison with standard of care as experience with ESD in Canada grows.

Funding Agencies

None

Single-cell reconstruction of follicular remodeling in the human adult ovary

The ovary is perhaps the most dynamic organ in the human body, only rivaled by the uterus. The molecular mechanisms that regulate follicular growth and regression, ensuring ovarian tissue homeostasis, remain elusive. We have performed single-cell RNA-sequencing using human adult ovaries to provide a map of the molecular signature of growing and regressing follicular populations. We have identified different types of granulosa and theca cells and detected local production of components of the complement system by (atretic) theca cells and stromal cells. We also have detected a mixture of adaptive and innate immune cells, as well as several types of endothelial and smooth muscle cells to aid the remodeling process. Our results highlight the relevance of mapping whole adult organs at the single-cell level and reflect ongoing efforts to map the human body. The association between complement system and follicular remodeling may provide key insights in reproductive biology and (in)fertility.

BRD4 bimodal binding at promoters and drug-induced displacement at Pol II pause sites associates with I-BET sensitivity

Background

Deregulated transcription is a major driver of diseases such as cancer. Bromodomain and extra-terminal (BET) proteins (BRD2, BRD3, BRD4 and BRDT) are chromatin readers essential for maintaining proper gene transcription by specifically binding acetylated lysine residues. Targeted displacement of BET proteins from chromatin, using BET inhibitors (I-BETs), is a promising therapy, especially for acute myeloid leukemia (AML), and evaluation of resistance mechanisms is necessary to optimize the clinical efficacy of these drugs.

Results

To uncover mechanisms of intrinsic I-BET resistance, we quantified chromatin binding and displacement for BRD2, BRD3 and BRD4 after dose response treatment with I-BET151, in sensitive and resistant in vitro models of leukemia, and mapped BET proteins/I-BET interactions genome wide using antibody- and compound-affinity capture methods followed by deep sequencing. The genome-wide map of BET proteins sensitivity to I-BET revealed a bimodal pattern of binding flanking transcription start sites (TSSs), in which drug-mediated displacement from chromatin primarily affects BRD4 downstream of the TSS and prolongs the pausing of RNA Pol II. Correlation of BRD4 binding and drug-mediated displacement at RNA Pol II pause sites with gene expression revealed a differential behavior of sensitive and resistant tumor cells to I-BET and identified a BRD4 signature at promoters of sensitive coding and non-coding genes.

Conclusions

We provide evidence that I-BET-induced shift of Pol II pausing at promoters via displacement of BRD4 is a determinant of intrinsic I-BET sensitivity. This finding may guide pharmacological treatment to enhance the clinical utility of such targeted therapies in AML and potentially other BET proteins-driven diseases.

Electronic supplementary material

The online version of this article (10.1186/s13072-019-0286-5) contains supplementary material, which is available to authorized users.

Strategies for successful recruitment of young adults to healthy lifestyle programmes for the prevention of weight gain: a systematic review

Recruiting healthy young adults, aged 18-35, to lifestyle programmes for prevention of weight gain is challenging but important given their increasing rates of obesity. This review aimed to examine the success of different recruitment strategies. A systematic literature search identified 26 separate studies using 10 electronic databases. Participant characteristics and efficacy of interventions were well reported in all studies, but reporting of recruitment procedures, costs, times and effectiveness was minimal. Of those reporting recruitment, both active (e.g. face-to-face) and passive (e.g. print-media and mass-mailings) approaches were identified with the latter most frequently employed. Novel strategies such as social media and marketing approaches were identified. Television and radio have potentially high reach but low efficiency with high cost compared with mass-mailings which yield high numbers of participants. Marketing campaigns appeared to be a promising approach. Incentives demonstrated enhanced recruitment. The use of formative research to guide recruitment strategies for interventions is recommended. Reporting of success, cost and timelines for recruitment should be included in reporting of future trials. This first synthesis of recruitment information can be used to inform recruitment frameworks for lifestyle programmes seeking to attract young adults.

Prevalence and Perceptions Toward Anabolicandrogenic Steroid Use Amongst University Students

Anabolic-androgenic steroids (AASs) are highly sought-after in order to achieve muscle growth and better physical attributes. The study was conducted to measure the prevalence and attitudes towards the use of AASs among university students. 1008 male students from Isfahan University, Iran, between the ages of 18 and 25 years (23.3 ± 1.2 years) completed a questionnaire that investigated participation in bodybuilding, level of sport competition, participation in sports and recreational activities, AASs use, prevalence, knowledge among users, attitudes, as well as intent to continue using AASs in the future. 8% of respondents had used AASs and 6% currently use AASs. 71% of users believed using only a small amount of AASs or using AASs with anti-toxic drugs would not result in any harm, 10% indicated that AASs were harmless and 19% admitted to taking AASs despite knowing the adverse effects. 33% of respondents believed that they needed to use AASs to ensure athletic success and 26% believed that athletes should be allowed to use AASs without consequence. The prevalent use of AASs is a public health concern which implies that educational programmes at university level are needed to educate students about the adverse effects of AASs use

Regulation of Human Adenovirus Replication by RNA Interference

Adenoviruses cause a wide variety of human infectious diseases. Adenoviral conjunctivitis and epidemic keratoconjunctivitis are commonly associated with human species D adenoviruses. Currently, there is no sufficient or appropriate treatment to counteract these adenovirus infections. Thus, there is an urgent need for new etiology-directed therapies with selective activity against human adenoviruses. To address this problem, the adenoviral early genes E1A and E2B (viral DNA polymerase) seem to be promising targets. Here, we propose an effective approach to downregulate the replication of human species D adenoviruses by means of RNA interference. We generated E1A expressing model cell lines enabling fast evaluation of the RNA interference potential. Small interfering RNAs complementary to the E1A mRNA sequences of human species D adenoviruses mediate significant suppression of the E1A expression in model cells. Furthermore, we observed a strong downregulation of replication of human adenoviruses type D8 and D37 by small hairpin RNAs complementary to the E1A or E2B mRNA sequences in primary human limbal cells. We believe that our results will contribute to the development of efficient anti-adenoviral therapy.

Regulation of Human Adenovirus Replication by RNA Interference

Adenoviruses cause a wide variety of human infectious diseases. Adenoviral conjunctivitis and epidemic keratoconjunctivitis are commonly associated with human species D adenoviruses. Currently, there is no sufficient or appropriate treatment to counteract these adenovirus infections. Thus, there is an urgent need for new etiology-directed therapies with selective activity against human adenoviruses. To address this problem, the adenoviral early genes E1A and E2B (viral DNA polymerase) seem to be promising targets. Here, we propose an effective approach to downregulate the replication of human species D adenoviruses by means of RNA interference. We generated E1A expressing model cell lines enabling fast evaluation of the RNA interference potential. Small interfering RNAs complementary to the E1A mRNA sequences of human species D adenoviruses mediate significant suppression of the E1A expression in model cells. Furthermore, we observed a strong downregulation of replication of human adenoviruses type D8 and D37 by small hairpin RNAs complementary to the E1A or E2B mRNA sequences in primary human limbal cells. We believe that our results will contribute to the development of efficient anti-adenoviral therapy.

Assessment, validation and deployment strategy of a two-barcode protocol for facile genotyping of duckweed species

Lemnaceae, commonly called duckweeds, comprise a diverse group of floating aquatic plants that have previously been classified into 37 species based on morphological and physiological criteria. In addition to their unique evolutionary position among angiosperms and their applications in biomonitoring, the potential of duckweeds as a novel sustainable crop for fuel and feed has recently increased interest in the study of their biodiversity and systematics. However, due to their small size and abbreviated structure, accurate typing of duckweeds based on morphology can be challenging. In the past decade, attempts to employ molecular barcoding techniques for species assignment have produced promising results; however, they have yet to be codified into a simple and quantitative protocol. A study that compiles and compares the barcode sequences within all known species of this family would help to establish the fidelity and limits of this DNA-based approach. In this work, we compared the level of conservation between over 100 strains of duckweed for two intergenic barcode sequences derived from the plastid genome. By using over 300 sequences publicly available in the NCBI database, we determined the utility of each of these two barcodes for duckweed species identification. Through sequencing of these barcodes from additional accessions, 30 of the 37 known species of duckweed could be identified with varying levels of confidence using this approach. From our analyses using this reference dataset, we also confirmed two instances where mis-assignment of species has likely occurred. Potential strategies for further improving the scope of this technology are discussed.

A rare WNT1 missense variant overrepresented in ASD leads to increased Wnt signal pathway activation

Wnt signaling, which encompasses multiple biochemical pathways that regulate neural development downstream of extracellular Wnt glycoprotein ligands, has been suggested to contribute to major psychiatric disorders including autism spectrum disorders (ASD). We used next-generation sequencing and Sequenom genotyping technologies to resequence 10 Wnt signaling pathway genes in 198 ASD patients and 240 matched controls. Results for single-nucleotide polymorphisms (SNPs) of interest were confirmed in a second set of 91 ASD and 144 control samples. We found a significantly increased burden of extremely rare missense variants predicted to be deleterious by PolyPhen-2, distributed across seven genes in the ASD sample (3.5% in ASD vs 0.8% in controls; Fisher's exact test, odds ratio (OR)=4.37, P=0.04). We also found a missense variant in WNT1 (S88R) that was overrepresented in the ASD sample (8 A/T in 267 ASD (minor allele frequency (MAF)=1.69%) vs 1 A/T in 377 controls (MAF=0.13%), OR=13.0, Fisher's exact test, P=0.0048; OR=8.2 and P=0.053 after correction for population stratification). Functional analysis revealed that WNT1-S88R is more active than wild-type WNT1 in assays for the Wnt/β-catenin signaling pathway. Our findings of a higher burden in ASD of rare missense variants distributed across 7 of 10 Wnt signaling pathway genes tested, and of a functional variant at the WNT1 locus associated with ASD, support that dysfunction of this pathway contributes to ASD susceptibility. Given recent findings of common molecular mechanisms in ASD, schizophrenia and affective disorders, these loci merit scrutiny in other psychiatric conditions as well.

A differentiated porcine bronchial epithelial cell culture model for studying human adenovirus tropism and virulence

The species specificity of human adenoviruses (HAdV) almost precludes studying virulence and tropism in animal models, e.g. rodent models, or derived tissue and cell culture models. However, replication of HAdV type 5 (HAdV-C5) has been shown after intravenous injection in swine. In order to study adenovirus replication in airway tissue propagation of bronchial epithelial cells from porcine lungs was established. These primary cells proved to be fully permissive for HAdV-C5 infection in submerged culture, demonstrating efficient HAdV genome replication, infectious viral particle release (1.07×10(8) TCID(50)/ml±6.63×10(7)) and development of cytopathic effect (CPE). Differentiation of porcine bronchial epithelial cells was achieved at the air-liquid interface on collagen I coated 0.4μm polyester membranes. Morphology, expression of tubulin and occludin, the development of tight-junctions and cilia were similar to human bronchial epithelial cells. Infection with HAdV-C5 from the basolateral side resulted in release of infectious virus progeny (2.05×10(7) TCID(50)/ml±2.39×10(7)) to the apical surface as described recently in human bronchial epithelial cells, although complete CPE was not observed. Differentiated porcine bronchial epithelial cells hold promise as a novel method for studying the virulence and pathophysiology of pneumonia associated HAdV types.

Bax inhibitor-1: a highly conserved endoplasmic reticulum-resident cell death suppressor

In spite of fundamental differences between plant and animal cells, it is remarkable that some cell death regulators that were identified to control cell death in metazoans can also function in plants. The fact that most of these proteins do not have structural homologs in plant genomes suggests that they may be targeting a highly conserved 'core' mechanism with conserved functions that is present in all eukaryotes. The ubiquitous Bax inhibitor-1 (BI-1) is a common cell death suppressor in eukaryotes that has provided a potential portal to this cell death core. In this review, we will update the current status of our understanding on the function and activities of this intriguing protein. Genetic, molecular and biochemical studies have so far suggested a consistent view that BI-1 is an endoplasmic reticulum (ER)-resident transmembrane protein that can interact with multiple partners to alter intracellular Ca(2+) flux control and lipid dynamics. Functionally, the level of BI-1 protein has been hypothesized to have the role of a rheostat to regulate the threshold of ER-stress inducible cell death. Further, delineation of the cell death suppression mechanism by BI-1 should shed light on an ancient cell death core-control pathway in eukaryotes, as well as novel ways to improve stress tolerance.

Reconstruction of the chloroplast noncyclic electron transport pathway from water to NADP with three integral protein complexes

RECONSTRUCTION OF PHOTOSYNTHETIC NONCYCLIC ELECTRON TRANSPORT FROM WATER TO NADP HAS BEEN ACCOMPLISHED BY USING THREE INTEGRAL PROTEIN COMPLEXES ISOLATED FROM CHLOROPLAST THYLAKOID MEMBRANES: photosystems I and II and the cytochrome b(6)-f complex. This system shows an absolute dependence on the presence of all three protein complexes for NADP reduction, in addition to plastocyanin, ferredoxin, and ferredoxin-NADP reductase. The reconstructed system was found to be sensitive to low concentrations of known inhibitors of noncyclic electron transport. Depletion of the Rieske iron-sulfur center and bound plastoquinone from the cytochrome b(6)-f complex resulted in an inhibition of the photoreduction of NADP.

Function of HES6 an Inhibitor of HES1, in the Breast Cancer Cell Lines T47D and MCF-7 Is to Up-Regulate E2F-1 and Increased Proliferation

Hormone resistance remains as a major obstacle in breast cancer treatment. The majority of breast tumors are dependent on estrogens to grow, therefore anti-estrogens such as Tamoxifen is an effective treatment option. We have found that a transcription factor Hes6, earlier described in the nervous tissue, is up-regulated in hormone-independent breast cancer cells compared to normal estrogen sensitive breast cancer cells. By using a lenti-virus system, we have over-expressed Hes6 in T47D cells which are estrogen sensitive. This resulted in increased proliferation. We also found that estrogen treatment of MCF-7 breast cancer cells induced expression of endogenous Hes6 in the G1-phase. We could not find any binding of estrogen receptor α to the HES6 gene but instead found a binding site up-steam of the promoter in the ASCL1 gene. ASCL1 is a known inducer of HES6 and we are showing that ASCL1 is up-regulated by 17β-estradiol in MCF-7 cells. To find the mechanism behind the tumorogenic effects of Hes6, we analysed important factors of the cell-cycle. We found that the G1-phase factor E2F-1 was up-regulated in response to increased Hes6 expression. Since HES6 have been shown to be an inhibitor of HES1, this is in agreement with a previous study where we found that HES1 inhibited proliferation by binding to the promoter of and down-regulating E2F-1 expression. E2F-1 is an important limiting factor in late G1-phase of the cell cycle and can drive cell proliferation.We believe that the HES1-HES6 interplay is important in antiestrogen-resistant breast cancer. Studies are now ongoing to investigate if Hes6 is up-regulated in estrogen-independent human breast cancer samples.

Citation Information: Cancer Res 2009;69(24 Suppl):Abstract nr 2153.

The glass transition in twinned ((phenyl)4As)2C60Cl crystals

We have studied the crystal structure of ((phenyl)4As)2C60Cl at room temperature and below the phase transition at Tc = 125 K by single-crystal x-ray diffraction. At room temperature tetragonal lattice parameters were found as a = b = 12.588(1)Å and c = 20.345(1)Å. At T = 120 K the lattice parameters were determined as a = b = 12.5060(1)Å and c = 20.4420(1)Å. The room temperature and low-temperature structures were found to be isostructural, with space group I4/m. Structure refinements were performed with restrictions on the C60 molecules according to the noncrystallographic isohedral point symmetry Ih . Derivations from this symmetry could not be found, suggesting that any possible Jahn-Teller distortion of the C60 radical anions will be smaller than 0.01Å. The phase transition observed in ESR at Tc = 125 K is proposed to be a glass transition. At room temperature there is dynamic disorder between two orientations of the C60 molecules as they are related by the 4-fold rotation. Below Tc the disorder becomes static. Two types of twinning have been observed in different crystals. The first type is represented by a rotation over 180 about [1,1,1] axis. It results in different orientations of the 4-fold unique axes with angles of 82.4 degrees between them. Secondly, merohedral twinning was observed corresponding to the two orientations of the structure with 4/m symmetry on the tetragonal lattice. Both twinnings result in extra orientations of the C60 molecules, and they should be taken into account, when analysing the anisotropy of the physical properties of crystals of this compound.

Critical role of FoxO3a transcription factor in response to therapy with EGFR inhibitors, gefitinib and lapatinib, in breast cancer

21018

Background: Inhibition of the EGF-receptor is a potential therapeutic strategy for breast cancer. The PI3-K/PKB signalling pathway plays an important role in cell proliferation, survival and malignant transformation. The Forkhead box group O transcriptional factor, FoxO3a, is a direct downstream target of PKB. Here we studied the role of the FoxO3a in response to the EGFR inhibitors Gefitinib and Lapatinib. Methods: Response of breast cancer cell lines to treatment with Gefitinib and Lapatinib was evaluated by proliferation assay and FACS analysis. Expression of FoxO3a and its downstream targets was analysed using Western blotting. Sub-cellular localisation of FoxO3a was analysed by confocal microscopy. FoxO3a mRNA level was measured by RTq-PCR. siRNA transfections were performed using Oligofectamine reagent. Immunohistological staining was performed on patient samples to validate our findings. Results: Treatment of a panel of breast cancer cell lines with both inhibitors resulted in decreased proliferation due to G1-arrest and apoptosis in two sensitive cell-lines, BT474 and SKBR3. Western blot analysis revealed that response to the treatment was associated with a decrease in PKB and FoxO3a phosphorylation and thus the nuclear relocalisation of FoxO3a. Confocal microscopy confirmed that treatment induced nuclear translocation of FoxO3a only in sensitive but not resistant cells. This relocation of FoxO3a was accompanied by an induction of FoxO3a mRNA and its principal targets, p27kip1 and Bim. Transfection of the sensitive BT474 cells with FoxO3a specific siRNA resulted in a significant reduction in FoxO3a protein expression and Gefitinib-induced cell death. Comparison of immunohistochemical staining of biopsies from breast cancer patients before and after Gefitinib treatment revealed that therapy resulted in a significant increase in nuclear FoxO3a staining. Conclusion: Our results demonstrate for the first time that the EGFR-family inhibitors, Gefitinib and Lapatinib, specifically target FoxO3a to induce cell cycle arrest and apoptosis. This finding helps to define the mechanism of action of Gefitinib and Lapatinib and may provide novel insights into the molecular basis for resistance to these inhibitors.

No significant financial relationships to disclose.