The impact of neighborhood disadvantage on colorectal cancer screening among African Americans in Chicago

Historically, colorectal cancer (CRC) screening rates have been lower among African Americans. Previous studies that have examined the relationship between community characteristics and adherence to CRC screening have generally focused on a single community parameter, making it challenging to evaluate the overall impact of the social and built environment. In this study, we will estimate the overall effect of social and built environment and identify the most important community factors relevant to CRC screening. Data are from the Multiethnic Prevention and Surveillance Study (COMPASS), a longitudinal study among adults in Chicago, collected between May 2013 to March 2020. A total 2,836 African Americans completed the survey. Participants' addresses were geocoded and linked to seven community characteristics (i.e., community safety, community crime, household poverty, community unemployment, housing cost burden, housing vacancies, low food access). A structured questionnaire measured adherence to CRC screening. Weighted quantile sum (WQS) regression was used to evaluate the impact of community disadvantages on CRC screening. When analyzing all community characteristics as a mixture, overall community disadvantage was associated with less adherence to CRC screening even after controlling for individual-level factors. In the adjusted WQS model, unemployment was the most important community characteristic (37.6%), followed by community insecurity (26.1%) and severe housing cost burden (16.3%). Results from this study indicate that successful efforts to improve adherence to CRC screening rates should prioritize individuals living in communities with high rates of insecurity and low socioeconomic status.

The PRECEDE consortium: A longitudinal international cohort study of individuals with genetic risk or familial pancreatic cancer

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Background: Pancreatic ductal adenocarcinoma (PDAC) is a highly lethal disease with lack of effective early detection strategies. There is an incomplete understanding of who is at risk for PDAC development and the contribution of heritability to that risk. Further, efforts at biomarker development for detection of early stage disease have been hampered by small sample sizes, lack of coordination, and inadequate access to high quality clinical data and biospecimens in relevant clinical populations. The PRECEDE Consortium was established to serve as a collaborative international network of PDAC clinical and research centers to accelerate early detection advances by standardizing collection of clinical data and biospecimens from patients at increased risk for PDAC. The consortium goal is to increase the overall survival rate for PDAC to 50% in 10 years by enabling transformative biomarker-driven discoveries in early detection of high-risk premalignant lesions and early stage cancers. Methods: The PRECEDE Consortium (NCT04970056; precedestudy.org) launched in 2019 and began enrollment in May, 2020. Data and biospecimen sharing are required for centers to join the consortium, which is facilitated through use of standardized data and biospecimen collection, and a centralized database (PRECEDELink) managed by a data coordinating center (Arbor Research). Imaging and clinical sequencing data will be stored and analyzed via a PRECEDE solution in the Amazon Web Services cloud. Participants age 18-90 are enrolled into one of seven cohorts based on personal and/or family history of PDAC and carrier status of pathogenic germline variants (PGV) in cancer predisposition genes (CPG). Three-generation pedigrees are collected at enrolment from participants, and standardized clinical germline testing is offered. Blood sample collection for DNA, plasma, and serum is completed at enrollment, and repeated annually for individuals meeting guidelines for annual surveillance. Results: To date, 24 clinical sites have enrolled 2187 participants, with a target of 10,000 participants enrolled from100 sites over the next 5 years. Among enrolled patients, 55% meet criteria for annual surveillance by MRI or endoscopic ultrasound. Demographics of the cohort to date: 56% female; 73% white; 35% CPG PGV carriers; 32% meet criteria for familial pancreatic cancer. Conclusions: The PRECEDE Consortium study is a large international, longitudinal, prospective cohort study designed to accelerate the pace and scale of early diagnosis. Planned projects will address modifiers of risk, penetrance of disease, creating comprehensive risk models for clinical decision-making, and development and validation of biomarker assays. The PRECEDE Consortium provides a unique, innovative platform to bring together key stakeholders (academia, patients, public and private sector) to effect progress.

Digital Navigation Improves No-Show Rates and Bowel Preparation Quality for Patients Undergoing Colonoscopy: A Randomized Controlled Quality Improvement Study

OBJECTIVES

Because of high historical no-show rates and poor bowel preparation quality in our unit, we sought to evaluate whether text message navigation for patients scheduled for colonoscopy would reduce no-show rates and improve bowel preparation quality compared with usual care.

METHODS

We performed a randomized controlled quality improvement study from April to August 2019 in an urban academic endoscopy unit. All patients scheduled for colonoscopy were randomly assigned to a control group that received usual care (paper instructions/nursing precalls) or to the intervention group that received usual care plus the text message program [short message service (SMS)]. The program provided timed-release instructions on dietary modifications and bowel preparation before colonoscopy. The primary outcome was no-shows. Secondary outcomes were no-show/same-day cancellations, no-show/cancellations within 7 days of the procedure, and bowel preparation quality.

RESULTS

A total of 1625 patients were randomized (SMS=833, control=792). No-show rates were significantly lower in the SMS group compared with the control group (8% vs. 14%; P<0.0001). Similar results were found for no-show/same-day cancellations (10% vs. 16%; P=0.0003), and no-show/cancellations within 7 days (18% vs. 26%; P=0.0008). There was no difference in adequate bowel preparation for all colonoscopies between the groups (89% vs. 87%; P=0.47). However, rates of adequate bowel preparation for screening/surveillance colonoscopies were significantly higher in SMS versus control groups (93% vs. 88%; P=0.04).

CONCLUSIONS

Text message navigation for patients scheduled for colonoscopy improved the quality of colorectal cancer screening by decreasing no-show rates and increasing adequate bowel preparation rates in patients undergoing screening colonoscopy compared with usual care.

Abstract PO-143: Differences in vitamin D genomic and epigenomic responses in colonic organoids from African- and European-Americans

Background: African Americans have the highest burden of colorectal cancer (CRC) in the US. Active 1,25(OH)2vitamin D (1,25vitD) protects from CRC, though the role of population differences in 1,25vitD responses to CRC disparities is unknown. To study inter-ethnic host-environment interactions in the colon, we have established human-derived colonic organoids from diverse populations. We used this approach to study differences in transcriptional and chromatin accessibility responses to 1,25vitD between Americans of African (AA) and European (EA) ancestry. Methods: Colonic organoids from 60 subjects (30 AA and 30 EA) were established. After passaging, organoids were differentiated for 24h and then treated with 100nM 1,25vitD or ethanol (vehicle control). Chromatin accessibility and gene expression were assessed at 4 and 6 hours by RNA-seq and ATAC-seq, respectively. Inter-ethnic responses were assessed using dream (Hoffman et al, 2020). Genotyping was performed using the Infinium OmniExpress-24, and ancestry was estimated using imputed genotypes. Expression quantitative trait loci (eQTL) mapping was performed using BRIdGE (Maranville et al, 2011). Results: Organoid lines from 54 subjects (28 AA and 26 EA) were included after removing 5 with inconsistent ancestry. For overall 1,25vitD response, 7816 differentially expressed protein-coding genes at a false discovery rate (FDR)&lt;5% were found. Gene set enrichment included the KEGG pathway “colorectal cancer” (FDR&lt;5%) with differentially responsive genes such as APC and MYC. eQTL mapping showed 131 1,25vitD-only and 21 control-only significant variants (FDR&lt;5%). For inter-ethnic 1,25vitD responses, top genes included MORC3, MAP4K3, AMACR, KYNU, PIK3CA and POLB. Results for POLB, a base-excision repair polymerase, were particularly interesting given significant inter-ethnic differences in genomic and epigenomic responses to 1,25vitD likely due to a genetic mechanism. Specifically, organoids from AA showed significantly higher POLB expression with 1,25vitD. In the region, a POLB eQTL, rs2272733, showed large allele frequency differences for the ancestral T allele (80% in Africa; 14% in Europe). This eQTL is located in a POLB enhancer region, and there is a vitamin D-responsive ATAC peak ~10kb 5' to this SNP that is only present in T/T genotypes. Conclusion: Application of organoids from diverse populations enables genome-wide assessment of population differences in host-environment interactions related to CRC. In this study, overall 1,25vitD responses were robust and found pathways relevant to CRC. eQTL mapping further established a genetic basis for 1,25vitD colonic responses. We found a number of genes that showed differences in 1,25vitD transcriptional response between AA and EA with a particularly promising CRC-relevant candidate gene, POLB. These results provide new insights into differences in host-environment interactions between populations that could underlie cancer disparities.

Citation Format: Sonia Kupfer, David Witonsky, Jinchao Li, Margaret Bielski, Kristi Lawrence. Differences in vitamin D genomic and epigenomic responses in colonic organoids from African- and European-Americans [abstract]. In: Proceedings of the AACR Virtual Conference: 14th AACR Conference on the Science of Cancer Health Disparities in Racial/Ethnic Minorities and the Medically Underserved; 2021 Oct 6-8. Philadelphia (PA): AACR; Cancer Epidemiol Biomarkers Prev 2022;31(1 Suppl):Abstract nr PO-143.

Abstract IA26: Mechanistic differences in early-onset colorectal cancer

African Americans (AAs) have higher incidence and mortality rates of colorectal cancer (CRC) compared to other US populations. AAs present with more right-sided, microsatellite stable disease, and they are diagnosed at earlier ages compared to non-Hispanic whites (NHWs). Data from the Chicago Colorectal Cancer Consortium (CCCC) suggest that the right-sided and early-onset CRCs are distinct diseases, because early-onset CRC arises more often in the distal colon (1). In addition, analysis of stage at presentation data from the SEER database suggests that early-onset CRC is on average a more rapidly developing disease that is less likely to be prevented by colonoscopy (2). To better understand these trends, we conducted exome sequencing (n=45), copy number (n=33), and methylation analysis (n=11) of microsatellite stable AA CRCs. Results were compared to data from The Cancer Genome Atlas (TCGA). In the 43 non-hypermutable tumors, only 27 (63%) contained loss-of-function mutations in APC as compared to 80% of TCGA NHW CRCs. Importantly, APC mutation-negative CRCs were associated with an earlier age of onset of CRC (p=0.01). In the TCGA, APC mutation-negative CRCs were also associated with an earlier age of onset of CRC (p=10−5). In CCCC CRCs, APC mutation-negative CRCs were also associated with previous cancer, lower overall mutation burden, and fewer copy number variants. We conducted an analysis of DNA methylation patterns and found an epigenetic signature that was distinct from the CpG island methylator phenotype characterized in microsatellite unstable disease, referred to as CIMP. Included in the list of genes that were differentially hypermethylated in APC mutation-negative CRCs were genes that regulate the WNT signaling pathway, such as SOX9, GATA6, TET1, GLIS1, and FAT1. Using the most variable differentially methylated regions from the CCCC data, we found that these regions similarly clustered in APC mutation-negative CRCs from the TCGA. These data strongly suggest that a novel epigenetic mechanism accounts for cancer development in early-onset CRCs. Contrary to the mechanism that predominates in later-onset CRC, the early-onset mechanism does not depend on mutation in the APC gene but is associated with differential methylation of WNT pathway regulating genes instead. Our data support the claim that early-onset CRC is driven by a distinct subtype of CRC that is associated with lack of APC mutation, microsatellite and chromosome stability, lower mutation burden, and distinctive DNA methylation changes. CRC driven by epigenetic changes is consistent with the epidemiologic data suggesting that early-onset CRC develops as a more rapidly advancing disease. A deeper understanding is needed of the pathways affected by the epigenetic changes and the exposures that drive those changes in order to develop therapeutic approaches to early-onset CRC.

References

1. Xicola et al. Clin Cancer Res 2014;20:4962-70.

2. Augustus et al. PLOS One 2018 13:e0200462.

Citation Format: Rosa Xicola, Zarko Manojlovic, Gaius Augustus, Sonia Kupfer, Rajyasree Emmadi, Victoria Alagiozian-Angelova, Tim Triche, Salhia Bodour, John Carpten, Xavier Llor, Nathan Ellis. Mechanistic differences in early-onset colorectal cancer [abstract]. In: Proceedings of the Eleventh AACR Conference on the Science of Cancer Health Disparities in Racial/Ethnic Minorities and the Medically Underserved; 2018 Nov 2-5; New Orleans, LA. Philadelphia (PA): AACR; Cancer Epidemiol Biomarkers Prev 2020;29(6 Suppl):Abstract nr IA26.

Morphologic and molecular analysis of early-onset gastroesophageal adenocarcinomas

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Background: The incidence of early-onset gastroesophageal adenocarcinomas (EO-GEA) is increasing, and these tumors now constitute > 30% of all gastroesophageal cancers. Besides hereditary gastric cancer syndromes, which form ~3% of EO-GEA, the morphologic and molecular spectrum of these tumors is not well-studied. Methods: Next-generation sequencing (NGS) data obtained from routine clinical care from patients with EO-GEA, defined as age ≤50 years, from 3 tertiary care centers was evaluated and compared with tumor profiles of 2,081 patients with GEA from cBioPortal for Cancer Genomics. Available histologic slides were reviewed, and the tumors were classified into Lauren and WHO subtypes. Tumor-detected pathogenic variants of potential germline origin were identified from the NGS data. Results: The study cohort was formed by 79 patients with gastroesophageal (42%) and gastric (58%) adenocarcinoma. The most commonly mutated genes included TP53 (28.5%), CDH1 (10%), ARID1A (5%), KRAS (3.9%) and PIK3CA (3.9%). EO-GEA were less likely to harbor TP53 (28.5% vs. 57.5%, p 0.003) and ARID1A (5% vs. 20.6%, p 0.002) mutations when compared with cBioPortal data. Based on the Lauren scheme, the tumors were classified into intestinal (40%), diffuse (24%), mixed (12%), and indeterminate (15%) subtypes. Driver mutations in CDH1, TP53, FBXW7, BAP1 genes were seen in diffuse/mixed subtype, and TP53, ARID1A, KRAS, PIK3CA, APC, ATM, NBN, MUTYH genes in intestinal subtype. The indeterminate subtype showed TP53 mutations and additional alterations, including SMARCB1/ SMARCA4 loss leading to rhabdoid/undifferentiated morphology. ERBB2 amplification was more likely to be present in intestinal and indeterminate subtypes (p = 0.003). CD274 amplification/PD-L1 expression was more likely to be present in indeterminate subtype (p < 0.0001). Potential germline variants included mutations in gastric cancer susceptibility genes such as CDH1 (2.5%) and APC (1%), and other cancer susceptibility genes such as ATM (4%), NBN (1%), MUTYH (1%) and POLD1 (1%). Conclusions: The molecular profile of EO-GEA is distinct from traditional gastric cancers. Histologic subtypes of EO-GEA correlate with distinct genomic alterations. Our findings also support multigene germline panel testing in parallel for patients with EO-GEA.

Suspected and confirmed germline variants from tumor-only somatic sequencing of 864 gastrointestinal malignancies

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Background: Targeted tumor-only somatic sequencing informs therapies and is becoming a routine part of cancer care. It also identifies patients with possible germline variants who require confirmatory genetic testing. The aim was to identify patients with suspected and confirmed germline variants whose GI tumors underwent somatic sequencing. Methods: 864 patients with GI tumors who had Foundation One (FO) somatic sequencing from 4/2003-3/2018 were evaluated. Inclusion criteria for suspected germline variants were: a) allele frequency ≥ 35% in hereditary cancer genes and b) pathogenic variants by FO and/or ClinVar. Variants in commonly mutated somatic genes ( TP53, KRAS, CDKN2A) were excluded in patients over age 40. Recommendation of genetic evaluation and germline test results were recorded. Patient, family, and tumor characteristics were compared using univariate analysis. Results: 199 of 864 patients had suspected germline pathogenic variants. 50 patients were recommended genetic evaluation, and 26 patients underwent genetic testing. A germline pathogenic variant was confirmed in 15 patients. Among all patients suspected to have germline variants, 8% were confirmed by genetic testing. Patients under age 40 and those with family cancer history were more often referred for testing (Table). Patients with variants in BRCA1, MLH1, MSH2, PMS2, POLE and TP53 were more often referred for testing. Conclusions: A quarter of patients carried a somatic pathogenic variant with allele frequency ≥35% in a hereditary cancer gene. 25% of these patients were recommended for genetic evaluation. Younger patients and those with family history were more often referred. 8% of patients with suspected germline variants were confirmed by genetic testing. These results provide “real world” experience in using somatic only tumor testing to identify patients with germline pathogenic variants who then might benefit from future cancer screening and genetic testing in family members. Comparison of characteristics by recommendation to undergo genetic testing based on somatic tumor sequencing results. [Table: see text]

Prevention of colonic neoplasia with polyethylene glycol: A short term randomized placebo-controlled double-blinded trial

Chemoprevention represents an attractive modality against colorectal cancer (CRC) although widespread clinical implementation of promising agents (e.g. aspirin/NSAIDS) have been stymied by both suboptimal efficacy and concerns over toxicity. This highlights the need for better agents. Several groups, including our own, have reported that the over-the-counter laxative polyethylene glycol (PEG) has remarkable efficacy in rodent models of colon carcinogenesis. In this study, we undertook the first randomized human trial to address the role of PEG in prevention of human colonic neoplasia. This was a double-blind, placebo-controlled, three-arm trial where eligible subjects were randomized to 8g PEG-3350 (n = 27) or 17g PEG-3350 (n = 24), or placebo (n = 24; maltodextrin) orally for a duration of six months. Our initial primary endpoint was rectal aberrant crypt foci (ACF) but this was changed during protocol period to rectal mucosal epidermal growth factor receptor (EGFR). Of the 87 patients randomized, 48 completed study primary endpoints and rectal EGFR unchanged PEG treatment. Rectal ACF had a trend suggesting potentially reduction with PEG treatment (pre-post change 1.7 in placebo versus -0.3 in PEG 8+ 17g doses, p = 0.108). Other endpoints (proliferation, apoptosis, expression of SNAIL and E-cadherin), previously noted to be modulated in rodent models, appeared unchanged with PEG treatment in this clinical trial. We conclude that PEG was generally well tolerated with the trial failing to meet primary efficacy endpoints. However, rectal ACFs demonstrated a trend (albeit statistically insignificant) for suppression with PEG. Moreover, all molecular assays including EGFR were unaltered with PEG underscoring issues with lack of translatability of biomarkers from preclinical to clinical trials. This data may provide the impetus for future clinical trials on PEG using more robust biomarkers of chemoprevention.

Trial registration: ClinicalTrials.gov NCT00828984

Colorectal Carcinomas With Isolated Loss of PMS2 Staining by Immunohistochemistry

Context.—

Isolated loss of PMS2 staining is an uncommon immunophenotype in colorectal carcinomas, accounting for approximately 4% of tumors with microsatellite instability. Limited information regarding these tumors is available in the literature.

Objective.—

To compare the clinicopathologic features of colorectal carcinomas with isolated PMS2 loss by immunohistochemistry to those with other forms of mismatch repair deficiency.

Design.—

Ninety-three colorectal carcinomas with isolated PMS2 loss by immunohistochemistry and 193 with other forms of mismatch repair deficiency were identified. Forty (43%) of the isolated PMS2 loss cases and 35 control cases (18%) had a known germline mutation or a clinical diagnosis of Lynch syndrome.

Results.—

Overall, isolated PMS2-loss tumors occurred in significantly younger patients (P &lt; .001) and in fewer female patients (P = .006). These tumors were significantly less likely to be right-sided (P = .001), high-grade (P = .01), or display histologic features of microsatellite instability (P &lt; .001). The isolated PMS2-loss group also exhibited increased odds of disease-specific death (odds ratio [OR], 3.09; 95% CI, 1.41–6.85; P = .007). When the analysis was restricted to germline mutation/Lynch syndrome cases and controls, no significant differences were detected for age, sex, tumor location, tumor grade, histologic features, or distant metastases, although a trend toward increased odds of disease-specific death in the isolated PMS2-loss group was evident (OR, 3.87; 95% CI, 0.89–27.04; P = .10).

Conclusions.—

Unusual clinicopathologic features observed in colorectal carcinomas with isolated PMS2 loss are likely related to the high proportion of cases caused by germline mutations. Isolated PMS2-loss tumors may demonstrate more aggressive behavior than other tumors with microsatellite instability, but larger studies are needed to investigate that possibility further.

Genetic variation in the vitamin D related pathway and breast cancer risk in women of African ancestry in the root consortium

The vitamin D related pathway has been evaluated in carcinogenesis but its genetic contribution remains poorly understood. We examined single-nucleotide polymorphisms (SNPs) in the vitamin D related pathway genes using data from a genome-wide association study (GWAS) of breast cancer in the African Diaspora that included 3,686 participants (1,657 cases). Pathway- and gene-level analyses were conducted using the adaptive rank truncated product test. Odds ratios (OR) and 95% confidence intervals (CI) were estimated at SNP-level. After stringent Bonferroni corrections, we observed no significant association between variants in the vitamin D pathway and breast cancer risk at the pathway-, gene-, or SNP-level. In addition, no association was found for either the reported signals from GWASs of vitamin D related traits, or the SNPs within vitamin D receptor (VDR) binding regions. Furthermore, a decrease in genetically predicted 25(OH)D levels by Mendelian randomization was not associated with breast cancer (p = 0.23). However, an association for breast cancer with the pigment synthesis/metabolism pathway almost approached significance (pathway-level p = 0.08), driven primarily by a nonsense SNP rs41302073 in TYRP1, with an OR of 1.54 (95% CI = 1.24-1.91, p_adj  = 0.007). In conclusion, we found no evidence to support an association between vitamin D status and breast cancer risk in women of African ancestry, suggesting that vitamin D is unlikely to have significant effect on breast carcinogenesis. Interestingly, TYRP1 might be related to breast cancer through a non-vitamin D relevant mechanism but further studies are needed.

Germline ATM mutations in families with early-onset and familial gastroesophageal and colorectal cancers

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Background: ATM is involved in repair of DNA damage due to radiation and environmental toxins via downstream interaction with CHEK2, BRCA1, and other proteins involved in double strand break repair. Mutations in ATM (Ataxia-Telangiectasia Mutated, 11q22) are among the most common hereditary cancer risk mutations in the general population (0.5-1.0% carrier rate), yet beyond risks of breast (BC) and pancreatic cancer (PC), the spectrum of clinically relevant cancer risks in ATM+ individuals remains uncertain. Thompson (JNCI 2005) previously reported possible risk of colorectal (CRC) (RR 2.54; 1.06-6.09) and gastric cancer (GC)(RR 3.39; 0.86-13.4) in ATM+ individuals, while more recently Hansford (JAMA Onc 2015) performed panel gene testing including CDH1 in patients meeting criteria for hereditary diffuse gastric cancer, and found possibly pathogenic ATM mutations in 3/144 (2%) CDH1-negative probands. In addition to GC, families contained multiple cases of BC, PC and CRC (5 cases, 2 < 50). To further describe the frequency of upper and lower GI cancer in ATM+ families, we reviewed pedigrees from 20 families seen for risk assessment in two high-risk clinics and found to have germline ATM mutations. Methods: Pedigrees from ATM+ families evaluated at Fox Chase Cancer Center and the University of Chicago are included in this analysis. Cancer type, age at diagnosis, number of genes clinically tested, and ATM mutation were collected. Cancers < 50 yrs are considered early-onset. Results: Among 20 total ATM+ families, 22 GI cancers were reported, with 5 families containing 16/22 (73%) of all GI cancers (see Table). Early-onset GI cancers were common in the 5 families (7/16, 44%), including 2/6 (33%) cases of GC, a 23 yr old man and his 45 yr old father both with GEJxn cancer (2/2, 100%), and 3/6 (50%) cases of CRC all from one large family. Conclusions: Our data lend evidence to support the need for early CRC and GC screening in ATM+ patients. [Table: see text]

Celiac patients' attitudes regarding novel therapies

BACKGROUND

The only current treatment for celiac disease (CD) is a gluten-free diet (GFD). Novel therapies are in development to supplement or replace a GFD. Knowledge of patients' attitudes toward these therapies is limited. The aim of this study was to determine attitudes about novel therapies in securely diagnosed patients with CD on a GFD and to correlate factors associated with these attitudes.

METHODS

A survey was created with two scenarios: a novel therapy that protects against cross contamination while on a GFD and one that allows intentional gluten consumption. The survey also included the Celiac Dietary Adherence Test and the CD Quality of Life (QOL) surveys.

RESULTS

A total of 182/284 (64%) CD patients completed the survey. Significantly more respondents would take a novel therapy to protect against cross contamination compared with one that allows intentional gluten consumption (87% vs. 65%; P<0.001). This difference was significant among women but not men. In both scenarios, protection against bowel inflammation was significantly more important than symptom control, and side effects were more important than cost. For a novel therapy that would allow intentional gluten consumption, a one-time injection was preferred over a daily pill, and patients willing to take this therapy had significantly lower QOL scores.

CONCLUSIONS

CD patients on a GFD are interested in novel therapies. There were notable differences in attitudes by gender and QOL. Considering patient preferences, drugs with daily or less frequent dosing that protect against bowel inflammation from gluten cross contamination would be best accepted.

Abstract B19: Colonic transcriptional response to 1,25(OH)2 vitamin D in African and European Americans

Background: 1,25(OH)2 vitamin D (1,25vitD) is a steroid hormone with anti-cancer effects that functions through direct transcriptional mechanisms. In colorectal cancer (CRC), 1,25vitD is thought to play a protective role; however, it is not known to what extent inter–ethnic differences in transcriptional response could underlie differences in disease susceptibility in African-Americans (AA) whose incidence of CRC is the highest in the US. To study differences in short-term transcriptional response in the colon, we have optimized an ex vivo culture system using colonic biopsies obtained during colonoscopy, thereby eliminating a number of confounders. We use this system to study transcriptional responses between ethnicities.

Methods: Healthy subjects (n=69; 34 in discovery cohort & 35 in replication cohort) undergoing colonoscopy were consented and colonic biopsies were obtained at the rectosigmoid junction. Two colonic biopsies each were treated with 0.1μM 1,25vitD or vehicle control (EtOH) and incubated for 6 hours at 37°C. For the discovery cohort, RNA from two treatment replicates was pooled and hybridized to Illumina Human HT-12 expression chips. Transcriptional response was analyzed using the packages LUMI and LIMMA in R adjusting for covariates and multiple testing. For the replication cohort, expression for select genes was performed using quantitative real-time PCR. In silico analysis was done to identify vitamin D receptor (VDR) binding peaks using ChIP-sequence data from LS180 cell lines.

Results: In the discovery cohort, 16 AA and 18 European Americans (EA) were included. As proof of concept, the top two significantly up-regulated genes were CD14 (p=1.15x10-25) and CYP24A1 (p=7.65x10-23). There were 10 genes that showed significantly different responses to 1,25vitD between AA and EA including UPP1, UCKL1, ZSWIM4, ERCC1, MFSDA2, EPHA2, CLRN3, KIAA1324, TRIP8 and WDR55. In the replication cohort, 20 AA and 15 EA were included. Of 5 genes tested to date, 3 genes (UPP1, ERCC1 & ZSWIM4) showed evidence of replication with similar direction and effect sizes as the discovery cohort. Two genes (UCKL1 & UPP1) have VDR binding peaks within an intron (UCKL1) or 21kb downstream (UPP1). Within these peaks, there are SNPs with allele frequency differences between Africans and Europeans. In particular, the UCKL1 SNP rs58190754 that is located within the DR3 binding motif and is predicted to be functionally significant for VDR binding has an allele frequency of 10% in YRI & AA and &lt;1% in Europeans.

Conclusions: Using short-term ex vivo culture of primary colonic tissue, we found significantly up- and down-regulated genes in response to 1,25vitD including a number of established 1,25vitD targets. There were 10 genes with significantly different transcriptional responses to 1,25vitD treatment between AA and EA of which 3 genes have been replicated in preliminary work. Two genes (UPP1 & UCKL1) harbor VDR binding peaks with candidate SNPs that could be functionally relevant for gene expression differences between populations. These genes are involved in pyrimidine salvage and could have a role in cancer susceptibility. Future work will genotype SNPs and determine whether genotype predicts expression. In addition, functional assays of pyrimidine salvage are being tested. Finally, replication of additional genes is ongoing. Further studies of these genes may reveal important pathways underlying CRC disparities.

Citation Format: Sonia Kupfer, Brandon Mapes, Shigeki Nakagome, David Witonsky, Anna Di Rienzo. Colonic transcriptional response to 1,25(OH)2 vitamin D in African and European Americans. [abstract]. In: Proceedings of the Eighth AACR Conference on The Science of Health Disparities in Racial/Ethnic Minorities and the Medically Underserved; Nov 13-16, 2015; Atlanta, GA. Philadelphia (PA): AACR; Cancer Epidemiol Biomarkers Prev 2016;25(3 Suppl):Abstract nr B19.

Abstract B20: Genetic testing for inherited colorectal cancer among African Americans and Caucasians in the era of multigene panels

Background: There is little data about ethnic differences in genetic testing for inherited colorectal cancer (CRC) syndromes. We previously found that African Americans were less likely to be tested for inherited CRC syndromes. With the advent of multigene panel testing, we sought to determine whether there are differences in genetic testing among African Americans and Caucasians over the last 4 years.

Aim: Compare patterns of genetic testing for inherited colorectal cancer between African Americans and Caucasians with personal history of CRC or colonic polyps seen in a cancer risk clinic at a single academic institution.

Methods: We identified patients with personal history of colon polyps or CRC who were seen in our academic cancer risk clinic between 2011-2015. This time period was selected because multigene panels became commercially available. Patient characteristics were compared between patients tested and those who were not tested for CRC syndromes by race. Multigene panel and single syndrome (i.e., Lynch syndrome or FAP) testing between African Americans and Caucasians was compared. All patients in this study signed informed consent to be part of a clinical registry.

Results: A total of 171 patients were identified with a personal history of colon polyps and/or CRC from our registry between 2011-2015. Patients had a mean age of 55.5 years, 62% were female, 66% were Caucasian and 22% African American. Of 171 patients, 101 (59%) underwent germline testing and 70 (41%) did not undergo germline testing. Of those who did not have germline testing, 55/70 (79%) were not offered testing, while 13/70 (19%) declined testing. Differences between African Americans (n=40) and Caucasians (n=112) are detailed in Table 1. Fewer African Americans than Caucasians were tested though this was not statistically significant (50% vs. 59.8%, respectively; p=0.19). There was no difference in declined testing between African Americans and Caucasians (20% vs. 17.8%, respectively; p=0.32). Tested African Americans were older than tested Caucasians (57.6 years vs. 51 years, respectively; p=0.04). There were no differences in gender between races among tested patients (p=0.35). There was no difference in multigene panel compared to single syndrome testing by race (p=0.58). Multigene panel testing was performed in 31 (45.6%) Caucasians and 9 (45.0%) African Americans.

Conclusion: Overall, about 60% of patients with personal history of colon polyps or cancer seen in an academic cancer risk clinic underwent genetic testing. Regarding differences by race, we noted a trend toward fewer African Americans getting germline testing; however, the difference was not statistically significant. Among tested individuals, African Americans were significantly older. There were no differences in multigene panel versus single syndrome testing between races. Further investigation is required to determine reasons for lower genetic testing in African Americans at older ages, though these differences do not appear to vary by multigene panel versus single syndrome testing approaches.

Citation Format: Jessica Stoll, Funmi Olopade, Sonia Kupfer. Genetic testing for inherited colorectal cancer among African Americans and Caucasians in the era of multigene panels. [abstract]. In: Proceedings of the Eighth AACR Conference on The Science of Health Disparities in Racial/Ethnic Minorities and the Medically Underserved; Nov 13-16, 2015; Atlanta, GA. Philadelphia (PA): AACR; Cancer Epidemiol Biomarkers Prev 2016;25(3 Suppl):Abstract nr B20.

Abstract A75: Excess of proximal microsatellite-stable colorectal cancer in African Americans from a multiethnic study

Background: African Americans (AAs) have the highest incidence of colorectal cancer (CRC) compared to other US populations and more proximal CRCs. The objective is to elucidate the basis of these cancer disparities.

Methods: 566 AA and 328 Non-Hispanic White (NHW) CRCs were ascertained in five Chicago hospitals. Clinical and exposure data were collected. Microsatellite instability and BRAF (V600E) and KRAS mutations were tested. Statistical significance of categorical variables was tested by Fisher's exact test or logistic regression and age by Mann-Whitney U test.

Results: Over a ten-year period, the median age at diagnosis significantly decreased for both AAs (68 to 61; P&lt;0.01) and NHWs (64.5 to 62; P=0.04); more AA patients were diagnosed before age 50 than NHWs (22% vs 15%; P=0.01). AAs had more proximal CRC than NHWs (49.5% vs. 33.7%; P&lt;0.01), but overall frequencies of microsatellite instability, BRAF and KRAS mutations were not different nor were they different by location in the colon. Proximal CRCs often presented with lymphocytic infiltrate (P&lt;0.01) and were diagnosed at older ages (P=0.02). Smoking, drinking, and obesity were less common in this group, but results were not statistically significant.

Conclusions: Patients with CRC have gotten progressively younger. The excess of CRC in AAs predominantly consists of more proximal, microsatellite stable tumors, commonly presenting lymphocytic infiltrate and less often associated with toxic exposures or a higher BMI. Younger AAs had more distal CRCs than older ones. These data suggest two different mechanisms driving younger age and proximal location of CRCs in AAs.

Citation Format: Rosa Xicola, The Chicago Colorectal Cancer Consortium, Sonia Kupfer, Carol Braunschweig, Nathan Ellis, Xavier Llor. Excess of proximal microsatellite-stable colorectal cancer in African Americans from a multiethnic study. [abstract]. In: Proceedings of the Seventh AACR Conference on The Science of Health Disparities in Racial/Ethnic Minorities and the Medically Underserved; Nov 9-12, 2014; San Antonio, TX. Philadelphia (PA): AACR; Cancer Epidemiol Biomarkers Prev 2015;24(10 Suppl):Abstract nr A75.

Dynamic inversion enables external magnets to concentrate ferromagnetic rods to a central target

The ability to use magnets external to the body to focus therapy to deep tissue targets has remained an elusive goal in magnetic drug targeting. Researchers have hitherto been able to manipulate magnetic nanotherapeutics in vivo with nearby magnets but have remained unable to focus these therapies to targets deep within the body using magnets external to the body. One of the factors that has made focusing of therapy to central targets between magnets challenging is Samuel Earnshaw's theorem as applied to Maxwell's equations. These mathematical formulations imply that external static magnets cannot create a stable potential energy well between them. We posited that fast magnetic pulses could act on ferromagnetic rods before they could realign with the magnetic field. Mathematically, this is equivalent to reversing the sign of the potential energy term in Earnshaw's theorem, thus enabling a quasi-static stable trap between magnets. With in vitro experiments, we demonstrated that quick, shaped magnetic pulses can be successfully used to create inward pointing magnetic forces that, on average, enable external magnets to concentrate ferromagnetic rods to a central location.

Abstract 2191: Identification of functional risk alleles in colorectal cancer-associated regions in African Americans

Background. There are disparities in both colorectal cancer (CRC) incidence and survival between African Americans (AAs) and Non-Hispanic Whites (NHWs). Genetic susceptibility factors are believed to contribute to CRC development but have been inadequately studied in AAs. Our previous work showed both shared and independent CRC-associated risk alleles are present in some gene regions identified in genome-wide association studies (GWAS) in NHWs. In the present work, using a functional bioinformatics approach, we searched for risk alleles in these regions in AAs. Methods. 10 chromosomal regions (8q23.3, 8q24.21, 10p14, 11q23.1, 14q22.2, 15q13.3, 16q22.1, 18q21.1, 19q13.11, 20p12) from COGENT consortium meta-analysis were selected for DNA sequencing. Three additional high-interest regions were included. The region surrounding each associated SNP was analyzed using r2 plots, based on European-ancestry genotype data from HapMap Phase 3. DNAs from 63 individuals (25 AA CRC cases and 38 AA controls) were sequenced using Agilent SureSelect enrichment arrays and Illumina HiSeq platform technology. Variants from the targeted sequencing were combined with 1000 genomes variant data for a total of 16,193 variants. Potentially functional variants were identified based on the following criteria: the variant is (i) in a coding region, (ii) an expression quantitative trait locus (eQTL) or a DNAseI eQTL (DsQTL), (iii) in a miRNA binding site, and (iv) in a transcription factor binding site. Golden Helix software was used to process the data. Using the Sequenom Massarray platform, we genotyped variants in discovery and replication sets for a total of 1177 AA CRC cases and 1264 AA controls. We calculated odds ratios (OR) and 95% confidence intervals using logistic regression, assuming an additive genetic model and adjusting for age, sex, and African ancestry. Results. We identified 81 variants in coding sequences, 82 eQTLs, 5 dsQTLs, 38 variants in putative microRNA binding sites, 33 variants in possible transcription factor binding sites, and 6 variants that are in two or more of the preceding categories, for a total of 245 variants. After assay development and quality control, 163 SNPs were available for genetic analysis. Nominal associations (p&lt;0.05) were detected between CRC and 17 variants. We have completed genetic analysis in the replication set for 8 of the 17 SNPs. The SNPs rs1862748 (OR, 0.73; P = 0.001) in the CDH1 region and 16888699 (OR, 1.39; P = 0.0006) in the EIF3H region were statistically significant in both the discovery and replication series. rs1862748 has previously been associated with AA CRC and was identified as a eQTL for ZFP90. rs16888699 was identified as an eQTL for UTP23. Conclusion. Our results suggest that rs1862748 and rs16888699 are CRC risk alleles, validating the bioinformatics approach. Functional studies will are now needed to characterize the genetic mechanisms underlying risk.

Citation Format: Fabio Pibiri, Ricky Rechenmacher, Rosa Xicola, Rick Kittles, Robert Sandler, Temitope Keku, Xavier Llor, John Carpten, Sonia Kupfer, Nathan Ellis. Identification of functional risk alleles in colorectal cancer-associated regions in African Americans. [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 2191. doi:10.1158/1538-7445.AM2014-2191

Cancer risks and mutation spectrum of mismatch repair genes in African American families with Lynch syndrome

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Background: Although African Americans (AA) have the highest colorectal cancer (CRC) incidence and mortality of all populations in the United States, no studies have determined cancer risk and mismatch repair (MMR) genes mutation spectrum in LS patients of AA ancestry and the contribution of this syndrome to cancer disparities. Thus, the aims of this study are: (1) to describe LS cancers in AAs; (2) to investigate the mismatch repair (MMR) gene mutation spectrum in AA families with LS; (3) to determine how Amsterdam II criteria, revised Bethesda guideline, and PREMM(1,2,6) model perform for predicting MMR gene mutations in this population. Methods: Pedigrees of AA families with deleterious mutation or suspected deleterious mutation in MMR genes from five US referral centers were analyzed for personal and familial clinical cancer histories. Results: Twenty-four AA families were identified, of which 22 had deleterious mutations (15 MLH1, 4 MSH2, 2 MSH6, 1 PMS2) and 2 had suspected deleterious mutations (1 MLH1, 1 MSH2). Three recurrent mutation were found in MLH1(677G>A, IVS1-2A>G, IVS4-1G>A), accounting for 25% of all mutations. Of 24 probands, 58% were female and 96% had personal history of cancer. The median age at first primary tumor was 42yrs (range 28-57) and 50% developed more than 1 primary tumor. The majority of probands (79%) had CRC (median age of onset – 42yrs [range 31-61]), of which 26% had at least 2 CRC primaries. Endometrial cancer developed in 50% of the women (median age of onset – 51yrs [range 32-57]). Amsterdam II and Bethesda criteria were met in 63% and 88% of the individuals, respectively. Median score by PREMM(1,2,6) model was 54% (range 12.9-99.8). Conclusions: To our knowledge, this is the largest series of AA families with LS reported to date. Earlier age of onset for CRC at 42yrs (previously reported ~45 yrs) is suggested. The majority of mutations were found in MLH1 (67%), including three recurrent mutations. A 10% cutoff for PREMM(1,2,6) predictive model identified all mutation carriers. Larger studies are warranted to confirm the differences observed in age of CRC onset in this population.

Abstract 1330: Genetic variation in the vitamin D pathway and risk for colorectal cancer in African Americans

Background: Colorectal cancer (CRC) is the third leading cause of cancer-related deaths in both sexes in the United States. There is a large disparity in both CRC incidence and survival between African Americans (AAs) and all other US racial groups. Differences in serum vitamin D levels could contribute to this disparity because vitamin D is thought to protect against CRC and AAs have lower serum vitamin D levels than whites. We hypothesized that genetic variants in vitamin D-related genes are associated with CRC risk in AAs.

Methods: To evaluate association with CRC risk, we genotyped 39 putatively functional single nucleotide polymorphisms (SNPs) in vitamin D-related genes (CYP27A1, GC, CYP3A4, CYP2R1, DHCR7/NADSYN1, VDR, CYP27B1 and CYP24A1, in 961 AA cases (292 right colon, 340 left colon, 113 rectal) and 838 AA controls from the North Carolina Colorectal Cancer Study and the Chicago Colorectal Cancer Consortium. We calculated odds ratios (OR) using logistic regression, assuming an additive genetic model and controlling for age, gender, and West African ancestry. We further evaluated whether the genetic polymorphisms conferred differential risk for right-sided CRC (R-CRC) and left-sided CRC (L-CRC, including rectal).

Results: Nominal associations (p&lt;0.05) were detected between CRC and SNPs in the 24-hydroxylase gene CYP24A1, rs73913755 (OR, 0.73; P = 0.0003), which degrades calcidiol, and the 25-hydroxylase gene CYP2R1, rs12794714 (OR, 0.82; P = 0.032), which converts cholecalciferol into calcidiol. When we analyzed R-CRC and L-CRC separately, no SNPs were associated with R-CRC, whereas 4 SNPs were associated with L-CRC. Two SNPs in the vitamin D binding protein gene GC, rs1155563 (OR, 0.77; P = 0.039) and rs16847024 (OR, 1.56; P = 0.003) and two SNPs in the 24-hydroxylase gene CYP24A1, rs6022990 (OR, 1.48; P = 0.006) and rs73913755 (OR, 0.67; P = 0.0002). The P value for rs73913755 was statistically significant after adjustment for multiple testing.

Conclusion: Our results indicate that several SNPs in the vitamin D pathway contribute to CRC susceptibility in AAs. The minor allele of rs73913755 was present in at least one dose in 48% of AA controls and only 30% of cases, conferring increased protection against L-CRC. We hypothesize that the minor allele of rs73913755 causes a reduction in the expression levels of CYP24A1. Because rs73913755 is African-specific, showing high Fst value in comparison to ancestrally European populations, its presence could explain in part the lower proportion of L-CRC in AAs compared to whites. Future studies include analysis of vitamin D pathway gene expression levels relative to genotype and analysis of possible gene-vitamin D level interactions in AA CRC.

Citation Format: Fabio Pibiri, Nathan Ellis, Rick Kittles, Xavier LLor, Rosa Xicola, Sonia Kupfer, Robert S. Sandler, Temitope Keku. Genetic variation in the vitamin D pathway and risk for colorectal cancer in African Americans. [abstract]. In: Proceedings of the 104th Annual Meeting of the American Association for Cancer Research; 2013 Apr 6-10; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2013;73(8 Suppl):Abstract nr 1330. doi:10.1158/1538-7445.AM2013-1330

Antihypertensive efficacy of the angiotensin receptor blocker azilsartan medoxomil compared with the angiotensin-converting enzyme inhibitor ramipril

Drug therapy often fails to control hypertension. Azilsartan medoxomil (AZL-M) is a newly developed angiotensin II receptor blocker with high efficacy and good tolerability. This double-blind, controlled, randomised trial compared its antihypertensive efficacy and safety vs the angiotensin-converting enzyme inhibitor ramipril (RAM) in patients with clinic systolic blood pressure (SBP) 150-180 mm Hg. Patients were randomised (n=884) to 20 mg AZL-M or 2.5 mg RAM once daily for 2 weeks, then force-titrated to 40 or 80 mg AZL-M or 10 mg RAM for 22 weeks. The primary endpoint was change in trough, seated, clinic SBP. Mean patient age was 57±11 years, 52.4% were male, 99.5% were Caucasian. Mean baseline BP was 161.1±7.9/94.9±9.0 mm Hg. Clinic SBP decreased by 20.6±0.95 and 21.2±0.95 mm Hg with AZL-M 40 and 80 mg vs12.2±0.95 mm Hg with RAM (P<0.001 for both AZL-M doses). Adverse events leading to discontinuation were less frequent with AZL-M 40 and 80 mg (2.4% and 3.1%, respectively) than with RAM (4.8%). These data demonstrated that treatment of stage 1-2 hypertension with AZL-M was more effective than RAM and better tolerated.

Abstract 1661: Fine-mapping of GWAS variants in BMP4, GREM1, CDH1, and RHPN2 in African American colorectal cancer patients

Background: Genome-wide association studies (GWAS) of colorectal cancer (CRC) have identified risk variants in candidate genes involved in TGF-ß signaling including BMP4, GREM1, CDH1, RHPN2 and SMAD7. We previously replicated the association with a 3′-UTR SNP in GREM1 (rs10318) in African Americans but did not find evidence of associations in the other genes. This finding could be explained by different genomic structure in African Americans. Therefore, we sought to fine-map these genes to identify CRC risk variants in African Americans who are at highest risk of CRC in the US. Methods: DNA from cases and controls was obtained from two US institutions. In total, we included DNA from 795 AA cases and 985 AA controls. TagSNPs with minor allele frequencies &gt;5% and pairwise r2 &gt;0.8 were identified in five genes using YRI Hapmap data. A total of 81 SNPs were genotyped in cases and controls using Sequenom MassARRAY. We calculated odds ratios and 95% confidence intervals using logistic regression controlling for ancestry, age, gender and multiple testing in PLINK. Results: Association analysis was completed for four genes: BMP4, GREM1, CDH1 and RHPN2. The top tagSNP associations for each gene are shown in the Table. None of the SNPs were significant after permutation testing. In GREM1, the strongest SNP associations were found at the 3′ end of the gene. In BMP4, we identified two SNPs (rs1957852 and rs7146040) that are in LD with rs4444235 previously identified in a European GWAS. In CDH1, rs12931189 is located in the same LD block as the strongest association signal (rs7199991) in a recent fine-mapping study in Europeans. Finally, we have no evidence for associations in RHPN2 in African Americans. Conclusion: These results provide preliminary evidence of associations in African American colorectal cancer patients in BMP4, GREM1 and CDH1 identified by GWAS in Europeans. Ongoing work is testing associations in SMAD7 and further fine-mapping by imputation and resequencing in these regions.

Abstract 3597: The Chicago Colorectal Cancer Consortium (CCCC) experience: Understanding colorectal cancer disparities

Colorectal cancer (CRC) affects disproportionally African Americans (AAs) who have a 20% higher incidence and a 40% higher mortality than Caucasians. Very few studies have specifically addressed CRC in AAs. In order to uncover the factors that underlie this disparity we set up the CCCC, a large, robust and well-characterized database and biorepository of CRC patients from the Chicago metropolitan area that is highly enriched with AAs. The project enrolls newly diagnosed CRCs, polyps at different stages, and cancer/polyp-free controls in 5 large hospitals. Extensive clinical, family history, demographic, dietary, toxic exposure data is collected along with tumor and uninvolved mucosa as well as plasma, serum, and paraffin-embedded samples. Tumors are molecularly characterized and germline DNA is used to assess genetic factors implicated in CRC development. The primary goal of the project is to study how genetic and environmental factors as well as their interaction contribute to CRC development and which factors make AAs more prone to develop this cancer. We will also assess specific factors that may contribute to the worse prognosis in AAs. Results: A total of 205 CRCs, (58% AAs), 86 patients with high-risk adenomas, 75 mild-risk adenomas, and 173 controls have been recruited so far. The mean age at diagnosis was 60.2 for AAs and 61.8 for whites (P=0.08), in both cases significantly lower than the mean age reported for the US CRCs in general (68-70). There was a significantly higher number of AA patients younger than age 50 at diagnosis (19.5% vs. 7.1% whites; P=0.043). In AA patients tumors were more often on the right side of the colon (43.3% vs. 22.7%; P=0.02) and more were undifferentiated (19.1% vs. 3.5%; P=0.03). Both groups had a similar number of colonoscopies before cancer diagnosis (60.2% for AAs vs. 68.3% for whites; P=0.11). While there was no significant difference among AA cases and controls regarding high tobacco use (&gt;20 pack/years)(16.9% cases vs. 17.1% controls), more whites with CRC were heavy smokers (45.7% cases vs. 29.7 controls). Less AA patients reported family history of CRC than whites (16.4% vs. 35.2%; P0.02) or family history of polyps (21.7% vs. 44%). Conclusions: In our urban cohort both AA and white patients present CRC significantly earlier than expected. Very important differences are seen between AAs and whites that may have significant implications when considering CRC screening approaches, such as the high percentage of AA patients diagnosed before age 50 or the much higher number of right-sided tumors. Heavy tobacco use seems to associate with CRC in whites but not in AAs. Altogether points towards important biological differences that need to be further assessed. As we are ascertaining toxic and dietary exposure and molecularly characterizing all tumors, eventually we should be able to explain the biological basis of the significant disparity in CRC

Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 103rd Annual Meeting of the American Association for Cancer Research; 2012 Mar 31-Apr 4; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2012;72(8 Suppl):Abstract nr 3597. doi:1538-7445.AM2012-3597

Abstract B73: The Chicago Colorectal Cancer Consortium (CCCC), a step forward in understanding colorectal cancer in African Americans

Background: Colorectal cancer (CRC) is the third leading cause of cancer-related death in both sexes in the United States. While the overall CRC incidence rates have declined over the past 10 years, the disparity between African Americans (AAs) and non-Hispanic whites has increased and the incidence in AAs remains higher than in other populations. Very few studies have specifically addressed CRC in AAs, and important studies on CRC almost never include significant numbers of AAs to draw any firm conclusions.

Objective: To establish a large, robust and well-characterized database and bio-repository collection of CRC from AA patients and controls strengthening a collaborative working group, the Chicago Colorectal Cancer Consortium (CCCC), which spans 5 of the main hospitals of the Chicago area. We collect clinical, demographic and dietary data; and a biological repository of specimens consisting of tumor and non-tumor genomic DNA, RNA, plasma, serum, and paraffin-embedded samples.

Specific Aims: The primary goal of the project is to study how genetic and environmental factors and their interaction result in the development of CRC. We will also study prognosis determinants in the AA population.

Results: Recruitment and data collection: So far we have recruited 56 AA and 17 white-non Hispanic adenocarcinoma colorectal patients. We have also recruited 84 AAs and 32 white patients with adenomatous polyps, and 44 AAs and 30 white controls (individuals without polyps or previous history of polyps). From all individuals we have collected demographic/socioeconomic data, clinical data, family history of cancer, medication and toxic substance history, and dietary data using the Block Brief 2000 Food Frequency Questionnaire.

Preliminary analyses: To identify potential variables that could influence the cancer disparity between AAs and whites, we performed a preliminary analysis of all these data using a Fisher exact test.

A systematic molecular analysis of BRAF and KRAS mutations, microsatellite instability and presence of CpG island methylation phenotype in all CRC tumors is being performed. We are also analyzing protein expression of the mismatch repair genes through immunohistochemistry. We will test for an association between these molecular features and clinical variables. Moreover, 1 year follow-up data is already available and being collected on 23 cases. Therefore, we will soon be able to start investigating the relationship of those molecular features with survival and specific chemotherapy response. Summary: The preliminary analysis has highlighted some significant differences between AA and white CRC patients. In comparison with white patients, a higher proportion of AA patients are less than 50 years at diagnosis, take NSAIDS, and fulfill Bethesda criteria, which is a set of criteria to select out patients to be pre-screened for mismatch repair deficiency and eventually for genetic testing to rule out Lynch syndrome.

It has also highlighted that CRC patients have a lower level of education than cancer-free individuals in both ethnicities. This type of sociocultural disparities could potentially be associated with different life styles. In fact, AA CRC cases consumed more carbohydrates than controls reflecting this potential life style difference.

Cancer Relevance: Understanding the key molecular features and environmental factors that impact CRC development in the AA population is of paramount importance given the scarce information available. Understanding the role genetic factors will be crucial to help risk stratify patients, recommend screening modalities, and recommend preventive measures. When this information is combined with environmental factors, such as dietary habits, we will be able to offer a comprehensive personalized medicine approach for AA CRC patients.

Citation Information: Cancer Epidemiol Biomarkers Prev 2011;20(10 Suppl):B73.

EGFR signals downregulate tumor suppressors miR-143 and miR-145 in Western diet-promoted murine colon cancer: role of G1 regulators

Epidermal growth factor receptors (EGFR) contribute to colonic tumorigenesis in experimental models of colon cancer. We previously showed that EGFR was also required for colonic tumor promotion by Western diet. The goal of this study was to identify EGFR-regulated microRNAs that contribute to diet-promoted colonic tumorigenesis. Murine colonic tumors from Egfr(wt) and hypomorphic Egfr(wa2) mice were screened using micro RNA (miRNA) arrays and miR-143 and miR-145 changes confirmed by Northern, real-time PCR, and in situ analysis. Rodent and human sporadic and ulcerative colitis (UC)-associated colon cancers were examined for miR-143 and miR-145. Effects of EGFR on miR-143 and miR-145 expression were assessed in murine and human colonic cells and their putative targets examined in vitro and in vivo. miR-143 and miR-145 were readily detected in normal colonocytes and comparable in Egfr(wt) and Egfr(wa2) mice. These miRNAs were downregulated in azoxymethane and inflammation-associated colonic tumors from Egfr(wt) mice but upregulated in Egfr(wa2) tumors. They were also reduced in human sporadic and UC colon cancers. EGFR signals suppressed miR-143 and miR-145 in human and murine colonic cells. Transfected miR-143 and miR-145 inhibited HCT116 cell growth in vitro and in vivo and downregulated G(1) regulators, K-Ras, MYC, CCND2, cdk6, and E2F3, putative or established targets of these miRNAs. miRNA targets Ras and MYC were increased in colonic tumors from Egfr(wt) but not Egfr(wa2) mice fed a Western diet. EGFR suppresses miR-143 and miR-145 in murine models of colon cancer. Furthermore, Western diet unmasks the tumor suppressor roles of these EGFR-regulated miRNAs.

Abstract 4734: Validation of genome-wide colorectal cancer genetic risk factors in African- and European-Americans

Background: Genome-wide association studies have identified several colorectal cancer (CRC) genetic risk factors. However, these studies have been performed primarily in individuals of European descent and none include African Americans (AAs). Determining CRC genetic risk factors in AAs is important because CRC incidence and mortality rates are highest of all US populations.

Aim: To validate genome-wide CRC genetic risk factors, we tested single nucleotide polymorphism (SNP) associations in ten chromosome (chr) regions in AAs and European-Americans (EAs).

Methods: We genotyped 22 SNPs in 1725 AA and 883 EA CRC cases and controls using Sequenom iPLEX. Ancestry estimates were obtained using STRUCTURE 2.1. We tested for allelic association and calculated odds ratios and confidence intervals using logistic regression adjusting for ancestry, age and gender.

Results: Association results are shown in the Table. In AAs, rs10795668 (chr 10) and rs10318 (chr 15) were significantly associated with CRC. rs7014346 (chr 8) and rs355527 (chr 20) trended toward significant associations. In EAs, three SNPs on chr 8 were significantly associated with CRC. In addition, two chr 11 SNPs (rs3802842 & rs1074997) and rs1862748 (chr 16) were significantly associated with disease in EAs. SNPs on chr 15 and chr 16 are located in or near genes GREM1 and CDH1 respectively. SNPs on chr 8, 10, 11 and 20 are in gene deserts.

Conclusion: This is the first study to validate genome-wide SNP associations in AAs. We also confirm several associations in EAs. SNPs on chr 15 & 16 are located in genes involved in TGFβ signaling (GREM1 & CDH1) which has been implicated in CRC pathogenesis, while those on chr 8, 10, 11 and 20 are in gene deserts. Future fine-mapping in these regions is warranted to identify functional variants.Genome-wide SNP associations in African- and European-AmericansChr (gene)SNPReference alleleAllele frequency casesAllele frequency controlsOR [95% CI]p*African Americans      8rs7014346A0.420.391.14 [0.99-1.31]0.0710rs10795668A0.080.061.41 [1.07-1.87]0.0415 (GREM1)rs10318T0.050.031.45 [1.02-2.05]0.0520rs355527A0.180.200.87 [0.73-1.04]0.09European Americans      8rs6983626T0.120.091.38 [1.00-1.91]0.058rs6983267G0.520.471.24 [1.01-1.51]0.048rs7837328A0.430.371.30 [1.06-1.60]0.0111rs3802842C0.330.281.26 [1.02-1.57]0.0211rs10749971G0.410.331.42 [1.15-1.74]0.000216 (CDH1)rs1862748T0.280.320.80 [0.64-0.99]0.04

Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 101st Annual Meeting of the American Association for Cancer Research; 2010 Apr 17-21; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2010;70(8 Suppl):Abstract nr 4734.

Abstract 4731: Resequencing of the MYC-335 enhancer in the colorectal cancer associated 8q24 region

Genome-wide association studies have identified multiple different regions at 8q24 associated with risk of colorectal, prostate, breast and bladder cancers. It has been suggested that the cancer predisposition could be mediated through altered MYC expression. One of the regions, marked by SNP rs6983267, has been consistently shown to confer susceptibility to colorectal and prostate cancers. In our previous work, we aimed to understand the biological basis of the colorectal cancer (CRC) predisposition associated with the G allele of rs6983267. By utilizing a computer program, Enhancer Element Locator, we showed that rs6983267 affects a TCF4 binding site in an evolutionary conserved enhancer element (MYC-335). Enhancer activity of this element was confirmed in vitro and in vivo. The G allele of rs6983267 was shown to enhance the activity of the MYC-335, and in the presence of active Wnt signaling potentially lead to increased expression of a target gene, possibly MYC. To examine the contribution of other variants in the MYC-335 to CRC predisposition, we determined the genetic variation within MYC-335 in different ethnic groups by resequencing the 1271-bp genomic fragment in Caucasian, African and African American samples. This effort identified eight variants which showed population-specific allele frequencies. One variant, a 2-bp deletion, affected a putative transcription factor binding site and was present only in individuals with African origin. The deletion affected GA nucleotides at the fifth and sixth position of the putative binding sequence for transcriptional repressor GFI1 (CAGAGATTGC). The identified GFI1 binding sequence is evolutionary highly conserved and the deletion is predicted to cause a 5.5-fold lower binding affinity. Both the SNP rs6983267 and the GA deletion affect transcription factor binding sites and are differentially distributed in different ethnic populations, which suggests that both alleles are functional and under selective pressure from environmental exposure. We hypothesized that the deletion could contribute to CRC predisposition by abolishing the binding of the repressor, which in turn would lead to enhanced transcriptional activity. Here, we show preliminary results that GFI1 has preferential binding affinity for the wild type allele in the heterozygous cell line HeLa. Also, we investigated the role of the deletion in CRC predisposition in African American individuals. The 2-bp deletion identified here might be a novel population-specific colorectal cancer risk variant.

Note: This abstract was not presented at the AACR 101st Annual Meeting 2010 because the presenter was unable to attend.

Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 101st Annual Meeting of the American Association for Cancer Research; 2010 Apr 17-21; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2010;70(8 Suppl):Abstract nr 4731.

Improved culture methods to expand Schwann cells with altered growth behaviour from CMT1A patients

A duplication of the gene for myelin protein PMP22 is by far the most common cause of the hereditary demyelinating neuropathy CMT1A. A role for PMP22 in cell growth in addition to its function as a myelin protein has been suggested because PMP22 is homologous to a gene specifically upregulated during growth arrest. Furthermore, transfected rat Schwann cells overexpressing PMP22 show reduced growth. In addition, abnormal Schwann cell differentiation has been described in nerve biopsies from CMT1A patients. To analyse whether the duplication of the PMP22 gene in CMT1A neuropathy primarily alters Schwann cell differentiation and to exclude nonspecific secondary responses, we improved human Schwann cell culturing. This allowed us long-term passaging of human Schwann cells with unchanged phenotype, assessed by expression of different Schwann cell markers. Subsequently we established Schwann cell cultures from CMT1A nerve biopsies. We find decreased proliferation of Schwann cells from different CMT1A patients in all passages. We also demonstrate PMP22 mRNA overexpression in cultured CMT1A Schwann cells. We conclude that decreased proliferation in cultured Schwann cells that carry the CMT1A duplication indicates abnormal differentiation of CMT1A Schwann cells. The identification of an abnormal phenotype of CMT1A Schwann cells in culture could possibly lead to an in vitro disease model.

Renal biopsy: why and when

The purpose of this paper is to emphasize the importance of information obtained by renal biopsy in the diagnosis, prognosis, and therapy of patients with renal disease. Because controversy persists regarding the value of renal biopsy as an aid in determining prognosis and in choosing appropriate therapy, there has been some reluctance to use it early after the onset of obvious signs, symptoms, and laboratory findings indicative of renal disease with or without involvement of other organs. Although all such patients may not benefit from the information provided by a proper biopsy, we will illustrate some of the characteristic histologic details found in specific circumstances in our experience where the biopsy has been particularly helpful in reaching a diagnosis, in assessing prognosis, and in choosing therapy.

Full-lenth cloning, expression and cellular localization of rat plasmolipin mRNA, a proteolipid of PNS and CNS

We have isolated a 1.476 bp cDNA (NTII11) representing a transcript that is differntially expressed during sciatic nerve development and regeneration in the rat. Nucleotide sequence comparison indicates partial identity with a recently isolated plasmolipin cDNA. However, our clone extends the published sequence by 234 bp at the 5' end and predicts a protein that contains an additional 25 amino acids at th N-terminus. The open reading frame of th NTII11 transcript encodes a 19.4 kDa protein with four putative transmembrane domains. Northern blot analyses revealed a tissue-specific expression was confirmed by in situ hybridization, and cellular localization of plasmolipin mRNA was demonstrated in Schwann cells of the sciatic nerve and in glial cells of myelinated brain structures. The steady-state levels of plasmolipin mRNA were markedly altered (i) during development of sciatic nerve and brain. (ii) after sciatic nerve injury, and (ii) in cured Schwann cells maintained under different conditions of cell growth and arrest. Our data indicate a function of plasmolipin during myelination in the central as well as in the peripheral nervous system.

Organ perfusion by dynamic scintigraphy convection-diffusion tracer kinetics in a phantom

Dynamic scintigraphy is used widely to evaluate qualitatively the perfusion of an organ. Attempts to quantify blood flow to an organ by means of scintigraphic imaging modalities have often employed assumptions that lead to oversimplifying the physiology of the tracer kinetics. We used a mathematical formalism described by W. Perl and F. P. Chinard (Circ. Res. 22: 273-298, 1968), the convection-diffusion tracer kinetics, model, for parameter evaluation of flow (F) and volume of distribution (V). This modeling methodology was evaluated using a circulatory phantom with absolute flow measured independently by flowmeter. In a series of 22 phantom experiments with F/V < 0.32 s-1, there was a strong correlation between F and flow probe measurement [r = 0.97; slope = 1.08 +/- 0.06 (SE)]. The theoretical analysis comparing this approach with classical tracer kinetics methods explains both the satisfactory results for F/V using mean transit time and the systematic overestimation of F/V using decay constant methods.

The Simultaneous Measurement of Glomerular Filtration Rate (Gfr) and Renal Plasma Flow (Rpf) following Renal Transplantation by use of Functional Imaging

A new method for evaluating renal function using dynamic scintigraphy and deconvolution is described; functional images can be created from the data to quantitate kidney function. Our data are indicating that GFR measurements obtained by this method do not differ from those obtained by classical renal clearance methods. As was expected measurements of renal plasma flow exceed the values of PAH clearance. Additional studies to determine extraction ratios must be done along with direct flow meter measurements.

The simultaneous measurement of glomerular filtration rate (GFR) and renal plasma flow (RPF) following renal transplantation by use of functional imaging

A new method for evaluating renal function using dynamic scintigraphy and deconvolution is described; functional images can be created from the data to quantitate kidney function. Our data are indicating that GFR measurements obtained by this method do not differ from those obtained by classical renal clearance methods. As was expected measurements of renal plasma flow exceed the values of PAH clearance. Additional studies to determine extraction ratios must be done along with direct flow meter measurements.

Purification and properties of boar acrosin

An isolation procedure in the presence of non-ionic detergents has been developed for the large-scale preparation of boar acrosin. Five steps including hydrophobic interaction chromatography on phenyl-Sepharose resulted in a 161-fold purification of the enzyme with an accumulation yield of 41%. The resultant acrosin preparation had a molecular weight of 38,000, an isoelectric point of 10.5 and a specific activity of 37 U/mg. Apparent homogeneity was judged by sodium dodecyl sulfate electrophoresis and isoelectric focusing. A polarity index of 41.2% was calculated from the amino acid composition. Acrosin was stable at pH 5.5 in the presence of 0.1% Triton X-100. In the absence of detergent acrosin was strongly adsorbed on plastic surfaces.

Kinetics of the interaction of alpha-chymotrypsin with trypsin kallikrein inhibitor (Kunitz) in which the reactive-site peptide bond Lys-15--Ala-16 is split

Modified trypsin kallikrein inhibitor (I*), with the reactive-site peptide bond Lys-15--Ala-16 split, reacts with alpha-chymotrypsin (E) via an intermediate X to the stable tetrahedral complex C:E + I in equilibrium X leads to C. Formation X constitutes a fast pre-equilibrium (equilibrium constant Kx = 7 X 10(-5) M, association rate constant kx = 4 X 10(3)M-1s-1) to the slow reaction X leads to C (rate constant kc = 2 X 10(-3) s-1), all values at pH 7.5. No intermediate X is observed when alpha-chymotrypsin reacts with I*-OMe in which the carboxyl group of Lys-15 is esterified by methanol. This observation as well as the different pH dependence of the overall association rate constants in the case of I* and I*-OMe indicate tha formation of X precedes formation of the acyl enzyme in the catalytic pathway. The data are compared to the similar results obtained with beta-trypsin and I* or I*-OMe.