Vaccination generates functional progenitor tumor-specific CD8 T cells and long-term tumor control

Background

Immune checkpoint blockade (ICB) therapies are an important treatment for patients with advanced cancers; however only a subset of patients with certain types of cancer achieves durable remissions. Cancer vaccines are an attractive strategy to boost patient immune responses, but less is known about whether and how immunization can induce long-term tumor immune reprogramming and arrest cancer progression. We developed a clinically-relevant genetic cancer mouse model in which hepatocytes sporadically undergo oncogenic transformation. We compared how tumor-specific CD8 T cells (TST) differentiate in mice with early sporadic lesions as compared to late lesions and tested how immunotherapeutic strategies, including vaccination and ICB, reprogram TST and impact liver cancer progression.

Methods

Mice with a germline floxed allele of the SV40 large T antigen (TAG) undergo spontaneous recombination and activation of the TAG oncogene, leading to rare early pre-cancerous lesions that inevitably progress to established liver cancer. We assessed the immunophenotype and function of TAG-specific CD8 T cells in mice with early and late liver lesions. We vaccinated mice, either alone or in combination with ICB, to test whether these immunotherapeutic interventions could stop liver cancer progression.

Results

In mice with early lesions, a subset of TST were PD1 + TCF1 + TOX - and could produce IFNγ, while TST present in mice with late liver cancers were PD1 + TCF1 lo/- TOX + and unable to make effector cytokines. Strikingly, vaccination with attenuated TAG epitope-expressing Listeria monocytogenes (LM TAG ) blocked liver cancer development and led to a population of TST that were TCF1 + TOX - TST and polyfunctional cytokine producers. In contrast, ICB administration did not slow cancer progression or improve LM TAG vaccine efficacy.

Conclusion

Vaccination, but not ICB, generated a population of progenitor TST and halted cancer progression in a clinically relevant model of sporadic liver cancer. In patients with early cancers or at high-risk of cancer recurrence, immunization may be the most effective strategy.

What is already known on this topic

Immunotherapy, including immune checkpoint blockade and cancer vaccines, fails to induce long-term remissions in most patients with cancer.

What this study adds

Hosts with early lesions but not hosts with advanced cancer retain a progenitor TCF1+ TST population. This population can be reprogrammed and therapeutically exploited by vaccination, but not ICB, to block tumor progression.

How this study might affect research practice or policy

For people at high-risk of cancer progression, vaccination administered when a responsive progenitor TST population is present may be the optimal immunotherapy to induce long-lasting progression-free survival.

Claudin-2 protects against colitis-associated cancer by promoting colitis-associated mucosal healing

Patients with inflammatory bowel disease (IBD) are susceptible to colitis-associated cancer (CAC). Chronic inflammation promotes the risk for CAC. In contrast, mucosal healing predicts improved prognosis in IBD and reduced risk of CAC. However, the molecular integration among colitis, mucosal healing, and CAC remains poorly understood. Claudin-2 (CLDN2) expression is upregulated in IBD; however, its role in CAC is not known. The current study was undertaken to examine the role for CLDN2 in CAC. The AOM/DSS-induced CAC model was used with WT and CLDN2-modified mice. High-throughput expression analyses, murine models of colitis/recovery, chronic colitis, ex vivo crypt culture, and pharmacological manipulations were employed in order to increase our mechanistic understanding. The Cldn2KO mice showed significant inhibition of CAC despite severe colitis compared with WT littermates. Cldn2 loss also resulted in impaired recovery from colitis and increased injury when mice were subjected to intestinal injury by other methods. Mechanistic studies demonstrated a possibly novel role of CLDN2 in promotion of mucosal healing downstream of EGFR signaling and by regulation of Survivin expression. An upregulated CLDN2 expression protected from CAC and associated positively with crypt regeneration and Survivin expression in patients with IBD. We demonstrate a potentially novel role of CLDN2 in promotion of mucosal healing in patients with IBD and thus regulation of vulnerability to colitis severity and CAC, which can be exploited for improved clinical management.

Deletion of Endogenous Neuregulin-4 Limits Adaptive Immunity During Interleukin-10 Receptor-Neutralizing Colitis

BACKGROUND

Growth factors are essential for maintenance of intestinal health. We previously showed that exogenous neuregulin-4 (NRG4) promotes colonocyte survival during cytokine challenge and is protective against acute models of intestinal inflammation. However, the function(s) of endogenous NRG4 are not well understood. Using NRG4-/- mice, we tested the role of endogenous NRG4 in models of colitis skewed toward either adaptive (interleukin-10 receptor [IL-10R] neutralization) or innate (dextran sulfate sodium [DSS]) immune responses.

METHODS

NRG4-/- and wild-type cage mate mice were subjected to chronic IL-10R neutralization colitis and acute DSS colitis. Disease was assessed by histological examination, inflammatory cytokine levels, fecal lipocalin-2 levels, and single cell mass cytometry immune cell profiling. Homeostatic gene alterations were evaluated by RNA sequencing analysis from colonic homogenates, with real-time quantitative polymerase chain reaction confirmation in both tissue and isolated epithelium.

RESULTS

During IL-10R neutralization colitis, NRG4-/- mice had reduced colonic inflammatory cytokine expression, histological damage, and colonic CD8+ T cell numbers vs wild-type cage mates. Conversely, in DSS colitis, NRG4-/- mice had elevated cytokine expression, fecal lipocalin-2 levels, and impaired weight recovery. RNA sequencing showed a loss of St3gal4, a sialyltransferase involved in immune cell trafficking, in NRG4-null colons, which was verified in both tissue and isolated epithelium. The regulation of St3gal4 by NRG4 was confirmed with ex vivo epithelial colon organoid cultures from NRG4-/- mice and by induction of St3gal4 in vivo following NRG4 treatment.

CONCLUSIONS

NRG4 regulates colonic epithelial ST3GAL4 and thus may allow for robust recruitment of CD8+ T cells during adaptive immune responses in colitis. On the other hand, NRG4 loss exacerbates injury driven by innate immune responses.

The Cooperative Human Tissue Network of the National Cancer Institute: Supporting Cancer Research for 35 Years

The Cooperative Human Tissue Network was created by the NCI in 1987 to support a coordinated national effort to collect and distribute high quality, pathologist-validated human tissues for cancer research. Since then, the network has expanded to provide different types of tissue samples, blood and body fluid samples, immunohistologic and molecular sample preparations, tissue microarrays, and clinical datasets inclusive of biomarkers and molecular testing. From inception through the end of 2021, the network has distributed 1,375,041 biospecimens. It served 889 active investigators in 2021. The network has also taken steps to begin to optimize the representation of diverse communities among the distributed biospecimens. In this article, the authors review the 35-year history of this network, describe changes to the program over the last 15 years, and provide operational and scientific highlights from each of the divisions. Readers will learn how to engage with the network and about the continued evolution of the program for the future.

Racial/Ethnic and Sex Differences in Somatic Cancer Gene Mutations among Patients with Early-Onset Colorectal Cancer

Molecular features underlying colorectal cancer disparities remain uncharacterized. Here, we investigated somatic mutation patterns by race/ethnicity and sex among 5,856 non-Hispanic white (NHW), 535 non-Hispanic Black (NHB), and 512 Asian/Pacific Islander (API) patients with colorectal cancer (2,016 early-onset colorectal cancer patients: sequencing age <50 years). NHB patients with early-onset nonhypermutated colorectal cancer, but not API patients, had higher adjusted tumor mutation rates than NHW patients. There were significant differences for LRP1B, FLT4, FBXW7, RNF43, ATRX, APC, and PIK3CA mutation frequencies in early-onset nonhypermutated colorectal cancers between racial/ethnic groups. Heterogeneities by race/ethnicity were observed for the effect of APC, FLT4, and FAT1 between early-onset and late-onset nonhypermutated colorectal cancer. By sex, heterogeneity was observed for the effect of EP300, BRAF, WRN, KRAS, AXIN2, and SMAD2. Males and females with nonhypermutated colorectal cancer had different trends in EP300 mutations by age group. These findings define genomic patterns of early-onset nonhypermutated colorectal cancer by race/ethnicity and sex, which yields novel biological clues into early-onset colorectal cancer disparities.

SIGNIFICANCE

NHBs, but not APIs, with early-onset nonhypermutated colorectal cancer had higher adjusted tumor mutation rates versus NHWs. Differences for FLT4, FBXW7, RNF43, LRP1B, APC, PIK3CA, and ATRX mutation rates between racial/ethnic groups and EP300, KRAS, AXIN2, WRN, BRAF, and LRP1B mutation rates by sex were observed in tumors of young patients. See related commentary by Shen et al., p. 530 . This article is highlighted in the In This Issue feature, p. 517.

Predicting Crohn's disease severity in the colon using mixed cell nucleus density from pseudo labels

Crohn's disease (CD) is a debilitating inflammatory bowel disease with no known cure. Computational analysis of hematoxylin and eosin (H&E) stained colon biopsy whole slide images (WSIs) from CD patients provides the opportunity to discover unknown and complex relationships between tissue cellular features and disease severity. While there have been works using cell nuclei-derived features for predicting slide-level traits, this has not been performed on CD H&E WSIs for classifying normal tissue from CD patients vs active CD and assessing slide label-predictive performance while using both separate and combined information from pseudo-segmentation labels of nuclei from neutrophils, eosinophils, epithelial cells, lymphocytes, plasma cells, and connective cells. We used 413 WSIs of CD patient biopsies and calculated normalized histograms of nucleus density for the six cell classes for each WSI. We used a support vector machine to classify the truncated singular value decomposition representations of the normalized histograms as normal or active CD with four-fold cross-validation in rounds where nucleus types were first compared individually, the best was selected, and further types were added each round. We found that neutrophils were the most predictive individual nucleus type, with an AUC of 0.92 ± 0.0003 on the withheld test set. Adding information improved cross-validation performance for the first two rounds and on the withheld test set for the first three rounds, though performance metrics did not increase substantially beyond when neutrophils were used alone.

Inherited Cancer Susceptibility Gene Sequence Variations Among Patients With Appendix Cancer

Importance

Germline sequence variations in APC, BMPR1A, CDH1, CHEK2, EPCAM, MLH1, MSH2, MSH6, MUTYH, PMS2, PTEN, SMAD4, STK11, and TP53 genes are associated with susceptibility to gastrointestinal cancers. As a rare cancer, the evaluation of appendiceal cancer (AC) predisposition has been limited.

Objective

To assess the prevalence and spectrum of inherited cancer susceptibility gene sequence variations in patients with AC and the utility of germline genetic testing for this population.

Design, Setting, and Participants

This cohort study included patients with AC who underwent germline genetic testing of 14 cancer susceptibility genes performed by a clinical testing laboratory between March 1, 2012, and December 31, 2016. Data were analyzed from March to August 2022. Clinical, individual, and family histories were obtained from clinician-completed test requisition forms. Multigene panel testing was performed by targeted custom capture and sequencing and chromosome rearrangement analysis.

Main Outcomes and Measures

The main outcomes were germline sequence variation prevalence and spectrum in patients with AC.

Results

Among the 131 patients with AC in the cohort (90 female [68.7%]), a total of 16 deleterious sequence variations were identified in 15 patients (11.5%). Similarly, when limited to the 74 patients with AC as the first and only primary tumor, a total of 8 patients (10.8%) had at least 1 deleterious sequence variation in a cancer susceptibility gene. Overall, 6 patients (4.6%) had a deleterious sequence variation observed in MUTYH (5 with monoallelic MUTYH and 1 with biallelic MUTYH). All 4 patients with Lynch syndrome (3.1%) had a sequence variation in the MLH1 gene, of whom 3 were aged 50 years or older at AC diagnosis. Five patients (3.8%) had deleterious sequence variations in other cancer predisposition genes (1 with APC [c.3920T>A, p.I1307K], 2 with CHEK2 [c.470T>C, p.I157T], 1 with SMAD4 [c.263 287dup, p.L98IFS*14], and 1 with TP53 [c.524G>A, p.R175H]).

Conclusions and Relevance

In this cohort study, 1 in every 10 patients with AC who underwent testing for hereditary cancer predisposition carried an inherited gene sequence variation associated with cancer susceptibility. Given the high frequency and broad spectrum of germline gene sequence variations, these data suggest that genetic evaluation might be warranted for all patients diagnosed with this rare malignant tumor. A systemic sequencing effort for all patients with AC may also identify cancer vulnerabilities to exploit for therapeutic development in a cancer type for which clinical trials are limited.

AXL Promotes Metformin-Induced Apoptosis Through Mediation of Autophagy by Activating ROS-AMPK-ULK1 Signaling in Human Esophageal Adenocarcinoma

AXL receptor tyrosine kinase promotes an invasive phenotype and chemotherapy resistance in esophageal adenocarcinoma (EAC). AXL has been implicated in the regulation of autophagy, but the underlying molecular mechanism remains poorly understood. Herein, we investigate the mechanistic role of AXL in autophagy as well as metformin-induced effects on the growth and survival of EAC. We demonstrate that AXL mediates autophagic flux through activation of AMPK-ULK1 signaling in a reactive oxygen species (ROS)-dependent mechanism by glucose starvation. AXL positively regulates basal cellular ROS levels without significantly affecting mitochondrial ROS production in EAC cells. Pharmacological inhibition of cellular ROS using Trolox abrogates glucose starvation-induced AMPK signaling and autophagy. We demonstrate that AXL expression is required for metformin-induced apoptosis in EAC cells in vitro. The apoptosis induction by metformin is markedly attenuated by inhibition of autophagy through genetic silencing of Beclin1 or ATG7 autophagy mediators, thereby confirming the requirement of intact autophagy for enhancing metformin-induced apoptosis in EAC cells. Our data indicate that metformin-induced autophagy displays a pro-apoptotic function in EAC cells. We show that the metformin-induced suppression of tumor growth in vivo is highly dependent on AXL expression in a tumor xenograft mouse model of EAC. We demonstrate that AXL promotes metformin-induced apoptosis through activation of autophagy in EAC. AXL may be a valuable biomarker to identify tumors that are sensitive to metformin. Therefore, AXL expression could inform the selection of patients for future clinical trials to evaluate the therapeutic efficacy of metformin in EAC.

MTG16 (CBFA2T3) regulates colonic epithelial differentiation, colitis, and tumorigenesis by repressing E protein transcription factors

Aberrant epithelial differentiation and regeneration contribute to colon pathologies including inflammatory bowel disease (IBD) and colitis-associated cancer (CAC). MTG16 (CBFA2T3) is a transcriptional corepressor expressed in the colonic epithelium. MTG16 deficiency in mice exacerbates colitis and increases tumor burden in CAC, though the underlying mechanisms remain unclear. Here, we identified MTG16 as a central mediator of epithelial differentiation, promoting goblet and restraining enteroendocrine cell development in homeostasis and enabling regeneration following dextran sulfate sodium (DSS)-induced colitis. Transcriptomic analyses implicated increased E box-binding transcription factor (E protein) activity in MTG16-deficient colon crypts. Using a novel mouse model with a point mutation that attenuates MTG16:E protein interactions (Mtg16P209T), we established that MTG16 exerts control over colonic epithelial differentiation and regeneration by repressing E protein-mediated transcription. Mimicking murine colitis, MTG16 expression was increased in biopsies from patients with active IBD compared to unaffected controls. Finally, uncoupling MTG16:E protein interactions partially phenocopied the enhanced tumorigenicity of Mtg16-/- colon in the azoxymethane(AOM)/DSS-induced model of CAC, indicating that MTG16 protects from tumorigenesis through additional mechanisms. Collectively, our results demonstrate that MTG16, via its repression of E protein targets, is a key regulator of cell fate decisions during colon homeostasis, colitis, and cancer.

A cross-platform informatics system for the Gut Cell Atlas: integrating clinical, anatomical and histological data

The Gut Cell Atlas (GCA), an initiative funded by the Helmsley Charitable Trust, seeks to create a reference platform to understand the human gut, with a specific focus on Crohn's disease. Although a primary focus of the GCA is on focusing on single-cell profiling, we seek to provide a framework to integrate other analyses on multi-modality data such as electronic health record data, radiological images, and histology tissues/images. Herein, we use the research electronic data capture (REDCap) system as the central tool for a secure web application that supports protected health information (PHI) restricted access. Our innovations focus on addressing the challenges with tracking all specimens and biopsies, validating manual data entry at scale, and sharing organizational data across the group. We present a scalable, cross-platform barcode printing/record system that integrates with REDCap. The central informatics infrastructure to support our design is a tuple table to track longitudinal data entry and sample tracking. The current data collection (by December 2020) is illustrated with types and formats of the data that the system collects. We estimate that one terabyte is needed for data storage per patient study. Our proposed data sharing informatics system addresses the challenges with integrating physical sample tracking, large files, and manual data entry with REDCap.

Histologic and Racial/Ethnic Patterns of Appendiceal Cancer among Young Patients

BACKGROUND

Appendiceal cancer incidence among individuals age < 50 years (early-onset appendiceal cancer) is rising with unknown etiologies. Distinct clinicopathologic/demographic features of early-onset appendiceal cancer remain unexplored. We compared patterns of appendiceal cancer among individuals by age of disease-onset.

METHODS

Using the NIH/NCI's Surveillance, Epidemiology, and End Results program data, we identified individuals age 20+ years diagnosed with appendiceal cancer from 2007 to 2016. Cochran-Armitage trend tests and multinomial logistic regression models were used to examine age-related differences in clinicopathologic/demographic features of appendiceal cancer.

RESULTS

We identified 8,851 patients with appendiceal cancer during the 10-year study period. Histologic subtype, tumor grade, stage, sex and race/ethnicity all significantly differed by age of appendiceal cancer diagnosis. After adjustment for race/ethnicity, sex, stage, insurance status, and tumor grade, young patients were 82% more likely to be Hispanic [OR, 1.82; 95% confidence interval (CI), 1.48-2.25; P < 0.001] and 4-fold more likely to be American Indian or Alaska Native (OR, 4.02; 95% CI, 1.77-9.16; P = 0.0009) compared with late-onset cases. Patients with early-onset appendiceal cancer were also 2- to 3.5-fold more likely to be diagnosed with neuroendocrine tumors of the appendix (goblet cell carcinoid: OR, 1.96; 95% CI, 1.59-2.41; P < 0.0001; carcinoid: OR, 3.52; 95% CI, 2.80-4.42; P < 0.0001) compared with patients with late-onset appendiceal cancer. Among patients with neuroendocrine tumors, early-onset cases were also 45% to 61% less likely to present with high-grade (III-IV) tumors.

CONCLUSIONS

Approximately one in every three patients with appendiceal cancer is diagnosed before age 50 years in the United States. Appendiceal cancer in young patients is classified by distinct histologic and demographic features.

IMPACT

Early-onset appendiceal cancer determinants can inform discovery of risk factors and molecular biomarkers of appendiceal cancer in young patients, with implications for appendiceal cancer prevention, detection, and treatment.

Linking bacterial enterotoxins and alpha defensin 5 expansion in the Crohn's colitis: A new insight into the etiopathogenetic and differentiation triggers driving colonic inflammatory bowel disease

Evidence link bacterial enterotoxins to apparent crypt-cell like cells (CCLCs), and Alpha Defensin 5 (DEFA5) expansion in the colonic mucosa of Crohn's colitis disease (CC) patients. These areas of ectopic ileal metaplasia, positive for Paneth cell (PC) markers are consistent with diagnosis of CC. Retrospectively, we: 1. Identified 21 patients with indeterminate colitis (IC) between 2000-2007 and were reevaluation their final clinical diagnosis in 2014 after a followed-up for mean 8.7±3.7 (range, 4-14) years. Their initial biopsies were analyzed by DEFA5 bioassay. 2. Differentiated ulcer-associated cell lineage (UACL) analysis by immunohistochemistry (IHC) of the CC patients, stained for Mucin 6 (MUC6) and DEFA5. 3. Treated human immortalized colonic epithelial cells (NCM460) and colonoids with pure DEFA5 on the secretion of signatures after 24hr. The control colonoids were not treated. 4. Treated colonoids with/without enterotoxins for 14 days and the spent medium were collected and determined by quantitative expression of DEFA5, CCLCs and other biologic signatures. The experiments were repeated twice. Three statistical methods were used: (i) Univariate analysis; (ii) LASSO; and (iii) Elastic net. DEFA5 bioassay discriminated CC and ulcerative colitis (UC) in a cohort of IC patients with accuracy. A fit logistic model with group CC and UC as the outcome and the DEFA5 as independent variable differentiator with a positive predictive value of 96 percent. IHC staining of CC for MUC6 and DEFA5 stained in different locations indicating that DEFA5 is not co-expressed in UACL and is therefore NOT the genesis of CC, rather a secretagogue for specific signature(s) that underlie the distinct crypt pathobiology of CC. Notably, we observed expansion of signatures after DEFA5 treatment on NCM460 and colonoids cells expressed at different times, intervals, and intensity. These factors are key stem cell niche regulators leading to DEFA5 secreting CCLCs differentiation 'the colonic ectopy ileal metaplasia formation' conspicuously of pathogenic importance in CC.

Idiopathic Myointimal Hyperplasia of the Mesenteric Veins: A Rare Imitator of Inflammatory Bowel Disease

Idiopathic myointimal hyperplasia of the mesenteric veins (IMHMV) is a rare cause of chronic colonic ischemia characterized by intimal smooth muscle proliferation and luminal narrowing of the small to medium sized mesenteric veins. It predominantly affects the rectosigmoid colon in otherwise healthy, middle-aged males. Definitive diagnosis and treatment are surgical; however, patients are frequently misdiagnosed, which often results in a protracted clinical course. We describe a case of IMHMV presenting as left hemicolitis in a 53-year-old male, as well as the endoscopic, histopathologic, and radiographic findings that established the diagnosis.

Co-overexpression of AXL and c-ABL predicts a poor prognosis in esophageal adenocarcinoma and promotes cancer cell survival

Background: Esophageal adenocarcinoma (EAC) is highly aggressive and characterized by poor prognosis. AXL expression has been linked to Barrett's tumorigenesis and resistance to chemotherapy, which is associated with c-ABL intracellular localization. However, the molecular and functional relationship between AXL and c-ABL and the clinical significance of the co-expression of these proteins in EAC remain unclear.

Methods: We used immunohistochemical analysis (IHC) on tissue microarrays containing human EAC samples (n=53) and normal esophageal tissues (n=11) in combination with corresponding deidentified clinicopathological information to evaluate the expression and the prognostic significance of AXL and c-ABL in EAC. The data were statistically analyzed using Kruskal-Wallis, the chi-square, the Fisher's exact, and Pearson tests. The Kaplan-Meier method and Cox proportional hazards regression model were used to evaluate cancer patient survival. We used a serum deprivation EAC cell model to investigate the pro-survival function of AXL and c-ABL using cell viability, apoptosis, and lactate dehydrogenase activity assays. We performed in vitro assays, including Western blotting, quantitative real-time PCR, and translational chromatin immunoprecipitation (TrIP-Chip) to study the molecular relationship between AXL and c-ABL in EAC cells.

Results: IHC analysis revealed that AXL and c-ABL were overexpressed in 55% and 66% of EAC samples, respectively, as compared to normal tissues. Co-overexpression of the two proteins was observed in 49% of EAC samples. The chi-square test indicated a significant association between AXL and c-ABL expression in the EAC samples (χ² = 6.873, p = 0.032), and the expression of these proteins was significantly associated with EAC patient age (p < 0.001), tumor stage (p < 0.01), and lymph node status (p < 0.001). AXL and c-ABL protein expression data analysis exhibited an identical clinicopathological association profile. Additionally, we found a significant association between expression of AXL (χ² = 16.7, p = 0.002) or c-ABL (χ² = 13.4, p = 0.001) and survival of EAC patients. The Cox proportional hazards model and log rank test predicted a significant increase in mortality of patients with high expression of AXL [hazard ratio (HR): 2.86, 95% confidence interval (CI): 1.53 - 5.34, p = 0.003] or c-ABL [HR: 3.29, 95% CI: 1.35 - 8.03, p = 0.001] as compared to those patients with low expression of AXL or c-ABL proteins. Molecular investigations indicated that AXL positively regulates c-ABL protein expression through increased cap-dependent protein translation involving phosphorylation of EIF4E in EAC cells. Next, we investigated the functional relationship between AXL and c-ABL in EAC cells. We demonstrated that the pro-survival activity of AXL requires c-ABL expression in response to serum deprivation.

Conclusion: This study highlights the importance of the co-overexpression of AXL and c-ABL proteins as a valuable prognostic biomarker and targeting these proteins could be an effective therapeutic approach in EAC or other solid tumors expressing high levels of AXL and c-ABL proteins.

Small Molecule Inhibitor Screen Reveals Calcium Channel Signaling as a Mechanistic Mediator of Clostridium difficile TcdB-Induced Necrosis

Clostridioides difficile is the leading cause of nosocomial diarrhea in the United States. The primary virulence factors are two homologous glucosyltransferase toxins, TcdA and TcdB, that inactivate host Rho-family GTPases. The glucosyltransferase activity has been linked to a "cytopathic" disruption of the actin cytoskeleton and contributes to the disruption of tight junctions and the production of pro-inflammatory cytokines. TcdB is also a potent cytotoxin that causes epithelium necrotic damage through an NADPH oxidase (NOX)-dependent mechanism. We conducted a small molecule screen to identify compounds that confer protection against TcdB-induced necrosis. We identified an enrichment of "hit compounds" with a dihydropyridine (DHP) core which led to the discovery of a key early stage calcium signal that serves as a mechanistic link between TcdB-induced NOX activation and reactive oxygen species (ROS) production. Disruption of TcdB-induced calcium signaling (with both DHP and non-DHP molecules) is sufficient to ablate ROS production and prevent subsequent necrosis in cells and in a mouse model of intoxication.

Blood vessel epicardial substance reduces LRP6 receptor and cytoplasmic β-catenin levels to modulate Wnt signaling and intestinal homeostasis

Blood vessel epicardial substance (BVES, otherwise known as POPDC1) is an integral membrane protein known to regulate tight junction formation and epithelial-mesenchymal transition. BVES is underexpressed in a number of malignancies, including colorectal cancer. BVES loss leads to activation of the Wnt pathway, suggesting that decreased BVES expression functionally contributes to tumorigenesis. However, the mechanism by which BVES modulates Wnt signaling is unknown. Here, we confirm that BVES loss increases β-catenin protein levels, leads to Wnt pathway activation in a ligand-independent fashion and coordinates with Wnt ligand to further increase Wnt signaling. We show that BVES loss increases levels and activation of the Wnt co-receptor, LRP6, in cell lines, murine adenoma tumoroids and human-derived colonoids. We also demonstrate that BVES interacts with LRP6. Finally, murine tumor modeling using a Wnt-driven genetic model and a chemically induced model of colorectal carcinogenesis demonstrate that BVES loss increases tumor multiplicity and dysplasia. Together, these results implicate BVES as an inhibitor of Wnt signaling, provide one of the first examples of a tight junction-associated protein regulating Wnt receptor levels, and expand the number of putative molecular targets for therapeutic intervention in colorectal cancer.

Abstract 3126: A novel biomarker signature in predicting chemoresistance in colorectal cancer: Potential application in chemotherapy

Despite advances in the cytotoxic and targeted therapy, resistance to chemotherapy remains one of the greatest challenges in long-term management of metastatic colorectal cancer, which eventually contributes to patient death as tumors accumulate means of evading treatment. We have recently demonstrated that expression of the tight junction protein claudin-1 increases while claudin-7 expression decreases with human colon cancer (CRC) progression and metastasis. Epithelial-mesenchymal transition (EMT) and cancer stem cells (CSC) are critically implicated in cancer metastasis and chemoresistance. Taking this to account, we performed a computational assessment of 250 patient datasets from two different cancer centers (Vanderbilt and Moffitt) and identified the gene sets whose expression increased proportionally with claudin-1 expression and decreased with claudin-7, and vice versa, and correlated these gene sets it with chemoresistance, EMT and CSC markers. We identified a resulting 23-gene set biomarker signature, out of these gene clusters. Some of the important candidates based on literature and their function in colorectal cancer which we focused on were SLC6A6, PIK3CA, ASAP1, TMEM and E2F2. This signature was then validated using the TCGA database. To further evaluate functional relevance of this biomarker signature, we developed oxaliplatin resistant DLD-1 and HT29 colon cancer cells. The chemoresistance of these cells were confirmed by determining the IC50 values DLD (Parental) (4.5μM) and HT29 (Parental) (10.08 μM), after exposing them to increasing conc. of clinically relevant dose of oxaliplatin DLD (Oxaliplatin-R) (16.35 μM) and HT29 (Oxaliplatin-R) (20.05 μM). To our interest, we observed a significant upregulation of SLC6A6, PIK3CA, ASAP1, TMEM and downregulation of E2F2 in DLDOxaR and HT29OxaR cells compared to parental cells. Moreover, DLDOxaR and HT29OxaR cells possessed significantly increased expression of EMT markers such as α-SMA, vimentin, Snail and Slug along with enrichment of the stem cell markers like CD133, CD44 and Aldh1, colony and sphere forming ability. A concomitant decrease in E-cadherin characterized these cells. A similar increase in the expressions of SLC6A6, PIK3CA, ASAP1, TMEM and decrease in E2F2 was observed in colon cancer mouse models as well as chemoresistant patient samples. Taken together, we propose a new predictive biomarker signature which may offer insights into identifying new therapies required to overcome the acquired resistance of colon cancer towards Oxaliplatin and uncover potential molecular pathways involved in treatment failure to help guide therapeutic alternative.

Citation Format: Saiprasad Gowrikumar, Kristina Pravoverov, Caroline Selisteda, Kiran D. Bastola, Steven Chen, Joshua J. Smith, Mary K. Washington, Amar B. Singh, Punita Dhawan. A novel biomarker signature in predicting chemoresistance in colorectal cancer: Potential application in chemotherapy [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2019; 2019 Mar 29-Apr 3; Atlanta, GA. Philadelphia (PA): AACR; Cancer Res 2019;79(13 Suppl):Abstract nr 3126.

High dietary salt-induced dendritic cell activation underlies microbial dysbiosis-associated hypertension

Excess dietary salt contributes to inflammation and hypertension via poorly understood mechanisms. Antigen presenting cells including dendritic cells (DCs) play a key role in regulating intestinal immune homeostasis in part by surveying the gut epithelial surface for pathogens. Previously, we found that highly reactive γ-ketoaldehydes or isolevuglandins (IsoLGs) accumulate in DCs and act as neoantigens, promoting an autoimmune-like state and hypertension. We hypothesized that excess dietary salt alters the gut microbiome leading to hypertension and this is associated with increased immunogenic IsoLG-adduct formation in myeloid antigen presenting cells. To test this hypothesis, we performed fecal microbiome analysis and measured blood pressure of healthy human volunteers with salt intake above or below the American Heart Association recommendations. We also performed 16S rRNA analysis on cecal samples of mice fed normal or high salt diets. In humans and mice, high salt intake was associated with changes in the gut microbiome reflecting an increase in Firmicutes, Proteobacteria and genus Prevotella bacteria. These alterations were associated with higher blood pressure in humans and predisposed mice to vascular inflammation and hypertension in response to a sub-pressor dose of angiotensin II. Mice fed a high salt diet exhibited increased intestinal inflammation including the mesenteric arterial arcade and aorta, with a marked increase in the B7 ligand CD86 and formation of IsoLG-protein adducts in CD11c+ myeloid cells. Adoptive transfer of fecal material from conventionally housed high salt-fed mice to germ-free mice predisposed them to increased intestinal inflammation and hypertension. These findings provide novel insight into the mechanisms underlying inflammation and hypertension associated with excess dietary salt and may lead to interventions targeting the microbiome to prevent and treat this important disease.

Upregulated claudin-1 expression promotes colitis-associated cancer by promoting β-catenin phosphorylation and activation in Notch/p-AKT-dependent manner

In IBD patients, integration between a hyper-activated immune system and epithelial cell plasticity underlies colon cancer development. However, molecular regulation of such a circuity remains undefined. Claudin-1(Cld-1), a tight-junction integral protein deregulation alters colonic epithelial cell (CEC) differentiation, and promotes colitis severity while impairing colitis-associated injury/repair. Tumorigenesis is a product of an unregulated wound healing process and therefore we postulated that upregulated Cld-1 levels render IBD patients susceptible to the colitis-associated cancer (CAC). Villin Cld-1 mice is used to carryout overexpressed studies in mice. The role of deregulated Cld-1 expression in CAC and underlying mechanism using a well-constructed study scheme and mouse models of DSS colitis/recovery and CAC. Using an inclusive investigative scheme, we here report that upregulated Cld-1 expression promotes susceptibility to the CAC and its malignancy. Increased mucosal inflammation, defective epithelial homeostasis accompanied the increased CAC in Villin-Cld1-Tg mice. We further found significantly increased levels of pro-tumorigenic M2 macrophages and β-CateninSer552 (β-CatSer552) expression in the CAC in Cld-1Tg versus WT mice. Mechanistic studies identified the role of PI3K/Akt signaling in Cld-1 dependent activation of the β-CatSer552, which, in turn, was dependent on pro-inflammatory signals. Our studies identify a critical role of Cld-1 in promoting susceptibility to CAC. Importantly, these effects of deregulated Cld-1 were not associated with altered tight junction integrity, but on its non-canonical role in regulating Notch/PI3K/Wnt/ β-CatSer552 signaling. Overall, outcome from our current studies identifies Cld-1 as potential prognostic biomarker for IBD severity and CAC, and a novel therapeutic target.

Nonsteroidal Anti-inflammatory Drugs Alter the Microbiota and Exacerbate Clostridium difficile Colitis while Dysregulating the Inflammatory Response

Clostridium difficile infection (CDI) is a major public health threat worldwide. The use of nonsteroidal anti-inflammatory drugs (NSAIDs) is associated with enhanced susceptibility to and severity of CDI; however, the mechanisms driving this phenomenon have not been elucidated. NSAIDs alter prostaglandin (PG) metabolism by inhibiting cyclooxygenase (COX) enzymes. Here, we found that treatment with the NSAID indomethacin prior to infection altered the microbiota and dramatically increased mortality and the intestinal pathology associated with CDI in mice. We demonstrated that in C. difficile-infected animals, indomethacin treatment led to PG deregulation, an altered proinflammatory transcriptional and protein profile, and perturbed epithelial cell junctions. These effects were paralleled by increased recruitment of intestinal neutrophils and CD4⁺ cells and also by a perturbation of the gut microbiota. Together, these data implicate NSAIDs in the disruption of protective COX-mediated PG production during CDI, resulting in altered epithelial integrity and associated immune responses.IMPORTANCEClostridium difficile infection (CDI) is a spore-forming anaerobic bacterium and leading cause of antibiotic-associated colitis. Epidemiological data suggest that use of nonsteroidal anti-inflammatory drugs (NSAIDs) increases the risk for CDI in humans, a potentially important observation given the widespread use of NSAIDs. Prior studies in rodent models of CDI found that NSAID exposure following infection increases the severity of CDI, but mechanisms to explain this are lacking. Here we present new data from a mouse model of antibiotic-associated CDI suggesting that brief NSAID exposure prior to CDI increases the severity of the infectious colitis. These data shed new light on potential mechanisms linking NSAID use to worsened CDI, including drug-induced disturbances to the gut microbiome and colonic epithelial integrity. Studies were limited to a single NSAID (indomethacin), so future studies are needed to assess the generalizability of our findings and to establish a direct link to the human condition.

Abstract 4082: Contrasting role for claudin-2 in colitis-associated cancer (CAC) and spontaneous colon tumorigenesis (CRC) by regulating mucosal healing

A link between chronic inflammation and colon cancer has long been appreciated. Accordingly, patients with ulcerative colitis are at higher risk for developing colitis-associated cancer (CAC). Mucosal barrier dysregulation allies with inflammation and colon cancer. Accordingly, claudin-2, a tight junction protein, is upregulated in ulcerative colitis, CAC and spontaneous colon cancer (CRC). Remarkably, claudin-2 expression is restricted to the colon crypt base, among undifferentiated and proliferative colonocytes, and its increased expression is responsible for the regulation of paracellular permeability, differentiation and proliferation. However, causal role of claudin-2 in CAC and CRC remains unclear. Considering the recent data from our laboratory and of others, that in vivo genetic manipulation of claudin-2 has inverse effects on colitis, we hypothesized an adaptive role for increased claudin-2 expression in colitis by promoting mucosal healing. We further postulated that mucosal healing can manifest in contrasting phenotypes for the CAC and CRC. To examine, Villin-claudin-2 transgenic (Cldn-2) mice were subjected to CAC by exposing them to AOM/DSS-induced cancer or interbred with the APCmin mice, the mouse model of spontaneous intestinal cancer. It was intriguing that the inflammation-driven colon cancer (AOM/DSS induced colon cancer) was significantly suppressed in Cldn-2 mice compared to WT littermates (p&lt;0.001). These mice also showed immune suppressive milieu ideal for spontaneous colon tumorigenesis. Accordingly, we found contrasting disparity in results from APCmin/Cldn-2 mice, generated by the cross between Cldn-2 and APCmin mice. These mice showed significant increase in intestinal tumor burden (248+40%, p&lt;0.001) and colonic tumor burden [Incidence (172.50±18%, p&lt;0.001) and size (521.5±34%, p&lt;0.001)] compared to APCmin mice. H&E analysis confirmed aggressive phenotype of APCmin-Cldn-2 mice tumors (vs APCmin mice tumors). APCmin/Cldn-2 mice also survived less than the APCmin mice. Further, inflammation induction by subjecting these mice to Dextran Sodium Sulfate (DSS) resulted in precocious colonic tumorigenesis only in APCmin mice, rejecting a role for the pro-inflammatory signaling in colon cancer progression in APCmin/Cldn-2 mice. High throughput transcriptome and oncogenic array analyses further suggested modifications of the key inflammatory and oncogenic signaling, in supporting these disparate phenotypes. Taken together, our data provide strong support for the key significance for the context and diverse immunogenic signaling in regulating CAC versus CRC. These studies also suggest that claudin-2 manipulated mice can provide the much needed mouse modelling to help identify key immunogenic signaling supportive of the colon tumorigenesis for therapeutic gains.

Citation Format: Rizwan Ahmad, Balawant Kumar, Narendra Kumar, Mary K. Washington, Punita Dhawan, Amar B. Singh. Contrasting role for claudin-2 in colitis-associated cancer (CAC) and spontaneous colon tumorigenesis (CRC) by regulating mucosal healing [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2018; 2018 Apr 14-18; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2018;78(13 Suppl):Abstract nr 4082.

Abstract 3094: Effects of aryl hydrocarbon receptor and estrogen receptor beta crosstalk on benzo(a)pyrene induced AhR target genes

Colorectal cancer (CRC) is the third most common diagnosed cancer and the third leading cause of cancer-related deaths in the United States. Epidemiological evidence show estrogen might influence the incidence of CRC in women by acting in a protective role via estrogen receptor beta (ERβ) but the mechanism of action is not known. Benzo(a)pyrene [B(a)P], a member of the polycyclic aromatic hydrocarbon (PAH) family of compounds is a well-characterized environmental toxicant that has been proven to be a major contributor to the development of sporadic colon cancer. Literature provides evidence of crosstalk between Aryl Hydrocarbon Receptor (AhR), a receptor for B(a)P, and estrogen receptors (ERs) which negatively affect ER-mediated transcription. This study aims to elucidate the effect of AhR/ERB crosstalk on B(a)P-induced expression of AHR target genes in adult Polyposis In the Rat Colon (PIRC) model. We hypothesize that estrogen inhibits B(a)P-induced expression of AHR target genes and attenuates the formation of colon polyps in female PIRC rats. Groups of female and male PIRC rats (n = 8) received sub-chronic exposure to 25, 50 and 100 µg B(a)P/kg body wt. via oral gavage for 60 days. Female PIRC rats that received 25, 50 and 100 µg B(a)P/kg body wt. showed significant decrease in total polyp count when compared to males with respective treatments. Polyp sizes of female PIRC rats receiving 25, 50 and 100 µg B(a)P/kg body wt. were increased when compared to males respectively. Histopathological analysis of colon polyps revealed that female animals exhibited low-grade to no dysplasia while high-grade dysplasia was recorded in male animals treated with corresponding doses. As expected B(a)P increased expression of Cytochrome P450 isoform 1A1 (CYP1A1), CYP1B1, Sulfotransferase Family 1A Member 1 (SULT1A1), and Glutathione S-transferases (GST) in the colon of PIRC rats. Female PIRC rats show increase in CYP1B1, SULT1A1 and GST when compared to males in various treatment groups. It is possible that the increase in Phase II enzymes may provide clearance of B(a)P, preventing polyp development in female PIRC rats. In future studies, by measuring the expression of other phase 1 and phase 2 drug metabolizing enzymes (DME), along with measuring circulating estrogen levels, analyzing [B(a)P] metabolite profile, and probing B(a)P-DNA interactions, we will provide insight into how estrogen protects females from developing colon cancer. This research was funded by NIH grants 5RO1CA142845-04, 5R25GM059994-3, and G12MD007586-29.

Citation Format: Kenneth J. Harris, Kelly L. Harris, Mary K. Washington, James Amos-Landgraf, Aramandla Ramesh. Effects of aryl hydrocarbon receptor and estrogen receptor beta crosstalk on benzo(a)pyrene induced AhR target genes [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2018; 2018 Apr 14-18; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2018;78(13 Suppl):Abstract nr 3094.

Western diet enhances benzo(a)pyrene-induced colon tumorigenesis in a polyposis in rat coli (PIRC) rat model of colon cancer

Consumption of Western diet (WD), contaminated with environmental toxicants, has been implicated as one of the risk factors for sporadic colon cancer. Our earlier studies using a mouse model revealed that compared to unsaturated dietary fat, the saturated dietary fat exacerbated the development of colon tumors caused by B(a)P. The objective of this study was to study how WD potentiates B(a)P-induced colon carcinogenesis in the adult male rats that carry a mutation in the Apc locus - the polyposis in the rat colon (PIRC) rats. Groups of PIRC rats were fed with AIN-76A standard diet (RD) or Western diet (WD) and received 25, 50, or 100 μg B(a)P/kg body weight (wt) via oral gavage for 60 days. Subsequent to exposure, rats were euthanized; colons were retrieved and preserved in 10% formalin for counting the polyp numbers, measuring the polyp size, and histological analyses. Blood samples were collected and concentrations of cholesterol, triglycerides, glucose, insulin and leptin were measured. Rats that received WD + B(a)P showed increased levels of cholesterol, triglycerides, and leptin in comparison to RD + B(a)P groups or controls. The colon tumor numbers showed a B(a)P dose-response relationship. Adenomas with high grade dysplasia were prominent in B(a)P + WD rats compared to B(a)P + RD rats and controls (p < 0.05). The larger rat model system used in this study allows for studying more advanced tumor phenotypes over a longer duration and delineating the role of diet - toxicant interactions in sporadic colon tumor development.

Correction: Human alpha defensin 5 is a candidate biomarker to delineate inflammatory bowel disease

[This corrects the article DOI: 10.1371/journal.pone.0179710.].

p120-Catenin is an obligate haploinsufficient tumor suppressor in intestinal neoplasia

p120-Catenin (p120) functions as a tumor suppressor in intestinal cancer, but the mechanism is unclear. Here, using conditional p120 knockout in Apc-sensitized mouse models of intestinal cancer, we have identified p120 as an "obligatory" haploinsufficient tumor suppressor. Whereas monoallelic loss of p120 was associated with a significant increase in tumor multiplicity, loss of both alleles was never observed in tumors from these mice. Moreover, forced ablation of the second allele did not further enhance tumorigenesis, but instead induced synthetic lethality in combination with Apc loss of heterozygosity. In tumor-derived organoid cultures, elimination of both p120 alleles resulted in caspase-3-dependent apoptosis that was blocked by inhibition of Rho kinase (ROCK). With ROCK inhibition, however, p120-ablated organoids exhibited a branching phenotype and a substantial increase in cell proliferation. Access to data from Sleeping Beauty mutagenesis screens afforded an opportunity to directly assess the tumorigenic impact of p120 haploinsufficiency relative to other candidate drivers. Remarkably, p120 ranked third among the 919 drivers identified. Cofactors α-catenin and epithelial cadherin (E-cadherin) were also among the highest scoring candidates, indicating a mechanism at the level of the intact complex that may play an important role at very early stages of of intestinal tumorigenesis while simultaneously restricting outright loss via synthetic lethality.

Loss of claudin-3 expression induces IL6/gp130/Stat3 signaling to promote colon cancer malignancy by hyperactivating Wnt/β-catenin signaling

The Hyperactivated Wnt/β-catenin signaling acts as a switch to induce EMT and promote colorectal cancer. However, due to its essential role in gut homeostasis, therapeutic targeting of this pathway has proven challenging. Additionally, IL-6/Stat-3 signaling, activated by microbial translocation through the dysregulated mucosal barrier in colon adenomas, facilitates the adenoma to adenocarcinomas transition. However, inter-dependence between these signaling pathways and key mucosal barrier components in regulating colon tumorigenesis and cancer progression remains unclear. In current study, we have discovered, using a comprehensive investigative regimen, a novel and tissue specific role of claudin-3, a tight junction integral protein, in inhibiting colon cancer progression by serving as the common rheostat of Stat-3 and Wnt-signaling activation. Loss of claudin-3 also predicted poor patient survival. These findings however contrasted an upregulated claudin-3 expression in other cancer types and implicated role of the epigenetic regulation. Claudin-3−/− mice revealed dedifferentiated and leaky colonic epithelium, and developed invasive adenocarcinoma when subjected to colon cancer. Wnt-signaling hyperactivation, albeit in GSK-3β independent manner, differentiated colon cancer in claudin-3−/− mice versus WT-mice. Claudin-3 loss also upregulated the gp130/IL6/Stat3 signaling in colonic epithelium potentially assisted by infiltrating immune components. Genetic and pharmacological studies confirmed that claudin-3 loss induces Wnt/β-catenin activation, which is further exacerbated by Stat-3-activation and help promote colon cancer. Overall, these novel findings identify claudin-3 as a therapeutic target for inhibiting overactivation of Wnt-signaling to prevent CRC malignancy.

Abstract 5013: A 3D culture system identifies a new mode of cetuximab resistance and disease-relevant genes in colorectal cancer

We previously reported that single cells from a human colorectal cancer (CRC) cell line (HCA-7) formed either hollow single-layered polarized cysts or solid spiky masses when plated within type-I collagen in 3D. To begin in-depth analyses into whether clonal cysts and spiky masses possessed divergent malignant properties, individual colonies of each morphology were isolated and expanded. The lines thus derived faithfully retained the parental cystic and spiky morphologies and were termed CC (cystic) and SC (spiky), respectively. Although both CC and SC expressed EGF receptor (EGFR), cetuximab strongly inhibited growth of CC, whereas SC was resistant to growth inhibition and this was coupled to increased tyrosine phosphorylation of MET and RON. Addition of the dual MET/RON tyrosine kinase inhibitor, crizotinib, to cetuximab in SC restored cetuximab sensitivity. To characterize genome-wide divergence between CC and SC, we performed comprehensive genomic and transcriptomic analysis of CC and SC in 3D. One of the most upregulated genes in CC was the tumor suppressor 15-PGDH/HPGD and the most upregulated gene in SC was versican (VCAN) in 3D and xenografts. Analysis of a human CRC tissue microarray showed that epithelial, but not stromal, VCAN staining strongly correlated with reduced survival, and combined epithelial VCAN and absent HPGD staining portended a poorer prognosis. Thus, with this 3D system, we have identified a new mode of cetuximab resistance and a potential prognostic marker in CRC. As such, this represents a potentially powerful system to identify additional therapeutic sensitivities and disease-relevant genes for CRC.

Citation Format: Bhuminder Singh, Cunxi Li, Ramona Graves-Deal, Haiting Ma, Alina Starchenko, William H. Fry, Yuanyuan Lu, Yang Wang, Galina Bogatcheva, Mohseen P. Khan, Ginger L. Milne, Shilin Zhao, Gregory D. Ayers, Nenggan Li, Mary K. Washington, Timothy J. Yeatman, Oliver G. McDonald, Qi Liu, Robert J. Coffey. A 3D culture system identifies a new mode of cetuximab resistance and disease-relevant genes in colorectal cancer [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2017; 2017 Apr 1-5; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2017;77(13 Suppl):Abstract nr 5013. doi:10.1158/1538-7445.AM2017-5013

Abstract 4804: Sex-specific differences in Benzo(a)Pyrene [B(a)P]-induced colon carcinogenesis

Colorectal cancer (CRC) is the third most common diagnosed cancer and the third leading cause of cancer-related deaths in the United States. It has also been reported that colon cancer incidence and mortality rates are higher in men than woman, but there is yet a determined mechanistic link to show the factors that underlie the sex-specific differences in CRC initiation and progression. Benzo(a)pyrene [B(a)P], a member of the polycyclic aromatic hydrocarbon (PAH) family of compounds is a well-characterized environmental toxicant that has been proven to be a major contributor to the development of sporadic colon cancer. Published studies indicate that Aryl Hydrocarbon Receptor (AhR), a receptor for [B(a)P], bind to estrogen receptor (ER) and negatively affect AhR-target gene transcription. This study aims to elucidate the sex-specific differences in B(a)P-induced colon cancer in adult Polyposis In the Rat Colon (PIRC) model. We hypothesize that sex-specific differences in B(a)P biotransformation modulates the formation of colon tumors in PIRC rats. Groups of female and male PIRC rats (n = 8) received sub-chronic exposure to 25, 50 and 100 µg B(a)P/kg body wt. via oral gavage for 60 days. Female and male rats that received no [B(a)P] treatment served as controls. [B(a)P] was shown to have no significant effect on body weight of these rats and female PIRC rats that received 25, 50 and 100 µg B(a)P/kg body wt. showed significant decrease in total polyp count when compared to males with respective treatments. Polyp sizes of female PIRC rats receiving 25, 50 and 100 µg B(a)P/kg body wt. were increased when compared to males respectively. Histopathological analysis of colon polyps revealed that female animals exhibited low-grade to no dysplasia while high-grade dysplasia was recorded in male animals treated with corresponding doses. Phase 1 enzyme, Cytochrome P450 isoform 1A1 (CYP1A1), and phase 2 enzyme, Sulfotransferase Family 1A Member 1 (SULT1A1), were downregulated in colon tissue of female PIRC rats receiving 25, 50 and 100 µg B(a)P/kg body wt. when compared to male counterparts. In future studies, by measuring the expression of other phase 1 and phase 2 drug metabolizing enzymes (DME), along with measuring circulating estrogen levels, analyzing [B(a)P] metabolite profile, and probing B(a)P-DNA interactions, we will provide insight into if and how estrogen receptor protects females from developing colon cancer. This research was funded by NIH grants 5RO1CA142845-04, 5R25GM059994-3, and G12MD007586-29.

Citation Format: Kenneth J. Harris, Kelly L. Harris, Mary K. Washington, James Amos-Landgraf, Aramandla Ramesh. Sex-specific differences in Benzo(a)Pyrene [B(a)P]-induced colon carcinogenesis [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2017; 2017 Apr 1-5; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2017;77(13 Suppl):Abstract nr 4804. doi:10.1158/1538-7445.AM2017-4804

BVES regulates c-Myc stability via PP2A and suppresses colitis-induced tumourigenesis

OBJECTIVE

Blood vessel epicardial substance (BVES) is a tight junction-associated protein that regulates epithelial-mesenchymal states and is underexpressed in epithelial malignancy. However, the functional impact of BVES loss on tumourigenesis is unknown. Here we define the in vivo role of BVES in colitis-associated cancer (CAC), its cellular function and its relevance to patients with IBD.

DESIGN

We determined BVES promoter methylation status using an Infinium HumanMethylation450 array screen of patients with UC with and without CAC. We also measured BVES mRNA levels in a tissue microarray consisting of normal colons and CAC samples. Bves^-/- and wild-type mice (controls) were administered azoxymethane (AOM) and dextran sodium sulfate (DSS) to induce tumour formation. Last, we used a yeast two-hybrid screen to identify BVES interactors and performed mechanistic studies in multiple cell lines to define how BVES reduces c-Myc levels.

RESULTS

BVES mRNA was reduced in tumours from patients with CAC via promoter hypermethylation. Importantly, BVES promoter hypermethylation was concurrently present in distant non-malignant-appearing mucosa. As seen in human patients, Bves was underexpressed in experimental inflammatory carcinogenesis, and Bves^-/- mice had increased tumour multiplicity and degree of dysplasia after AOM/DSS administration. Molecular analysis of Bves^-/- tumours revealed Wnt activation and increased c-Myc levels. Mechanistically, we identified a new signalling pathway whereby BVES interacts with PR61α, a protein phosphatase 2A regulatory subunit, to mediate c-Myc destruction.

CONCLUSION

Loss of BVES promotes inflammatory tumourigenesis through dysregulation of Wnt signalling and the oncogene c-Myc. BVES promoter methylation status may serve as a CAC biomarker.

EGFR-mediated macrophage activation promotes colitis-associated tumorigenesis

Epidermal growth factor receptor (EGFR) signaling is a known mediator of colorectal carcinogenesis. Studies have focused on the role of EGFR signaling in epithelial cells, although the exact nature of the role of EGFR in colorectal carcinogenesis remains a topic of debate. Here, we present evidence that EGFR signaling in myeloid cells, specifically macrophages, is critical for colon tumorigenesis in the AOM-DSS model of colitis-associated carcinogenesis (CAC). In a human tissue microarray, colonic macrophages demonstrated robust EGFR activation in the pre-cancerous stages of colitis and dysplasia. Utilizing the AOM-DSS model, mice with a myeloid-specific deletion of Egfr had significantly decreased tumor multiplicity and burden, protection from high-grade dysplasia, and significantly reduced colitis. Intriguingly, mice with gastrointestinal epithelial cell-specific Egfr deletion demonstrated no differences in tumorigenesis in the AOM-DSS model. The alterations in tumorigenesis in myeloid-specific Egfr knockout mice were accompanied by decreased macrophage, neutrophil, and T cell infiltration. Pro-tumorigenic M2 macrophage activation was diminished in myeloid-specific Egfr-deficient mice, as marked by decreased Arg1 and Il10 mRNA expression and decreased IL-4, IL-10 and IL-13 protein levels. Surprisingly, diminished M1 macrophage activation was also detectable, as marked by significantly reduced Nos2 and Il1b mRNA levels and decreased IFN-γ, TNF-α, and IL-1β protein levels. The alterations in M1 and M2 macrophage activation were confirmed in bone marrow-derived macrophages from mice with the myeloid-specific Egfr knockout. The combined effect of restrained M1 and M2 macrophage activation resulted in decreased production of pro-angiogenic factors, CXCL1 and VEGF, and reduced CD31⁺ blood vessels, which likely contributed to protection from tumorigenesis. These data reveal that EGFR signaling in macrophages, but not in colonic epithelial cells, has a significant role in CAC. EGFR signaling in macrophages may prove to be an effective biomarker of CAC or target for chemoprevention in patients with inflammatory bowel disease.

Abstract A16: Smad4 pathways modulate induction of the chemokine Ccl20 and repress inflammation-induced carcinogenesis in mouse colon

Inflammation regulates many aspects of gut homeostasis but is also a key component of colon cancer progression. While TGFβ signaling is known to regulate inflammatory responses within immune cells, we have uncovered a novel regulatory pathway in which TGFβ and BMP signaling suppress responses to inflammatory stimuli within the colonic epithelium. Using mice with conditional deletion of Smad4 in intestinal epithelium, we found that CCL20 expression was increased with Smad4 loss. Similarly, in murine immortalized colonocytes and human colon cancer cell lines, blocking TGFβ and/or BMP receptors increased CCL20 expression. CCL20 is upregulated in response to inflammatory signals such as TNF and IL-1β. CCL20 is also upregulated in colon cancer but the mechanism is not understood. We found that pre-treatment of colonocytes or colon cancer cells with TGFβ1 and BMP2 completely suppressed TNF- or IL-1β-induced CCL20 expression at the level of gene transcription. By chromatin immunoprecipitation, we found that TGFβ1/BMP2 treatment impaired binding of NFκB and phospho-STAT3 to the CCL20 promoter. To understand the significance of this regulation in chronic inflammation, we subjected Smad4 deleted and control mice to three rounds of dextran sodium sulfate (DSS)-mediated damage to the distal colon. We found that loss of Smad4 in mouse colonic epithelium was sufficient to induce tumorigenesis following damage-induced inflammation. Following DSS-mediated damage, Smad4-null epithelium developed invasive colorectal adenocarcinoma within two months of DSS treatment while Smad4+ control mice never develop tumors following DSS exposure. The Smad4 null tumors were histologically similar to those of human colitis-associated colon cancers. Prior to tumor formation, we saw an increase in CD8+ cells in Smad4-deleted colons, suggesting that tumor progression involves bidirectional crosstalk between the epithelium and immune cells and that this crosstalk is regulated in part by Smad4-mediated signaling within the epithelium. SMAD4, TGFβ receptors, or BMP receptors are often mutated in colon cancer. This loss of TGFβ and/or BMP signaling likely facilitates epithelial-immune cell crosstalk in colitis-associated colon cancers.

Citation Format: Anna L. Means, Tanner J. Freeman, Connie J. Weaver, Chanjuan Shi, Mary K. Washington, Bronson C. Wessinger, Tasia Brown, David K. Flaherty, Kevin P. Weller, Robert J. Coffey, Keith T. Wilson, Robert D. Beauchamp. Smad4 pathways modulate induction of the chemokine Ccl20 and repress inflammation-induced carcinogenesis in mouse colon. [abstract]. In: Proceedings of the AACR Special Conference on Colorectal Cancer: From Initiation to Outcomes; 2016 Sep 17-20; Tampa, FL. Philadelphia (PA): AACR; Cancer Res 2017;77(3 Suppl):Abstract nr A16.

Abstract B29: Reorganization of signaling modules revealed in human colorectal cancer using single-cell mass cytometry

Cellular heterogeneity poses a significant challenge to understanding tissue level phenotypes, and confounds conventional bulk analyses. To facilitate the analysis of signaling at the single-cell level in human tissues, we, for the first time, applied mass cytometry using CyTOF (Cytometry Time-of-Flight) to formalin-fixed paraffin-embedded (FFPE) normal and diseased intestinal specimens. We developed and validated FFPE-DISSECT (Disaggregation for Intracellular Signaling in Single Epithelial Cells from Tissue), a single-cell approach for preserving and characterizing native signaling states from embedded solid tissue samples. We applied FFPE-DISSECT coupled to mass cytometry to demonstrate differential TNF-α signaling in intestinal enterocytes, goblet cells and enteroendocrine cells, implicating the role of the RAS-RAF-MEK-ERK signaling pathway in goblet cell identity. In addition, application of FFPE-DISSECT, mass cytometry, and data-driven computational analyses of human colorectal cancer specimens confirmed reduction of differentiation and revealed quantitative changes in inter- and intra-tumoral heterogeneity with regards to the modular regulation of signaling pathways. Our single-cell approach, applied in conjunction with genomic annotation such as microsatellite and K-Ras and B-RAF status, allows rapid and detailed characterization of cellular heterogeneity from clinical repositories of embedded human tissues.

Citation Format: Alan J. Simmons, Cherie R. Scurrah, Eliot T. McKinley, Charles A. Herring, Jonathan M. Irish, Mary K. Washington, Robert J. Coffey, Ken S. Lau. Reorganization of signaling modules revealed in human colorectal cancer using single-cell mass cytometry. [abstract]. In: Proceedings of the AACR Special Conference on Colorectal Cancer: From Initiation to Outcomes; 2016 Sep 17-20; Tampa, FL. Philadelphia (PA): AACR; Cancer Res 2017;77(3 Suppl):Abstract nr B29.

Human alpha defensin 5 is a candidate biomarker to delineate inflammatory bowel disease

Inability to distinguish Crohn's colitis from ulcerative colitis leads to the diagnosis of indeterminate colitis. This greatly effects medical and surgical care of the patient because treatments for the two diseases vary. Approximately 30 percent of inflammatory bowel disease patients cannot be accurately diagnosed, increasing their risk of inappropriate treatment. We sought to determine whether transcriptomic patterns could be used to develop diagnostic biomarker(s) to delineate inflammatory bowel disease more accurately. Four patients groups were assessed via whole-transcriptome microarray, qPCR, Western blot, and immunohistochemistry for differential expression of Human α-Defensin-5. In addition, immunohistochemistry for Paneth cells and Lysozyme, a Paneth cell marker, was also performed. Aberrant expression of Human α-Defensin-5 levels using transcript, Western blot, and immunohistochemistry staining levels was significantly upregulated in Crohn's colitis, p< 0.0001. Among patients with indeterminate colitis, Human α-Defensin-5 is a reliable differentiator with a positive predictive value of 96 percent. We also observed abundant ectopic crypt Paneth cells in all colectomy tissue samples of Crohn's colitis patients. In a retrospective study, we show that Human α-Defensin-5 could be used in indeterminate colitis patients to determine if they have either ulcerative colitis (low levels of Human α-Defensin-5) or Crohn's colitis (high levels of Human α-Defensin-5). Twenty of 67 patients (30 percent) who underwent restorative proctocolectomy for definitive ulcerative colitis were clinically changed to de novo Crohn's disease. These patients were profiled by Human α-Defensin-5 immunohistochemistry. All patients tested strongly positive. In addition, we observed by both hematoxylin and eosin and Lysozyme staining, a large number of ectopic Paneth cells in the colonic crypt of Crohn's colitis patient samples. Our experiments are the first to show that Human α-Defensin-5 is a potential candidate biomarker to molecularly differentiate Crohn's colitis from ulcerative colitis, to our knowledge. These data give us both a potential diagnostic marker in Human α-Defensin-5 and insight to develop future mechanistic studies to better understand crypt biology in Crohn's colitis.

Abstract B19: Kras mutation imparts neoplastic potential on duct cells but not acinar cells in a mouse model of obstructive chronic pancreatitis

Understanding the progression of human pancreatic cancer is difficult due to the late stage of diagnosis of this deadly disease. We must therefore rely upon robust model systems to understand how pancreatic cancer arises, how its acute and chronic phases of progression are regulated, and how best to identify and treat it, hopefully still in the early stage. Models of pancreatic ductal adenocarcinoma (PDAC) that accurately reflect human disease are still being developed. To mimic human disease, PDAC must arise from mutations occurring in adult animals and with etiologies relevant to humans. We developed a new mouse model that incorporates obstructive chronic pancreatitis with tissue-specific, adult-onset expression of mutant Kras. We found that KrasG12D expression in duct cells but not in acinar cells led to progression of metaplastic ducts to eventual dysplasia and cancer. In early-stage disease, Kras mutation in acinar cells led to increased acinar-to-ductal metaplasia but did not downregulate p53, thus leading to reduced cell survival. Ducts naturally express much lower p53 levels, however, and there was increased survival of KrasG12D-mediated, duct-derived metaplastic cells. Furthermore, acinar cells upregulated Pdx1 during acinar-to-ductal metaplasia while duct cells did not do so during their metaplastic transition. Without chronic pancreatitis, Kras mutation in acinar cells causes abundant Pancreatic Intraepithelial Neoplasm (PanIN)-like lesions. However, overexpression of Pdx1 in acinar cells in this context permitted acinar-to-ductal metaplasia but prevented PanIN-like lesion formation, suggesting that Pdx1 can repress neoplastic progression. In summary, in the setting of obstructive chronic pancreatitis, ducts are the principal source of cancer development via reduced Pdx1 and p53 levels and increased cell survival.

Citation Format: Fong C. Pan, Jessica N. Kim, Chanjuan Shi, Mary K. Washington, Maike Sander, Maureen Gannon, Robert D. Beauchamp, Christopher V. Wright, Anna L. Means.{Authors}. Kras mutation imparts neoplastic potential on duct cells but not acinar cells in a mouse model of obstructive chronic pancreatitis. [abstract]. In: Proceedings of the AACR Special Conference on Pancreatic Cancer: Advances in Science and Clinical Care; 2016 May 12-15; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2016;76(24 Suppl):Abstract nr B19.

Prevention of DNA damage in Barrett's esophageal cells exposed to acidic bile salts

Esophageal adenocarcinoma (EA) is one of the fastest rising tumors in the USA. The major risk factor for EA is gastroesophageal reflux disease (GERD). During GERD, esophageal cells are exposed to refluxate which contains gastric acid frequently mixed with duodenal bile. This may lead to mucosal injury and Barrett's metaplasia (BE) that are important factors contributing to development of EA. In this study, we investigated DNA damage in BE cells exposed to acidic bile salts and explored for potential protective strategies. Exposure of BE cells to acidic bile salts led to significant DNA damage, which in turn, was due to generation of reactive oxygen species (ROS). We found that acidic bile salts induce a rapid increase in superoxide radicals and hydrogen peroxide, which were determined using electron paramagnetic resonance spectroscopy and Amplex Red assay. Analyzing a panel of natural antioxidants, we identified apocynin to be the most effective in protecting esophageal cells from DNA damage induced by acidic bile salts. Mechanistic analyses showed that apocynin inhibited ROS generation and increases the DNA repair capacity of BE cells. We identified BRCA1 and p73 proteins as apocynin targets. Downregulation of p73 inhibited the protective effect of apocynin. Taken together, our results suggest potential application of natural compounds such as apocynin for prevention of reflux-induced DNA damage and GERD-associated tumorigenesis.

Abstract 4919: Evaluating the gene expression of frozen tissue-derived prognostic signatures in FFPE colorectal cancer samples

OBJECTIVE: Defining molecular features that can predict the recurrence of colorectal cancer (CRC) for stage II and stage III patients remains a challenging problem in cancer research. Most available clinical samples are Formalin Fixed and Paraffin Embedded (FFPE). Nanostring nCounter® and Affymetrix GeneChip® Human Transcriptome Array 2.0 (HTA) are the two platforms marketed for high throughput measurement of mRNA expression from FFPE tissue samples. In this study, to identify an optimal platform for the gene expression profiling of FFPE CRC samples, we compared the expression of genes that make up published frozen tissue-derived prognostic signatures measured by these two platforms. METHODS: FFPE primary tumor tissue blocks were identified from 500 patients with stage II or III CRC and complete pathological information. We removed samples with neoadjuvant therapy, inadequate clinical follow-up or tumor specimens, samples with failure of RNA extraction and highly degraded samples. We identified 194 eligible FFPE-derived CRC primary tumors with a 7.4-year mean follow up. To measure the gene expression of the 194 samples, we designed a custom nCounter codeset using 536 gene elements from multiple published frozen tissue-derived prognostic signatures for CRC. We also performed gene expression profiling using the HTA platform on a subset of 84 of the 194 samples. For the nCounter data, samples with low total average count or with more than 20% genes having lower average count than the synthetic negative control genes were omitted to ensure adequate data quality. RESULTS: In total, for CRC samples from 42 patients, the gene expression data of 516 common genes measured by both platforms were of sufficient quality for comparative analysis. Based on HTA platform-derived data, we found that (1) 36 and 97 of the 516 common genes are significantly associated with overall survival (OS) and disease-free survival (DFS) at the single gene level (FDR &lt; 0.05), respectively; and (2) two of the nine reported multi-gene signatures, for which sufficient information from the original papers enabled such evaluation, can divide patients into high-risk and low-risk groups with significantly different DFS (p ≤ 0.05). Based on nCounter platform-derived data, no individual gene was found to be significantly associated with survival at the single gene level (FDR &lt; 0.05), but one of the nine published multi-gene signatures can divide patients into two groups with significantly different OS (p ≤ 0.05). Our results also showed moderate correlations between paired FFPE samples measured by nCounter and HTA platforms (the median correlation coefficient is 0.52). CONCLUSION: Our data demonstrate that while both platforms may identify gene or gene set expression differences associated with survival outcomes, the HTA appears to provide a more robust gene expression analysis dataset when using genes selected from published gene signatures.

Citation Format: Jing Zhu, Natasha G. Deane, Keeli B. Lewis, Chandrasekhar Padmanabhan, Mary K. Washington, Kristen K. Ciombor, Cynthia Timmers, Richard M. Goldberg, R. Daniel Beauchamp, Xi Chen. Evaluating the gene expression of frozen tissue-derived prognostic signatures in FFPE colorectal cancer samples. [abstract]. In: Proceedings of the 107th Annual Meeting of the American Association for Cancer Research; 2016 Apr 16-20; New Orleans, LA. Philadelphia (PA): AACR; Cancer Res 2016;76(14 Suppl):Abstract nr 4919.

Myeloid translocation genes differentially regulate colorectal cancer programs

Myeloid translocation genes (MTGs), originally identified as chromosomal translocations in acute myelogenous leukemia, are transcriptional corepressors that regulate hematopoietic stem cell programs. Analysis of The Cancer Genome Atlas (TCGA) database revealed that MTGs were mutated in epithelial malignancy and suggested that loss of function might promote tumorigenesis. Genetic deletion of MTGR1 and MTG16 in the mouse has revealed unexpected and unique roles within the intestinal epithelium. Mtgr1^−/− mice have progressive depletion of all intestinal secretory cells, and Mtg16^−/− mice have a decrease in goblet cells. Furthermore, both Mtgr1^−/− and Mtg16^−/− mice have increased intestinal epithelial cell proliferation. We thus hypothesized that loss of MTGR1 or MTG16 would modify Apc^1638/+-dependent intestinal tumorigenesis. Mtgr1^−/− mice, but not Mtg16^−/− mice, had a 10-fold increase in tumor multiplicity. This was associated with more advanced dysplasia, including progression to invasive adenocarcinoma, and augmented intratumoral proliferation. Analysis of ChIP-seq datasets for MTGR1 and MTG16 targets indicated that MTGR1 can regulate Wnt and Notch signaling. In support of this, immunohistochemistry and gene expression analysis revealed that both Wnt and Notch signaling pathways were hyperactive in Mtgr1^−/− tumors. Furthermore, in human colorectal cancer (CRC) samples MTGR1 was downregulated at both the transcript and protein level. Overall our data indicates that MTGR1 has a context dependent effect on intestinal tumorigenesis.

Human Islets Have Fewer Blood Vessels than Mouse Islets and the Density of Islet Vascular Structures Is Increased in Type 2 Diabetes

Human and rodent islets differ substantially in several features, including architecture, cell composition, gene expression and some aspects of insulin secretion. Mouse pancreatic islets are highly vascularized with interactions between islet endothelial and endocrine cells being important for islet cell differentiation and function. To determine whether human islets have a similar high degree of vascularization and whether this is altered with diabetes, we examined the vascularization of islets from normal human subjects, subjects with type 2 diabetes (T2D), and normal mice. Using an integrated morphometry approach to quantify intra-islet capillary density in human and mouse pancreatic sections, we found that human islets have five-fold fewer vessels per islet area than mouse islets. Islets in pancreatic sections from T2D subjects showed capillary thickening, some capillary fragmentation and had increased vessel density as compared with non-diabetic controls. These changes in islet vasculature in T2D islets appeared to be associated with amyloid deposition, which was noted in islets from 8/9 T2D subjects (and occupied 14% ± 4% of islet area), especially around the intra-islet capillaries. The physiological implications of the differences in the angioarchitecture of mouse and human islets are not known. Islet vascular changes in T2D may exacerbate β cell/islet dysfunction and β cell loss.

Olive oil prevents benzo(a)pyrene [B(a)P]-induced colon carcinogenesis through altered B(a)P metabolism and decreased oxidative damage in Apc(Min) mouse model

Colon cancer ranks third in cancer-related mortalities in the United States. Many studies have investigated factors that contribute to colon cancer in which dietary and environmental factors have been shown to play an integral role in the etiology of this disease. Specifically, human dietary intake of environmental carcinogens such as polycyclic aromatic hydrocarbons has generated interest in looking at how it exerts its effects in gastrointestinal carcinogenesis. Therefore, the objective of this study was to investigate the preventative effects of olive oil on benzo(a)pyrene [B(a)P]-induced colon carcinogenesis in adult Apc(Min) mice. Mice were assigned to a control (n=8) or treatment group (n=8) consisting of 25, 50 and 100-μg B(a)P/kg body weight (bw) dissolved in tricaprylin [B(a)P-only group] or olive oil daily via oral gavage for 60 days. Our studies showed that Apc(Min) mice exposed to B(a)P developed a significantly higher number (P<0.05) of larger dysplastic adenomas compared to those exposed to B(a)P + olive oil. Treatment of mice with B(a)P and olive oil significantly altered (P<0.05) the expression of drug-metabolizing enzymes in both the colon and liver tissues. However, only GST activity was significantly higher (P<0.05) in the liver of mice treated with 50- and 100-μg B(a)P/kg bw + olive oil. Lastly, olive oil promoted rapid detoxification of B(a)P by decreasing its organic metabolite concentrations and also decreasing the extent of DNA damage to colon and liver tissues (P<0.05). These results suggest that olive oil has a protective effect against B(a)P-induced colon tumors.

Implementation of an error-reporting module within a biorepository IT application to enhance operations

The Collaborative (formerly the Cooperative) Human Tissue Network (CHTN) is a federally funded service oriented grant that provides high-quality biospecimens and services to the research community. The CHTN consists of six institutions located throughout the United States to assist investigators in obtaining research specimens required for basic research. The CHTN divisions have similar operating goals: however, each division is responsible for maintaining operations at their local institutions. This requires the divisions to identify ways to maintain and sustain operations in a challenging federally funded environment, especially when the number of investigators requesting services drives the operation. Sustainability plans and goals are often times patched together out of necessity rather than taking a thoughtful approach by clearly defining and aligning activities with business strategy and priorities. The CHTN Western Division at Vanderbilt University Medical Center (CHTN-WD) has responded to this challenge of biospecimen resource sustainability in the face of diminished funding by continually identifying ways to innovate our processes through IT enhancements and requiring that the innovation produce measurable and relevant criteria for credibly reporting our operations progress and performance issues. With these overarching goals in mind, CHTN-WD underwent a Lean Six Sigma (LSS) series to identify operational inefficiencies that could be addressed with redesigning workflow and innovating the processes using IT solutions. The result of this internal collaborative innovation process was the implementation of an error-reporting module (ERM) hosted within our biorepository donor IT application, which allowed staff to report errors immediately; determine the operational area responsible; assess the severity of the error; determine course of action; determine if standard operating procedure (SOPs) revisions were required; and through automated e-mails, alert the area personnel responsible. The module provides a data-reporting feature by date range and area of operation for management and analysis.

Abstract 3421: Comparing gene expression of matched FFPE colorectal cancer samples measured by Nanostring nCounter® platform and Affymetrix GeneChip® Human Transcriptome Array platform

OBJECTIVE: Due to the lack of clinically annotated fresh frozen tumor samples, defining molecular features that can predict the recurrence of colorectal cancer (CRC) for stage II or stage III patients remains challenging in cancer research. Most available clinical samples are Formalin Fixed and Paraffin Embedded (FFPE). Nanostring nCounter® and Affymetrix GeneChip® Human Transcriptome Array (HTA) are two latest platforms that enable gene expression profiling of FFPE samples. In this study, we evaluated these two platforms for validating the prognostic gene expression signature based on FFPE-derived CRC samples.

METHODS: We designed a custom nCounter® codeset based on elements from multiple published prognostic gene signatures for CRC based on frozen tissues and used this platform to measure the gene expression of FFPE-derived CRC tissues passing strict quality control measures. Then, we measured the gene expression of 42 matched FFPE-derived samples on the HTA platform. Gene expression data for matched CRC samples measured by the two platforms were compared. Finally, we compared the previously published prognostic subtype assignments based on gene expression data measured by the two platforms.

RESULTS: In total, 42 pairs of matched CRC samples including 31 pairs of technical replicates and 11 pairs of biological replicates measured by both platforms passed the quality control. Our results showed moderate positive correlation of gene expression between matched samples measured by both platforms, which is not correlated with the RNA quality. When comparing the gene expression of patients with metastatic recurrence to that of patients with no recurrence over a 7.4-year mean follow up, we identified 5 differentially expressed genes (SYT17, LRIG1, PTPRJ, BSG, PTEN) in common (p &lt; 0.05) based on both platforms. Subtype analysis assigned Zhu et al.'s subtypes (Zhu, J. et al., PLOS One 2013) to 29 pairs of matched technical replicates measured by both platforms with posterior probability greater than 50%. Overall, we found that the gene expression patterns visualized in the HTA dataset were more consistent within defined subtypes as compared to those of the nCounter dataset and the HTA-based assignments are better supported by the corresponding survival estimates.

CONCLUSION: We found a moderate positive correlation between matched samples across both HTA and nCounter platforms, however the gene-by-gene correlations were weak. Both platforms support 5 potential biomarkers of poor prognosis. Discovery of CRC subtypes was more definitive using data from the HTA platform as compared to the nCounter® platform. Further comparisons of matched FFPE-derived CRC tissues across these platforms can lead to the discovery of additional prognostic biomarkers and increased confidence in the optimal platform for expanded clinical trial studies.

Citation Format: Jing Zhu, Natasha G. Deane, Keeli B. Lewis, Mary K. Washington, Xi Chen, Robert D. Beauchamp. Comparing gene expression of matched FFPE colorectal cancer samples measured by Nanostring nCounter® platform and Affymetrix GeneChip® Human Transcriptome Array platform. [abstract]. In: Proceedings of the 106th Annual Meeting of the American Association for Cancer Research; 2015 Apr 18-22; Philadelphia, PA. Philadelphia (PA): AACR; Cancer Res 2015;75(15 Suppl):Abstract nr 3421. doi:10.1158/1538-7445.AM2015-3421

Selenoprotein P influences colitis-induced tumorigenesis by mediating stemness and oxidative damage

Patients with inflammatory bowel disease are at increased risk for colon cancer due to augmented oxidative stress. These patients also have compromised antioxidant defenses as the result of nutritional deficiencies. The micronutrient selenium is essential for selenoprotein production and is transported from the liver to target tissues via selenoprotein P (SEPP1). Target tissues also produce SEPP1, which is thought to possess an endogenous antioxidant function. Here, we have shown that mice with Sepp1 haploinsufficiency or mutations that disrupt either the selenium transport or the enzymatic domain of SEPP1 exhibit increased colitis-associated carcinogenesis as the result of increased genomic instability and promotion of a protumorigenic microenvironment. Reduced SEPP1 function markedly increased M2-polarized macrophages, indicating a role for SEPP1 in macrophage polarization and immune function. Furthermore, compared with partial loss, complete loss of SEPP1 substantially reduced tumor burden, in part due to increased apoptosis. Using intestinal organoid cultures, we found that, compared with those from WT animals, Sepp1-null cultures display increased stem cell characteristics that are coupled with increased ROS production, DNA damage, proliferation, decreased cell survival, and modulation of WNT signaling in response to H2O2-mediated oxidative stress. Together, these data demonstrate that SEPP1 influences inflammatory tumorigenesis by affecting genomic stability, the inflammatory microenvironment, and epithelial stem cell functions.

The transcriptional corepressor MTGR1 regulates intestinal secretory lineage allocation

Notch signaling largely determines intestinal epithelial cell fate. High Notch activity drives progenitors toward absorptive enterocytes by repressing secretory differentiation programs, whereas low Notch permits secretory cell assignment. Myeloid translocation gene-related 1 (MTGR1) is a transcriptional corepressor in the myeloid translocation gene/Eight-Twenty-One family. Given that Mtgr1(-/-) mice have a dramatic reduction of intestinal epithelial secretory cells, we hypothesized that MTGR1 is a key repressor of Notch signaling. In support of this, transcriptome analysis of laser capture microdissected Mtgr1(-/-) intestinal crypts revealed Notch activation, and secretory markers Mucin2, Chromogranin A, and Growth factor-independent 1 (Gfi1) were down-regulated in Mtgr1(-/-) whole intestines and Mtgr1(-/-) enteroids. We demonstrate that MTGR1 is in a complex with Suppressor of Hairless Homolog, a key Notch effector, and represses Notch-induced Hairy/Enhancer of Split 1 activity. Moreover, pharmacologic Notch inhibition using a γ-secretase inhibitor (GSI) rescued the hyperproliferative baseline phenotype in the Mtgr1(-/-) intestine and increased production of goblet and enteroendocrine lineages in Mtgr1(-/-) mice. GSI increased Paneth cell production in wild-type mice but failed to do so in Mtgr1(-/-) mice. We determined that MTGR1 can interact with GFI1, a transcriptional corepressor required for Paneth cell differentiation, and repress GFI1 targets. Overall, the data suggest that MTGR1, a transcriptional corepressor well characterized in hematopoiesis, plays a critical role in intestinal lineage allocation.

Targeted colonic claudin-2 expression renders resistance to epithelial injury, induces immune suppression, and protects from colitis

Expression of claudin-2, a tight junction protein, is highly upregulated during inflammatory bowel disease (IBD) and, due to its association with epithelial permeability, has been postulated to promote inflammation. Notably, claudin-2 has also been implicated in the regulation of intestinal epithelial proliferation. However, precise role of claudin-2 in regulating colonic homeostasis remains unclear. Here, we demonstrate, using Villin-Claudin-2 transgenic mice, that increased colonic claudin-2 expression augments mucosal permeability as well as colon and crypt length. Most notably, despite leaky colon, Cl-2TG mice were significantly protected against experimental colitis. Importantly, claudin-2 expression increased colonocyte proliferation and provided protection against colitis-induced colonocyte death in a PI-3Kinase/Bcl-2-dependent manner. However, Cl-2TG mice also demonstrated marked suppression of colitis-induced increases in immune activation and associated signaling, suggesting immune tolerance. Accordingly, colons from naive Cl-2TG mice harbored significantly increased numbers of regulatory (CD4(+)Foxp3(+)) T cells than WT littermates. Furthermore, macrophages isolated from Cl-2TG mouse colon exhibited immune anergy. Importantly, these immunosuppressive changes were associated with increased synthesis of the immunoregulatory cytokine TGF-β by colonic epithelial cells in Cl-2TG mice compared with WT littermates. Taken together, our findings reveal a critical albeit complex role of claudin-2 in intestinal homeostasis by regulating epithelial permeability, inflammation and proliferation and suggest novel therapeutic opportunities.

Abstract 1589: Olive oil alters benzo(a)pyrene biotransformation and reduces oxidative DNA damage in colon of ApcMin mouse

Sporadic colon cancers have been shown to be triggered by diet and environmental factors. Epidemiological studies have shown that colon cancer rates were significantly reduced in Mediterranean countries where olive oil is the main ingredient of diet. Published works have shown that olive oil inhibits cell proliferation and promotes apoptosis in colorectal cancer cell lines. Studies conducted earlier in our laboratory have shown that dietary exposure to the environmental toxicant benzo(a)pyrene (BaP) leads to colon tumor formation. Benzo(a)pyrene biotransformation studies have shown that once BaP is metabolized by cytochrome P450 drug metabolizing enzymes, it forms metabolites such as BaP 7, 8-diol-epoxide (BPDE), BaP 3,6 & 6,12-diones. These metabolites have also been shown to cause double stranded breaks in DNA and cause oxidative damage. Therefore, we hypothesize that olive oil's interaction with BaP will modulate BaP metabolism and reduce colon tumor formation. In this study we investigated the effect of olive oil on BaP-induced colon carcinogenesis in male ApcMin mice. Mice were assigned to a control (n=7) or treatment group (n =7). Treatment consisted of 50 and 100 μg BaP/kg body weight dissolved in tricaprylin (BaP-only group) or olive oil administered daily via oral gavage for sixty days. Post exposure, mice were sacrificed; colon and liver tissues were retrieved from each group of mice and were preserved in formalin and pathological changes were evaluated. The tissues were further analyzed for the induction of drug metabolizing enzymes such as cytochrome 1A, cytochrome 1B1, and glutathione S-Transferase. Additionally, to determine if BaP caused oxidative DNA damage to tissues, genomic DNA was isolated from the respective tissues and we quantified aldehyde lesions. There was a reduced incidence of adenomas in colons of mice that ingested BaP + olive oil compared to mice that received BaP only (p &lt; 0.05). CYP protein expression was reduced while GST protein expression increased in the colon and liver tissues of BaP + olive oil-treated mice compared to BaP only-treated mice. The BaP organic metabolite concentrations decreased, while aqueous metabolite concentrations increased in the BaP + olive oil group compared to BaP only-treatment group. DNA lesions were increased in the colon and liver tissues of BaP-treated mice compared to BaP + olive oil treated mice. In summary, our studies suggest that olive oil exerts a protective effect against BaP-induced colon cancer.

Citation Format: Leah D. Banks, Priscilla Amoah, Mohammad S. Niaz, Mary K. Washington, Samuel E. Adunyah, Aramandla Ramesh. Olive oil alters benzo(a)pyrene biotransformation and reduces oxidative DNA damage in colon of ApcMin mouse. [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 1589. doi:10.1158/1538-7445.AM2014-1589

Abstract 3322: Spatio-temporal regulation of epithelial transformation by mistrafficking of EGFR ligand, epiregulin

The EGF receptor (EGFR) ligand epiregulin (EREG) is delivered preferentially to the basolateral cell surface of polarized MDCK cells. Recently, we showed that EREG basolateral trafficking is regulated by a conserved tyrosine residue within a YXXΦ motif (Y156ERV) in its cytoplasmic domain. Interestingly, a Y156A substitution led to apical mistrafficking of EREG and transformation of polarized MDCK cells (PNAS 110: 8960-5, 2013). We have identified EREG mutations (R147stop) in human tumors that would disrupt the basolateral sorting motif of EREG and now report that EREG harboring these patient mutations mistrafficks to the apical surface. We propose that ligand mistrafficking is a driver of transformation rather than being a mere passenger. To test our proposal wild-type and mutant EREG will be inducibly (Tet-ON) expressed at various stages of MDCK cyst formation and maintenance in 3D Matrigel cultures where we have now recapitulated the transformation phenotype induced by EREG-mistrafficking. Results from these experiments will be presented at the meeting.

Citation Format: Bhuminder Singh, Galina Bogatcheva, Mary K. Washington, Robert J. Coffey. Spatio-temporal regulation of epithelial transformation by mistrafficking of EGFR ligand, epiregulin. [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 3322. doi:10.1158/1538-7445.AM2014-3322

Abstract 1583: Western diet enhances benzo(a)pyrene [B(a)P]-induced colon tumorigenesis in the PIRC rat model via proinflammatory mechanisms

Colorectal cancer ranks third in terms of mortalities in the United States. Consumption of Western Diet (rich in red meat and fats), contaminated with environmental toxicants such as benzo(a)pyrene [B(a)P] has also been implicated as one of the causative factors for sporadic colon cancer. Therefore, the objective of this study was to investigate the effect of dietary fat type on B(a)P -induced colon cancer in an adult male rat model, the Polyposis In the Rat Colon (PIRC) kindred type. Groups of PIRC rats (n = 5) were fed with AIN-76A regular diet (RD) or Western diet (WD) and these rats also received 25, 50 and 100 µg B(a)P/kg body wt., daily via oral gavage for a period of 60 days. Rats that were fed with the diets alone, but no B(a)P served as controls. Food consumption and body weights of the rats were periodically monitored. Subsequent to exposure, rats were sacrificed; colons, liver and other tissues were retrieved and preserved in 10% formalin for observation of gross pathological changes. Blood samples were collected and concentrations of cholesterol, triglycerides, and adiponectin were measured. Colon tissues were scored for tumors, and preserved in 10% formalin for observation of pathological changes. Colon and liver samples were analyzed for activation of drug metabolizing enzymes (DMEs) CYP1A1, CYP1B1 and GST. The lack of change in food consumption notwithstanding, body weight loss of WD group compared to RD group and controls (p &lt; 0.05) was noticed. An increased incidence of adenomas and high grade dysplasia were encountered in rats that were fed with WD compared to RD and controls (p &lt; 0.05). The colon tumor counts were more in B(a)P + WD rats compared to their B(a)P + RD counterparts, and also exhibited a B(a)P dose-response relationship, with 100 µg B(a)P/kg registering greater counts. Adenomas with high grade dysplasia were prominent in B(a)P + WD rats compared to B(a)P + RD rats. Immunohistochemical analyses of colon tissue samples for PCNA, cyclin D1, TGF-β, and β-catenin revealed increased levels of cell proliferation and nuclear positivity among all treatment groups. Rats that received B(a)P + WD showed increased levels of cholesterol and triglycerides in comparison to rats that received B(a)P + RD and also controls. Levels of adiponectin did not vary much between B(a)P + WD, and B(a)P + RD groups. Western diet consumption increased DME activation among rats that were given B(a)P + WD with marked increase in rats that were administered 100 µg/kg B(a)P + WD (p &lt; 0.05) compared to other treatment groups. Our results demonstrate that WD accelerates the development of colon tumors induced by B(a)P through proinflammatory action, characterized by gain in tumor number and sizes, and body weight loss.

Citation Format: Kelly L. Harris, Stephanie R. Pulliam, Mohammad S. Niaz, Mary K. Washington, Samuel E. Adunyah, Aramandla Ramesh. Western diet enhances benzo(a)pyrene [B(a)P]-induced colon tumorigenesis in the PIRC rat model via proinflammatory mechanisms. [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 1583. doi:10.1158/1538-7445.AM2014-1583