Early Colorectal Carcinogenesis Research Articles

Abstract 7324: Impact of BMI on immune pathways in preinvasive colorectal lesions

Abstract Background: Obesity is a risk factor for colorectal neoplasia, possibly mediated by metabolic dysregulation or chronic inflammation. Circulating inflammatory cytokines have been associated with an increased risk of CRC, but no studies have examined the impact of BMI on immune gene expression in preinvasive lesions. Our analysis combines data from 3 retrospective epidemiologic studies among patients with colorectal adenomas or serrated polyps. Using a cross-sectional design, we investigate whether BMI categories (obese (OB), overweight (OW), normal (NL)) are associated with T-helper gene pathways. Methods: For each patient, we include demographic, clinical, and specimen (archival FFPE for RNA isolation) data. Immune gene expression data was determined using the NanoString nCounter platform on a subset of cases (n=100) balanced by study site and lesion type from our cohort (n=630). Genes were normalized using a modified RUVseq methodology. We examined 4 pathways (Th1, Th2, Th17, Treg) defined by gene lists included in the NS immune v2. panel. Differences in pathway expression by BMI categories were analyzed using our distance-based methods (Wd* multivariate analysis of variance and TW2 pairwise method) adjusted for age & sex. Using linear regression analysis, we generated coefficients (p-values) for OW and OB vs NL for genes within each pathway. Results: 86 samples passed QC. Th2 and Th1 pathways were significant for OW vs NL (p<0.05) whereas Th17 was marginally significant (<0.1). Several genes within the Th1, Th2, and Th17 pathways were enriched in OW vs. NL: e.g., IL2 (coeff. 0.77 (p=0.008), IL5 (coeff. 1.02, p=0.001), IL17F (coeff. 0.57, p=0.05), respectively. (Table) Conclusion: Enrichment of genes specific to the Th pathways in OW persons suggest that metabolic immune modulation may be important in early colorectal carcinogenesis. Differences in immune pathway and gene expression by BMI categories TW2 (p-value) Wd* (p-value) Pathways Normal (N = 22) Overweight (N = 32) Obese (N = 29) Th2 Ref. 0.017 0.15 0.038 Th1 Ref. 0.03 0.204 0.10 Th17 Ref. 0.073 0.125 0.103 MLR coefficient (p-value) Pathway Gene Overweight vs. Normal Obese vs. Normal ANOVA (p-value) Th2 IL2RA 0.34 (0.041) -0.11 (0.517) 0.010 IL4 0.58 (0.019) 0.22 (0.386) 0.052 IL5 1.02 (0.001) 0.41 (0.191) 0.004 NOTCH1 -0.05 (0.742) -0.34 (0.045) 0.078 Th1 IL12B 0.57 (0.031) 0.40 (0.136) 0.093 IL2 0.77 (0.008) 0.39 (0.179) 0.028 TBX21 0.46 (0.015) 0.19 (0.308) 0.044 Th17 IL17F 0.57 (0.050) 0.42 (0.157) 0.139 IL21 0.77 (0.004) 0.42 (0.131) 0.017 IL23R 0.29 (0.048) -0.008 (0.957) 0.047 IL6R 0.002 (0.990) 0.36 (0.039) 0.041 IRF4 -0.61 (0.007) -0.33 (0.149) 0.025 TGFB1 -0.26 (0.023) -0.19 (0.101) 0.069 Citation Format: Lauren R. Fanning, Bashir Hamidi, Ivan Korostenskij, Souvik Seal, Tami L. Crawford, Todd A. MacKenzie, Elizabeth L. Barry, Jessica E. Thaxton, Martha J. Shrubsole, Benjamin Vincent, John A. Baron, Alexander V. Alekseyenko, Kristin Wallace. Impact of BMI on immune pathways in preinvasive colorectal lesions [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(6_Suppl):Abstract nr 7324.

The effect of aspirin and eicosapentaenoic acid on urinary biomarkers of prostaglandin E2 synthesis and platelet activation in participants of the seAFOod polyp prevention trial.

Urinary prostaglandin (PG) E metabolite (PGE-M) and 11-dehydro (d)-thromboxane (TX) B2 are biomarkers of cyclooxygenase-dependent prostanoid synthesis. We investigated (1) the effect of aspirin 300 mg daily and eicosapentaenoic acid (EPA) 2000 mg daily, alone and in combination, on urinary biomarker levels and, (2) whether urinary biomarker levels predicted colorectal polyp risk, during participation in the seAFOod polyp prevention trial. Urinary PGE-M and 11-d-TXB2 were measured by liquid chromatography-tandem mass spectrometry. The relationship between urinary biomarker levels and colorectal polyp outcomes was investigated using negative binomial (polyp number) and logistic (% with one or more polyps) regression models. Despite wide temporal variability in PGE-M and 11-d-TXB2 levels within individuals, both aspirin and, to a lesser extent, EPA decreased levels of both biomarkers (74% [P ≤ .001] and 8% [P ≤ .05] reduction in median 11-d-TXB2 values, respectively). In the placebo group, a high (quartile [Q] 2-4) baseline 11-d-TXB2 level predicted increased polyp number (incidence rate ratio [IRR] [95% CI] 2.26 [1.11,4.58]) and risk (odds ratio [95% CI] 3.56 [1.09,11.63]). A low (Q1) on-treatment 11-d-TXB2 level predicted reduced colorectal polyp number compared to placebo (IRR 0.34 [0.12,0.93] for combination aspirin and EPA treatment) compared to high on-treatment 11-d-TXB2 values (0.61 [0.34,1.11]). Aspirin and EPA both inhibit PGE-M and 11-d-TXB2 synthesis in keeping with shared in vivo cyclooxygenase inhibition. Colorectal polyp risk and treatment response prediction by 11-d-TXB2 is consistent with a role for platelet activation during early colorectal carcinogenesis. The use of urinary 11-d-TXB2 measurement for a precision approach to colorectal cancer risk prediction and chemoprevention requires prospective evaluation.

Isomaltooligosaccharides inhibit early colorectal carcinogenesis in a 1,2-dimethylhydrazine-induced rat model.

Colon cancer (CC) is a multistage disease and one of the most common cancers worldwide. Establishing an effective treatment strategies of early colon cancer is of great significance for preventing its development and reducing mortality. The occurrence of colon cancer is closely related to changes in the intestinal flora structure. Therefore, remodelling the intestinal flora structure through prebiotics is a powerful approach for preventing and treating the occurrence and development of colon cancer. Isomaltooligosaccharides (IMOs) are often found in fermented foods and can directly reach the gut for use by microorganisms. In this study, a rat model of early colon cancer (DMH) was established by subcutaneous injection of 1,2-dimethylhydrazine, and the model rats were fed IMOs as a dietary intervention (DI). The untargeted faecal metabolomics, gut metabolome and intestinal function of the model rats were investigated. The results showed that DMH, DI and IMOs alone (IMOs) groups exhibited gut microbial community changes. In the DI group, there was an increased abundance of probiotics (Lactobacillus) and decreased abundance of CC marker bacteria (Fusobacterium). The key variations in the faecal metabolites of the DI group included decreased levels of glucose, bile acids (including deoxycholic acid and chenodeoxycholic acid) and amino acids (including L-glutamic acid and L-alanine). In addition, dietary intake of IMOs attenuated the intestinal inflammatory response, improved the intestinal microecological environment, and slowed the development of DMH-induced early CC in rats. This work provides a theoretical basis and technical support for the clinical prevention or treatment of CC with prebiotics.

Ficus dubia latex extract prevent DMH-induced rat early colorectal carcinogenesis through the regulation of xenobiotic metabolism, inflammation, cell proliferation and apoptosis

Ficus dubia latex is recognized as a remedy in Asian traditional medicine with various therapeutic effects. The present study aimed to determine the preventive action of Ficus dubia latex extract (FDLE) on 1,2-dimethylhydrazine (DMH)-induced rat colorectal carcinogenesis and its mechanisms. The experiment included an initiation model in which rats were orally administered with FDLE daily for 1 week before DMH injection until the end of the experiment, while only after DMH injection until the end in the post-initiation model. The results firstly indicated that FDLE treatment could reduce the level of methylazoxymethanol (MAM) in rat colonic lumen by inhibition of the activities of both phase I xenobiotic metabolizing enzymes in the liver and β-glucuronidase in the colon, leading to reduced DNA methylation in colonic mucosal cells, related to the number of ACF in the initiation stage. Besides, FDLE modulated the inflammation which could suppress the growth and induce apoptosis of aberrant colonic mucosal cells, leading to retardation of ACF multiplicity. Therefore, FDLE showed the ability to suppress the DMH-induced rat ACF formation and inflammation promoted growth of ACF. In conclusion, FDLE had the potential to prevent carcinogens-induced rat colorectal carcinogenesis in the initiation stage.

Circulating tumor DNA-based early detection of precancerous colorectal lesions using QClamp XNA-mediated real-time PCR.

The mutation status of the gene involved in early colorectal carcinogenesis and micro-invasive liquid biopsy allows detection of mutated circulating tumor DNA (ctDNA). Early detection of precancerous lesions and CRC is vital in proper treatment and hence associated to patient survival. The frequency of APC, CTNNB1, KRAS, and BRAF mutations in circulating free DNA (cfDNA) were analyzed to evaluate the performance of the mutated ctDNA in detecting polyp and adenoma using highly sensitive QClamp XNA based PCR. A total of 71 patients with low-risk adenoma or polyps were screened and there was no significant difference in the distribution of mutations gender, age, long-term medication, smoking history, alcohol drinking, and fecal occult blood. The positive predictive value (PPV) of the four genes' panel to detect low-risk adenoma and polyps was 39.44% (n = 28/71). Specifically, of all the 71 cases studied, there were 20 cases (28.2%) with APC mutations, 7 cases (9.9%) with CTNNB1 mutations, 4 cases (5.6%) with KRAS mutations, and 2 cases (2.8%) with BRAF mutations. Most mutations occurred at APC876. The four genes' panel detected by XNA-based PCR technique might be suited to efficiently and micro-invasively detect genetic alterations in cfDNA of patients with precancerous colorectal lesions.

Variant profiling of colorectal adenomas from three patients of two families with MSH3-related adenomatous polyposis.

The spectrum of somatic genetic variation in colorectal adenomas caused by biallelic pathogenic germline variants in the MSH3 gene, was comprehensively analysed to characterise mutational signatures and identify potential driver genes and pathways of MSH3-related tumourigenesis. Three patients from two families with MSH3-associated polyposis were included. Whole exome sequencing of nine adenomas and matched normal tissue was performed. The amount of somatic variants in the MSH3-deficient adenomas and the pattern of single nucleotide variants (SNVs) was similar to sporadic adenomas, whereas the fraction of small insertions/deletions (indels) (21–42% of all small variants) was significantly higher. Interestingly, pathogenic somatic APC variants were found in all but one adenoma. The vast majority (12/13) of these were di-, tetra-, or penta-base pair (bp) deletions. The fraction of APC indels was significantly higher than that reported in patients with familial adenomatous polyposis (FAP) (p < 0.01) or in sporadic adenomas (p < 0.0001). In MSH3-deficient adenomas, the occurrence of APC indels in a repetitive sequence context was significantly higher than in FAP patients (p < 0.01). In addition, the MSH3-deficient adenomas harboured one to five (recurrent) somatic variants in 13 established or candidate driver genes for early colorectal carcinogenesis, including ACVR2A and ARID genes. Our data suggest that MSH3-related colorectal carcinogenesis seems to follow the classical APC-driven pathway. In line with the specific function of MSH3 in the mismatch repair (MMR) system, we identified a characteristic APC mutational pattern in MSH3-deficient adenomas, and confirmed further driver genes for colorectal tumourigenesis.

Induction of colorectal carcinogenesis in the C57BL/6J and A/J mouse strains with a reduced DSS dose in the AOM/DSS model

BackgroundColorectal cancer (CRC) is one of the most frequently diagnosed cancers worldwide and thus mouse models of CRC are of significant value to study the pathogenesis. The Azoxymethane/Dextran sulfate sodium (AOM/DSS) model is a widely used, robust initiation-promotion model for chemical induction of colitis-associated CRC in rodents. However, the dosage of chemicals, treatment regimens and outcome measures vary greatly among studies employing this model. Thus, the aim of this study was to examine an AOM/DSS model involving a reduced (1%) dose of DSS for induction of carcinogenesis in A/J and C57BL/6J (B6) mice.ResultsWe show that colonic preneoplastic lesions can be reliably detected in A/J and B6 mice by use of a AOM/DSS model involving a single injection of 10 mg/kg AOM followed by three 7-day cycles of a low-dose (1%) DSS administration. Supporting existing evidence of A/J mice exhibiting higher susceptibility to AOM than B6 mice, our AOM/DSS-treated A/J mice developed the highest number of large colonic lesions. Clinical symptoms in both strains subjected to the AOM/DSS treatment did not persist in-between treatment cycles, demonstrating that the animals tolerated the treatment well.ConclusionsOur findings suggest that a reduced dose of DSS in the AOM/DSS model can be considered in future studies of early phase colorectal carcinogenesis in the A/J and B6 mouse strains using preneoplastic lesions as an outcome measure, and that such regimen may reduce the risk of early trial terminations to accommodate human endpoints. Overall, our data emphasize the importance of devoting attention towards choice of protocol, outcome measures and mouse strain in studies of CRC in mice according to the study purpose.

Differential gene expression of tight-junction proteins and their correlation with PRSS8 and prognosis in colorectal cancer.

e15548 Background: Intestinal epithelia cells are made up of tight junctions, adheren junctions and desmosomes. As integral membrane proteins, the tight junction proteins (TJPs) claudins (CLDNs) and occludin (OCLN) are the most important TJPs that play a major role in maintaining the integrity of the intestinal epithelia and regulate several key signaling pathways in cancers. Dysregulation of tight junction and adheren junction has been shown to be associated with disruption of mucosa barriers, chronic colitis, early onset of colorectal carcinogenesis, epithelial mesenchymal transition and cancer metastasis. Our recent studies have shown that intestinal conditional knockout of the Press8 (protease serine 8) gene causes disruption of intestinal epithelial homeostasis, spontaneous inflammation and tumorigenesis in mouse intestine. Whether these pathogeneses are resulted from TJPs alterations and their correlation with PRSS8 are largely unknown. Methods: PRSS8 overexpression plasmid was transfected into colon cancer cell line HCT116 cells and proteomics was conducted. The Cancer Genome Atlas colorectal cancer (CRC) data set was deeply mined, and the correlation between TJPs’ alterations, PRSS8 and prognosis was analyzed. Results: In vitro proteomics assay showed that increasing expression of PRSS8 led to differential expression of cellular TJPs and adheren proteins, including upregulation of E-cadherin, TJP1 (ZO-1) and OCLN, and downregulation of RAC1, CDC42, RHOA, CLDND1, ARHGAP1, CTNNB1 and CTNNBL1. TCGA data mining showed differential gene expression of tight junction proteins. For instance, similar as PRSS8, most colonic mucosal TJPs, such as TJP1 (ZO-1), TJP3, OLCN, CLDN7, CLDN8 and PTPRJ, were significantly decreased in CRC tissues (n = 215), compared to normal mucosa (n = 22). Moreover, these reduced expression of TJPs were positively correlated with the reduction of PRSS8 and were inversely associated with prognosis. In contrast, another group of TJPs, such as TJP2, CLDN1, CLDN2 and CLDN12, was significantly increased in CRC tissues in comparison with the normal mucosa. These increases of expression were negatively correlated with PRSS8 expression and poor outcomes. More interestingly, the PTPRJ, a newly identified tumor suppressor, was dramatically reduced in metastatic CRC, compared to the primary CRC. Furthermore, the reduced expression of PTPRJ was linked to poor prognosis in the CRC patients. The underlying mechanisms of regulatory interaction between PRSS8 and TJPs are under investigation. Conclusions: TJPs are differentially expressed in CRC and the alterations were well correlated with PRSS8 and prognosis. Therefore, these two opposite groups of TJPs could be used as biomarkers for the monitoring of early onset colorectal carcinogenesis, progression and for the prediction of prognosis.

Plasma sex hormones and risk of conventional and serrated precursors of colorectal cancer in postmenopausal women

BackgroundSex hormones have been suggested to play a role in colorectal cancer (CRC), but their influence on early initiation of CRC remains unknown.MethodsWe retrospectively examined the associations with risk of CRC precursors, including conventional adenomas and serrated polyps, for plasma estrone, estradiol, free estradiol, testosterone, free testosterone, sex hormone-binding globulin (SHBG), and the ratio of estradiol to testosterone among 5404 postmenopausal women from the Nurses’ Health Study I and II. Multivariable logistic regression was used to calculate the odds ratio (OR) and 95% confidence intervals (CI). Given multiple testing, P < 0.005 was considered statistically significant.ResultsDuring 20 years of follow-up, we documented 535 conventional adenoma cases and 402 serrated polyp cases. Higher concentrations of SHBG were associated with lower risk of conventional adenomas, particularly advanced adenomas (multivariable OR comparing the highest to the lowest quartile, 0.40, 95% CI 0.24–0.67, P for trend < 0.0001). A nominally significant association was found for SHBG with lower risk of large serrated polyps (≥ 10 mm) (OR, 0.47, 95% CI 0.17–1.35, P for trend = 0.02) as well as free estradiol and free testosterone with higher risk of conventional adenomas (OR, 1.54, 95% CI 1.02–2.31, P for trend = 0.03 and OR, 1.33, 95% CI 0.99–1.78, P for trend = 0.03, respectively).ConclusionsThe findings suggest a potential role of sex hormones, particularly SHBG, in early colorectal carcinogenesis.

Glucosamine and Chondroitin Supplements and Risk of Colorectal Adenoma and Serrated Polyp.

Studies have shown an inverse association between use of glucosamine and chondroitin supplements and colorectal cancer risk. However, the association with the precursor lesion, colorectal adenoma and serrated polyp, has not been examined. Analyses include 43,163 persons from the Nurses' Health Study (NHS), Health Professionals Follow-up Study (HPFS), and NHS2 who reported on glucosamine/chondroitin use in 2002 and who subsequently underwent ≥1 lower gastrointestinal endoscopy. By 2012, 5,715 conventional (2,016 high-risk) adenomas were detected, as were 4,954 serrated polyps. Multivariable logistic regression for clustered data was used to calculate OR and 95% confidence intervals (CI). Glucosamine/chondroitin use was inversely associated with high risk and any conventional adenoma in NHS and HPFS: in the pooled multivariable-adjusted model, glucosamine + chondroitin use at baseline was associated with a 26% (OR = 0.74; 95% CI, 0.60-0.90; P heterogeneity = 0.23) and a 10% (OR = 0.90; 95% CI, 0.81-0.99; P heterogeneity = 0.36) lower risk of high-risk adenoma and overall conventional adenoma, respectively. However, no association was observed in NHS2, a study of younger women (high-risk adenoma: OR = 1.09; 95% CI, 0.82-1.45; overall conventional adenoma: OR = 1.00; 95% CI, 0.86-1.17), and effect estimates pooled across all three studies were not significant (high-risk: OR = 0.83; 95% CI, 0.63-1.10; P heterogeneity = 0.03; overall conventional adenoma: OR = 0.93; 95% CI, 0.85-1.02; P heterogeneity = 0.31). No associations were observed for serrated polyps. Glucosamine/chondroitin use was associated with lower risks of high-risk and overall conventional adenoma in older adults; however, this association did not hold in younger women, or for serrated polyps. Our study suggests that glucosamine and chondroitin may act on early colorectal carcinogenesis in older adults.

Metabolomics Analysis of Aspirin's Effects in Human Colon Tissue and Associations with Adenoma Risk.

Although substantial evidence supports aspirin's efficacy in colorectal cancer chemoprevention, key molecular mechanisms are uncertain. An untargeted metabolomics approach with high-resolution mass spectrometry was used to elucidate metabolic effects of aspirin treatment in human colon tissue. We measured 10,269 metabolic features in normal mucosal biopsies collected at colonoscopy after approximately 3 years of randomized treatment with placebo, 81 or 325 mg/day aspirin from 325 participants in the Aspirin/Folate Polyp Prevention Study. Linear regression was used to identify aspirin-associated metabolic features and network analysis was used to identify pathways and predict metabolite identities. Poisson regression was used to examine metabolic features associations with colorectal adenoma risk. We detected 471 aspirin-associated metabolic features. Aside from the carnitine shuttle, aspirin-associated metabolic pathways were largely distinct for 81 mg aspirin (e.g., pyrimidine metabolism) and 325 mg (e.g., arachidonic acid metabolism). Among aspirin-associated metabolic features, we discovered three that were associated with adenoma risk and could contribute to the chemopreventive effect of aspirin treatment, and which have also previously been associated with colorectal cancer: creatinine, glycerol 3-phosphate, and linoleate. The last two of these are in the glycerophospholipid metabolism pathway, which was associated with 81 mg aspirin treatment and provides precursors for the synthesis of eicosanoids from arachidonic acid upstream of cyclooxygenase inhibition by aspirin. Conversely, carnitine shuttle metabolites were increased with aspirin treatment and associated with increased adenoma risk. Thus, our untargeted metabolomics approach has identified novel metabolites and pathways that may underlie the effects of aspirin during early colorectal carcinogenesis.

Periodontal Disease, Tooth Loss, and Risk of Serrated Polyps and Conventional Adenomas.

Growing data indicate an association between periodontal disease and the development of cancer. However, the evidence for colorectal cancer has been inconsistent and longitudinal study examining its precursor lesions is lacking. We prospectively collected information on periodontal disease and number of tooth loss in the Nurses' Health Study (1992-2002) and the Health Professionals Follow-up Study (1992-2010). Polyp diagnosis was acquired via self-reported questionnaires and confirmed through review of medical records. We used logistic regression to calculate the multivariate-adjusted ORs and 95% confidence intervals (CI) with adjustment for smoking and other known risk factors for periodontal disease and colorectal cancer. In this study, we included 17,904 women and 24,582 men. We documented 2,336 cases of serrated polyps and 4,102 cases of conventional adenomas among 84,714 person-endoscopies throughout follow-up. The ORs of serrated polyps and conventional adenomas comparing individuals with and without periodontal disease were 1.17 (95% CI, 1.06-1.29) and 1.11 (95% CI, 1.02-1.19), respectively. Compared with participants without tooth loss, those who lost ≥4 teeth had 20% (OR, 1.20; 95% CI, 1.03-1.39) greater risk of serrated polyps (P trend 0.01). Among never smokers, similar associations with periodontal disease were observed for both serrated polyps (OR, 1.20; 95% CI, 1.02-1.41) and conventional adenomas (OR, 1.12; 95% CI, 1.00-1.26). History of periodontal disease and possibly higher number of tooth loss may modestly increase the risk of developing colorectal precursor lesions. Our findings advance our understanding of the interplay between oral health, microbiome, and early colorectal carcinogenesis.

Abstract B33: Racial differences in tumor-associated microbes in early colorectal carcinogenesis

Abstract African Americans (AA) have a higher incidence of colorectal cancer (CRC) than Caucasian Americans (CA). Emerging evidence indicates that pathogenic tumor-associated microbes (TAMs) within preinvasive lesions may promote carcinogenesis. Since AAs are more prone than CAs to robust inflammatory responses to bacteria and fungi, especially at younger ages, infiltrates in early neoplasms may differ by race and age. To study this issue, we selected a convenience sample of 35 preinvasive cases diagnosed between October 2013 and October 2016 at the Medical University of South Carolina for microbial analysis. The study pathologist diagnosed the degree of dysplasia and predominant histology for each lesion. We extracted DNA from 10-micron-thick FFPE sections and sequenced 16S rRNA gene amplicons to determine the microbial communities. We normalized the data using central log ratio transformation with pseudo-counts and selected 20 microbes previously associated with CRC for analysis. Linear regression was used to assess associations between TAMs and race while adjusting for age and sex. We also examined these associations by colorectal location (distal, proximal), degree of dysplasia (high, not high), and age (&amp;lt; 55, 55+) using product interaction terms in our statistical models. 49% of cases were AAs, 57% were female, and 51% were less than 55 years of age. We analyzed 4 serrated polyps, 6 tubular adenoma, 16 tubulovillous adenomas, and 9 villous adenomas. 40% of the cases had high-grade dysplasia (including focal) and 51% of all lesions were from the distal colon (and rectum). We observed that AAs compared to CAs had a significantly higher microbial abundance of genus Escherichia (coef. 1.42 p=0.005), species Escherichia coli (coef. 1.38, p=0.007), and genus Shigella (coef. 1.15, p=0.02). Moreover, AAs had relatively higher TAM infiltration with these microbes in distal colorectal lesions than CAs, but there were no differences by race in the proximal colon. Finally, we observed that in comparison to older CAs, older AAs had relatively higher abundance of Escherichia (coef. 2.50; p &amp;lt; 0.001; p for interaction=0.056), E. coli (coef. 2.45, p=0.001; p for interaction=0.04), and Shigella (coef. 2.24, p=0.001; p for interaction=0.04), but there were no significant differences in younger patients by race. Two additional microbes, Porphyromonas (p=0.01) and Ruminococcus gnavus (p=0.02), were found in lower relative abundance in AAs vs. CAs. We identified racial differences in TAMs associated with the Enterobacteriaceae family. The stronger racial differences in TAMs observed in the older but not younger patients may reflect age-related differences in bacterial clearance. In future studies, it will be important to compare the TAMs, immune reactions with markers of tumor progression. Citation Format: Kristin Wallace, David N. Lewin, Christine Bookhout, Shaoli Sun, Brianna Bronsky, Chentha Vasu, Brenda J. Hoffman, John A. Baron, Alexander V. Alekseyenko. Racial differences in tumor-associated microbes in early colorectal carcinogenesis [abstract]. In: Proceedings of the AACR Special Conference on the Microbiome, Viruses, and Cancer; 2020 Feb 21-24; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2020;80(8 Suppl):Abstract nr B33.

Isolation, characterization and identification of antigenotoxic and anticancerous indigenous probiotics and their prophylactic potential in experimental colon carcinogenesis

Colorectal cancer, the third most commonly diagnosed cancer, is a lifestyle disease where diet and gut microbiome contribute intricately in its initiation and progression. Prophylactic bio-interventions mainly probiotics offer an alternate approach towards reducing or delaying its progression. Therefore, the present study was designed wherein a robust protocol for the isolation, characterization, and identification of indigenous probiotics having antigenotoxic and anticancerous activity was followed along with their prophylactic potential assessment in early experimental colorectal carcinogenesis. Among forty-six isolated lactic acid bacterial strains, only three were selected on the basis of antigenotoxicity against N,N-Dimethyl dihydrazine dihydrochloride and 4-Nitroquinoline 1-oxide and probiotic attributes. All three selected probiotic strains exhibited anticancerous potential as is evident by the reduced Aberrant Crypt Foci, reduced fecal pH, enhanced fecal lactic acid bacteria and altered fecal enzymes (β-glucuronidase, nitroreductase, β-glucosidase) that modulated gut microbiota and microenvironment resulting into restored histoarchitecture of the colon. The results are a clear indicator of the prophylactic potential of selected indigenous probiotics which may be used as an alternative prophylactic biological therapy against colon carcinogenesis particularly in highly susceptible individuals.

State Variation in Early-Onset Colorectal Cancer in the United States, 1995-2015.

The extent to which the increase in early-onset colorectal cancer (CRC) in the United States varies geographically is unknown. We analyzed changes in CRC incidence and risk factors among people aged 20-49 years by state using high-quality population-based cancer registry data provided by the North American Association of Central Cancer Registries and national survey data, respectively. Early-onset CRC incidence was mostly stable among blacks and Hispanics but increased in 40 of 47 states among non-Hispanic whites, most prominently in western states. For example, rates increased in Washington from 6.7 (per 100 000) during 1995-1996 to 11.5 during 2014-2015 (rate ratio = 1.73, 95% confidence interval = 1.48 to 2.01) and in Colorado from 6.0 to 9.5 (rate ratio = 1.57, 95% confidence interval = 1.30 to 1.91). Nevertheless, current CRC incidence was highest in southern states. From 1995 to 2005, increases occurred in obesity prevalence in all states and heavy alcohol consumption in one-third of states, but neither were correlated with CRC incidence trends. Early-onset CRC is increasing most rapidly among whites in western states. Etiologic studies are needed to explore early life colorectal carcinogenesis.

Circulating inflammation markers and colorectal adenoma risk.

Inflammation is a driver of colorectal neoplasia; however, what particular inflammatory processes play a role in early carcinogenesis are unclear. We compared serum levels of 78 inflammation markers between 171 pathologically confirmed colorectal adenoma cases (including 48 incident cases) and 344 controls within the Prostate, Lung, Colorectal and Ovarian Cancer Screening Trial. We used weighted multivariable logistic regression to compute odds ratio (OR) and 95% confidence interval (CI). We found 14 markers associated with risk of adenoma overall; three of these were also associated with incident adenoma: CC-chemokine cysteine motif chemokine ligand 20 (CCL20) [overall adenoma fourth versus first quartile: OR 4.8, 95% CI 2.0-12, Ptrend 0.0007; incident adenoma third versus first tertile: OR 4.6, 95% CI 1.0-22, Ptrend 0.03], growth-related gene oncogene products (GRO) [OR 3.8, 95% CI 1.6-9.3, Ptrend 0.006 and OR 3.6, 95% CI 1.1-12, Ptrend 0.04, respectively] and insulin [OR 2.9, 95% CI 0.8-10, Ptrend 0.05 and OR 7.8, 95% CI 1.3-46, Ptrend 0.03, respectively]. All statistical tests were two-sided. These results provide important new evidence implicating CCL20- and GRO-related pathways in early colorectal carcinogenesis and further support a role for insulin.

Comprehensive molecular analysis based on somatic copy number alterations in intramucosal colorectal neoplasias and early invasive colorectal cancers.

It is unclear whether somatic copy number alterations (SCNAs) contribute to the development of colorectal cancer (CRC). Here, we aimed to identify the molecular profiles of early colorectal carcinogenesis based on SCNAs and determine the associations of other molecular abnormalities for the detection of neoplasia in both intramucosal neoplasia (IMN) and invasive CRC with invasion into the muscular layer without metastasis (early invasive CRC). A single nucleotide polymorphism array was used to examine 100 colorectal IMNs (low-grade adenoma [LGA], 40; high-grade adenoma [HGA], 25; intramucosal adenocarcinoma [IMA], 35) and early invasive CRC (20 tumors). In addition, genetic mutations (KRAS, BRAF), TP53 overexpression, microsatellite instability (MSI), and DNA methylation (low, intermediate, high) were examined. Hierarchical clustering analysis based on the SCNA pattern was carried out to identify molecular profiles in IMNs and early invasive CRC. Colorectal tumors were classified into three subgroups based on SCNA patterns. Subgroup 1 was characterized by multiple SCNAs, subgroup 3 was closely associated with infrequent SCNAs, and subgroup 2 was an intermediate subgroup in SCNA pattern between subgroups 1 and 3. Although mutations in KRAS were commonly found in all three subgroups, overexpression of TP53 was observed primarily in subgroup 1 and 2. DNA methylation showed a low/intermediate type. Finally, no MSI was detected. Each subgroup was correlated with histology (subgroup 1, early invasive CRC; subgroup 2, LGA; subgroups 2 and 3, HGA and IMA). Considerable SCNAs may be required for acquisition of invasive ability in CRC. Our results provide novel insights into early CRC.

Low-Dose Aspirin Acetylates Cyclooxygenase-1 in Human Colorectal Mucosa: Implications for the Chemoprevention of Colorectal Cancer.

The mechanism of action of low-dose aspirin in the prevention of colorectal cancer (CRC) remains largely hypothetical. We aimed to compare the effects of low-dose aspirin (100 mg/day for 7 days) given to 40 individuals undergoing CRC screening on the extent of cyclooxygenase (COX)-1 acetylation at serine-529 (AceCOX-1), in blood platelets vs. colorectal mucosa, at 7 (group 1) and 24 h (group 2) after dosing. A significantly (P < 0.01) lower %AceCOX-1 was detected in colonic and rectal mucosa (average 64%) vs. platelets (average 75%) in both groups. This effect was associated with an average 46% (P < 0.01) and 35% (P < 0.05) reduction in prostaglandin (PG) E2 levels and phosphorylated S6 (p-S6) levels, respectively. Rectal mucosal levels of p-S6/S6 significantly (P < 0.01) correlated with PGE2 . These findings demonstrate that low-dose aspirin produces long-lasting acetylation of COX-1 and downregulation of p-S6 in human colorectal mucosa, an effect that may interfere with early colorectal carcinogenesis.

Molecular alterations in colorectal adenomas and intramucosal adenocarcinomas defined by high-density single-nucleotide polymorphism arrays

BackgroundWe examined colorectal adenomas and intramucosal adenocarcinomas (IMAs) to develop a genome-wide overview of copy number alterations (CNAs) during colorectal tumorigenesis.MethodsWe analysed CNAs using a high-resolution SNP array of isolated tumour glands obtained from 55 colorectal adenomas (35 low-grade adenomas and 20 high-grade adenomas) and 30 IMAs. Next, we examined whether frequent CNAs differed between low-grade and high-grade adenomas or high-grade adenomas and IMAs. Finally, we investigated the total lengths of the CNAs in low-grade adenomas, high-grade adenomas, and IMAs.ResultsAlthough no frequent CNAs were found in low-grade adenomas, the most frequent alterations of high-grade adenomas were gains of 7q11, 7q21 and 9p13 and loss of 5q14.3-35. High levels of gains were detected at 13q, 7q, 8p, 20q, 7p, 18p and 17p in IMAs. Although no frequent alteration differed between low-grade and high-grade adenomas, significant differences of gains at 13q, 17p and 18p were found between high-grade adenoma and IMAs. Although the total lengths of all CNAs (gains and losses), copy number gains, and losses of heterozygosity were significantly greater in high-grade adenomas than in low-grade adenomas, no significant differences in the lengths of CNAs were found between high-grade adenomas and IMAs.ConclusionsGenomic alterations play an essential role in early colorectal carcinogenesis. CNAs in colorectal tumours provide new insights for evaluation of colorectal tumorigenesis.

Colonization with enterotoxigenic Bacteroides fragilis is associated with early-stage colorectal neoplasia

BackgroundEnterotoxigenic Bacteroides fragilis (ETBF) is a toxin-producing bacteria thought to possibly promote colorectal carcinogenesis by modulating the mucosal immune response and inducing epithelial cell changes. Here, we aim to examine the association of colonic mucosal colonization with ETBF and the presence of a range of lesions on the colonic neoplastic spectrum.MethodsMucosal tissue from up to four different colonic sites was obtained from a consecutive series of 150 patients referred for colonoscopy. The presence and relative abundance of the B. fragilis toxin gene (bft) in each tissue sample was determined using quantitative PCR, and associations with clinicopathological characteristics were analysed.FindingsWe found a high concordance of ETBF between different colonic sites (86%). Univariate analysis showed statistically significant associations between ETBF positivity and the presence of low-grade dysplasia (LGD), tubular adenomas (TA), and serrated polyps (P-values of 0.007, 0.027, and 0.007, respectively). A higher relative abundance of ETBF was significantly associated with LGD and TA (P-values of < 0.0001 and 0.025, respectively). Increased ETBF positivity and abundance was also associated with left-sided biopsies, compared to those from the right side of the colon.ConclusionOur results showing association of ETBF positivity and increased abundance with early-stage carcinogenic lesions underlines its importance in the development of colorectal cancer, and we suggest that detection of ETBF may be a potential marker of early colorectal carcinogenesis.