Most colitis associated carcinomas lack expression of LGR5: a preliminary study with implications for unique pathways of carcinogenesis compared to sporadic colorectal carcinoma

Background Leucine-rich repeat-containing G-protein-coupled receptor 5 (LGR5), a component of the Wnt receptor complex, is thought to lineage label gastric and intestinal stem cells. LGR5 expression is increased in colorectal carcinoma (CRC) compared to normal tissue. Colitis associated colorectal adenocarcinoma (CAC) often shows distinct morphologic and molecular phenotypes compared to sporadic cases. However, the expression profile of LGR5, and by extension the potential role of an intestinal stem cell phenotype, has not been well described in a series of human CAC. Method RNA in situ hybridization (ISH) for LGR5 expression on 30 CACs (12 cases with conventional morphology and 18 cases with non-conventional type morphology) from 29 inflammatory bowel disease (IBD) patients was performed and compared the expression profile to a control group of 10 sporadic CRCs. Immunohistochemistry for beta-catenin and SATB2 was performed on the 30 CACs. Result LGR5 was positive in 30% (9/30) of CAC cases and 90% (9/10) of sporadic CRCs (p = 0.002). A large majority (89%) of LGR5 positive CACs were of the conventional histologic type, and conventional type CAC showed a significantly higher LGR5 score (median 3.0; interquartile range 1.75–3.25) than non-conventional type CAC (median 1.5; interquartile range 1.00–2.00) (p = 0.034). CAC with conventional morphology did have a lower level of LGR5 expression than sporadic CRC. Sporadic CRCs showed a significantly higher LGR5 level score than non-conventional type CACs (p < 0.001). Nuclear translocation of beta-catenin was strongly associated with LGR5 expression (p = 0.003), however no significant association was identified between SATB2 expression and LGR5 expression status in CACs. Conclusion These findings suggest that the wider spectrum of tumor morphology in CAC may be associated with absence of a LGR5-expressing intestinal stem cell phenotype.

Metagenomic and metabolomic analyses reveal distinct stage-specific phenotypes of the gut microbiota in colorectal cancer

Colorectal cancer (CRC) worldwide affects over a quarter of a million people each year. Most sporadic CRCs develop through formation of polypoid adenomas and are preceded by intramucosal carcinoma (Stage 0), which can progress into malignant forms. Detection of early cancers and their endoscopic removal are priorities for cancer control. Human gut microbiome has been associated to CRC development, and its comprehensive characterization is of a great importance to assess its potential as a diagnostic marker. We performed whole shotgun metagenomic sequencing and CE-TOFMS-based metabolomic studies on fecal samples collected from 616 participants undergoing colonoscopy to assess taxonomic and functional characteristics of gut microbiota and metabolites. As a result, microbiome and metabolite shifts were apparent in cases of multiple polypoid adenomas (MP) and Stage 0, in addition to more advanced lesions (Stage I/II and Stage III/IV). Two distinct patterns of microbiome elevations were found (P<0.005). First, CRC-associated species including Fusobacterium nucleatum were elevated continuously from Stage 0 to more advanced stages. Second, Atopobium parvulum and Actinomyces odontolyticus, which co-occurred in Stage 0, were elevated only in MP and/or in Stage 0. Metabolome analyses showed elevation of branched-chain amino acids and phenylalanine in Stage 0 and bile acids including deoxycholate in MP and/or Stage 0. Metagenomic functional analyses showed amino acid metabolism and sulfide producing pathways were associated with CRCs. Our study indicates possible etiological and diagnostic significance of fecal microbiota and metabolite in the very early stages of CRC (Yachida et al., Nature Medicine 2019).

Most colitis associated carcinomas lack expression of LGR5: a preliminary study with implications for unique pathways of carcinogenesis compared to sporadic colorectal carcinoma

Background: Leucine-rich repeat-containing G-protein-coupled receptor 5 (LGR5), a component of the Wnt receptor complex, is thought to lineage label gastric and intestinal stem cells. LGR5 expression is increased in colorectal carcinoma (CRC) compared to normal tissue. Colitis associated colorectal adenocarcinoma (CAC) often shows distinct morphologic and molecular phenotypes compared to sporadic cases. However, the expression profile of LGR5, and by extension the potential role of an intestinal stem cell phenotype, has not been well described in a series of human CAC. Method: RNA in situ hybridization (ISH) for LGR5 expression on 30 CACs (12 cases with conventional morphology and 18 cases with non-conventional type morphology) from 29 inflammatory bowel disease (IBD) patients was performed and compared the expression profile to a control group of 10 sporadic CRCs. Immunohistochemistry for beta-catenin and SATB2 was performed on the 30 CACs. Result: LGR5 was positive in 30% (9/30) of CAC cases and 90% (9/10) of sporadic CRCs (p=0.002). A large majority (89%) of LGR5 positive CACs were of the conventional histologic type, and conventional type CAC showed a significantly higher LGR5 score (median 3.0; interquartile range 1.75-3.25) than non-conventional type CAC (median 1.5; interquartile range 1.00-2.00) (p = 0.034). CAC with conventional morphology did have a lower level of LGR5 expression than sporadic CRC. Sporadic CRCs showed a significantly higher LGR5 level score than non-conventional type CACs (p <0.001). Nuclear translocation of beta-catenin was strongly associated with LGR5 expression (p=0.003), however no significant association was identified between SATB2 expression and LGR5 expression status in CACs. Conclusion: These findings suggest that the wider spectrum of tumor morphology in CAC may be associated with absence of a LGR5 -expressing intestinal stem cell phenotype.

Most colitis associated carcinomas lack expression of LGR5: implications for unique pathways of carcinogenesis compared to sporadic colorectal carcinoma

BackgroundLeucine-rich repeat-containing G-protein-coupled receptor 5 (LGR5), a component of the Wnt receptor complex, is thought to lineage label gastric and intestinal stem cells. LGR5 expression is increased in colorectal carcinoma (CRC) compared to normal tissue. Colitis associated colorectal adenocarcinoma (CAC) often shows distinct morphologic and molecular phenotypes compared to sporadic cases. However, the expression profile of LGR5, and by extension the potential role of an intestinal stem cell phenotype, has not been well described in a series of human CAC. MethodRNA in situ hybridization (ISH) for LGR5 expression on 30 CACs (12 cases with conventional morphology and 18 cases with non-conventional type morphology) from 29 inflammatory bowel disease (IBD) patients was performed and compared the expression profile to a control group of 10 sporadic CRCs. ResultLGR5 was positive in 30% (9/30) of CAC cases and 90% (9/10) of sporadic CRCs (p=0.002). A large majority (89%) of LGR5 positive CACs were of the conventional histologic type, and conventional type CAC showed a significantly higher LGR5 score (median 3.0; interquartile range 1.75-3.25) than non-conventional type CAC (median 1.5; interquartile range 1.00-2.00) (p = 0.034). CAC with conventional morphology did have a lower level of LGR5 expression than sporadic CRC. Sporadic CRCs showed a significantly higher LGR5 level score than non-conventional type CACs (p <0.001). ConclusionThese findings suggest that the wider spectrum of tumor morphology in CAC may be associated with absence of a LGR5-expressing intestinal stem cell phenotype.

Mutational signatures of early-onset colorectal cancer.

e15113 Background: Despite a reduction of Colorectal Cancer (CRC) incidence in western countries in the past decades, Early-Onset CRCs (EO-CRC, patients diagnosed with CRC ≤ 40 years old) incidence has increased. Although frequently occurring in the context of familial syndromes, EO-CRCs are mainly sporadic cases and phenotipically enriched for distal localisation and advanced stage at diagnosis. Whether EO-sporadic CRCs pathogenesis differs from that of normal-onset (NO) CRC and how this might impact incidence rates is currently unknown. This had prompted us to ask if, at the genetic level, “traces” of peculiar pathogenic processes could be identified in EO-specific (or -enriched) genetic signatures (GS). Methods: The mutational signatures of 424 TCGA CRC patient samples (19 EO and 405 ≥ 50 years at diagnosis) were analyzed and the similarity between each mutational profile and COSMIC GS was calculated using Bioconductor R package Mutational Patterns (doi: 10.1186/s13073-018-0539-0). Unsupervised hierarchical clustering of the samples according to similarity to GS was performed in single cohort and pooled analysis. Association between age and individual GS was assessed through grouped and linear correlation analysis. Results: EO-CRC patients were grouped in three main clusters: Cluster1 exposing a major similarity with GS10 (associated with defects in polymerase proofreading activity), Cluster2 showing stronger similarities with GS6 (associated with mismatch repair deficiency), and GS1 (associated with 5-MeC deamination) and Cluster3 presenting similarity with multiple GSs, such as 3 (associated with homologous recombination deficiency) and 5 (pathogenesis unknown). Overall this clustering was maintained when EO-CRC samples were pooled with NO CRC. Grouped and correlation analysis revealed no significant association between age and individual GSs, including GS1 (associated with age). Conclusions: These preliminary analyses show that the relative contribution of known GS is similar in EO and NO cohorts of patients. Possible enrichment for EO-CRC in specific signature clusters will be analysed on a wider sample series.

Whole Exome Sequencing of Ulcerative Colitis–associated Colorectal Cancer Based on Novel Somatic Mutations Identified in Chinese Patients

BackgroundCarcinogenesis is a severe consequence of chronic ulcerative colitis. We investigated the somatic mutations and pathway alterations in ulcerative colitis–associated colorectal cancer (CRC) in Chinese patients compared with sporadic CRCs to reveal potential therapeutic targets in ulcerative colitis–associated CRC.MethodsWhole exome sequencing was performed on archival tumor tissues and paired adjacent nondysplastic mucosa from 10 ulcerative colitis–associated CRC patients at a high risk of carcinogenesis. Genomic alteration profiles from 223 primary CRCs from The Cancer Genome Atlas served as sporadic CRC controls. A meta-analysis was performed to investigate differences in major genetic mutations between ulcerative colitis–associated and Crohn’s disease–associated CRCs.ResultsWe identified 44 nonsilent recurrent somatic mutations via whole exome sequencing, including 25 deleterious mutations involved in apoptosis and the PI3K-Akt pathway (COL6A3, FN1), autophagy (ULK1), cell adhesion (PODXL, PTPRT, ZFHX4), and epigenetic regulation (ARID1A, NCOR2, KMT2D, NCOA6, MECP2, SUPT6H). In total, 11 of the 25 mutated genes significantly differed between ulcerative colitis–associated CRC and sporadic CRC (APC, APOB, MECP2, NCOR2, NTRK2, PODXL, RABGAP1, SIK3, SUPT6H, ULK1, USP48). Somatic TP53 mutations occurred in 33% of ulcerative colitis–associated CRCs. Subsequent meta-analysis revealed distinct mutation profiles for Crohn’s disease– and ulcerative colitis–associated CRCs. Mutations involving the NF-kB pathway and epigenetic regulation were more common in ulcerative colitis–associated CRCs than in sporadic CRCs.ConclusionDistinct genomic alteration profiles of deleterious somatic mutations were found in ulcerative colitis–associated and sporadic CRCs. Mutations of epigenetic regulators, such as KMT2D and NCOA6, were common, suggesting an epigenetic pathomechanism for colitis-associated carcinoma in Chinese patients.

IBD-associated Colon Cancers Differ in DNA Methylation and Gene Expression Profiles Compared With Sporadic Colon Cancers

Background and Aims As ulcerative colitis [UC]-associated colorectal cancer [CRC] and sporadic CRC differ in presentation and molecular features, we sought to evaluate differences in the impact of DNA methylation on gene expression. Methods DNA methylation was assessed in 11 UC-CRCs and adjacent tissue and 11 sporadic CRCs and adjacent tissue, using Illumina arrays. RNA sequencing was performed on 10 UC-CRCs and adjacent tissue and eight sporadic CRCs and adjacent tissues. Differences in DNA methylation and transcript expression, as well as their correlation in the same tissues, were assessed. Immunohistochemistry was performed for three proteins, ANPEP, FAM92A1, and STK31, all of which exhibited an inverse correlation between DNA methylation and transcript expression in UC. Results Thirty three loci demonstrated differences in DNA methylation between UC-CRC and adjacent tissue. In contrast, there were 4204 differentially methylated loci between sporadic colon cancer and adjacent tissue. Eight hundred eighty six genes as well as 10 long non-coding RNAs [lncRNA] were differentially expressed between UC-CRC and adjacent tissues. Although there were no differentially methylated loci between UC and sporadic CRC, 997 genes and 38 lncRNAs were differentially expressed between UC-CRC and sporadic CRC. In UC, 18 genes demonstrated a negative correlation between DNA methylation and transcript expression. Evaluation of protein expression related to three genes, ANPEP, FAM92A1, and STK31, confirmed down-regulation of ANPEP and up-regulation of STK31 in UC-CRC. Conclusions Regulation of transcript expression by DNA methylation involves genes key to colon carcinogenesis and may account for differences in presentation and outcomes between inflammatory bowel disease and sporadic colon cancer.

Prognostic significance of VDR, DKK-1, and DKK-4 expression in colorectal cancer

e15047 Introduction: Inactivation of the vitamin D receptor (VDR) and up-regulation of its down-stream molecules, Dickkopf-1 (DKK-1) and DKK-4 are implicated in the aggressive progression of colorectal adenocarcinomas (CRC). In this study, the expression of these molecules was evaluated in sporadic CRCs, and their expression levels were assessed for correlation with patient prognosis. Methods: By the qRT-PCR, 98 CRCs and matching normal tissues were analyzed for expression of VDR, DKK-1, and DKK-4 at the mRNA level. These levels were normalized to b-actin expression and calculated as ratios of copy numbers. The expression levels were assessed for correlation with clinicopathological features and for their prognostic importance. The survival probabilities were estimated by the Kaplan-Meier method. Results: VDR expression was 1.5 times lower in CRCs (53 of 98, 54%) than in their corresponding normal tissues. Expression of DKK-1 was found in 51 of 98 (52%) of the CRCs and in 29 of 98 (29%) of the normal tissues. Expression of DKK-4 was found in only 14 of 98 (14%) of the CRCs and in none of the normal tissues. VDR expression was 2.0 fold lower in tumors that exhibited metastasis, and poor differentiation and in large tumors ( > 5) cm as compared to tumors without metastasis, well or moderately differentiated tumors and tumors of small size (< 5 cm), respectively. In contrast, increased (3-fold) expression of DKK-1 and DKK-4 was observed in tumors with distant and/or nodal metastases as compared to tumors without such metastases. Expression of DKK-1 was higher in tumors with poor differentiation and in large tumors. There was an inverse relationship between VDR and DKK-4 expression. Survival analyses suggested that CRCs expressing DKK-1 (log rank, P = 0.046) and those with decreased or lack of expression of VDR (log rank, P = 0.043) were associated with poor patient survival. There was, however, no prognostic value for DKK-4 expression (log rank P=0.624). Conclusions: These findings suggest that, for CRCs, increased expression of DKK-1 and reduced or lack of expression of VDR, are associated with aggressiveness and with a poor prognosis for patients. These results provide evidence augmenting the VDR-DKK- pathway may represent a rational therapeutic strategy in colorectal carcinoma. No significant financial relationships to disclose.

Molecular screening for hereditary nonpolyposis colorectal cancer in Bulgaria

Hereditary non-polyposis colorectal cancer (HNPCC) is an autosomal dominant disease, caused by germline mutations in DNA mismatch-repair genes (MMR). These mutations lead to microsatellite instability (MSI). It has been found that the MSI is not confined to the setting of hereditary disease and may be seen in approximately 12-17% of the sporadic CRCs. In 1998 a National Registry for CRC was instituted in Queen Giovanna Hospital, Sofia. A total of 150 patients have been selected for MSI analysis and 25 tumors showed to be unstable, 14 with loss of heterozygosity (LOH). These tumors were further analyzed for MLH1 promoter hypermethylation and a significant association between this epigenetic change and MSI/LOH sporadic cases. We proposed this method as a step that follows the analysis for MSI and prior to the screening for MMR mutations. The mutation screening detected four known and two novel mutations, one unpublished and four known intronic polymorphisms in both hMLH1 and hMSH2 genes. The use of IHC analysis has been found effective in the investigation of some unclear molecular variations.We developed an efficient diagnostic strategy for HNPCC testing and the mutation status of 80% MSI HNPCC cases could be detected.