Phenotype In Colorectal Cancer Research Articles

Infrequently expressed miRNAs in colorectal cancer tissue and tumor molecular phenotype

We have previously shown that commonly expressed miRNAs influenced tumor molecular phenotype in colorectal cancer. We hypothesize that infrequently expressed miRNAs, when showing higher levels of expression, help to define tumor molecular phenotype. In this study, we examine 304 miRNAs expressed in at least 30 individuals, but in <50% of the population and with a mean level of expression above 1.0 relative florescent unit. We examine associations in 1893 individuals who have the tumor molecular phenotype data as well as miRNA expression levels for both carcinoma and normal colorectal tissue. We compare miRNAs uniquely associated with tumor molecular phenotype to the RNAseq data to identify genes associated with these miRNAs. This information is used to further identify unique pathways associated with tumor molecular phenotypes of TP53-mutated, KRAS-mutated, CpG island methylator phenotype and microsatellite instability tumors. Thirty-seven miRNAs were uniquely associated with TP53-mutated tumors; 30 of these miRNAs had higher level of expression in TP53-mutated tumors, while seven had lower levels of expression. Of the 34 miRNAs associated with CpG island methylator phenotype-high tumors, 16 were more likely to have a CpG island methylator phenotype-high tumor and 19 were less likely to be CpG island methylator phenotype-high. For microsatellite instability, 13 of the 22 infrequently expressed miRNAs were significantly less likely to be expressed in microsatellite unstable tumors. KRAS-mutated tumors were not associated with any miRNAs after adjustment for multiple comparisons. Of the dysregulated miRNAs, 17 were more likely to be TP53-mutated tumors while simultaneously being less likely to be CpG island methylator phenotype-high and/or microsatellite instability tumors. Genes regulated by these miRNAs were involved in numerous functions and pathways that influence cancer risk and progression. In summary, some infrequently expressed miRNAs, when expressed at higher levels, appear to have significant biological meaning in terms of tumor molecular phenotype and gene expression profiles.

TrkC promotes colorectal cancer growth and metastasis.

The current work reveals that TrkC receptor is crucial to many aspects of tumorigenicity and metastasis of cancer. However, with only a few exceptions, such as colorectal cancer (CRC), where suppressing tumorigenic and metastatic ability via expression of TrkC as tumor suppressor have been proposed. These diverse lines of evidence led us to investigate whether TrkC is involved in CRC progression. By using mouse models and molecular biology analyses, we demonstrate that TrkC acts as an activator in tumorigenicity and metastasis of colorectal cancer. In this study, TrkC was frequently overexpressed in CRC cells, patients’ tumor samples and an azoxymethane/dextran sulphate sodium-induced mouse model of colitis-associated CRCs. TrkC expression was associated with a high-grade CRC phenotype, leading to significantly poorer survival. Also, TrkC expression promoted the acquisition of motility and invasiveness in CRC. Moreover, TrkC increased the ability to form tumor spheroids, a property associated with cancer stem cells. Importantly, knockdown of TrkC in malignant mouse or human CRC cells inhibited tumor growth and metastasis in a mouse xenograft model. Furthermore, TrkC enhanced metastatic potential and induced proliferation by aberrant gain of AKT activation and suppression of transforming growth factor (TGF)-β signalling. Interestingly, TrkC not only modulated the actions of TGF-β type II receptor, but also attenuated expression of this receptor. These findings reveal an unexpected physiological role of TrkC in the pathogenesis of CRC. Therefore, TrkC is a potential target for designing effective therapeutic strategies for CRC development.

A Specific Mutational Signature Associated with DNA 8-Oxoguanine Persistence in MUTYH-defective Colorectal Cancer

8-Oxoguanine, a common mutagenic DNA lesion, generates G:C>T:A transversions via mispairing with adenine during DNA replication. When operating normally, the MUTYH DNA glycosylase prevents 8-oxoguanine-related mutagenesis by excising the incorporated adenine. Biallelic MUTYH mutations impair this enzymatic function and are associated with colorectal cancer (CRC) in MUTYH-Associated Polyposis (MAP) syndrome. Here, we perform whole-exome sequencing that reveals a modest mutator phenotype in MAP CRCs compared to sporadic CRC stem cell lines or bulk tumours. The excess G:C>T:A transversion mutations in MAP CRCs exhibits a novel mutational signature, termed Signature 36, with a strong sequence dependence. The MUTYH mutational signature reflecting persistent 8-oxoG:A mismatches occurs frequently in the APC, KRAS, PIK3CA, FAT4, TP53, FAT1, AMER1, KDM6A, SMAD4 and SMAD2 genes that are associated with CRC. The occurrence of Signature 36 in other types of human cancer indicates that DNA 8-oxoguanine-related mutations might contribute to the development of cancer in other organs.

Genome-wide methylation analysis identifies a core set of hypermethylated genes in CIMP-H colorectal cancer

BackgroundAberrant DNA methylation profiles are a characteristic of all known cancer types, epitomized by the CpG island methylator phenotype (CIMP) in colorectal cancer (CRC). Hypermethylation has been observed at CpG islands throughout the genome, but it is unclear which factors determine whether an individual island becomes methylated in cancer.MethodsDNA methylation in CRC was analysed using the Illumina HumanMethylation450K array. Differentially methylated loci were identified using Significance Analysis of Microarrays (SAM) and the Wilcoxon Signed Rank (WSR) test. Unsupervised hierarchical clustering was used to identify methylation subtypes in CRC.ResultsIn this study we characterized the DNA methylation profiles of 94 CRC tissues and their matched normal counterparts. Consistent with previous studies, unsupervized hierarchical clustering of genome-wide methylation data identified three subtypes within the tumour samples, designated CIMP-H, CIMP-L and CIMP-N, that showed high, low and very low methylation levels, respectively. Differential methylation between normal and tumour samples was analysed at the individual CpG level, and at the gene level. The distribution of hypermethylation in CIMP-N tumours showed high inter-tumour variability and appeared to be highly stochastic in nature, whereas CIMP-H tumours exhibited consistent hypermethylation at a subset of genes, in addition to a highly variable background of hypermethylated genes. EYA4, TFPI2 and TLX1 were hypermethylated in more than 90% of all tumours examined. One-hundred thirty-two genes were hypermethylated in 100% of CIMP-H tumours studied and these were highly enriched for functions relating to skeletal system development (Bonferroni adjusted p value =2.88E-15), segment specification (adjusted p value =9.62E-11), embryonic development (adjusted p value =1.52E-04), mesoderm development (adjusted p value =1.14E-20), and ectoderm development (adjusted p value =7.94E-16).ConclusionsOur genome-wide characterization of DNA methylation in colorectal cancer has identified 132 genes hypermethylated in 100% of CIMP-H samples. Three genes, EYA4, TLX1 and TFPI2 are hypermethylated in >90% of all tumour samples, regardless of CIMP subtype.

Polymerase proofreading domain mutations: New opportunities for immunotherapy in hypermutated colorectal cancer beyond MMR deficiency.

Immune checkpoint inhibition is a new therapeutic strategy that has shown promising efficacy in many cancer types. Significant activity associated with mismatch repair (MMR) deficiency has been observed in hypermutated, microsatellite unstable (MSI) metastatic colorectal cancer (CRC). Beyond deficient-MMR tumors, somatic or germline DNA polymerase D1 (POLD1) or DNA polymerase E (POLE) alterations cause a hypermutated phenotype in CRC. This recently identified and rare subgroup of proficient-MMR tumors may also benefit from immunotherapy. In this review, we provide a comprehensive overview of recent data on CRC tumors harboring POLD1 or POLE mutations, with a focus on their molecular, histological, and clinical features. We also examine the evidence supporting the development of immune checkpoint inhibitors in this specific subgroup of CRC patients.

Interactions between microsatellite instability and human gut colonization by Escherichia coli in colorectal cancer.

Recent studies suggest that colonization of colonic mucosa by pathogenic Escherichia coli could be involved in the development of colorectal cancer (CRC), especially through the production of genotoxins such as colibactin and/or by interfering with the DNA mismatch repair (MMR) pathway that leads to microsatellite instability (MSI). The present study, performed on 88 CRC patients, revealed a significant increase in E. coli colonization in the MSI CRC phenotype. In the same way, E. coli persistence and internalization were increased invitro in MMR-deficient cells. Moreover, we demonstrated that colibactin-producing E. coli induce inhibition of the mutL homologue 1 (MLH1) MMR proteins, which could lead to genomic instability. However, colibactin-producing E. coli were more frequently identified in microsatellite stable (MSS) CRC. The present study suggests differences in the involvement of colibactin-producing E. coli in colorectal carcinogenesis according to the CRC phenotype. Further host-pathogen interactions studies should take into account CRC phenotypes.

Overexpression of miR-10b in colorectal cancer patients: Correlation with TWIST-1 and E-cadherin expression.

MicroRNAs are emergent players of epigenetics that function as oncogenes or tumor suppressors and that have been implicated in regulating diverse cellular pathways. MiR-10b is an oncogenic microRNA involved in tumor invasion and metastasis in various cancers. Our data have shown that miR-10b is overexpressed in colorectal cancer samples in comparison with non-tumorous adjacent mucosa (p = 0.0025) and that it is associated with severe features such as tumor size >5 cm (p = 0.023), distant metastasis (p = 0.0022), non-differentiated tumors (p = 0.016), and vascular invasion (p = 0.01). Regarding the regulation of its expression, positive correlation between the loss of miR-10b and aberrant DNA methylation (p = 0.02) as well as a loss of TWIST-1 messenger RNA (p = 0.018) have been observed. Furthermore, expression analysis of the downstream miR-10b targets has shown that there are associations between low HOXD10 messenger RNA and E-cadherin protein levels (p < 0.0001, p = 0.0008, respectively) and overexpression of miR-10b. Our data suggests that overexpression of miR-10b results from high levels of TWIST-1 and may induce a decrease of E-cadherin membranous protein levels, thus contributing to the acquisition of metastatic phenotypes in colorectal cancer.

POLE and POLD1 screening in 155 patients with multiple polyps and early-onset colorectal cancer.

Germline mutations in POLE and POLD1 have been shown to cause predisposition to colorectal multiple polyposis and a wide range of neoplasms, early-onset colorectal cancer being the most prevalent. In order to find additional mutations affecting the proofreading activity of these polymerases, we sequenced its exonuclease domain in 155 patients with multiple polyps or an early-onset colorectal cancer phenotype without alterations in the known hereditary colorectal cancer genes. Interestingly, none of the previously reported mutations in POLE and POLD1 were found. On the other hand, among the genetic variants detected, only two of them stood out as putative pathogenic in the POLE gene, c.1359 + 46del71 and c.1420G > A (p.Val474Ile). The first variant, detected in two families, was not proven to alter correct RNA splicing. Contrarily, c.1420G > A (p.Val474Ile) was detected in one early-onset colorectal cancer patient and located right next to the exonuclease domain. The pathogenicity of this change was suggested by its rarity and bioinformatics predictions, and it was further indicated by functional assays in Schizosaccharomyces pombe. This is the first study to functionally analyze a POLE genetic variant outside the exonuclease domain and widens the spectrum of genetic changes in this DNA polymerase that could lead to colorectal cancer predisposition.

The suppressing effects of BTG3 expression on aggressive behaviors and phenotypes of colorectal cancer: An in vitro and vivo study.

Here, we found that down-regulated expression of BTG3 might be positively correlated with colorectal carcinogenesis and its overexpression suppressed proliferation, glycolysis, mitochondrial respiration, cell cycle progression, migration, and invasion, and induced apoptosis, senescence and differentiation in SW480 and SW620 cells. After treated with cisplatin, MG132, paclitaxel and SAHA, BTG3 transfectants exhibited lower viability and higher apoptosis than the control in both time- and dose-dependent manners. BTG3 overexpression up- regulated the protein expression of Cyclin E, p16, p27, NF-κB, p38α/β, XIAP, Bcl-2, ATG14 and p53, but down-regulated the mRNA expression of MRP1, BCRP, and mTOR in SW480 and SW620 cells. BTG3 overexpression inhibited tumor growth of SW620 cells by suppressing proliferation and inducing apoptosis. It was suggested that down-regulated BTG3 expression might be considered as a marker for colorectal carcinogenesis. BTG3 overexpression might reverse the aggressive phenotypes and be employed as a potential target for gene therapy of colorectal cancer.

The role of MRP1 in the multidrug resistance of colorectal cancer.

The role of multidrug resistance associated protein 1 (MRP1) in the multidrug resistance (MDR) of colorectal cancer (CRC) remains unclear. The present study aimed to investigate the effect of MRP1 in MDR CRC and its therapeutic potential for the treatment of patients with this disease. The human MDR CRC cell lines HCT-8 and Colo205 were established through stable exposure to 5-florouracil (5-FU) over a 5-month period. MRP1 was knocked-down in MDR CRC cells through the transfection of short hairpin RNA targeting MRP1 (shMRP1). Western blotting was performed to assess the efficiency of this silencing. MTT and apoptosis assays were conducted to detect cell viability and apoptosis, respectively. Compared with their parental cells, HCT-8/5-FU and Colo205/5-FU cells were 23.1 and 15.8 times more resistant to 5-FU, and 17.2 and 20.9 times more resistant oxaliplatin, respectively. The knockdown of MRP1 resulted in the attenuation of the MDR phenotype through the induction of apoptosis. The shMRP1-transfected Colo205/5-FU cells were injected subcutaneously into the right scapular region of BALB/c nude mice and tumor size was measured for 15 days post-injection. This in vivo experiment demonstrated that MRP1 knockdown inhibited tumor growth. On the 9, 12 and 15th day post-injection, tumor volume in the shMRP1-transfected Colo205/5-FU cell-injected group was significantly lower compared with that in the Colo205/5-FU cell-injected group (day 9, 2.1±0.8 vs. 6.9±1.9 mm3, P=0.009; day 12, 3.1±1.4 vs. 14.3±4.0 mm3, P=0.008; day 15, 4.8±2.7 vs. 21.3±3.4 mm3; all P<0.001). These results demonstrate that MRP1 serves a role in the MDR phenotype of CRC through inhibiting apoptosis and may serve as a potential therapeutic target for inhibition, which would increase the efficacy of other chemotherapeutic agents in the treatment of CRC.

Identification of Predictive DNA Methylation Biomarkers for Chemotherapy Response in Colorectal Cancer.

Resistance to 5-Fluorouracil (5-FU) is a major obstacle to the successful treatment of colorectal cancer (CRC) and posed an increased risk of recurrence. DNA methylation has been suggested as one of the underlying mechanisms for recurrent disease and its contribution to the development of drug resistance remains to be clarified. This study aimed to determine the methylation phenotype in CRC for identification of predictive markers for chemotherapy response. We performed DNA methylation profiling on 43 non-recurrent and five recurrent CRC patients using the Illumina Infinium HumanMethylation450 Beadchip assay. In addition, CRC cells with different genetic backgrounds, response to 5-FU and global methylation levels (HT29 and SW48) were treated with 5-FU and DNA methylation inhibitor 5-aza-2′-deoxycytidine (5-azadC). The singular and combined effects of these two drug classes on cell viability and global methylation profiles were investigated. Our genome-wide methylation study on the clinical specimens showed that recurrent CRCs exhibited higher methylation levels compared to non-recurrent CRCs. We identified 4787 significantly differentially methylated genes (P < 0.05); 3112 genes were hyper- while 1675 genes were hypomethylated in the recurrent group compared to the non-recurrent. Fifty eight and 47 of the significantly hypermethylated and hypomethylated genes have an absolute recurrent/non-recurrent methylation difference of ≥20%. Most of the hypermethylated genes were involved in the MAPK signaling pathway which is a key regulator for apoptosis while the hypomethylated genes were involved in the PI3K-AKT signaling pathway and proliferation process. We also demonstrate that 5-azadC treatment enhanced response to 5-FU which resulted in significant growth inhibition compared to 5-FU alone in hypermethylated cell lines SW48. In conclusion, we found the evidence of five potentially biologically important genes in recurrent CRCs that could possibly serve as a new potential therapeutic targets for patients with chemoresistance. We postulate that aberrant methylation of CCNEI, CCNDBP1, PON3, DDX43, and CHL1 in CRC might be associated with the recurrence of CRC and 5-azadC-mediated restoration of 5-FU sensitivity is mediated at least in part by MAPK signaling pathway.

Metabolic Phenotype and Risk of Colorectal Cancer in Normal-Weight Postmenopausal Women.

The prevalence of metabolically unhealthy phenotype in normal-weight adults is 30%, and few studies have explored the association between metabolic phenotype and colorectal cancer incidence in normal-weight individuals. Our aim was to compare the risk of colorectal cancer in normal-weight postmenopausal women who were characterized by either the metabolically healthy phenotype or the metabolically unhealthy phenotype. A large prospective cohort, the Women's Health Initiative, was used. The analytic sample included 5,068 postmenopausal women with BMI 18.5 to <25 kg/m2 Metabolic phenotype was defined using the Adult Treatment Panel-III definition, excluding waist circumference; therefore, women with one or none of the four components (elevated triglycerides, low high-density lipoprotein cholesterol, elevated blood pressure, and elevated fasting glucose) were classified as metabolically healthy. Multivariable Cox proportional hazards regression was used to estimate adjusted HRs for the association between metabolic phenotype and risk of colorectal cancer. Among normal-weight women, those who were metabolically unhealthy had higher risks of colorectal cancer (HR, 1.49; 95% CI, 1.02-2.18) compared with those who were metabolically healthy. A metabolically unhealthy phenotype was associated with higher risk of colorectal cancer among normal-weight women. Normal-weight women should still be evaluated for metabolic health and appropriate steps taken to reduce their risk of colorectal cancer. Cancer Epidemiol Biomarkers Prev; 26(2); 155-61. ©2017 AACR.

Abstract PR03: The pig as a model for colorectal cancer

Abstract Colorectal cancer is the fourth most common cancer worldwide with a mortality of more than 50%. Contrary to the increasing advances in cancer research colorectal cancer deaths are increasing in number. Most animal models also for colorectal cancer are in rodents. However, mice differ significantly in size, lifespan, physiology, anatomy and diet. Furthermore, genetically engineered mouse models for colorectal cancer show polyp development in the small intestine, contrary to the human phenotype that develops polyps in the large intestine. Therefore, a more suitable animal model is necessary. Pigs are increasingly recognized as a valuable model facilitating diagnostic and therapeutic strategies at human scale, longitudinal studies of disease initiation, progression and treatment response in preclinical trials. We generated gene targeted cloned pigs carrying the nonsense mutation, APC1311 that is orthologous to a human mutation associated with a very severe phenotype of colorectal cancer and the inherited condition familial adenomatous polyposis (FAP). In pigs the APC1311 mutation results in multiple adenomatous polyps in the colon and rectum that, so far, have progressed to carcinoma in situ. Histological and molecular analysis show that the porcine model recapitulates all major features of early stage human FAP. Breeding and analysis of the mutant pig herd has revealed segregation of traits that affect polyposis severity in animals carrying the same APC1311 mutation. We are currently investigating the genetic basis for this effect by comparing normal mucosa samples from low and high polyp animals and have discovered some genes that are differentially expressed. A progression study comparing low-grade with high-grade adenomas also identified differentially expressed genes and miRNAs. Further improvements of this model are targeted at generating organ/tissue specific Cre pigs to activate latent mutations such as KRAS and TP53 mutations in the colon. Additionally to encourage cancer progression we are working on the introduction of ubiquitous Cas9 expression in our APC1311 pigs to allow the activation of oncogenic pathways locally in vivo. Our porcine model provides a powerful new resource for preclinical cancer research, including identifying and investigating novel biomarkers for early detection. This abstract is also being presented as Poster A20. Citation Format: Carolin Wander, Tatiana Flisikowska, Krzysztof Flisikowski, Érica Schulze, Hans-Rudolf Fries, Stefan Bauersachs, Alexander Kind, Angelika Schnieke. The pig as a model for colorectal cancer. [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 PR03.

Overexpression of Rad51 Predicts Poor Prognosis in Colorectal Cancer: Our Experience with 54 Patients.

BackgroundAberrant Rad51 expression is implicated in the progression of human malignancies. However, the role of Rad51 in colorectal cancer (CRC) remains undefined. This study aimed to establish a relationship between Rad51 and clinicopathologic features of CRC.MethodsWe retrospectively examined the paraffin-embedded tissue samples obtained from 54 patients with CRC who had received surgical therapies at our institution during 2006–2008. Rad51 expression in adenocarcinoma, paracancerous tissue, and normal colonic tissue was determined by immunohistochemistry. The correlation between Rad51 immunoreactivity and clinicopathologic features of these patients was evaluated.ResultsRad51 immunoreactivity was detected in 67% of adenocarcinoma, 48% of paracancerous tissue, and 27% of normal colonic mucosa. Rad51 expression in adenocarcinoma was significantly higher than normal colonic tissue (p < 0.05). Rad51 was also overexpressed in poorly differentiated tumors and tumor samples from patients with lymph node metastasis (p < 0.05). Patients with Rad51 overexpression had a 69% two-year survival, 49% three-year survival, and 16% five-year survival, considerably worse than patients with negative Rad51 expression (p < 0.05).ConclusionOur data suggest that Rad51 overexpression is correlated with malignant phenotypes of CRC and may predict poor prognosis for these patients.

Circulating tumor microemboli (CTM) and vimentin+ circulating tumor cells (CTCs) detected by a size-based platform predict worse prognosis in advanced colorectal cancer patients during chemotherapy

BackgroundCirculating tumor cells (CTCs) detected in peripheral blood (PB) of cancer patients can be identified as isolated CTCs and circulating tumor microemboli (CTM). This study aimed to evaluate the prognostic value of CTM detection and CTC phenotype in advanced colorectal cancer (CRC) patients during chemotherapy.MethodsA size-based platform for CTC isolation was applied. PB samples (5 ml) from 98 advanced CRC patients during 2–6 cycles chemotherapy were collected for CTC detection, and CTC count was correlated to patient’s clinicopathological characteristics and clinical outcome. And CTC phenotype was measured by immunofluorescent staining and evaluate the predictive significance on survival in 32 CTCs-positive patients with advanced CRC.ResultsForty-eight of 98 patients were CTCs-positive, including 18 CTM-positive patients, and CTC detection was positively correlated with lymphatic invasion (P = 0.049), TNM stage (P = 0.023), and serum CEA level (P = 0.014). Moreover, Kaplan–Meier survival and Cox regression analyses revealed that the presence of CTCs was an independent factor for poor PFS and OS (P < 0.05) in advanced CRC patients during chemotherapy, and CTM-positive patients had shooter survival than isolated CTCs-positive patients (P < 0.05). Furthermore, patients with vimentin+ isolated CTCs/CTM had shorter PFS and OS compared with CK+ CTCs (P < 0.05).ConclusionsThis study provided evidence that the presence of CTCs was positively correlated with poor prognosis, and furthermore, CTM and vimentin+ CTCs predicted poorer survival, which indicated that CTM and vimentin+ CTCs detected by a sensitive platform could be used to improve prognostic value of CTCs in advanced CRC patients under treatment.

Subcellular proteomics analysis of different stages of colorectal cancer cell lines.

Studying cell differentiation and transformation allows a better understanding of the mechanisms involved in the initiation and the evolution of cancer. The role of proteins which participate in these processes is dependent on their location within the cell. Determining the subcellular localization of proteins or the changes in localization is, therefore, paramount in elucidating their role. Using quantitative mass spectrometry, we characterized the protein expression and subcellular localization of nearly 5000 proteins from seven different colorectal cancer (CRC) cell lines, as well as normal colon fibroblasts and intestinal epithelial cells. This cellular characterization allowed the identification of colon cancer-associated proteins with differential expression patterns as well as deregulated protein networks and pathways. Indeed, our results demonstrate differential expression of proteins involved in cell adhesion, cytoskeleton, and transcription in colon cancer cells compared to normal colon-derived cells. Pathway analyses identified different cellular functions, including endocytosis and eIF2 signaling, whose deregulation correlates with mutations found in the different CRC phenotypes. Our results provide an unbiased, quantitative and high-throughput approach to measure changes in protein expression and subcellular protein locations in different CRC cell lines.

LGR5 and CD133 as prognostic and predictive markers for fluoropyrimidine-based adjuvant chemotherapy in colorectal cancer

Background: Expression of leucine-rich-repeat-containing G-protein-coupled receptor 5 (LGR5) gene is associated with a metastatic phenotype and poor prognosis in colorectal cancer (CRC). CD133 expression is a putative cancer stem cell marker and a proposed prognostic marker in CRC, whereas the predictive value of CD133 expression for effect of adjuvant chemotherapy in CRC is unclear.Material and methods: For the study of LGR5 mRNA and CD133 expression, tissue microarrays from 409 primary CRC stage II and III tumors, where patients had been randomized to adjuvant chemotherapy or surgery only, were available. LGR5 mRNA and CD133 expression were assessed by in situ hybridization (ISH) and immunohistochemistry (IHC), respectively. LGR5 mRNA and CD133 expression as prognostic and predictive markers were evaluated by univariate and multivariate analyses.Results: For all CRC patients, positive LGR5 mRNA and CD133 expression were associated with classic adenocarcinoma histology type (p = 0.001 and p = 0.014, respectively). Positive LGR5 mRNA expression was also associated with smaller tumor diameter for CRC stage II (p = 0.005), but not for CRC stage III (p = 0.054). For CRC stage II, lack of LGR5 mRNA expression was associated with longer time to recurrence (TTR) in Kaplan-Meier (p = 0.045) and in multivariate Cox analysis (HR 0.27, 95% CI 0.08–0.95, p = 0.041). For colon cancer stage III patients, lack of CD133 expression was associated with better effect of adjuvant chemotherapy (p = 0.016) in Kaplan-Meier univariate analysis, but the interaction between CD133 and adjuvant chemotherapy was not statistically significant in multivariate analysis (HR 0.59, 95% CI 0.18–1.89, p = 0.374).Conclusion: LGR5 mRNA expression is a prognostic factor for CRC stage II patients, whereas the value of CD133 expression as prognostic and predictive biomarker is inconclusive.

Abstract 4135: A signature of rejection in colorectal cancer: immune markers and their epigenetic regulation

Abstract Background The immune system plays a pivotal role in the development and progression of colorectal cancer (CRC). Tumor immune rejection has been previously linked to activation of the interferon stimulated genes (ISG) pathway including STAT1, IRF5 and IRF1. Here, we tested the associations of ISG pathway genes with cytotoxic T cell (CTL) infiltration, granzymeB and perforin secretion, tumor expression of intercellular adhesion molecule 1 (ICAM-1), and clinicopathological factors. Further, we investigated the poorly understood regulation of STAT1 and IRF1 by miR-34a and miR-93 using sequential in situ hybridization (ISH) /immunohistochemistry and digital image analysis. Methods Resection specimens from 244 CRC patients with full clinicopathological data were included in this study. ngTMA (next generation tissue microarray) slides containing 8 punches of tumor and normal tissue from each case were immunostained for proteins of interest. The expression of the miRNAs was visualized on consecutive slides by ISH. Precise correlation analysis of miRNA expression and the target proteins was performed using digital image analysis. Results Active interferon signaling in the tumor microenvironment negatively correlated with the presence of distant metastasis (STAT1: p = 0.013, OR = 0.98, 95%CI = 0.96-0.99; IRF1: p = 0.014, OR = 0.96, 95%CI = 0.940.99; IRF5: p = 0.009, OR = 0.96, HR = 0.93-0.99). High miR-34a and miR-93 expression corresponded to a 22.5 fold decrease of STAT1 and IRF1 (p = 0.006, OR = 0.39, 95%CI = 0.20-0.77; p = 0.058, OR: 0.48 95%CI = 0.231.02). Finally, a combined score was generated from the three protein markers, representing an immune activated and a “quiescent” phenotype. The activated phenotype was associated with elevated CD8+ CTL infiltration (p = 0.007, HR = 2.07, 95%CI = 1.22-3.52), an increase in granzymeB (p&amp;lt;0.001, HR = 3.22, 95%CI = 1.70-6.08), perforin (p = 0.020, OR = 1.90, 95%CI = 1.10-3.26) and ICAM-1 expression (p = 0.006, OR = 0.2.17, 95%CI = 1.263.85). Patients with immune activated CRC had a considerably reduced risk of developing distant metastases (p = 0.001, OR = 0.034, 95%CI = 0.006-0.183). Conclusion Here, we describe a combined marker phenotype that can help to differentiate between patients with an activated and “quiescent” immune phenotype of CRC. The score is based on a quantitative assessment of STAT1, IRF1 and IRF5 expression by digital image analysis. Increased tumor infiltrating CTLs, granzymeB, perforin and tumor ICAM-1 expression, as well as a lower risk of distant metastases characterize the immune activated phenotype. Targeted inhibition of miR34a and miR-93 may be a promising strategy to activate the anti-tumoral immune response and will be validated in future experimental studies. Citation Format: Lena Sokol, Viktor H. Koelzer, Stefan P. Zahnd, Lucine Christe, Inti Zlobec, Alessandro Lugli. A signature of rejection in colorectal cancer: immune markers and their epigenetic regulation. [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 4135.

MicroRNA-103 promotes tumor growth and metastasis in colorectal cancer by directly targeting LATS2.

Colorectal cancer (CRC) has become the third most common cancer worldwide and leads to a high mortality rate. Although colorectal cancer has been studied widely, the underlying molecular mechanism remains unclear. Increasing evidence shows that the abnormal expression of microRNAs (miRNAs) is involved in tumorigenesis. Previous studies have reported that miRNA-103 (miR-103) is dysregulated in CRC; however, the expression, function and mechanism of miR-103 in CRC are not well known. The present study showed that miR-103 was overexpressed in the primary tumor tissues of patients with CRC and was significantly associated with a more aggressive phenotype of CRC in patients. Survival rate analysis demonstrated that CRC patients with high miR-103 expression had a poorer overall survival compared with CRC patients with low miR-103 expression. In CRC cell lines, miR-103 inhibition significantly decreased the proliferation, invasion and migration of the cells in vitro. Furthermore, miR-103 repressed large tumor suppressor kinase 2 (LATS2) expression by directly binding to the LATS2-3'-untranslated region, and an inverse correlation was identified between the expression of miR-103 and LATS2 messenger RNA in primary CRC tissues. In addition, the restoration of LATS2 led to suppressed proliferation, invasion and migration of CRC cells. In vivo, miR-103 promotes tumor growth in nude mice. In summary, miR-103 performs a critical role in the promotion of the invasive and metastatic capacities of CRC, possibly by directly targeting LATS2. This miRNA may be involved in the development and progression of CRC.

Adverse prognostic impact of the CpG island methylator phenotype in metastatic colorectal cancer.

Background:The association between the CpG island methylator phenotype (CIMP) and clinical outcomes in metastatic colorectal cancer remains unclear. We investigated the prognostic impact of CIMP in patients with metastatic colorectal cancer treated with systemic chemotherapy.Methods:Eight CIMP-specific promoters (CACNA1G, IGF2, NEUROG1, RUNX3, SOCS1, CDKN2A, CRABP1, and MLH1) were examined. The CIMP status was determined by the number of methylated promoters as high (⩾5), low (1–4), and negative (0).Results:A total of 153 patients were included (men/women, 103/50; median age, 61 years; range, 22–80 years). The CIMP status was negative/low/high in 77/ 69/7 patients, respectively. Overall survival (OS) was significantly different among the three CIMP groups, with median values of 35.7, 22.2, and 9.77 months for the negative, low, and high groups, respectively (P<0.001). For patients treated with fluoropyrimidine and oxaliplatin first-line chemotherapy (N=128), OS and progression-free survival (PFS) were significantly different among the three CIMP groups; the median OS was 37.9, 23.8, and 6.77 months for the negative, low, and high groups, respectively (P<0.001), while the median PFS was 9.97, 7.87, and 1.83 months, respectively (P=0.002). Response rates were marginally different among the three CIMP groups (53.4% vs 45.1% vs 16.7%, respectively; P=0.107). For patients treated with fluoropyrimidine and irinotecan second-line chemotherapy (N=86), only OS showed a difference according to the CIMP status, with median values of 20.4, 13.4, and 2.90 months for the negative, low, and high groups, respectively (P<0.001).Conclusions:The CIMP status is a negative prognostic factor for patients with metastatic colorectal cancer treated with chemotherapy.