Project description:Microsatellite instability (MSI), caused by defective mismatch repair, is observed in a subset of colorectal cancers (CRCs). We evaluated somatic mutations in microsatellite repeats of genes chosen based on reduced expression in MSI CRC and existence of a coding mononucleotide repeat. Expression profiling of 34 MSI colorectal cancers and 15 normal colonic mucosas was performed in 2002. Comparison of malignant and healthy tissue.
Project description:Genomic instability, including microsatellite instability (MSI) and gross chromosomal abnormalities, has been described in sporadic colorectal cancer (CRC) and MSI has been suggested to have prognostic significance. However, there are few prognostically relevant biomarkers. Here we explore the potential of the analysis of DNA copy number changes at 1Mb resolution to predict survivorship in sporadic CRC. Keywords: Comparative Genomic Hybridization
Project description:Microsatellite instability (MSI), caused by defective mismatch repair, is observed in a subset of colorectal cancers (CRCs). We evaluated somatic mutations in microsatellite repeats of genes chosen based on reduced expression in MSI CRC and existence of a coding mononucleotide repeat.
Project description:A large proportion of indigenous African (IA) colorectal cancer (CRC) patients in South Africa are young (<50years), with no unique histopathological or molecular characteristics. Anatomical site as well as microsatellite instability (MSI) status have shown to be associated with different clinicopathological and molecular features. This study aimed to ascertain key histopathological and miRNA expression patterns in microsatellite stable (MSS) and low-frequency MSI (MSI-L) patients, to provide insight into the mechanism of the disease. This study revealed distinct histopathological features for Left Colon Cancer (LCC), and suggests BAT25/26, miRNAs let-7a-5p and miRNA-125a/b-5p as negative prognostic markers in African CRC patients.
Project description:Colorectal cancer (CRC), a malignant tumor worldwide consists of microsatellite instability (MSI) and microsatellite stable (MSS) phenotypes. Although SHP2 is a potential target for cancer therapy, its relationship with innate immunosuppression remains elusive. To address that, single-cell RNA sequencing was performed to explore the role of SHP2 in all cell types of tumor microenvironment (TME) from murine MC38 xenografts.
Project description:The incidence and mortality of colorectal cancer (CRC) is higher in African Americans (AAs) than in other ethnic groups in the U. S., but reasons for the disparities are unknown. We performed gene expression profiling and microsatellite instability (MSI) analysis of sporadic CRCs from AAs vs. European Americans (EAs) to assess the contribution to CRC disparities. We evaluated gene expression of 43 AA and 43 EA CRC tumors matched by stage and 40 normal colon tissues using the Agilent human whole genome 4x44K cDNA arrays. Gene and pathway analysis were performed using Significance Analysis of Microarrays (SAM), 10-fold Cross Validation (10-fCV) and Ingenuity Pathway Analysis (IPA). MSI analysis was assessed with five NIH Bethesda markers. SAM revealed that 95 genes were differentially expressed between AA and EA patients at a false discovery rate of <5%. A 10f-CV demonstrated that 9 genes were differentially expressed between AA and EA with an accuracy of 97%. Nine genes (CRYBB2, PSPH, ADAL, VSIG10L, C17orf81, ARSE, ANKRD36B, ZNF835, ARHGAP6) were validated and differential expression confirmed by qRT-PCR in independent test set of 21 patients (10 AA, 11 EA). We also analyzed MSI in 57 of the CRC subjects. Overall, 15.8% of CRC patients had MSI, with a higher rate observed in EA (20%) than in AA (12%). MSI distribution by tumor site was 77% right and 23% left colon. Previously, genetic, epigenetic and environmental factors have been implicated in the etiology of CRC. Our results are the first to implicate differential gene expression in CRC disparities and support the existence of distinct tumor microenvironments in these two patients' populations. 126 total samples: 1) 43 white cancer samples; 2) 43 black cancer samples; 3) 27 white control samples; 4) 13 black control samples.
Project description:Background. Colorectal cancer develops through two main genetic instability pathways characterized by distinct pathologic features and clinical outcome. Results. We investigated colon cancer samples (23 characterized by microsatellite stability, MSS, and 16 by high microsatellite instability, MSI-H) for genome-wide expression of microRNA (miRNA) and mRNA. Based on combined miRNA and mRNA gene expression, a molecular signature consisting of twenty seven differentially expressed genes, inclusive of 8 miRNAs, could correctly distinguish MSI-H versus MSS colon cancer samples. Among the differentially expressed miRNAs, various members of the oncogenic miR-17-92 family were significantly up-regulated in MSS cancers. The majority of protein coding genes were also up-regulated in MSS cancers. Their functional classification revealed that they were most frequently associated with cell cycle, DNA replication, recombination, repair, gastrointestinal disease and immune response. Conclusions. This is the first report that indicates the existence of differences in miRNA expression between MSS versus MSI-H colorectal cancers. In addition, the work suggests that the combination of mRNA/miRNA expression signatures may represent a general approach for improving bio-molecular classification of human cancer.
Project description:Synthetic lethality is a powerful approach for targeting oncogenic drivers in cancer. Recent studies revealed that cancer cells with microsatellite instability (MSI) require Werner (WRN) helicase for survival; however, the underlying mechanism remains unclear. In this study, we found that WRN depletion strongly induced p53 and its downstream apoptotic target PUMA in MSI colorectal cancer (CRC) cells. p53 or PUMA deletion abolished apoptosis induced by WRN depletion in MSI CRC cells. Importantly, correction of MSI abrogated the activation of p53/PUMA and cell killing, while induction of MSI led to sensitivity in isogenic CRC cells. Rare p53-mutant MSI CRC cells are resistant to WRN depletion due to lack of PUMA induction, which could be restored by wildtype p53 knock-in or reconstitution. WRN depletion or treatment with the RecQ helicase inhibitor ML216 suppressed in vitro and in vivo growth of MSI CRCs in a p53/PUMA_x0002_dependent manner. ML216 treatment was efficacious in MSI CRC patient-derived xenografts (PDX). Interestingly, p53 gene remains wildtype in the majority of MSI CRCs. These results indicate a critical role of p53/PUMA-mediated apoptosis in the vulnerability of MSI CRCs to WRN loss, and support WRN as a promising therapeutic target in p53-wildtype MSI CRCs.
Project description:Colorectal cancer (CRC) remains the third most common cancer in the US, with 15% of cases displaying Microsatellite Instability (MSI) secondary to Lynch Syndrome (LS) or somatic hypermethylation of the MLH1 promoter. A cohort of rhesus macaques from our institution developed spontaneous mismatch repair deficient (MMRd) CRC with a notable fraction harboring a pathogenic germline mutation in MLH1. DNA methylation and transcriptome analysis was used to evaluate the rhesus macaque as a model organism to study carcinogenesis, develop immunotherapies and vaccines, and implement chemoprevention approaches pertinent to sporadic MSI-H and LS CRC in humans. NIH grant(s): Grant ID: 5 P30 CA016672-44 Grant title: Cancer Center Support Grant Affiliation: The University of Texas MD Anderson Cancer Center Grantor: NCI
Project description:Colorectal cancer (CRC) remains the third most common cancer in the US, with 15% of cases displaying Microsatellite Instability (MSI) secondary to Lynch Syndrome (LS) or somatic hypermethylation of the MLH1 promoter. A cohort of rhesus macaques from our institution developed spontaneous mismatch repair deficient (MMRd) CRC with a notable fraction harboring a pathogenic germline mutation in MLH1. DNA methylation and transcriptome analysis was performed to evaluate the rhesus macaque as a model organism to study carcinogenesis, develop immunotherapies and vaccines, and implement chemoprevention approaches pertinent to sporadic MSI-H and LS CRC in humans. NIH grant(s): Grant ID: 5 P30 CA016672-44 Grant title: Cancer Center Support Grant Affiliation: The University of Texas MD Anderson Cancer Center Grantor: NCI