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Lack of APC somatic mutation is associated with early-onset colorectal cancer in African Americans.

ABSTRACT: African Americans (AAs) have higher incidence and mortality rates of colorectal cancer (CRC) compared with other US populations. They present with more right-sided, microsatellite stable disease and are diagnosed at earlier ages compared with non-Hispanic Whites (NHWs). To gain insight into these trends, we conducted exome sequencing (n = 45), copy number (n = 33) and methylation analysis (n = 11) of microsatellite stable AA CRCs. Results were compared with data from The Cancer Genome Atlas (TCGA). Two of the 45 tumors contained POLE mutations. In the remaining 43 tumors, only 27 (63%) contained loss-of-function mutations in APC compared with 80% of TCGA NHW CRCs. APC-mutation-negative CRCs were associated with an earlier onset of CRC (P = 0.01). They were also associated with lower overall mutation burden, fewer copy number variants and a DNA methylation signature that was distinct from the CpG island methylator phenotype characterized in microsatellite unstable disease. Three of the APC-mutation-negative CRCs had loss-of-function mutations in BCL9L. Mutations in driver genes identified by TCGA exome analysis were less frequent in AA CRC cases than TCGA NHWs. Genes that regulate the WNT signaling pathway, including SOX9, GATA6, TET1, GLIS1 and FAT1, were differentially hypermethylated in APC-mutation-negative CRCs, suggesting a novel mechanism for cancer development in these tumors. In summary, we have identified a subtype of CRC that is associated with younger age of diagnosis, lack of APC mutation, microsatellite and chromosome stability, lower mutation burden and distinctive methylation changes.

SUBMITTER: Xicola RM

PROVIDER: S-EPMC6292413 | biostudies-literature | 2018 Dec

REPOSITORIES: biostudies-literature

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Lack of APC somatic mutation is associated with early-onset colorectal cancer in African Americans.

Xicola Rosa M RM Manojlovic Zarko Z Augustus Gaius J GJ Kupfer Sonia S SS Emmadi Rajyasree R Alagiozian-Angelova Victoria V Triche Tim T Salhia Bodour B Carpten John J Llor Xavier X Ellis Nathan A NA

Carcinogenesis 20181201 11

African Americans (AAs) have higher incidence and mortality rates of colorectal cancer (CRC) compared with other US populations. They present with more right-sided, microsatellite stable disease and are diagnosed at earlier ages compared with non-Hispanic Whites (NHWs). To gain insight into these trends, we conducted exome sequencing (n = 45), copy number (n = 33) and methylation analysis (n = 11) of microsatellite stable AA CRCs. Results were compared with data from The Cancer Genome Atlas (TCG ...[more]

PMID: 30239619

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Project description:Background: Colorectal cancer (CRC) incidence is rising worldwide, as well as in the Republic of Kazakhstan, while its occurrence is also increasing in the younger population. Hereditary forms associated with the development of colon and rectal cancer and early-onset CRC have never been studied in the population of Kazakhstan. The aim of this research was to investigate the spectrum of CRC-related gene mutations to determine which mutations cause early onset of CRC in the Kazakhstan population. Methods: The study included 125 unrelated patients from Kazakhstan (range 17-50 years in age) with early onset CRC. Genomic DNA was obtained from peripheral blood of the patients. Next-generation sequencing was performed using the TruSightCancer Kit on the MiSeq platform. The Studio Variant was used to annotate and interpret genetic variants. Results: Bioinformatics analysis of Next-generation sequencing data revealed 11,152 variants from 85 genes, of them, 3,790 missense, 6,254 synonymous variants, 44 3'UTR variants, 10 frameshift variants, five stop-gain variants, four in-frame deletions, two splice donors, one splice acceptor variant, and 1,042 intron or non-coding variants. APC, BRCA2/1, ALK, BRIP1, EGFR, FANCA, FANCD2, FANCI, HNF1A, MEN1, NSD1, PMS2, RECQL4, RET, SLX4, WRN, and XPC genes mutated most often. According to the ACMG guidelines and LOVD/ClinVar databases, 24 variants were pathogenic (10 frameshifts, five missenses, five stop-gain, one in-frame deletion, and three splice-site mutations), and 289 were VUS with population frequency <1%, 131 of them were attributed as deleterious. In the study, 50% of all pathogenic mutations found in Kazakhstani patients with early CRC onset were identified in the subgroups with a family history of CRC and primary multiple tumors. In APC, pathogenic mutations were most often (21%). Conclusion: Pathogenic and likely pathogenic mutations were found in 20 (16%) out of 125 patients. Eight novel pathogenic mutations detected in FANCI, APC, BMPR1, ATM, and DICER1 genes have not been reported in previous literature. Given the high frequency and wide spectrum of mutations, NGS analysis must be carried out in families with a history of CRC/CRC-related cancers with the purpose to identify cause-effective mutations, clarify the clinical diagnosis, and prevent the development of the disease in other family members.

Project description:Background & aimsThe incidence of colorectal cancer (CRC) is increasing in individuals younger than 50 years, who do not usually undergo screening if they are of average risk. We sought to identify risk factors for CRC in this population.MethodsWe compared sociodemographic and medical characteristics of patients who received a diagnosis of CRC at an age of 18-49 years (early-onset) with patients who received a diagnosis of CRC at an age of 50 years or older (late-onset) and with age-matched, cancer-free individuals (controls) at a tertiary academic hospital. We collected data from all adult patients with a diagnosis of CRC from January 1, 2011 through April 3, 2017 from electronic health records. Associations with risk factors were assessed using univariable and multivariable logistic regression models.ResultsWe identified 269 patients with early-onset CRC, 2802 with late-onset CRC, and 1122 controls. Compared with controls, patients with early-onset CRC were more likely to be male (odds ratio [OR], 1.87; 95% CI, 1.39-2.51), have inflammatory bowel disease (IBD) (3% vs 0.4% for controls; univariable P < .01), and have a family history of CRC (OR, 8.61; CI, 4.83-15.75). Prevalence values of well-established modifiable CRC risk factors, including obesity, smoking, and diabetes, were similar. Compared to patients with late-onset CRC, patients with early-onset CRC were more likely to be male (OR, 1.44; 95% CI, 1.11-1.87), black (OR, 1.73; 95% CI, 1.08-2.65) or Asian (OR, 2.60; 95% CI, 1.57-4.15), and have IBD (OR, 2.97; 95% CI, 1.16-6.63) or a family history of CRC (OR, 2.87; 95% CI, 1.89-4.25). Sensitivity analyses excluding IBD and family history of CRC showed comparable results. Early-onset CRC was more likely than late-onset disease to be detected in the left colon or rectum (75% vs 59%, P = .02) and at a late stage of tumor development (77% vs 62%, P = .01).ConclusionsIn a retrospective study of patients with early-onset CRC vs late-onset CRC or no cancer, we identified non-modifiable risk factors, including sex, race, IBD, and family history of CRC, to be associated with early-onset CRC.

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Lack of APC somatic mutation is associated with early-onset colorectal cancer in African Americans.

Publications

Lack of APC somatic mutation is associated with early-onset colorectal cancer in African Americans.

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