Dataset Information

Prevalence of alterations in DNA mismatch repair genes in patients with young-onset colorectal cancer.

ABSTRACT:

Background & aims

Direct germline analysis could be used to screen high-risk patients for mutations in DNA mismatch repair genes associated with Lynch Syndrome. We examined the prevalence of mutations in MLH1, MSH2, and MSH6 in a population-based sample of patients with young-onset (age <50 years) colorectal cancer (CRC).

Methods

Young-onset CRC cases were randomly selected from 3 Colon Cancer Family Registry sites. DNA was extracted from peripheral blood leukocytes; MLH1, MSH2, and MSH6 were sequenced, and duplication and deletion analyses was performed for MLH1 and MSH2. Results were reported as deleterious or suspected deleterious, likely neutral, variant of uncertain significance, or no alteration detected. Germline data were compared to Amsterdam II criteria (ACII) and immunohistochemistry results in secondary analyses.

Results

Among 195 subjects, 11 had deleterious/suspected deleterious mutations (5.6%; 95% confidence interval [CI], 2.8%-9.9%), 12 had likely neutral alterations (6.2%; 95% CI, 3.2%-10.5%), 14 had variants of uncertain significance (7.2%; 95% CI, 4.0%-11.8%), 2 had a likely neutral alteration and a variant of uncertain significance (1.0%; 95% CI, 0.1%-3.7%), and 156 had no alteration detected (80.0%; 95% CI, 73.7%-85.4%). Sensitivity, specificity, and positive and negative predictive values for detecting deleterious/suspected deleterious mutations, based on ACII, were 36.4% (4/11), 96.7% (178/184), 40.0% (4/10), and 96.2% (178/185), respectively; based on immunohistochemistry these values were 85.7% (6/7), 91.9% (136/148), 33.3% (6/18), and 99.3% (136/137), respectively.

Conclusions

In a population-based sample of young-onset CRC cases, germline mutations in MLH1, MSH, and/or MSH6 were more prevalent than reported for CRC patients overall. Because only about 5% of young-onset CRC cases had confirmed deleterious or suspected deleterious mutations, further comparative effectiveness research is needed to determine the most appropriate screening strategy for Lynch Syndrome in this high-risk group.

SUBMITTER: Limburg PJ

PROVIDER: S-EPMC3058119 | biostudies-literature | 2011 Jun

REPOSITORIES: biostudies-literature

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Publications

Prevalence of alterations in DNA mismatch repair genes in patients with young-onset colorectal cancer.

Limburg Paul J PJ Harmsen William S WS Chen Helen H HH Gallinger Steven S Haile Robert W RW Baron John A JA Casey Graham G Woods Michael O MO Thibodeau Stephen N SN Lindor Noralane M NM

Clinical gastroenterology and hepatology : the official clinical practice journal of the American Gastroenterological Association 20101105 6

<h4>Background & aims</h4>Direct germline analysis could be used to screen high-risk patients for mutations in DNA mismatch repair genes associated with Lynch Syndrome. We examined the prevalence of mutations in MLH1, MSH2, and MSH6 in a population-based sample of patients with young-onset (age <50 years) colorectal cancer (CRC).<h4>Methods</h4>Young-onset CRC cases were randomly selected from 3 Colon Cancer Family Registry sites. DNA was extracted from peripheral blood leukocytes; MLH1, MSH2, a ...[more]

PMID: 21056691

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Project description:BackgroundColorectal cancers (CRCs) that lack DNA mismatch repair function exhibit the microsatellite unstable (MSI) phenotype and are characterized by the accumulation of frameshift mutations at short repetitive DNA sequences (microsatellites). These tumors recurrently show inactivating frameshift mutations in the tumor suppressor Transforming Growth Factor Beta Receptor Type 2 (TGFBR2) thereby abrogating downstream signaling. How altered TGFBR2 signaling affects exosome-mediated communication between MSI tumor cells and their environment has not been resolved. Here, we report on molecular alterations of exosomes shed by MSI cells and the biological response evoked in recipient cells.MethodsExosomes were isolated and characterized by electron microscopy, nanoparticle tracking, and western blot analysis. TGFBR2-dependent effects on the cargo and functions of exosomes were studied in a MSI CRC model cell line enabling reconstituted and inducible TGFBR2 expression and signaling. Microsatellite frameshift mutations in exosomal and cellular DNA were examined by PCR-based DNA fragment analysis and exosomal protein profiles were identified by mass spectrometry. Uptake of fluorescent-labeled exosomes by hepatoma recipient cells was monitored by confocal microscopy. TGFBR2-dependent exosomal effects on secreted cytokine levels of recipient cells were analyzed by Luminex technology and ELISA.ResultsFrameshift mutation patterns in microsatellite stretches of TGFBR2 and other MSI target genes were found to be reflected in the cargo of MSI CRC-derived exosomes. At the proteome level, reconstituted TGFBR2 expression and signaling uncovered two protein subsets exclusively occurring in exosomes derived from TGFBR2-deficient (14 proteins) or TGFBR2-proficient (five proteins) MSI donor cells. Uptake of these exosomes by recipient cells caused increased secretion (2-6 fold) of specific cytokines (Interleukin-4, Stem Cell Factor, Platelet-derived Growth Factor-B), depending on the TGFBR2 expression status of the tumor cell.ConclusionOur results indicate that the coding MSI phenotype of DNA mismatch repair-deficient CRC cells is maintained in their exosomal DNA. Moreover, we uncovered that a recurrent MSI tumor driver mutation like TGFBR2 can reprogram the protein content of MSI cell-derived exosomes and in turn modulate the cytokine secretion profile of recipient cells. Apart from its diagnostic potential, these TGFBR2-dependent exosomal molecular and proteomic signatures might help to understand the signaling routes used by MSI tumors. Fricke et al. uncovered coding microsatellite instability-associated mutations of colorectal tumor driver genes like TGFBR2 in MSI tumor cellderived exosomes. Depending on the TGFBR2 expression status of their donor cells, shed exosomes show distinct proteomic signatures and promote altered cytokine secretion profiles in recipient cells.

Project description:BackgroundThe landscape of hereditary syndromes and clinicopathologic characteristics among US Latino/Hispanic individuals with colorectal cancer (CRC) remains poorly understood.MethodsA total of 265 patients with CRC who were enrolled in the Hispanic Colorectal Cancer Study were included in the current study. Information regarding CRC risk factors was elicited through interviews, and treatment and survival data were abstracted from clinical charts. Tumor studies and germline genetic testing results were collected from medical records or performed using standard molecular methods.ResultsThe mean age of the patients at the time of diagnosis was 53.7 years (standard deviation, 10.3 years), and 48.3% were female. Overall, 21.2% of patients reported a first-degree or second-degree relative with CRC; 3.4% met Amsterdam I/II criteria. With respect to Bethesda guidelines, 38.5% of patients met at least 1 criterion. Of the 161 individuals who had immunohistochemistry and/or microsatellite instability testing performed, 21 (13.0%) had mismatch repair (MMR)-deficient (dMMR) tumors. dMMR tumors were associated with female sex (61.9%), earlier age at the time of diagnosis (50.4 ± 12.4 years), proximal location (61.9%), and first-degree (23.8%) or second-degree (9.5%) family history of CRC. Among individuals with dMMR tumors, 13 (61.9%) had a germline MMR mutation (MutL homolog 1 [MLH1] in 6 patients; MutS homolog 2 [MSH2] in 4 patients; MutS homolog 6 [MHS6] in 2 patients; and PMS1 homolog 2, mismatch repair system component [PMS2] in 1 patient). The authors identified 2 additional MLH1 mutation carriers by genetic testing who had not received immunohistochemistry/microsatellite instability testing. In total, 5.7% of the entire cohort were confirmed to have Lynch syndrome. In addition, 6 individuals (2.3%) had a polyposis phenotype.ConclusionsThe percentage of dMMR tumors noted among Latino individuals (13%) is similar to estimates in non-Hispanic white individuals. In the current study, the majority of individuals with dMMR tumors were confirmed to have Lynch syndrome. Cancer 2017. © 2017 The Authors. Cancer published by Wiley Periodicals, Inc. on behalf of American Cancer Society. Cancer 2017;123:3732-3743. © 2017 American Cancer Society.

Dataset Information

Prevalence of alterations in DNA mismatch repair genes in patients with young-onset colorectal cancer.

Background & aims

Methods

Results

Conclusions

Publications

Prevalence of alterations in DNA mismatch repair genes in patients with young-onset colorectal cancer.

Similar Datasets

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