Related Experiment Videos
DNA mismatch repair gene mutations in human cancer
1Department of Medical Genetics, University of Helsinki, Finland. paivi.peltomaki@helsinki.fi
Abstract:
A new pathogenetic mechanism leading to cancer has been delineated in the past 3 years when human homologues of DNA mismatch repair (MMR) genes have been identified and shown to be involved in various types of cancer. Germline mutations of MMR genes cause susceptibility to a hereditary form of colon cancer, hereditary nonpolyposis colon cancer (HNPCC), which represents one of the most common syndromes associated with cancer predisposition in man. Tumors from HNPCC patients are hypermutable and show length variation at short tandem repeat sequences, a phenomenon referred to as microsatellite instability or replication errors. A similar abnormality is found in a proportion of sporadic tumors of the colorectum as well as a variety of other organs; acquired mutations in MMR genes or other endogenous or exogenous causes may underlie these cases. Genetic and biochemical characterization of the functions of normal and mutated MMR genes elucidates mechanisms of cancer development and provides tools for diagnostic applications.
Insights
DNA mismatch repair (MMR) gene mutations are linked to hereditary nonpolyposis colon cancer (HNPCC) and other cancers. These mutations cause microsatellite instability, a key cancer development mechanism with diagnostic potential.
Area of Science:
- Oncology
- Molecular Biology
- Genetics
Background:
- DNA mismatch repair (MMR) genes are crucial for maintaining genomic stability.
- Defects in MMR genes are implicated in various cancers, particularly hereditary nonpolyposis colon cancer (HNPCC).
- Microsatellite instability (MSI), characterized by length variations in repetitive DNA sequences, is a hallmark of MMR deficiency.
Purpose of the Study:
- To delineate the pathogenetic mechanism of cancer involving DNA mismatch repair (MMR) genes.
- To understand the role of MMR gene mutations in hereditary nonpolyposis colon cancer (HNPCC) and sporadic tumors.
- To explore the diagnostic applications of characterizing MMR gene functions.
Main Methods:
- Identification and characterization of human homologues of DNA mismatch repair (MMR) genes.
- Analysis of germline and acquired mutations in MMR genes.
- Biochemical studies of normal and mutated MMR gene functions.
- Assessment of microsatellite instability (MSI) in tumor samples.
Main Results:
- Human MMR genes have been identified and linked to cancer development.
- Germline mutations in MMR genes predispose individuals to HNPCC, a common hereditary cancer syndrome.
- Tumors from HNPCC patients exhibit hypermutability and microsatellite instability (MSI).
- Similar MSI is observed in sporadic colorectal and other organ tumors, potentially due to acquired MMR gene mutations.
Conclusions:
- DNA mismatch repair (MMR) gene defects represent a significant pathogenetic mechanism in cancer development.
- MMR gene mutations are critical in hereditary nonpolyposis colon cancer (HNPCC) and contribute to sporadic cancers.
- Understanding MMR gene function and mutations offers valuable insights into cancer mechanisms and diagnostic strategies.