Cancer cells often have abnormal patterns of chromatin modifications. In some cancers, the DNA repair genes MLH1 and BRCA1 are hypermethylated on their promoter regions. Explain how this abnormal methylation pattern could contribute to cancer.
To determine: The way by which the pattern of abnormal methylation pattern could contribute to cancer.
Introduction: DNA methylation is a type of chromatin modification that plays an important role in gene regulation. Cancer cells mostly originate under the influence of mutations in tumour-suppressor genes (proto-oncogenes).
Explanation of Solution
Abnormalities of DNA methylation patterns are the hallmark of cancer. Hypomethylation activates several genes that are usually inactive, including oncogenes. This trigger uncontrolled division of cell.
Hypermethylation occurs in one of many DNA repair genes and facilitates chromatin remodeling, chromosome rearrangements, and changes in the chromosome number. Since the DNA repair system is compromised, the frequency of mutation would increase. The resulting increase in mutations might occur in proto-oncogenes, which is responsible for the origination of cancer.
Thus, both hypomethylation and hypermethylation trigger the uncontrolled cell division, which results in cancer.
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Chapter 17 Solutions
Concepts of Genetics Plus Mastering Genetics with Pearson eText -- Access Card Package (12th Edition) (What's New in Genetics)
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