(Lily Barghi lbarghi4@students.d125.org)
Thursday, March 28, 2013
Methylation & Cancer
On pages 170-173, Dr. Moalem explains how the methylation of PITX2 can be an indicator of breast cancer recurrence Ninety percent of women who have low methylation of PITX2 are cancer-free after ten years. Only sixty-five percent of women with high methylation of PITX2 were as lucky. Methylation relates to Big Idea 3, living systems store, retrieve, transmit, and respond to information essential to life processes. How does the information regarding PITX2 in the book help scientists treating patients who have had breast cancer? Find two more example from the book regarding methylation of genes that are red flags for cancer and explain how scientist use this information to their advantage. Include hypermethylation, methylation, and epigenetics. Research for one of the examples of how methylation can lead to different remedies besides chemotherapy.
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In Survival of the Sickest, Dr. Moalem discusses the relationship between methylation of the PITX2 gene and breast cancer recurrence; in essence, the lower the methylation rate of PITX2 in cancer patients, the lower the risk of breast cancer recurrence. This information helps scientists treating patients who have had breast cancer, as the doctor would have options of customizing treatments for the patient. For example, when dealing with a patient who has been discovered to have low methylation of PITX2, it may be more beneficial to rely on the body itself to fight off cancer recurrence and prescribe a lower dose of chemotherapy, which has a lesser risk of damaging the patient with harmful radiation. Scientists have identified other relationships between methylation of genes and cancer risks.
ReplyDeleteSmoking has been discovered to lead to hypermethylation of certain genes, which means that massive numbers of methyl markers - much more than regular methylation - can attach to these genes and prevent transcription from occurring. Often, it turns out that these methylated genes are, in fact, cancer-fighting genes; due to their inability to produce regulatory proteins, the body is left vulnerable to lung cancer and prostate cancer. One such gene is the p16 gene, or a tumor-suppressing gene - according to a study by UK scientists (http://www.sciencedaily.com/releases/2010/10/101009082825.htm), women who took up smoking were more than three times as likely to have their p16 gene methylated, leading to a much higher risk of getting cancer.
Another similar example of gene methylation rate correlating with cancer rate is the practice of betel nut chewing in India. Betel nut chewing has been found to lead to hypermethylation of genes that suppress tumors, genes that repair DNA from damages from environmental mutagens or transcription errors, and genes that trigger apoptosis (cell destruction) in cancerous cells. As a result, oral cancer develops much more quickly in betel-chewing Indian men than in others. With clearer identification of relations between an activity and its methyl-related consequence, practices that have a high cancer-risk can be warned against and eliminated, helping to limit cancer rates.
When scientists have identified a relationship between methylation of a particular gene and higher rates of cancer, another approach can be taken: demethylation. In one study, hypermethylation of CpG promoters has been found to inactivate its tumor-suppressing capabilities (http://www.ncbi.nlm.nih.gov/pubmed/15608514). As a result, scientists have been able to develop new drugs such as procaine to target that specific promoter region and demethylate it, allowing the gene to continue its operation in suppressing tumors. Treatments such as these have a huge potential in drastically reducing cancer risks, as well as influence our understanding of how epigenetics work.
(Matthew Zhang mzhang4@students.d125.org)
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