Methylation is a mechanism we use to switch genes on and off.
By attaching a methyl group to the nucleotide cytosine we silence that gene. Removing the methyl group allows the gene to be transcribed.
Insufficient methylation raises the possbility that oncogenes will remain active leading to an increased risk to cancer. Now, too much methylation may be similarly risky. This is not entirely surprising since we know that methylation may switch off some cancer extinction mechanisms. Whether this actually happended has been debated for a while and now we have some evidence that this is the case.
Some of the genes responsible for carcinogen detoxification (CYP1A1, CYP2A13 and GSTM1) were assessed in patients with head and neck cancer. Compared to healthy normal tissue, the cancer tissues exhibited significant hypermethylation. Hypermethylation was found in the cancer tissues with a frequency of about 39.7%, 27.4%, and 58.1%, respectively, compared to normal healthy tissues with a frequency of about 10.5%, 15.8%, and 20.0%, respectively.
Interestingly, smokers had an even higher methylation status of CYP1A1 and CYP2A13 in these cancer patients.
Takeaway - Folate and B12, amongst others, are methylators and may have disadvantageous effects when used at very high doses. This study also identifies a new mechanism of smoking induced tumours.
Reference
Hypermethylation of carcinogen metabolism genes, CYP1A1, CYP2A13 and GSTM1 genes in head and neck cancer. Sharma R, Panda NK, Khullar M. Oral Dis. 2010 May 30. [Epub ahead of print] http://www3.interscience.wiley.com/journal/123484214/abstract
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What do you feel is the max does b6 b12 betine and folate especially to reduce homocysine levels with increasing cancer risk?