Cancer treatment: the critical factors
The family of proteins known as Ras plays a central role in the
regulation of cell growth. It fulfills this fundamental role by
integrating the regulatory signals that govern the cell cycle and
proliferation.
Defects in the Ras-Raf pathway can result in cancerous growth. Mutant
Ras genes were among the first oncogenes identified for their ability to
transform cells to a cancerous phenotype, that is, a cell observably
altered because of distorted gene expression. Mutations in one of three
genes (H, N, or K-Ras) encoding Ras proteins are associated with
upregulated cell proliferation and are found in an estimated 30-40% of
all human cancers. The highest incidences of Ras mutations are found in
cancers of the pancreas (80%), colon (50%), thyroid (50%), lung (40%),
liver (30%), melanoma (30%), and myeloid leukemia (30%) ( Duursma et al.
2003; Minamoto et al. 2000 ; Vachtenheim 1997; Bartram 1988 ; Bos 1989;
Minamoto et al. 2000 ).
According to information in Scientific American, the differences between
oncogenes and normal genes are slight. The mutant protein that an
oncogene ultimately creates may differ from the healthy version by only
a single amino acid, but this subtle variation can radically alter the
protein's functionality.
Researchers at Rutgers University investigated the ability of different
green and black tea polyphenols to inhibit H-Ras oncogenes. The Rutgers
team found that all the major polyphenols contained in green and black
tea except epicatechin showed strong inhibition of cell growth (Chung et
al. 1999). Texas A&M University also found that fish oil decreased
colonic Ras membrane localization and reduced tumor formation in rats.
In view of the central role of oncogenic Ras in the development of colon
cancer, the finding that omega-3 fatty acids modulate Ras activation
likely explains why dietary fish oil protects against colon cancer
(Collett et al. 2001).
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