Introduction to Epigenetics In Cancer:
Cancer development depends on the survival and
multiplication of genetically transformed /altered cells. Genetic
transformation alone does not lead to cancer since the epigenetic or external controls
on the expression of the genome also need to be lost or modified for the
development of cancer. This second line
of control consists of a set of chemicals outside the DNA that control the
expression of various parts of the DNA by acting like on-off switches.
Epigenetic factors and processes are thus additional points at which the
regulatory function may fail, leading to cancer development. Consequently they
also provide additional opportunities in oncology for treatment by targeting
processes that lead to cancer development.
Various epigenetic changes have been found in
cancer cells. Most common are DNA methylation and histone modification, which alter
the expression of specific parts of the genome by inactivating the cancer
suppressor genes and activating oncogenes.
Chromatin remodeling and MicroRNA variations lead to faulty and
excessive coding of oncogenes and noncoding of tumor suppressor genes.
The current knowledge on the role of the
epigenome on cancer development can be used in screening, diagnosis, treatment
planning and prognostication of cancers. Changes linked with specific tumor
types can be used for screening. Epigenetic changes known to occur early in the
disease course can be used for early diagnosis of the primary tumor and identification
of tumor recurrence. More specific typing of cancers by finding the different
subtypes can lead to targeted therapies with
reduced side- effects. On the other hand, some treatment modalities may
be unified across various cancer types which show the same epigenetic changes
thus reducing development costs and approval time.
References:
- Brait M, Sidransky D. cancer epigenetics: above and beyond. Toxicol Mech Methods. 2011 May;21(4):275-88. doi: 10.3109/15376516.2011.56267
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J Lopez, M Percharde, HM Coley, A Webb and T
Crook. The context and potential of epigenetics in oncology. British Journal of
Cancer. 2009, 100(4), 571 – 577
