Genetic mosaicism and Cancer: cause and effect

Significance

Extensive research has been conducted over the last hundred years in order to understand cancer pathology. Theories and experiments have shown that the genomes of cells, that is normal cells and cancer cells are usually subjected to mutation due to alteration of genes in the various cells. The different changes occur due to copying errors during replication, defects in chromosome segregation during mitosis and direct chemical attacks by reactive oxygen species. The basis of cancer cell formation was based on genetic instability which contradicts recent evidence that shows that the human body represents a mosaic made up of trillions of genetically distinct cells in such a way that two identical cells can rarely be found. The process of cellular genetic diversification commences during the embryonic development and continues throughout life causing the phenomenon of somatic mosaicism. Somatic mosaicism is the presence of two or more genetically diverse cell populations in an organism originating from a single fertilized egg, which is the zygote. It is a natural consequence of generalized and continuous life-long mutagenesis. However, there is need to understand better how genetic mosaicism works.

Recently, Dr. Anatoly Lichtenstein at the Institute of Carcinogenesis-Blokhin Cancer Research Center in Moscow reported that the notion of genetic instability should no longer be considered a unique property of cancer. His main objective was to revise numerous concepts of oncology and make the phenomenon on genetic mosaicism the point of focus when viewing carcinogenesis. He aimed at explaining changes that occur only in the genome of somatic cells and not in the programmed mosaicism of germ and immune cells. The study is described widely in the journal, Cancer research.

An extensive meta-analysis was performed on the different articles on cancer that date as back as 1975 in order to explain somatic mosaicism and how it causes cancer and its effect on the normal cells and cancer cells. He studied how different researchers explained genetic mosaicism in order to draw conclusions from their various researches.

After conducting a thorough research on the theory of somatic mosaicism the author found out that mosaicism is a dynamic process as DNA mutations accumulate during embryonic and postnatal development and that the earlier a change appears in the cells the higher its representation in the body and if it is potentially oncogenic, the higher the risk of developing cancer. Mosaicism is proven by many evidences which show that the genetic profile underlying carcinogenesis has been morphing over the years up to the point of final diagnosis. The researcher studied the “seed/soil” theory and established that most probably the genetic mosaicism affects both the “seeds” and the “soil” whereby the “soil” was the tissue where the tumor emerges hence linking cancer to its various causes.

According to Anatoly Lichtenstein somatic mosaicism plays a crucial role in understanding the causes of cancer. Mosaicism shows that a significant part of the blame for carcinogenesis lays on the environment which triggers malignant mutation of normal cells and favors carcinogenesis. The understanding of somatic mosaicism sets a foundation on which cancer prevention measures that is lifestyle and environmental modifications can be taken as the major way to control the many incidences and prevalence of various types of cancer in the world.

 

Reference

Anatoly V Linchestein; Genetic mosaicism: Cause and Effect: Cancer research. 2018, volume 78, page 1375-1377

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