What is common?
The development of the embryo and cancer trigger the same molecular mechanisms
Alexandra Medvedeva, Naked Science
After fertilization, gene expression in the resulting zygote stops. For further embryonic development, of course, the inclusion of genes is necessary, but for a long time it remained a mystery how and when this happens. For decades, scientists have believed that the genes of human embryos are "silent" for several days after fertilization, and the activation of the genome occurs at about the stage of eight cells. Up to this point, the embryo synthesizes all the proteins it needs on the basis of matrix RNAs obtained from the mother.
However, RNA sequencing of single cells conducted by researchers from the University of Bath and the University of Cambridge (UK) showed that in human embryos, gene expression begins already at the stage of a single cell. This happens almost immediately after fertilization, which by itself triggers transcription, activating transcription factors already contained in the egg.
Another surprising discovery was that the first genes expressed in the embryo activate cancer-related transcription factors, including the proto-oncogenic proteins MYC and MYCN. The results of the study are published in the journal Trends in Cell Biology (Perry et al., The initiation of mammalian embryonic transcription: to begin at the beginning).
Scientists know very little about how cancer begins. As a rule, by the time he is diagnosed, the disease is already progressing. Data on the factors triggering the development of a tumor would allow the development of new methods for the diagnosis and treatment of oncological diseases. The process of fertilization is predictable, and the growth of the embryo can be easily observed in the laboratory, so the similarity of embryonic development with the development of a tumor is a promising result.
Activation of embryo gene expression is probably associated with epigenetic changes in the way the genome is packaged. Phosphorylation and other modifications that occur to the genome during fertilization can activate egg transcription factors to initiate the activation of the embryonic genome.
The expressed genes lie on the molecular pathways associated with cancer. One possible explanation is that the beginning of embryonic development, as well as the transformation of a somatic cell into a cancer cell, is initiated epigenetically, that is, it is triggered by modifications of DNA that do not change the sequence of its nucleotides.
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