Genes are DNA sequences that carry genetic information and are the basic genetic units that control traits.Oncogene is a kind of gene, which refers to the gene inherent in human or other animal cells (as well as carcinogenic viruses), also known as transformation gene, and can promote the canceration, invasion and metastasis of normal cells after activation.Oncogene activation includes point mutation, gene amplification, chromosome rearrangement, virus infection, etc.The result of oncogene activation is that the number or function of oncogene increases, which makes cells proliferate excessively and obtain other malignant characteristics, thus forming malignant tumors.
The viral oncogene refers to the gene in the retrovirus genome that can cause the host cell infected by the virus to become cancerous.
2. Cell Oncogene
In normal people and higher animals, cell oncogenes are ubiquitous, so they are also called proto oncogenes.There are proto oncogenes in the genome of every normal cell, but they do not appear carcinogenic activity, and only become oncogenes with carcinogenic ability after mutation or abnormal activation.
Activation mechanism
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The process of transforming from a normal proto oncogene to an oncogene capable of transforming cells is called proto oncogene activation.There are four main mechanisms of cell oncogene activation:
1. Obtain strong promoter and enhancer
2. Chromosome translocation
3. Gene amplification
4. Point mutation
Proto oncogene family
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1. ras family
Ras gene family is the most common oncogene family, which plays an important role in regulating the proliferation and differentiation of normal cells.
2. myc family
Myc gene is a kind of nucleoprotein oncogene that has been studied most at present, including C-myc, N-myc, L-myc and R-myc.One of the remarkable characteristics of myc gene in malignant tumors is that it is activated by gene amplification and gene mutation, and there are double micro chromosomes and chromosome homochromatic regions.The activated myc gene largely expresses myc protein, which plays an important role in cell growth and differentiation.
3. src family
The product has protein tyrosine kinase activity, can promote the signal transduction of proliferation, and is located inside the cell or distributed across the membrane.
4. sis Family
P28 can stimulate cell division and proliferation of mesenchymal tissue.
5. myb family
Intranuclear transcription factors.
Product and function
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1. Extracellular growth factor
Receptors acting on the cell membrane or directly transferred to the cell, activate transcription factors through protein kinases, and trigger the transcription activation of a series of genes.
2. Transmembrane growth factor receptor
It receives extracellular growth signals and transmits them into cells.
3. Intracellular signal transduction molecules
Transmit the received signal from the cell to the nucleus to promote cell growth.
4. Intranuclear transcription factors
Some oncogene expression proteins are located in the nucleus and combine with cis regulatory elements of target genes to directly regulate the transcriptional activity of target genes.
