Gradually accumulating data has convinced scientists that the key events in the development of cancer to be found in the changes of the cells - the mother of a cancer. Studies conducted in the 70-ies, it was shown that the transfer of DNA from tumor cells in healthy accompanied by the recent acquisition of malignant properties. Information about the phenotype of cancer cells, as it turned out, contained in a separate DNA molecules, but because of a malignant process is supported by the work of genes and only partially - other constituent elements of the cell.
Recently techniques have been developed to obtain and cloning (breeding) individual genes from a specific segment of DNA. To select individual genes from total long chain of its "cut" on the part of special enzymes - restrictedly. Selected fragments of DNA inserted into bacterial plasmids (DNA molecule capable of Autonomous replication") or bacteriophages (viruses, bacteria), which then infects Escherichia coli. In this way it was found that the malignant transformation (from lat. transformo-turn) passes not all DNA animal cells, and only certain genes, which were called oncogenes.
Each oncogene has its physiological predecessor, who called protooncogenes, they represent the three Latin letters. Under the action of various activators protooncogen can turn into an oncogene, this is sometimes enough odnodozovy mutations in a single cell. So, in the segment consisting of 350 amino acid residues that may occur replacing just one reason (say, guanine replaces thymine or glycine - valine) and protooncogen transformed into an oncogene.
The proto-oncogene are evolutionary ancient, and therefore stable genetic structure. Protooncogen src found in fruit flies, fruit flies and all mammals, and protooncogen ras is common for yeast and humans. This gives grounds to think that the proto-oncogene originated hundreds of millions of years ago, and they would have not survived in the genome of the higher animals, if not carried important metabolic function. Consider that the number of different proto-oncogene, a person does not exceed 100. They are found in all cells, are in an embryonic and differentsirovaniya tissues, in resting and dividing cells.
Gene activity is manifested through the function of the encoded protein them, namely proteins are the basis of all the structures of the cell. They catalyze everything in her reaction, and, therefore, defined as the form of the cell, and its function. The action of the oncogene is beyond the scope of natural regulation, proteins begin to operate abnormally, and contribute to the transformation of normal cells in the tumor. So, gene srv encodes proteins, non-enzymatic activity, which occur accession phosphate groups to other proteins. Phosphorylation is an important way for the regulation of many of protein functions; in particular, it defines the motor activity of the cells. The strengthening of this process is observed in many tumors, weakens the intercellular contacts. Protein gene rsv important for the processes of glycolysis anaerobic oxidation of glucose. Oncogene also leads to an increase of some intermediate enzymes of this process, causing the tumor cells intensively produce lactic acid.
Cancer cells have a number of features that differentiate them from normal cells. They often differ in shape, degree of differentiation. Their localization is not limited to certain tissues, which is typical of normal cells. The outer membrane of cancer cells can be depleted antigens compatibility, but it contains proteins early stages of development (embryonic) or tumor-specific molecules with different immunological properties. The transformation of energy in cancer cells is mainly anaerobically, i.e. oxidation takes place without participation of oxygen. They are the "sweet tooth"as faster than normal cells capture from the blood carbohydrates. Believe that this set of characteristics is provided not different genes, but one. So say pleiotropic effects of oncogene, which defines the entire complex of characteristics of tumor cells. Chief among them is accelerated and uncontrolled division.
