The Disturbance of Cell-Self-Regulation Due to Oncogene Activation and Antioncogene Inactivation

Abstract

We mentioned in Chapter 2 that point mutations in a protooncogene can cause a change in the sequence and possibly also in the conformation of the protein coded by the oncogene. If this so-called oncoprotein takes part in the self-regulation of the cell, it can disturbed to such an extent that the cell goes over to another stationary state. Namely a living cell is not in thermodynamical equilibrium, because it is, due to the metabolism, in contact with its environment, and thus an open system. Therefore one can only speak about so-called stationary states of a cell in a given phase of its duplication cycle in which the quantity of the different chemical substances which enter and leave it per time-unit does not change. Further its temperature, volume, the pressure inside the cell, and the osmotic pressures of the transport of chemicals through its various membranes is constant. An open system can exist in different stationary states. If a living cell in its normal state is in a given stationary state and if instead of a protein taking part in its self-regulation a changed protein (an oncoprotein) occurs, or the original regulatory protein becomes inactive because of a point mutation, the cell can go over to another stationary state which is characterized by other flow of chemicals (its metabolism changes) and/or different thermodynamical parameters. The transition of a cell from its normal stationary state to another one can cause the initiation of the malignant transformation of the cell.