## Tumour cells are stressed too

You can read more about the transformation of a healthy cell into a tumour in chapter 9 - When cells go crazy, but at this point we will mention that in the process of tumour transformation, when an initially healthy cell undergoes a large number of changes that fundamentally affect many aspects of its functioning, this cases the cell stress. A direct consequence of the rapid division and accumulation of mutations is the stress of DNA damage. Rapid division is also accompanied by errors in the division of chromosomes into daughter cells, which results in the formation of cells with a defected karyotype, and the cell thus finds itself in mitotic stress. The instability of the genome is further manifested by changes in the level of proteins produced in the cell, which causes proteotoxic stress. Non-functional proteins or the accumulation of proteins can cause their insufficient removal and possible aggregation, which has a toxic effect on the cell. The stress of lack of oxygen also has a significant impact, as the imperfect vascular network that forms in the tumor cannot cover the demands of the growing tumour. There are also changes in the expression of genes which could help the cells deal with this condition, but these changes give them aggressive properties. The consequence of adaptation to lack of oxygen is the suppression of breathing and the transition to metabolism without the need for oxygen, which is accompanied by unnatural metabolic stress. And last but not least, there is also the stress of damage to immune control. Cells (not only tumour cells) can thus experience a large number of different stressful situations, which they have to deal with during their lifetime and thus ensure the proper functioning of the organism even in adverse environments.