What makes cells not go through the process of DNA multiplication and the other stages of cell division, that make cancer cells?
In: Biology
A flaw in dna coding. There are many factors.
Could be genetics.
Could be congenital (mutation from birth)
Could be a proofreading error from the trna or mrna
Could be environmental (carcinogenic)
But its 99.9999% of the time a coding error, which is any of the above and more.
This puts them in the growth phase and locks them in the growth phase as opposed to the stand by phase.
There are multiple proteins in the cell that detect things like massive DNA damage and stop the multiplication process. Cancer occurs when one of these monitors gets mutated. p53 and Rb are two such proteins.
Another way cancer can occur is if a protein that PROMOTES cell division gets mutated and amplified in some way
I thought it was uncontrolled mitosis cell replication so it just keeps spreading?? Maybe that’s just how it grows.
Cells in mature multicellular organisms are constrained from division unless they are stimulated by growth hormones. In culture, mammalian cells are given nutrients, but also have blood serum supplied to them, which contains these hormones. A type of serum that is rich in hormones is fetal calf serum, which is particularly good for promoting cell growth in culture.
But when they touch another cell, they srop growing even in the presence of serum. This is seen in cell culture, where cells will grow until they form a single layer on a dish, and then stop. The phenomenon is called “contact inhibition”.
A dose of fresh serum, or additional hormones, can overcome this behavior, making the cells form a crowded layer after one cell division. But the cells will still largely stop growing, even in the presence of hormones. So the contact with other cells is actively inhibitory to cell growth.
Cancer cells seen to have a defect in this inhibition. Some may grow without hormonal stimulation. Some may ignore contact inhibition, pilling into reach other and forming clumps of cells in culture that die in the middle, where those cells cannot receive oxygen and nutrients. In many different ways, cancer cells have some defect that makes them ignore the need for an external signal to begin each cycle of growth.
This defect can take many forms. In some cases, a cell might have a defect in the gene for a growth hormone receptor, so it makes receptors that are stuck in the “on” position, making the cell think that it is being given hormones. In others, the proteins that detect the presence of other cells is damaged, so the cell cannot tell that it is in contact with neighbors. Or some internal control protein might be defective, allowing inappropriate cell growth. These defects might be from small mutations, or even from a virus that inserts its DNA into the middle of an important gene by accident.
Cells of multicellular organisms have multiple layers of control over growth, and so the number and types of defects would take years of study to understand.
Latest Answers