|Natural killer cells|
Normal cells go through senescence through shortening of telomeres with every cell division. Cancer cells however have telomerase that will sustain the telomere length of the chromosomes rendering the cell virtually immortal.
2. Cancer cells have a way around apoptosis, their programmed cell death.
They overexpress antiapoptotic molecules and can multiply forever.
3. The Grim Reaper can't recognize them.
The Natural killer cells, or the Grim Reaper; are supposed to cause death of the tumor cells. However, cancer cells remain undetected because they down regulate their MHC proteins or use decoy proteins to look innocent.
4. If recognized, the Grim Reaper can't kill them.
Tumor cells block the death receptor pathway and directly interfere with the perforin/granzyme pathway. That is why, natural killer cells fail to kill them.
5. Cancer cells don't need anything.
Cancer cells are self sufficient on growth factors. This means that they can continue to proliferate and divide independently, as opposed to normal cells that need external growth factors.
6. And if they do need something, they order it to come to them.
When cancer cells need of oxygen and nutrients, they stimulate angiogenesis; which is inducing growth of new blood vessels.
7. They have metabolic super powers.
The metabolism of malignant cells is usually more anaerobic than that of normal cells and is greatly accelerated. Malignant cells have the ability to withstand hypoxic conditions. They have increased glucose and amino acid uptake. In addition, they have high levels of hexokinase increasing their glucose utilization.