Somebody recently ask me about cancer research in cellular biology and what are the essential signs when a cell is cancerous.
Cancer cells have defects in controlling normal mechanisms that govern how often cells divide, grow or differentiate. Cancer often occurs when these mechanisms cannot be properly regulated anymore.
There are five hallmarks of cancer and at least one of these hallmarks will bear fruit if cells become cancerous.
1. Uncontrolled cell growth in absence of growth signals
Normal cells require external growth signals (growth factors like EGFR) to grow and divide. These signals are transmitted through receptors that pass through the semi-permeable cell membrane. When the growth signals are absent, the mechanisms to stimulate cell growth is inhibited and cells stop growing.
Cancer cells can grow and divide without external growth signals. Some cancer cells can generate their own growth signals. For example sarcomas can produce their own tumor growth factor α (TGF-α).
2.Evading apoptosis
Cell apoptosis in biology means 'programmed cell death'. Natural in healthy tissues, cells function for a period of time and then enzymes are release which signals a death of a cell to allow new healthy cells to take over and carry out the intended function.
Cancer cells can avoid the signal to 'programmed cell death' and hence these faulty cells cannot be destroyed.
3. Resistance to inhibitors of cell growth
In normal cells, there are often internal or external growth factors, co-factors or kinases that often stimulate cell growth. There are also a group of co-factors and inhibitors in cells that inhibit cell growth. A healthy cell will generally have a good balance between growth and suppression.
Cancer cells become immune to inhibitors or co-factors which are meant to suppress cell growth, differentiation or induce apoptosis. These cells will grow uncontrollable.
4. Angiogenesis
Angiogenesis is the process by which new blood vessels are formed. Cancer cells promote this process, ensuring that such cells receive a continual supply of oxygen and other nutrients, thus starving these essential nutrients to normal cells where it is most needed.
5. Invasion into other tissues and organs
Cancer cells has the ability to break away from the original site and spread into the surrounding organs, tissues and cells.
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