1. Uncontrolled Growth and Division:
* Normal cells: Grow and divide in a controlled manner, only when needed, and stop dividing when they come into contact with other cells (contact inhibition).
* Cancer cells: Ignore signals that normally regulate growth and division. They continue to divide even when not needed and can pile up on top of each other, forming tumors.
2. Ability to Metastasize:
* Normal cells: Remain in their designated tissue or organ.
* Cancer cells: Can break away from the original tumor, travel through the bloodstream or lymphatic system, and invade other tissues and organs, forming new tumors (metastases).
3. Immature and Undifferentiated:
* Normal cells: Mature into specialized cells with specific functions.
* Cancer cells: Often remain immature (undifferentiated) or revert to a more primitive state, losing their specialized functions.
4. Angiogenesis (Blood Vessel Formation):
* Normal cells: Only promote blood vessel growth when necessary, such as wound healing.
* Cancer cells: Release signals that stimulate the formation of new blood vessels to supply the tumor with nutrients and oxygen.
5. Evading the Immune System:
* Normal cells: Display "self" markers that allow the immune system to recognize them as healthy.
* Cancer cells: May develop ways to evade the immune system, allowing them to grow undetected.
6. Telomere Maintenance:
* Normal cells: Their telomeres (protective caps on the ends of chromosomes) shorten with each cell division, eventually leading to cell death.
* Cancer cells: Can activate mechanisms to maintain their telomeres, allowing them to divide indefinitely.
7. Metabolic Changes:
* Normal cells: Maintain a balanced metabolism.
* Cancer cells: May exhibit altered metabolism, utilizing nutrients differently and producing more waste products.
8. Increased Resistance to Apoptosis:
* Normal cells: Undergo programmed cell death (apoptosis) when damaged or unhealthy.
* Cancer cells: Often develop ways to resist apoptosis, allowing them to survive and proliferate even when damaged.
9. Changes in Gene Expression:
* Normal cells: Have a tightly controlled pattern of gene expression.
* Cancer cells: Can have altered gene expression patterns, leading to the production of proteins that promote uncontrolled growth, invasiveness, and other cancer hallmarks.
10. Sensitivity to Chemotherapy:
* Normal cells: Generally less sensitive to chemotherapy drugs.
* Cancer cells: Often more sensitive to chemotherapy drugs due to their rapid growth and altered metabolism.
Understanding these differences in behavior is essential for developing effective strategies for diagnosing and treating cancer.
