22.3: Hallmarks of Cancer
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Researchers have identified six molecular and cellular traits that characterize most cancers. These six hallmarks of cancer are summarized in Table \(\PageIndex{1}\). In this chapter, we will focus on the first two hallmarks, namely growth signal autonomy and insensitivity to anti-‐growth signals.
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Table \(\PageIndex{1}\) Ten Hallmarks of Cancer (Hanahan and Weinberg, 2000; Hanahan 2011) |
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1. Growth signal autonomy Cancer cells can divide without the external signals normally required to stimulate division. 2. Insensitivity to growth inhibitory signals Cancer cells are unaffected by external signals that inhibit division of normal cells. 3. Evasion of apoptosis When excessive DNA damage and other abnormalities are detected, apoptosis (a type of programmed cell death) is induced in normal cells, but not in cancer cells. 4. Reproductive potential not limited by telomeres Each division of a normal cell reduces the length of its telomeres. Normal cells arrest further division once telomeres reach a certain length. Cancer cells avoid this arrest and/or maintain the length of their telomeres. 5. Sustained angiogenesis Most cancers require the growth of new blood vessels into the tumor. Normal angiogenesis is regulated by both inhibitory and stimulatory signals not required in cancer cells. 6. Tissue invasion and metastasis Normal cells generally do not migrate (except in embryo development). Cancer cells invade other tissues including vital organs. 7. Deregulated metabolic pathways Cancer cells use an abnormal metabolism to satisfy a high demand for energy and nutrients. 8. Evasion of the immune system Cancer cells are able to evade the immune system. 9. Chromosomal instability Severe chromosomal abnormalities are found in most cancers. 10. Inflammation Local chronic inflammation is associated with many types of cancer. |