In January 2000, two researchers published a famous and often cited article in the journal Cell, titled "Hallmarks of Cancer." They compared the development of a tumor to Darwin's theory of evolution: a succession of genetic changes leads to a progressive conversion of normal cells into cancer cells.
Furthermore, they identified six essential alterations in cell physiology they believed, when taken collectively, dictated malignant growth (although the sequence of alterations varies among tumors).
1. Self sufficiency in growth signals
2. Insensitivity to anti-growth signals
3. The ability to evade pre-programmed cell death
4. Limitless potential to replicate
5. Sustained ability to generate new blood vessels to support the tumor's growth
6. Tissue invasion and metastasis
Now, new discoveries expand on this knowledge, hinting at more of cancer's secrets and identifying additional physiological activities that may dictate how a single cell loses its ability to regulate itself and becomes cancerous.
Theory one: microbes
Millions of tiny microbes reside in the body. They aid in food digestion and perform other important functions. Our body's cells communicate regularly with these microbes. Researchers suspect that a miscommunication between cells and microbes might be the signal cells need to start dividing.
Theory two: junk DNA
Every cell has DNA, which transmits genetic information. Scientists believed only about 2 percent of DNA contained important information; the other 98 percent was what they called "junk" DNA. Now, researchers are evaluating whether junk DNA in fact sends signals that disrupts the balance between healthy cells and malignant ones.
Theory three: messenger RNA
Messenger RNA carries DNA information to ribosomes, little factories in our cells where we convert the information into proteins our body needs. However, behind the scenes, microRNA might be binding to these messenger RNA molecules, keeping DNA information from reaching the ribosomes. MicroRNAs are small RNA molecules that regulate genes, play a role in numerous biological processes, and may contribute to cancer when disrupted.
The National Cancer Institute has launched the Provocative Questions Initiative to re-energize cancer research. It's developed a list of important we must answer to further unravel cancer's secrets and improve our ability to prevent and treat cancer.
Sources:
Johnson, George. "Cancer's Secrets Come Into Sharper Focus." New York Times. Web. 15 August 2011.
http://www.nytimes.com/2011/08/16/health/16cancer.html
Hanahan, Douglas, and Weinberg, Robert A.. "The Hallmarks of Cancer."Cell 100(1) (2000): 57 - 70.
http://www.sciencedirect.com/science/article/pii/S0092867400816839
National Cancer Institute. "Provocative Questions." Web.
http://provocativequestions.nci.nih.gov/
