Chapter 17: Death (Genome)

•The brain is born with too many connections between cells, which are later lost as it develops.

• This loss happens because of experience and the environment, which sharpens the skills of the brain.

• Cells in the body are constantly committing suicide for the greater good of the body.

• Mutiny is a perpetual problem for cells, as they are constantly forgetting their patriotic duty to serve germ cells.

• Cancerous mutiny can usually be stopped by an elaborate series of switches that induce cell suicide if necessary.

•In 1909, Peyton Rous proved that cancer could be contagious among chickens.

• In the 1960s, a whole string of animal cancer viruses (oncoviruses) were discovered.

• By 1975, it was proven that genes alone could cause cancer (not just viral infection).

• Tumor suppressor genes are the opposite of oncogenes: they prevent uncontrolled cell growth.

• TP53 is a gene that detects abnormal behaviour in cells and issues an instruction to commit suicide.

• Mutation in the TP53 gene is almost the defining feature of a lethal cancer; in fifty-five per cent of all human cancers, TP53 is broken.

•Mutation is random, but selection is not.

• Cancer is a disease that very roughly doubles in frequency every decade of our lives.

• TP53 encodes the recipe for a simple protein, p53, that is normally rapidly digested by other enzymes so that it has a half-life of only twenty minutes.

• P53 sometimes realises what is happening and kills the tumour cells before the blood supply arrives.

• Cancers in tissues with poor blood supply, such as skin cancers, therefore must disable TP53 early in their development or fail to grow.

• So chemotherapy and radiation therapy are actually, like vaccination, treatments that work by helping the body to help itself.

•Division and death are triggered by the gene, but its death signal is temporarily suppressed by external factors called survival signals.

• When these survival signals run out, death takes over.

• It is as if the designer, aware of MYC’s capacity to run amok, has automatically booby-trapped it so that any cell which gets carried away kills itself as soon as the supply of survival factors expires.

• The ingenious designer has gone a step further, by tying together three different oncogenes, MYC, BCL-2 and RAS.

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Related posts:

1. Law 17: Seize the Historical Moment (The Laws of Human Nature)
2. Part 2: Isolate the Victim (The Art of Seduction)
3. Chapter 16: The Capitalist Creed (Sapiens)
4. The Veil of Ignorance