Cancer-fighting roles Scientists have discovered a new
role in cancer protection for an already well-known tumor suppressor
protein. The protein, called p53, protects cells from becoming
cancerous by sensing stress and either shutting down cell division or
triggering cell death. Researchers at the University of Tokyo and
colleagues have discovered that p53 also plays a role in slicing
stretches of RNA into regulatory molecules called microRNAs (SN: 8/15/09, p. 8). Mutations of the gene for p53 prevent proper assembly of microRNA-processing machinery, the researchers found.
MicroRNAs are tiny, containing only about 22 nucleotides, or chemical
letters. But the molecules have a big influence on nearly every aspect
of cellular function. The absence of some microRNAs has recently been
linked to cancers. Researchers at Johns Hopkins University, along with
others, replaced a microRNA missing from liver cancer cells in mice and
either stopped growth of or shrunk tumors (SN: 7/4/09, p. 13). And scientists at MIT discovered that lacking just one copy of Dicer1, a gene that encodes a protein that helps snip RNAs into microRNA, can make for more aggressive cancer in mice (SN Online: 12/2/09).
