Thursday, September 07, 2006

gene that pro­tects against can­cer ~ ageing

Gene fights cancer by aging us, studies find:
"Gene fights cancer by aging us, studies find
Sept. 6, 2006Courtesy Natureand World Science staff
Bi­ol­o­gists say they’ve iden­ti­fied a gene that pro­tects against can­cer by sup­press­ing cells’ abil­i­ty to di­vide—making us age faster in the proc­ess.The find­ings sug­gest that a fun­da­men­tal trade­off be­tween long life and can­cer pro­tec­tion is built in­to our bod­ies, the sci­en­tists said. The work also in­di­cate ag­ing may in some sense be pro­grammed, they added, which some re­searchers have the­o­r­ized be­fore.
Lung can­cer cells in an image from a scan­ning elec­tron mi­cro­scope. (Cour­te­sy U.S. Centers for Disease Control)
The con­clu­sions emerge from three pa­pers pub­lished on­line in the re­search jour­nal Na­ture this week.The stud­ies were aimed at ex­plain­ing why stem cells, “mas­ter” cells that can de­vel­op in­to a va­ri­e­ty of dif­fer­ent cell types, lose the abil­i­ty to di­vide and gen­er­ate new cells with age. Ex­per­i­ments found that a mo­l­e­cule called p16­INK­4a, and a gene that pro­duces it, lim­its such cells’ re­gen­er­a­tive abil­i­ties, the re­search­ers said. The ap­par­ent ben­e­fit of this is to head off can­cer, which in­volves run­away cell mul­ti­pli­ca­tion. The mol­e­cule was al­read­y known to sup­press can­cer. The draw­back is that slowed cell di­vi­sion is linked with ag­ing, ac­cord­ing to the sci­en­tists.The au­thors of the stud­ies found that that the gene’s ac­tiv­i­ty in­creases as stem cells in three mouse tis­sues lose their abil­i­ty to self-re­new. The teams ge­net­i­cal­ly en­gi­neered mice that lacked p16INK4a and then ex­am­ined them when they got old. Pro­gen­i­tor cells in the ro­dents clung on­to their youth and did­n’t show the nor­mal de­cline in pro­lif­er­a­tion with age, they said. Sean Mor­ri­son of the Uni­ver­si­ty of Mich­i­gan in Ann Ar­bor, Mich. and col­leagues stud­ied pro­gen­i­tor brain cells in mice. Nor­man Sharp­less of the Uni­ver­si­ty of North Car­o­li­na School of Med­i­cine in Chap­el Hill, N.C. and his team stud­ied pro­gen­i­tors in the pan­cre­at­ic islets that make insulin-secreting beta-cells. Da­vid Scad­den of the Har­vard Stem Cell In­sti­tute in Bos­ton and his group ex­am­ined bone mar­row cells that make blood.The work al­so sug­gests type 2 di­a­be­tes might part­ly re­sult from a fail­ure of cells in the pan­cre­at­ic islets to re­new with age­ing, the re­searchers said. Thus, they added, block­ing this pro­tein in cer­tain tis­sues might com­bat cer­tain ef­fects of age­ing.

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