We found a match
Your institution may have access to this item. Find your institution then sign in to continue.
- Title
Loss of p53 function accelerates acquisition of telomerase activity in indefinite lifespan human mammary epithelial cell lines.
- Authors
Stampfer, Martha R; Garbe, James; Nijjar, Tarlochan; Wigington, Don; Swisshelm, Karen; Yaswen, Paul
- Abstract
We describe novel effects of p53 loss on immortal transformation, based upon comparison of immortally transformed human mammary epithelial cell (HMEC) lines lacking functional p53 with closely related p53(+) lines. Our previous studies of p53(+) immortal HMEC lines indicated that overcoming the stringent replicative senescence step associated with critically short telomeres (agonescence), produced indefinite lifespan lines that maintained growth without immediately expressing telomerase activity. These telomerase(-) ‘conditionally immortal’ HMEC underwent an additional step, termed conversion, to become fully immortal telomerase(+) lines with uniform good growth. The very gradual conversion process was associated with slow heterogeneous growth and high expression of the cyclin-dependent kinase inhibitor p57Kip2. We now show that p53 suppresses telomerase activity and is necessary for the p57 expression in early passage p53(+) conditionally immortal HMEC lines, and that p53(-/-) lines exhibit telomerase reactivation and attain full immortality much more rapidly. A p53-inhibiting genetic suppressor element introduced into early passages of a conditionally immortal telomerase(-) p53(+) HMEC line led to rapid induction of hTERT mRNA, expression of telomerase activity, loss of p57 expression, and quick attainment of uniform good growth. These studies indicate that derangements in p53 function may impact malignant progression through direct effects on the conversion process, a potentially rate-limiting step in HMEC acquisition of uniform unlimited growth potential. These studies also provide evidence that the function of p53 in suppression of telomerase activity is separable from its cell cycle checkpoint function.Oncogene (2003) 22, 5238-5251. doi:10.1038/sj.onc.1206667
- Subjects
P53 antioncogene; TELOMERASE; EPITHELIAL cells; CYCLIN-dependent kinases; CELL cycle
- Publication
Oncogene, 2003, Vol 22, Issue 34, p5238
- ISSN
0950-9232
- Publication type
Article
- DOI
10.1038/sj.onc.1206667