Telomere erosion triggers growth arrest but not cell death in human cancer cells retaining wild-type p53: implications for antitelomerase therapy

Preto, Ana, Singhrao, Simarjit Kaur, Haughton, Michele Fleur, Kipling, David Glyn, Wynford-Thomas, David and Jones, Christopher John 2004. Telomere erosion triggers growth arrest but not cell death in human cancer cells retaining wild-type p53: implications for antitelomerase therapy. Oncogene 23 (23) , pp. 4136-4145. 10.1038/sj.onc.1207564

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Abstract

Telomerase activity in tumours is often associated with p53 mutation. Many antitelomerase therapies take advantage of the inability of cells expressing mutant p53 to undergo replicative senescence, since this allows telomere erosion to continue until 'crisis', hence providing the desired cytotoxic effect. However, some tumour types, including breast, melanomas and thyroid, retain wild-type p53 function and the effectiveness of antitelomerase therapies in such tumour cells have not been adequately addressed. To explore this, we made use of two thyroid cancer cell lines K1 and K2, which retain wt p53. Telomere erosion induced by the expression of a dominant-negative (DN) hTERT resulted in delayed onset of growth arrest in K1 and K2 cells, reminiscent of replicative senescence, with low levels of BrdU labelling and apoptosis, associated with high p21WAF1 and senescence-associated galactosidase expression. In contrast, abrogation of p53 function by the expression of HPV16 E6 in K1 and K2 cells either at the same time as DNhTERT or just prior to the onset of senescence allowed cells to continue growing until 'crisis'. Likewise, microinjection of a p53 neutralizing antibody into 'senescent' K1 DNhTERT cells permitted re-entry into the cell cycle. We conclude that thyroid tumour cells with wild-type p53 retain an intact p53-mediated growth arrest response to telomere erosion. This raises the intriguing question of why, therefore, p53 mutation is not selected for in such cancers, and also calls into question the therapeutic value of telomerase inhibitors in such cases.

Item Type:	Article
Date Type:	Publication
Status:	Published
Schools:	Medicine
Uncontrolled Keywords:	p53 ; telomerase ; cancer ; senescence ; therapy
Publisher:	Nature Publishing
ISSN:	0950-9232
Last Modified:	18 Oct 2017 08:15
URI:	https://orca.cardiff.ac.uk/id/eprint/172

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