Use this URL to cite or link to this record in EThOS: http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.392459
Title: Functional demonstration of a mortality phenotype associated with 4cen-q23.
Author: Forsyth, Nicholas R.
Awarding Body: University of Glasgow
Current Institution: University of Glasgow
Date of Award: 2000
Availability of Full Text:
Access through EThOS:
Abstract:
Normal human keratinocytes possess a finite replicative lifespan whereas most advanced squamous cells carcinomas are immortal. The mechanisms, whose abrogation's can be considered necessary to achieve immortality, include those involving the negative cell cycle regulators p53, p161NK4Aa,nd the telomere repair reverse-transcriptase enzyme, telomerase. Other specific chromosomes have also been demonstrated to carry functions whose loss is necessary for the development of immortality, through immortal phenotype reversion upon reintroduction into an immortal cell line. We demonstrate here the phenotypic reversion of immortal HNSCCderived keratinocyte cell lines to a mortal growth-arrest upon reintroduction of a resistance marker tagged wild-type human chromosome 4. We further demonstrate that this phenotypic reversion occurs only in cell lines, which display LOH on 4q (BICR6 and BICR31), and not in those with intact endogenous chromosome 4 copies (BICR3 and BICR19), and that it is chromosome 4-specific, chromosomes 6, 11, and 15 having no effect on proliferative lifespan following introduction into BICR6 by MMCT. Through XMMCT-based truncated chromosomal fragment generation the functional complementation was localised to 4cen-q23, whilst fine mapping in segregants arising from the MMCT experiments identified an approximate 1.5Mb locus containing a minimal number of candidate genes. Through biological assay we have further determined the growth-arrest to have characteristics of crisis. This was determined through low BrdU incorporation balanced with high levels of apoptosis to statistically significance levels «0.05). We found no evidence for involvement of telomeric attrition in the observed phenotype, through insufficient phenotypic lag (3-10 MPD) and growth-arrest in the presence of ectopic hTERT expression, suggesting the operation of an alternative mechanism. This suggests the presence of gene(s) at 4cen-q23 whose loss is advantageous to the development of immortality in advanced tumours including HNSCC
Supervisor: Not available Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID: uk.bl.ethos.392459  DOI: Not available
Share: