Absence of cancer–associated changes in human fibroblasts immortalized with telomerase

Morales, Carmela P.; Holt, Shawn E.; Ouellette, Michel; Kaur, Kiran; Yan, Ying; Wilson, Kathleen; White, Michael A.; Wright, Woodring E.; Shay, Jerry W.

doi:10.1038/5063

Cited by 741 publications

(503 citation statements)

References 26 publications

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“…Telomere attrition leads to genomic instability, typified by chromosomal end-toend fusions resulting in nonreciprocal chromosomal translocations (Artandi et al 2000). Cells with reconstituted telomerase activity maintain telomere structure (Masutomi et al 2003), a diploid karyotype and have an extended replicative life span (Bodnar et al 1998;Vaziri and Benchimol 1998) without any indication of being transformed (Jiang et al 1999;Morales et al 1999). Likewise, we found that wild-type SF-MEFs or p53 −/− SFMEFs are immortal but have stable diploid genomes (Fig.…”

Section: Genomic Stability Prolongs Cellular Life Spanmentioning

confidence: 53%

Activated oncogenes promote and cooperate with chromosomal instability for neoplastic transformation

Woo¹,

Poon²

2004

Genes Dev.

113

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Most cancer cells are aneuploid. The chromosomal instability hypothesis contends that aneuploidy is the catalyst for transformation, whereas the gene mutation hypothesis asserts that cancer is driven by mutations to proto-oncogenes and tumor-suppressor genes, with the aneuploidy a side effect of tumorigenesis. Because genotoxic stress induced by "culture shock" can obscure the transforming potential of exogenous genes, we cultured wild-type and p53 −/− mouse embryo fibroblasts in a more physiological (serum-free) environment. Under these conditions, the cells were immortal and, more importantly, chromosomally stable. Expression of oncogenic H-RasV12 did not induce senescence, but sensitized these cells to p53-dependent apoptosis. In addition, H-RasV12 induced chromosomal instability, as well as accumulation and phosphorylation of p53. Significantly, whereas cells grown under standard conditions could be transformed by coexpression of H-RasV12 and E1A, the chromosomally stable cells were refractory to transformation, as measured by anchorage-independent growth and tumor formation in nude mice. These oncogenes required a third genetic alteration that abolished the p53 pathway to create a permissive environment that promotes rapid chromosomal instability and transformation. Oncogene-induced chromosomal instability and transformation was attenuated by antioxidants. These data indicate that chromosomal instability could be a catalyst for oncogenic transformation, and bring together aspects of the chromosomal instability hypothesis and the gene mutation hypothesis for tumorigenesis.[Keywords: Chromosomal instability; oncogenic Ras; p53; transformation] Supplemental material is available at http://www.genesdev.org.

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Section: Genomic Stability Prolongs Cellular Life Spanmentioning

confidence: 53%

Activated oncogenes promote and cooperate with chromosomal instability for neoplastic transformation

Woo¹,

Poon²

2004

Genes Dev.

113

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“…Some authors have noted that hTERT þ cells express a normal cell-cycle arrest and checkpoint protein response to specific challenges including DNA damaging agents (including chromium) (Jiang et al, 1999;Morales et al, 1999;Pritchard et al, 2001;Wood et al, 2001;Gorbunova et al, 2002). In contrast, other authors have reported that there is a loss of p16INK4a and hyperphosphorylation of pRb in hTERT þ cells (Tsutsui et al, 2002;Piboonniyom et al, 2003) and in one cell line a mutation in p53 and abnormal G1 checkpoint (Noble et al, 2004).…”

Section: Metal-induced Genomic Instabilitymentioning

confidence: 99%

Effects of hTERT on metal ion-induced genomic instability

et al. 2006

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There is currently a great interest in delayed chromosomal and other damaging effects of low-dose exposure to a variety of pollutants which appear collectively to act through induction of stress-response pathways related to oxidative stress and ageing. These have been studied mostly in the radiation field but evidence is accumulating that the mechanisms can also be triggered by chemicals, especially heavy metals. Humans are exposed to metals, including chromium (Cr) (VI) and vanadium (V) (V), from the environment, industry and surgical implants. Thus, the impact of low-dose stress responses may be larger than expected from individual toxicity projections. In this study, a short (24 h) exposure of human fibroblasts to low doses of Cr (VI) and V (V) caused both acute chromosome damage and genomic instability in the progeny of exposed cells for at least 30 days after exposure. Acutely, Cr (VI) caused chromatid breaks without aneuploidy while V (V) caused aneuploidy without chromatid breaks. The longerterm genomic instability was similar but depended on hTERT positivity. In telomerase-negative hTERTÀ cells, Cr (VI) and V (V) caused a long lasting and transmissible induction of dicentric chromosomes, nucleoplasmic bridges, micronuclei and aneuploidy. There was also a long term and transmissible reduction of clonogenic survival, with an increased b-galactosidase staining and apoptosis. This instability was not present in telomerasepositive hTERT þ cells. In contrast, in hTERT þ cells the metals caused a persistent induction of tetraploidy, which was not noted in hTERTÀ cells. The growth and survival of both metal-exposed hTERT þ and hTERTÀ cells differed if they were cultured at subconfluent levels or plated out as colonies. Genomic instability is considered to be a driving force towards cancer. This study suggests that the type of genomic instability in human cells may depend critically on whether they are telomerase-positive or -negative and that their sensitivities to metals could depend on whether they are clustered or diffuse.

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“…However, we and others have described earlier that the only step required for the immortalization of somatic cells is activation of telomerase (Jiang et al, 1999;Morales et al, 1999;Li et al, 2007). In our study, we generated hTERT immortalized epithelial cell lines without disruption of pRb and p53 function.…”

mentioning

confidence: 90%

A novel function of colony-stimulating factor 1 receptor in hTERT immortalization of human epithelial cells

Kocher

Salako

et al. 2008

Oncogene

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The receptor for macrophage colony-stimulating factor 1 receptor (CSF1R) is a product of the proto-oncogene c-fms and a member of the class III transmembrane tyrosine kinase receptor family. Earlier, we described increased mRNA expression of CSF1R in human telomerase reverse transcriptase (hTERT) immortalized human ovarian surface epithelial (IOSE) cell lines derived from a single donor. Here, we further describe that CSF1R is upregulated at both the mRNA and protein level in hTERT immortalized human normal OSE cells from two different donors and in hTERT immortalized human pancreatic ductal epithelial cells. CSF1R was not upregulated in hTERT immortalized epithelial clones that subsequently underwent senescence or in immortalized fibroblasts. Upon stimulation by the CSF1R ligand CSF1, the immortalized epithelial cell lines showed rapid internalization of CSF1R with concomitant down-modulation and colocalization of phosphorylated NFjBp65 with hTERT protein, hTERT translocation into the nucleus and the binding of c-Myc to the hTERT promoter region. Reducing the expression of CSF1R using short hairpin interfering RNA abolished these effects and also decreased cell survival and the number of population doublings under suboptimal culture conditions. The telomerase inhibitor GRN163L confirmed a role for telomerase in the cleavage of the intracellular domain of CSF1R. On the basis of these findings, we suggest that CSF1R may be a critical factor facilitating hTERT immortalization of epithelial cells.

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Absence of cancer–associated changes in human fibroblasts immortalized with telomerase

Cited by 741 publications

References 26 publications

Activated oncogenes promote and cooperate with chromosomal instability for neoplastic transformation

Activated oncogenes promote and cooperate with chromosomal instability for neoplastic transformation

Effects of hTERT on metal ion-induced genomic instability

A novel function of colony-stimulating factor 1 receptor in hTERT immortalization of human epithelial cells

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