Amplification of DNA Sequences in Mammalian Cells

Hamlin, Joyce L.; Leu, Tzong-Shyng; Vaughn, James M.; Ma, Chi; Dijkwel, Pieter A.

doi:10.1016/s0079-6603(08)60010-0

Cited by 44 publications

(24 citation statements)

References 186 publications

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“…This may re¯ect the fact that gene ampli®cation can only occur in genetically unstable cells. 20,21 AR ampli®cation also is associated with increased SPF. This indicates that AR mediated cell proliferation can be augmented in the recurrent tumour cells.…”

Section: Discussionmentioning

confidence: 98%

Aneuploidy and rapid cell proliferation in recurrent prostate cancers with androgen receptor gene amplification

Koivisto

1997

Prostate Cancer Prostatic Dis

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Mechanisms of prostate cancer recurrence during androgen deprivation are poorly understood. We recently described androgen receptor (AR) gene ampli®-cation in 28% of recurrent prostate carcinomas from hormone-refractory prostate cancer patients. To investigate the hypothesis that ampli®cation of the AR gene promotes the growth of hormone-refractory prostate carcinomas, DNA¯ow cytometric (FCM) studies were carried out to compare matched, primary and hormone-refractory recurrent samples from 31 prostate cancer patients. Recurrent tumours had a higher (P 0.05) S-phase fraction (SPF) (10.6 AE 4.6) than corresponding primary tumours from the same patients (7.0 AE 4.1) and the frequency of aneuploidy also increased from 8±55%. Recurrent tumours with AR gene ampli®cation had a signi®cantly higher (P 0.02) SPF (14.0 AE 6.5) than those with no ampli®cation (9.0 AE 2.9). The results suggest that clinical progression of prostate cancer during androgen withdrawal therapy is often associated with increased cell proliferation rate and formation of DNA aneuploidy. AR ampli®-cation may be an important molecular mechanism underlying the increase in proliferation rate of some recurrent tumours.

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Section: Discussionmentioning

confidence: 98%

Aneuploidy and rapid cell proliferation in recurrent prostate cancers with androgen receptor gene amplification

Koivisto

1997

Prostate Cancer Prostatic Dis

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“…It ranges from aneuploidy to various chromosomal aberrations including DNA ampli®cation. The latter chromosomal abnormality is not only characteristic for most tumor cells and is responsible for the frequent development of drug resistance in cancer treatments, but it is also often used as a relatively easily measurable indicator of genomic instability in experimental systems (for recent reviews see Hamlin et al, 1991;Stark, 1993;Wintersberger, 1994;Chernova et al, 1995). Normal cells (in particular normal diploid human cells) have a well functioning feedback or checkpoint system (for reviews see Lane, 1992;Hartwell, 1992;Hartwell and Kastan, 1994;Kaufmann and Paules, 1996) which prevents the multiplication of cells carrying genomic abnormalities.…”

Section: Introductionmentioning

confidence: 99%

Polyomavirus large T antigen-dependent DNA amplification

et al. 1997

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DNA ampli®cation is a readily measurable indicator for genome destabilization. Contrary to normal senescing cells, those of most immortal or transformed cell lines are karyotypically unstable and permissive for ampli®ca-tion. Permissivity for ampli®cation can be generated by gene products of several DNA tumor viruses whereby their interaction with the tumorsuppressor protein p53 is important. p53 is the major protein involved in check point control of DNA damage. Polyomavirus large T antigen is also involved in immortalization and transformation of cells but it does not interact with p53. We, therefore, examined whether this protein could still make the non-permissive cell line REF52 permissive for gene ampli®cation. To this end REF52 cell lines were constructed which conditionally expressed the wild type polyomavirus large T antigen or a mutant form unable to bind the retinoblastoma protein. Using the inhibitor of de novo pyrimidine biosynthesis, phosphonoacetyl-L-aspartate (PALA), as selective agent we found that PALA resistant cells arise with a frequency of about 5610 75 and that the interaction of polyomavirus large T protein with the retinoblastoma protein or another related pocket protein is important for this to occur. PALA resistant cells have an increased number of chromosomes and dicentric chromosomes which are considered as starting point for DNA structures characteristic for ampli®ed DNA. Such structures were indeed found with the help of uorescence in situ hybridization. PALA resistant cells appear normal with respect to p53. Our data indicate that PALA induces a G 1 block which can be partially overcome by polyomavirus large T protein by its interaction with E2F-pocket protein complexes providing further evidence that these complexes are downstream targets of p53.

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“…Amplification is extremely common in advanced tumors: the majority of mitotic chromosome spreads display either expanded, homogenously staining chromosome regions (HSRs) or small, acentric, autonomously replicating double minutes (DMs; reviewed in refs. [4][5][6][7][8]. In many cases, these structures have been shown to contain cellular oncogenes (reviewed in refs.…”

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confidence: 99%

Amplification of the human dihydrofolate reductase gene via double minutes is initiated by chromosome breaks

Singer

Mesner

Friedman

et al. 2000

Proc. Natl. Acad. Sci. U.S.A.

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120

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DNA sequence amplification is one of the most frequent manifestations of genomic instability in human tumors. We have shown previously that amplification of the dihydrofolate reductase (DHFR) gene in Chinese hamster cells is initiated by chromosome breaks, followed by bridge-breakage-fusion cycles that generate large intrachromosomal repeats; these are ultimately trimmed by an unknown process to smaller, more homogenous units manifested as homogenously staining chromosome regions (HSRs). However, in most human tumor cells, amplified DNA sequences are borne on unstable, extrachromosomal double minutes (DMs), which suggests the operation of a different amplification mechanism. In this study, we have isolated a large number of independent methotrexate-resistant human cell lines, all of which contained DHFR-bearing DMs. Surprisingly, all but one of these also had suffered partial or complete loss of one of the parental DHFR-bearing chromosomes. Cells in a few populations displayed what could be transient intermediates in the amplification process, including an initial HSR, its subsequent breakage, the appearance of DHFR-containing fragments, and, finally, DMs. Our studies suggest that HSRs and DMs both are initiated by chromosome breaks, but that cell types differ in how the extra sequences ultimately are processed and͞or maintained.

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Amplification of DNA Sequences in Mammalian Cells

Cited by 44 publications

References 186 publications

Aneuploidy and rapid cell proliferation in recurrent prostate cancers with androgen receptor gene amplification

Aneuploidy and rapid cell proliferation in recurrent prostate cancers with androgen receptor gene amplification

Polyomavirus large T antigen-dependent DNA amplification

Amplification of the human dihydrofolate reductase gene via double minutes is initiated by chromosome breaks

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