The Combined Effects of Xeroderma Pigmentosum C Deficiency and Mutagens on Mutation Rates in the Mouse Germ Line

Miccoli, Laurent; Burr, Karen; Hickenbotham, Peter; Friedberg, Errol C.; Angulo, Jaime F.; Dubrova, Yuri E.

doi:10.1158/0008-5472.can-06-3844

Cited by 19 publications

(18 citation statements)

References 39 publications

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“…We therefore conclude that exposure to the anticancer drugs analyzed here does not affect the size of ESTR mutation changes. These data are in line with the results of our previous studies showing no difference in the structure of spontaneous and radiation-or ethylnitrosourea-induced ESTR mutants in the mouse germ line (37,38). We and others have previously hypothesized that ESTR mutation induction cannot be attributed to the direct targeting of these small genomic loci by ionizing radiation and chemical mutagens (8,9,13,14,39).…”

Section: Resultssupporting

confidence: 92%

Single-Molecule PCR Analysis of Germ Line Mutation Induction by Anticancer Drugs in Mice

2008

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Understanding and estimating the genetic hazards of exposure to chemical mutagens and anticancer drugs in humans requires the development of efficient systems for monitoring germ line mutation. The suitability of a single-molecule PCRbased approach for monitoring mutation induction at the mouse expanded simple tandem repeat (ESTR) locus Ms6-hm by chemical mutagens and anticancer drugs has been validated. The frequency of ESTR mutation was evaluated in the germ line of male mice exposed to the well-characterized alkylating agent and mutagen, ethylnitrosourea, and four widely used anticancer drugs, bleomycin, cyclophosphamide, mitomycin C, and procarbazine. The dose-response of ethylnitrosourea-induced mutation was found to be very close to that previously established using a pedigree-based approach for ESTR mutation detection. Paternal exposure to the clinically relevant doses of bleomycin (15-30 mg/kg), cyclophosphamide (40-80 mg/kg), and mitomycin C (2.5-5 mg/kg) led to statistically significant, dose-dependent increases in ESTR mutation frequencies in the germ line of treated male mice. Exposure to procarbazine led to a maximal increase in mutation frequency at 50 mg/kg, with a plateau at the higher concentrations. The results of this study show that the singlemolecule PCR technique provides a new and efficient experimental system for monitoring the genetic effects of anticancer drugs, capable of detecting increases in mutation rates at clinically relevant doses of exposure. In addition, this approach dramatically reduces the number of mice needed for the measurement of germ line mutation induction.

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Section: Resultssupporting

confidence: 92%

Single-Molecule PCR Analysis of Germ Line Mutation Induction by Anticancer Drugs in Mice

2008

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“…Therefore, in these patients, the cells accumulate mutations in nontranscribed parts of the genome, leading to neoplastic transformation (11). Notably, XPC-knockout mice have heightened predisposition to many types of UV-induced and spontaneous cancers (14,15), indicating that XPC plays a role in the removal of non-UV-related mutations as well. Moreover, lymphocytes from Xpc -/-mice accumulate spontaneous lesions in the hypoxanthine guanine phosphoribosyl transferase (Hprt) gene (16).…”

Section: Introductionmentioning

confidence: 99%

XPC silencing in normal human keratinocytes triggers metabolic alterations that drive the formation of squamous cell carcinomas

Rezvani

Kim²,

Rossignol³

et al. 2011

J. Clin. Invest.

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DNA damage is a well-known initiator of tumorigenesis. Studies have shown that most cancer cells rely on aerobic glycolysis for their bioenergetics. We sought to identify a molecular link between genomic mutations and metabolic alterations in neoplastic transformation. We took advantage of the intrinsic genomic instability arising in xeroderma pigmentosum C (XPC). The XPC protein plays a key role in recognizing DNA damage in nucleotide excision repair, and patients with XPC deficiency have increased incidence of skin cancer and other malignancies. In cultured human keratinocytes, we showed that lentivirus-mediated knockdown of XPC reduced mitochondrial oxidative phosphorylation and increased glycolysis, recapitulating cancer cell metabolism. Accumulation of unrepaired DNA following XPC silencing increased DNA-dependent protein kinase activity, which subsequently activated AKT1 and NADPH oxidase-1 (NOX1), resulting in ROS production and accumulation of specific deletions in mitochondrial DNA (mtDNA) over time. Subcutaneous injection of XPC-deficient keratinocytes into immunodeficient mice led to squamous cell carcinoma formation, demonstrating the tumorigenic potential of transduced cells. Conversely, simultaneous knockdown of either NOX1 or AKT1 blocked the neoplastic transformation induced by XPC silencing. Our results demonstrate that genomic instability resulting from XPC silencing results in activation of AKT1 and subsequently NOX1 to induce ROS generation, mtDNA deletions, and neoplastic transformation in human keratinocytes. IntroductionEarly studies of the metabolic changes that accompany the development of cancer led Otto Warburg to propose that a respiratory deficiency might drive neoplastic transformation (1), prompting many investigators to analyze the metabolism of tumor cells. These analyses revealed that a large number of cancer cell lines have a higher rate of glycolysis, an increased rate of glucose transport, increased pentose phosphate pathway (PPP) activity, decreased numbers of mitochondria, and a reduction in mitochondrial oxidative phosphorylation (OXPHOS) proteins and activities (2-4). These alterations in cancer cell energy metabolism could be related to somatic mutations in mitochondrial DNA (mtDNA); oxidative stress as a result of increased ROS level; adaptation to tissue hypoxia (4-7); the activation of oncogenes and/or inactivation of tumor suppressors (TP53,; as well as deregulation of PI3K/AKT, which influences the glycolytic flux through regulation of different factors (8).However, the etiologic relationship among genomic mutations, the Warburg effect, and increased ROS levels in tumor induction remains unclear (3,5,9). Furthermore, there is no clear mechanism(s) linking genomic mutations and modified cellular bioenergetics. To understand the relationships between these factors, we speculated that cells with heightened predisposition to malignant transformation, or cells with the capacity to accumu-

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“…Therefore, in these patients, that have proficient TCR and defective GGR, the cells accumulate mutations, notably UVB-induced photoproducts such as cyclobutane pyrimidine dimers (CPD) and 6-4 photoproducts (6-4pp), in non-transcribed parts of the genome, leading to neoplastic transformation [1]. It has also been shown that XPC knockout mice have heightened predisposition to many types of UV-induced and spontaneous cancers [5, 6], indicating that XPC plays a role in the removal of non-UV-related mutations as well. Moreover, lymphocytes from XPC −/− mice accumulate spontaneous lesions in the hypoxanthine guanine phosphoribosyl transferase (HPRT) gene [7].…”

Section: Introductionmentioning

confidence: 99%

XPC silencing in normal human keratinocytes triggers metabolic alterations through NOX-1 activation-mediated reactive oxygen species

Rezvani

Rossignol

Ali

et al. 2011

Biochimica et Biophysica Acta (BBA) - Bioenergetics

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Summary Cancer cells utilize complex mechanisms to remodel their bioenergetic properties. We exploited the intrinsic genomic stability of xeroderma pigmentosum C (XPC) to understand the interrelationships between genomic instability, reactive oxygen species (ROS) generation, and metabolic alterations during neoplastic transformation. We showed that knockdown of XPC (XPCKD) in normal human keratinocytes results in metabolism remodeling through NADPH oxidase-1 (NOX-1) activation, which in turn leads to increased ROS levels. While enforcing antioxidant defenses by overexpressing catalase, CuZnSOD, or MnSOD could not block the metabolism remodeling, impaired NOX-1 activation abrogates both alteration in ROS levels and modifications of energy metabolism. As NOX-1 activation is observed in human squamous cell carcinomas (SCCs), the blockade of NOX-1 could be a target for the prevention and the treatment of skin cancers.

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The Combined Effects of Xeroderma Pigmentosum C Deficiency and Mutagens on Mutation Rates in the Mouse Germ Line

Cited by 19 publications

References 39 publications

Single-Molecule PCR Analysis of Germ Line Mutation Induction by Anticancer Drugs in Mice

Single-Molecule PCR Analysis of Germ Line Mutation Induction by Anticancer Drugs in Mice

XPC silencing in normal human keratinocytes triggers metabolic alterations that drive the formation of squamous cell carcinomas

XPC silencing in normal human keratinocytes triggers metabolic alterations through NOX-1 activation-mediated reactive oxygen species

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