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

Abstract

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.

Oxidative DNA Damage and Nucleotide Excision Repair

“…XPC silencing did not interfere with repair of arsenic-induced DNA damage, but caused increased arsenic susceptibility by disturbing redox homeostasis, as was suggested by Liu et al (52). In addition, in normal human keratinocytes, the down-regulation of XPC resulted in increased intracellular ROS levels, genomic and mtDNA oxidation, and altered metabolism (65). It could, therefore, also be possible that, besides decreased repair of oxidative lesions, the hypersensitivity to oxidative stress in cells defective in XPC can at least partly be due to altered oxidative metabolism, resulting in an increased production of ROS.…”

Loss of epidermal hypoxia-inducible factor-1α accelerates epidermal aging and affects re-epithelialization in human and mouse

“…Keratinocytes were isolated from normal human skin of patients undergoing plastic surgery as previously described (Rezvani et al, 2006;Rezvani et al, 2011c). Briefly, fresh skin fragments were immediately cut into 565 mm pieces and treated with trypsin for 3 hours at 37˚C or overnight at 4˚C to separate the epidermis from the dermis.…”

Lexeroderma pigmentosum

“…En effet, notre étude montre que l'accumulation de mutations n'est pas suffisante seule pour l'induction de la transformation tumorale des kératinocytes XPC KD et que l'augmentation du niveau des ERO et les changements métaboli-ques sont indispensables pour ce processus. Comme l'activation de NOX a été constatée dans plusieurs tumeurs [9,13], l'inhibition de cette activation pourrait être une piste originale pour la prévention et la thérapie des cancers liés à une augmentation des ERO. ‡ Xeroderma pigmentosum: a useful model to study the relation between genomic mutations and cell transformation ERO, les délétions de l'ADN mitochondrial, les modifications métaboliques ainsi que la transformation tumorale des kératino-cytes XPC KD (Figure 2) [9,10].…”

“…Comme l'activation de NOX a été constatée dans plusieurs tumeurs [9,13], l'inhibition de cette activation pourrait être une piste originale pour la prévention et la thérapie des cancers liés à une augmentation des ERO. ‡ Xeroderma pigmentosum: a useful model to study the relation between genomic mutations and cell transformation ERO, les délétions de l'ADN mitochondrial, les modifications métaboliques ainsi que la transformation tumorale des kératino-cytes XPC KD (Figure 2) [9,10]. Compte tenu de l'importance de l'activation de NOX1 dans la transformation tumorale des kératinocytes XPC KD , nous nous sommes intéressés au mécanisme de cette activation.…”

“…Notre approche [9,10] a été d'analyser le comportement métabolique et la transformation tumorale des kératino-cytes normaux lorsqu'on invalide l'expression de XPC en utilisant des vecteurs lentiviraux qui expriment des petits ARN en « épingle à cheveux » (shRNA) (Figure 2). …”