title: Malignant melanoma cells acquire resistance to DNA interstrand cross-linking chemotherapeutics by p53-triggered upregulation of DDB2/XPC-mediated DNA repair.
abstract: Malignant melanoma is a cancer characterized by high chemoresistance although p53 is rarely mutated. Here, we show that p53 wild-type melanoma cells acquire resistance to cell death induced by fotemustine (FM), which is a representative of alkylating DNA interstrand cross-linking agents used in melanoma therapy. We show that drug-induced resistance is a result of p53-dependent upregulation of the nucleotide excision repair (NER) genes xeroderma pigmentosum complementation group C (XPC) and damaged DNA-binding protein 2 (DDB2), which stimulate the repair of DNA interstrand cross-links (ICLs) arising from O(6)-chloroethylguanine. Consequently, TP53 mutated cells are unable to repair ICLs, leading to prolonged ATM, ATR and checkpoint kinase 1 (CHK1) activation, and finally apoptosis. The roles of p53 and NER in ICL-triggered cell death were confirmed by knockdown of p53 and XPC. Upregulation of XPC and DDB2 in p53wt cells following a single drug treatment is a robust and sustained response that lasts for up to 1 week. Pretreatment with an inducing dose followed by a high and toxic dose of FM provoked an adaptive response as the killing outcome of the challenge dose was reduced. Upregulation of XPC and DDB2 was also observed in a melanoma mouse xenograft model following systemic administration of FM. Additionally, XPC and DDB2 induction occurred upon treatment with other cross-linking anticancer drugs, such as cisplatin and mafosfamide, indicating it is a general response of cancer cells to this group of chemotherapeutics. Collectively, the data indicate that p53-dependent upregulation of XPC and DDB2 is a key mechanism upon genotoxic stress, whereby melanoma cells acquire resistance towards DNA cross-linking agents. To our knowledge, this is the first demonstration of upregulation of NER following a single dose of a DNA interstrand cross-linker, which is a robust and long-lasting effect that impacts the killing response of cancer cells to subsequent treatments.
authors.affiliation: Institute of Toxicology, Medical Center of the University Mainz, Obere Zahlbacher Str. 67, Mainz, Germany.
authors.forename: C
authors.initials: C
authors.lastname: Barckhausen
authors.affiliation: Institute of Toxicology, Medical Center of the University Mainz, Obere Zahlbacher Str. 67, Mainz, Germany.
authors.forename: W P
authors.initials: WP
authors.lastname: Roos
authors.affiliation: Institute of Toxicology, Medical Center of the University Mainz, Obere Zahlbacher Str. 67, Mainz, Germany.
authors.forename: S C
authors.initials: SC
authors.lastname: Naumann
authors.affiliation: Institute of Toxicology, Medical Center of the University Mainz, Obere Zahlbacher Str. 67, Mainz, Germany.
authors.forename: B
authors.initials: B
authors.lastname: Kaina
mesh_terms: D000818:Animals; D000970:Antineoplastic Agents / Q000494:pharmacology; D045744:Cell Line, Tumor; D004249:DNA Damage / Q000235:genetics; D004260:DNA Repair / Q000235:genetics*; D004268:DNA-Binding Proteins / Q000096:biosynthesis / Q000235:genetics; D019008:Drug Resistance, Neoplasm / Q000235:genetics*; D005434:Flow Cytometry; D005455:Fluorescent Antibody Technique; D015972:Gene Expression Regulation, Neoplastic; D064593:Heterografts; D006801:Humans; D015151:Immunoblotting; D008545:Melanoma / Q000235:genetics* / Q000378:metabolism; D051379:Mice; D060888:Real-Time Polymerase Chain Reaction; D020133:Reverse Transcriptase Polymerase Chain Reaction; D016159:Tumor Suppressor Protein p53 / Q000235:genetics / Q000378:metabolism*; D015854:Up-Regulation
chemical_list: D000970:Antineoplastic Agents; C117669:DDB2 protein, human; D004268:DNA-Binding Proteins; D016159:Tumor Suppressor Protein p53; C086984:XPC protein, human