DNA repair gene polymorphisms, such as those of XRCC3 and xeroderma pigmentosum, complementation group D and G (XPD, XPG), contribute to carcinogenesis.
We assessed polymorphisms in the aryl hydrocarbon receptor (AhR-Arg554Lys), null variants of the glutathione S-transferase superfamily (GSTM1 and GSTT1), x-ray repair cross-complementing 1 and 3, and Xeroderma pigmentosum, group D (XRCC1-Arg399Gln, XRCC3-Thr241Met, XPD-Lys751Gln).
These cellular phenotypes are amenable to experimental strategies employing complementation, an approach previously used to demonstrate the correction of XP-D phenotypes following the introduction of the XPD (ERCC2) gene.
Nucleotide sequence analysis of the ERCC2 cDNA from five XP group D cell strains [XP6BE(SV40), XP17PV, XP102LO, A31-27 (a HeLa/XP102LO hybrid), and XP-CS-2] revealed mutations predominantly affecting previously identified functional domains.
For the most part, the authors found no association between these genes and the cancer sites investigated, except for some statistically significant associations between XPD/ERCC2 single nucleotide polymorphisms and skin, breast, and lung cancers.
No major modifications of the ERCC-2 gene were detected with two cDNA probes in either XP-D or TTD patients indicating that the association between TTD and XP-D is not likely to result from a large deletion or rearrangement involving this gene.
Two individuals with features of both xeroderma pigmentosum and trichothiodystrophy highlight the complexity of the clinical outcomes of mutations in the XPD gene.
The Xeroderma pigmentosum group D (XPD, also referred to as excision repair cross complementing gene 2, ERCC2) is one of key genes involved in nucleotide excision repair and two potentially functional polymorphisms of XPD (Asp312Asn and Lys751Gln) have been widely investigated in various cancers including prostate cancer.
Genome sequence analysis indicated that the patient harbored a compound heterozygous mutation of c.1621A>C and c.591_594del, resulting in p.S541R and p.Y197* in ERCC2: then, patient was diagnosed with XP-D. Y197* has not been described before.
Nucleotide sequence analysis of the ERCC2 cDNA from five XP group D cell strains [XP6BE(SV40), XP17PV, XP102LO, A31-27 (a HeLa/XP102LO hybrid), and XP-CS-2] revealed mutations predominantly affecting previously identified functional domains.
Thus, we are developing a model for gene therapy in XP, particularly for patients belonging to group D. We report here the construction of a retroviral vector (LXPDSN) containing the XPD (ERCC2) cDNA, which fully complements the DNA repair deficiency of primary skin fibroblasts.
In most cases, xeroderma pigmentosum group D (XP-D) and trichothiodystrophy (TTD) patients carry mutations in the carboxy-terminal domain of the evolutionarily conserved helicase XPD, which is one of the subunits of the transcription/repair factor TFIIH (refs 1,2).
To study the relationships between mutagenesis and carcinogenesis, we compared the mutations and their frequency induced by ultraviolet irradiation at 254 nm (UV-C) in XP-D (GM-08207B/XP6BE), TTD/XP-D (TTD1VI-LAS-KMT11) and wild-type (MRC-5V1) human cells.
When the genotype frequencies of XPD (Llys751Gln) and XRCC1 (Arg399Gln) genes were examined in the patient and control groups, no significant difference was detected, while a significant association was found in XRCC4 (VNTR in intron 3 and G-1394T) polymorphisms.
We investigated the genetic basis for these findings by analysing the Asp312Asn and Lys751Gln polymorphisms of the XPD (ERCC2) DNA repair gene in the same subjects.