Regulation of DNA repair gene expression in human cancer cell lines

Abstract

Although most advanced cancers are incurable, the majority of testicular germ cell tumors can be cured using cisplatin-based combination chemotherapy. The nucleotide excision repair (NER) pathway removes most DNA adducts produced by cisplatin, and the low levels of NER in testis tumor cells may explain why these cancers are curable. Three NER proteins: ERCC1, XPF, and XPA, are present at low levels in testis tumor cell lines, and addition of these proteins to protein extracts of testis tumor cells increases their in vitro DNA repair capacity to normal levels. The aim of this study was to identify the mechanism responsible for the low levels of these DNA repair proteins. The levels of the mRNA transcripts for ERCC1, XPF, and XPA were measured in a panel of 14 different human cancer cell lines, using real-time PCR. Three ERCC1 splice variants were identified and quantitated. Three alternative transcription start points (TSPs) were identified for ERCC1 but none were testis-specific. The significantly lower levels of ERCC1, XPF, and XPA protein in testis tumor cell lines cannot be explained solely by differences in transcriptional efficiency or mRNA stability. For ERCC1, post-transcriptional control by alternative splicing does not account for the testis-specific low levels of protein expression. Pulse-chase experiments showed that the half-life of ERCC1 protein in a testis tumor cell line was not significantly different to that in a prostate cancer cell line. Taken together, these results suggest that constitutive levels of these DNA repair proteins are controlled at the level of translation.

Predictive biomarkers for combined chemotherapy with 5‑fluorouracil and cisplatin in oro‑ and hypopharyngeal cancers

“…ERCC1 dimerizes with xeroderma pigmentosum complementation group F to form a complex that is required for excising the damaged DNA (15). XPA is a protein involved in the initial damage recognition and recruitment stage of the NER pathway (20). A previous study investigating the contribution of the XPA-binding region of ERCC1 on NER activity showed that the interaction between ERCC1 and XPA was essential for NER (21).…”

Thymidylate Synthase Expression in Gastroenteropancreatic and Pulmonary Neuroendocrine Tumors

“…To further normalize across samples, the highest DC t value was subtracted from each DC t to give the DDC t values. These values were converted to relative expression levels by the following formula: 2 -DDC t (29). The sequences of the primers and probe used were as follows (30) Data analysis.…”

Revisiting DNA damage repair, p53-mediated apoptosis and cisplatin sensitivity in germ cell tumors

“…Using atomic spectroscopy and alkaline elution, Bedford demonstrated that following treatment with cisplatin, bladder cancer cells were able to repair most of the DNA damage, while TGCTs could not (Bedford et al, 1988). Some years later, Koberle and co-workers confirmed this observation (Koberle et al, 1997, Koberle et al, 1999, Koberle et al, 1996, and proposed that reduced NER proficiency was caused by the reduced expression of xeroderma pigmentosum, complementation group A (XPA), XPF and ERCC1 (Welsh et al, 2004); likely due to reduced translation of these proteins (McGurk et al, 2006). However, a later study found that increasing the level of XPA protein in cisplatin-sensitive TGCT cell lines was insufficient to induce resistance to cisplatin or ultraviolet (UV) damage (Koberle et al, 2008).. Interestingly however, different findings were observed for ERCC1-XPF proteins.…”