Regulation of DNA repair gene expression in human cancer cell lines.
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.
McGurk
Claire J
CJ
Prostate Cancer Research Centre, Institute of Urology, UCL, 3rd Floor Research Laboratories, London, W1W 7EJ, United Kingdom.
Cummings
Michele
M
Köberle
Beate
B
Hartley
John A
JA
Oliver
R Timothy
RT
Masters
John R
JR
D020413:3' Untranslated Regions; D020121:5' Untranslated Regions; D017398:Alternative Splicing; D015152:Blotting, Northern; D045744:Cell Line, Tumor; D002945:Cisplatin / Q000494:pharmacology*; D004260:DNA Repair / Q000502:physiology*; D004268:DNA-Binding Proteins / Q000235:genetics* / Q000378:metabolism; D004720:Endonucleases / Q000235:genetics* / Q000378:metabolism; D005786:Gene Expression Regulation; D006801:Humans; D008297:Male; D009369:Neoplasms / Q000235:genetics*; D011401:Promoter Regions, Genetic; D014176:Protein Biosynthesis / Q000235:genetics; D012333:RNA, Messenger / Q000378:metabolism*; D012097:Repressor Proteins / Q000235:genetics; D024363:Transcription Initiation Site; D014158:Transcription, Genetic; D051760:Xeroderma Pigmentosum Group A Protein / Q000378:metabolism
D020413:3' Untranslated Regions; D020121:5' Untranslated Regions; D004268:DNA-Binding Proteins; D012333:RNA, Messenger; D012097:Repressor Proteins; C497314:XPA protein, human; D051760:Xeroderma Pigmentosum Group A Protein; C095888:xeroderma pigmentosum group F protein; C071447:ERCC1 protein, human; D004720:Endonucleases; D002945:Cisplatin