Different splicing isoforms of ERCC1 affect the expression of its overlapping genes CD3EAP and PPP1R13L, and indicate a potential application in non-small cell lung cancer treatment

Abstract

Numerous genes are arranged in complex overlapping and interlaced patterns, and such arrangements potentially contribute to the regulation of gene expression. Previous studies have demonstrated that a region in chromosome 19q13.2-3 encompassing the overlapping genes excision repair cross-complementation group1 (ERCC1), CD3e molecule associated protein (CD3EAP) and protein phosphatase1 regulatory subunit13 like (PPP1R13L) was found to be associated with the risk and prognosis of non-small cell lung cancer (NSCLC). The present study confirmed the hypothesis that there are co-expression patterns among these overlapping genes. The suggestive bioinformatic evidence of The Cancer Genome Atlas was verified by quantitative polymerase chain reaction(qPCR) analysis of NSCLC tissue samples. In addition, a cisplatin-induced DNA damage cell model was assessed by microarray analysis, qPCR and 3'rapid amplification of cDNA ends (3'RACE) to verify and quantify the expression levels of co-expressed alternative splicing isoforms in the NSCLC tissues, as well as in cancer A549 and normal 16HBE cells. The expression of CD3EAP exon1 was demonstrated to be significantly associated with PPP1R13L exon1, while CD3EAP exon3 was significantly associated with ERCC1 exon11 in normal and NSCLC tissues. It was observed that short transcripts of ERCC1, CD3EAP and PPP1R13L are co-expressed in A549 cells and full-length transcripts are co-expressed in 16HBE cells. Furthermore, a novel transcriptional regulation pattern was described based on the positional associations of overlapping genes. The region encompassing the overlapping genes ERCC1, CD3EAP and PPP1R13L may be involved in linking the upstream and downstream genes, while the different splicing isoforms of ERCC1 affect the expression of its overlapping genes, suggesting potential application in cisplatin resistance in NSCLC treatment.