Analysis of the nuclear localization signal of TRF1 in non-small cell lung cancer

Abstract

Several studies revealed a similar down-regulation of telomeric repeat binding factor 1 (TRF1) in tumors. We have previously reported the TRF1 expression levels were down-regulation in non-small cell lung cancer (NSCLC). The regulation of TRF1 localization is proposed to be important for the function and expression. The nuclear localization signal (NLS) and nuclear export signal (NES) are often important clues to localization of protein. The objective of the present study was to investigate the NLS and NES of TRF1 in NSCLC patients. Thirty (30) patients with NSCLCs had undergone radical operations in The First Affiliated Hospital, College of Medicine, Zhejiang University. DNA sequences of NLSs and NESs were amplified by PCR. The PCR products were analyzed by DNA sequencing. There were four NLSs of the TRF1 protein, including two monopartite and two bipartite NLSs. The NLSs sequences were included in 337KKERRVGTPQSTKKKKESRR356. The exon 8 and exon 9 of TRF1 DNA were covered the NLS sequences. The sequences of predicted NESs were 77WMLDFLCLSL86 and 174NLIKIQAIAV183, respectively. The exon 1, exon 3 and exon 4 of TRF1 were covered the NES sequences. In NSCLCs, there was no a mutation, deletion, or substitution in NLS and NES of TRF1. We conclude that the NLS and NES sequences in NSCLCs patients did not have mutations. Down-expression of TRF1 does not indicate gene mutation of NLS and NES in NSCLCs.