Association of predicted pathogenic mutations in mitochondrial ND genes with distant metastasis in NSCLC and colon cancer

Nobuko Koshikawa,Keizo Takenaga,Jun-Ichi Hayashi,Miho Akimoto,Hiroki Nagase

doi:10.1038/s41598-017-15592-2

Nobuko Koshikawa, Keizo Takenaga + Show 3 more

Open Access

https://doi.org/10.1038/s41598-017-15592-2

Copy DOI

Abstract

Cancer cells have more mutations in their mitochondrial DNA (mtDNA) than do normal cells, and pathogenic mutations in the genes encoding mitochondrial NADH dehydrogenase (ND) subunits have been found to enhance the invasive and metastatic ability of various tumour cells in animal experiments. However, it is unknown whether single-nucleotide variants (SNVs) of the ND genes that decrease complex I activity are involved in distant metastasis in human clinical samples. Here, we demonstrated the enhancement of the distant metastasis of Lewis lung carcinoma cells by the ND6 13885insC mutation, which is accompanied by the overexpression of metastasis-related genes, metabolic reprogramming, the enhancement of tumour angiogenesis and the acquisition of resistance to stress-induced cell death. We then sequenced ND genes in primary tumour lesions with or without distant metastases as well as metastatic tumour lesions from 115 patients with non-small cell lung cancer (NSCLC) and colon cancer, and we subsequently selected 14 SNVs with the potential to decrease complex I activity. Intriguingly, a significant correlation was observed (P < 0.05 by Chi-square test) between the incidence of the selected mutations and distant metastasis. Thus, these results strongly suggest that pathogenic ND gene mutations participate in enhancing distant metastasis in human cancers.

Highlights

Mitochondrial complex I is the large membrane protein complex of the respiratory chain[1], whose central subunits are well conserved from bacteria to humans
We focused on nonsynonymous single-nucleotide variants (SNVs) and single-nucleotide polymorphisms (SNPs) (SNVs observed in at least 1% of the population were defined as SNPs in this study) in the NADH dehydrogenase (ND) genes of non-small cell lung cancer (NSCLC) and colon cancer and selected candidate SNVs and SNPs with a high probability of reducing complex I activity, on the basis of the Grantham value; the evolutionary conservation of the original amino acid residue; the effect of the altered amino acid residue on protein structure; reported disease associations; and the predicted pathogenicity score
We have previously shown that P29mtB82M cells harbouring a 13885insC mutation in the ND6 gene show lower complex I activity, produce a larger amount of reactive oxygen species (ROS), and exhibit higher lung-colonizing ability than do P29mtP29 cells with wild-type mtDNA6

Summary

Introduction

Mitochondrial complex I is the large membrane protein complex of the respiratory chain[1], whose central subunits are well conserved from bacteria to humans. It is uncertain why reduction of complex I activity is mostly reported to be associated with invasion and metastasis It remains unclear whether ND gene mutations, which decrease complex I activity, are associated with distant metastasis in human cancers. We focused on nonsynonymous single-nucleotide variants (SNVs) and single-nucleotide polymorphisms (SNPs) (SNVs observed in at least 1% of the population were defined as SNPs in this study) in the ND genes of non-small cell lung cancer (NSCLC) and colon cancer and selected candidate SNVs and SNPs with a high probability of reducing complex I activity, on the basis of the Grantham value; the evolutionary conservation of the original amino acid residue; the effect of the altered amino acid residue on protein structure; reported disease associations; and the predicted pathogenicity score. The results showed that the incidence of the selected nonsynonymous SNVs and SNPs predicted to decrease complex I activity was significantly associated with distant metastasis

Methods

Results

Conclusion