Integrative genomic and proteomic analyses identifies glycerol-3-phosphate acyltransferase as a target of low-dose ionizing radiation in EBV infected-B cells

Abstract

Purpose: We sought to gain a better understanding of the low-dose ionizing radiation (LDIR)-induced molecular changes in transformed pre-malignant cells in their microenvironment.

Materials and methods: The cellular response to LDIR was compared and contrasted using immortalized human Epstein-Barr virus-infected B-cells (EBV-B) in mono-culture, co-culture with human bone marrow derived stromal cells (MSC), or under the LDIR-induced bystander effect. The resulting alterations in protein and gene expression (including microRNA, miRNA) were evaluated by isobaric tags for relative and absolute quantification (iTRAQ) proteomics assay, western blot, cDNA array and quantitative reverse transcription polymerase chain reaction (RT-PCR), respectively.

Results: The miRNAs let7a, miR-15b, miR-16, and miR-21, and a lipid metabolic miRNA hub miR-23b, were upregulated after LDIR exposure in the mono-cultured EBV-B cells, but were downregulated in EBV-B cells co-irradiated with MSC. A lipid biosynthesis enzyme glycerol-3-phosphate acyltransferase, the common target of these miRNA, was downregulated at the level of protein and mRNA expression in the LDIR-exposed, mono-cultured EBV-B cells and upregulated MSC co-cultured EBV-B cells.

Conclusions: These results suggest a putative miRNA regulatory mechanism controlling the LDIR-induced stress response, and illustrate that LDIR exposure, and the cell’s microenvironment, can affect specific gene expression, both directly and indirectly, resulting in altered protein expression.

Keywords:

• Low-dose ionizing radiation (LDIR)
• glycerol-3-phosphate acyltransferase (GPAM)
• Epstein-Barr virus-infected B-cells (EBV-B)
• microRNA (miRNA)
• isobaric tags for relative and absolute quantification (iTRAQ)

Acknowledgements

The authors wish to thank Drs Hideki Hayashi and Masayuki Tanaka, Support Center for Medical Research and Education, Tokai University, Kaori Saitoh, Tomomi Ikeda and Akemi Kawasaki for technical assistance. We thank the Laboratories of Molecular and Biochemical Research and Cell Biology, Research Support Center, Juntendo University Graduate School of Medicine for use of their facilities. We thank Kathryn Hale for manuscript review and Numsen Hail Jr for help in the preparation of the manuscript. This work was supported in part by the Grant-in-Aid for Scientific Research (C), Japan and by Grant-in-Aid (S1311011) from the Foundation of Strategic Research Projects in Private Universities from the MEXT, Japan (to Y.T.).

Declaration of interest

The authors report no conflict of interest. The authors alone are responsible for the content and writing of the paper.

Supplementary material available online Supplementary tables 1 & 2 and figure 1 available online at http://dx.doi.org/10.3109/09553002.2015.1106021