High and Low Doses of Ionizing Radiation Induce Different Secretome Profiles in a Human Skin Model

Qibin Zhang,Melissa Matzke,Zeping Hu,Bobbie-Jo Webb-Robertson,Ronald J Moore,Wei-Jun Qian,Matthew E Monroe,Athena A Schepmoes,William F Morgan,Richard D Smith,Gayle E Woloschak

doi:10.1371/journal.pone.0092332

Abstract

It is postulated that secreted soluble factors are important contributors of bystander effect and adaptive responses observed in low dose ionizing radiation. Using multidimensional liquid chromatography-mass spectrometry based proteomics, we quantified the changes of skin tissue secretome – the proteins secreted from a full thickness, reconstituted 3-dimensional skin tissue model 48 hr after exposure to 3, 10 and 200 cGy of X-rays. Overall, 135 proteins showed statistical significant difference between the sham (0 cGy) and any of the irradiated groups (3, 10 or 200 cGy) on the basis of Dunnett adjusted t-test; among these, 97 proteins showed a trend of downregulation and 9 proteins showed a trend of upregulation with increasing radiation dose. In addition, there were 21 and 8 proteins observed to have irregular trends with the 10 cGy irradiated group either having the highest or the lowest level among all three radiated doses. Moreover, two proteins, carboxypeptidase E and ubiquitin carboxyl-terminal hydrolase isozyme L1 were sensitive to ionizing radiation, but relatively independent of radiation dose. Conversely, proteasome activator complex subunit 2 protein appeared to be sensitive to the dose of radiation, as rapid upregulation of this protein was observed when radiation doses were increased from 3, to 10 or 200 cGy. These results suggest that different mechanisms of action exist at the secretome level for low and high doses of ionizing radiation.

Highlights

Both natural and man-made sources of ionizing radiation contribute to human exposure and pose a possible risk to human health
Ionizing radiation-induced cancer risks at low doses have been extrapolated from high dose studies, for which the effects on human health and biological systems are well documented, based on a linear no threshold dose-response model between radiation dose and effects;[3,4,5] recent literature suggests that the mechanisms of action for many biological endpoints may be different at low doses from those observed at high doses.[6,7,8,9,10,11]
Using advanced LC-MS based proteomics technologies, we present a comprehensive profiling of proteins secreted into culturing medium by a model 3D human skin tissue upon various doses of X-ray irradiation

Summary

Introduction

Both natural and man-made sources of ionizing radiation contribute to human exposure and pose a possible risk to human health. Secreted proteins play key roles in cell–cell signalling, communication, migration and growth, as they reflect the various stages of biological and pathological conditions.[12] Secreted soluble factors have long been postulated as the contributor of bystander effects observed from both in vitro and in vivo studies following ionizing radiation, where detrimental health effects of radiation exposure occur on neighbouring cells of the irradiated cells.[13] Many past studies on secreted factors were focused on a limited number of known proteins using targeted biochemical assays of Western-Blot, ELISA or protein microarrays;[14,15] despite decades of study, the identities of these secreted factors remain elusive

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Conclusion