Effects of cyclophosphamide and mitomycin C on radiation-induced transcriptional biomarkers in human lymphoblastoid cells

Abstract

Purpose

Ionizing radiation (IR)-induced transcriptional changes are considered a potential biodosimetry for dose evaluation and health risk monitoring of acute or chronic radiation exposure. It is crucial to understand the impact of confounding factors on the radiation-responsive gene expressions for accurate and reproducible dose assessment. This study aims to explore the potential influence of exposures to chemotherapeutic agents such as cyclophosphamide (CP) and mitomycin C (MMC) on IR-induced transcriptional biomarkers.

Methods

The human B lymphoblastoid cells (AHH-1) were exposed to 0, 20, 50, 100, 200 and 500 μg/ml CP or 0, 0.025, 0.05, 0.1 and 1 μg/ml MMC, respectively. The appropriate concentrations of CP and MMC were added for 1 h before irradiation with 0, 2, 4 and 6 Gy of ⁶⁰Co γ-rays at a dose rate of 1 Gy/min. Cell viability was evaluated by CCK-8 assay. The gene expression responses of 18 radiation-induced transcriptional biomarkers were examined at 24 h after exposures to CP and MMC, respectively. The expression levels of five crucial DNA interstrand crosslinks (ICLs) repair genes were also evaluated. The biodosimetry models were established based on the specific radiation-responsive gene combinations.

Results

The baseline transcriptional levels of the 18 selected genes were slightly affected by CP treatment in the absence of IR, while the transcript responses to IR could be inhibited as the concentration of CP up to 50 μg/ml. MMC treatment up-regulated the background levels in most radiation-responsive gene expressions. Of 18 genes, only the relative mRNA expression levels of CDKN1A and BBC3 were repressed after treatment with IR and MMC in combination. The relative mRNA level of RAD51 was significantly up-regulated after exposure to CP, while the expression of FANCD2, RAD51 and BLM showed an overall increase in response to MMC treatment. After irradiation, the relative mRNA expression levels of FANCD2, BRCA2 and RAD51 exhibited dose-dependent increases in IR alone and MMC treatment groups. In addition, the biodosimetry models were established using 2-4 radiation-responsive genes based on different radiation exposure scenarios.

Conclusion

Our findings suggested that IR-induced gene expression changes were slightly affected after exposure to a relatively low concentration of CP and MMC. Gene expression combinations might improve the broad applicability of transcriptional biodosimetry across diverse radiation exposures.

Keywords:

• Cyclophosphamide
• mitomycin C
• ionizing radiation
• gene expression
• biodosimetry

Author contributions

S.L. designed the study, performed the qRT-PCR experiments, processed the data and drafted the manuscript; T.J.C. performed the chemical treatment experiments and collected the data; X.L. cultured the cells; M.T. reviewed and supervised the study; Q.J.L. designed, reviewed and supervised the manuscript. All contributing authors approved and agreed with the final manuscript.

Disclosure statement

No potential conflict of interest was reported by the author(s).

Data availability statement

The data presented in this study are available on request to the corresponding author.

Correction Statement

This article has been corrected with minor changes. These changes do not impact the academic content of the article.

Additional information

Funding

This work was supported by the National Natural Science Foundation of China (grant No. 82173464, 81803162 and 82173463).

Notes on contributors

Shuang Li

Shuang Li, MD. She is an Associate Researcher in the Department of Radiobiology, National Institute for Radiological Protection, Chinese Center for Disease Control and Prevention.

Tian-Jing Cai

Tian-Jiing Cai, MPH. She is an Associate Researcher in the Department of Radiobiology, National Institute for Radiological Protection, Chinese Center for Disease Control and Prevention.

Xue Lu

Xue Lu, BA. She is an Senior Technician in the Department of Radiobiology, National Institute for Radiological Protection, Chinese Center for Disease Control and Prevention.

Mei Tian

Mei Tian, PhD. She is a Chief of the Department of Radiobiology, National Institute for Radiological Protection, Chinese Center for Disease Control and Prevention.

Qing-Jie Liu

Qing-Jie Liu, MD/PhD. He is a professor of Radiobiology, Deputy Director General, National Institute for Radiological Protection, Chinese Center for Disease Control and Prevention. His research fields are the biological effects of radiation medicine.