mRNA and small RNA gene expression changes in peripheral blood to detect internal Ra-223 exposure

Abstract

Purpose

Excretion analysis is the established method for detection of incorporated alpha-emitting radionuclides, but it is laborious and time consuming. We sought a simplified method in which changes in gene expression might be measured in human peripheral blood to detect incorporated radionuclides. Such an approach could be used to quickly determine internal exposure in instances of a radiological dispersal device or a radiation accident.

Materials and methods

We evaluated whole blood samples from five patients with castration-resistant prostate cancer and multiple bone metastases (without visceral or nodal involvement), who underwent treatment with the alpha emitting isotope Radium-223 dichloride (Ra-223, Xofigo^®). Patients received about 4 MBq per cycle and, depending on survival and treatment tolerance, were followed for six months. We collected 24 blood samples approximately monthly corresponding to treatment cycle.

Results

Firstly, we conducted whole genome screening of mRNAs (mRNA seq) and small RNAs (small RNA seq) using next generation sequencing in one patient at eight different time points during all six cycles of Ra-223-therapy. We identified 1900 mRNAs and 972 small RNAs (222 miRNAs) that were differentially up- or down-regulated during follow-up after the first treatment with Ra-223. Overall candidate RNA species inclusion criteria were a general (≥|2|-fold) change or with peaking profiles (≥|5|-fold) at specific points in time. Next we chose 72 candidate mRNAs and 101 small RNAs (comprising 29 miRNAs) for methodologic (n = 8 samples, one patient) and independent (n = 16 samples, four patients) validation by qRT-PCR. In total, 15 mRNAs (but no small RNAs) were validated by methodologic and independent testing. However, the deregulation occurred at different time points, showing a large inter-individual variability in response among patients.

Conclusions

This proof of concept provides support for the applicability of gene expression measurements to detect internalized alpha-emitting radionuclides, but further work is needed with a larger sample size. While our approach has merit for internal deposition monitoring, it was complicated by the severe clinical condition of the patients we studied.

Keywords:

• Incorporation
• alpha-emitter
• peripheral blood
• biomarker
• gene expression changes
• mRNA
• small RNA
• Ra-223
• prostate cancer
• Xofigo

Data availability statement

The datasets generated and analyzed in the course of the current study are available from the corresponding author on request.

Acknowledgements

We appreciate the sophisticated and carefully performed technical assistance of Sven Doucha-Senf, Thomas Müller and Oliver Wittmann.

Author contributions

Patrick Ostheim and Michael Abend wrote the main manuscript text and prepared the figures, tables and supplement table. Tim Nestler, Matthias Miederer and Manuela A. Hoffmann contributed to the conception of the study. Alexis Rump, Michael Lassmann and Uta Eberlein performed the dose reconstructions. Alexis Rump, Michael Lassmann, Uta Eberlein, Matthias Miederer, Mathias Schreckenberger, Tim Nestler, Manuela A. Hoffmann, Vahe Barsegian, Matthaeus Majewski and Matthias Port revised the work. All authors reviewed the manuscript.

Disclosure statement

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

Additional information

Funding

This work was supported by the German Ministry of Defense.

Notes on contributors

Patrick Ostheim

Patrick Ostheim, MD, is a Post-Doctoral Researcher of Radiobiology and a Resident in Radiology at the Bundeswehr Institute of Radiobiology, Munich, Germany.

Matthias Miederer

Matthias Miederer, MD, is a Senior Physician and Senior Scientist at the Clinic and Polyclinic for Nuclear Medicine, University Medical Center of the Johannes Gutenberg University, Mainz, Germany.

Mathias Schreckenberger

Mathias Schreckenberger, MD, is a Professor of Nuclear Medicine and Head of the Clinic and Polyclinic for Nuclear Medicine, University Medical Center of the Johannes Gutenberg University, Mainz, Germany.

Tim Nestler

Tim Nestler, MD, is an Assistant Professor of Urology and Consultant at the Department of Urology, Federal Armed Services Hospital Koblenz, Koblenz, Germany.

Manuela A. Hoffmann

Manuela A. Hoffmann, MD, is a Senior Scientist of Nuclear Medicine and Occupational physician at the Clinic and Polyclinic for Nuclear Medicine, University Medical Center of the Johannes Gutenberg University, Mainz, Germany and Deputy Branch Chief at the Federal Ministry of Defense, Department of Occupational Health & Safety, Bonn, Germany.

Michael Lassmann

Michael Lassmann, PhD, is a Professor of Medical Physics and senior scientist at the Department of Nuclear Medicine, University of Würzburg, Germany.

Uta Eberlein

Uta Eberlein, PhD, is a Post-Doctoral Researcher and Physicist at the Department of Nuclear Medicine, University of Würzburg, Germany.

Vahe Barsegian

Vahe Barsegian, MD, is a Professor of Nuclear Medicine and Head of the Institute of Nuclear Medicine, Helios Kliniken, Schwerin, Germany.

Alexis Rump

Alexis Rump, MD, is a Senior Scientist of Radiobiology and Anesthesiologist at the Bundeswehr Institute of Radiobiology, Munich, Germany.

Mattháus Majewski

Matthäus Majewski, MD, is a Resident in Urology at the Department of Urology, Armed Services Hospital Ulm, Germany.

Matthias Port

Matthias Port, MD, is a Professor of Radiobiology and Internal Medicine and Head of the Bundeswehr Institute of Radiobiology, Munich, Germany.

Michael Abend

Michael Abend, MD, is a Professor of Radiobiology and Deputy Head of the Bundeswehr Institute of Radiobiology, Munich, Germany.