Single-dose radiotherapy disables tumor cell homologous recombination via ischemia/reperfusion injury
Sahra Bodo, … , Richard Kolesnick, Zvi Fuks
Sahra Bodo, … , Richard Kolesnick, Zvi Fuks
Published November 27, 2018
Citation Information: J Clin Invest. 2019;129(2):786-801. https://doi.org/10.1172/JCI97631.
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Research Article Oncology Vascular biology

Single-dose radiotherapy disables tumor cell homologous recombination via ischemia/reperfusion injury

Abstract

Tumor cure with conventional fractionated radiotherapy is 65%, dependent on tumor cell–autonomous gradual buildup of DNA double-strand break (DSB) misrepair. Here we report that single-dose radiotherapy (SDRT), a disruptive technique that ablates more than 90% of human cancers, operates a distinct dual-target mechanism, linking acid sphingomyelinase–mediated (ASMase-mediated) microvascular perfusion defects to DNA unrepair in tumor cells to confer tumor cell lethality. ASMase-mediated microcirculatory vasoconstriction after SDRT conferred an ischemic stress response within parenchymal tumor cells, with ROS triggering the evolutionarily conserved SUMO stress response, specifically depleting chromatin-associated free SUMO3. Whereas SUMO3, but not SUMO2, was indispensable for homology-directed repair (HDR) of DSBs, HDR loss of function after SDRT yielded DSB unrepair, chromosomal aberrations, and tumor clonogen demise. Vasoconstriction blockade with the endothelin-1 inhibitor BQ-123, or ROS scavenging after SDRT using peroxiredoxin-6 overexpression or the SOD mimetic tempol, prevented chromatin SUMO3 depletion, HDR loss of function, and SDRT tumor ablation. We also provide evidence of mouse-to-human translation of this biology in a randomized clinical trial, showing that 24 Gy SDRT, but not 3×9 Gy fractionation, coupled early tumor ischemia/reperfusion to human cancer ablation. The SDRT biology provides opportunities for mechanism-based selective tumor radiosensitization via accessing of SDRT/ASMase signaling, as current studies indicate that this pathway is tractable to pharmacologic intervention.

Authors

Sahra Bodo, Cécile Campagne, Tin Htwe Thin, Daniel S. Higginson, H. Alberto Vargas, Guoqiang Hua, John D. Fuller, Ellen Ackerstaff, James Russell, Zhigang Zhang, Stefan Klingler, HyungJoon Cho, Matthew G. Kaag, Yousef Mazaheri, Andreas Rimner, Katia Manova-Todorova, Boris Epel, Joan Zatcky, Cristian R. Cleary, Shyam S. Rao, Yoshiya Yamada, Michael J. Zelefsky, Howard J. Halpern, Jason A. Koutcher, Carlos Cordon-Cardo, Carlo Greco, Adriana Haimovitz-Friedman, Evis Sala, Simon N. Powell, Richard Kolesnick, Zvi Fuks

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Figure 6

ROS mediate SUMO dysfunction and synthetic tumor lethality via the reproductive death pathway.

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ROS mediate SUMO dysfunction and synthetic tumor lethality via the repro...
(A–E) Experiments were performed using MCA/129 fibrosarcoma. Data were collated from 2–4 independent experiments using 2–4 mice per experiment. (A) Representative images (left; scale bar: 20 μm) and quantitation (right; data represent mean ± 95% CI) of dihydroethidium staining (DHE, red) and DAPI counterstaining (blue) of tumors in asmase+/+ mice before and 1 hour after SDRT, with or without BQ-123 (designated B, 30 minutes before SDRT) or tempol (designated T, 30 minutes after SDRT). *P < 0.05, Bonferroni correction (threshold: α = 0.05/3 = 0.017). (B) Prdx6 overexpression or tempol abrogates the SSR induced by SDRT. Representative WBs of whole-cell lysates from tumors in asmase+/+ (WT) mice. (C) Tempol abrogates chromatin-associated SUMO3 depletion. Representative WB of chromatin-enriched extract from tumors in asmase+/+ mice. (D and E) Prdx6 overexpression or tempol abrogates delayed γH2AX focus resolution (D) and restores BRCA1 and RAD51 loading into repair foci (E) in SDRT-I/R–competent (WT or KO+C) tumors. Data represent median ± IQR. **P < 0.01, ****P < 0.0001 for all focus types vs. WT, Bonferroni correction (threshold: α = 0.05/8 = 0.00625). (F) Left: Representative images of micronuclei (MN; arrows) in H&E-stained tumor sections. Scale bar: 5 μm. Right: MN quantitation; data represent mean ± 95% CI from 3 independent experiments using 3 mice per group, 2,000 cells per tumor. *P < 0.05, **P < 0.01 for 15 Gy and 15 Gy + C vs. unirradiated WT, Bonferroni correction (threshold: α = 0.05/4 = 0.0125). (G) Ablation of MCA/129 fibrosarcomas in sv129/BL6 mice is aborted by pre-SDRT treatment with BQ-123 or post-SDRT treatment with tempol. Each line represents an individual tumor volume. Arrows indicate day of SDRT. Tumors undetectable at 120 days are considered cured.