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 3

I/R confers epigenetic HDR loss of function.

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I/R confers epigenetic HDR loss of function. Foci were scored as in Figu...
Foci were scored as in Figure 2 in asmase+/+ (WT) or asmase–/– (KO) hosts. (A) Canonical NHEJ is insensitive to SDRT-I/R. Left: Representative DNA-PKcs foci in MCA/129 fibrosarcomas 1 hour after 15 Gy SDRT. Right: Time-dependent change in DNA-PKcs and XRCC4 foci in SDRT-treated B16F1 melanomas. Scale bar: 20 μm. Data represent mean ± SEM collated from 2–4 independent experiments per panel of 3 mice per group. P > 0.05, WT vs. KO. (B) Time course of SUMO2/3, PIAS1, and BRCA1 focus accrual/resolution after 15 Gy SDRT in HCT116 xenografts. *P < 0.05, WT vs. KO unpaired t test. Data represent mean ± SEM collated from 2–4 independent experiments per panel of 3 mice per group. *P < 0.05, WT vs. KO. (C) Effects of SDRT-I/R injury (WT, WT+B+C, KO+C) versus SDRT-inert (WT+B, KO) settings on SUMO2/3 foci formation in HCT116 tumor xenografts at 6 hours after 15 Gy SDRT. BQ-123 (designated B), when used, was injected i.p. 30 minutes before SDRT, while mechanical percutaneous clamp (designated C) of large tumor-feeding vessels was used immediately after SDRT. Data represent median ± IQR percent foci-positive nuclei in tumor-derived histological specimens from 2–4 mice each, scoring a total of 2 × 103 to 7 × 103 HCT116 cells. ***P < 0.001, ****P < 0.0001 vs. WT, with Bonferroni correction (threshold: α = 0.05/4 = 0.0125). Inset shows representative SUMO2/3 focus images in respective SDRT-I/R–conditioned and I/R-inert. Scale bar: 20 μm.