Cotargeting DNA topoisomerase II enhances efficacy of RAS-targeted therapy in KRAS-mutant cancer models
Rongzhong Xu, Dongsheng Wang, Guangzhi Ma, Xun Yuan, Qian Chu, Songqing Fan, Rener Zhang, Pan Du, Shidong Jia, Ticiana A. Leal, Suresh S. Ramalingam, Zhen Chen, Shi-Yong Sun
Rongzhong Xu, Dongsheng Wang, Guangzhi Ma, Xun Yuan, Qian Chu, Songqing Fan, Rener Zhang, Pan Du, Shidong Jia, Ticiana A. Leal, Suresh S. Ramalingam, Zhen Chen, Shi-Yong Sun
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Research Article Cell biology Oncology

Cotargeting DNA topoisomerase II enhances efficacy of RAS-targeted therapy in KRAS-mutant cancer models

Abstract

The approval of sotorasib and adagrasib as the first KRAS G12C inhibitors has made the RAS oncogene a druggable target. However, they have modest objective response rates and short response durations. Therefore, strategies for improving RAS-targeted cancer therapy are urgently needed. Here, we found that both sotorasib and adagrasib promoted topoisomerase IIα (Topo IIα) proteasomal degradation in KRAS G12C–mutant cancer cells and induced DNA damage and apoptosis. In cell lines with acquired resistance to sotorasib, elevated Topo IIα levels were detected. TOP2A overexpression in sensitive KRAS G12C–mutant cells conferred resistance to sotorasib, whereas TOP2A knockdown in sotorasib-resistant cell lines sensitized the cells to sotorasib. Moreover, the combination of a KRAS G12C inhibitor such as sotorasib with a Topo II inhibitor such as VP-16 synergistically decreased the survival of sotorasib-resistant RAS G12C–mutant cells with augmented induction of DNA damage and apoptosis, effectively inhibited the growth of sotorasib-resistant tumors, and delayed or prevented the emergence of acquired resistance to sotorasib in vivo. Collectively, our results reveal an essential role of Topo IIα inhibition in mediating the therapeutic efficacy of RAS-targeted cancer therapy, providing a strong scientific rationale for targeting Topo II to improve RAS-targeted cancer therapies.

Authors

Rongzhong Xu, Dongsheng Wang, Guangzhi Ma, Xun Yuan, Qian Chu, Songqing Fan, Rener Zhang, Pan Du, Shidong Jia, Ticiana A. Leal, Suresh S. Ramalingam, Zhen Chen, Shi-Yong Sun

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Figure 2

KRAS G12C inhibitors decrease Topo IIα levels through inducing GSK3-dependent and FBXW7-mediated proteasomal degradation.

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KRAS G12C inhibitors decrease Topo IIα levels through inducing GSK3-depe...
(A) The tested cell lines were pretreated with 10 μM MG132 for 30 minutes and then cotreated with DMSO, 500 nM sotorasib (Soto), or 250 nM adagrasib (Adag) for another 6 hours. (B) The indicated cell lines were treated with 500 nM sotorasib or adagrasib for 16 hours followed by the addition of 10 μg/mL CHX and then harvested at the indicated times. (C) The tested cell lines were pretreated with 10 μM CHIR99021 or SB216763 for 30 minutes and then cotreated with 500 nM sotorasib for an additional 16 hours. (D and E) Both H358 and Calu-1 cells were transfected with scrambled control, GSK3 (D), or FBXW7 (E) siRNA for 48 hours followed by treatment with 500 nM sotorasib for another 24 hours. Proteins in the treated cells were detected by Western blotting. Band intensities were quantified using ImageJ software (NIH) and plotted as a percentage of 0 time point (B). (F) Schematic illustration of KRAS G12C inhibition-induced GSK3-dependent and FBXW7-mediated degradation of Topo IIα in KRAS G12C–mutant cancer cells. G12Ci, G12C inhibitor.