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
View: Text | PDF
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

×

Figure 4

Sotorasib combined with VP-16 synergistically decreases cell survival, augments induction of apoptosis and DNA damage, and enhances suppression of tumor growth in vivo.

Options: View larger image (or click on image) Download as PowerPoint
Sotorasib combined with VP-16 synergistically decreases cell survival, a...
(A) The tested cell lines were treated with varied concentrations of agents either alone or in combinations for 3 days. Cell numbers were measured by SRB assay, and CIs were calculated and presented inside the graph. Data are shown as the mean ± SD of 4 replicate determinations. (B) The tested cell lines were treated with 200 nM (H1792) or 20 nM (H358) sotorasib, 500 nM VP-16, or their combination. These treatments were repeated with fresh medium every 3 days. After 10 days, the cells were fixed, stained, and photographed. Data are shown as the mean ± SD of triplicate treatments. (C–E) H1792 cells were exposed to 1 μM sotorasib, 2.5 μM VP-16, or their combination for 48 hours. γ-H2AX foci were detected with IF staining (E). Scale bars: 25 μm, 5 μm (zoom). (F and G) H358 cells were exposed to 0.1 μM sotorasib, 2.5 μM VP-16, or their combination for 24 hours. The proteins of interest were detected with Western blotting (C and F). Apoptotic cells were detected with annexin V staining/flow cytometry (D and G). Data are shown as the mean ± SD of triplicate determinations. (H–J) H1792 CDXs in nu/nu nude mice (n = 6/group) were treated with vehicle, sotorasib alone (50 mg/kg, daily, og), VP-16 alone (1 mg/kg, daily, i.p.), or their combination. Tumor sizes (H) were measured at the indicated time points. At the end of treatment, tumors in each group were weighed (I) and photographed (J). Data are shown as the mean ± SEM of 6 tumors from 6 mice. Statistical analysis was conducted using 1-way ANOVA.