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The HSP90 Inhibitor Ganetespib Radiosensitizes Human Lung Adenocarcinoma Cells
Roberto Gomez-Casal1,2, Chitralekha Bhattacharya3,4, Michael W Epperly5,6
1The University of Pittsburgh Cancer Institute, Pittsburgh, PA 15213, USA. gomezcasalr@upmc.edu.
Abstract:
The molecular chaperone HSP90 is involved in stabilization and function of multiple client proteins, many of which represent important oncogenic drivers in NSCLC. Utilization of HSP90 inhibitors as radiosensitizing agents is a promising approach. The antitumor activity of ganetespib, HSP90 inhibitor, was evaluated in human lung adenocarcinoma (AC) cells for its ability to potentiate the effects of IR treatment in both in vitro and in vivo. The cytotoxic effects of ganetespib included; G2/M cell cycle arrest, inhibition of DNA repair, apoptosis induction, and promotion of senescence. All of these antitumor effects were both concentration- and time-dependent. Both pretreatment and post-radiation treatment with ganetespib at low nanomolar concentrations induced radiosensitization in lung AC cells in vitro. Ganetespib may impart radiosensitization through multiple mechanisms: such as down regulation of the PI3K/Akt pathway; diminished DNA repair capacity and promotion of cellular senescence. In vivo, ganetespib reduced growth of T2821 tumor xenografts in mice and sensitized tumors to IR. Tumor irradiation led to dramatic upregulation of β-catenin expression in tumor tissues, an effect that was mitigated in T2821 xenografts when ganetespib was combined with IR treatments. These data highlight the promise of combining ganetespib with IR therapies in the treatment of AC lung tumors.
Insights
Ganetespib, an HSP90 inhibitor, enhances radiation therapy effectiveness in lung adenocarcinoma by inducing cell cycle arrest, inhibiting DNA repair, and promoting apoptosis. This combination shows promise for treating lung tumors.
Area of Science:
- Oncology
- Molecular Biology
- Radiotherapy
Background:
- Heat Shock Protein 90 (HSP90) is crucial for stabilizing oncogenic proteins in non-small cell lung cancer (NSCLC).
- HSP90 inhibitors are being explored as radiosensitizers to improve cancer treatment outcomes.
Purpose of the Study:
- To evaluate the antitumor activity of ganetespib, an HSP90 inhibitor, in human lung adenocarcinoma (AC) cells.
- To determine ganetespib's ability to potentiate the effects of ionizing radiation (IR) in vitro and in vivo.
Main Methods:
- In vitro studies using human lung AC cell lines treated with ganetespib and/or IR.
- In vivo studies using T2821 tumor xenografts in mice treated with ganetespib and/or IR.
- Analysis of cell cycle, DNA repair, apoptosis, senescence, and specific signaling pathways (PI3K/Akt, β-catenin).
Main Results:
- Ganetespib demonstrated concentration- and time-dependent cytotoxic effects, including G2/M cell cycle arrest, DNA repair inhibition, apoptosis, and senescence.
- Both pre- and post-radiation treatment with ganetespib induced radiosensitization in lung AC cells.
- Ganetespib downregulated the PI3K/Akt pathway, diminished DNA repair capacity, and promoted senescence.
- In vivo, ganetespib reduced tumor xenograft growth and sensitized tumors to IR.
- Combination therapy mitigated IR-induced β-catenin upregulation in tumors.
Conclusions:
- Ganetespib exhibits significant antitumor activity and radiosensitizing potential in lung adenocarcinoma.
- The combination of ganetespib with IR therapy presents a promising strategy for treating AC lung tumors.
