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Updated: Jan 31, 2026
Analytical Determination of Mitochondrial Function of Excised Solid Tumor Homogenates
Published on: August 6, 2021
Targeting mitochondrial hexokinases increases efficacy of histone deacetylase inhibitors in solid tumor models
Andrew J McDonald1, Katherine M Curt2, Ruchi P Patel2
1Developmental Therapeutics Branch, National Cancer Institute, National Institutes of Health, 9000 Rockville Pike, Bethesda, MD 20892, United States.
Abstract:
Hexokinase 1 and 2 have been shown to inhibit Bak- and Bax-mediated apoptosis, leading us to combine the histone deacetylase inhibitor romidepsin with clotrimazole or bifonazole, two compounds that reportedly decrease mitochondrial localization of hexokinases. Cancer cell lines derived from breast, kidney, lung, colon or ovarian cancers were treated with a short-term exposure to 25 ng/ml romidepsin combined with either clotrimazole or bifonazole. The combination of romidepsin with 25 µM clotrimazole or bifonazole resulted in increased annexin staining compared to cells treated with any of the drugs alone. Cell death was caspase-mediated, as the pan-caspase inhibitor Q-VD-OPh was found to inhibit apoptosis induced by the combination. A549 lung cancer cells or HCT-116 cells deficient in Bak and Bax were also resistant to apoptosis with the combination implicating the intrinsic apoptotic pathway. We found that a 24 h treatment with clotrimazole or bifonazole decreased total hexokinase 2 expression, resulting in a 76% or 60% decrease, respectively, of mitochondrial expression of hexokinase 2. Mitochondrial hexokinase 1 levels increased 2-fold or less. Our work suggests that the combination of a short-term romidepsin treatment with bifonazole or clotrimazole leads to increased apoptosis, most likely due to decreased mitochondrial expression of hexokinase 2.
Insights
Combining romidepsin with clotrimazole or bifonazole enhances cancer cell death by targeting mitochondrial hexokinase 2. This combination effectively induces apoptosis, offering a potential new therapeutic strategy for various cancers.
Area of Science:
- Biochemistry
- Molecular Biology
- Oncology
Background:
- Hexokinases 1 and 2 (HK1, HK2) are known to inhibit apoptosis.
- Romidepsin is a histone deacetylase inhibitor.
- Clotrimazole and bifonazole can reduce mitochondrial hexokinase localization.
Purpose of the Study:
- To investigate the synergistic effect of romidepsin combined with clotrimazole or bifonazole on cancer cell apoptosis.
- To explore the role of hexokinase mitochondrial localization in this process.
Main Methods:
- Treatment of various cancer cell lines with romidepsin and either clotrimazole or bifonazole.
- Assessment of apoptosis using annexin staining and caspase inhibition.
- Measurement of hexokinase 1 and 2 expression and mitochondrial localization.
Main Results:
- The combination of romidepsin with clotrimazole or bifonazole significantly increased apoptosis compared to monotherapy.
- Apoptosis was caspase-mediated and involved the intrinsic apoptotic pathway.
- Clotrimazole and bifonazole reduced mitochondrial hexokinase 2 expression, while hexokinase 1 levels showed a modest increase.
Conclusions:
- Short-term treatment with romidepsin combined with clotrimazole or bifonazole effectively induces apoptosis in cancer cells.
- This effect is primarily mediated by the reduction of mitochondrial hexokinase 2 expression.
- The combination therapy shows promise for cancer treatment by targeting the intrinsic apoptotic pathway.
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