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Updated: Jul 17, 2026
Co-immunoprecipitation Assay Using Endogenous Nuclear Proteins from Cells Cultured Under Hypoxic Conditions
Published on: August 2, 2018
Inhibitory activity of the hypoxia-inducible factor-1 pathway by tartrolone C
Yohko Yamazaki1, Tetsuya Someno, Kazuhisa Minamiguchi
1Numazu Bio-Medical Research Institute, Microbial Chemistry Research Center, 18-24 Miyamoto, Numazu-shi, Shizuoka 410-0301, Japan yamako@bikaken.or.jp
Abstract:
Hypoxia-inducible factor-1 (HIF-1) is a central mediator of cellular responses to low oxygen and has recently become an important therapeutic target for solid tumor therapy. To identify small molecule inhibitors of the HIF-1 transcriptional activation, we have established a high through-put assay system using a stable transformant of mammalian cells that express a luciferase reporter gene construct containing a HIF-1 binding site. Using this system, we screened 5000 cultured broths of microorganisms, and we found that fermentation broth produced by Streptomyces strain 1759-27 showed significant inhibition of the reporter activity induced by hypoxic conditions. The active substance NBRI759-27 was purified and determined to be tartrolone C by several methods including X-ray crystallography. In the reporter gene assay, tartrolone C inhibited the HIF-1 transcriptional activity under hypoxic conditions with an IC50 value of 0.17 microg/ml.
Insights
Researchers discovered tartrolone C, a novel compound from Streptomyces, effectively inhibits Hypoxia-inducible factor-1 (HIF-1) transcriptional activity. This finding offers a potential new therapeutic strategy for solid tumors by targeting cellular responses to low oxygen.
Area of Science:
- Biochemistry
- Molecular Biology
- Pharmacology
Background:
- Hypoxia-inducible factor-1 (HIF-1) is a key regulator of cellular adaptation to low oxygen conditions.
- HIF-1 plays a critical role in solid tumor development and progression, making it a significant therapeutic target.
- Targeting HIF-1 transcriptional activity presents a promising strategy for anti-cancer therapies.
Purpose of the Study:
- To identify novel small molecules that inhibit HIF-1 transcriptional activation.
- To screen microbial fermentation broths for compounds with HIF-1 inhibitory activity.
- To characterize the structure and inhibitory potential of newly discovered active substances.
Main Methods:
- Development of a high-throughput screening assay using mammalian cells with a HIF-1 responsive luciferase reporter.
- Screening of 5000 microbial fermentation broths.
- Purification and structural elucidation of the active compound using techniques including X-ray crystallography.
- Quantification of inhibitory activity using the reporter gene assay (IC50 determination).
Main Results:
- A fermentation broth from Streptomyces strain 1759-27 demonstrated significant inhibition of hypoxia-induced reporter activity.
- The active compound, designated NBRI759-27, was isolated and identified as tartrolone C.
- Tartrolone C exhibited potent inhibition of HIF-1 transcriptional activity with an IC50 value of 0.17 microg/ml under hypoxic conditions.
Conclusions:
- Tartrolone C is a novel inhibitor of HIF-1 transcriptional activity.
- The discovery of tartrolone C provides a new lead compound for the development of anti-cancer therapeutics targeting the HIF-1 pathway.
- This study highlights the potential of microbial natural products in drug discovery for cancer therapy.
