Streptospherin A, a New Cancer Stem Cell Inhibitor, Produced by Streptomyces sp. KUSC-240

Area of Science:

• Microbiology
• Organic Chemistry
• Cancer Research

Background:

• Cancer stem cells (CSCs) drive tumor recurrence, making them key targets for chemotherapy.
• Targeting CSCs is a promising strategy to overcome treatment resistance and prevent cancer relapse.

Purpose of the Study:

• To identify novel compounds with CSC-inhibitory activity using a previously established screening system.
• To isolate and characterize a new scarce compound, streptospherin A, from Streptomyces sp. KUSC-240.

Main Methods:

• High-resolution mass spectrometry (HR-MS) and Nuclear Magnetic Resonance (NMR) spectroscopy for structural elucidation.
• Nuclear Overhauser effect (NOE) spectroscopy and J-resolved heteronuclear multiple bond connectivity (HMBC) analysis for determining relative configuration.
• In vitro assays to evaluate the effects of streptospherin A on CSC sphere formation and growth.

Main Results:

• Streptospherin A (1) was isolated and its planar structure elucidated using HR-MS and NMR.
• Partial relative configuration of the tetrahydropyran ring in streptospherin A was determined through NOE and HMBC analyses.
• Streptospherin A demonstrated significant inhibition of CSC sphere formation and suppressed CSC proliferation.

Conclusions:

• Streptospherin A is a novel compound with potent activity against cancer stem cells.
• This compound represents a potential new therapeutic agent for cancer chemotherapy, specifically targeting CSCs to prevent recurrence.