J Cancer 2021; 12(11):3126-3135. doi:10.7150/jca.51650

Research Paper

The natural compound n-butylidenephthalide kills high-grade serous ovarian cancer stem cells by activating intrinsic apoptosis signaling pathways

Yu-Hsun Chang1, Kun-Chi Wu2, Dah-Ching Ding3,4✉

1. Department of Pediatrics, Hualien Tzu Chi Hospital, Buddhist Tzu Chi Foundation, and Tzu Chi University, Hualien, Taiwan.
2. Department of Orthopedics, Hualien Tzu Chi Hospital, Buddhist Tzu Chi Foundation, and Tzu Chi University, Hualien, Taiwan.
3. Department of Obstetrics and Gynecology, Hualien Tzu Chi Hospital, Buddhist Tzu Chi Foundation, and Tzu Chi University, Hualien, Taiwan.
4. Institute of Medical Sciences, Tzu Chi University, Hualien, Taiwan.

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Citation:
Chang YH, Wu KC, Ding DC. The natural compound n-butylidenephthalide kills high-grade serous ovarian cancer stem cells by activating intrinsic apoptosis signaling pathways. J Cancer 2021; 12(11):3126-3135. doi:10.7150/jca.51650. Available from https://www.jcancer.org/v12p3126.htm

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Abstract

High-grade serous ovarian cancer (HGSOC) constitutes 80% of ovarian cancer. Cancer stem cells (CSCs) are responsible for most of the tumor metastasis and chemoresistance. n-Butylidenephthalide (BP) is a potential anti-tumor agent for treating a variety of cancers. The aim of this study was to evaluate the effect of BP on CSCs of HGSOC. CSCs were isolated using the CSC marker (ALDH; aldehyde dehydrogenase) from KURAMOCHI and OVSAHO cells (HGSOC cell lines). The cell proliferation, IC50 (the half-maximal inhibitory concentration), cell migration and invasion, TUNEL (terminal deoxynucleotidyl transferase (TdT) dUTP nick end labeling) assay, western blot of ovarian CSC were evaluated. The animal xenograft studies were evaluated on an immunodeficient mouse model. The results showed the proliferation of ALDH+ cells was greater than that of ALDH- cells. The dosage of IC50 of BP was higher in ALDH+ cells than in mixed cancer cells (317.2 vs. 206.5 μg/ml) in KURAMOCHI cells, but not in OVSAHO cells (61.1 vs. 48.5 μg/ml). BP could inhibit the migration and invasion of both cancer stem cells. BP treatment could activate apoptosis signaling, as indicated by the TUNEL assay and the increased expression of cleaved caspase-3, -7, and -9 but not cleaved caspase-8. A low dose of BP (20 and 25 μg/mL) treatment could increase the toxicity of taxol and cisplatin. In the animal model, BP (200 mg/kg) treatment also decreased the KURAMOCHI and OVSAHO tumor growth rate and induced tumor apoptosis. In conclusion, BP could kill ALDH+ CSCs of HGSOC in vitro and in vivo by inducing apoptosis. BP may provide a new therapeutic approach for HGSOC.

Keywords: Butylidenephthalide, high grade serous ovarian cancer, cancer stem cell, ALDH, apoptosis.