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Huang SH, Tseng JC, Lin CY, Kuo YY, Wang BJ, Kao YH, Muller CJF, Joubert E, Chuu CP. Rooibos suppresses proliferation of castration-resistant prostate cancer cells via inhibition of Akt signaling. PHYTOMEDICINE : INTERNATIONAL JOURNAL OF PHYTOTHERAPY AND PHYTOPHARMACOLOGY 2019; 64:153068. [PMID: 31419729 DOI: 10.1016/j.phymed.2019.153068] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/18/2019] [Revised: 07/26/2019] [Accepted: 08/06/2019] [Indexed: 05/22/2023]
Abstract
BACKGROUND Androgen ablation therapy is the primary treatment for metastatic prostate cancer (PCa). However, the majority of PCa patients receiving the androgen deprivation therapy develop recurrent castration-resistant prostate cancer (CRPC) within two years. Chemotherapies show little effect on prolonging survival of CRPC patients and new treatments are needed. Previous studies reported that the extracts from rooibos (Aspalathus linearis) exhibit chemopreventive properties in some cancer models, including skin, liver and oesophagus cancers in animals. We therefore investigate if extracts from rooibos can suppress the proliferation of CRPC cells. PURPOSE We investigated whether an aspalathin-rich green rooibos extract (GRT™; 12.78 g aspalathin/100 g extract) demonstrates anti-cancer activity against CRPC cells. METHODS High performance liquid chromatography (HPLC) was used to profile the major flavonoids in GRT. Hoechst-dye proliferation assay, 3,4,5-dimethylthiazol-2-yl)-2-5-diphenyltetrazolium bromide (MTT) viability assay and flow cytometry assay were used to explore the effects of GRT on the proliferation and cell cycle progression of CRPC cells. Comet assay was used to survey whether GRT induces apoptosis in CRPC cells. LNCaP 104-R1 xenograft nude mice model was used to determine the inhibitory effect of GRT on CRPC tumors in vivo. Micro-Western Array (MWA) and Western blot analysis were carried out to unravel the underlying molecular mechanism. RESULTS GRT contained aspalathin as the most abundant flavonoid. GRT suppressed the proliferation and survival of LNCaP 104-R1, LNCaP FGC and PC-3 PCa cells. Flow cytometry analysis showed that GRT decreased the population of PCa cells in S phase but increased the cell population in G2/M phase. Comet assay confirmed that GRT induced apoptosis in LNCaP 104-R1 cells. Gavage of 400 mg/kg GRT suppressed LNCaP 104-R1 xenografts in castrated nude mice. MWA and Western blot analysis indicated that GRT treatment suppressed Akt1, phospho-Akt Ser473, Cdc2, Bcl-2, TRAF4 and Aven, but increased activated Caspase 3, cytochrome c, and p27Kip1. Overexpression of Akt rescued the suppressive effects of GRT on CRPC cells. Co-treatment of GRT with Bcl-2 inhibitor ABT-737, PI3K inhibitor LY294002 and Akt inhibitor GSK 690693 exhibited additive inhibitory effect on proliferation of CRPC cells. CONCLUSIONS GRT suppresses the proliferation of CRPC cells via inhibition of Akt signaling.
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Affiliation(s)
- Shih-Han Huang
- Institute of Cellular and System Medicine, National Health Research Institutes, Miaoli County 35053, Taiwan; Department of Life Sciences, National Central University, Taoyuan City 32001, Taiwan
| | - Jen-Chih Tseng
- Institute of Cellular and System Medicine, National Health Research Institutes, Miaoli County 35053, Taiwan
| | - Ching-Yu Lin
- Institute of Cellular and System Medicine, National Health Research Institutes, Miaoli County 35053, Taiwan
| | - Ying-Yu Kuo
- Institute of Cellular and System Medicine, National Health Research Institutes, Miaoli County 35053, Taiwan; Institute of Biotechnology, National Tsing Hua University, Hsinchu City 30013, Taiwan
| | - Bi-Juan Wang
- Institute of Cellular and System Medicine, National Health Research Institutes, Miaoli County 35053, Taiwan
| | - Yung-Hsi Kao
- Department of Life Sciences, National Central University, Taoyuan City 32001, Taiwan
| | - Christo J F Muller
- Biomedical Research and Innovation Platform (BRIP), South African Medical Research Council, Tygerberg 7505, South Africa; Division of Medical Physiology, Faculty of Health Sciences, Stellenbosch University, Tygerberg 7505, South Africa; Department of Biochemistry and Microbiology, University of Zululand, KwaDlangezwa 3886, South Africa
| | - Elizabeth Joubert
- Plant Bioactives Group, Post-Harvest and Agro-Processing Technologies, Agricultural Research Council (ARC), Infruitec-Nietvoorbij, Stellenbosch 7599, South Africa; Department of Food Science, Stellenbosch University, Stellenbosch 7599, South Africa
| | - Chih-Pin Chuu
- Institute of Cellular and System Medicine, National Health Research Institutes, Miaoli County 35053, Taiwan; PhD Program for Aging and Graduate Institute of Basic Medical Science, China Medical University, Taichung City 40402, Taiwan; Biotechnology Center, National Chung Hsing University, Taichung City 40227, Taiwan.
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Mazibuko-Mbeje SE, Dludla PV, Johnson R, Joubert E, Louw J, Ziqubu K, Tiano L, Silvestri S, Orlando P, Opoku AR, Muller CJF. Aspalathin, a natural product with the potential to reverse hepatic insulin resistance by improving energy metabolism and mitochondrial respiration. PLoS One 2019; 14:e0216172. [PMID: 31048842 PMCID: PMC6497260 DOI: 10.1371/journal.pone.0216172] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/22/2019] [Accepted: 04/14/2019] [Indexed: 02/07/2023] Open
Abstract
Aspalathin is a rooibos flavonoid with established blood glucose lowering properties, however, its efficacy to moderate complications associated with hepatic insulin resistance is unknown. To study such effects, C3A liver cells exposed to palmitate were used as a model of hepatic insulin resistance. These hepatocytes displayed impaired substrate metabolism, including reduced glucose transport and free fatty acid uptake. These defects included impaired insulin signaling, evident through reduced phosphatidylinositol-4,5-bisphosphate 3-kinase/ protein kinase B (PI3K/AKT) protein expression, and mitochondrial dysfunction, depicted by a lower mitochondrial respiration rate. Aspalathin was able to ameliorate these defects by correcting altered substrate metabolism, improving insulin signaling and mitochondrial bioenergetics. Activation of 5'-adenosine monophosphate-activated protein kinase (AMPK) may be a plausible mechanism by which aspalathin increases hepatic energy expenditure. Overall, these results encourage further studies assessing the potential use of aspalathin as a nutraceutical to improve hepatocellular energy expenditure, and reverse metabolic disease-associated complications.
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Affiliation(s)
- Sithandiwe E. Mazibuko-Mbeje
- Biomedical Research and Innovation Platform, South African Medical Research Council, Tygerberg, South Africa
- Division of Medical Physiology, Faculty of Health Sciences, Stellenbosch University, Tygerberg, South Africa
| | - Phiwayinkosi V. Dludla
- Biomedical Research and Innovation Platform, South African Medical Research Council, Tygerberg, South Africa
- Department of Life and Environmental Sciences, Polytechnic University of Marche, Ancona, Italy
| | - Rabia Johnson
- Biomedical Research and Innovation Platform, South African Medical Research Council, Tygerberg, South Africa
- Division of Medical Physiology, Faculty of Health Sciences, Stellenbosch University, Tygerberg, South Africa
| | - Elizabeth Joubert
- Plant Bioactives Group, Post-Harvest and Agro-Processing Technologies, Agricultural Research Council, Infruitec-Nietvoorbij, Stellenbosch, South Africa
- Department of Food Science, Stellenbosch University, Stellenbosch, South Africa
| | - Johan Louw
- Division of Medical Physiology, Faculty of Health Sciences, Stellenbosch University, Tygerberg, South Africa
- Department of Biochemistry and Microbiology, University of Zululand, KwaDlangezwa, South Africa
| | - Khanyisani Ziqubu
- Division of Medical Physiology, Faculty of Health Sciences, Stellenbosch University, Tygerberg, South Africa
- Department of Biochemistry and Microbiology, University of Zululand, KwaDlangezwa, South Africa
| | - Luca Tiano
- Department of Life and Environmental Sciences, Polytechnic University of Marche, Ancona, Italy
| | - Sonia Silvestri
- Department of Life and Environmental Sciences, Polytechnic University of Marche, Ancona, Italy
| | - Patrick Orlando
- Department of Life and Environmental Sciences, Polytechnic University of Marche, Ancona, Italy
| | - Andy R. Opoku
- Department of Biochemistry and Microbiology, University of Zululand, KwaDlangezwa, South Africa
| | - Christo J. F. Muller
- Biomedical Research and Innovation Platform, South African Medical Research Council, Tygerberg, South Africa
- Division of Medical Physiology, Faculty of Health Sciences, Stellenbosch University, Tygerberg, South Africa
- Department of Biochemistry and Microbiology, University of Zululand, KwaDlangezwa, South Africa
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