Anticancer polysaccharides from natural resources: A review of recent research

Owing to a dramatic increase in average life expectancy and the Family Planning program of the 1970s - 1990s, China is rapidly becoming an aging society. Therefore, the investigation of healthspan-extending drugs becomes more urgent. Astragalus membranaceus (Huangqi) is a major medicinal herb that has been commonly used in many herbal formulations in the practice of traditional Chinese medicine (TCM) to treat a wide variety of diseases and body disorders, or marketed as life-prolonging extracts for human use in China, for more than 2000 years. The major components of Astragalus membranaceus are polysaccharides, flavonoids, and saponins. Pharmacological research indicates that the extract component of Astragalus membranaceus can increase telomerase activity, and has antioxidant, anti-inflammatory, immunoregulatory, anticancer, hypolipidemic, antihyperglycemic, hepatoprotective, expectorant, and diuretic effects. A proprietary extract of the dried root of Astragalus membranaceus, called TA-65, was associated with a significant age-reversal effect in the immune system. Our review focuses on the function and the underlying mechanisms of Astragalus membranaceus in lifespan extension, anti-vascular aging, anti-brain aging, and anti-cancer effects, based on experimental and clinical studies.

Anti-Aging Implications of Astragalus Membranaceus (Huangqi): A Well-Known Chinese Tonic.

The relationship between the expression levels of matrix metalloproteinase-2 (MMP-2) and MMP-9 and breast cancer prognosis was studied. Two breast cancer cell lines (MDA-MB-231 and MCF-7) and one human normal breast cell line (HS578Bst) were investigated. Fluorescence real-time reverse transcription-polymerase chain reaction (RT-PCR) and western blotting were used to detect cellular mRNA and protein MMP-2 and MMP-9 expression levels. Breast cancer tissue samples from 80 patients and tumor-adjacent normal tissue samples from 40 patients were collected, and MMP-2 and MMP-9 expression in these samples were examined using immunohistochemistry (IHC). The relationship of MMP-2 and MMP-9 expression levels with breast cancer patient clinicopathological parameters and prognosis was analyzed. RT-PCR and western blot results showed that MMP-2 and MMP-9 mRNA and protein expression levels were significantly higher in MDA-MB-231 and MCF-7 cells than in HS578Bst cells. A high expression of MMP-2 and MMP-9 was found in 83.75% (67/80) and 78.75% (63/80) of breast cancer tissue samples, respectively. MMP-2 and MMP-9 expression in breast cancer tissues were significantly different from that in tumor-adjacent normal tissues (p<0.01). MMP-2 and MMP-9 expression levels in breast cancer tissues were correlated with lymph node metastasis and tumor staging. Single factor survival analysis showed that MMP-2 and MMP-9 were factors influencing breast cancer prognosis. MMP-2 and MMP-9 are highly expressed in breast cancer tissues and are closely related to lymph node metastasis and tumor staging. MMP-2 and MMP-9 can be used as reference indices for guiding breast cancer prognosis and treatment.

https://www.spandidos-publications.com/10.3892/ol.2017.6924/download

The relationship between MMP-2 and MMP-9 expression levels with breast cancer incidence and prognosis.

Astragalus polysaccharides (APS), which is widely used as a remedy to promote immunity of breast cancer patients, can enhance immune responses and exert anti-tumor effects. In this study, we investigated the effects and mechanisms of APS on macrophage RAW 264.7 and EAC tumor-bearing mice. Griess reaction and ELISA assays revealed that the concentrations of nitric oxide, TNF-α, IL-1β and IL-6 were increased by APS. However, this effect was diminished in the presence of TAK-242 (TLR4 inhibitor) or ST-2825(MyD88 inhibitor). In C57BL/10J (TLR4+/+wild-type) and C57BL/6J (MyD88+/+wild-type) tumor-bearing mice, the tumor apoptosis rate, immune organ indexes and the levels of TNF-α, IL-1β and IL-6 in blood increased and the tumor weight decreased by oral administration of APS for 25 days. APS had no obvious effects on IL-12p70. However, these effects were not significant in C57BL/10ScNJ (TLR4-deficient) and C57BL/B6.129P2(SJL)-Myd88m1.1Defr/J (MyD88-deficient) tumor-bearing mice. qRT-PCR and Western blot indicated that APS stimulated the key nodes in the TLR4-MyD88 dependent signaling pathway, including TLR4, MyD88, TRAF-6, NF-κB and AP-1, both in vitro and in vivo. However, TRAM was an exception. Moreover, TRAF-6 and NF-κB were not triggered by APS in gene-deficient tumor-bearing mice. Therefore, APS may modulate immunity of host organism through activation of TLR4-mediated MyD88-dependent signaling pathway.

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Astragalus polysaccharides exerts immunomodulatory effects via TLR4-mediated MyD88-dependent signaling pathway in vitro and in vivo.

Cancer, a complex yet common disease, is caused by uncontrolled cell division and abnormal cell growth due to a variety of gene mutations. Seeking effective treatments for cancer is a major research focus, as the incidence of cancer is on the rise and drug resistance to existing anti-cancer drugs is major concern. Natural products have the potential to yield unique molecules and combinations of substances that may be effective against cancer with relatively low toxicity/better side effect profile compared to standard anticancer therapy. Drug discovery work with natural products has demonstrated that natural compounds display a wide range of biological activities correlating to anticancer effects. In this review, we discuss formononetin (C16H12O4), which originates mainly from red clovers and the Chinese herb Astragalus membranaceus. The compound comes from a class of 7-hydroisoflavones with a substitution of methoxy group at position 4. Formononetin elicits antitumorigenic properties in vitro and in vivo by modulating numerous signaling pathways to induce cell apoptosis (by intrinsic pathway involving Bax, Bcl-2, and caspase-3 proteins) and cell cycle arrest (by regulating mediators like cyclin A, cyclin B1, and cyclin D1), suppress cell proliferation [by signal transducer and activator of transcription (STAT) activation, phosphatidylinositol 3-kinase/protein kinase-B (PI3K/AKT), and mitogen-activated protein kinase (MAPK) signaling pathway], and inhibit cell invasion [by regulating growth factors vascular endothelial growth factor (VEGF) and Fibroblast growth factor 2 (FGF2), and matrix metalloproteinase (MMP)-2 and MMP-9 proteins]. Co-treatment with other chemotherapy drugs such as bortezomib, LY2940002, U0126, sunitinib, epirubicin, doxorubicin, temozolomide, and metformin enhances the anticancer potential of both formononetin and the respective drugs through synergistic effect. Compiling the evidence thus far highlights the potential of formononetin to be a promising candidate for chemoprevention and chemotherapy.

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Formononetin: A Review of Its Anticancer Potentials and Mechanisms

Formononetin is a naturally existing isoflavone, which can be found in the roots of Astragalus membranaceus, Trifolium pratense, Glycyrrhiza glabra, and Pueraria lobata. It was found to be associated with inhibition of cell proliferation and cell cycle progression, as well as induction of apoptosis in various cancer cell lines. However, the effect of formononetin on breast cancer cell metastasis remains unclear. In this study, we examined the effect of formononetin on the migration and invasion of breast cancer cells MDA-MB-231 and 4T1 in vitro and in vivo. Our data demonstrated that formononetin did not effectively inhibit the cell viability of MDA-MB-231 and 4T1 in 24 h with the concentration lower than 160 μmol/l. When treated with nontoxic concentration of formononetin, the migration and invasion of MDA-MB-231 and 4T1 cells were markedly suppressed by wound healing assay, chamber invasion assay, and in vivo mouse metastasis model. In vitro, formononetin reduced the expression of matrix metalloproteinase-2 (MMP-2), MMP-9 and increased the expression of tissue inhibitor of metalloproteinase-1 (TIMP-1) and TIMP-2. Furthermore, the immunoﬂuorescence and immunoblotting assays indicated that formononetin was very effective in suppressing the phosphorylation of Akt and PI3K. Collectively, these results suggest that formononetin inhibited breast cancer cell migration and invasion by reducing the expression of MMP-2 and MMP-9 through the PI3K/AKT signaling pathway. These findings demonstrate a potentially new therapeutic strategy of formononetin as anti-invasive agent for breast cancer.

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Formononetin Inhibits Migration and Invasion of MDA-MB-231 and 4T1 Breast Cancer Cells by Suppressing MMP-2 and MMP-9 Through PI3K/AKT Signaling Pathways

Objective To investigate the effects of Astragalus polysaccharide (APS) on proliferation of basal-like breast cancer cell line MDA-MB-468 cells and Akt phosphorylation in MDA-MB-468 cells. Methods APS at different concentrations was used to culture MDA-MB-468 cells for different time periods, and then proliferation of MDA-MB-468 cells was assayed using methyl thiazolyl tetrazolium (MTT) assay to determine the time- and dose-dependent effects of APS. For observing the effects of APS on phosphor-Akt (p-Akt), in-cell Western blot method was used after 1, 2, 4 and 7 d of culture in APS to detect protein expressions of p-Akt (Thr308) and p-Akt (Ser473). Protein levels of the key targets in p53/murine double minute 2 (MDM2) signaling pathway, such as p53, MDM2 and phosphatase and tensin homolog deleted on chromosome ten (PTEN) were also detected. After PTEN gene was silenced by small interfering RNA (siRNA) in MDA-MB-468 cells, expressions of p-Akt (Thr308 and Ser473) were assayed by the in-cell Western blot method after 2 d of APS treatment. Results APS at 1 and 0.5 mg/mL concentrations effectively inhibited the proliferation of MDA-MB-468 cells and was used in subsequent tests. Compared with the control group, APS decreased the protein expression of p-Akt (Thr308) in MDA-MB-468 cells after 1-, 2-, 4- and 7-day culture, and also decreased the protein expression of p-Akt (Ser473) and up-regulated the protein expression of MDM2 in MDA-MB-468 cells after 1- and 2-day culture. Expressions of p53 and PTEN were up-regulated after 7 d of APS culture. After silencing PTEN gene by siRNA, APS could not mediate Akt phosphorylation. Conclusion APS can inhibit proliferation of basal-like breast cancer cell line MDA-MB-468, and down-regulate the expression of Akt phosphorylation. The antiproliferation mechanisms may be related to its effects of up-regulating the expressions of p53 and PTEN by regulating p53/MDM2 positive and negative feedback loops.

[Effects of Astragalus polysaccharide on proliferation and Akt phosphorylation of the basal-like breast cancer cell line].

Yiqi formula (YF), a traditional herbal prescription, has long been used to treat triple-negative breast cancer (TNBC) patients. The present study aims to investigate the effects and the related mechanism of YF for treatment of TNBC xenografts. MDA-MB-231 (human TNBC) cells were subcutaneously injected into the second mammary fat pad of 40 female nude mice, which were divided into four groups: control, erlotinib (an epidermal growth factor receptor (EGFR) tyrosine kinase inhibitor), YF, and combination (YF plus erlotinib). All treatments were administered orally for 30 days. Inhibition rate of tumor weight by erlotinib, YF, and the combination was 26.47%, 17.24%, and 39.15%, respectively. Western blotting showed that YF, erlotinib, and the combination downregulated p-EGFR (P < 0.01) and p-Akt1 (pT308) (P < 0.05) and upregulated PTEN compared with control, and the combination was more efficacious than erlotinib alone (P < 0.05). Similar results were detected by immunohistochemistry. Real-time quantitative PCR showed that YF, erlotinib, and the combination increased PTEN mRNA (P < 0.05, P < 0.01) compared with control, and the combination was more efficacious than erlotinib alone (P < 0.05). In conclusion, YF can regulate the main components of the PI3K/Akt pathway in TNBC xenografts. When YF was used in combination with erlotinib, it enhanced the antitumor effects of erlotinib on TNBC xenografts. These findings suggest that YF is suitable to use for the treatment of TNBC patients.

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Ming-juan Liao

Papers

Formononetin Inhibits Migration and Invasion of MDA-MB-231 and 4T1 Breast Cancer Cells by Suppressing MMP-2 and MMP-9 Through PI3K/AKT Signaling Pathways

[Effects of Astragalus polysaccharide on proliferation and Akt phosphorylation of the basal-like breast cancer cell line].

Yiqi Formula Enhances the Antitumor Effects of Erlotinib for Treatment of Triple-Negative Breast Cancer Xenografts