Arctigenin-mediated cell death of SK-BR-3 cells is caused by HER2 inhibition and autophagy-linked apoptosis

Arctigenin induces activated HSCs quiescence via AMPK-PPARγ pathway to ameliorate liver fibrosis in mice

Arctigenin (ATG), a traditional Chinese herbal medicine, is a natural lignan compound extracted from the seeds of burdock (Arctium lappa L, Asteraceae). As a natural product with multiple biological activities, the effect and mechanism of ATG against liver fibrosis are not fully elucidated yet. In current work, we first discovered that ATG could improve CCl4-induced liver injury reflected by lower plasma ALT and AST levels, liver coefficient and pathological scoring of ballooning. Furthermore, it also could reduce the positive areas of Masson, Sirius red and α-SMA staining, inhibit the expression of fibrosis-related genes (Col1a1, Col3a1, Acta2), and decrease the content of hydroxyproline, indicated ATG treatment had benefits in alleviating CCl4-induced liver fibrosis. In vitro, we observed that ATG can inhibit collagen production stimulated by TGF-β1 in LX2 cells. By analysis of the information obtained from SymMap and GeneCards databases and in vitro validation experiments, ATG was proven to be an indirect PPARγ agonist and its effect on collagen production was dependent on PPARγ. Subsequently, we confirmed that ATG activating AMPK was the contributor of its effect on PPARγ and collagen production. Finally, the transformation of activated hepatic stellate cells was determined after treated with ATG, in which ATG treatment could return activated LX2 cells to quiescence because of the elevated quiescent markers and lipid droplets. Our work has highlighted the potential of ATG in the treatment of liver fibrosis and clarified that ATG can activate AMPK/PPARγ pathway to restore the activated hepatic stellate cell to quiescence thereby improving liver fibrosis.

Targeted Delivery of Arctigenin Using Sialic Acid Conjugate-Modified Liposomes for the Treatment of Breast Cancer

Arctigenin (ATG) is a broad-spectrum antitumor drug with an excellent inhibitory effect on malignant tumors such as breast cancer, glioblastoma, liver cancer, and colon cancer. However, the clinical application of ATG is limited by its poor water solubility and quick hydrolysis in the liver, intestine, and plasma, which might hinder its application. Sialic acid (SA) recognizes selectin receptors overexpressed on the surface of tumor-associated macrophages. In this study, SA was conjugated with octadecylamine (ODA) to prepare SA-ODA, which was employed to prepare SA functionalized nanoliposomes (SA-Lip) to achieve breast cancer targeting. The formulations were finely optimized using the Box-Behnken design to achieve higher ATG loading. The size, ζ potential, entrapment efficiency, drug loading, and release behavior of ATG@SA-Lip were fully investigated in comparison with conventional ATG@Lip. The ATG@SA-Lip displayed more potent cytotoxicity and higher cellular internalization compared to ATG@Sol and ATG@Lip in both MCF7 and 4T1 cells. Notably, ATG@SA-Lip showed the lowest impact on the immune system. Our study demonstrates that SA-Lip has strong potential as a delivery system for the targeted delivery of ATG.

Anthocyanin Oligomers Induce Apoptosis and Autophagy by Inhibiting the mTOR Signaling Pathway in Human Breast Cancer Cells

Anthocyanin oligomers (AOs) are phytochemicals synthesized by fermenting anthocyanins extracted from grape skins and are more biologically active than monomeric anthocyanins. In this study, we evaluate the effects of an AO on triple-negative MDA-MB-231 and HER2-overexpressing SK-BR-3 breast cancer cells. The cell viability of MDA-MB-231 and SK-BR-3 cells was significantly inhibited in a concentration-dependent manner by AO treatment for 24 h, while delphinidin (a monomeric anthocyanin) had no effect on cell viability. In addition, the AO increased H2A.X phosphorylation (a marker of DNA damage), reduced RAD51 (a DNA repair protein) and survivin (a cell survival factor) protein levels, and induced apoptosis by caspase-3-dependent PARP1 cleavage in both cell lines. Surprisingly, the AO induced autophagy by increasing intracellular LC3-II puncta and LC3-II and p62 protein levels. In addition, the AO inhibited the mTOR pathway in MDA-MB-231 and SK-BR-3 cells by suppressing the HER2, EGFR1, and AKT pathways. These results demonstrate that the anti-cancer effect of the AO was due to the induction of apoptosis and autophagy via cleaved caspase-3-mediated PARP1 cleavage and mTOR pathway inhibition, respectively. Furthermore, our results suggest that anthocyanin oligomers could be considered potential candidates for breast cancer treatment.

Phytochemicals Target Multiple Metabolic Pathways in Cancer

Cancer metabolic reprogramming is a complex process that provides malignant cells with selective advantages to grow and propagate in the hostile environment created by the immune surveillance of the human organism. This process underpins cancer proliferation, invasion, antioxidant defense, and resistance to anticancer immunity and therapeutics. Perhaps not surprisingly, metabolic rewiring is considered to be one of the "Hallmarks of cancer". Notably, this process often comprises various complementary and overlapping pathways. Today, it is well known that highly selective inhibition of only one of the pathways in a tumor cell often leads to a limited response and, subsequently, to the emergence of resistance. Therefore, to increase the overall effectiveness of antitumor drugs, it is advisable to use multitarget agents that can simultaneously suppress several key processes in the tumor cell. This review is focused on a group of plant-derived natural compounds that simultaneously target different pathways of cancer-associated metabolism, including aerobic glycolysis, respiration, glutaminolysis, one-carbon metabolism, de novo lipogenesis, and β-oxidation of fatty acids. We discuss only those compounds that display inhibitory activity against several metabolic pathways as well as a number of important signaling pathways in cancer. Information about their pharmacokinetics in animals and humans is also presented. Taken together, a number of known plant-derived compounds may target multiple metabolic and signaling pathways in various malignancies, something that bears great potential for the further improvement of antineoplastic therapy.

Arctigenin improves neuropathy via ameliorating apoptosis and modulating autophagy in streptozotocin-induced diabetic mice

BACKGROUND

Oxidative stress mediates the pathophysiology of diabetic neuropathy (DN) with activation of apoptotic pathway and reduction of autophagy. Arctigenin (ARC) is a natural lignan isolated from some plants of the Asteraceae family that shows antioxidant property. The present study aimed to explore the mechanistic neuroprotective effect of ARC on animal model for DN.

METHODS

DN was induced using streptozotocin (STZ) at a dose of 45 mg/kg, i.p, for five consecutive days and ARC was administered orally (25 or 50 mg) for 3 weeks. The mechanical sensitivity and thermal latency were determined using von Frey and hotplate, respectively. Beclin, p62, and LC3 were detected as markers for autophagy by western blot. Levels of reduced glutathione, lipid peroxides, and activities of catalase and superoxide dismutase were detected as readout for oxidative stress. Apoptotic parameters and histopathological changes were revealed in all experimental groups.

RESULTS

The present study showed deterioration of the function and structure of neurons as a result of hyperglycemia. Oxidative stress and impaired autophagy were observed in diabetic neurons as well as the activation of apoptotic pathway. ARC improved the behavioral and histopathological changes of diabetic mice. ARC combated oxidative stress through diminishing lipid peroxidation and improving the activity of antioxidant enzymes. This was concomitant by reducing the biomarkers of apoptosis. ARC augmented the expression of Beclin and LC3 while it lessened the expression of p62 indicating the activation of autophagy. These findings suggest that ARC can ameliorate DN by combating apoptosis and oxidative stress and improving autophagy.

Combined doxorubicin and arctigenin treatment induce cell cycle arrest-associated cell death by promoting doxorubicin uptake in doxorubicin-resistant breast cancer cells

Chemotherapy failure is often caused by drug resistance, for which no effective treatment strategy has been established. Many studies have been undertaken with the aim of overcoming drug resistance using natural products. Arctigenin (ATG), a natural product, has been investigated for its anti-cancer effects in HER2-overexpressing, ER-positive, and triple-negative breast cancer cells. We investigated the efficacy of ATG against self-established doxorubicin (DOX)-resistant breast cancer cells (MCF-DR and MDA-DR cells) derived from MCF-7 and MDA-MB-231 cells, respectively. ATG was found to increase DOX intracellular levels by downregulating multidrug Resistance 1 (MDR1) mRNA expression in DOX-resistant cells. In addition, combined treatment with DOX and ATG (DOX/ATG) reduced the viability of and colony formation by DOX-resistant cells. DOX/ATG also significantly induced G2/M cell cycle arrest by suppressing the Cyclin D1/CDK4/RB pathways and suppressed the expressions of MDR1 and Cyclin D1 by inhibiting the Mitogen-activated protein kinase (MAPK)/Activating protein-1 (AP-1) signaling pathways. Furthermore, DOX/ATG induced DNA damage and attenuated the expressions of RAD51 and Ku80. However, PARP1 (Poly [ADP-ribose] polymerase1) cleavage and AIF (Apoptosis-inducing factor) induced apoptosis did not occur despite DNA damage-induced cell death. Rather, flow cytometry showed that DOX/ATG caused necrosis. In summary, DOX/ATG increased intracellular DOX levels by inhibiting MDR1 and inducing G2/M arrest by inhibiting the Cyclin D1/CDK4/RB pathways and causing necrosis by damaging DNA. Our results suggest that ATG might be used as an adjuvant to enhance the efficacy of DOX in DOX-resistant breast cancer.