Isolation Techniques, Structural Characteristics, and Pharmacological Effects of Phellinus Polysaccharides: A Review.

Phellinus is a precious perennial medicinal fungus. Its polysaccharides are important bioactive components, and their chemical composition is complex. The polysaccharides are mainly extracted from the fruiting body and mycelium. The yield of the polysaccharides is dependent on the extraction method. They have many pharmacological activities, such as antitumor, immunomodulatory, antioxidant, hypoglycemic, anti-inflammatory, etc. They are also reported to show minor toxic and side effects. Many studies have reported the anticancer activity of Phellinus polysaccharides. This review paper provides a comprehensive examination of the current methodologies for the extraction and purification of Phellinus polysaccharides. Additionally, it delves into the structural characteristics, pharmacological activities, and mechanisms of action of these polysaccharides. The primary aim of this review is to offer a valuable resource for researchers, facilitating further studies on Phellinus polysaccharides and their potential applications.

High-fat diet exacerbated motor dysfunction via necroptosis and neuroinflammation in acrylamide-induced neurotoxicity in mice.

Health risks associated with acrylamide (ACR) or high-fat diet (HFD) exposure alone have been widely concerned in recent years. In a realistic situation, ACR and HFD are generally co-existence, and both are risk factors for the development of neurological diseases. The purpose of the present study was to investigate the combined effects of ACR and HFD on the motor nerve function. As a result, neurobehavioral tests and Nissl staining disclosed that long-term HFD exacerbated motor dysfunction and the damage of spinal cord motor neurons in ACR-exposed mice. Co-exposure of ACR and HFD resulted in morphological changes in neuronal mitochondria of the spinal cord, a significantly reduced mitochondrial subunits NDUFS1, UQCRC2, and MTCO1, released the mitochondrial DNA (mtDNA) into the cytoplasm, and promoted the production of reactive oxygen species (ROS). Combined exposure of HFD and ACR activated the calpain/CDK5/Drp1 axis and caused the mitochondrial excessive division, ultimately increasing MLKL-mediated necroptosis in spinal cord motor neurons. Meanwhile, HFD significantly exacerbated ACR-induced activation of NFkB, NLRP3 inflammasome, and cGAS-STING pathway. Taken together, our findings demonstrated that combined exposure of ACR and HFD aggravated the damage of spinal cord motor neurons via neuroinflammation and necroptosis signaling pathway, pointing to additive effects in mice than the individual stress effects.

Mitophagy suppresses motor neuron necroptotic mitochondrial damage and alleviates necroptosis that converges to SARM1 in acrylamide-induced dying-back neuropathy.

Acrylamide (ACR), a common industrial ingredient that is also found in many foodstuffs, induces dying-back neuropathy in humans and animals. However, the mechanisms remain poorly understood. Sterile alpha and toll/interleukin 1 receptor motif-containing protein 1 (SARM1) is the central determinant of axonal degeneration and has crosstalk with different cell death programs to determine neuronal survival. Herein, we illustrated the role of SARM1 in ACR-induced dying-back neuropathy. We further demonstrated the upstream programmed cell death mechanism of this SARM1-dependent process. Spinal cord motor neurons that were induced to overexpress SARM1 underwent necroptosis rather than apoptosis in ACR neuropathy. Mechanically, non-canonical necroptotic pathways mediated mitochondrial permeability transition pore (mPTP) opening, reactive oxygen species (ROS) production, and mitochondrial fission. What's more, the final executioner of necroptosis, phosphorylation-activated mixed lineage kinase domain-like protein (MLKL), aggregated in mitochondrial fractions. Rapamycin intervention removed the impaired mitochondria, inhibited necroptosis for axon maintenance and neuronal survival, and alleviated ACR neuropathy. Our work clarified the functional links among mitophagy, necroptosis, and SARM1-dependent axonal destruction during ACR intoxication, providing novel therapeutic targets for dying-back neuropathies.

Bioactivities of Dietary Polyphenols and Their Effects on Intestinal Microbiota.

The human gut is a complex but stable micro-ecosystem in which the intestinal microbiota play a key role in human health, the health of the intestine and also affect the ability of the host to metabolize nutrients. Intestinal microbiota can affect human physiological functions by regulating host metabolism, immunity and intestinal barrier function. Dysbiosis in the intestinal microbiota is a crucial stimulus for the development of various diseases, which is associated with a variety of diseases in the body. The composition and function of intestinal microbiota depend on the host's physiological status, genetic makeup, dietary habits, age, and environment, which are the risk factors for obesity, diabetes, cardiovascular diseases and tumors. Polyphenols are important plant secondary metabolites with many physiological functions like anti-oxidation, antitumor, bacteriostasis, cardiovascular and cerebrovascular prevention, and protection of liver and kidney and so on. A large number of studies have confirmed the benefits of dietary polyphenols to human health. Polyphenols and their associated metabolites affect intestinal health and the balance of intestinal microbiota by stimulating the growth of beneficial bacteria and inhibiting the proliferation of pathogens. This review aims to update the current knowledge and highlight how the bioactivities of polyphenols can modulate the intestinal microbiota and regulate the mechanisms of the microbiota, providing a theoretical basis and reference for the scientific and overall use of polyphenols to prevent and treat intestinal diseases and maintain human intestinal health.

Cryptotanshinone Inhibits ERα-Dependent and -Independent BCRP Oligomer Formation to Reverse Multidrug Resistance in Breast Cancer.

Both long-term anti-estrogen therapy and estrogen receptor-negative breast cancer contribute to drug resistance, causing poor prognosis in breast cancer patients. Breast cancer resistance protein (BCRP) plays an important role in multidrug resistance. Here, we show that cryptotanshinone (CPT), an anti-estrogen compound, inhibited the oligomer formation of BCRP on the cell membrane, thus blocking its efflux function. The inhibitory effect of CPT on BCRP was dependent on the expression level of estrogen receptor α (ERα) in ERα-positive breast cancer cells. Furthermore, ERα-negative breast cancer cells with high expression of BCRP were also sensitive to CPT because CPT was able to bind to BCRP and inhibit its oligomer formation on the cell membrane, suggesting that the high level of BCRP expression is crucial for CPT to reverse drug resistance. The combination of CPT and chemotherapeutic agents displayed enhanced anticancer effects. The results suggest that CPT is a novel BCRP inhibitor via blocking the oligomer formation of BCRP on the cell membrane. CPT is able to inhibit the activity of BCRP in an ERα-dependent and -independent manner, sensitizing breast cancer cells to chemotherapy.

Beta-elemene inhibits breast cancer metastasis through blocking pyruvate kinase M2 dimerization and nuclear translocation.

Pyruvate kinase M2 (PKM2), playing a central role in regulating aerobic glycolysis, was considered as a promising target for cancer therapy. However, its role in cancer metastasis is rarely known. Here, we found a tight relationship between PKM2 and breast cancer metastasis, demonstrated by the findings that beta-elemene (ß-elemene), an approved drug for complementary cancer therapy, exerted distinct anti-metastatic activity dependent on PKM2. The results indicated that ß-elemene inhibited breast cancer cell migration, invasion in vitro as well as metastases in vivo. ß-Elemene further inhibited the process of aerobic glycolysis and decreased the utilization of glucose and the production of pyruvate and lactate through suppressing pyruvate kinase activity by modulating the transformation of dimeric and tetrameric forms of PKM2. Further analysis revealed that ß-elemene suppressed aerobic glycolysis by blocking PKM2 nuclear translocation and the expression of EGFR, GLUT1 and LDHA by influencing the expression of importin α5. Furthermore, the effect of ß-elemene on migration, invasion, PKM2 transformation, and nuclear translocation could be reversed in part by fructose-1,6-bisphosphate (FBP) and L-cysteine. Taken together, tetrameric transformation and nuclear translocation of PKM2 are essential for cancer metastasis, and ß-elemene inhibited breast cancer metastasis via blocking aerobic glycolysis mediated by dimeric PKM2 transformation and nuclear translocation, being a promising anti-metastatic agent from natural compounds.

Breaking Glucose Transporter 1/Pyruvate Kinase M2 Glycolytic Loop Is Required for Cantharidin Inhibition of Metastasis in Highly Metastatic Breast Cancer.

Aerobic glycolysis plays a decisive role in cancer growth. However, its role in cancer metastasis was rarely understood. Cantharidin a natural compound from an arthropod insect cantharis exerts potent anticancer activity. Here we found cantharidin possesses significant anti-metastatic activity on breast cancer dependent on inhibition of aerobic glycolysis. Cantharidin indicates significant inhibition on migration and invasion of breast cancer cells, angiogenesis in vitro, and inhibits breast cancer cells metastasizing to liver and lung in vivo. Subsequent results revealed that cantharidin decreases the extracellular acidification rates (ECAR) but increases the oxygen consumption rates (OCR) in high metastatic cells, leading to suppression of aerobic glycolysis. This was considered to be due to inhibiting the activity of pyruvate kinase (PK) and further blocking pyruvate kinase M2 (PKM2) translocation in nucleus. Fructose-1,6-bisphosphate (FBP) and L-cysteine can significantly reverse cantharidin inhibition on breast cancer cell migration, invasion, and PKM2 translocation. Furthermore, glucose transporter 1 (GLUT1) forming a metabolic loop with PKM2 is downregulated, as well as epidermal growth factor receptor (EGFR), the regulator of the glycolytic loop. Totally, cantharidin inhibits the PKM2 nuclear translocation and breaks GLUT1/PKM2 glycolytic loop, resulting in aerobic glycolysis transformation to oxidation and subsequent reversing the metastases in breast cancer. Based on inhibiting multi signals mediated aerobic glycolysis, cantharidin could be prospectively used for prevention of metastasis in breast cancer patients.

Correction to: Cryptotanshinone activates AMPK-TSC2 axis leading to inhibition of mTORC1 signaling in cancer cells.

Following publication of the original article [1], the author noticed the following errors in the article.

Emerging findings into molecular mechanism of brain metastasis.

Brain metastasis is an important cause of morbidity and mortality in cancer patients. Hence, the need to develop improved therapies to prevent and treat metastasis to the brain is becoming urgent. Recent studies in this area are bringing about some advanced progress on brain metastasis. It was concluded that the occurrence and poor prognosis of brain metastasis have been mostly attributed to the exclusion of anticancer drugs from the brain by the blood-brain barrier. And several highly potent new generation targeted drugs with enhanced CNS distribution have been developed constantly. However, the noted "seed and soil" hypothesis also suggests that the outcome of metastasis depends on the relationship between unique tumor cells and the specific organ microenvironment. Moreover, increasing studies in multiple tumor types demonstrated that brain metastasis has great molecular differences between primary tumors and extracranial metastasis to a large extent. Here, the authors summarized the most common malignancies that could lead to brain metastasis-lung cancer, breast cancer and melanoma and their related mutated factors. Only by comprehending a deeper understanding of the molecular mechanisms, more effective brain-specific therapies will be developed for brain metastasis.

Cryptotanshinone inhibition of mammalian target of rapamycin pathway is dependent on oestrogen receptor alpha in breast cancer.

Cryptotanshinone (CPT) has been demonstrated to inhibit proliferation and mammalian target of rapamycin (mTOR) pathway in MCF-7 breast cancer cells. However, the same results are unable to be repeated in MDA-MB-231 cells. Given the main difference of oestrogen receptor α (ERα) between two types of breast cancer cells, It is possibly suggested that CPT inhibits mTOR pathway dependent on ERα in breast cancer. CPT could significantly inhibit cell proliferation of ERα-positive cancer cells, whereas ERα-negative cancer cells are insensitive to CPT. The molecular docking results indicated that CPT has a high affinity with ERα, and the oestrogen receptor element luciferase reporter verified CPT distinct anti-oestrogen effect. Furthermore, CPT inhibits mTOR signalling in MCF-7 cells, but not in MDA-MB-231 cells, which is independent on binding to the FKBP12 and disrupting the mTOR complex. Meanwhile, increased expression of phosphorylation AKT and insulin receptor substrate (IRS1) induced by insulin-like growth factor 1 (IGF-1) was antagonized by CPT, but other molecules of IGF-1/AKT/mTOR signalling pathway such as phosphatase and tensin homolog (PTEN) and phosphatidylinositol-4,5-bisphosphate 3-kinase (PI3K) were negatively affected. Finally, the MCF-7 cells transfected with shERα for silencing ERα show resistant to CPT, and p-AKT, phosphorylation of p70 S6 kinase 1 (p-S6K1) and eukaryotic initiation factor 4E binding protein 1 (4E-BP1) were partially recovered, suggesting ERα is required for CPT inhibition of mTOR signalling. Overall, CPT inhibition of mTOR is dependent on ERα in breast cancer and should be a potential anti-oestrogen agent and a natural adjuvant for application in endocrine resistance therapy.

Cryptotanshinone activates AMPK-TSC2 axis leading to inhibition of mTORC1 signaling in cancer cells.

BACKGROUND: Cryptotanshinone (CPT), a fat-soluble phenanthraquinone from Salvia miltiorrhiza Bunge, has been demonstrated to inhibit phosphorylation of p70 S6 kinase 1 (S6K1) and eukaryotic initiation factor 4E binding protein 1 (4E-BP1), a couple of direct downstream effectors of the mammalian target of rapamycin complex 1 (mTORC1), resulting in cancer cell arrested in G0 phase and subsequent inhibition of proliferation. However, its concrete molecular mechanism about how CPT inhibits mTORC1 signaling pathway is unclear. METHODS: one solution was used to check cell viability and western blotting for determining expression of the indicated proteins. Molecular docking was performed to assess the binding of CPT with mTOR. The co-immunoprecipitation assay was to analyze whether CPT could disrupt the mTORC1 and TSC1/TSC2 complex. Recombinant adenoviral dominant-negative AMPKα was used to downregulate expression of AMPKα and lentiviral AMPK and TSC2 to silence the AMPK and TSC2 in Rh30 cells. RESULTS: Primarily, Rh30 cells expressing rapamycin-resistant mutant mTOR are also sensitive to CPT, while the molecular docking result for CPT binding to mTOR is negative, suggesting that CPT inhibition of mTORC1 is different from rapamycin. Then the related proteins of PTEN-PI3K pathway was proved not to be affected, but the phosphorylation of adenosine monophosphate-activated protein kinase (AMPK) was activated by a concentration- and time- dependent manner, meaning that it may be associated with AMPK. Further results indicated that compound C, inhibitor of AMPK, could clearly reversed CPT inhibitory effect on Rh30 cells, and dominant-negative AMPK in cancer cells conferred resistance to CPT inhibition of 4E-BP1 and phosphorylation of S6K1, as well as sh-AMPK. Furthermore, compared with AMPK-positive MEF cells, AMPK-negative MEF cells are less sensitive to CPT by the findings that 4E-BP1 and phosphorylation of S6K1 express comparatively more. Additionally, phosphorylation of tuberous sclerosis complex 2 (TSC2) was activated under the treatment of CPT, and down-expression of TSC2 by shRNA slightly recovered expression of 4E-BP1 and phosphorylation of S6K1, while co-immunoprecipitation of TSC2 did not alter expression of TSC1 by CPT. CONCLUSION: CPT inhibiting mTORC1 pathway was mostly due to activation of AMPK-TSC2 axis rather than specific binding to mTORC1. CPT is a potent anticancer agent targeting AMPK.