The mechanistic/mammalian target of rapamycin (mTOR), a serine/threonine kinase, is a central regulator for human physiological activity. Deregulated mTOR signaling is implicated in a variety of ...disorders, such as cancer, obesity, diabetes, and neurodegenerative diseases. The papers published in this special issue summarize the current understanding of the mTOR pathway and its role in the regulation of tissue regeneration, regulatory T cell differentiation and function, and different types of cancer including hematologic malignancies, skin, prostate, breast, and head and neck cancer. The findings highlight that targeting the mTOR pathway is a promising strategy to fight against certain human diseases.
The mushroom Ganoderma lucidum (G. lucidum) has been used for centuries in Asian countries to treat various diseases and to promote health and longevity. Clinical studies have shown beneficial ...effects of G. lucidum as an alternative adjuvant therapy in cancer patients without obvious toxicity. G. lucidum polysaccharides (GLP) is the main bioactive component in the water soluble extracts of this mushroom. Evidence from in vitro and in vivo studies has demonstrated that GLP possesses potential anticancer activity through immunomodulatory, anti-proliferative, pro-apoptotic, anti-metastatic and anti-angiogenic effects. Here, we briefly summarize these anticancer effects of GLP and the underlying mechanisms.
Cell division cycle 25 A (Cdc25A), a dual-specificity protein phosphatase, is one of the most crucial cell cycle regulators, which removes the inhibitory phosphorylation in cyclin-dependent kinases ...(CDKs), such as CDK2, CDK4, and CDK6, and positively regulates the activities of CDKs that lead to cell cycle progression. In addition, Cdc25A also acts as a regulator of apoptosis. Overexpression of Cdc25A promotes tumorigenesis, and is frequently observed in various types of cancer. Here we briefly summarize current understanding of the role of Cdc25A in cell proliferation and apoptosis, as well as the impact of overexpression of Cdc25A on tumorigenesis.
Tumor cell migration and invasion play fundamental roles in cancer metastasis. The mammalian target of rapamycin (mTOR), a highly conserved and ubiquitously expressed serine/threonine (Ser/Thr) ...kinase, is a central regulator of cell growth, proliferation, differentiation and survival. Recent studies have shown that mTOR also plays a critical role in the regulation of tumor cell motility, invasion and cancer metastasis. Current knowledge indicates that mTOR functions as two distinct complexes, mTORC1 and mTORC2. mTORC1 phosphorylates p70 S6 kinase (S6K1) and eukaryotic initiation factor 4E (eIF4E) binding protein 1 (4E-BP1), and regulates cell growth, proliferation, survival and motility. mTORC2 phosphorylates Akt, protein kinase C α (PKCα) and the focal adhesion proteins, and controls the activities of the small GTPases (RhoA, Cdc42 and Rac1), and regulates cell survival and the actin cytoskeleton. Here we briefly review recent knowledge of mTOR complexes and the role of mTOR signaling in tumor cell migration and invasion. We also discuss recent efforts about the mechanism by which rapamycin, a specific inhibitor of mTOR, inhibits cell migration, invasion and cancer metastasis.
The targets of curcumin Zhou, Hongyu; Beevers, Christopher S; Huang, Shile
Current drug targets,
03/2011, Letnik:
12, Številka:
3
Journal Article
Recenzirano
Odprti dostop
Curcumin (diferuloylmethane), an orange-yellow component of turmeric or curry powder, is a polyphenol natural product isolated from the rhizome of the plant Curcuma longa. For centuries, curcumin has ...been used in some medicinal preparation or used as a food-coloring agent. In recent years, extensive in vitro and in vivo studies suggested curcumin has anticancer, antiviral, antiarthritic, anti-amyloid, antioxidant, and anti-inflammatory properties. The underlying mechanisms of these effects are diverse and appear to involve the regulation of various molecular targets, including transcription factors (such as nuclear factor-kB), growth factors (such as vascular endothelial cell growth factor), inflammatory cytokines (such as tumor necrosis factor, interleukin 1 and interleukin 6), protein kinases (such as mammalian target of rapamycin, mitogen-activated protein kinases, and Akt) and other enzymes (such as cyclooxygenase 2 and 5 lipoxygenase). Thus, due to its efficacy and regulation of multiple targets, as well as its safety for human use, curcumin has received considerable interest as a potential therapeutic agent for the prevention and/or treatment of various malignant diseases, arthritis, allergies, Alzheimer's disease, and other inflammatory illnesses. This review summarizes various in vitro and in vivo pharmacological aspects of curcumin as well as the underlying action mechanisms. The recently identified molecular targets and signaling pathways modulated by curcumin are also discussed here.
Influenza A viruses (IAVs) are contagious pathogens responsible for severe respiratory infection in humans and animals worldwide. Upon detection of IAV infection, host immune system aims to defend ...against and clear the viral infection. Innate immune system is comprised of physical barriers (mucus and collectins), various phagocytic cells, group of cytokines, interferons (IFNs), and IFN-stimulated genes, which provide first line of defense against IAV infection. The adaptive immunity is mediated by B cells and T cells, characterized with antigen-specific memory cells, capturing and neutralizing the pathogen. The humoral immune response functions through hemagglutinin-specific circulating antibodies to neutralize IAV. In addition, antibodies can bind to the surface of infected cells and induce antibody-dependent cell-mediated cytotoxicity or complement activation. Although there are neutralizing antibodies against the virus, cellular immunity also plays a crucial role in the fight against IAVs. On the other hand, IAVs have developed multiple strategies to escape from host immune surveillance for successful replication. In this review, we discuss how immune system, especially innate immune system and critical molecules are involved in the antiviral defense against IAVs. In addition, we highlight how IAVs antagonize different immune responses to achieve a successful infection.
Ciclopirox (CPX), a broad-spectrum fungicide, has been widely used to treat fungal infection on the skin and nails for decades. Recent preclinical and clinical studies have shown that CPX also ...possesses promising anticancer activity.
The objective of this study is to summarize the patents, the pharmacological and toxicological properties, the anticancer activity, and the mechanisms of action of CPX and its derivatives as anticancer agents.
PubMed and Google using the keywords "ciclopirox", "cancer or tumor" and "patent" were searched, and the identified literature was reviewed.
Pharmacological and toxicological profiles from preclinical and clinical studies support that systemic administration of CPX and its derivatives is feasible and safe for cancer treatment. CPX exerts its anticancer activity by inhibiting cell proliferation, inducing apoptosis, suppressing cell migration and invasion, and inhibiting angiogenesis and lymphangiogenesis. Mechanistically, CPX impacts the expression or activities of multiple signaling molecules or pathways, such as ribonucleotide reductase, Myc, DJ-1, Wnt/β-catenin, DOHH/eIF5A/PEAK1, VEGFR-3/ERK1/2, ATR/Chk1/Cdc25A, and AMPK/TSC/mTORC1. Most of these effects are attributed to iron chelation by CPX. Five patents have been retrieved: four patents on the development of CPX prodrugs to improve the water solubility and bioavailability of CPX, and one patent on the methods of bladder cancer treatment with CPX, CPX-O, or a CPX prodrug.
CPX has a great potential to be repositioned for cancer therapy.
Ciclopirox (CPX) has been used as an antifungal agent in various formulations to treat superficial fungal infection for decades. Its effectiveness and safety in treatments have been demonstrated by ...multiple studies.
Here we briefly summarize the pharmacological and toxicological properties of CPX as an antifungal agent, the new medical uses of CPX, as well as the correspondent molecular mechanisms.
Increasing evidence has demonstrated that CPX is able to inhibit tumor growth, ameliorate diabetes and its complications, prevent human immunodeficiency virus (HIV) infection, and improve age-associated cardiovascular defects. Interestingly, its antifungal activity and all those newly observed effects are more or less related to its capability of chelating iron and interfering with the related signaling pathways. Mechanistically, CPX is capable of modulating the activities of certain enzymes or signaling pathways, such as ribonucleotide reductase (RR), deoxyhypusine hydroxylase (DOHH)/eukaryotic translation initiation factor 5A (eIF5A), Wnt/β-catenin, hypoxia-inducible factor-1α (HIF-1 α)/vascular endothelial growth factor (VEGF), vascular endothelial growth factor receptor 3 (VEGFR-3)/extracellular signal-regulated protein kinases 1/2, mammalian target of rapamycin, and cyclin dependent kinases (CDKs). Most of these activities are related to its chelation of iron.
CPX, as an antifungal agent, may be repositioned for treatment of cancer and other human diseases.
Cadmium (Cd), a highly toxic environmental pollutant, induces neurodegenerative diseases. Recently we have demonstrated that Cd may induce neuronal apoptosis in part through activation of c-Jun ...N-terminal kinase (JNK) and extracellular signal-regulated kinase 1/2 (Erk1/2) pathways. However, the underlying mechanism remains enigmatic. Here we show that Cd induced generation of reactive oxygen species (ROS), leading to apoptosis of PC12 and SH-SY5Y cells. Pretreatment with
N-acetyl-L-cysteine (NAC) scavenged Cd-induced ROS, and prevented cell death, suggesting that Cd-induced apoptosis is attributed to its induction of ROS. Furthermore, we found that Cd-induced ROS inhibited serine/threonine protein phosphatases 2A (PP2A) and 5 (PP5), leading to activation of Erk1/2 and JNK, which was abrogated by NAC. Overexpression of PP2A or PP5 partially prevented Cd-induced activation of Erk1/2 and JNK, as well as cell death. Cd-induced ROS was also linked to the activation of caspase-3. Pretreatment with inhibitors of JNK (SP600125) and Erk1/2 (U0126) partially blocked Cd-induced cleavage of caspase-3 and prevented cell death. However, zVAD-fmk, a pan caspase inhibitor, only partially prevented Cd-induced apoptosis. The results indicate that Cd induction of ROS inhibits PP2A and PP5, leading to activation of JNK and Erk1/2 pathways, and consequently resulting in caspase-dependent and -independent apoptosis of neuronal cells. The findings strongly suggest that the inhibitors of JNK, Erk1/2, or antioxidants may be exploited for prevention of Cd-induced neurodegenerative diseases.
The mammalian target of rapamycin (mTOR) functions as two complexes (mTORC1 and mTORC2), regulating cell growth and metabolism. Aberrant mTOR signaling occurs frequently in cancers, so mTOR has ...become an attractive target for cancer therapy. Iron chelators have emerged as promising anticancer agents. However, the mechanisms underlying the anticancer action of iron chelation are not fully understood. Particularly, reports on the effects of iron chelation on mTOR complexes are inconsistent or controversial. Here, we found that iron chelators consistently inhibited mTORC1 signaling, which was blocked by pretreatment with ferrous sulfate. Mechanistically, iron chelation-induced mTORC1 inhibition was not related to ROS induction, copper chelation, or PP2A activation. Instead, activation of AMPK pathway mainly and activation of both HIF-1/REDD1 and Bnip3 pathways partially contribute to iron chelation-induced mTORC1 inhibition. Our findings indicate that iron chelation inhibits mTORC1 via multiple pathways and iron is essential for mTORC1 activation.
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