curcumin and 3-methyladenine

Curcumin, a polyphenolic compound, is a well-known anticancer agent, although its poor bioavailability remains a big concern. Recent studies suggest that autophagy-targeted therapy may be a useful adjunct treatment for patients with thyroid cancer. Curcumin acts as an autophagy inducer on many cancer cells. However, little is known about the exact role of curcumin on thyroid cancer cells. In the present study, curcumin significantly inhibited the growth of thyroid cancer cells. Autophagy was markedly induced by curcumin treatment as evidenced by an increase in LC3-II conversion, beclin-1 accumulation, p62 degradation as well as the increased formation of acidic vesicular organelles (AVOs). 3-MA, an autophagy inhibitor, partially rescued thyroid cancer cells from curcumin-induced cell death. Additionally, curcumin was found to exert selective cytotoxicity on thyroid cancer cells but not normal epithelial cells and acted as an autophagy inducer through activation of MAPK while inhibition of mTOR pathways. Hyperactivation of the AKT/mTOR axis was observed in the majority of PTC samples we tested, and thyroid cancer cell lines along with cancer tissue specimens sustained a low basal autophagic activity. Taken together, our results provide new evidence that inducing autophagic cell death may serve as a potential anti-cancer strategy to handle thyroid cancer.

Topics: Adenine; Antineoplastic Agents; Autophagic Cell Death; Cell Line; Cell Line, Tumor; Cell Survival; Cells, Cultured; Curcumin; Humans; Proto-Oncogene Proteins c-akt; Signal Transduction; Thyroid Neoplasms; TOR Serine-Threonine Kinases

Experimental autoimmune myocarditis (EAM) is characterized by pronounced macrophage infiltration, cardiac necrosis, and cardiac fibrosis. Our previous studies have demonstrated that suppressed androgen receptor (AR) enables anti-inflammation to promote tissue repair by decreasing M1 macrophages and increasing M2 macrophages in an EAM model. Given that autophagy mediates inflammatory response in macrophages, we investigated whether AR inhibition executes its protective role in inflammation through the autophagy pathway in EAM.. To determine whether AR inhibition can perform its anti-inflammatory effects by upregulating autophagy, we pre-treated mice with 3-methyl adenine (3-MA), a pharmacological inhibitor of autophagy. Immunofluorescence assay and Western blot were used to detect autophagy levels and autophagy activity in five different groups. Immunofluorescence marked F4/80 and LC3 to illustrate the autophagy level in macrophages. TUNEL assays were used to detect the apoptosis level in heart tissue of five different groups.. We demonstrated that AR inhibition resolves injury with sustained inhibition of inflammatory cytokines associated with enhanced autophagy, especially in macrophages. Increased LC3II/I expression corroborated complete autolysosome formation detected by electron microscopy and correlated with degradation of SQSTM1/p62 in the AR inhibition group by Western blot. These effects could be reversed within 3-MA, a pharmacological inhibitor of autophagy. Specifically, pharmacological inhibition of autophagy increased apoptosis and inflammation, which could be attenuated by AR inhibition.. AR inhibition alleviates the inflammatory response and tissue apoptosis by enhancing autophagy, especially in macrophages.

Topics: Adenine; Androgen Receptor Antagonists; Animals; Anti-Inflammatory Agents; Apoptosis; Autoimmune Diseases; Autophagy; Curcumin; Disease Models, Animal; Macrophages; Male; Mice, Inbred BALB C; Myocarditis; Myocardium

BACKGROUND The aim of this study was to use a rat model of femoral fracture healing to study the effects of curcumin on cell autophagy, compared with treatment with 3-methyladenine (3-MA), an inhibitor of autophagy. MATERIAL AND METHODS Thirty-six Sprague-Dawley rats with right mid-femoral fracture were divided into three groups: the curcumin-treated group (N=12) (gavage with curcumin 400 mg/kg/day); the curcumin + 3-MA-treated group (gavage with curcumin 400 mg/kg/day + 3-MA 30 mg/kg/day); and the control group (N=12) (gavage normal saline). Each group underwent femoral bone imaging using anteroposterior X-ray and micro-computed tomography (CT) at two weeks and six weeks following bone fracture. All rats were euthanized at the end of the study. Histology of the bone was performed to compare bone healing. Immunofluorescence and immunohistochemical tissue staining and Western blots were performed, to compare the expression of autophagy-related proteins, Beclin-1 and LC3-II. RESULTS Autophagy of rat femoral bone tissue was activated following fracture, increasing with time, reaching a peak at 24 hours. Imaging and histology showed that curcumin promoted the fracture healing in rats, which was reduced by treatment with 3-MA. Immunohistochemistry, immunofluorescence, and Western blot showed that curcumin treatment increased the expression of Beclin-1 and LC3-II, which were reduced by treatment with the autophagy inhibitor, 3-MA. CONCLUSIONS The findings of this study, in a rat model of femoral bone fracture healing, showed that curcumin promoted bone healing and autophagy, which were reduced by treatment with 3-MA, a known inhibitor of autophagy.

Topics: Adenine; Animals; Autophagy; Bone and Bones; Curcumin; Femoral Fractures; Femur; Fracture Healing; Male; Models, Animal; Rats; Rats, Sprague-Dawley; X-Ray Microtomography

Curcumin possesses an anticancer effect against a wide assortment of tumors with selective cytotoxicity for tumor cells. However, the mechanism involved in the curcumin‑induced anticancer effect remain unclear. In the present study, we investigated the efficacy of curcumin against human gastric cancer cell growth and the molecular mechanism involved. Our results demonstrated that curcumin inhibited the viabilities of gastric cancer cell lines BGC-823, SGC-7901 and MKN-28 in both a time- and dose-dependent manner. In addition, curcumin treatment induced gastric cancer cell apoptosis in a dose‑responsive manner. Western blotting of apoptosis‑related proteins further confirmed the pro-apoptotic potential of curcumin. After exposure to curcumin, a robust induction of autophagy was observed in gastric cancer cells, which was characterized by the formation of acidic vesicular organelles (AVOs), conversion of LC3-I to LC3-II and an increase in the levels of autophagy‑related proteins. Activation of the PI3K/Akt/mTOR signaling pathway was suppressed in gastric cancer cells with curcumin treatment. However, administration of the autophagy inhibitor 3-methyladenine (3-MA) significantly promoted the apoptotic cell death induced by curcumin. Collectively, our findings provide new evidence that curcumin induces apoptotic cell death and protective autophagy in human gastric cancer cells in vitro. Autophagy inhibitor treatment may provide a novel and effective strategy for improving the anticancer effect of curcumin against gastric cancer.

Topics: Adenine; Apoptosis; Apoptosis Regulatory Proteins; Autophagy; Cell Line, Tumor; Curcumin; Gene Expression Regulation, Neoplastic; Humans; Phosphatidylinositol 3-Kinases; Proto-Oncogene Proteins c-akt; Stomach Neoplasms; TOR Serine-Threonine Kinases

Our previous studies have indicated that a novel curcumin derivate nicotinate-curcumin (NC) has beneficial effects on the prevention of atherosclerosis, but the precise mechanisms are not fully understood. Given that autophagy regulates lipid metabolism, the present study was designed to investigate whether NC decreases foam cell formation through restoring autophagy flux in oxidized low-density lipoprotein (ox-LDL)-treated THP-1 cells. Our results showed that ox-LDL (100 μg/ml) was accumulated in THP-1 cells and impaired autophagy flux. Ox-LDL-induced impairment of autophagy was enhanced by treatment with the autophagy inhibitor chloroquine (CQ) and rescued by the autophagy inducer rapamycin. The aggregation of ox-LDL was increased by CQ, but decreased by rapamycin. In addition, colocalization of lipid droplets with LC3-II was remarkably reduced in ox-LDL group. In contrast, NC (10 μM) rescued the impaired autophagy flux by significantly increasing level of LC3-II, the number of autophagolysosomes, and the degradation of p62 in ox-LDL-treated THP-1 cells. Inhibition of the PI3K-Akt-mTOR signaling was required for NC-rescued autophagy flux. Notably, our results showed that NC remarkably promoted the colocalization of lipid droplets with autophagolysosomes, increased efflux of cholesterol, and reduced ox-LDL accumulation in THP-1 cells. However, treatment with 3-methyladenine (3-MA) or CQ reduced the protective effects of NC on lipid accumulation. Collectively, the findings suggest that NC decreases lipid accumulation in THP-1 cells through restoring autophagy flux, and further implicate that NC may be a potential therapeutic reagent to reverse atherosclerosis.

Topics: Adenine; Atherosclerosis; Autophagy; Cell Line; Chloroquine; Cholesterol; Curcumin; Foam Cells; Humans; Lipid Metabolism; Lipoproteins, LDL; Macrophages; Niacin; Phosphatidylinositol 3-Kinases; Proto-Oncogene Proteins c-akt; Signal Transduction; TOR Serine-Threonine Kinases

Parkinson's disease (PD) is pathologically characterized by the presence of α-synuclein positive intracytoplasmic inclusions. The missense mutation, A53T α-synuclein is closely related to hereditary, early-onset PD. Accumulating evidences suggest that pathological accumulation of A53T α-synuclein protein will perturb itself to be efficiently and normally degraded through its usual degradation pathway, macroautophagy-lysosome pathway, therefore toxic effects on the neuron will be exacerbated. Based on the above fact, we demonstrated in this study that A53T α-synuclein overexpression impairs macroautophagy in SH-SY5Y cells and upregulates mammalian target of rapamycin (mTOR)/p70 ribosomal protein S6 kinase (p70S6K) signaling, the classical suppressive pathway of autophagy. We further found that curcumin, a natural compound derived from the curry spice turmeric and with low toxicity in normal cells, could efficiently reduce the accumulation of A53T α-synuclein through downregulation of the mTOR/p70S6K signaling and recovery of macroautophagy which was suppressed. These findings suggested that the regulation of mTOR/p70S6K signaling may be a participant of the accumulation of A53T α-synuclein protein-linked Parkinsonism. Meanwhile curcumin could be a candidate neuroprotective agent by inducing macroautophagy, and needs to be further investigated by clinical application in patients suffering Parkinson's disease.

Topics: Adenine; alpha-Synuclein; Autophagy; Blotting, Western; Cell Line; Cell Survival; Curcumin; Genetic Vectors; Humans; Immunohistochemistry; Macrophages; Neurodegenerative Diseases; Neuroprotective Agents; Parkinson Disease; Ribosomal Protein S6 Kinases, 70-kDa; TOR Serine-Threonine Kinases; Transfection

Novel ruthenium-letrozole complexes have been prepared, and cell viability of two human cancer cell types (breast and glioblastoma) was determined. Some ruthenium compounds are known for their cytotoxicity to cancer cells, whereas letrozole is an aromatase inhibitor administered after surgery to post-menopausal women with hormonally responsive breast cancer. A significant in vitro activity was established for complex 5·Let against breast cancer MCF-7 cells and significantly lower activity against glioblastoma U251N cells. The activity of 5·Let was even higher than that of 4, a compound analogous to the well-known drug RAPTA-C. Results from the combination of 5·Let (or 4) with 3-methyladenine (3-MA) or with curcumin, respectively, revealed that the resultant cancer cell death likely involves 5·Let-induced autophagy.

Topics: Adenine; Adenocarcinoma; Antineoplastic Agents; Aromatase Inhibitors; Autophagy; Breast Neoplasms; Cell Line, Tumor; Cell Proliferation; Cell Survival; Coordination Complexes; Crystallography, X-Ray; Curcumin; Drug Interactions; Drug Screening Assays, Antitumor; Female; Glioblastoma; Humans; Letrozole; Nitriles; Ruthenium; Stereoisomerism; Structure-Activity Relationship; Triazoles

Autophagy (type II programmed cell death) is crucial for maintaining cellular homeostasis. Several autophagy-deficient or knockout studies indicate that autophagy is a tumor suppressor. Tetrahydrocurcumin (THC), a major metabolite of curcumin, has been demonstrated with anti-colon carcinogenesis and antioxidation in vivo.. In the present study, we found that treatment with THC induced autophagic cell death in human HL-60 promyelocytic leukemia cells by increasing autophage marker acidic vascular organelle (AVO) formation. Flow cytometry also confirmed that THC treatment did not increase sub-G1 cell population whereas curcumin did with strong apoptosis-inducing activity. At the molecular levels, the results from Western blot analysis showed that THC significantly down-regulated phosphatidylinositol 3-kinase/protein kinase B and mitogen-activated protein kinase signalings including decreasing the phosphorylation of mammalian target of rapamycin, glycogen synthase kinase 3β and p70 ribosomal protein S6 kinase. Further molecular analysis exhibited that the pretreatment of 3-methyladenine (an autophagy inhibitor) also significantly reduced acidic vascular organelle production in THC-treated cells.. Taken together, these results demonstrated the anticancer efficacy of THC by inducing autophagy as well as provided a potential application for the prevention of human leukemia.

Topics: Adenine; Antineoplastic Agents, Phytogenic; Apoptosis Regulatory Proteins; Autophagy; Beclin-1; Cell Proliferation; Curcumin; Down-Regulation; HL-60 Cells; Humans; Leukemia, Myeloid; MAP Kinase Signaling System; Membrane Proteins; Microtubule-Associated Proteins; Neoplasm Proteins; Phosphatidylinositol 3-Kinases; Phosphorylation; Protein Processing, Post-Translational; Proto-Oncogene Proteins c-akt; Signal Transduction; TOR Serine-Threonine Kinases