Extracellular signal-regulated kinase signaling-mediated induction and interaction of FOXO3a and p53 contribute to the inhibition of nasopharyngeal carcinoma cell growth by curcumin

Targeted therapies of curcumin focus on its therapeutic benefits in cancers and human health: Molecular signaling pathway-based approaches and future perspectives

The curry powder spices turmeric (Curcuma longa L.), which contains curcumin (diferuloylmethane), an orange-yellow chemical. Polyphenols are the most commonly used sources of curcumin. It combats oxidative stress and inflammation in diseases, such as hyperlipidemia, metabolic syndrome, arthritis, and depression. Most of these benefits are due to their anti-inflammatory and antioxidant properties. Curcumin consumption leads to decreased bioavailability, resulting in limited absorption, quick metabolism, and quick excretion, which hinders health improvement. Numerous factors can increase its bioavailability. Piperine enhances bioavailability when combined with curcumin in a complex. When combined with other enhancing agents, curcumin has a wide spectrum of health benefits. This review evaluates the therapeutic potential of curcumin with a specific emphasis on its approach based on molecular signaling pathways. This study investigated its influence on the progression of cancer, inflammation, and many health-related mechanisms, such as cell proliferation, apoptosis, and metastasis. Curcumin has a significant potential for the prevention and treatment of various diseases. Curcumin modulates several biochemical pathways and targets involved in cancer growth. Despite its limited tissue accumulation and bioavailability when administered orally, curcumin has proven useful. This review provides an in-depth analysis of curcumin's therapeutic applications, its molecular signaling pathway-based approach, and its potential for precision medicine in cancer and human health.

The efficacy of natural products for the treatment of nasopharyngeal carcinoma

Nasopharyngeal carcinoma (NPC) is a malignant tumor originating in the nasopharyngeal epithelium with a high incidence in southern China and parts of Southeast Asia. The current treatment methods are mainly radiotherapy and chemotherapy. However, they often have side effects and are not suitable for long-term exposure. Natural products have received more and more attention in cancer prevention and treatment because of their its high efficiency, low toxic side effects, and low toxicity. Natural products can serve as a viable alternative, and this study aimed to review the efficacy and mechanisms of natural products in the treatment of NPC by examining previous literature. Most natural products act by inhibiting cell proliferation, metastasis, inducing cell cycle arrest, and apoptosis. Although further research is needed to verify their effectiveness and safety, natural products can significantly improve the treatment of NPC.

Impact of curcumin on p38 MAPK: therapeutic implications

Curcumin (diferuloylmethane) is a herbal remedy which possesses numerous biological attributes including anti-inflammatory, anti-oxidant and anti-cancer properties. Curcumin has been shown to impact a number of signaling pathways including nuclear factor kappa B (NF-KB), reactive oxygen species (ROS), Wingless/Integrated (Wnt), Janus kinase-signal transducer and activator of mitogen-activated protein kinase (MAPK) and transcription (JAK/STAT). P38 belongs to the MAPKs, is known as a stress-activated MAPK and is involved in diverse biological responses. P38 is activated in various signaling cascades. P38 plays a role in inflammation, cell differentiation, proliferation, motility and survival. This cascade can serve as a therapeutic target in many disorders. Extensive evidence confirms that curcumin impacts the P38 MAPK signaling pathway, through which it exerts anti-inflammatory, neuroprotective, and apoptotic effects. Hence, curcumin can positively affect inflammatory disorders and cancers, as well as to increase glucose uptake in cells. This review discusses the pharmacological and therapeutic effects of curcumin as effected through p38 MAPK.

Functional drug-target-disease network analysis of gene-phenotype connectivity for curcumin in hepatocellular carcinoma

Background

The anti-tumor properties of curcumin have been demonstrated for many types of cancer. However, a systematic functional and biological analysis of its target proteins has yet to be fully documented. The aim of this study was to explore the underlying mechanisms of curcumin and broaden the perspective of targeted therapies.

Methods

Direct protein targets (DPTs) of curcumin were searched in the DrugBank database. Using the STRING database, the interactions between curcumin and DPTs and indirect protein targets (IPTs) weres documented. The protein-protein interaction (PPI) network of curcumin-mediated proteins was visualized using Cytoscape. Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway enrichment analysis was performed for all curcumin-mediated proteins. Furthermore, the cancer targets were searched in the Comparative Toxicogenomics Database (CTD). The overlapping targets were studied using Kaplan-Meier analysis to evaluate cancer survival. Further genomic analysis of overlapping genes was conducted using the cBioPortal database. Lastly, MTT, quantitative polymerase chain reaction (qPCR), and western blot (WB) analysis were used to validate the predicted results on hepatocellular carcinoma (HCC) cells.

Results

A total of five DPTs and 199 IPTs were found. These protein targets were found in 121 molecular pathways analyzed via KEGG enrichment. Based on the anti-tumor properties of curcumin, two pathways were selected, including pathways in cancer (36 genes) and HCC (22 genes). Overlapping with 505 HCC-related gene sets identified in CTD, five genes (TP53, RB1, TGFB1, GSTP1, and GSTM1) were finally identified. High mRNA levels of TP53, RB1, and GSTM1 indicated a prolonged overall survival (OS) in HCC, whereas elevated mRNA levels of TGFB1 were correlated with poor prognosis. The viability of both HepG2 cells and Hep3B cells was significantly reduced by curcumin at concentrations of 20 or 30 μM after 48 or 72 h of culture. At a concentration of 20 μM curcumin cultured for 48 h, the expression of TGFB1 and GSTP1 in Hep3B cells was reduced significantly in qPCR analysis, and reduced TGFB1 protein expression was also found in Hep3B cells.

Curcumin reverses diabetic nephropathy in streptozotocin-induced diabetes in rats by inhibition of PKCβ/p66Shc axis and activation of FOXO-3a

This study investigated if the nephroprotective effect of Curcumin in streptozotocin-induced type 1 diabetes mellitus (DM) in rats involves downregulation/inhibition of p66Shc and examined the underlying mechanisms. Rats were divided into 4 groups (n = 12/group) as control, control + Curcumin (100 mg/kg), T1DM, and T1DM + Curcumin. Curcumin was administered orally to control or diabetic rats for 12 weeks daily. As compared to diabetic rats, Curcumin didn't affect either plasma glucose or insulin levels but significantly reduced serum levels of urea, blood urea nitrogen, and creatinine, and concurrently reduced albumin/protein urea and increased creatinine clearance. It also prevented the damage in renal tubules and mitochondria, mesangial cell expansion, the thickness of the basement membrane. Mechanistically, Curcumin reduced mRNA and protein levels of collagen I/III and transforming growth factor- β-1 (TGF-β1), reduced inflammatory cytokines levels, improved markers of mitochondrial function, and suppressed the release of cytochrome-c and the activation of caspase-3. In the kidneys of both control and diabetic rats, Curcumin reduced the levels of reactive oxygen species (ROS), increased mRNA levels of manganese superoxide dismutase (MnSOD) and gamma-glutamyl ligase, increased glutathione (GSH) and protein levels of Bcl-2 and MnSOD, and increased the nuclear levels of nuclear factor2 (Nrf2) and FOXO-3a. Besides, Curcumin reduced the nuclear activity of the nuclear factor-kappa B (NF-κB), downregulated protein kinase CβII (PKCβII), NADPH oxidase, and p66Shc, and decreased the activation of p66Shc. In conclusion, Curcumin prevents kidney damage in diabetic rats by activating Nrf2, inhibiting Nf-κB, suppressing NADPH oxidase, and downregulating/inhibiting PKCβII/p66Shc axis.

Curcumin and wikstroflavone B, a new biflavonoid isolated from Wikstroemia indica, synergistically suppress the proliferation and metastasis of nasopharyngeal carcinoma cells via blocking FAK/STAT3 signaling pathway

BACKGROUND

Curcumin (CUR) is a natural diarylheptanoid with marked anti-tumor activities. Recent investigations demonstrate that CUR combines with some other phytochemicals exerts advantages over its single application manifested as lower toxicity, higher efficacy or more significant reversal of multidrug resistance.

PURPOSE

This study aimed to elucidate a new biflavonoid (wikstroflavone B, WFB) isolated from Wikstroemia indica and to assess the synergistic inhibition of combined CUR and WFB (CUR/WFB) on human nasopharyngeal carcinoma (NPC) cell lines proliferation and metastasis.

METHODS

WFB was obtained through sequential chromatographic methods including silica gel, Sephadex LH-20 and preparative HPLC. Its structure was determined by HRESIMS, 1D and 2D NMR spectroscopic analysis. The absolute configuration of WFB was assigned through comparison of experimental and calculated optical rotation (OR) values. Changes in cellular viability, migration and invasion were assessed by MTT, colony formation, wound healing and Transwell assays. The nature of synergistic interaction of CUR/WFB was determined through the combination index (CI) method under the median-effect analysis. Expression levels of indicated mRNAs and proteins were measured by qRT-PCR and Western blotting assays, respectively.

RESULTS

WFB was isolated and structural elucidated. Compared with CUR or WFB used alone, CUR/WFB treatment inhibited more effectively on the cell viability, colony formation, cell migration and invasion. Both CI and dose reduction index (DRI) values indicated the significant synergistic effects existed between CUR and WFB. Besides, CUR/WFB showed the marked modulation on the genes involved in cell proliferation (survivin, cyclin D1, p53 and p21) and metastasis (MMP-2, MMP-9 and FAK). CUR/WFB treatment was also found to restrain the phosphorylation of FAK and STAT3 proteins. When pretreatment with a FAK inhibitor, the cell viability and metastasis were significantly attenuated.

CONCLUSION

The results indicate that WFB can synergistically increase the inhibitory effects of CUR on NPC cells proliferation and metastasis, and these findings may afford a rational approach for developing the antitumor medications.

Lapatinib sensitivity in nasopharyngeal carcinoma is modulated by SIRT2-mediated FOXO3 deacetylation

Background

Chemoresistance is an obstacle to the successful treatment of nasopharyngeal carcinoma (NPC). Lapatinib is a targeted tyrosine kinase inhibitor therapeutic drug also used to treat NPC, but high doses are often required to achieve a result. To investigate the mechanism for the development of Lapatinib resistance, we characterised a number of NPC cell lines to determine the role of FOXO3 and sirtuins in regulating NPC resistance.

Methods

Sulforhodamine B (SRB) assays, Clonogenic assays, Protein extraction, quantification and western blotting, RT qPCR, Co-immunoprecipitation assay.

Results

To explore novel treatment strategies, we first characterized the Lapatinib-sensitivity of a panel of NPC cell lines by SRB and clonogenic cytotoxic assays and found that the metastatic NPC (C666–1 and 5-8F) cells are highly resistant whereas the poorly metastatic lines (6-10B, TW01 and HK-1) are sensitive to Lapatinib. Western blot analysis of the Lapatinib-sensitive 6-10B and resistant 5-8F NPC cells showed that the expression of phosphorylated/inactive FOXO3 (P-FOXO3;T32), its target FOXM1 and its regulator SIRT2 correlate negatively with Lapatinib response and sensitivity, suggesting that SIRT2 mediates FOXO3 deacetylation to promote Lapatinib resistance. In agreement, clonogenic cytotoxic assays using wild-type and foxo1/3/4^−/− mouse embryonic fibroblasts (MEFs) showed that FOXO1/3/4-deletion significantly attenuates Lapatinib-induced cytotoxicity, confirming that FOXO proteins are essential for mediating Lapatinib response. SRB cell viability assays using chemical SIRT inhibitors (i.e. sirtinol, Ex527, AGK2 and AK1) revealed that all SIRT inhibitors can reduce NPC cell viability, but only the SIRT2-specific inhibitors AK1 and AGK2 further enhance the Lapatinib cytotoxicity. Consistently, clonogenic assays demonstrated that the SIRT2 inhibitors AK1 and AGK2 as well as SIRT2-knockdown increase Lapatinib cytotoxicity further in both the sensitive and resistant NPC cells. Co-immunoprecipitation studies showed that besides Lapatinib treatment, SIRT2-pharmaceutical inhibition and silencing also led to an increase in FOXO3 acetylation. Importantly, SIRT2 inhibition and depletion further enhanced Lapatinib-mediated FOXO3-acetylation in NPC cells.

Conclusion

Collectively, our results suggest the involvement of SIRT2-mediated FOXO3 deacetylation in Lapatinib response and sensitivity, and that SIRT2 can specifically antagonise the cytotoxicity of Lapatinib through mediating FOXO3 deacetylation in both sensitive and resistant NPC cells. The present findings also propose that SIRT2 can be an important biomarker for metastatic and Lapatinib resistant NPC and that targeting the SIRT2-FOXO3 axis may provide novel strategies for treating NPC and for overcoming chemoresistance.

Effects of tanshinones mediated by forkhead box O3a transcription factor on the proliferation and apoptosis of lung cancer cells

According to global cancer statistics in 2012, lung cancer (LC) was the most frequently diagnosed cancer and the leading cause of cancer-associated mortality among males worldwide. Owing to the limited therapeutic approaches available, novel methods for treating LC are required. Tanshinones (Ts) have previously been proved to be effective in treating cardiovascular disease, inflammatory disease and cancer, and have been reported to regulate cell proliferation and apoptosis of LC. The underlying molecular mechanism of action of Ts remains unclear. Furthermore, forkhead box O3a (FoxO3a) has been reported to be a critical gene in cell apoptosis. Therefore, the A549 lung cancer cell line was transfected with FoxO3a small interfering RNA (siRNA) or scrambled siRNA, and the cells which exhibited the most successful transfection efficacy were selected for further investigation into the underlying molecular mechanism of the influence of Ts on FoxO3a in LC cells. Various concentrations of Ts were assigned to experimental groups I-IV (5, 10, 20 and 30 µmol/l Ts, respectively). An MTT assay revealed that Ts inhibited cell proliferation in a dose- and time-dependent manner compared with the control group (CON; without Ts administration) with a maximal dose of 20 µmol/l at 72 h treatment (P<0.05). Similarly, compared with CON, flow cytometry results revealed that Ts induce LC cell apoptosis in a dose-dependent manner (P<0.05). Consistently, the expression levels of FoxO3a mRNA and protein were restored following treatment with Ts in a dose-dependent manner, alongside caspase-3 activation. On the basis of these results, we hypothesize that Ts regulate LC cell proliferation and apoptosis by triggering an apoptotic cascade through the FoxO3a/caspase-3 signaling pathway.

Downregulation of glucose-regulated protein 78 enhances the cytotoxic effects of curcumin on human nasopharyngeal carcinoma cells

Curcumin is a conventional Chinese medicine, which exerts a marked effect on various tumor types and suppresses tumor invasion. The present study analyzed the antineoplastic effects of curcumin on human nasopharyngeal carcinoma (NPC) cells and determined the effects of endoplasmic reticulum (ER) stress on curcumin‑induced cytotoxicity. The Cell Counting Kit‑8 assay examined the viability of SUNE1 and SUNE2 NPC cells. The Annexin V/propidium iodide staining technique was used to detect cell apoptosis and flow cytometry was used to examine cell cycle distribution. Western blotting and immunofluorescence were used to detect ER stress‑associated molecules. Furthermore, the toxic effects of curcumin treatment alongside glucose‑regulated protein 78 (GRP78) knockdown using small interfering (si)RNA, and treatment with the pan‑caspase inhibitor Z‑VAD‑FMK and the protein kinase B (AKT) inhibitor MK‑2206 were detected. The results demonstrated that curcumin markedly reduced cell viability, blocked cell cycle progression and induced apoptosis of human NPC cells. In addition, curcumin activated ER stress‑associated proteins to participate in the apoptosis of human NPC cells. siRNA‑induced knockdown of GRP78 may be able to strengthen the toxic effects of curcumin through mediating the AKT signaling pathway. These findings indicated that downregulation of GRP78 promoted the therapeutic effects of curcumin on NPC cells. The present study identified a potential, novel therapeutic method for the treatment of NPC.

Curcumin exerts its antitumor activity through regulation of miR-7/Skp2/p21 in nasopharyngeal carcinoma cells

Curcumin, a natural polyphenol compound, exhibits tumor suppressive activity in a wide spectrum of cancers, including nasopharyngeal carcinoma cells. However, the exact molecular mechanisms governing this tumor suppressive activity remain elusive. Multiple studies have revealed that miRNAs are critically involved in tumorigenesis, indicating that targeting miRNAs could be a therapeutic strategy for treating human cancer. In the current study, we set out to determine whether curcumin regulates miR-7 expression in nasopharyngeal carcinoma cells. We found that curcumin inhibited cell growth, induced apoptosis, retarded cell migration and invasion, and triggered cell cycle arrest in the human nasopharyngeal carcinoma cell lines CNE1 and CNE2. Importantly, we observed that curcumin upregulated the expression of miR-7 and subsequently inhibited Skp2, a direct miR-7 target. Our results identified that upregulation of miR-7 by curcumin could benefit nasopharyngeal carcinoma patients.

Anticancer Activity of Curcumin and Its Analogues: Preclinical and Clinical Studies

Curcumin has been shown to have a wide variety of therapeutic effects, ranging from anti-inflammatory, chemopreventive, anti-proliferative, and anti-metastatic. This review provides an overview of the recent research conducted to overcome the problems with the bioavailability of curcumin, and of the preclinical and clinical studies that have reported success in combinatorial strategies coupling curcumin with other treatments. Research on the signaling pathways that curcumin treatment targets shows that it potently acts on major intracellular components involved in key processes such as genomic modulations, cell invasion and cell death pathways. Curcumin is a promising molecule for the prevention and treatment of cancer.

Molecular mechanisms of cholangiocarcinoma cell inhibition by medicinal plants

Cholangiocarcinoma (CCA) is one of the most common causes of cancer-associated mortality in Thailand. Certain phytochemicals have been demonstrated to modulate apoptotic signaling pathways, which may be targeted for the prevention and treatment of cancer. Therefore, the aim of the present study was to investigate the effect of specific medicinal plants on the inhibition of CCA cell proliferation, and to identify the molecular mechanisms underlying this. A WST-1 cell proliferation assay was performed using an RMCCA1 cell line, and apoptotic signaling pathways were also investigated using a PathScan Stress and Apoptosis Signaling Antibody Array Kit. The cell proliferation assay indicated that extracts from the Phyllanthus emblica fruit pulp (PEf), Phyllanthus emblica seed (PEs), Terminalia chebula fruit pulp (TCf), Terminalia chebula seed (TCs), Areca catechu seed (ACs), Curcuma longa (CL) and Moringa oleifera seed (MOs) exerted anti-proliferative activity in RMCCA1 cells. In addition, the PathScan assay revealed that certain pro-apoptotic molecules, including caspase-3, poly (ADP-ribose) polymerase, checkpoint kinase 2 and tumor protein 53, exhibited increased activity in RMCCA1 cells treated with the aforementioned selected plant extracts, with the exception of PEf. The mitogen-activated protein kinase (MAPK) pathways (including ERK1/2 and p38 MAPK) expression level was significantly increased in RMCCA1 cells pre-treated with extracts of PEs, TCf, CL and MOs. The activation of protein kinase B (Akt) was significantly demonstrated in RMCCA1 cells pre-treated with extracts of TCf, ACs and MOs. In summary, the present study demonstrated that extracts of PEs, TCf, TCs, ACs, CL and MOs exhibited anti-proliferative effects in CCA cells by inducing pro-apoptotic signals and modulating signal transduction molecules. Further studies in vivo are required to demonstrate the potential applications of specific plant extracts for the treatment of human cancer.

Chinese Herbal Medicine Fuzheng Kang-Ai Decoction Inhibited Lung Cancer Cell Growth through AMPKα-Mediated Induction and Interplay of IGFBP1 and FOXO3a

The aim of this study is to investigate the actions of Chinese herbal medicine, called “Fuzheng Kang-Ai” (FZKA for short) decoction, against non-small cell lung cancer (NSCLC) and its mechanisms in vitro and in vivo. We showed that the effect of FZKA decoction significantly inhibited growth of A549 and PC9 cells. Furthermore, FZKA increased phosphorylation of AMP-activated protein kinase alpha (AMPKα) and induced protein expression of insulin-like growth factor (IGF) binding protein 1 (IGFBP1) and forkhead homeobox type O3a (FOXO3a). The specific inhibitor of AMPKα (Compound C) blocked FZKA-induced protein expression of IGFBP1 and FOXO3a. Interestingly, silencing of IGFBP1 and FOXO3a overcame the inhibitory effect of FZKA on cell growth. Moreover, silencing of IGFBP1 attenuated the effect of FZKA decoction on FOXO3a expression, and exogenous expression of FOXO3a enhanced the FZKA-stimulated phosphorylation of AMPKα. Accordingly, FZKA inhibited the tumor growth in xenograft nude mice model. Collectively, our results show that FZKA decoction inhibits proliferation of NSCLC cells through activation of AMPKα, followed by induction of IGFBP1 and FOXO3a proteins. Exogenous expression of FOXO3a feedback enhances FZKA decoction-stimulated IGFBP1 expression and phosphorylation of AMPKα. The reciprocal interplay of IGFBP1 and FOXO3a contribute to the overall responses of FAKA decoction.

Analysis of the differential secretome of nasopharyngeal carcinoma cell lines CNE-2R and CNE-2

Radioresistance is the major cause of poor prognosis in nasopharyngeal carcinoma (NPC). To identify and characterize the secretome associated with NPC radioresistance, we compared the conditioned serum-free medium of radioresistant CNE-2R cells with that of the parental radiosensitive CNE-2 cells using isobaric tags for relative and absolute quantitation (iTRAQ) with liquid chromatography-electrospray tandem mass spectrometry (LC-ESI-MS/MS) quantitative proteomics. Before proceeding to quantitative proteomics, we investigated the survival curves of CNE-2R and CNE-2 cells by colony formation assay, and the CNE-2R survival curves were significantly higher than those for CNE-2. In total, 3,581 proteins were identified in the quantitative proteomics experiments, and 40 proteins exhibited significant differences between the CNE-2R and CNE-2 cells. Twenty-six of the 40 proteins were secreted by classical, non-classical, or exosomal secretion pathways. To verify the reliability of iTRAQ quantitative proteomics, we applied western blotting (WB) to study the secretory protein expression of fibrillin-2, CD166, sulfhydryl oxidase 1 and cofilin-2, which are involved in cell adhesion, migration and invasion. The WB results showed that fibrillin-2 (p=0.017) and sulfhydryl oxidase 1 (p=0.000) were highly expressed in the CNE-2 cells, while CD166 (p=0.012) and cofilin-2 (p=0.003) were highly expressed in the CNE-2R cells, which was in accordance with iTRAQ quantitative proteomics. Finally, a phenotypic subset of CD166-positive NPC cells was verified by immunocytochemistry. In summary, we defined a collection of secretory proteins that may be relevant to the radioresistance in NPC cells, and we determined that CD166, which is widely used as a positive marker of cancer stem cells, is expressed in NPC cells.

The beneficial role of curcumin on inflammation, diabetes and neurodegenerative disease: A recent update

The concept of using phytochemicals has ushered in a new revolution in pharmaceuticals. Naturally occurring polyphenols (like curcumin, morin, resveratrol, etc.) have gained importance because of their minimal side effects, low cost and abundance. Curcumin (diferuloylmethane) is a component of turmeric isolated from the rhizome of Curcuma longa. Research for more than two decades has revealed the pleiotropic nature of the biological effects of this molecule. More than 7000 published articles have shed light on the various aspects of curcumin including its antioxidant, hypoglycemic, anti-inflammatory and anti-cancer activities. Apart from these well-known activities, this natural polyphenolic compound also exerts its beneficial effects by modulating different signalling molecules including transcription factors, chemokines, cytokines, tumour suppressor genes, adhesion molecules, microRNAs, etc. Oxidative stress and inflammation play a pivotal role in various diseases like diabetes, cancer, arthritis, Alzheimer's disease and cardiovascular diseases. Curcumin, therefore, could be a therapeutic option for the treatment of these diseases, provided limitations in its oral bioavailability can be overcome. The current review provides an updated overview of the metabolism and mechanism of action of curcumin in various organ pathophysiologies. The review also discusses the potential for multifunctional therapeutic application of curcumin and its recent progress in clinical biology.

Baicalein increases the expression and reciprocal interplay of RUNX3 and FOXO3a through crosstalk of AMPKα and MEK/ERK1/2 signaling pathways in human non-small cell lung cancer cells

Background

Baicalein, a natural flavonoid obtained from the Scutellaria baicalensis root, has been reported to inhibit growth of human lung cancer. However, the detailed mechanism underlying this has not been well elucidated.

Methods

Cell viability was measured using a 3-(4, 5-dimethylthiazol-2-yl)-2, 5-diphenyltetrazolium bromide (MTT) assays. Apoptosis was detected by flow cytometry analysis and caspase 3/7 assays. The expression of RUNX3 and FOXO3a mRNA were measured by real time RT-PCR methods. Western blot analysis was performed to measure the phosphorylation and protein expression of AMP-activated protein kinase alpha (AMPKα) and extracellular signal-regulated kinase 1/2 (ERK1/2), runt-related transcription factor 3 (RUNX3) and forkhead box O3a (FOXO3a). Silencing of FOXO3a and RUNX3 were performed by small interfering RNA (siRNA) methods. Exogenous expression of FOXO3a or RUNX3 was carried out by electroporated transfection assays.

Results

We showed that baicalein significantly inhibited growth and induced apoptosis of non-small cell lung cancer (NSCLC) cells in a time- and dose-dependent manner. Baicalein induced RUNX3 and FOXO3a protein expression, and increased phosphorylation of AMPKα and ERK1/2. Moreover, the inhibitors of AMPK and MEK/ERK1/2 reversed the effect of baicalein on RUNX3 and FOXO3a protein expression. Interestingly, while compound C had little effect on blockade of baicalein-induced phosphorylation of ERK1/2, PD98059 significantly abrogated baicalein-induced phosphorylation of AMPKα. Intriguingly, while silencing of RUNX3 abolished the effect of baicalein on expression of FOXO3a and apoptosis, silencing of FOXO3a significantly attenuated baicalein-reduced cell proliferation. On the contrary, overexpression of FOXO3a restored the effect of baicalein on cell growth inhibition in cells silencing of endogenous FOXO3a gene and enhanced the effect of baicalein on RUNX3 protein expression. Finally, exogenous expression of RUNX3 increased FOXO3a protein and strengthened baicalein-induced phosphorylation of ERK1/2.

Conclusion

Collectively, our results show that baicalein inhibits growth and induces apoptosis of NSCLC cells through AMPKα- and MEK/ERK1/2-mediated increase and interaction of FOXO3a and RUNX3 protein. The crosstalk between AMPKα and MEK/ERK1/2 signaling pathways, and the reciprocal interplay of FOXO3a and RUNX3 converge on the overall response of baicalein. This study reveals a novel mechanism for regulating FOXO3a and RUNX3 signaling axis in response to baicalein and suggests a new strategy for NSCLC associated targeted therapy.

Curcumin induces apoptosis of upper aerodigestive tract cancer cells by targeting multiple pathways

Curcumin, a natural compound isolated from the Indian spice "Haldi" or "curry powder", has been used for centuries as a traditional remedy for many ailments. Recently, the potential use of curcumin in cancer prevention and therapy urges studies to uncover the molecular mechanisms associated with its anti-tumor effects. In the current manuscript, we investigated the mechanism of curcumin-induced apoptosis in upper aerodigestive tract cancer cell lines and showed that curcumin-induced apoptosis is mediated by the modulation of multiple pathways such as induction of p73, and inhibition of p-AKT and Bcl-2. Treatment of cells with curcumin induced both p53 and the related protein p73 in head and neck and lung cancer cell lines. Inactivation of p73 by dominant negative p73 significantly protected cells from curcumin-induced apoptosis, whereas ablation of p53 by shRNA had no effect. Curcumin treatment also strongly inhibited p-AKT and Bcl-2 and overexpression of constitutively active AKT or Bcl-2 significantly inhibited curcumin-induced apoptosis. Taken together, our findings suggest that curcumin-induced apoptosis is mediated via activating tumor suppressor p73 and inhibiting p-AKT and Bcl-2.

The multifaceted role of curcumin in cancer prevention and treatment

Despite significant advances in treatment modalities over the last decade, neither the incidence of the disease nor the mortality due to cancer has altered in the last thirty years. Available anti-cancer drugs exhibit limited efficacy, associated with severe side effects, and are also expensive. Thus identification of pharmacological agents that do not have these disadvantages is required. Curcumin, a polyphenolic compound derived from turmeric (Curcumin longa), is one such agent that has been extensively studied over the last three to four decades for its potential anti-inflammatory and/or anti-cancer effects. Curcumin has been found to suppress initiation, progression, and metastasis of a variety of tumors. These anti-cancer effects are predominantly mediated through its negative regulation of various transcription factors, growth factors, inflammatory cytokines, protein kinases, and other oncogenic molecules. It also abrogates proliferation of cancer cells by arresting them at different phases of the cell cycle and/or by inducing their apoptosis. The current review focuses on the diverse molecular targets modulated by curcumin that contribute to its efficacy against various human cancers.

Evaluation of two novel antioxidants with differential effects on curcumin-induced apoptosis in C2 skeletal myoblasts; involvement of JNKs

Excessive levels of reactive oxygen species (ROS) result in numerous pathologies including muscle disorders. In essence, skeletal muscle performance of daily activities can be severely affected by the redox imbalances occurring after muscular injuries, surgery, atrophy due to immobilization, dystrophy or eccentric muscle contraction. Therefore, research on the potential beneficial impact of antioxidants is of outmost importance. In this context, aiming at further exploring the mechanisms of action of our newly synthesized antioxidant compounds (AK1 and AK2) in a skeletal muscle experimental setting, we initially investigated their scavenging effect on 2,2-diphenyl-1-picrylhydrazyl (DPPH) and subsequently assessed their effect on the viability of C2 skeletal myoblasts in the presence of two pro-oxidants: H2O2 and curcumin (MTT assay). Interestingly, while both compounds reversed the detrimental effect of H2O2, only AK2 was cytoprotective in curcumin-treated C2 cells. We next confirmed the immediate activation of extracellular signal-regulated kinases (ERKs) and the more delayed activation profile of c-Jun NH2-terminal kinases (JNKs) in C2 skeletal myoblasts exposed to curcumin, by Western blotting. In correlation with the aforementioned results, only AK2 blocked the curcumin-induced activation of JNKs pathway. Furthermore, JNKs were revealed to mediate curcumin-induced apoptosis in C2 cells and only AK2 to effectively suppress it (by detecting its effect on poly(ADP-ribose) polymerase fragmentation). Overall, we have shown that two similar in structure novel antioxidants confer differential effects on C2 skeletal myoblasts viability under oxidative stress conditions. This result may be attributed to these antioxidants respective diverse mode of interaction with the signaling effectors involved in the observed responses. Future studies should further evaluate the mechanism of action of these compounds in order to support their potential application in therapeutic protocols against ROS-related muscle disorders.

Curcumin inhibits cell proliferation and induces apoptosis in cholangiocarcinoma

AIM: To investigate the effect of curcumin on proliferation and apoptosis of cholangiocarcinoma cells and whether curcumin shows a therapeutic effect on cholangicarcinoma in vivo.

METHODS: CCK-8 assay was employed to investigate the effect of curcumin on cell proliferation in cholangiocarcinoma cell lines QBC939, RBE and TFK-1. Flow cytometry was employed to assess the effect of curcumin on cell apoptosis in cholangiocarcinoma cell lines. A nude mouse model of orthotopic transplantation of cholangiocarcinoma was developed to investigate the effect of curcumin on weight gain and survival state of mice.

RESULTS: Curcumin inhibited the proliferation of QBC939, RBE and TFK-1 cells (P < 0.05) in a dose- and time-dependent manner. Curcumin significantly induced apoptosis of cholangiocinoma cells. When curcumin concentrations were 0, 0.1, 1, 5 and 10 μmol/L, the corresponding apoptosis rates were 8.41% ± 1.22%, 21.49% ± 2.58%, 48.53% ± 2.41%, 69.75% ± 1.46% and 87.59% ± 3.25%, respectively (P < 0.05). In vivo experimental results show that curcumin significantly prolonged the survival time of tumor-bearing mice (P < 0.05) and significantly improved their survival state (P < 0.05).

CONCLUSION: Curcumin inhibits cell proliferation and induces apoptosis in cholangiocarcinoma cell lines in vitro, and prolongs the survival time of cholangiocarcinoma bearing mice and improve their survival status in vivo.