Curcumin effectively inhibits oncogenic NF-κB signaling and restrains stemness features in liver cancer

Curcumin Inhibits the PERK-eIF2α-CHOP Pathway through Promoting SIRT1 Expression in Oxidative Stress-induced Rat Chondrocytes and Ameliorates Osteoarthritis Progression in a Rat Model

Oxidative stress plays a crucial role in the occurrence and development of osteoarthritis (OA) through the activation of endoplasmic reticulum (ER) stress. Curcumin is a polyphenolic compound with significant antioxidant and anti-inflammatory activity among various diseases. To elucidate the role of curcumin in oxidative stress-induced chondrocyte apoptosis, this study investigated the effect of curcumin on ER stress-related apoptosis and its potential mechanism in oxidative stress-induced rat chondrocytes. The results of flow cytometry and terminal deoxynucleotidyl transferase-mediated dUTP nick-end labeling (TUNEL) staining showed that curcumin can significantly attenuate ER stress-associated apoptosis. Curcumin inhibited the expression of cleaved caspase3, cleaved poly (ADP-ribose) polymerase (PARP), C/EBP homologous protein (CHOP), and glucose-regulated protein78 (GRP78) and upregulated the chondroprotective protein Bcl2 in TBHP-treated chondrocytes. In addition, curcumin promoted the expression of silent information regulator factor 2-related enzyme 1 (SIRT1) and suppressed the expression of activating transcription factor 4 (ATF4), the ratio of p-PERK/PERK, p-eIF2α/eIF2α. Our anterior cruciate ligament transection (ACLT) rat OA model research demonstrated that curcumin (50 mg/kg and 150 mg/kg) ameliorated the degeneration of articular cartilage and inhibited chondrocyte apoptosis in ACLT rats in a dose-dependent manner. By applying immunohistochemical analysis, we found that curcumin enhanced the expression of SIRT1 and inhibited the expression of CHOP and cleaved caspase3 in ACLT rats. Taken together, our present findings firstly indicate that curcumin could inhibit the PERK-eIF2α-CHOP axis of the ER stress response through the activation of SIRT1 in tert-Butyl hydroperoxide- (TBHP-) treated rat chondrocytes and ameliorated osteoarthritis development in vivo.

Nalbuphine suppresses breast cancer stem-like properties and epithelial-mesenchymal transition via the AKT-NFκB signaling pathway

BACKGROUND

Cancer pain is a debilitating disorder of human breast cancer and a primary determinant of the poor quality of life, and relieving pain is fundamental strategy in the cancer treatment. However, opioid analgesics, like morphine and fentanyl, which are widely used in cancer pain treatment have been reported to enhance stem-like traits and epithelial-mesenchymal transition (EMT) of breast cancer cells. As such, it is vital to make the best choice of analgesic for breast cancer management.

METHODS

MTT assays and colony formation assays were performed to examine tumor cell proliferation upon nalbuphine treatment. RT-PCR, western blot, flow cytometry, sphere formation, immunohistochemistry, transwell assays, wound healing assays and mouse xenograft were used to assess the biological effects of nalbuphine treatment.

RESULTS

Nalbuphine inhibited breast cancer cell growth and tumorigenesis, with little effect on noncancerous breast cell lines. Nalbuphine suppressed cancer stem-like traits and EMT in both breast cancer cells and mouse xenograft tumor tissues. Additionally, activation of AKT reversed the nalbuphine-induced inhibition of cancer stem-like properties, tumorigenesis and EMT.

CONCLUSIONS

Our results demonstrate a new role of nalbuphine in inhibiting cancer stem-like properties and EMT in addition to relieving pain, which suggests that nalbuphine may be effective in breast cancer treatment.

ROS-Mediated Cancer Cell Killing through Dietary Phytochemicals

Reactive oxygen species (ROS) promote carcinogenesis by inducing genetic mutations, activating oncogenes, and raising oxidative stress, which all influence cell proliferation, survival, and apoptosis. Cancer cells display redox imbalance due to increased ROS level compared to normal cells. This unique feature in cancer cells may, therefore, be exploited for targeted therapy. Over the past few decades, natural compounds have attracted attention as potential cancer therapies because of their ability to maintain cellular redox homeostasis with minimal toxicity. Preclinical studies show that bioactive dietary polyphenols exert antitumor effects by inducing ROS-mediated cytotoxicity in cancer cells. These bioactive compounds also regulate cell proliferation, survival, and apoptotic and antiapoptotic signalling pathways. In this review, we discuss (i) how ROS is generated and (ii) regulated and (iii) the cell signalling pathways affected by ROS. We also discuss (iv) the various dietary phytochemicals that have been implicated to have cancer therapeutic effects through their ROS-related functions.

Developments in the anticancer activity of structurally modified curcumin: An up-to-date review

Curcumin is a pharmacologically active polyphenol derived from the popular spice element-Turmeric. The therapeutic activity of curcumin has been extensively investigated over the last few decades and reports suggest the role of curcumin in a large number of biological activities, particularly its prominent anticancer activity. Curcumin, being a pleiotropic molecule, is a regulator of multiple molecular targets which play crucial roles in various cell signaling pathways. It is known to suppress transformation, inhibit proliferation as well as induce apoptosis. However, despite all these benefits, the efficacy of curcumin remains limited due to its poor bioavailability, poor absorption within the systemic circulation and rapid elimination from the body. To overcome these limiting factors, researchers all around the world are working towards designing a synthetic and superior curcuminoid by making suitable structural modifications to the parent skeleton. These curcuminoids, mainly analogues and derivatives, will not only improve the physicochemical properties but also enhance the efficacy simultaneously. The present review will provide a comprehensive account of the analogues and derivatives of curcumin that have been reported since 2014 which have indicated a better anticancer activity than curcumin.

Curcumin and α/β-Adrenergic Antagonists Cotreatment Reverse Liver Cirrhosis in Hamsters: Participation of Nrf-2 and NF-κB

Liver cirrhosis is the result of an uncontrolled fibrogenetic process, due to the activation and subsequent differentiation into myofibroblasts of the hepatic stellate cells (HSC). It is known that HSC express adrenoreceptors (AR), and the use of AR antagonists protects experimental animals from cirrhosis. However, several studies suggest that the toxicity generated by metabolism of these antagonists would hinder its use in cirrhotic patients. In addition, liver fibrosis may be associated with a decrease of the antioxidant response of the nuclear factor erythroid 2-related factor 2 (Nrf-2) and the overregulation of the proinflammatory pathway of nuclear factor kappa B (NF-κB). Therefore, in the present work, the capacity of doxazosin (α1 antagonist), carvedilol (nonselective beta-adrenoceptor blocker with alpha 1-blocking properties), and curcumin (antioxidant and anti-inflammatory compound) to reverse liver cirrhosis and studying the possible modulation of Nrf-2 and NF-κB were evaluated. Hamsters received CCl4 for 20 weeks, and then treatments were immediately administered for 4 weeks more. The individual administration of doxazosin or carvedilol showed less ability to reverse cirrhosis in relation to concomitantly curcumin administration. However, the best effect was the combined effect of doxazosin, carvedilol, and curcumin, reversing liver fibrosis and decreasing the amount of collagen I (Sirius red stain) without affecting the morphology of hepatocytes (hematoxylin and eosin stain), showing normal hepatic function (glucose, albumin, AST, ALT, total bilirubin, and total proteins). In addition, carvedilol treatment and the combination of doxazosin with curcumin increased Nrf-2/NF-κB mRNA ratio and its protein expression in the inflammatory cells in the livers, possibly as another mechanism of hepatoprotection. Therefore, these results suggest for the first time that α/β adrenergic blockers with curcumin completely reverse hepatic damage, possibly as a result of adrenergic antagonism on HSC and conceivably by the increase of Nrf-2/NF-κB mRNA ratio.

Controlled-release curcumin attenuates progression of tendon ectopic calcification by regulating the differentiation of tendon stem/progenitor cells

Tendon calcification is a common but intractable problem leading to pain and activity limitation when injury or tendinopathy progresses into the late stage. This is because tendon stem/progenitor cells (TSPCs) can undergo aberrant osteogenic differentiation under inflammatory conditions. This study aims to investigate the effect of curcumin, a natural anti-inflammatory agent, on regulating the differentiation of TSPCs in tendon calcification. With inflammatory stimulation, TSPCs showed higher alkaline phosphatase activity and more frequent formation of mineralized nodules which were verified in the culture system; however, curcumin significantly alleviated these pathological changes. In in vivo function analysis, chitosan microsphere-encapsulated curcumin was delivered to injured sites of rat tendon ectopic calcification model. The inflammation in the tendon tissues of the curcumin group was significantly relieved. Controlled-release curcumin partially rescued tendon calcification and enhanced tendon regeneration in animal model. This study demonstrates that controlled-release curcumin can manipulate the fate decision of TSPCs, and that it promotes the tenogenesis and inhibits the osteogenesis of TSPCs in a pathological microenvironment, which provides a possible new therapeutic strategy for tendon disease.

Determination and pharmacokinetic study of isothiouronium-modified pyrimidine-substituted curcumin analog (1G), a novel antitumor agent, in rat plasma by liquid chromatography-tandem mass spectrometry

1G, a novel derivative of curcumin, exhibits promising anticancer activities in various cancer cell lines. To support its further pharmacological studies, a liquid chromatography-tandem mass spectrometry method was developed and validated in accordance with FDA's Guidance. After extraction by protein precipitation, analytes were separated by a 4.5 min gradient elution (water/0.1% formic acid and methanol) on a reverse-phase C₁₈ column at 40 °C. The multiple reaction monitoring mode was used for quantification on a triple quadrupole mass spectrometer with positive ionization. The assay was linear over the concentration range of 5-1000 ng/mL with a correlation coefficient (r) greater than 0.99. Values of intra- and inter-day precision and accuracy were satisfactory, i.e. <10.1% for precision and within ± 14.5% for accuracy. No obvious matrix effect was observed. Recovery of the analyte was higher than 95.3%. 1G was stable during the whole analytic process. The validated method was successfully applied to the pharmacokinetic study of 1G after intravenous and intraperitoneal administration in rats. Favorable pharmacokinetic profiles were demonstrated, including good abdominal absorption (F = 62.58%), moderate clearance and high extravascular distribution. Results indicated that as a novel antitumor agent, 1G exhibited acceptable pharmacokinetic properties for further in vivo pharmacologic evaluation.

Curcumin Provides Hepatoprotection against Amoebic Liver Abscess Induced by Entamoeba histolytica in Hamster: Involvement of Nrf2/HO-1 and NF-κB/IL-1β Signaling Pathways

Amoebic liver abscess (ALA) is the most common extraintestinal amoebiasis caused by Entamoeba histolytica (E. histolytica). However, despite current knowledge and scientific advances about this infection, there are no effective treatments to prevent it. Herein, the antiamoebic capacity of curcumin in a hamster model was evaluated. Curcumin (150 mg/kg, p.o., daily during 10 days before infection) considerably prevents liver damage induced at 12 and 48 h post-intrahepatic inoculation of trophozoites and decreases ALT, ALP, and γ-GTP activities, and macroscopic and microscopic observations were consistent with these results. On the other hand, after one week of intraportal inoculation, liver damage was prevented by curcumin (150 mg/kg, p.o., daily, 20 days before amoebic inoculation and during the week of infection); liver/body weight ratios and tissue and histological stains showed normal appearance; in addition, the increases in ALT, ALP, and γ-GTP activities were prevented; the depletion of glycogen content induced by the amoebic damage was partially but significantly prevented, while NF-κB activity was inhibited and the expression of IL-1β was reduced; Nrf2 production showed a tendency to increase it, and HO-1 protein was overexpressed. These results suggest for the first time that curcumin can be a compound with antiamoebic effect in the liver, suggesting that its daily use could help greatly decrease the incidence of this type of infection.

Curcumin: New Insights into an Ancient Ingredient against Cancer

Cancer patients frequently use complementary medicine. Curcumin (CUR) and its derivates (from the extract of Curcuma longa L.) represent some of the most frequently used ones, having a long history in traditional Asian medicine. CUR was demonstrated, both in vitro and in vivo, to have significant anti-inflammatory effects, thus potentially counteracting cancer-promoting inflammation, which is a hallmark of cancer. CUR modulate a plethora of signaling pathways in cancer cells, comprising the NF-κB (nuclear factor k-light-chain-enhancer of activated B cells), the JAK/STAT (Janus-Kinase/Signal Transducers and Activators of Transcription), and the TGF-β (transforming growth factor-β) pathways. Furthermore, CUR confers properties of electron receptors, which destabilize radical oxygen species (ROS), explaining its antioxidant and anti-apopototic effects. Although CUR has a low bioavailability, its role in advanced cancer treatment and supportive care was addressed in numerous clinical trials. After promising results in phase I–II trials, multiple phase III trials in different indications are currently under way to test for direct anti-cancer effects. In addition, CUR exerts beneficial effects on cancer treatment-related neurotoxcity, cardiotoxicity, nephrotoxicity, hemato-toxicity, and others. More efficient galenic formulations are tested to optimze CUR’s usability in cancer treatment. This review should provide a comprehensive overview of basic science, and pre-clinical and clinical data on CUR in the field of oncology.

Co-regulatory Network of Oncosuppressor miRNAs and Transcription Factors for Pathology of Human Hepatic Cancer Stem Cells (HCSC)

Hepatic cancer stem cells (HCSCs) are considered as main players for the hepatocellular carcinoma (HCC) initiation, metastasis, drug resistance and recurrence. There is a growing evidence supporting the down-regulated miRNAs in HCSCs as key suppressors for the stemness traits, but still more details are vague about how these miRNAs modulate the HCC development. To uncover some of these miRNA regulatory aspects in HCSC, we compiled 15 down-regulated miRNA and their validated and predicted up-regulated targets in HCSC. The targets were enriched for several cancer cell stemness hallmarks and CSC pre-metastatic niche, which support these miRNAs role in suppression of HCSCs neoplastic transformation. Further, we constructed miRNA-Transcription factor (TF) regulatory networks, which provided new insights on the role of the proposed miRNA-TF co-regulation in the cancer stemness axis and its cross talk with the surrounding microenvironment. Our analysis revealed HCSC important hubs as candidate regulators for targeting hepatic cancer stemness such as, miR-148a, miR-214, E2F family, MYC and SLC7A5. Finally, we proposed a possible model for miRNA and TF co-regulation of HCSC signaling pathways. Our study identified an HCSC signature and set bridges between the reported results to give guide for future validation of HCC therapeutic strategies avoiding drug resistance.

The molecular mechanisms of curcumin’s inhibitory effects on cancer stem cells

Curcumin is a dietary polyphenol and a bioactive phytochemical that possesses anti‐inflammatory, antioxidant, anticancer, and chemopreventive properties, which make it capable of affecting multiple sites along the stem cell pathways to induce apoptosis in these cells. Curcumin’s function is through suppression of cytokine release, especially the secretion of interleukins. Some of the predominant activities of stem cells include regeneration of identical cells and the ability to maintain the proliferation and multipotentiality. However, these cells could be stimulated to differentiate into specific cell types, leading to the development of tumors. Cancer stem cells (CSC) are capable of sustaining tumor formation and differentiation, and are normally characterized by self‐renewal mechanisms. Furthermore, these cells might be responsible for tumor relapse and resistance to therapy. Several studies have focused on the mechanisms of curcumin action in manipulating transcription factors, signaling pathways, CSC markers, microRNAs related to CSCs functions and apoptosis induction in various human cancer cells. In the present review, we aimed to summarize the reported molecular mechanisms of curcumin’s effects on CSCs.

Growth and Proliferation of Renal Cell Carcinoma Cells Is Blocked by Low Curcumin Concentrations Combined with Visible Light Irradiation

The anti-cancer properties of curcumin in vitro have been documented. However, its clinical use is limited due to rapid metabolization. Since irradiation of curcumin has been found to increase its anti-cancer effect on several tumor types, this investigation was designed to determine whether irradiation with visible light may enhance the anti-tumor effects of low-dosed curcumin on renal cell carcinoma (RCC) cell growth and proliferation. A498, Caki1, and KTCTL-26 cells were incubated with curcumin (0.1–0.4 µg/mL) and irradiated with 1.65 J/cm² visible light for 5 min. Controls were exposed to curcumin or light alone or remained untreated. Curcumin plus light, but not curcumin or light exposure alone altered growth, proliferation, and apoptosis of all three RCC tumor cell lines. Cells were arrested in the G0/G1 phase of the cell cycle. Phosphorylated (p) CDK1 and pCDK2, along with their counter-receptors Cyclin B and A decreased, whereas p27 increased. Akt-mTOR-signaling was suppressed, the pro-apoptotic protein Bcl-2 became elevated, and the anti-apoptotic protein Bax diminished. H3 acetylation was elevated when cells were treated with curcumin plus light, pointing to an epigenetic mechanism. The present findings substantiate the potential of combining low curcumin concentrations and light as a new therapeutic concept to increase the efficacy of curcumin in RCC.

Role of Natural Products in Modulating Histone Deacetylases in Cancer

Histone deacetylases (HDACs) are enzymes that can control transcription by modifying chromatin conformation, molecular interactions between the DNA and the proteins as well as the histone tail, through the catalysis of the acetyl functional sites removal of proteins from the lysine residues. Also, HDACs have been implicated in the post transcriptional process through the regulation of the proteins acetylation, and it has been found that HDAC inhibitors (HDACi) constitute a promising class of pharmacological drugs to treat various chronic diseases, including cancer. Indeed, it has been demonstrated that in several cancers, elevated HDAC enzyme activities may be associated with aberrant proliferation, survival and metastasis. Hence, the discovery and development of novel HDACi from natural products, which are known to affect the activation of various oncogenic molecules, has attracted significant attention over the last decade. This review will briefly emphasize the potential of natural products in modifying HDAC activity and thereby attenuating initiation, progression and promotion of tumors.

Liver-targeted liposomes for codelivery of curcumin and combretastatin A4 phosphate: preparation, characterization, and antitumor effects

Background

Recent efforts have been focused on combining two or more therapeutic approaches with different mechanisms to enhance antitumor therapy. Moreover, nanosize drug-delivery systems for codelivering two drugs with proapoptotic and antiangiogenic activities have exhibited great potential in efficient treatment of cancers.

Methods

Glycyrrhetinic acid (GA)–modified liposomes (GA LPs) for liver-targeted codelivery of curcumin (Cur) and combretastatin A4 phosphate (CA4P) were prepared and characterized. In vitro cellular uptake, cytotoxicity, cell migration, in vivo biodistribution, antitumor activity, and histopathological studies were performed.

Results

Compared with unmodified LPs (Cur-CA4P LPs), Cur-CA4P/GA LPs were taken up effectively by human hepatocellular carcinoma cells (BEL-7402) and showed higher cytotoxicity than free drugs. In vivo real-time near-infrared fluorescence–imaging results indicated that GA-targeted LPs increased accumulation in the tumor region. Moreover, Cur-CA4P/GA LPs showed stronger inhibition of tumor proliferation than Cur, Cur + CA4P, and Cur-CA4P LPs in vivo antitumor studies, which was also verified by H&E staining.

Conclusion

GA-modified LPs can serve as a promising nanocarrier for liver-targeted co-delivery of antitumor drugs against hepatocellular carcinoma.

Insulin receptor isoform A favors tumor progression in human hepatocellular carcinoma by increasing stem/progenitor cell features

Hepatocellular carcinoma (HCC) is one of the most common and deadly neoplasms. Insulin receptor (IR) exists in two isoforms, IR-A and IR-B, the latter being predominantly expressed in normal adult hepatocytes while IR-A is overexpressed in HCC to the detriment of IR-B. This study evaluated the biological functions associated with IR-A overexpression in HCC in relation to expression of its ligand IGF-II. The value of INSRA:INSRB ratio which was increased in _˜70% of 85 HCC was associated with stem/progenitor cell features such as cytokeratin-19 and α-fetoprotein and correlated with shorter patient survival. IGF2 mRNA upregulation was observed in 9.4% of HCC and was not associated with higher INSRA:INSRB ratios. Ectopic overexpression of IR-A in two HCC cell lines presenting a strong autocrine IGF-II secretion loop or not stimulated cell migration and invasion. In cells cultured as spheroids, IR-A overexpression promoted gene programs related to stemness, inflammation and cell movement. IR-A also increased cell line tumorigenicity in vivo after injection to immunosuppressed mice and the sphere-forming cells made a significant contribution to this effect. Altogether, these results demonstrate that IR-A is a novel player in HCC progression.

Hepatitis B Virus Induces Autophagy to Promote its Replication by the Axis of miR-192-3p-XIAP Through NF kappa B Signaling

Hepatitis B virus (HBV) is a major risk factor for the development and progression of hepatocellular carcinoma. It has been reported that viral infection can interfere with cellular microRNA (miRNA) expression and participate in the pathogenesis of oncogenicity. Here, we report that decreasing levels of the expression of the miRNA miR-192-3p is associated with rising levels of HBV DNA in the serum of HBV patients. We revealed that HBV infection repressed the expression of miR-192-3p through hepatitis B x protein interaction with c-myc. We further showed that miR-192-3p was repressed by HBV transfection in vitro and in a mouse model, leading to cellular autophagy. Using an miRNA target prediction database miRBase, we identified X-linked inhibitor of apoptosis protein (XIAP) as a target gene of miR-192-3p and demonstrated that miR-192-3p directly targeted the XIAP 3'-untranslated region of XIAP messenger RNA. Importantly, we discovered that HBV promoted autophagy through miR-192-3p-XIAP axis and that this process was important for HBV replication in vitro and in vivo. We demonstrated that miR-192-3p functioned through the nuclear factor kappa B signaling pathway to inhibit autophagy, thereby reducing HBV replication. Conclusions: Our findings indicate that miR-192-3p is a regulator of HBV infection and may play a potential role in hepatocellular carcinoma. It may also serve as a biomarker or therapeutic target for HBV patients.

Immunoregulatory, proliferative and anti-oxidant effects of nanocurcuminoids on adipose-derived mesenchymal stem cells

Curcuminoids are dietary complexes extracted from the seeds of Curcuma longa L. that contain curcumin, bisdemethoxycurcumin and desmethoxycurcumin. Curcuminoids are popular for their pleiotropic therapeutic functions, such as their anti-inflammatory and anti-oxidant effects. Nonetheless, their clinical use is associated with poor systemic bioavailability and insolubility. The nano-formulation of curcuminoids eliminates these shortcomings. In the present study, we explored immunoregulatory, proliferative and anti-oxidant effects of nanocurcuminoids on adipose-derived mesenchymal stem cells (AT-MSCs). Flow cytometry analysis and MTT assay were employed to explore the effects of nanocurcuminoids on the apoptosis and proliferation of adipose-derived MSCs (AT-MSCs). The anti-oxidant effect of nanocurcuminoids on AT-MSCs also was examined. The immune regulatory effect of nanocurcuminoids was evaluated by the flow cytometric measurement of the T regulatory (Treg) population. The expression of inflammatory and anti-inflammatory cytokines was quantified using real-time PCR. Our findings demonstrate that low concentrations of nanocurcuminoids are beneficial for MSC proliferation, protection of MSCs from apoptosis, reducing inflammatory cytokines and SOD activity. A high concentration of nanocurcuminoids increases the population of Tregs and elevates the expression of TGFβ and FOXP3 genes. The beneficial effects of nanocurcuminoids on AT-MSCs were mainly observed at low doses of nanocurcuminoids.

The therapeutic potential of curcumin: A review of clinical trials

Curcuma longa L., its derived extracts and even its major compound curcumin has a long history of use and doubtless effectiveness, reported through increasingly detailed in vitro, ex vivo, in vivo and even clinical trials. Regarding its biological effects, multiple health-promoting, disease-preventing and even treatment attributes has been remarkably highlighted. Clinical trials, although have increased in a progressive manner, significant disproportionalities have been stated in terms of biological effects assessment. In this sense, the present report aims to provide an extensive overview to curcumin therapeutic effects in human subjects. For that, clinical trials assessing the curcumin effect on inflammation, skin, eye, central nervous system, respiratory, cardiovascular, gastrointestinal, urogenital and metabolic disorders are here presented and discussed. A special emphasis was also given to curcumin activity on intoxications and multiple malignant diseases.

Curcumin prevented human autocrine growth hormone (GH) signaling mediated NF-κB activation and miR-183-96-182 cluster stimulated epithelial mesenchymal transition in T47D breast cancer cells

Autocrine growth hormone (GH) signaling is a promoting factor for breast cancer via triggering abnormal cell growth, proliferation, and metastasis, drug resistance. Curcumin (diferuloylmethane), a polyphenol derived from turmeric (Curcuma longa), has anti-proliferative, anti-carcinogenic, anti-hormonal effect via acting on PI3K/Akt, NF-κB and JAK/STAT signaling. Forced GH expression induced epithelial mesenchymal transition (EMT) through stimulation of miR-182-96-183 cluster expression in breast cancer cells. This study aimed to investigate the role of NF-κB signaling and miR-182-96-183 cluster expression profile on autocrine GH-mediated curcumin resistance, which was prevented by time-dependent curcumin treatment in T47D breast cancer cells. Dose- and time-dependent effect of curcumin on T47D wt and GH+ breast cancer cells were evaluated by MTT cell viability and trypan blue assay. Apoptotic effect of curcumin was determined by PI and Annexin V/PI FACS flow analysis. Immunoblotting performed to investigate the effect of curcumin on PI3K/Akt/MAPK, NF-κB signaling. miR182-96-183 cluster expression profile was observed by qRT-PCR. Overexpression of GH triggered resistant profile against curcumin (20 µM) treatment for 24 h, but this resistance was accomplished following 48 h curcumin exposure. Concomitantly, forced GH induced invasion and metastasis through EMT and NF-κB activation were prevented by long-term curcumin exposure in T47D cells. Moreover, 48 h curcumin treatment prevented the autocrine GH-mediated miR-182-96-183 cluster expression stimulation in T47D cells. In consequence, curcumin treatment for 48 h, prevented autocrine GH-triggered invasion-metastasis, EMT activation through inhibiting NF-κB signaling and miR-182-96-183 cluster expression and induced apoptotic cell death by modulating Bcl-2 family members in T47D breast cancer cells.

Curcumin-induced promoter hypermethylation of the mammalian target of rapamycin gene in multiple myeloma cells

Curcumin, a polyphenol derived from the rhizome of Curcuma, is a potential tumor inhibitor through affecting signaling pathways and epigenetic regulation. The mammalian target of rapamycin (mTOR) gene serves a crucial role in the carcinogenesis of multiple myeloma. The curcumin-induced epigenetic regulation of mTOR, including promoter DNA methylation in multiple myeloma, has not yet been fully elucidated. In the present study, antitumor effects of curcumin were investigated in RPMI-8226 and NCI-H929 cells using an MTT assay and flow cytometry. The expression of mTOR and DNA methyltransferase proteins were determined by western blot analysis, and the methylation status of the mTOR promoter were detected by sequencing following bisulfite conversion. The results of the present study revealed that the half-maximal inhibitory concentration of curcumin was 10 µM in myeloma cells. Following curcumin treatment, the mRNA and protein expression levels of mTOR were decreased by 43.31 and 39.34% in NCI-H929 cells, respectively. The promoter of mTOR, located in chromosome 1 (chromosome position, 11262153-11263153), contains a CpG island that was hypermethylated in myeloma cells following curcumin treatment. The expression levels of DNA methyltransferase (DNMT)3a and DNMT3b were increased in curcumin-treated cells. Collectively, these results indicate that curcumin serves a role in the epigenetic regulation of mTOR expression, and that mTOR downregulation is due to promoter hypermethylation, which may be associated with DNMT3a and DNMT3b upregulation. The results of the present study contribute towards improving the understanding of curcumin treatment in multiple myeloma and provide novel insights into the molecular mechanisms underlying the epigenetic regulation of mTOR.

The emerging spectrum of early life exposure-related inflammation and epigenetic therapy

Early life exposure to a variety of insults during sensitive windows of development can reprogram normal physiological responses and alter disease susceptibility later in life. During this process, Inflammation triggered by a variety of adverse exposures plays an important role in the initiation and development of many types of diseases including tumorigenesis. This review article summaries the current knowledge about the role and mechanism of inflammation in development of diseases. In addition, epigenome alteration related to inflammation and treatment options using epigenetic modifiers are highlighted and discussed.

Pluronic micelles encapsulated curcumin manifests apoptotic cell death and inhibits pro-inflammatory cytokines in human breast adenocarcinoma cells

BACKGROUND

Curcumin is a natural derivative, which exhibits broad spectrum biological activities including anti-oxidant, anti-inflammatory, and anti-cancer. Since ancient times, it has been used for the treatment of various diseases. Many reports highlighted its potential as a chemopreventive and chemotherapeutic agent. Despite its imperative properties, the pharmacological application had been limited due to low solubility in the aqueous medium, limited tissue absorption, and rapid degradation at physiological pH.

AIMS

Cytotoxicity of drugs and their undesirable side effects are major obstacles in the regimens of cancer therapy. Therefore, natural plant derivatives-based anti-cancer drug delivery systems are getting more attention as they are less toxic, safer, and effective. In the present study, Pluronic block copolymer encapsulated curcumin was developed as an improved curcumin delivery system with the aim to improve its efficacy and biological response against cancer cells.

METHODS AND RESULTS

Pluronic micelles encapsulated curcumin was synthesized, and its characterization was done by particle size analysis, Fourier transform infrared spectroscopy, small-angle neutron scattering analysis, PXRD, and differential scanning calorimetry. Further, its biological activities were corroborated in cancer cells. Results indicate that Pluronic micelles encapsulated curcumin exemplify solubility and stability of curcumin in the aqueous medium. Biophysical characterization indicated that Pluronic F127 forms nanoparticle, and its micellar core radius was increased after incorporation of curcumin. Furthermore, biological studies show that Pluronic micelles encapsulated curcumin inhibits cell proliferation, improves cellular uptake of curcumin, arrests the cell cycle in G0/G1 phase, and inhibits the activation of NF-kB and release of pro-inflammatory cytokines to manifest apoptotic cell death rather than necrotic. This formulation was non-toxic to normal cells.

CONCLUSION

This study suggests that Pluronic micelles encapsulated curcumin is stable that can effectively inhibit cell proliferation and release of pro-inflammatory cytokines in cancer cells as compared with the free curcumin. This approach could be applied to improve the therapeutic index of anti-cancer agents.

Curcumin sensitized the antitumour effects of irradiation in promoting apoptosis of oesophageal squamous-cell carcinoma through NF-κB signalling pathway

Objectives

To investigate the potential synergistic effect of curcumin with irradiation (IR) in oesophageal squamous-cell carcinoma (ESCC) and elucidate the underlying molecular mechanisms.

Methods

The ESCC cell lines were established from clinical samples. Cell apoptosis post-treatment was stained by Annexin V/PI staining and analysed by flow cytometry. Cells survived IR was evaluated with clonogenic assay. Xenograft tumour model was established by subcutaneous inoculation, and tumour progression was monitored. The NF-κB pathway was characterized by immunoblotting.

Key findings

Curcumin enhanced the pro-apoptotic effect of IR in ESCC cells. Pretreatment with curcumin significantly sensitized ESCC cells to IR in a dose-dependent manner. Coadministration with curcumin remarkably extended the median survival time of ESCC xenograft mice while exposed to IR therapy. The xenograft tumour progression was significantly suppressed as well. Mechanistically, curcumin treatment was demonstrated to efficiently inhibited NF-κB signalling.

Conclusions

We have well-recapitulated the pathological properties and therapeutic response of ESCC with established cell lines derived from clinical samples. We further demonstrated the significantly synergistic effect of curcumin on IR-elicited cell apoptosis in ESCC both in vitro and in vivo. Our data suggested the potential therapeutic values of curcumin for future clinical investigations.

Transcriptional Activation of Human GD3 Synthase (hST8Sia I) Gene in Curcumin-Induced Autophagy in A549 Human Lung Carcinoma Cells

Curcumin, a natural polyphenolic compound isolated from the plant Curcuma longa, is known to induce autophagy in various cancer cells, including lung cancer. In the present study, we also confirmed by LC3 immunofluorescence and immunoblotting analyses that curcumin triggers autophagy in the human lung adenocarcinoma A549 cell line. In parallel with autophagy induction, the gene expression of human GD3 synthase (hST8Sia I) responsible for ganglioside GD3 synthesis was markedly elevated in response to curcumin in the A549 cells. To investigate the transcriptional activation of hST8Sia I associated with the autophagy formation in curcumin-treated A549 cells, functional characterization of the 5'-flanking region of the hST8Sia I gene was carried out using the luciferase reporter assay system. Deletion analysis demonstrated that the -1146 to -646 region, which includes the putative c-Ets-1, CREB, AP-1, and NF-κB binding sites, functions as the curcumin-responsive promoter of hST8Sia I in A549 cells. The site-directed mutagenesis and chromatin immunoprecipitation assay demonstrated that the NF-κB binding site at -731 to -722 was indispensable for the curcumin-induced hST8Sia I gene expression in A549 cells. Moreover, the transcriptional activation of hST8Sia I by the curcumin A549 cells was strongly inhibited by compound C, an inhibitor of AMP-activated protein kinase (AMPK). These results suggest that curcumin controls hST8Sia I gene expression via AMPK signal pathway in A549 cells.

Curcumin prevents the bile reflux-induced NF-κB-related mRNA oncogenic phenotype, in human hypopharyngeal cells

The presence of bile is not an uncommon finding in acidic oesophageal and extra‐oesophageal refluxate, possibly affecting the hypopharyngeal mucosa and leading to neoplastic events. We recently demonstrated that acidic bile (pH ≤ 4.0) can induce NF‐κB activation and oncogenic mRNA phenotype in normal hypopharyngeal cells and generate premalignant changes in treated hypopharyngeal mucosa. We hypothesize that curcumin, a dietary inhibitor of NF‐κB, may effectively inhibit the acidic bile‐induced cancer‐related mRNA phenotype, in treated human hypopharyngeal primary cells (HHPC), supporting its potential preventive use in vivo. Luciferase assay, immunofluorescence, Western blot, qPCR and PCR microarray analysis were used to explore the effect of curcumin in HHPC exposed to bile (400 μmol/L) at acidic and neutral pH. Curcumin successfully inhibited the acidic bile‐induced NF‐κB signalling pathway (25% of analysed genes), and overexpression of NF‐κB transcriptional factors, c‐REL, RELA(p65), anti‐apoptotic bcl‐2, oncogenic TNF‐α, EGFR, STAT3, WNT5A, ΔNp63 and cancer‐related IL‐6. Curcumin effectively reduced bile‐induced bcl‐2 overexpression at both acidic and neutral pH. Our novel findings suggest that, similar to pharmacologic NF‐κB inhibitor, BAY 11‐7082, curcumin can suppress acidic bile‐induced oncogenic mRNA phenotype in hypopharyngeal cells, encouraging its future in vivo pre‐clinical and clinical explorations in prevention of bile reflux‐related pre‐neoplastic events mediated by NF‐κB.

Effects of resveratrol, curcumin, berberine and other nutraceuticals on aging, cancer development, cancer stem cells and microRNAs

Natural products or nutraceuticals have been shown to elicit anti-aging, anti-cancer and other health-enhancing effects. A key target of the effects of natural products may be the regulation of microRNA (miR) expression which results in cell death or prevents aging, diabetes, cardiovascular and other diseases. This review will focus on a few natural products, especially on resveratrol (RES), curcumin (CUR) and berberine (BBR). RES is obtained from the skins of grapes and other fruits and berries. RES may extend human lifespan by activating the sirtuins and SIRT1 molecules. CUR is isolated from the root of turmeric (Curcuma longa). CUR is currently used in the treatment of many disorders, especially in those involving an inflammatory process. CUR and modified derivatives have been shown to have potent anti-cancer effects, especially on cancer stem cells (CSC). BBR is also isolated from various plants (e.g., Coptis chinensis) and has been used for centuries in traditional medicine to treat diseases such as adult- onset diabetes. Understanding the benefits of these and other nutraceuticals may result in approaches to improve human health.

Can Curcumin Counteract Cognitive Decline? Clinical Trial Evidence and Rationale for Combining ω-3 Fatty Acids with Curcumin

The rate of cognitive decline in the elderly is highly variable. One potential factor contributing to accelerated cognitive decline is chronic systemic inflammation, because it has been linked to cognitive impairment and increased dementia risk. Certain lifestyle factors, such as excess body weight and sedentary behavior, can exacerbate a proinflammatory state in older adults, resulting in chronic low-grade inflammation. Supplementing the diet with curcumin, an anti-inflammatory polyphenolic compound from the curry spice turmeric, is a potential approach to prevent accelerated cognitive decline by counteracting chronic inflammatory processes. Although the anti-inflammatory effects of curcumin are well established, the potential cognitive benefits of curcumin were discovered more recently. Several animal and epidemiologic studies on the effect of curcumin supplementation on cognition showed promising results; however, randomized controlled trials in humans are limited. In this review, we identified 5 randomized controlled trials, of which only 2 observed a beneficial effect of curcumin supplementation on cognition by improving working memory. By critically examining the methodologies of those studies, we identified some limitations, one of which is that none of the studies explored the possibility that anti-inflammatory mechanisms were mediating cognitive benefits (i.e., no study tested participants with low-grade inflammation or measured inflammatory biomarkers). Other factors influencing the likelihood of conclusive outcomes include choice of study population (cognitively unimpaired compared with impaired), study duration, curcumin dose and its bioavailability, and neurocognitive test battery. On the basis of these findings, we offer recommendations for future studies to examine the potential cognitive benefits of curcumin in humans, which include evaluating its effects on cerebral endothelial vasodilator function and boosting its cognitive effects by combining it with long-chain omega-3 (n-3) fatty acids.

Inhibition of hepatocellular carcinoma tumorigenesis by curcumin may be associated with CDKN1A and CTGF

This study aimed to explore crucial genes, transcription factors (TFs), and microRNAs (miRNAs) associated with the effects of curcumin against hepatocellular carcinoma (HCC). We downloaded data (GSE59713) from Gene Expression Omnibus to analyze differentially expressed genes (DEGs) between curcumin-treated and untreated HCC cell lines. Then, we identified the disease ontology (DO) and functional enrichment analysis of these DEGs and analyzed their protein-protein interactions (PPIs). Additionally, we constructed TF-target gene and miRNA-target gene regulatory networks and explored the potential functions of these DEGs. Finally, we detected the expression of CDKN1A, CTGF, LEF1 TF and MIR-19A regulated by curcumin in PLC/PRF/5 cells using RT-PCR. In total, 345 upregulated and 212 downregulated genes were identified. The main enriched pathway of upregulated genes was the TNF signaling pathway. The downregulated genes were significantly enriched in TGF-beta signaling pathway. In addition, most DEGs were significantly enriched in DO terms such as liver cirrhosis, hepatitis, hepatitis C and cholestasis (eg., CTGF). In the constructed PPI network, CDKN1A and CTGF were the key proteins. Moreover, LEF1, CDKN1A, and miR-19A that regulated CTGF were highlighted in the regulatory networks. Furthermore, the expression of CDKN1A, CTGF, LEF1 TF and miR-19A regulated by curcumin in PLC/PRF/5 cells was consistent with the aforementioned bioinformatics analysis results. To conclude, curcumin might exert its protective effects against HCC tumorigenesis by downregulating LEF1 and downregulating CTGF regulated by MIR-19A and upregulating CDKN1A expression.

Nuclear IKKα mediates microRNA-7/-103/107/21 inductions to downregulate maspin expression in response to HBx overexpression

Maspin is a tumor suppressor that stimulates apoptosis and inhibits metastasis in various cancer types, including hepatocellular carcinoma (HCC). Our previous study has demonstrated that HBx induced microRNA-7, 103, 107, and 21 expressions to suppress maspin expression, leading to metastasis, chemoresistance, and poor prognosis in HCC patients. However, it remains unclear how HBx elicits these microRNA expressions. HBx has been known to induce aberrant activation and nuclear translocation of inhibitor-κB kinase-α (IKKα) to promote HCC progression. In this study, our data further revealed that nuclear IKKα expression was inversely correlated with maspin expression in HBV-associated patients. Nuclear IKKα but not IKKβ reduced maspin protein and mRNA expression, and inhibition of IKKα reverses HBx-mediated maspin downregulation and chemoresistance. In response to HBx overexpression, nuclear IKKα was further demonstrated to induce the gene expressions of microRNA-7, −103, −107, and −21 by directly targeting their promoters, thereby leading to maspin downregulation. These findings indicated nuclear IKKα as a critical regulator for HBx-mediated microRNA induction and maspin suppression, and suggest IKKα as a promising target to improve the therapeutic outcome of HCC patients.

Targeting oncogenic transcription factors by polyphenols: A novel approach for cancer therapy

Inflammation is one of the major causative factor of cancer and chronic inflammation is involved in all the major steps of cancer initiation, progression metastasis and drug resistance. The molecular mechanism of inflammation driven cancer is the complex interplay between oncogenic and tumor suppressive transcription factors which include FOXM1, NF-kB, STAT3, Wnt/β- Catenin, HIF-1α, NRF2, androgen and estrogen receptors. Several products derived from natural sources modulate the expression and activity of multiple transcription factors in various tumor models as evident from studies conducted in cell lines, pre-clinical models and clinical samples. Further combination of these natural products along with currently approved cancer therapies added an additional advantage and they considered as promising targets for prevention and treatment of inflammation and cancer. In this review we discuss the application of multi-targeting natural products by analyzing the literature and future directions for their plausible applications in drug discovery.

Curcumin inhibits gastric cancer-derived mesenchymal stem cells mediated angiogenesis by regulating NF-κB/VEGF signaling

Cancer-derived mesenchymal stem cells (MSCs) seem to play an important role in mediating tumor angiogenesis. Recently, curcumin has been shown to display multiple therapeutic properties, including anticancer activity. In the present study, we have tried to explore the role of curcumin in regulating gastric cancer cells-derived mesenchymal stem cells (GC-MSCs) mediated angiogenesis. Our results showed that curcumin attenuated the high expression levels of fibroblast proteins (α-SMA & Vimentin) in GC-MSCs. Its treatment also inhibited GC-MSCs induced human umbilical vein endothelial cells (HUVEC) tube formation, migration and colony formation. Furthermore, it was noticed that curcumin abrogated NF-κB signaling activity and VEGF production in GC-MSCs. Next, to establish the link between regulation of NF-κB/VEGF signaling by curcumin, and its influence on GC-MSC-derived angiogenesis, we pretreated GC-MSCs with either NF-κB inhibitor PDTC or a neutralizing antibody against VEGF (NA-VEGF), and then collected conditioned media (CM). The HUVEC cells were then cultured in this conditioned media to test their ability to form tubes, migrate and form colonies. Our results demonstrated that NF-κB/VEGF signaling is important for GC-MSCs induced tube formation, migration and colony formation in HUVEC cells. Moreover, we also observed that NF-κB/VEGF signaling regulated VEGF expression of gastric cancer cells both in vitro and in vivo. Overall, our study indicated that curcumin may serve as a novel therapeutic target for GC-MSCs derived angiogenesis, by inhibiting NF-κB/VEGF signaling.

Improving anti-melanoma effect of curcumin by biodegradable nanoparticles

Melanoma is known as the most common malignant cutaneous cancer. Curcumin, a natural component, has been shown to have various activities such as anti-oxidant, anti-septic, anti-inflammatory, anti-biotic, anti-amyloid and anti-thrombosis. However, there is a greatest obstacle in the administration of curcumin due to its hydrophobicity and low oral bioavailability. In this study, we formulated curcumin-loaded MPEG-PLA (Curcumin/MPEG-PLA) micelles aiming to improve its solubility in aqueous solution and investigated anti-tumor effect on melanoma in vitro and in vivo. The spherical curcumin/MPEG-PLA micelles were completely dispersed in normal saline and could release curcumin in a sustained manner in vitro. In addition, we demonstrated that curcumin/MPEG-PLA micelles had stronger cytotoxicity and induced a higher percentage of apoptosis in B16 and A375 cancer cells than free curcumin in vitro. The immunohistochemical study revealed that curcumin/MPEG-PLA micelles induced more melanoma cell apoptosis than free curcumin and inhibited neovascularization in tumor tissues. In conclusion, the curcumin/MPEG-PLA micelles have potential clinical application for melanoma.

Combination Therapies Targeting HDAC and IKK in Solid Tumors

The rationale for developing histone deacetylase (HDAC) inhibitors (HDACi) as anticancer agents was based on their ability to induce apoptosis and cell cycle arrest in cancer cells. However, while HDACi have been remarkably effective in the treatment of hematological malignancies, clinical studies with HDACi as single agents in solid cancers have been disappointing. Recent studies have shown that, in addition to inducing apoptosis in cancer cells, class I HDACi induce IκB kinase (IKK)-dependent expression of proinflammatory chemokines, such as interleukin-8 (IL8; CXCL8), resulting in the increased proliferation of tumor cells, and limiting the effectiveness of HDACi in solid tumors. Here, we discuss the mechanisms responsible for HDACi-induced CXCL8 expression, and opportunities for combination therapies targeting HDACs and IKK in solid tumors.

Inhibition of cancer antioxidant defense by natural compounds

All classic, non-surgical anticancer approaches like chemotherapy, radiotherapy or photodynamic therapy kill cancer cells by inducing severe oxidative stress. Even tough chemo- and radiotherapy are still a gold standard in cancer treatment, the identification of non-toxic compounds that enhance their selectivity, would allow for lowering their doses, reduce side effects and risk of second cancers. Many natural products have the ability to sensitize cancer cells to oxidative stress induced by chemo- and radiotherapy by limiting antioxidant capacity of cancer cells. Blocking antioxidant defense in tumors decreases their ability to balance oxidative insult and results in cell death. Though one should bear in mind that the same natural compound often exerts both anti-oxidant and pro-oxidant properties, depending on concentration used, cell type, exposure time and environmental conditions. Here we present a comprehensive overview of natural products that inhibit major antioxidant defense mechanisms in cancer cells and discuss their potential in clinical application.

Maintenance of stemness is associated with the interation of LRP6 and heparin-binding protein CCN2 autocrined by hepatocellular carcinoma

Background

The overall response rate of hepatocellular carcinoma (HCC) to chemotherapy is poor. In our previous study, oxaliplatin-resistant HCC is found to exhibit an enhanced stemness, and increased levels of CCN2 and LRP6, while the role of CCN2 and LRP6 in the prognosis of HCC patients, and the interaction regulation mechanism between CCN2 and LRP6 are still unclear.

Methods

The expression levels of CCN2 and LRP6 were detected in large cohorts of HCCs, and functional analyses of CCN2 and LRP6 were performed both in vitro and in vivo. The roles of cell surface heparin sulfate proteoglycans (HSPGs) in the mutual regulatory between CCN2 and LRP6 were verified in HCC, and the interventions of low molecular weight heparin sodium (LMWH) were explored.

Results

CCN2 and LRP6 were overexpressed in HCCs, and the CCN2 and LRP6 levels were positively associated with the malignant phenotypes and poor prognosis of HCCs. LRP6 could significantly upregulate the expression of CCN2. Meanwhile, CCN2 was able to enhance malignant phenotype of HCC cells in a dose-dependent manner through binding with LRP6; and knock-down of LRP6 expression, perturbation of HSPGs, co-incubation of CCN2 with LMWH could significantly block the adhesion of CCN2 to LRP6. LMWH enhanced the therapeutic effect of oxaliplatin on HCC with a high CCN2 expression.

Conclusions

 CCN2 plays a promoting role in HCC progression through activating LRP6 in a HSPGs-dependent manner. Heparin in combination with chemotherapy has a synergic effect and could be a treatment choice for HCCs with a high CCN2 expression. 

Electronic supplementary material

The online version of this article (doi:10.1186/s13046-017-0576-3) contains supplementary material, which is available to authorized users.

Cucurmin, anticancer, & antitumor perspectives: A comprehensive review

Cucurmin, a naturally yellow component isolated from turmeric, ability to prevent various life-style related disorders. The current review article mainly emphasizes on different anticancer perspectives of cucurmin, i.e., colon, cervical, uterine, ovarian, prostate head and neck, breast, pulmonary, stomach and gastric, pancreatic, bladder oral, oesophageal, and bone cancer. It holds a mixture of strong bioactive molecule known as cucurminoids that has ability to reduce cancer/tumor at initial, promotion and progression stages of tumor development. In particular, these compounds block several enzymes required for the growth of tumors and may therefore involve in tumor treatments. Moreover, it modulates an array of cellular progressions, i.e., nitric oxide synthetase activity, protein kinase C activity, epidermal growth factor (EGF) receptor intrinsic kinase activity, nuclear factor kappa (NF-kB) activity, inhibiting lipid peroxidation and production of reactive oxygen species. However, current manuscript summarizes most of the recent investigations of cucurmin but still further research should be conducted to explore the role of curcumin to mitigate various cancers.

Tg737 acts as a key driver of invasion and migration in liver cancer stem cells and correlates with poor prognosis in patients with hepatocellular carcinoma

We previously demonstrated that the Tg737 gene plays a critical role in the carcinogenesis of hepatocellular carcinoma (HCC). However, few systematic investigations have focused on the biological function of Tg737 in the invasion and migration of liver cancer stem cells (LCSCs) and on its clinical significance. In this study, Tg737 overexpression was achieved via gene transfection in MHCC97-H side population (SP) cells, which are considered a model for LCSCs in scientific studies. Tg737 overexpression significantly inhibited the invasion and migration of SP cells in an extracellular signal-regulated kinase1/2 (ERK1/2)/matrix metalloproteinase-2 (MMP-2)-dependent manner. Furthermore, Tg737 expression was frequently decreased in HCC tissues relative to that in adjacent noncancerous liver tissues. This decreased expression was significantly associated with tumor differentiation, the American Joint Committee on Cancer (AJCC) stage, metastasis, tumor size, vascular invasion, alpha-fetoprotein (AFP) levels, and tumor number. Moreover, multivariate Cox regression analyses demonstrated that Tg737 expression was an independent factor for predicting the overall survival of HCC patients. Notably, Kaplan-Meier analysis further showed that overall survival was significantly worse among patients with low Tg737 expression. Collectively, our findings demonstrated that Tg737 is a poor prognostic marker in patients with HCC, which may be due to its ability to promote LCSCs invasion and migration. These results provide a basis for investigating of Tg737 as a novel prognostic biomarker and therapeutic target.

Curcumin induces apoptotic cell death and protective autophagy in human gastric cancer cells

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.

The functional genomic studies of curcumin

Curcumin is a natural plant-derived compound that has attracted a lot of attention for its anti-cancer activities. Curcumin can slow proliferation of and induce apoptosis in cancer cell lines, but the precise mechanisms of these effects are not fully understood. However, many lines of evidence suggested that curcumin has a potent impact on gene expression profiles; thus, functional genomics should be the key to understanding how curcumin exerts its anti-cancer activities. Here, we review the published functional genomic studies of curcumin focusing on cancer. Typically, a cancer cell line or a grafted tumor were exposed to curcumin and profiled with microarrays, methylation assays, or RNA-seq. Crucially, these studies are in agreement that curcumin has a powerful effect on gene expression. In the majority of the studies, among differentially expressed genes we found genes involved in cell signaling, apoptosis, and the control of cell cycle. Curcumin can also induce specific methylation changes, and is a powerful regulator of the expression of microRNAs which control oncogenesis. We also reflect on how the broader technological progress in transcriptomics has been reflected on the field of curcumin. We conclude by discussing the areas where more functional genomic studies are highly desirable. Integrated OMICS approaches will clearly be the key to understanding curcumin's anticancer and chemopreventive effects. Such strategies may become a template for elucidating the mode of action of other natural products; many natural products have pleiotropic effects that are well suited for a systems-level analysis.

Anticancer Natural Compounds as Epigenetic Modulators of Gene Expression

Accumulating evidence shows that hallmarks of cancer include: "genetic and epigenetic alterations leading to inactivation of cancer suppressors, overexpression of oncogenes, deregulation of intracellular signaling cascades, alterations of cancer cell metabolism, failure to undergo cancer cell death, induction of epithelial to mesenchymal transition, invasiveness, metastasis, deregulation of immune response and changes in cancer microenvironment, which underpin cancer development". Natural compounds as bioactive ingredients isolated from natural sources (plants, fungi, marine life forms) have revolutionized the field of anticancer therapeutics and rapid developments in preclinical studies are encouraging. Natural compounds could affect the epigenetic molecular mechanisms that modulate gene expression, as well as DNA damage and repair mechanisms. The current review will describe the latest achievements in using naturally produced compounds targeting epigenetic regulators and modulators of gene transcription in vitro and in vivo to generate novel anticancer therapeutics.