Autophagic and apoptotic mechanisms of curcumin-induced death in K562 cells

Molecular mechanisms underlying chemopreventive potential of curcumin: Current challenges and future perspectives

In recent years, natural compounds have received considerable attention in preventing and curing most dreadful diseases including cancer. The reason behind the use of natural compounds in chemoprevention is associated with fewer numbers of side effects than conventional chemotherapeutics. Curcumin (diferuloylmethane, PubMed CID: 969516), a naturally occurring polyphenol, is derived from turmeric, which is used as a common Indian spice. It governs numerous intracellular targets, including proteins involved in antioxidant response, immune response, apoptosis, cell cycle regulation and tumor progression. A huge mass of available studies strongly supports the use of Curcumin as a chemopreventive drug. However, the main challenge encountered is the low bioavailability of Curcumin. This extensive review covers various therapeutic interactions of Curcumin with its recognized cellular targets involved in cancer treatment, strategies to overcome the bioavailability issue and adverse effects associated with Curcumin consumption.

Redox regulation of autophagy in healthy brain and neurodegeneration

Autophagy and redox biochemistry are two major sub disciplines of cell biology which are both coming to be appreciated for their paramount importance in the etiology of neurodegenerative diseases including Alzheimer's disease (AD). Thus far, however, there has been relatively little exploration of the interface between autophagy and redox biology. Autophagy normally recycles macro-molecular aggregates produced through oxidative-stress mediated pathways, and also may reduce the mitochondrial production of reactive oxygen species through recycling of old and damaged mitochondria. Conversely, dysfunction in autophagy initiation, progression or clearance is evidenced to increase aggregation-prone proteins in neural and extraneural tissues. Redox mechanisms of autophagy regulation have been documented at the level of cross-talk between the Nrf2/Keap1 oxidant and electrophilic defense pathway and p62/sequestosome-1 (SQSTM1)-associated autophagy, at least in extraneural tissue; but other mechanisms of redox autophagy regulation doubtless remain to be discovered and the relevance of such processes to maintenance of neural homeostasis remains to be determined. This review summarizes current knowledge regarding the relationship of redox signaling, autophagy control, and oxidative stress as these phenomena relate to neurodegenerative disease. AD is specifically addressed as an example of the theme and as a promising indication for new therapies that act through engagement of autophagy pathways. To exemplify one such novel therapeutic entity, data is presented that the antioxidant and neurotrophic agent lanthionine ketimine-ethyl ester (LKE) affects autophagy pathway proteins including beclin-1 in the 3xTg-AD model of Alzheimer's disease where the compound has been shown to reduce pathological features and cognitive dysfunction.

The role of natural polyphenols in cell signaling and cytoprotection against cancer development

The cytoprotective and anticancer action of dietary in-taken natural polyphenols has for long been attributed only to their direct radical scavenging activities. Currently it is well supported that those compounds display a broad spectrum of biological and pharmacological outcomes mediated by their complex metabolism, interaction with gut microbiota as well as direct interactions of their metabolites with key cellular signaling proteins. The beneficial effects of natural polyphenols and their synthetic derivatives are extensively studied in context of cancer prophylaxis and therapy. Herein we focus on cell signaling to explain the beneficial role of polyphenols at the three stages of cancer development: we review the recent proceedings about the impact of polyphenols on the cytoprotective antioxidant response and their proapoptotic action at the premalignant stage, and finally we present data showing how phenolic acids (e.g., caffeic, chlorogenic acids) and flavonols (e.g., quercetin) hamper the development of metastatic cancer.

Elaborating the role of natural products-induced autophagy in cancer treatment: achievements and artifacts in the state of the art

Autophagy is a homeostatic process that is highly conserved across different types of mammalian cells. Autophagy is able to relieve tumor cell from nutrient and oxidative stress during the rapid expansion of cancer. Excessive and sustained autophagy may lead to cell death and tumor shrinkage. It was shown in literature that many anticancer natural compounds and extracts could initiate autophagy in tumor cells. As summarized in this review, the tumor suppressive action of natural products-induced autophagy may lead to cell senescence, provoke apoptosis-independent cell death, and complement apoptotic cell death by robust or target-specific mechanisms. In some cases, natural products-induced autophagy could protect tumor cells from apoptotic death. Technical variations in detecting autophagy affect data quality, and study focus should be made on elaborating the role of autophagy in deciding cell fate. In vivo study monitoring of autophagy in cancer treatment is expected to be the future direction. The clinical-relevant action of autophagy-inducing natural products should be highlighted in future study. As natural products are an important resource in discovery of lead compound of anticancer drug, study on the role of autophagy in tumor suppressive effect of natural products continues to be necessary and emerging.

Regulation of autophagy by polyphenolic compounds as a potential therapeutic strategy for cancer

Autophagy, a lysosomal degradation pathway for cellular constituents and organelles, is an adaptive and essential process required for cellular homeostasis. Although autophagy functions as a survival mechanism in response to cellular stressors such as nutrient or growth factor deprivation, it can also lead to a non-apoptotic form of programmed cell death (PCD) called autophagy-induced cell death or autophagy-associated cell death (type II PCD). Current evidence suggests that cell death through autophagy can be induced as an alternative to apoptosis (type I PCD), with therapeutic purpose in cancer cells that are resistant to apoptosis. Thus, modulating autophagy is of great interest in cancer research and therapy. Natural polyphenolic compounds that are present in our diet, such as rottlerin, genistein, quercetin, curcumin, and resveratrol, can trigger type II PCD via various mechanisms through the canonical (Beclin-1 dependent) and non-canonical (Beclin-1 independent) routes of autophagy. The capacity of these compounds to provide a means of cancer cell death that enhances the effects of standard therapies should be taken into consideration for designing novel therapeutic strategies. This review focuses on the autophagy- and cell death-inducing effects of these polyphenolic compounds in cancer.

Feroniellin A-induced autophagy causes apoptosis in multidrug-resistant human A549 lung cancer cells

During the screening of natural chemicals that can reverse multidrug resistance in human A549 lung cancer cells resistant to etoposide (A549RT-eto), we discovered that Feroniellin A (FERO), a novel furanocoumarin, shows toxicity toward A549RT-eto cells in a dose- and time-dependent manner. FERO reduced the expression of NF-κB, leading to downregulation of P-glycoprotein (P-gp), encoded by MDR1, which eventually sensitized A549RT-eto cells to apoptosis. FERO specifically diminished transcription and promoter activity of MDR1 but did not inhibit the expression of other multidrug resistance genes MRP2 and BCRP. Moreover, co-administration of FERO with Bay11-7802, an inhibitor of NF-κB, accelerated apoptosis of A549RT-eto cells through decreased expression of P-gp, indicating that NF-κB is involved in multidrug resistance. Conversely, addition of Z-VAD, a pan-caspase inhibitor, blocked FERO-induced apoptosis in A549RT-eto cells but did not block downregulation of P-gp, indicating that a decrease in P-gp expression is necessary but not sufficient for FERO-induced apoptosis. Interestingly, we found that FERO also induces autophagy, which is characterized by the conversion of LC3 I to LC3 II, induction of GFP-LC3 puncta, enhanced expression of Beclin-1 and ATG5, and inactivation of mTOR. Furthermore, suppression of Beclin-1 by siRNA reduced FERO-induced apoptosis in A549RT-eto cells and activation of autophagy by rapamycin accelerated FERO-induced apoptosis, suggesting that autophagy plays an active role in FERO-induced apoptosis. Herein, we report that FERO reverses multidrug resistance in A549RT-eto cells and exerts its cytotoxic effect by induction of both autophagy and apoptosis, which suggests that FERO can be a useful anticancer drug for multidrug-resistant lung cancer.

Regulation of HA14-1 mediated oxidative stress, toxic response, and autophagy by curcumin to enhance apoptotic activity in human embryonic kidney cells

An alteration in susceptibility to apoptosis not only contributes to promotion of malignancy but can also enhance drug resistance in response to anticancer therapies. HA14-1 is a small molecule which has the potential of inducing apoptosis in cancerous cells. HA14-1 manifests an antagonistic effect on antiapoptotic protein Bcl-2 and consequently induces cell death in various cancerous cell lines. However, it is also known to generate ROS and toxic response in the cells upon decomposition. Elevated level of ROS is responsible for oxidative stress and other pathological consequences, if not metabolized properly. The aim of the present study was to examine the synergistic effect of curcumin in promoting apoptosis by regulating the HA14-1 mediated ROS generation, toxicity, oxidative stress, and autophagy in human embryonic kidney cells. Our study demonstrates that curcumin efficiently scavenges HA14-1 mediated generation of ROS and toxic response resulting in augmentation of apoptosis in HEK 293T cells by promoting inhibition of antiapoptotic proteins and process of autophagy. Thus curcumin along with HA14-1 regulates cell proliferation by disruption of the antiapoptotic signaling mechanism. This approach could serve as a promising strategy for therapeutic potential to overcome their adverse effects.

Synthesis, characterisation, and in vitro anticancer activity of curcumin analogues bearing pyrazole/pyrimidine ring targeting EGFR tyrosine kinase

In search of potential therapeutics for cancer, we described herein the synthesis, characterization, and in vitro anticancer activity of a novel series of curcumin analogues. The anticancer effects were evaluated on a panel of 60 cell lines, according to the National Cancer Institute (NCI) screening protocol. There were 10 tested compounds among 14 synthesized compounds, which showed potent anticancer activity in both one-dose and 5-dose assays. The most active compound of the series was 3,5-bis(4-hydroxy-3-methylstyryl)-1H-pyrazole-1-yl(phenyl)methanone (10) which showed mean growth percent of −28.71 in one-dose assay and GI₅₀ values between 0.0079 and 1.86 µM in 5-dose assay.

Apoptotic and autophagic effects of Sesbania grandiflora flowers in human leukemic cells

Background

Identification of cytotoxic compounds that induce apoptosis has been the mainstay of anti-cancer therapeutics for several decades. In recent years, focus has shifted to inducing multiple modes of cell death coupled with reduced systemic toxicity. The plant Sesbania grandiflora is widely used in Indian traditional medicine for the treatment of a broad spectrum of diseases. This encouraged us to investigate into the anti-proliferative effect of a fraction (F2) isolated from S. grandiflora flowers in cancer cells and delineate the underlying involvement of apoptotic and autophagic pathways.

Principal Findings

Using MTT based cell viability assay, we evaluated the cytotoxic potential of fraction F2. It was the most effective on U937 cells (IC₅₀∶18.6 µg/ml). Inhibition of growth involved enhancement of Annexin V positivity. This was associated with elevated reactive oxygen species generation, measured by flow cytometry and reduced oxygen consumption – both effects being abrogated by anti-oxidant NAC. This caused stimulation of pro-apoptotic proteins and concomitant inhibition of anti-apoptotic protein expressions inducing mitochondrial depolarization, as measured by flow cytometry and release of cytochrome c. Interestingly, even with these molecular features of apoptosis, F2 was able to alter Atg protein levels and induce LC3 processing. This was accompanied by formation of autophagic vacuoles as revealed by fluorescence and transmission electron microscopy – confirming the occurrence of autophagy. Eventually, F2 triggered caspase cascade – executioners of programmed cell death and AIF translocation to nuclei. This culminated in cleavage of the DNA repair enzyme, poly (ADP-ribose) polymerase that caused DNA damage as proved by staining with Hoechst 33258 leading to cell death.

Conclusions

The findings suggest fraction F2 triggers pro-oxidant activity and mediates its cytotoxicity in leukemic cells via apoptosis and autophagy. Thus, it merits consideration and further investigation as a therapeutic option for the treatment of leukemia.

Neem leaf extract induces cell death by apoptosis and autophagy in B-chronic lymphocytic leukemia cells

Chronic lymphocytic leukemia (CLL) is the most common adult leukemia and is currently incurable. To expand the therapeutic armamentarium, we investigated neem leaf extract (NLE) after a patient with CLL demonstrated disease regression upon taking oral NLE. NLE-mediated apoptosis was examined in peripheral blood mononuclear cells (PBMCs) from 41 patients with CLL. NLE induced a dose-dependent reduction in CLL cell viability with significant apoptosis observed at 0.06% (w/v) by 24 h. Annexin-V staining and poly(ADP-ribose) polymerase 1 (PARP-1) and caspase 3 cleavage were observed after NLE treatment. However, a pan-caspase inhibitor only partially blocked NLE-mediated cell death. NLE also caused loss of mitochondrial outer membrane permeability and nuclear translocation of apoptosis-inducing factor. Furthermore, NLE treatment resulted in LC3-I cleavage. Biochemical analyses revealed that NLE also inhibits Bcl-2 and p53 proteins. In summary, NLE exhibits anti-leukemic properties in patient primary CLL cells and demonstrates clinical efficacy, warranting further investigation as a potential therapy for CLL.

Amyloidosis in Alzheimer's Disease: The Toxicity of Amyloid Beta (A β ), Mechanisms of Its Accumulation and Implications of Medicinal Plants for Therapy

Alzheimer's disease (AD) is a progressive neurodegenerative disorder that leads to memory deficits and death. While the number of individuals with AD is rising each year due to the longer life expectancy worldwide, current therapy can only somewhat relieve the symptoms of AD. There is no proven medication to cure or prevent the disease, possibly due to a lack of knowledge regarding the molecular mechanisms underlying disease pathogenesis. Most previous studies have accepted the “amyloid hypothesis,” in which the neuropathogenesis of AD is believed to be triggered by the accumulation of the toxic amyloid beta (Aβ) protein in the central nervous system (CNS). Lately, knowledge that may be critical to unraveling the hidden pathogenic pathway of AD has been revealed. This review concentrates on the toxicity of Aβ and the mechanism of accumulation of this toxic protein in the brain of individuals with AD and also summarizes recent advances in the study of these accumulation mechanisms together with the role of herbal medicines that could facilitate the development of more effective therapeutic and preventive strategies.

Small-molecule regulators of autophagy and their potential therapeutic applications

Autophagy is a highly conserved process in which damaged proteins and organelles are sequestered in double-membrane autophagosomes and delivered to lysosomes for degradation and recycling. As an efficient response to cellular stress, autophagy is essential for the maintenance of cellular homeostasis. Defective autophagy is associated with a variety of diseases, including cancer. This article summarizes current knowledge about the molecular mechanism of autophagy and its role in tumorigenesis. Particular focus is placed on the development of small-molecule regulators of autophagy and their potential application as anticancer therapeutic agents.

Curcumin, a component of turmeric: from farm to pharmacy

Curcumin, an active polyphenol of the golden spice turmeric, is a highly pleiotropic molecule with the potential to modulate the biological activity of a number of signaling molecules. Traditionally, this polyphenol has been used in Asian countries to treat such human ailments as acne, psoriasis, dermatitis, and rash. Recent studies have indicated that curcumin can target newly identified signaling pathways including those associated with microRNA, cancer stem cells, and autophagy. Extensive research from preclinical and clinical studies has delineated the molecular basis for the pharmaceutical uses of this polyphenol against cancer, pulmonary diseases, neurological diseases, liver diseases, metabolic diseases, autoimmune diseases, cardiovascular diseases, and numerous other chronic diseases. Multiple studies have indicated the safety and efficacy of curcumin in numerous animals including rodents, monkeys, horses, rabbits, and cats and have provided a solid basis for evaluating its safety and efficacy in humans. To date, more than 65 human clinical trials of curcumin, which included more than 1000 patients, have been completed, and as many as 35 clinical trials are underway. Curcumin is now used as a supplement in several countries including the United States, India, Japan, Korea, Thailand, China, Turkey, South Africa, Nepal, and Pakistan. In this review, we provide evidence for the pharmaceutical uses of curcumin for various diseases.

In vitro evaluation of schistosomicidal potential of curcumin against Schistosoma japonicum

Curcumin is a polyphenol derived from the dietary spice turmeric. The aim of this study was to investigate the in vitro effect of curcumin against eggs, cercariae, pre-adults, and adults of Schistosoma japonicum compared to praziquantel. After incubated by different concentration of curcumin or praziquantel in different time, the percent hatching rates of eggs, the percent dead rates of cercariae, and the number of dead worms were observed. Curcumin showed time- and dose-dependent schistosomicidal effects on every life stages of S. japonicum. In addition, curcumin exhibited an optimal activity against the adult stage with no differential sensitivity between male and female worms and decreased motor activity of these worms without tegumental alterations. The promising in vitro effects on all stages of S. japonicum warrants further evaluation for the prophylactic and therapeutic values in the early and late schistosomiasis in field trials.

Plant natural compounds: targeting pathways of autophagy as anti-cancer therapeutic agents

Natural compounds derived from plant sources are well characterized as possessing a wide variety of remarkable anti-tumour properties, for example modulating programmed cell death, primarily referring to apoptosis, and autophagy. Distinct from apoptosis, autophagy (an evolutionarily conserved, multi-step lysosomal degradation process in which a cell destroys long-lived proteins and damaged organelles) may play crucial regulatory roles in many pathological processes, most notably in cancer. In this review, we focus on highlighting several representative plant natural compounds such as curcumin, resveratrol, paclitaxel, oridonin, quercetin and plant lectin - that may lead to cancer cell death - for regulation of some core autophagic pathways, involved in Ras-Raf signalling, Beclin-1 interactome, BCR-ABL, PI3KCI/Akt/mTOR, FOXO1 signalling and p53. Taken together, these findings would provide a new perspective for exploiting more plant natural compounds as potential novel anti-tumour drugs, by targeting the pathways of autophagy, for future cancer therapeutics.

Curcumin: updated molecular mechanisms and intervention targets in human lung cancer

Curcumin, a yellow pigment derived from Curcuma longa Linn, has attracted great interest in the research of cancer during the past decades. Extensive studies documented that curcumin attenuates cancer cell proliferation and promotes apoptosis in vivo and in vitro. Curcumin has been demonstrated to interact with multiple molecules and signal pathways, which makes it a potential adjuvant anti-cancer agent to chemotherapy. Previous investigations focus on the mechanisms of action for curcumin, which is shown to manipulate transcription factors and induce apoptosis in various kinds of human cancer. Apart from transcription factors and apoptosis, emerging studies shed light on latent targets of curcumin against epidermal growth factor receptor (EGFR), microRNAs (miRNA), autophagy and cancer stem cell. The present review predominantly discusses significance of EGFR, miRNA, autophagy and cancer stem cell in lung cancer therapy. Curcumin as a natural phytochemicals could communicate with these novel targets and show synergism to chemotherapy. Additionally, curcumin is well tolerated in humans. Therefore, EGFR-, miRNA-, autophagy- and cancer stem cell-based therapy in the presence of curcumin might be promising mechanisms and targets in the therapeutic strategy of lung cancer.

Curcumin induces autophagy in ACC-MESO-1 cells

Malignant pleural mesothelioma is known to be widely resistant to therapy and new treatment strategies are needed. Curcumin, which has a long history as a dietary spice is known to suppress the growth of multiple cancer lines, but the effects on mesothelioma cells are not well defined. In the present study we examined the effects of curcumin on ACC-MESO-1, which is a human derived mesothelioma cell line. We found that curcumin dose-dependently reduced cell viability but did not induce apoptosis. Curcumin administration increased LC3B-II/LC3B-I expression, and induced the formation of autophagosomes on electron microscopy. These changes were attenuated by RNA silencing of atg5. From these findings it was speculated that induction of autophagy was at least in part involved in the reduction of cell viability by curcumin.

Mitochondrial effects of plant-made compounds

SIGNIFICANCE

Plants produce many small molecules with biomedical potential. Their absorption from foods, metabolism, their effects on physiological and pathological processes, and the mechanisms of action are intensely investigated. Many are known to affect multiple cellular functions. Mitochondria are coming to be recognized as a major target for these compounds, especially redox-active ones, but the mechanisms involved still need clarification. At the same time, frontline research is uncovering the importance of processes involving these organelles for the cell and for an array of physiological and pathological processes. We review the major functions and possible dysfunctions of mitochondria, identify signaling pathways through which plant-derived molecules have an impact, and show how this may be relevant for major pathologies.

RECENT ADVANCES

Antioxidant, protective effects may arise as a reaction to a low-level pro-oxidant activity, largely taking place at mitochondria. Some plant-derived molecules can activate AMP-dependent kinase, with a consequent upregulation of mitochondrial biogenesis and a potential favorable impact on aging, pathologies like diabetes and neurodegeneration, and on ischemic damage.

CRITICAL ISSUES

The extrapolation of in vitro results and the verification of paradigms in vivo is a key issue for current research on both plant-derived compounds and mitochondria. The low bioavailability of many of these molecules poses a problem for both the study of their activities and their utilization.

FUTURE DIRECTIONS

The further clarification of the role of mitochondria in the activities of plant dietary compounds and their metabolites, mitochondrial targeting, the development of analogs and pro-drugs are all topics for promising research.

Anti-cancer natural products isolated from chinese medicinal herbs

In recent years, a number of natural products isolated from Chinese herbs have been found to inhibit proliferation, induce apoptosis, suppress angiogenesis, retard metastasis and enhance chemotherapy, exhibiting anti-cancer potential both in vitro and in vivo. This article summarizes recent advances in in vitro and in vivo research on the anti-cancer effects and related mechanisms of some promising natural products. These natural products are also reviewed for their therapeutic potentials, including flavonoids (gambogic acid, curcumin, wogonin and silibinin), alkaloids (berberine), terpenes (artemisinin, β-elemene, oridonin, triptolide, and ursolic acid), quinones (shikonin and emodin) and saponins (ginsenoside Rg3), which are isolated from Chinese medicinal herbs. In particular, the discovery of the new use of artemisinin derivatives as excellent anti-cancer drugs is also reviewed.

Anti-cancer natural products isolated from chinese medicinal herbs

In recent years, a number of natural products isolated from Chinese herbs have been found to inhibit proliferation, induce apoptosis, suppress angiogenesis, retard metastasis and enhance chemotherapy, exhibiting anti-cancer potential both in vitro and in vivo. This article summarizes recent advances in in vitro and in vivo research on the anti-cancer effects and related mechanisms of some promising natural products. These natural products are also reviewed for their therapeutic potentials, including flavonoids (gambogic acid, curcumin, wogonin and silibinin), alkaloids (berberine), terpenes (artemisinin, β-elemene, oridonin, triptolide, and ursolic acid), quinones (shikonin and emodin) and saponins (ginsenoside Rg₃), which are isolated from Chinese medicinal herbs. In particular, the discovery of the new use of artemisinin derivatives as excellent anti-cancer drugs is also reviewed.

Does autophagy take a front seat in lifespan extension?

This review focuses on the interrelationship between ageing and autophagy. There is a striking similarity between the signalling aspects of these two processes. Both ageing and autophagy involve several of the signalling components such as insulin/IGF-1, AMPK, Ras-cAMP-PKA, Sch9 and mTOR. Ageing and ageing-mediated defective autophagy involve accumulation of lipofuscin. Components of anti-ageing and autophagy include SirTs and FoxOs. Nutritional deprivation or calorie restriction as well as several nutriceuticals including resveratrol, spermidine, curcumin and piperine can enhance autophagy and increase lifespan. Such striking similarities indicate that lifespan is strongly dependent on autophagy.

Involvement of ROS in Curcumin-induced Autophagic Cell Death

Many anticancer agents as well as ionizing radiation have been shown to induce autophagy which is originally described as a protein recycling process and recently reported to play a crucial role in various disorders. In HCT116 human colon cancer cells, we found that curcumin, a polyphenolic phytochemical extracted from the plant Curcuma longa, markedly induced the conversion of microtubule-associated protein 1 light chain 3 (LC3)-I to LC3-II and degradation of sequestome-1 (SQSTM1) which is a marker of autophagosome degradation. Moreover, we found that curcumin caused GFP-LC3 formation puncta, a marker of autophagosome, and decrease of GFP-LC3 and SQSTM1 protein level in GFP-LC3 expressing HCT116 cells. It was further confirmed that treatment of cells with hydrogen peroxide induced increase of LC3 conversion and decrease of GFP-LC3 and SQSTM1 levels, but these changes by curcumin were almost completely blocked in the presence of antioxidant, N-acetylcystein (NAC), indicating that curcumin leads to reactive oxygen species (ROS) production, which results in autophagosome development and autolysosomal degradation. In parallel with NAC, SQSTM1 degradation was also diminished by bafilomycin A, a potent inhibitor of autophagosome-lysosome fusion, and cell viability assay was further confirmed that cucurmin-induced cell death was partially blocked by bafilomycin A as well as NAC. We also observed that NAC abolished curcumin-induced activation of extracelluar signal-regulated kinases (ERK) 1/2 and p38 mitogen-activated protein kinases (MAPK), but not Jun N-terminal kinase (JNK). However, the activation of ERK1/2 and p38 MAPK seemed to have no effect on the curcumin-induced autophagy, since both the conversion of LC3 protein and SQSTM1 degradation by curcumin was not changed in the presence of NAC. Taken together, our data suggest that curcumin induced ROS production, which resulted in autophagic activation and concomitant cell death in HCT116 human colon cancer cell. However, ROS-dependent activation of ERK1/2 and p38 MAPK, but not JNK, might not be involved in the curcumin-induced autophagy.

Curcumin: A review of anti-cancer properties and therapeutic activity in head and neck squamous cell carcinoma

Curcumin (diferuloylmethane) is a polyphenol derived from the Curcuma longa plant, commonly known as turmeric. Curcumin has been used extensively in Ayurvedic medicine for centuries, as it is nontoxic and has a variety of therapeutic properties including anti-oxidant, analgesic, anti-inflammatory and antiseptic activity. More recently curcumin has been found to possess anti-cancer activities via its effect on a variety of biological pathways involved in mutagenesis, oncogene expression, cell cycle regulation, apoptosis, tumorigenesis and metastasis. Curcumin has shown anti-proliferative effect in multiple cancers, and is an inhibitor of the transcription factor NF-κB and downstream gene products (including c-myc, Bcl-2, COX-2, NOS, Cyclin D1, TNF-α, interleukins and MMP-9). In addition, curcumin affects a variety of growth factor receptors and cell adhesion molecules involved in tumor growth, angiogenesis and metastasis. Head and neck squamous cell carcinoma (HNSCC) is the sixth most common cancer worldwide and treatment protocols include disfiguring surgery, platinum-based chemotherapy and radiation, all of which may result in tremendous patient morbidity. As a result, there is significant interest in developing adjuvant chemotherapies to augment currently available treatment protocols, which may allow decreased side effects and toxicity without compromising therapeutic efficacy. Curcumin is one such potential candidate, and this review presents an overview of the current in vitro and in vivo data supporting its therapeutic activity in head and neck cancer as well as some of the challenges concerning its development as an adjuvant chemotherapeutic agent.

A pilot study on morphology and the mechanism involved in linearly patterned programmed cell necrosis in melanoma

Accumulating data provide evidence that autophagy contributes to programmed cell death (PCD) under certain circumstances. Immunohistochemistry and real-time PCR were performed to investigate the correlation the expression of autophagy-related proteins LC3 and Atg4B and linearly patterned programmed cell necrosis (LPPCN) in melanoma. LPPCN was recently reported to be a special PCD, which is similar to neither apoptosis nor conventional necrosis commonly observed in tumoral tissues. The mechanism involved in LPPCN remains unclear. Our data showed that the expression of LC3 and Atg4B in the LPPCN-positive group was significantly higher than that in the LPPCN-negative group regarding protein and mRNA levels (p<0.05). Based on morphological observation, immunohistochemistry and real-time PCR experiments in this study, it was concluded that autophagy may play a crucial role in the process of LPP+CN in melanoma. This study provides novel insights into the mechanism that regulates LPPCN in vivo during tumor development. We speculated that LPPCN may be an early stage event in tumoral neovascularization under hypoxic-microenvironmental conditions. Accordingly, LPPCN can be considered a novel target in the process of antiangiogenesis treatment, which can be expected to obtain a better clinical outcome in the future.