Curcumin induces proapoptotic effects against human melanoma cells and modulates the cellular response to immunotherapeutic cytokines

Targeting anticancer immunity in melanoma tumour microenvironment: unleashing the potential of adjuvants, drugs, and phytochemicals

Melanoma poses a challenge in oncology because of its aggressive nature and limited treatment modalities. The tumour microenvironment (TME) in melanoma contains unique properties such as an immunosuppressive and high-density environment, unusual vasculature, and a high number of stromal and immunosuppressive cells. In recent years, numerous experiments have focused on boosting the immune system to effectively remove malignant cells. Adjuvants, consisting of phytochemicals, toll-like receptor (TLR) agonists, and cytokines, have shown encouraging results in triggering antitumor immunity and augmenting the therapeutic effectiveness of anticancer therapy. These adjuvants can stimulate the maturation of dendritic cells (DCs) and infiltration of cytotoxic CD8+ T lymphocytes (CTLs). Furthermore, nanocarriers can help to deliver immunomodulators and antigens directly to the tumour stroma, thereby improving their efficacy against malignant cells. The remodelling of melanoma TME utilising phytochemicals, agonists, and other adjuvants can be combined with current modalities for improving therapy outcomes. This review article explores the potential of adjuvants, drugs, and their nanoformulations in enhancing the anticancer potency of macrophages, CTLs, and natural killer (NK) cells. Additionally, the capacity of these agents to repress the function of immunosuppressive components of melanoma TME, such as immunosuppressive subsets of macrophages, stromal and myeloid cells will be discussed.

Effect of polyphenols against complications of COVID-19: current evidence and potential efficacy

The COVID-19 pandemic that started in 2019 and resulted in significant morbidity and mortality continues to be a significant global health challenge, characterized by inflammation, oxidative stress, and immune system dysfunction.. Developing therapies for preventing or treating COVID-19 remains an important goal for pharmacology and drug development research. Polyphenols are effective against various viral infections and can be extracted and isolated from plants without losing their therapeutic potential. Researchers have developed methods for separating and isolating polyphenols from complex matrices. Polyphenols are effective in treating common viral infections, including COVID-19, and can also boost immunity. Polyphenolic-based antiviral medications can mitigate SARS-CoV-2 enzymes vital to virus replication and infection. Individual polyphenolic triterpenoids, flavonoids, anthraquinonoids, and tannins may also inhibit the SARS-CoV-2 protease. Polyphenol pharmacophore structures identified to date can explain their action and lead to the design of novel anti-COVID-19 compounds. Polyphenol-containing mixtures offer the advantages of a well-recognized safety profile with few known severe side effects. However, studies to date are limited, and further animal studies and randomized controlled trials are needed in future studies. The purpose of this study was to review and present the latest findings on the therapeutic impact of plant-derived polyphenols on COVID-19 infection and its complications. Exploring alternative approaches to traditional therapies could aid in developing novel drugs and remedies against coronavirus infection.

The Combination of Bioavailable Concentrations of Curcumin and Resveratrol Shapes Immune Responses While Retaining the Ability to Reduce Cancer Cell Survival

The polyphenols Curcumin (CUR) and Resveratrol (RES) are widely described for their antitumoral effects. However, their low bioavailability is a drawback for their use in therapy. The aim of this study was to explore whether CUR and RES, used at a bioavailable concentration, could modulate immune responses while retaining antitumor activity and to determine whether CUR and RES effects on the immune responses of peripheral blood mononuclear cells (PBMCs) and tumor growth inhibition could be improved by their combination. We demonstrate that the low-dose combination of CUR and RES reduced the survival of cancer cell lines but had no effect on the viability of PBMCs. Although following CUR + RES treatment T lymphocytes showed an enhanced activated state, RES counteracted the increased IFN-γ expression induced by CUR in T cells and the polyphenol combination increased IL-10 production by T regulatory cells. On the other hand, the combined treatment enhanced NK cell activity through the up- and downregulation of activating and inhibitory receptors and increased CD68 expression levels on monocytes/macrophages. Overall, our results indicate that the combination of CUR and RES at low doses differentially shapes immune cells while retaining antitumor activity, support the use of this polyphenol combinations in anticancer therapy and suggest its possible application as adjuvant for NK cell-based immunotherapies.

Modulatory properties of curcumin in cancer: A narrative review on the role of interferons

The immune network is an effective network of cell types and chemical compounds established to maintain the body's homeostasis from foreign threats and to prevent the risk of a wide range of diseases; hence, its proper functioning and balance are essential. A dysfunctional immune system can contribute to various disorders, including cancer. Therefore, there has been considerable interest in molecules that can modulate the immune network. Curcumin, the active ingredient of turmeric, is one of these herbal remedies with many beneficial effects, including modulation of immunity. Curcumin is beneficial in managing various chronic inflammatory conditions, improving brain function, lowering cardiovascular disease risk, prevention and management of dementia, and prevention of aging. Several clinical studies have supported this evidence, suggesting curcumin to have an immunomodulatory and anti-inflammatory function; nevertheless, its mechanism of action is still not clear. In the current review, we aim to explore the modulatory function of curcumin through interferons in cancers.

Combination Therapy of Curcumin and Disulfiram Synergistically Inhibits the Growth of B16-F10 Melanoma Cells by Inducing Oxidative Stress

Oxidative stress plays a central role in the pathophysiology of melanoma. Curcumin (CUR) is a polyphenolic phytochemical that stimulates reactive oxygen species (ROS) production, while disulfiram (DSS) is a US FDA-approved drug for the treatment of alcoholism that can act by inhibiting the intracellular antioxidant system. Therefore, we hypothesized that they act synergistically against melanoma cells. Herein, we aimed to study the antitumor potential of the combination of CUR with DSS in B16-F10 melanoma cells using in vitro and in vivo models. The cytotoxic effects of different combination ratios of CUR and DSS were evaluated using the Alamar Blue method, allowing the production of isobolograms. Apoptosis detection, DNA fragmentation, cell cycle distribution, and mitochondrial superoxide levels were quantified by flow cytometry. Tumor development in vivo was evaluated using C57BL/6 mice bearing B16-F10 cells. The combinations ratios of 1:2, 1:3, and 2:3 showed synergic effects. B16-F10 cells treated with these combinations showed improved apoptotic cell death and DNA fragmentation. Enhanced mitochondrial superoxide levels were observed at combination ratios of 1:2 and 1:3, indicating increased oxidative stress. In vivo tumor growth inhibition for CUR (20 mg/kg), DSS (60 mg/kg), and their combination were 17.0%, 19.8%, and 28.8%, respectively. This study provided data on the potential cytotoxic activity of the combination of CUR with DSS and may provide a useful tool for the development of a therapeutic combination against melanoma.

Curcumin suppresses cell proliferation and triggers apoptosis in vemurafenib-resistant melanoma cells by downregulating the EGFR signaling pathway

Melanoma is a malignant tumor with aggressive behavior. Vemurafenib, a BRAF inhibitor, is clinically used in melanoma, but resistance to melanoma cytotoxic therapies is associated with BRAF mutations. Curcumin can effectively inhibit numerous types of cancers. However, there are no reports regarding the correlation between curcumin and vemurafenib-resistant melanoma cells. In this study, vemurafenib-resistant A375.S2 (A375.S2/VR) cells were established, and the functional mechanism of the epidermal growth factor receptor (EGFR), serine-threonine kinase (AKT), and the extracellular signal-regulated kinase (ERK) signaling induced by curcumin was investigated in A375.S2/VR cells in vitro. Our results indicated that A375.S2/VR cells had a higher IC₅₀ concentration of vemurafenib than the parental A375.S2 cells. Moreover, curcumin reduced the viability and confluence of A375.S2/VR cells. Curcumin triggered apoptosis via reactive oxygen species (ROS) production, disruption of mitochondrial membrane potential (ΔΨm), and intrinsic signaling (caspase-9/-3-dependent) pathways in A375.S2/VR cells. Curcumin-induced apoptosis was also mediated by the EGFR signaling pathway. Combination treatment with curcumin and gefitinib (an EGFR inhibitor) synergistically potentiated the inhibitory effect of cell viability in A375.S2/VR cells. The present study provides new insights into the therapy of vemurafenib-resistant melanoma and suggests that curcumin might be an encouraging therapeutic candidate for its drug-resistant treatment.

Potential Therapeutic Targets of Curcumin, Most Abundant Active Compound of Turmeric Spice: Role in the Management of Various Types of Cancer

BACKGROUND

Curcumin, an active compound of turmeric spice, is one of the most-studied natural compounds and has been widely recognized as a chemopreventive agent. Several molecular mechanisms have proven that curcumin and its analogs play a role in cancer prevention through modulating various cell signaling pathways as well as in the inhibition of the carcinogenesis process.

OBJECTIVE

To study the potential role of curcumin in the management of various types of cancer through modulating cell signalling molecules based on available literature and recent patents.

METHODS

A wide-ranging literature survey was performed based on Scopus, PubMed, PubMed Central, and Google scholar for the implication of curcumin in cancer management, along with a special emphasis on human clinical trials. Moreover, patents were searched through www.google.com/patents, www.freepatentsonline.com, and www.freshpatents.com.

RESULT

Recent studies based on cancer cells have proven that curcumin has potential effects against cancer cells as it prevents the growth of cancer and acts as a cancer therapeutic agent. Besides, curcumin exerted anti-cancer effects by inducing apoptosis, activating tumor suppressor genes, cell cycle arrest, inhibiting tumor angiogenesis, initiation, promotion, and progression stages of tumor. It was established that co-treatment of curcumin and anti-cancer drugs could induce apoptosis and also play a significant role in the suppression of the invasion and metastasis of cancer cells.

CONCLUSION

Accumulating evidences suggest that curcumin has the potential to inhibit cancer growth, induce apoptosis, and modulate various cell signaling pathway molecules. Well-designed clinical trials of curcumin based on human subjects are still needed to establish the bioavailability, mechanism of action, efficacy, and safe dose in the management of various cancers.

Xmrks the Spot: Fish Models for Investigating Epidermal Growth Factor Receptor Signaling in Cancer Research

Studies conducted in several fish species, e.g., Xiphophorus hellerii (green swordtail) and Xiphophorus maculatus (southern platyfish) crosses, Oryzias latipes (medaka), and Danio rerio (zebrafish), have identified an oncogenic role for the receptor tyrosine kinase, Xmrk, a gene product closely related to the human epidermal growth factor receptor (EGFR), which is associated with a wide variety of pathological conditions, including cancer. Comparative analyses of Xmrk and EGFR signal transduction in melanoma have shown that both utilize STAT5 signaling to regulate apoptosis and cell proliferation, PI3K to modulate apoptosis, FAK to control migration, and the Ras/Raf/MEK/MAPK pathway to regulate cell survival, proliferation, and differentiation. Further, Xmrk and EGFR may also modulate similar chemokine, extracellular matrix, oxidative stress, and microRNA signaling pathways in melanoma. In hepatocellular carcinoma (HCC), Xmrk and EGFR signaling utilize STAT5 to regulate cell proliferation, and Xmrk may signal through PI3K and FasR to modulate apoptosis. At the same time, both activate the Ras/Raf/MEK/MAPK pathway to regulate cell proliferation and E-cadherin signaling. Xmrk models of melanoma have shown that inhibitors of PI3K and MEK have an anti-cancer effect, and in HCC, that the steroidal drug, adrenosterone, can prevent metastasis and recover E-cadherin expression, suggesting that fish Xmrk models can exploit similarities with EGFR signal transduction to identify and study new chemotherapeutic drugs.

Design of New Improved Curcumin Derivatives to Multi-targets of Cancer and Inflammation

BACKGROUND

Curcumin is a major active principle of Curcuma longa. There are more than 1700 citations in the Medline, reflecting various biological effects of curcumin. Most of these biological activities are associated with the antioxidant, anti-inflammatory and antitumor activity of the molecule. Several reports suggest various targets of natural curcumin that include growth factors, growth factor receptor, cytokines, enzymes and gene regulators of apoptosis. This review focuses on the improved curcumin derivatives that target the cancer and inflammation.

METHODOLOGY

In this present review, we explored the anticancer drugs with curcumin-based drugs under pre-clinical and clinical studies with critical examination. Based on the strong scientific reports of patentable and non-patented literature survey, we have investigated the mode of the interactions of curcumin-based molecules with the target molecules.

RESULTS

Advanced studies have added new dimensions of the molecular response of cancer cells to curcumin at the genomic level. However, poor bioavailability of the molecule seems to be the major limitation of the curcumin. Several researchers have been involved to improve the curcumin derivatives to overcome this limitation. Sufficient data of clinical trials to various cancers that include multiple myeloma, pancreatic cancer and colon cancer, have also been discussed.

CONCLUSION

The detailed analysis of the structure-activity relationship (SAR) and common synthesis of curcumin-based derivatives have been discussed in the review. Utilising the predictions of in silico coupled with validation reports of in vitro and in vivo studies have concluded many targets for curcumin. Among them, cancer-related inflammation genes regulating curcumin-based molecules are a very promising target to overcome hurdles in the multimodality therapy of cancer.

Targeting the tumor immune microenvironment with "nutraceuticals": From bench to clinical trials

The occurrence of immune effector cells in the tissue microenvironment during neoplastic progression is critical in determining tumor growth outcomes. On the other hand, tumors may also avoid immune system-mediated elimination by recruiting immunosuppressive leukocytes and soluble factors, which coordinate a tumor microenvironment that counteracts the efficiency of the antitumor immune response. Checkpoint inhibitor therapy results have indicated a way forward via activation of the immune system against cancer. Widespread evidence has shown that different compounds in foods, when administered as purified substances, can act as immunomodulators in humans and animals. Although there is no universally accepted definition of nutraceuticals, the term identifies a wide category of natural compounds that may impact health and disease statuses and includes purified substances from natural sources, plant extracts, dietary supplements, vitamins, phytonutrients, and various products with combinations of functional ingredients. In this review, we summarize the current knowledge on the immunomodulatory effects of nutraceuticals with a special focus on the cancer microenvironment, highlighting the conceptual benefits or drawbacks and subtle cell-specific effects of nutraceuticals for envisioning future therapies employing nutraceuticals as chemoadjuvants.

STAT3 transcription factor as target for anti-cancer therapy

STATs constitute a large family of transcription activators and transducers of signals that have an important role in many cell functions as regulation of proliferation and differentiation of the cell also regulation of apoptosis and angiogenesis. STAT3 as a member of that family, recently was discovered to have a vital role in progression of different types of cancers. The activation of STAT3 was observed to regulate multiple gene functions during cancer-like cell proliferation, differentiation, apoptosis, metastasis, inflammation, immunity, cell survival, and angiogenesis. The inhibition of STAT3 activation has been an important target for cancer therapy. Inhibitors of STAT3 have been used for a long time for treatment of many types of cancers like leukemia, melanoma, colon, and renal cancer. In this review article, we summarize and discuss different drugs inhibiting the action of STAT3 and used in treatment of different types of cancer.

Synergistic Induction of Apoptosis by Quercetin and Curcumin in Chronic Myeloid Leukemia (K562) Cells: II. Signal Transduction Pathways Involved

Flavonoids are phenolic substances with chemo-preventive and chemotherapeutic properties. They are widely found in fruits and vegetables. The polyphenols quercetin and curcumin have antioxidant, anti-inflammatory, anti-carcinogenic, and pro-apoptotic properties. They were successfully used against different human cancers, especially chronic myeloid leukemia cancer cells. We have previously investigated anti-proliferative and apoptotic effects of quercetin and curcumin combination in K562 cells. Our data showed that they had beneficial synergistic effects. Based on these findings, we aimed to clarify signaling pathways involved in synergistic combination treatment with quercetin and curcumin in these cells. Proteins were investigated by Western blotting and by confocal microscopy. Changes in several genes in 10 different pathways related to cell proliferation, apoptosis, cell cycle, inflammation, hypoxia and oxidative stress were observed. Combination of quercetin and curcumin was effective on genes that were particularly related to p53, NF-κB and TGF-α pathways. Down-regulatory (CDKN1B, AKT1, IFN-γ) and up-regulatory (BTG2, CDKN1A, FAS) effects on genes and related protein expressions may provide a multi-targeted therapy potential for chronic myeloid leukemia cancer cells without affecting healthy cells.

Natural Compounds with Potential to Modulate Cancer Therapies and Self-Reactive Immune Cells

Cancer-related deaths are approaching 10 million each year. Survival statistics for some cancers, such as ovarian cancer, have remained unchanged for decades, with women diagnosed at stage III or IV having over 80% chance of a lethal cancer recurrence after standard first-line treatment (reductive surgery and chemotherapy). New treatments and adjunct therapies are needed. In ovarian cancer, as in other cancers, the immune response, particularly cytotoxic (CD8⁺) T cells are correlated with a decreased risk of recurrence. As well as completely new antigen targets resulting from DNA mutations (neo-antigens), these T cells recognize cancer-associated overexpressed, re-expressed or modified self-proteins. However, there is concern that activation of self-reactive responses may also promote off-target pathology. This review considers the complex interplay between cancer-reactive and self-reactive immune cells and discusses the potential uses for various leading immunomodulatory compounds, derived from plant-based sources, as a cancer therapy option or to modulate potential autoimmune pathology. Along with reviewing well-studied compounds such as curcumin (from turmeric), epigallocatechin gallate (EGCG, from green tea) and resveratrol (from grapes and certain berries), it is proposed that compounds from novel sources, for example, native Australian plants, will provide a useful source for the fine modulation of cancer immunity in patients.

Potential therapeutic effects of curcumin mediated by JAK/STAT signaling pathway: A review

Curcumin is a naturally occurring nutraceutical compound with a number of therapeutic and biological activities such as antioxidant, anti-inflammatory, anti-diabetic, antitumor, and cardioprotective. This plant-derived chemical has demonstrated great potential in targeting various signaling pathways to exert its protective effects. Signal transducers and activator of transcription (STAT) is one of the molecular pathways involved in a variety of biological processes such as cell proliferation and cell apoptosis. Accumulating data demonstrates that the STAT pathway is an important target in treatment of a number of disorders, particularly cancer. Curcumin is capable of affecting STAT signaling pathway in induction of its therapeutic impacts. Curcumin is able to enhance the level of anti-inflammatory cytokines and improve inflammatory disorders such as colitis by targeting STAT signaling pathway. Furthermore, studies show that inhibition of JAK/STAT pathway by curcumin is involved in reduced migration and invasion of cancer cells. Curcumin normalizes the expression of JAK/STAT signaling pathway to exert anti-diabetic, renoprotective, and neuroprotective impacts. At the present review, we provide a comprehensive discussion about the effect of curcumin on JAK/STAT signaling pathway to direct further studies in this field.

The roles of curcumin in regulating the tumor immunosuppressive microenvironment

Cancer is a harmful threat to human health. In addition to surgery, a variety of anticancer drugs are increasingly used in cancer therapy; however, despite the developments in multimodality treatment, the morbidity and mortality of patients with cancer patients are on the increase. The tumor-specific immunosuppressive microenvironment serves an important function in tumor tolerance and escape from immune surveillance leading to tumor progression. Therefore, identifying new drugs or foods that can enhance the tumor immune response is critical to develop improved cancer prevention methods and treatment. Curcumin, a polyphenolic compound extracted from ginger, has been shown to effectively inhibit tumor growth, proliferation, invasion, metastasis and angiogenesis in a variety of tumors. Recent studies have also indicated that curcumin can modulate the tumor immune response and remodel the tumor immunosuppressive microenvironment, indicating its potential in the immunotherapy of cancer. In this review, a brief introduction to the effects of curcumin on the tumor immune response and tumor immune microenvironment is provided and recent clinical trials investigating the potential of curcumin in cancer therapy are discussed.

Potential of Curcumin in Skin Disorders

Curcumin is a compound isolated from turmeric, a plant known for its medicinal use. Recently, there is a growing interest in the medical community in identifying novel, low-cost, safe molecules that may be used in the treatment of inflammatory and neoplastic diseases. An increasing amount of evidence suggests that curcumin may represent an effective agent in the treatment of several skin conditions. We examined the most relevant in vitro and in vivo studies published to date regarding the use of curcumin in inflammatory, neoplastic, and infectious skin diseases, providing information on its bioavailability and safety profile. Moreover, we performed a computational analysis about curcumin's interaction towards the major enzymatic targets identified in the literature. Our results suggest that curcumin may represent a low-cost, well-tolerated, effective agent in the treatment of skin diseases. However, bypass of limitations of its in vivo use (low oral bioavailability, metabolism) is essential in order to conduct larger clinical trials that could confirm these observations. The possible use of curcumin in combination with traditional drugs and the formulations of novel delivery systems represent a very promising field for future applicative research.

Unraveling the molecular mechanisms and the potential chemopreventive/therapeutic properties of natural compounds in melanoma

Melanoma is the most fatal form of skin cancer. Current therapeutic approaches include surgical resection, chemotherapy, targeted therapy and immunotherapy. However, these treatment strategies are associated with development of drug resistance and severe side effects. In recent years, natural compounds have also been extensively studied for their anti-melanoma effects, including tumor growth inhibition, apoptosis induction, angiogenesis and metastasis suppression and cancer stem cell elimination. Moreover, a considerable number of studies reported the synergistic activity of phytochemicals and standard anti-melanoma agents, as well as the enhanced effectiveness of their synthetic derivatives and novel formulations. However, clinical data confirming these promising effects in patients are still scanty. This review emphasizes the anti-tumor mechanisms and potential application of the most studied natural products for melanoma prevention and treatment.

Targeting Immune-Related Molecules in Cancer Therapy: A Comprehensive In Vitro Analysis on Patient-Derived Tumor Models

This study investigated the impact of immune-related pathway inhibition, among them indolamine 2,3-dioxygenase (IDO), alone and together with immune cells on growth and viability of colorectal cancer (CRC) cells. A panel of patient-derived CRC cell lines with different molecular characteristics (CpG island methylator phenotype, chromosomal, and microsatellite instability) was included. Initial phenotyping of CRC cell lines (n=17) revealed high abundance of immunosuppressive checkpoint-molecules in general, but an individual profile for IDO. Presence of immune-related molecules was independent of the molecular subtype. Selective treatment of CRC cell lines showing high or low IDO expression (n=2 cell lines each) was performed with single agents and combinations of Indoximod, Curcumin, and Gemcitabine with and without the addition of peripheral blood lymphocytes (PBL) in an allogeneic setting. All substances affected CRC cell growth in a cell line specific manner. The combination of Curcumin and Gemcitabine proved to be most effective in tumor cell elimination. Functional read-out analyses identified cellular senescence, after both single and combined treatment. Curcumin alone exerted strong cytotoxic effects by inducing early and late apoptosis. Necrosis was not detectable at all. Addition of lymphocytes generally boosted antitumoral effects of all IDO-inhibitors, with up to 80 % cytotoxicity for the Curcumin treatment. Here, no obvious differences became apparent between individual cell lines. Combined application of Curcumin and low-dose chemotherapy is a promising strategy to kill tumor target cells and to stimulate antitumoral immune responses.

Identification of candidate biomarkers associated with apoptosis in melanosis coli: GNG5, LPAR3, MAPK8, and PSMC6

Purpose: Melanosis coli (MC) is a disorder of pigmentation of the wall of the colon, often identified at the time of colonoscopy. The aim of the present study is to identify candidate biomarkers for MC. Methods: The transcriptome data for MC (GSE78933) with five MC tissues and five corresponding normal tissues is obtained from the NCBI Gene Expression Omnibus (GEO) database. R/Bioconductor package limma was used to screen differently expressed genes (DEGs). ClueGO of cytoscape was applied for Gene Ontology (GO) functional and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway enrichment. Based on STRING V10 database, protein–protein interaction (PPI) network was constructed. The pathological tissue and normal tissue from 23 MC patients and 23 controls were collected, respectively. The relative expression of hub nodes was detected by qRT-PCR and Western blot. For regulating the expression of these genes, overexpression vector was constructed or siRNA transfection was used. Finally, apoptosis was detected by flow cytometry. Results: Total 1342 DEGs were screened, including 786 up-regulated and 556 down-regulated genes. These genes were mainly enriched in stimulatory C-type lectin receptor signaling pathway, polysaccharide biosynthetic process, intracellular, and oxidative phosphorylation. PPI network was then constructed with 426 DEGs and 895 interactions. Thereinto, G-protein subunit γ 5 (GNG5), lysophosphatidic acid receptor 3 (LPAR3), mitogen-activated protein kinase 8 (MAPK8), NHP2L1, proteasome 26S subunit, ATPase 6 (PSMC6), and phosphatidylinositol-4,5-bisphosphate 3-kinase catalytic subunit β (PIK3CB) were hub nodes with higher degree. RT-PCR and Western blot results showed that GNG5, LPAR3, MAPK8, and PSMC6 were differently expressed with significance. The expression of these screened genes is also related with cell apoptosis. Conclusion: GNG5, LPAR3, MAPK8, and PSMC6 might be candidate biomarkers associated with apoptosis in MC.

Exploring major signaling cascades in melanomagenesis: a rationale route for targetted skin cancer therapy

Although most melanoma cases may be treated by surgical intervention upon early diagnosis, a significant portion of patients can still be refractory, presenting low survival rates within 5 years after the discovery of the illness. As a hallmark, melanomas are highly prone to evolve into metastatic sites. Moreover, melanoma tumors are highly resistant to most available drug therapies and their incidence have increased over the years, therefore leading to public health concerns about the development of novel therapies. Therefore, researches are getting deeper in unveiling the mechanisms by which melanoma initiation can be triggered and sustained. In this context, important progress has been achieved regarding the roles and the impact of cellular signaling pathways in melanoma. This knowledge has provided tools for the development of therapies based on the intervention of signal(s) promoted by these cascades. In this review, we summarize the importance of major signaling pathways (mitogen-activated protein kinase (MAPK), phosphoinositide 3-kinase (PI3K)-Akt, Wnt, nuclear factor κ-light-chain-enhancer of activated B cell (NF-κB), Janus kinase (JAK)-signal transducer and activator of transcription (STAT), transforming growth factor β (TGF-β) and Notch) in skin homeostasis and melanoma progression. Available and developing melanoma therapies interfering with these signaling cascades are further discussed.

The enhanced effect of tetrahydrocurcumin on radiosensitivity of glioma cells

Objectives

To evaluate the effects of tetrahydrocurcumin (THC) on the radiosensitivity of glioma cells and the possible molecular mechanism.

Methods

MTT assay, colony forming and wound healing assays were performed to detect the proliferation, radiosensitivity and migration of cells with various treatments. Cell apoptosis, cell cycle and GHS level were determined for exploring potent sensitization mechanism of THC. Meanwhile, protein expressions of cyclin D1 and PCNA were also measured. Furthermore, both orthotopic C6 mouse models and C6 subcutaneously grafted mouse models were established to test the tumour inhibitory effects of combined treatment in vivo.

Key findings

Cells treated with combined THC and radiation demonstrated lower cell viability and higher apoptosis rate as compared to radiation group. Moreover, the intracellular GSH was also decreased in the THC co-treated C6 cells. More importantly, combinatorial treatment group significantly induced G0/G1 cell cycle arrest and a decrease in the S phase cell through the down-regulation of cyclin D1 and PCNA. The in-vivo therapeutic efficacy assay indicated that the growth of tumour was greatly inhibited in combinatorial group.

Conclusions

Tetrahydrocurcumin can synergistically enhance the radiosensitivity of glioma cells by inhibiting the expressions of cyclin D1 and PCNA.

Curcumin and Melanoma: From Chemistry to Medicine

Melanoma is the most deadly form of skin cancer, with about 48,000 deaths each year worldwide. Growing evidence suggests that individual nutrients or dietary patterns might have important roles in the prevention of melanoma. Considering that melanoma is a potentially life-threatening cancer, novel protective and adjuvant treatments are needed to improve its prognosis. Curcumin is a bioactive substance extracted from rhizome of Curcuma longa L. Its global market is expected to grow in the next few years, especially in the pharmaceutical industry, due to its numerous physiological and pharmacological properties. For this review, we collected the available data on the protective and therapeutic role of curcumin against melanoma. We also discuss the chemistry, dietary sources, bioavailability, and metabolism of curcumin, and the mechanisms of action of its potential anticancer effects at the molecular level. Current challenges and future directions for research are also critically discussed.

Co-Delivery of Curcumin and Chrysin by Polymeric Nanoparticles Inhibit Synergistically Growth and hTERT Gene Expression in Human Colorectal Cancer Cells

Nanoparticle (NP)-based combinational chemotherapy has been proposed as a potent approach for improving intracellular drug concentrations and attaining synergistic effects in colorectal cancer therapy. Here, two well-known herbal substances, Curcumin (Cur) and Chrysin (Chr), were co-encapsulated in PEGylated PLGA NPs and investigated their synergistic inhibitory effect against Caco-2 cancer cells. Characterization of nanoformulated drugs was determined using DLS, FTIR, TEM, and SEM. Drug release study was performed using dialysis method. MTT and real-time PCR assays were applied to evaluate the cytotoxic effects of free and nano-encapsulated drugs on expression level of hTERT in Caco-2 cells. The results showed that free drugs and nano-formulations exhibited a dose-dependent cytotoxicity against Caco-2 cells and especially, Cur-Chr-PLGA/PEG NPs had more synergistic antiproliferative effect and significantly arrested the growth of cancer cells than the other groups (P < 0.05). Real-time PCR results revealed that Cur, Chr, and combination of Cur-Chr in free and encapsulated forms inhibited hTERT gene expression. Also, it was found that Cur-Chr-PLGA/PEG NPs than free combination forms could further decline hTERT expression in all concentration (P < 0.05). In summary, our study represents the first report of nano-combinational application of the natural herbal substances with a one-step fabricated codelivery system for effective colorectal cancer combinational chemotherapy.

Bisdemethoxycurcumin in combination with α-PD-L1 antibody boosts immune response against bladder cancer

Curcumin was recently discovered to strengthen immune response through multiple mechanisms. Cytotoxic CD8⁺ T-cells play a critical role in modulating anticancer immune response, but is severely restricted by T-cell exhaustion. Bladder carcinomas express PD-L1 and can abrogate CD8⁺ T-cell response. Thus, we hypothesized that bisdemethoxycurcumin, a natural dimethoxy derivative of curcumin, may provide a favorable environment for T-cell response against bladder cancer when used in combination with α-PD-L1 antibody. Immunocompetent C56BL/6 mouse models bearing subcutaneous or lung metastasized MB79 bladder cancer were established to validate this conjecture. We found that bisdemethoxycurcumin significantly increased intratumoral CD8⁺ T-cell infiltration, elevated the level of IFN-γ in the blood, and decreased the number of intratumoral myeloid-derived suppressor cells. Furthermore, α-PD-L1 antibody protected these amplified CD8⁺ T-cells from exhaustion, and therefore facilitated the secretion of IFN-γ, granzyme B, and perforin through these CD8⁺ T-cells. As a result, this combination treatment strategy significantly prolonged survival of intraperitoneal metastasized bladder cancer bearing mice, suggesting that bisdemethoxycurcumin in combination with α-PD-L1 antibody may be promising for bladder cancer patients.

STAT3 targeting by polyphenols: Novel therapeutic strategy for melanoma

Melanoma or malignant melanocytes appear with the low incidence rate, but very high mortality rate worldwide. Epidemiological studies suggest that polyphenolic compounds contribute for prevention or treatment of several cancers particularly melanoma. Such findings motivate to dig out novel therapeutic strategies against melanoma, including research toward the development of new chemotherapeutic and biologic agents that can target the tumor cells by different mechanisms. Recently, it has been found that signal transducer and activator of transcription 3 (STAT3) is activated in many cancer cases surprisingly. Different evidences supply the aspect that STAT3 activation plays a vital role in the metastasis, including proliferation of cells, survival, invasion, migration, and angiogenesis. This significant feature plays a vital role in various cellular processes, such as cell proliferation and survival. Here, we reviewed the mechanisms of the STAT3 pathway regulation and their role in promoting melanoma. Also, we have evaluated the emerging data on polyphenols (PPs) specifically their contribution in melanoma therapies with an emphasis on their regulatory/inhibitory actions in relation to STAT3 pathway and current progress in the development of phytochemical therapeutic techniques. An understanding of targeting STAT3 by PPs brings an opportunity to melanoma therapy. © 2016 BioFactors, 43(3):347-370, 2017.

Immunosuppressive Effects of Natural α,β-Unsaturated Carbonyl-Based Compounds, and Their Analogs and Derivatives, on Immune Cells: A Review

The immune system is complex and pervasive as it functions to prevent or limit infections in the human body. In a healthy organism, the immune system and the redox balance of immune cells maintain homeostasis within the body. The failure to maintain the balance may lead to impaired immune response and either over activity or abnormally low activity of the immune cells resulting in autoimmune or immune deficiency diseases. Compounds containing α,β-unsaturated carbonyl-based moieties are often reactive. The reactivity of these groups is responsible for their diverse pharmacological activities, and the most important and widely studied include the natural compounds curcumin, chalcone, and zerumbone. Numerous studies have revealed the mainly immunosuppressive and anti-inflammatory activities of the aforesaid compounds. This review highlights the specific immunosuppressive effects of these natural α,β-unsaturated carbonyl-based compounds, and their analogs and derivatives on different types of immune cells of the innate (granulocytes, monocytes, macrophages, and dendritic cells) and adaptive (T cells, B cells, and natural killer cells) immune systems. The inhibitory effects of these compounds have been comprehensively studied on neutrophils, monocytes and macrophages but their effects on T cells, B cells, natural killer cells, and dendritic cells have not been well investigated. It is of paramount importance to continue generating experimental data on the mechanisms of action of α,β-unsaturated carbonyl-based compounds on immune cells to provide useful information for ensuing research to discover new immunomodulating agents.

Curcumin: A new candidate for melanoma therapy?

Melanoma remains among the most lethal cancers and, in spite of great attempts that have been made to increase the life span of patients with metastatic disease, durable and complete remissions are rare. Plants and plant extracts have long been used to treat a variety of human conditions; however, in many cases, effective doses of herbal remedies are associated with serious adverse effects. Curcumin is a natural polyphenol that shows a variety of pharmacological activities including anti-cancer effects, and only minimal adverse effects have been reported for this phytochemical. The anti-cancer effects of curcumin are the result of its anti-angiogenic, pro-apoptotic and immunomodulatory properties. At the molecular and cellular level, curcumin can blunt epithelial-to-mesenchymal transition and affect many targets that are involved in melanoma initiation and progression (e.g., BCl2, MAPKS, p21 and some microRNAs). However, curcumin has a low oral bioavailability that may limit its maximal benefits. The emergence of tailored formulations of curcumin and new delivery systems such as nanoparticles, liposomes, micelles and phospholipid complexes has led to the enhancement of curcumin bioavailability. Although in vitro and in vivo studies have demonstrated that curcumin and its analogues can be used as novel therapeutic agents in melanoma, curcumin has not yet been tested against melanoma in clinical practice. In this review, we summarized reported anti-melanoma effects of curcumin as well as studies on new curcumin formulations and delivery systems that show increased bioavailability. Such tailored delivery systems could pave the way for enhancement of the anti-melanoma effects of curcumin.

Pyridine analogues of curcumin exhibit high activity for inhibiting CWR-22Rv1 human prostate cancer cell growth and androgen receptor activation

The concentrations required for curcumin to exert its anticancer activity (IC₅₀, 20 µM) are difficult to achieve in the blood plasma of patients, due to the low bioavailability of the compound. Therefore, much effort has been devoted to the development of curcumin analogues that exhibit stronger anticancer activity and a lower IC₅₀ than curcumin. The present study investigated twelve pyridine analogues of curcumin, labeled as groups AN, BN, EN and FN, to determine their effects in CWR-22Rv1 human prostate cancer cells. The inhibitory effects of these compounds on testosterone (TT)-induced androgen receptor (AR) activity was determined by performing an AR-linked luciferase assay and by TT-induced expression of prostate-specific antigen. The results of the current study suggested that the FN group of analogues had the strongest inhibitory effect of growth on CWR-22Rv1 cultured cells, and were the most potent inhibitor of AR activity compared with curcumin, and the AN, BN and EN analogues. Thus, the results of the present study indicate the inhibition of the AR pathways as a potential mechanism for the anticancer effect of curcumin analogues in human prostate cancer cells. Furthermore, curcumin analogues with pyridine as a distal ring and tetrahydrothiopyran-4-one as a linker may be good candidates for the development of novel drugs for the treatment of prostate cancer, by targeting the AR signaling pathway.

Curcuminoids and ω-3 fatty acids with anti-oxidants potentiate cytotoxicity of natural killer cells against pancreatic ductal adenocarcinoma cells and inhibit interferon γ production

Pancreatic cancer has a poor prognosis attributed in part to immune suppression and deactivation of natural killer (NK) cells. Curcuminoids have a potential for improving the therapy of pancreatic cancer given promising results in cancer models and a clinical trial, but their oral absorption is limited. Our objective in this study is to show curcuminoid anti-oncogenic effects alone and together with human NK cells. We tested curcuminoids in an emulsion of ω-3 fatty acids and anti-oxidants (“Smartfish”) regarding their direct cytocidal effect and enhancement of the cytocidal activity of NK cells in pancreatic ductal adenocarcinoma (PDAC) cells (Mia Paca 2 and L3.6). Curcuminoids (at ≥10 μM) with ω-3 fatty acids and anti-oxidants or with the lipidic mediator resolvin D1 (RvD1) (26 nM) induced high caspase-3 activity in PDAC cells. Importantly, curcuminoids with ω-3 fatty acids and anti-oxidants or with RvD1 significantly potentiated NK cell cytocidal function and protected them against degradation. In a co-culture of cancer cells with NK cells, interferon-γ (IFN-γ) production by NK cells was not altered by ω-3 fatty acids with anti-oxidants or by RvD1 but was inhibited by curcuminoids. The inhibition was not eliminated by ω-3 fatty acids or RvD1 but was relieved by removing curcuminoids after adding NK cells. In conclusion, curcuminoids with ω-3 fatty acids and anti-oxidants or with RvD1 have increased cytotoxic activity on PDAC cells alone and with NK cells. The effects of curcuminoids with ω-3 fatty acids and anti-oxidants on pancreatic cancer will be investigated in a mouse model with humanized immune system.

Glucose-6-phosphate dehydrogenase and NADPH oxidase 4 control STAT3 activity in melanoma cells through a pathway involving reactive oxygen species, c-SRC and SHP2

BACKGROUND

Glucose-6-phosphate dehydrogenase (G6PD) participates in glucose utilization by catalysing the first step of the pentose-phosphate pathway in mammalian cells. Previous studies have shown that changes in G6PD levels can promote tumor cell proliferation or apoptosis via the STAT3/5 pathway in a human melanoma xenograft model. G6PD cooperates with NADPH oxidase 4 (NOX4) in the cellular metabolism of reactive oxygen species (ROS) and in maintaining the intracellular redox state.

METHODS

In this study, the effect of G6PD or NOX4 silencing in the melanoma line A375 was examined in terms of redox state, proto-oncogene tyrosine-protein kinase Src (c-Src) and the tyrosine-specific protein phosphatase SHP2 expression as well as cell cycle progression.

RESULTS

The results demonstrate that: (1) Downregulation of cyclin D1 and CDK4 and up-regulation of p53 and p21 occurred in response to silencing of G6PD and NOX4 thus resulting in G1/S cell cycle arrest and inhibition of A375 cell proliferation. (2) The blockade of cell proliferation is primarily due to a reduced DNA-binding activity of STAT3. (3) The DNA-binding activity of STAT3 was regulated by the upstream factors, c-SRC and SHP2. Silencing of NOX4 in A375 cells inhibited c-SRC and SHP2 regulated STAT3 activity.

CONCLUSION

The data are consistent with a novel G6PD-NOX4-NADPH-ROS-c-SRC/SHP2 pathway controlling STAT3 activity in A375 melanoma cells.

Curcumin and omega-3 fatty acids enhance NK cell-induced apoptosis of pancreatic cancer cells but curcumin inhibits interferon-γ production: benefits of omega-3 with curcumin against cancer

STAT-3 and STAT-1 signaling have opposite effects in oncogenesis with STAT-3 acting as an oncogene and STAT-1 exerting anti-oncogenic activities through interferon-γ and interferon-α. The cytokine IL-6 promotes oncogenesis by stimulation of NFκB and STAT-3 signaling. Curcuminoids have bi-functional effects by blocking NFκB anti-apoptotic signaling but also blocking anti-oncogenic STAT-1 signaling and interferon-γ production. In our recent study (unpublished work [1]) in pancreatic cancer cell cultures, curcuminoids enhanced cancer cell apoptosis both directly and by potentiating natural killer (NK) cell cytotoxic function. The cytotoxic effects of curcuminoids were increased by incubation of cancer cells and NK cells in an emulsion with omega-3 fatty acids and antioxidants (Smartfish), which enhanced cancer cell apoptosis and protected NK cells against degradation. However, as also shown by others, curcuminoids blocked interferon-γ production by NK cells. The combined use of curcuminoids and omega-3 in cancer immunotherapy will require deeper understanding of their in vivo interactions with the immune system.

The multifaceted role of curcumin in cancer prevention and treatment

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

Targeting drivers of melanoma with synthetic small molecules and phytochemicals

Melanoma is the least common form of skin cancer, but it is responsible for the majority of skin cancer deaths. Traditional therapeutics and immunomodulatory agents have not shown much efficacy against metastatic melanoma. Agents that target the RAS/RAF/MEK/ERK (MAPK) signaling pathway - the BRAF inhibitors vemurafenib and dabrafenib, and the MEK1/2 inhibitor trametinib - have increased survival in patients with metastatic melanoma. Further, the combination of dabrafenib and trametinib has been shown to be superior to single agent therapy for the treatment of metastatic melanoma. However, resistance to these agents develops rapidly. Studies of additional agents and combinations targeting the MAPK, PI3K/AKT/mTOR (PI3K), c-kit, and other signaling pathways are currently underway. Furthermore, studies of phytochemicals have yielded promising results against proliferation, survival, invasion, and metastasis by targeting signaling pathways with established roles in melanomagenesis. The relatively low toxicities of phytochemicals make their adjuvant use an attractive treatment option. The need for improved efficacy of current melanoma treatments calls for further investigation of each of these strategies. In this review, we will discuss synthetic small molecule inhibitors, combined therapies and current progress in the development of phytochemical therapies.

Magnetic core-shell nanocapsules with dual-targeting capabilities and co-delivery of multiple drugs to treat brain gliomas

Lactoferrin (Lf)-tethered magnetic double emulsion nanocapsules (Lf-MDCs) are assembled from polyvinyl alcohol (PVA), polyacrylic acid (PAA), and iron oxide (IO) nanoparticles. The core-shell nanostructure of the Lf-MDCs (particle diameters from 100 to 150 nm) can simultaneously accommodate a hydrophilic drug, doxorubicin (Dox), and a hydrophobic drug, curcumin (Cur), in the core and shell, respectively, of the nanocapsules for an efficient drug delivery system. The release patterns of the two drugs can be regulated by manipulating the surface charges and drug-loading ratios, providing the capability for a stepwise adjuvant release to treat cancer cells. The results demonstrate that the dual (Dox+Cur)-drug-loaded nanocapsule can be effectively delivered into RG2 glioma cells to enhance the cytotoxicity against the cells through a synergistic effect. The combined targeting, i.e., magnetic guidance and incorporation of Lf ligands, of these Lf-MDCs results in significantly elevated cellular uptake in the RG2 cells that overexpress the Lf receptor. Interestingly, an intravenous injection of the co-delivered chemotherapeutics follows by magnetic targeting in brain tumor-bearing mice not only achieve high accumulation at the targeted site but also more efficiently suppress cancer growth in vivo than does the delivery of either drug alone.

FLLL31, a derivative of curcumin, attenuates airway inflammation in a multi-allergen challenged mouse model

Signal transducer and activator of transcription protein 3 (STAT3), one of the major regulators of inflammation, plays multiple roles in cellular transcription, differentiation, proliferation, and survival in human diseases. Dysregulation of STAT3 is related to the severe airway inflammation associated with asthma. FLLL31 is a newly developed compound based on the herbal medicine curcumin, which specifically suppresses the activation of STAT3. However, the function of FLLL31 on inflammatory diseases, especially on the regulation of airway inflammation, has not been fully studied. In our prior investigations, we developed a mouse model that was challenged with a mixture of DRA allergens (including house dust mite, ragweed, and Aspergillums species) to mimic the severe airway inflammation observed in human patients. In this study, we performed a series of experiments on the inflammatory regulation activities of FLLL31 in both in vitro cultured cells and our in vivo DRA-challenged mouse model. Our results show that FLLL31 exhibits anti-inflammatory effects on macrophage activation, lymphocyte differentiation, and pro-inflammatory factor production. Importantly, FLLL31 significantly inhibited airway inflammation and recruitment of inflammatory cells in the DRA-challenged mouse model. Based on these results, we conclude that FLLL31 is a potential therapeutic agent that can be used against severe airway inflammation diseases.

The molecular basis for the pharmacokinetics and pharmacodynamics of curcumin and its metabolites in relation to cancer

This review addresses the oncopharmacological properties of curcumin at the molecular level. First, the interactions between curcumin and its molecular targets are addressed on the basis of curcumin's distinct chemical properties, which include H-bond donating and accepting capacity of the β-dicarbonyl moiety and the phenylic hydroxyl groups, H-bond accepting capacity of the methoxy ethers, multivalent metal and nonmetal cation binding properties, high partition coefficient, rotamerization around multiple C-C bonds, and the ability to act as a Michael acceptor. Next, the in vitro chemical stability of curcumin is elaborated in the context of its susceptibility to photochemical and chemical modification and degradation (e.g., alkaline hydrolysis). Specific modification and degradatory pathways are provided, which mainly entail radical-based intermediates, and the in vitro catabolites are identified. The implications of curcumin's (photo)chemical instability are addressed in light of pharmaceutical curcumin preparations, the use of curcumin analogues, and implementation of nanoparticulate drug delivery systems. Furthermore, the pharmacokinetics of curcumin and its most important degradation products are detailed in light of curcumin's poor bioavailability. Particular emphasis is placed on xenobiotic phase I and II metabolism as well as excretion of curcumin in the intestines (first pass), the liver (second pass), and other organs in addition to the pharmacokinetics of curcumin metabolites and their systemic clearance. Lastly, a summary is provided of the clinical pharmacodynamics of curcumin followed by a detailed account of curcumin's direct molecular targets, whereby the phenotypical/biological changes induced in cancer cells upon completion of the curcumin-triggered signaling cascade(s) are addressed in the framework of the hallmarks of cancer. The direct molecular targets include the ErbB family of receptors, protein kinase C, enzymes involved in prostaglandin synthesis, vitamin D receptor, and DNA.

Molecular changes induced by the curcumin analogue D6 in human melanoma cells

BACKGROUND

In a previous report, we described the in vitro and in vivo antiproliferative and proapoptotic activity of a hydroxylated biphenyl (D6), a structural analogue of curcumin, on malignant melanoma and neuroblastoma tumours. In this paper, we investigated the molecular changes induced by such a compound, underlying cell growth arrest and apoptosis in melanoma cells.

RESULTS

To shed light on the mechanisms of action of D6, we firstly demonstrated its quick cellular uptake and subsequent block of cell cycle in G2/M phase transition. A gene expression profile analysis of D6-treated melanoma cells and fibroblasts was then carried out on high density microarrays, to assess gene expression changes induced by this compound. The expression profile study evidenced both an induction of stress response pathways and a modulation of cell growth regulation mechanisms. In particular, our data suggest that the antiproliferative and proapoptotic activities of D6 in melanoma could be partially driven by up-regulation of the p53 signalling pathways as well as by down-regulation of the PI3K/Akt and NF-kB pathways. Modulation of gene expression due to D6 treatment was verified by western blot analysis for single proteins of interest, confirming the results from the gene expression profile analysis.

CONCLUSIONS

Our findings contribute to the understanding of the mechanisms of action of D6, through a comprehensive description of the molecular changes induced by this compound at the gene expression level, in agreement with the previously reported anti-tumour effects on melanoma cells.

Bcl-2 family proteins and cytoskeleton changes involved in DM-1 cytotoxic effect on melanoma cells

Melanoma is one of the most aggressive types of skin cancer and its incidence rate is still increasing. All existing treatments are minimally effective. Consequently, new therapeutic agents for melanoma treatment should be developed. The DM-1 compound is a curcumin analog that possesses several curcumin characteristics, such as antiproliferative, antitumor, and anti-metastatic properties. The aim of this study was to evaluate the different signaling pathways involved in the cytotoxic effect of DM-1 on melanoma cells. The apoptotic process and cytoskeletal changes were evaluated by immunoblotting and immunofluorescence, respectively, in melanoma cells. After DM-1 treatment, SK-MEL-5 melanoma cells showed actin filament disorganization with spicule formation throughout the cytoskeleton and significant reduction of focal adhesion as well as they were present only at cell extremities, conferring a poor connection between the cell and the substrate. Besides this, there was significant filopodium retraction and loss of typical cytoskeleton scaffold. These modifications contributed to cell detachment followed by cell death. Furthermore, DM-1-induced apoptosis was triggered by multiple Bcl-2 proteins involved in both the extrinsic and the intrinsic apoptotic pathways. SK-MEL-5 cells showed a death mechanism mainly by Bcl-2/Bax ratio decrease, whereas A375 cells presented apoptosis induction by Mcl-1 and Bcl-xL downregulation. In SK-MEL-5 and A375 melanoma cells, there was a significant increase in the active form of caspase 9, and the inactive form of the effector caspase 3 was decreased in both cell lines. Expression of cleaved poly ADP ribose polymerase was increased after DM-1 treatment in these melanoma cell lines, demonstrating that the apoptotic process occurred. Altogether, these data elucidate the cellular and molecular mechanisms involved in the cytotoxicity induced by the antitumor agent DM-1 in melanoma cells.

Synthesis of novel quinoline-2-one based chalcones of potential anti-tumor activity

Novel quinoline-2-one based chalcones were synthesized from a Claisen-Schmidt condensation by using the couple KOH/1,4-dioxane as reaction medium. A relatively stable aldol was isolated and identified as the intermediate species in the formation of the target chalcones. Nine of the obtained compounds were in vitro screened by the US National Cancer Institute (NCI) for their ability to inhibit 60 different human tumor cell lines. Products 16c, 16d, 16h and 27 exhibited the highest activity, being compound 27 the most active, displaying remarkable activity against 50 human tumor cell lines, thirteen of them with GI(50) values ≤1.0 μM, being the HCT-116 (Colon, GI(50) = 0.131 μM) and LOX IMVI (Melanoma, GI(50) = 0.134 μM) the most sensitive strains. Compound 27 was referred to in vivo acute toxicity and hollow fiber assay by the Biological Evaluation Committee of the NCI. The acute toxicity study indicated that compound 27 was well tolerated intraperitoneally (150 mg/kg/dose) by athymic nude mice. This compound may possibly be used as lead compound for developing new anticancer agents.

Structurally modified curcumin analogs inhibit STAT3 phosphorylation and promote apoptosis of human renal cell carcinoma and melanoma cell lines

The Janus kinase-2 (Jak2)-signal transducer and activator of transcription-3 (STAT3) pathway is critical for promoting an oncogenic and metastatic phenotype in several types of cancer including renal cell carcinoma (RCC) and melanoma. This study describes two small molecule inhibitors of the Jak2-STAT3 pathway, FLLL32 and its more soluble analog, FLLL62. These compounds are structurally distinct curcumin analogs that bind selectively to the SH2 domain of STAT3 to inhibit its phosphorylation and dimerization. We hypothesized that FLLL32 and FLLL62 would induce apoptosis in RCC and melanoma cells and display specificity for the Jak2-STAT3 pathway. FLLL32 and FLLL62 could inhibit STAT3 dimerization in vitro. These compounds reduced basal STAT3 phosphorylation (pSTAT3), and induced apoptosis in four separate human RCC cell lines and in human melanoma cell lines as determined by Annexin V/PI staining. Apoptosis was also confirmed by immunoblot analysis of caspase-3 processing and PARP cleavage. Pre-treatment of RCC and melanoma cell lines with FLLL32/62 did not inhibit IFN-γ-induced pSTAT1. In contrast to FLLL32, curcumin and FLLL62 reduced downstream STAT1-mediated gene expression of IRF1 as determined by Real Time PCR. FLLL32 and FLLL62 significantly reduced secretion of VEGF from RCC cell lines in a dose-dependent manner as determined by ELISA. Finally, each of these compounds inhibited in vitro generation of myeloid-derived suppressor cells. These data support further investigation of FLLL32 and FLLL62 as lead compounds for STAT3 inhibition in RCC and melanoma.