Overexpression of the ATP binding cassette gene ABCA1 determines resistance to Curcumin in M14 melanoma cells

Enhancement of gemcitabine sensitivity in intrahepatic cholangiocarcinoma through Saikosaponin-a mediated modulation of the p-AKT/BCL-6/ABCA1 axis

BACKGROUND

Intrahepatic cholangiocarcinoma (ICC) remains a significant challenge in cancer therapy, especially due to its resistance to established treatments like Gemcitabine, necessitating novel therapeutic approaches.

METHODS

This study utilized Gemcitabine-resistant cell lines, patient-derived organotypic tumor spheroids (PDOTs), and patient-derived xenografts (PDX) to evaluate the effects of Saikosaponin-a (SSA) on ICC cellular proliferation, migration, apoptosis, and its potential synergistic interaction with Gemcitabine. Techniques such as transcriptome sequencing, Luciferase reporter assays, and molecular docking were employed to unravel the molecular mechanisms.

RESULTS

SSA exhibited antitumor effects in both in vitro and PDX models, indicating its considerable potential for ICC treatment. SSA markedly inhibited ICC progression by reducing cellular proliferation, enhancing apoptosis, and decreasing migration and invasion. Crucially, it augmented Gemcitabine's efficacy by targeting the p-AKT/BCL6/ABCA1 signaling pathway. This modulation led to the downregulation of p-AKT and suppression of BCL6 transcriptional activity, ultimately reducing ABCA1 expression and enhancing chemosensitivity to Gemcitabine. Additionally, ABCA1 was validated as a predictive biomarker for drug resistance, with a direct correlation between ABCA1 expression levels and the IC50 values of various small molecule drugs in ICC gene profiles.

CONCLUSION

This study highlights the synergistic potential of SSA combined with Gemcitabine in enhancing therapeutic efficacy against ICC and identifies ABCA1 as a key biomarker for drug responsiveness. Furthermore, the introduction of the novel PDOTs microfluidic model provides enhanced insights into ICC research. This combination strategy may provide a novel approach to overcoming treatment challenges in ICC.

Targeting ABCA1 via Extracellular Vesicle-Encapsulated Staurosporine as a Therapeutic Strategy to Enhance Radiosensitivity

Cancer stem cells (CSCs) are essential for tumor initiation, recurrence, metastasis, and resistance. However, targeting CSCs as a therapeutic approach remains challenging. Here, a stemness signature based on 22-gene is developed to predict prognosis in esophageal squamous cell carcinoma (ESCC). Staurosporine (STS) is identified as a radioresistance suppressor by high-throughput screening of a library of 2131 natural compounds, leading to dramatically improved radiotherapy efficacy in subcutaneous tumor models. Mechanistically, STS inhibits cell proliferation through the mTOR/AKT signaling pathway and suppressed stemness by targeting ATP-binding cassette A1 (ABCA1), which is transcriptionally regulated by liver X receptor alpha (LXRα). STS can selectively bind to the nucleotide-binding domain (NBD) of ABCA1 and compete for ATP, blocking ABCA1-mediated drug efflux and facilitating intracellular accumulation of STS. Considering the cytotoxicity of STS, an extracellular vesicle-encapsulated STS system (EV-STS) is established for effective STS delivery. EV-STS shows remarkable tumor growth inhibition, even at half the dose of STS, with superior safety and efficacy. These findings indicate that ABCA1 may serve as a predictor of response to neoadjuvant chemotherapy and/or radiotherapy in ESCC patients. EV-STS has shown improved antitumor efficacy and low systemic toxicity, offering a promising therapeutic approach for ESCC.

Integrated analysis of single-cell and bulk RNA-sequencing reveals the poor prognostic value of ABCA1 in gastric adenocarcinoma

PURPOSE

ATP-binding cassette A1 (ABCA1) is a potential prognostic marker for various tumor types. However, the biological effects and prognostic value of ABCA1 in gastric adenocarcinoma (GAC) remain unknown.

METHODS

GAC-associated single-cell RNA and bulk RNA-sequencing (bulk-seq) data were obtained from the Gene Expression Omnibus and The Cancer Genome Atlas databases, respectively. The differential expression of ABCA1 between GAC and normal gastric tissues was analyzed based on the bulk-seq data. Additionally, the relationship between ABCA1 expression and various clinicopathological features was explored. Furthermore, Kaplan-Meier survival and Cox regression analyses were performed to establish the prognostic value of ABCA1. The relationships between ABCA1 expression and anti-tumor drug sensitivity and immune checkpoints were also explored. Finally, the biological functions of ABCA1 were evaluated at the single-cell level, and in vitro studies were performed to assess the effects of ABCA1 on GAC cell proliferation and invasion.

RESULTS

ABCA1 expression is significantly elevated in GAC samples compared with that in normal gastric tissues. Clinical features and survival analysis revealed that high ABCA1 expression is associated with poor clinical phenotypes and prognosis, whereas Cox analysis identified ABCA1 as an independent risk factor for patients with GAC. Furthermore, high ABCA1 expression suppresses sensitivity to various chemotherapeutic drugs, including cisplatin and mitomycin, while upregulating immune checkpoints. ABCA1-overexpressing macrophages are associated with adverse clinical phenotypes in GAC and express unique ligand-receptor pairs that drive GAC progression. In vitro, ABCA1-knockdown GAC cells exhibit significantly inhibited proliferative and invasive properties.

CONCLUSION

High ABCA1 expression promotes an adverse immune microenvironment and low survival rates in patients with GAC. Furthermore, ABCA1 and ABCA1-producing macrophages may serve as novel molecular targets in GAC treatment.

Current state of research on the clinical benefits of herbal medicines for non-life-threatening ailments

Herbal medicines are becoming increasingly popular among patients because they are well tolerated and do not exert severe side effects. Nevertheless, they receive little consideration in therapeutic settings. The present article reviews the current state of research on the clinical benefits of herbal medicines on five indication groups, psychosomatic disorders, gynecological complaints, gastrointestinal disorders, urinary and upper respiratory tract infections. The study search was based on the database PubMed and concentrated on herbal medicines legally approved in Europe. After applying defined inclusion and exclusion criteria, 141 articles were selected: 59 for psychosomatic disorders (100% randomized controlled trials; RCTs), 20 for gynecological complaints (56% RCTs), 19 for gastrointestinal disorders (68% RCTs), 16 for urinary tract infections (UTI, 63% RCTs) and 24 for upper respiratory tract infections (URTI) (79% RCTs). For the majority of the studies, therapeutic benefits were evaluated by patient reported outcome measures (PROs). For psychosomatic disorders, gynecological complaints and URTI more than 80% of the study outcomes were positive, whereas the clinical benefit of herbal medicines for the treatment of UTI and gastrointestinal disorders was lower with 55%. The critical appraisal of the articles shows that there is a lack of high-quality studies and, with regard to gastrointestinal disorders, the clinical benefits of herbal medicines as a stand-alone form of therapy are unclear. According to the current state of knowledge, scientific evidence has still to be improved to allow integration of herbal medicines into guidelines and standard treatment regimens for the indications reviewed here. In addition to clinical data, real world data and outcome measures can add significant value to pave the way for herbal medicines into future therapeutic applications.

Drug metabolism-related gene ABCA1 augments temozolomide chemoresistance and immune infiltration abundance of M2 macrophages in glioma

Gliomas are the most prevalent primary tumor in the central nervous system, with an abysmal 5-year survival rate and alarming mortality. The current standard management of glioma is maximum resection of tumors followed by postoperative chemotherapy with temozolomide (TMZ) or radiotherapy. Low chemosensitivity of TMZ in glioma treatment eventuates limited therapeutic efficacy or treatment failure. Hence, overcoming the resistance of glioma to TMZ is a pressing question. Our research centered on identifying the drug metabolism-related genes potentially involved in TMZ-treated resistance of glioma through several bioinformatics datasets and cell experiments. One efflux transporter, ATP-binding cassette transporter subfamily A1 (ABCA1), was discovered with an upregulated expression level and signaled poor clinical outcomes for glioma patients. The transcript level of ABCA1 significantly elevated across the TMZ-resistant glioma cells in contrast with non-resistant cells. Over-expressed ABCA1 restrained the drug activity of TMZ, and ABCA1 knockdown improved the treatment efficacy. Meanwhile, the results of molecular docking between ABCA1 protein and TMZ showed a high binding affinity. Additionally, co-expression and immunological analysis revealed that ABCA1 facilitates the immune infiltration of M2 macrophages in glioma, thereby stimulating tumor growth and aggravating the poor survival of patients. Altogether, we discovered that the ABCA1 transporter was involved in TMZ chemoresistance and the immune infiltration of M2 macrophages in glioma. Treatment with TMZ after ABCA1 knockdown enhances the chemosensitivity, suggesting that inhibition of ABCA1 may be a potential strategy for improving the therapeutic efficacy of gliomas.

Is cholesterol a risk factor for breast cancer incidence and outcome?

Cholesterol plays important roles in many physiological processes, including cell membrane structure and function, hormone synthesis, and the regulation of cellular homeostasis. The role of cholesterol in breast cancer is complex, and some studies have suggested that elevated cholesterol levels may be associated with an increased risk of developing breast cancer, while others have found no significant association. On the other hand, other studies have shown that, for total cholesterol and plasma HDL-associated cholesterol levels, there was inverse association with breast cancer risk. One possible mechanism by which cholesterol may contribute to breast cancer risk is as a key precursor of estrogen. Other potential mechanisms by which cholesterol may contribute to breast cancer risk include its role in inflammation and oxidative stress, which have been linked to cancer progression. Cholesterol has also been shown to play a role in signaling pathways regulating the growth and proliferation of cancer cells. In addition, recent studies have shown that cholesterol metabolism can generate tumor promoters such as cholesteryl esters, oncosterone, 27-hydroxycholesterol but also tumor suppressor metabolites such as dendrogenin A. This review summarizes some of the most important clinical studies that have evaluated the role of cholesterol or its derivatives in breast cancer. It also addresses the role of cholesterol and its derivatives at the cellular level.

Dietary Polyphenols, Microbiome, and Multiple Sclerosis: From Molecular Anti-Inflammatory and Neuroprotective Mechanisms to Clinical Evidence

Multiple sclerosis (MS) is a multifactorial, immune-mediated disease caused by complex gene-environment interactions. Dietary factors modulating the inflammatory status through the control of the metabolic and inflammatory pathways and the composition of commensal gut microbiota, are among the main environmental factors involved in the pathogenesis of MS. There is no etiological therapy for MS and the drugs currently used, often accompanied by major side effects, are represented by immunomodulatory substances capable of modifying the course of the disease. For this reason, nowadays, more attention is paid to alternative therapies with natural substances with anti-inflammatory and antioxidant effects, as adjuvants of classical therapies. Among natural substances with beneficial effects on human health, polyphenols are assuming an increasing interest due to their powerful antioxidant, anti-inflammatory, and neuroprotective effects. Beneficial properties of polyphenols on the CNS are achieved through direct effects depending on their ability to cross the blood-brain barrier and indirect effects exerted in part via interaction with the microbiota. The aim of this review is to examine the literature about the molecular mechanism underlying the protective effects of polyphenols in MS achieved by experiments conducted in vitro and in animal models of the disease. Significant data have been accumulated for resveratrol, curcumin, luteolin, quercetin, and hydroxytyrosol, and therefore we will focus on the results obtained with these polyphenols. Clinical evidence for the use of polyphenols as adjuvant therapy in MS is restricted to a smaller number of substances, mainly curcumin and epigallocatechin gallate. In the last part of the review, a clinical trial studying the effects of these polyphenols in MS patients will also be revised.

ABCA1-Mediated EMT Promotes Papillary Thyroid Cancer Malignancy through the ERK/Fra-1/ZEB1 Pathway

Papillary thyroid cancer (PTC) is the most prevalent histological type of thyroid cancer (TC) worldwide. Although tumor metastasis occurs in regional lymph nodes, distant metastasis (DM) may also occur. Radioactive iodine (RAI) therapy is an effective treatment for TC; however, resistance to RAI occurs in patients with DM. Therefore, in this study, we investigated the efficacy of DM-related biomarkers as therapeutic targets for PTC therapy. ABCA1 expression was higher in aggressive BCPAP cells than in other PTC cells in terms of migration and invasion capacity. The knockdown of ABCA1 substantially decreased the expression of the epithelial-mesenchymal transition (EMT) marker, N-cadherin, and EMT regulator (ZEB1), resulting in suppressed migration and invasion of BCPAP cells. ABCA1 knockdown also reduced ERK activity and Fra-1 expression, which correlated with the effects of an ERK inhibitor or siRNA-mediated inhibition of ERK or Fra-1 expression. Furthermore, ABCA1-knocked-down BCPAP cells suppressed cell migration and invasion by reducing Fra-1 recruitment to Zeb1 promoter; lung metastasis was not observed in mice injected with ABCA1-knocked-down cells. Overall, our findings suggest that ABCA1 regulates lung metastasis in TC cells.

ABCA1 Expression Is Upregulated in an EMT in Breast Cancer Cell Lines via MYC-Mediated De-Repression of Its Proximal Ebox Element

The ATP-Binding Cassette transporter A1 (ABCA1) reverse cholesterol transport channel has been associated with a number of phenotypes in breast cancer, including reduced proliferation and increased metastatic capacity. It is induced in an epithelial–mesenchymal transition (EMT), but little is known about how this occurs, and whether it is sufficient to promote metastatic phenotypes. To address these questions, we have deciphered the transcriptional regulation of ABCA1 across EMT states and found that it is repressed by MYC via an E-box element in its P1 alternative promoter. De-repression of the promoter by MYC knockdown leads to induction of ABCA1 expression. This indicates that ABCA1 expression is regulated in an EMT, revealing another link between ABCA1 and malignant phenotypes.

Antimetastatic Effects of Curcumin in Oral and Gastrointestinal Cancers

Gastrointestinal (GI) cancers are known as frequently occurred solid malignant tumors that can cause the high rate mortality in the world. Metastasis is a significant destructive feature of tumoral cells, which directly correlates with decreased prognosis and survival. Curcumin, which is found in turmeric, has been identified as a potent therapeutic natural bioactive compound (Curcuma longa). It has been traditionally applied for centuries to treat different diseases, and it has shown efficacy for its anticancer properties. Numerous studies have revealed that curcumin inhibits migration and metastasis of GI cancer cells by modulating various genes and proteins, i.e., growth factors, inflammatory cytokines and their receptors, different types of enzymes, caspases, cell adhesion molecules, and cell cycle proteins. Herein, we summarized the antimetastatic effects of curcumin in GI cancers, including pancreatic cancer, gastric cancer, colorectal cancer, oral cancer, and esophageal cancer.

Connecting Cholesterol Efflux Factors to Lung Cancer Biology and Therapeutics

Cholesterol is a foundational molecule of biology. There is a long-standing interest in understanding how cholesterol metabolism is intertwined with cancer biology. In this review, we focus on the known connections between lung cancer and molecules mediating cholesterol efflux. A major take-home lesson is that the roles of many cholesterol efflux factors remain underexplored. It is our hope that this article would motivate others to investigate how cholesterol efflux factors contribute to lung cancer biology.

A mean-field approach for modeling the propagation of perturbations in biochemical reaction networks

Often, the time evolution of a biochemical reaction network is crucial for determining the effects of combining multiple pharmaceuticals. Here we illustrate a mathematical framework for modeling the dominant temporal behaviour of a complicated molecular pathway or biochemical reaction network in response to an arbitrary perturbation, such as resulting from the administration of a therapeutic agent. The method enables the determination of the temporal evolution of a target protein as the perturbation propagates through its regulatory network. The mathematical approach is particularly useful when the experimental data that is available for characterizing or parameterizing the regulatory network is limited or incomplete. To illustrate the method, we consider the examples of the regulatory networks for the target proteins c-Myc and Chop, which play an important role in venetoclax resistance in acute myeloid leukemia. First we show how the networks that regulate each target protein can be reduced to a mean-field model by identifying the distinct effects that groups of proteins in the regulatory network have on the target protein. Then we show how limited protein-level data can be used to further simplify the mean-field model to pinpoint the dominant effects of the network perturbation on the target protein. This enables a further reduction in the number of parameters in the model. The result is an ordinary differential equation model that captures the temporal evolution of the expression of a target protein when one or more proteins in its regulatory network have been perturbed. Finally, we show how the dominant effects predicted by the mathematical model agree with RNA sequencing data for the regulatory proteins comprising the molecular network, despite the model not having a priori knowledge of this data. Thus, while the approach gives a simplified model for the expression of the target protein, it allows for the interpretation of the effects of the perturbation on the regulatory network itself. This method can be easily extended to sets of target proteins to model components of a larger systems biology model, and provides an approach for partially integrating RNA sequencing data and protein expression data. Moreover, it is a general approach that can be used to study drug effects on specific protein(s) in any disease or condition.

CCAAT/Enhancer-binding protein delta mediates glioma stem-like cell enrichment and ATP-binding cassette transporter ABCA1 activation for temozolomide resistance in glioblastoma

Glioblastoma (GBM) is the most aggressive brain tumor and relapses after chemo- or radiotherapy in a short time. The anticancer drug temozolamide (TMZ) is commonly used for GBM treatment, but glioma stem-like cells (GSCs) often lead to drug resistance and therapeutic failure. To date, the mechanism of GSC formation in TMZ-treated GBM remains largely unknown. CCAAT/Enhancer-binding protein delta (CEBPD) is an inflammation-responsive transcription factor and is proposed to be oncogenic in the context of drug resistance, prompting us to clarify its role in TMZ-resistant GBM. In this study, we first found that the CEBPD protein levels in GBM patients were significantly increased and further contributed to TMZ resistance by promoting GSC formation. Accordingly, the protein levels of stemness transcription factors, namely, SRY-box transcription factor 2 (SOX2), octamer-binding transcription factor 4 (OCT4), NANOG, and ATP-binding cassette subfamily A member 1 (ABCA1), were increased in GSCs and TMZ-treated GBM cells. Increased binding of CEBPD to promoter regions was observed in GSCs, indicating the direct regulation of these GSC-related genes by CEBPD. In addition, an ABCA1 inhibitor increased the caspase 3/7 activity of TMZ-treated GSCs, suggesting that TMZ efflux is controlled by ABCA1 activity and that the expression levels of the ABCA1 gene are an indicator of the efficiency of TMZ treatment. Together, we revealed the mechanism of CEBPD-mediated GSC drug resistance and proposed ABCA1 inhibition as a potential strategy for the treatment of TMZ-resistant GBM.

Role of hydrogen sulfide donors in cancer development and progression

In recent years, a vast number of potential cancer therapeutic targets have emerged. However, developing efficient and effective drugs for the targets is of major concern. Hydrogen sulfide (H2S), one of the three known gasotransmitters, is involved in the regulation of various cellular activities such as autophagy, apoptosis, migration, and proliferation. Low production of H2S has been identified in numerous cancer types. Treating cancer cells with H2S donors is the common experimental technique used to improve H2S levels; however, the outcome depends on the concentration/dose, time, cell type, and sometimes the drug used. Both natural and synthesized donors are available for this purpose, although their effects vary independently ranging from strong cancer suppressors to promoters. Nonetheless, numerous signaling pathways have been reported to be altered following the treatments with H2S donors which suggest their potential in cancer treatment. This review will analyze the potential of H2S donors in cancer therapy by summarizing key cellular processes and mechanisms involved.

MiR-200b-3p Functions as an Oncogene by Targeting ABCA1 in Lung Adenocarcinoma

Objective:

The aim of this study was to investigate the microRNA-200b-3p expression in lung adenocarcinoma and the possible functional associations of microRNA-200b-3p with cell proliferation, migration, and invasion.

Methods:

Quantitative real-time polymerase chain reaction was used to detect the expression of microRNA-200b-3p in lung adenocarcinoma samples and in the human lung adenocarcinoma cell lines A549 and H1299. A549 and H1299 cells were transfected with either a microRNA-200b-3p mimic or a negative control microRNA or either an empty vector or an adenosine triphosphate-binding cassette transporter A-1 overexpression vector. A Cell Counting Kit-8 assay was employed to assess the ability of cell proliferation. Transwell assays and transwell-Matrigel invasion assay were, respectively, utilized to assess the capacity of migration and invasion in A549 and H1299 cells.

Results:

The results showed that microRNA-200b-3p expression was significantly upregulated in tumor tissues compared with that in adjacent normal tissues. Overexpression of microRNA-200b-3p promoted lung adenocarcinoma cell proliferation and metastasis. Furthermore, adenosine triphosphate-binding cassette transporter A-1 was a direct target of microRNA-200b-3p, and this binding was verified by luciferase reporter analysis. Overexpression of adenosine triphosphate-binding cassette transporter A-1 obviously suppressed lung adenocarcinoma cell proliferation, migration, and invasion. Lung adenocarcinoma cell phenotypes induced by microRNA-200b-3p overexpression could be partially remitted by the co-overexpression of microRNA-200b-3p and adenosine triphosphate-binding cassette transporter A-1.

Conclusion:

This study first identified that microRNA-200b-3p is upregulated in lung adenocarcinoma cells and associated with cell proliferation and metastasis. MicroRNA-200b-3p promoted lung adenocarcinoma cell proliferation and metastasis by suppressing adenosine triphosphate-binding cassette transporter A-1. MicroRNA-200b-3p may function as a novel molecular marker and therapeutic target for lung adenocarcinoma treatment.

Role of de novo cholesterol synthesis enzymes in cancer

Despite extensive research in the cancer field, cancer remains one of the most prevalent diseases. There is an urgent need to identify specific targets that are safe and effective for the treatment of cancer. In recent years, cancer metabolism has come into the spotlight in cancer research. Lipid metabolism, especially cholesterol metabolism, plays a critical role in membrane synthesis as well as lipid signaling in cancer. This review focuses on the contribution of the de novo cholesterol synthesis pathway to tumorigenesis, cancer progression and metastasis. In conclusion, cholesterol metabolism could be an effective target for novel anticancer treatment.

Preventing Calpain Externalization by Reducing ABCA1 Activity with Probenecid Limits Melanoma Angiogenesis and Development

Calpains, intracellular proteases specifically inhibited by calpastatin, play a major role in neoangiogenesis involved in tumor invasiveness and metastasis. They are partly exteriorized via the ATP-binding cassette transporter A1(ABCA1) transporter, but the importance of this process in tumor growth is still unknown. The aim of our study was to investigate the role of extracellular calpains in a model of melanoma by blocking their extracellular activity or exteriorization. In the first approach, a B16-F10 model of melanoma was developed in transgenic mice expressing high extracellular levels of calpastatin. In these mice, tumor growth was inhibited by ∼ 3-fold compared with wild-type animals. In vitro cytotoxicity assays and in vivo tumor studies have demonstrated that this protection was associated with a defect in tumor neoangiogenesis. Similarly, in wild-type animals given probenecid to blunt ABCA1 activity, melanoma tumor growth was inhibited by ∼ 3-fold. Again, this response was associated with a defect in neoangiogenesis. In vitro studies confirmed that probenecid limited endothelial cell migration and capillary formation from vascular explants. The observed reduction in fibronectin cleavage under these conditions is potentially involved in the response. Collectively, these studies demonstrate that probenecid, by blunting ABCA1 activity and thereby calpain exteriorization, limits melanoma tumor neoangiogenesis and invasiveness.

Expression of LXR‑β, ABCA1 and ABCG1 in human triple‑negative breast cancer tissues

Previous studies have reported that liver X receptor (LXR), ATP-binding cassette sub-family G number 1 (ABCG1) and ATP-binding cassette transporter number 1 (ABCA1), which are associated with cholesterol metabolism, may be associated with the development and progression of breast cancer. The expression levels of LXR-β, ABCA1 and ABCG1 in triple-negative breast cancer (TNBC) tissues and in non-cancerous mammary tissues were observed by immunohistochemistry, quantum dot-based immunohistochemistry, western blot analysis and reverse transcription-quantitative polymerase chain reaction. The present study identified that the expression of ABCA1 in TNBC tissues was higher than that in non-cancerous mammary tissues. A high expression of ABCA1 in the TNBC tissues was significantly associated with the histological grade. However, no significant differences were identified between the expression levels of LXR-β and ABCG1 in the TNBC tissues compared with the non-cancerous mammary tissues. Therefore, the findings of this study suggest that ABCA1 is a specific marker for TNBC.

Therapeutic Effects of Curcumin-From Traditional Past to Present and Future Clinical Applications

The efficacy of the plant-derived polyphenol curcumin, in various aspects of health and wellbeing, are a matter of public interest. An internet search of the term “Curcumin” displays about 12 million hits. Among the multitudinous information presented on partly doubtful websites, there are reports attracting the reader with promises ranging from eternal youth to cures for incurable diseases. Unfortunately, many of these reports are not based on scientific evidence, but they feed the desideratum of the reader for a “miracle cure”. This circumstance makes it very difficult for researchers, whose work is scientifically sound and evidence is based on the therapeutic benefits (or side effects) of curcumin, to demarcate their results from sensational reports that circulate in the web and in other media. This is only one of many obstacles making it difficult to pave curcumin’s way into clinical application; others are its nonpatentability and low economic usability. A further impediment comes from scientists who never worked with curcumin or any other natural plant-derived compound in their own labs. They have never tested these compounds in any scientific assay, neither in vitro nor in vivo; however, they claim, in a sometimes polemic manner, that everything that has so far been published on curcumin’s molecular effects is based on artefacts. The here presented Special Issue comprises a collection of five scientifically sound articles and nine reviews reporting on the therapeutic benefits and the molecular mechanisms of curcumin or of chemically modified curcumin in various diseases ranging from malignant tumors to chronic diseases, microbial infection, and even neurodegenerative diseases. The excellent results of the scientific projects that underlie the five original papers give reason to hope that curcumin will be part of novel treatment strategies in the near future—either as monotherapy or in combination with other drugs or therapeutic applications.

The Stem Cell Phenotype of Aggressive Breast Cancer Cells

Aggressive cancer cells are characterized by their capacity to proliferate indefinitely and to propagate a heterogeneous tumor comprised of subpopulations with varying degrees of metastatic propensity and drug resistance properties. Particularly daunting is the challenge we face in the field of oncology of effectively targeting heterogeneous tumor cells expressing a variety of markers, especially those associated with a stem cell phenotype. This dilemma is especially relevant in breast cancer, where therapy is based on traditional classification schemes, including histological criteria, differentiation status, and classical receptor markers. However, not all patients respond in a similar manner to standard-of-care therapy, thereby necessitating the need to identify and evaluate novel biomarkers associated with the difficult-to-target stem cell phenotype and drug resistance. Findings related to the convergence of embryonic and tumorigenic signaling pathways have identified the embryonic morphogen Nodal as a promising new oncofetal target that is reactivated only in aggressive cancers, but not in normal tissues. The work presented in this paper confirms previous studies demonstrating the importance of Nodal as a cancer stem cell molecule associated with aggressive breast cancer, and advances the field by providing new findings showing that Nodal is not targeted by standard-of-care therapy in breast cancer patients. Most noteworthy is the linkage found between Nodal expression and the drug resistance marker ATP-binding cassette member 1 (ABCA1), which may provide new insights into developing combinatorial approaches to overcome drug resistance and disease recurrence.

RASSF1C regulates miR-33a and EMT marker gene expression in lung cancer cells

RASSF1C functions as an oncogene in lung cancer cells by stimulating proliferation and migration, and reducing apoptosis. Further, RASSF1C up-regulates important protein-coding and non-coding genes involved in lung cancer cell growth, including the stem cell self-renewal gene, piwil1, and small noncoding PIWI-interacting RNAs (piRNAs). In this article, we report the identification of microRNAs (miRNAs) that are modulated in lung cancer cells over-expressing RASSF1C. A lung cancer-specific miRNA PCR array screen was performed to identify RASSF1C target miRNA-coding genes using RNA isolated from the lung cancer cell line H1299 stably over-expressing RASSF1C and corresponding control. Several modulated miRNA genes were identified that are important in cancer cell proliferation and survival. Among the miRNAs down-regulated by RASSF1C is miRNA-33a-5p (miRNA-33a), which functions as a tumor suppressor in lung cancer cells. We validated that over-expression of RASSF1C down-regulates miR-33a expression and RASSF1C knockdown up-regulates miR-33a expression. We found that RASSF1C over-expression also increases β-catenin, vimentin, and snail protein levels in cells over-expressing miR-33a. In addition, we found that RASSF1C up-regulates the expression of ABCA1 mRNA which is a known target of miR-33a. Our findings suggest that RASSF1C may promote lung epithelial mesenchymal transition (EMT), resulting in the development of a lung cancer stem cell phenotype, progression, and metastasis, in part, through modulation of miR-33a expression. Our findings reveal a new mechanistic insight into how RASSF1C functions as an oncogene.

High-Density Lipoprotein Components and Functionality in Cancer: State-of-the-Art

Cancer is the second leading cause of death in western countries, and thus represents a major global public health issue. Whilst it is well-recognized that diet, obesity, and smoking are risk factors for cancer, the role of low levels of high-density lipoprotein cholesterol (HDL-C) in cancer is less well appreciated. Conflicting evidence suggests that serum HDL-C levels may be either positively or negatively associated with cancer incidence and mortality. Such disparate associations are supported in part by the multitude of high-density lipoprotein (HDL) functions that can all have an impact on cancer cell biology. The aim of this review is to provide a comprehensive overview of the crosstalk between HDLs and cancer, focusing on the molecular mechanisms underlying this association.

The Role of Curcumin in Prevention and Management of Metastatic Disease

In the last two decades, targeted therapies have enhanced tumor patient care and treatment success, however, metastatic growth still cannot be stopped efficiently and, therefore, mortality rates remain high. Prevention strategies against formation of metastases are the most promising approach we have, however, due to lack of clinical validation studies, they have not yet entered routine clinical care. In order to smooth the way for efficient prevention, further preclinical and large clinical studies are required. In this context, the underlying molecular mechanisms and factors that lead to metastatic growth have to be explored, and potential preventive agents have to be tested. Thereby, special attention has to be paid to natural bioactive compounds which do not exert major adverse effects, like the plant-derived polyphenol Curcumin, which is known to be a powerful antitumor agent. So far, most of the preclinical studies with Curcumin have focused on its effect on inhibiting tumor cell proliferation and invasion, although, it is known that it also inhibits metastatic spread in vivo. This review discusses the preventive potential of this natural compound not only against tumor onset, but also against formation of metastases.

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.

ABC Transporters in Cancer Stem Cells: Beyond Chemoresistance

The efficacy of chemotherapy is one of the main challenges in cancer treatment and one of the major obstacles to overcome in achieving lasting remission and a definitive cure in patients with cancer is the emergence of cancer resistance. Indeed, drug resistance is ultimately accountable for poor treatment outcomes and tumour relapse. There are various molecular mechanisms involved in multidrug resistance, such as the change in the activity of membrane transporters primarily belonging to the ATP binding cassette (ABC) transporter family. In addition, it has been proposed that this common feature could be attributed to a subpopulation of slow-cycling cancer stem cells (CSCs), endowed with enhanced tumorigenic potential and multidrug resistance. CSCs are characterized by the overexpression of specific surface markers that vary in different cancer cell types. Overexpression of ABC transporters has been reported in several cancers and more predominantly in CSCs. While the major focus on the role played by ABC transporters in cancer is polarized by their involvement in chemoresistance, emerging evidence supports a more active role of these proteins, in which they release specific bioactive molecules in the extracellular milieu. This review will outline our current understanding of the role played by ABC transporters in CSCs, how their expression is regulated and how they support the malignant metabolic phenotype. To summarize, we suggest that the increased expression of ABC transporters in CSCs may have precise functional roles and provide the opportunity to target, particularly these cells, by using specific ABC transporter inhibitors.

Valproic acid (VPA) enhances cisplatin sensitivity of non-small cell lung cancer cells via HDAC2 mediated down regulation of ABCA1

Valproic acid (VPA) has been suggested to be a histone deacetylase inhibitor (HDACI). Our present study revealed that VPA at 1 mm, which had no effect on cell proliferation, can significantly increase the sensitivity of non-small cell lung cancer (NSCLC) cells to cisplatin (DDP). VPA treatment markedly decreased the mRNA and protein levels of ABCA1, while had no significant effect on ABCA3, ABCA7 or ABCB10. Luciferase reporter assays showed that VPA can decrease the ABCA1 promoter activity in both A549 and H358 cells. VPA treatment also decreased the phosphorylation of SP1, which can bind to -100 and -166 bp in the promoter of ABCA1. While the phosphorylation of c-Fos and c-Jun were not changed in VPA treated NSCLC cells. Over expression of HDAC2 attenuated VPA induced down regulation of ABCA1 mRNA expression and promoter activities. Over expression of HDAC2 also attenuated VPA induced DDP sensitivity of NSCLC cells. These data revealed that VPA can increase the DDP sensitivity of NSCLC cells via down regulation of ABCA1 through HDAC2/SP1 signals. It suggested that combination of VPA and anticancer drugs such as DDP might be great helpful for treatment of NSCLC patients.

Curcumin and insulin resistance-Molecular targets and clinical evidences

Curcumin ((1E,6E)-1,7-bis(4-hydroxy-3-methoxyphenyl)-1,6-heptadiene-3,5-dione), the main component of the Indian spice turmeric, has been used in traditional medicine to improve diabetes and its comorbidities. Since the last two decades, scientific research has shown that in addition to its antioxidant properties, curcumin could also work as protein homeostasis regulator and it is able to modulate other intracellular pathways. Curcumin supplementation has been proposed to improve insulin resistance (IR) through the activation of the insulin receptor and its downstream pathways in several experimental models, pointing out that its clinical use may be a good and innocuous strategy to improve IR-related diseases. IR is associated with many diseases and syndromes like carbohydrate intolerance, diabetes, metabolic syndrome, and cardiovascular disease. Therefore, it is imperative to identify safe therapeutic interventions aimed to reduce side effects that could lead the patient to leave the treatment. To date, many clinical trials have been carried out using turmeric and curcumin to improve metabolic syndrome, carbohydrate intolerance, diabetes, and obesity in individuals with IR. Results so far are inconclusive because dose, time of treatment, and type of curcumin can change the study outcome significantly. However, there is some clinical evidence suggesting a beneficial effect of curcumin on IR. In this review, we discuss the factors that could influence curcumin effects in clinical trials aimed to improve IR and related diseases, and the conclusions that can be drawn from results obtained so far. © 2016 BioFactors, 42(6):561-580, 2016.

Comparative Gene Expression Profiling of Primary and Metastatic Renal Cell Carcinoma Stem Cell-Like Cancer Cells

Background

Recent advancement in cancer research has shown that tumors are highly heterogeneous, and multiple phenotypically different cell populations are found in a single tumor. Cancer development and tumor growth are driven by specific types of cells—stem cell-like cancer cells (SCLCCs)—which are also responsible for metastatic spread and drug resistance. This research was designed to verify the presence of SCLCCs in renal cell cancer cell lines. Subsequently, we aimed to characterize phenotype and cell biology of CD105+ cells, defined previously as renal cell carcinoma tumor-initiating cells. The main goal of the project was to describe the gene-expression profile of stem cell-like cancer cells of primary tumor and metastatic origin.

Materials and Methods

Real-time PCR analysis of stemness genes (Oct-4, Nanog and Ncam) and soft agar colony formation assay were conducted to check the stemness properties of renal cell carcinoma (RCC) cell lines. FACS analysis of CD105+ and CD133+ cells was performed on RCC cells. Isolated CD105+ cells were verified for expression of mesenchymal markers—CD24, CD146, CD90, CD73, CD44, CD11b, CD19, CD34, CD45, HLA-DR and alkaline phosphatase. Hanging drop assay was used to investigate CD105+ cell-cell cohesion. Analysis of free-floating 3D spheres formed by isolated CD105+ was verified, as spheres have been hypothesized to contain undifferentiated multipotent progenitor cells. Finally, CD105+ cells were sorted from primary (Caki-2) and metastatic (ACHN) renal cell cancer cell lines. Gene-expression profiling of sorted CD105+ cells was performed with Agilent’s human GE 4x44K v2 microarrays. Differentially expressed genes were further categorized into canonical pathways. Network analysis and downstream analysis were performed with Ingenuity Pathway Analysis.

Results

Metastatic RCC cell lines (ACHN and Caki-1) demonstrated higher colony-forming ability in comparison to primary RCC cell lines. Metastatic RCC cell lines harbor numerous CD105+ cell subpopulations and have higher expression of stemness genes (Oct-4 and Nanog). CD105+ cells adopt 3D grape-like floating structures under handing drop conditions. Sorted CD105+ cells are positive for human mesenchymal stem cell (MSC) markers CD90, CD73, CD44, CD146, and alkaline phosphatase activity, but not for CD24 and hematopoietic lineage markers CD34, CD11b, CD19, CD45, and HLA-DR. 1411 genes are commonly differentially expressed in CD105+ cells (both from primary [Caki-2] and metastatic RCC [ACHN] cells) in comparison to a healthy kidney epithelial cell line (ASE-5063). TGF-β, Wnt/β-catenine, epithelial-mesenchymal transition (EMT), Rap1 signaling, PI3K-Akt signaling, and Hippo signaling pathway are deregulated in CD105+ cells. TGFB1, ERBB2, and TNF are the most significant transcriptional regulators activated in these cells.

Conclusions

All together, RCC-CD105+ cells present stemlike properties. These stem cell-like cancer cells may represent a novel target for therapy. A unique gene-expression profile of CD105+ cells could be used as initial data for subsequent functional studies and drug design.

Impacts on Sirtuin Function and Bioavailability of the Dietary Bioactive Compound Dihydrocoumarin

The plant secondary metabolite and common food additive dihydrocoumarin (DHC) is an inhibitor of the Sirtuin family of NAD+-dependent deacetylases. Sirtuins are key regulators of epigenetic processes that maintain silent chromatin in yeast and have been linked to gene expression, metabolism, apoptosis, tumorogenesis and age-related processes in multiple organisms, including humans. Here we report that exposure to the polyphenol DHC led to defects in several Sirtuin-regulated processes in budding yeast including the establishment and maintenance of Sir2p-dependent silencing by causing disassembly of silent chromatin, Hst1p-dependent repression of meiotic-specific genes during the mitotic cell cycle. As both transient and prolonged exposure to environmental and dietary factors have the potential to lead to heritable alterations in epigenetic states and to modulate additional Sirtuin-dependent phenotypes, we examined the bioavailability and digestive stability of DHC using an in vivo rat model and in vitro digestive simulator. Our analyses revealed that DHC was unstable during digestion and could be converted to melilotic acid (MA), which also caused epigenetic defects, albeit less efficiently. Upon ingestion, DHC was observed primarily in intestinal tissues, but did not accumulate over time and was readily cleared from the animals. MA displayed a wider tissue distribution and, in contrast to DHC, was also detected in the blood plasma, interstitial fluid, and urine, implying that the conversion of DHC to the less bioactive compound, MA, occurred efficiently in vivo.

ColoLipidGene: signature of lipid metabolism-related genes to predict prognosis in stage-II colon cancer patients

Lipid metabolism plays an essential role in carcinogenesis due to the requirements of tumoral cells to sustain increased structural, energetic and biosynthetic precursor demands for cell proliferation. We investigated the association between expression of lipid metabolism-related genes and clinical outcome in intermediate-stage colon cancer patients with the aim of identifying a metabolic profile associated with greater malignancy and increased risk of relapse. Expression profile of 70 lipid metabolism-related genes was determined in 77 patients with stage II colon cancer. Cox regression analyses using c-index methodology was applied to identify a metabolic-related signature associated to prognosis. The metabolic signature was further confirmed in two independent validation sets of 120 patients and additionally, in a group of 264 patients from a public database. The combined analysis of these 4 genes, ABCA1, ACSL1, AGPAT1 and SCD, constitutes a metabolic-signature (ColoLipidGene) able to accurately stratify stage II colon cancer patients with 5-fold higher risk of relapse with strong statistical power in the four independent groups of patients. The identification of a group of 4 genes that predict survival in intermediate-stage colon cancer patients allows delineation of a high-risk group that may benefit from adjuvant therapy, and avoids the toxic and unnecessary chemotherapy in patients classified as low-risk group.

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

BACKGROUND & AIMS

The cancer stem cells (CSCs) have important therapeutic implications for multi-resistant cancers including hepatocellular carcinoma (HCC). Among the key pathways frequently activated in liver CSCs is NF-κB signaling.

METHODS

We evaluated the CSCs-depleting potential of NF-κB inhibition in liver cancer achieved by the IKK inhibitor curcumin, RNAi and specific peptide SN50. The effects on CSCs were assessed by analysis of side population (SP), sphere formation and tumorigenicity. Molecular changes were determined by RT-qPCR, global gene expression microarray, EMSA, and Western blotting.

RESULTS

HCC cell lines exposed to curcumin exhibited differential responses to curcumin and were classified as sensitive and resistant. In sensitive lines, curcumin-mediated induction of cell death was directly related to the extent of NF-κB inhibition. The treatment also led to a selective CSC-depletion as evidenced by a reduced SP size, decreased sphere formation, down-regulation of CSC markers and suppressed tumorigenicity. Similarly, NF-κB inhibition by SN50 and siRNA against p65 suppressed tumor cell growth. In contrast, curcumin-resistant cells displayed a paradoxical increase in proliferation and expression of CSC markers. Mechanistically, an important component of the CSC-depleting activity of curcumin could be attributed to a NF-κB-mediated HDAC inhibition. Co-administration of the class I/II HDAC inhibitor trichostatine sensitized resistant cells to curcumin. Further, integration of a predictive signature of curcumin sensitivity with human HCC database indicated that HCCs with poor prognosis and progenitor features are most likely to benefit from NF-κB inhibition.

CONCLUSIONS

These results demonstrate that blocking NF-κB can specifically target CSC populations and suggest a potential for combined inhibition of NF-κB and HDAC signaling for treatment of liver cancer patients with poor prognosis.

MicroRNA-106a confers cisplatin resistance in non-small cell lung cancer A549 cells by targeting adenosine triphosphatase-binding cassette A1

MicroRNAs (miRNAs) have been discovered to have pivotal roles in regulating the drug resistance of various types of human cancer, including cisplatin (DDP) resistance in non-small cell lung cancer (NSCLC). Fewer studies have explored the roles of miR-106a in NSCLC-cell resistance to DDP and its precise molecular mechanism has remained elusive. In the present study, whether miR-106a was able to mediate resistance of the lung cancer cell line A549 to DDP was investigated. Reverse transcription quantitative polymerase chain reaction was used to analyze miR-106a mRNA expression levels. miR-106a expression levels were upregulated in the DDP-resistant cell line A549/DDP compared with its parental cell line, A549. miR-106a-transfection induced DDP-resistance in A549 cells, while repression of miR-106a by anti-miR-106a in A549/DDP resulted in enhanced DDP cytotoxicity. Furthermore, it was discovered that the mechanism of miR-106a-induced DDP resistance involved the expression of adenosine triphosphatase-binding cassette, sub-family A, member 1 (ABCA1), as indicated by transfection of cells with short interfering RNA-ABCA1. The results of the present study suggested a novel mechanism underlying DDP-resistance in NSCLC.

Cytotoxic activity of hirsutanone, a diarylheptanoid isolated from Alnus glutinosa leaves

BACKGROUND

The low efficacy of cancer therapy for the treatment of patients with advanced disease makes the development of new anticancer agents necessary. Because natural products are a significant source of anticancer drugs, it is important to explore cytotoxic activity of novel compounds from natural origin.

PURPOSE

The aim of this work is to evaluate the cytotoxic capacity of hirsutanone, a diarylheptanoid isolated from Alnus glutinosa leaves. Hirsutanone cytotoxic way of action was also studied.

MATERIAL AND METHODS

The cytotoxic ability of Alnus glutinosa leaves ethyl acetate extract was studied over HeLa and PC-3 cell lines, with the MTT colorimetric assay. Hirsutanone was isolated from this extract using chromatographic methods, and its structure elucidated by spectroscopic analysis. HT-29 cell viability after hirsutanone treatment was determined using SRB assay. In order to understand hirsutanone way of action, cytotoxicity was evaluated adding the diarylheptanoid and antioxidants. DNA topoisomerase II (topo II) poison activity, was also evaluated using purified topo II and a supercoiled form of DNA that bears specific topo II recognition and binding region; topo II poisons stabilize normally transient DNA-topo II cleavage complexes, and lead an increased yield of linear form as a consequence of a lack of double-strand breaks rejoining.

RESULTS

The diarylheptanoid hirsutanone was isolated from Alnus glutinosa (L.) Gaertn. (Betulaceae) leaves extract that showed cytotoxic activity against PC-3 and HeLa cell lines. Hirsutanone showed cytotoxic activity against HT-29 human colon carcinoma cells. Pre-treatment with the antioxidants NAC (N-acetylcysteine) and MnTMPyP (Mn(III)tetrakis-(1-methyl-4-pyridyl)porthyrin) reduced this activity, suggesting that reactive oxygen species (ROS) participate in hirsutanone-induced cancer cell death. Using human topo II and a DNA supercoiled form, hirsutanone was found to stabilize topo II-DNA cleavage complexes, acting as a topo II poison.

CONCLUSION

Our data suggest that, like curcumin, an induction of oxidative stress and topo II-mediated DNA damage may play a role in hirsutanone-induced cancer cell death. Since both compounds share similar structure and cytotoxic profile, and curcumin is in clinical trials for the treatment of cancer, our results warrant further studies to evaluate the anticancer potential of hirsutanone.

Effects of curcumin on ion channels and transporters

Curcumin [1,7-bis(4-hydroxy-3-methoxyphenyl)-1,6-heptadiene-3,5-dione], a polyphenolic compound isolated from the rhizomes of Curcuma longa (turmeric), has been shown to exhibit a wide range of pharmacological activities including anti-inflammatory, anti-cancer, anti-oxidant, anti-atherosclerotic, anti-microbial, and wound healing effects. These activities of curcumin are based on its complex molecular structure and chemical features, as well as its ability to interact with multiple signaling molecules. The ability of curcumin to regulate ion channels and transporters was recognized a decade ago. The cystic fibrosis transmembrane conductance regulator (CFTR) is a well-studied ion channel target of curcumin. During the process of studying its anti-cancer properties, curcumin was found to inhibit ATP-binding cassette (ABC) family members including ABCA1, ABCB1, ABCC1, and ABCG2. Recent studies have revealed that many channels and transporters are modulated by curcumin, such as voltage-gated potassium (Kv) channels, high-voltage-gated Ca(2+) channels (HVGCC), volume-regulated anion channel (VRAC), Ca(2+) release-activated Ca(2+) channel (CRAC), aquaporin-4 (AQP-4), glucose transporters, etc., In this review, we aim to provide an overview of the interactions of curcumin with different types of ion channels and transporters and to help better understand and integrate the underlying molecular mechanisms of the multiple pharmacological activities of curcumin.

miR181b is induced by the chemopreventive polyphenol curcumin and inhibits breast cancer metastasis via down-regulation of the inflammatory cytokines CXCL1 and -2

Chronic inflammation is a major risk factor for the development and metastatic progression of cancer. We have previously reported that the chemopreventive polyphenol Curcumin inhibits the expression of the proinflammatory cytokines CXCL1 and -2 leading to diminished formation of breast and prostate cancer metastases. In the present study, we have analyzed the effects of Curcumin on miRNA expression and its correlation to the anti-tumorigenic properties of this natural occurring polyphenol. Using microarray miRNA expression analyses, we show here that Curcumin modulates the expression of a series of miRNAs, including miR181b, in metastatic breast cancer cells. Interestingly, we found that miR181b down-modulates CXCL1 and -2 through a direct binding to their 3'-UTR. Overexpression or inhibition of miR181b in metastatic breast cancer cells has a significant impact on CXCL1 and -2 and is required for the effect of Curcumin on these two cytokines. miR181b also mediates the effects of Curcumin on inhibition of proliferation and invasion as well as induction of apoptosis. Importantly, over-expression of miR181b in metastatic breast cancer cells inhibits metastasis formation in vivo in immunodeficient mice. Finally, we demonstrated that Curcumin up-regulates miR181b and down-regulates CXCL1 and -2 in cells isolated from several primary human breast cancers. Taken together, these data show that Curcumin provides a simple bridge to bring metastamir modulation into the clinic, placing it in a primary and tertiary preventive, as well as a therapeutic, setting.

Mitochondrial targeting overcomes ABCA1-dependent resistance of lung carcinoma to α-tocopheryl succinate

α-Tocopheryl succinate (α-TOS) is a promising anti-cancer agent due to its selectivity for cancer cells. It is important to understand whether long-term exposure of tumour cells to the agent will render them resistant to the treatment. Exposure of the non-small cell lung carcinoma H1299 cells to escalating doses of α-TOS made them resistant to the agent due to the upregulation of the ABCA1 protein, which caused its efflux. Full susceptibility of the cells to α-TOS was restored by knocking down the ABCA1 protein. Similar resistance including ABCA1 gene upregulation was observed in the A549 lung cancer cells exposed to α-TOS. The resistance of the cells to α-TOS was overcome by its mitochondrially targeted analogue, MitoVES, that is taken up on the basis of the membrane potential, bypassing the enhanced expression of the ABCA1 protein. The in vitro results were replicated in mouse models of tumours derived from parental and resistant H1299 cells. We conclude that long-term exposure of cancer cells to α-TOS causes their resistance to the drug, which can be overcome by its mitochondrially targeted counterpart. This finding should be taken into consideration when planning clinical trials with vitamin E analogues.

Genome-wide identification of molecular pathways and biomarkers in response to arsenic exposure in zebrafish liver

Inorganic arsenic is a worldwide metalloid pollutant in environment. Although extensive studies on arsenic-induced toxicity have been conducted using in vivo and in vitro models, the exact molecular mechanism of arsenate toxicity remains elusive. Here, the RNA-SAGE (serial analysis of gene expression) sequencing technology was used to analyse hepatic response to arsenic exposure at the transcriptome level. Based on more than 12 million SAGE tags mapped to zebrafish genes, 1,444 differentially expressed genes (750 up-regulated and 694 down-regulated) were identified from a relatively abundant transcripts (>10 TPM [transcripts per million]) based on minimal two-fold change. By gene ontology analyses, these differentially expressed genes were significantly enriched in several major biological processes including oxidation reduction, translation, iron ion transport, cell redox, homeostasis, etc. Accordingly, the main pathways disturbed include metabolic pathways, proteasome, oxidative phosphorylation, cancer, etc. Ingenity Pathway Analysis further revealed a network with four important upstream factors or hub genes, including Jun, Kras, APoE and Nr2f2. The network indicated apparent molecular events involved in oxidative stress, carcinogenesis, and metabolism. In order to identify potential biomarker genes for arsenic exposure, 27 out of 29 up-regulated transcripts were validated by RT-qPCR analysis in pooled RNA samples. Among these, 14 transcripts were further confirmed for up-regulation by a lower dosage of arsenic in majority of individual zebrafish. Finally, at least four of these genes, frh3 (ferrintin H3), mgst1 (microsomal glutathione S-transferase-like), cmbl (carboxymethylenebutenolidase homolog) and slc40a1 (solute carrier family 40 [iron-regulated transporter], member 1) could be confirmed in individual medaka fish similarly treated by arsenic; thus, these four genes might be robust arsenic biomarkers across species. Thus, our work represents the first comprehensive investigation of molecular mechanism of asenic toxicity and genome-wide search for potential biomarkers for arsenic exposure.

Evidence of epidermal growth factor receptor expression in uveal melanoma: inhibition of epidermal growth factor-mediated signalling by Gefitinib and Cetuximab triggered antibody-dependent cellular cytotoxicity

Despite advances in surgery and radiotherapy of uveal melanoma (UM), many patients develop distant metastases that poorly respond to therapy. Improved therapies for the metastatic disease are therefore urgently needed. Expression of the epidermal growth factor receptor (EGFR), a target of kinase inhibitors and humanised antibodies in use for several cancers, had been reported. Forty-eight human UMs were analysed by expression profiling. Signalling was tested in three EGFR expressing UM cell lines by Western blotting using phosphorylation specific antibodies for EGFR and the downstream mediators AKT (v-akt murine thymoma viral oncogene homolog) and extracellular signal-regulated kinase (ERK). Evidence for signalling in tumours was obtained through the application of a UM-specific EGF-signature. The EGFR specific kinase inhibitor, Gefitinib and the humanised monoclonal antibody, Cetuximab, were tested for their effect on EGFR signalling. Natural killer cell mediated antibody-dependent cellular cytotoxicity (ADCC) and tumour necrosis factor α (TNF-α) release was analysed for Cetuximab. Fourteen of 48 UMs and three of 14 cell lines (over-)express EGFR, at least in part due to trisomy of the EGFR locus on chromosome 7p12. EGFR and the downstream mediator, AKT, are phosphorylated upon stimulation with EGF in EGFR expressing cell lines. EGFR over-expressing tumours but not EGFR negative tumours show an activated EGF-signature. Gefitinib inhibits EGFR and AKT phosphorylation and Cetuximab induces EGFR phosphorylation but inhibits signalling to AKT induced with EGF. Cetuximab triggers natural killer (NK) cells to lyse EGFR+ cell lines and to release TNF-α. EGFR appears suited as a novel molecular drug target for therapy of uveal melanoma.

Properties of lewis lung carcinoma cells surviving curcumin toxicity

The anti-inflammatory agent curcumin can selectively eliminate malignant rather than normal cells. The present study examined the effects of curcumin on the Lewis lung carcinoma (LLC) cell line and characterized a subpopulation surviving curcumin treatments. Cell density was measured after curcumin was applied at concentrations between 10 and 60 μM for 30 hours. Because of the high cell loss at 60 μM, this dose was chosen to select for surviving cells that were then used to establish a new cell line. The resulting line had approximately 20% slower growth than the original LLC cell line and based on ELISA contained less of two markers, NF-κB and ALDH1A, used to identify more aggressive cancer cells. We also injected cells from the original and surviving lines subcutaneously into syngeneic C57BL/6 mice and monitored tumor development over three weeks and found that the curcumin surviving-line remained tumorigenic. Because curcumin has been reported to kill cancer cells more effectively when administered with light, we examined this as a possible way of enhancing the efficacy of curcumin against LLC cells. When LLC cells were exposed to curcumin and light from a fluorescent lamp source, cell loss caused by 20 μM curcumin was enhanced by about 50%, supporting a therapeutic use of curcumin in combination with white light. This study is the first to characterize a curcumin-surviving subpopulation among lung cancer cells. It shows that curcumin at a high concentration either selects for an intrinsically less aggressive cell subpopulation or generates these cells. The findings further support a role for curcumin as an adjunct to traditional chemical or radiation therapy of lung and other cancers.

Potential applications of curcumin and its novel synthetic analogs and nanotechnology-based formulations in cancer prevention and therapy

Curcumin has attracted great attention in the therapeutic arsenal in clinical oncology due to its chemopreventive, antitumoral, radiosensibilizing and chemosensibilizing activities against various types of aggressive and recurrent cancers. These malignancies include leukemias, lymphomas, multiple myeloma, brain cancer, melanoma and skin, lung, prostate, breast, ovarian, liver, gastrointestinal, pancreatic and colorectal epithelial cancers. Curcumin mediates its anti-proliferative, anti-invasive and apoptotic effects on cancer cells, including cancer stem/progenitor cells and their progenies, through multiple molecular mechanisms. The oncogenic pathways inhibited by curcumin encompass the members of epidermal growth factor receptors (EGFR and erbB2), sonic hedgehog (SHH)/GLIs and Wnt/β-catenin and downstream signaling elements such as Akt, nuclear factor-kappa B (NF-κB) and signal transducers and activators of transcription (STATs). In counterbalance, the high metabolic instability and poor systemic bioavailability of curcumin limit its therapeutic efficacy in human. Of great therapeutic interest, the selective delivery of synthetic analogs or nanotechnology-based formulations of curcumin to tumors, alone or in combination with other anticancer drugs, may improve their chemopreventive and chemotherapeutic efficacies against cancer progression and relapse. Novel curcumin formulations may also be used to reverse drug resistance, eradicate the total cancer cell mass and improve the anticarcinogenic efficacy of the current anti-hormonal and chemotherapeutic treatments for patients with various aggressive and lethal cancers.

Pharmacogenomic determination of genes associated with sensitivity or resistance of tumor cells to curcumin and curcumin derivatives

Curcuma longa L. has long been used as a medicinal plant in traditional Chinese medicine against abdominal disorders. Its active constituent curcumin has anti-inflammatory, chemopreventive and cytotoxic properties. In the present investigation, we have analyzed the cytotoxic activity of curcumin and four derivatives. Among these compounds, ethoxycurcumintrithiadiazolaminomethylcarbonate was the most cytotoxic one. The curcumin-type compounds were not cross-resistant to standard anticancer drugs and were not involved in ATP-binding cassette transporter-mediated multidrug resistance. A combined approach of messenger RNA-based microarray profiling, COMPARE analyses and signaling pathway analyses identified genes as determinants of sensitivity and resistance to curcumin and specific signaling routes involved in cellular response to curcumin. These genes may be useful as biomarkers to develop individualized treatment options in the future. From a nutritional point of view, it is a thriving perspective to further investigate whether C. longa may be used as a spice to improve cancer therapy.

Botanicals for the prevention and treatment of cutaneous melanoma

Cutaneous melanoma, a cancer of melanocytes, when detected at later stages is arguably one of the most lethal cancers and the cause of more years of lost life than any other cancer among young adults. There is no standard therapy for advanced-stage melanoma and the median survival time for patients with metastatic melanoma is <1 yr. An urgent need for novel strategies against melanoma has directed research towards the development of new chemotherapeutic and biologic agents that can target the tumor by several different mechanisms. Recently, several dietary agents are being investigated for their role in the prevention and treatment of various forms of cancer and may represent the future modality of the treatment. Here, we have reviewed emerging data on botanicals that are showing promise for their potential inhibitory effect against cutaneous melanoma.