Inhibitor of 5-lipoxygenase, zileuton, suppresses prostate cancer metastasis by upregulating E-cadherin and paxillin

A disease-associated missense mutation in CYP4F3 affects the metabolism of leukotriene B4 via disruption of electron transfer

BACKGROUND

Cytochrome P450 4F3 (CYP4F3) is an ω-hydroxylase that oxidizes leukotriene B4 (LTB4), prostaglandins, and fatty acid epoxides. LTB4 is synthesized by leukocytes and acts as a chemoattractant for neutrophils, making it an essential component of the innate immune system. Recently, involvement of the LTB4 pathway was reported in various immunological disorders such as asthma, arthritis, and inflammatory bowel disease. We report a 26-year-old female with a complex immune phenotype, mainly marked by exhaustion, muscle weakness, and inflammation-related conditions. The molecular cause is unknown, and symptoms have been aggravating over the years.

METHODS

Whole exome sequencing was performed and validated; flow cytometry and enzyme-linked immunosorbent assay were used to describe patient's phenotype. Function and impact of the mutation were investigated using molecular analysis: co-immunoprecipitation, western blot, and enzyme-linked immunosorbent assay. Capillary electrophoresis with ultraviolet detection was used to detect LTB4 and its metabolite and in silico modelling provided structural information.

RESULTS

We present the first report of a patient with a heterozygous de novo missense mutation c.C1123 > G;p.L375V in CYP4F3 that severely impairs its activity by 50% (P < 0.0001), leading to reduced metabolization of the pro-inflammatory LTB4. Systemic LTB4 levels (1034.0 ± 75.9 pg/mL) are significantly increased compared with healthy subjects (305.6 ± 57.0 pg/mL, P < 0.001), and immune phenotyping shows increased total CD19+ CD27- naive B cells (25%) and decreased total CD19+ CD27+ IgD- switched memory B cells (19%). The mutant CYP4F3 protein is stable and binding with its electron donors POR and Cytb5 is unaffected (P > 0.9 for both co-immunoprecipitation with POR and Cytb5). In silico modelling of CYP4F3 in complex with POR and Cytb5 suggests that the loss of catalytic activity of the mutant CYP4F3 is explained by a disruption of an α-helix that is crucial for the electron shuffling between the electron carriers and CYP4F3. Interestingly, zileuton still inhibits ex vivo LTB4 production in patient's whole blood to 2% of control (P < 0.0001), while montelukast and fluticasone do not (99% and 114% of control, respectively).

CONCLUSIONS

A point mutation in the catalytic domain of CYP4F3 is associated with high leukotriene B4 plasma levels and features of a more naive adaptive immune response. Our data provide evidence for the pathogenicity of the CYP4F3 variant as a cause for the observed clinical features in the patient. Inhibitors of the LTB4 pathway such as zileuton show promising effects in blocking LTB4 production and might be used as a future treatment strategy.

Comparative Pathobiology of Canine and Human Prostate Cancer: State of the Art and Future Directions

First described in 1817, prostate cancer is considered a complex neoplastic entity, and one of the main causes of death in men in the western world. In dogs, prostatic carcinoma (PC) exhibits undifferentiated morphology with different phenotypes, is hormonally independent of aggressive character, and has high rates of metastasis to different organs. Although in humans, the risk factors for tumor development are known, in dogs, this scenario is still unclear, especially regarding castration. Therefore, with the advent of molecular biology, studies were and are carried out with the aim of identifying the main molecular mechanisms and signaling pathways involved in the carcinogenesis and progression of canine PC, aiming to identify potential biomarkers for diagnosis, prognosis, and targeted treatment. However, there are extensive gaps to be filled, especially when considering the dog as experimental model for the study of this neoplasm in humans. Thus, due to the complexity of the subject, the objective of this review is to present the main pathobiological aspects of canine PC from a comparative point of view to the same neoplasm in the human species, addressing the historical context and current understanding in the scientific field.

Zileuton inhibits arachidonate-5-lipoxygenase to exert antitumor effects in preclinical cervical cancer models

BACKGROUND

Inhibitors of arachidonate lipoxygenase 5 (ALOX5) exhibit anticancer activity. Zileuton is an FDA-approved drug for treating asthma and an ALOX5 inhibitor. This study evaluated the efficacy of zileuton in cervical cancer, determined the molecular mechanism of action, and assessed ALOX5 expression in cervical cancer patients.

METHODS

The effects of zileuton were evaluated using cervical cancer cell lines and xenograft mouse models. Loss-of-function analysis of ALOX5 was performed using siRNA. The levels of ALOX5 and 5-HETE were determined using immunohistochemistry and ELISA.

RESULTS

Zileuton resulted in cell proliferation inhibition and apoptosis induction in a dose-dependent manner, regardless of cellular origin or HPV infection. In two independent cervical cancer xenograft mouse models, zileuton at nontoxic doses significantly prevented tumor formation and decreased tumor growth. Zileuton acts on cervical cancer cells by inhibiting the ALOX5-5-HETE axis. Of note, ALOX5-5-HETE was significantly upregulated in cervical cancer compared with normal tissue. Inhibition of ALOX5 via the siRNA approach mimics the inhibitory effects of zileuton and confirms the roles of ALOX5 in cervical cancer.

CONCLUSIONS

Our work demonstrates that the ALOX5-5-HETE axis is activated in cervical cancer, with important roles in growth and survival, and this can be therapeutically targeted by zileuton. Our findings also provide preclinical evidence to assess the efficacy of zileuton in cervical cancer in clinical settings.

Small Molecules as Drugs to Upregulate Metastasis Suppressors in Cancer Cells

It is well-recognized that the majority of cancer-related deaths is attributed to metastasis, which can arise from virtually any type of tumor. Metastasis is a complex multistep process wherein cancer cells must break away from the primary tumor, intravasate into the circulatory or lymphatic systems, extravasate, proliferate and eventually colonize secondary sites. Since these molecular processes involve the coordinated actions of numerous proteins, targeted disruptions of key players along these pathways represent possible therapeutic interventions to impede metastasis formation and reduce cancer mortality. A diverse group of proteins with demonstrated ability to inhibit metastatic colonization have been identified and they are collectively known as metastasis suppressors. Given that the metastasis suppressors are often downregulated in tumors, drug-induced re-expression or upregulation of these proteins represents a promising approach to limit metastasis. Indeed, over 40 compounds are known to exhibit efficacy in upregulating the expression of metastasis suppressors via transcriptional or post-transcriptional mechanisms, and the most promising ones are being evaluated for their translational potentials. These small molecules range from natural products to drugs in clinical use and they apparently target different molecular pathways, reflecting the diverse nature of the metastasis suppressors. In this review, we provide an overview of the different classes of compounds known to possess the ability to upregulate one or more metastasis suppressors, with an emphasis on their mechanisms of action and therapeutic potentials.

Zileuton, a 5-Lipoxygenase Inhibitor, Exerts Anti-Angiogenic Effect by Inducing Apoptosis of HUVEC via BK Channel Activation

The arachidonic acid metabolism through 5-lipoxygenase (5-LO) pathways is involved in modulating both tumorigenesis and angiogenesis. Although anti-carcinogenic activities of certain 5-LO inhibitors have been reported, the role of zileuton, a well known 5-LO inhibitor, on the endothelial cell proliferation and angiogenesis has not been fully elucidated. Here, we report that zileuton has an anti-angiogenic effect, and the underlying mechanisms involved activation of the large-conductance Ca²⁺-activated K⁺ (BK) channel. Our results show that zileuton significantly prevented vascular endothelial growth factor (VEGF)-induced proliferation of human umbilical vein endothelial cells (HUVECs) in vitro, as well as in vivo. However, such anti-angiogenic effect of zileuton was abolished by iberiotoxin (IBTX), a BK channel blocker, suggesting zileuton-induced activation of BK channel was critical for the observed anti-angiogenic effect of zileuton. Furthermore, the anti-angiogenic effect of zileuton was, at least, due to the activation of pro-apoptotic signaling cascades which was also abolished by IBTX. Additionally, zileuton suppressed the expression of VCAM-1, ICAM-1, ETS related gene (Erg) and the production of nitric oxide (NO). Taken together, our results show that zileuton prevents angiogenesis by activating the BK channel dependent-apoptotic pathway, thus highlighting its therapeutic capacity in angiogenesis-related diseases, such as cancer.

Rational approaches, design strategies, structure activity relationship and mechanistic insights for therapeutic coumarin hybrids

Hybrid molecules, furnished by combining two or more pharmacophores is an emerging concept in the field of medicinal chemistry and drug discovery that has attracted substantial traction in the past few years. Naturally occurring scaffolds such as coumarins display a wide spectrum of pharmacological activities including anticancer, antibiotic, antidiabetic and others, by acting on multiple targets. In this view, various coumarin-based hybrids possessing diverse medicinal attributes were synthesized in the last five years by conjugating coumarin moiety with other therapeutic pharmacophores. The current review summarizes the recent development (2014 and onwards) of these pharmacologically active coumarin hybrids and demonstrates rationale behind their design, structure-activity relationships (SAR) and mechanistic studies performed on these hybrid molecules. This review will be beneficial for medicinal chemist and chemical biologist, and in general to the drug discovery community and will facilitate the synthesis and development of novel, potent coumarin hybrid molecules serving as lead molecules for the treatment of complex disorders.

Inhibiting eukaryotic ribosome biogenesis

BACKGROUND

Ribosome biogenesis is a central process in every growing cell. In eukaryotes, it requires more than 250 non-ribosomal assembly factors, most of which are essential. Despite this large repertoire of potential targets, only very few chemical inhibitors of ribosome biogenesis are known so far. Such inhibitors are valuable tools to study this highly dynamic process and elucidate mechanistic details of individual maturation steps. Moreover, ribosome biogenesis is of particular importance for fast proliferating cells, suggesting its inhibition could be a valid strategy for treatment of tumors or infections.

RESULTS

We systematically screened ~ 1000 substances for inhibitory effects on ribosome biogenesis using a microscopy-based screen scoring ribosomal subunit export defects. We identified 128 compounds inhibiting maturation of either the small or the large ribosomal subunit or both. Northern blot analysis demonstrates that these inhibitors cause a broad spectrum of different rRNA processing defects.

CONCLUSIONS

Our findings show that the individual inhibitors affect a wide range of different maturation steps within the ribosome biogenesis pathway. Our results provide for the first time a comprehensive set of inhibitors to study ribosome biogenesis by chemical inhibition of individual maturation steps and establish the process as promising druggable pathway for chemical intervention.

mPGES-1 and ALOX5/-15 in tumor-associated macrophages

The tumor immune landscape gained considerable interest based on the knowledge that genetic aberrations in cancer cells alone are insufficient for tumor development. Macrophages are basically supporting all hallmarks of cancer and owing to their tremendous plasticity they may exert a whole spectrum of anti-tumor and pro-tumor activities. As part of the innate immune response, macrophages are armed to attack tumor cells, alone or in concert with distinct T cell subsets. However, in the tumor microenvironment, they sense nutrient and oxygen gradients, receive multiple signals, and respond to this incoming information with a phenotype shift. Often, their functional output repertoire is shifted to become tumor-supportive. Incoming and outgoing signals are chemically heterogeneous but also comprise lipid mediators. Here, we review the current understanding whereby arachidonate metabolites derived from the cyclooxygenase and lipoxygenase pathways shape the macrophage phenotype in a tumor setting. We discuss these findings in the context of cyclooxygenase-2 (COX-2) and microsomal prostaglandin E synthase-1 (mPGES-1) expression and concomitant prostaglandin E₂ (PGE₂) formation. We elaborate the multiple actions of this lipid in affecting macrophage biology, which are sensors for and generators of this lipid. Moreover, we summarize properties of 5-lipoxygenases (ALOX5) and 15-lipoxygenases (ALOX15, ALOX15B) in macrophages and clarify how these enzymes add to the role of macrophages in a dynamically changing tumor environment. This review will illustrate the potential routes how COX-2/mPGES-1 and ALOX5/-15 in macrophages contribute to the development and progression of a tumor.

Pathway-Based Drug Repositioning for Cancers: Computational Prediction and Experimental Validation

Developing drugs with anticancer activity and low toxic side-effects at low costs is a challenging issue for cancer chemotherapy. In this work, we propose to use molecular pathways as the therapeutic targets and develop a novel computational approach for drug repositioning for cancer treatment. We analyzed chemically induced gene expression data of 1112 drugs on 66 human cell lines and searched for drugs that inactivate pathways involved in the growth of cancer cells (cell cycle) and activate pathways that contribute to the death of cancer cells (e.g., apoptosis and p53 signaling). Finally, we performed a large-scale prediction of potential anticancer effects for all the drugs and experimentally validated the prediction results via three in vitro cellular assays that evaluate cell viability, cytotoxicity, and apoptosis induction. Using this strategy, we successfully identified several potential anticancer drugs. The proposed pathway-based method has great potential to improve drug repositioning research for cancer treatment.

Zileuton suppresses cholangiocarcinoma cell proliferation and migration through inhibition of the Akt signaling pathway

Background

Inflammatory lipid mediators play an important role in several cancer types. Leukotrienes (LTs), pro-inflammatory lipid mediators, are involved in chronic inflammation and cancer progression. They are derived from arachidonic acid by 5-lipoxygenase (5-LOX) activity. On the other hand, 15-lipoxygenase (15-LOX-1) converts LTs into lipoxins (LXs), pro-resolving lipid mediators. LXs are involved in the attenuation of inflammation and cancer development.

Purpose

We aimed to investigate the lipid mediator pathways, especially the LTs and LXs pathways, by studying 5-LOX and 15-LOX-1 expression in human cholangiocarcinoma (CCA) tissue. We also investigated the efficiency of zileuton (5-LOX inhibitor) treatment and BML-111 (LXA4 analog) addition on CCA cell lines properties.

Patients and methods

The expression of 5-LOX and 15-LOX-1 in fifty human cholangiocarcinoma (CCA) tissue was analyzed using immunohistochemical staining. In addition, the effect of zileuton and BML-111 on CCA cell growth and migration was demonstrated using a cell viability assay and wound-healing assay, respectively. Furthermore, the molecular mechanism by which zileuton inhibits CCA cell migration was revealed using immunofluorescent staining and western blot analysis, respectively.

Results

We demonstrate that the upregulation of 5-LOX is significantly correlated with CCA recurrent status. A positive 15-LOX-1 signal was significantly associated with a longer survival time in CCA patients. We found that co-expression of 5-LOX and 15-LOX-1 resulted in a relatively good prognosis in CCA patients. In addition, zileuton could inhibit CCA cell migration as well as BML-111. Interestingly, zileuton treatment not only downregulated 5-LOX, but also upregulated 15-LOX-1, together with reversing the epithelial-mesenchymal transition to mesenchymal-epithelial transition phenotype as observed in EMT marker western blot.

Conclusion

These findings suggest that 5-LOX and 15-LOX-1 play a key role in CCA and may serve as targets for CCA therapy.

Down-regulated paxillin suppresses cell proliferation and invasion by inhibiting M2 macrophage polarization in colon cancer

The paxillin and M2 macrophage are all involved in cell proliferation and tumor progression, and this study aims to explore the interaction between them in colon cancer and the role of paxillin in cancer progression. Expression of mRNAs and proteins was determined by quantitative reverse transcription-polymerase chain reaction (qRT-PCR) and Western blot, separately. Endogenous expression of genes was modulated by recombinant plasmids and cell transfection. The levels of cytokines were determined by enzyme-linked immunosorbent assay (ELISA). The cell viability, invasion and migration were detected using the MTT assay, the transwell assay and the wound-healing cell migration assay, respectively. A nude mouse model for human colon cancer was constructed for tumor orthotopic expression. Paxillin was up-regulated in tumor-associated macrophages (TAMs). Paxillin was up-regulated in process of M2 macrophage polarization. M2 macrophage polarization was inhibited with paxillin suppressed. Down-regulated paxillin inhibited cell proliferation and invasion in colon cancer through suppressing M2 macrophage polarization. PI3k/Akt inhibitor repressed M2 macrophage polarization through down-regulating paxillin. PI3k/Akt inhibitor inhibited the function of the macrophage in promoting cell proliferation and invasion of colon cancer through down-regulating paxillin. Down-regulated paxillin in macrophages inhibited tumor growth of colon cancer. With the PI3K/AKT pathway inhibited, down-regulated paxillin suppressed colon cancer cell proliferation and invasion by inhibiting the M2 macrophage polarization, thereby restraining the tumor progression.

Epigallocatechin-3-gallate reduces the proliferation of benign prostatic hyperplasia cells via regulation of focal adhesions

AIMS

Benign prostatic hyperplasia (BPH) is the most common urological disease that is characterized by the excessive growth of prostatic epithelial and stromal cells. Pharmacological therapy for BPH has limited use due to the many side effects so there is a need for new agents including natural compounds such as epigallocatechin-3-gallate (EGCG). This study was undertaken to assess the role of EGCG, suppressing the formation of BPH by reducing inflammation and oxidative stress, in cytoskeleton organization and ECM interactions via focal adhesions.

MAIN METHODS

We performed MTT assay to investigate cell viability of BPH-1 cells, wound healing assay to examine cell migration, immunofluorescence assay for F-actin organization and paxillin distribution and finally immunoblotting to investigate focal adhesion protein levels in the presence and absence of EGCG.

KEY FINDINGS

We found that EGCG inhibits cell proliferation at the concentration of 89.12μM, 21.2μM and 2.39μM for 24, 48 and 72h, respectively as well as inhibitory effects of EGCG on BPH-1 cell migration were observed in a wound healing assay. Furthermore, it was determined by immunofluorescence labeling that EGCG disrupts F-actin organization and reduces paxillin distribution. Additionally, EGCG decreases the activation of FAK (Focal Adhesion Kinase) and the levels of paxillin, RhoA (Ras homolog gene family, member A), Cdc42 (cell division cycle 42) and PAK1 (p21 protein-activated kinase 1) in a dose-dependent manner.

SIGNIFICANCE

For the first time, by this study, we found evidence that BPH-1 cell proliferation could be inhibited with EGCG through the disruption of cytoskeleton organization and ECM interactions. Consequently, EGCG might be useful in the prevention and treatment of diseases characterized by excessive cell proliferation such as BPH.

Cross-Talk between Cancer Cells and the Tumour Microenvironment: The Role of the 5-Lipoxygenase Pathway

5-lipoxygenase is an enzyme responsible for the synthesis of a range of bioactive lipids signalling molecules known collectively as eicosanoids. 5-lipoxygenase metabolites such as 5-hydroxyeicosatetraenoic acid (5-HETE) and a number of leukotrienes are mostly derived from arachidonic acid and have been shown to be lipid mediators of inflammation in different pathological states including cancer. Upregulated 5-lipoxygenase expression and metabolite production is found in a number of cancer types and has been shown to be associated with increased tumorigenesis. 5-lipoxygenase activity is present in a number of diverse cell types of the immune system and connective tissue. In this review, we discuss potential routes through which cancer cells may utilise the 5-lipoxygenase pathway to interact with the tumour microenvironment during the development and progression of a tumour. Furthermore, immune-derived 5-lipoxygenase signalling can drive both pro- and anti-tumour effects depending on the immune cell subtype and an overview of evidence for these opposing effects is presented.

The Complex Role of Neutrophils in Tumor Angiogenesis and Metastasis

Chronic inflammation fosters cancer development and progression and also modulates tumor responses to anticancer therapies. Neutrophils are key effector cells in innate immunity and are known to play a critical role in various inflammatory disorders. However, the functions of neutrophils in cancer pathogenesis have been largely neglected until recently and still remain poorly characterized compared with other immune cells in the tumor microenvironment. We highlight recent findings on the mechanisms by which tumor cells, in cooperation with tumor-associated stromal cells, induce expansion, recruitment, and polarization of neutrophils. We also review the multifaceted roles that neutrophils play in different aspects of cancer development and progression, with an emphasis on tumor angiogenesis and metastasis.

Synthesis, in vitro anticancer and antibacterial activities and in silico studies of new 4-substituted 1,2,3-triazole-coumarin hybrids

The 4-substituted 1,2,3-triazole core in designed coumarin hybrids (4-35) with diverse physicochemical properties was introduced by eco-friendly copper(I)-catalyzed Huisgen 1,3-dipolar cycloaddition under microwave irradiation. Coumarin-1,2,3-triazole-benzofused heterocycle hybrids emerged as the class of compounds exhibiting the highest antiproliferative activity. The strong relationship between lipophilicity and antiproliferative activities was observed indicating that lipophilic 1,2,3-triazole-coumarin hybrids containing phenylethyl (13), 3,5-difluorophenyl (14), 5-iodoindole (30) and benzimidazole (33 and 35) subunits showed the most potent cytostatic effects. The 7-methylcoumarin-1,2,3-triazole-2-methylbenzimidazole hybrid 33 can be highlighted as a lead that exerted the highest cytotoxicity against hepatocellular carcinoma HepG2 cells with IC₅₀ value of 0.9 μM and high selectivity (SI = 50). This compound induced cell death, mainly due to early apoptosis. Strong antiproliferative effect of 33 could be associated with its inhibition of 5-lipoxygenase (5-LO) activity and perturbation of sphingolipid signaling by interfering with intracellular acid ceramidase (ASAH) activity. Outlined considerable effect of lipophilicity on antiproliferative activity was not observed for antibacterial activity. The compounds with p-pentylphenyl (17), 2-chloro-4-fluorobenzenesulfonamide (23) and dithiocarbamate (27) moiety were endowed with high selectivity against Enterococcus species. Moreover, these compounds were found to be superior in inhibiting the growth of clinically isolated vancomycin-resistant Enterococcus faecium, while the reference antibiotics exhibited the lack of activity. Our findings indicate that coumarin-1,2,3-triazole could be used as the scaffold for structural optimization to develop more potent and selective anticancer agents and encourage further development of novel structurally related analogs of 33 as more effective 5-LO inhibitors.

An integrated network platform for contextual prioritization of drugs and pathways

Repurposing of drugs to novel disease indications has promise for faster clinical translation. However, identifying the best drugs for a given pathological context is not trivial. We developed an integrated random walk-based network framework that combines functional biomolecular relationships and known drug-target interactions as a platform for contextual prioritization of drugs, genes and pathways. We show that the use of gene-centric or drug-centric data, such as gene expression data or a phenotypic drug screen, respectively, within this network platform can effectively prioritize drugs and pathways, respectively, to the studied biological context. We demonstrate that various genomic data can be used as contextual cues to effectively prioritize drugs to the studied context, while similarly, phenotypic drug screen data can be used to effectively prioritize genes and pathways to the studied phenotypic context. As a proof-of-principle, we showcase the use of our platform to identify known and novel drug indications against different subsets of breast cancers through contextual prioritization based on genome-wide gene expression, shRNA and drug screen and clinical survival data. The integrated network and associated methods are incorporated into the NetWalker suite for functional genomics analysis ().

5-lipoxygenase mediates docosahexaenoyl ethanolamide and N-arachidonoyl-L-alanine-induced reactive oxygen species production and inhibition of proliferation of head and neck squamous cell carcinoma cells

Background

Endocannabinoids have recently drawn attention as promising anti-cancer agents. We previously observed that anandamide (AEA), one of the representative endocannabinoids, effectively inhibited the proliferation of head and neck squamous cell carcinoma (HNSCC) cell lines in a receptor-independent manner. In this study, using HNSCC cell lines, we examined the anti-cancer effects and the mechanisms of action of docosahexaenoyl ethanolamide (DHEA) and N-arachidonoyl-L-alanine (NALA), which are polyunsaturated fatty acid (PUFA)-based ethanolamides like AEA.

Methods and Results

DHEA and NALA were found to effectively inhibit HNSCC cell proliferation. These anti-proliferative effects seemed to be mediated in a cannabinoid receptor-independent manner, since the antagonist of cannabinoid receptor-1 (CB1) and vanilloid receptor-1 (VR1), two endocannabinoid receptors, did not reverse the ability of DHEA and NALA to induce cell death. Instead, we observed an increase in reactive oxygen species (ROS) production and a decrease of phosphorylated Akt as a result of DHEA and NALA treatment. Antioxidants efficiently reversed the inhibition of cell proliferation and the decrease of phosphorylated Akt induced by DHEA and NALA; inhibition of 5-lipoxygenase (5-LO), which is expected to be involved in DHEA- and NALA-degradation pathway, also partially blocked the ability of DHEA and NALA to inhibit cell proliferation and phosphorylated Akt. Interestingly, ROS production as a result of DHEA and NALA treatment was decreased by inhibition of 5-LO.

Conclusions

From these findings, we suggest that ROS production induced by the 5-LO pathway mediates the anti-cancer effects of DHEA and NALA on HNSCC cells. Finally, our findings suggest the possibility of a new cancer-specific therapeutic strategy, which utilizes 5-LO activity rather than inhibiting it.

Electronic supplementary material

The online version of this article (doi:10.1186/s12885-016-2499-3) contains supplementary material, which is available to authorized users.

Erlotinib augmentation with dapsone for rash mitigation and increased anti-cancer effectiveness

BACKGROUND

The epidermal growth factor receptor tyrosine kinase inhibitor erlotinib has failed in many ways to be as potent in the anti-cancer role as pre-clinical studies would have suggested. This paper traces some aspects of this failure to a compensatory erlotinib-mediated increase in interleukin-8. Many other-but not all- cancer chemotherapeutic cytotoxic drugs also provoke a compensatory increase in a malignant clone's interleukin-8 synthesis. Untreated glioblastoma and other cancer cells themselves natively synthesize interleukin-8. Interleukin-8 has tumor growth promoting, mobility and metastasis formation enhancing, effects as well as pro-angiogenesis effects.

FINDINGS

The old sulfone antibiotic dapsone- one of the very first antibiotics in clinical use- has demonstrated several interleukin-8 system inhibiting actions. Review of these indicates dapsone has potential to augment erlotinib effectiveness. Erlotinib typically gives a rash that has recently been proven to come about via an erlotinib triggered up-regulated keratinocyte interleukin-8 synthesis. The erlotinib rash shares histological features reminiscent of typical neutrophilic dermatoses. Dapsone has an established therapeutic role in current treatment of other neutrophilic dermatoses.

CONCLUSION

Thus, dapsone has potential to both improve the quality of life in erlotinib treated patients by amelioration of rash as well as to short-circuit a growth-enhancing aspect of erlotinib when used in the anti-cancer role.

Cytoplasmic 5-Lipoxygenase Staining Is a Highly Sensitive Marker of Human Tumors of the Choroid Plexus

OBJECTIVES

To determine the immunoreactivity status of 5-lipoxygenase (5-LO) in normal tissues, in tumors of the human choroid plexus, and in other brain tumors.

METHODS

In total, 135 cases of various types of brain tumors were selected. Tissue samples were immunostained with a rabbit polyclonal anti-5-LO antibody.

RESULTS

Nuclear reactivity was observed in most brain tumors, with most of the positive tumor cells exhibiting low-level reactivity. Cytoplasmic strong immunoreactivity for 5-LO (2+ or 3+) was only observed in 8.8% of astrocytic tumors, 0% of oligodendrogliomatous tumors, 5.6% of ependymal tumors, 0% of embryonal tumors, 3.1% of meningeal tumors, and 0% of metastatic lung adenocarcinomas. In contrast, cytoplasmic immunoreactivity for 5-LO was detected in all 27 cases of choroid plexus tumors. Twenty-five cases showed strong and diffuse cytoplasmic immunoreactivity.

CONCLUSIONS

Our findings indicate that cytoplasmic 5-LO immunoreactivity is highly characteristic of human choroid plexus tumors but not other central nervous system tumor types. Cytoplasmic staining for 5-LO may prove to be a useful immunoreactive marker in the diagnosis of choroid plexus tumors.

Potency of non-steroidal anti-inflammatory drugs in chemotherapy

Cancer cell resistance, particularly multidrug resistance (MDR), is the leading cause of chemotherapy failure. A number of mechanisms involved in the development of MDR have been described, including the overexpression of ATP-dependent membrane-bound transport proteins. The enhanced expression of these proteins, referred to as ATP-binding cassette (ABC) transporters, results in an increased cellular efflux of the cytotoxic drug, thereby reducing its intracellular concentration to an ineffective level. Non-steroidal anti-inflammatory drugs (NSAIDs) are the most frequently consumed drugs worldwide. NSAIDs are mainly used to treat pain, fever and inflammation. Numerous studies suggest that NSAIDs also show promise as anticancer drugs. NSAIDs have been shown to reduce cancer cell proliferation, motility, angiogenesis and invasiveness. In addition to these effects, NSAIDs have been shown to induce apoptosis in a wide variety of cancer types. Moreover, several studies have indicated that NSAIDs may sensitise cancer cells to the antiproliferative effects of cytotoxic drugs by modulating ABC transporter activity. Therefore, combining specific NSAIDs with chemotherapeutic drugs may have clinical applications. Such treatments may allow for the use of a lower dose of cytotoxic drugs and may also enhance the effectiveness of therapy. The objective of this review was to discuss the possible role of NSAIDs in the modulation of antitumour drug cytotoxicity. We particularly emphasised on the use of COX-2 inhibitors in combination with chemotherapy and the molecular and cellular mechanisms underlying the alterations in outcome that occur in response to this combination therapy.