Experimental survey of non-clonogenic viability assays for adherent cells in vitro

Molecular Effects of Iodine-Biofortified Lettuce in Human Gastrointestinal Cancer Cells

Considering the growing number of cancer cases around the world, natural products from the diet that exhibit potential antitumor properties are of interest. Our previous research demonstrated that fortification with iodine compounds is an effective way to improve the antioxidant potential of lettuce. The purpose of the present study was to evaluate the effect of iodine-biofortified lettuce on antitumor properties in human gastrointestinal cancer cell lines, gastric AGS and colon HT-29. Our results showed that extracts from iodine-biofortified lettuce reduce the viability and proliferation of gastric and colon cancer cells. The extracts mediated cell cycle arrest which was accompanied by inactivation of anti-apoptotic Bcl-2 and activation of caspases, as assessed by flow cytometry. However, extracts from lettuce fortified with organic forms of iodine acted more effectively than extracts from control and KIO3-enriched plants. Using quantitative PCR, we detected the increase in pro-apoptotic genes BAD, BAX and BID in AGS cells whereas up-regulation of cell cycle progression inhibitor CDKN2A and downregulation of pro-proliferative MDM2 in HT-29 cells. Interestingly, lettuce extracts led to down-regulation of pro-survival AKT1 and protooncogenic MDM2, which was consistent for extracts of lettuce fortified with organic form of iodine, 5-ISA, in both cell lines. MDM2 downregulation in HT-29 colon cancer cells was associated with RB1 upregulation upon 5-ISA-fortified lettuce extracts, which provides a link to the epigenetic regulation of tumor suppressor genes by RB/MDM2 pathway. Indeed, SEMA3A tumor suppressor gene was hypomethylated and upregulated in HT-29 cells treated with 5-ISA-fortified lettuce. Control lettuce exerted similar effects on RB/MDM2 pathway and SEMA3A epigenetic activation in HT-29 cells. Our findings suggest that lettuce as well as lettuce fortified with organic form of iodine, 5-ISA, may exert epigenetic anti-cancer effects that can be cancer type-specific.

The amount of dextran in PLGA nanocarriers modulates protein corona and promotes cell membrane damage

Polymeric nanocarriers (NCs) are efficient vehicles to prevent drug unspecific biodistribution and increase the drug amounts delivered to tumor tissues. However, some toxicological aspects of NCs still lack a comprehensive assessment, such as their effects on cellular processes that lead to toxicity. We evaluate the interaction of poly(lactic-co-glycolic acid) (PLGA) NCs prepared using dextran (Dex) and Pluronic®-F127 as stabilizing agents with myocardial cells (H9C2), breast adenocarcinoma cells (MCF-7) and macrophages (RAW 264.7) to address the effect of Dex in PLGA NC formulations. By an emulsion diffusion method, doxorubicin-loaded NCs were prepared with no Dex (PLGA-DOX), 1% (w/v) Dex (Dex1/PLGA-DOX) and 5% (w/v) Dex (Dex5/PLGA-DOX). Uptake analyses revealed a significant reduction in Dex5/PLGA-DOX NC uptake by H9C2 and MCF-7, as in the case of Dex1/PLGA-DOX NCs in the absence of in vitro protein corona, revealing an effect of dextran concentration on the formation of protein corona. RAW 264.7 cells presented a greater uptake of Dex5/PLGA-DOX NCs than the other NCs likely because of receptor mediated endocytosis, since C-type lectins like SIGN-R1, mannose receptors and scavenger receptor type 1 that are expressed in RAW 264.7 can mediate Dex uptake. Despite the lower uptake, Dex5/PLGA-DOX NCs promote the generation of reactive oxygen species and oxidative membrane damage in MCF-7 and H9C2 even though cellular metabolic activity assessed by MTT was comparable among all the NCs. Our results highlight the importance of an in-depth investigation of the NC-cell interaction considering additional mechanisms of damage apart from metabolic variations, as nanoparticle-induced damage is not limited to imbalance in metabolic processes, but also associated with other mechanisms, e.g., membrane and DNA damage.

Antibacterial metal-phenolic nanosheets as smart carriers for the controlled release of epirubicin hydrochloride

Bacterial infections can cause serious complications in cancer treatment and have been proven to weaken therapeutic benefits. Recently, antibacterial nanomaterials that serve as carriers for anticancer drug delivery have been attracting extensive interest due to their combined antimicrobial and anticancer activities. In this study, antibacterial metal-phenolic nanosheets (Cu-TA) were successfully prepared via the self-assembly of the metal-phenolic coordination complexes formed between copper ions and tannic acid, and the structure, morphology, and formation mechanism of Cu-TA nanosheets were explored. The antibacterial activity of Cu-TA nanosheets against both Gram-positive and Gram-negative bacteria was detected using the minimum inhibitory concentration (MIC), zone of inhibition and plate counting methods. The MIC values of both bacterial strains were about 0.4 mg mL^-1, and the killing rates of Cu-TA samples were close to 100% at the concentration of 2 and 0.2 mg mL^-1 after 12-hour incubation. Epirubicin hydrochloride (EPI) molecules were successfully loaded on the porous Cu-TA nanosheets mainly through the formation of the Cu-EPI chelate complex and strong electrostatic interactions. The Cu-EPI complex and Cu-TA nanosheets could be disassembled under acidic conditions or in the presence of high levels of glutathione (GSH) after uptake by cancer cells, which triggered the unique pH and GSH-responsive controlled release behaviors of EPI and copper ions. The MTT assay results revealed that the presence of bacteria in Hep G2 cells can greatly impair the cell death rate induced by free EPI, but the resultant EPI-loaded Cu-TA nanosheets can significantly enhance cell death both in the presence and absence of bacteria.

A colon-targeted podophyllotoxin nanoprodrug: synthesis, characterization, and supramolecular hydrogel formation for the drug combination

Making full use of the undeveloped bioactive natural product derivatives by selectively delivering them to target sites can effectively increase their druggability and reduce the wastage of resources. Azo-based prodrugs are widely regarded as an effective targeted delivery means for colon-related disease treatment. Herein, we report a new-type of azo-based nanoprodrug obtained from bioactive natural products, in which the readily available podophyllotoxin natural products are connected with methoxy polyethylene glycol (mPEG) via a multifunctional azobenzene group. The amphiphilic prodrug can form nanosized micelles in water and will be highly selectively activated by azoreductases, leading to the in situ generation of anticancer podophyllotoxin derivatives (AdP) in the colon after the cleavage of the azo bond. To satisfy the demand of drug carriers for cancer combination therapy in clinics, α-CD is further introduced into this nanoprodrug micelle system to form a supramolecular hydrogel via a cascade self-assembly strategy. Using imaging mass spectrometry (IMS), the colon-specific drug release ability of the hydrogel after oral administration is demonstrated at the molecular level. Finally, the nanoprodrug hydrogel is further used as a carrier to load a hydrophilic anti-cancer drug 5-FU during the hierarchical self-assembly process and to co-deliver AdP and 5-FU for the drug combination. The combination use of AdP and 5-FU provides enhanced cytotoxicity which indicates a significant synergistic interaction. This work offers a new way to enhance the therapeutic effect of nanoprodrugs via drug combination, and provides a new strategy for reusing bioactive natural products and their derivatives.

Non-Specific Antibodies Induce Lysosomal Activation in Atlantic Salmon Macrophages Infected by Piscirickettsia salmonis

Piscirickettsia salmonis, an aggressive intracellular pathogen, is the etiological agent of salmonid rickettsial septicemia (SRS). This is a chronic multisystemic disease that generates high mortalities and large losses in Chilean salmon farming, threatening the sustainability of the salmon industry. Previous reports suggest that P. salmonis is able to survive and replicate in salmonid macrophages, inducing an anti-inflammatory environment and a limited lysosomal response that may be associated with host immune evasion mechanisms favoring bacterial survival. Current control and prophylaxis strategies against P. salmonis (based on the use of antibiotics and vaccines) have not had the expected success against infection. This makes it urgent to unravel the host-pathogen interaction to develop more effective therapeutic strategies. In this study, we evaluated the effect of treatment with IgM-beads on lysosomal activity in Atlantic salmon macrophage-enriched cell cultures infected with P. salmonis by analyzing the lysosomal pH and proteolytic ability through confocal microscopy. The impact of IgM-beads on cytotoxicity induced by P. salmonis in infected cells was evaluated by quantification of cell lysis through release of Lactate Dehydrogenase (LDH) activity. Bacterial load was determined by quantification of 16S rDNA copy number by qPCR, and counting of colony-forming units (CFU) present in the extracellular and intracellular environment. Our results suggest that stimulation with antibodies promotes lysosomal activity by lowering lysosomal pH and increasing the proteolytic activity within this organelle. Additionally, incubation with IgM-beads elicits a decrease in bacterial-induced cytotoxicity in infected Atlantic salmon macrophages and reduces the bacterial load. Overall, our results suggest that stimulation of cells infected by P. salmonis with IgM-beads reverses the modulation of the lysosomal activity induced by bacterial infection, promoting macrophage survival and bacterial elimination. This work represents a new important evidence to understand the bacterial evasion mechanisms established by P. salmonis and contribute to the development of new effective therapeutic strategies against SRS.

Significance of Notch and Wnt signaling for chemoresistance of colorectal cancer cells HCT116

5-fluorouracil (5-FU) and oxaliplatin (OxaPt) are the main chemotherapeutics for colorectal cancer (CRC). Chemotherapy response rates for advanced CRC remain low, primarily due to intrinsic or acquired chemoresistance. The importance of Notch and Wnt signaling for carcinogenesis of CRC as well as crosstalk of Notch and Wnt signaling with many oncogenic signaling pathways suggest that Notch and Wnt pathways could be responsible for chemoresistance. In this study, we compared changes in Notch and Wnt signaling after 5-FU and OxaPt treatment in CRC cells HCT116 and its chemoresistant sublines HCT116/FU and HCT116/OXA. The levels of Notch1 receptor intracellular domain NICD1 and non-phosphorylated β-catenin, the reporters of Notch and Wnt signaling, were upregulated in untreated chemoresistant HCT116/FU and HCT116/OXA cells. Our data suggest that Notch inhibitor RO4929097 (RO) and Wnt inhibitor XAV939 (XAV) enhance the survival potential of OxaPt-treated cells. The protein level of Notch target gene HES1 was significantly upregulated in chemoresistant HCT116/FU and HCT116/OXA cells, compared to HCT116. HES1 silencing increased viability of HCT116 and its chemoresistant sublines after 5-FU or OxaPt treatment. The results of HES1 downregulation coincide with RO and XAV effects on cell viability of OxaPt-treated cells.

Targeting tissue factor as a novel therapeutic oncotarget for eradication of cancer stem cells isolated from tumor cell lines, tumor xenografts and patients of breast, lung and ovarian cancer

Targeting cancer stem cell (CSC) represents a promising therapeutic approach as it can potentially fight cancer at its root. The challenge is to identify a surface therapeutic oncotarget on CSC. Tissue factor (TF) is known as a common yet specific surface target for cancer cells and tumor neovasculature in several solid cancers. However, it is unknown if TF is expressed by CSCs. Here we demonstrate that TF is constitutively expressed on CD133 positive (CD133+) or CD24-CD44+ CSCs isolated from human cancer cell lines, tumor xenografts from mice and breast tumor tissues from patients. TF-targeted agents, i.e., a factor VII (fVII)-conjugated photosensitizer (fVII-PS for targeted photodynamic therapy) and fVII-IgG1Fc (Immunoconjugate or ICON for immunotherapy), can eradicate CSC via the induction of apoptosis and necrosis and via antibody-dependent cellular cytotoxicity and complement-dependent cytotoxicity, respectively. In conclusion, these results demonstrate that TF is a novel surface therapeutic oncotarget for CSC, in addition to cancer cell TF and tumor angiogenic vascular endothelial TF. Moreover, this research highlights that TF-targeting therapeutics can effectively eradicate CSCs, without drug resistance, isolated from breast, lung and ovarian cancer with potential to translate into other most commonly diagnosed solid cancer, in which TF is also highly expressed.

VPS52 induces apoptosis via cathepsin D in gastric cancer

Vacuolar protein sorting (VPS) genes encode a class of proteins involved in vesicular trafficking. Growing evidence suggests that VPS proteins play roles in tumor biology. Vacuolar protein sorting 52 (VPS52) is involved in retrograde transport of endosomes, and its roles in cancers have not been explored. This study investigated the genetic alterations, protein changes, biological role, and molecular mechanism of VPS52 in gastric cancer. Loss of heterozygosity of VPS52 was detected in 52.9% (9/17) of gastric cancer samples. Twenty-five percent (5/20) gastric cancer samples contained somatic stop-gain mutation of VPS52, two of which also had simultaneous loss of heterozygosity. Lack of VPS52 protein expression in gastric cancer tissue was found compared with pericancerous tissue and was significantly correlated with more advanced TNM staging and shorter 3-year overall survival. Overexpression of VPS52 significantly reduced viability and increased apoptosis in gastric cancer cells in vitro and reduced tumor volume and tumor weight in xenograft model in vivo. Activation of the cathepsin D/Bax/cytochrome C/caspase 9/caspase 3 pathway was detected in gastric cancer cells overexpressing VPS52. Collectively, VPS52 is a tumor suppressor gene in gastric cancer and could be used as a biomarker. VPS52 adenovirus could be a novel anti-tumor reagent for future gene therapy.

KEY MESSAGES

Loss of heterozygosity and stop-gain mutation of VPS52 were found in gastric cancer. Negative expression of VPS52 significantly correlated with poor prognosis. VPS52 inhibited viability and induced apoptosis of gastric cancer cells in vitro. VPS52 reduced tumor volume and tumor weight in vivo. VPS52 activated the apoptotic pathway through cathepsin D in gastric cancer cells.

Synthesis, cytotoxicity and anti-cancer activity of new alkynyl-gold(i) complexes

Alkynyl(triphenylphosphine)gold(i) complexes carrying variously substituted propargylic amines have been synthesized and fully characterized in solution and solid state.

Nanoencapsulation of the sasanquasaponin from Camellia oleifera, its photo responsiveness and neuroprotective effects

Sasanquasaponin, a bioactive compound isolated from seeds of Camellia oleifera, shows central effects in our previous research. In order to investigate its neuroprotective effects, a new kind of nanocapsule with photo responsiveness was designed to deliver sasanquasaponin into the brain and adjusted by red light. The nanocapsule was prepared using sasanquasaponin emulsified with soybean lecithin and cholesterol solution. The natural phaeophorbide from silkworm excrement as a photosensitizer was added in the lipid phase to make the nanocapsules photo responsive. The physicochemical properties of encapsulation efficiency, size distribution, morphology and stability were measured using high-performance liquid chromatography, particle size analyzer, transmission electron microscope, differential scanning calorimetry and thermogravimetry. Photo responsiveness was determined by the sasanquasaponin release in pH 7.5 phosphate buffer under the laser at 670 nm. The neuroprotective effects were evaluated by the expression of tyrosine hydroxylase (TH), decrease of inflammatory cytokines TNF-α and IL-1β in the brain, and amelioration of kainic acid-induced behavioral disorder in mice. The nanocapsules had higher encapsulation efficiency and stability when the phaeophorbide content was 2% of lecithin weight. The average size was 172.2 nm, distributed in the range of 142-220 nm. The phaeophorbide was scattered sufficiently in the outer lecithin layer of the nanocapsules and increased the drug release after irradiation. TH expression in brain tissues and locomotive activities in mice were reduced by kainic acid, but could be improved by the sasanquasaponin nanocapsules after tail vein injection with 15 minutes of irradiation at the nasal cavity. The sasanquasaponin took effect through inflammatory alleviation in central tissues. The sasanquasaponin nanocapsules with phaeophorbide have photo responsiveness and neuroprotective effects under the irradiation of red light. This preparation presents a new approach to brain neuroprotection, and has potential for clinical application.

Short term exposure to elevated levels of leptin reduces proximal tubule cell metabolic activity

Leptin plays a pathophysiological role in the kidney, however, its acute effects on the proximal tubule cells (PTCs) are unknown. In opossum kidney (OK) cells in vitro, Western blot analysis identified that exposure to leptin increases the phosphorylation of the mitogen-activated protein kinase (MAPK) p44/42 and the mammalian target of rapamycin (mTOR). Importantly leptin (0.05, 0.10, 0.25 and 0.50 μg/ml) significantly reduced the metabolic activity of PTCs, and significantly decreased protein content per cell. Investigation of the role of p44/42 and mTOR on metabolic activity and protein content per cell, demonstrated that in the presence of MAPK inhibitor U0126 and mTOR inhibitor Ku-63794, that the mTOR pathway is responsible for the reduction in PTC metabolic activity in response to leptin. However, p44/42 and mTOR play no role the reduced protein content per cell in OKs exposed to leptin. Therefore, leptin modulates metabolic activity in PTCs via an mTOR regulated pathway.

A comprehensive tutorial on in vitro characterization of new photosensitizers for photodynamic antitumor therapy and photodynamic inactivation of microorganisms

In vitro research performed on eukaryotic or prokaryotic cell cultures usually represents the initial step for characterization of a novel photosensitizer (PS) intended for application in photodynamic therapy (PDT) of cancer or photodynamic inactivation (PDI) of microorganisms. Although many experimental steps of PS testing make use of the wide spectrum of methods readily employed in cell biology, special aspects of working with photoactive substances, such as the autofluorescence of the PS molecule or the requirement of light protection, need to be considered when performing in vitro experiments in PDT/PDI. This tutorial represents a comprehensive collection of operative instructions, by which, based on photochemical and photophysical properties of a PS, its uptake into cells, the intracellular localization and photodynamic action in both tumor cells and microorganisms novel photoactive molecules may be characterized for their suitability for PDT/PDI. Furthermore, it shall stimulate the efforts to expand the convincing benefits of photodynamic therapy and photodynamic inactivation within both established and new fields of applications and motivate scientists of all disciplines to get involved in photodynamic research.

Cell damage following carbon monoxide releasing molecule exposure: implications for therapeutic applications

The cytoprotective properties of carbon monoxide (CO) gas and CO-releasing molecules (CORMs) are well established. Despite promising pre-clinical results, little attention has been paid to the toxicological profile of CORMs. The effects of CORM-2 and its CO-depleted molecule (iCORM-2) (20-400 μM) were compared in primary rat cardiomyocytes and two cell lines [human embryonic kidney (HeK) and Madine-Darby canine kidney Cells (MDCK)]. Cells were assessed for cell viability, apoptosis, necrosis, cytology, mitochondrial energetics, oxidative stress and cell cycle arrest markers. In separate experiments, the anti-apoptotic effects of CORM-2 and i-CORM-2 treatment were compared against CO gas treatment in HeK and MDCK lines. H(2)O(2) -induced cellular damage, measured by lactate dehydrogenase (LDH) release from primary cardiomyocytes, was reduced by 20 μM CORM-2; LDH activity, however, was directly inhibited by 400 μM CORM-2. Both CORM-2/iCORM-2 and CO gas decreased cisplatin-induced caspase-3 activity in MDCK and HeK cells suggesting an anti-apoptotic effect. Conversely, both CORM-2 and iCORM-2 induced significant cellular toxicity in the form of decreased cell viability, abnormal cell cytology, increased apoptosis and necrosis, cell cycle arrest and reduced mitochondrial enzyme activity. Comparison of these markers after CO gas administration to MDCK cells found significantly less cellular toxicity than in 100 μM CORM-2/iCORM-2-treated cells. CO gas did not have an adverse effect on mitochondrial energetics and integrity. Release of CO by low concentrations of intact CORM-2 molecules provides cytoprotective effects. These results show, however, that the ruthenium-based CORM by-product, iCORM-2, is cytotoxic and suggest that the accumulation of iCORM-2 would seriously limit any clinical application of the ruthenium-based CORMs.

Toxicological considerations when creating nanoparticle-based drugs and drug delivery systems

INTRODUCTION

The biggest challenge faced by the scientific community involved in drug development is to deliver safe and effective dosage of drugs without causing systemic toxicity. Therefore, novel nano-based delivery vehicles specifically targeting tumors but not normal tissues are urgently needed.

AREAS COVERED

Nanoparticles have beneficial aspects but can be toxic themselves, which is always a concern for any drug or delivery agent. This review examines and details the toxicological aspects that should be considered when planning to use nanoparticles in animals or in man for drug delivery or imaging. Subjects discussed in this review include i) overviews of applications of various nanoparticles for drug delivery and imaging; ii) toxicological aspects to consider when selecting particular nanoparticles for use in various applications in animals or man; iii) hurdles faced when examining nanoparticle toxicity; and iv) current approaches for assessing nanoparticle toxicity.

EXPERT OPINION

Nanotechnology has significant potential for advancing therapeutic efficacy and imaging in cancer; however, these agents can be toxic. Therefore, toxicity needs to be considered when selecting nanoparticles for a particular application. Methods for assessing nanoparticle toxicity need to be improved and standardized across all nanotechnology platforms in order to speed up the application of nanoparticle use in humans.

Temoporfin (Foscan®, 5,10,15,20-tetra(m-hydroxyphenyl)chlorin)--a second-generation photosensitizer

This review traces the development and study of the second-generation photosensitizer 5,10,15,20-tetra(m-hydroxyphenyl)chlorin through to its acceptance and clinical use in modern photodynamic (cancer) therapy. The literature has been covered up to early 2011.

Effective treatment of chemoresistant breast cancer in vitro and in vivo by a factor VII-targeted photodynamic therapy

Background:

The purpose of this study was to test a novel, dual tumour vascular endothelial cell (VEC)- and tumour cell-targeting factor VII-targeted Sn(IV) chlorin e6 photodynamic therapy (fVII-tPDT) by targeting a receptor tissue factor (TF) as an alternative treatment for chemoresistant breast cancer using a multidrug resistant (MDR) breast cancer line MCF-7/MDR.

Methods:

The TF expression by the MCF-7/MDR breast cancer cells and tumour VECs in MCF-7/MDR tumours from mice was determined separately by flow cytometry and immunohistochemistry using anti-human or anti-murine TF antibodies. The efficacy of fVII-tPDT was tested in vitro and in vivo and was compared with non-targeted PDT for treatment of chemoresistant breast cancer. The in vitro efficacy was determined by a non-clonogenic assay using crystal violet staining for monolayers, and apoptosis and necrosis were assayed to elucidate the underlying mechanisms. The in vivo efficacy of fVII-tPDT was determined in a nude mouse model of subcutaneous MCF-7/MDR tumour xenograft by measuring tumour volume.

Results:

To our knowledge, this is the first presentation showing that TF was expressed on tumour VECs in chemoresistant breast tumours from mice. The in vitro efficacy of fVII-tPDT was 12-fold stronger than that of ntPDT for MCF-7/MDR cancer cells, and the mechanism of action involved induction of apoptosis and necrosis. Moreover, fVII-tPDT was effective and safe for the treatment of chemoresistant breast tumours in the nude mouse model.

Conclusions:

We conclude that fVII-tPDT is effective and safe for the treatment of chemoresistant breast cancer, presumably by simultaneously targeting both the tumour neovasculature and chemoresistant cancer cells. Thus, this dual-targeting fVII-tPDT could also have therapeutic potential for the treatment of other chemoresistant cancers.

Cellular chemosensitivity assays: an overview

Data on cell viability have long been obtained from in vitro cytotoxicity assays. Today, there is a focus on markers of cell death, and the MTT cell survival assay is widely used for measuring cytotoxic potential of a compound. However, a comprehensive evaluation of cytotoxicity requires additional assays which -measure short and long-term cytotoxicity. Assays which measure the cytostatic effects of compounds are not less important, particularly for newer anticancer agents. This overview discusses the advantages and disadvantages of different non-clonogenic assays for measuring short and medium-term cytotoxicity. It also discusses clonogenic assays, which accurately measure long-term cytostatic effects of drugs and toxic agents. For certain compounds and cell types, the advent of high throughput, multiparameter, cytotoxicity assays, and gene expression assays have made it possible to predict cytotoxic potency in vivo.

Comparison of methods for measuring viable E. coli cells during cultivation: great differences in the early and late exponential growth phases

Four methods, namely enumeration of colony-forming units (CFU), aerobic respiration, MTT reduction capacity and succinate dehydrogenase activity were compared to determine the viability of E. coli cells at the early and late exponential growth phases. Our results revealed that great differences in cell viability existed between these methods and that the choice of method to determine cell viability must be made with caution.

Protective role of ortho-substituted Mn(III) N-alkylpyridylporphyrins against the oxidative injury induced by tert-butylhydroperoxide

The present work addresses the role of two ortho-substituted Mn(III) N-alkylpyridylporphyrins, alkyl being ethyl in MnTE-2-PyP(5+) and n-hexyl in MnTnHex-2-PyP(5+), on the protection against the oxidant tert-butylhydroperoxide (TBHP). Their protective role was studied in V79 cells using endpoints of cell viability (MTT and crystal violet assays), intracellular O(2)*- generation (dihydroethidium assay) and glutathione status (DTNB and monochlorobimane assays). MnPs per se did not show cytotoxicity (up to 25 microM, 24 h). The exposure to TBHP resulted in a significant decrease in cell viability and in an increase in the intracellular O(2)(*-) levels. Also, TBHP depleted total and reduced glutathione and increased GSSG. The two MnPs counteracted remarkably the effects of TBHP. Even at low concentrations, both MnPs were protective in terms of cell viability and abrogated the intracellular O(2)(*-) increase in a significant way. Also, they augmented markedly the total and reduced glutathione contents in TBHP-treated cells, highlighting the multiple mechanisms of protection of these SOD mimics, which at least in part may be ascribed to their electron-donating ability.

Selective and effective killing of angiogenic vascular endothelial cells and cancer cells by targeting tissue factor using a factor VII-targeted photodynamic therapy for breast cancer

The cell surface receptor tissue factor (TF) is regarded as a common but specific target on angiogenic tumor vascular endothelial cells (VECs) and tumor cells in many types of cancer including breast cancer. The purpose of this study is to develop a selective and effective TF-targeting photodynamic therapy (PDT) by using its natural ligand factor VII (fVII)-conjugated Sn(IV) chlorin e6 (SnCe6) for the treatment of breast cancer. A cross linker EDC was used to covalently conjugate fVII protein to SnCe6, and the binding activity and phototoxicity was confirmed by ELISA and in vitro PDT. The efficacy of fVII-tPDT was assessed in vitro by crystal violet staining assay and in vivo by measuring tumor size in mice carrying murine or human breast cancer xenografts. We show that active site-mutated (K341A) fVII protein can be internalized into breast cancer cells and vascular endothelial growth factor (VEGF)-stimulated human umbilical vein endothelial cells (HUVECs) as angiogenic VECs. fVII-tPDT not only enhances 12-fold the in vitro efficacy but also selectively and effectively kills angiogenic HUVECs and breast cancer cells via specifically binding of fVII to TF and inducing apoptosis and necrosis as the underlying mechanism. Furthermore, fVII-tPDT can significantly inhibit the tumor growth of murine and human breast cancer without obvious toxicities in mice. We conclude that fVII-tPDT using fVII-SnCe6 conjugate can selectively and effectively kill angiogenic VECs and breast cancer cells in vitro and significantly inhibit the tumor growth of murine and human breast cancer in mice.

Targeting tissue factor on tumour cells and angiogenic vascular endothelial cells by factor VII-targeted verteporfin photodynamic therapy for breast cancer in vitro and in vivo in mice

Background

The objective of this study was to develop a ligand-targeted photodynamic therapy (tPDT) by conjugating factor VII (fVII) protein with photosensitiser verteporfin in order to overcome the poor selectivity and enhance the effect of non-targeted PDT (ntPDT) for cancer. fVII is a natural ligand for receptor tissue factor (TF) with high affinity and specificity. The reason for targeting receptor TF for the development of tPDT is that TF is a common but specific target on angiogenic tumour vascular endothelial cells (VEC) and many types of tumour cells, including solid tumours and leukaemia.

Methods

Murine factor VII protein (mfVII) containing a mutation (Lys341Ala) was covalently conjugated via a cross linker EDC with Veterporfin (VP) that was extracted from liposomal Visudyne, and then free VP was separated by Sephadex G50 spin columns. fVII-tPDT using mfVII-VP conjugate, compared to ntPDT, was tested in vitro for the killing of breast cancer cells and VEGF-stimulated VEC and in vivo for inhibiting the tumour growth of breast tumours in a mouse xenograft model.

Results

We showed that: (i) fVII protein could be conjugated with VP without affecting its binding activity; (ii) fVII-tPDT could selectively kill TF-expressing breast cancer cells and VEGF-stimulated angiogenic HUVECs but had no side effects on non-TF expressing unstimulated HUVEC, CHO-K1 and 293 cells; (iii) fVII targeting enhanced the effect of VP PDT by three to four fold; (iii) fVII-tPDT induced significantly stronger levels of apoptosis and necrosis than ntPDT; and (iv) fVII-tPDT had a significantly stronger effect on inhibiting breast tumour growth in mice than ntPDT.

Conclusions

We conclude that the fVII-targeted VP PDT that we report here is a novel and effective therapeutic with improved selectivity for the treatment of breast cancer. Since TF is expressed on many types of cancer cells including leukaemic cells and selectively on angiogenic tumour VECs, fVII-tPDT could have broad therapeutic applications for other solid cancers and leukaemia.

Synergistic effects of the membrane actions of cecropin-melittin antimicrobial hybrid peptide BP100

BP100 (KKLFKKILKYL-NH(2)) is a short cecropin A-melittin hybrid peptide, obtained through a combinatorial chemistry approach, which is highly effective in inhibiting both the in vitro and in vivo growth of economically important plant pathogenic Gram-negatives. The intrinsic Tyr fluorescence of BP100 was taken advantage of to study the peptide's binding affinity and damaging effect on phospholipid bilayers modeling the bacterial and mammalian cytoplasmic membranes. In vitro cytotoxic effects of this peptide were also studied on mammalian fibroblast cells. Results show a stronger selectivity of BP100 toward anionic bacterial membrane models as indicated by the high obtained partition constants, one order of magnitude greater than for the neutral mammalian membrane models. For the anionic systems, membrane saturation was observed at high peptide/lipid ratios and found to be related with BP100-induced vesicle permeabilization, membrane electroneutrality, and vesicle aggregation. Occurrence of BP100 translocation was unequivocally detected at both high and low peptide/lipid ratios using a novel and extremely simple method. Moreover, cytotoxicity against mammalian models was reached at a concentration considerably higher than the minimum inhibitory concentration. Our findings unravel the relationships among the closely coupled processes of charge neutralization, permeabilization, and translocation in the mechanism of action of antimicrobial peptides.

Calcitriol treatment improves methyl aminolaevulinate-based photodynamic therapy in human squamous cell carcinoma A431 cells

BACKGROUND

Photodynamic therapy (PDT) using methyl aminolaevulinate (MAL) provides a new, approved method for treatment of skin cancer and its precursors. However, MAL-based PDT is not very efficient for poorly differentiated skin carcinoma. Thus, novel strategies to enhance the PDT effect are needed.

OBJECTIVES

In order to improve the efficacy of MAL-based PDT, we investigated the effect of adding calcitriol, a prodifferentiation hormone, to human squamous cell carcinoma A431 cells in vitro.

METHODS

A short course (24 h) of calcitriol pretreatment was applied in A431 cells, and, subsequently, MAL-induced protoporphyrin IX (PpIX) was measured.

RESULTS

Calcitriol pretreatment of the cells elevated their PpIX levels. Furthermore, the cell damage after exposure to blue light was significantly higher in calcitriol-treated cells. Increased photoinactivation correlated with higher levels of PpIX in the calcitriol-pretreated cells.

CONCLUSIONS

Calcitriol enhances MAL-based PDT in A431 cells.

Characterization of nanoparticles for therapeutics

Nanotechnology offers many advantages to traditional drug design, delivery and medical diagnostics; however, nanomedicines present considerable challenges for preclinical development. Nanoparticle constructs intended for medical applications consist of a wide variety of materials, and their small size, unique physicochemical properties and biological activity often require modification of standard characterization techniques. A rational characterization strategy for nanomedicines includes physicochemical characterization, sterility and pyrogenicity assessment, biodistribution (absorption, distribution, metabolism and excretion [ADME]) and toxicity characterization, which includes both in vitro tests and in vivo animal studies. Here, we highlight progress for a few methods that are uniquely useful for nanoparticles or are indicative of their toxicity or efficacy.

Two formulations of the agricultural pesticide adjuvant, Toximul, reduce the glycogen content of HepG2 cells

Young mice exposed dermally to the Toximul (Tox) class of agricultural pesticide adjuvants have reduced levels of hepatic glycogen, a marker of subclinical toxicity. The present study determined whether these effects on glycogen also occurred in cultured HepG2 cells. Exposure (3 hr) to Tox resulted in significant, concentration-dependent glycogen reductions (up to 70%) relative to control values (76 +/- 3 microg glycogen/mg protein). These reductions did not appear to be due to loss of cell viability, and were reversible with Tox removal. Two different formulations of Tox (3409F and MP-A) differed significantly in the magnitudes of glycogen reduction in the HepG2 cells.

In vitro antileishmanial activity of resveratrol and its hydroxylated analogues against Leishmania major promastigotes and amastigotes

Resveratrol, a natural phytoalexin found mainly in grapes, possesses a variety of beneficial activities including anticancer, antimicrobial and antiviral. However, there is no information about its effects on kinetoplastid parasites such as Leishmania. Leishmania is a human pathogen responsible for a spectrum of diseases known as leishmaniases and a significant health problem in many parts of the world. In this study, we investigated effects of resveratrol and its hydroxylated analogues on Leishmania major, a causative agent of zoonotic cutaneous leishmaniasis in the Old World. Resveratrol showed antileishmanial activity against promastigotes in vitro and, more importantly, was effective against intracellular amastigotes, a parasite life stage infectious in humans, as detected in in vitro macrophage assay. The hydroxylated stilbenes tested in this study also showed antileishmanial activity against promastigotes, the most promising being 3,4,4',5'-tetrahydroxy-trans-stilbene. This compound showed excellent antileishmanial activity against extracellular promastigotes in vitro but not intracellular amastigotes. Our results suggest that resveratrol may be useful as a therapeutic agent to treat leishmaniasis and warrant its further assessment in animal models of disease.

A new EGFR inhibitor induces apoptosis in colon cancer cells

The use of agents targeting EGFR represents a new frontier in colon cancer therapy. Among these, mAbs and EGFR tyrosine kinase inhibitors seemed to be the most promising. However they have demonstrated scarce utility in therapy, the former being effective only at toxic doses, the latter resulting inefficient in colon cancer. This paper presents studies on a new EGFR inhibitor, FR18, a molecule containing the same naphthoquinone core as shikonin, an agent with great anti-tumor potential. In HT29, a human colon carcinoma cell line, flow cytometry, immunoprecipitation, and Western blot analysis, confocal spectral microscopy have demonstrated that FR18 is active at concentrations as low as 10 nM, inhibits EGF binding to EGFR while leaving unperturbed the receptor kinase activity. At concentration ranging from 30 nM to 5 microM, it activates apoptosis. FR18 seems therefore to have possible therapeutic applications in colon cancer.

Combined effect of proteasome and calpain inhibition on cisplatin-resistant human melanoma cells

Resistance of tumor cells to cisplatin is a common feature frequently encountered during chemotherapy against melanoma caused by various known and unknown mechanisms. To overcome drug resistance toward cisplatin, a targeted treatment using alternative agents, such as proteasome inhibitors, has been investigated. This combination could offer a new therapeutic approach. Here, we report the biological effects of proteasome inhibitors on the parental cisplatin-sensitive MeWo human melanoma cell line and its cisplatin-resistant MeWo(cis1) variant. Our experiments show that proteasome inhibitor treatment of both cell lines impairs cell viability at concentrations that are not toxic to primary human fibroblasts in vitro. However, compared with the parental MeWo cell line, significantly higher concentrations of proteasome inhibitor are required to reduce cell viability of MeWo(cis1) cells. Moreover, whereas proteasome activity was inhibited to the same extent in both cell lines, IkappaBalpha degradation and nuclear factor-kappaB (NF-kappaB) activation in MeWo(cis1) cells was proteasome inhibitor independent but essentially calpain inhibitor sensitive. In support, a calpain-specific inhibitor impaired NF-kappaB activation in MeWo(cis1) cells. Here, we show that cisplatin resistance in MeWo(cis1) is accompanied by a change in the NF-kappaB activation pathway in favor of calpain-mediated IkappaBalpha degradation. Furthermore, combined exposure to proteasome and calpain inhibitor resulted in additive effects and a strongly reduced cell viability of MeWo(cis1) cells. Thus, combined strategies targeting distinct proteolytic pathways may help to overcome mechanisms of drug resistance in tumor cells.

Schedule-dependent interaction between Doxorubicin and mTHPC-mediated photodynamic therapy in murine hepatoma in vitro and in vivo

PURPOSE

To evaluate cytotoxic and antitumor effects of a conventional anticancer drug Doxorubicin (Dox) and photodynamic therapy (PDT) mediated by a promising photosensitizer of second generation meta-tetra (3-hydroxyphenyl)-chlorin (mTHPC) in combination.

METHODS

Murine hepatoma MH-22A was used for investigation in vitro and in vivo. In vitro, the cells were incubated with 0.15 microg/ml mTHPC for 18 h and exposed to light from LED array (lambda = 660+/-20 nm) at 0.6-2.4 kJ/m2. 0.05-0.2 microg/ml Dox was administered either 24 h prior to or immediately after light exposure (Dox-->PDT or PDT + Dox, respectively). The cytotoxicity was tested by staining with crystal violet. The character of the combined effect was assessed by multiple regression analysis. In vivo, the antitumor activity was estimated by monitoring the tumor volume over time, in mice transplanted subcutaneously with MH-22A and treated with Dox and/or PDT. For PDT, mice were exposed to light from diode laser (lambda = 650+/-2 nm) at 12 kJ/m2 following 24 h after administration of 0.15 mg/kg mTHPC. A 3 mg/kg Dox was administered either within 15 min prior to mTHPC or within 15 min after light exposure (Dox-->PDT or PDT + Dox, respectively).

RESULTS

Both in vitro and in vivo, the combination of mTHPC-mediated PDT and Dox was evaluated to be more effective than each treatment alone. In vitro, the difference between cell viability curves after photodynamic treatment as a single modality and after combination of photodynamic treatment with Dox was statistically significant under most of the applied conditions (P < or = 0.02). In the case of PDT + Dox, the combination had an additive character, and the sequence Dox-->PDT caused a sub-additive interaction. In vivo, both regimens of combination were more effective in inhibiting tumor growth than any single treatment (P < 0.09). The antitumor activity of PDT + Dox regimen was more prominent than that of Dox-->PDT; however, significance of the difference was not high (P = 0.08).

CONCLUSIONS

These results indicate that Dox potentiates therapeutic efficacy of mTHPC-mediated PDT and vice versa, and the degree of potentiation is influenced by the combination schedule: administration of Dox immediately after light exposure is preferable to administration of Dox at 24 h prior to light exposure.

Role of physical mechanisms in biological self-organization

Organs form during morphogenesis, the process that gives rise to specialized biological structures of specific shape and function in early embryonic development. Morphogenesis is under strict genetic control, but shape evolution itself is a physical process. Here we report the results of experimental and modeling biophysical studies on in vitro biological structure formation. Experimentally, by controlling the interaction between cells and their embedding matrices, we were able to build living structures of definite geometry. The experimentally observed shape evolution was reproduced by Monte Carlo simulations, which also shed light on the biophysical basis of the process. Our work suggests a novel way to engineer biological structures of controlled shape.