Tumor Cell Toxicity Research Articles

The in vitro study of Her-2 targeted gold nanoshell liquid fluorocarbon poly lactic-co-glycolic acid ultrasound microcapsule for ultrasound imaging and breast tumor photothermal therapy

Antibody-mediated targeting therapy has been successful in treating patients with breast cancer by improving the specificity and clinical efficacy. In this study, we constructed the human epidermal growth factor receptor-2 (Her2) antibody-conjugated ultrasound contrast agent with lactic-co-glycolic acid (PLGA) as film forming and perfluorocty bromide (PFOB) as internal material, which was coated by gold nanoshell (Her2-PFOB@PLGA@Au), to realize the integration of diagnosis and treatment. The contrast agent was spherical, with the diameter was 256.8 ± 53.4 nm, and had a good dispersion; Ultrasound imaging experiments in vitro showed that the gold nanoshell polylactic acid microcapsule was suitable for ultrasound contrast imaging with the exquisite and uniform dot intensive high echo. The agent had a great photothermal effect under the near-infrared (NIR) with no obvious biological toxicity for both Her2-positive and negative tumor cells; Moreover, both the results of laser scanning confocal microscope (LSCM) and flow cytometer (FCM) demonstrated the great specificity of Her2-PFOB@PLGA@Au conjugating with Her2 positive breast cancer cells (SKBR3). In conclusion, the successful synthesis of the Her2-PFOB@PLGA@Au microcapsule, offered a new therapeutic strategy of combining diagnosis with therapy for fighting against the breast cancer.

DNA/protein interactions, cell cycle arrest and apoptosis study of potent cytotoxic Pt(II) complexes with reduced side-effects

A series of platinum(II) complexes (C1–C6), incorporating an intercalating substituted benzimidazole (2-aminomethylbenzimidazole) and varied leaving groups such as chloride, chelating carboxylates, and thiols, was synthesized to achieve more potent and specific metallodrugs. Spectroscopic titrations, viscosity and electrophoresis measurements revealed that the complexes bound to DNA via an intercalative mode. The complexes were also found to have high affinity towards serum albumin, BSA. Cell viability experiments against three human cancer cell lines (A549, MCF-7, MDA-MB-231) in vitro indicated that the antitumor activities were comparable with cisplatin and its successors, with the greatest efficiency towards A549. Interestingly, complexes C1–C4 were 1.3–1.6 times more potent than cisplatin towards MDA-MB-231 cells. The complexes generate lower degrees of oxidative stress and are almost non-toxic to normal L6 myotubes, indicative of selective toxicity for tumor cells over normal cells. Further studies with A549 cell line revealed that the inhibition of cancer cell proliferation by the complexes is brought about by a combination of cell cycle arrest at the G2/M phase and induction of a caspase-mediated apoptosis.

Effect of gold nanoparticles on radiation doses in tumor treatment: a Monte Carlo study.

Radiotherapy is an extensively used treatment for most tumor types. However, ionizing radiation does not discriminate between cancerous and normal cells surrounding the tumor, which can be considered as a dose-limiting factor. This can lead to the reduction of the effectiveness of tumor cell eradication with this treatment. A potential solution to this problem is loading the tumor with high-Z materials prior to radiotherapy as this can induce higher toxicity in tumor cells compared to normal ones. New advances in nanotechnology have introduced the promising use of heavy metal nanoparticles to enhance tumor treatment. The primary studies showed that gold nanoparticles (GNPs) have unique characteristics as biocompatible radiosensitizers for tumor cells. This study aimed to quantify the dose enhancement effect and its radial dose distribution by Monte Carlo simulations utilizing the EGSnrc code for the water-gold phantom loaded with seven different concentrations of Au: 0, 7, 18, 30, 50, 75, and 100mg-Au/g-water. The phantom was irradiated with two different radionuclide sources, Ir-192 and Cs-137, which are commonly used in brachytherapy, for all concentrations. The results exhibited that gold nanoparticle-aided radiotherapy (GNRT) increases the efficacy of radiotherapy with low-energy photon sources accompanied with high Au concentration loads of up to 30mg-Au/g-water. Our finding conducts also to the detection of dose enhancement effects in a short average range of 650μm outside the region loaded with Au. This can indicate that the location determination is highly important in this treatment method.

X-ray visible and doxorubicin-loaded beads based on inherently radiopaque poly(lactic acid)-polyurethane for chemoembolization therapy

The aim of current study was to develop drug-loaded polymeric beads with intrinsic X-ray visibility as embolic agents, targeting for noninvasive intraoperative location and postoperative examination during chemoembolization therapy. To endow polymer with inherent radiopacity, 4,4'-isopropylidinedi-(2,6-diiodophenol) (IBPA) was firstly synthesized and employed as a contrast agent, and then a set of radiopaque iodinated poly(lactic acid)-polyurethanes (I-PLAUs) via chain extender method were synthesized and characterized. These I-PLAU copolymers possessed sufficient radiopacity, in vitro non-cytotoxicity with human adipose-derived stem cells, and in vivo biocompatibility and degradability in rabbit model via intramuscular implantation. Doxorubicin (DOX), as a chemotherapeutic agent, was further incorporated into I-PLAU beads via a double emulsification (W/O/W) method. For drug release, two ratios of DOX-loaded I-PLAU beads exhibited calibrated size (200-550μm), porous internal structure, good X-ray visibility, evenly drug loading as well as tunable drug release. A preliminary test on in vitro tumor cell toxicity demonstrated that the DOX-loaded I-PLAU beads performed efficient anti-tumor effect. This study highlights novel X-ray visible drug-loaded I-PLAU beads used as promising embolic agents for non-invasive in situ X-ray tracking and efficient chemotherapy, which could bring opportunities to the next generation of multifunctional embolic agents.

Cytotoxic effect of different treatment parameters in pressurized intraperitoneal aerosol chemotherapy (PIPAC) on the in vitro proliferation of human colonic cancer cells

BackgroundPressurized intraperitoneal aerosol chemotherapy (PIPAC) has been recently reported as a new approach for intraperitoneal chemotherapy (IPC). By means of a patented micropump, the liquid chemotherapy is delivered into the peritoneal cavity as an aerosol which is supposed to achieve “gas-like” distribution. However, recent data report that the fraction of the submicron aerosol (gas-like) is less than 3 vol% of the total amount of aerosolized chemotherapy. Until today, possible modifications of treatment parameters during PIPAC with the aim of improving therapeutic outcomes have not been studied yet.This study aims to establish an in vitro PIPAC model to explore the cytotoxic effect of the submicron aerosol fraction and to investigate the impact of different application parameters on the cytotoxic effect of PIPAC on human colonic cancer cells.MethodsAn in vitro model using HCT8 colon adenocarcinoma wild-type cells (HCT8WT) and multi-chemotherapy refractory subline (HCT8RT) was established. Different experimental parameters such as pressure, drug dosage, time exposure, and system temperature were monitored in order to search for the conditions with a higher impact on cell toxicity. Cell proliferation was determined by means of colorimetric MTT assay 48 h following PIPAC exposures.ResultsStandard operational parameters applied for PIPAC therapy depicted a cytotoxic effect of the submicron aerosol fraction generated by the PIPAC micropump. We also observed that increasing pressure significantly enhanced tumor cell toxicity in both wild-type and chemotherapy-resistant cells. A maximum of cytotoxicity was observed at 15 mmHg. Pressure >15 mmHg did not show additional cytotoxic effect on cells. Increased oxaliplatin dosage resulted in progressively higher cell toxicity as expected. However, in resistant cells, a significant effect was only found at higher drug concentrations. Neither an extension of exposure time nor an increase in temperature of the aerosolized chemotherapy solution added an improvement in cytotoxicity.ConclusionsIn this in vitro PIPAC model, the gas-like PIPAC aerosol fraction showed a cytotoxic effect which was enhanced by higher intra-abdominal pressure with a maximum at 15 mmHg. Similar findings were observed for drug dose escalation. A phase I dose escalation study is currently performed at our institution. However, increasing the intra-abdominal pressure might be a first and simple way to enhance the cytotoxic effect of PIPAC therapy which needs further clinical investigations.

An in vitro demonstration of overcoming drug resistance in SKOV3 TR and MCF7 ADR with targeted delivery of polymer pro-drug conjugates

Drug resistance is a common phenomenon that occurs in cancer chemotherapy. Delivery of chemotherapeutic agents as polymer pro-drug conjugates (PPDCs) pretargeted with bispecific antibodies could circumvent drug resistance in cancer cells. To demonstrate this approach to overcome drug resistance, Paclitaxel (Ptxl)-resistant SKOV3 TR human ovarian- and doxorubicin (Dox)-resistant MCF7 ADR human mammary-carcinoma cell lines were used. Pre-targeting over-expressed biotin or HER2/neu receptors on cancer cells was conducted by biotinylated anti-DTPA or anti-HER2/neu affibody – anti-DTPA Fab bispecific antibody complexes. The targeting PPDCs are either D-Dox-PGA or D-Ptxl-PGA. Cytotoxicity studies demonstrate that the pretargeted approach increases cytotoxicity of Ptxl or Dox in SKOV3 TR or MCF7 ADR resistant cell lines by 5.4 and 27 times, respectively. Epifluorescent microscopy – used to track internalization of D-Dox-PGA and Dox in MCF7 ADR cells – shows that the pretargeted delivery of D-Dox-PGA resulted in a 2- to 4-fold increase in intracellular Dox concentration relative to treatment with free Dox. The mechanism of internalization of PPDCs is consistent with endocytosis. Enhanced drug delivery and intracellular retention following pretargeted delivery of PPDCs resulted in greater tumor cell toxicity in the current in vitro studies.

Activation of the Chicken Anemia Virus Apoptin Protein by Chk1/2 Phosphorylation Is Required for Apoptotic Activity and Efficient Viral Replication.

Chicken anemia virus (CAV) is a single-stranded circular DNA virus that carries 3 genes, the most studied of which is the gene encoding VP3, also known as apoptin. This protein has been demonstrated to specifically kill transformed cells while leaving normal cells unharmed in a manner that is independent of p53 status. Although the mechanistic basis for this differential activity is unclear, it is evident that the subcellular localization of the protein is important for the difference. In normal cells, apoptin exists in filamentous networks in the cytoplasm, whereas in transformed cells, apoptin is present in the nucleus and appears as distinct foci. We have previously demonstrated that DNA damage signaling through the ataxia telangiectasia mutated (ATM) pathway induces the translocation of apoptin from the cytoplasm to the nucleus, where it induces apoptosis. We found that apoptin contains four checkpoint kinase consensus sites and that mutation of either threonine 56 or 61 to alanine restricts apoptin to the cytoplasm. Furthermore, treatment of tumor cells expressing apoptin with inhibitors of checkpoint kinase 1 (Chk1) and Chk2 causes apoptin to localize to the cytoplasm. Importantly, silencing of Chk2 rescues cancer cells from the cytotoxic effects of apoptin. Finally, treatment of virus-producing cells with Chk inhibitor protects them from virus-mediated toxicity and reduces the titer of progeny virus. Taken together, our results indicate that apoptin is a sensor of DNA damage signaling through the ATM-Chk2 pathway, which induces it to migrate to the nucleus during viral replication. The chicken anemia virus (CAV) protein apoptin is known to induce tumor cell-specific death when expressed. Therefore, understanding its regulation and mechanism of action could provide new insights into tumor cell biology. We have determined that checkpoint kinase 1 and 2 signaling is important for apoptin regulation and is a likely feature of both tumor cells and host cells producing virus progeny. Inhibition of checkpoint signaling prevents apoptin toxicity in tumor cells and attenuates CAV replication, suggesting it may be a future target for antiviral therapy.

Engineered adenovirus fiber shaft fusion homotrimer of soluble TRAIL with enhanced stability and antitumor activity.

Successful cancer therapies aim to induce selective apoptosis in neoplastic cells. Tumor necrosis factor-related apoptosis-inducing ligand (TRAIL) is considered an attractive anticancer agent due to its tumor cell-specific cytotoxicity. However, earlier studies with recombinant TRAIL revealed many shortcomings, including a short half-life, off-target toxicity and existence of TRAIL-resistant tumor cells. In this study, we developed a novel engineering strategy for recombinant soluble TRAIL by redesigning its structure with the adenovirus knobless fiber motif to form a stable homotrimer with improved antitumor activity. The result is a highly stable fiber-TRAIL fusion protein that could form homotrimers similar to natural TRAIL. The recombinant fusion TRAIL developed here displayed high specific activity in both cell-based assays in vitro and animal tests in vivo. This construct will serve as a foundation for a new generation of recombinant proteins suitable for use in preclinical and clinical studies and for effective combination therapies to overcome tumor resistance to TRAIL.

Fabrication of folic acid-sensitive gold nanoclusters for turn-on fluorescent imaging of overexpression of folate receptor in tumor cells

Based on the fluorescence quenching of folic acid-sensitive bovine serum albumin-directed gold nanoclusters (BSA-AuNCs) via folic acid-induced the change of environment around BSA-AuNCs, we have constructed a turn on fluorescence imaging of folate receptor overexpressed tumor cells. In this paper, the primary fluorescence intensity of BSA-AuNCs was quenched via self-assembly of folic acid onto BSA-AuNCs to produce negligible fluorescence background, the linear range of the method was 0.1-100μg/mL with the limit of detection (LOD) of 30ng/mL (S/N=3); In the presence of overexpression of folate receptor on the surface of tumor cells, the primary fluorescence intensity of BSA-AuNCs turned on by folic acid desorbing from BSA-AuNCs, the linear range of method was 0.12-2μg/mL with the LOD of 20ng/mL (S/N=3). Additionally, due to specific and high affinity of folic acid and folate receptor, the probe had high selectivity for folate receptor, other interferences hardly changed the fluorescence intensity of the probe. Moreover, the text for cytotoxicity implied that the probe had no toxicity for tumor cells. Consequently, using the fluorescence probe, satisfactory results for the turn on imaging of folate receptor overexpressed tumor cells were obtained. A novel turn-on and red fluorescent probe for folate receptor overexpressed tumor cells was developed based on the recovery of fluorescence intensity of folic acid-sensitive BSA-AuNCs.

Effect of surface ligand density on cytotoxicity and pharmacokinetic profile of docetaxel loaded liposomes

Various biotin-modified liposomes incorporated with docetaxel (DTX) were prepared to study the effect of surface biotin density on the pharmacokinetic profile of the liposome. Four types of liposomes such as PEG modified liposome (PDL), 0.5% (mol) biotin modified liposome (0.5BDL), 1% (mol) biotin modified liposome (1BDL) and 2% (mol) biotin modified liposome (2BDL) were prepared using thin film dispersion method. The prepared liposomes were characterized by measuring encapsulation efficiency (EE), particle size, Zeta-potential, physical stability and drug release profiles in vitro. MTT assay was performed to elevate the cytotoxicity of liposomes on MCF-7 cells. In vivo evaluation was further performed to investigate the effect of biotin surface density on the pharmacokinetic profiles. All the prepared liposomes exhibited high encapsulation efficiency, small particle size, narrow particle distribution and sustained release profiles in vitro. In MTT assay, 0.5BDL showed largest tumor cell toxicity, compared with DTX solution. All liposomes containing DTX showed prolonged blood circulation in vivo, and 0.5BDL showed the longest circulation time among the biotin modified liposome. Surface modification of liposome had a negative impact on the circulation of liposomes in the blood, which needs to be considered when designing the ligand mediated targeting delivery systems. A proper amount of biotin liposome with 0.5% molar ratio is expected to produce the best anti-tumor effect.

In vitro cytotoxicity and phototoxicity of surface-modified gold nanoparticles associated with neutral red as a potential drug delivery system in phototherapy

The surface of gold nanoparticles (AuNP) was modified, improving their interaction with neutral red (NR), by using sodium thioglycolate (TGA) as a covering agent. The resulting NR-AuNPTGA system was evaluated as a potential drug delivery system for photodynamic therapy (PDT). The associations of NR with the gold nanoparticles were evaluated using UV-vis spectrometry and measurement of their zeta potential and size distribution. The toxicity and phototoxicity of NR, AuNPTGA and NR-AuNPTGA were evaluated in NIH-3T3 fibroblast and 4T1 tumor cell lines. The compounds NR and NR-AuNPTGA induced toxicity in 4T1 tumor cells and NIH-3T3 fibroblasts under visible light irradiation. Modification of the surface of AuNP with TGA prevented nanoparticle aggregation and allowed greater association with NR molecules than for naked AuNP. The photosensitizer (PS) characteristics were not affected by its association with the modified surface of the gold nanoparticles, leading to a reduction of cell viability in both cell lines assayed. This NR-AuNPTGA system is a promising drug delivery system for photodynamic cancer therapy.

Preclinical Evaluation of an Epidermal Growth Factor Receptor–Targeted Doxorubicin–Peptide Conjugate: Toxicity, Biodistribution, and Efficacy in Mice

Doxorubicin (DOX) is known to induce apoptosis and necrosis in healthy tissue resulting in unwanted toxicities. To improve the ability of DOX to more specifically target tumors and minimize undesirable side effects, conjugation of DOX with epidermal growth factor receptor (EGFR)--binding peptide (DOX-EBP) has been developed to deliver DOX to EGFR-overexpressing neoplastic cells. Here, we investigated whether DOX-EBP was able to reduce toxicity and enhance anticancer efficacy in vivo through receptor-mediated targeted delivery system. Nude mice were treated with DOX or DOX-EBP to estimate general toxicity, normal tissue damage, biodistribution, and antitumor efficacy. In addition, the expression levels of EGFR in tumor tissues and normal organs were investigated by Western blotting, and their mRNA expression was analyzed by reverse transcription PCR. This study demonstrated that DOX-EBP was able to effectively decrease the distribution of DOX in normal tissues without EGFR overexpressing and reduce DOX-induced toxicity. On the other hand, the research also confirmed that DOX-EBP was able to preferentially accumulate DOX in EGFR-overexpressing tumor tissues and showed the enhanced anticancer efficacy over free DOX. DOX-EBP could be used for receptor-targeted chemotherapy with less toxicity and greater efficacy of tumor cells overexpressing EGFR. DOX-EBP conjugate is a good therapeutic agent for cancer treatment.

Different gap junction-propagated effects on cisplatin transfer result in opposite responses to cisplatin in normal cells versus tumor cells.

Previous work has shown that gap junction intercellular communication (GJIC) enhances cisplatin (Pt) toxicity in testicular tumor cells but decreases it in non-tumor testicular cells. In this study, these different GJIC-propagated effects were demonstrated in tumor versus non-tumor cells from other organ tissues (liver and lung). The downregulation of GJIC by several different manipulations (no cell contact, pharmacological inhibition, and siRNA suppression) decreased Pt toxicity in tumor cells but enhanced it in non-tumor cells. The in vivo results using xenograft tumor models were consistent with those from the above-mentioned cells. To better understand the mechanism(s) involved, we studied the effects of GJIC on Pt accumulation in tumor and non-tumor cells from the liver and lung. The intracellular Pt and DNA-Pt adduct contents clearly increased in non-tumor cells but decreased in tumor cells when GJIC was downregulated. Further analysis indicated that the opposite effects of GJIC on Pt accumulation in normal versus tumor cells from the liver were due to its different effects on copper transporter1 and multidrug resistance-associated protein2, membrane transporters attributed to intracellular Pt transfer. Thus, GJIC protects normal organs from cisplatin toxicity while enhancing it in tumor cells via its different effects on intracellular Pt transfer.

Selective redox-responsive drug release in tumor cells mediated by chitosan based glycolipid-like nanocarrier

The redox responsive nanocarriers have made a considerable progress in achieving triggered drug release by responding to the endogenous occurring difference between the extra- and intra- cellular redox environments. Despite the promises, this redox difference exists both in normal and tumor tissue. So a non-selective redox responsive drug delivery system may result in an undesired drug release in normal cells and relevant side-effects. To overcome these limitations, we have developed a chitosan based glycolipid-like nanocarrier (CSO-ss-SA) which selectively responded to the reducing environment in tumor cells. The CSO-ss-SA showed an improved reduction-sensitivity which only fast degraded and released drug in 10mM levels of glutathione (GSH). The CSO-ss-SA could transport the drug fast into the human ovarian cancer SKOV-3 cells and human normal liver L-02 cells by internalization, but only fast release drug in SKOV-3 cells. By regulating the intracellular GSH concentration in SKOV-3 cells, it indicated that the cellular inhibition of the PTX-loaded CSO-ss-SA showed a positive correlation with the GSH concentration. The CSO-ss-SA was mainly located in the liver, spleen and tumor in vivo, which evidenced the passive tumor targeting ability. Despite the high uptake of liver and spleen, drug release was mainly occurred in tumor. PTX-loaded CSO-ss-SA achieved a remarkable tumor growth inhibition effect with rather low dose of PTX. This study demonstrates that a smartly designed glycolipid-like nanocarrier with selective redox sensitivity could serve as an excellent platform to achieve minimal toxicity and rapid intracellular drug release in tumor cells.

8:09 AM, Abstract No. 22 - Dimethyaminoparthenolide exhibits selective toxicity and chemosensitization for liver tumor cells

8:09 AM, Abstract No. 22 - Dimethyaminoparthenolide exhibits selective toxicity and chemosensitization for liver tumor cells

Molecular mechanisms of fenofibrate-induced metabolic catastrophe and glioblastoma cell death.

Fenofibrate (FF) is a common lipid-lowering drug and a potent agonist of the peroxisome proliferator-activated receptor alpha (PPARα). FF and several other agonists of PPARα have interesting anticancer properties, and our recent studies demonstrate that FF is very effective against tumor cells of neuroectodermal origin. In spite of these promising anticancer effects, the molecular mechanism(s) of FF-induced tumor cell toxicity remains to be elucidated. Here we report a novel PPARα-independent mechanism explaining FF's cytotoxicity in vitro and in an intracranial mouse model of glioblastoma. The mechanism involves accumulation of FF in the mitochondrial fraction, followed by immediate impairment of mitochondrial respiration at the level of complex I of the electron transport chain. This mitochondrial action sensitizes tested glioblastoma cells to the PPARα-dependent metabolic switch from glycolysis to fatty acid β-oxidation. As a consequence, prolonged exposure to FF depletes intracellular ATP, activates the AMP-activated protein kinase-mammalian target of rapamycin-autophagy pathway, and results in extensive tumor cell death. Interestingly, autophagy activators attenuate and autophagy inhibitors enhance FF-induced glioblastoma cytotoxicity. Our results explain the molecular basis of FF-induced glioblastoma cytotoxicity and reveal a new supplemental therapeutic approach in which intracranial infusion of FF could selectively trigger metabolic catastrophe in glioblastoma cells.

Abstract 5036: Blockade of the CD39 immunoregulatory pathway by monoclonal antibodies

Abstract The CD39/ CD73/ adenosine pathway is an important regulator of effector immune cell response. We previously demonstrated that, in human cancer specimen, CD39 is expressed by infiltrating regulatory T cells, tumor cells and the tumor associated stroma. CD39 enzymatic activity decreases peritumoral ATP, a potent tumor cell toxicity and immunogenic inducer, and generates immunosuppressive adenosine that binds adenosine receptors and inhibits CD4, CD8 T cell and NK cell responses. We and other demonstrated that CD39-mediated decrease of extracellular ATP and increase of adenosine promote tumor progression and immune escape as well as resistance to chemotherapy-induced immune response. We therefore generated several CD39 blocking monoclonal antibodies and present here the latest developments of these antibodies. We provide evidence that CD39 blocking antibodies restore the proliferation of CD4 and CD8 T cells inhibited by melanoma cells expressing CD39 and increase the generation of CD8 cytotoxic T cells against CD39+ melanoma cells. We also demonstrated that CD39+ lymphoma cells are less sensitive to NK cell cytotoxic activity than CD39- lymphoma cells, and that CD39-blocking monoclonal antibodies increase NK-mediated lysis of CD39+ lymphoma cells but not CD39- lymphoma cells. In conclusion, CD39 blocking antibodies may represent a novel immunotherapy strategy for inhibiting regulatory T cells and tumor cell-mediated immunosuppression. The results presented here support the ongoing development of CD39 blocking monoclonal antibodies as potential anticancer drugs to restore antitumor immune response. Citation Format: Jeremy Bastid, Cécile Dejou, Jérôme Giustiniani, Stéphanie Cochaud, Gilles Alberici, Armand Bensussan, Jean-François Eliaou, Nathalie Bonnefoy. Blockade of the CD39 immunoregulatory pathway by monoclonal antibodies. [abstract]. In: Proceedings of the 105th Annual Meeting of the American Association for Cancer Research; 2014 Apr 5-9; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2014;74(19 Suppl):Abstract nr 5036. doi:10.1158/1538-7445.AM2014-5036

Safe and efficient pH sensitive tumor targeting modified liposomes with minimal cytotoxicity

Incorporating the pH-sensitivity of octylamine grafted poly aspartic acid (PASP) with the biocompatibility of liposomes, a novel pH sensitive drug delivery system, octylamine-graft-PASP (PASP-g-C8) modified liposomes (OPLPs), was obtained. Since hydrophobic chains have been grafted into PASP backbones, the octylamine chain could act as the "anchor" to implant onto liposomes. The structure of PASP-g-C8, involving long-chain and hydrophobic anchors can significantly enhance the stability of the drug carrier. The shortcoming of single PASP chain modified liposomes (PLPs), that cannot sustain a slow and controlled release especially in a physiological pH solution (resembling normal tissues of pH 7.4) is thus overcome. Drug release experiments were carried out and the result showed that OPLPs sustained a slow and steady release in comparison with PLPs in the physiological pH 7.4 environment. However, OPLPs can provide a fast release in subacid environment (pH 5.0 of resembled tumor tissues). The results of diameter analysis and zeta potential demonstrated that OPLPs presented a larger diameter and higher electronegativity. Furthermore, in the "chain-anchor" structure of PASP-g-C8, the degree of substitution (DS) of the "anchor" is a remarkable factor to alter the pH-sensitivity of OPLPs. The in vitro tumor inhibition and cell toxicity studies revealed that tumor cells treated with OPLPs survived only 35.0% after 48 h whereas normal cells survived 100% in the same condition. The pH sensitive OPLPs are promising tumor targeting drug delivery with high tumor inhibition and insignificant cytotoxicity.

Mitogen-activated protein kinase-interacting kinase regulates mTOR/AKT signaling and controls the serine/arginine-rich protein kinase-responsive type 1 internal ribosome entry site-mediated translation and viral oncolysis.

Translation machinery is a major recipient of the principal mitogenic signaling networks involving Raf-ERK1/2 and phosphoinositol 3-kinase (PI3K)-mechanistic target of rapamycin (mTOR). Picornavirus internal ribosomal entry site (IRES)-mediated translation and cytopathogenic effects are susceptible to the status of such signaling cascades in host cells. We determined that tumor-specific cytotoxicity of the poliovirus/rhinovirus chimera PVSRIPO is facilitated by Raf-ERK1/2 signals to the mitogen-activated protein kinase (MAPK)-interacting kinase (MNK) and its effects on the partitioning/activity of the Ser/Arg (SR)-rich protein kinase (SRPK) (M. C. Brown, J. D. Bryant, E. Y. Dobrikova, M. Shveygert, S. S. Bradrick, V. Chandramohan, D. D. Bigner, and M, Gromeier, J. Virol. 22:13135-13148, 2014, doi:http://dx.doi.org/10.1128/JVI.01883-14). Here, we show that MNK regulates SRPK via mTOR and AKT. Our investigations revealed a MNK-controlled mechanism acting on mTORC2-AKT. The resulting suppression of AKT signaling attenuates SRPK activity to enhance picornavirus type 1 IRES translation and favor PVSRIPO tumor cell toxicity and killing. Oncolytic immunotherapy with PVSRIPO, the type 1 live-attenuated poliovirus (PV) (Sabin) vaccine containing a human rhinovirus type 2 (HRV2) IRES, is demonstrating early promise in clinical trials with intratumoral infusion in recurrent glioblastoma (GBM). Our investigations demonstrate that the core mechanistic principle of PVSRIPO, tumor-selective translation and cytotoxicity, relies on constitutive ERK1/2-MNK signals that counteract the deleterious effects of runaway AKT-SRPK activity in malignancy.

DNA binding mode of transition metal complexes, a relationship to tumor cell toxicity.

Transition metal-based compounds constitute a distinct class of chemotherapeutics extensively used in the clinic as antitumor and antiviral agents. However, drug resistance and side effects of established antitumor metallodrugs such as cisplatin [cis-diamminedichloroplatinum(II)] and its analogues, carboplatin and oxaliplatin, have limited their clinical utility. These limitations have prompted a search for more effective and less toxic metal-based antitumor agents. The unique properties of metal ions, such as redox transfer/electron shuttling, and versatile coordination geometries arising from various oxidation states, result in metal ions and complexes that have potential medicinal applications that could be complementary to organic compounds and which are widely sought in drug discovery efforts. This review summarizes the results that show that transition metal complexes exhibit antitumor effects that differ from cisplatin or its analogues.