HuR-targeted small molecule inhibitor exhibits cytotoxicity towards human lung cancer cells

Human antigen (Hu) R is an RNA-binding protein whose overexpression in human cancer correlates with aggressive disease, drug resistance, and poor prognosis. HuR inhibition has profound anticancer activity. Pharmacologic inhibitors can overcome the limitations of genetic inhibition. In this study, we examined the antitumor activity of CMLD-2, a small-molecule inhibitor directed against HuR, using non-small cell lung cancer (NSCLC) as a model. CMLD-2 efficacy was tested in vitro using H1299, A549, HCC827, and H1975 NSCLC cells and MRC-9 and CCD-16 normal human fibroblasts. Treatment of NSCLC cells with CMLD-2 produced dose-dependent cytotoxicity, caused a G1 phase cell-cycle arrest and induced apoptosis. CMLD-2 decreased HuR mRNA and the mRNAs of HuR-regulated proteins (Bcl2 and p27) in tumor cells. Additionally, reduction in the expression of HuR, Bcl2, cyclin E, and Bcl-XL with increased expression of Bax and p27 in CMLD-2-treated NSCLC cells were observed. CMLD-2-treated normal cells, HuR-regulated mRNAs and proteins albeit showed some reduction were less compared to tumor cells. Finally, CMLD-2 treatment resulted in greater mitochondrial perturbation, activation of caspase-9 and -3 and cleavage of PARP in tumor cells compared to normal cells. Our proof-of concept study results demonstrate CMLD-2 represents a promising HuR-targeted therapeutic class that with further development could lead to advanced preclinical studied and ultimately for lung cancer treatment.

Electric field control of magnetization direction across the antiferromagnetic to ferromagnetic transition

Electric-field-induced magnetic switching can lead to a new paradigm of ultra-low power nonvolatile magnetoelectric random access memory (MeRAM). To date the realization of MeRAM relies primarily on ferromagnetic (FM) based heterostructures which exhibit low voltage-controlled magnetic anisotropy (VCMA) efficiency. On the other hand, manipulation of magnetism in antiferromagnetic (AFM) based nanojunctions by purely electric field means (rather than E-field induced strain) remains unexplored thus far. Ab initio electronic structure calculations reveal that the VCMA of ultrathin FeRh/MgO bilayers exhibits distinct linear or nonlinear behavior across the AFM to FM metamagnetic transition depending on the Fe- or Rh-interface termination. We predict that the AFM Fe-terminated phase undergoes an E-field magnetization switching with large VCMA efficiency and a spin reorientation across the metamagnetic transition. In sharp contrast, while the Rh-terminated interface exhibits large out-of-plane (in-plane) MA in the FM (AFM) phase, its magnetization is more rigid to external E-field. These findings demonstrate that manipulation of the AFM Néel-order magnetization direction via purely E-field means can pave the way toward ultra-low energy AFM-based MeRAM devices.

Tumor-targeted Nanoparticle Delivery of HuR siRNA Inhibits Lung Tumor Growth In Vitro and In Vivo By Disrupting the Oncogenic Activity of the RNA-binding Protein HuR

Selective downregulation of the human antigen R (HuR) protein by siRNA may provide a powerful approach for treating lung cancer. To this end, we investigated the efficacy of transferrin receptor-targeted liposomal nanoparticle-based HuR siRNA (HuR-TfNP) therapy and compared with control siRNA (C)-TfNP therapy both, in vitro and in vivo using lung cancer models. In vitro studies showed HuR-TfNP, but not C-TfNP, efficiently downregulated HuR and HuR-regulated proteins in A549, and HCC827 lung cancer cells, resulting in reduced cell viability, inhibition of cell migration and invasion, and induction of G₁ cell-cycle arrest culminating in apoptosis. However, HuR-TfNP activity in normal MRC-9 lung fibroblasts was negligible. In vivo biodistribution study demonstrated that fluorescently labeled HuR-siRNA or ICG dye-loaded TfNP localized in tumor tissues. Efficacy studies showed intratumoral or intravenous administration of HuR-TfNP significantly inhibited A549 (>55% inhibition) and HCC827 (>45% inhibition) subcutaneous tumor growth compared with C-TfNP. Furthermore, HuR-TfNP treatment reduced HuR, Ki67, and CD31 expression and increased caspase-9 and PARP cleavage and TUNEL-positive staining indicative of apoptotic cell death in tumor tissues compared with C-TfNP treatment. The antitumor activity of HuR-TfNP was also observed in an A549-luc lung metastatic model, as significantly fewer tumor nodules (9.5 ± 3.1; P < 0.001; 88% inhibition) were observed in HuR-TfNP-treated group compared with the C-TfNP-treated group (77.7 ± 20.1). Significant reduction in HuR, Ki67, and CD31 expression was also observed in the tumor tissues of HuR-TfNP-treatment compared with C-TfNP treatment. Our findings highlight HuR-TfNP as a promising nanotherapeutic system for lung cancer treatment. Mol Cancer Ther; 16(8); 1470-86. ©2017 AACR.

Functional electronic inversion layers at ferroelectric domain walls

Ferroelectric domain walls hold great promise as functional two-dimensional materials because of their unusual electronic properties. Particularly intriguing are the so-called charged walls where a polarity mismatch causes local, diverging electrostatic potentials requiring charge compensation and hence a change in the electronic structure. These walls can exhibit significantly enhanced conductivity and serve as a circuit path. The development of all-domain-wall devices, however, also requires walls with controllable output to emulate electronic nano-components such as diodes and transistors. Here we demonstrate electric-field control of the electronic transport at ferroelectric domain walls. We reversibly switch from resistive to conductive behaviour at charged walls in semiconducting ErMnO₃. We relate the transition to the formation-and eventual activation-of an inversion layer that acts as the channel for the charge transport. The findings provide new insight into the domain-wall physics in ferroelectrics and foreshadow the possibility to design elementary digital devices for all-domain-wall circuitry.

Do Health Information Exchanges Deter Repetition of Medical Services?

Repetition of medical services by providers is one of the major sources of healthcare costs. The lack of access to previous medical information on a patient at the point of care often leads a physician to perform medical procedures that have already been done. Multiple healthcare initiatives and legislation at both the federal and state levels have mandated Health Information Exchange (HIE) systems to address this problem. This study aims to assess the extent to which HIE could reduce these repetitions, using data from Centers for Medicare 8 Medicaid Services and a regional HIE organization. A 2-Stage Least Square model is developed to predict the impact of HIE on repetitions of two classes of procedures: diagnostic and therapeutic. The first stage is a predictive analytic model that estimates the duration of tenure of each HIE member-practice. Based on these estimates, the second stage predicts the effect of providers’ HIE tenure on their repetition of medical services. The model incorporates moderating effects of a federal quality assurance program and the complexity of medical procedures with a set of control variables. Our analyses show that a practice's tenure with HIE significantly lowers the repetition of therapeutic medical procedures, while diagnostic procedures are not impacted. The medical reasons for the effects observed in each class of procedures are discussed. The results will inform healthcare policymakers and provide insights on the business models of HIE platforms.

Polymeric Nanoparticle-Mediated Gene Delivery for Lung Cancer Treatment

In recent years, researchers have focused on targeted gene therapy for lung cancer, using nanoparticle carriers to overcome the limitations of conventional treatment methods. The main goal of targeted gene therapy is to develop more efficient therapeutic strategies by improving the bioavailability, stability, and target specificity of gene therapeutics and to reduce off-target effects. Polymer-based nanoparticles, an alternative to lipid and inorganic nanoparticles, efficiently carry nucleic acid therapeutics and are stable in vivo. Receptor-targeted delivery is a promising approach that can limit non-specific gene delivery and can be achieved by modifying the polymer nanoparticle surface with specific receptor ligands or antibodies. This review highlights the recent developments in gene delivery using synthetic and natural polymer-based nucleic acid carriers for lung cancer treatment. Various nanoparticle systems based on polymers and polymer combinations are discussed. Further, examples of targeting ligands or moieties used in targeted, polymer-based gene delivery to lung cancer are reviewed.

Multifaceted Applications of Chitosan in Cancer Drug Delivery and Therapy

Chitosan is a versatile polysaccharide of biological origin. Due to the biocompatible and biodegradable nature of chitosan, it is intensively utilized in biomedical applications in scaffold engineering as an absorption enhancer, and for bioactive and controlled drug release. In cancer therapy, chitosan has multifaceted applications, such as assisting in gene delivery and chemotherapeutic delivery, and as an immunoadjuvant for vaccines. The present review highlights the recent applications of chitosan and chitosan derivatives in cancer therapy.

Silencing BMI1 radiosensitizes human breast cancer cells by inducing DNA damage and autophagy

Overexpression of BMI1 in human cancer cells, a member of the polycomb group of repressive complexes, correlates with advanced stage of disease, aggressive clinico-pathological behavior, poor prognosis, and resistance to radiation and chemotherapy. Studies have shown that experimental reduction of BMI1 protein level in tumor cells results in inhibition of cell proliferation, induction of apoptosis and/or senescence, and increased susceptibility to cytotoxic agents and radiation therapy. Although a role for BMI1 in cancer progression and its importance as a molecular target for cancer therapy has been established, information on the impact of silencing BMI1 in triple-negative breast cancer (TNBC) and its consequence on radiotherapy have not been well studied. Therefore, in the present study we investigated the potential therapeutic benefit of radiation therapy in BMI1-silenced breast cancer cells and studied the mechanism(s) of radiosensitization. Human MDA-MB-231 and SUM159PT breast cancer cells that were either stably transfected with a lentiviral vector expressing BMI1 shRNA (shBMI1) or control shRNA (shControl) or transient transfection with a BMI1-specific siRNA were used. Silencing of BMI1 resulted in marked reduction in BMI1 both at the mRNA and protein level that was accompanied by a significant reduction in cell migration compared to control cells. Further, BMI1 knockdown produced a marked enhancement of DNA damage as evidenced by Comet Assay and γH2AX foci, resulting in a dose-dependent radiosensitization effect. Molecular studies revealed modulation of protein expression that is associated with the DNA damage response (DDR) and autophagy pathways. Our results demonstrate that BMI1 is an important therapeutic target in breast cancer and suppression of BMI1 produces radiation sensitivity. Further, combining BMI1-targeted therapeutics with radiation might benefit patients diagnosed with TNBC.

Ambipolar transport and magneto-resistance crossover in a Mott insulator, Sr2IrO4

Electric field effect (EFE) controlled magnetoelectric transport in thin films of undoped and La-doped Sr₂IrO₄ (SIO) is investigated using ionic liquid gating. The temperature dependent resistance measurements exhibit insulating behavior in chemically and EFE doped samples with the band filling up to 10%. The ambipolar transport across the Mott gap is demonstrated by EFE tuning of the channel resistance and chemical doping. We observe a crossover from high temperature negative to low temperature positive magnetoresistance around  ∼80-90 K, irrespective of the filling. This temperature and magnetic field dependent crossover is discussed in the light of conduction mechanisms of SIO, especially variable range hopping (VRH), and its relevance to the insulating ground state of SIO.

Nanoparticles for siRNA-Based Gene Silencing in Tumor Therapy

Gene silencing through RNA interference (RNAi) has emerged as a potential strategy in manipulating cancer causing genes by complementary base-pairing mechanism. Small interfering RNA (siRNA) is an important RNAi tool that has found significant application in cancer therapy. However due to lack of stability, poor cellular uptake and high probability of loss-of-function due to degradation, siRNA therapeutic strategies seek safe and efficient delivery vehicles for in vivo applications. The current review discusses various nanoparticle systems currently used for siRNA delivery for cancer therapy, with emphasis on liposome based gene delivery systems. The discussion also includes various methods availed to improve nanoparticle based-siRNA delivery with target specificity and superior efficiency. Further this review describes challenges and perspectives on the development of safe and efficient nanoparticle based-siRNA-delivery systems for cancer therapy.

Evaluation of the multiple biomarkers on identification of the vulnerable coastal pollution hotspots

This paper presents multiple biomarkers on metal accumulation and its impacts along the Chennai to Puducherry, southeast coast of India using bivalves as bioindicators. In this regard, water samples and Perna viridis were collected from three stations and the accumulation of metals and its biological impacts were assessed. Among the three sampling stations, the maximum accumulation was noticed in Ennore (S1) than the Puducherry (S3) followed by Kovalam (S2). Mean accumulation pattern of metals in Perna viridis was found to be in the following order Zn > Cu > Ni > Cr > Pb > Cd, which were in close match with the metal concentration in seawater at respective site. The ambient metal concentration and behavior of multiple biomarkers were positively correlated indicating that the uptake of metals might induce biological changes, particularly in the internal organs, thus significantly affecting health of the aquatic organisms. P. viridis provides reliable information concerning the adverse effects and reflects the integrated effects of all contaminants. Thus, study confirmed that Ennore (S1) coast is highly vulnerable for significant pollution, in terms of metal toxicity in the study area. Overall investigation revealed that metal enrichment was observed close to the major urban areas in the S1 and S2 which were associated with industrialized areas. The assessment of multiple biomarkers on metal accumulation was the first step in determining the trophic transfer factors on marine foot web, which can be evaluated in the future based on this study.

Ultrafast dynamics of localized magnetic moments in the unconventional Mott insulator Sr2IrO4

We report a time-resolved study of the ultrafast dynamics of the magnetic moments formed by the [Formula: see text] states in Sr2IrO4 by directly probing the localized iridium 5d magnetic state through resonant x-ray diffraction. Using optical pump-hard x-ray probe measurements, two relaxation time scales were determined: a fast fluence-independent relaxation is found to take place on a time scale of 1.5 ps, followed by a slower relaxation on a time scale of 500 ps-1.5 ns.

Abstract 3738: IL-24 modulates the high mobility group (HMG) A1/miR222 /AKT signaling in lung cancer cells

Background: High mobility group A1 (HMGA1), a member of the non-histone chromosomal proteins and commonly referred to as architectural transcription factor, regulates transcription of various genes involved in cell growth and survival. Overexpression of HMGA1 has been shown to be associated with tumor progression and metastasis in several cancers, including human lung cancer. A recent study demonstrated that HMGA1 activates AKT function by reducing the activity of the protein phosphatase, phosphatase 2A subunitB (PPPR2A) via the oncogenic micro (mi) RNA-222. We demonstrated that interleukin (IL)-24, a novel tumor suppressor/cytokine, inhibited AKT in lung cancer cells. However, the molecular mechanism of AKT inhibition by IL-24 remains elusive.

Aim: To determine the molecular mechanism of IL-24-mediated AKT inhibition involved the HMGA1/miR-222 axis.

Methods: Human H1299 lung tumor cell line was stably transfected with a tetracycline-inducible plasmid vector carrying the IL-24. After the induced expression of IL-24 protein, expression levels of HMGA1 and its downstream molecular mechanisms were analyzed at the RNA and protein levels in lung cancer cell lines. The inhibitory effect of IL-24 on HMG A1/miR222 /AKT axis in the lung cancer cells is determined by RT-qPCR, western blot, reporter assay, and immunocytochemistry. Mechanistic approaches on overexpression and knockdown of HMGA1 and or miR-222 were utilized and the consequences of its inhibition/overexpression were analyzed on HMGA1/miR222 /AKT signaling axis and in vitro migration and invasion.

Results: Upon induction of IL-24 expression in the H1299 lung tumor cells, we observed a marked reduction in HMGA1protein and mRNA levels. Using a mechanistic approach, we found that IL-24 reduced miR-222-3p and -5p levels, as determined by qRT-PCR. Associated with HMGA1 and miR-222 inhibition was a marked increase in PPP2R2A, with a concomitant decrease in phosphorylated AKTT308/S473 expression. SiRNA-mediated knockdown of HMGA1in combination with IL-24 significantly reduced AKT T308/S473 protein expression and greatly reduced cell migration and invasion compared with individual treatments. Further combination of IL-24 and a miR-222-3p inhibitor significantly increased PPP2R2A expression.

Conclusion: Our results demonstrate for the first time that IL-24 inhibits AKT via regulating the HMGA1/miR-222 signaling node in human lung cancer cells and acts as an effective tumor suppressor. HMGA1 should present a novel target for the effective treatment of lung cancer.

Citation Format: Janani Panneerselvam, Akhil Srivastava, Ranganayaki Muralidharan, Qi Wang, Wei Zheng, Lichao Zhao, Allshine Chen, Yan Zhao, Anupama Munshi, Rajagopal Ramesh. IL-24 modulates the high mobility group (HMG) A1/miR222 /AKT signaling in lung cancer cells. [abstract]. In: Proceedings of the 107th Annual Meeting of the American Association for Cancer Research; 2016 Apr 16-20; New Orleans, LA. Philadelphia (PA): AACR; Cancer Res 2016;76(14 Suppl):Abstract nr 3738.

Folate receptor-targeted nanoparticle delivery of HuR-RNAi suppresses lung cancer cell proliferation and migration

BACKGROUND

Human antigen R (HuR) is an RNA binding protein that is overexpressed in many human cancers, including lung cancer, and has been shown to regulate the expression of several oncoproteins. Further, HuR overexpression in cancer cells has been associated with poor-prognosis and therapy resistance. Therefore, we hypothesized that targeted inhibition of HuR in cancer cells should suppress several HuR-regulated oncoproteins resulting in an effective anticancer efficacy. To test our hypothesis, in the present study we investigated the efficacy of folate receptor-α (FRA)-targeted DOTAP:Cholesterol lipid nanoparticles carrying HuR siRNA (HuR-FNP) against human lung cancer cells.

RESULTS

The therapeutic efficacy of HuR-FNP was tested in FRA overexpressing human H1299 lung cancer cell line and compared to normal lung fibroblast (CCD16) cells that had low to no FRA expression. Physico-chemical characterization studies showed HuR-FNP particle size was 303.3 nm in diameter and had a positive surface charge (+4.3 mV). Gel retardation and serum stability assays showed that the FNPs were efficiently protected siRNA from rapid degradation. FNP uptake was significantly higher in H1299 cells compared to CCD16 cells indicating a receptor-dose effect. The results of competitive inhibition studies in H1299 cells demonstrated that HuR-FNPs were efficiently internalized via FRA-mediated endocytosis. Biologic studies demonstrated HuR-FNP but not C-FNP (control siRNA) induced G1 phase cell-cycle arrest and apoptosis in H1299 cells resulting in significant growth inhibition. Further, HuR-FNP exhibited significantly higher cytotoxicity against H1299 cells than it did against CCD16 cells. The reduction in H1299 cell viability was correlated with a marked decrease in HuR mRNA and protein expression. Further, reduced expression of HuR-regulated oncoproteins (cyclin D1, cyclin E, and Bcl-2) and increased p27 tumor suppressor protein were observed in HuR-FNP-treated H1299 cells but not in C-FNP-treated cells. Finally, cell migration was significantly inhibited in HuR-FNP-treated H1299 cells compared to C-FNP.

CONCLUSIONS

Our results demonstrate that HuR is a molecular target for lung cancer therapy and its suppression using HuR-FNP produced significant therapeutic efficacy in vitro.

Phosphorylation of interleukin (IL)-24 is required for mediating its anti-cancer activity

Interleukin (IL)-24 is a tumor suppressor/cytokine gene that undergoes post-translational modifications (PTMs). Glycosylation and ubiquitination are important for IL-24 protein stabilization and degradation respectively. Little is known about IL-24 protein phosphorylation and its role in IL-24-mediated anti-tumor activities. In this study we conducted molecular studies to determine whether IL-24 phosphorylation is important for IL-24-mediated anti-cancer activity.

Human H1299 lung tumor cell line that was stably transfected with a doxycycline (DOX)-inducible (Tet-on) plasmid vector carrying the cDNA of IL-24-wild-type (IL-24^wt) or IL-24 with all five phosphorylation sites replaced (IL-24^mt) was used in the present study. Inhibition of tumor cell proliferation, cell migration and invasion, and induction of G2/M cell cycle arrest was observed in DOX-induced IL-24^wt-expressing cells but not in IL-24^mt-expressing cells. Secretion of IL-24^mt protein was greatly reduced compared to IL-24^wt protein. Further, IL-24^wt and IL-24^mt proteins markedly differed in their subcellular organelle localization. IL-24^wt but not IL-24^mt inhibited the AKT/mTOR signaling pathway. SiRNA-mediated AKT knockdown and overexpression of myristolyated AKT protein confirmed that IL-24^wt but not IL-24^mt mediated its anti-cancer activity by inhibiting the AKT signaling pathway.

Our results demonstrate that IL-24 phosphorylation is required for inhibiting the AKT/mTOR signaling pathway and exerting its anti-cancer activities.

Full Electroresistance Modulation in a Mixed-Phase Metallic Alloy

We report a giant, ∼22%, electroresistance modulation for a metallic alloy above room temperature. It is achieved by a small electric field of 2  kV/cm via piezoelectric strain-mediated magnetoelectric coupling and the resulting magnetic phase transition in epitaxial FeRh/BaTiO_{3} heterostructures. This work presents detailed experimental evidence for an isothermal magnetic phase transition driven by tetragonality modulation in FeRh thin films, which is in contrast to the large volume expansion in the conventional temperature-driven magnetic phase transition in FeRh. Moreover, all the experimental results in this work illustrate FeRh as a mixed-phase model system well similar to phase-separated colossal magnetoresistance systems with phase instability therein.

DNA Repair Gene (XRCC1) Polymorphism (Arg399Gln) Associated with Schizophrenia in South Indian Population: A Genotypic and Molecular Dynamics Study

This paper depicts the first report from an Indian population on the association between the variant Arg399Gln of XRCC1 locus in the DNA repair system and schizophrenia, the debilitating disease that affects 1% of the world population. Genotypic analysis of a total of 523 subjects (260 patients and 263 controls) revealed an overwhelming presence of Gln399Gln in the case subjects against the controls (P < 0.0068), indicating significant level of association of this nsSNP with schizophrenia; the Gln399 allele frequency was also perceptibly more in cases than in controls (p < 0.003; OR = 1.448). The results of the genotypic studies were further validated using pathogenicity and stability prediction analysis employing computational tools [I-Mutant Suite, iStable, PolyPhen2, SNAP, and PROVEAN], with a view toassess the magnitude of deleteriousness of the mutation. The pathogenicity analysis reveals that the nsSNP could be deleterious inasmuch as it could affect the functionality of the gene, and interfere with protein function. Molecular dynamics simulation of 60ns was performed using GROMACS to analyse structural change due to a mutation (Arg399Gln) that was never examined before. RMSD, RMSF, hydrogen bonds, radius of gyration and SASA analysis showedthe existence of asignificant difference between the native and the mutant protein. The present study gives astrong indication that the XRCC1 locus deserves serious attention, as it could be a potential candidatecontributing to the etio-pathogenesis of the disease.

Antiproliferative activity of cationic and neutral thiosemicarbazone copper(ii) complexes

Three new copper(ii) thiosemicarbazone complexes were synthesized and characterized. The DNA/protein binding and antiproliferative activity of the complexes have been described.

Environmental safety level of lead (Pb) pertaining to toxic effects on grey mullet (Mugil cephalus) and tiger perch (Terapon jarbua)

Acute and chronic bioassay toxicity test of Lead (Pb) in Grey Mullet (Mugil cephalus), and Tiger perch (Terapon jarbua) was conducted. LC50 values (Lethal Concentration) from acute tests and chronic values were calculated by the geometric mean of the No-Observed-Effect Concentration (NOEC) and the Lowest-Observed-Effect Concentration (LOEC) in a study period of 30 days. This research was conducted to evaluate the quantitative relationship between toxicity test statistics and correlation between toxicant and the organisms exposed. Three test average LC50 was analyzed for 24, 48, 72, and 96 h and the 96 h average LC50 of M. cephalus and T. jarbua is 2.57 ± 0.47 and 2.99 ± 0.23 mg/L of Pb, respectively. Significant correlation is observed with the increased time duration and exposure concentration. The NOEC and LOEC values were calculated based on survival of test organisms for M. cephalus and T. jarbua and the values are 0.014 and 0.029 and 0.011 and 0.022 mg/L, respectively. The chronic value is found to be 0.011 mg/L for M. cephalus and 0.021 mg/L for T. jarbua. The intensity of biochemical and histological alterations increased gradually with increased Pb concentration and the exposure time. Toxicity testing is the primary step to determine the water quality safe limit on marine organisms. The outcome of the study indicates that the sensitivity of juvenile organisms to Pb, persistence of toxic effects and biomarkers as a tool capable of revealing the toxic effects of heavy metals on the environment and aquatic biota.

Exosomes: a role for naturally occurring nanovesicles in cancer growth, diagnosis and treatment

Exosomes are 30-100 nm bodies secreted from almost all types of cells into the extracellular spaces. They enclose in their lumen active genetic information in the form of messenger RNA (mRNA), micro RNA (miRNA), DNA and active peptides that are representative of the parental cell and can be isolated from different body fluids. Exosomes can participate in inter-cellular communication by trafficking molecules to their target cells. Because they can stably carry cargo including miRNA, mRNA, and proteins and can pass through stringent biological barriers (e.g., blood brain barrier) without eliciting an immune response, they are considered as an ideal acellular vehicle for drug delivery. In this review, we describe the structure and biogenesis of exosomes and new directions related to their role in diagnosis and treatment of diseases, especially for cancer. We also discuss potential challenges associated with exosomes that should be addressed before exosome-based therapy can be applied to clinical settings.

Tumor-targeted and pH-controlled delivery of doxorubicin using gold nanorods for lung cancer therapy

Background

In lung cancer, the efficacy of conventional chemotherapy is limited due to poor drug accumulation in tumors and nonspecific cytotoxicity. Resolving these issues will increase therapeutic efficacy.

Methods

GNR-Dox-Tf-NPs (gold nanorod-doxorubicin-transferrin-nanoparticles) were prepared by different chemical approaches. The efficacy of these nanoparticles was carried out by cell viability in lung cancer and primary coronary artery smooth muscle cells. The receptor-mediated endocytosis studies were done with human transferrin and desferrioxamine preincubation. The GNR-Dox-Tf nanoparticles induced apoptosis, and DNA damage studies were done by Western blot, H2AX foci, and comet assay.

Results

We developed and tested a gold nanorod-based multifunctional nanoparticle system (GNR-Dox-Tf-NP) that carries Dox conjugated to a pH-sensitive linker and is targeted to the transferrin receptor overexpressed in human lung cancer (A549, HCC827) cells. GNR-Dox-Tf-NP underwent physicochemical characterization, specificity assays, tumor uptake studies, and hyperspectral imaging. Biological studies demonstrated that transferrin receptor-mediated uptake of the GNR-Dox-Tf-NP by A549 and HCC827 cells produced increased DNA damage, apoptosis, and cell killing compared with nontargeted GNR-Dox-NP. GNR-Dox-Tf-NP-mediated cytotoxicity was greater (48% A549, 46% HCC827) than GNR-Dox-NP-mediated cytotoxicity (36% A549, 39% HCC827). Further, GNR-Dox-Tf-NP markedly reduced cytotoxicity in normal human coronary artery smooth muscle cells compared with free Dox.

Conclusion

Thus, GNR-Dox-Tf nanoparticles can selectively target and deliver Dox to lung tumor cells and alleviate free Dox-mediated toxicity to normal cells.

Determinant role for the gep oncogenes, Gα12/13, in ovarian cancer cell proliferation and xenograft tumor growth

Recent studies have shown that the gip2 and gep oncogenes defined by the α-subunits of Gi2 and G12 family of G proteins, namely Gαi2 and Gα12/13, stimulate oncogenic signaling pathways in cancer cells including those derived from ovarian cancer. However, the critical α-subunit involved in ovarian cancer growth and progression in vivo remains to be identified. Using SKOV3 cells in which the expressions of individual Gα-subunits were silenced, we demonstrate that the silencing of Gα12 and Gα13 drastically attenuated serum- or lysophosphatidic acid-stimulated proliferation. In contrast, the invasive migration of these cells were reduced only by the silencing of Gαi2 or Gα13. Analyses of the xenograft tumors derived from these Gα-silenced cells indicated that only the silencing of Gα13 drastically reduced xenograft tumor growth and prolonged the survival of the mice. Similar, but albeit reduced, effect was seen with the silencing of Gα12. On the contrary, the silencing of Gαi2 or Gαq failed to exert such effect. Thus, our studies establish for the first time that Gα12/13, the putative gep oncogenes, are the determinant α-subunits involved in ovarian cancer growth in vivo and their increased oncogenicity can be correlated with its ability to stimulate both proliferation and invasive migration.

Drivers of information disclosure on health information exchange platforms: insights from an exploratory empirical study

OBJECTIVE

The objective of this research is to empirically explore the drivers of patients' consent to sharing of their medical records on health information exchange (HIE) platforms.

MATERIALS AND METHODS

The authors analyze a dataset consisting of consent choices of 20,076 patients in Western New York. A logistic regression is applied to empirically investigate the effects of patients' age, gender, complexity of medical conditions, and the role of primary care physicians on patients' willingness to disclose medical information on HIE platforms.

RESULTS

The likelihood of providing consent increases by age (odds ratio (OR) = 1.055; P < .0001). Female patients are more likely to provide consent (OR = 1.460; P = .0003). As the number of different physicians involved in the care of the patient increases, the odds of providing consent slightly increases (OR = 1.024; P = .0031). The odds of providing consent is significantly higher for the patients whom a primary care physician has been involved in their medical care (OR = 1.323; P < .0001).

CONCLUSION

Individual-level characteristics are important predictors of patients' willingness to disclose their medical information on HIE platforms.

Abstract 1713: IL-24 inhibits lung cancer cell migration and invasion by disrupting the SDF-1/CXCR4 signaling axis

Introduction

The stromal cell derived factor (SDF)-1/chemokine receptor (CXCR)-4 signaling pathway plays a key role in lung cancer metastasis. Therefore, disrupting the SDF-1/CXCR4 signaling axis will reduce the incidence of lung metastasis. In the present study we investigated whether interleukin (IL)-24 can inhibit the SDF-1/CXCR4 axis and suppress lung cancer cell migration and invasion in vitro. Further, the efficacy of IL-24 in combination with CXCR4 antagonists was investigated.

Methods

Human H1299 lung tumor cell line was stably transfected with a tetracycline-inducible plasmid vector carrying the IL-24. Upon addition of doxycycline (Dox; 1μg/ml), cells were induced to express IL-24 protein. The expression levels of CXCR4 and its downstream molecular mechanisms in H1299 cells were analyzed. The inhibitory effect of IL-24 on SDF-1/CXCR4 axis is determined by RT-qPCR, western blot, luciferase reporter assay, flow-cytometry and immuno-cytochemistry and the consequence of its inhibition on cell migration, and invasion.

Results

Endogenous CXCR4 protein expression levels varied among four human lung cancer cell lines with H1299 cells showing the highest expression. Doxycycline-induced IL-24 expression in the H1299-IL-24 cell line resulted in reduced CXCR4 mRNA and protein expression. IL-24 post-transcriptionally regulated CXCR4 mRNA expression by decreasing the half-life of CXCR4 mRNA (&gt;40%). Associated with CXCR4 inhibition was the reduced protein expression of pAKTS473, pmTORS2448, pPRAS40T246 and HIF-1α. IL-24 inhibited tumor cell migration and invasion both in the presence and absence of the CXCR4 agonist, SDF-1. However, the combinatorial effect of either IL-24 combined with CXCR4 inhibitors (AMD3100, SJA5) or with CXCR4 siRNA demonstrated enhanced inhibitory activity on tumor cell migration.

Conclusions

Our study results demonstrate that IL-24 inhibits lung tumor cell migration and invasion by disrupting the SDF-1/CXCR4 signaling pathway and exhibits enhanced anti-metastatic activity when combined with CXCR4 inhibitors.

Citation Format: Janani Panneerselvam, Jiankang Jin, Manish Shanker, Jason Lauderdale, Jonathan Bates, Qi Wang, Daniel Zhao, Stephen Archibald, Timothy Hubin, Rajagopal Ramesh. IL-24 inhibits lung cancer cell migration and invasion by disrupting the SDF-1/CXCR4 signaling axis. [abstract]. In: Proceedings of the 106th Annual Meeting of the American Association for Cancer Research; 2015 Apr 18-22; Philadelphia, PA. Philadelphia (PA): AACR; Cancer Res 2015;75(15 Suppl):Abstract nr 1713. doi:10.1158/1538-7445.AM2015-1713

Abstract 3306: The RNA-binding protein HuR radiosensitizes human TNBC cells by modulating the cellular response to DNA damage and oxidative stress

The RNA-binding protein human antigen R (HuR) associates with U-/AU-rich mRNAs encoding proteins that control cell proliferation, metabolism and the stress response. HuR is overexpressed in several human cancers and its overexpression is associated with poor prognosis and resistance to therapy. While the role of HuR in drug resistance has been studied, its contribution to radiation resistance has not been examined. Therefore, we investigated the role of HuR in radiation resistance of triple negative breast cancer (TNBC) cells: MDA-MB-231, MDA-MB-468 and Hs578t. Reduction of HuR expression using small interfering (si) RNA decreased cell proliferation and sensitized TNBC cells to ionizing radiation. Clonogenic assays indicated that silencing HuR suppressed the clonogenic survival of all three TNBC cell lines with survival at 2 Gy (SF2) reduced from 59%, 49%, 65% in control cells to 40%, 33%, and 46% in siHuR-treated MDA-MB-231, MDA-MB-468 and Hs578t cells, respectively. To delineate the underlying mechanism of radiosensitization and to identify candidate mRNAs showing altered levels after silencing HuR, we undertook a ribonomic approach. First, since ionizing radiation enhances the production of reactive oxygen species (ROS), causing DNA damage, we investigated the possible involvement of ROS in siHuR-mediated radiosensitization. ROS production in control or HuR-silenced cells treated with or without radiation was measured using the fluorescent dye 2′-7′-Dichlorodihydrofluorescein diacetate (DCFDA). Radiation significantly increased ROS generation in HuR knockdown cells compared to control cells. To further test the involvement of ROS in radiosensitivity, control and HuR-silenced cells were pre-treated with N-Acetyl-L- cysteine (NAC), an ROS scavenger, prior to radiation. The presence of NAC completely prevented radiation sensitivity and ROS production, indicating the involvement of ROS in HuR-mediated radiation sensitivity. Second, we directly tested the involvement of the DNA damage response (DDR) pathway in radiosensitivity after silencing HuR by evaluating the number of γ-H2AX foci (a common indicator of DNA damage) in control and HuR-silenced cells following irradiation. Our results showed that the number of γ-H2AX foci was significantly greater in HuR-silenced cells than in control cells at 1 h, 2 h and 24 h after irradiation. The persistence of γ-H2AX foci suggests that radiosensitization by HuR silencing involves inhibition of the repair of damaged DNA. This hypothesis was supported by the comet assay, which showed that HuR-silenced cells had larger and longer-lasting tails than control cells, in keeping with the higher levels of DNA damage seen after silencing HuR. Our studies indicate that radiosensitization upon HuR knockdown is linked to suppression of the cellular response to genotoxic and oxidative damage.

Citation Format: Meghna Mehta, James Griffith, Kanthesh Basalingappa, Anish Babu, Narsireddy Amreddy, Ranganayaki Muralidharan, Myriam Gorospe, Terence Herman, Wei-Qun Ding, Rajagopal Ramesh, Anupama Munshi. The RNA-binding protein HuR radiosensitizes human TNBC cells by modulating the cellular response to DNA damage and oxidative stress. [abstract]. In: Proceedings of the 106th Annual Meeting of the American Association for Cancer Research; 2015 Apr 18-22; Philadelphia, PA. Philadelphia (PA): AACR; Cancer Res 2015;75(15 Suppl):Abstract nr 3306. doi:10.1158/1538-7445.AM2015-3306

Probing single magnon excitations in Sr₂IrO₄ using O K-edge resonant inelastic x-ray scattering

Resonant inelastic x-ray scattering (RIXS) at the L-edge of transition metal elements is now commonly used to probe single magnon excitations. Here we show that single magnon excitations can also be measured with RIXS at the K-edge of the surrounding ligand atoms when the center heavy metal elements have strong spin-orbit coupling. This is demonstrated with oxygen K-edge RIXS experiments on the perovskite Sr2IrO4, where low energy peaks from single magnon excitations were observed. This new application of RIXS has excellent potential to be applied to a wide range of magnetic systems based on heavy elements, for which the L-edge RIXS energy resolution in the hard x-ray region is usually poor.

IL-24 inhibits lung cancer cell migration and invasion by disrupting the SDF-1/CXCR4 signaling axis

Background

The stromal cell derived factor (SDF)-1/chemokine receptor (CXCR)-4 signaling pathway plays a key role in lung cancer metastasis and is molecular target for therapy. In the present study we investigated whether interleukin (IL)-24 can inhibit the SDF-1/CXCR4 axis and suppress lung cancer cell migration and invasion in vitro. Further, the efficacy of IL-24 in combination with CXCR4 antagonists was investigated.

Methods

Human H1299, A549, H460 and HCC827 lung cancer cell lines were used in the present study. The H1299 lung cancer cell line was stably transfected with doxycycline-inducible plasmid expression vector carrying the human IL-24 cDNA and used in the present study to determine the inhibitory effects of IL-24 on SDF-1/CXCR4 axis. H1299 and A549 cell lines were used in transient transfection studies. The inhibitory effects of IL-24 on SDF1/CXCR4 and its downstream targets were analyzed by quantitative RT-PCR, western blot, luciferase reporter assay, flow cytometry and immunocytochemistry. Functional studies included cell migration and invasion assays.

Principal Findings

Endogenous CXCR4 protein expression levels varied among the four human lung cancer cell lines. Doxycycline-induced IL-24 expression in the H1299-IL24 cell line resulted in reduced CXCR4 mRNA and protein expression. IL-24 post-transcriptionally regulated CXCR4 mRNA expression by decreasing the half-life of CXCR4 mRNA (>40%). Functional studies showed IL-24 inhibited tumor cell migration and invasion concomitant with reduction in CXCR4 and its downstream targets (pAKT^S473, pmTOR^S2448, pPRAS40^T246 and HIF-1α). Additionally, IL-24 inhibited tumor cell migration both in the presence and absence of the CXCR4 agonist, SDF-1. Finally, IL-24 when combined with CXCR4 inhibitors (AMD3100, SJA5) or with CXCR4 siRNA demonstrated enhanced inhibitory activity on tumor cell migration.

Conclusions

IL-24 disrupts the SDF-1/CXCR4 signaling pathway and inhibits lung tumor cell migration and invasion. Additionally, IL-24, when combined with CXCR4 inhibitors exhibited enhanced anti-metastatic activity and is an attractive therapeutic strategy for lung metastasis.

Binuclear ruthenium(III) bis(thiosemicarbazone) complexes: synthesis, spectral, electrochemical studies and catalytic oxidation of alcohol

A new series of binuclear ruthenium(III) thiosemicarbazone complexes of general formula [(EPh3)2(X)2Ru-L-Ru(X)2(EPh3)2] (where E=P or As; X=Cl or Br; L=NS chelating bis(thiosemicarbazone ligands) has been synthesized and characterized by analytical and spectral (FT-IR, UV-Vis and EPR). IR spectra show that the thiosemicarbazones behave as monoanionic bidentate ligands coordinating through the azomethine nitrogen and thiolate sulphur. The electronic spectra of the complexes indicate that the presence of d-d and intense LMCT transitions in the visible region. The complexes are paramagnetic (low spin d(5)) in nature and all the complexes show rhombic distortion around the ruthenium ion with three different 'g' values (gx≠gy≠gz) at 77K. All the complexes are redox active and exhibit an irreversible metal centered redox processes (Ru(III)-Ru(III)/Ru(IV)-Ru(IV); Ru(III)-Ru(III)/Ru(II)-Ru(II)) within the potential range of 0.38-0.86V and -0.39 to -0.66 V respectively, versus Ag/AgCl. Further, the catalytic efficiency of one of the complexes [Ru2Cl2(AsPh3)4(L1)] (4) has been investigated in the case of oxidation of primary and secondary alcohols into their corresponding aldehydes and ketones in the presence of N-methylmorpholine-N-oxide(NMO) as co-oxidant. The formation of high valent Ru(V)O species is proposed as catalytic intermediate for the catalytic cycle.

Characterization of bacteria degrading 3-hydroxy palmitic acid methyl ester (3OH-PAME), a quorum sensing molecule of Ralstonia solanacearum

Bacterial wilt pathogen Ralstonia solanacearum causes severe crop loss of eggplant, which is of economic importance in India. 3-hydroxy palmitic acid methyl ester (3OH-PAME) is the main quorum sensing molecule governing the expression of virulence factors in R. solanacearum. Ability of 164 bacterial isolates from the xylem of eggplant (Solanum melongena L.), chilli pepper (Capsicum annuum L.) and wild eggplant (Solanum torvum Sw.) to degrade 3OH-PAME was tested by disc diffusion assay. Enzymatic degradation of 3OH-PAME by five bacteria was confirmed by High-Performance Liquid Chromatography-Mass Spectrometry analysis. 3OH-PAME degrading bacteria were identified as Stenotrophomonas maltophilia, Pseudomonas aeruginosa and Rhodococcus corynebacterioides. 3OH-PAME degrading bacteria reduced the expression of virulence factors (exopolysaccharides and endoglucanase) of R. solanacearum in vitro and reduced wilt incidence in eggplant seedlings under greenhouse conditions. Isolates with quorum quenching activity successfully re-colonized eggplant seedlings. Quorum quenching bacteria produced antagonistic compounds, which may act synergistically with quorum quenching in reducing bacterial wilt in eggplant.

SIGNIFICANCE AND IMPACT OF THE STUDY

This is the first report on endophytic bacteria of class Gammaproteobacteria and phylum Actinobacteria having 3OH-PAME degrading activity. This study demonstrates the potential use of endophytic bacteria as quorum quenching biocontrol agents for management of bacterial wilt in eggplant.

Abstract 3943: siRNA-mediated HuR silencing sensitizes triple-negative breast cancer cells to radiation therapy

HuR is a ubiquitously expressed member of the Elav/Hu family of RNA-binding proteins which can associate with mRNAs containing AU-rich elements in their 3′-untranslated regions. It is predominantly a nuclear protein that translocates to the cytoplasm in response to stress signals and stabilizes mRNAs encoding proteins implicated in cell proliferation, angiogenesis, apoptosis, and stress response. Studies examining HuR expression in human cancers indicated that elevated cytoplasmic HuR expression is associated with a high histologic grade, large tumor size, and poor survival of patients with cancer, leading to the hypothesis that cytoplasmic HuR abundance could be a prognostic marker in cancer patients. It has been reported that altering the subcellular distribution of HuR leads to a decrease in mRNA stability and increases tamoxifen responsiveness in breast cancer cells. As the role of HuR in radiation resistance has not been previously evaluated, we designed this study to determine the role of HuR in mediating radiation response of human breast cancer cells. Subcellular fractionation studies in a panel of breast cancer cells [triple negative (MDA-MB-231, MDA-MB-468 and Hs578t), luminal (MCF-7), and normal mammary epithelial (MCF-10a)] demonstrated elevated cytoplasmic levels of HuR in the more aggressive triple negative breast cancer cells (TNBC) compared to the normal mammary and the luminal cells. TNBCs also had high expression of HuR mRNA and total protein as observed by quantitative (Q) RT-PCR and western blot analysis. To test if high expression of HuR contributed to the radiation resistance of TNBCs, HuR was silenced and cells were exposed to various doses of radiation. Clonogenic assays indicated that silencing HuR enhanced tumor cell radiosensitivity in MDA-MB-231, MDA-MB-468 and Hs578t cells, with the survival fraction at 2Gy declining from 59%, 49%, 65% in control (scrambled siRNA-transfected cells) to 40%, 33%, 46% in HuR-silenced cells, respectively. MCF-7 and MCF-10a cells were not radiosensitized upon HuR silencing. Since HuR plays a central role in cancer it is possible that multiple pathways and mechanisms are affected by HuR knockdown and could contribute to the observed radiosensitivity. Molecular studies suggested that HuR silencing in combination with radiation modulated the expression of several genes involved in cell survival, cell cycle and DNA repair in MDA-MB-231 cells. The involvement of the DNA repair pathway following treatment with siHuR was assessed using γ-H2AX foci as a marker. Our results show that a higher number of radiation-induced γ-H2AX foci are present in HuR-silenced MDA-MB-231 cells compared with control cells, suggesting a suppression of the double-strand DNA repair pathway. The persistence of γ-H2AX foci was not seen in the MCF-7 cells. We propose that HuR knockdown enhances the radioresponse of TNBC cells by inhibiting the repair of radiation-induced double-strand DNA breaks.

Citation Format: Kanthesh M. Basalingappa, Meghna Mehta, James N. Griffith, Ranganayaki Muralidharan, Myriam Gorospe, Rajagopal Ramesh, Anupama Munshi. siRNA-mediated HuR silencing sensitizes triple-negative breast cancer cells to radiation therapy. [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 3943. doi:10.1158/1538-7445.AM2014-3943

Abstract 5418: Tumor-targeted nanoparticle delivery of HuR-RNAi suppresses lung cancer cell proliferation and cell migration

Objective. HuR is an mRNA-binding protein that specifically binds to AU rich (ARE) sites at the 3′end of the mRNA of several growth factors, cell-cycle regulators, and transcription-regulating proteins and transports the mRNA to the cytoplasm for protein translation. HuR overexpression has been demonstrated to be a poor prognostic marker in a spectrum of human cancers and correlate with chemotherapy resistance. On the basis of these reports we hypothesized HuR is a druggable target for cancer therapy and its inhibition will down-regulate multiple oncoproteins resulting in efficient tumor cell killing. To test our hypothesis, we developed and tested the efficacy of a nanoparticle (NP) containing HuR-specific siRNA and targeted towards folate receptor (Fr) overexpressing lung cancer cells in vitro.

Methods. Human lung cancer (H1299, A549) and normal fibroblast (MRC-9) cell lines were used in the present study. Folate receptor (Fr) overexpressing KB cell line was used as positive control. Tumor targeted nanoparticle was synthesized by mixing cationic lipid (DOTAP) with a neutral lipid (cholesterol) in equimolar ratio. The NPs thus formed were used to encapsulate fluorescently labeled siRNA for determining transfection efficiency; scrambled (control) siRNA or HuR-specific siRNA (100 nm) for efficacy studies. The control- and HuR-siRNA-containing NPs were subsequently decorated with DSPE-PEG5000-folate and labeled as C-FNP and HuR-FNP respectively. Transfection efficiency, NP specificity, cell viability, cell migration and HuR knock down studies were performed using standard laboratory assay protocols.

Results. HuR protein expression in H1299 and A549 was higher than in MRC-9 cell line. Folate receptor (Fr) expression from highest to lowest was in the following order KB&gt; H1299&gt;MRC9. Fr expression was not detected in A549 cells. Transfection efficiency study showed FNP uptake was highest in KB cells followed by H1299 cells with lowest uptake by A549 cells. Addition of exogenous folic acid resulted in reduced FNP uptake by H1299 cells demonstrating NP specificity towards Fr. Treatment of H1299 cells with HuR-FNP significantly reduced cell viability at 48h compared to C-FNP-treatment and correlated with a marked reduction in HuR mRNA and protein expression levels. Analysis for proteins whose mRNAs are targets for and regulated by HuR (Bcl2, Cyclin D1, HIF-1α) showed diminished expression in HuR-FNP-treated cells. Finally, cell migration was significantly inhibited in HuR-FNP-treated H1299 cells compared to C-FNP treatment.

Conclusions. Tumor-targeted nanoparticle delivery of HuR-RNAi in lung cancer cells selectively inhibited HuR and HuR-regulated oncoproteins resulting in diminished cell proliferation and cell migration in vitro.

Acknowledgement. This study was funded by a grant (R01CA167516-01) from the National Cancer Institute.

Citation Format: Ranganayaki Muralidharan, Anish Babu, Kanthesh Basalingappa, Anupama Munshi, Rajagopal Ramesh. Tumor-targeted nanoparticle delivery of HuR-RNAi suppresses lung cancer cell proliferation and cell migration. [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 5418. doi:10.1158/1538-7445.AM2014-5418

Anisotropic magnetoresistance in an antiferromagnetic semiconductor

Recent studies in devices comprising metal antiferromagnets have demonstrated the feasibility of a novel spintronic concept in which spin-dependent phenomena are governed by an antiferromagnet instead of a ferromagnet. Here we report experimental observation of the anisotropic magnetoresistance in an antiferromagnetic semiconductor Sr2IrO4. Based on ab initio calculations, we associate the origin of the phenomenon with large anisotropies in the relativistic electronic structure. The antiferromagnet film is exchange coupled to a ferromagnet, which allows us to reorient the antiferromagnet spin-axis in applied magnetic fields via the exchange spring effect. We demonstrate that the semiconducting nature of our AFM electrode allows us to perform anisotropic magnetoresistance measurements in the current-perpendicular-to-plane geometry without introducing a tunnel barrier into the stack. Temperature-dependent measurements of the resistance and anisotropic magnetoresistance highlight the large, entangled tunabilities of the ordinary charge and spin-dependent transport in a spintronic device utilizing the antiferromagnet semiconductor.

EGFR-targeted plasmonic magnetic nanoparticles suppress lung tumor growth by abrogating G2/M cell-cycle arrest and inducing DNA damage

Background

We have previously demonstrated the epidermal growth factor receptor (EGFR)-targeted hybrid plasmonic magnetic nanoparticles (225-NP) produce a therapeutic effect in human lung cancer cell lines in vitro. In the present study, we investigated the molecular mechanism of 225-NP-mediated antitumor activity both in vitro and in vivo using the EGFR-mutant HCC827 cell line.

Methods

The growth inhibitory effect of 225-NP on lung tumor cells was determined by cell viability and cell-cycle analysis. Protein expression related to autophagy, apoptosis, and DNA-damage were determined by Western blotting and immunofluorescence. An in vivo efficacy study was conducted using a human lung tumor xenograft mouse model.

Results

The 225-NP treatment markedly reduced tumor cell viability at 72 hours compared with the cell viability in control treatment groups. Cell-cycle analysis showed the percentage of cells in the G2/M phase was reduced when treated with 225-NP, with a concomitant increase in the number of cells in Sub-G1 phase, indicative of cell death. Western blotting showed LC3B and PARP cleavage, indicating 225-NP-treatment activated both autophagy- and apoptosis-mediated cell death. The 225-NP strongly induced γH2AX and phosphorylated histone H3, markers indicative of DNA damage and mitosis, respectively. Additionally, significant γH2AX foci formation was observed in 225-NP-treated cells compared with control treatment groups, suggesting 225-NP induced cell death by triggering DNA damage. The 225-NP-mediated DNA damage involved abrogation of the G2/M checkpoint by inhibiting BRCA1, Chk1, and phospho-Cdc2/CDK1 protein expression. In vivo therapy studies showed 225-NP treatment reduced EGFR phosphorylation, increased γH2AX foci, and induced tumor cell apoptosis, resulting in suppression of tumor growth.

Conclusion

The 225-NP treatment induces DNA damage and abrogates G2/M phase of the cell cycle, leading to cellular apoptosis and suppression of lung tumor growth both in vitro and in vivo. Our findings provide a rationale for combining 225-NP with other DNA-damaging agents for achieving enhanced anticancer activity.