Dioscin potentiates the antitumor effect of suicide gene therapy in melanoma by gap junction intercellular communication-mediated antigen cross-presentation.

Dioscin (Dio), steroid saponin, exists in several medicinal herbs with potent anticancer efficacy. This study aimed to explore the effect of Dio on the immune-related modulation and synergistic therapeutic effects of the herpes simplex virus thymidine kinase/ganciclovir (HSV-Tk/GCV) suicide gene therapy system in murine melanoma, thereby providing a research basis to improve the potential immunomodulatory mechanism underlying combination therapy. Using both in vitro and in vivo experiments, we confirmed the immunocidal effect of Dio-potentiated suicide gene therapy on melanoma. The results showed that Dio upregulated connexin 43 (Cx43) expression and improved gap junction intercellular communication (GJIC) in B16 cells while increasing the cross-presentation of antigens by dendritic cells (DCs), eventually promoting the activation and antitumor immune killing effects of CD8+ T lymphocytes. In contrast, inhibition or blockade of the GJIC function (overexpression of mutant Cx43 tumor cells/Gap26) partially reversed the potentiating effect. The significant synergistic effect of Dio on HSV-Tk/GCV suicide gene therapy was further investigated in a B16 xenograft mouse model. The increased number and activation ratio of CD8+ T lymphocytes and the levels of Gzms-B, IFN-γ, and TNF-α in mice reconfirmed the potential modulatory effects of Dio on the immune system. Taken together, Dio targets Cx43 to enhance GJIC function, improve the antigens cross-presentation of DCs, and activate the antitumor immune effect of CD8+ T lymphocytes, thereby providing insights into the potential immunomodulatory mechanism underlying combination therapy.

Therapeutic Effects of Mesenchymal Stem Cells Expressing Erythropoietin on Cancer-Related Anemia in Mice Model.

BACKGROUND: Cancer-related anemia (CRA) negatively influences cancer patients' survival, disease progression, treatment efficacy, and quality of life (QOL). Current treatments such as iron therapy, red cell transfusion, and erythropoietin-stimulating agents (ESAs) may cause severe adverse effects. Therefore, the development of long-lasting and curative therapies is urgently required. OBJECTIVE: In this study, a cell and gene therapy strategy was developed for in vivo delivery of EPO cDNA by way of genetic engineering of human Wharton's jelly mesenchymal stem cells (hWJMSCs) to produce and secrete human EPO protein for extended periods after transplantation into the mice model of CRA. METHODS: To evaluate CRA's treatment in cancer-free and cancerous conditions, first, a recombinant breast cancer cell line 4T1 which expressed herpes simplex virus type 1 thymidine kinase (HSV1-TK) by a lentiviral vector encoding HSV1-TK was developed and injected into mice. After three weeks, all mice developed metastatic breast cancer associated with acute anemia. Then, ganciclovir (GCV) was administered for ten days in half of the mice to clear cancer cells. Meanwhile, another lentiviral vector encoding EPO to transduce hWJMSCs was developed. Following implantation of rhWJMSCs-EPO in the second group of mice, peripheral blood samples were collected once a week for ten weeks from both groups. RESULTS: Analysis of peripheral blood samples showed that plasma EPO, hemoglobin (Hb), and hematocrit (Hct) concentrations significantly increased and remained at therapeutic for >10 weeks in both treatment groups. CONCLUSION: Data indicated that rhWJMSCs-EPO increased the circulating level of EPO, Hb, and Hct in both mouse subject groups and improved the anemia of cancer in both cancer-free and cancerous mice.

Phenotypic and genotypic acyclovir resistance surveillance of genital herpes simplex virus 2 in South Africa.

Acyclovir (ACV) is currently included in the syndromic management algorithm for genital ulcer disease in South Africa, and is the recommended first-line treatment for herpes simplex virus 2 (HSV-2). In the majority of cases, HSV-2 resistance to ACV is due to amino acid changes within the viral thymidine kinase (TK). Phenotypic and genotypic ACV resistance surveillance of HSV-2 derived from genital ulcer disease swab specimens was conducted at a primary healthcare facility in Johannesburg between 2018 and 2020. The objectives of this surveillance were to identify ACV resistance-associated mutations and polymorphisms in HSV-2 TK, and to determine the phenotypic ACV resistance profiles of the corresponding clinical HSV-2 isolates. Genotypic analysis of TK from 67 HSV-2 positive genital ulcer swabs revealed 48 specimens with TK mutations, conferring 113 nucleotide changes. No resistance-associated mutations were found, however, we identified nine known natural polymorphisms (R26H, A27T, S29A, G39E, N78D, L140F, T159I, R220K and R284S) and five amino acid changes of unknown significance (R18C, G39K, M70R, P75S and L263P). Phenotypic susceptibility testing of 52 cultivable HSV-2 isolates revealed all to be susceptible to ACV with IC50 values of <2 µg/ml. The five amino acid changes of unknown significance identified by genotypic testing were not correlated to phenotypic ACV resistance, and therefore grouped as natural polymorphisms. We did not detect any unknown or resistance-associated mutations in specimens that could not be phenotypically tested for ACV resistance. Our findings will supplement existing databases of HSV antiviral resistance-associated mutations and polymorphisms that could be used for genotypic ACV resistance screening.

Nanoscale bubble ultrasound contrast agents-mediated suicide gene therapy system, Nanoscale bubble-LV5-YCD-TK/GCV/5-FC, effectively inhibits bladder cancer cell growth.

OBJECTIVE: Bladder cancer is the 2nd most common reason for human genitourinary cancer-associated mortality. This study aimed to investigate the effects of Nanoscale bubble ultrasound contrast agents-mediated yeast-cytosine-deaminase-thymidine kinase/ganciclovir (YCD-TK/GCV) or YCD-TK/5-fluorocytosine (5-FC) suicide gene therapy system on BIU-87 cell growth. MATERIALS AND METHODS: Targeted nanoscale bubble ultrasound contrast agents were prepared by utilizing thin-film hydration-sonication approach. Nanoscale bubble-LV5-YCD-TK/GCV(5-FC) was constructed and transfected to BIU-87 cells. Hematoxylin and eosin (HE) staining was used to evaluate inflammation. 3-(4,5-dimethyl-2-thiazolyl)-2,5-diphenyl-2-H-tetrazolium bromide (MTT) assay was used to examine cell viability. Cell-cycle distribution was analyzed with cell cycle assay. Flow cytometry assay was utilized to test apoptosis of BIU-87 cells. YCD-TK expression was examined using Western blot and quantitative Real Time-PCR (qRT-PCR), respectively. RESULTS: YCD-TK highly expressed in Nanoscale bubble mediated suicide gene therapy system. Nanoscale bubble-mediated suicide gene therapy system significantly induced inflammatory response and apoptosis compared to that of Nanoscale bubble group (p<0.05). Nanoscale bubble mediated suicide gene therapy system significantly reduced cell viability compared to that of the Nanoscale bubble group (p<0.05). Nanoscale bubble mediated suicide gene therapy system significantly inhibited cell cycle arrest compared to that of the Nanoscale bubble group (p<0.05). Nanoscale bubble-LV5-YCD-TK/GCV/5-FC therapy system significantly reduced BIU-87 cell viability compared to that of the Nanoscale bubble-associated groups (p<0.05). CONCLUSIONS: Nanoscale bubble-mediated suicide gene therapy system, bubble-LV5-YCD-TK/GCV/5-FC, acts as a novel therapeutic strategy for bladder cancer treatment.

Non-Small-Cell Lung Cancer: Feasibility of Intratumoral Radiofrequency Hyperthermia-enhanced Herpes Simplex Virus Thymidine Kinase Gene Therapy.

Purpose To validate the feasibility and efficacy of intratumoral radiofrequency hyperthermia (RFH)-enhanced herpes simplex virus (HSV) thymidine kinase (TK) and ganciclovir (GCV) (hereafter, HSV-TK/GCV) gene therapy for non-small-cell lung cancer (NSCLC). Materials and Methods This study was performed from November 11, 2015, to April 14, 2017, and included (a) in vitro experiments with human NSCLC cells to establish the proof of principle, (b) in vivo experiments using mice with subcutaneous NSCLC to further demonstrate the principle, and (c) in vivo experiments using rats with orthotopic NSCLC to validate the technical feasibility. Cells, nude mice, and nude rats were randomly divided into four groups (six animals per group): (a) combination therapy (HSV-TK/GCV combined with RFH), (b) RFH, (c) HSV-TK/GCV, and (d) phosphate-buffered saline. Data were analyzed by using the Dunnett t test or Kruskal-Wallis test. Results For in vitro experiments, the cell proliferation assay showed significantly diminished viable cells with combination therapy (mean, 0.56; 95% confidence interval [CI]: 0.44, 0.68) versus RFH (mean, 0.89; 95% CI: 0.82, 0.97), HSV-TK/GCV (mean, 0.71; 95% CI: 0.56, 0.86), and phosphate-buffered saline (mean, 1; 95% CI: 1, 1) (P < .05 for all). For in vivo experiments, optical imaging showed significantly decreased relative bioluminescence signal with combination therapy (mean, 0.71 [95% CI: 0.03, 1.39] in mice; 1.29 [95% CI: 0.51, 2.06] in rats) compared with RFH (mean, 2.66 [95% CI: 1.73, 3.59] in mice; 2.26 [95% CI: 1.51, 3.01] in rats), HSV-TK/GCV (mean, 1.37 [95% CI: 0.65, 2.08] in mice; 1.76 [95% CI: 1.20, 2.31] in rats), and phosphate-buffered saline (mean, 3.07 [95% CI: 2.50, 3.65] in mice; 2.94 [95% CI: 2.29, 3.58] in rats) (P < .001 for all). US showed that the smallest relative tumor volumes occurred with combination therapy (mean, 0.60; 95% CI: 0.15, 1.05) versus RFH (mean, 2.43; 95% CI: 1.80, 3.06), HSV-TK/GCV (mean, 1.32; 95% CI: 0.75, 1.89), and phosphate-buffered saline (mean, 2.56; 95% CI: 1.75, 3.38) (P < .05 for all) in the mouse subcutaneous model. Conclusion Intratumoral radiofrequency hyperthermia-enhanced herpes simplex virus thymidine kinase and ganciclovir gene therapy for non-small-cell lung cancer is feasible and can be guided by molecular imaging. © RSNA, 2018.

Low-dose rapamycin extends lifespan in a mouse model of mtDNA depletion syndrome.

Mitochondrial disorders affecting oxidative phosphorylation (OxPhos) are caused by mutations in both the nuclear and mitochondrial genomes. One promising candidate for treatment is the drug rapamycin, which has been shown to extend lifespan in multiple animal models, and which was previously shown to ameliorate mitochondrial disease in a knock-out mouse model lacking a nuclear-encoded gene specifying an OxPhos structural subunit (Ndufs4). In that model, relatively high-dose intraperitoneal rapamycin extended lifespan and improved markers of neurological disease, via an unknown mechanism. Here, we administered low-dose oral rapamycin to a knock-in (KI) mouse model of authentic mtDNA disease, specifically, progressive mtDNA depletion syndrome, resulting from a mutation in the mitochondrial nucleotide salvage enzyme thymidine kinase 2 (TK2). Importantly, low-dose oral rapamycin was sufficient to extend Tk2KI/KI mouse lifespan significantly, and did so in the absence of detectable improvements in mitochondrial dysfunction. We found no evidence that rapamycin increased survival by acting through canonical pathways, including mitochondrial autophagy. However, transcriptomics and metabolomics analyses uncovered systemic metabolic changes pointing to a potential 'rapamycin metabolic signature.' These changes also implied that rapamycin may have enabled the Tk2KI/KI mice to utilize alternative energy reserves, and possibly triggered indirect signaling events that modified mortality through developmental reprogramming. From a therapeutic standpoint, our results support the possibility that low-dose rapamycin, while not targeting the underlying mtDNA defect, could represent a crucial therapy for the treatment of mtDNA-driven, and some nuclear DNA-driven, mitochondrial diseases.

Association of the Emergence of Acyclovir-Resistant Herpes Simplex Virus Type 1 With Prognosis in Hematopoietic Stem Cell Transplantation Patients.

Background: Antiviral-resistant herpes simplex virus type 1 (HSV-1) has been recognized as an emerging clinical problem among patients undergoing hematopoietic stem cell transplantation (HSCT). Methods: A prospective observational study was conducted at a hematological center over a 2-year period. Oropharyngeal swab samples were serially collected each week from 1 week before and up to 100 days after HSCT and were tested for virus isolation. The HSV-1 isolates were tested for sensitivity to acyclovir (ACV). The prognosis of patients with ACV-resistant (ACVr) HSV-1 and the genetic background of the ACVr HSV-1 isolates were assessed. Results: Herpes simplex virus type 1 was isolated in 39 of 268 (15%) HSCT patients within 100 days after transplantation. Acyclovir-resistant HSV-1 emerged in 11 of these 39 patients (28%). The 100-day death rates of HSCT patients without HSV-1 shedding, those with only ACV-sensitive HSV-1 shedding, and those with ACVr HSV-1 shedding were 31%, 39%, and 64%, respectively. Patients with HSV-1, including ACVr HSV-1, shedding showed a significantly higher mortality rate. Relapsed malignancies were a significant risk factor for the emergence of ACVr HSV-1. Acyclovir resistance was attributable to viral thymidine kinase and DNA polymerase mutations in 6 and 5 patients, respectively. Conclusions: Herpes simplex virus type 1, including ACVr HSV-1, shedding was associated with poorer outcome in HSCT patients, even if HSV disease did not always occur. Patients with relapsed malignancies were at especially high risk for the emergence of ACVr HSV-1.

In vitro toxicological assessment of an organosulfur compound from Allium extract: Cytotoxicity, mutagenicity and genotoxicity studies.

Garlic (Allium sativum) and onion (Allium cepa) are being used in the food industry as flavoring but also for their antimicrobial activities. These activities are mainly derived from the organosulfur compounds (OSCs). Propyl propane thiosulfinate (PTS) is an OSC with potential use in the active packaging, but its safety should be guaranteed before being commercialized. The aim of this work was to investigate for the first time the cytotoxicity of PTS as well as its in vitro mutagenic/genotoxic potential using the following battery of genotoxicity tests:(1)the bacterial reverse-mutation assay in S. typhimurium (Ames test, OECD 471, 1997); (2) the micronucleus test (MN, OECD 487, 2016); (3) the mouse lymphoma thymidine-kinase assay (MLA, OECD 476, 2015), and (4) the comet assay (standard and modified with restriction enzymes). The results revealed that PTS was not mutagenic neither in the Ames test nor in MLA. However, genotoxic effects were recorded in the MN test on mammalian cells (L5178YTk+/-cells) after PTS exposure at the highest concentration tested (17.25 µM) without S9, and also its metabolites (+S9, from 20 µM). Moreover, in the comet assay, PTS induced DNA breaks damage in Caco-2 cells at the highest concentration tested (280 µM) but it did not induce oxidative DNA damage.

Effects of PUFAs in a Mouse Model of HSV-1 Chorioretinitis.

PURPOSE: To examine the effects of n-3 and n-6 polyunsaturated fatty acids (n-3 and n-6 PUFAs) in a murine model of herpetic chorioretinitis. METHODS: BALB/c mice were fed on three high fat diets, which contained: Menhaden oil (rich in n-3 PUFAs); Safflower oil (rich in n-6 PUFAs); or Corn oil (rich in saturated fatty acids) as control group, 14 days previously and until 12 days following anterior chamber (AC) HSV-1 inoculation. RESULTS: Mice fed on Menhaden oil present an early development of contralateral chorioretinitis by day 6 post-AC HSV-1 inoculation and also significant increase of RNA HSV-1 expression compared with Safflower and Corn oil groups. Furthermore, mice fed on Menhaden oil showed a significant decrease secretion of TNF-α, IFN-γ, IL-2 and IL-10 in splenic cells and both retinas. CONCLUSION: Our results showed that mice fed on Menhaden oil (n-3 PUFAs) presented an early development of contralateral chorioretinitis by day 6 post-AC HSV-1 inoculation and also a significant increase in RNA HSV-1 expression compared with animals fed on Safflower and Corn oils. This increase of HSV-1 could be associated with the higher development of chorioretinitis.

Radiofrequency hyperthermia promotes the therapeutic effects on chemotherapeutic-resistant breast cancer when combined with heat shock protein promoter-controlled HSV-TK gene therapy: Toward imaging-guided interventional gene therapy.

OBJECTIVE: Gene therapy is a frontier in modern medicine. In the present study, we explored a new technique for the effective treatment of multidrug-resistant (MDR) breast cancer by combining fully the advantages of multidisciplinary fields, including image-guided minimally invasive interventional oncology, radiofrequency technology, and direct intratumoral gene therapy. RESULTS: Combination treatment with PHSP-TK plus RFH resulted in significantly higher TK gene transfection/expression, as well as a lower cell proliferation rate and a higher cell apoptosis index, than those of control groups. In vivo validation experiments with MRI confirmed that combination therapy resulted in a significant reduction of relative tumor volume compared with those of control animals, which was supported by the results of histologic and apoptosis analyses. MATERIALS AND METHODS: The heat shock protein promoter (PHSP) was used to precisely control the overexpression of thymidine kinase (TK) (PHSP-TK). Serial in vitro experiments were performed to confirm whether radiofrequency hyperthermia (RFH) could enhance PHSP-TK transfection and expression in a MDR breast cancer cell line (MCF7/Adr). Serial in vivo experiments were then carried out to validate the feasibility of the new technique, termed interventional RFH-enhanced direct intratumoral PHSP-TK gene therapy. The therapeutic effect of combination therapy was evaluated by MRI and confirmed by subsequent laboratory correlation. CONCLUSIONS: This study has established "proof-of-principle" of a new technique, interventional RFH-enhanced local gene therapy for MDR breast cancer, which may open new avenues for the effective management of MDR breast cancers via the simultaneous integration of interventional oncology, RF technology, and direct intratumoral gene therapy.

Combination of PEI-Mn0.5Zn0.5Fe2O4 nanoparticles and pHsp 70-HSV-TK/GCV with magnet-induced heating for treatment of hepatoma.

BACKGROUND: To explore a new combination of thermal treatment and gene therapy for hepatoma, a heat-inducible herpes simplex virus thymidine kinase/ganciclovir (HSV-TK/GCV) gene therapy system was developed in which thermal energy generated by Mn0.5Zn0.5Fe2O4 nanoparticles (MZF-NPs) under an alternating magnetic field was used to activate gene expression. METHODS: First, a recombinant eukaryotic plasmid, pHsp 70-HSV-TK, was constructed as a target gene for therapy. This recombinant plasmid was used to transfect SMMC-7721 hepatoma cells and the gene expression was evaluated. Magnet-induced heating was then applied to cells to assess the antihepatoma effects of the polyethylenimine (PEI)-MZF-NPs/pHsp 70-HSV-TK/GCV complex, in vitro and in vivo. RESULTS: The results showed that cells were successfully transfected with pHsp 70-HSV-TK and that expression levels of HSV-TK remained stable. Both in vitro and in vivo results indicated that the combination of gene therapy and heat treatment resulted in better therapeutic effects than heating-alone group. The rates of apoptosis and necrosis in the combined treatment group were 49.0% and 7.21%, respectively. The rate of inhibition of cell proliferation in the combined treatment group was significantly higher (87.5%) than that in the heating-alone group (65.8%; P<0.01). The tumor volume and mass inhibition rates of the combined treatment group were 91.3% and 87.91%, respectively, and were significantly higher than the corresponding rates of the heating-alone group (70.41% and 57.14%; P<0.01). The expression levels of Stat3 and Bcl-xL messenger RNA and p-Stat3 and Bcl-xL protein in the combined treatment group were significantly lower than those in the other groups (P<0.01). The expression levels of Bax messenger RNA and protein in the recombinant plasmid group were significantly higher than those in the other groups (P<0.01). CONCLUSION: It can therefore be concluded that the combined application of heat treatment and gene therapy has a synergistic and complementary effect and that PEI-MZF-NPs can simultaneously act both as a nonviral gene vector and a magnet-induced source of heat, thereby representing a viable approach for the treatment of cancer.

Genetic modification of the diarrhoeal pathogen Cryptosporidium parvum.

Recent studies into the global causes of severe diarrhoea in young children have identified the protozoan parasite Cryptosporidium as the second most important diarrhoeal pathogen after rotavirus. Diarrhoeal disease is estimated to be responsible for 10.5% of overall child mortality. Cryptosporidium is also an opportunistic pathogen in the contexts of human immunodeficiency virus (HIV)-caused AIDS and organ transplantation. There is no vaccine and only a single approved drug that provides no benefit for those in gravest danger: malnourished children and immunocompromised patients. Cryptosporidiosis drug and vaccine development is limited by the poor tractability of the parasite, which includes a lack of systems for continuous culture, facile animal models, and molecular genetic tools. Here we describe an experimental framework to genetically modify this important human pathogen. We established and optimized transfection of C. parvum sporozoites in tissue culture. To isolate stable transgenics we developed a mouse model that delivers sporozoites directly into the intestine, a Cryptosporidium clustered regularly interspaced short palindromic repeat (CRISPR)/Cas9 system, and in vivo selection for aminoglycoside resistance. We derived reporter parasites suitable for in vitro and in vivo drug screening, and we evaluated the basis of drug susceptibility by gene knockout. We anticipate that the ability to genetically engineer this parasite will be transformative for Cryptosporidium research. Genetic reporters will provide quantitative correlates for disease, cure and protection, and the role of parasite genes in these processes is now open to rigorous investigation.

Humanized thymidine kinase-NOG mice can be used to identify drugs that cause animal-specific hepatotoxicity: a case study with furosemide.

Interspecies differences have limited the predictive utility of toxicology studies performed using animal species. A drug that could be a safe and effective treatment in humans could cause toxicity in animals, preventing it from being used in humans. We investigated whether the use of thymidine kinase (TK)-NOG mice with humanized livers could prevent this unfortunate outcome (i.e., "rescue" a drug for use in humans). A high dose of furosemide is known to cause severe liver toxicity in mice, but it is a safe and effective treatment in humans. We demonstrate that administration of a high dose of furosemide (200 mg/kg i.p.) causes extensive hepatotoxicity in control mice but not in humanized TK-NOG mice. This interspecies difference results from a higher rate of production of the toxicity-causing metabolite by mouse liver. Comparison of their survival curves indicated that the humanized mice were more resistant than control mice to the hepatotoxicity caused by high doses of furosemide. In this test case, humanized TK-NOG mouse studies indicate that humans could be safely treated with a high dose of furosemide.

Tomato thymidine kinase-based suicide gene therapy for malignant glioma--an alternative for Herpes Simplex virus-1 thymidine kinase.

Malignant gliomas (MGs) are the most common malignant primary brain tumors with a short life estimate accompanied by a marked reduction in the quality of life. Herpes Simplex virus-1 thymidine kinase ganciclovir (HSV-TK/GCV) system is the best characterized enzyme prodrug therapy in use. However, lipophobicity of GCV and low enzymatic activity of HSV-TK reduce the treatment efficacy. Tomato TK (ToTK) has shown high activity in combination with its specific substrate azidothymidine (AZT). The aim of this study was to evaluate whether ToTK/AZT could be used as an alternative to HSV-TK/GCV therapy. Both treatments demonstrated cytotoxicity in human MG cells in vitro. In vivo, both treatments decreased tumor growth and tumors were smaller in comparison with controls in mouse orthotopic MG model. Survival of ToTK/AZT-treated mice was significantly increased compared with control mice (*P<0.05) but not as compared with HSV-TK/GCV-treated mice. No significant differences were observed in clinical chemistry safety analyses. We conclude that both treatments showed a beneficial treatment response in comparison to controls on tumor growth and ToTK/AZT also on survival. There were no significant differences between these treatments. Therefore ToTK/AZT could be considered as an alternative treatment option for MG because of its favorable therapeutic characteristics.

Chimeric TK-NOG mice: a predictive model for cholestatic human liver toxicity.

Due to the substantial interspecies differences in drug metabolism and disposition, drug-induced liver injury (DILI) in humans is often not predicted by studies performed in animal species. For example, a drug (bosentan) used to treat pulmonary artery hypertension caused unexpected cholestatic liver toxicity in humans, which was not predicted by preclinical toxicology studies in multiple animal species. In this study, we demonstrate that NOG mice expressing a thymidine kinase transgene (TK-NOG) with humanized livers have a humanized profile of biliary excretion of a test (cefmetazole) drug, which was shown by an in situ perfusion study to result from interspecies differences in the rate of biliary transport and in liver retention of this drug. We also found that readily detectable cholestatic liver injury develops in TK-NOG mice with humanized livers after 1 week of treatment with bosentan (160, 32, or 6 mg/kg per day by mouth), whereas liver toxicity did not develop in control mice after 1 month of treatment. The laboratory and histologic features of bosentan-induced liver toxicity in humanized mice mirrored that of human subjects. Because DILI has become a significant public health problem, drug safety could be improved if preclinical toxicology studies were performed using humanized TK-NOG.

Thymidine kinase gene delivery using curcumin loaded peptide micelles as a combination therapy for glioblastoma.

PURPOSE: The effect of the combination therapy of curcumin and the herpes simplex virus thymidine kinase (HSVtk) gene using R7L10 as a carrier was evaluated in a glioblastoma animal model. METHODS: Curcumin was loaded into the cores of R7L10 peptide micelles using an oil-in-water emulsion/solvent evaporation method to generate curcumin loaded R7L10 micelles (R7L10-Cur), which were used as a carrier to deliver the HSVtk gene. The plasmid DNA (pDNA)/R7L10-Cur complex was confirmed by gel retardation, heparin competition, and dynamic light scattering analyses. Transfection efficiency and cytotoxicity were measured using luciferase, MTT, and TUNEL assays. Intracellular delivery of curcumin was determined by fluorescence and absorbance. In the glioblastoma animal model, the effects of the intratumoral delivery of curcumin and the HSVtk gene were evaluated according to tumor size, immunohistochemistry, and TUNEL assays. RESULTS: R7L10-Cur delivered pDNA into the cells more efficiently than PLL and R7L10. In addition, R7L10-Cur delivered curcumin into the cells more efficiently than curcumin alone. The pHSVtk/R7L10-Cur complex induced cell death efficiently both in vitro and in vivo. Likewise, the combination of curcumin and the HSVtk gene using the pHSVtk/R7L10-Cur complex reduced tumor size more efficiently than the pHSVtk/PEI and pHSVtk/R7L10 complexes in a glioblastoma animal model. CONCLUSION: R7L10 is an efficient carrier for delivery of curcumin and the HSVtk gene, which may be a useful combination therapy for glioblastoma.

Phenotypic and genotypic characterization of acyclovir-resistant corneal HSV-1 isolates from immunocompetent patients with recurrent herpetic keratitis.

Herpes simplex virus type 1 (HSV-1) is a leading cause of corneal blindness. Acyclovir (ACV) constitutes the standard treatment of HSV infections including herpetic keratitis (HK). HSV resistance to ACV is mainly described in immunocompromised patients. We describe two cases of ACV-resistant corneal HSV-1 in immunocompetent individuals with recurrent HK.

The therapeutic effect of PEI-Mn0.5Zn0.5Fe2O4 nanoparticles/pEgr1-HSV-TK/GCV associated with radiation and magnet-induced heating on hepatoma.

Comprehensive therapy based on the integration of hyperthermia, radiation, gene therapy and chemotherapy is a promising area of study in cancer treatment. Using PEI-Mn(0.5)Zn(0.5)Fe(2)O(4) nanoparticles (PEI-MZF-NPs) as a gene transfer vector, the authors transfected self-prepared pEgr1-HSV-TK into HepG2 cells and measured the expression of the exogenous gene HSV-TK by RT-PCR. The results showed that HSV-TK was successfully transfected into HepG2 cells and the expression levels of HSV-TK remained stable. Besides, PEI-MZF-NPs were used as magnetic media for thermotherapy to treat hepatoma by magnet-induced heating, combined with radiation-gene therapy. Both in vitro and in vivo results suggest that this combined treatment with gene, radiation and heating has a better therapeutic effect than any of them alone. The apoptotic rate and necrotic rate of the combined treatment group was 51.84% and 15.45%, respectively. In contrast, it was only 20.55% and 6.80% in the radiation-gene group, 7.49% and 3.62% in the radiation-alone group, 15.23% and 7.90% in the heating-alone group, and only 3.52% and 2.16% in the blank control group. The inhibition rate of cell proliferation (88.5%) of the combined treatment group was significantly higher than that of the radiation-gene group (59.5%), radiation-alone group (37.6%) and heating-alone group (60.6%). The tumor volume and mass inhibition rate of the combined treatment group was 94.45% and 93.38%, respectively, significantly higher than 41.28% and 33.58% of the radiation-alone group, 60.76% and 52.18% of the radiation-gene group, 79.91% and 77.40% of the heating-alone group. It is therefore concluded that this combined application of heating, radiation and gene therapy has a good synergistic and complementary effect and PEI-MZF-NPs can act as a novel non-viral gene vector and magnetic induction medium, which offers a viable approach for the treatment of cancer.

In vitro-selected drug-resistant varicella-zoster virus mutants in the thymidine kinase and DNA polymerase genes yield novel phenotype-genotype associations and highlight differences between antiherpesvirus drugs.

Varicella zoster virus (VZV) is usually associated with mild to moderate illness in immunocompetent patients. However, older age and immune deficiency are the most important risk factors linked with virus reactivation and severe complications. Treatment of VZV infections is based on nucleoside analogues, such as acyclovir (ACV) and its valyl prodrug valacyclovir, penciclovir (PCV) as its prodrug famciclovir, and bromovinyldeoxyuridine (BVDU; brivudin) in some areas. The use of the pyrophosphate analogue foscarnet (PFA) is restricted to ACV-resistant (ACV(r)) VZV infections. Since antiviral drug resistance is an emerging problem, we attempt to describe the contributions of specific mutations in the viral thymidine kinase (TK) gene identified following selection with ACV, BVDU and its derivative BVaraU (sorivudine), and the bicyclic pyrimidine nucleoside analogues (BCNAs), a new class of potent and specific anti-VZV agents. The string of 6 Cs at nucleotides 493 to 498 of the VZV TK gene appeared to function as a hot spot for nucleotide insertions or deletions. Novel amino acid substitutions (G24R and T86A) in VZV TK were also linked to drug resistance. Six mutations were identified in the "palm domain" of VZV DNA polymerase in viruses selected for resistance to PFA, PCV, and the 2-phophonylmethoxyethyl (PME) purine derivatives. The investigation of the contributions of specific mutations in VZV TK or DNA polymerase to antiviral drug resistance and their impacts on the structures of the viral proteins indicated specific patterns of cross-resistance and highlighted important differences, not only between distinct classes of antivirals, but also between ACV and PCV.

Synthesis of conformationally North-locked pyrimidine nucleosides built on an oxabicyclo[3.1.0]hexane scaffold.

Beginning with a known 3-oxabicyclo[3.1.0]hexane scaffold (I), the relocation of the fused cyclopropane ring bond and the shifting of the oxygen atom to an alternative location engendered a new 2-oxabicyclo[3.1.0]hexane template (II) that mimics more closely the tetrahydrofuran ring of conventional nucleosides. The synthesis of this new class of locked nucleosides involved a novel approach that required the isocyanate II (B = NCO) with a hydroxyl-protected scaffold as a pivotal intermediate that was obtained in 11 steps from a known dihydrofuran precursor. The completion of the nucleobases was successfully achieved by quenching the isocyanate with the lithium salts of the corresponding acrylic amides that led to the uracil and thymidine precursors in a single step. Ring closure of these intermediates led to the target, locked nucleosides. The anti-HIV activity of 29 (uridine analogue), 31 (thymidine analogue), and 34 (cytidine analogue) was explored in human osteosarcoma (HOS) cells or modified HOS cells (HOS-313) expressing the herpes simplex virus 1 thymidine kinase (HSV-1 TK). Only the cytidine analogue showed moderate activity in HOS-313 cells, which means that the compounds are not good substrates for the cellular kinases.