[Effect of Nucleolin on Lymphoma Proliferation by Regulating Thymidine Kinase 1].

OBJECTIVE: To investigate the mechanism of nucleolin (NCL) involved in lymphoma proliferation by regulating thymidine kinase 1 (TK1). METHODS: Twenty-three patients with diffuse large B-cell lymphoma (DLBCL) were selected and divided into initial treatment group (14 cases) and relapsed/refractory group (9 cases). Serum TK1 and C23 protein in peripheral blood mononuclear cells were detected. Cell models of CA46-NCL-KD (CA46-NCL-knockdown) and CA46-NCL-KNC (CA46-NCL-knockdown negative control) were established by lentivirus vector mediated transfection in Burkitt lymphoma cell line CA46. The half maximal inhibitory concentration (IC50) of CA46-NCL-KD, CA46-NCL-KNC, and CA46 to adriamycin were detected by cell proliferation assay (MTS). The expression of NCL mRNA and protein in CA46-NCL-KD and CA46-NCL-KNC cells were dectected by Q-PCR and Western blot, respectively. The cell cycle of CA46-NCL-KD, CA46-NCL-KNC, and CA46 cells were detected by flow cytometry. The expression of TK1 protein in CA46-NCL-KD and CA46-NCL-KNC cells was detected by an enhanced chemiluminescence (ECL) dot blot assay. RESULTS: The level of serum TK1 in the initial treatment group was 0.43(0-30-1.01) pmol/L, which was lower than 10.56(2.19-14.99) pmol/L in the relapsed/refractory group (P<0-01), and the relative expression level of NCL protein in peripheral blood was also significantly lower. The IC50 of CA46-C23-KD cells to adriamycin was (0.147±0.02) µg/ml, which was significantly lower than (0.301±0.04) µg/ml of CA46-C23-KNC cells and (0.338±0.05) µg/ml of CA46 cells (P<0.05). Compared with CA46-NCL-KNC cells, the expression of NCL mRNA and protein, TK1 protein decreased in CA46-NCL-KD cells, and the proportion of S phase and G2/M phase also decreased, while G0/G1 phase increased in cell cycle. CONCLUSION: The increased expression of NCL in DLBCL and CA46 cells indicates low sensitivity to drug. NCL may participate in regulation of lymphoma proliferation by affecting TK1 expression, thereby affecting the drug sensitivity.

Molecular docking and dynamics supported investigation of antiviral activity of Lichen metabolites of Roccella montagnei: an in silico and in vitro study.

Lichens are symbiotic organisms that have been traditionally used for treating different kinds of ailments. As there are only a few reports on the antiviral activity of lichens, we thought of evaluating the anti-Herpes simplex virus-1 (HSV-1) activity of methanolic extract of Roccella montagnei and their isolated compounds. Fractionation of crude methanolic extract of Roccella montagnei by column chromatography isolated two pure compounds. Antiviral activity was assessed using a CPE inhibition assay at non-cytotoxic concentrations on Vero cells. Molecular docking and dynamics studies were carried out against Herpes simplex type-1 thymidine kinase to understand the binding interactions of the isolated compounds with reference to acyclovir. Isolated compounds were characterized as methyl orsellinate and montagnetol by spectral methods. Methanolic extract of Roccella montagnei exhibited an EC50 value of 56.51 µg/ml, while the compounds methyl orsellinate and montagnetol offered EC50 values of 13.50 µg/ml and 37.52 µg/ml, respectively, against HSV-1 viral infection on Vero cell lines. The selectively index (SI) of montagnetol (10.93) was found to be higher when compared to that of methyl orsellinate (5.55), indicating its better anti-HSV-1 activity. The docking and dynamics studies showed montagnetol was stable throughout the 100 ns, having better interactions and docking scores with HSV-1 thymidine kinase than methyl orsellinate, as well as the standard. To understand the mechanism of montagnetol's anti-HSV-1 activity, more research is required, and this could lead to the discovery of new and effective antiviral agents.Communicated by Ramaswamy H. Sarma.

Heterogeneity and viral replication fitness of HSV-1 clinical isolates with mutations in the thymidine kinase and DNA polymerase.

BACKGROUND: Prolonged antiviral therapy in immunocompromised individuals can result in the emergence of (multi)drug-resistant herpes simplex virus 1 (HSV-1) infections, forming a therapeutic challenge. OBJECTIVES: To evaluate spatial and temporal differences in drug resistance of HSV-1 samples from a HSCT recipient and to determine the effect of resistance mutations on viral replication fitness. PATIENTS AND METHODS: Five HSV-1 isolates were recovered from a HSCT recipient who suffered from persistent HSV-1 lesions, consecutively treated with aciclovir, foscarnet, cidofovir and a combination of ganciclovir and cidofovir. Spatial and temporal differences in HSV-1 drug resistance were evaluated genotypically [Sanger sequencing and next-generation sequencing (NGS) of the viral thymidine kinase (TK) and DNA polymerase (DP)] and phenotypically (plaque reduction assay). Viral replication fitness was determined by dual infection competition assays. RESULTS: Rapid evolution to aciclovir and foscarnet resistance was observed due to acquisition of TK (A189V and R222H) and DP (L778M and L802F) mutations. Virus isolates showed heterogeneous populations, spatial virus compartmentalization and minor viral variants in three out of five isolates (detectable by NGS but not by Sanger sequencing). Mutations in the TK and DP genes did not alter replication fitness without drug pressure. TK and/or DP mutants influenced replication fitness under antiviral pressure and showed increased fitness under pressure of the drug they showed resistance to. CONCLUSIONS: The use of NGS and dual infection competition assays revealed rapid evolution of HSV-1 drug resistance in a HSCT recipient with spatial and temporal compartmentalization of viral variants that had altered replication fitness under antiviral pressure.

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.

Step-by-Step Immune Activation for Suicide Gene Therapy Reinforcement.

Gene-directed enzyme prodrug gene therapy (GDEPT) theoretically represents a useful method to carry out chemotherapy for cancer with minimal side effects through the formation of a chemotherapeutic agent inside cancer cells. However, despite great efforts, promising preliminary results, and a long period of time (over 25 years) since the first mention of this method, GDEPT has not yet reached the clinic. There is a growing consensus that optimal cancer therapies should generate robust tumor-specific immune responses. The advent of checkpoint immunotherapy has yielded new highly promising avenues of study in cancer therapy. For such therapy, it seems reasonable to use combinations of different immunomodulators alongside traditional methods, such as chemotherapy and radiotherapy, as well as GDEPT. In this review, we focused on non-viral gene immunotherapy systems combining the intratumoral production of toxins diffused by GDEPT and immunomodulatory molecules. Special attention was paid to the applications and mechanisms of action of the granulocyte-macrophage colony-stimulating factor (GM-CSF), a cytokine that is widely used but shows contradictory effects. Another method to enhance the formation of stable immune responses in a tumor, the use of danger signals, is also discussed. The process of dying from GDEPT cancer cells initiates danger signaling by releasing damage-associated molecular patterns (DAMPs) that exert immature dendritic cells by increasing antigen uptake, maturation, and antigen presentation to cytotoxic T-lymphocytes. We hypothesized that the combined action of this danger signal and GM-CSF issued from the same dying cancer cell within a limited space would focus on a limited pool of immature dendritic cells, thus acting synergistically and enhancing their maturation and cytotoxic T-lymphocyte attraction potential. We also discuss the problem of enhancing the cancer specificity of the combined GDEPT-GM-CSF-danger signal system by means of artificial cancer specific promoters or a modified delivery system.

Iron Oxide Nanoparticles Promote Cx43-Overexpression of Mesenchymal Stem Cells for Efficient Suicide Gene Therapy during Glioma Treatment.

Background: Mesenchymal stem cells (MSCs) have been applied as a promising vehicle for tumour-targeted delivery of suicide genes in the herpes simplex virus thymidine kinase (HSV-tk)/ganciclovir (GCV) suicide gene therapy against malignant gliomas. The efficiency of this strategy is largely dependent on the bystander effect, which relies on high suicide gene expression levels and efficient transportation of activated GCV towards glioma cells. However, up to now, the methods to enhance the bystander effect of this strategy in an efficient and safe way are still lacking and new approaches to improve this therapeutic strategy are required. Methods: In this study, MSCs were gene transfected using magnetosome-like ferrimagnetic iron oxide nanochains (MFIONs) to highly express HSV-tk. Both the suicide and bystander effects of HSV-tk expressed MSCs (MSCs-tk) were quantitatively evaluated. Connexin 43 (Cx43) expression by MSCs and glioma cells was measured under different treatments. Intercellular communication between MSCs and C6 glioma cells was examined using a dye transfer assay. Glioma tropism and the bio-distribution of MSCs-tk were observed. Anti-tumour activity was investigated in the orthotopic glioma of rats after intravenous administration of MSCs-tk followed by intraperitoneal injection of GCV. Results: Gene transfection using MFIONs achieved sufficient expression of HSV-tk and triggered Cx43 overexpression in MSCs. These Cx43 overexpressing MSCs promoted gap junction intercellular communication (GJIC) between MSCs and glioma cells, resulting in significantly inhibited growth of glioma through an improved bystander effect. Outstanding tumour targeting and significantly prolonged survival with decreased tumour size were observed after the treatment using MFION-transfected MSCs in glioma model rats. Conclusion: Our results show that iron oxide nanoparticles have the potential to improve the suicide gene expression levels of transfected MSCs, while promoting the GJIC formation between MSCs and tumour cells, which enhances the sensitivity of glioma cells to HSV-tk/GCV suicide gene therapy.

ERK-dependent suicide gene therapy for selective targeting of RTK/RAS-driven cancers.

Suicide gene therapies provide a unique ability to target cancer cells selectively, often based on modification of viral tropism or transcriptional regulation of therapeutic gene expression. We designed a novel suicide gene therapy approach wherein the gene product (herpes simplex virus thymidine kinase or yeast cytosine deaminase) is phosphorylated and stabilized in expression by the extracellular signal-regulated kinase (ERK), which is overactive in numerous cancers with elevated expression or mutation of receptor tyrosine kinases or the GTPase RAS. In contrast to transcriptional strategies for selectivity, regulation of protein stability by ERK allows for high copy expression via constitutive viral promoters, while maintaining tumor selectivity in contexts of elevated ERK activity. Thus, our approach turns a signaling pathway often coopted by cancer cells for survival into a lethal disadvantage in the presence of a chimeric protein and prodrug, as highlighted by a series of in vitro and in vivo examples explored here.

Molecular imaging-monitored radiofrequency hyperthermia-enhanced intratumoral herpes simplex virus-thymidine kinase gene therapy for rat orthotopic ovarian cancer.

Objective: To establish the technique of intratumoral combination therapy of radiofrequency hyperthermia (RFH) with herpes simplex virus-thymidine kinase/ganciclovir (HSV-TK/GCV) gene therapy for rat ovarian cancers.Material and methods: This study consisted of three parts: (1) in vitro experiments to establish the 'proof of principal' that combination of RFH and HSV-TK gene therapy has the synergistic effect on human ovarian cancer cells; (2) creation of bioluminescence imaging-detectable rat ovarian cancer model; and (3) in vivo experiments using this rat model to validate the technical feasibility of the combination therapy. Cells and nude rats were divided into four groups: (i) combination therapy (HSV-TK/GCV + RFH); (ii) RFH; (iii) HSV-TK/GCV; and (iv) phosphate-buffered saline (PBS). Data were analyzed using Dunnett t-test or Kruskal-Wallis test.Results: Cell proliferation assay demonstrated significantly greater reduction in viable cells with the combination therapy [0.52 (0.43, 0.61)] compared to other treatments [RFH 0.90 (0.84, 0.96), HSV-TK/GCV 0.71 (0.53, 0.88), PBS 1 (1, 1); p < .05]. For 24 rat models with bioluminescence imaging-detectable orthotopic ovarian cancer (n = 6 per group), optical imaging demonstrated significantly decreased relative bioluminescence signal with the combination therapy [0.81 (0.52, 1.08)] compared to other treatments [RFH 3.60 (2.34, 4.86), HSV-TK/GCV 2.21 (1.71, 2.71), PBS 3.74 (3.19, 4.29); p < .001]. Ultrasound imaging demonstrated the smallest relative tumor volume with the combination therapy [0.78 (0.45, 1.11) versus 3.50 (2.67, 4.33), 2.10 (0.83, 3.37), 3.70 (1.79, 5.61); p < .05].Conclusion: The feasibility of intratumoral RFH-enhanced HSV-TK/GCV gene therapy was established on a unique rat model with molecular imaging-detectable orthotopic ovarian cancer.

Prognostic role of serum thymidine kinase 1 activity in patients with hormone receptor-positive metastatic breast cancer: Analysis of the randomised phase III Evaluation of Faslodex versus Exemestane Clinical Trial (EFECT).

BACKGROUND: Thymidine kinase 1 (TK1) plays a critical role in DNA synthesis and cell proliferation. Recent studies have shown potential for serum TK1 activity (sTKa) as a prognostic marker and indicator of early response to endocrine therapy in advanced breast cancer. The aim of this study is to assess the correlation between sTKa and patient outcome. PATIENTS AND METHODS: The Evaluation of Faslodex versus Exemestane Clinical Trial (EFECT) was a double-blind, double-dummy, randomised trial of fulvestrant versus exemestane after progression on non-steroidal aromatase inhibitor therapy, in postmenopausal women with advanced breast cancer. Retrospective analyses of serum archived from EFECT were conducted. sTKa was assessed using the DiviTum® assay on samples collected at baseline, after three and six months of endocrine therapy, and at disease progression. RESULTS: The median time to progression (mTTP) for patients with low baseline sTKa levels was 5.03 months (95% confidence interval [CI]: 3.91-5.89) versus 2.57 months (95% CI: 2.04-3.52) in patients with high sTKa baseline levels (P < 0.0001). On treatment, patients whose sTKa increased from baseline had a significantly shorter mTTP (3.39 months, 95% CI: 2.14-4.11) than those without an sTKa increase (5.39 months, 95% CI: 4.01-6.68) (P = 0.0045). Similar results were observed in the separate EFECT treatment arms. After adjusting for major prognostic factors, sTKa remained an independent marker. CONCLUSION: sTKa is a potential circulating prognostic marker in patients with advanced breast cancer treated with endocrine therapy. It may also represent a tool for upfront identification of endocrine therapy resistance and early positive response to therapy. Independent validation of these results is warranted.

HSV­TK/GCV can induce cytotoxicity of retinoblastoma cells through autophagy inhibition by activating MAPK/ERK.

Retinoblastoma is an severe ophthalmic disease and the most common type intraocular malignant tumor, particularly in infants. Currently, few drugs and therapies are available. Gene therapy has been considered to be a potential treatment to cure cancer effectively and Herpes simplex virus type 1 thymidine kinase/ganciclovir (HSV­TK/GCV) is one type of suicide gene therapy that has been extensively studied. Numerous in vitro and in vivo studied have shown that this system can kill tumor cells, including liver and lung cancer cells. GCV is used as an antiviral drug, and the thymidine kinase, HSV­TK can phosphorylate GCV to GCV­TP, a competitive inhibitor of DNA synthesis, instead of guanine­5'­triphosphate in the process of DNA synthesis. This process prevents DNA chain elongation causing cell death via apoptosis. However, the toxic effects of HSV­TK/GCV on retinoblastoma cells remain unknown, and the molecular mechanisms of its therapeutic effects have not been fully elucidated. Our results suggest that HSV­TK/GCV can significantly cause the death of retinoblastoma cell lines, HXO­RB44 and Y79. Further studies have reported that this cell death is induced by the inhibition of autophagy by activating the MAPK/ERK (mitogen­activated protein kinase/ERK) signaling pathway. The mTOR inhibitor Torin1 can partially block the toxic effects of HSV­TK/GCV on HXO­RB44 cells. The above results demonstrate that the mechanism undertaken by HSV­TK/GCV to exhibit therapeutic effects mechanism may inhibit autophagy by activating MAPK/ERK. The findings of the present study may provide novel insight for the exploration of HSV­TK/GCV in the treatment of retinoblastoma.

Stereoselective synthesis of 4'-selenonucleosides via seleno-Michael reaction as potent antiviral agents.

Based on the hypothesis that the bulky selenium atom, with 4p orbitals, can sterically hinder the approach of a cellular kinase to 5'-OH for phosphorylation, 4'-selenonucleosides with one-carbon homologation were designed and synthesized via a novel seleno-Michael reaction, with the stereoselectivity controlled by steric effects. 5'-Homo-4'-selenonucleosides (n = 2) demonstrated potent antiherpes simplex virus (HSV-1) activity, indicating that the bulky selenium atom might play a key role in preventing phosphorylation by cellular kinases, resulting in no antiviral activity.

SMAC-armed vaccinia virus induces both apoptosis and necroptosis and synergizes the efficiency of vinblastine in HCC.

Hepatocellular carcinoma (HCC) has particularly high incidence rate in Asia and its resistance to the chemotherapeutic drugs and cell death make it intractable. Vaccinia virus (VV) is a potential vehicle and has been widely used in cancer therapy. SMAC/DIABLO is a critical factor in activating caspases and eliminating inhibition of IAPs when the programmed cell death is promoted. In this study, we constructed a tumor-targeted vaccinia virus carrying SMAC/DIABLO gene that was knocked in the region of viral thymidine kinase gene (VV-SMAC). Our results showed that VV-SMAC efficiently infected and destroyed HCC cells via triggering both caspase-dependent apoptosis and necroptosis with depletion of IAPs. Furthermore, ripoptosome, a prerequisite complex of necroptosis, was assembled and induced by VV-SMAC. In addition, the combination of VV-SMAC and vinblastine represented a synergistic effect on HCC cells. In summary, our data suggest that VV-SMAC is a potential candidate and combination of VV-SMAC and vinblastine may provide a new avenue in treatment of HCC.

Tanshinone IIA increases the bystander effect of herpes simplex virus thymidine kinase/ganciclovir gene therapy via enhanced gap junctional intercellular communication.

The bystander effect is an intriguing phenomenon by which adjacent cells become sensitized to drug treatment during gene therapy with herpes simplex virus thymidine kinase/ganciclovir (HSV-tk/GCV). This effect is reported to be mediated by gap junctional intercellular communication (GJIC), and therefore, we postulated that upregulation of genes that facilitate GJIC may enhance the HSV-tk/GCV bystander effect. Previous findings have shown Tanshinone IIA (Tan IIA), a chemical substance derived from a Chinese medicine herb, promotes the upregulation of the connexins Cx26 and Cx43 in B16 cells. Because gap junctions are formed by connexins, we hypothesized that Tan IIA might increase GJIC. Our results show that Tan IIA increased GJIC in B16 melanoma cells, leading to more efficient GCV-induced bystander killing in cells stably expressing HSV-tk. Additionally, in vivo experiments demonstrated that tumors in mice with 10% HSV-tk positive B16 cells and 90% wild-type B16 cells became smaller following treatment with the combination of GCV and Tan IIA as compared to GCV or Tan IIA alone. These data demonstrate that Tan IIA can augment the bystander effect of HSV-tk/GCV system through increased gap junction coupling, which adds strength to the promising strategy that develops connexins inducer to potentiate the effects of suicide gene therapy.

Expression of herpes simplex virus type 1 recombinant thymidine kinase and its application to a rapid antiviral sensitivity assay.

Antiviral-resistant herpesvirus infection has become a great concern for immunocompromised patients. Herpes simplex virus type 1 (HSV-1) infections are treated with viral thymidine kinase (vTK)-associated drugs such as acyclovir (ACV), and most ACV-resistance (ACV(r)) is due to mutations in the vTK. The standard drug sensitivity test is usually carried out by the plaque reduction assay-based method, which requires over 10 days. To shorten the time required, a novel system was developed by the concept, in which 293T cells transiently expressing recombinant vTK derived from the test sample by transfection of the cells with an expression vector were infected with vTK-deficient and ACV(r) HSV-1 (TAR), and then cultured in a maintenance medium with or without designated concentrations of ACV, ganciclovir (GCV) and brivudine (BVdU). The replication of TAR was strongly inhibited by ACV, GCV and BVdU in 293T cells expressing recombinant vTK of the ACV-sensitive HSV-1, whereas replication was not or slightly inhibited in cells expressing the recombinant vTK of highly resistant or intermediately resistant HSV-1, respectively. An inverse correlation was demonstrated in the 50% effective concentrations (EC(50)s) and inhibitory effects of these compounds on the replication of TAR among ACV(s) and ACV(r) HSV-1 clones. These results indicate that the EC(50)s of the vTK-associated drugs including ACV can be assumed by measuring the inhibitory effect of drugs in 293T cells expressing recombinant vTK of the target virus. The newly developed antiviral sensitivity assay system for HSV-1 makes it possible to estimate EC(50) for vTK-associated drugs, when whole vTK gene is available for use by gene amplification directly from lesion's samples or from virus isolates.

Selective suicide gene therapy of colon cancer exploiting the urokinase plasminogen activator receptor promoter.

Colon cancer is the third and fourth most prevalent cancer among Iranian men and women, respectively. Suicide gene therapy is one of the alternative therapeutic modalities for cancer. The application of specific promoters for therapeutic genes should decrease the adverse effects of this modality. The combined aims of this study were to design a specific suicide gene therapy construct for colon cancer and study its effect in distinct representatives of transformed and nontransformed cells. The KRAS oncogene signaling pathway is one of the most important signaling pathways activated in colon cancer; therefore, we inserted the urokinase plasminogen activator receptor (uPAR; PLAUR gene) promoter as one of the upregulated promoters by this pathway upstream of a suicide gene (thymidine kinase [TK]) and a reporter gene (beta-galactosidase, beta-gal [LacZ]). This promoter is a natural combination of different motifs responsive to the RAS signaling pathway, such as the transcription factors AP1 (FOS/JUN), SP1, SP3, and AP2alpha, and nuclear factor kappa B (NFkappaB). The reporter plasmid under the control of the uPAR promoter (PUCUPARLacZ) had the ability to express beta-gal in colon cancer cells (human colon adenocarcinoma [SW480] and human colorectal carcinoma [HCT116] cell lines), while it could not express beta-gal in nontransformed human umbilical vein endothelial cells (HUVEC) and normal colon cells. After confirming the ability of pUCUPARTK (suicide plasmid) to express TK in SW480 and HCT116 cells by real-time PCR, cytotoxicity assays showed that pUCUPARTK decreased the viability of these cells in the presence of ganciclovir 20 and 40 microg/mL (and higher), respectively. Although M30 CytoDEATH antibody could not detect a significant rate of apoptosis induced by ganciclovir in pUCUPARTK-transfected HCT116 cells, the percentage of stained cells was marked in comparison with untreated cells. While this antibody could detect apoptosis in HCT116 cell line transfected with positive control plasmid, it could not detect apoptosis in SW480 cells transfected with the same positive control. This discrepancy could be attributed to the different mechanisms of TK/ganciclovir-induced apoptosis in tumor protein p53 (TP53)-expressing (HCT116) and -deficient (SW480) cells. Annexin-propidium iodide staining could detect apoptosis in treated, pUCUPARTK-transfected SW480 and HCT116 cells. This study showed that the uPAR promoter can be considered as a suitable candidate for specific suicide gene therapy of colon cancer and probably other cancers in which the RAS signaling pathway is involved in their carcinogenesis process.

T cells' immunological synapses induce polarization of brain astrocytes in vivo and in vitro: a novel astrocyte response mechanism to cellular injury.

BACKGROUND: Astrocytes usually respond to trauma, stroke, or neurodegeneration by undergoing cellular hypertrophy, yet, their response to a specific immune attack by T cells is poorly understood. Effector T cells establish specific contacts with target cells, known as immunological synapses, during clearance of virally infected cells from the brain. Immunological synapses mediate intercellular communication between T cells and target cells, both in vitro and in vivo. How target virally infected astrocytes respond to the formation of immunological synapses established by effector T cells is unknown. FINDINGS: Herein we demonstrate that, as a consequence of T cell attack, infected astrocytes undergo dramatic morphological changes. From normally multipolar cells, they become unipolar, extending a major protrusion towards the immunological synapse formed by the effector T cells, and withdrawing most of their finer processes. Thus, target astrocytes become polarized towards the contacting T cells. The MTOC, the organizer of cell polarity, is localized to the base of the protrusion, and Golgi stacks are distributed throughout the protrusion, reaching distally towards the immunological synapse. Thus, rather than causing astrocyte hypertrophy, antiviral T cells cause a major structural reorganization of target virally infected astrocytes. CONCLUSIONS: Astrocyte polarization, as opposed to hypertrophy, in response to T cell attack may be due to T cells providing a very focused attack, and thus, astrocytes responding in a polarized manner. A similar polarization of Golgi stacks towards contacting T cells was also detected using an in vitro allogeneic model. Thus, different T cells are able to induce polarization of target astrocytes. Polarization of target astrocytes in response to immunological synapses may play an important role in regulating the outcome of the response of astrocytes to attacking effector T cells, whether during antiviral (e.g. infected during HIV, HTLV-1, HSV-1 or LCMV infection), anti-transplant, autoimmune, or anti-tumor immune responses in vivo and in vitro.

Gene therapy: the first approved gene-based medicines, molecular mechanisms and clinical indications.

As gene therapy has matured from clinical trials to the first commercial products, understanding of the mechanisms of gene delivery has increased tremendously. This has also been reflected in viral vector development, creating a number of new approaches to tackle issues in transduction efficiency, biodistribution and viral safety. This review will highlight the most important issues and advancements in vector development, administration, surface modification, integration to host genome and safety. The gene therapy products currently available or near market approval, based on p53 expression (Gendicine and Advexin), conditionally replicative adenoviruses (Oncorine) and thymidine kinase + ganciclovir therapy (Cerepro), are introduced with emphasis on the molecular mechanisms of action.

[The effect of lentivirus-mediated suicide gene therapy on lens epithelial cells].

OBJECTIVE: To investigate the cytotoxicity of lentivirus-mediated herpes simplex virus thymidine kinase/ganciclovir (HSV-TK/GCV) suicide gene therapy on human lens epithelial cell line and analyze the mechanism of cell death. METHODS: a lentiviral containing the Lenti-HSVtk-EGFP as therapeutic vector and Lenti-EGFP as the control were used in the study. Transfection efficiency in vitro was assessed by fluorescence-activated cell sorting. Expression of HSV-tk in lens epithelial cells (LECs) mediated by lentivirus was examined by fluorescence microscope, genomic PCR and reverse transcription PCR. The cytotoxicity of HSV-TK/GCV suicide-gene system was assessed using DNA ladder and electron microscope. The time dependent transfection efficiency and bystander effect induced by the HSV-TK/GCV in LECs were evaluated. RESULT: the transduction efficiency was higher than 95%. When concentration of GCV was 15-25 microg/ml, apoptosis or necrosis was induced by Lenti-HSVtk-EGFP in HLE. The cytotoxicity was enhanced with increased time of transfection and concentration of GCV. Non transfected cells were also effectively killed by mixing the cell with GCV transfected cells (Bystander effect). CONCLUSION: GCV can effectively kill the LECs with the expressing of HSV-tk. Bicistronic lentiviral vectors can efficiently integrate multiple genes into LECs, therefore, it is a reliable vector for gene therapy; lentivirus mediated HSV-tk/GCV suicide gene therapy may provide an effective approach for the treatment of posterior capsule opacification.

[Lethal effect of adenovirus-mediated HSV-TK gene in combination with hydroxycamptothecin on human bladder cancer in vitro].

OBJECTIVE: To evaluate the lethal effect of adenovirus-mediated HSV-TK-ganciclovir (GCV) gene therapy in combination with hydroxycamptothecin (HCPT) on hunman bladder carcinoma cell line T-24 cells. METHODS: Human bladder carcinoma cell line T-24 was transfected with adenovirus expression vector containing TK gene and green fluorescent protein (GFP) gene, and the transfection efficiency was observed and TK expression detected by PCR. After successful cell transfection indicated by GFP expression, GCV and hydroxycamptothecin are respectively added into the cell culture with normal T-24 cells serving as the blank control group. The growth inhibition rate of hunman bladder carcinoma cells in response to HCPT treatment for 72 h and the cell survival rate of 24 h, 48 h and 72 h after transfection with different protocols were observed by MTT assay. The apoptosis of the cells treated with GCV (0.5 mg/ml)+HCPT (10 mg/L) for 4 h was observed by flow cytometry. RESULTS: The cell inhibition rate increased gradually with increment of HCPT concentration, from 14% at HCPT concentration of 0.01 mg/L to 60% at 50 mg/L, but for a concentration above 100 mg/L, the inhibition rate did not exhibit further increase (P=0.216). GCV alone and GCV in combination with HCPT both resulted in significantly decreased survival rate of human bladder carcinoma cells (P=0.00), and the killing efficiency of the cells by GCV+HCPT protocol increased obviously with increment of HCPT concentration and prolongation of the action time. The cells treated with 0.5 mg/ml GCV alone for 72 h retained a cell survival rate of 34.6%, which was lowered to only 8.07% with combined treatment with GCV (0.5mg/ml) and HCPT (10 mg/L). Typical apoptotic peak before M1 phase of the cells appeared 4 h after treatment with GCV+10 mg/ml HCPT, which resulted in a apoptosis rate of 52.93%. CONCLUSION: HSV-TK/GCV in combination with HCPT can enhance the lethal effect of suicide gene therapy against human bladder carcinoma cells and effectively induce apoptosis of the cells.

[Toxic effects of CD-TK double suicidal gene system against prostate carcinoma cells].

OBJECTIVE: To evaluate the toxic effects of the CD-TK fusion gene systems against prostate carcinoma cell line RM-1 for assessing the value of suicidal gene therapy for prostate carcinoma. METHODS: CD-TK fusion gene and green fluorescent protein (GFP) gene were transfected into RM-1 cells through adenovirus vectors. RT-PCR was used to demonstrate successful transfection and transcription of the suicidal genes. The toxic effects of 5-FC and GCV used alone or in combination on the transfected cells were observed by MTT assay, with the non-transfected RM-1 cells serving as control. RESULTS: Cytotoxic activity of CD/5-FC and TK/GCV systems against RM-1 cells was observed, and combined treatment with the two drugs resulted in significantly lowered survival of CD-TK-expressing cells (P<0.05). After exposure to 5-FC and GCV for 72 h, the survival rate of the transfected cells decreased to 71.56% and 47.27%, respectively, and their combined use resulted in a survival rate as low as 18.46%. CONCLUSION: CD-TK fusion double suicidal gene system can produce significantly stronger toxic effect against RM-1 cells in vitro than either of suicidal genes.