Project description:The objective of this research was to evaluate the efficacy of a recombinant nonviral vector for targeted delivery of a thymidine kinase (TK) suicide gene to xenograft SKOV-3 tumors. The vector was genetically engineered and used to condense the TK gene into particles of less than 100 nm. The nanoparticles were used to transfect and kill SKOV-3 cancer cells in combination with ganciclovir (GCV) in vitro. The results demonstrated that the vector could effectively kill up to 80% of the SKOV-3 cancer cells. In the next step, the ability of the vector to deliver the TK suicide gene to xenograft tumors of SKOV-3 was studied. The results demonstrated that the vector could transfect tumors and result in significant tumor size reduction during the period that GCV was administered. Administration of GCV for at least 3 weeks post transfection was of paramount importance. These results illustrate the therapeutic efficacy and application of a designed recombinant nonviral vector in cancer gene therapy.A recombinant nonviral vector is used to deliver a suicide thymidine kinase gene under gancylovir control in vitro to SKOV-3 cancer cells with 70% efficiency. Follow on testing in a xenograft tumor demonstrated tumor reduction persisting for three weeks.
Project description:Lung cancer is one of the most common cancers, and the number of patients with intracranial metastases is increasing. Previously, we developed an enzyme prodrug suicide gene therapy based on the herpes simplex virus thymidine kinase (HSV-TK)/ganciclovir (GCV) system using various mesenchymal stem cells to induce apoptosis in malignant gliomas through bystander killing effects. Here, we describe stem cells from human exfoliated deciduous teeth (SHED) as gene vehicles of the TK/GCV system against a brain metastasis model of non-small cell lung cancer (NSCLC). We introduced the A168H mutant TK (TKA168H) into SHED to establish the therapeutic cells because of the latent toxicity of wild type. SHED expressing TKA168H (SHED-TK) exhibited chemotaxis to the conditioned medium of NSCLC and migrated toward implanted NSCLC in vivo. SHED-TK demonstrated a strong bystander effect in vitro and in vivo and completely eradicated H1299 NSCLC in the brain. SHED-TK cells implanted intratumorally followed by GCV administration significantly suppressed the growth of H1299 and improved survival time. These results indicate that the TKA168H variant is suitable for establishing therapeutic cells and that intratumoral injection of SHED-TK followed by GCV administration may be a useful strategy for therapeutic approaches.
Project description:Ovarian cancer (OC) is most often contained within the peritoneal cavity, making it an ideal disease for adenoviral-delivered gene therapies. In effort to develop a safe and effective gene therapy for OC, we created a replication deficient adenovirus bearing the herpes simplex thymidine kinase (HSV-tk) gene under direction of the tumor specific promoter human epididymis protein 4 (HE4). The purpose of this study was to investigate the ability of our adenoviral construct to transduce OC cells in vitro and mediate transgene expression of HSV-tk, thereby sensitizing OC to the pro-drug ganciclovir. Cisplatin-sensitive (CS) and -resistant (CR) A2780 OC cells, infected with virus for 6 hours at 100, 500, and 1000 multiplicity of infection followed by ganciclovir treatment every other day for 5 days, were assayed for cell viability. Adenoviral-mediated transgene expression increased with increasing amounts of virus and peaked at 48 hours after transduction in both A2780-CS and -CR. Unexpectedly, ganciclovir alone was slightly toxic to both A2780 cell lines (IC50 of 234.9 μg/mL and 257.2 μg/mL in A2780-CS and -CR, respectively). Transduction with ADV-HE4-HSV-tk followed by ganciclovir treatment increased (P<0.05) cell killing up to ten-fold, lowering the IC50 to 23.9 μg/mL and 32.6 μg/mL in A2780-CS and -CR, respectively, at 1000 multiplicity of infection. The results support the potential use of this approach as a gene therapy for OC, a disease that accounts for more deaths than any other cancer of the female reproductive system.
Project description:Ovarian cancer is the leading cause of death from all gynecological cancers and conventional therapies such as surgery, chemotherapy, and radiotherapy usually fail to control advanced stages of the disease. Thus, there is an urgent need for alternative and innovative therapeutic options. We reason that cancer gene therapy using a vector capable of specifically delivering an enzyme-encoding gene to ovarian cancer cells will allow the cancer cell to metabolize a harmless prodrug into a potent cytotoxin, which will lead to therapeutic effects. In the current study, we explore the use of a human papillomavirus (HPV) pseudovirion to deliver a herpes simplex virus thymidine kinase (HSV-tk) gene to ovarian tumor cells. We found that the HPV-16 pseudovirion was able to preferentially infect murine and human ovarian tumor cells when administered intraperitoneally. Furthermore, intraperitoneal injection of HPV-16 pseudovirions carrying the HSV-tk gene followed by treatment with ganciclovir led to significant therapeutic anti-tumor effects in murine ovarian cancer-bearing mice. Our data suggest that HPV pseudovirion may serve as a potential delivery vehicle for ovarian cancer gene therapy.
Project description:Suicide gene therapy is a promising strategy against melanoma. However, the low efficiency of the gene transfer technique can limit its application. Our preliminary data showed that dioscin, a glucoside saponin, could upregulate the expression of connexins Cx26 and Cx43, major components of gap junctions, in melanoma cells. We hypothesized that dioscin may increase the bystander effect of herpes simplex virus thymidine kinase/ganciclovir (HSV-tk/GCV) through increasing the formation of gap junctions. Further analysis showed that dioscin indeed could increase the gap junctional intercellular communication in B16 melanoma cells, resulting in more efficient GCV-induced bystander killing in B16tk cells. By contrast, overexpression of dominant negative Cx43 impaired the cell-cell communication of B16 cells and subsequently weakened the bystander effect of HSV-tk/GCV gene therapy. In vivo, combination treatment with dioscin and GCV of tumor-bearing mice with 30% positive B16tk cells and 70% wild-type B16 cells caused a significant reduction in tumor volume and weight compared to treatment with GCV or dioscin alone. Taken together, these results demonstrated that dioscin could augment the bystander effect of the HSV-tk/GCV system through increasing connexin-mediated gap junction coupling.
Project description:Combination targeted therapy is a promising cancer therapeutic strategy. Here, using PEI-Mn0.5Zn0.5Fe2O4 nanoparticles (PEI-MZF-NPs) as magnetic media for MFH (magnetic fluid hyperthermia) and gene transfer vector for gene-therapy, a combined therapy, pHRE-Egr1-HSV-TK/(131)I-antiAFPMcAb-GCV/MFH, for hepatoma is developed. AntiAFPMcAb (Monoclonal antibody AFP) is exploited for targeting. The plasmids pHRE-Egr1-HSV-TK are achieved by incorporation of pEgr1-HSV-TK and pHRE-Egr1-EGFP. Restriction enzyme digestion and PCR confirm the recombinant plasmids pHRE-Egr1-HSV-TK are successfully constructed. After exposure to the magnetic field, PEI-MZF-NPs/pHRE-Egr1-EGFP fluid is warmed rapidly and then the temperature is maintained at 43?°C or so, which is quite appropriate for cancer treatment. The gene expression reaches the peak when treated with 200??Ci (131)I for 24?hours, indicating that the dose of 200??Ci might be the optimal dose for irradiation and 24?h irradiation later is the best time to initiate MFH. The in vitro and in vivo experiments demonstrate that pHRE-Egr1-HSV-TK/(131)I-antiAFPMcAb-GCV/MFH can greatly suppress hepatic tumor cell proliferation and induce cell apoptosis and necrosis and effectively inhibit the tumor growth, much better than any monotherapy does alone. Furthermore, the combination therapy has few or no adverse effects. It might be applicable as a strategy to treat hepatic cancer.
Project description:Nucleoside analogues, such as penciclovir, ganciclovir, acyclovir, and their fluoro-substituted derivatives, have wide utility as antivirals. Among these analogues, FHBG ((18)F-Fluorohydroxybutylguanine) is a well-validated PET (positron emission tomography) probe for monitoring reporter gene expression. To evaluate whether or not imposing rigidity into the flexible side chain of FHBG 4 could also impact its interaction, with amino acid residues within the binding site of HSV1-TK (Herpes Simplex Virus-1 Thymidine Kinase), thus influencing its cytotoxic activity. Herein, the synthesis of a new fluorinated nucleoside analogue 6 (conceived via ligand-docking studies) is reported. Agent 6 demonstrates selective activity against HeLa cells stably transfected with mutant HSV1-sr39TK and is also 47-fold more potent than FHBG.
Project description:In gene therapy, effective and selective suicide gene expression is crucial. We exploited the endogenous Long INterspersed Element-1 (L1) machinery often reactivated in human cancers to integrate the Herpes Simplex Virus Thymidine Kinase (HSV-TK) suicide gene selectively into the genome of cancer cells. We developed a plasmid-based system directing HSV-TK expression only when reverse transcribed and integrated in the host genome via the endogenous L1 ORF1/2 proteins and an Alu element. Delivery of these new constructs into cells followed by Ganciclovir (GCV) treatment selectively induced mortality of L1 ORF1/2 protein expressing cancer cells, but had no effect on primary cells that do not express L1 ORF1/2. This novel strategy for selective targeting of tumour cells provides high tolerability as the HSV-TK gene cannot be expressed without reverse transcription and integration, and high selectivity as these processes take place only in cancer cells expressing high levels of functional L1 ORF1/2.