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Biomedical subjects

N S Yang

Publications and source records attributed to N S Yang.

60 records · Page 4Linked to original sources
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Preclinical development of human granulocyte-macrophage colony-stimulating factor-transfected melanoma cell vaccine using established canine cell lines and normal dogs.

Tumor vaccines and gene therapy have received significant attention as means of increasing cellular and humoral immune responses to cancer. We conducted a pilot study of seven research dogs to determine whether intradermal injection of canine tumor cells transfected via the Accell particle-mediated gene transfer device with the cDNA for human granulocyte-macrophage colony-stimulating factor (hGM-CSF) would generate biologically relevant levels of protein and result in demonstrable histological changes at sites of vaccination. Tumor cell vaccines of 10(7) irradiated canine melanoma cells were nontoxic, safe, and well tolerated. No significant alterations in blood chemistry values or hematological profiles were detected. A histological review of control vaccine sites revealed inflammatory responses predominated by eosinophils, whereas vaccine sites with hGM-CSF-transfected tumor cells had an influx of neutrophils and macrophages. Enzyme-linked immunosorbent assays of skin biopsies from vaccine sites had local hGM-CSF production (8.68-16.82 ng/site of injection) at 24 hours after injection and detectable levels (0.014-0.081 ng/site) for < or =2 weeks following vaccination. Flow cytometric analysis of hGM-CSF-transfected cells demonstrated < or =25% transfection efficiency, and hGM-CSF levels obtained during time-course assays demonstrated biologically relevant levels for both irradiated and nonirradiated samples. These data demonstrate the in vivo biological activity of irradiated hGM-CSF-transfected canine tumor cells and help provide evidence for a valid translational research model of spontaneous tumors.

Animals↗
PubMedDate not supplied

Interleukin-12 cDNA skin transfection potentiates human papillomavirus E6 DNA vaccine-induced antitumor immune response.

Human papillomaviruses are associated with >90% of all cases of uterine cervical tumors. The E6 and E7 oncoproteins of human papillomavirus are potentially ideal targets of immune therapy for cervical cancer, because their expression is necessary for cellular transformation. Although both E6 and E7 proteins contain numerous predicted cytotoxic T lymphocyte (CTL) epitopes that are capable of binding to human leukocyte antigens, the majority of earlier in vivo tumor rejection studies have focused on E7. We show here that gene gun-mediated skin transfection of plasmid vector encoding the nontransforming, amino-terminal half of E6 resulted in the induction of E6-specific CTL activity and tumor rejection in a murine model. The use of recombinant murine interleukin-12 (rmIL-12) as a vaccine adjuvant has been shown to result in both an enhancement and suppression of immune responses, depending upon the doses of rmIL-12 and the experimental systems used. We demonstrate here that local expression of transgenic mIL-12 at the E6 DNA vaccination site potentiated E6-specific CTL responses and increased vaccine-induced antitumor therapeutic efficacy. Our results indicate that transfection of the mIL-12 gene at the vaccination site may represent an attractive adjuvant for cancer gene immunotherapy.

Animals↗
PubMedDate not supplied

In vivo particle-mediated cytokine gene transfer into canine oral mucosa and epidermis.

Cytokines can stimulate immune effector cells present within the oral mucosa and epidermis to respond to vaccination or to combat cancer. However, intravenous cytokine delivery is often inefficient and frequently accompanied by systemic toxicity. The goal of this study was to evaluate dogs as a large animal model for gene therapy of cancer because they develop spontaneous oral and epidermal tumors. In this report, we demonstrate that particle-mediated gene transfer of beta-galactosidase, luciferase, interleukin-2, interleukin-6, and granulocyte-macrophage colony stimulating factor (GM-CSF) complementary DNA (cDNA) into the oral mucosa and epidermis of healthy dogs resulted in effective, localized, transgenic protein expression. Additionally, the epidermal sites transfected with GM-CSF developed a profound inflammatory reaction characterized by neutrophilic infiltration. Clinical pathology analyses were unremarkable. These results demonstrate that in vivo particle-mediated gene transfer of canine oral mucosa and epidermis with cytokine cDNA can result in production of biologically active transgenic cytokines with minimal toxicity. These findings have applications to cancer immunotherapy using a gene gun approach.

Animals↗
PubMedDate not supplied

Immune responsiveness to a murine mammary carcinoma modified to express B7-1, interleukin-12, or GM-CSF.

This report characterizes the immunological host response to a syngeneic murine mammary carcinoma along with variants genetically modified to express B7-1 or secrete GM-CSF and interleukin-12 (IL-12). MT-901 is a subline of a mammary adenocarcinoma that was chemically induced in the Balb/c host. It was found to be weakly immunogenic by immunization/ challenge experiments, and it induced tumor-specific T-cell responses in lymph nodes (LN) draining progressive subcutaneous tumors. Tumor clones expressing B7-1 or secreting GM-CSF exhibited reduced tumorigenicity without completely abrogating tumor growth, whereas IL-12 elaboration lead to complete tumor growth inhibition. In vivo subcutaneous inoculation of a transgenic cell clone secreting GM-CSF (240 ng/10(6) cells/24 hours) resulted in significantly enhanced T-cell reactivity of tumor-draining lymph node (TDLN) cells as compared to wild-type TDLN cells. This finding was obtained from observations assessed by several different methods, including: 1) in vitro cytotoxicity, 2) in vitro interferon-gamma release, and 3) adoptive transfer in mice with established tumor. Moreover, the transfer of activated LN cells derived from mice inoculated with GM-CSF-secreting tumor cells resulted in the prolonged survival of animals with macroscopic metastatic disease, which was not evident utilizing LN cells from mice inoculated with wild-type tumor. By contrast, clones that expressed B7-1 or IL-12 (4 ng/10(6) cells/24 hours) did not elicit enhanced tumor-reactive TDLN cells compared with wild-type tumor when assessed in the adoptive transfer model. The autocrine secretion of GM-CSF by transduced tumor cells was found to serve as an effective immune adjuvant in the host response to this weakly immunogenic tumor.

Adenocarcinoma↗