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At least 37 records · Page 2Linked to original sources
PubMed1998

Reduced tumorigenicity of human gastric carcinoma cells engineered to produce IL-2 in SCID mice reconstituted with peripheral blood cells from cancer patients.

We have examined the validity of a humanized immune system with an animal model to assess cytokine gene therapy for cancer patients. For that purpose, we prepared hematologically-reconstituted severe combined immunodeficiency mice by transferring patient's peripheral blood cells containing CD34+ cells. These animals were inoculated subcutaneously with human gastric cancer lines transduced with cytokine genes. Tumorigenicity of interleukin-2-producing cells was significantly reduced in reconstituted but not in non-reconstituted mice, whereas that of wild-type and interleukin-6 producer cells was not affected irrespective of the reconstitution status. An inability to induce protective immunity in the reconstituted mice, which had rejected interleukin-2-producers, suggested that the effector cells mediating the antitumor response were non-T cells of donor origin. The experimental system presented in this study seems to be a feasible model to investigate applicable cytokines for patients.

Adult↗
PubMed1996

Tumor cells engineered to express major histocompatibility complex class II molecules induce T helper cell-dependent responses that protect mice from normally lethal doses of unmodified tumor cells.

Tumor cells typically fail to stimulate protective immune response in the autochthonous host. This does not appear to be the result of either inadequate antigenicity or failure to express a normal complement of major histocompatibility complex (MHC) class 1 molecules. To investigate if tumor cells fail to stimulate protective immunity because they fail to activate adequate numbers of T helper cells, we transfected murine fibrosarcoma and melanoma cells with genes encoding syngeneic and allogeneic MHC class II molecules. Fibrosarcoma cells expressing either type of MHC class II molecules failed to induce tumors in syngeneic mice and stimulated T helper cell-dependent antitumor immune responses that protected mice from subsequent challenge with untransfected tumor cells. The antitumor response involved both CD4+ and CD8+ T cells, and appeared to be dependent on at least low levels of innate tumor cell immunogenicity.

Animals↗
PubMed1991

Treatment of established renal cancer by tumor cells engineered to secrete interleukin-4.

The generation of antigen-specific antitumor immunity is the ultimate goal in cancer immunotherapy. When cells from a spontaneously arising murine renal cell tumor were engineered to secrete large doses of interleukin-4 (IL-4) locally, they were rejected in a predominantly T cell-independent manner. However, animals that rejected the IL-4-transfected tumors developed T cell-dependent systemic immunity to the parental tumor. This systemic immunity was tumor-specific and primarily mediated by CD8+ T cells. Established parental tumors could be cured by the systemic immune response generated by injection of the genetically engineered tumors. These results provide a rationale for the use of lymphokine gene-transfected tumor cells as a modality for cancer therapy.

Animals↗
PubMedDate not supplied

In vitro and in vivo characteristics of human squamous cell carcinoma of the head and neck cells engineered to secrete interleukin-2.

Two human squamous cell carcinoma of the head and neck (SCCHN) cell lines, PCI-13 and PCI-52, were transduced with the retroviral construct containing human interleukin-2 (IL-2) cDNA and selected for neomycin resistance in G418 medium. Stably transduced SCCHN cells produced and secreted IL-2, which was shown to have biologic activity in a bioassay, using an IL-2-dependent CTLL-2 cell line. By immunohistochemistry, IL-2 gene-transduced PCI-13 cells were strongly positive for IL-2, and by flow cytometry showed both cell surface and intracytoplasmic expression of IL-2 protein. Expression of IL-2 mRNA was measured by quantitative RT-PCR and found to be considerably increased in transduced SCCHN relative to that in parental cells. There was no difference in expression of IL-2R between the parental and IL-2 gene-transduced cells. In vitro proliferation of IL-2 gene-transduced tumor cells was consistently more rapid than that of parental cells. Sensitivity of the parental and IL-2 gene-transduced targets to lysis or apoptosis mediated by purified human natural killer (NK) cells or IL-2-activated NK (A-NK) cells was comparable as measured in 4-hour 51Cr-release and 1-hour [3H]thymidine-release assays, respectively. However, transduced cells were significantly more sensitive than parental cells to these effectors in 24-hour MTT assays, most likely due to IL-2 production by the transduced targets. PCI-52 cells selected for in vivo experiments formed large subcutaneous tumors in immunosuppressed nude mice. Tumors established by subcutaneous injections of 1 x 10(7) IL-2 gene-transduced cells regressed completely by day 25, while those formed by parental or LacZ gene-transduced tumor cells grew progressively. Tumor regression was mediated by numerous mononuclear cells, identified as murine NK cells and macrophages by immunohistochemistry, which accumulated around the IL-2-secreting, but not parental, tumors within 5-6 days after tumor cell injections. Thus, IL-2 gene-transduced SCCHN cells produce functional IL-2 in vivo in amounts sufficient to support the recruitment to the tumor site and antitumor activity of cytotoxic effector cells. IL-2-secreting SCCHN cells may be a useful component of vaccines designed to induce and sustain effector cell activation at the tumor site.

Animals↗
PubMedDate not supplied

[Electrostimulated cell fusion in cell engineering].

A survey of studies on reconstructions of animal and plant cells which apply a new physical method--electrostimulated fusion, is presented. Effects of different factors of the medium on the efficiency of electrofusion is discussed. A detailed account is given of the authors' studies on zygotes reconstruction by combined methods of microsurgery and electrostimulated cell fusion. Advantages of the latter as compared to the widely distributed methods of fusion by polyethylenglycol and Sendai virus are considered. This physical method can play an important role in the progress of cellular engineering.

Animals↗
PubMed1997

Neurite differentiation is modulated in neuroblastoma cells engineered for altered acetylcholinesterase expression.

Previous observations from several groups suggest that acetylcholinesterase (AChE) may have a role in neural morphogenesis, but not solely by virtue of its ability to hydrolyze acetylcholine. We tested the possibility that AChE influences neurite outgrowth in nonenzymatic ways. With this aim, antisense oligonucleotides were used to decrease AChE levels transiently, and N1E.115 cell lines were engineered for permanently altered AChE protein expression. Cells stably transfected with a sense AChE cDNA construct increased their AChE expression 2.5-fold over the wild type and displayed significantly increased neurite outgrowth. Levels of the differentiation marker, tau, also rose. In contrast, AChE expression in cell lines containing an antisense construct was half of that observed in the wild type. Significant reductions in neurite outgrowth and tau protein accompanied this effect. Overall, these measures correlated statistically with the AChE level (p < 0.01). Furthermore, treatment of AChE-overexpressing cells with a polyclonal antibody against AChE decreased neurite outgrowth by 43%. We conclude that AChE may have a novel, noncholinergic role in neuronal differentiation.

Acetylcholinesterase↗
PubMed1997

Engineered cell surfaces: fertile ground for molecular landscaping.

The cell surface contains a wealth of information that determines how cells interact with their environment. Methods for directing the cell surface expression of novel protein-based and oligosaccharide-based epitopes are stimulating new directions in biotechnology and biomedical research.

Biotechnology↗
PubMed1996

Murine colon carcinoma cells engineered to produce human interleukin-2 induce tumor-specific anti-tumor response.

Murine colon carcinoma cells (colon 26) transduced by a retrovirus vector with the human interleukin-2 (IL-2) cDNA were studied for their tumorigenicity. Although cell growth in vitro was not affected by integration of the IL-2 gene, s.c. tumors of IL-2-producing colon 26 cells (H2) in syngeneic mice regressed spontaneously after producing small masses. Histological examination of the sites of tumor rejection revealed predominant infiltration of macrophages around the tumor necrotic mass. Subsequent challenge with parent colon 26 cells, but not with Meth A cells (fibrosarcoma of the same genetic background), did not result in tumor formation in mice which had been protected against H2 cells. Inoculation of H2 cells into syngeneic nude mice resulted in tumors with a retarded growth rate. Taken together, T cell-dependent, tumor-specific immunity is obtained by local IL-2 secretion around colon tumors, and this experimental animal model gives us a clue(s) for investigating host anti-tumor responses by cytokine production.

Animals↗
PubMed1993

Self-reactive antibody expression by human carcinoma cells engineered with monoclonal antibody genes.

The purpose of this study was to determine if human colon cancer cells transduced with monoclonal antibody (MAb) genes become sensitive to immune destruction through coexpression of both the MAb and its reactive antigen. Murine retroviral expression vectors were constructed with the heavy or light chain genes of an anti-human colon carcinoma MAb, D612, that mediates antibody-dependent cell-mediated cytotoxicity (ADCC). Transduction of D612 MAb genes into the D612 antigen-positive (> 95%) human colon carcinoma cell line, LS-174T, was carried out by sequential cocultivation with PA317 packaging cells producing infectious virions containing the light or heavy chain expression vectors. Six cultures survived drug selection, two of which were found to have elevated levels of both light and heavy immunoglobulin chain activity in their supernatants. IgG secretion levels (24 h) were 1-2 ng/1 x 10(6) cells. Low but definite antigen reactivity was also present in supernatants obtained from these LS-174T transductants. Immunocytochemical staining of transduced tumor cells revealed that > 95% of the cells were positive for IgG expression. Thus, LS-174T transductants were capable of producing both the D612 MAb and D612-reactive antigen. Analysis of transductants by flow cytometry further revealed that > 95% of the cells had murine immunoglobulin on their surfaces. ADCC mediated by human natural killer cells against nontransduced tumor cells was observed when the latter cells were co-cultivated in the presence of transductants producing both D612 heavy and light chains but not in the presence of tumor cells transduced with light chain only. LS-174T cells transduced with both D612 heavy and light chain genes were more sensitive to cytotoxicity mediated by natural killer cells than were light chain gene only transductants. ADCC contributed to the greater sensitivity of the former transductants to cytotoxicity based on its inhibition by anti-FcR gamma III antibody. Thus, these studies demonstrate that tumor cells transduced with genes encoding for MAbs that can participate in ADCC reactions are able to sensitize nontransduced tumor cells to immune destruction as well as to direct killer cells against themselves. These studies may lead to a new immunotherapeutic approach for the treatment of cancer based on MAb gene therapy.

Antibodies, Monoclonal↗
PubMed1996

Microencapsulation and transplantation of genetically engineered cells: a new approach to somatic gene therapy.

In order to develop a model for gene therapy which avoids dependence on an autologous source of target cells and immunosuppressive therapy, mouse Ltk fibroblasts transfected with a human growth hormone (hGH) fusion gene were encapsulated in a semipermeable alginate-poly-L-lysine-alginate (APA) membrane. The encapsulated cells were cultured in vitro or transplanted intraperitoneally into mice to monitor cell viability, cell growth, and hGH secretion. The effect of Zn2+ ions on vector expression was also monitored in vitro and in vivo. Results indicate that: (1) the capsule environment is compatible with cell viability and cell growth; (2) the capsule limits cell growth; (3) the capsule membrane is permeable to the exit of hGH; (4) gene product expression may be stimulated by external means; (5) the novel gene product is delivered in vivo; and (6) encapsulated cells recovered from transplant recipients continue to secrete hGH in vitro. The results suggest therapeutic potential of this approach to somatic gene therapy.

Animals↗
PubMed1996

Therapeutic effectiveness of the immunity elicited by P815 tumor cells engineered to express the B7-2 costimulatory molecule.

It is well accepted that inoculation of B7-1-transfected tumor cells into normal mice leads to tumor rejection and subsequent resistance to challenge. However, the effectiveness of B7-2-transfected tumor cells in eliciting protective antitumor immunity is less clear. Here we show that B7-2-transfected P815 tumor cells (B7-2+) are as effective as B7-1-transfected P815 tumor cells (B7-1+) in eliciting protective immunity in normal DBA/2 mice. In addition, B7-2+ cells were found to be at least as effective as B7-1+ cells retarding tumor progression when admixed with parental P815 tumor cells prior to inoculation into normal mice. Moreover, the B7-2+ cells and the B7-1+ cells were equivalent in their ability to retard tumor growth when administered peritumorally into mice bearing established (approx. 3 mm in diameter) parental P815 tumors. Finally, P815 tumor cells infected with a recombinant replication-defective adenovirus encoding the murine B7-2 gene were effective in retarding the growth of established parental P815 tumors. Thus, B7-1 and B7-2 are comparable in terms of their ability to stimulate the generation of tumor-eradicating immunity in normal mice as well as in mice bearing established parental tumors. Moreover, adenovirus vectors can be used to generate B7-2-expressing tumor cells effective in the immunotherapy of established parental tumors.

Adenoviridae↗