Biomedical subjects

W M Siders

Publications and source records attributed to W M Siders.

6 recordsLinked to original sources

PubMed2000

Cationic lipid:bacterial DNA complexes elicit adaptive cellular immunity in murine intraperitoneal tumor models.

Previous studies with a mycobacterial heat shock protein (hsp-65) have demonstrated some efficacy using cationic liposome-mediated gene transfer in murine i.p. sarcoma models. To further analyze the efficacy of hsp-65 immunotherapy in clinically relevant models of localized cancer, immunocompetent mice bearing i.p. murine mesothelioma were treated with four i.p. doses of a cationic lipid complexed with plasmid DNA (pDNA) containing hsp65, LacZ, or a null plasmid. We observed >90% long-term survival (median survival, 150 days versus approximately 25 days, treated versus saline control, respectively) in a syngeneic, i.p. murine mesothelioma model (AC29). Long-term survivors were observed in all groups treated with lipid complexed with any pDNA. Lipid alone or DNA alone provided no demonstrable survival advantage. In a more aggressive i.p. model of mesothelioma (AB12), we observed >40% long-term survival in groups treated with lipid:pDNA complexes, again irrespective of the transgene. To ask whether these antitumor effects had led to an adaptive immune response against the tumor cell, we rechallenged long-term survivors in both murine models s.c. with the parental tumor cell line. Specific, long-lasting systemic immunity against the tumor was readily demonstrated in both models (AB12 and AC29). Consistent with these results, splenocytes from long-term survivors specifically lysed the parental tumor cell lines. Depleting the CD8+ T-cells from the splenocyte pool eliminated this lytic activity. Lipid:pDNA treatment of athymic, SCID, and SCID/Beige mice bearing a murine i.p. mesothelioma (AC29) resulted in only a slight survival advantage, but there were no long-term survivors. Treatment of immunocompetent mice depleted of specific immune effector cells demonstrated roles for CD8+ and natural killer cells. Although the exact mechanism(s) responsible for these antitumor effects is unclear, the results are consistent with roles for both innate and adaptive immune responses. An initial tumor cell killing stimulated by cationic lipid:pDNA complexes appears to be translated into long-term, systemic immunity against the tumor cell. These results are the first to demonstrate that adaptive immunity against a tumor cell can be induced by the administration of lipid:pDNA complexes. Multiple administrations of cationic lipid complexed with pDNA lacking an expressed transgene could provide a promising generalized immune-mediated modality for treating cancer.

Animals↗

PubMed1998

T cell- and NK cell-independent inhibition of hepatic metastases by systemic administration of an IL-12-expressing recombinant adenovirus.

IL-12 is a potent immunoregulatory cytokine that has been shown to mediate tumor regression in a variety of tumor models. We describe the construction of AdCMV-IL-12, a recombinant adenovirus that encodes both subunits of IL-12 under transcriptional control of the CMV promoter. This recombinant virus efficiently infects a wide variety of cell types leading to the production of high levels of biologically active IL-12. Because the liver is a primary site of infection after i.v.-administered adenovirus, we tested the therapeutic efficacy of this virus in a murine hepatic metastasis tumor model. Systemic administration of AdCMV-IL-12 dramatically inhibited the formation of 3-day Renca hepatic metastases (mean of 16 metastases per liver) compared with the control virus AdCMV-betagal (mean of 209) or vehicle alone (mean of 272). Histologic analysis indicated that metastatic growth inhibition was accompanied by a dramatic perivascular infiltrate consisting of T cells, macrophages, and neutrophils. Therapeutic efficacy was not diminished in animals depleted of CD4+ or CD8+ T cells, or in SCID mice, even after NK cell ablation. In the latter case, a hepatic perivascular infiltrate composed of macrophages and neutrophils was observed after AdCMV-IL-12-treatment, while numerous activated Kupffer cells were noted in the hepatic parenchyma. Analysis of therapy-induced changes in hepatic gene expression demonstrated increased levels of IP-10 and Mig RNAs, but no increase in iNOS, Fas, or FasL RNA levels was observed. Our data suggest a model of metastatic growth inhibition mediated by nonlymphocyte effector cells including macrophages and neutrophils and that may involve anti-angiogenic chemokines.

Adenocarcinoma↗

PubMed1996

Transcriptional targeting of recombinant adenoviruses to human and murine melanoma cells.

One potential avenue for future cancer therapy involves the specific targeting of effector genes to cancer cells throughout the body, including distant metastatic sites. As a first step toward this goal, we tested the ability of the transcriptional regulatory elements of the human and mouse tyrosinase genes to promote high levels of pigment cell-specific transcription. A construct consisting of 209 bp of the human tyrosinase promoter linked to two enhancer elements was demonstrated to drive high-level, melanoma-specific expression of a beta-galactosidase (beta-gal) reporter gene in transient transfection assays. In studies of the murine tyrosinase promoter region, constructs containing up to 2500 bp of the 5' regulatory region were found to have very low transcriptional activity in murine melanoma cells. However, as with the human system, addition of two tandem repeats of an upstream enhancer element resulted in high levels of lineage-specific transcriptional activation. The murine tyrosinase promoter-enhancer expression cassette was introduced into the E1 region of a recombinant adenovirus to generate the virus AdmTyr-beta gal. This virus grows to high titer and maintains transcriptional specificity for pigment cell lineages. Strikingly, AdmTyr-beta gal is extremely active in human melanoma cells, in some cases exceeding the transcriptional activity of a cytomegalovirus promoter-driven recombinant beta-gal virus. Tissue specificity of gene expression is maintained, with very low levels observed in tumors and primary human cells derived from other lineages. These data provide evidence that it is possible to target human melanoma cells with great efficiency and specificity using high-titer recombinant adenovirus vectors.

Adenoviridae↗

PubMed1995

Interleukin-1 beta secretion. A possible multistep process that is regulated in a cell type-specific manner.

In a prior study, we found that the processed form of human interleukin-1 beta (mature IL-1 beta) is secreted to a significantly greater extent than the precursor form of the protein, indicating that the precursor domain acts in some manner to reduce the secretory potential of the protein. In view of this observation, we sought to define the sequence(s) in the IL-1 beta precursor that limit the secretion of the protein as well as the sequences in the mature protein that promote secretion. The P388D1 murine macrophage cell line and the Jurkat human T-cell line were transiently transfected with cDNA expression vectors encoding truncated forms of human precursor IL-1 beta proteins, lacking either the first 76, 94, 99, or 104 amino acids. The removal of increasing numbers of precursor amino acid residues resulted in a graded increase in the secretion of the truncated precursor IL-1 beta proteins from both cell lines. The minimal region of the precursor sequence required to inhibit the optimal secretion of IL-1 beta occurs between amino acids 100 and 104 for P388D1 cells and 95-99 for Jurkat cells. Deletion of the amino acids within these regions increased the secretion level of the truncated proteins to that of mature IL-1 beta. Mutagenesis of the mature IL-1 beta sequence revealed that a region of basic amino acids may play an important role in the optimal secretion of mature IL-1 beta in P388D1 cells, but not in Jurkat cells. Based on the differences in the structural requirements for IL-1 beta secretion in P388D1 and Jurkat cell lines, it is likely that the secretion of IL-1 beta may be subject to multiple levels of regulation that are differentially operative in different cell types.

Amino Acid Sequence↗

PubMed1993

Characterization of the structural requirements and cell type specificity of IL-1 alpha and IL-1 beta secretion.

The murine macrophage cell line, P388D1, was transfected with expression plasmids containing a cDNA for the precursor or mature form of human interleukin (IL)-1 alpha or -1 beta, and the extent of IL-1 protein secretion was analyzed. The secretion of IL-1 beta from cells transfected with a cDNA encoding the mature IL-1 beta was approximately 15-fold greater than from cells transfected with a precursor IL-1 beta cDNA. Although P388D1 cells transfected with precursor and mature IL-1 alpha cDNAs exhibited similar levels of secretion, the precursor IL-1 alpha cDNA-transfected cells secreted only the mature form of IL-1 alpha. Relatively high levels of IL-1 secretion were also observed in cultures of HeLa cells and the murine EL 4 and human Jurkat T cell lines that were transfected with a mature IL-1 alpha or -beta expression plasmid. Secretion was not observed when these cell lines were transfected with precursor IL-1 alpha or -beta expression plasmids. Secretion was also minimal when P388D1 cells were transfected with cDNAs encoding mature IL-1 beta proteins lacking the NH2- or COOH-terminal 20 amino acids. These results indicate that the mature forms of IL-1 proteins are the preferred substrates for secretion and that the maintenance of a specific conformation of these proteins may be required for optimal secretion.

Amino Acid Sequence↗

PubMedDate not supplied

Melanoma-specific cytotoxicity induced by a tyrosinase promoter-enhancer/herpes simplex virus thymidine kinase adenovirus.

The ability to specifically and efficiently express selected genes in tumor cells is an important goal for cancer gene therapy. Transcriptional targeting of adenovirus to tumor cells, thereby limiting their expression to specific cell types, represents one experimental approach to this problem. We have previously shown that a recombinant adenovirus containing the murine tyrosinase promoter coupled to a dimer of the tyrosinase-enhancer element can target the expression of beta-galactosidase cDNA to melanoma cells. We now report that this same promoter/enhancer cassette can efficiently drive the expression of the herpes simplex virus thymidine kinase gene in melanoma cells. Infection of melanoma cells with the AdmTyr-tk virus along with subsequent ganciclovir treatment induces S phase cell cycle arrest associated with a profound change in cell size and morphology. Treated cells remain viable for prolonged periods, but clonogenic assays demonstrate that the cell cycle arrest is irreversible. In contrast, nonmelanoma cells are unaffected by this treatment regimen, exhibiting normal growth kinetics, metabolic activity, and cell cycle progression. The therapeutic efficacy of the AdmTyr-tk virus was tested in vivo using a xenograft model of human melanoma. The injection of the AdmTyr-tk virus into established subcutaneous tumor nodules in combination with systemic ganciclovir administration led to a decreased tumor growth rate and to complete tumor regressions in some cases. These studies demonstrate the feasibility of selectively targeting growth-inhibitory genes to melanoma cells in vitro and in vivo.

Adenoviridae↗