Biomedical subjects

Y Sun

Publications and source records attributed to Y Sun.

At least 127 records · Page 7Linked to original sources

PubMed2001

Regulation of CD40 and CD40 ligand by the AT-hook transcription factor AKNA.

Proteins containing AT hooks bind A/T-rich DNA through a nine-amino-acid motif and are thought to co-regulate transcription by modifying the architecture of DNA, thereby enhancing the accessibility of promoters to transcription factors. Here we describe AKNA, a human AT-hook protein that directly binds the A/T-rich regulatory elements of the promoters of CD40 and CD40 ligand (CD40L) and coordinately regulates their expression. Consistent with its function, AKNA is a nuclear protein that contains multiple PEST protein-cleavage motifs, which are common in regulatory proteins with high turnover rates. AKNA is mainly expressed by B and T lymphocytes, natural killer cells and dendritic cells. During B-lymphocyte differentiation, AKNA is mainly expressed by germinal centre B lymphocytes, a stage in which receptor and ligand interactions are crucial for B-lymphocyte maturation. Our findings show that an AT-hook molecule can coordinately regulate the expression of a key receptor and its ligand, and point towards a molecular mechanism that explains homotypic cell interactions.

Amino Acid Sequence↗

PubMed2001

Studies using structural analogs and inbred strain differences to support a role for quinone methide metabolites of butylated hydroxytoluene (BHT) in mouse lung tumor promotion.

Chronic treatment of BALB and GRS mice with BHT (2,6-di-tert-butyl-4-methylphenol) following a single urethane injection increases lung tumor multiplicity, but this does not occur in CXB4 mice. Previous data suggest that promotion requires the conversion of BHT to a tert-butyl-hydroxylated metabolite (BHTOH) in lung and the subsequent oxidation of this species to an electrophilic quinone methide. To obtain additional evidence for the importance of quinone methide formation, structural analogs that form less reactive quinone methides were tested and found to lack promoting activity in BHT-responsive mice. The possibility that promotion-unresponsive strains are unable to form BHTOH was tested by substituting this compound for BHT in the promotion protocol using CXB4 mice. No promotion occurred, and in-vitro work demonstrated that CXB4 mice are, in fact, capable of producing BHTOH and its quinone methide, albeit in smaller quantities. Incubations with BALB lung microsomes and radiolabeled substrates confirmed that more covalent binding to protein occurs with BHTOH than with BHT and, in addition, BHTOH quinone methide is considerably more toxic to mouse lung epithelial cells than BHT quinone methide. These data are consistent with the hypothesis that a two-step oxidation process, i.e. hydroxylation and quinone methide formation, is required for the promotion of mouse lung tumors by BHT.

Animals↗

PubMed2001

Hormonal regulation of mitochondrial Tim23 gene expression in the mouse mammary gland.

Tim23, a mitochondrial inner membrane protein, is essential for cell viability. Mouse Tim23 cDNA consisted of 1142 nucleotides plus poly(A) at the 3' end. In situ hybridization showed that mammary epithelial cells expressed Tim23 mRNA during pregnancy. In order to examine the hormonal regulation of the Tim23 gene expression at lactogenesis, the quantity of Tim23 mRNA in the mammary gland was determined by the competitive RT-PCR. The level of Tim23 mRNA was low until mid-pregnancy, increased toward the end of pregnancy and was the highest on day 18 of pregnancy. On day 13 of pregnancy, Tim23 mRNA increased 2.7-fold between 8 and 16 h after ovariectomy but this increase was cancelled out by the simultaneous operation of adrenalectomy. In adreno-ovariectomized mice, the administration of cortisol increased Tim23 mRNA 2-fold but with progesterone, the stimulatory action of cortisol was no longer observed. The results indicated that the expression of the Tim23 gene became active in response to glucocorticoid.

Animals↗

PubMed2001

Role of cysteinyl residues in sensing Pb(II), Cd(II), and Zn(II) by the plasmid pI258 CadC repressor.

The cadCA operon of Staphylococcus aureus plasmid pI258 confers resistance to salts of the soft metals lead, cadmium, and zinc. The operon is regulated by CadC, a member of the ArsR family of metal-responsive transcriptional repressors. In this study the role of the five cysteine residues of CadC in soft metal ion sensing was investigated. Cys-7, Cys-11, Cys-52, Cys-58, and Cys-60 were changed individually to glycine or serine residues. The effect of the cadC mutations was examined in Escherichia coli using a green fluorescent protein reporter system. None of the mutations affected the ability of CadC to repress gfp expression. Neither Cys-11 nor Cys-52 was required for in vivo response to Pb(II), Zn(II), or Cd(II). Cys-7, Cys-58, or Cys-60 mutations each reduced or eliminated soft metal sensing. Wild-type and mutant CadC proteins were purified, and the effect of the substitutions on DNA binding was determined using a restriction enzyme protection assay. Binding of wild-type CadC protected cad operator DNA from digestion at the single SspI site, and the addition of Pb(II), Zn(II), or Cd(II) resulted in deprotection. Chemical modification of the cysteine residues in CadC had no effect on protection but eliminated deprotection. C11G and C52G proteins exhibited wild-type properties in vitro. C7G, C58S, and C60G proteins were able to be protected from SspI digestion but had reduced responses to soft metal ions. The results indicate that Cys-7, Cys-58, and Cys-60 are involved in sensing those soft metals and suggest that they are ligands to Pb(II), Zn(II), and Cd(II).

Amino Acid Sequence↗

PubMed2001

Neurogenin promotes neurogenesis and inhibits glial differentiation by independent mechanisms.

The mechanisms by which neural stem cells give rise to neurons, astrocytes, or oligodendrocytes are beginning to be elucidated. However, it is not known how the specification of one cell lineage results in the suppression of alternative fates. We find that in addition to inducing neurogenesis, the bHLH transcription factor neurogenin (Ngn1) inhibits the differentiation of neural stem cells into astrocytes. While Ngn1 promotes neurogenesis by functioning as a transcriptional activator, Ngn1 inhibits astrocyte differentiation by sequestering the CBP-Smad1 transcription complex away from astrocyte differentiation genes, and by inhibiting the activation of STAT transcription factors that are necessary for gliogenesis. Thus, two distinct mechanisms are involved in the activation and suppression of gene expression during cell-fate specification by neurogenin.

Animals↗

PubMed2001

Signal via lymphotoxin-beta R on bone marrow stromal cells is required for an early checkpoint of NK cell development.

NK cells play an important role in the immune system but the cellular and molecular requirements for their early development are poorly understood. Lymphotoxin-alpha (LTalpha)(-/-) and LTbetaR(-/-) mice show a severe systemic reduction of NK cells, which provides an excellent model to study NK cell development. In this study, we show that the bone marrow (BM) or fetal liver cells from LTalpha(-/-) or LTbetaR(-/-) mice efficiently develop into mature NK cells in the presence of stromal cells from wild-type mice but not from LTalpha(-/-) or LTbetaR(-/-) mice. Direct activation of LTbetaR-expressing BM stromal cells is shown to promote to early NK cell development in vitro. Furthermore, the blockade of the interaction between LT and LTbetaR in adult wild-type mice by administration of LTbetaR-Ig impairs the development of NK cells in vivo. Together, these results indicate that the signal via LTbetaR on BM stromal cells by membrane LT is an important pathway for early NK cell development.

Adoptive Transfer↗

PubMed2001

DNA hypomethylation perturbs the function and survival of CNS neurons in postnatal animals.

DNA methyltransferase I (Dnmt1), the maintenance enzyme for DNA cytosine methylation, is expressed at high levels in the CNS during embryogenesis and after birth. Because embryos deficient for Dnmt1 die at gastrulation, the role of Dnmt1 in the development and function of the nervous system could not be studied by using this mutation. We therefore used the cre/loxP system to produce conditional mutants that lack Dnmt1 in neuroblasts of embryonic day 12 embryos or in postmitotic neurons of the postnatal animal. Conditional deletion of the Dnmt1 gene resulted in rapid depletion of Dnmt1 proteins, indicating that the enzyme in postmitotic neurons turns over quickly. Dnmt1 deficiency in postmitotic neurons neither affected levels of global DNA methylation nor influenced cell survival during postnatal life. In contrast, Dnmt1 deficiency in mitotic CNS precursor cells resulted in DNA hypomethylation in daughter cells. Whereas mutant embryos carrying 95% hypomethylated cells in the brain died immediately after birth because of respiratory distress, mosaic animals with 30% hypomethylated CNS cells were viable into adulthood. However, these mutant cells were eliminated quickly from the brain within 3 weeks of postnatal life. Thus, hypomethylated CNS neurons were impaired functionally and were selected against at postnatal stages.

Animals↗

PubMed2001

Overexpression of 12-lipoxygenase causes cardiac fibroblast cell growth.

Evidence suggests that leukocyte type 12-lipoxygenase (12-LO) plays an important role in cell growth. However, the role of 12-LO in cardiac cell growth has not been tested. We have now stably overexpressed 12-LO cDNA in rat fetal cardiac fibroblasts to evaluate the role of the 12-LO pathway in cardiac cell growth. Overexpression of 12-LO increased cell [(3)H]leucine incorporation by 2.1+/-0.1-fold (P<0.01) and cell protein content by 2.2+/-0. 3-fold (P<0.01) over mock-transfected cells. These findings were confirmed in additional clones. Baicalein, a 12-LO enzyme inhibitor, dose-dependently inhibited serum-induced leucine incorporation in cardiac fibroblast cells as well as partially inhibited leucine incorporation in cells overexpressing 12-LO. 12-LO overexpression also caused cell [(3)H]thymidine incorporation to increase by 3.4+/-0.3-fold (P<0.01). Cell flow cytometry analysis showed that the size of 12-LO-overexpressing cells was markedly enlarged compared with that of mock-transfected cells. The fibronectin content of the 12-LO-overexpressing cardiac fibroblasts was also significantly increased. We next evaluated the effects of 12-LO RNA overexpression on kinase pathways linked to cellular growth. The overexpression of 12-LO enhanced extracellular signal-regulated kinase activity (4. 1+/-0.5-fold), c-Jun NH(2)-terminal kinase activity (2.9+/-0.5-fold), and p38 mitogen-activated protein kinase activity (2.2+/-0.3-fold). Pretreatment with SB202190 (100 nmol/L), a specific inhibitor of p38, prevented the increases in protein content of 12-LO-overexpressing cardiac fibroblast cells. These data clearly demonstrate that the overexpression of 12-LO causes cell growth of cardiac fibroblasts, thus supporting the role of 12-LO as a novel growth-promoting pathway in the heart.

Animals↗

PubMed2001

Nerve growth factor antiserum induces axotomy-like changes in neuropeptide expression in intact sympathetic and sensory neurons.

Axonal transection of adult sympathetic and sensory neurons leads to a decrease in their content of target-derived nerve growth factor (NGF) and to dramatic changes in the expression of several neuropeptides and enzymes involved in transmitter biosynthesis. For example, axotomy of sympathetic neurons in the superior cervical ganglion (SCG) dramatically increases levels of galanin, vasoactive intestinal peptide (VIP), and substance P and their respective mRNAs and decreases mRNA levels for neuropeptide Y (NPY) and tyrosine hydroxylase (TH). Axotomy of sensory neurons in lumbar dorsal root ganglia (DRG) increases protein and mRNA levels for galanin and VIP and decreases levels for substance P and calcitonin gene-related peptide (CGRP). To assess whether reduction in the availability of endogenous NGF might play an important role in triggering these changes, we injected nonoperated animals with an antiserum against NGF (alphaNGF). alphaNGF increased levels of peptide and mRNA for galanin and VIP in neurons in both the SCG and DRG. NPY protein and mRNA were decreased in the SCG, but levels of TH protein and mRNA remained unchanged. In sensory neurons the levels of SP and CGRP protein decreased after alphaNGF treatment. These data suggest that the reduction in levels of NGF in sympathetic and sensory neurons after axotomy is partly responsible for the subsequent changes in neuropeptide expression. Thus, the peptide phenotype of these axotomized neurons is regulated both by the induction of an "injury factor," leukemia inhibitory factor, as shown previously, and by the reduction in a target-derived growth factor.

Animals↗

PubMed2001

Complementary effects of TNF and lymphotoxin on the formation of germinal center and follicular dendritic cells.

The formation of germinal centers (GC) around follicular dendritic cells (FDC) is a critical step in the humoral immune responses that depends on the cooperative effects of B cells and T cells. Mice deficient in either TNF or lymphotoxin (LT) fail to form both GC and FDC network in B cell follicles. To test a potential complementary effect of TNF and LT, a mixture of bone marrow cells from TNF(-/-) mice and LT alpha(-/-) mice was transferred into irradiated LT alpha(-/-) mice or TNF(-/-) mice. Interestingly, the formation of both GC and FDC clusters in B cell follicles was restored in such chimeric mice, suggesting that TNF and LT from different cells could complement one another. To identify the exact contributions of each subset to the complementary effect of TNF and LT, different sources of T and B cells from LT alpha(-/-) mice or TNF(-/-) mice were used for reconstitution. Our study demonstrates that either T or B cell-derived TNF is sufficient to restore FDC/GC in the presence of LT-expressing B cells. However, TNF itself is not required for GC reactions if the FDC network is already intact. Thus, the development and maintenance of these lymphoid structures depend on a delicate interaction between TNF and LT from different subsets of lymphocytes.

Adjuvants, Immunologic↗

PubMed2001

Independent anchoring and assembly mechanisms of INAD signaling complexes in Drosophila photoreceptors.

In Drosophila photoreceptors the multivalent PDZ protein INAD organizes the phototransduction cascade into a macromolecular signaling complex containing the effector PLC, the light-activated TRP channels, and a regulatory PKC. Previously, we showed that the subcellular localization of INAD signaling complexes is critical for signaling. Now we have examined how INAD complexes are anchored and assembled in photoreceptor cells. We find that trp mutants, or transgenic flies expressing inaD alleles that disrupt the interaction between INAD and TRP, cause the mislocalization of the entire transduction complex. The INAD-TRP interaction is not required for targeting but rather for anchoring of complexes, because INAD and TRP can be targeted independently of each other. We also show that, in addition to its scaffold role, INAD functions to preassemble transduction complexes. Preassembly of signaling complexes helps to ensure that transduction complexes with the appropriate composition end up in the proper location. This may be a general mechanism used by cells to target different signaling machinery to the pertinent subcellular location.

Animals↗

PubMed2001

Promotion of S-phase entry and cell growth under serum starvation by SAG/ROC2/Rbx2/Hrt2, an E3 ubiquitin ligase component: association with inhibition of p27 accumulation.

The sensitive-to-apoptosis gene (SAG) was initially identified as a redox-inducible, apoptosis-protective protein and subsequently found to be the second family member of regulator of cullins (ROC)/RING box protein (Rbx)/Hrt, which acts as a component of E3 ubiquitin ligase. We report here that SAG promoted cell growth under serum starvation. Microinjection of SAG mRNA into quiescent NIH/3T3 cells induced S-phase entry as determined by [(3)H]-thymidine incorporation. Likewise, overexpression of SAG by either adenovirus infection of immortalized human epidermal keratinocytes (Rhek-1) or DNA transfection of SY5Y human neuroblastoma cells induced cell proliferation under serum starvation. Because cyclin-dependent kinase inhibitors (CKIs), including p21, p27, and p57, are degraded through the ubiquitin pathway, we tested whether SAG-induced cell growth is associated with CKI degradation. Although there was no significant difference in the levels of p21 and p57 between the vector controls and SAG-overexpressing cells, serum starvation induced 10- to 18-fold accumulation of p27 in control Rhek-1 cells. Accumulation of p27 was remarkably inhibited (only 2 to 5-fold) in SAG-infected cells. Inhibition of p27 accumulation was also observed in stably SAG-overexpressing SY5Y cells. Significantly, SAG-associated inhibition of p27 accumulation was largely abolished by the treatment with a proteasome inhibitor. In vivo binding of SAG and Skp2, an F-box protein that promotes p27 ubiquitination, was detected, and the binding was enhanced in SAG-overexpressing cells grown under serum starvation. Thus, SAG-induced growth with serum withdrawal appears to be associated with SAG-mediated p27 degradation. Mol. Carcinog. 30:37-46, 2001.

Animals↗

PubMed2001

USPIO-enhanced dynamic MRI: evaluation of normal and transplanted rat kidneys.

To evaluate first-pass renal perfusion with ultrasmall superparamagnetic iron oxide (USPIO) particles by MRI, 40 normal rats (20 Dark Agouti (DA) rats and 20 Brown Norway (BN) rats) and 16 transplanted rats (12 allografts and four isografts) were studied on day 4 post-transplantation with different USPIO doses (3.0-18.1 mg Fe/kg/body weight). All animals underwent 128 consecutive snapshot fast low-angle shot (FLASH) coronal dynamic studies in 43 s. In the normal rats, a larger maximum signal decrease (MSD) in the cortex and the outer medulla is observed with an increasing dose of USPIO particles (P < 0.01). No significant differences were observed between the right and left kidneys at all doses studied. Higher MSD, time of occurrence of MSD (tMSD), and wash-in slope appear with higher doses of USPIO particles. The dynamic curves for DA rats show similar shapes when compared to those for BN rats. In the transplanted rats, allograft kidneys show lower MSD, longer tMSD, and lower wash-in slope compared to those in the normal kidneys. Isograft kidneys show perfusion patterns similar to those of normal kidneys in the cortex and the outer medulla. Histopathology indicates acute vascular rejection in all allografts and normal kidney architecture in all isografts. The results clearly show good agreement between the renal graft perfusion measurements and histopathological changes associated with rejection. This work also introduces a new signal analysis methodology for the automatic detection of transplanted organ rejection. This method compares the dynamics of the intrarenal signal intensities for native and transplanted kidneys. A quantitative measurement to detect significant differences between these signals was developed, and showed that this technique exhibits good performance in identifying renal rejection.

Animals↗

PubMed2001

Decreased interferon-alpha production in HIV-infected patients correlates with numerical and functional deficiencies in circulating type 2 dendritic cell precursors.

Peripheral blood mononuclear cells from patients with human immunodeficiency virus (HIV) infection exhibit a progressively marked decrease in the production of virus-induced interferon (IFN)-alpha, a finding that correlates with and is highly predictive of disease progression and opportunistic infections. The major IFN-alpha producing population has recently been defined as the precursor to type 2 dendritic cells (pDC2) or plasmacytoid DC (pDC). Using four-color flow cytometry, we have enumerated the pDC2 vs non-IFN-alpha producing myeloid DC1 in peripheral blood from HIV-infected patients and healthy controls and related these values to CD4 cell numbers, viral load, and functional activity. The patients had reductions in the numbers of both pDC2 (lin-/HLA-DR+/CD123(bright)) and DC1 (lin1-/HLA-DR+/CD123(dim)/CD11c+), both at an absolute level and as a percentage of cells. The decreases were most evident in patients with decreased CD4 levels. Viral load correlated with the functional frequency of the IFN producing cells but not with absolute pDC2 levels. Using intracellular flow cytometric analysis for IFN-alpha, the patients were demonstrated to have fewer pDC2, as well as a lower percentage of responding cells among those remaining. We conclude that deficient production of IFN-alpha by pDC2 from HIV-infected patients results from both selective loss of these cells and their qualitative dysfunction. Given the central role of DC, and in particular, DC2, in linking innate and adaptive immune responses, these qualitative and quantitative changes in pDC2 are likely to be key contributors to HIV pathogenesis.

CD4 Lymphocyte Count↗

PubMed2001

Renin expression at sites of repair in the infarcted rat heart.

Y. Sun, J. Zhang, J. Q. Zhang and K. T. Weber. Renin Expression at Sites of Repair in the Infarcted Rat Heart. Journal of Molecular and Cellular Cardiology (2001) 33, 995-1003. Angiotensin (Ang) II has autocrine and paracrine functions that contribute to structural cardiac remodeling by fibrous tissue following myocardial infarction (MI). The recruitment of angiotensin converting enzyme (ACE) and AngII receptors by inflammatory and fibroblast-like cells involved in tissue repair of the infarcted heart is now well established. On the other hand, the temporal and spatial response and cellular source of renin in infarcted hearts have not been fully elucidated. The relationship between renin synthesis and circulating renin activity have likewise not been addressed. The present study sought to assess the cellular source, spatial distribution and temporal response of renin expression and synthesis in the rat heart following anterior transmural MI, and to determine its relationship to circulating renin activity. At day 3 and weeks 1, 2, 3 and 4 following left coronary artery ligation, the localization and optical density of cardiac renin mRNA was detected by quantitative in situ hybridization; cardiac and circulating renin activity was measured by radioimmunoassay; cells expressing cardiac renin were detected by immunohistochemistry; and injury/repair was assessed by hematoxylin/eosin and collagen-specific picrosirius red staining. Unoperated rats served as normal controls. The authors found: (1) renin mRNA and activity were not detected in either normal control or non-infarcted myocardium, but were expressed at the site of infarction and other sites of repair involving visceral pericardium and endocardium of interventricular septum at all time points; (2) cells expressing renin at day 3 and weeks 1 and 2 were predominantly macrophages, while at weeks 3 and 4, they were primarily myofibroblasts; (3) renin activity in the infarcted myocardium rose progressively over the course of 4 weeks; and (4) circulating renin activity was significantly increased at day 3 and week 1, reached a peak at week 2, declined at week 3 and returned to normal levels at week 4. Thus, renin expression and activity appear at sites of repair in the infarcted rat heart on day 3 and rise progressively thereafter over 4 weeks, independent of circulating renin. Several types of cells are responsible for renin synthesis at these sites; primarily macrophages during the inflammatory phase of repair, and myofibroblasts during the subsequent fibrogenic phase. Cardiac renin production following MI contributes to local AngII generation that regulates tissue repair and structural remodeling following MI.

Actins↗

PubMed2001

Tissue inhibitor of metalloproteinase-3 is a basement membrane-associated protein that is significantly decreased in human colorectal cancer.

PURPOSE: The balance between local levels of matrix metalloproteinases and tissue inhibitor of metalloproteinases is believed to play a key role in tumor invasion and metastases. Because tissue inhibitor of metalloproteinase-3 suppresses tumorigenicity and tumor invasion in vitro, the aim of this study was to determine its expression in human colorectal cancer. METHODS: Thirty-nine human colorectal cancer specimens, three adenomas, and matched normal adjacent mucosa from 39 colorectal cancer patients were analyzed. Tissue inhibitor of metalloproteinase-3 ribonucleic acid and protein expression were analyzed by Northern blot hybridization and Western blot analysis, respectively. The cellular localizations of tissue inhibitor of metalloproteinase-3 ribonucleic acid and protein were determined by in situ hybridization and immunolocalization. RESULTS: Tissue inhibitor of metalloproteinase-3 ribonucleic acid expression was increased in colorectal cancer compared with paired normal mucosa. In contrast, tissue inhibitor of metalloproteinase-3 protein level was higher in normal mucosa than in the corresponding colorectal cancer. In addition, tissue inhibitor of metalloproteinase-3 protein levels progressively decreased with advancing colorectal cancer stages. Tissue inhibitor of metalloproteinase-3 protein tumor to normal mucosa ratio was 0.74 +/- 0.12, 0.51 +/- 0.18, 0.48 +/- 0.12, and 0.45 +/- 0.2 for Dukes A (n = 8), B (n = 9), C (n = 9), and D (n = 13) stages, respectively. Both tissue inhibitor of metalloproteinase-3 messenger ribonucleic acid and protein were located predominantly within spindle-shaped and round stromal cells. Furthermore, in colonic epithelium, tissue inhibitor of metalloproteinase-3 and type IV collagen protein were similarly concentrated in the basal region. CONCLUSIONS: These data provide the first detailed description of the cellular expression of tissue inhibitor of metalloproteinase-3 in colorectal cancer and identify it as a basement membrane-associated protein. This is an important observation, because the presence of tissue inhibitor of metalloproteinase-3 protein near the basement membrane supports its role in preventing proteolytic degradation, angiogenesis, and apoptosis.

Adenocarcinoma↗

PubMed2001

Highly efficient expression of rabbit neutrophil peptide-1 gene in Chlorella ellipsoidea cells.

A highly efficient system was developed for the expression of foreign genes in Chlorella ellipsoidea cells. The effect of five promoters on the expression efficiency of beta-glucuronidase (GUS) gene was evaluated by transient expression of the UidA gene. Among these promoters, Ubiquitin-omega was found to be the most efficient and was selected to drive the expression of foreign genes in Chlorella cells. A gene encoding the mature rabbit neutrophil peptide-1 (NP-1) was introduced into the cells. Integration of the gene for NP-1 into the Chlorella genome was confirmed by PCR and Southern blot analysis. In, vitro anti-microbial testes demonstrated the expression of biologically active NP-1 by the transgenic Chlorella cells.

Animals↗

PubMed2001

The potent antitumor effects of combined p16 gene and GM-CSF gene therapy through efficient induction of antitumor immunity.

PURPOSE: Tumor suppressor gene therapy and cytokine gene therapy have limited antitumor effects when used alone. Thus, in the present study, we investigated the antitumor potentials of the combined transfer of the p16 tumor suppressor gene and the murine granulocyte-macrophage colony-stimulating factor (GM-CSF) gene. METHODS: The adenovirus-harboring p16 gene (Adp16) and adenovirus-harboring GM-CSF (AdGMCSF) gene were utilized for the treatment of established tumors in vivo. The mice were inoculated s.c. with Renca renal carcinoma cells and 3 days later received an intratumoral injection of Adp16 in combination with AdGMCSF. RESULTS: The results demonstrated that tumor-bearing mice treated with Adp16 and Ad-GMCSF showed more potent inhibition of tumor growth and a prolonged survival period than mice treated with Adp16. AdGMCSF, adenovirus-expressing beta-galactosidase or PBS (P<0.01). Treatments of the mice with Adp16 alone or AdGMCSF alone also showed obvious antitumor effects as compared with those mice treated with PBS (P<0.05). After combined p16 and AdGMCSF gene therapy, the expression of H2Kd and Fas molecules on freshly isolated tumor cells increased markedly, and more CD(4)+ T cells and CD(8)+ T cells infiltrated in the tumor sites. The cytotoxicity of natural killer cells and specific cytotoxic T lymphocytes increased more significantly after the combined therapy. CONCLUSIONS: Our results demonstrated that combination p16 gene and GM-CSF gene therapy could inhibit the growth of established tumors in mice more significantly through efficient induction of antitumor immunity.

Adenoviridae↗