Local production of TGF beta1 inhibits cerebral edema, enhances TNF-alpha induced apoptosis and improves survival in a murine glioma model

Duality of Interactions Between TGF-β and TNF-α During Tumor Formation

The tumor microenvironment is essential for the formation and development of tumors. Cytokines in the microenvironment may affect the growth, metastasis and prognosis of tumors, and play different roles in different stages of tumors, of which transforming growth factor β (TGF-β) and tumor necrosis factor α (TNF-α) are critical. The two have synergistic and antagonistic effect on tumor regulation. The inhibition of TGF-β can promote the formation rate of tumor, while TGF-β can promote the malignancy of tumor. TNF-α was initially determined to be a natural immune serum mediator that can induce tumor hemorrhagic necrosis, it has a wide range of biological activities and can be used clinically as a target to immune diseases as well as tumors. However, there are few reports on the interaction between the two in the tumor microenvironment. This paper combs the biological effect of the two in different aspects of different tumors. We summarized the changes and clinical medication rules of the two in different tissue cells, hoping to provide a new idea for the clinical application of the two cytokines.

Therapeutic Targeting of TGFβ Ligands in Glioblastoma Using Novel Antisense Oligonucleotides Reduces the Growth of Experimental Gliomas

PURPOSE

Transforming growth factor (TGF)-β is expressed at high levels by glioma cells and contributes to the malignant phenotype of glioblastoma. However, its therapeutic targeting remains challenging. Here, we examined an alternative therapeutic approach of TGFβ inhibition using two novel phosphorothioate-locked nucleic acid (LNA)-modified antisense oligonucleotide gapmers, ISTH1047 and ISTH0047, which specifically target TGFβ₁ and TGFβ₂.

EXPERIMENTAL DESIGN

We characterized the effects of ISTH1047 and ISTH0047 on TGFβ_1/2 expression, downstream signaling and growth of human LN-308, LN-229, and ZH-161 cells as well as murine SMA-560 glioma cells in vitro. Furthermore, we assessed their target inhibition and effects on survival in orthotopic xenogeneic and syngeneic rodent glioma models in vivo.

RESULTS

Both antisense oligonucleotides specifically silenced their corresponding target and abrogated SMAD2 phosphorylation in several glioma cell lines. Moreover, inhibition of TGFβ₁ or TGFβ₂ expression by ISTH1047 or ISTH0047 reduced the migration and invasiveness of LN-308 and SMA-560 glioma cells. Systemic antisense oligonucleotide administration to glioma-bearing mice suppressed TGFβ₁ or TGFβ₂ mRNA expression as well as the expression of the downstream target PAI-1 in orthotopic gliomas. Glioma-bearing mice had significantly prolonged survival upon systemic treatment with ISTH1047 or ISTH0047, which was associated with a reduction of intratumoral SMAD2 phosphorylation and, in a fully immunocompetent model, with increased immune cell infiltration.

CONCLUSIONS

Targeting TGFβ expression with the novel LNA antisense oligonucleotides ISTH1047 or ISTH0047 results in strong antiglioma activity in vitro and in vivo, which may represent a promising approach to be examined in human patients with glioma.

Novel GM-CSF-based vaccines: One small step in GM-CSF gene optimization, one giant leap for human vaccines

Granulocyte macrophage-colony stimulating factor (GM-CSF) is a potent immunomodulatory cytokine that is known to facilitate vaccine efficacy by promoting the development and prolongation of both humoral and cellular immunity. In the past years we have generated a novel codon-optimized GM-CSF gene as an adjuvant. The codon-optimized GM-CSF gene significantly increased protein expression levels in all cells tested and helped in generating a strong immune responses against HIV-1 Gag and HPV-associated cancer. Here, we review the literature dealing with the adjuvant activity of GM-CSF both in animal models and clinical trials. We anticipate that the codon-optimized GM-CSF gene offers a practical molecular strategy for potentiating immune responses to tumor cell-based vaccinations as well as other immunotherapeutic strategies.

Limited role for transforming growth factor-β pathway activation-mediated escape from VEGF inhibition in murine glioma models

BACKGROUND

The vascular endothelial growth factor (VEGF) and transforming growth factor (TGF)-β pathways regulate key biological features of glioblastoma. Here we explore whether the TGF-β pathway, which promotes angiogenesis, invasiveness, and immunosuppression, acts as an escape pathway from VEGF inhibition.

METHODS

The role of the TGF-β pathway in escape from VEGF inhibition was assessed in vitro and in vivo and by gene expression profiling in syngeneic mouse glioma models.

RESULTS

We found that TGF-β is an upstream regulator of VEGF, whereas VEGF pathway activity does not alter the TGF-β pathway in vitro. In vivo, single-agent activity was observed for the VEGF antibody B20-4.1.1 in 3 and for the TGF-β receptor 1 antagonist LY2157299 in 2 of 4 models. Reduction of tumor volume and blood vessel density, but not induction of hypoxia, correlated with benefit from B20-4.1.1. Reduction of phosphorylated (p)SMAD2 by LY2157299 was seen in all models but did not predict survival. Resistance to B20 was associated with anti-angiogenesis escape pathway gene expression, whereas resistance to LY2157299 was associated with different immune response gene signatures in SMA-497 and GL-261 on transcriptomic profiling. The combination of B20 with LY2157299 was ineffective in SMA-497 but provided prolongation of survival in GL-261, associated with early suppression of pSMAD2 in tumor and host immune cells, prolonged suppression of angiogenesis, and delayed accumulation of tumor infiltrating microglia/macrophages.

CONCLUSIONS

Our study highlights the biological heterogeneity of murine glioma models and illustrates that cotargeting of the VEGF and TGF-β pathways might lead to improved tumor control only in subsets of glioblastoma.

Pilot Trial of FANG Immunotherapy in Ewing's Sarcoma

We report on 12 consecutive patients with advanced/metastatic Ewing's sarcoma who were treated as a separate cohort of a phase 1 trial of FANG autologous immunotherapy (1 × 10(6)-2.5 × 10(7) cells/intradermal injection each month for minimum 4 months). Safety and clinical response were monitored. Patient immune response to unmodified autologous tumor cells was assessed by gamma interferon-enzyme-linked immunospot (γIFN-ELISPOT) assay using peripheral blood mononuclear cells from baseline (pretreatment) and multiple postvaccination time points. None of the 12 patients (47 vaccinations) developed grade 2/3/4 drug-related toxicity. Median product release granulocyte-macrophage colony-stimulating factor expression was 1,941 pg/10(6) cells, and TGFβ1and TGFβ2 knockdown were 99 and 100%, respectively. Eight patients were assessed for ELISPOT response to autologous tumor cells at baseline and all (100%) were negative. In contrast, follow-up ELISPOT response at month 1 or month 4 (one patient) after FANG was positive in all eight patients. One patient achieved a partial tumor response (38% tumor reduction, RECIST 1.1). The Kaplan-Meier estimated survival of these 12 patients at 1 year was 75%. In this phase 1 study in patients with Ewing's sarcoma, FANG immunotherapy was well tolerated, elicited a tumor-specific systemic immune response in all patients, and was associated with favorable 1-year survival. Further clinical testing is indicated.

Alcohol, phospholipase A2-associated neuroinflammation, and ω3 docosahexaenoic acid protection

Chronic alcohol (ethanol) abuse causes neuroinflammation and brain damage that can give rise to alcoholic dementia. Insightfully, Dr. Albert Sun was an early proponent of oxidative stress as a key factor in alcoholism-related brain deterioration. In fact, oxidative stress has proven to be critical to the hippocampal and temporal cortical neurodamage resulting from repetitive "binge" alcohol exposure in adult rat models. Although the underlying mechanisms are uncertain, our immunoelectrophoretic and related assays in binge alcohol experiments in vivo (adult male rats) and in vitro (rat organotypic hippocampal-entorhinal cortical slice cultures) have implicated phospholipase A(2) (PLA(2))-activated neuroinflammatory pathways, release of pro-oxidative arachidonic acid (20:4 ω6), and elevated oxidative stress adducts (i.e., 4-hydroxynonenal-protein adducts). Also, significantly increased by the binge alcohol treatments was aquaporin-4 (AQP4), a water channel enriched in astrocytes that, when augmented, may trigger brain (esp. cellular) edema and neuroinflammation; of relevance, glial swelling is known to provoke increased PLA(2) activities or levels. Concomitant with PLA(2) activation, the results have further implicated binge alcohol-elevated poly (ADP-ribose) polymerase-1 (PARP-1), an oxidative stress-responsive DNA repair enzyme linked to parthanatos, a necrotic-like neuronal death process. Importantly, supplementation of the brain slice cultures with docosahexaenoic acid (22:6 ω3) exerted potent suppression of the induced changes in PLA(2) isoforms, AQP4, PARP-1 and oxidative stress footprints, and prevention of the binge alcohol neurotoxicity, by as yet unknown mechanisms. These neuroinflammatory findings from our binge alcohol studies and supportive rat binge studies in the literature are reviewed.

TNF-alpha- and TRAIL-resistant glioma cells undergo autophagy-dependent cell death induced by activated microglia

The role of microglia, the brain resident macrophages, in glioma biology is still ill-defined. Despite their cytotoxic potential, these cells that significantly infiltrate the tumor mass seem to support tumor growth rather than tumor eradication. A proper activation of microglia anti-tumor activities within the tumor may provide a valuable additional arm of defense to immunotherapies against brain tumors. We herewith report a detailed characterization of (lipopolysaccharide and interferon-gamma)-induced anti-tumor activities of mouse primary microglia towards two TNF-alpha and TRAIL resistant glioma cell lines, in cell monolayer or spheroid cultures and in collagen-embedded tumor explants. Irrespective of the mouse strain, stimulated microglia secreted proteic factors that decreased proliferation and migration of these glioma cells and efficiently killed them. Death occurred specifically in glioma cells as demonstrated by the lack of toxicity of microglia supernatant towards primary cultures of astrocytes or neurons. Cell death was characterized by the early accumulation of acidic vesicles, phosphatidylserine exposure, appearance of double-membrane cytoplasmic vesicles, extensive zeiosis and a very late loss of DNA in cells that had lost membrane integrity. Inhibition of autophagosome formation efficiently protected glioma cells from death whereas caspase inhibition could only prevent DNA loss but not cytotoxicity. Death however, resulted from a blockade by microglia supernatant of the basal autophagic flux present in the glioma cells. These observations demonstrate that glioma cells resistant to apoptotic death ligands could be successfully and specifically killed through autophagy-dependent death induced by appropriately activated microglia.

Endothelial cell barrier impairment induced by glioblastomas and transforming growth factor beta2 involves matrix metalloproteinases and tight junction proteins

Gliomas, particularly glioblastoma multiforme, perturb the blood-brain barrier and cause brain edema that contributes to morbidity and mortality. The mechanisms underlying this vasogenic edema are poorly understood. We examined the effects of cocultured primary cultured human glioblastoma cells and glioma-derived growth factors on the endothelial cell tight junction proteins claudin 1, claudin 5, occludin, and zonula occludens 1 of brain-derived microvascular endothelial cells and a human umbilical vein endothelial cell line. Cocultured glioblastoma cells and glioma-derived factors (e.g. transforming growth factor beta2) enhanced the paracellular flux of endothelial cell monolayers in conjunction with downregulation of the tight junction proteins. Neutralizing anti-transforming growth factor beta2 antibodies partially restored the barrier properties in this in vitro blood-brain barrier model. The involvement of endothelial cell-derived matrix metalloproteinases (MMPs) was demonstrated by quantitative reverse-transcriptase-polymerase chain reaction analysis and by the determination of MMP activities via zymography and fluorometry in the presence or absence of the MMP inhibitor GM6001. Occludin, claudin 1, and claudin 5 were expressed in microvascular endothelial cells in nonneoplastic brain samples but were significantly reduced in anaplastic astrocytoma and glioblastoma samples. Taken together, these in vitro and in vivo results indicate that glioma-derived factors may induce MMPs and downregulate endothelial tight junction protein and, thus, play a key role in glioma-induced impairment of the blood-brain barrier.

Adenovirally delivered tumor necrosis factor-alpha improves the antiglioma efficacy of concomitant radiation and temozolomide therapy

PURPOSE

Treatment of malignant glioma involves concomitant temozolomide and ionizing radiation (IR). Nevertheless, overall patient survival remains poor. This study was designed to evaluate if addition of Ad.Egr-tumor necrosis factor (TNF), a replication defective adenovector encoding a cDNA for TNF-alpha, to temozolomide and IR can improve overall antiglioma effect.

EXPERIMENTAL DESIGN

The efficacy of combination treatment with Ad.Egr-TNF, IR, and temozolomide was assessed in two glioma xenograft models. Animal toxicity and brain histopathology after treatment were also examined. In addition, in an attempt to explain the antitumor interaction between these treatments, the activation status of the transcription factor nuclear factor-kappaB was examined.

RESULTS

Triple therapy (Ad.Egr-TNF, IR, and temozolomide) leads to significantly increased survival in mice bearing glioma xenografts compared with dual treatment. Fifty percent of animals treated with the triple regimen survive for >130 days. Pathologic examination shows that triple therapy leads to a complete response with formation of a collagenous scar. No significant change in myelination pattern is noted after triple therapy, compared with any double treatment. Treatment of intracranial glioma bearing mice with Ad.Egr-TNF and IR leads to cachexia and poor feeding that does not improve, whereas triple therapy results in less toxicity, which improves over 21 days. Both Ad.Egr-TNF and IR activate nuclear factor-kappaB, and temozolomide inhibits this activity in an inhibitor of kappaBalpha (IkappaBalpha)-independent manner.

CONCLUSION

This work shows that the addition of adenoviral TNF-alpha gene delivery to temozolomide and IR significantly improves antiglioma efficacy and illustrates a potential new treatment regimen for use in patients with malignant glioma.

LRRC4 inhibits glioblastoma cell proliferation, migration, and angiogenesis by downregulating pleiotropic cytokine expression and responses

Leucine-rich repeat C4 (LRRC4) has been shown to inhibit glioma cell proliferation, however, little is known about the mechanism(s) underlying the action of LRRC4. Here, we show that two glioblstoma U251 cell clones stably expressing LRRC4 were established. LRRC4 expression significantly inhibited the expression of some cytokines and their receptors determined by microarray and Western blot assays, and dramatically reduced cytokine-induced AP-1, NF-kB, and CyclinD1 activation in glioma cells. Furthermore, LRRC4 expression in glioma cells significantly downregulated spontaneous and cytokine-induced expression of K-RAS and phosphorylation of c-Raf, ERK, AKT, NF-kBp65, p70S6K, and PKC, suggesting that LRRC4 inhibited receptor tyrosine kinase (RTK) signaling pathways. Moreover, treatment with bFGF, IGF1, or IGF2 stimulated LRRC4(-/-), but not the LRRC4(+), glioma cell proliferation, indicating that LRRC4 mitigated cytokine-stimulated proliferation in glioma cells. In addition, treatment of LRRC4(-/-) glioma cells with EGF, IGF2, or PDGF promoted long distance mobilization, but induced little migration in LRRC4(+) glioma cells, suggesting that LRRC4 retarded cytokine-promoted glioma cell migration in vitro. Finally, human vessel endothelial cells (ECV304) treated with VEGF grew, aligned and formed hollow tube-like structures in vitro. In contrast, LRRC4(+) ECV304 treated with VEGF failed to form vessel-tube structures. Collectively, LRRC4 expression inhibited the expression of some growth factors, cytokines and their receptors, and the capacity of glioma cells responding to cytokine stimulation, leading to inhibition of glioma cell proliferation. Conceivably, induction of LRRC4 expression may provide new intervention for human glioma in the clinic.

Reverse association between high-altitude headache and nasal congestion

No evidence is available to show that nasal congestion is a manifestation of exposing an individual to high altitude and hypoxia. Since both nasal congestion and high-altitude headache are vasogenic, we explored whether there is a coincidence between these two symptoms. A prospective observational study was carried out on a cohort of 118 adults (>18 years old) in a mountain clinic at 3450 m. After 24 h of ascent, an interview was held to ask if each individual experienced acute mountain sickness symptoms (headache, etc.) and nasal congestion. Sixty-six (55.9%) individuals mentioned headache within 24 h after ascent and nasal congestion was reported by 34 (28.8%) individuals. There was a reverse association between headache and nasal congestion (P < 0.001). In conclusion, there is a reverse association between altitude headache and nasal congestion, probably as result of contradictory autoregulation effects or exaggerated sympathetic activity.

Increased expression of TGF-beta1 reduces tumor growth of human U-87 Glioblastoma Cells in vivo

The role that transforming growth factor beta1 (TGF-beta1) plays in influencing growth of glioma cells is somewhat controversial. To further understand the potential growth-regulatory effects of TGF-beta1,we constructed an animal astroglial tumor model by injecting either wild-type or virally transduced human U-87 glioblastoma cells into nude rat brains. Wild type U-87 cells produced very low amounts of TGF-beta1 and were highly tumorigenic. In contrast, U-87 cells transduced to express high levels of TGF-beta1 showed reduced tumor size in vivo, in a dose-dependent manner. This reduction in tumor size was not due to either decreased vascularity or increased apoptosis. To test whether TGF-beta1 overproduction inhibited tumor growth through an autocrine mechanism, the highest TGF-beta1 producing cells were then double transduced with a vector expressing the kinase-truncated type II TGF-beta receptor. Cells expressing high levels of truncated TGF-beta receptor were less sensitive to TGF-beta1 mediated growth inhibition in vitro and produced more aggressive tumors in vivo. The data suggest that the degree of tumorigenicity of the U-87 high-grade glioblastoma cell line may be associated with correspondingly low level of production of TGF-beta1. These results also would tend to support the possibility that TGF-beta1 may be useful in treating some high-grade gliomas.

Vaccines in cancer: GVAX, a GM-CSF gene vaccine

GVAX is a granulocyte-macrophage colony-stimulating factor (GM-CSF) gene-transfected tumor cell vaccine. Original work with GM-CSF as a recombinant DNA protein (Leukine) involved proliferative stimulation of macrophages and neutrophils for the purpose of reducing hematopoietic toxicity related to dose-intensive chemotherapy. Following US Food and Drug Administration approval of Leukine several years ago, extensive preclinical results have demonstrated an immunostimulatory effect related to GM-CSF gene when transfected into tumor cells and used as a vaccine (GVAX). Tumor regression and prolonged survival was demonstrated in animal models. Toxicology with GVAX indicated no adverse effects, which enabled further testing in cancer patients. A small number of responses were demonstrated in Phase I trials in immunosensitive cancer patients (renal cell carcinoma and melanoma). However, a series of dramatic complete and durable responses in advanced non-small cell lung cancer patients, demonstrated in recent clinical trials, have generated interest in further development of this vaccine in nontraditional cancer disease types. The rationale of GVAX development and a summary of clinical results are reviewed.

Effects of sulfur dioxide on apoptosis-related gene expressions in lungs from rats

Sulfur dioxide (SO2) is an air pollutant in densely populated areas as well as in areas polluted by coal-fired power plants, smelters, and sulfuric acid factories. In the present study, male Wistar rats were housed in exposure chambers and treated with 14.00+/-1.01, 28.00+/-1.77, and 56.00+/-3.44 mg/m3 SO2 for 6 h/day for 7 days, while control rats were exposed to filtered air in the same condition. The mRNA and protein levels of three apoptosis-related genes (p53 and bax are promoters of apoptosis, whereas bcl-2 is apoptotic suppressor) were analyzed in lungs using a real-time reverse transcription-polymerase chain reaction (real-time RT-PCR) assay and immunohistochemistry method, and caspase-3 activities were detected. The results showed that mRNA levels of p53 and bax were increased in a dose-dependent manner and at the concentrations of 28.00 and 56.00 mg/m3 SO2 the increases were significant (for p53: 1.23-fold at 28 mg/m3 and 1.39-fold at 56 mg/m3; for bax: 1.77-fold at 28 mg/m3 and 2.26-fold at 56 mg/m3, respectively), while mRNA levels of bcl-2 were decreased significantly (0.78-fold at 28 mg/m3 and 0.73-fold at 56 mg/m3) in lungs of rats exposed to SO2. Dose-dependent increase of p53 and bax proteins in the lungs was observed after SO2 inhalation, while decrease of bcl-2 protein levels was obtained using immunohistochemistry method. Caspase-3 activities were increased in lungs of rats after SO2 inhalation. These results lead to a conclusion that SO2 exposure can change the expression of apoptosis-related genes, and it suggests that SO2 can induce apoptosis in lung of rat and may have relations with some apoptosis-related diseases. Elucidating the expression patterns of those factors after SO2 inhalation may be critical to our understanding mechanisms of SO2 toxicity and helpful for the therapeutic intervention.

Expression of apoptosis-related genes in livers from rats exposed to sulfur dioxide

Sulfur dioxide (SO2) is a ubiquitous air pollutant that is present in low concentrations in the urban air, and in higher concentrations in the working environment. In the present study, male Wistar rats were housed in exposure chambers and treated with 14.00+/-1.01, 28.00+/-1.77 and 56.00+/-3.44 mg/m3 SO2 for 6 h/day for 7 days, while control rats were exposed to filtered air in the same condition. The mRNA and protein levels of three apoptosis-related genes (p53 and bax were promoters of apoptosis, whereas bcl-2 was apoptotic suppressor) were analyzed in livers using a real-time reverse transcription-polymerase chain reaction (real-time RT-PCR) assay and immunohistochemistry method. The results showed that mRNA levels of p53 and bax were increased in a dose-dependent manner and at the concentrations of 28.00 and 56.00 mg/m3SO2 the increases were significant (for p53: 1.30-fold at 28 mg/m3 and 3.43-fold at 56 mg/m3, for bax: 1.63-fold at 28 mg/m3 and 2.17-fold at 56 mg/m3, respectively), while mRNA levels of bcl-2 were decreased significantly (0.63-fold at 28 mg/m3 and 0.45-fold at 56 mg/m3) in livers of rats exposed to SO2. Dose-dependent increases of p53 and bax proteins in the livers were observed after SO2 inhalation, while decrease of bcl-2 protein levels was obtained using immunohistochemistry method. These results lead to a conclusion that SO2 exposure could change the expression of apoptosis-related genes, and it suggests that SO2 can induce apoptosis in liver of rat and may have relations with some apoptosis-related diseases. It is critical for our understanding of the mechanisms of SO2 toxicity and helpful for the therapeutic intervention to elucidate the expression pattern of those factors involved in apoptosis signaling pathway after SO2 inhalation.

Increased efficacy of an interleukin-12-secreting herpes simplex virus in a syngeneic intracranial murine glioma model

Long-term survivors of glioblastoma multiforme, the most common form of primary intracranial malignancy in adults, are extremely rare. Experimental animal models that more closely resemble human disease are essential for the identification of effective novel therapies. We report here an extensive analysis of the 4C8 glioma model to assess its suitability for evaluating novel type 1 herpes simplex virus (HSV-1) therapies of malignant glioma. We first determined that expression of major histocompatibility complex I and II and of alphavbeta3 in the 4C8 model was comparable to that seen in human glioma cells. Next, using a panel of Delta(gamma1)34.5 HSVs, we demonstrated that, in vitro, 4C8 cells were as sensitive as human glioma cells to both infection and lysis and that the 4C8 cells supported the production of foreign gene products. Replication competence of HSV was demonstrated in vitro. Finally, 4C8 intracranial gliomas were established in immunologically competent syngeneic B6D2F1 mice, treated by intratumoral injection of selected engineered HSVs, including the interleukin-12-expressing virus, M002. Survival data from these studies demonstrated that 4C8 cells in vivo are sensitive to both direct oncolysis and HSV-mediated interleukin-12 expression. Fluorescence-activated cell sorting analyses of immune-related infiltrating cells supported the concept that survival was prolonged in part because of antitumor actions of these cells. We conclude that the 4C8/B6D2F1 syngeneic glioma model is suitable for preclinical evaluation of HSV-based therapies and that M002 is a superior virus for the treatment of murine glioma in this model.

Expression of a soluble transforming growth factor-beta (TGFbeta) receptor reduces tumorigenicity by regulating natural killer (NK) cell activity against 9L gliosarcoma in vivo

Immunotherapy of gliomas has been forwarded as an attractive alternative to standard therapeutic modalities. Numerous observations indicate some therapeutic efficacy with this approach, but it is not curative in most reports. It is well established that gliomas suppress immune reactivity via a number of mechanisms, including expression CD95 ligand (CD95L), which induces apoptosis of immune effector cells, and secretion of immunosuppressive factors such as transforming growth factor-beta (TGFbeta). It has been hypothesized that abrogation of production or function of TGFbeta would improve immune reactivity to gliomas. To investigate this in a fashion that is translatable into clinical practice, we utilized a retroviral vector encoding a truncated, soluble form of the Type II receptor for TGFbeta (TFGbeta sr) and expressed it in the rat 9L gliosarcoma line (9L-TGFbeta sr). We then determined whether expression of TGFbeta sr affected in vitro sensitivity of 9L to lysis by immune effector cells, whether expression of TGFbeta sr affected tumorigenesis of 9L in vivo, and whether TGFbeta sr affected expression of immunity to 9L. In these experiments, we determined that 9L-TGFbeta sr was more susceptible than sham transfected 9L (9L-neo) to lysis by natural killer (NK) cells. We also determined that subcutaneously implanted 9L-TGFbeta sr was less tumorigenic than 9L-neo in syngeneic rats. Similarly, survival was extended by approximately 40% in rats given intracranial 9L-TGFbeta sr compared to 9L-neo. Finally, we determined that elimination of CD161+ cells resulted in comparable growth of 9L-neo and 9L-TGFbeta sr in vivo, indicating that NK or NK-like cells were responsible for the anti-tumor effects in this model.

Tumor necrosis factor-alpha induces neuronal death by silencing survival signals generated by the type I insulin-like growth factor receptor

Within the central nervous system, the proinflammatory cytokine tumor necrosis factor (TNF)-alpha is best characterized by its ability to directly foment signals of death. However, recent evidence suggests that TNF-alpha also promotes neurodegeneration through inhibition of a vital survival signal, insulin-like growth factor-I (IGF-I). By inhibiting essential components of the IGF-I survival response, such as phosphatidylinositol 3'-kinase (PI 3-kinase), low nontoxic concentrations of TNF-alpha indirectly trigger the death of neurons. We suggest that this inhibition of survival signaling is a pathophysiologically relevant action of TNF-alpha in the brain. This type of cross-talk by which vastly different receptors utilize shared intracellular substrates is potentially applicable to a broad number of receptors that are coexpressed on the same cell. The use of neuronal growth factors in the treatment of neurodegenerative diseases, such as cerebral ischemia and the AIDS dementia complex, may prove much more effective if the elevated expression of TNF-alpha in these disorders is neutralized.

Role of apoptosis and transforming growth factor beta1 in fibroblast selection and activation in systemic sclerosis

OBJECTIVE

We hypothesized that pathophysiologic events during the development of systemic sclerosis (SSc) may lead to selection and propagation of certain apoptosis-resistant fibroblast subpopulations. The aim of this study was to examine a possible role for apoptosis in fibroblast selection in SSc and the role of transforming growth factor beta1 (TGFbeta1).

METHODS

We compared SSc and normal fibroblasts for their susceptibility to anti-Fas-induced apoptosis and analyzed 2 models that might lead to fibroblast resistance to apoptosis in this process: long-term exposure to either anti-Fas or TGFbeta1.

RESULTS

SSc-derived fibroblasts were resistant to anti-Fas-induced apoptosis, showing 5.5 +/- 17.2% (mean +/- SD) apoptosis, compared with 32.1 +/- 14.0% among normal fibroblasts (P < 0.05). Anti-Fas-selected normal fibroblasts showed 9.0 +/- 3.7% apoptosis, compared with 21.6 +/- 5.9% for sham-treated cells, which is consistent with the elimination of apoptosis-susceptible subpopulations. Normal fibroblasts subjected to 6 weeks of TGFbeta1 treatment showed not only resistance to apoptosis, but also proliferation (118.5 +/- 35.4%), after anti-Fas treatment, compared with sham-treated cells (35.1 +/- 11.1% apoptotic cell death). TGFbeta1 treatment also increased the proportion of myofibroblasts (47% versus 28% in controls). Cultured SSc fibroblasts had a greater proportion of myofibroblasts (32-83%) than did normal fibroblasts (4-25%). We also examined the relationship between collagen gene expression and the myofibroblast phenotype in normal and SSc skin sections. Only 2 of 7 normal sections had alpha-smooth muscle actin (a-SMA)-positive cells (mean +/- SD score 0.29 +/- 0.49 on a scale of 0-3), but all SSc sections were positive for alpha-SMA, with a mean score of 1.90 +/- 0.88 for lesional and 1.50 +/- 0.71 for nonlesional sections. Scores for alpha1(I) procollagen messenger RNA (mRNA) in lesional skin (mean +/- SD 3.30 +/- 0.82 on a scale of 1-4) were significantly higher than in normal (1.43 +/- 0.79) or nonlesional (1.40 +/- 0.52) skin, but scores varied, and there was no correlation between collagen mRNA and alpha-SMA levels.

CONCLUSION

Our results show that resistance to apoptosis is an important part of the SSc phenotype. TGFbeta1 may play a role by inducing apoptosis-resistant fibroblast populations, and also by inducing myofibroblasts and by enhancing extracellular matrix synthesis.

Gene transfer technologies for malignant gliomas

Although early clinical gene therapy trials for recurrent central nervous system neoplasms showed the proof-of-principle, they did not fulfill the high expectations suggested by the preclinical experimental data. Insufficient distribution of vectors in human brain tumors and very low transduction efficiency require that we reevaluate gene transfer concepts for brain tumor treatment. Major steps to improve gene transfer into the central nervous system and the efficacy of gene therapy for malignant brain tumors include: 1) the design of more effective vector systems; 2) the development of new or improved prodrug/suicide systems, gene replacement approaches, or strategies targeting the immune response or tumor angiogenesis; 3) the study of new techniques to enhance delivery of genetic vectors into brain tumors and for monitoring gene delivery into tumors; and 4) assessment of the role of gene therapy as part of a combined treatment approach.