Transfection of cells with transforming growth factor-alpha leads to cellular resistance to the antiproliferative effects of tumor necrosis factor

Local intratumoral tumor necrosis factor-alpha and systemic IFN-alpha 2b in patients with locally advanced prostate cancer

To examine tolerability and activity of local, intratumoral tumor necrosis factor-alpha (TNF-alpha) and systemic interferon-alpha2b (IFN-alpha2b) in locally advanced, hormone-resistant prostate cancer (LA-HRPC), 10 patients with LA-HRPC (T4N x M0, n = 3, T4N x M1, n = 5; T4N1M1, n = 2) were treated with recombinant TNF-alpha injected locally into prostate tumor tissue at 4-week intervals (maximum of four cycles) combined with intermittent subcutaneous (s.c.) administration of 5 x 10(6) IU IFN-alpha2b. Twenty-nine TNF-alpha cycles were administered. Despite significant TNF-alpha leakage into the systemic circulation 2 h after intraprostatic application (from a mean of 9 to a mean of 416 pg/ml; p = 0.0034), TNF-alpha (and IFN-alpha2b) was well tolerated (WHO grade 1-2 toxicity), possibly because of its rapid neutralization by increasing soluble 55-kDa and 75-kDa TNF receptor levels in the serum (mean increase 268% and 91%, respectively) at the same time. TNF-alpha induced prostate tumor cell necrosis in all patients, leading to a significant reduction of prostate volume in 9 of 10 cases (mean 38%; p = 0.0025). The significant short-term increase of prostate-specific antigen (PSA) (mean 65%; p < 0.001), tissue polypeptide-specific antigen (TPS) (mean 85%; p = 0.001), and possibly interleukin-8 (IL-8) (mean 2687%; p < 0.009) serum levels within 4 h after TNF-alpha confirmed the cytotoxic effect in vivo. In the long term, serum PSA levels dropped by 18%-87%, reaching the nadir value 7 weeks after baseline. Objective responses of metastases were not seen. Intraprostatic administration of TNF-alpha is feasible at a tolerable toxicity in patients with LA-HRPC and, thus, may be a new treatment option for these patients.

TNF-induced signaling in apoptosis

Out of the almost 17 members of the TNF superfamily, TNF is probably the most potent inducer of apoptosis. TNF activates both cell-survival and cell-death mechanisms simultaneously. Activation of NF-kB-dependent genes regulates the survival and proliferative effects pf TNF, whereas activation of caspases regulates the apoptotic effects. TNF-induced apoptosis is mediated primarily through the activation of type I receptors, the death domain of which recruits more than a dozen different signaling proteins, which together are considered part of an apoptotic cascade. This cascade does not, however, account for the role of reactive oxygen intermediates, ceramide, phospholipases, and serine proteases which are also implicated in TNF-induced apoptosis. This cascade also does not explain how type II TNF receptors which lack the death domain, induce apoptosis. Nevertheless, this review of apoptosis signaling will be limited to those proteins that makeup the cascade.

Attenuation of acute lung injury in transgenic mice expressing human transforming growth factor-alpha

Transforming growth factor-alpha (TGF-alpha) is produced in the lung in experimental and human lung diseases; however, its physiological actions after lung injury are not understood. To determine the influence of TGF-alpha on acute lung injury, transgenic mouse lines expressing differing levels of human TGF-alpha in distal pulmonary epithelial cells under control of the surfactant protein C gene promoter were generated. TGF-alpha transgenic and nontransgenic control mice were exposed to polytetrafluoroethylene (PTFE; Teflon) fumes to induce acute lung injury. Length of survival of four separate TGF-alpha transgenic mouse lines was significantly longer than that of nontransgenic control mice, and survival correlated with the levels of TGF-alpha expression in the lung. The transgenic line expressing the highest level of TGF-alpha (line 28) and nontransgenic control mice were then compared at time intervals of 2, 4, and 6 h of PTFE exposure for differences in pulmonary function, lung histology, bronchoalveolar lavage fluid protein and cell differential, and lung homogenate proinflammatory cytokines. Line 28 TGF-alpha transgenic mice demonstrated reduced histological changes, decreased bronchoalveolar lavage fluid total protein and neutrophils, and delayed alterations in pulmonary function measures of airway obstruction compared with those in nontransgenic control mice. Both line 28 and nontransgenic control mice had similar increases in interleukin-1beta protein levels in lung homogenates. In contrast, interleukin-6 and macrophage inflammatory protein-2 levels were significantly reduced in line 28 transgenic mice compared with those in nontransgenic control mice. In the transgenic mouse model, TGF-alpha protects against PTFE-induced acute lung injury, at least in part, by attenuating the inflammatory response.

H441 pulmonary epithelial cell mitogenic effects and signaling pathways in response to HGF and TGF-alpha

Pulmonary epithelial cells are important in lung growth, development, and injury. H441 pulmonary adenocarcinoma cells may be a useful model for studying pulmonary epithelial cell growth factor responses in vitro. Isolated pulmonary epithelial type II cells proliferate in response to transforming growth factor (TGF)-alpha via the epidermal growth factor (EGF) receptor. Type II cells also proliferate in response to hepatocyte growth factor (HGF). In the present study, H441 cell responses to these growth factors were examined, and compared to type II cells. Both the EGF-R and the c-met proto-oncogene receptor, to which HGF binds, were immunoprecipitated from H441 cells. In H441 cells, addition of TGF-alpha resulted in phosphorylation of the EGF receptor and increased cell number and tritiated thymidine incorporation. Incubation with HGF resulted in phosphorylation of its c-met proto-oncogene receptor in type II and H441 cells, and also increased cell number and tritiated thymidine incorporation. Both HGF and TGF-alpha stimulated phosphorylation of the intracellular signaling molecules p42 and p44 mitogen activated protein kinases in H441 cells. H441 cells exhibited responses to mitogenic growth factors similar to type II cells and may be useful as a model for type II cell growth factor responses and signal transduction.

Transfection of cells with basic fibroblast growth factor and Kaposi fibroblast growth factor genes induce resistance to and receptor modulation of tumor necrosis factor

Tumor necrosis factor (TNF) has been shown to inhibit the growth of some cell types and stimulate the proliferation of others by a mechanism that is not understood. In the present study, we investigated the effect of transfection of NIH-3T3 cells with either the basic fibroblast growth factor gene (bFGF) or the kaposi FGF gene (K-fgf) on the growth-modulatory effects of TNF. Our results show that transformation of cells with either gene leads to resistance to the growth-inhibitory effects of TNF. The K-fgf gene was found to be a more potent inducer of cellular resistance than the bFGF gene. The cellular resistance correlated with the inhibition of TNF-induced activation of phospholipase A2 and down-modulation of TNF receptors. Overall, our results indicate that both K-fgf and bFGF play an important role in suppression of antiproliferative effects of TNF.

Suppression of antiproliferative effects of tumor necrosis factor by transfection of cells with human platelet-derived growth factor B/c-sis gene

The growth of cells is determined by the balance between growth-stimulatory and growth-inhibitory signals. In the present study, we demonstrate that the transfection of NIH 3T3 cells with a platelet-derived growth factor (PDGF-Blc-sis) gene induces resistance to the anticellular effects of tumor necrosis factor (TNF). Human tumor cell lines that express elevated levels of c-sis (e.g. epidermoid carcinoma, A-431) are also TNF resistant, whereas those that express no significant levels of this gene (e.g. breast adenocarcinoma, MCF-7) are TNF sensitive. Transfection of cells with the c-sis gene leads to down-modulation of TNF receptors and also a decrease in intracellular glutathione levels. Thus, our results demonstrate that over-expression of PDGF-Blc-sis by certain tumor cells can lead to their protection from the anticellular effects of TNF.