transforming-growth-factor-beta and Neoplasm-Regression--Spontaneous

Microarray transcriptome study in cancer has been commonly used to investigate tumorigenic mechanisms. The unique growth pattern of spontaneous regression (SR) after progressive (P) growth in canine transmissible venereal tumor (CTVT) provides a valuable cancer model to study the genome-wide differences in samples between the two stages of growth. In this study, Affymetrix analysis was performed based on the canine genome to compare the gene expression profiles of CTVT P- and SR-phase tumors. A total of 459 (278 up-regulated and 181 down-regulated) genes were identified as being differentially-expressed during the SR phase by the 2-fold method. Further analysis of these genes revealed that the expression of three genes associated with IL-6 production -TIMD-4, GPNMB and PLTP - was significantly higher in SR-phase tumors than in P-phase tumors; these results were also confirmed by real time RT-PCR in tumor tissues of beagles. In addition, we found that Th17-related genes were over-expressed in the SR phase, suggesting autoimmune responses involvement in tumor regression. Although the interaction between CTVT and host immunity were partially investigated in previous studies, our results enable us to gain new insight into the genes and possible mechanisms involved in tumor regression and reveal potentially useful targets for cancer therapy.

Topics: Animals; Cell Differentiation; Dog Diseases; Dogs; Gene Expression Profiling; Gene Expression Regulation, Neoplastic; Interleukin-6; Neoplasm Regression, Spontaneous; T-Lymphocytes; Th17 Cells; Transforming Growth Factor beta; Venereal Tumors, Veterinary

We have shown previously that transforming growth factor-beta (TGF-beta) is a potent tumour suppressor in Smad4-deficient human malignant oral keratinocytes but the mechanism by which this occurs is unknown. In the present study, we show that over-expression of TGF-beta1 causes regression of tumours derived from Smad4-deficient oral keratinocytes transplanted orthotopically to athymic mice. Further, tumour regression is associated with the induction of apoptosis without changes in cell proliferation. In vitro, TGF-beta1 did not induce apoptosis directly in these cells but sensitized cells to cisplatin, but not Fas, -induced cell death. The data suggest that TGF-beta1 induces tumour regression in vivo by Smad4-independent pathways that sensitize keratinocytes to mitochondrial-mediated apoptosis.

Topics: Animals; Apoptosis; Cisplatin; DNA-Binding Proteins; Drug Synergism; Humans; Mice; Mice, Inbred BALB C; Mice, Nude; Mouth Neoplasms; Neoplasm Proteins; Neoplasm Regression, Spontaneous; Neoplasm Transplantation; Recombinant Proteins; Smad4 Protein; Trans-Activators; Transforming Growth Factor beta; Transforming Growth Factor beta1; Transplantation, Heterologous; Tumor Cells, Cultured

IL-6 is a multifunctional cytokine that regulates cell growth, differentiation, and cell survival. Many tumor cells produce TGF-beta1, which allows them to evade CTL-mediated immune responses. IL-6 antagonizes TGF-beta1 inhibition of CD3 cell activation. However, whether IL-6 restores NK activity, which also is suppressed by TGF-beta1, is not known. We used canine transmissible venereal tumor (CTVT), which produces TGF-beta1, as a model to determine whether IL-6 restores lymphokine-activated killer (LAK) activity. During the progression phase, CTVT cells stop expressing MHC molecules. During the regression phase, the number of surface MHC molecules increases dramatically on about one-third of tumor cells. Tumor cells that stop expressing MHC should be targeted by NK cells. In this study, we found that TGF-beta1 secreted by CTVT cells suppressed LAK cytotoxicity. Interestingly, tumor-infiltrating lymphocytes (TIL) isolated from regressing CTVT secrete high concentrations of IL-6 and antagonize the anti-LAK activity of tumor cell TGF-beta1. TIL also produce IL-6 during progression phase, but the concentration is too low to block the anti-LAK activity of TGF-beta1. There is probably a threshold concentration of IL-6 needed to reverse TGF-beta1-inhibited LAK activity. In addition, in the absence of TGF-beta1, IL-6 derived from TIL does not promote the activity of LAK. This new mechanism, in which TIL manufacture high concentrations of IL-6 to block tumor TGF-beta1 anti-LAK activity, has potential applications in cancer immunotherapy and tumor prognosis.

Topics: Adjuvants, Immunologic; Animals; Cell-Free System; Coculture Techniques; Cytotoxicity, Immunologic; Disease Progression; Dogs; Female; Interleukin-6; Intracellular Fluid; Killer Cells, Lymphokine-Activated; Lymphocyte Subsets; Lymphocytes, Tumor-Infiltrating; Male; Monocytes; Neoplasm Proteins; Neoplasm Regression, Spontaneous; RNA, Messenger; Suppressor Factors, Immunologic; Transforming Growth Factor beta; Transforming Growth Factor beta1; Tumor Cells, Cultured; Venereal Tumors, Veterinary

Several sexually transmitted viruses have been associated with the development of Kaposi's sarcoma (KS), a highly vascularized multi-focal neoplasm, characterized by the presence of spindle-shaped and endothelial cells, fibroblasts and macrophages. As BK virus (BKV) sequences were found in 100% of primary KS and 75% of KS cell lines, we established an experimental model to test whether BKV may be involved in the pathogenesis of KS. For this purpose, we transformed primary and spontaneously immortalized murine endothelial cells with BKV or with a plasmid containing BKV early region, which encodes BKV T antigen. Murine endothelial cells lost endothelial markers after transformation by BKV and, when inoculated s.c. in nude mice, induced tumors which regressed 7-30 days after onset, whereas spontaneously immortalized murine endothelial MHE cells induced progressing tumors, which brought the animals to death. Histologic examination showed an initial formation of vessels around the tumors, followed by the appearance of a dense population of fibroblasts and mononuclear cells in the peritumoral tissue. Subsequently, tumors appeared to be infiltrated by mononuclear cells and surrounded by a thick fibrous wall with scattered fibroblasts and without vessels. Areas of necrosis developed in the tumor mass and finally the neoplastic tissue completely degenerated. The medium conditioned by BKV-transformed cells induced proliferation and migration of human fibroblasts and NIH3T3 cells. These effects were inhibited by an anti-transforming growth factor-beta1 (TGF-beta1) antibody. Northern blot analysis revealed that BKV-transformed cells express a greater amount of TGF-beta1 RNA than normal murine endothelial cells. Besides, TGF-beta1 was not expressed in progressing tumors induced by spontaneously immortalized endothelial MHE cells, whereas it was highly expressed during the regression of tumors induced by BKV-transformed MHE and primary endothelial cells. Over-expression of TGF-beta1 may be responsible for the mononuclear cell infiltration, inhibition of angiogenesis and formation of the fibrotic wall around tumors, inducing tumor regression through tumor cell necrosis and nutritional starvation. These results prompt us to test whether production of TGF-beta1 is associated with spontaneous KS regression in human patients. In this case, KS regression could be induced or accelerated by any means that enhances TGF-beta1 production at the tumor site.

Topics: Animals; BK Virus; Cell Line, Transformed; Cell Transformation, Viral; Epithelial Cells; Leukocytes, Mononuclear; Male; Mice; Mice, Nude; Neoplasm Regression, Spontaneous; Neoplasm Transplantation; Neovascularization, Pathologic; Polyomavirus Infections; Sarcoma, Kaposi; Transforming Growth Factor beta; Transforming Growth Factor beta1; Tumor Virus Infections

We studied the changes of tumor size after gene therapy treatment and its relationship with the changes of vascular volume as measured by dynamic contrast-enhanced magnetic resonance imaging (MRI), to investigate whether the vascular changes is predictive of tumor regression. The study was carried out using a spontaneously regressing rat tumor model (C6 Glioma grown subcutaneously in rats). Three rats were treated with recombinant adenoviruses expressing three genes, mouse interleukin 1-alpha (IL1-alpha), mouse interferon gamma (IFN-gamma), and human transforming growth factor beta (TGF-beta), one from each kind. Two rats were treated with saline as controls. Longitudinal studies were performed to monitor the changes of tumor volume (based on T(2)-weighted images) and the vascular volume (based on dynamic contrast enhanced images). In untreated animals, tumor regression was preceded by several days with a decrease in vascular volume. When the tumor growth was perturbed by expression of mouse IL-1alpha, the increase in vascular volume was correlated with the continuing growth in size, and the decrease in vascular volume was predictive of the onset of tumor regression. As new advances in immunotherapy in cancer treatment emerge, the ability to determine the efficacy of therapy as early as possible will enable optimization of treatment regiments. The vascularity changes measured by dynamic MRI may provide a means to serve for this purpose.

Topics: Adenoviridae; Animals; Gadolinium DTPA; Genetic Therapy; Genetic Vectors; Glioma; Humans; Image Enhancement; Interferon-gamma; Interleukin-1; Liver; Longitudinal Studies; Magnetic Resonance Angiography; Mice; Microcirculation; Neoplasm Regression, Spontaneous; Neoplasm Transplantation; Neovascularization, Pathologic; Nonlinear Dynamics; Rats; Rats, Wistar; Recombinant Fusion Proteins; Recombinant Proteins; Remission Induction; Transforming Growth Factor beta; Tumor Cells, Cultured

The coexistence of tumor specific immunity with a progressing tumor remains a major paradox of tumor immunology. This enigma is most evident in partially regressing melanomas, where efficient eradication of tumor cells is closely linked to uncontrolled tumor growth. Mechanisms involved in this differential susceptibility of tumor cells to the host immune response may include altered production of immunosuppressive cytokines, i.e., transforming growth factor (TGF) beta or interleukin (IL) 10. Since only limited amounts of tissue samples are available from primary tumors, a semi-quantitative reverse transcriptase polymerase chain reaction (RT-PCR) was established which allowed to estimate the amount of cytokine mRNA expressed in a small number of melanoma cells segregated by indirect immunomagnetic isolation. Thereby, we determined the expression of TGF-beta 1 and IL-10 mRNA in melanoma cells obtained from regressing and progressing areas of 9 primary tumors. TGF-beta 1 mRNA could be detected in all undiluted samples from progressing areas and in 7 samples from regression zones. Titration of the sample revealed that in 6 cases TGF-beta 1 mRNA could be detected at a significant higher titer in progressing than in regressing areas. IL-10 mRNA was present in 8 samples obtained from progressing and in 7 samples from regressing tumor areas. In 6 tumors IL-10 mRNA was detectable at a higher titer in the progression zones. Specificity of the PCR amplification was confirmed with a series of restriction enzyme digestions of the resulting PCR product. Based on these findings the hypothesis that immunosuppressive cytokines, such as TGF-beta 1 or IL-10, represent important factors for the melanoma cells to escape immune surveillance is supported.

Topics: Disease Progression; Humans; Immune Tolerance; Immunologic Surveillance; Interleukin-10; Melanoma; Neoplasm Regression, Spontaneous; Reverse Transcriptase Polymerase Chain Reaction; RNA, Messenger; Skin Neoplasms; Transforming Growth Factor beta