transforming-growth-factor-beta and Gliosarcoma

Tenascin-C is an extracellular matrix protein known to correlate with prognosis in patients with glioblastoma, probably by stimulation of invasion and neoangiogenesis. Transforming Growth Factor-beta1 (TGF-beta1) plays an important role in the biology of high-grade gliomas, partly by regulating invasion of these tumors into parenchyma. This study was designed to evaluate if TGF-beta1 induces the expression and deposition of Tenascin-C in the extracellular matrix of high-grade gliomas which may be pivotal for the invasion of these tumors into healthy parenchyma.. A series of 20 high-grade gliomas was stained immunohistochemically with Tenascin-C- and TGF-beta1- specific antibodies. Expression levels of both proteins were evaluated and correlated with each other, time to progression and molecular and morphological markers of invasion. A quantitative PCR assay was performed evaluating the induction of Tenascin-C mRNA by treatment with TGF-beta1 in vitro.. Tenascin-C was expressed in 18 of 19 (95%) evaluable tumors, whereas 14 of 20 tumors (70%) expressed TGF-beta1 in a significant percentage of cells. Treatment with TGF-beta1 did induce the expression of Tenascin-C at the mRNA and protein level in vitro. The expression of Tenascin-C and TGF-beta1 did neighter statistically correlate with each other nor with time to progression.. In our series, Tenascin-C and TGF-beta1 were expressed in the vast majority of high-grade gliomas. We could not detect a correlation of one of the proteins with time to progression. Nevertheless, we describe induction of Tenascin-C by TGF-beta1, possibly providing a mechanism for the invasion of high-grade gliomas into healthy parenchyma.

Topics: Adult; Aged; Astrocytoma; Biomarkers, Tumor; Brain Neoplasms; Child; Disease Progression; Extracellular Matrix Proteins; Gene Expression Regulation, Neoplastic; Glioblastoma; Glioma; Gliosarcoma; Humans; Immunohistochemistry; Middle Aged; Neoplasm Invasiveness; RNA, Messenger; Tenascin; Time Factors; Transforming Growth Factor beta; Transforming Growth Factor beta1; Tumor Cells, Cultured

Like human gliomas, the rat 9L gliosarcoma secretes the immunosuppressive transforming growth factor beta (TGF-beta). Using the 9L model, we tested our hypothesis that genetic modification of glioma cells to block TGF-beta expression may enhance their immunogenicity and make them more suitable for active tumor immunotherapy. Subcutaneous immunizations of tumor-bearing animals with 9L cells genetically modified to inhibit TGF-beta expression with an antisense plasmid vector resulted in a significantly higher number of animals surviving for 12 weeks (11/11, 100%) compared to immunizations with control vector-modified 9L cells (2/15, 13%) or 9L cells transduced with an interleukin 2 retroviral vector (3/10, 30%) (P < 0.001 for both comparisons). Histologic evaluation of implantation sites 12 weeks after treatment revealed no evidence of residual tumor. In vitro tumor cytotoxicity assays with lymph node effector cells revealed a 3- to 4-fold increase in lytic activity for the animals immunized with TGF-beta antisense-modified tumor cells compared to immunizations with control vector or interleukin 2 gene-modified tumor cells. These results indicate that inhibition of TGF-beta expression significantly enhances tumor-cell immunogenicity and supports future clinical evaluation of TGF-beta antisense gene therapy for TGF-beta-expressing tumors.

Topics: Animals; Brain Neoplasms; Cytotoxicity, Immunologic; DNA, Antisense; Gene Expression; Genetic Therapy; Genetic Vectors; Gliosarcoma; Humans; Immunotherapy; Interleukin-2; Lymphocytes; Plasmids; Rats; Rats, Inbred F344; Retroviridae; Time Factors; Transforming Growth Factor beta