Establishment of a human glioma cell line bearing a homogeneously staining chromosomal region and releasing alpha- and beta-type transforming growth factors

Hyperthermia and chemotherapy using Fe(Salen) nanoparticles might impact glioblastoma treatment

We previously reported that μ-oxo N,N’-bis(salicylidene)ethylenediamine iron [Fe(Salen)], a magnetic organic compound, has direct anti-tumor activity, and generates heat in an alternating magnetic field (AMF). We showed that Fe(Salen) nanoparticles are useful for combined hyperthermia-chemotherapy of tongue cancer. Here, we have examined the effect of Fe(Salen) on human glioblastoma (GB). Fe(Salen) showed in vitro anti-tumor activity towards several human GB cell lines. It inhibited cell proliferation, and its apoptosis-inducing activity was greater than that of clinically used drugs. Fe(Salen) also showed in vivo anti-tumor activity in the mouse brain. We evaluated the drug distribution and systemic side effects of intracerebrally injected Fe(Salen) nanoparticles in rats. Further, to examine whether hyperthermia, which was induced by exposing Fe(Salen) nanoparticles to AMF, enhanced the intrinsic anti-tumor effect of Fe(Salen), we used a mouse model grafted with U251 cells on the left leg. Fe(Salen), BCNU, or normal saline was injected into the tumor in the presence or absence of AMF exposure. The combination of Fe(Salen) injection and AMF exposure showed a greater anti-tumor effect than did either Fe(Salen) or BCNU alone. Our results indicate that hyperthermia and chemotherapy with single-drug nanoparticles could be done for GB treatment.

The failure of current immunotherapy for malignant glioma. Tumor-derived TGF-beta, T-cell apoptosis, and the immune privilege of the brain

Human malignant gliomas are rather resistant to all current therapeutic approaches including surgery, radiotherapy and chemotherapy as well as antibody-guided or cellular immunotherapy. The immunotherapy of malignant glioma has attracted interest because of the immunosuppressed state of malignant glioma patients which resides mainly in the T-cell compartment. This T-cell suppression has been attributed to the release by the glioma cells of immunosuppressive factors like transforming growth factor-beta (TGF-beta) and prostaglandins. TGF-beta has multiple effects in the immune system, most of which are inhibitory. TGF-beta appears to control downstream elements of various cellular activation cascades and regulates the expression of genes that are essential for cell cycle progression and mitosis. Since TGF-beta-mediated growth arrest of T-cell lines results in their apoptosis in vitro, glioma-derived TGF-beta may prevent immune-mediated glioma cell elimination by inducing apoptosis of tumor-infiltrating lymphocytes in vivo. T-cell apoptosis in the brain may be augmented by the absence of professional antigen-presenting cells and of appropriate costimulating signals. Numerous in vitro studies predict that tumor-derived TGF-beta will incapacitate in vitro-expanded and locally administered lymphokine-activated killer cells (LAK-cells) or tumor-infiltrating lymphocytes. Thus, TGF-beta may be partly responsible for the failure of current adoptive cellular immunotherapy of malignant glioma. Recent experimental in vivo studies on non-glial tumors have corroborated that neutralization of tumor-derived TGF-beta activity may facilitate immune-mediated tumor rejection. Current efforts to improve the efficacy of immunotherapy for malignant glioma include various strategies to enhance the immunogenicity of glioma cells and the cytotoxic activity of immune effector cells, e.g., by cytokine gene transfer. Future strategies of cellular immunotherapy for malignant glioma will have to focus on rendering glioma cell-targeting immune cells resistent to local inactivation and apoptosis which may be induced by TGF-beta and other immunosuppressive molecules at the site of neoplastic growth. Cytotoxic effectors targeting Fas/APO-1, the receptor protein for perforin-independent cytotoxic T-cell killing, might be promising, since Fas/APO-1 is expressed by glioma cells but not by untransformed brain cells, and since Fas/APO-1-mediated killing in vitro is not inhibited by TGF-beta.

Immunolocalization of alpha-transforming growth factor in the developing rat mammary gland in vivo, rat mammary cells in vitro and in human breast diseases

Immunoreactive alpha-transforming growth factor (alpha-TGF) was shown by immunocytochemistry to be present in the rat mammary gland at various stages of development, the staining being most intense in mature myoepithelial cells. Alpha-TGF was also detected in the secretions of the mammary glands of pregnant and lactating rats. alpha-TGF in the extracts of rat mammary glands at each stage of development, and in several rat mammary cell lines and in culture medium in which they had been grown, was shown by Western blotting to consist primarily of a protein of molecular weight 50 kDa. The amount of this protein was greater in the mammary gland of the lactating rat than in resting or involuting glands. alpha-TGF was also found in some, but not all, human breast carcinomas, and in benign hyperplastic breast diseases.

Effect of endothelin-1 as growth factor on a human glioma cell line; its characteristic promotion of DNA synthesis

In addition to its powerful vasoconstrictive activity, endothelin-1 (ET-1) has been recognized to stimulate DNA synthesis in some cell lines. In this study, we confirmed the existence of ET-1 receptor in YKG-1 human glioma cells, and investigated its effect on DNA synthesis in YKG-1 for 6 consecutive days, comparing it with that of epidermal growth factor (EGF), platelet-derived growth factor (PDGF), and insulin-like growth factor-I (IGF-I). Scatchard analysis of the binding data revealed the presence of a single class of high-affinity binding molecule. The apparent dissociation constant (Kd) was 5.2 x 10(-9) M and the maximal binding capacity (B max) was 4.7 x 10(4) sites/cell. The percentage of non-cycling cells was initially more than 85%, and decreased to 55.40%, 24.22%, 11.50%, and 7.51% on days 1, 2, 4, and 6, respectively, after ET-1 stimulation. Although ET-1 reduces the fraction of non-cycling cells more slowly than other growth factors such as EGF, PDGF and IGF-I, it reaches the same level as the others by day 6. These results indicate that YKG-1 human glioma cells have ET-1 receptors and that ET-1 initiates a peculiar slow induction of DNA synthesis in these cells, suggesting that secondary factors might exist to accelerate the DNA synthesis in response to ET-1.

Urinary epidermal growth factor in patients with gliomas: significance of the factor as a glial tumor marker

Epidermal growth factor (EGF) content in urine from patients with glial tumors was examined by radioimmunoassay techniques with labeled human EGF and its rabbit EGF polyclonal antibody. There was no cross-reaction with transforming growth factor-alpha, which has a common receptor with EGF. Forty glial tumors were divided into three groups according to the clinical stage: Samples from Group A patients were obtained before therapy and/or after biopsy; in these patients a large volume of tumor was apparent on computerized tomography (CT). Group B samples were obtained after gross total removal of the tumor and/or chemo- and radiation therapy; these patients showed a small volume of residual tumor on CT. Samples from Group C patients were obtained after gross tumor total removal and/or chemo- and radiation therapy; no tumor was detected on CT scans in these patients. Urinary EGF levels in Group A samples were statistically significantly higher than in samples from healthy individuals (p < 0.001), Group B patients (p < 0.10), and Group C patients (p < 0.02). In addition, high-grade glial tumors in Group A cases showed a significantly higher level of urinary EGF than low-grade tumors in Group A patients (p < 0.05), or patients with meningioma (p < 0.02), metastatic brain tumor (p < 0.05), and cerebral infarction (p < 0.001). Longitudinal changes of urinary EGF levels in glioma patients mostly synchronized with the clinical course and therapeutic interventions. Therefore, urinary EGF, as a glial tumor marker, may be of practical value for diagnosing a malignant glioma and evaluating for the efficacy of chemo- and radiation therapy.

Transforming growth factor-alpha, epidermal growth factor receptor, and proliferating potential in benign and malignant gliomas

Surgical specimens from six benign and 16 malignant human gliomas were investigated immunohistochemically to correlate the degree of malignancy, the distribution of transforming growth factor-alpha (TGF-alpha) and epidermal growth factor (EGF) receptor, and the potential for cell proliferation using monoclonal antibodies to TGF-alpha, EGF receptor, and Ki-67. Fourteen (88%) of the malignant gliomas and one (17%) of the benign gliomas were found to be positive for TGF-alpha, and 14 (88%) of the malignant gliomas and two (33%) of the benign gliomas expressed EGF receptor. The proliferation index with Ki-67 was 18.8% +/- 8.1% (mean +/- standard deviation) in malignant gliomas and 1.9% +/- 1.8% in benign gliomas. In general, cells positive for EGF receptor and Ki-67 were randomly distributed throughout the tumor tissue, and cells positive for TGF-alpha tended to be clustered without obvious relationship to areas of necrosis or blood vessels. In some tumors, cells positive for TGF-alpha, EGF receptor, and Ki-67 were associated in a focal distribution. The more frequent expression of TGF-alpha and EGF receptor in the highly proliferative malignant gliomas is compatible with a role for TGF-alpha and EGF receptor in the induction or stimulation of malignant gliomas.