Eiji Ohmura

Transforming growth factor (TGF) - α in human milk

Abstract Transforming growth factor (TGF) - α and epidermal growth factor (EGF) were measured in human milk by means of homologous radioimmunoassay. As previously reported, EGF concentration in the colostrum was approximately 200 ng/ml and decreased to 50 ng/ml by day 7 postpartum. The value of immunoreactive (IR) -TGF- α was 2.2–7.2 ng/ml, much lower than that of EGF. In contrast to EGF, the concentration of IR-TGF-α was fairly stable during the 7 postpartum days. There was no relationship between the concentrations of IR-TGF-α and IR-EGF, suggesting that the regulatory mechanism in the release of the two growth factors is different. On gel-chromatography using a Sephadex G-50 column, IR-EGF appeared in the fraction corresponding to that of authentic human EGF, while 70%–80% of the IR-TGF-α was eluted as a species with a molecular weight greater than that of authentic human TGF-α. Although the physiological role of TGF-α in milk is not known, it is possible that it is involved in the development of the mammary gland and/or the growth of newborn infants.

Autocrine role of insulin-like growth factor (IGF)-I in a human thyroid cancer cell line

An established cell line (TC-cell, clone 78) derived from human thyroid papillary cancer cells was investigated for production of peptide growth factors. The cells had specific binding sites for insulin-like growth factor-I (IGF-I) and responded to this growth factor with increased proliferation. Culture medium conditioned by TC cells was found to contain insulin-like growth factor (IGF)-I and IGF-binding protein(s). Furthermore, reverse transcription-polymerase chain reaction revealed expression of IGF-I mRNA. When monoclonal antibody to IGF-I receptors (alpha IR3) was added, the growth of TC cells cultured in serum-free medium was significantly reduced. The growth rate of the cells was restored when the antibody was removed from the medium. These results strongly suggest that TC cells produce IGF-I, which is involved in the regulation of their own growth.

Basic fibroblast growth factor (FGF-2) in renal cell carcinoma, which is indistinguishable from that in normal kidney, is involved in renal cell carcinoma growth.

To investigate the role of basic fibroblast growth factor (FGF) in renal cell carcinoma growth, we have analyzed the expression of mRNA of basic FGF. In 7 of 15 cases, basic FGF mRNA level in renal cell carcinoma tissues was higher than that in corresponding normal tissues. However, the tumor-to-normal ratios of expression levels are chiefly less than 2.0 and, in 5 cases, are even less than 1.0. Furthermore, there was no correlation between the ratio and the clinical stage. In protein analysis, we could not find any difference between basic FGF extracted from renal cell carcinomas and that from normal kidney tissues in bioactivity, immunoreactivity, molecular weight and affinity to heparin. On the other hand, anti-basic FGF monoclonal antibody inhibited the growth of a renal cell carcinoma cell line, VMRC-RCW, and this inhibition was reversed by an extraphysiological amount of exogenous basic FGF (100 ng./ml.). These results suggest that basic FGF itself may have no pivotal role in renal cell carcinoma etiology but is involved in the growth of renal cell carcinomas in an autocrine manner.

Mechanism of inhibitory actions of minocycline and doxycycline on ascitic fluid production induced by mouse fibrosarcoma cells

Semisynthetic tetracyclines (TCNs) are used for the management of malignant pleural effusions as sclerosing agents. However, their precise mechanism of actions are uncertain. In the present study, the mechanism of inhibitory effects of minocycline (MINO) and doxycycline (DOXY), on the accumulation of ascitic fluid induced by mouse fibrosarcoma (Meth-A) cells were investigated using male mice. Meth-A cells inoculated intraperitoneally elicited 2.5-4 ml of bloody ascites 10 days after implantation. The production of ascitic fluid was suppressed in a dose-related manner by daily intraperitoneal injections of MINO or DOXY, whereas vehicle (normal saline with 0.01N HCl) did not exert a significant effect. The inhibitory activity of these two substances was quite similar; one mg/mouse of MINO or DOXY inhibited the accumulation of fluid by 87% and 84%, respectively. The survival rate of Meth-A-bearing mice treated with MINO or DOXY was higher than that of the controls. Macroscopic examination of the peritoneal cavity did not reveal any obvious effects, such as adhesions, in mice treated with either MINO or DOXY. In vitro studies showed that MINO and DOXY suppressed Meth-A cell growth with IC50s of 5 microM and 8 microM, respectively. Maximal suppression (95%) was achieved at MINO and DOXY concentrations of 25 microM. The above observations suggest that MINO and DOXY inhibit the accumulation of ascites by a direct effect on Meth-A cell growth. Therefore, it appears that TCNs injected into the pleural cavity to manage malignant effusions in man exert their activity, at least in part, by suppressing malignant cell growth.

Transforming growth factor - α activity in effusions: Comparison of radioimmunoassay and radioreceptorassay

Transforming growth factor-alpha (TGF-alpha) in pleural and peritoneal effusions was assayed by homologous radioimmunoassay (RIA) and radioreceptor assay (RRA) using human placental membrane. Effusions were obtained from 24 patients with and 17 patients without cancer. Most of the effusions were found to contain TGF-alpha by RIA and RRA, but immunoreactive epidermal growth factor (EGF) was not detected. Effusions were chromatographed on Bio-Gel P-60 with several peaks of TGF-alpha activity by both RIA and RRA. A discrepancy in the chromatographic pattern of TGF-alpha between RIA and RRa suggested the existence of EGF-like substances capable of binding to EGF receptors which lack immunoreactivity for EGF or TGF-alpha. The TGF-alpha concentration of the acetic acid-extracted malignant effusions assayed by RRA significantly exceeded the value obtained from benign effusions (17.0 +/- 8.7 vs. 9.2 +/- 6.3 ng/ml; mean +/- SD: p < 0.02). However, the concentrations obtained by RIA did not differ.