Immunological detection and quantitation of alpha transforming growth factors in human breast carcinoma cells

Abstract

Alpha transforming growth factors (alpha TGFs) were immunologically detected in the concentrated conditioned medium (CM) prepared from four human breast cancer cell lines and from primary cultures of human mammary epithelial cells, and in the tissue extracts prepared from normal, benign, and malignant breast biopsies. Immunoreactive alpha TGFs were quantitated by a competitive radioimmunoassay (RIA) using affinity-purified polyclonal sheep anti-rat alpha TGF antibodies which react with human alpha TGF but not with human epidermal growth factor (EGF). The relative level of RIA-detectable alpha TGFs in the CM from the breast cancer cell lines MCF-7, ZR-75-1, T47-D, and MDA-MB-231, and from the CM of primary cultures of human mammary epithelial cells, ranged from 0.02 to 0.85 ng/ml. MCF-7 or ZR-75-1 cells grown in the presence of 17 beta-estradiol (10(-8) M) for 48 h were found to release two- to three-fold more alpha TGFs into their CM than the same cells grown in the absence of estrogen. In detergent extracts prepared from normal breast tissue, a benign fibrocystic lesion, fibroadenomas and primary breast carcinomas, the relative alpha TGF concentrations were found to range from 1.5 to 6 ng/mg cell protein. No significant correlations were found between the alpha TGF levels and the pathological state of the tissues, the estrogen receptor status of the tumors, or the relative amounts of the ras gene protein p21ras in the tissues as determined by Western immunoblot analysis. The question of biological relevancy of alpha TGF for human mammary tumors will require further studies on synthesis and turnover of alpha TGF, the relationship between immunoreactivity and biological activity of alpha TGF, and differences in biological responsiveness of mammary tumor cells.

Transformation of mouse mammary epithelial cells with the Ha‐ras but not with the neu oncogene results in a gene dosage‐dependent increase in transforming growth factor‐α production

“…In this respect, TGFcr binds to the EGF receptor (c-erbB) and activates the EGF receptor tyrosine kinase [1,2]. Elevated levels of TGFcr have been found in a number of rodent and human breast carcinomas [3][4][5][6]. TGFa expression can be enhanced by estrogens in estrogen-responsive rat and human breast tumor cell lines [4][5][6].…”

Production and response of a human prostatic cancer line to transforming growth factor-like molecules

“…Biologically active TGFaxs have been demonstrated in crude or partially purified extracts prepared from rodent and human mammary tumours and in the conditioned medium (CM) obtained from several human cell lines (Zwiebel et al, 1982;Brown & Blakely, 1984;Moses, 1984;Salomon et al, 1984Salomon et al, , 1986Dickson et al, 1986;Perroteau et al, 1986). In addition TGFa has been shown to be produced by the hormone responsive LNCaP prostate cell line (Wilding et al, 1989 (Stone et al, 1978) EGF radioreceptor assay Binding assays were carried out on DU145 monolayers, in 24-well plates (Cell-Cult) at a cell density of 2 x 105 cells per well.…”

Effect of Ovariectomy on Mammary Gland Expression of TGF.ALPHA. and EGFR mRNAs and its Relation to Mammary Gland Involution in Mice.

“…At 3 months of age, they were divided into two groups; the first group underwent a sham operation and served as the control. The ransforming growth factor α (TGFα) is a polypeptide which has been suggested to play T an important role in the growth of normal and abnormal mammary tissues [1][2][3][4][5][6]. TGFα relates structurally to epidermal growth factor (EGF) [7] and binds to epidermal growth factor receptor (EGFR) on the cell surface [8].…”