EGF binding is quantitatively related to growth in node-positive breast cancer

Clinical relevance of transforming growth factor-beta 1 in the urine of patients with hepatocellular carcinoma

To assess the clinical relevance of transforming growth factor-beta 1 (TGF-beta 1) in the urine of patients with hepatocellular carcinoma (HCC), TGF-beta 1 was measured, by radioimmunoassay, in 140 patients with HCC, 50 cirrhotic patients, 30 patients with chronic active hepatitis, and 50 healthy controls. The results indicate that there were significantly increased urinary TGF-beta 1 levels in patients with HCC. Raised TGF-beta 1 levels were associated, in a dose-related fashion, with increased risk for development of HCC (odds ratio, 1.05, 95% confidence interval, 1.03-1.07). HCC patients with raised TGF-beta 1 levels had shorter survival than those with normal TGF-beta 1 levels (p = 0.038). TGF-beta 1 levels decreased after successful anticancer therapy (p < 0.0001). There was an inverse correlation between TGF-beta 1 and serum alpha-fetoprotein (AFP) (r = -0.199, p < 0.04). Receiver operating characteristics (ROC) curve analysis indicated that parallel determination of TGF-beta 1 and AFP significantly increased the sensitivity and diagnostic accuracy, with a high specificity. In conclusion, raised urinary TGF-beta 1 was associated with HCC development. It is a predictor of poor prognosis, and a tumor marker for diagnosis and therapeutic follow-up of HCC.

Analogs of alkyllysophospholipids: chemistry, effects on the molecular level and their consequences for normal and malignant cells

In the search for new approaches to cancer therapy, the first alkyllysophospholipid (ALP) analogs were designed and studied about two decades ago, either as potential immunomodulators or as antimetabolites of phospholipid metabolism. In the meantime, it has been demonstrated that they really act in this way. However, their special importance is based on the fact that, in addition, they interfere with key events of signal transduction, such as hormone (or cytokine)-receptor binding or processing, protein kinase C or phospholipase C function and phosphatidylinositol and calcium metabolism. There are no strict structural requirements for their activity. Differences in the cellular uptake or the state of cellular differentiation seem to be mainly responsible for higher or lower sensitivities of cells towards ALP analogs. Consequences of the molecular effects mentioned on the cellular level are cytostasis, induction of differentiation (while in contrast the effects of known inducers of differentiation such as 12-O-tetradecanoylphorbol-13-acetate are inhibited, probably as a consequence of protein kinase C inhibition) and loss of invasive properties. Already in sublytic concentrations, alterations in the membrane structure were observed, and lysis may begin at concentrations not much higher than those causing the other effects described. Few ALP analogs have already entered clinical studies or are in clinical use. ALP analogs are the only antineoplastic agents that do not act directly on the formation and function of the cellular replication machinery. Therefore, their effects are independent of the proliferative state of the target cells. Because of their interference with cellular regulatory events, including those failing in cancer cells, ALP analogs, beyond their clinical importance, are interesting model compounds for the development of new, more selective drugs for cancer therapy.

Clinical value of enzyme immunoassay of epidermal growth factor receptor in human breast cancer

Epidermal growth factor receptor (EGFr) levels were analyzed in 140 primary breast cancer specimens by immunohistochemical assay (ICA), competitive binding assay (BA), or enzyme immunoassay (EIA). Thirty-nine of 118 specimens (33.1%) were scored as positive by ICA, 30 of 116 (25.9%; cut-off level 10 fmol/mg protein) by BA, and 31 of 80 (38.9%: cut-off level 5 fmol/mg protein) by EIA. Agreement on EGFr status was 72.3% (68/94) between ICA and BA, 77.0% (57/74) between BA and EIA, and 73.8% (59/80) between EIA and ICA. These discrepancies are based on assay differences and the heterogeneous distribution of cancer cells within specimens. Regardless of the assay method used, EGFr status had a significantly negative correlation with estrogen receptor status. Although EGFr-ICA and BA status had no relationship with prognosis, patients with medium and high EGFr-EIA level tumors (over 5 fmol/mg protein) had shorter relapse-free periods than those with low level tumors. However, the prognostic value of positive EGFr-EIA status was weaker than that of c-erbB-2 overexpression.

Tyrosine kinase receptor--nuclear protooncogene interactions in breast cancer

In summary, evidence is beginning to accumulate in support of a major role for tyrosine kinase receptors (and their activating growth factors) and steroid hormones and their receptors in normal development and differentiation of the mammary gland. A point of intersection of their mechanisms of action in growth control appears to be the induction of nuclear protooncogenes such as c-myc. When c-myc is amplified, as it is in many breast cancers, EGF and FGF receptor tyrosine kinase action becomes transforming, not simply mitogenic. A source of the transforming factors could be either stromal or epithelial. This mechanism could function early in the progression of breast cancer. c-erbB-2 and EGF receptor overexpression and amplification, when they occur, appear to render tumors even more malignant and of especially poor prognosis. These mechanisms could function late in the progression of breast cancer. Transgenic mouse studies have begun to echo these themes. They have established that a growth factor (TGF-alpha) and its receptor (EGF receptor), which appear to be important in normal mouse and human proliferation and gland development, and a protooncogene (c-myc), commonly amplified and overexpressed in human and mouse breast cancer, can each contribute to mammary carcinogenesis. The mechanisms of the two are likely to be distinct. myc is likely to be acting as a tumor initiator in combination with normal proliferative factors, whereas TGF-alpha is likely to be acting as a hyperproliferative (promotional) factor in combination with a normal background of mutational events. The role of unmutated but amplified erbB-2 in the transgenic mouse is not yet known.

A new monoclonal antibody for detection of EGF-receptors in western blots and paraffin-embedded tissue sections

The prognostic significance of the epidermal growth factor receptor status (EGF-R-status) for certain human tumors requires the development of antibodies useful for clinical application. We used purified receptor preparations to generate monoclonal antibodies immunoreactive with the EGF-R purified from placenta membranes and A431 tumors. Four of the hybridomas contained antibodies (R2, R3, R5, and R9) which recognized both antigens. Antibody R3 was shown to display the following properties: it binds with a KD value of about 10(-9)-10(-10) M to the receptor, a half maximal inhibition of EGF-binding is achieved at 5 x 10(-8) M, and in Western blots of cell membranes R3 specifically detects the EGF-R at 0.1 micrograms/ml. R3 inhibits EGF-dependent clonogenic growth of NRK cells and completely blocks EGF stimulated autophosphorylation of the receptor. Moreover, R3 also detects EGF-R in paraffin-embedded tissue sections taken from human salivary gland, term placenta, and adult skin and mammary carcinomas. Thus, R3 can be used in retrospective diagnostic clinical studies and might help to develop new immunotherapeutic intervention.

Effects of growth factors on proliferation on basal and luminal cells in human breast epithelial explants in serum-free culture

A method of culturing human breast epithelium is described in which viable explants can be maintained in protein-free medium while retaining the capacity of responding to added hormones and growth factors for at least 7 days. Culture parameters were chosen to provide maximum sensitivity of detection of proliferative responses by autoradiography. Under basal conditions, the mean thymidine labeling index of the explants was 0.08%. After stimulation with insulin, hydrocortisone, and cholera toxin (I,H,CT), a combination known to stimulate proliferation in human breast epithelium in vitro, the mean labeling index was 15.7%. Stimulation of explants with epidermal growth factor (EGF) and transforming growth factor (TGF)-alpha resulted in mean labeling indices of 6.6 and 10.8%, respectively. Autoradiography at the ultrastructural level demonstrated that in I,H,CT-stimulated explants the majority of the labeled cells were luminal, with only 1.5% being basal cells. In contrast, after EGF and TGF-alpha basal cells accounted for 11.5 and 18.5% of the labeled population. These results indicate that this system provides an in vitro assay of proliferative activity in the normal human breast that enables comparisons to be made between both the luminal and the basal cells in the explants and their counterparts in monolayer culture prepared from flow sorted cells. Thus, growth responses dependent on cell-to-cell interactions or stromal modulation can be identified.

A meta-analysis of reported correlations between prognostic factors in breast cancer: does axillary lymph node metastasis represent biology or chronology?

A statistical overview of published results on correlations between various prognostic factors in breast cancer was undertaken. A distinction was made between clinical (or anatomical) prognostic factors--namely, axillary lymph node status and tumour size--and eight different biological prognostic factors. The latter included: tumour grade, oestrogen and progesterone receptor status, thymidine labelling index, DNA ploidy, S-phase fraction, epidermal growth factor receptor expression and c-erbB-2 gene amplification (or overexpression). 139 articles were eligible for review which reported a total of 432 individual correlations. A simple form of meta-analysis was employed: the counting method, in which the number of studies achieving a statistically significant correlation or not were counted. For each possible correlation examined, the proportion of studies showing a statistically significant correlation was calculated and an exact binomial 99% confidence interval determined for that proportion. If the 99% confidence interval included 5% (the proportion of correlations that would be expected to be statistically significant if the null hypothesis was true), it was taken as failing to exclude the null hypothesis of a zero correlation, while if it excluded 5% it was taken as rejecting the null hypothesis of a zero correlation. A broad agreement was found among published reports on the existence of a statistically significant correlation between the various biological prognostic factors in breast cancer. Of the 20 correlations examined, 18 had a 99% confidence interval excluding 5%, thus rejecting the null hypothesis of a zero correlation. On the other hand, a completely different result was obtained when reports on possible correlations between lymph node status and tumour size on the one hand and the eight biological prognostic factors on the other were analysed. Of the 16 correlations examined, 13 had a 99% confidence interval including 5%, failing to reject the null hypothesis of a zero correlation. These observations suggest the hypothesis that the prognostic influence of node status and tumour size cannot be explained by an analysis of the biology of breast cancer; and is compatible with the contention that axillary node status is merely a reflection of the relative chronological age of breast cancer.

Over-expression of the epidermal growth factor receptor in human breast cancer cells fails to induce an estrogen-independent phenotype

An association exists in primary human breast tumors between high epidermal growth factor receptor (EGFR) expression and a reduced number or even absence of estrogen receptors (ER). To determine whether an increase in EGFR expression might alter the estrogen responsiveness of an ER-positive human breast cancer cell line, ZR 75-1 cells were cotransfected with a plasmid containing the full-length cDNA for the human EGFR under the transcriptional control of the Harvey murine sarcoma virus (HaMSV) long terminal repeat (LTR) and with a pSV2neo plasmid. Two of the isolated G418-resistant clones were found to constitutively express EGFR levels 15- to 60-fold higher than those found on nontransfected ZR 75-1 cells. The EGFR in these clones were functionally normal since EGF could increase their autophosphorylation and since EGF could enhance the transphosphorylation of p185erbB-2. No change was seen in either the number or affinity of ER in these clones. In addition, the ability of estrogen to stimulate the anchorage-dependent and anchorage-independent growth of these clones was not significantly modified. These results suggest that an increase in EGFR expression alone is not sufficient to induce a hormone-independent phenotype in vitro in human breast cancer cells.

2,3,7,8-Tetrachlorodibenzo-p-dioxin inhibition of 17 beta-estradiol-induced increases in rat uterine epidermal growth factor receptor binding activity and gene expression

Treatment of immature female Sprague-Dawley rats with 17 beta-estradiol (5 micrograms/animal) resulted in an increase in uterine epidermal growth factor (EGF) receptor binding activity. Moreover, in a separate study it was also shown that 17 beta-estradiol increased steady-state levels of rat uterine EGF receptor mRNA as determined by Northern analysis. In contrast, 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) caused a dose-response decrease in constitutive rat uterine EGF receptor binding activity and this was paralleled by a decrease in steady-state levels of uterine EGF receptor mRNA. Cotreatment of the animals with both TCDD (16 nmol/kg) and 17 beta-estradiol (5 micrograms/rat) gave results which showed that TCDD significantly inhibited the estrogen-induced increases in rat uterine EGF receptor binding activity and EGF receptor mRNA levels. These results further extend the range of antiestrogenic properties of TCDD and suggest that the inhibition of growth factor expression may play a role in the growth-inhibiting properties of TCDD in estrogen-responsive tissues or cells.

Epidermal growth factor receptor in human breast cancer: correlation with cytosolic and nuclear ER receptors and with biological and histological tumor characteristics

Epidermal growth factor receptor (EGFr) and cytosolic (cER) and nuclear (nER) estradiol receptors were quantified in 220 primary breast cancers. The EGFr was significantly more frequent (chi 2 = 5.9; P less than 0.025) and its concentration was significantly higher (P less than 0.001) among ER- tumors than in ER+ tumors. There was a significantly greater proportion (chi 2 = 6.4; P less than 0.05) of node involvement in EGFr+/ER+ tumors than in EFGr-/ER+. Increases in the proportion of EGFr+ in ER- tumors are parallel to Scarff-Bloom scores (chi 2 = 6.1; P less than 0.05) and there is a significant trend (Spearman rs = 0.25; P less than 0.05) towards increased EGFr concentrations with histologic dedifferentiation. In ER+ tumors the median concentrations of EGFr in the different age groups show a linear correlation (LCC = 0.89; P less than 0.05) and follow a parallel profile with the medians of nER. These findings support the hypothesis that EGFr is a bad prognosis factor and suggest that EGFr expression and concentration in ER+ tumors might be considered an estrogenic action mediated through the binding of ER to their nuclear acceptors.