Detection of c-erbB-2 related protein in sera from breast cancer patients. Relationship to ERBB2 gene amplification and c-erbB-2 protein overexpression in tumour

Isolation of blood-borne epithelium-derived c-erbB-2 oncoprotein-positive clustered cells from the peripheral blood of breast cancer patients

Clinical studies including thousands of breast cancer patients have shown that c-erbB-2 is amplified and overexpressed in 20-30% of invasive human breast cancers and that it is associated with distant metastasis in specified patient subgroups. To isolate and characterize hematogeneously spreading c-erbB-2-positive epithelium-derived cells from the peripheral blood of breast cancer patients, a combined buoyant density gradient and immuno-magnetic separation method has been used. The method utilizes a biotinylated anti-cytokeratin monoclonal antibody (MAb) for capturing the epithelium-derived cells. The expression of c-erbB-2 by the captured cells was detected using an anti-c-erbB-2 rabbit antibody (21N) coupled to an anti-rabbit gold-labeled anti-body, whereby immunoenzymatic cytokeratin staining was performed using a silver-enhanced immunogold double staining protocol. In total, 29 of the 46 patients tested had either cytokeratin (24/29) or cytokeratin/c-erbB-2 (19/29) positive clustered cells in their peripheral blood. We thus report here the presence and the frequency of clone-specifically stained clustered cells in the peripheral blood of breast cancer patients. The frequency of cytokeratin/c-erbB2 double-positive clustered cells in the peripheral blood was on average 10 times higher than that of double-positive single cells. The numbers of cytokeratin/c-erbB-2 double-positive clustered cells were positively correlated with the stage of tumors. Results of in vitro motility experiments using single and clustered cells from primary breast cancer tissue strongly support the assumption that cytokeratin/c-erbB-2 double-positive clustered cells have a high potential for locomotion. We suggest that blood-borne epithelium-derived c-erbB-2-positive clustered cells are the possible precursor cells responsible for the formation of distant metastases and bone marrow micrometastases.

Molecular markers of carcinogenesis

The protein products of oncogenes and tumor suppressor genes play critical roles in the development of many cancers. The expression of a number of these proteins can be detected in extracellular fluids such as blood. This article reviews the literature on the application of methods for the detection of the proteins of oncogenes and tumor suppressor genes in the blood of humans with cancer or at risk for the development of cancer. The detection of these proteins in blood may be useful molecular markers of carcinogenesis that could play an important part in cancer diagnosis, prognosis, and prevention.

Influence of circulating c-erbB-2 serum protein on response to adjuvant chemotherapy in node-positive breast cancer patients

This retrospective case control study investigated the therametric value of the circulating c-erbB-2 gene product (Her-2, NEU) as (1) an eligibility criterion for high doses of chemotherapy and (2) response to standard adjuvant chemotherapy in node-positive breast cancer patients. Preoperative c-erbB-2 levels were measured in 211 locally advanced (> 3 nodes positive), pre- and perimenopausal breast cancer patients to determine if circulating levels of the gene product can assist in the determination of appropriate therapeutic options. 152 of 211 breast cancer patients received post-operatively a combination chemotherapy including the anthracycline analog mitoxantrone, while 59 patients were treated with conventional CMF therapy. Using 120 fmol/ml as a cut-off level, elevated c-erbB-2 values were found in 26 (12.3%) patients with locally advanced breast cancer. In univariate analysis significant survival differences were detected when c-erbB-2 'positive' patients were compared with c-erbB-2 'negative' patients. However, no significant survival differences were detected, when c-erbB-2 'positive' patients were compared according to regimen of adjuvant treatment. In multivariate analysis c-erbB-2 was an independent prognostic factor for predicting disease-free survival, but not for overall survival. High levels of c-erbB-2 were associated with low estrogen and progesterone receptor concentrations of the tumor cytosol. There was no correlation between elevated c-erbB-2 values and age, tumor size or degree of nodal involvement. c-erbB-2 was a better predictor of risk of recurrence than extent of nodal involvement or hormone receptor status.

Clinical applications of tumor suppressor genes and oncogenes in cancer

In the search for new ways to better diagnose and monitor cancer, scientists have turned to oncogenes and tumor suppressor genes. These genes are involved in cell differentiation, communication and proliferation and their alteration is frequently associated with cancer. Such alterations include mutations, translocations, amplifications and deletions. In this review, I give examples of using the detection of such alterations for patient diagnosis and monitoring. The practical examples are restricted to a few cancer types, but the identification of new tumor suppressor genes, like BRCA-1 and BRCA-2, is creating new possibilities for determining cancer risk of individual family members. There is no doubt that the cloning of new genes which predispose to sporadic cancer will lead to the introduction of widespread testing to assess risk and to the application of preventive measures.

Prognostic significance of serum c-erbB-2 protein in breast cancer patients

The tissue expression of c-erbB-2 protein in breast cancer is a marker of poor prognosis in a number of studies. More recently it has also been suggested that c-erbB-2 expression may predict response to systemic therapy in patients with advanced breast cancer. The measurement of c-erbB-2 protein in the serum of breast cancer patients has now been reported, but the significance of this finding is not clear. In this study an ELISA assay was used to measure c-erbB-2 in the sera of 23 normal controls, 46 benign breast disease patients, and 119 breast cancer patients. Elevated serum c-erbB-2 protein levels were detected in 13% (3/23) of normal controls, 15% (7/46) of benign disease patients, 15% (7/46) of Stage I/II patients, 26% (9/35) of Stage III patients, and 21% (8/38) of Stage IV patients. The tissue expression of the c-erbB-2 protein showed no association with detection of the serum c-erbB-2 protein (p = 0.31). In the 67 Stage III and IV patients who had assessable disease the presence of the c-erbB-2 protein in the serum bore no relationship to response to hormonal therapy (p = 0.71). Serum detection of the c-erbB-2 protein in Stage I/II patients predicted for a worsening of both survival outcome (p = 0.002) and disease free interval (p = 0.002). A worse outcome was also seen for the Stage III patients (p = 0.04) and Stage IV patients, although the latter did not reach statistical significance (p = 0.27). This study found that the presence of c-erbB-2 in the serum of breast cancer patients was of prognostic significance for all stages of disease.