Epidermal growth factor receptor assay: validation of a single point method and application to breast cancer

Clinical Significance of Epidermal Growth Factor Receptor Content in Gastric Cancer

The objective of this work was to evaluate the epidermal growth factor receptor (EGFR) content in gastric cancer, its possible relationship with clinicopathological parameters of tumors and its prognostic significance. Membranous EGFR levels were examined by radioligand binding assays in 110 patients with gastric cancer. The mean follow-up period was 30.7 months. EGFR levels of tumors ranged widely, from 0.3 to 510 fmol/mg protein. EGFR levels were significantly higher (p<0.0005) in neoplastic tissue than in paired adjacent mucosa samples (median) (n= 84; 8.7 vs. 3.9 fmol/mg protein). Intratumoral EGFR levels were significantly correlated with tumor stage (p<0.05), and were higher in patients with stage III tumors (median) (7.6, 6.4, 12.3 and 7.5 fmol/mg protein for stages I, II, III and IV, respectively). In addition, the tumor/mucosa ratios of the EGFR content were significantly higher (p<0.05) in patients with stage III tumors (1, 1.8, 3.9, and 0.92, respectively). Although there was no significant relationship between EGFR levels of tumors and overall survival, the results suggest a role for EGFR in tumor progression of gastric cancer.

Epidermal growth factor receptor protein detection in head and neck cancer patients: a many-faceted picture

PURPOSE

Epidermal growth factor receptor (EGFR) overexpression is associated with poor prognosis in head and neck squamous cell carcinoma (HNSCC). Despite intensive biomarker studies, a consensual method for assessing EGFR protein expression is still lacking. Here we set out to compare three EGFR detection methods in tumor specimens from HNSCC patients.

EXPERIMENTAL DESIGN

Tumors were prospectively excised from a series of 79 high-risk HNSCC patients enrolled in a GORTEC-sponsored clinical trial. EGFR expression was determined using a ligand-binding assay on membranes, Western blotting (WB) on membranes and total homogenates, and immunohistochemistry (IHC) on tissue microarrays. In addition, phosphorylated EGFR (pEGFR) was measured by WB on membranes.

RESULTS

Distributions and ranges of tumor EGFR expression were method dependent. Moderate positive correlations (Spearman coefficient r ≈ 0.50) were observed between EGFR expression measured by the binding assay and WB or IHC. pEGFR levels positively and significantly correlated with total EGFR expression measured by WB or ligand binding, but not by IHC. The highest correlation (r = 0.85) was observed between EGFR and pEGFR levels, both measured by WB on membranes. Interestingly, the fraction of phosphorylated receptor (pEGFR/EGFR both measured by WB on membranes) significantly declined with increasing tumor EGFR expression, by all assessment methods used.

CONCLUSION

This study shows significant correlations between EGFR detection methods. The observed relationships between EGFR and pEGFR indicate that high-throughput pEGFR/EGFR analyses merit further investigations and consideration for routine use in patient samples.

Erlotinib in combination with capecitabine (5'dFUR) in resistant pancreatic cancer cell lines

The combination of capecitabine and the tyrosine kinase inhibitor erlotinib has recently been tested in patients with gemcitabine-refractory pancreatic tumors, with limited success. To understand this lack of efficacy, we studied the molecular effects of these agents in Capan-1 and Capan-2 human pancreatic resistant cancer cells. Erlotinib up-regulated thymidine phosphorylase (+50%) and downregulated dihydropyrimidine dehydrogenase (+55%) in a cell-dependent manner, thus suggesting that the combination should result in synergism. However, only mild additivity was achieved at best when combining both drugs, and several sequences tested even led to strong antagonism. Further experiments were performed to understand this lack of efficacy. We found that the fluoropyrimidine down-regulated EGFR expression by 30%, an unexpected finding resulting in a possible reduction in efficacy when cells were subsequently exposed to erlotinib. We also observed marked drug-induced over-expression of both cytosolic and extracellular vascular endothelial growth factor (VEGF) secretion, thus possibly triggering proliferation. These preliminary findings strongly suggest that these observations could be new mechanisms in the development of acquired drug resistance in pancreatic cancer cells.

Human epidermal growth factor receptor-2 family in colorectal adenocarcinoma: correlation with survival and clinicopathological findings

BACKGROUND AND PURPOSE

Erb-B1 (epidermal growth factor receptor, EGFR) and Erb-B2 (HER-2) are two of the best-characterized members in the EGFR pathway. In many tumor types, overexpression of these proteins is associated with enhanced malignant potential. The aim of this study was to determine the prognostic impact of EGFR and HER-2 protein expression on colorectal cancer.

METHOD

Immunohistochemistry was carried out in paraffin-embedded specimens of 115 colorectal carcinomas for the assessment of EGFR and HER-2 expression. Immunostaining for EGFR was graded negative, weak or strong according to extension and staining intensity. The results were correlated with traditional clinicopathologic parameters and patients' outcome.

RESULTS

The mean survival time was 64 (range 9-78) months in the EGFR-negative group, 166 (range 2-293) months in the group with a low EGFR expression, and 51 (range 4-71) months in the group with a high EGFR expression. The median survival time was 31 (range 2-114) months in the HER-2 negative group, and 30 (range 4-293) months in the HER-2 positive group. None of the clinicopathologic parameters or patient prognoses had statistically significant association with EGFR or HER-2 expression.

CONCLUSION

Conventional immunohistochemistry was unable to reveal any association between EGFR or HER-2 expression and outcome predicted by the biologic role of EGFR in tumor behavior and the established prognostic role of HER-2 in breast cancer.

Lymphatic and/or blood vessel invasion in gastric cancer: relationship with clinicopathological parameters, biological factors and prognostic significance

BACKGROUND

Lymphatic and/or blood vessel tumoral invasion (LBVI) is a common histopathologic finding of gastric carcinomas, which could make it an additional cost efficient marker and help in the detection of patients at risk for recurrence.

MATERIALS AND METHODS

The subjects of this study were 144 patients with primary gastric adenocarcinoma, who consecutively underwent surgery. LBVI was evaluated by H&E staining and complementary with immunohistochemical staining with anti-CD34. Intratumoral levels of EGFR were analyzed with a radioligand technique, whereas c-erbB-2 and tPA were determined by ELISA methods; pS2, cathepsin D and hyaluronic acid by immunoradiometric assays; and VEGFR-1 and -2 by immunohistochemical assays. The mean follow-up period for these patients was 33.1 months.

RESULTS

LBVI was present in 46 patients (31.9%). The presence of LBVI correlated significantly with tumor stage, lymph node involvement, surgical resectability, histological type and histological grade, being present in a higher percentage among II-IV tumor stage (P = 0.0001), poorly differentiated (P = 0.01), diffuse type (P = 0.009), R1-R2 (P = 0.002) and lymph node-positive (P = 0.005) tumors. In addition, statistical analysis demonstrated that LBVI was significantly associated with a poorer overall patients' survival in the univariate analysis (P = 0.0001) as well as in the multivariate analysis (P = 0.009). However, our results failed to show any significant relationship between LBVI and any of the intratumoral biological parameters studied.

CONCLUSION

LBVI provides additional useful information that could be applied to identify gastric cancer patients at risk for recurrence, who might be candidates for further adjuvant therapies.

EGFR in colorectal cancer: more than a simple receptor

BACKGROUND

Advances in the understanding of tumor biology have led to the development of targeted therapies allowing progress in colorectal cancer treatment. One of the most promising targets is the epidermal growth factor receptor (EGFR).

METHOD

The presence and distribution of high- and low-affinity EGFR was investigated retrospectively in a group of 82 colorectal cancer samples (43 normal colon-colon cancer paired samples) using a specific ligand binding assay (Scatchard Analysis).

FINDINGS

A large majority of tumor samples exhibited one class of high-affinity binding sites (78%). Eighteen cases (22%) exhibited both high- and low-affinity binding sites. A wide interpatient variability was observed for the site number, with physiologically-relevant high-affinity sites ranging from 7 to 310 fmol/mg protein in tumors and from 6 to 313 fmol/mg protein in normal mucosa. A significant positive correlation was demonstrated between tumor and normal mucosa for the high-affinity Kd values and for the number of high-affinity sites, suggesting a common regulation for both tumor and normal tissue.

INTERPRETATION

These observations (i) could explain recently-reported clinically-active EGFR targeting in colorectal tumors apparently negative for EGFR, and (ii) may offer a plausible explanation for the link observed between toxicity in normal tissue (cutaneous rash) and clinical outcome of patients treated with anti-EGFR drugs. Present data extends our understanding of EGFR identity in colorectal cancer which could be useful in reconsidering the predictive tools for the identification of tumors putatively responsive to EGFR targeted therapy.

Epidermal growth factor receptor signaling in colorectal cancer: preclinical data and therapeutic perspectives

Epidermal growth factor receptor (EGFR) belongs to a family of receptors known as the ErbB family (ErbB tyrosine kinase receptors) which comprises four proteins encoded by the c-erbB proto-oncogene. EGFR is known to activate a cascade of multiple signaling pathways that facilitate tumor growth process. EGFR has been shown to be overexpressed in colorectal cancer patient populations but its prognostic value in colorectal cancer progression remains unclear. The development of a panel of EGFR inhibitors could reduce the proliferation of tumor cells when used alone or in combination with cytotoxic drugs or radiation. This review focuses on the potential role of EGFR signaling in the survival of colorectal tumor cells and the possible modulation of such signaling pathways by EGFR inhibitors so as to increase tumor control or render tumor cells more sensitive to conventional therapy.

Prognostic impact of the epidermal growth factor receptor levels for patients with larynx and hypopharynx cancer

The aim of this study was to analyse prognostic factors for disease free interval (DFI) and overall survival (OS) among patients with larynx and hypopharynx cancer requiring a total laryngectomy. Three groups of patients were studied according to the type of treatment they received. Fifty-eight patients had total laryngectomy, 71 patients had organ preservation treatment including induction chemotherapy followed by exclusive radiotherapy, 26 patients received induction chemotherapy followed by salvage total laryngectomy. The studied potential prognostic factors were age, gender, performans status, primary tumor localization, T status, N status, tumor volume and tumoral EGFR level (fmol/mg protein). The multivariate analysis showed that both N status and tumor volume were significant for DFI and OS. EGFR level was significant only for patients treated by induction chemotherapy and exclusive radiotherapy (p = 0.05 and 0.05 for DFI and OS length, respectively). Among this group, patients with tumor EGFR levels lower and higher than 100 fmol/mg protein had 53% versus 22% and 51% versus 18% 5-year of DFI and OS rates, respectively (Log rank test: p = 0.001 and 0.0001). EGFR determination appears to be a powerful prognostic parameter for patients treated by induction chemotherapy followed by exclusive radiotherapy. Laryngectomy seems to erase the prognostic impact of EGFR expression. These results profile the use of EGFR targeting therapy for this category of patients.

Impact of EGFR expression on colorectal cancer patient prognosis and survival

BACKGROUND

Epidermal growth factor receptor (EGFR) is overexpressed in many types of cancers, especially colorectal cancer (CRC), and seems to reflect more aggressive histological and clinical behaviors. The aim of this study was to evaluate EGFR immunohistochemical reactivity in CRC biopsies, and to analyze its relationship with various histological and clinical characteristics and survival.

PATIENTS AND METHODS

A composite EGFR score, obtained by multiplying the grade (% positive cells) by the intensity of labeling (0-9) was used to define patients with low or high EGFR expression whose clinicopathological features were then compared. Univariate tests and multivariate Cox proportional hazards model were applied for data analysis.

RESULTS

Tissue sections from 150 CRC patients with a median follow-up of 40 months were examined. Median patient age at diagnosis was 70 years (range 38-89 years). EGFR reactivity was positive for 143 patients (97%) and high for 118 (80%). According to multivariate analysis, EGFR overexpression was significantly associated with tumor stage, with a higher percentage of EGFR overexpression in T3 than T4 (P=0.003) and not with overall survival.

CONCLUSIONS

EGFR was overexpressed in this CRC patient population and was significantly associated with TNM (tumor-node-metastasis) stage T3. In the context of a new therapeutic strategy using EGFR-targeted therapies, although EGFR remains a controversial prognostic factor, this expression-stage association may play a crucial role in a decision to initiate an adjuvant treatment.

Clinical significance of the epidermal growth factor receptor and HER2 receptor in resectable gastric cancer

BACKGROUND

Epidermal growth factor receptor (EGFR or HER1) and its homolog c-erbB-2 (HER2) are membrane receptors. Both EGFR and HER2 genes are overexpressed in a variety of solid human cancers and are related to poor prognosis of the patients. The objective of this work was to evaluate the EGFR and HER2 contents in resectable gastric cancer, their possible relationship with clinicopathologic parameters of tumors, and their prognostic significance.

METHODS

This was a prospective analysis of 63 patients with resectable gastric carcinomas, with a mean follow-up period of 40.7 months. Membranous EGFR levels were examined by radioligand binding assays, and cytosolic HER2 levels were examined by means of an immunoenzymatic assay.

RESULTS

There was a wide variability of EGFR (1-1,239 fmol/mg of protein) and HER2 (7-20,863 NHU/mg of protein) levels in tumors. There was no significant correlation between these levels and patient or tumor characteristics. However, high levels of EGFR and HER2 were significantly associated with a shorter overall survival period (P =.03 and P =.02, respectively).

CONCLUSIONS

There is a wide variability in membranous EGFR levels and in cytosolic HER2 levels in gastric cancer, which seems to be related to the biological heterogeneity of these tumors. In addition, high tumor EGFR and HER2 levels were associated with an unfavorable outcome in patients with resectable gastric cancer.

Direct effect of a gonadotropin-releasing hormone agonist on the growth of canine mammary tumour cells

Gonadotropin-releasing hormone (GnRH) agonist exert "in vivo" an inhibitory action on the growth of hormone-dependent canine mammary tumours (Lombardi et al. [1999] J. Vet. Pharmacol Ther. 22(1):56-61). The present experiments have been performed "in vitro" in order to investigate the mechanisms involved in this direct antiproliferative action of GnRH agonists. In particular, the aim was to study whether these compounds might exert their antiproliferative effect by interfering with the stimulatory action of epidermal growth factor (EGF). To this purpose, the effects of GnRH agonist, Goserelin (GnRH-A), on the mitogenic action of EGF, on EGF-activated intracellular signaling mechanisms (intracellular calcium and nitric oxide production) as well as on ATP induced cell proliferation and signalling, and on the binding of EGF receptors have been evaluated in primary culture of canine mammary tumour cells. The results of these "in vitro" studies show that GnRH-A counteracts the mitogenic action of EGF and ATP, decreases the EGF/ATP-induced calcium signalling and reduces EGF binding, probably by means of NO-induced [Ca2+]i downregulation. These data suggest that GnRH agonists may inhibit the proliferation of the tumour cells by interfering with the stimulatory action of EGF.

The relationship of epidermal growth factor receptor levels to the prognosis of unresectable pharyngeal cancer patients treated by chemo-radiotherapy

The aim of this study was to analyse prognostic factors for time to treatment failure (TTF) and overall survival (OS) in patients with unresectable cancer of the pharynx. A twice daily (b.i.d.) radiotherapy with concomitant cisplatin-5-fluorouracil chemotherapy was administered to 77 consecutive patients (68 males, 9 females; median age: 56 years). The studied factors were: age, gender, tumour differentiation, tumour volume, initial hemoglobin level, karnofsky index (KI), primary tumour location, T, N, epidermal growth factor receptor (EGFR) level in the tumour (fmol/mg protein). KI and EGFR level were significant predictors in a multivariate analysis for TTF (P=0.004 and P=0.0001) and OS (P=0.004 and P=0.0001). In order to select subgroups with different outcomes, a stratification of patients was performed based on the EGFR value: patients with tumour EGFR levels <35 fmol/mg protein, between 35 and 275 fmol/mg protein and >275 fmol/mg protein had 95%, 51% and 16% 3 year OS rates, respectively (log rank test; P=0.0001). Interestingly, for patients exhibiting a complete response (CR) after concomitant b.i.d. chemo-radiotherapy, patients with EGFR levels <35 fmol/mg protein were all alive at 3 years; in contrast, there was only 70 and 13% 3 year survival rates for patients with EGFR tumour levels between 35 and 275 fmol/mg protein and above 275 fmol/mg protein, respectively. EGFR determination appears to be a powerful prognostic parameter in unresectable pharyngeal cancer patients treated by concomitant chemo-radiotherapy.

Epidermal growth factor receptor expression in 780 breast cancer patients: a reappraisal of the prognostic value based on an eight-year median follow-up

PURPOSE

Because new therapeutic approaches target tumors expressing epidermal growth factor receptor (EGFR), the aim was to undertake a thorough analysis of the expression profile of EGFR in breast cancer and to reassess its prognostic value.

PATIENTS AND METHODS

Tumor EGFR levels were determined by a specific ligand binding assay in 780 consecutive breast cancer patients followed in our institute between 1980 and 1993. Mean age was 61 years (25-85 years). All patients had undergone tumor resection with axillary lymph node dissection: 373 patients (47.8%) underwent mastectomy, 37 (5%) subcutaneous mastectomy and 370 (47.2%) tumorectomy.

RESULTS

EGFR levels ranged between non-detectable up to 789 fmol/mg protein. EGFR median value was 9 fmol/mg protein and only a small proportion of patients exhibited a relatively marked EGFR expression. There was no link between tumor size, grade, node status and EGFR tumoral levels. There was a constant and significant decrease in EGFR tumoral levels according to patient age. A significant inverse relationship was found between estradiol receptors (ER) and EGFR. Median follow-up was 97 months with a minimum at 4 months and a maximum at 228 months. From univariate analysis it was found that histological grade, tumor size, node status and ER status were all significant predictors of survival, considering metastasis-free as well as overall survival. Using multivariable analysis, only histological grade, tumor size and node status remained independent predictors of survival.

CONCLUSION

EGFR determination is of limited value as a prognostic indicator in breast cancer.

Ovarian function suppression with a GnRH analogue: D-ser(But[t])[6]-Arzgly[10]-LHRH (Goserelin) in hormone dependent canine mammary cancer

Hormones and hormone level modifying substances have long been used to treat hormone-dependent tumours in humans. Recently, attempts have been made to use hormone manipulation regimens for the treatment of these tumours in veterinary medicine. The aim of the present study was to evaluate the activity of the luteinizing hormone-releasing hormone (LHRH)-agonist, D-ser(But[t])[6]-Azgly[10]-LHRH (Goserelin) in hormone-dependent mammary cancer in dogs. Eighteen female dogs with hormone-dependent mammary cancer (T2-T4, N0, M0 according to TNM clinical staging classification) were selected and allocated into two groups: nine dogs not treated with Goserelin (Group 1) referred to as control; and nine dogs treated with 60 microg/kg depot Goserelin every 21 days for 12 months (Group 2). Goserelin treatment decreased circulating levels of oestradiol and progesterone and reduced the size of mammary tumours; all the animals showed objective response (OR) to treatment after 3 months, and the relapse-free survival after 2 years was 88%. Haematology and blood chemistry parameters, measured every month from the beginning of treatment, as well as physical examination, showed that the drug was without toxic effects. This suggests that, at the dose administered, Goserelin blocks the hypothalamus-pituitary-ovary axis, and consequently can be useful to treat hormone-dependent mammary tumours in female dogs.

Effect of a cytotoxic analog of LH-RH (T-98) on the growth of estrogen-dependent MXT mouse mammary cancers: correlations between growth characteristics and EGF receptor content of tumors

Female BDF mice bearing estrogen-dependent MXT mouse mammary cancers were treated for 4 weeks with a cytotoxic analog of luteinizing hormone-releasing hormone (LH-RH). T-98 (agonist [D-Lys6]LH-RH linked to glutaryl-2(hydroxymethyl)anthraquinone). The effects of T-98 were compared to those of equimolar amounts of the cytotoxic moiety 2-(hydroxymethyl)anthraquinone hemiglutarate (G-HMAQ) and carrier LH-RH agonist [D-Lys6]LH-RH. Both T-98 and [D-Lys6]LH-RH significantly inhibited the growth of MXT cancers, but G-HMAQ had only a minor non-significant effect. Cytotoxic analog T-98 and the carrier [D-Lys6]LH-RH had similar inhibitory hormonal activities on the pituitary-gonadal axis, but T-98 caused a larger reduction in tumor volume and decreased proliferation characteristics such as mitotic activity and AgNOR numbers in tumor cells to a greater extent than the carrier. Tumor inhibition by T-98, [D-Lys6]LH-RH, and ovariectomy was connected with a significant decrease in binding capacity of EGF receptors in tumor cell membranes. The concentration of EGF receptors remained high in tumors that continued to enlarge in spite of treatment and in all control untreated tumors, even those of small size. Thus, the changes in EGF receptors are likely to be the result of the therapy. Treatment with T-98 caused a greater reduction in the binding capacity of EGF receptors in tumors than [D-Lys6]LH-RH. This could explain the higher inhibitory effect of the cytotoxic analog on tumor growth. Since radiolabeled T-98 was shown to accumulate in MXT cancers 3 hours after a subcutaneous injection, this indicates that specific targeting might play a role in the antitumor effect exerted by this cytotoxic analog.

Relationship between receptors for epidermal growth factor and steroid hormones in normal, dysplastic and neoplastic canine mammary tissues

The concentrations of receptors for epidermal growth factor (EGF-R), oestrogen (ER) and progesterone (PR) were measured in 108 samples from canine mammary tumours and 132 samples of normal mammary tissue removed surgically from 84 bitches. The history and clinical signs were also recorded. Binding sites of high affinity were detected in 70 per cent of both types of tissue and no significant variations in EGF-R concentrations or positivity were observed with the histology, location, size or number of mammary tumours or the age of the animal. A significant direct correlation (P = 0.002) was observed between the concentrations of ER and EGF-R only in malignant tumours. The concentrations of EGF-R were significantly correlated (P = 0.04) in normal mammary tissues adjacent to and distant from the lesions, but not between normal tissue and tumour tissue. No significant differences were observed in the expression of EGF-R in normal and neoplastic tissues from the same bitches. The direct correlation between the concentrations of EGF-R and ER in malignant tumours could be related to an oestrogen-dependent expression of EGF-R or to a similar pattern of regulation of the receptors.

Lack of prognostic value of epidermal growth factor receptor in a series of 229 T1/T2, N0/N1 breast cancers, with well defined prognostic parameters

The prognostic value of epidermal growth factor receptor (EGF-R) was prospectively assessed in a series of 229 clinical T1-T2, N0-N1 breast carcinomas diagnosed between May 1987 and October 1989. EGF-R expression was determined by measuring the specific Bmax of 125I EGF to tumor plasma membrane preparations. Tumor with a Bmax > or = 3 fmol/mg of protein were considered positive with regard to EGF-R expression. With a median follow-up of 34 months, the 3-year overall and disease-free survivals are respectively 92% and 88% for EGF-R < or = 3, and 91% and 86% EGF-R > 3 fmol, showing no significant difference, even when comparing axillary lymph node status. We did not succeed in finding an EGF-R cut-off value which might be significant in univariate analysis. Multivariate analysis of our data indicates that pT (p = 0.001), pN (p = 0.04), and Scarff-Bloom grade (p = 0.04) are the only significant predictors of disease-free survival among the parameters investigated in this study.

Analysis of epidermal growth factor receptor mRNA expression by polymerase chain reaction assay in 94 human breast adenocarcinoma tumors

It is well known that breast cancer cells can synthesize and secrete various growth factors that are able to stimulate tumor growth through autocrine and/or paracrine mechanisms. EGF is one of these growth factors involved in normal breast epithelial development and tumor proliferation. EGF and TGF alpha (EGF-like peptide) are produced in variable amounts and both bind to the EGF receptor (EGF-R). Previous investigation in the laboratory measuring free and occupied EGF-R sites by differential ligand binding assays had demonstrated that non-occupied and total binding sites were present in 54 and 90% of 216 breast tumor biopsies respectively. EGF-R appeared to be totally masked by endogenous ligand in 40 and 21% of estrogen receptor positive and negative tumors respectively. The aim of the present study was to check by a molecular method the expression of the EGF-R gene. The PCR method was applied to 94 tumor samples of the previous series. Total RNA was treated with 0.5 units of Rnase-free Dnase/mg of RNA to remove any contaminating DNA. We simultaneously reverse transcribed and amplified another transcript (beta-actin) as an internal standard. Both signals were present in 88 of the 94 samples while the presence of EGF-R was detected in 74 of them when assessed by radioligand assay. The findings indicate that 93% of the tumors analysed in this series expressed EGF-R mRNA, in agreement with our previous data on occupied EGF-R sites, i.e. two-fold more than by using the standard binding assay. No significant correlation was observed between the expression of the EGF-R gene and the estrogen receptor content.

Epidermal growth factor receptor in breast cancer: storage conditions affecting measurement, and relationship to steroid receptors

This study investigates the effect of freezing and storage of tissue and subcellular fractions on the measurement of epidermal growth factor receptors (EGF-r); compares competition binding and single saturating dose assays (SSD) for quantitating EGF-r levels; investigates several tissues as potential quality control; and examines the relationship between EGF-r and hormone receptor expression in human breast cancers. Mouse and calf uterine cell membranes were preferred sources of quality control tissue with similar levels of high affinity EGF-r to human breast cancer tissue (less than 150-200 fmol/mg membrane protein). Studies using pooled mouse uterine tissues indicated a loss of 40% in EGF-r activity following a single-20 degrees C freeze/thaw cycle, while a breast cancer tissue showed a 75% loss, independent of storage temperature (liquid nitrogen, -70 degrees C, -20 degrees C). A single freeze/thaw cycle of mouse uterine broken cell pellets (nuclei plus membrane fraction) again indicated a loss of EGF-r irrespective of storage temperature (43% loss at -70 degrees C, 52% loss at -20 degrees C). In most cases irrespective of the tissue type or tissue fraction being stored, the length of storage had little impact on the extent of the loss in activity. A second freeze/thaw cycle of intact tissue, or freezing of broken cell pellets from a previously-frozen tissue, led to a further major or total loss of the remaining EGF-r. Overall these results are commensurate with the published effects of freezing and storage on estrogen receptor measurement. In addition, our studies suggest that the most suitable procedure for assaying frozen breast cancer specimens for EGF-r levels in conjunction with steroid receptor quantitation is to prepare and assay both cytosol and membrane fractions for their respective receptor content without further storage. A concordance of 86% was found in 44 breast cancers assayed for EGF-4 by saturation analysis and SSD. Statistically significant inverse relationships were found between EGF-r and estrogen and progesterone receptor levels in the study of approximately 350 breast cancer patients. No association was found with tumor stage or diameter, axillary node involvement, or patient age.

Measurement of occupied and non-occupied epidermal growth factor receptor sites in 216 human breast cancer biopsies

The epidermal growth factor (EGF) is one of several growth factors involved in normal breast epithelial development and tumor proliferation. EGF and EGF-like peptide TGF alpha bind and activate the same membrane receptor protein. This receptor (EGF-R) has been recently studied in breast tumor biopsies and its detectability reported as a prognostic indicator. However, normal and tumor tissue themselves produce EGF and related peptides in variable amount. This suggests that the standard measurement of EGF-R by binding assay should reflect only the number of non-occupied receptor sites. Based on this observation, the presence of occupied sites (EGF-R2) has been assessed in 216 human mammary tumor biopsies simultaneously with the direct measurement of non occupied EGF receptor sites (EGF-R1) and the results compared to estrogen and progesterone receptor status (ER, PGR). EGF-R1 and EGF-R2 were evaluated by 2 separate (125I) EGF binding assays performed on 2 aliquots of tumor crude membrane fraction, the first one directly, the other after dissociation of the endogenously bound ligand. The validity of the method has been assessed on membrane fractions prepared from human placenta. It is shown that the dissociation does not modify the binding dissociation constant. ER and PGR were measured by the dextran coated charcoal method. Results greater than 10 fmol/mg of membrane or cytosol protein were considered as positive. It is found that EGF-R1 and EGF-R2 are detectable in 54 and 90% of the cases, indicating that EGF-R is masked by endogenous ligand in 36% of the tumors.(ABSTRACT TRUNCATED AT 250 WORDS)