Hormonal regulation of c-erbB-2 oncogene expression in breast cancer cells

Does loss of hormonal receptors influence the pathophysiological characteristics of the HER-2 breast cancer phenotype?

BACKGROUND

Some breast carcinomas (BC) of the HER-2 type respond poorly to endocrine therapy, indicating that hormonal receptor (HR) status possibly impacts the biological criteria of this tumor class. The aim of this study was to compare the clinicopathological characteristics of HR-positive and HR-negative tumors occurring in HER-2 and non-HER-2 BC.

METHODS

Tissue microarray sections from 336 primary invasive BC specimens were stained immunohistochemically with antibodies against HER-2, ER, and PR. Proliferation was assessed using Ki67 and the P53 status was identified.

RESULTS

The HER-2 phenotype was identified in 42/336 (12.5%) specimens, while 293/336 (87.5%) were of the non-HER-2 phenotype. In the non-HER-2 group, 103/293 (35%) were HR-negative tumors. HR negativity was significantly associated with higher tumor grades (P < 0.0001), higher proliferation rates (P < 0.0001), presence of necrosis (P < 0.0001), and with a higher P53 expression (P < 0.0001). There were no differences in patient age, tumor size, LN status, or presence of vascular invasion (VI) between the HR-negative and HR-positive groups. In the HER-2 group, 16/42 (38%) had HR-negative tumors. No significant difference in clinicopathological characteristics, except for tumor grade, was detected between the HR-positive and HR-negative tumors in this group.

CONCLUSION

Loss of HR does not influence the biological features of HER-2 BC. This finding may indicate that some tumors will 'biologically' move from being HER-2-positive/HR-positive tumors to behaving more like HER-2-positive/HR-negative tumors even when ER are present on the cell surface. Further studies are needed to explore this hypothesis and to identify the subset of tumors that will benefit from endocrine therapy.

Association of estrogen receptor, progesterone receptor and HER2 following neoadjuvant systemic treatment in breast cancer patients undergoing surgery

AIMS

The aim of this study was to analyze the association between the status of estrogen receptor (ER), progesterone receptor (PR), and human epidermal growth factor receptor-2 (HER2) in breast cancer with neoadjuvant therapy by using tissue biopsy and surgical specimens.

METHODS

This study included 78 patients with breast cancer, who presented to our hospital between June 1999 and June 2011, and were treated with neoadjuvant therapy and subsequent mastectomy or partial mastectomy. All clinicopathological data regarding pre-neoadjuvant biopsy and definitive surgical specimens were reviewed for accuracy. The status of ER, PR, and HER2 was determined by immunohistochemistry.

RESULTS

Paired samples from 78 women (mean age 51.4 ± 11.7 years) were successfully analyzed. A switch in the status of ER was identified in 16 patients (20 %); PR, in 18 (23 %); and HER2, in 27 (35 %). There were no significant differences in the status of ER, PR, and HER2 between the primary tumor and the resected tumor after neoadjuvant therapy. Neoadjuvant therapy does not significantly influence the status of the steroid hormone receptors and the HER2 level in our study.

CONCLUSIONS

Initial biopsy may be reliable for determining the appropriate adjuvant therapy, but final pathology are still needed to evaluate the prognosis and provided the alternative treatment when tumor recurrence. Further prospective study is needed to optimize the care available for breast cancer patients.

Arecoline induced disruption of expression and localization of the tight junctional protein ZO-1 is dependent on the HER 2 expression in human endometrial Ishikawa cells

Background

Approximately 600 million people chew Betel nut, making this practice the fourth most popular oral habit in the world. Arecoline, the major alkaloid present in betel nut is one of the causative agents for precancerous lesions and several cancers of mouth among those who chew betel nut. Arecoline can be detected in the human embryonic tissue and is correlated to low birth weight of newborns whose mothers chew betel nut during pregnancy, suggesting that arecoline can induce many systemic effects. However, few reports exist as to the effects of arecoline in human tissues other than oral cancer cell lines. Furthermore, in any system, virtually nothing is known about the cellular effects of arecoline treatment on membrane associated signaling components of human cancer cells.

Results

Using the human Ishikawa endometrial cancer cell line, we investigated the effects of arecoline on expression, localization and functional connections between the ZO-1 tight junction protein and the HER2 EGF receptor family member. Treatment of Ishikawa cells with arecoline coordinately down-regulated expression of both ZO-1 and HER2 protein and transcripts in a dose dependent manner. Biochemical fractionation of cells as well as indirect immunofluorescence revealed that arecoline disrupted the localization of ZO-1 to the junctional complex at the cell periphery. Compared to control transfected cells, ectopic expression of exogenous HER2 prevented the arecoline mediated down-regulation of ZO-1 expression and restored the localization of ZO-1 to the cell periphery. Furthermore, treatment with dexamethasone, a synthetic glucocorticoid reported to up-regulate expression of HER2 in Ishikawa cells, precluded arecoline from down-regulating ZO-1 expression and disrupting ZO-1 localization.

Conclusion

Arecoline is known to induce precancerous lesions and cancer in the oral cavity of betel nut users. The arecoline down-regulation of ZO-1 expression and subcellular distribution suggests that arecoline potentially disrupts cell-cell interactions mediated by ZO-1, which may play a role in arecoline-mediated carcinogenesis. Furthermore, our study has uncovered the dependency of ZO-1 localization and expression on HER2 expression, which has therefore established a new cellular link between HER2 mediated signaling and apical junction formation involving ZO-1.

Identification of biology-based breast cancer types with distinct predictive and prognostic features: role of steroid hormone and HER2 receptor expression in patients treated with neoadjuvant anthracycline/taxane-based chemotherapy

Introduction

Reliable predictive and prognostic markers for routine diagnostic purposes are needed for breast cancer patients treated with neoadjuvant chemotherapy. We evaluated protein biomarkers in a cohort of 116 participants of the GeparDuo study on anthracycline/taxane-based neoadjuvant chemotherapy for operable breast cancer to test for associations with pathological complete response (pCR) and disease-free survival (DFS). Particularly, we evaluated if interactions between hormone receptor (HR) and human epidermal growth factor receptor 2 (HER2) expression might lead to a different clinical behavior of HR+/HER2+ co-expressing and HR+/HER2- tumors and whether subgroups of triple negative tumors might be identified by the help of Ki67 labeling index, cytokeratin 5/6 (CK5/6), as well as cyclooxygenase-2 (COX-2), and Y-box binding protein 1 (YB-1) expression.

Methods

Expression analysis was performed using immunohistochemistry and silver-enhanced in situ hybridization on tissue microarrays (TMAs) of pretherapeutic core biopsies.

Results

pCR rates were significantly different between the biology-based tumor types (P = 0.044) with HR+/HER2+ and HR-/HER2- tumors having higher pCR rates than HR+/HER2- tumors. Ki67 labeling index, confirmed as significant predictor of pCR in the whole cohort (P = 0.001), identified HR-/HER- (triple negative) carcinomas with a higher chance for a pCR (P = 0.006). Biology-based tumor type (P = 0.046 for HR+/HER2+ vs. HR+/HER2-), Ki67 labeling index (P = 0.028), and treatment arm (P = 0.036) were independent predictors of pCR in a multivariate model. DFS was different in the biology-based tumor types (P < 0.0001) with HR+/HER2- and HR+/HER2+ tumors having the best prognosis and HR-/HER2+ tumors showing the worst outcome. Biology-based tumor type was an independent prognostic factor for DFS in multivariate analysis (P < 0.001).

Conclusions

Our data demonstrate that a biology-based breast cancer classification using estrogen receptor (ER), progesterone receptor (PgR), and HER2 bears independent predictive and prognostic potential. The HR+/HER2+ co-expressing carcinomas emerged as a group of tumors with a good response rate to neoadjuvant chemotherapy and a favorable prognosis. HR+/HER2- tumors had a good prognosis irrespective of a pCR, whereas patients with HR-/HER- and HR-/HER+ tumors, especially if they had not achieved a pCR, had an unfavorable prognosis and are in need of additional treatment options.

Trial registration

ClinicalTrials.gov identifier: NCT00793377

Role of manganese superoxide dismutase on growth and invasive properties of human estrogen-independent breast cancer cells

Manganese superoxide dismutase (MnSOD) is known to play a role in cancer. MnSOD exerts a tumor suppressive effect in estrogen-dependent human breast cancer cells. In the present study we investigated the in vitro role of MnSOD in the growth of some aggressive and highly metastatic estrogen-independent breast cancer cells, i.e., MDA-MB231 and SKBR3 cells. We show that estrogen-independent cells expressed a significantly higher basal MnSOD level compared to estrogen-dependent human breast cancer cell lines (MCF-7 and T47D). For MDA-MB231 cells, the high-MnSOD level was accompanied by an overproduction of intracellular hydrogen peroxide (H2O2) and by a low expression of the major H2O2-detoxifying enzymes, catalase, and peroxiredoxin 3, compared to MCF-7 cells. Suppression of MnSOD expression by antisense RNA was associated with a decrease of H2O2 content and caused a stimulation of growth with a reduced cell doubling time but induced a decrease of colony formation. Furthermore, treatment of MDA-MB231 cells with H2O2 scavengers markedly reduced tumor cell growth and colony formation. In addition, MnSOD suppression or treatment with H2O2 scavengers reduced the invasive properties of MDA-MB231 cells up to 43%, with a concomitant decrease of metalloproteinase-9 activity. We conclude that MnSOD plays a role in regulating tumor cell growth and invasive properties of estrogen-independent metastatic breast cancer cells. These action are mediated by MnSOD-dependent H2O2 production. In addition, these results suggest that MnSOD up-regulation may be one mechanism that contributes to the development of metastatic breast cancers.

Co-expression of steroid receptors (estrogen receptor alpha and/or progesterone receptors) and Her-2/neu: Clinical implications

The response of breast cancer patients to endocrine therapy is guided by the expression of two steroid hormone receptors (HR): estrogen receptor alpha (ERalpha) and/or progesterone receptors (PR). In most laboratories the expression of these predictive markers is studied by immunohistochemistry (IHC) in the breast cancer biopsy samples. Another molecular marker that is being increasingly examined in breast cancer is the oncoprotein Her-2/neu, whose expression/amplification predicts the response to anti-Her-2/neu immunotherapy. The co-expression of HR with that of Her-2/neu is infrequent (most reports agree on this), however, there are some conflicting reports about the clinical implications in term of response to endocrine therapy in the patients that co-express HR and Her-2/neu. We have examined these molecular markers for a number of years in our tumor bank, in this dissertation we will present the method and cut-off to study these markers, the correlations between their expression, and the follow-up of the patients that received tamoxifen-based endocrine therapy, alone or following chemotherapy. We confirmed that the co-expression of HR with Her-2/neu is infrequent, and that these patients presented both a shorter disease free survival and overall survival. Our results will be compared with others related recently published. For example, the aromatase inhibitor anastrozole appears to be an effective endocrine treatment in HR+ patients, irrespective of the Her-2/neu status. We will present data on the molecular mechanisms that could explain the relatively poor outcome of these patients. Heregulin has been found to be a potent inducer of heat shock factor 1 (HSF1) activity and of heat shock protein (Hsp) synthesis in breast cancer cells and HSF1 activation plays a role in the tumorigenic changes induced by heregulin, heregulin exerts its tumorigenic changes through the cell surface tyrosine kinase receptors c-erbB-3 and c-erbB-4 which are able to form dimers with the "ligandless" Her-2/neu. We found that HSF1 associates with metastasis associated protein 1 (MTA1) on the promoters of genes as well as other molecules involved in gene repression (HDAC1, HDAC2) in a manner that is enhanced by either heregulin exposure or heat shock. ERs, although promoting the growth of breast cancer cells are less associated with invasion/metastasis and ER-induced gene expression is involve in this effect. Heregulin can overcome the protective effects of ER and at least a component of this appears to be due to MTA1 repression of ERE dependent transcription, HSF1 and MTA1 cooperate in gene repression. The co-expression of HSF1 and MTA1 was confirmed by IHC in human breast cancer biopsy samples.

Synergistic Interactions between Tamoxifen and Trastuzumab (Herceptin)

PURPOSE

HER-2/neu and estrogen receptor (ER) are critical in the biology of breast carcinoma, and both are validated therapeutic targets. Extensive interactions between the signaling pathways of these receptors have been demonstrated. This suggests that targeting both receptors simultaneously may have a dramatic effect on the biology of breast cancer. This hypothesis was tested in cell culture experiments.

EXPERIMENTAL DESIGN

ER-positive, HER-2/neu-overexpressing BT-474 human breast carcinoma cells were cultured in the presence of the anti-HER-2/neu therapeutic antibody trastuzumab (Herceptin), the antiestrogen tamoxifen, or both. The effects on cell growth, cell cycle distribution, clonogenicity, survival, and the level and activity of HER-2/neu were examined.

RESULTS

The combination of tamoxifen and Herceptin resulted in synergistic growth inhibition and enhancement of cell accumulation in the G(0)-G(1) phase of the cell cycle, with a decrease in cells in S phase. Clonogenicity was inhibited in the presence of each drug and more so by the combination, although prior exposure to drugs did not affect subsequent clonogenicity in drug-free media, and neither drug nor the combination induced apoptosis. Herceptin, but not tamoxifen, inhibited signaling by HER-2/neu.

CONCLUSIONS

The combination of tamoxifen and Herceptin is formally demonstrated to result in synergistic growth inhibition and enhancement of G(0)-G(1) cell cycle accumulation. In vitro, the individual drugs or combination produces a cytostatic effect. These results suggest that combined inhibition of ER and HER-2/neu signaling may represent a powerful approach to the treatment of breast cancer.

Intratumoural mRNA expression of genes from the oestradiol metabolic pathway and clinical and histopathological parameters of breast cancer

Introduction

The expression of the oestrogen receptor (ER) is one of the more important clinical parameters of breast cancer. However, the relationship between the ER and its ligand, oestradiol, and the enzymes that synthesise it are not well understood. The expression of mRNA transcripts of members of the oestradiol metabolic and signalling pathways including the ER was studied in detail.

Method

mRNA transcripts for aromatase (CYP19), 17-β-hydroxysteroid dehydrogenase I, 17-β-hydroxysteroid dehydrogenase II, ERα, ERβ, steroid sulfatase (STS), oestradiol sulfotransferase (EST), cyclin D₁ (CYCLD1) and ERBB2 were fluorometrically quantified by competitive RT-PCR using an internal standard in 155 breast carcinomas. In addition, the transcripts of CYP19 were analysed for alternative splicing/usage of exon 1 and an alternative poly A tail.

Results

A great variability of expression was observed, ranging from 0 to 2376 amol/mg RNA. The highest levels were observed for STS and EST, and the lowest levels (close to zero) were observed for the 17-β-hydroxysteroid dehydrogenase isoenzymes. The levels of mRNA expression were analysed with respect to clinical and histopathological parameters as well as for disease-free survival. High correlation of the mRNA expression of STS, EST and 17-β-hydroxysteroid dehydrogenase in the tumours suggested a common regulation, possibly by their common metabolite (oestradiol). Hierarchical clustering analysis in the 155 patients resulted in two main clusters, representing the ERα-negative and ERα-positive breast cancer cases. The mRNA expression of the oestradiol metabolising enzymes did not follow the expression of the ERα in all cases, leading to the formation of several subclasses of tumours. Patients with no expression of CYP19 and patients with high levels of expression of STS had significantly shorter disease-free survival time (P > 0.0005 and P < 0.03, respectively). Expression of ERβ mRNA was a better prognostic factor than that of ERα in this material.

Conclusion

Our results indicate the importance of CYP19 and the enzymes regulating the oestrone sulfate metabolism as factors of disease-free survival in breast cancer, in addition to the well-known factors ER and ERBB2.

Oestrogen Receptor-Mediated Modulation of the EGFR/MAPK Pathway in Tamoxifen-Resistant MCF-7 Cells

Oestrogen receptor (ER) levels are usually maintained on acquisition of tamoxifen resistance in the clinic, however, tumour re-growth is associated with increased expression of epidermal growth factor receptor (EGFR) and activation of the mitogen activated protein kinase (MAPK) pathway. In the present study we have used the ER down-regulator fulvestrant ('Faslodex') to investigate the influence of the ER on growth of a tamoxifen-resistant (TAM-R) human breast cancer cell line. Expression levels of ER mRNA and protein were equivalent in parental wild-type MCF-7 (WT) and TAM-R cells. Fulvestrant eliminated ER protein expression and inhibited proliferation in both cell lines. The growth inhibitory effects of fulvestrant were associated with a decrease in basal EGFR, c-erbB2 and ERK1/2 activity in TAM-R but not WT cells. ER functionality as determined by oestrogen response element (ERE)-luciferase reporter activity and expression of PgR, pS2 and transforming growth factor alpha (TGFalpha) was significantly reduced in TAM-R compared to WT cells and was further decreased by fulvestrant treatment in both cell lines. Epidermal growth factor (EGF) and TGFalpha significantly increased EGFR/MAPK pathway activity in both cell lines. Ligand-induced EGFR/MAPK activation promoted TAM-R cell growth in both the absence and presence of fulvestrant, whereas no proliferative activity was observed under the same conditions in WT cells. These results suggest that the ER modulates EGFR/MAPK signalling efficiency in TAM-R cells possibly through the regulation of TGFalpha availability. This effect may be overcome by the action of exogenous EGFR ligands, which strengthen EGFR/MAPK signalling activity to generate endocrine-insensitive cell growth.

Studies on the development of resistance to the pure antiestrogen Faslodex in three human breast cancer cell lines

In order to understand the mechanisms underlying the development of resistance to a pure antiestrogen we established three human breast carcinoma cell lines resistant to ZM 182780 (ZM) (Faslodex). Long-term cultivation of the ERalpha-positive, 17beta-estradiol (E(2))-responsive cell lines T47D, ZR-75-1, and MCF-7 with the pure antiestrogen ZM 182780 resulted in the T47D-r, ZR-75-1-r, and MCF-7-r cell lines, which proliferate continuously in the presence of 10(-6)M ZM 182780. The resulting antiestrogen-resistant cells grow equally well in medium with or without E(2) and in medium with or without ZM 182780 indicating that they are no longer estrogen-responsive. ERalpha expression was lost at the protein level in all three resistant cell lines. At the mRNA level, the ERalpha was only faintly detectable in T47D-r, whereas a weak signal was seen in ZR-75-1-r and MCF-7-r. By reverse transcription-polymerase chain reaction (RT-PCR) the ERbeta was detectable in the antiestrogen-sensitive and -resistant breast cancer cell lines, however, ZR75-1-r contained the smallest signal for ERbeta. In all three antiestrogen-resistant cells the PR was undetectable, whereas binding of epidermal growth factor (EGF) and protein expression of epidermal growth factor receptor (EGFR) were increased. To analyse alterations in the gene expression pattern in more detail Atlas arrays were hybridised with RNA isolated from T47D-r and T47D and the two Ca2+-binding proteins calgranulin A and B were found to be up-regulated in T47D-r compared to T47D. Calgranulin A and B were also both up-regulated in ZR-75-1-r and MCF-7-r compared to their antiestrogen-sensitive counterparts. Loss of ERalpha expression may be linked to the acquisition of antiestrogen resistance and enhanced expression of the EGFR and of proteins of the S100 family of Ca2+-binding proteins which may contribute to the outgrowth of resistant cells.

The evaluation of human breast lesions with magnetic resonance imaging and proton magnetic resonance spectroscopy

PURPOSE

MR spectroscopy (MRS) assists in lesion characterization and diagnosis when combined with magnetic resonance imaging (MRI). Cancerous lesions demonstrate elevated composite choline levels arising from increased cellular proliferation. Our study investigated if MR spectroscopy of the breast would be useful for characterizing benign and malignant lesions.

MATERIALS AND METHODS

Single voxel proton MR spectroscopy (MRS) was acquired as part of an MR imaging protocol in 38 patients referred upon surgical consultation. The MR spectra were read independently in a blinded fashion without the MR images by three spectroscopists. The MRI exam was interpreted in two settings: (a) as a clinical exam with detailed histories and results from previous imaging studies such as mammography or ultrasound included and (b) as a blinded study without prior histories or imaging results.

RESULTS

Elevated choline levels were demonstrated by MRS in 19 of the 23 confirmed cancer patients. The sensitivity and specificity for determining malignancy from benign breast disease with MRS alone were 83 and 87%, respectively, while a blinded MRI review reported 95 and 86%, respectively.

CONCLUSIONS

Proton MR spectroscopy provides a noninvasive, biochemical measure of metabolism. The technique can be performed in less than 10 min as part of an MRI examination. MRI in combination with MRS may improve the specificity of breast MR and thereby, influence patient treatment options. This may be particularly true with less experienced breast MRI readers. In exams where MRI and MRS agree, the additional confidence measure provided by MRS may influence the course of treatment.

Growth inhibition and growth stimulation by estradiol of estrogen receptor transfected human breast epithelial cell lines involve different pathways

Epidermal growth factor (EGF) and estradiol (E2) are important mitogens in breast epithelial cells, and expression of epidermal growth factor receptor (EGFR) and estrogen receptor (ER) is often inversely correlated in human breast cancer cells. Stable transfection of ER-negative cells with ER cDNA is not sufficient to restore E2-mediated growth stimulation, on the contrary, E2 often inhibits growth of ER-transfected cell lines. In this study we used the ER-transfected human breast epithelial cell lines HMT-3522F9, growth inhibited by E2 in the presence of EGF, and HMT-3522F9/S3B, growth stimulated by E2 in the absence of EGF. In S3B cells, no active MAP kinase could be detected in response to E2, suggesting that signalling through the MAP kinase is not the major pathway in the E2-mediated growth stimulation. Interestingly, a decreased level of active MAP kinase was observed in HMT-3522F9 cells in response to E2, indicating that in these cells cross-talk between the ER and the MAP kinase signalling pathway could be due to the E2-mediated growth inhibition. Moreover, we found that EGF-induced signalling also could be reduced by E2 in S3B cells, suggesting a general mechanism of action by E2 in cells concomitantly expressing ER and EGFR.

Effects of retinoic acid and fenretinide on the c-erbB-2 expression, growth and cisplatin sensitivity of breast cancer cells

We investigated the effects of all-trans retinoic acid (ATRA) and fenretinide (4-HPR) on c-erbB-2 expression in SK-BR-3, BT-474 and MCF-7 breast cancer cells and on the growth, differentiation, apoptosis and cisplatin (CDDP) sensitivity of SK-BR-3 cells. It has been reported that oestrogen inhibits c-erbB-2 in oestrogen receptor-positive breast cancer cells. Using ELISA, Western and Northern analysis we have demonstrated that ATRA and 4-HPR exert similar effects down-regulating c-erbB-2 protein and mRNA in c-erbB-2-overexpressing SK-BR-3 and BT-474 and in normally expressing MCF-7 cells. Both retinoids inhibit SK-BR-3 cell growth. ATRA induces cellular enlargement and flattening, suggesting epithelial differentiation. 4-HPR causes nuclear and cytoplasmic condensation, DNA fragmentation and externalization of phosphatidylserine, indicating apoptosis. c-erbB-2 expression/activity has been linked to sensitivity against CDDP. Therefore, combinations of ATRA or 4-HPR with CDDP were tested for their anti-proliferative activity. Retinoid-conditioned cells were either exposed to retinoid and CDDP (schedule I, 'continuous retinoid treatment') or to CDDP alone (schedule II, 'retinoid pretreatment'). This retinoid-conditioning followed by CDDP +/- retinoid yields stronger growth inhibition compared with unconditioned cells, which were exposed to CDDP +/- retinoid (schedule III, 'no retinoid pretreatment'). The inefficacy of schedule III indicates that retinoid-conditioning is essential for the improvement of the antiproliferative effect. The interactions in schedules I and II are synergistic for ATRA and CDDP, but slightly antagonistic for 4-HPR and CDDR However, 4-HPR + CDDP is more effective in growth inhibition than each drug alone.

Estrogens and glucocorticoids induce the expression of c-erbB2/NEU receptor in Ishikawa human endometrial cells

We investigated the effects of estrogens and other steroid hormones on c-erbB2 gene expression in Ishikawa human endometrial adenocarcinoma cells. We have found that the c-erbB2/NEU transcripts are present in the Ishikawa endometrial cell line as well as in human endometrial adenocarcinoma cells. Both cell types express the 4.6 and 2.3 kb c-erbB2 mRNAs. Estradiol significantly increased in a time- and dose-dependent manner the content of c-erbB2 mRNA and the concentration of NEU protein in Ishikawa cell extracts, while progesterone was devoid of any activity. The effect of estradiol was partially reversed by the antiestrogen 4-hydroxytamoxifen, which, however, given alone exhibited agonist effects. Glucocorticoid dexamethasone augmented in a time- and dose-dependent fashion the content of c-erbB2 mRNA and the concentration of NEU protein in Ishikawa cell extracts. The antiglucocorticoid RU 486 acted as a glucocorticoid agonist increasing c-erbB2 gene activation. To our knowledge, this is the first report documenting the induction by steroid hormones of c-erbB2 gene expression in neoplastic human endometrial cells. Our data support the hypothesis that the oncogenic effect of estrogens on human endometrial cells may be partially mediated by its effect on the expression of the c-erbB2 proto-oncogene. The finding that glucocorticoids may induce endometrial c-erbB2 gene expression suggests that they may participate in the emergence of uterine neoplasias.

Expression of pS2, c-erbB-2, and cathepsin D during the menstrual cycle in human breast cancers

BACKGROUND

Many studies have addressed the effect of the timing of surgery for breast cancer relative to menstrual cycle phase, with conflicting results. Explanations for the possibility that survival could be altered by the appropriate timing of breast cancer surgery in humans remain speculative.

METHODS

We examined the expression of three estrogen related proteins (c-erbB-2, cathepsin D, pS2) in the breast tumors from 69 premenopausal women sampled in different phases of the menstrual cycle. Data on S-phase fraction and hormone receptor expression were also analyzed. Immunohistochemical assays were used to measure the proteins of interest. S-phase fraction was determined by flow cytometry. Analyses were performed based on fraction of cells staining positive for the protein, density of stain, and a histoscore that combined both fraction of positive cells and density.

RESULTS

We found no differences in c-erbB-2, cathepsin D, hormone receptor, or S-phase levels in tumors sampled in the follicular versus luteal phase, or perimenstrual versus periovulatory phase. The exception was pS2, which was expressed at greater levels during the luteal than during the follicular phase of the cycle (p < 0.01); but there was no difference in pS2 expression when the patients were classified as periovulatory versus perimenstrual.

CONCLUSIONS

Our findings do not support a variation in c-erbB-2, cathepsin D, S-phase fraction, or receptor expression as an explanation for the differences in breast cancer prognosis when surgery is timed by menstrual cycle phase. The finding that pS2 (an indicator of hormone sensitivity, and possibly better prognosis) is expressed at higher levels in tumor samples during the luteal phase suggests that the biologic profile of breast tumors may vary with the menstrual cycle and that these variations deserve further study.

The effects of dihydrotestosterone on the expression of p185(erbB-2) and c-erbB-2 mRNA in the prostatic cell line LNCaP

The c-erbB-2 proto-oncogene encodes a 185000 molecular weight protein (p185(erbB-2)) which shares structural homology with the epidermal growth factor (EGF) receptor. We examined the effects of dihydrotestosterone (DHT) on the expression of p185(erbB2) and c-erbB-2 mRNA in the human malignant prostatic cell line LNCaP. LNCaP cells grown in steroid-depleted media were treated with DHT (10(-11)-10(-6) M) for 48 h and p185(erbB-2) expression was determined by Western blotting and immunoprecipitation of 35S-methionine labelled p185(erbB-2). c-erbB-2 mRNA levels were determined using a competitive quantitative reverse transcription-polymerase chain reaction (RT-PCR) based technique. DHT at concentrations of 10(-9) M or greater resulted in decreased expression of p185(erbB-2). In contrast, DHT at these levels stimulated EGF receptor protein expression and cellular proliferation. c-erbB-2 mRNA levels declined to 30-50% of control levels following treatment with DHT of 10(-10) M or greater. Furthermore, the inhibitory effects on c-erbB-2 mRNA were rapid, occurring within 6-12 h of treatment. In summary, these results demonstrate that DHT, at concentrations that stimulate cell growth, inhibits the expression of p185(erbB-2) and c-erbB-2 mRNA.

Relation of oestradiol-mediated growth stimulation with the expression of c-erbB-2 protein in xenotransplanted oestradiol-receptor-positive and -negative breast carcinomas

Attempts were made to correlate growth effects induced by oestradiol and tamoxifen with the hormonal regulation of c-erbB-2 protein in experiments in vivo. We report here the responsiveness of four xenotransplanted oestrogen-receptor(ER)-positive and four ER-negative human mammary carcinomas to oestradiol and tamoxifen. Oestradiol in a dose of 0.5 mg/kg significantly increased the growth of the ER-positive mammary carcinomas 3366, MCF-7, 4134 and 4049, but not the ER-negative tumours 4000, 4296 and MT-3. However, within the group of the ER-negative breast carcinomas the tumour 4151 ES deviates from this growth behaviour, as we could prove an estrogen induced growth. The stimulation of tumour growth by oestradiol was always accompanied by a down-regulation of c-erbB-2 protein both in the ER-positive mammary carcinomas and in the ER-negative mammary carcinoma 4151 ES. Tamoxifen significantly inhibited the growth of the ER/PR-positive mammary carcinomas 3366 and MCF-7 but not the ER-positive/PR-negative mammary carcinomas 4049 and 4134. In the group of ER-negative mammary carcinomas only the growth of the oestrogen-responsive tumour 4151 ES was significantly inhibited by tamoxifen. The inhibition of tumour growth by tamoxifen was correlated with a reversion of the oestradiol-induced down-regulation of c-erbB-2, also in the ER-negative/oestradiol-responsive mammary carcinoma 4151 ES. From our results we hypothesize that the oestrogen-dependent growth of ER-negative breast carcinoma 4151 ES could also be correlated with the oestradiol-regulated expression of c-erbB-2 protein.

Significance of immunohistochemical c-erbB-2 product localization pattern for prognosis of primary human breast cancer

Concerning immunohistochemistry of the c-erbB-2 receptor in human mammary carcinoma, membranous immunostaining of tumor cells has been generally considered as a potential risk factor for early recurrence, whereas cytoplasmic reactivity has been neglected. An archival study on 463 patients with primary breast cancers demonstrates that cytoplasmic localization of p185 is significantly correlated with high estrogen and progesterone receptor levels, low histological grade and a low proliferating tumor cell fraction. In accordance with these data, patients bearing mammary carcinomas with cytoplasmic localization of p185 reactivity have a significant better overall survival than those with membranous immunostaining.

Determination of c-erbB-2 protein in primary breast cancer tissue extract using an enzyme immunoassay

The c-erbB-2 protein in breast cancer tissue extract was determined by using an enzyme-immunoassay (EIA) to see whether the quantitative determination of the oncoprotein correlates with the results of immunohistochemistry and other prognostic factors. Primary breast cancer from 104 patients was assayed for c-erbB-2 protein with an EIA that used two monoclonal antibodies directed against the extracellular domain of the protein. Pelleted tissue homogenate prepared routinely for hormone receptor assay was used as the starting material. The mean quantity of c-erbB-2 protein was 695 unit/mg protein (range 23 to 5939), and this correlated well with the results of immunohistochemical staining (P < 0.00001). It was found that 17.3% (18/104) of all tumors contained amounts of c-erbB-2 protein exceeding 1000 units/mg protein. All tumors with negative or weakly positive staining contained the oncoprotein as less than 1000 units/mg protein. The content of c-erbB-2 protein was correlated with the histologic grade (P = 0.0022), mitotic index (P = 0.0002) and degree of nuclear atypia (P = 0.013). It was inversely correlated with progesterone receptor (P = 0.006) and less strongly with estrogen receptor status (P = 0.016). Values of hormone receptor concentration and c-erbB-2 protein content showed a hyperbolic relationship that suggested biological interactions between c-erbB-2 protein and steroid hormone receptors. We conclude that c-erbB-2 protein in tissue extracts of primary breast cancer can be determined reliably by EIA, and it seems feasible to explore further the advantages of introducing EIA as a routine laboratory examination for providing additional information about the biological aspects of breast cancer.

Establishment and characteristics of two new human mammary carcinoma lines serially transplantable in nude mice

Two human mammary carcinomas of postmenopausal women were successfully transplanted into nude mice. Both tumours were classified as epidermal-growth-factor-, oestradiol- and progesterone-receptor-negative and c-erbB2-protein-positive. Histological studies of the primary tumours (4000 and 4151) revealed ductal invasive mammary carcinomas. In the first passages the precondition for the growth of breast carcinoma 4000 were pretreatments of the nude mice with oestradiol and peanut oil before transplantation. The mammary carcinomas 4000 and 4151 described here are suitable for in vivo testing of antineoplastic substances and for biological studies.