Mitogenic effects of epidermal growth factor and transforming growth factor-alpha on EGF-receptor positive human ovarian carcinoma cell lines

The Role of Inflammation and Inflammatory Mediators in the Development, Progression, Metastasis, and Chemoresistance of Epithelial Ovarian Cancer

Inflammation plays a role in the initiation and development of many types of cancers, including epithelial ovarian cancer (EOC) and high grade serous ovarian cancer (HGSC), a type of EOC. There are connections between EOC and both peritoneal and ovulation-induced inflammation. Additionally, EOCs have an inflammatory component that contributes to their progression. At sites of inflammation, epithelial cells are exposed to increased levels of inflammatory mediators such as reactive oxygen species, cytokines, prostaglandins, and growth factors that contribute to increased cell division, and genetic and epigenetic changes. These exposure-induced changes promote excessive cell proliferation, increased survival, malignant transformation, and cancer development. Furthermore, the pro-inflammatory tumor microenvironment environment (TME) contributes to EOC metastasis and chemoresistance. In this review we will discuss the roles inflammation and inflammatory mediators play in the development, progression, metastasis, and chemoresistance of EOC.

MiR-205 functions as a tumor suppressor via targeting TGF-α in osteosarcoma

Osteosarcoma (OS) is the most common primary bone cancer, and it is most prevalent in children and young adults. The prognosis of OS remains poor, and survival of OS reached a plateau. The discovery of microRNAs (miRNAs) provides a new possibility for the early diagnosis and treatment of OS. In this study, we detected the expression level of miR-205 and Transforming growth factor-alpha (TGF-α) in 15 cases of clinical OS tissues and adjacent normal bone tissues. We found that the expression of miR-205 was significantly lower in OS tissues than in normal bone tissues; the expression of TGF-α mRNA was significantly increased in OS tissues than in normal bone tissues, the miR-205 was negatively correlated with TGF-α levels in both OS and normal bone tissues. Functional studies demonstrated that miR-205 significantly decreased the capability of cell proliferation, invasion and migration and induced G0/G1 growth arrest and apoptosis in OS cells. By using bioinformatics analytic tool (Targetscan), the 3'UTR of TGF-α gene was found to be a target of miR-205. Luciferase report assay further confirmed that TGF-α 3'UTR is a direct target of miR-205. We also found that the expression of TGF-α mRNA and protein was significantly down-regulated or up-regulated after miR-205 mimic or miR-205 inhibitor transfection. TGF-α knockdown study further showed that miR-205 regulated cell proliferation, invasion and migration by targeting TGF-α in OS. Enforced expression of TGF-α sufficiently restore the effects of miR-205 on cell proliferation, invasion and migration. In conclusion, our study suggested that miR-205 may function as a tumor suppressor via targeting TGF-α in OS, and the abnormal expression of miR-205 might be a key factor in OS progression.

Transforming growth factor alpha promotes osteosarcoma metastasis by ICAM-1 and PI3K/Akt signaling pathway

Osteosarcoma is the most common primary malignancy of bone and is characterized by a high malignant and metastatic potential. Transforming growth factor alpha (TGF-α) is classified as the EGF (epidermal growth factor)-like family, which is involved in cancer cellular activities such as proliferation, motility, migration, adhesion and invasion abilities. However, the effect of TGF-α on human osteosarcoma is largely unknown. We found that TGF-α increased the cell migration and expression of intercellular adhesion molecule-1 (ICAM-1) in human osteosarcoma cells. Transfection of cells with ICAM-1 siRNA reduced TGF-α-mediated cell migration. We also found that the phosphatidylinositol 3'-kinase (PI3K)/Akt/NF-κB pathway was activated after TGF-α treatment, and TGF-α-induced expression of ICAM-1 and cell migration was inhibited by the specific inhibitors and siRNAs of PI3K, Akt, and NF-κB cascades. In addition, knockdown of TGF-α expression markedly decreased cell metastasis in vitro and in vivo. Our results indicate that TGF-α/EGFR interaction elicits PI3K and Akt activation, which in turn activates NF-κB, resulting in the expression of ICAM-1 and contributing the migration of human osteosarcoma cells.

Clinical implications of the ErbB/epidermal growth factor (EGF) receptor family and its ligands in ovarian cancer

The ERBB or EGF receptor (EGFR) proto-oncogene family, which consists of four structurally-related transmembrane receptors (i.e., EGFR, ErbB2, ErbB3, and ErbB4), plays an etiological role in the molecular pathogenesis of cancer and is a key therapeutic target in many types of cancer, including ovarian cancer. These ErbB/EGF receptor tyrosine kinases play important physiologic roles in cell proliferation, survival, adhesion, motility, invasion, and angiogenesis. It is, therefore, not surprising that gene amplification, genetic mutation, and altered transcription/translation result in aberrant ErbB/EGF receptor expression and/or signal transduction, contributing to the development of malignant transformation. Clinically, the diagnostic, prognostic, and theragnostic significance of any single ErbB receptor and/or ErbB ligand is controversial, but generally, ErbB receptor overexpression has been correlated with poor prognosis and decreased therapeutic responsiveness in ovarian cancer patients. Thus, anticancer agents targeting ErbB/EGF receptors hold great promise for personalized cancer treatment. Yet, challenges remain in designing prospective clinical trials to assess the clinical utility of ErbB receptors and their ligands to diagnose cancer; to predict progression-free and overall survival, therapeutic responsiveness, and disease recurrence; and to monitor treatment responsiveness. Here, we review the tissue expression and serum biomarker studies that have evaluated the diagnostic, prognostic, and theragnostic utility of ErbB/EGF receptors, their circulating soluble isoforms (sEGFR/sErbBs), and their cognate ligands in ovarian cancer patients.

Sensitivity to pertuzumab (2C4) in ovarian cancer models: cross-talk with estrogen receptor signaling

Pertuzumab (Omnitarg, rhuMab 2C4) is a humanized monoclonal antibody, which inhibits HER2 dimerization. Because it has shown some clinical activity in ovarian cancer, this study sought to identify predictors of response to this agent in a model of ovarian cancer. A panel of 13 ovarian cancer cell lines was treated with heregulin beta1 (HRGbeta1) or transforming growth factor-alpha, and cell proliferation was assessed. Both agents increased cell number in the majority of cell lines studied, the response to both being similar (r = 0.83; P = 0.0004, Pearson test). HRGbeta1 stimulation could be partially reversed by pertuzumab in 6 of 13 cell lines, with complete reversal in PE04 and PE06 cells. Addition of pertuzumab to transforming growth factor-alpha-stimulated cells produced growth inhibition in 3 of 13 cell lines (PE01, PE04, and PE06). The magnitude of HRGbeta1-driven growth stimulation correlated significantly with an increase in extracellular signal-regulated kinase 2 (P = 0.037) but not Akt (P = 0.99) phosphorylation. Such HRGbeta1-driven phosphorylation of extracellular signal-regulated kinase 1/2 and Akt could be reduced with pertuzumab, accompanied by changes in cell cycle distribution. In cell lines responsive to pertuzumab, HRGbeta1-enhanced phosphorylation of HER2 (Tyr(877)) was reduced. Estrogen-stimulated changes in growth, cell cycle distribution, and signaling were reversed by pertuzumab, indicating cross-talk between HER2 and estrogen signaling. These data indicate that there is a subset of ovarian cancer cell lines sensitive to pertuzumab and suggest possible predictors of response to identify patients who could benefit from this therapy. Furthermore, we have identified an interaction between HER2 and estrogen signaling in this disease.

Altered ErbB receptor signaling and gene expression in cisplatin-resistant ovarian cancer

The majority of ovarian cancer patients are treated with platinum-based chemotherapy, but the emergence of resistance to such chemotherapy severely limits its overall effectiveness. We have shown that development of resistance to this treatment can modify cell signaling responses in a model system wherein cisplatin treatment has altered cell responsiveness to ligands of the erbB receptor family. A cisplatin-resistant ovarian carcinoma cell line PE01CDDP was derived from the parent PE01 line by exposure to increasing concentrations of cisplatin, eventually obtaining a 20-fold level of resistance. Whereas PE01 cells were growth stimulated by the erbB receptor-activating ligands, such as transforming growth factor-alpha (TGFalpha), NRG1alpha, and NRG1beta, the PE01CDDP line was growth inhibited by TGFalpha and NRG1beta but unaffected by NRG1alpha. TGFalpha increased apoptosis in PE01CDDP cells but decreased apoptosis in PE01 cells. Differences in extracellular signal-regulated kinase and phosphatidylinositol 3-kinase signaling were also found, which may be implicated in the altered cell response to ligands. Microarray analysis revealed 51 genes whose mRNA increased by at least 2-fold in PE01CDDP cells relative to PE01 (including FRA1, ETV4, MCM2, AXL, MT3, TRAP1, and FANCG), whereas 36 genes (including IGFBP3, TRAM1, and KRT4 and KRT19) decreased by a similar amount. Differential display reverse transcriptase-PCR identified altered mRNA expression for TCP1, SLP1, proliferating cell nuclear antigen, and ZXDA. Small interfering RNA inhibition of FRA1, TCP1, and MCM2 expression was associated with reduced growth and FRA1 inhibition with enhanced cisplatin sensitivity. Altered expression of these genes by cytotoxic exposure may provide survival advantages to cells including deregulation of signaling pathways, which may be critical in the development of drug resistance.

Genetic contributions to Parkinson's disease

Sporadic Parkinson's disease (PD) is a common neurodegenerative disorder, characterized by the loss of midbrain dopamine neurons and Lewy body inclusions. It is thought to result from a complex interaction between multiple predisposing genes and environmental influences, although these interactions are still poorly understood. Several causative genes have been identified in different families. Mutations in two genes [alpha-synuclein and nuclear receptor-related 1 (Nurr1)] cause the same pathology, and a third locus on chromosome 2 also causes this pathology. Other familial PD mutations have identified genes involved in the ubiquitin-proteasome system [parkin and ubiquitin C-terminal hydroxylase L1 (UCHL1)], although such cases do not produce Lewy bodies. These studies highlight critical cellular proteins and mechanisms for dopamine neuron survival as disrupted in Parkinson's disease. Understanding the genetic variations impacting on dopamine neurons may illuminate other molecular mechanisms involved. Additional candidate genes involved in dopamine cell survival, dopamine synthesis, metabolism and function, energy supply, oxidative stress, and cellular detoxification have been indicated by transgenic animal models and/or screened in human populations with differing results. Genetic variation in genes known to produce different patterns and types of neurodegeneration that may impact on the function of dopamine neurons are also reviewed. These studies suggest that environment and genetic background are likely to have a significant influence on susceptibility to Parkinson's disease. The identification of multiple genes predisposing to Parkinson's disease will assist in determining the cellular pathway/s leading to the neurodegeneration observed in this disease.

Identification of epidermal growth factor-responsive genes in normal rat ovarian surface epithelial cells

Alteration in epidermal growth factor receptor (EGFR) family signaling is among the most frequently implicated effectors of human oncogenesis. Overexpression of members of this family of receptors has often been detected in many epithelial tumors and is believed to be associated with an overall poor prognosis in patients with cancer. Therefore, we hypothesized that identification of potential EGF target genes in normal cells will provide a basis for unbiased genetic analysis of this signaling pathway in cancer. We utilized Atlas Rat 1.2 nylon cDNA arrays (Clontech) to determine gene expression changes in normal rat ovarian surface epithelial (ROSE) cells following EGF treatment. The results indicate activation of genes involved in a wide variety of cellular mechanisms, including regulation of cell cycle and proliferation, apoptosis, and protein turnover. In addition, using an in vitro model of ovarian cancer, we demonstrated that malignant transformation of ROSE cells resulted in alteration of downstream effectors of the EGFR pathway, as exemplified by aberrant expression of p66Shc, c-Jun, c-Myc, c-Fos, Lot1, p21Cip/Waf, and cdc25A. These data suggest that knowledge of the downstream genetic lesions, which may result in loss of growth factor requirement of the affected cells, will be crucial for the selection of the EGFR pathway as an effective target for cancer therapy.

Effective treatment of experimental ES-2 human ovarian cancers with a cytotoxic analog of luteinizing hormone-releasing hormone AN-207

The receptors for luteinizing hormone-releasing hormone (LHRH) are found in 80% of human ovarian carcinomas. These receptors can be used for targeted chemotherapy with cytotoxic analogs of LHRH, such as AN-207, consisting of 2-pyrrolinodoxorubicin (AN-201) linked to [D-Lys ]LHRH. We investigated the effects of AN-207 and AN-201 on the growth of LHRH receptor-positive ES-2 human ovarian cancers. The effects of the treatment on mRNA and protein levels of human epidermal growth factor (EGF) receptors (EGFR and HER-2) in ovarian tumors were determined by RT-PCR and immunoblotting. In Experiment 1, nude mice bearing ES-2 ovarian tumors were injected i.v. with 250 nmol/kg doses of AN-207, AN-201, the carrier [D-Lys ]LHRH, an unconjugated mixture of AN-201 and [D-Lys ]LHRH or vehicle. AN-207 caused a significant ( <0.01) 59.5% inhibition in tumor growth while its components were ineffective. In Experiment 2, mice with large ES-2 tumors were treated with AN-207 or AN-201 at 250 nmol/kg. Again, AN-207, but not AN-201, inhibited tumor growth. In Experiment 3, the site of action of AN-207 was investigated. The blockade of LHRH receptors with Cetrorelix partially suppressed the antitumor effect of AN-207. Treatment with AN-207 significantly ( <0.01) decreased the expression of mRNA for EGFR, and HER-2 by 27 and 34%, respectively, as compared to controls and reduced the receptor protein levels of EGFR and HER-2 by 35 and 36%, respectively ( <0.05). The results indicate that cytotoxic LHRH analog AN-207 could be considered for chemotherapy of ovarian cancers expressing LHRH receptors.

The expression of EGFR family ligands in breast carcinomas

Expression of EGF, HB-EGF, TGF-alpha, HRG-alpha, HRG-beta1, and HRG-beta3 in 100 frozen breast carcinoma materials was immunohistochemically studied. Among these tumors, 67% were positive for EGF, 53% for HB-EGF, 57% for TGF-alpha, 60% for HRG-alpha, 53% for HRG-beta1, and 63% for HRG-beta3 in the neoplastic epithelial cells. No significant associations between expression of the growth factors and clinicopathological features like tumor size, histologic grade, node status, ploidy, ER status, and c-erbB-4 expression were observed, with the exceptions that significant relations were present between EGF expression and tumor size (p = 0.01) and between HRG-beta3 expression and node status (p = 0.02). The expressions of these growth factors showed no association with cancer-specific survival by the Kaplan Meier analysis.

Targeting the EGF receptor in ovarian cancer with the tyrosine kinase inhibitor ZD 1839 ("Iressa")

The modulating effects of the orally active epidermal growth factor receptor-specific tyrosine kinase inhibitor ZD 1839 ("Iressa") on cell growth and signalling were evaluated in four ovarian cancer cell lines (PE01, PE04, SKOV-3, OVCAR-5) that express the epidermal growth factor receptor, and in A2780, which is epidermal growth factor receptor-negative. Transforming growth factor-alpha stimulated growth was completely inhibited by concentrations of ZD 1839 > or =0.3 microM in the epidermal growth factor receptor-expressing cell lines, as were transforming growth factor-alpha stimulated phosphorylation of the epidermal growth factor receptor and downstream components of the MAP kinase and PI-3 kinase signalling cascades. Growth inhibition in the absence of added transforming growth factor-alpha was also observed which could be consistent with suppression of action of autocrine epidermal growth factor receptor-activating ligands by ZD 1839. In support of this, transforming growth factor-alpha, EGF and amphiregulin mRNAs were detected by RT-PCR in the epidermal growth factor receptor-expressing cell lines. ZD 1839 inhibited growth of the PE04 ovarian cancer xenograft at 200 mg kg(-1)day(-1). These data lend further support to the view that targeting the epidermal growth factor receptor in ovarian cancer could have therapeutic benefit.

Ovarian epithelial carcinoma tyrosine phosphorylation, cell proliferation, and ezrin translocation are stimulated by interleukin 1alpha and epidermal growth factor

BACKGROUND

Ezrin is a member of the ezrin, radixin, and moesin family. These proteins are membrane-actin cross-linking proteins. Furthermore, ezrin is an important signal transduction protein that undergoes phosphorylation and translocation on stimulation by growth factors. Ezrin phosphorylation and translocation are thought to be correlated with cell motility, invasion, and carcinoma metastasis. Recently, the authors reported that an ezrin antisense phosphorothionate could significantly inhibit endometrial carcinoma cells' penetration in the Matrigel membrane cancer invasion assay. In the current study, the authors measured ezrin content in clinical ovarian epithelial carcinoma (OVCA) specimens and cell lines and investigated whether interleukin (IL)-1alpha and epidermal growth factor (EGF) induce an invasive phenotype in OVCA cells via ezrin phosphorylation and translocation.

METHODS

Twenty-five normal ovary, 25 primary OVCA, 21 metastatic OVCA tissue (7 in omentum, 16 in ascites), and 3 OVCA cell lines were collected for Western blot detection of ezrin content. The OVCA cell line SKOV3 was treated with IL-1alpha or EGF. Indirect immunofluorescence staining followed by confocal laser scanning and double-staining electron microscopic immunohistochemistry were used to investigate changes in the intracellular distribution of ezrin and cell morphology after IL-1alpha or EGF treatment. The content of ezrin was measured by Western blotting and analyzed by the National Institutes of Health Image computer program. Immunoprecipitation and Western blot techniques were used for ezrin phosphorylation studies. Genistein was used to block tyrosine phosphorylation.

RESULTS

(1) Ezrin was overexpressed in OVCA, with the highest values in metastases. (2) Interleukin-1alpha and EGF significantly increased OVCA tyrosine phosphorylation, ezrin translocation, and cell growth. (3) These effects were abolished by treatment with the tyrosine kinase inhibitor, genistein. (4) Treatment with IL-1alpha or EGF induced an invasive phenotype, i.e., membrane ruffling, and process formation.

CONCLUSIONS

High expression and activation of ezrin appear to be related to OVCA metastatic behavior. Interleukin-1alpha and EGF may regulate OVCA invasive behavior by activating ezrin tyrosine phosphorylation, translocation, and cancer cell proliferation. The authors' results may partially explain why OVCA patients with positive macrophage colony stimulating factor (a chemoattractant of IL-1alpha secreting monocytes) or EGF receptors (c-erb B-2) have a poor prognosis.

Ovarian surface epithelium: biology, endocrinology, and pathology

The epithelial ovarian carcinomas, which make up more than 85% of human ovarian cancer, arise in the ovarian surface epithelium (OSE). The etiology and early events in the progression of these carcinomas are among the least understood of all major human malignancies because there are no appropriate animal models, and because methods to culture OSE have become available only recently. The objective of this article is to review the cellular and molecular mechanisms that underlie the control of normal and neoplastic OSE cell growth, differentiation, and expression of indicators of neoplastic progression. We begin with a brief discussion of the development of OSE, from embryonic to the adult. The pathological and genetic changes of OSE during neoplastic progression are next summarized. The histological characteristics of OSE cells in culture are also described. Finally, the potential involvement of hormones, growth factors, and cytokines is discussed in terms of their contribution to our understanding of the physiology of normal OSE and ovarian cancer development.

EGF-related antisense oligonucleotides inhibit the proliferation of human ovarian carcinoma cells

BACKGROUND

The epidermal growth factor (EGF)-like peptides CRIPTO (CR), amphiregulin (AR) and transforming growth factor alpha (TGFalpha) are expressed in human ovarian carcinomas.

MATERIALS AND METHODS

The expression of AR, CR and TGFalpha in ovarian carcinoma cell lines was assessed by immunocytochemistry and reverse transcriptase polymerase chain reaction (RT-PCR). The antiproliferative effects of antisense phosphorothioate oligodeoxynucleotides (AS S-Oligos) directed against either AR, CR or TGFalpha was evaluated by using a clonogenic assay.

RESULTS

A majority of the ovarian carcinoma cell lines was found to express TGFalpha, AR and CR mRNAs and proteins. AS S-Oligos directed against either AR, CR or TGFalpha were able to inhibit the anchorage-independent growth of NIH:OVCAR3 and NIH:OVCAR8 cells in a dose dependent manner. A 30%-50% growth inhibition was observed at a 2 microM concentration of the AS S-Oligos. Treatment of these cells with combinations of EGF-related AS S-Oligos resulted in a more significant growth inhibition when compared to treatment with a single AS S-oligo. A 60%-75% growth inhibition was observed using combinations of AR, CR and TGFalpha AS S-oligos at a total concentration of 2 microM. An additive growth-inhibitory effect occurred when ovarian carcinoma cells were exposed to the AS S-Oligos after treatment with either paclitaxel or cis-platinum.

CONCLUSIONS

These data suggest that EGF-related peptides function as autocrine growth factors in ovarian carcinoma cells, and that they might represent targets for experimental therapy of ovarian carcinoma.

Expression and function of EGF-related peptides and their receptors in gynecological cancer--from basic science to therapy

EGF-related peptides and their receptors play an important, but not fully understood role, both, in epithelial physiology and pathophysiology but also in human tumor carcinogenesis and tumor behavior, respectively. Overexpression of EGF-related growth factors from normal epithelium to carcinomas has been demonstrated for several human tissues such as breast, endometrium, cervix and ovary. Additionally, the differential overexpression of EGFR or erb B-2 in various malignancies has already proven to be efficacious in stratifying patients with respect to a poor prognosis. These data suggest that EGF-related growth factors, erb B receptors or signaling proteins that function either upstream or downstream from these receptors may represent novel targets for selective tumor therapy. In the future, conventional chemotherapy regimes will ultimately be wedded to more biologically-oriented therapies. One important target for these novel therapeutic approaches in solid tumors will be the EGF-related growth factors and their receptors.

Inhibition of transforming growth factor alpha (TGF-alpha)-mediated growth effects in ovarian cancer cell lines by a tyrosine kinase inhibitor ZM 252868

The modulating effects of the epidermal growth factor (EGF) receptor-specific tyrosine kinase inhibitor ZM 252868 on cell growth and signalling have been evaluated in four ovarian carcinoma cell lines PE01, PE04, SKOV-3 and PE01CDDP. Transforming growth factor alpha (TGF-alpha)-stimulated growth was completely inhibited by concentrations > or =0.3 microM in the PE01 and PE04 cell lines and by > or =0.1 microM in SKOV-3 cells. TGF-alpha inhibition of PE01CDDP growth was reversed by concentrations > or =0.1 microM ZM 252868. TGF-alpha-stimulated tyrosine phosphorylation of both the EGF receptor and c-erbB2 receptor in all four cell lines. The inhibitor ZM 252868, at concentrations > or =0.3 microM, completely inhibited TGF-alpha-stimulated tyrosine phosphorylation of the EGF receptor and reduced phosphorylation of the c-erbB2 protein. EGF-activated EGF receptor tyrosine kinase activity was completely inhibited by 3 microM ZM 252868 in PE01, SKOV-3 and PE01CDDP cells. These data indicate that the EGF receptor-targeted TK inhibitor ZM 252868 can inhibit growth of ovarian carcinoma cells in vitro consistent with inhibition of tyrosine phosphorylation at the EGF receptor.

Regulation of proliferation and apoptosis by epidermal growth factor and protein kinase C in human ovarian surface epithelial cells

Epidermal growth factor (EGF) is produced in the ovary and influences proliferation of the malignant ovarian surface epithelium (OSE); yet its role in malignancy or in regulating the normal surface epithelium is unclear. In human OSE cells derived from primary cultures of normal tissue transfected with SV40 large T antigen (IOSE cells), EGF promoted survival but not proliferation. This survival effect was reversed by acute treatment with the phorbol ester, 12-0-tetradecanoyl-13-phorbol acetate (TPA) which alone markedly inhibited IOSE proliferation. We tested whether the activities of the mitogen-activated protein kinases (ERK1/2 and JNK1) varied in response to EGF, TPA, or combinations of these agonists and if the same treatments altered patterns of immediate early gene expression. Alone, EGF activated ERK1/2, increased and sustained levels of c-jun mRNA, but had almost no effect on JNK1 activation. Conversely, PKC activation resulted in a rapid, but transient induction of c-fos RNA and of both kinases, JNK1 and ERK2. When combined, EGF and TPA further enhanced the phosphorylation of both enzymes despite inhibiting survival. Though JNKs and ERKs are thought to transduce opposing cellular responses, in IOSE cells, robust costimulation of the JNK and ERK pathways may redirect the survival message.

Endogenous EGF-family growth factors are necessary for the progression from the G1 to S phase in human keratinocytes

Recently several endogenous epidermal growth factor (EGF)-family growth factors (transforming growth factor-alpha, amphiregulin, and heparin-binding EGF-like growth factor) have been identified in human keratinocytes. These factors are known to play an important role in the regulation of cell proliferation. Here we show that the interaction between these factors and EGF receptor are key factors in the progression from the G1 phase to the S phase (the G1/S progression) in human keratinocytes. In this study, human keratinocytes were cultured in serum-free MCDB153 medium and then partially synchronized by isoleucine deprivation. After synchronization, the number of S phase cells increased and reached a maximum after 18-24 h. The immediate addition of anti-EGF receptor blocking antibody (1 microg per ml) to synchronized cells decreased S phase cells by 42.5% compared with untreated keratinocytes at 18 h. By contrast, the addition of anti-EGF receptor antibodies at 12 h or later did not alter the percentage of S phase cells. Northern blot analysis of synchronized cells demonstrated that mRNA expression of transforming growth factor-alpha, amphiregulin, heparin-binding EGF-like growth factor, and EGF receptor reached a maximum within 0.5-3 h after synchronization, when many cells initiated progression from the G1 to the S phase. The results show that anti-EGF receptor antibodies block the G1/S progression and the rapid increase of mRNA expression of endogenous EGF-family growth factors and EGF receptor during G1/S progression. These findings indicate that growth factor binding and EGF receptor activation are involved in the G1/S cell cycle progression of human keratinocytes.

Detection of serum transforming growth factor-alpha in patients of primary epithelial ovarian cancers by enzyme immunoassay

Transforming growth factor-alpha (TGF-alpha) is a potent mitogenic polypeptide. It is secreted by a variety of transformed cells and tumors, modifying tumor growth through autocrine or paracrine mechanism. In the present study, serum levels of TGF-alpha were determined by enzyme-linked immunosorbent assay (ELISA) in 27 normal females, 116 patients with benign ovarian tumors, and 42 patients with epithelial ovarian cancers (10 with stage I, 7 with stage II, 19 with stage III, and 6 with stage IV). The ELISA assay could detect a minimum level of serum TGF-alpha concentration at 10 pg/ml. Serum samples were obtained from normal females and from patients with benign or malignant ovarian tumors before initial surgery. The detectable rates were 11% (3/27) in normal females, 28% (32/116) in benign ovarian tumors, and 62% (26/42) in ovarian cancers. The detectable rates in serous and endometrioid ovarian cancers were 71 and 70%, respectively, which were higher than the rate of 33% in mucinous type. However, there was no obvious relationship between the detectability of serum TGF-alpha and the stages of ovarian cancers. The mean concentration of TGF-alpha in ovarian cancer was 159.8 pg/ml, which was significantly higher than 27.7 pg/ml in benign ovarian tumors (P < 0.001) as well as 15 pg/ml in normal females (P < 0.001). The mean concentrations of serum TGF-alpha in stages I to IV ovarian cancers were 133.5, 96.2, 194.8, and 178.3 pg/ml, respectively. The mean concentration of serum TGF-alpha in any two stages of ovarian cancers was not statistically different. In conclusion, measurement of serum TGF-alpha can be used as a supplementary tumor marker to differentiate a malignant ovarian tumor from a benign one. However, the concentration of serum TGF-alpha has no special relation with the stage of ovarian cancer itself. Because of the small number of stage I ovarian cancers with detectable TGF-alpha in the present investigation, it would probably not be feasible to differentiate a stage I ovarian cancer from a benign ovarian tumor based only on the level of TGF-alpha in serum.

Absence of constitutive EGF receptor activation in ovarian cancer cell lines

Previous investigators have noted that certain ovarian cancer cell lines secrete and respond to transforming growth factor-alpha (TGF-alpha), suggesting that endogenous activation of the epidermal growth factor (EGF) receptor through autocrine or paracrine mechanisms might contribute to the proliferative response. In order to determine whether autocrine stimulation was partly responsible for the proliferative response in ovarian cancer, we investigated whether the EGF receptor expressed by ovarian cancer cell lines was constitutively activated as assessed by the presence of tyrosine phosphorylation. A specific anti-phosphotyrosine antibody was used in conjunction with an immunoblotting technique in order to detect EGF receptor phosphorylation in ovarian cancer cell lines in the absence and presence of exogenous EGF. The effects of neutralising anti-EGF receptor antibody on the proliferation of ovarian cancer cell lines was also examined. We found no evidence for constitutive tyrosine phosphorylation of the p170 EGF receptor in eight epithelial ovarian cancer cell lines tested, although each line demonstrated inducible phosphorylation in response to exogenous EGF. The absence of constitutive EGF receptor activation was also noted when cells were grown under high density conditions, thus excluding a role for membrane-bound EGF or TGF-alpha in this process. Media conditioned by five ovarian cancer cell lines, as well as malignant ascites obtained from 12 different ovarian cancer patients, were not capable of stimulating EGF receptor phosphorylation. Finally, the proliferation of ovarian cancer cell lines was not significantly inhibited in the presence of neutralising anti-EGF receptor antibody. These data suggest that EGF receptor activation through autocrine pathways is not a major mechanism for the growth of many ovarian cancer cell lines. Other pathways of signal transduction which bypass the requirement for EGF receptor activation may be important in the proliferation for ovarian cancer cells. Such EGF receptor-independent pathways may limit the effectiveness of strategies designed to inhibit ovarian cancer cell growth through disruption of EGF receptor function.

The prognostic value of epidermal growth factor receptor mRNA expression in primary ovarian cancer

The expression of mRNA for the epidermal growth factor (EGF) receptor, EGF and transforming growth factor alpha (TGF-alpha) was determined in 76 malignant, six borderline and 15 benign primary ovarian tumours using the reverse transcriptase-polymerase chain reaction and related to clinical and pathological parameters. Of the malignant tumours, 70% (53/76) expressed EGF receptor mRNA, 31% (23/75) expressed EGF mRNA and 35% (26/75) expressed TGF-alpha mRNA. For the borderline tumours, four of six (67%) expressed EGF receptor mRNA, 1/6 (17%) expressed TGF-alpha mRNA and none expressed EGF mRNA. Finally, 33% (5/15) of the benign tumours expressed EGF receptor mRNA, whereas 40% (6/15) expressed EGF mRNA and 7% (1/15) expressed TGF-alpha mRNA. The presence of the EGF receptor in malignant tumours was associated with that of TGF-alpha (P = 0.0015) but not with EGF (P = 1.00), whereas there was no relationship between the presence of EGF and TGF-alpha (P = 1.00). EGF receptor mRNA expression was significantly and positively associated with serous histology (P = 0.006) but not with stage or grade. Neither EGF nor TGF-alpha showed any link with histological subtype or stage. The survival of patients with malignant tumours possessing EGF receptor mRNA was significantly reduced compared with that of patients whose tumours were negative (P = 0.030 for all malignant tumours; P = 0.007 for malignant epithelial tumours only). In contrast, neither the expression of TGF-alpha nor EGF was related to survival. These data suggest that the presence of EGF receptor mRNA is associated with poor prognosis in primary ovarian cancer.

The regulation of growth and protein expression by estrogen in vitro: a study of 8 human ovarian carcinoma cell lines

The effects of 17 beta-estradiol (E2) on the growth and the levels of estrogen receptor (ER), progesterone receptor (PR) and pS2 protein were examined in a range of 8 ovarian carcinoma cell lines. E2 stimulated growth of the 3 cell lines with an ER content of 80-220 fmol/mg protein but not the 5 cell lines with ER concentrations less than 20 fmol/mg protein. After exposure to E2, ER concentration in 2 of the 3 responsive cell lines was decreased relative to untreated cells and in 2 lines, progesterone receptors were increased. No change in steroid receptor levels was observed in cell lines with low or negligible levels of receptors. The pS2 protein was not induced by E2 in the 5 ovarian carcinoma cell lines examined. These results indicate that E2 can stimulate the growth of some ER-positive ovarian carcinoma cells and that these effects may be associated with changes in the cellular levels of steroid hormone receptors.

Involvement of polyamines in epidermal growth factor (EGF), transforming growth factor (TGF)-alpha and -beta 1 action on culture of L6 and fetal bovine myoblasts

1. alpha-Difluoromethylornithine, an irreversible inhibitor of ornithine decarboxylase significantly abolished stimulation of protein synthesis evoked by EGF, TGF-alpha or -beta 1 in L6 and fetal bovine myoblasts. 2. The participation of polyamines in early events evoked by growth factors was shown by a significant stimulation of ornithine decarboxylase and S-adenosylmethionine decarboxylase activity as well as increased concentration of spermidine and spermine in L6 cells exposed to TGF-alpha and EGF. 3. TGF-beta 1 at a high concentration (1 ng/ml) increased protein synthesis in L6 myoblasts but inhibited it in fetal bovine myoblasts. Metabolic effects of TGF-beta 1 in L6 cells was associated with an enhancement of decarboxylase activities, however there were no significant changes in cellular polyamine concentrations. Presented data suggest that polyamines are involved in the signal transduction pathway of EGF, TGF-alpha, and -beta 1 in L6 and fetal bovine myoblasts.

Growth inhibition of oestrogen receptor-positive human ovarian carcinoma by anti-oestrogens in vitro and in a xenograft model

This paper presents results of the in vitro and in vivo effects of anti-oestrogens on the growth of human ovarian cancer cells. Tamoxifen and the "pure" anti-oestrogens, ICI 164,384 and ICI 182,780, inhibited the oestrogen-stimulated growth of the oestrogen receptor (ER)-positive PE04 and PE01 cell lines grown in culture, the latter two compounds being more potent than tamoxifen. In the absence of 17 beta-oestradiol (E2), tamoxifen, but not the pure anti-oestrogens, produced a small degree of growth stimulation in the PE01 and PE04 lines at concentrations between 10((7) and 10(-9) M. In contrast, growth of the ER-negative PE014 line was unaffected by E2 and all three anti-oestrogens. The effects of tamoxifen and ICI 182,780 on PE04 cells grown as xenografts in nude mice were also studied. Both anti-oestrogens produce significant growth inhibitory effects. These results indicate that ovarian carcinoma cells may be sensitive to anti-oestrogens in vitro and in vivo, and support the view that anti-oestrogens merit further clinical studies in patients with ER-positive tumours.

Comparison of metabolic effects of EGF, TGF-alpha, and TGF-beta 1 in primary culture of fetal bovine myoblasts and rat L6 myoblasts

1. Comparative studies of EGF, TGF-alpha, and TGF-beta 1 action on the synthesis of DNA and cellular proteins in rat L6 myogenic cells and fetal bovine myoblasts demonstrated considerable differences between particular growth factors, dependent on dose and target cells. 2. Among examined growth factors only EGF exerted mitostimulatory action, more pronounced at lower concentrations. EGF, progressively with dose, stimulated protein synthesis much more effectively in fetal bovine myoblasts than in L6 cells. 3. The dynamics of stimulation of protein synthesis by TGF-alpha was greater than by EGF in both examined types of cell cultures. 4. The maximal response of fetal bovine myoblasts to TGF-alpha in a concentration of 100 ng/ml reached 370%, whereas EGF in a 10 times higher concentration stimulated protein synthesis only to 123% of control. 5. In contrast to EGF, TGF-alpha significantly inhibits DNA synthesis. Inhibition of the mitogenic response with simultaneous stimulation of protein synthesis by TGF-alpha may indicate changes toward cell differentiation. 6. TGF-beta 1 in smallest concentration inhibits both DNA and protein synthesis. The suppressive action of TGF-beta 1 was more distinct in fetal bovine myoblasts than in the L6 cell line. 7. Increasing concentrations of TGF-beta 1 diminished its inhibitory effect, even leading to stimulation of protein synthesis at higher doses in L6 myoblasts.

Contrasting effects of 17 beta-estradiol on the growth of human ovarian carcinoma cells in vitro and in vivo

A human ovarian adenocarcinoma cell line (PE04) has been established as a xenograft in nude mice. In vitro, this cell line is estrogen receptor (ER)-positive and its growth is stimulated by 17 beta-estradiol at concentrations between 10(-12) and 10(-6) M. When xenografted, PE04 cells remain ER-positive and also possess progesterone receptors (PR); treatment with 17 beta-estradiol reduces the concentration of ER and increases levels of PR. Growth of the xenograft is reduced in ovariectomized animals while implantation of estrogen pellets also results in growth inhibition. Similar treatment with estrogen does not inhibit the ER-negative HOX 60 ovarian xenograft, and stimulates growth of the ER-positive ZR-75-I breast carcinoma xenograft. Serum measurements of 17 beta-estradiol confirm that ovariectomy reduces the level of 17 beta-estradiol while implantation of estrogen pellets results in raised levels of the hormone. Tamoxifen inhibits growth of the PE04 xenograft but not that of the HOX 60 xenograft, consistent with ER status. These results indicate that ER-positive PE04 ovarian cancer cells are sensitive to 17 beta-estradiol in vivo but that the response may be of a different type from the in vitro response. This lends further support to the concept that ovarian cancer may be hormone-sensitive and potentially responsive to endocrine therapy.