Autocrine action of amphiregulin in a colon carcinoma cell line and immunocytochemical localization of amphiregulin in human colon.

Amphiregulin (AR) is a newly discovered glycosylated, 84-amino acid residue polypeptide growth regulator which has sequence homology to the EGF family of proteins. To obtain immunological reagents to study the biological role of AR, two synthetic peptides containing sequences corresponding to distinct regions of AR were used to generate polyclonal antibodies in rabbits. One preparation of antipeptide antibodies directed against residues 26-44 of AR (AR-Ab2) was most effective in the detection of native AR, whereas another preparation of antibodies against residues 8-26 (AR-Ab1) was found to be most efficacious in the detection of AR in formalin-fixed and paraffin-embedded tissues. The growth of a colon carcinoma cell line, Geo, which proliferates autonomously under serum-free conditions, was stimulated by the exogenous addition of AR or EGF. Half-maximal stimulation of this growth was observed at 40 and 200 pM of EGF and AR, respectively. A mAb to the extracellular domain of the EGF receptor blocked the stimulation of cell proliferation induced by the exogenous addition of AR, suggesting that this stimulation was mediated via the EGF receptor. Geo cells were found to constitutively express significant levels of the AR mRNA transcript as determined by analysis of the polymerase chain reaction-amplified cDNA product and AR protein was detected immunocytochemically using the AR-Ab1 antibodies in these cells. AR was immunoprecipitated specifically using the AR-Ab2 antibodies from the conditioned medium of Geo cells, which had been metabolically labeled with [35S]cysteine. The secreted AR migrated as a broad band (18.5-22.5 kD) with a median molecular weight of approximately 20.7 kD in SDS-PAGE. Immunospecific removal of AR from serum-free medium conditioned by the Geo cells and readdition of the AR-depleted medium to Geo cells resulted in an approximately 40% inhibition of cell growth relative to controls. Furthermore, the growth of the Geo cells was also inhibited by approximately 50% by the addition of the anti-EGF receptor mAb alone. These results indicate that AR and the EGF receptor are involved in the autocrine growth of these cells and suggests that AR may act through the EGF receptor via an extracellular autocrine loop. To study the expression of AR in human colon in vivo, AR was localized immunocytochemically in formalin-fixed, paraffin-embedded sections from normal and malignant human colon using the AR-Ab1 antibodies.(ABSTRACT TRUNCATED AT 400 WORDS)

Characterization of exogenous type D retrovirus from a fibroma of a macaque with simian AIDS and fibromatosis.

A novel type D retrovirus was isolated by cocultivation of explants of fibromatous tissue from a rhesus monkey (Macaca mulatta) with immunodeficiency and retroperitoneal fibromatosis. This type D virus, isolated from a macaque with simian acquired immunodeficiency syndrome (SAIDS-D/Washington), is exogenous and is partially related to the Mason-Pfizer and the langur monkey type D viruses. The SAiDS-D virus can be distinguished from all other primate retroviruses by antigenicity and molecular hybridization. Nucleic acid hybridization studies reveal that the origin of the SAIDS-D isolate may reside in Old World monkey (subfamily Colobinae) cellular DNA.

Histopathology of breast lesions induced in BUF rats of varying ages by ingestion of N-4-(4'-fluorobiphenyl) acetamide.

Inbred BUF male and female rats 4, 12, 24, and 52 weeks old ingested 0.04 percent N-4-(4'fluorobiphenyl)-acetamide in a semisynthetic diet for 36 weeks. They were killed 12 weeks later. Susceptibility to mammary carcinogenesis was related to the age and sex of the animals. Younger female rats developed more mammary tumors. Approximately half of these mammary tumors were well-differentiated adenocarcinomas; the remainder were either poorly differentiated or anaplastic adenocarcinomas.

Epidermal growth factor receptor signaling and the invasive phenotype of ovarian carcinoma cells.

BACKGROUND: Most (70%-100%) ovarian carcinomas express high levels of the epidermal growth factor receptor (EGFR). To examine the relationship between EGFR and the invasive phenotype, we assessed integrin expression, adhesion, matrix metalloproteinase (MMP) activity, and migration in ovarian cancer cells in which EGFR expression was modified. METHODS: NIH:OVCAR-8 human ovarian carcinoma cells were transfected with an expression vector containing the human EGFR complementary DNA in an antisense orientation (EGFR-antisense cells) or the vector alone (vector control cells). We compared vector control and EGFR-antisense cells for cell morphology and adhesion by light microscopy, expression of alpha(6)- and alpha(3)-integrin subunits by flow cytometry, MMP and tissue inhibitor of MMP (TIMP) activity by zymography, and migration by a wound migration assay. In some experiments, EGFR kinase activity in parental cells was inhibited by treatment with PD153035. All statistical tests were two-sided. RESULTS: EGFR-antisense cells were morphologically distinct from vector control cells and had a selective decrease in adhesion to laminin-1 that was not observed with vector control cells (P = .008) or on other extracellular matrix substrates. Compared with vector control cells, cell surface alpha(6)-integrin expression decreased by approximately 80% (difference = 78.7%; 95% confidence interval [CI] = 77.8% to 79.6), MMP-9 activity decreased by approximately 50%, and TIMP activity increased by approximately 50% in EGFR-antisense cells. Vector control cells were highly motile (5.51 arbitrary distance unit; 95% CI = 4.98 to 6.04), whereas the EGFR-antisense cells were not (0.99 arbitrary distance units; 95% CI = 0.38 to 1.60). The morphology and integrin profile of NIH:OVCAR-8 parental cells treated with PD153035 were similar to those of the EGFR-antisense cells. CONCLUSIONS: Reduced EGFR expression in ovarian carcinoma cells decreased their adhesion to laminin-1, expression of the alpha(6)-integrin subunit (a well-characterized laminin-1 receptor), and MMP-9 activity. These data support the hypothesis that EGFR overexpression in ovarian cancer cells results in multiple phenotypic changes that enhance the invasive phenotype.

Murine type C retroviruses and intracisternal A-particles in human tumors serially passaged in nude mice.

An ultrastructural survey of 11 human tumors passaged in N:NIH(S) (nu/nu) mice showed two instances of type C virus production. In one instance type C virus particles were observed in the endothelial murine stromal cell component of an embryonal carcinoma but not in the human tumor cells. In another instance type C virus particles were seen replicating in the chondroblastic human cells of a xenografted osteosarcoma. The type C virus produced in the human cells failed to transform NIH/3T3 cells, the C-127 rat cell line, or mink cells. Nucleic acid hybridization studies in which a human endogenous retroviral probe and a xenotropic murine leukemia virus envelope probe were used suggested that the retrovirus present in the human osteosarcoma cells is related to murine leukemia viruses. Intracisternal A-particles (IAP) were also detected in the human osteosarcoma cells. Their presence in the human cells was demonstrated by simultaneous visualization of IAP and human HLA determinants at the cell surface. The literature on type C virus infection of human cells and tumors grafted in nude mice is reviewed.

Urinary transforming growth factors in neoplasia: separation of 125I-labeled transforming growth factor-alpha from epidermal growth factor in human urine.

Purified human epidermal growth factor (hEGF) from urine promotes anchorage-independent cell growth in soft agar medium. This growth is enhanced by transforming growth factor-beta (TGF-beta), and is specifically inhibited by hEGF antiserum. Transforming growth factors of the alpha type (TGF-alpha), potentially present in normal human urine or urine from tumor-bearing patients, also promote anchorage-independent cell growth and compete with EGF for membrane receptor binding. Consequently, TGF-alpha cannot be distinguished from urinary hEGF by these two functional assays. Therefore, a technique for separation of TGF-alpha and related peptides from urinary EGF based on biochemical characteristics would be useful. Radioiodination of characterized growth factors [mouse EGF (mEGF), hEGF, and rat TGF-alpha (rTGF-alpha)], which were then separately added to human urine, was used to evaluate a resolution scheme that separates TGF-alpha from the high level of background hEGF present in human urine. Commercially available methyl bonded microparticulate silica efficiently adsorbed the 125I-labeled mEGF, 125I-labeled hEGF, and 125I-labeled rTGF-alpha that were added to 24-h human urine samples. Fractional elution with acetonitrile (MeCN) of the adsorbed silica released approximately 70 to 80% of the 125I-labeled mEGF and 125I-labeled hEGF between 25 and 30% MeCN, and over 80% of the 125I-labeled rTGF-alpha between 15 and 25% MeCN, with retention after dialysis of less than 0.2 and 1.7% of the original urinary protein, respectively. Consequently, a single-step enrichment of about 400-fold for mEGF and hEGF, and 50-fold for rTGF-alpha were achieved rapidly. Subsequent Bio-Gel P-10 chromatography indicated that 125I-labeled mEGF and 125I-labeled hEGF eluted later than would be predicted on the basis of their reported molecular weight of approximately 6000, whereas 125I-labeled rTGF-alpha eluted from Bio-Gel P-10 at an approximate molecular weight of 8000 to 9000. 125I-labeled rTGF-alpha bound to carboxymethyl cellulose and eluted at a less acidic pH than did hEGF. On reverse phase high performance liquid chromatography using a linear gradient of 18 to 35% MeCN over 120 min, 125I-labeled rTGF-alpha was comparatively hydrophilic, eluting at 22% MeCN in contrast to the more hydrophobic 125I-labeled hEGF, which eluted at 27% MeCN. These observed biochemical differences between hEGF and TGF-alpha provide a rationale for resolution of these and perhaps other related putative transforming growth factors from bulk urine of tumor-bearing patients.

Variant forms of rat epidermal growth factor present in the urine of nude rats bearing human tumors.

Epidermal growth factor (EGF) receptor-binding peptides from the urine of tumor patients have been reported to differ in molecular weight and relative hydrophobicity from those of normal individuals. Nude rats bearing human large cell lung carcinomas or chondrosarcomas and non-tumor-bearing sibling control rats were used to investigate the contributions of tumor and host to urinary EGF-related peptide growth factors. Peptides were adsorbed from urine onto methyl-bonded silica and eluted according to their relative hydrophobicity by a stepwise gradient of aqueous acetonitrile. Total EGF receptor-binding activity relative to urinary creatine was elevated in the urine of only one group of tumor-bearing rats. However, the proportion of relatively hydrophilic activity was increased markedly in all three groups of tumor-bearing rats. Rats bearing a large cell lung cancer excreted unusually hydrophilic Mr 6000 peptides that were chromatographically similar to transforming growth factor alpha on reverse phase high performance liquid chromatography but proved to be rat EGF by radioimmunoassay (RIA). EGF receptor-binding activity that was common to the urine of tumor-bearing animals regardless of tumor type, but more hydrophilic than that from control rats, had Mr 60,000, 30,000, 12,000, and 4,000 to 7,000 components. All reacted fully in the rat EGF RIA and were negative for human EGF and transforming growth factor alpha by RIA. A more hydrophobic fraction of EGF receptor-binding activity, common to control and tumor-bearing animals, contained Mr 33,000, 5,000 to 7,000, and 2,000 to 5,000 components. High performance liquid chromatography and gel electrophoresis of the Mr 33,000 activity revealed a high molecular weight rat EGF comparable to that reported in human urine. No human EGF or transforming growth factor alpha was detected by RIA in any of the active fractions from tumor-bearing rat urine. Thus, all EGF receptor-binding activity appeared to derive from rat EGF produced by the rat host and not by the xenografted tumors.

Differential modulation of human chorionic gonadotropin production by methotrexate in normal and malignant placental cultures and its increase by dibutyryl cyclic adenosine monophosphate and/or actinomycin D in normal cultures.

The influence of methotrexate (MTX), dibutyryl cyclic AMP, and actinomycin D on production of human chorionic gonadotropin (HCG) in normal first trimester human placental organ cultures was compared. Actinomycin D (10(-8) to 10(-6) M) elevated HCG production by as much as 3.5-fold in normal placenta, and a 2-fold increase in HCG levels was obtained by treatment with dibutyryl cyclic AMP (1 mM) and theophylline (1 mM). The combination of dibutyryl cyclic AMP (1 mM) plus theophylline (1 mM) and actinomycin D (10(-8) M) additively enhanced HCG production by 4.5-fold. In contrast, HCG levels in normal placental organ cultures were unaffected by MTX (10(-8) to 10(-5) M) despite several differing treatment regimens. The JAr line of human choriocarcinoma cells, on the other hand, exhibited an 8-fold increase in HCG levels following MTX exposure (10(-7) M). Incorporation of selected radiolabeled precursors of the de novo and salvage pathways of DNA synthesis was evaluated to assess potential metabolic alterations underlying the differential HCG response of these cultures to MTX. Deoxyuridine incorporation into DNA was decreased similarly in both normal and malignant placenta following MTX exposure. However, deoxycytidine incorporation was inhibited by MTX in normal placental cultures but was elevated by as much as 4-fold in JAr cultures exposed to MTX. Thymidine incorporation into DNA was increased in both groups in the presence of MTX; however, thymidine incorporation was more profoundly stimulated (5-fold) in normal placenta than in JAr cultures (2.5-fold). These data indicate dissimilar utilization of the de novo and salvage pathways of DNA synthesis by these cultures which may explain their differential responsiveness to MTX.

The stimulation by methotrexate of human chorionic gonadotropin and placental alkaline phosphatase in cultured choriocarcinoma cells.

Treatment of the BeWo line of choriocarcinoma cells with methotrexate in doses that inhibit DNA synthesis causes a tenfold increase in synthesis of human chorionic gonadotropin and a threefold increase in activity of placental alkaline phosphatase. No concomitant increase in lactic dehydrogenase activity occurs under these conditions. This effect of methotrexate can be blocked by simultaneous addition of thymidine or folinic acid, neither of which alone increases human chorionic gonadotropin synthesis or placental alkaline phosphatase activity in BeWo cells.

Stimulation of human chorionic gonadotropin by JAr line choriocarcinoma after inhibition of DNA synthesis.

Treatment of choriocarcinoma cells (JAr line) for 24 hr with methotrexate, fluorodeoxyuridine, 1-beta-D-arabinofuranosylcytosine, or hydroxyurea, in doses that inhibit DNA synthesis, results in a 2.5- to 12-fold increase in human chorionic gonadotropin (HCG) synthesis. Under the conditions of use, these agents do not significantly depress RNA or protein synthesis. Simultaneous addition of thymidine with methotrexate or fluorodeoxyuridine and of deoxycytidine with 1-beta-D-arabinofuranosylcytosine blocks the HCG stimulation. Despite a rapid inhibition of DNA synthesis, HCG stimulation is gradual and reaches a peak after drug removal. Decline in HCG synthesis is coincident with recovery of DNA synthesis, and there is a positive correlation between the duration of inhibition of DNA synthesis and the amount of HCG increase. Although most of the methotrexate-induced stimulation of HCG synthesis occurs after methotrexate removal, preventing protein synthesis during the exposure to methotrexate abrogates the increase. The stimulation of HCG synthesis by methotrexate is more sensitive to protein synthesis inhibition during the first 12 hr of a 24-hr exposure than it is during the second 12 hr. Thus, in accord with the kinetics, specificity, dose dependence, and protein synthesis requirement, HCG synthesis seems to be stimulated as a direct consequence of inhibition of DNA synthesis, with a requirement for some other protein synthesis-dependent event(s) preceding the stimulation.

Transforming growth factor-alpha acts as an autocrine growth factor in ovarian carcinoma cell lines.

The potential of transforming growth factor-alpha (TGF-alpha) to function as an autocrine growth factor was evaluated in numerous ovarian carcinoma cell lines. All 17 lines which were examined expressed the epidermal growth factor receptor and 16 cell lines, in addition, concomitantly secreted TGF-alpha. Radioimmunoassay of processed serum-free-conditioned medium indicated TGF-alpha concentrations ranging from 16 to 197 pg/ml, or 1.5 to 95 ng/10(8) cells. 125I-TGF-alpha bound to a single class of high-affinity-binding sites on the surface of the cells. The dissociation constant for the 125I-TGF-alpha/epidermal growth factor receptor complex ranged from 0.21 to 5.3 nM with receptor numbers from 3,500 to 96,000/cell, depending upon the cell line. The growth of 8 ovarian cell lines was stimulated in a dose-dependent manner when grown in the presence of exogenous TGF-alpha. Growth in 4 of 5 cell lines capable of serum-free propagation was inhibited from 28 to 56% when cultured in medium containing a TGF-alpha-neutralizing monoclonal antibody. These results support the view that TGF-alpha is an autocrine growth factor for cell lines derived from ovarian cancers of epithelial origin and suggest a potential role for TGF-alpha in the pathogenesis or progression of the disease.

Differential immunohistochemical detection of amphiregulin and cripto in human normal colon and colorectal tumors.

Thirty-six primary human colorectal tumors, 43 noninvolved colon samples that were adjacent to either carcinomas of adenomas, 22 adenomas, and nine normal colon specimens were immunohistochemically examined for the presence and localization of two epidermal growth factor-related peptides, amphiregulin (AR) and cripto. Within the primary tumors, 18 (50%) showed moderate levels of AR expression. Approximately 60% of the tubular and tubulovillous adenomas were positive for AR expression, whereas only 15% of the adjacent, noninvolved colon mucosa expressed AR. A greater proportion of well-differentiated tumors (71%) were positive for AR expression than were poorly differentiated tumors (18%). All of the nine normal colon specimens were positive. Consequently, AR expression appeared to be associated with both normal and malignant epithelial cells that were more differentiated. The distribution of cripto expression was different. Seventy-nine % of the colon tumors expressed cripto with a frequency of expression that was approximately equivalent between well-differentiated and poorly differentiated tumors. Approximately 86% of the tubulovillous adenomas, but only 43% of the tubular adenomas, were positive for cripto expression. In contrast, whereas AR was expressed in normal colon specimens, none of these tissues expressed cripto, and only 12% of the noninvolved normal colon samples adjacent to tumors or adenomas were positive for cripto. Cripto expression therefore appeared related to neoplasia. These data suggest that AR and cripto may be functioning as potential autocrine and/or paracrine growth factors in the colon and that the differential expression of cripto may serve as a potential tumor marker for colonic carcinogenesis.

Human brain tumor-associated urinary high molecular weight transforming growth factor: a high molecular weight form of epidermal growth factor.

Urinary protein obtained from a patient with a highly malignant brain tumor (astrocytoma, grade IV) was adsorbed to trimethylsilyl controlled-pore glass beads and selectively eluted with acetonitrile to yield a high molecular weight (HMW) human transforming growth factor (hTGF). This HMW hTGF promoted clonogenic cell growth in soft agar and competed for membrane receptors with mouse epidermal growth factor. After surgical resection of the tumor, no HMW hTGF was found in urine. HMW hTGF generated a human EGF (hEGF) radioimmunoassay competitive binding curve similar to that of hEGF and parallel to that of a highly purified HMW form of hEGF previously reported to be present in trace concentrations in normal human urine. Both hEGF and HMW hEGF were clonogenic in soft agar, and their clonogenic activity as well as that of HMW hTGF was inhibited by anti-hEGF serum. Both HMW hTGF and HMW hEGF had 20 to 25% of the radioreceptor binding activity of hEGF. HMW hTGF purified from the pooled urine of several patients with malignant astrocytomas and HMW hEGF purified from normal control urine comigrated at Mr 33,000. Thus, HMW hTGF was indistinguishable from HMW hEGF in terms of apparent molecular size, epidermal growth factor receptor binding activity, epidermal growth factor immunoreactivity, and clonogenic activity. Urinary HMW hEGF/hTGF may be of tumor cell origin or may represent a response of normal host tissues to the tumor or its products.

Identification of DNA in the core component of avian myeloblastosis virus.

Avian myeloblastosis virus (AMV) was found to contain DNA associated with the virion. The viral envelope was removed by treating the virus with a nonionic detergent and the DNA was found in the core fraction. These experiments indicate that the DNA associated with tumor virus is not contaminant associated with the viral envelope and suggest that the DNA is part of the internal core component. The DNA from avian myeloblastosis virus has a density of 1.70 g/cm3.

The processing and intracellular transport of myeloperoxidase. Modulation by lysosomotropic agents and monensin.

Myeloperoxidase, stored in azurophil granules of neutrophils, is synthesized in promyelocytes as a larger molecular weight precursor, which is processed to yield a transient Mr 82 000 intermediate and mature polypeptides with molecular weights of 62 000 and 12 000. We have tried to define subcellular sites for processing using metabolic labelling of the promyelocytic leukemia cell line HL-60 in combination with subcellular fractionation on a Percoll gradient. A reasonable separation was achieved between azurophil granules, Golgi elements and endoplasmic reticulum. The finding of almost exclusively fully processed myeloperoxidase in granules and a mixture of unprocessed and processed polypeptide in fractions enriched in Golgi elements suggests that processing occurred mainly in pregranular structures. Monensin, which exchanges protons for Na+, and the base chloroquine blocked processing probably by inhibition of transport through the Golgi apparatus. However, the lysosomotropic NH4+ cation did not inhibit processing or transport indicating that processing is not necessarily influenced by pH-dependent mechanisms. Results from digestion with endoglycosidase H, incubation with tunicamycin and metabolic labelling with [3H]mannose indicated that myeloperoxidase contained high mannose oligosaccharide side chains. Also [32P]phosphate incorporated into Mr 90 000 and Mr 62 000 myeloperoxidase was susceptible to endoglycosidase H indicating that oligosaccharide side chains are modified by phosphorylation as in lysosomal enzymes. Thus, even if myeloperoxidase contained mannose 6-phosphate residues, these may not necessarily be involved in directing transport to the azurophil granules.

Differential modulation of human chorionic gonadotropin secretion by epidermal growth factor in normal and malignant placental cultures.

The ability of epidermal growth factor (EGF) to modulate the secretion of human chorionic gonadotropin (hCG) in both normal and malignant placental cells was compared. Receptors for EGF were present on the JAr line of choriocarcinoma cells and were localized to the trophoblast cells of normal placental organ cultures as detected by immunofluorescence. Despite the presence of EGF receptors, the normal placenta did not respond to EGF by significantly increasing its levels of hCG production. The JAr line of choriocarcinoma exhibited a 2-fold increase in hCG secretion after the addition of EGF. EGF stimulated growth in the JAr cells, as measured by the protein content of the cultures, but did not elevate the incorporation of [methyl-3H]thymidine in either the JAr cells or placental organ cultures.

Inducible antisense inhibition of erbB-2 expression reduces anchorage independent growth of ovarian carcinoma cells.

We have investigated the effect of c-erbB-2 expression on the growth of ovarian carcinoma cell lines using antisense methodology. A 1.5 kb fragment of c-erbB-2 cDNA was cloned in an antisense and sense orientation into an IPTG inducible vector. These vectors were stably transfected into two ovarian carcinoma cell lines, one of which (NIH:OVCAR-8) grew well in soft agar. Inhibition of expression of endogenous c-erbB-2 protein was detected by immunoprecipitation and Western blot in both of the induced transfectants with the antisense construct. Although growth in monolayer culture was unaffected, NIH:OVCAR-8 cells transfected with the antisense construct and induced with IPTG lost their ability to form colonies in soft agar. Consequently, endogenous expression of c-erbB-2 modulates anchorage-independent growth of NIH:OVCAR-8.

mRNA phenotyping of the major ligands and receptors of the EGF supergene family in human ovarian epithelial cells.

mRNA amplification phenotyping (MAPPing) was used to determine the level of mRNA expression of the major EGF-related ligands (EGF, TGF-alpha, and Amphiregulin) and receptors (EGF-receptor and erbB-2) of the EGF supergene family in three ovarian carcinoma lines (OVCA 429 and 433, and NIH:OVCAR-8) under serum-supplemented and reduced serum (minimal medium with 2% fetuin) growth conditions. mRNA levels of TGF-alpha, EGF-R, and erbB-2 were particularly high, and increased approximately 2-3 orders of magnitude when grown in serum, consistent with an autocrine involvement of these genes in ovarian epithelial growth in vitro. Moreover, even when grown without serum, OVCA 429 and NIH:OVCAR-8 expressed elevated levels of mRNA for erbB-2.

ErbB receptor expression and growth response to heregulin beta 1 in five ovarian carcinoma lines.

SKOV-3, NIH:OVCAR-3, NIH:OVCAR-8, Ovca 429 and Ovca 433 ovarian carcinoma cell lines were examined to correlate biological behavior (growth in monolayer and soft agar) with erbB family receptor expression levels and response to recombinant Heregulin beta1 (Hrg). While all lines expressed variable amounts of each receptor, erbB-3 and to a lesser extent erbB-2 were constitutively tyrosine phosphorylated in all lines. Hrg beta1 treatment enhanced only erbB-3 tyrosine phosphorylation; however, the addition of Hrg in low serum did not stimulate ovarian cell growth, unlike all three breast cancer cell lines examined. In addition, all five of the ovarian carcinoma cell lines expressed Hrg mRNA by RT-PCR, unlike two of the three breast cancer cell lines. These results suggest the apparent importance of erbB-3 and endogenous Hrg in ovarian carcinoma cell growth in vitro.

An albumin-like protein is the major secretory protein of ovarian epithelial cells in vivo and in vitro.

Contemporary experimental techniques were used to evaluate the protein secretion of ovarian epithelium. The protein composition of 14 ovarian cyst fluids (OCF) from either cystadenomas or cystadenocarcinomas, and conditioned media (CM) from seven ovarian carcinoma lines in culture, were analyzed by SDS-PAGE under reducing conditions, and Western immunoblots. The major protein common to all the above samples was a 65 kDa protein that, by densitometry, constituted between 43% and 77% of OCF protein and 19% and 38% of CM protein. By Western blot analysis, this band was immunologically related to human albumin. Moreover, immunoreactivity to albumin was demonstrated in ovarian epithelium in vivo. Ovarian epithelium synthesizes and releases an albumin-like protein that constitutes the major secretory protein. This may suggest an osmotic mechanism for cyst enlargement in ovarian cystadenomas.