Impact of BMI on the incidence of metabolic abnormalities in metabolically healthy men.

OBJECTIVES: Although the existence of metabolically healthy obese (MHO) individuals has been recognized, little is known regarding metabolic health status in these subjects over time. Thus, we evaluated longitudinal changes in metabolic parameters among MHO subjects compared with metabolically healthy, normal-weight (MHNW) subjects. METHODS: A cohort study was performed on 2599 Korean men, 30-59 years of age, with no evidence of fatty liver disease on ultrasound and no traits of metabolic syndrome at baseline. BMI was categorized based on criteria for Asian population. Study participants were followed annually or biennially between 2002 and 2009. At each visit, the fatty liver on ultrasound was assessed and metabolic abnormalities were measured. Parametric Cox models and a pooled logistic regression models were used to evaluate the relationships of BMI with incident metabolic abnormalities. RESULTS: During 9647.1 person-years of follow-up, 1673 participants developed metabolic abnormalities. After adjusting for age, smoking, alcohol intake and exercise, higher baseline BMI categories predicted increased incidences of metabolic abnormalities in a dose-response manner. The hazard ratios (95% confidence intervals) for hypertriglyceridemia, prediabetes, pre-hypertension, low high-density lipoprotein-cholesterol, fatty liver, elevated high sensitivity-C reactive protein, elevated homeostasis model assessment of insulin resistance, any metabolic abnormality and metabolic syndrome among the MHO subjects compared with the MHNW subjects were 1.51 (1.23-1.85), 1.43 (1.19-1.72), 1.79 (1.45-2.22), 1.80 (1.30-2.49), 2.69 (2.19-3.31), 1.39 (1.16-1.67), 2.90 (2.31-3.62), 1.68 (1.45-1.93) and 1.84(1.02-3.30), respectively. CONCLUSION: In this study, MHO individuals showed higher incidences of metabolic abnormalities compared with MHNW individuals. This suggests that initially MHO individuals undergo adverse metabolic changes associated with obesity over time.

Concurrent delivery of GM-CSF and B7-1 using an oncolytic adenovirus elicits potent antitumor effect.

Oncolytic adenoviral vectors are currently being developed as biologic anticancer agents. Coupling the lytic function of an oncolytic adenovirus (Ad) with its ability as a transgene delivery system represents a powerful extension of this methodology. A clear advantage is the amplification of a therapeutic gene, as replicating vectors would be able to infect and deliver the gene of interest to neighboring cells. Granulocyte-macrophage colony-stimulating factor (GM-CSF) is one of the most potent stimulators of a specific and long-lasting antitumor immunity and its important role in the maturation of antigen-presenting cells to induce T-cell activation has been well documented. Similarly, the B7 family has also been shown to play an integral role in mediating an antitumor response. Most tumor cells, however, lack the expression of these costimulatory molecules on their surface, thus escaping immune system recognition. To increase the antitumor effect of an oncolytic Ad, we have generated an E1B 55 kDa-deleted oncolytic adenoviral vector, YKL-GB, that expresses both GM-CSF and B7-1. The therapeutic efficacy of YKL-GB Ad was evaluated in immunocompetent mice bearing murine melanoma B16-F10 tumors. Significant inhibition of tumor growth was seen in mice treated with YKL-GB compared to those treated with the analogous vector, YKL-1. Moreover, YKL-GB oncolytic Ad demonstrated enhanced antitumor activity and higher incidences of tumor regression compared to a replication-incompetent Ad, dl-GB, which coexpresses GM-CSF and B7-1. Localized GM-CSF and B7-1 gene transfer also conferred long-lasting immunity against a tumor re-challenge. To establish that the observed antitumor effect is associated with the generation of a tumor-specific immune response, we carried out interferon-gamma enzyme-linked immune spot assay. We observed that YKL-GB induced significantly higher immune cell activation than YKL-1. Furthermore, immunohistochemical studies demonstrated robust dendritic cells and CD4(+)/CD8(+) T-cell infiltration in these mice compared to the YKL-1-treated groups. In agreement with these results, splenocytes from tumor-bearing mice treated with YKL-GB expressed high levels of the costimulatory and activation molecules. These findings demonstrate the effectiveness of enhancing the immune response against tumors with an oncolytic Ad expressing both GM-CSF and B7-1 and provide a potential therapeutic strategy for the management of neoplasia.

Induction of apoptosis in non-small lung carcinoma cell line (H1299) by combination of anti-asthma drugs with gemcitabine and cisplatin.

Gemcitabine and cisplatin are commonly used in chemotherapy, however, these drugs may cause severe cytotoxic side effects. Theophylline and aminophylline are commonly used as anti-asthma drugs and can block anti-phosphodiesterase activity. We examined whether these methylxanthins could effect lung cancer cell survival and synergise with gemcitabine and cisplatin to induce apoptosis. We found that theophylline induced apoptosis in the cultured H1299 cell line already at concentrations of 30 microg/ml, reaching an ED50% at 100 microg/ml. In contrast, aminophylline induced apoptosis at concentrations of 300 microg/ml and 17% apoptosis was evident at concentrations as high as 900 microg/ml, which is a lethal dose for in vivo treatment. Cisplatin induced apoptosis with ED50% of 0.8 microg/ml, while gemcitabine induced apoptosis with ED50% of 20 ng/ml. Using a combination of 20 microg/ml of theophylline (calculated as an effective but not toxic anti-asthma drug) with 10 ng/ml gemcitabine or with 0.3 microg/ml cisplatin significantly elevated incidence of apoptosis compared to gemcitabine or cisplatin alone at similar concentrations. In contrast, an observed synergistic effect between aminophylline and gemcitabine was evident only at concentrations of 80 microg/ml and 10 ng/ml respectively. However, no effect was apparent in combination doses of aminophylline (80 microg/ml) with cisplatin (0.3 microg/ml). The combined treatments involved reduction in the intracellular level of the anti-apoptotic Bcl-2 gene product. This corresponded with the extent of apoptosis induced by the various drug combinations. Thus, theophylline is significantly more effective than aminophylline in increasing the sensitivity of the H1299 lung cancer cells to the induction of cell death by gemcitabine and cisplatin. Thus, combination of theophylline with these drugs may permit a reduction in the effective dose needed in chemotherapy treatment of lung cancer patients.

Involvement of p53 expression in cAMP-mediated apoptosis in immortalized granulosa cells.

In the accompanying paper we described the induction of apoptosis by extended cyclic AMP (cAMP)-mediated signals in primary granulosa cells and the reduction in this process in transformed cells expressing SV40 T antigen. In the present work, we examined the effect of overexpression of either wild-type or mutant p53 on cAMP-mediated apoptosis in steroidogenic granulosa cell lines transfected with SV40 DNA together with the Ha-ras oncogene and a temperature-sensitive variant of p53, p53val135. In cell lines expressing low amounts of T antigen and high amounts of p53val135, growth arrest was induced by transferring the cells from 37.5 degrees to 32 degrees C, a temperature which allows the manifestation of the wild-type phenotype of p53 and the induction of the WAF1 gene. While nonstimulated cells showed only a very modest apoptotic process, rapid and massive apoptosis was evident in cells stimulated by forskolin at 32 degrees C. The presence of serum could delay, but not abolish, this phenomenon. Progesterone production in such cells treated with cAMP was significantly higher at 32 degrees C than at 37.5 degrees C, suggesting that wild-type p53 can also enhance granulosa cell differentiation. Furthermore, at least at early stages, apoptosis is correlated with increased cell differentiation. On the other hand, in lines expressing high amounts of T antigen and low amounts of p53, neither an increase in cAMP-induced differentiation nor massive apoptosis was seen at 32 degrees C. These findings demonstrate that wild-type p53 can cooperate with cAMP-generated signals in the induction of steroidogenesis and of programmed cell death in granulosa cells.

Transfection of a differentiated human hepatoma cell line (Huh7) with in vitro-transcribed hepatitis C virus (HCV) RNA and establishment of a long-term culture persistently infected with HCV.

T7 RNA polymerase transcripts of a putative full-length cDNA clone of hepatitis C virus type 1 (HCV-1) were used to transfect a differentiated human hepatoma cell line, Huh7. The transfected genome replicated in cells, as evidenced by the appearance of progeny HCV RNA, detection of negative-strand viral RNA, and incorporation of [3H]uridine into the viral genome. Incubation of naive Huh7 cells with conditioned medium from transfected cells resulted in a new HCV infection, suggesting the production of biologically active virus in the inoculum. Maintenance of the transfected cells under serum-free culture conditions resulted in the selection of persistently infected cells which displayed a distinctive cellular morphology. This is the first demonstration that HCV RNA produced from cloned HCV cDNA is infectious and replication competent. This approach should provide a valuable system for studying HCV replication, persistence, and pathogenicity.

Introduction of a gonadotropin receptor expression plasmid into immortalized granulosa cells leads to reconstitution of hormone-dependent steroidogenesis.

We have recently succeeded in immortalizing rat granulosa cells by co-transfection with SV-40 DNA and the Ha-ras oncogene. These cells lost their response to gonadotropins, but expressed the cytochrome P450scc mitochondrial system enzymes and produced progesterone and 20 alpha-hydroxy-4-pregnan-3-one (20 alpha-OH-P) upon cAMP stimulation (Suh, B. S., and A. Amsterdam. 1990. Endocrinology. 127:2489-2500; Hanukoglu, I., B. S. Suh, S. Himmelhoch, and A. Amsterdam. 1990. J. Cell Biol. 111:1973-1981). In an attempt to restore the steroidogenic response to gonadotropins in immortalized cells, lutropin/choriogonadotropin (LH/CG-R) receptor expression plasmid was prepared by introducing the complete coding region of LH receptor cDNA (McFarland, K. C., R. Sprengel, H. S. Phillips, M. Köhler, N. Rosemblit, K. Nikolics, D. L. Segaloff, and P. H. Seeburg. 1989. Science (Wash. DC). 245:494-499) into a SV-40 early promoter based eucaryotic expression vector. Granulosa cells from preovulatory follicles were transfected with this LH receptor expression plasmid, together with SV-40 DNA and the Ha-ras oncogene. Cell lines obtained after this triple transfection accumulated cAMP in a dose-dependent manner in response to hCG. Moreover, they produced progesterone and 20 alpha-OH-P upon hCG stimulation with an ED50 of 125 pM and 75 pM, respectively, which is within the physiological range. Concomitantly with hCG induced differentiation, inhibition of cell proliferation was evident following stimulation with hormone concentrations as low as 40 pM. The number of hCG receptor sites per cell after numerous passages and several freezing and thawing cycles was 1.9 x 10(4), they showed a Kd of 180 pM. Stimulation with hCG induced pronounced morphological and biochemical changes in these cells including formation of mitochondrial located adrenodoxin, a marker enzyme for enhanced steroidogenesis. These findings make possible the expression in immortalized granulosa cells, of selectively mutated receptor molecules which preserve their steroidogenic potential, thereby opening the way to analysis of structure-function relationships of the receptor molecule.

Adenosine 3',5'-monophosphate suppresses metastatic spread in nude mice of steroidogenic rat granulosa cells transformed by simian virus-40 and Ha-ras oncogene.

8-Bromo-cAMP and substances elevating cAMP levels within cells, such as forskolin, cholera toxin, and Bordetella pertussis-invasive adenylate cyclase (BPAC), suppress the growth of cultured granulosa cells cotransfected by simian virus-40 (SV40) DNA and Ha-ras oncogene concomitantly with the induction of steroidogenesis and without affecting oncogene expression. We, therefore, tested the hypothesis that cAMP can modulate tumorigenesis and metastatic spread of these cells in vivo. The cotransfected cells induced rapid development of tumors when injected sc in nude mice. Tumor development was faster in less differentiated cotransfected cells originating from preantral ovarian follicles than in those obtained from highly differentiated transformed cells originating from preovulatory follicles. Cells transfected by SV40 DNA alone produced only slow-growing small tumors. Metastatic lesions of cotransfected cells were most abundant in lung and less frequent in ovaries, kidney, and spleen. No metastatic lesions were found in the liver. However, metastatic spread was dramatically suppressed when cotransfected cells injected into nude mice were pretreated with the invasive BPAC. In contrast, no suppression of metastases was observed when the cells were pretreated with 8-bromo-cAMP, forskolin, or cholera toxin. Removal of forskolin in cultured cotransfected cells yielded a rapid decrease in cAMP levels. In contrast, high levels of cAMP persist in cell cultures even several hours after 1-h pretreatment and subsequent removal of BPAC from the medium of culture cotransfected cells. It is suggested that the inhibitory effect of BPAC on the metastatic spread of these cells is due to prolonged elevation of cAMP in vivo. The newly established granulosa cell lines transformed by SV40 and the Ha-ras oncogene can serve as a model for further studies of cAMP modulation of carcinogenesis in ovarian malignancies.

Differentiation-controlled synthesis and binding of thrombospondin to granulosa cells.

Thrombospondin (TSP) is a large glycoprotein, synthesized by several matrix-forming cells and incorporated into their extracellular matrix. In several cell types its presence supports cell growth and proliferation. To investigate the role of this protein in cell differentiation, we studied the hormonal effect of TSP production and receptor-mediated binding to primary granulosa cells prepared from diethylstilbestrol-treated immature female rats. These cells can be induced to differentiate by FSH, 8-bromo-cAMP (8-Br-cAMP), or forskolin. Progesterone production is induced during differentiation, and its level of synthesis is an important manifestation of the differentiated phenotype. We find that undifferentiated granulosa cells synthesize and secrete TSP. The protein comprises about 0.5% of the total cell protein, and it is the major protein secreted in culture. Treatment of the cells with FSH or 8-Br-cAMP reduces TSP production dramatically, and forskolin completely inhibits it. In parallel, we observed that the undifferentiated cells bind TSP specifically with a Kd of 1.8 nM, and the number of binding sites per cell is 1.7 x 10(5). This binding can be prevented by excess TSP or an anti-TSP monoclonal antibody (B7-3). This ability to bind TSP is completely lost after induction of differentiation by FSH or 8-Br-cAMP. Our findings show that both the production and binding of TSP to granulosa cells are tightly controlled by normal cell differentiation and indicate that changes in TSP are correlated with the passage of the cell through the stages of maturation, a passage that also involves changes in cell shape and extracellular interactions and in the steroidogenic capacity of these cells.

Structure-function relationships during differentiation of normal and oncogene-transformed granulosa cells.

Granulosa cells, which nurse the oocyte, luteinize in response to the preovulatory surge of gonadotropins and become a major producer of progesterone during the normal estrous cycle and pregnancy. This process is characterized by a dramatic change in inter- and intracellular organization and modulation of gene expression that leads to enhanced steroidogenesis. Culturing of human, porcine, and rat cells has permitted detailed studies concerning the microenvironment (hormones, growth factors, and extracellular matrices) that control steroidogenesis in a coordinated fashion both in vivo and in vitro. Reorganization of the cytoskeleton--mainly characterized by down-regulation of the actin network, which is associated with changes in cell contacts and intercellular communication--seems to be a prerequisite for up-regulation of the steroidogenic enzymes. These processes can be investigated now in more detail due to the transfection of rat granulosa cells with specific oncogenes, which leads to their immortalization, concomitantly with the preservation of their capacity for inducible steroidogenesis. The effect of oncogene expression on granulosa cell differentiation suggests that different members of the ras oncogene superfamily may be involved in controlling development and luteinization of both normal and transformed granulosa cells. The identification of the specific forms of the ras protooncogene that may be involved in the differentiation of primary granulosa cells remains a challenging objective.

Oncogene-transformed granulosa cells as a model system for the study of steroidogenic processes.

Highly steroidogenic granulosa cell lines were established by transfection of primary granulosa cells from preovulatory follicles with SV40 DNA and Ha-ras oncogene. Progesterone production in these cells was enhanced to levels comparable to normal steroidogenic cells, by prolonged (> 12 h) stimulation with 8-Br-cAMP, forskolin and cholera toxin, which elevate intracellular cAMP. The steroidogenic capacity of individual lines correlated with the expression of the ras oncogene product (p21) and the morphology of the cells. Formation of the steroid hormones was associated with de novo synthesis of the mitochondrial cytochrome P450scc system proteins. Since cholesterol import into mitochondria is essential for steroidogenesis, the expression of the peripheral benzodiazepine receptor (PBR) and the sterol carrier protein 2 was characterized in these cells. The induction of the expression of the genes coding for both proteins appeared to be mediated, at least in part, by cAMP. Stimulation of the PBR by specific agonists enhanced progesterone production in these cells. The phorbol ester 12-O-tetradecanoyl-phorbol 13-acetate (TPA) dramatically suppressed the cAMP-induced steroidogenesis, in spite of enhanced intracellular cAMP levels, suggesting that TPA can modify the effects of cAMP. cAMP stimulation suppressed growth of transformed cells concomitantly with induction of steroidogenesis. The transformed cells lacked receptors for the native stimulants, the gonadotropic hormones. After transfection of the cells with a lutropin (LH) receptor expression plasmid, the LH and hCG response was reconstituted. In these newly established cell lines gonadotropins were able to stimulate the formation of cAMP and progesterone in a dose-dependent manner with an ED50 characteristic of the native receptor. High doses caused desensitization to gonadotropins as observed in normal cells. These newly established oncogene-transformed granulosa cell lines can serve as a useful model to study inducible steroidogenesis and the effect of oncogene expression on this process.

An inducible functional peripheral benzodiazepine receptor in mitochondria of steroidogenic granulosa cells.

Granulosa cell lines, transformed by SV40 T-antigen and Ha-ras oncogene, have recently been established that can produce progesterone at levels comparable to those of highly differentiated cultures of primary granulosa cells (1-4). Here, the hypothesis that these cells contain a mitochondrial benzodiazepine receptor, and that stimulation of the receptor can trigger progesterone production in these cells, was tested. The agonist of the peripheral benzodiazepine receptor, Ro5-4864, produced a 3- to 5-fold stimulation (P less than 0.005) of progesterone production both in differentiated granulosa primary cultures and in the oncogene-transformed cell lines. Ro5-2807 (diazepam, Valium) exerts a similar effect on granulosa cell steroidogenesis while the specific agonist of central benzodiazepine receptor Ro15-4513 was without effect. The effects of Ro5-4864 or Ro5-2807 were not additive to those of gonadotropins and cAMP. Intact isolated mitochondria possessed high-affinity binding sites to [3H]-Ro5-4864 (Kd = 3.03 +/- 0.70 nM), which were enriched by 1 order of magnitude in these organelles compared to total cell homogenate. Bound Ro5-4864 could be competitively displaced with 1 microM unlabeled Ro5-4864 and Ro5-2807, but not with specific ligands of central benzodiazepine receptors Ro15-4513 and Ro15-1788. Prolonged elevation of cAMP in these cells caused a 30% (P less than 0.01) rise in the number of receptors. Mitochondria of NIH 3T3 cells contained only 30-40% (P less than 0.001) of the Ro5-4864 binding sites of mitochondria from steroidogenic cells, whereas yeast mitochondria lacked them completely. The existence of functional peripheral benzodiazepine receptors in mitochondria suggests that they may have a physiological role in the mobilization of cholesterol into mitochondria, and in elevating progesterone production in ovarian cells. The modulation of the interaction between benzodiazepine compounds and the gamma-aminobutyric acid receptor by progesterone metabolites suggests new interrelationships between peripheral and central nervous system receptors sensitive to benzodiazepines.

Establishment of highly steroidogenic granulosa cell lines by cotransfection with SV40 and Ha-ras oncogene: induction of steroidogenesis by cyclic adenosine 3'-5'-monophosphate and its suppression by phorbol ester.

We have established new cell lines from preovulatory follicles of PMSG-treated immature rats by cotransfection of primary cells with SV40 DNA and Ha-ras oncogene. These cell lines secrete progesterone and 20 alpha-hydroxy-4-pregnen-3-one in response to stimulation with 8-bromo-cAMP, forskolin, or cholera toxin at levels similar to primary cultures of granulosa cells (500 ng/10(6) cells/48 h). 12-O-Tetradecanoylphorbol 13-acetate inhibits progesterone production induced by 8-bromo-cAMP (67%, P less than 0.001), forskolin (88%, P less than 0.001), and cholera toxin (75%, P less than 0.001), in spite of enhancing cAMP accumulation (200%, P less than 0.001) in response to forskolin or cholera toxin. LH, FSH, prostaglandins E1 and E2, and PRL do not stimulate progesterone production. The beta-adrenergic agonist, isoproterenol, stimulates significantly both cAMP accumulation (80%, P less than 0.05) and progesterone and 20 alpha-hydroxy-4-pregnen-3-one secretion (70%, P less than 0.05). In contrast to primary cultured cells in which progesterone secretion increases within 90 min of stimulation, in the cell lines progesterone secretion becomes evident only after 12-24 h of stimulation. The stimulation of these lines by forskolin produced a maximum rise in intracellular cAMP levels at 45 min which declined to 50% (P less than 0.001) of this value within 12 h. It was found that cAMP suppressed growth concomitantly with induction of steroidogenesis when cotransfected cells were examined for growth by total cell protein and [3H]thymidine incorporation to DNA. These granulosa cell lines are uniquely suited for further studies of cAMP induction and the role of oncogenes in steroidogenesis.

Regulation of tropomyosin expression in transformed granulosa cell lines with steroidogenic ability.

The expression of the different tropomyosin isoforms was analyzed in primary granulosa cell cultures and in established granulosa cell lines cotransfected with SV40 and Ha-ras DNA which retain a high steroidogenic response to cAMP stimulation. In contrast to normal cells which greatly reduce the expression of all tropomyosin isoforms during development of steroidogenic ability, in the doubly transformed cells only the synthesis of the high molecular weight isoforms nos 2 and 3 was decreased. The expression of isoforms 1 and 5 was elevated in the cotransfected lines and that of tropomyosin 1 was further enhanced by cAMP stimulation. The increased synthesis of tropomyosins 1 and 5 is unique to SV40 transformation, since it was observed also in cells transfected with SV40 DNA alone. These cells displayed a well organized microfilament system, but have lost the ability to differentiate. The reduced expression of tropomyosins 2 and 3 and a poorly organized microfilament system appear to be a dominant feature of both the highly differentiated normal- and transformed-granulosa cells. It is suggested that the switches in tropomyosin isoform expression during development of the steroidogenic phenotype and in cell transformation may account for necessary changes in microfilament organization which accompany these cellular processes.

Induction and mitochondrial localization of cytochrome P450scc system enzymes in normal and transformed ovarian granulosa cells.

After ovulation of an oocyte, granulosa cells of the ovarian follicle differentiate into luteal cells and become a major factor dedicated to the synthesis of the steroid hormone progesterone. We recently established granulosa cell lines by cotransfection of granulosa cells with SV-40 and Ha-ras oncogene. In these cells progesterone secretion can be induced by cAMP as in normal rat granulosa cells. The induction of progesterone secretion is observed only after approximately 24 h and closely follows the delayed but quantitatively dramatic induction of the mitochondrial cytochrome P450scc which catalyzes the first step in steroid hormone biosynthesis. The mitochondrial P450 system electron transport proteins, adrenodoxin and adrenodoxin reductase, are also induced but adrenodoxin shows a faster induction. Immunofluorescence studies show that the three enzymes are induced in all cells and incorporated into all mitochondria uniformly. Electron microscopic examination using immunogold technique further confirms this and reveals that adrenodoxin is predominantly located on the matrix side of the inner mitochondrial membrane. Thus, adrenodoxin, which is a small highly charged protein, shows a distribution similar to P450scc which is an integral membrane protein. The uniformity of the response of the cells provides further evidence for the homogeneity of the cell line and makes this new granulosa cell line a highly promising system for the study of the molecular mechanisms involved in changes in gene expression during the process of granulosa cell differentiation.

Cotransfection of granulosa cells with simian virus 40 and Ha-RAS oncogene generates stable lines capable of induced steroidogenesis.

Cellular and viral oncogenes are usually defined on the basis of their ability to elicit neoplastic transformation. However, oncogene activity has also been implicated in the control of differentiation. We have tested whether transfection of primary cultured granulosa cells with various oncogenes can yield cell lines that maintain their differentiated properties. Primary granulosa cells were prepared from diethylstilbestrol-treated immature female rats and transfected with simian virus 40 (SV40) DNA or with SV40 plus activated human Ha-RAS oncogene. Transfection with SV40 plus Ha-RAS yielded cell lines that lost response to gonadotropins but, after 48 hr of stimulation with isoproterenol, cholera toxin, forskolin, or 8-bromoadenosine 3',5'-cyclic monophosphate (8-Br-cAMP), produced progesterone at levels comparable to those of differentiated primary cells. In contrast, cells transformed only by SV40 lost their ability to produce progesterone. Whereas in primary cell cultures progesterone production was already evident after a 3-hr incubation with 1 mM 8-Br-cAMP, in cotransfected cells progesterone production became evident only after 12 hr. All cotransformed cell lines produced SV40 large tumor antigen as well as human RAS p21 protein. The expression of the expected oncogenes in the various cell lines was confirmed by mRNA analysis. These results suggest that the expression of an activated RAS oncogene in granulosa cells can play a role in preserving inducible steroidogenesis.