Background  Sex differences in drug pharmacokinetics have been well recognized and gender has been considered a risk factor for adverse events to medications. The aim of this study was to investigate the effect of gender on the expression of hepatocellular transport proteins involved in uptake and secretion of organic anions in rat.

PURPOSE:IGF-I serum levels have been demonstrated as being associated with prostate cancer (PCa) and can serve as a predictive factor for the risk of PCa development. However, the role of IGF-II in PCa and its importance as a predictive marker is still unclear. Our aim was to determine PSA and IGF-II serum levels in patients with PCa and benign prostatic hyperplasia (BPH) and to analyse the value of IGF-II as an additional predictive factor in the diagnostics of PCa. METHODS:112 patients who underwent surgery for BPH or PCa (no hormonal treatment, no further malignancies) were included in this study ((I) 38 PCa, PSA < or = 15 ng/ml; (II) 34 PCa, PSA > 15 ng/ml; (III) 40 BPH). Preoperative serum levels of total PSA and total IGF-II were determined by ELFA and ELISA, respectively. RESULTS:PSA levels were (I) 5.7+/-1.9 ng/ml; (II) 25.0+/-11.5 ng/ml and (III) 4.0+/-2.8 ng/ml. (II) was statistically associated with a high grading (2b/3; p = 0.0182), a high Gleason sum score (7-10; p = 0.0049) and a non-organ confined tumor (T3/4; p = 0.0009) compared to (I), all Chi2 test. IGF-II levels were significantly higher in PCa (I+II) compared to BPH (833.8+/-238.9 ng/ml vs. 633.3+/-141.4 ng/ml, p < 0.0001, t-test). Both PSA and IGF-II were associated with tumor staging (p = 0.0097, p = 0.0308; t-test). No significant correlation was observed between PSA and IGF-II levels. Logistic regression analysis revealed that the combination of PSA and IGF-II improves the prediction of tumor staging in PCa (p = 0.0175 and p = 0.0459, Wald test). Additionally, the combination of PSA and IGF-II can significantly increase discrimination between BPH and PCa; each p < 0.0001, Wald test. CONCLUSIONS:This study provides evidence that IGF-II serum levels may serve as an additional parameter for (a) improved determination of tumor staging and (b) better discrimination between BPH and PCa.

DHEA, a steroid of the adrenal gland, is a non-genotoxic hepatocarcinogen of the peroxisome proliferator type in rodents. However, DHEA also exerts anti-carcinogenic effects by reducing the number and proliferation of preneoplastic and neoplastic lesions induced by N-nitrosomorpholine. The mechanism underlying this growth-modulating effect is unclear, and no data are available on DHEA effects on normal liver. Here, we show that DHEA is a liver mitogen, increasing proliferation in rat liver after 3 days of treatment (100 mg/kg body weight per day) as indicated by significantly enhanced expression of cyclin E, PCNA and Ki-67 and an elevated number of mitotic figures. Histological observation of the liver and biochemical evaluation of serum transaminases and bilirubin did not reveal any evidence for cell death, demonstrating that increased proliferation was not due to liver damage. After 2 weeks of DHEA-treatment, proliferation parameters returned to control values and, after 4 weeks, cyclin E and Ki-67 were even lower than in controls. To study the DHEA effect on regenerating liver, we performed partial hepatectomy (PHx) on rats pretreated for 4 weeks with DHEA and analyzed the kinetics of the cell cycle. DHEA-treatment delayed the entry of hepatocytes into G1 phase by about 6 h indicated by a later rise in Ki-67 and cyclin E expression. Reduced STAT-3 activation before G1-phase entry indicates an impaired recruitment of hepatocytes to regenerative proliferation in DHEA-treated livers. The rise in proliferation observed after PHx in DHEA-treated livers was more flat and, in contrast to controls, did not show a peak value within the first 35h as indicated by Ki-67, PCNA, cyclin E and BrdU-incorporation levels in hepatocytes. In conclusion, the results show that DHEA acts as a mitogen in rat liver but reduces the regenerative capacity of the liver.

Abstract Purpose: S100 proteins comprise a family of calcium-modulated proteins that have recently been associated with epithelial tumors. We examined the expression of two members of this family, S100A8 and S100A9, together with the S100 receptor RAGE (receptor for advanced glycation end products) in human prostate adenocarcinomas and in prostatic intraepithelial neoplasia. Experimental Design: Tissue specimens of 75 patients with organ-confined prostate cancer of different grades were analyzed by immunohistochemistry for expression of S100A8, S100A9, and RAGE. In addition, in situ hybridization of S100A8 and S100A9 was done for 20 cases. An ELISA was applied to determine serum concentrations of S100A9 in cancer patients compared with healthy controls or to patients with benign prostatic hyperplasia (BPH). Results: S100A8, S100A9, and RAGE were up-regulated in prostatic intraepithelial neoplasia and preferentially in high-grade adenocarcinomas, whereas benign tissue was negative or showed weak expression of the proteins. There was a high degree of overlap of S100A8 and S100A9 expression patterns and of S100A8 or S100A9 and RAGE, respectively. Frequently, a gradient within the tumor tissue with an increased expression toward the invaded stroma of the prostate was observed. S100A9 serum levels were significantly elevated in cancer patients compared with BPH patients or healthy individuals. Conclusion: Our data suggest that enhanced expression of S100A8, S100A9, and RAGE is an early event in prostate tumorigenesis and may contribute to development and progression or extension of prostate carcinomas. Furthermore, S100A9 in serum may serve as useful marker to discriminate between prostate cancer and BPH.

The role of dehydroepiandrosterone (DHEA) in liver carcinogenesis remains a topic of widespread research. Studies in rats suggest a hepatocarcinogenetic effect of DHEA. The incidence of DHEA-induced hepatocellular neoplasms depends on the rat strain, the gender, and the dose and duration of the treatment. Gender specific differences observed regarding the incidence of DHEA-induced hepatocellular neoplasms suggest a hormonal impact of the treatment. Studies in rats, which initially had been treated with chemical carcinogens and subsequently underwent a DHEA administration with various doses, disclose both, DHEA associated hepatic tumour promotion and hepatic tumour inhibition. These findings depend on the type, dose and duration of the initial intoxication and of the DHEA treatment. DHEA administration to rats also induces multiple profound alterations of the liver metabolism. Metabolism during DHEA treatment is characterized by an overall increase in energy expenditure. Lipid and glucose metabolism of the liver is changed profoundly switching from an anabolic to a catabolic state. This energy waste may be related to the inhibitory action of DHEA on tumour growth. Tumour enhancement is due to promotion of a specific type of preneoplastic liver lesions with a basophilic phenotype. This review summarizes the current knowledge on DHEA effects on the liver and discusses molecular and functional aspects that may explain the paradoxical effects of DHEA regarding hepatocarcinogenesis.

Background & Aims : Sex differences in drug pharmacokinetics have been well recognized and gender has been considered a risk factor for adverse events to medications yet the underlying mechanisms are incompletely understood. The aim of this study was to investigate the effect of gender and dehydroepiandrosterone (DHEA) treatment on the expression of hepatocellular transport proteins involved in uptake and secretion of organic anions in rat. Methods: Expression of the rat liver organic anion transporting polypeptides (Oatps) and multidrug resistance proteins (Mrps) was analyzed by RT-PCR, immunoblot analysis and immunofluorescence microscopy in male and female rats. Regulation of these transport proteins in response to DHEA feeding was investigated. Results: In untreated rats, protein expression significantly differed between genders being higher [Mrp2; Mrp3; Oatp1b2 (Oatp4)] comparable [Oatp1a1 (Oatp1);] or lower [Oatp1a4 (Oatp2)] in female than in male rat. DHEA treatment led to a further increase in Mrp3 expression only in female rats. Mrp2 expression was not influenced by DHEA treatment. In contrast, Oatp1b2 (Oatp4) and Oatp1a1 (Oatp1) were significantly down-regulated after DHEA feeding in both male and female rats. Conclusions: In rat, liver transport proteins of the Oatp and Mrp family are expressed in a gender-specific manner and are differentially regulated in response to DHEA feeding. Down-regulation of uptake transporters and up-regulation of the export pump Mrp3 after DHEA feeding suggests a substrate-dependent feedback regulation. These findings may in part explain the well-known sex differences in hepatic handling of organic anions.

Protein phosphatase inhibitor-1 plays an important role in the regulation of glycogen metabolism through inhibition of protein phosphatase-1 activity, and it has been implicated in the regulation of cell growth. Using real-time quantitative RT-PCR, we studied the mRNA expression of inhibitor-1 in hepatocellular carcinomas induced in rats by oral administration of N-nitrosomorpholine, and in a non-tumorigenic liver cell line (C1I), that stores glycogen in excess during early passages. In late passages, glycogen is gradually lost concomitant with cell transformation. Our in vitro model included a tumorigenic subline of C1I cells that was obtained by chemically-induced neoplastic transformation using N-methyl-N'-nitro-N-nitrosoguanidine (C1Ict), and does not store glycogen, as well as Morris hepatoma 3924A (MH3924A) cells. We found that in hepatocellular carcinomas, in the late glycogen-poor passages (C1I(late)), and in the tumorigenic subline (C1Ict) of C1I cells, and in MH3924A cells the mRNA expression of inhibitor-1 is significantly increased. This increase in expression varied from 15 to 290-fold of that observed in normal liver. In contrast, in the early glycogen-storing passage of C1I cells (C1I(early)) the level of inhibitor-1 mRNA was found to be slightly less than that of normal liver. Inhibitor-1 mRNA levels correlated with the degree of differentiation of HCCs. These results indicate that the expression of inhibitor-1 mRNA is tightly linked to tumor progression and to the process of liver cell transformation in vitro and is inversely correlated with the glycogen content of the cell.

AKT/PKB is a central signaling molecule related to stimulation of cell proliferation and inhibition of apoptosis. Perturbations of AKT expression and function play an important role in tumor development and progression. We wanted to determine (a) whether AKT is overexpressed in human prostatic tumors, (b) whether AKT expression is correlated with tumor grade, and (c) whether AKT expression correlates with clinicopathological parameters. AKT expression was investigated by immunohistochemistry in sections from 56 paraffin-embedded prostate specimens displaying benign prostatic tissue (BPT), prostatic intraepithelial neoplasia (PIN), and primary tumors graded 2-5 according to Gleason. The staining intensity for AKT was significantly more pronounced in tumors compared to BPT, with PIN ranging between BPT and carcinomas. Similarly, the fraction of AKT-positive cells was higher in tumors than in BPT. A score of AKT expression (calculated as product from intensity and fraction of positive cells) ranging from 0-6 was also significantly higher in tumors than in BPT. Furthermore, the intensity of AKT expression in tumors showed a positive correlation with high preoperative serum levels of prostate specific antigen (PSA >/= 10 ng/ml, p = 0.0325). These data show that AKT is upregulated in prostate cancer and that expression is correlated with tumor progression.

Dehydroepiandrosterone (DHEA), the main adrenal steroid in humans and a precursor in androgen and estrogen biosynthesis, acts as a peroxisome proliferator and as a hepatocarcinogen in rats. Neoplasms emerge from a glycogenotic/amphophilic/basophilic preneoplastic cell lineage. A higher female tumor incidence suggests a relevant influence of sex hormones. DHEA enhances hepatocarcinogenesis induced by N-nitrosomorpholine (NNM), which is characterized by the glycogenotic/basophilic cell lineage. The tumor promoting effect is related to an additional amphophilic/basophilic preneoplastic lesion sequence and to faster proliferation of the basophilic preneoplastic lesions. Nevertheless, hepatocellular carcinomas provided under DHEA treatment seem to have a less malignant phenotype compared to tumors induced by NNM only. Further, DHEA treatment reduces growth and generation of glycogen storage foci (GSF) in initial NNM-treated rats. Thus, DHEA treatment results in both, a growth stimulation of the late basophilic lesion type with an additional amphophilic lesion sequence, and in a growth inhibition of early preneoplastic lesions, addressing especially GSF. DHEA also inhibits the growth of physiologically proliferating liver tissue. This might be explained by a DHEA related cellular metabolism, which results in significant energy consumption. Additionally, a DHEA-induced alteration of cytokine levels might contribute to this growth inhibition as well.

Dehydroepiandrosterone (DHEA) is a mitogen for estrogen-dependent MCF-7 breast cancer cells. Our aims were to determine whether DHEA required conversion to estrogens in order to stimulate cell proliferation and estrogen-dependent gene expression. After incubation of cells with 100 nM DHEA for 4 days, estradiol was present in the medium at a concentration of ∼200 pM. Other compounds identified were testosterone (∼300 pM) and estrone. Significant stimulation of cell proliferation by 1 nM estradiol and 100 nM DHEA was observed after 38 h and 4 days of incubation, respectively, indicating the necessity of DHEA conversion. DHEA doses ≥10 nM induced estrogen-dependent reporter gene expression in MCF-7 cells transfected with a luciferase reporter gene under the control of the estrogen response element. DHEA-dependent stimulation of proliferation and luciferase induction could be inhibited by the anti-estrogens ICI182,780 and tamoxifen, respectively, and by the aromatase inhibitor 4-hydroxyandrostenedione. An androgenic effect of DHEA on proliferation and gene expression of MCF-7 cells was not observed. We conclude that conversion of DHEA to estrogens, particularly estradiol, is required to exert a mitogenic response.

METHODS Cellular localisation of the cyclooxygenase (COX) isozymes COX-1 and COX-2 was analysed in 24 cholangiocarcinomas, including 17 matched tissues originating from non-tumorous liver tissue adjacent to tumours and seven biopsies of normal human liver, by immunohistochemistry using isozyme selective antibodies. RESULTS In normal liver, constitutive expression of COX-2 protein was a characteristic feature of hepatocytes whereas no COX-2 immunosignal was detectable in normal bile duct epithelium, Kupffer, and endothelial cells. In cholangiocarcinoma cells, COX-2 protein was strongly expressed at high frequency. The intensity, percentage of positive cells, and pattern of COX-2 expression were found to be independent of the stage of tumour differentiation. In hepatocytes of matched non-tumorous tissue, COX-2 expression was unaltered. In contrast, strong COX-1 expression was frequently localised to Kupffer cells, endothelial cells, and occasionally to hepatocytes, but not to bile duct epithelial cells. In approximately half of moderately and poorly differentiated but not well differentiated cholangiocarcinomas, weak to moderate COX-1 staining was found in tumour cells while COX-1 expression in Kupffer cells was much more pronounced. CONCLUSION Aberrant COX-2 expression occurs during the early stage while COX-1 over expression seems to be related to later stages of cholangiocarcinogenesis.

The ligands, receptors and related signaling proteins of the insulin-like growth factor family are involved in the regulation of breast-cancer cell growth. We investigated the expression pattern of insulin-like growth factor-I receptor (IGF-IR), insulin receptor (IR) and insulin receptor substrate-1 (IRS-1), a core downstream signaling protein, in 69 primary breast-cancer specimens of different grades and in 21 control tissues by immunohistochemistry. In addition, cell proliferation (percentage of Ki67(+) nuclei) and estrogen receptor (ER) expression were determined. IGF-IR, IRS-1 and IR were expressed mainly in epithelial cells. IRS-1 and IGF-IR were expressed at high levels in control tissues and in well and moderately differentiated carcinomas but at low levels in poorly differentiated breast cancers. IR expression did not show a significant correlation with the differentiation grade of the tissues investigated. Statistical analysis (ROC analysis for tumor grade) demonstrated that down-regulation of IGF-IR and IRS-1 correlated better with tumor progression than reduction of ER expression or increase in cell proliferation, IGF-IR showing the best correlation, followed by IRS-1 and, less significant, ER and Ki67. Our findings clearly show that progression of breast cancer is accompanied by a reduction of IGF-IR/IRS-1 expression and that IGF-IR/IRS-1 expression inversely correlates with high proliferation rate in dedifferentiated breast cancers. The strong correlation of IGF-IR and IRS-1 down-regulation with tumor progression suggests the use of IGF-IR and IRS-1 as a novel set of marker proteins for tumor grading.

Insulin receptor substrate-1 (IRS-1) is over-expressed in preneoplastic glycogenotic hepatic foci (GSF) and is gradually down-regulated during progression of these lesions, via mixed cell foci (MCF), to the basophilic neoplastic phenotype. The aim of the present study was to investigate the effect of dehydroepiandrosterone (DHEA), a weak hepatocarcinogen and tumour enhancer, on IRS-1 expression Hepatocellular lesions were induced by N-nitrosomorpholine followed by DHEA. Under these conditions, many glycogen-poor amphophilic (APF) and intermediate cell foci (ICF) appear, in addition to GSF and MCF. IRS-1 was over-expressed in 215 out of 295 GSF, in 50 out of 53 MCF and in a glycogen-rich mixed cell adenoma. IRS-1 expression was not shown in 147 APF, 51 ICF and 5 amphophilic hepatocellular adenomas, and 3 out of 5 hepatocellular carcinomas showed a weak IRS-1 expression. The results suggest a close association of IRS-1 over-expression with the glycogenotic hepatocellular phenotype. The modulation and enhancement of tumour progression by DHEA is associated with a shift from glycogenosis to amphophilia and basophilia, and a down-regulation of IRS-1 expression. (C) 1999 Elsevier Science Ireland Ltd. All rights reserved.

The adrenal steroid dehydroepiandrosterone (DHEA) is a hepatocarcinogen and peroxisome proliferator in the rat, producing an increase in peroxisomes mainly in perivenular parts of the liver lobule. Glutamine synthetase (GS) is expressed exclusively in hepatocytes that directly surround the central terminal vein in rat Liver. The GS-positive zone is wider in males than in females, covering about two to three cell layers in males and one to two cell layers in females. Treatment of rats with DHEA at a concentation of 0.6% in the diet for 4, 20, 32, 70 and 84 weeks resulted in an enlargement of the GS-positive zone in females, whereas no change was observed in males. In females treated for up to 32 weeks with DHEA, the relative mean width (RMW) of the GS-positive zone was as large as that observed in males. The increase in the RMW was paralleled by an increase in the number of GS-positive hepatocytes. Upon longer treatment, the width of GS expression decreased to that observed in untreated controls. The findings suggest an androgenic effect of DHEA. The areas of peroxisome proliferation, identified in haematoxylin and eosin- and periodic acid-Schiff-stained sections, and GS expression were not identical. Furthermore, preneoplastic and neoplastic liver lesions induced by DHEA were all negative for GS, indicating that they do not derive from the perivenular cells which show the most pronounced peroxisomal proliferation.

Cancer cells are characterized by fundamental aberrations in energy metabolism, which are regarded as secondary events appearing in late stages of the carcinogenic process by most authors. However, more recent biochemical and molecular biological approaches in situ provided compelling evidence for an essential role of early changes in energy metabolism during neoplastic development. Hepatic and renal carcinogenesis induced by various agents in rodents and some observations in humans will be used to exemplify this concept. In both the liver parenchyma and the renal tubular system two outstanding early metabolic aberrations were discovered: (1) a focal excessive storage of glycogen (glycogenosis) leading via various intermediate stages to neoplasms, the malignant phenotype of which is poor in glycogen but rich in ribosomes and sometimes also mitochondria, and (2) an accumulation of atypical mitochondria in so-called oncocytes or amphophilic cells, giving rise to well differentiated neoplasms. In the liver, the preneoplastic focal glycogenosis is characterized by an altered metabolic pattern resembling an insulin effect. The progression from the focal glycogenosis to glycogen-poor neoplasms is usually associated with a reduction in gluconeogenesis, an activation of the pentose phosphate pathway and glycolysis, and an ever increasing cell proliferation. A similar, albeit not identical metabolic shift and gradual increase in cell proliferation takes place during progression from glycogenotic rat renal cell tubules (originating from the collecting duct system) to renal cell carcinomas. The metabolic pattern of preneoplastic, oncocytic and amphophilic cell populations has not been analyzed in comparable detail but an important difference to the other cell lineages appears to be that the activity of the key enzyme of the pentose phosphate pathway, the glucose 6-phosphate dehydrogenase, is not increased but rather normal or even decreased in the early lesions and in the resulting neoplasms. At least in the case of the preneoplastic glycogenotic foci, the emergence of these cell populations appears to be a consequence of an early disturbance in signal transduction pathways. The later shift towards a glycogen-poor malignant phenotype might indicate a metabolic adaptation to the primary molecular lesion.

Preneoplastic liver foci and neoplasms of different morphological phenotypes were induced in rats with N‐nitrosomorpholine (NNM; 120 mg/l in drinking water for 7 weeks) and the peroxisome proliferator dehydroepiandrosterone (DHEA; 0.6% in the diet for up to 84 weeks). Preneoplastic glycogen storage foci (GSF) occurred mainly upon treatment with NNM, and amphophilic cell foci (APF) were mainly observed in rats treated with DHEA alone or in combination with NNM. The 2 types of lesions belong to 2 different cellular lineages, the glycogenotic/basophilic lineage and the amphophilic lineage, which are characterized by distinct patterns of alterations in key enzymes of energy metabolism. Whereas in GSF enzymes of glucose metabolizing pathways were modified (increase in glucose‐6‐phosphate dehydrogenase and pyruvate kinase, decrease in glucose‐6‐phosphatase), APF mainly demonstrated alterations in mitochondrial enzymes (increase in cytochrome c oxidase, succinate dehydrogenase and glycerol‐3‐phosphate dehydrogenase) and, to a lower extent, in peroxisomal enzymes (increase in peroxisomal hydratase and acyl‐CoA oxidase). The alterations in enzyme expression reflect an insulinomimetic effect in GSF and a thyromimetic effect in APF. Neoplasms resulting from APF show a more differentiated phenotype than those arising from GSF. We suggest that the different and in many aspects opposite effects of the 2 carcinogens on key enzymes of distinct pathways of energy metabolism modulate the process of neoplastic liver cell transformation and result in phenotypically different preneoplasias and neoplasias reflecting different cellular lineages. Int. J. Cancer (Pred. Oncol.): 79:232–240, 1998.© 1998 Wiley‐Liss, Inc.

Dehydroepiandrosterone (DHEA) is an intermediate product in the synthesis of male and female sex hormones in the adrenal cortex of man. In livers of rats and mice DHEA increases the levels of cytochrome P450 IVA and peroxisomal beta-oxidation enzymes associated with peroxisome proliferation. Prolonged treatment of rats with DHEA induces liver tumors that are more frequent in females arising mainly in the periportal regions of the liver lobule (Metzger et al., Toxicol. Pathol. 23, 591-605, 1995). Because of paucity of information on hepatic zonation of peroxisomal response to DHEA and controversial reports on gender-specific differences of its effects the present study was undertaken using qualitative immunohistochemical and quantitative immunoelectron microscopical techniques in addition to Western blotting. Rats were treated for 24 weeks with 0.6% DHEA supplied with diet. Immunoblot analysis revealed marked induction of peroxisomal beta-oxidation enzymes, which by quantitative analysis was equally strong in male and female animals, whilst catalase and urate-oxidase were not increased. Cytochrome P450 IVA, in contrast, was induced significantly stronger in male than in female rats. Immunohistochemistry confirmed the induction of cytochrome P450 IVA showing a marked lobular gradient in female animals with strong induction in pericentral and almost no induction in periportal regions of the liver lobule. In male animals cytochrome P450 IVA was expressed more uniformly across the liver lobule. A similar sex specific zone-dependent response was observed for peroxisomes. DHEA induced in females a significant zonal gradient with marked peroxisome proliferation and a strong induction of peroxisomal hydratase/dehydrogenase in pericentral hepatocytes and a much smaller response in periportal regions. Livers of male animals, in contrast, showed a uniform peroxisomal proliferation to DHEA with only slight zonal differences. The striking homologies of the induction patterns of cytochrome P450 IVA and the peroxisome proliferation in both sexes support the notion of a functional relationship. In view of the almost exclusive periportal localization of DHEA-induced tumors in female rats in contrast to the pericentral localization of the peroxisomal proliferation shown by this study, it seems likely that other factors in addition to peroxisome proliferation may contribute to the hepatocarcinogenic effect of DHEA.

Hepatocarcinogenesis was induced in male and female rats by continuous administration of the adrenal steroid dehydroepiandrosterone (DHEA; 0.6% in the diet) with and without previous treatment with N-nitrosomorpholine (NNM; 120 mg/l drinking water for 7 weeks). DHEA treatment alone resulted in hepatocellular adenomas (HCA) and carcinomas (HCC) after 72–84 weeks, the incidence of both benign and malignant neoplasms being higher in females than in males. After DHEA administration for up to 32 weeks subsequent to NNM, the incidence of HCA and HCC was significantly higher (HCA, 42%; HCC, 42%) than after NNM alone (HCA, 33%; HCC, 28%). While total tumor incidence was similar in male (63%) and female (60%) rats after NNM treatment alone, it was higher in females (87%) than in males (80%) after NNM/DHEA treatment. The difference between the genders was mainly due to the higher incidence of HCC in females. Morphometric analysis of preneoplastic foci of altered hepatocytes (FAH) yielded that DHEA treatment did not increase the average total number of FAH induced by NNM, but caused a modulation of the phenotype of FAH from the glycogenotic/basophilic to the amphophilic cell lineage. The results confirm that DHEA acts as a hepatocarcinogen and show for the first time that it enhances NNM-induced hepatocarcinogenesis in rats.