Lack of human leukocyte antigen-G expression in extravillous trophoblasts is associated with pre-eclampsia

Pre-eclampsia, a common complication of first pregnancies, is thought to result from a poorly perfused placenta and may reflect an abnormal maternal immune reaction to the hemiallogenic fetus. Human leukocyte antigen (HLA)-G, a major histocompatibility tissue-specific antigen expressed in extravillous trophoblast cells (fetal-derived), may protect trophoblasts from maternal-fetal immune intolerance and allow these cells to invade the uterus. Through RNA in-situ hybridization analysis, we studied the expression pattern of HLA-G in normal placentae and placentae from pregnancies complicated by severe pre-eclampsia. In normal placenta we found HLA-G expression in the anchoring extravillous trophoblasts with an increasing gradient of expression in the more invasive cells. However, in nine out of 10 pre-eclamptic placentae HLA-G expression was absent or reduced. We conclude that HLA-G is normally expressed in invasive trophoblasts and HLA-G expression is defective in most pre-eclamptic placentae. We propose that trophoblasts lacking HLA-G are vulnerable to attack by the maternal immune system. These defective trophoblasts will be unable to invade the maternal spiral arteries effectively, thereby developing vessels which cannot adequately nourish the developing placenta. This poorly perfused placenta may initiate the systemic cascade of events associated with pre-eclampsia.

Evaluation of epidermal growth factor receptors in bladder tumours

Epidermal growth factor (EGF) receptor expression in 31 primary human bladder tumours was quantitated using both structural and functional assays and the EGF receptor gene in the same tumours was analyzed by Southern blot analysis. Immunocytochemical studies using the EGFR1 monoclonal antibody (Mab) showed a significant correlation between EGF receptor levels and the stage and grade of the tumours. Autophosphorylation assays employed to evaluate the receptor's tyrosine kinase activity gave results which in general were consistent with the immunocytochemical data. Using internally controlled immunocytochemical studies with two Mabs and Southern blot analysis of DNA isolated from the tumours, no evidence was obtained for the production of truncated receptors similar to those encoded by the v-erb-B oncogene. Gene amplification was not found in any of the superficial tumours, but one invasive tumour with high EGF receptor expression had an 8-10 fold amplification of the EGF receptor gene. The EGF receptor isolated from this tumour showed a normal pattern of tyrosine phosphorylation at all three major autophosphorylation sites. Our detailed study is consistent with the correlation previously found between EGF receptor expression and stage and grade of bladder tumours, and suggests that at this level of analysis EGF receptors in bladder tumours are not abnormal in structure or size, autophosphorylation activity, or gene structure.

Epidermal growth factor binding induces a conformational change in the external domain of its receptor

To study the properties of the extracellular epidermal growth factor (EGF) binding domain of the human EGF receptor, we have infected insect cells with a suitably engineered baculovirus vector containing the cDNA encoding the entire ectodomain of the parent molecule. This resulted in a correctly folded, stable, 110 kd protein which possessed an EGF binding affinity of 200 nM. The protein was routinely purified in milligram amounts from 1 litre insect cell cultures using a series of three standard chromatographic steps. The properties of the ectodomain were studied before and after the addition of different EGF ligands, using both circular dichroism and fluorescence spectroscopic techniques. A secondary structural analysis of the far UV CD spectrum of the ectodomain indicated significant proportions of alpha-helix and beta-sheet in agreement with a published model of the EGF receptor. The ligand additions to the receptor showed differences in both the near- and far-UV CD spectra, and were similar for each ligand used, suggesting similar conformational differences between uncomplexed and complexed receptor. Steady-state fluorescence measurements indicated that the tryptophan residues present in the ectodomain are buried and that the solvent-accessible tryptophans in the ligands become buried on binding the receptor. The rotational correlation times measured by fluorescence anisotropy decay for the receptor-ligand complexes were decreased from 6 to 2.5 ns in each case. This may indicate a perturbation of the tryptophan environment of the receptor on ligand binding. Ultracentrifugation studies showed that no aggregation occurred on ligand addition, so this could not explain the observed differences from CD or fluorescence.(ABSTRACT TRUNCATED AT 250 WORDS)

Epidermal growth factor receptors in lung tumours

Immunocytochemical analysis of epidermal growth factor (EGF) receptor expression was carried out on frozen sections of 109 primary lung tumours resected at the Brompton Hospital from February 1984 to May 1985. Tumours with detectable levels of this proto-oncogene protein were significantly more frequent among squamous cell carcinomas than among other types of lung tumour. No truncated EGF receptors were detected in the tumours using two monoclonal antibodies (Mabs) directed against different portions of the receptor (EGFR1 and F4). Mab F4 is the first antibody to the EGF receptor to show reactivity in paraffin sections. Southern blot analysis of a subset of the tumours detected amplification of the EGF receptor gene in squamous cell carcinomas but not in adenocarcinomas. The one carcinosarcoma examined had a re-arranged and amplified EGF receptor gene. Measurement of EGF receptor expression in lung tumours can be of diagnostic value and may prove to be useful in the development of antibody-directed therapy.

Detection of serum HBV-DNA by molecular hybridisation. Correlation with HBeAg/anti-HBe status, racial origin, liver histology and hepatocellular carcinoma

The relationship of the presence of hepatitis B virus (HBV) DNA in serum, a measure of HBV-replication, to HBeAg/anti-HBe status has been examined. In Northern Europe, there is a strong positive correlation between the presence of HBV-DNA and HBe antigenaemia and a negative correlation with the presence of anti-HBe. These associations are less marked in patients from Southern Europe, Africa, the Middle and Far East. When HBV-DNA is present in the serum of anti-HBe carriers, it is usually associated with the presence of severe liver disease or carcinoma. Forty percent of patients with hepatocellular carcinoma had evidence of continuing HBV replication.

Tie-2 and angiopoietin-2 expression at the fetal-maternal interface: a receptor ligand model for vascular remodelling

The blood vessels at the fetal-maternal interface widen dramatically during pregnancy in order to increase blood flow to nourish the developing fetus. This vessel remodelling destroys normal vessel integrity and encompasses the dissolution of vessel muscle and elastic tissue. It also includes the displacement of endothelial cells by fetal trophoblasts that invade the maternal arteries of the uterus. Interaction between the endothelial cell receptor, Tie-2, and its recently discovered antagonist ligand, angiopoietin-2 (Ang-2), has been implicated in the loosening of vessel structure. Using Northern blot hybridization and RNA in-situ hybridization analysis the expression pattern of Tie-2, and Ang-2 in the placenta throughout pregnancy, was investigated. We found Ang-2 expressed in the syncytiotrophoblast during the first trimester. In addition to the expected expression of the Tie-2 receptor in both fetal and maternal endothelial cells, we observed Tie-2 expression in endovascular invasive trophoblasts. These cells of epithelial origin invade the uterine spiral arteries and acquire endothelial cell properties. The temporal- and lineage-specific pattern of expression of Tie-2 and Ang-2 suggests that this receptor-ligand pair functions during the critical phase of development of the fetal vasculature and reworking of the maternal vessels during normal placentation.

Expression of the human EGF receptor with ligand-stimulatable kinase activity in insect cells using a baculovirus vector

The mechanism by which the binding of epidermal growth factor (EGF) to specific cell surface receptors induces a range of biological responses remains poorly understood. An important part of the study of signal transduction in this system involves the production of sufficient native and mutant EGF receptor species for X-ray crystallographic and spectroscopic analysis. Baculovirus vectors containing the cDNA encoding the human EGF receptor protein have here been utilized to infect insect cells. This results in expression of a 155-kb transmembrane protein which is recognized by four antibodies against different regions of the human EGF receptor. Studies with tunicamycin, monensen and endoglycosidase H show the difference in size between the recombinant and the native receptor is due to alterations in glycocsylation. Studies of [125I] EGF binding shows a Kd of 2 X 10(-9) M in intact infected insect cells which falls to 2 X 10(-7) M upon detergent solubilization. The recombinant protein exhibits an EGF-stimulated tyrosine protein kinase activity and an analysis of tryptic peptides shows that the phosphate acceptor sites are similar to those of the EGF receptor isolated from A431 cells. These observations indicate that functional EGF receptor can be expressed in insect cells, and furthermore, this system can be used for large-scale production.

Clostridium difficile and inflammatory bowel disease

Stools from 109 patients with inflammatory bowel disease (13.4%) contained Clostridium difficile or its toxin, an incidence similar to the stools of 99 control patients with diarrhoea (11.9%), but significantly higher than the stools of 77 control patients with a normal bowel habit (1.4%). Sixty-six per cent of the diarrhoea controls, but only 11% of the inflammatory bowel disease patients, reported recent antibiotic use: however, 67% of inflammatory bowel disease patients were taking sulphasalazine. The presence of Cl difficile in the stool was not related to the clinical assessment of inflammatory bowel disease relapse, but it was related to hospital admission. During the one year study, 31 of the 109 patients (28%) with inflammatory bowel disease had one or more stool samples that were positive for Cl difficile.

Vascular endothelial growth factor, epidermal growth factor and fibroblast growth factor-4 and -10 stimulate trophoblast plasminogen activator system and metalloproteinase-9

Trophoblast invasion, accompanied by degradation of extracellular matrix, is crucial to normal pregnancy development, whereas shallow placental invasion and implantation likely plays a role in the subsequent development of pre-eclampsia. The growth factors vascular endothelial growth factor (VEGF), epidermal growth factor (EGF) and fibroblast growth factor (FGF) are placental growth factors that activate degradation of extracellular matrix. We determined the effect of VEGF, EGF, FGF-2, FGF-4 and FGF-10 on the plasminogen activator system of first trimester cytotrophoblasts cultured in vitro. We studied the activity of urokinase plasminogen activator (uPA), its inhibitor plasminogen activator inhibitor-1 (PAI-1), and 92 kDa gelatinase-B (matrix metalloproteinase-9, MMP-9), using protein gel and reversed gel zymography. The expression pattern of FGF-4 and FGF-10 in human placental sections was determined by immunohistochemistry. FGF-4 was expressed in first trimester villi stroma, primarily in endothelial cells. FGF-10 expression was localized to first trimester extravillous trophoblasts. VEGF, EGF, FGF-4 and FGF-10, but not FGF-2, stimulate the activity of trophoblast uPA, PAI-1 and MMP-9. These results support the hypothesis that specific growth factors modulate the invasive potential of trophoblasts, and therefore may play an important role in early placental development. Our findings may contribute to the understanding of the pathophysiology of diseases associated with shallow placentation, such as pre-eclampsia.

Dimethylsulphoxide-induced toxicity

Two elderly people were given intravenous infusion of dimethylsulphoxide (DMSO) as treatment for arthritis. One became seriously ill, the other remained well. Both had similar changes in aspartate transaminase, hydroxybutyrate dehydrogenase, and creatine kinase and evidence of haemolysis. This is the first report of serum enzyme changes and anaemia after intravenous DMSO in man.

Human placental Hofbauer cells express sprouty proteins: a possible modulating mechanism of villous branching

The development of the chorionic villous tree into a complex and organized ramified tubular network can be termed branching morphogenesis. Studying the molecular mechanisms involved in this process may contribute to the understanding of pregnancy complications such as preeclampsia. Sprouty (Spry) proteins are important regulators of branching morphogenesis and growth factor signaling. We analyzed the expression of Spry genes in human placenta. RT-PCR and immunohistochemistry were employed to detect placental Spry expression. Quantitative RT-PCR was used to assess the effect of FGF and reduced oxygen fraction on Spry gene expression. Spry 1, 2 and 3 expression was observed in placental tissue from all three trimesters. Our results reveal for the first time that Spry proteins are localized in the stroma of the chorionic villi, adjacent to cytotrophoblasts in areas of villous sprouting. Immunofluorescent double staining with anti-Spry and anti-CD68 confirmed that placental macrophages (Hofbauer cells) express Spry. Reduced oxygen fraction, FGF-4 and FGF-10 stimulated Spry-2 expression. Hofbauer cells also expressed c-Cbl, a protein that interacts with Spry. Placental expression of Spry and c-Cbl implies an important role for Hofbauer cells in placental development, possibly through a mesenchymal-epithelial interaction with trophoblasts. Regulation of Spry-2 expression by FGF-4 and FGF-10 suggests an orchestrated regulatory system that modulates villous branching.

HLA-G expression in extravillous trophoblasts is an intrinsic property of cell differentiation: a lesson learned from ectopic pregnancies

Human leukocyte antigen (HLA)-G is a major histocompatibility gene expressed almost exclusively in extravillous trophoblasts at the fetal-maternal interface. HLA-G may play a role in protecting the fetus from attack by the maternal natural killer cells. The extravillous trophoblasts invade the decidua and maternal spiral arteries. The factors which regulate the cell-specific expression of HLA-G are unknown. In this study we asked if HLA-G is expressed in extravillous trophoblasts that develop outside of their normal cellular environment, as in the case of ectopic pregnancies. Since all ectopic pregnancies implant in the absence of underlying decidua we also used a placenta accreta as an experimental control. We found that HLA-G mRNA and protein were expressed in the extravillous trophoblasts in the 13 ectopic specimens studied. In a case of placenta accreta (which develops without decidua basalis and is therefore adherent to the underlying myometrium), HLA-G mRNA and protein were also expressed. These results suggest that HLA-G expression is induced in a cell autonomous manner rather than determined by appropriate environmental cues.

Integration of HBV-DNA may not be a prerequisite for the maintenance of the state of malignant transformation. An analysis of 110 liver biopsies

Hundred and ten liver biopsy specimens from various parts of the world were examined for episomal and integrated HBV-DNA sequences. In 54 patients with HBsAg chronic liver disease episomal HBV-DNA was found in 83% of HBeAg-positive patients, compared to only 22% of patients with anti-HBe. Furthermore episomal HBV-DNA in the latter predominated among the Asians. Integrated HBV-DNA was found only in 5.5% of HBeAg-positive patients but in 16.5% of patients with anti-HBe. In 28 HBsAg-positive patients with hepatoma, episomal HBV-DNA was found in 50% of HBeAg-positive patients but in only 11% of anti-HBe patients. Conversely integrated sequences were less common (25%) in HBe-Ag-positive patients than in anti-HBe patients (50%), giving an overall incidence of integration in this group of 45%. No episomal, and only one case of integrated sequences of HBV-DNA, could be detected among 10 patients with HBsAg-negative hepatoma. In addition neither episomal nor integrated HBV-DNA could be detected in 18 patients with non-HBV-related liver disease. Our data suggests that stable integration of HBV-DNA into the host's genome is not necessarily a prerequisite for the maintenance of the state of malignant transformation but may be necessary for its initiation. Alternatively, the detection of integrated HBV-DNA may represent a 'snap shot' of a random integration event amplified by clonal expansion promoted by other factors.

Is pseudomembranous colitis infectious?

A cluster of eight patients in two adjacent hospital wards acquired acute diarrhoea within a period of 11 days. All their stool samples contained Clostridium difficile toxin and C. difficile was isolated in every case. Three patients had rectal biopsy findings compatible with pseudomembranous colitis (PMC). All the patients responded to treatment with oral vancomycin. Until the possibility of PMC being acquired by cross-infection is clarified such patients should be nursed in isolation with strict enteric precautions.

Eph and ephrin expression in normal placental development and preeclampsia

Eph receptors and their ephrin ligands play a fundamental role in embryogenesis. Their functions include cell targeting and angiogenesis. In placental development, trophoblasts migrate and invade maternal tissue and spiral arteries, where they play a role in both anchoring the placenta to the uterus and increasing blood flow to the developing fetus (interstitial and endovascular invasions). We investigated the cellular distribution and expression patterns of representative Eph and ephrin RNA and protein in an effort to identify the molecules involved in trophoblast migration during normal placental development and placental pathologies. We found ephrin-A1 expressed exclusively in the invasive extravillous trophoblast (EVT) cell lineage. We therefore proceeded to investigate ephrin-A1 in placental pathologies with defects in EVT invasion. In preeclampsia, where trophoblast invasion is shallow, we observed ephrin-A1 expression similar to normal placenta. Furthermore, in initial experiments on the deeply invading trophoblasts of placenta accreta, which lacks decidua, ephrin-A1 is found to be expressed highly in extravillous trophoblasts that have invaded the myometrium. In addition, we found the prototype ephrin-A1 receptor, EphA2, localized in several placental cell types. EphB4 and ephrin-B2 molecules, which have specific expression patterns during artery and vein development, respectively, were also expressed in the placenta. The cell specific distribution of ephrin-A1 suggests that it may play a role in targeting and migration of trophoblasts, and in the vascular remodeling induced by the invading extravillous trophoblasts. Failure of ephrin-A1 expression is unlikely to be the primary cause in defective migration of trophoblasts observed in preeclampsia. Specific roles for other Eph and ephrin proteins remain to be investigated.

Biliary sequelae of endoscopic sphincterotomy

Twenty five patients were reviewed a mean of 36 months after successful endoscopic sphincterotomy for the removal of bile duct stones. All the patients had improved symptomatically but 20% had episodes of mild abdominal pain and a similar number had elevated serum gamma glutamyltranspeptidase activities (up to 3 times normal). In 12 patients (50%) biliary gas was demonstrated indicating reflux of duodenal contents. Clinical cholangitis did not occur. Aspiration liver biopsy revealed mild portal tract fibrosis and inflammation in patients with biliary reflux. Biliary reflux was significantly associated with mild upper abdominal pain (P less than 0.05). This study has shown that mild abnormalities of biliary function persist after endoscopic sphincterotomy. The long term consequence of these changes is unclear.

A study of human leukocyte antigen G expression in hydatidiform moles

OBJECTIVE

Human leukocyte antigen G (HLA-G) is a nonclassic major histocompatibility gene normally expressed only in extravillous trophoblasts throughout pregnancy. It may be responsible in part for the successful evasion of the hemiallogenic trophoblasts from maternal immune surveillance. We investigated whether HLA-G is expressed in molar pregnancies.

STUDY DESIGN

We examined 5 complete hydatidiform mole specimens and 5 partial hydatidiform mole specimens to determine whether HLA-G is expressed by immunohistochemistry and by RNA in situ hybridization analysis.

RESULTS

We found that both the protein and RNA of HLA-G is expressed in complete and partial hydatidiform moles.

CONCLUSION

HLA-G RNA and protein are expressed in molar pregnancies. HLA-G expression is independent of embryonic development and may therefore be an integral part of placental development. Furthermore, expression of HLA-G in the complete hydatidiform mole, a naturally occurring androgenote, confirms expression of the paternal allele of HLA-G. Imprinting of HLA-G is therefore unlikely to play a role in protecting fetal trophoblasts from maternal immune rejection.

Hepatitis delta virus infection in Kenya. Its geographic and tribal distribution

In 1982-1984, an epidemiologic survey of the prevalence of hepatitis B virus surface antigen (HBsAg) in circulating blood (HBs-antigenemia) and of hepatitis delta virus infection was performed in Kenya. The distributions of hepatitis B virus and the delta virus were shown to be very variable. In southern Kenya, only two of 202 sera from HBsAg-positive individuals with no known liver disease and none from 123 HBsAg-positive patients with hepatitis B-related liver disease were positive for delta antibody. In contrast, in northern Kenya, there was an overall prevalence of delta antibody in healthy individuals of 31%. The distribution of delta infection is discussed in relation to lifestyle, ethnic group, and geographic area.

Perinatal transmission of hepatitis B virus in Kenya: its relation to the presence of serum HBV-DNA and anti-HBe in the mother

In Kenya hepatitis B virus (HBV) infection and its sequelae are common. We followed up 49 hepatitis B surface antigen (HBsAg)- positive mothers and their newborn infants for 9 months to determine the importance of perinatal transmission in the African and to relate this to the HBe and HBV-DNA status of the mother. Our study shows that perinatal transmission is relatively unimportant in Kenya and that this may be a consequence of the low levels of circulating HBV-DNA in the maternal plasma. These results imply that vaccination without hyperimmune globulin may be adequate to control HBV infection in Kenya.

Aetiology of acute sporadic hepatitis in adults in Kenya

Markers for acute hepatitis A virus (HAV), hepatitis B virus (HBV), and hepatitis non-A, non-B (HNANB) infections were examined in the sera of 94 patients presenting with acute hepatitis in Kenya. Hepatitis B virus was responsible for 70% of cases, HNANB for 18%, and HAV for only 12%. The use of an IgM anti-HBc assay increased the rate of diagnosis of acute HBV infection, thereby reducing the proportion of cases designated as NANB.

Plasma lipid and lipoprotein response to fat feeding in alcoholic liver disease

Serum lipids and lipoproteins were analyzed after an overnight fast, and following a fatty meal in 10 patients with cirrhosis, 5 with fatty liver, and 5 normal subjects. Cirrhotic patients were divided into two groups of five on the basis of serum lecithin-cholesterol acyltransferase activity. Fasting triglyceride levels were similar in all four groups. In all but cirrhotic patients with low lecithin-cholesterol acyltransferase activity, most fasting triglyceride was found in very low density lipoproteins; in the latter group, most of it was found in low density lipoproteins. We confirmed that patients with fatty liver have a higher serum triglyceride response to fat feeding than normal subjects, but we did not find higher levels in cirrhotic patients. Cirrhotic patients with "normal" lecithin-cholesterol acyltransferase activity had a normal triglyceride response to dietary fat. In patients with cirrhosis and low lecithin-cholesterol acyltransferase activity, the increase in triglyceride was less than in normal subjects. In this group, most of the extra triglyceride was carried in low density lipoprotein, and not in chylomicrons and very low density lipoprotein, as in the other groups.

Severe ulcerative colitis during successful pregnancy

A 31-year-old patient presented with fulminant colitis during the 27th week of her first pregnancy. Despite failed medical treatment, colectomy was delayed because of the gravid uterus. A healthy child was delivered at 32 weeks by caesarian section, but a postoperative ileus appeared to induce transient colonic dilatation. A colectomy was performed 10 days post-partum. Both mother and child survived.

Effect of swimming on prednisolone-induced osteoporosis in elderly rats

We investigated the possible ameliorating and preventive effect of swimming on prednisolone-induced osteoporosis in elderly rats. A total of 48 female Sabra strain rats were randomly assigned to the following groups and treatments: (1) control (C), (2) swimming (S), (3) prednisolone-treated (CP), and (4) swimming + prednisolone (SP). An additional 8 rats were sacrificed and examined at the onset of the study. Groups C and S were sham injected; groups CP and SP were injected with prednisolone (Ultracorten), 80 mg/kg three times per week for 10 weeks. Groups S and SP swam 1 h daily, 5 days per week for 10 weeks. SP rats swam simultaneously with prednisolone administration. At the end of the swimming period, in vivo bone mineral content (BMC) measurements were performed on rat vertebrae L4-5 by single-photon absorptiometry. Later, the humerus and femur were removed for the following measurements: morphometric, bone density (BD) by Compton scattering technique, bone ion content by atomic absorption, and hydration fraction by proton magnetic resonance (PMR). We found that the humeral BD of S rats was greater by 14% for group S over C and 3% greater for group SP over CP (P less than 0.05). Vertebral BMC was higher by 15% in group S over C and 11% higher for group SP over CP (P less than 0.05). Femoral calcium (mg/g dry bone) ion content was higher by 5% in group S over C and 8% in group SP over CP group (P less than 0.05).(ABSTRACT TRUNCATED AT 250 WORDS)

Tamoxifen exerts oestrogen-agonistic effects on proliferation and plasminogen activation, but not on gelatinase activity, glycogen metabolism and p53 protein expression, in cultures of oestrogen-responsive human endometrial adenocarcinoma cells

To elucidate potential mechanisms involved in the increased incidence of endometrial carcinomas in tamoxifen-treated patients, we examined the in-vitro effects of tamoxifen on endometrial cancer cells. The effects of tamoxifen, alone and in combination with oestradiol, on cell proliferation, plasminogen activator (PA) activity, glycogen synthase and phosphorylase activities, p53 protein concentration, and collagenase expression were assessed in two human adenocarcinoma cell lines. These lines were the oestrogen receptor-positive (Ishikawa) cells, representing a well-differentiated endometrial adenocarcinoma, and oestrogen receptor-negative (HEC-1A) cells, derived from a poorly differentiated endometrial adenocarcinoma. Tamoxifen or oestradiol alone and their combination significantly enhanced cellular proliferation of Ishikawa but not of HEC-1A cells. Both lines produced appreciable PA activity, most of which was of the urokinase type. Tamoxifen and oestradiol stimulated this activity in Ishikawa cells but not in HEC-1A cells. The effect of oestradiol was dose-dependent in a linear fashion, while tamoxifen produced a stimulation peaking at 10(-8) M and declining at higher concentrations. Tamoxifen in combination with oestradiol exhibited a synergistic effect on proliferation and on PA activity. The response of PA extended beyond the increase in proliferation, leading to higher specific activity of PA in the tamoxifen-treated cultures. In Ishikawa cells, oestradiol also increased glycogen synthase and glycogen phosphorylase activities, while tamoxifen markedly suppressed these enzymes. Oestradiol, tamoxifen, and their combination had no apparent effect on the expression of protein p53 in Ishikawa cells, or on gelatinase activity in either Ishikawa or HEC-1A cells. The present findings imply that tamoxifen produces oestrogen-agonistic effects on cell proliferation and PA activity, and oestrogen antagonistic effects on glycogen synthase and glycogen phosphorylase activities, but fails to regulate p53 and gelatinase expression. The tamoxifen-responsive systems were only observed in oestrogen-responsive adenocarcinoma cells. Thus, only certain potential oncogenic effects of tamoxifen can be simulated in vitro, and when present, these effects are enhanced in the presence of oestradiol.