Histochemical and immunohistochemical detection of putative preneoplastic liver foci in women after long-term use of oral contraceptives

Clear cell hepatocellular carcinoma: origin, metabolic traits and fate of glycogenotic clear and ground glass cells

Clear cell hepatocellular carcinoma (CCHCC) has hitherto been considered an uncommon, highly differentiated variant of hepatocellular carcinoma (HCC) with a relatively favorable prognosis. CCHCC is composed of mixtures of clear and/or acidophilic ground glass hepatocytes with excessive glycogen and/or fat and shares histology, clinical features and etiology with common HCCs. Studies in animal models of chemical, hormonal and viral hepatocarcinogenesis and observations in patients with chronic liver diseases prone to develop HCC have shown that the majority of HCCs are preceded by, or associated with, focal or diffuse excessive storage of glycogen (glycogenosis) which later may be replaced by fat (lipidosis/steatosis). In ground glass cells, the glycogenosis is accompanied by proliferation of the smooth endoplasmic reticulum, which is closely related to glycogen particles and frequently harbors the hepatitis B surface antigen (HBsAg). From the findings in animal models a sequence of changes has been established, commencing with preneoplastic glycogenotic liver lesions, often containing ground glass cells, and progressing to glycogen-poor neoplasms via various intermediate stages, including glycogenotic/lipidotic clear cell foci, clear cell hepatocellular adenomas (CCHCA) rich in glycogen and/or fat, and CCHCC. A similar process seems to take place in humans, with clear cells frequently persisting in CCHCC and steatohepatitic HCC, which presumably represent intermediate stages in the development rather than particular variants of HCC. During the progression of the preneoplastic lesions, the clear and ground glass cells transform into cells characteristic of common HCC. The sequential cellular changes are associated with metabolic aberrations, which start with an activation of the insulin signaling cascade resulting in pre-neoplastic hepatic glycogenosis. The molecular and metabolic changes underlying the glycogenosis/lipidosis are apparently responsible for the dramatic metabolic shift from gluconeogenesis to the pentose phosphate pathway and Warburg-type glycolysis, which provide precursors and energy for an ever increasing cell proliferation during progression.

Loss of heterozygosity at D8S262: an early genetic event of hepatocarcinogenesis

BACKGROUND

Hepatocellular carcinoma (HCC) is a multi-factor, multi-step, multi-gene and complicated process resulting from the accumulation of sequential genetic and epigenetic alterations. An important change among them is from precancerous lesions to HCC. However, only few studies have been reported about the sequential genetic changes during hepatocarcinogenesis.

METHODS

We observed firstly molecular karyotypes of 10 matched HCC using Affymetrix single-nucleotide polymorphism (SNP) 6.0 arrays, and found chromosomal fragments with high incidence (more than 70%) of loss of heterozygosity (LOH). Then, we selected 28 microsatellite markers at some gene spanning these chromosomal fragments, and examined the frequency of LOH of 128 matched HCC and 43 matched precancerous lesions-dysplastic nodules (DN) by a PCR-based analysis. Finally, we investigated the expression of proteins encoded by these genes in HCC, DN and the surrounding hepatic tissues.

RESULTS

The result of Affymetrix SNP6.0 arrays demonstrated that more than 70% (7/10) cases had chromosomal fragment deletion on 4q13.3-35.1, 8p23.2-21.2, 16q11.2-24.3, and 17p13.3-12. Among 28 microsatellite markers selected, LOH frequencies at D8S262 for DN and HCC were found to be the highest, 51.2% and 72.7%, respectively. Immunohistochemically, the positive rate of its adjacent gene CSMD1 in HCC, DN, and the surrounding hepatic tissues were 27.3% (35/128), 75% (33/44), and 82% (105/128), respectively.

CONCLUSIONS

LOH at D8S262 may be associated with an early genetic event of hepatocarcinogenesis, and a predictor for the monitor and prevention of HCC.

VIRTUAL SLIDES

The virtual slides for this article can be found here: http://www.diagnosticpathology.diagnomx.eu/vs/1557074981159099 .

Glycogenotic hepatocellular carcinoma with glycogen-ground-glass hepatocytes: A heuristically highly relevant phenotype

Glycogenotic hepatocellular carcinoma (HCC) with glycogen-ground-glass hepatocytes has recently been described as an allegedly “novel variant” of HCC, but neither the historical background nor the heuristic relevance of this observation were put in perspective. In the present contribution, the most important findings in animal models and human beings related to the emergence and further evolution of excessively glycogen storing (glycogenotic) hepatocytes with and without ground glass features during neoplastic development have been summarized. Glycogenotic HCCs with glycogen-ground-glass hepatocytes represent highly differentiated neoplasms which contain subpopulations of cells phenotypically resembling those of certain types of preneoplastic hepatic foci and benign hepatocellular neoplasms. It is questionable whether the occurrence of glycogen-ground-glass hepatocytes in a glycogenotic HCC justifies its classification as a specific entity. The typical appearance of ground-glass hepatocytes is due to a hypertrophy of the smooth endoplasmic reticulum, which is usually associated with an excessive storage of glycogen and frequently also with an expression of the hepatitis B surface antigen. Sequential studies in animal models and observations in humans indicate that glycogen-ground-glass hepatocytes are a facultative, integral part of a characteristic cellular sequence commencing with focal hepatic glycogenosis potentially progressing to benign and malignant neoplasms. During this process highly differentiated glycogenotic cells including ground-glass hepatocytes are gradually transformed via various intermediate stages into poorly differentiated glycogen-poor, basophilic (ribosome-rich) cancer cells. Histochemical, microbiochemical, and molecular biochemical studies on focal hepatic glycogenosis and advanced preneoplastic and neoplastic lesions in tissue sections and laser-dissected specimens in rat and mouse models have provided compelling evidence for an early insulinomimetic effect of oncogenic agents, which is followed by a fundamental metabolic switch from gluconeogenesis towards the pentose-phosphate pathway and the Warburg type of glycolysis during progression from preneoplastic hepatic glycogenosis to the highly proliferative malignant phenotype.

Clonality of nodular lesions in liver cirrhosis and chromosomal abnormalities in monoclonal nodules of altered hepatocytes

AIMS

To investigate the clonality and chromosome abnormalities of nodules of altered hepatocytes (NAH) in liver cirrhosis and determine whether there is a genetic link between monoclonal NAH and hepatocellular carcinoma (HCC).

METHODS AND RESULTS

First, 93 nodules from nine hepatitis B virus (HBV)-related liver cirrhosis patients were dissected by laser microdissection. Next, genomic DNA was extracted, pretreated with Hpa II or Hha I, and amplified via nested polymerase chain reaction for the phosphoglycerate kinase and androgen receptor genes. Finally, the chromosomal aberrations of 12 monoclonal NAH were studied using array-based comparative genomic hybridization (array-CGH). Loss of X chromosomal inactivation mosaicism was demonstrated in three large regenerative nodules and 12 NAH with small cell change (SCC), indicating their neoplastic nature. Among the 60 NAH without SCC, 29 (48.33%) were shown to be monoclonal, whereas four glycogen-storing foci and 14 regenerative nodules were found to be polyclonal. Array-CGH analysis revealed chromosomal abnormalities in one NAH with SCC. Moreover, a part of chromosomal abnormalities in the NAH with SCC coincided with those in HCC.

CONCLUSIONS

Some (48.33%) NAH in HBV-associated cirrhosis, particularly all those with SCC, are already neoplastic lesions. Occurrence of SCC is a late event during NAH progression, suggesting a premalignant phenotype.

Hepatocellular carcinoma occurring in a young Crohn's disease patient

Reported herein is a case of hepatocellular carcinoma (HCC) occurring in a 25-year-old Japanese man who was diagnosed with Crohn's disease (CD) at 14 years of age; treatment included predonisolone, azathioprine, and infliximab. The tumor was located in right upper lobe and the size was 8 cm in diameter; histology was poorly differentiated HCC with pleomorphic cellular changes. Adjacent normal liver showed no evidence of cirrhosis or viral hepatitis. Until now, only six cases of HCC arising in patients with CD have been reported in the English-language literature. Most of these patients had early onset of CD and HCC: none had cirrhosis or virus hepatitis. Most patients had a long disease history of CD and were being medicated with several immunosuppressive agents. Some factors associated with CD might indirectly or directly be related to the development of HCC in CD patients, although the possibility that these HCC occurred coincidentally in CD patients, including the present patient, cannot be ruled out. Accumulation of cases is necessary to evaluate the relationship between CD and HCC precisely.

Use of X-chromosome inactivation pattern and laser microdissection to determine the clonal origin of focal nodular hyperplasia of the liver

AIM

To determine the clonal origin of the whole lesion and each nodule of focal nodular hyperplasia (FNH) and elucidate its nature, simultaneously comparing the clonal composition with hepatocellular adenoma (HA).

METHODS

Nine FNHs from eight women, two HAs and four hepatocellular carcinomas (HCCs) were examined by clonality assays based on X-chromosomal inactivation mosaicism in females and laser microdissection. Genomic DNA was isolated from each nodule, the whole lesion and surrounding liver parenchyma, pretreated with Hpa II or Hha I, and amplified via nested PCR for phosphoglycerate kinase (PGK) and androgen receptor (AR) genes. The single nucleotide polymorphism at the PGK locus was identified by incubation with Bst XI and agarose gel electrophoresis, and the CAG repeat length polymorphism at AR locus was revealed on denaturing polyacrylamide gels and visualised by silver staining.

RESULTS

Monoclonality was confirmed in both of the two HAs and all of the four HCCs examined, while polyclonality was shown in all nine FNHs as determined by the whole lesions, demonstrating their distinction from neoplastic lesions. A total of 108 nodules, including 96 nodules of altered hepatocytes (NAH) and 12 ordinary regenerative nodules (ORN), were microdissected from eight of the nine FNH lesions. Loss of X-chromosomal inactivation mosaicism was demonstrated in 39 (40.6%) of 96 NAHs, indicating the monoclonal, neoplastic nature. In contrast, polyclonality was demonstrated in all of the 12 ORNs and the surrounding liver parenchyma.

CONCLUSIONS

FNH is composed of numerous NAHs and ORNs. The whole lesion shows a polyclonal cell composition, but neoplastic transformation has occurred in some of the nodules. Clonal assay is useful for its distinction from HA, and sampling the whole or larger part of the lesion is necessary.

[Hepatocellular carcinoma in the non-cirrhotic liver]

Of hepatocellular carcinomas (HCC), 15-20% occur in the non-cirrhotic liver. All factors which cause HCC when liver cirrhosis (LC) is present, can also lead to HCC without LC. On the basis of the relative frequency, HCC can be roughly differentiated into 3 groups: 1) HCC, rarely occurring without cirrhosis (e.g. virus hepatitis, alcohol abuse). 2) HCC, frequently occurring without LC (alpha1-antitrypsin deficiency, hemochromatosis, non-alcoholic fatty liver disease). 3) HCC, consistently occurring without LC (glycogen storage disease type 1, consumption of oral contraceptives/anabolic steroids). In groups 1 and 2 the level of hepatocellular toxicity necessary to reach LC is not yet achieved but the carcinogenic effect is already strong enough to induce HCC, possibly owing to the influence of additional carcinogens or host factors. In group 3, the carcinogenic effect is mediated by a long-standing alteration of the hepatocellular metabolism that is of low toxic effect and does not lead to cell death, but is nevertheless carcinogenic. In these cases, the initial formation of hepatocellular adenomas that subsequently transform into HCC is a common finding (adenoma-carcinoma sequence).

Intracellular conversion of irinotecan to its active form, SN-38, by native carboxylesterase in human non-small cell lung cancer

The anticancer agent irinotecan (CPT-11) is a prodrug converted to its active form, SN-38, by human carboxylesterase (hCE) and the SN-38 is further metabolized to its inactive form, SN-38G. We investigated the expression of hCE in human lung cancer cells as well as the ability of these cells to convert CPT-11 to SN-38 using surgically resected tumor samples and cultured cell lines. SN-38 was 40- to 3,000-fold more toxic to lung cancer cell lines than CPT-11, which acted more time-dependently than SN-38. Although human lung cancer cells expressed hCE in the cytoplasm, hCE expression levels in cancer cells were not correlated with their drug sensitivities. Although intracellular CPT-11 and SN-38 levels continuously increased within 60 min of CPT-11 exposure, SN-38 levels in cells exposed to SN-38 decreased. Cells with the ability to metabolize SN-38 to SN-38G were more resistant to extracellular SN-38 than cells lacking the ability. Of 25 squamous cell carcinomas, 15 were strongly positive for hCE and six were negative. Of 25 adenocarcinomas, four were strongly positive for hCE and 16 were positive, while five were negative. Thus, 70% of non-small cell lung cancers expressed hCE. From these results, we conclude that human lung cancer cells expressed the enzyme which can convert CPT-11 to SN-38 and that intracellular SN-38 converted from CPT-11 may act as a chemotherapeutic agent together with SN-38 absorbed from the outside and augment the dose intensity of SN-38. Therefore, to assess the effects of CPT-11 prior to chemotherapy, it is important to check if lung cancer cells express hCE.

Relevance of hepatic preneoplasia for human hepatocarcinogenesis

Different lesions have been suggested to represent preneoplastic conditions in human liver. They include liver cell dysplasia, separated in large-cell change (LCC) and small-cell change (SCC), adenomatoid hyperplasia, and the more recently identified foci of altered hepatocytes (FAH) and nodules of altered hepatocytes (NAH). FAH have been demonstrated to represent preneoplastic lesions in various animal models of hepatocarcinogenesis. To demonstrate prevalence and significance of FAH in the human liver, the cellular composition, size distribution, and proliferation kinetics of these lesions were studied in 163 explanted and resected human livers with or without hepatocellular carcinoma (HCC). FAH including glycogen-storing foci (GSF), mixed cell foci (MCF), and basophilic cell foci were found in 84 of 111 cirrhotic livers, demonstrating higher incidences in cases with than without HCC. MCF, predominant in cirrhotic livers of the high-risk group, were more proliferative, larger and more often involved in formation of NAH than GSF. The results suggest that the FAH are preneoplastic lesions, MCF being more advanced than GSP. We also investigated the relationship of FAH to liver cell dysplasia. Occurrence of SCC, rather than that of LCC, confers FAH an increased proliferation activity and higher risk to nodular transformation, and, hence, should be considered a precancerous condition. Histological detection of FAH and SCC through needle-aspiration liver biopsy can be used for monitoring HCC development in high-risk populations, such as HBV carriers with chronic hepatitis and/or cirrhosis.

Nonlinearity of nuclear enlargement in hepatocytes induced by the carcinogen N'-nitrosomorpholine in Ovo

In this study we investigated the effects of different doses of the carcinogenic nitrosamine N'-nitrosomorpholine (NNM) on the occurrence of enlarged nuclei in embryonic turkey liver in order to evaluate whether this parameter might represent a quantitative indicator of chemically induced hepatocarcinogenesis. Therefore fertile embryo turkey eggs were injected with NNM over a dose range of 125 microg-8 mg/egg at the first day of incubation. After incubation for 24 days, the embryonic livers were removed and processed for histologic evaluation. The induction of hepatocytes with enlarged nuclei (nuclear profiles > 35 microm2 was quantitated morphometrically in hematoxylin and eosin (H&E)-stained sections. The NNM treatment increased both the number of enlarged hepatocyte nuclei and the areas of the individual profiles of the enlarged nuclei in a dose-dependent manner. Exposure to 500 microg-8 mg NNM/egg resulted in a statistically significant increase in the number of hepatocytes with enlarged nuclei. The lower doses of 250 microg and 125 microg NNM/egg showed a similar albeit not significant trend. Signs for cytotoxic effects on the hepatocytes, such as necrosis or enhanced cytoplasmic vacuolization, were observed in tissue samples of embryos exposed to 4 or 8 mg NNM, but not after treatment with lower doses. The dose-effect curve for the induction of the nuclear enlargement was nonlinear, with a moderate slope for lower dose levels of 125-500 microg/egg and a steep slope for higher dose levels of 1-8 mg. Findings in rodents indicate a pathogenic link between the occurrence of enlarged nuclei and hepatocarcinogenesis. Based on the results with NNM, it is suggested that the in ovo model may represent a rapid, convenient, and inexpensive experimental approach for dose effect investigations on chemically induced hepatocarcinogenesis.

Short- and intermediate-term carcinogenicity testing--a review. Part 1: the prototypes mouse skin tumour assay and rat liver focus assay

Carcinogenicity testing is by far the most expensive and time-consuming study type of toxicology. For many years, the lifetime exposure with the maximum tolerated dose in two rodent species has been the gold standard of carcinogenicity testing of pharmaceuticals. Major change was introduced by the Fourth International Conference on Harmonization in July 1997; a chronic rodent bioassay in one species and a short-term carcinogenicity assay are regarded as sufficient for registration. Such requirements provide the opportunity to redirect the vast resources previously spent on the lifetime study in the second species. Numerous experimental protocols for short- and intermediate-term carcinogenicity testing in many target tissues have been available for years. The first part of this review describes the basic principles of short- and intermediate-term carcinogenicity testing using the examples of the widely used mouse skin tumour assay and the rat liver foci assay. In the context of these experimental models, the discrimination and quantification of initiating and promoting activity and the use of preneoplastic lesions as endpoints in carcinogenicity testing are described. The review includes the limitations of the models with regard to the extrapolation from effects observed in animal experiments to a potential exposure of humans.

Glycogen storage disease I and hepatocellular tumours

From 50 published cases of hepatocellular adenoma (HCA) in glycogen storage disease, type I (GSD I) some characteristic features may be deduced: 1. The male:female ratio was 2:1. This sharply contrasts to HCA of other origin which shows a strong female preponderance. 2. The histology of adenomas largely corresponded to other adenomas, except for the appearance of Mallory bodies, accompanied by neutrophilic inflammation and a peculiar lamellar fibrosis. This observation is of particular interest because Mallory bodies have so far not been described in adenomas but are a well established feature in hepatocellular carcinoma of any aetiology. 3. Adenomas had a tendency to regress after continuous nocturnal intragastric feeding, although not all cases responded favourably. 4. Ten cases of hepatocellular carcinoma (HCC) are recorded in GSD I in literature, whereby in half of them transition from HCA into HCC seems likely. 5. The similarity in clinical presentation and evolution with oestrogen-induced tumours is striking. Pathogenesis of adenoma formation in GSD I is not understood. Experimental evidence and the clinical observation of regression after correction of the metabolic imbalance suggest three possible candidate mechanisms: (1) a glucagon/insulin imbalance; (2) cellular glycogen overload; and (3) proto-oncogene activation. Evidence in favour of these three mechanisms from experimental studies and observations in humans are briefly reviewed.

The role of hepatitis B virus in the development of primary hepatocellular carcinoma: Part I

Chronic infections with hepatitis B virus (HBV) of humans and animal hepadnavirus infections in their natural hosts are strongly associated with primary hepatocellular carcinoma (HCC). Although viral integrations are found in cells of many HCC, no general viral-specific hepatocarcinogenic mechanism for hepadnaviruses has been identified. In approximately one half of HCC in woodchuck hepatitis virus (WHV) infected woodchucks, viral integrations near the c-myc or N-myc genes have been reported which result in enhanced expression of the respective gene. Such host gene-specific insertional mutagenesis has not been found in HCC of other hepadnavirus infected hosts. Thus in humans, ground squirrels and ducks hepadnaviral integrations appear to be at different host chromosomal DNA sites in each HCC and few integrations have been found within or near any cellular gene. Other possible hepadnavirus-specific carcinogenic mechanisms that are being investigated include transactivation of cellular gene expression by an hepadnavirus gene product (e.g. the X-gene), and mutation of host genes by unknown hepadnavirus-specific mechanisms. It should be noted, however, that chronic hepadnavirus infection is associated with chronic necroinflammatory liver disease with hepatocellular necrosis and regeneration (sometimes leading to cirrhosis in humans), a pathological process that is common to numerous other risk factors for HCC. This suggests the possibility that this pathological process is hepatocarcinogenic irrespective of the inciting agent and the role of hepadnavirus infection is no different from that of other risk factors in causing chronic necroinflammatory liver disease.

Association of hepatocellular carcinoma and a hyperplastic nodule after phosphate diethylstilbestrol therapy

We treated a patient in whom a hepatocellular carcinoma and a hyperplastic nodule of the liver concomitantly grew in association with long term phosphate diethylstilbestrol therapy for a carcinoma of the prostate. A 72-year-old Japanese man was admitted for investigation of hepatic masses. A diagnosis of prostate carcinoma had been made seven years ago and phosphate diethylstilbestrol 200 mg daily had been prescribed. A small mass was first detected in the liver four years later and another mass appeared three years after the appearance of the first mass. Histology of the excised tissue showed the former mass to be a hyperplastic nodule and the latter one hepatocellular carcinoma. Findings of cirrhosis, hepatitis or fibrosis were nil but fatty metamorphosis of the hepatocytes was apparent. These histological changes were considered to be associated with long-term phosphate diethylstilbestrol therapy therefore careful follow-up using amazing diagnosis is recommended for patients on phosphate diethylstilbestrol therapy.

Sequential changes in growth kinetics and cellular phenotype during hepatocarcinogenesis

Sequential changes in cell proliferation and cellular phenotype during hepatocarcinogenesis induced in rats with N-nitrosomorpholine were investigated by autoradiographic determination of the [3H]thymidine-labelling index in morphologically defined focal lesions and extrafocal hepatic tissue at different times between 4 and 48 weeks after withdrawal of the carcinogen (stop model). The labelling index was found to be significantly increased in all types of preneoplastic and neoplastic hepatic lesions as compared to both the liver tissue of untreated controls and the extrafocal parenchyma of N-nitrosomorpholine-treated rats. However, the extent of the increase in labelling index differed in the phenotypically diverse types of preneoplastic and neoplastic lesions. There was a significant but relatively small increase in the labelling index in clear and acidophilic cell foci. A much stronger elevation of cell proliferation was characteristic of mixed and basophilic cell foci. The development of hepatocellular adenomas and carcinomas from preneoplastic hepatic foci was further characterized by an additional increase in cell proliferation. Each specific cellular phenotype was associated with a rather uniform proliferation rate, which remained elevated at all time points studied, suggesting that the rate of cell proliferation in the phenotypically diverse preneoplastic hepatic foci mainly reflects the intrinsic growth potential of the respective cellular phenotypes. The results support the concept that the predominant sequence of cellular changes in hepatocarcinogenesis induced by the stop model leads from the clear and acidophilic cell foci, storing glycogen in excess, through mixed and basophilic cell foci to hepatocellular adenomas and carcinomas. The fact that the labelling index of the extrafocal liver tissue of N-nitrosomorpholine-treated rats was also significantly higher than that of the normal parenchyma of untreated controls might indicate an involvement of extrafocal hepatocytes, in addition to that of foci of altered hepatocytes, in hepatocarcinogenesis.

Biochemical microanalysis of alpha-glucosidase activity in preneoplastic and neoplastic hepatic lesions induced in rats by N-nitrosomorpholine

Preneoplastic and neoplastic hepatic lesions were induced in male Sprague-Dawley rats by oral administration of N-nitrosomorpholine (NNM) for 7 weeks at a concentration of 200 mg/l of drinking-water (stop model). Using a laser dissection technique and biochemical microanalysis, the activity of the lysosomal enzyme alpha-glucosidase was measured in glycogen storage foci emerging early, and in mixed or basophilic cell populations (foci and carcinomas) appearing later during hepatocarcinogenesis. In the liver tissue of normal appearance in both untreated controls and NNM-treated animals a slight gradient of alpha-glucosidase activity was observed leading from relatively high activities in zone 1 to lower activities in zone 3 of the liver lobule. In preneoplastic glycogen storage foci a considerable relative reduction in alpha-glucosidase activity was detected, suggesting that a decrease in the hydrolytic glycogen degradation contributes to the disturbance in phosphorylytic glycogen breakdown observed earlier in the majority of the glycogenotic foci. In contrast with glycogen storage foci, mixed and basophilic cell foci and particularly hepatocellular carcinomas showed a marked increase in alpha-glucosidase activity compared with that of normal liver tissue. The gradual enhancement in enzyme activity appeared to be closely related to the reduction in glycogen initially stored in excess during the later stages of hepatocarcinogenesis. The results support the concept that a fundamental shift in carbohydrate metabolism is characteristic of neoplastic transformation of hepatocytes.

Failure of hepatic adenomas (HCA) to regress after discontinuance of oral contraceptives. An association with focal nodular hyperplasia (FNH) and uterine leiomyoma

Oral contraceptives have been implicated in the development of hepatic cellular adenomas (HCA) and associated in at least one report with focal nodular hyperplasia (FNH). Recurrence of lesions or progression while the patient is no longer receiving exogenous steroids is less well documented. Three cases are reported in which progression or recurrence of HCA after the discontinuance of steroids was documented. In addition, FNH and uterine leiomyomas with HCA were observed in all three cases. The mechanism of tumor formation secondary to the use of oral contraceptives remains undetermined. In two cases, liver tissues were tested for estrogen receptors; both were found to be negative. Although technique as well as the observed progression of these lesions or development of new lesions after the discontinuance of steroids may account for this negative finding, it suggests that induction of this process may be caused by means other than direct cellular stimulation by the exogenous hormones. Finally, these three cases call attention to a potential subgroup of patients having oral contraceptive-associated HCA who may have progression of their liver tumors when no longer receiving steroids and who require an aggressive treatment program and noninvasive follow-up examinations.

Immunohistochemical demonstration of decreased L-pyruvate kinase in enzyme altered rat liver lesions produced by different carcinogens

Preneoplastic liver lesions were produced in female Wistar rats by application of 25 mg/kg N-nitrosomorpholine (NNM), 14 mg/kg diethylnitrosamine (DENA), 0.075 mg/kg aflatoxin B1 (AFB1) or 160 mg/kg safrole. These carcinogens were administered in two equal doses 12 and 24 h after partial hepatectomy. The animals then received sodium phenobarbital (0.1% in tap water) for up to 410 days. Numerous altered hepatic foci (AHF) and hyperplastic nodules (HN) were detected enzyme histochemically by their negative ATPase reaction after application of AFB1, DENA and NNM; some AHF and HN were also caused by the weak carcinogen safrole. Immunohistochemically these lesions were also L-pyruvate kinase (L-PK)-negative with a high coincidence with regard to their number and area. These results confirm the role of L-PK, an enzyme affecting the pentose phosphate pathway, as a negative marker of preneoplastic liver lesions.

Decrease in glucokinase and glucose-6-phosphatase and increase in hexokinase in putative preneoplastic lesions of rat liver

Preneoplastic liver lesions were produced in female Wistar rats by oral administration of 2-acetylaminofluorene for 165 days succeeded by a carcinogen-free standard diet up to 420 days. During the treatment numerous altered hepatic foci (AHF) and hyperplastic nodules (HN) were detected histochemically by a focal decrease or lack of adenosine-5-triphosphatase and glucose-6-phosphatase (G-6-Pase) activities. In addition, the immunohistochemically demonstrable amount of L-type pyruvate kinase was clearly reduced. The histochemically demonstrated decrease of G-6-Pase was substantiated by microbiochemical determination of the enzyme activity in microdissected material. Moreover, during the experimental period a continuous decrease in glucokinase and an increase in hexokinase was detected microbiochemically within AHF and HN. These alterations indicate a shift in the carbohydrate metabolism from gluconeogenesis to glucose utilization and pentose-phosphate-pathway for biosynthesis of nucleic acids. Beside other oncofetal markers, HK may be used as indicator of the early stages of liver carcinogenesis.

Increased UDP-glucuronyltransferase and gamma-glutamyltranspeptidase in enzyme-altered rat liver lesions produced by low doses of aflatoxin B1

Preneoplastic liver lesions were produced in female Wistar rats by low doses of aflatoxin B1 (Model 1: administration of 37.5 micrograms/kg 12 and 24 h after partial hepatectomy; Model 2: continuous application of 3.5 micrograms/kg in tap water daily for 28 days with partial hepatectomy after 14 days. The animals then received sodium phenobarbital, 0.1% in tap water, for 180 to 400 days). In both models numerous altered hepatic foci (AHF) and hyperplastic nodules (HN) were detected enzyme histochemically by their negative ATPase and positive gamma-glutamyltranspeptidase reactions. Immunohistochemically these lesions were also UDP-glucuronyltransferase positive. Increased UDP-glucuronyltransferase adds to permanent alterations of a number of drug metabolizing enzymes observed in a variety of different tumor models. These alterations are responsible for the toxin-resistant phenotype (Faber 1984b). Increased gamma-glutamyltranspeptidase was detected both enzyme histochemically and immunohistochemically; whereas gamma-glutamyltranspeptidase activity was present in both AHF/HN and in periportal areas by enzyme histochemistry, the immunohistochemical method selectively stained gamma-glutamyltranspeptidase in AHF and HN. Immunohistochemically detectable UDP-glucuronyltransferase and gamma-glutamyltranspeptidase are markers of putative precancerous liver lesions which may be useful in the analysis of the prestages of liver carcinogenesis.