Actin content and polymerization in tumour, liver and serum of the hepatoma Morris 5123 tumour bearing rats

Monomeric G-actin, total actin and filamentous F-actin were examined during the growth of experimental tumour hepatoma Morris 5123. Actin was measured by the inhibition of the standard DNase I from bovine pancreas. A remarkable increase in total actin, and F-actin content, as well as in the state of actin polymerization (measured by the F:G actin ratio) was shown in the cytosol of the tumour cells in the second week of the tumour growth, followed by a rapid decrease in the third week. Parallel observations were made in the cytosol of the liver and in the serum of the tumour bearing rats. The results were compared with the data obtained for control healthy rats. It was shown that hepatoma Morris tumour growth is accompanied by the changes in the actin content and polymerization, occurring also in the liver of the host animal. Only G-actin was found in the serum. It increased significantly in the second week of tumour growth as compared with the G-actin level in the serum of the control healthy rats.

Correlation between serum prolactin levels and hepatocellular tumorigenesis induced by 3'-methyl-4-dimethylaminoazobenzene in mice

Ovariectomy at 1 month of age promotes development of hepatocellular adenomatous nodules in female C57BL/6 x DS-F1 mice treated neonatally with 3'-methyl-4-dimethylaminoazobenzene (3'-Me-DAB). Implantation of oestradiol-17 beta (E2) pellets at 1 month of age suppresses nodule development. Since E2 increases serum levels of prolactin, high serum levels of prolactin in mice that have received implants of E2 pellets may play a role in the suppression of hepatocellular tumorigenesis. Therefore, to investigate the role of prolactin in hepatocellular tumorigenesis, we examined development of adenomatous nodules in female mice that had been treated neonatally with 3'-Me-DAB and had undergone ovariectomy at 1 month of age, under various serum levels of prolactin. Treatment of these mice with perphenazine (dopamine antagonist) from 6 months of age or transplantation of pituitary glands under the renal capsule at 6 months of age markedly increased serum levels of prolactin and significantly suppressed the incidence of adenomatous nodules at 12 months of age. Implantation of E2 pellets at 1 month of age increased serum levels of prolactin to a greater extent and further decreased the incidence of adenomatous nodules. Treatment of mice that had received implants of E2 pellets at 1 month of age with bromocriptine (dopamine agonist) from 6 months of age decreased serum levels of prolactin, and was accompanied by an increase in the incidence of nodules. The present results showed that an increase in serum levels of prolactin was accompanied by a decrease in incidence of liver tumours induced by 3'-Me-DAB in mice, suggesting a suppressive effect of prolactin on liver tumorigenesis in mice. Thus, it is possible that the suppressive effect of oestrogen on liver tumorigenesis in mice is mediated, at least in part, by prolactin.

The effects of tumour growth on circulating amino acids in the late pregnant rat

The implantation of a rapidly-growing tumour--the AH-130 Yoshida ascites hepatoma--to late pregnant rats resulted in important changes in both the maternal and fetal amino acid concentrations. Increased concentrations of most amino acids--glycine, alanine, threonine, serine, proline, glutamate+glutamine, valine, leucine, isoleucine, phenylalanine, tyrosine and lysine--are found in the fetal circulation, the concentration of total and essential amino acids being clearly higher than in the non-tumour bearing controls. In the maternal circulation, the presence of the tumour also caused increases in the concentration of glycine, lysine, glutamate+glutamine and arginine. Conversely, tumour-bearing rats had lower concentrations of threonine, serine, aspartate+asparagine, valine, leucine, phenylalanine and histidine. These results support the described increased fetal availability of amino acids during tumour growth (Carbó, N., López-Soriano, F.J. and Argilés, J.M. (1994). In the late pregnant rat, tumour growth results in an increased availability of fetal amino acids. Biochem. J., in press) and allow us to suggest that important changes in placental amino acid transport systems must be induced by tumour burden.

Urinary and serum mutagenicity studies with rats bearing experimental tumours

Urine and serum samples of rats bearing three different experimental tumours (hepatocellular carcinoma, myelomonocytic leukemia and mesoblastic nephroma) were investigated for mutagenicity with the Ames Salmonella test. Enhancement of mutagenic activity in TA98 and TA100 was observed only in the case of urine samples obtained from animals bearing nephromas. Mutagenicity increased with increasing time after implantation of tumours. There was no coincidence between urinary and serum mutagenicity under the experimental conditions employed. Further studies are needed to determine the origins, and chemical and genotoxic characteristics of urinary mutagens. In addition, the question as to whether any mutagenic substances can be detected in fractions of plasma/serum should also be experimentally addressed.

Lactate release and uptake in hepatoma 7288CTC perfused in situ with L-[(U)-14C]lactate or D-[(U)-14C]glucose

Arteriovenous differences (AVD) for glucose and lactic acid measured across tissue-isolated rat tumors in vivo have shown that individual tumors with similar rates of glucose consumption may either release or utilize lactic acid. The experiments described here investigated the relationships among arterial blood lactate concentrations and tumor lactate and glucose balances. AVDs for lactate, pyruvate, glucose, 14CO2, PO2, PCO2, pH, and lactate specific activities were measured across 17 tissue-isolated 7288CTC hepatomas perfused in situ with arterial blood containing 2.5 to 14.4 mmol/L lactate and either L-[(U)-14C]lactic acid or D-[(U)-14C]glucose. Measurements were made over a range of blood flow rates from 60% to 200% of the mean in vivo rate, 0.11 mL/min. Data collected during steady states were compared by regression analysis. Tumor lactate balance and the arterial blood lactate concentration were directly related (r = .895, n = 22, P < .01). Net negative and positive balances occurred below and above approximately 6.5 mmol/L arterial blood lactate, respectively. The mean intratumor lactate concentration for all tumors was 6.9 +/- 1.0 mmol/L (mean +/- SD, n = 13). Rates of 14C-lactate oxidation to 14CO2 (r = .716, n = 18, P < .01) and tumor venous/arterial blood 14C-lactate specific activity ratios (r = .845, n = 19, P < .01) were low during lactate release and were increased during lactate uptake. Total arterial blood lactate removal estimated from chemical and isotopic analyses was 23.1% +/- 11% and 43.0% +/- 16% (P < .05), respectively, for six lactate-utilizing tumors. Perfusions performed with 14C-glucose showed that approximately 50% of the glucose consumed during net negative lactate balance was released as 14C-lactate to the tumor venous blood, whereas only 5% was released as 14C-lactate during net positive lactate balance. The data support the following conclusions: Arterial blood lactate controls net lactate balance in solid tumors; high concentrations increase uptake. Lactate uptake inhibits lactate formation from glucose without changing the glucose balance. Lactate is release during net lactate uptake. Since lactate uptake may exceed glucose uptake, arterial blood lactate can be a substrate for tumor energy metabolism and growth.

Anti-tumour necrosis factor-alpha treatment interferes with changes in lipid metabolism in a tumour cachexia model

1. Rats bearing the Yoshida ascites hepatoma AH-130 showed an important decrease in white adipose tissue lipoprotein lipase activity as compared with non-tumour bearing rats. This was associated with a lower adipose tissue mass, as estimated from the weight of the lumbar fat-pads. Conversely, lipoprotein lipase activity was markedly increased in brown adipose tissue and heart. 2. These changes were associated with a distinct hyperlipaemia, essentially manifested as an increase in circulating triacylglycerol levels, whereas no changes were observed in glycaemia. 3. Tumour-bearing rats were treated with a polyclonal anti-murine tumour necrosis factor-alpha antibody or with a non-immune IgG preparation. Control animals were either untreated or received a non-immune IgG preparation. Anti-tumour necrosis factor-alpha treatment resulted in a significant increase in lipoprotein lipase activity in white adipose tissue in animals bearing a tumour growing exponentially (day 4 after inoculation) as compared with the animals receiving a non-immune goat IgG preparation. In addition, animals bearing an stationary tumour (day 7 after inoculation) and submitted to anti-tumour necrosis factor-alpha treatment had a higher adipose tissue lipoprotein lipase activity as compared with the IgG- or the non-treated groups. Correspondingly, circulating triacylglycerol levels were markedly decreased, with a lower hyperlipaemia than in control tumour-bearing rats. 4. These observations suggest that tumour necrosis factor-alpha is involved in activating the lipid metabolic changes that develop in rats after transplantation of a fast-growing tumour.

Myocardial effects of experimental neoplastic disease

The purpose of this study was to determine the effects of the 7288ctc Morris hepatoma on heart size and performance. Hearts from tumor bearing and control animals were perfused in the working configuration one to three weeks post implantation. As tumor growth progressed there was an inverse linear relationship between tumor size and heart weight. When intrinsic heart work (defined as the product of the cardiac output and peak systolic pressure) was assessed in vitro over a range of physiologic preloads, significant differences were found between tumor-bearing and non-tumor-bearing animals. The hearts from the tumor-bearing animals (tumor weight 10-20 grams) developed only 76% of the heart work of control animals at maximal left atrial filling pressure (25 cm H2O). Hearts excised from rats with tumor masses from 30-65 grams developed 43% of the myocardial work as controls at the same (25 cm) preload. At the time of sacrifice resting blood pressures, blood glucose, insulin, and tumor necrosis factor (TNF) levels were similar in both groups. Blood from tumor bearing animals were negative for both aerobic and anaerobic bacteria. The data suggests that the decrements in cardiac size and performance are independent of several vectors known to influence heart size and performance and occur in the absence of detectable bacteremia.

Cancer cachexia, malnutrition, and tissue protein turnover in experimental animals

The role of malnutrition in the development of cachexia in rats bearing the Yoshida ascites hepatoma AH-130 was investigated by comparing the changes in tissue protein turnover in these animals with those observed in pair-fed controls. The tumor elicited in rats an early and conspicuous loss of body weight and tissue waste. Protein loss was particularly prominent for the gastrocnemius muscle and the heart and less pronounced for the soleus, while the diaphragm was little affected. Liver, kidneys, and spleen transiently increased in weight then regressed and eventually atrophied, while adrenals were enlarged over the whole experimental period. Protein waste was mainly due to acceleration of tissue protein breakdown, this protein hypercatabolic state being associated with increased cathepsin D activity in liver and gastrocnemius. In pair-fed animals the liver showed a marked protein loss resulting from enhanced catabolism, while the sharp decrease of heart protein content and the less prominent waste of the gastrocnemius were due to a reduction in protein synthesis. The total plasmatic concentration of free amino acids in AH-130-bearing rats was decreased at Day 4, when the tumor was actively proliferating, and returned to control values at Day 10, when the tumor had reached a stationary state. On the contrary, in pair-fed animals total plasma amino acids decreased over the whole experimental period. Plasma branched-chain amino acids were unchanged or even decreased in tumor hosts, while the Gly/Pro ratio was elevated in pair-fed rats. The intracellular concentration of free amino acids was higher in stationary than in exponentially- growing tumors, reflecting the enhanced proteolytic rates observed in stationary tumor cells. On the whole, the results suggest that reduced food uptake and metabolic competition by the tumor are not sufficient to justify the marked hypercatabolism in host tissues during the AH-130 hepatoma growth. The profound differences between tumor-bearing and pair-fed animals suggest that, if malnutrition undoubtedly played a role in this model of cancer cachexia, its effects were overwhelmed and subverted in the frame of the tumor-host interplay that dictated a distinctively peculiar syndrome.

Elevated serum alpha-fetoprotein level of nude mice bearing hepatoma cells by treatment with monoclonal antibodies to alpha-fetoprotein

This study was carried out to clarify the reason for elevation of serum alpha-fetoprotein (AFP) level of nude mice bearing hepatoma cells after treatment with monoclonal antibodies (MoAbs) to AFP. MoAbs to AFP showed no effect on the cumulative amounts of AFP secreted from human hepatoma cell line, HuH-7, in vitro. However, the treatment of nude mice bearing HuH-7N cells (HuH-7 xenograft) with MoAbs to AFP led to elevation of the serum AFP level in spite of the fact that the growth curve of HuH-7N cells was similar to that for PBS treatment. This apparent elevation of the serum AFP level is thought to be due to the slow elimination of AFP-MoAb immune complexes with little lattice structure from circulation, but not the enhancement of AFP secretion of HuH-7N cells. Thus, when using a MoAb alone or MoAb-drug conjugate, the serum AFP level should only be cautiously used as a tumor marker for evaluating the targeting immunotherapy.

Impairment of insulin action on peripheral glucose uptake and hepatic glucose production in tumor-bearing rats

The present study was performed to determine the time-course for the development of peripheral and hepatic insulin resistance in rats as a result of an increasing tumor burden. Animals were inoculated with Yoshida ascites hepatoma, and studies were conducted during the early phase of tumor growth (day 4) at which time there was no change in food intake and at a later time point (day 8) when the tumor burden was increased and rats demonstrated anorexia. In vivo insulin action was accessed under euglycemic hyperinsulinemic conditions, in which insulin was infused at rates sufficient to produce arterial insulin levels that represent high physiological (3.5 ng/ml) or maximally stimulating values (180 ng/ml). On day 4, tumor-bearing (TB) rats were euglycemic, and whole body glucose turnover was elevated 32%. Insulin-mediated glucose uptake (IMGU) in TB rats was similar to control values at the low insulin infusion rate but reduced by 53% under maximally stimulating conditions. The insulin-induced suppression of glucose production was similar in TB and control animals at this time point. In contrast, on day 8, TB rats were hypoglycemic and glucose turnover was reduced 35%. The impairment in IMGU was more severe than seen earlier, with glucose uptake being reduced 39 and 61% at both levels of hyperinsulinemia. At this time point, the ability of insulin to inhibit glucose production was also impaired. These results indicate that the insulin resistance induced by the Yoshida hepatoma was manifested initially by a reduction in IMGU by peripheral tissues. As the tumor burden increased peripheral insulin resistance became more severe and an impairment in hepatic insulin action was observed.

The spleen can influence the metastasis of AH130 hepatoma cells in rats

The effect of pathophysiological conditions due to disturbance of the spleen is still unclear. We studied the effects of splenectomy in normal and methylcellulose-induced hypersplenic rats on the development of pulmonary metastases created by intravenous injection of ascites containing AH130 hepatoma cells from male Hos-Donryu rats. Growth of metastatic lesions in the lung was not affected by splenectomy in normal rats, but was increased by splenectomy in hypersplenic rats. Overall, there were fewer pulmonary metastases in rats with hypersplenism, but after splenectomy rats with hypersplenism had a significantly greater number of metastases than did normal rats. The metastases rate correlated somewhat with changes in the blood coagulation and T lymphocyte profile. There is a relationship between the spleen and formation of metastases in cancer. Formation of metastases in the lung was affected most by splenectomy in hypersplenism. To elucidate the mechanism by which metastases are formed in the lung under these pathologic conditions, further studies on the exact role of the spleen are required.

Evaluation of a new lipophilic prodrug 3', 5'-dioctanoyl-5-bromodeoxyuridine (BrdU-C8) suspended in Lipiodol as a radiosensitizer for the treatment of AH136B tumor

The effect of anti-cancer treatment on the AH136B tumor was studied using external beam irradiation in combination with a new oil-soluble agent, 3', 5'-dioctanoyl-5-bromodeoxyuridine (BrdU-C8), a lipophilic prodrug of BrdU. BrdU-C8 was dissolved in an oily lymphographic agent, Lipiodol (BrdU-C8/Lipiodol). BrdU-C8/Lipiodol is selectively accumulated in the neovasculature of the tumor and gradually releases BrdU. The AH136B tumor cell, a transplantable rat ascites hepatoma cell line, was implanted in the dorsal foot of rats. In vivo labeling index (L.I.) of the tumor cells after the intraarterial infusion of BrdU-C8/Lipiodol was significantly increased compared to the L.I. observed after intraarterial or intravenous infusion of BrdU. In addition, X-ray irradiation in combination with intraarterial infusion of BrdU-C8/Lipiodol significantly inhibited the tumor growth, indicating the increased radiosensitizing effect.

MR imaging of blood oxygenation-dependent changes in focal renal ischemia and transplanted liver tumor in rat

The potential of using fast magnetic resonance (MR) imaging in conjunction with apnea-induced blood deoxygenation for the noninvasive monitoring of relative perfusion in the rat abdomen has been studied with two experimental models: glycerol-induced focal renal ischemia and transplanted liver tumor. Gradient-echo echo-planar imaging (GRE-EPI) (TE of 20 msec at 2T) of liver and kidney was performed before, during, and after a 60-second apnea episode and then was followed in the same rat by contrast-enhanced (a) GRE-EPI and (b) T1-weighted spin-echo imaging (TR msec/TE msec = 200/6) with polylysine-(gadolinium-DTPA [diethylenetriaminepentaacetic acid]). The results indicate that a noninvasive vascular challenge due to apnea can be used for the detection of focal tissue perfusion abnormalities in rat kidney and liver tumor.

Deoxyribonuclease treatment prevents blood-borne liver metastasis of cutaneously transplanted tumour cells in mice

Murine L5178Y-ML cells, when transplanted subcutaneously into the flank of (BALB/c x DBA/2)F1 mice, grew locally and always formed spontaneous metastases in the liver. Even after surgical removal of the primary tumour mass 5 or 7 days after tumour cell inoculation, all mice died due to liver metastases within 18 days. Using this model of tumour metastasis, we examined whether serine protease or deoxyribonuclease I (DNase I) would affect metastasis. Spontaneous liver metastasis of L5178Y-ML cells was enhanced by systemic administration of alpha-chymotrypsin at 3, 4 and 5 days or at 5, 6 and 7 days after tumour cell inoculation. This result was consistent with a previous report on blood-borne lung metastasis. In contrast, systemic administration of DNase I at 3, 4 and 5 days or at 5, 6 and 7 days after tumour cell inoculation inhibited liver metastasis. Neither treatment affected primary tumour growth. An influence of DNase I on tumour cell arrest in the microvasculature of the liver was suggested by scanning electron microscopy. DNase I treatment resulted in a statistically significant prolongation of the survival period, however, the effect was not satisfactory. A more striking anti-metastatic treatment resulting in a greater prolongation of the survival period was achieved by combining surgical removal of the primary tumour mass with DNase I treatment. These results suggest that DNase I could be a potential therapeutic agent used in conjunction with surgery to prevent clinical blood-borne metastasis.

Humoral mediation for cachexia in tumour-bearing rats

Early and severe loss of body weight associated with pronounced tissue changes developed in rats transplanted with a fast-growing ascites hepatoma (Yoshida AH-130). The protein content showed an early and marked fall in the skeletal muscle, while in the liver it transiently increased 4 days after implantation then declined to values lower than in control animals. Protein loss in gastrocnemius muscle and liver resulted mainly from enhancement of protein catabolism (Tessitore L. et al., Biochem. J., 241: 153-158, 1987). In contrast to the tumour-bearing rats, in the pair-fed animals the initial body weight was maintained, while the protein mass decreased sharply in the liver and moderately in the gastrocnemius muscle. In host animals total plasma protein decreased during the period of tumour growth, while both triglycerides and total cholesterol markedly increased. Glucose remained unchanged even when overt cachexia had developed. The total free amino acid concentration in the plasma of tumour-bearing rats decreased slightly by day 4 and returned to values close to those of controls in the late stages of tumour growth. By contrast, in the pair-fed controls the plasma levels of triglycerides and particularly of total free amino acids and glucose decreased over the whole experimental period, whereas total protein and cholesterol were unchanged. Marked perturbations in the hormonal homeostasis developed early after tumour transplantation. The plasma levels of glucagon, corticosterone and catecholamines rose sharply, while those of insulin and thyroid hormones decreased. Furthermore, high plasma concentrations of prostaglandin E2 (PGE2) and tumour necrosis factor (TNF) were observed over the whole experimental period. IL-1-like activity, TNF and PGE2 were released in vitro from AH-130 cells. These data suggest that the systemic effects of AH-130 tumour on the host rat reflected the interplay of a complex network of factors, including classical hormones and cytokines, all of which likely concur in enhancing tissue protein catabolism.

Hepatic metastasis alters the immune function of murine liver nonparenchymal cells

To examine the effect of a single hepatic focus of metastatic colon tumor on the immune function of liver non-parenchymal cells (NPCs) from C57Bl/6 mice, we injected 2.5 x 10(5) liver-derived murine colon adenocarcinoma (LD-MCA-38) cells beneath the liver capsule. Three weeks following injection of the tumor cells, the immune function of the NPCs was studied. The NPCs from tumor-bearing mice exhibited increased cytotoxic and proliferative activity. The NPCs from tumor-bearing mice also contained a greater percentage of CD8+ and T-cell receptor gamma/delta+ liver-associated T lymphocytes. Levels of interleukin 6 and tumor necrosis factor were increased in the NPC supernatant, and interleukin 6 levels were increased in serum from tumor-bearing mice. We conclude that the presence of a single hepatic focus of metastatic tumor results in augmented immune function of murine liver NPCs.

Inhibitory effect of 2-deoxy-D-glucose on liver tumor growth in rats

Since tumor cells are more dependent on glycolysis for energy supply than other cells, we tested whether its inhibition by 2-deoxy-D-glucose (2-DG) affects tumor growth. Male Wistar rats were inoculated in the liver with tumor cells from a chemically induced colonic adenocarcinoma. From day 5 after inoculation 2-DG (400 mg/kg/24 h) was continuously infused into the hepatic artery for 5 days; controls received saline in the same fashion. Seven days after the end of infusion, the animals were sacrificed. A second experimental group of rats was treated with isolated liver perfusion for 30 min with oxygenated blood through the portal vein and hepatic artery simultaneously. In the perfusate, 400 mg/kg 2-DG were added, and the rats were sacrificed at 10 days after perfusion. A first control group underwent perfusion without 2-DG, and a second control group received i.v. infusion of 2-DG (400 mg/kg/30 min) for 30 min over 5 days. A nontreated control group was also added. All animals survived the procedures. The concentration of blood glucose increased in the rats receiving 2-DG i.v. and intraarterially but was unchanged in the other groups. The tumor growth was significantly reduced by 2-DG in all experimental groups, with no difference between the groups. It is therefore concluded that 2-DG is of potential interest in the treatment of malignancies. Since local application of 2-DG avoids the risk for systemic side effects, this approach should be explored further.

Inconsistent expression of glycolipid sulfotransferase activity between hepatoma and serum

Glycolipid sulfotransferase activity in human and rat hepatocellular carcinoma tissues was studied, since an elevated level of the enzyme activity in serum had been demonstrated in cancer patients. The level of the enzyme activity in carcinoma tissues, however, could not be distinguished from that of normal controls. Similar observations were made for rat hepatoma. A higher level of enzyme activity was observed in the female than in the male. Inconsistent expression between hepatoma tissue and serum suggests that humoral factor(s) derived from hepatoma tissue stimulates production of the sulfotransferase, which is released into the blood-stream in the host.

[Role of polymorphonuclear leukocytes (PMN) and active oxygen species in hyperthermia--antitumor effect of hyperthermia combined with rhG-CSF]

We have reported that polymorphonuclear leukocytes (PMN) and active oxygen species from PMN may play an important role in the mechanism of the antitumor effect of hyperthermia. At this time, we focused our experimental studies on rat AH109A carcinoma treated with hyperthermia combined with arterial injection of rhG-CSF. Rats with transplantable AH109A carcinoma at the hind leg received hyperthermia. These tumors showed mild suppression of further development only by hyperthermia. However, when arterial injection of rhG-CSF was applied together with hyperthermia, marked suppression of tumor development was observed. Our data suggest that hyperthermia combined with rhG-CSF is closely related to the generation of free radical-mediated tumor cell killing, and it can be an effective treatment for cancer.

Serum epoxide hydrolase (preneoplastic antigen) in human and experimental liver injury

Reports of an increase in a serum epoxide hydrolase (sEH), immunochemically related to microsomal EH in humans and rats with hepatocellular carcinoma (HCC), suggested its use as a serum marker for this disease. We have now measured sEH levels (as either immunochemically determined content or enzyme activity) in a number of human and experimental models of liver disease. sEH was elevated above the normal range in at least 50% of individuals with HCC, including: 3 of 6 northern Californians; 4 of 7 Koreans with hepatitis B-associated HCC; hepatitis B-associated HCC in woodchucks; and male rats receiving chronic treatment with aflatoxin B1 or ciprofibrate. sEH was rarely elevated in other forms of chronic liver disease. Only 2 of 9 Koreans with hepatitis B-associated cirrhosis, 1 of 8 carriers, but none with chronic active hepatitis or infection with no apparent liver disease had elevated sEH. In addition, no elevations were found in woodchucks with noncancerous viral hepatitis. In aflatoxin B1- and M1-treated rats sEH was not elevated in those with only hyperplastic foci or hepatocellular adenomas, and in two rat initiation-promotion protocols sEH was elevated only in those rats which received the entire set of treatments. sEH was also increased during acute hepatotoxicity in rats treated with CCl4 or 1,2-dibromo-3-chloropropane. The mechanism of increase in sEH during hepatocarcinogenesis appears to be different from that of other markers of HCC, for in the Korean patients, there was no correlation between sEH concentrations and those of alpha-fetoprotein or ferritin, nor was there a correlation with alpha-fetoprotein concentrations in the aflatoxin-treated rats. Furthermore, the increase in sEH does not correlate with induction of microsomal EH in the liver of experimental animals. Studies to date indicate that sEH is selective for HCC and severe hepatonecrotic injury, and may be of some use in the diagnosis of HCC, particularly as a complement to other serum markers.

Lack of modifying effects of 6-mercaptopurine in a medium term bioassay system for liver carcinogenesis using male F344 rats

Carcinogenic and modification potential of 6-mercaptopurine (6-MP) was studied in a medium-term bioassay system for rat liver carcinogenesis. F344 male rats were initiated with a single dose (200 mg/kg body wt.) of diethylnitrosamine (DEN) i.p. and fed diets containing either 0.005% or 0.02% 6-MP with or without 0.05% phenobarbital (PB) for 6 weeks. Quantitative data revealed that 6-MP did not enhance the appearance of enzyme-altered preneoplastic foci and nodules even when administered at the highest dose (0.02%) despite showing an immunosuppressive effect and slight liver cell damage. Neither of the doses of 6-MP exerted any significant influence on the enhancing effect of PB when administered simultaneously in the medium-term-bioassay.

Inhibitory effect of sarcophytol A on development of spontaneous hepatomas in mice

The inhibitory effect of sarcophytol A, a cembrane-type diterpene isolated from a marine soft coral, Sarcophyton glaucum, on development of spontaneous hepatomas was investigated in C3H/HeNCrj mice. A total of 80 mice were divided equally into two groups. The experimental and control groups were given basal diets with and without 0.01% sarcophytol A, respectively. At week 65 of the experiment, mice were examined for hepatomas. The percentages of hepatoma-bearing mice of the subgroup with three or more tumors and the tumor diameters of the group treated with sarcophytol A were smaller than those of the control group. Ridit analysis revealed that these differences were statistically significant. The body weight gain, and the food intake were not significantly different between these two groups. Analysis of blood serum revealed that feeding the diet containing 0.01% sarcophytol A for 65 weeks did not show any adverse effects. These results suggest that sarcophytol A inhibits the development of spontaneous hepatomas without toxicity, and should be considered as a possible cancer chemopreventive agent for hepatomas in humans.

Hyperammonemia and anorexia in Morris hepatoma-bearing rats

Inoculation of Buffalo rats with Morris hepatoma produced significant anorexia within four weeks and reduced body weight within two weeks. Blood ammonia concentration was increased by 113% when the rats were euthanized, five days after the development of anorexia. Infusing ammonium salts into normal Buffalo rats also induced anorexia at a blood ammonia concentration comparable to that observed in the tumor-bearing rats. Although ammonia-infused rats exhibited expected increases in brain tyrosine, tryptophan, and metabolites of dopamine and serotonin, these alterations were attenuated in the tumor-bearing rats. These results indicate that hyperammonemia may be a general consequence of experimental cancer and that the increase in ammonia concentration may be of primary importance in the development of experimental cancer-induced anorexia. The rather small alterations in neurotransmitter metabolism in anorectic tumor-bearing rats deemphasize the role aberrations in DA and 5-HT systems in the development of experimental cancer anorexia.