Effect of dietary conjugated linoleic acid on the in vivo growth of rat hepatoma dRLh-84

We examined the effect of dietary conjugated linoleic acid (CLA) on the growth of injected hepatoma dRLh-84 in Donryu rats. After experimental diets containing 0% or 2% CLA were given to male Donryu rats for 3 wk, dRLh-84 cells were injected into the left lobe of the hepatic capsule, and the experimental diet was continued. The cells formed a solid tumor > or = 1 wk after the injection, and thereafter the tumor grew with feeding duration. In a morphological study, this tumor appeared to be a low-differentiated hepatoma, and there was no remarkable difference in the morphology of the tumor between 0% and 2% CLA groups. Tumor weight was significantly higher in the 2% CLA group than in the 0% CLA group throughout the feeding period after the injection. Serum glutamic-oxaloacetic transaminase and glutamic-pyruvic transaminase activities were significantly higher in 2% CLA-injected rats than in 0% CLA-injected rats at 3 wk after the injection. CLA upregulated acyl-CoA oxidase activity, especially 1 wk after the injection. However, dietary CLA did not activate carnitine palmitoyl transferase II, which is a rate-limiting enzyme in the mitochondrial beta-oxidation pathway. Natural killer cell activity in the spleen tended to be higher in injected rats, but a significant effect of dietary CLA was not recognized. Serum interferon-gamma and tumor necrosis factor-alpha levels were higher in injected than in sham rats. Moreover, these levels were higher in 2% CLA groups than in the respective 0% CLA groups.     

Use of 5-FU plus hyperbaric oxygen for treating malignant tumors: evaluation of antitumor effect and measurement of 5-FU in individual organs

PURPOSE: Hyperbaric oxygen (HBO) has been shown to increase tumor radiosensitivity. Several reports indicate that it also increases sensitivity to alkylating agents, but other reports suggest that it may speed angiogenesis and tumor growth. To throw light on these questions, we investigated the effects of HBO and 5-fluorouracil (5-FU), individually and in combination, on Sarcoma 180 implants in mice. METHODS: We administered 5-FU at a dose of 0.75 mg/mouse six times per week and HBO at 2 atm absolute pressure for 90 min six times per week, both 17 times in total. In combination treatment, HBO was administered immediately after 5-FU injection. RESULTS: Over the treatment period, tumor diameter increased 277.8% in the untreated control group, 244.1% in the group receiving HBO monotherapy, 182.7% in the group receiving 5-FU monotherapy, and 138.5% in the group receiving combination therapy. Concomitant HBO increased accumulation of 5-FU in the tumors, liver, and kidneys, but not in the brain, of recipient animals. CONCLUSIONS: Based on the above results, we conclude that concomitant HBO enhances the effects of 5-FU.     

Gap junction proteins connexin32 and connexin43 partially acquire growth-suppressive function in HeLa cells by deletion of their C-terminal tails.

Our laboratory has previously reported that transfection of a connexin26 (Cx26) gene, but not connexin40 nor connexin43 (Cx43), into HeLa cells expressing no detectable level of connexins suppressed the tumorigenic phenotype of the HeLa cells both in vitro and in vivo, although all of these connexins induced gap junctional intercellular communication in HeLa cells to a similar extent. The most remarkable structural difference between connexin proteins is the length of the C-terminal cytoplasmic tail, Cx26 having almost no tail, while Cx43 and connexin32 (Cx32) have long and intermediate ones, respectively. When Cx32 and Cx43 lose their C-terminal tails, they seem to resemble Cx26 in structure. To examine whether such truncated connexins become tumor suppressive in HeLa cells, we introduced a stop codon into each of the Cx32 and Cx43 cDNAs to remove their C-terminal tails and transfected these constructs (DeltaCx) into HeLa cells. Both DeltaCx cDNAs induced GJIC as efficiently as the wild-type counterparts. Although none of the truncated connexins affected proliferation rate, the truncated Cx32 and Cx43 proteins suppressed anchorage-independent cell growth in soft agar. Furthermore, when the transfectants were injected into the backs of nude mice, tumor appearance was delayed by 7 days in animals given cells expressing truncated connexins, i.e. tumors became detectable on days 11 and 18 after injection of vector and DeltaCx transfectants, respectively. Although throughout these experiments the truncated connexins did not completely eliminate the tumorigenicity of HeLa cells, as Cx26 did, it was evident that deletion of the C-terminal tails gave both Cx32 and Cx43 a capacity for negative growth control, suggesting that the C-terminal tails of these two connexins function as a regulatory region for connexin-mediated growth control in HeLa cells.     

The risk of second malignancy after adjuvant chemotherapy for stomach cancer

Background. Although many trials have been conducted to evaluate the feasibility and effectiveness of adjuvant chemotherapy (ACT) for patients with stomach cancer, the benefits of ACT remain unclear. Moreover, some authors have reported that ACT increased the incidence of second malignancy. The risk of second malignancy was evaluated in patients who underwent treatment for stomach cancer in the past 20 years at Osaka Medical Center for Cancer and Cardiovascular Diseases. Methods. The study population consisted of 1925 patients who underwent gastrectomies for stomach cancer between the years 1978 and 1992 and who received follow-up examinations to check for second malignancies. They included 1114 patients who underwent surgery only (group A) and 811 who underwent surgery and received chemotherapy (group B). The observed incidence of second malignancy (O) was compared with the expected incidence (E), calculated by the person-year method, using data from the Cancer Registry in Osaka. Results. The average follow-up period was 7.99 years. The total number of patients with a second malignancy was 127 (men, 97; women, 30); 72 patients had the second malignancy in digestive organs; 27 in respiratory organs; and 28 in other organs. The relative risks of a second malignancy in group A and B patients were 1.05 and 1.02 (differences between the two groups were not significant). The relative risks of a second malignancy in patients who received ACT with 5-fluorouracil, Tegafur and Uracil, and FT207 were 0.79, 1.01, and 1.06, respectively (differences between the groups were not significant). Conclusion. The risk of second malignancy after chemotherapy for stomach cancer was not high in comparison with the expected incidence. Adjuvant chemotherapy did not increase the risk of a second malignancy. Received on April 16, 1999; accepted on Dec. 1, 1999     

Establishment of an in vivo Highly Metastatic Rat Hepatocellular Carcinoma Model

We previously found by chance that N-nitrosomorpholine (NMOR) given after a multi-carcinogenic treatment induces liver carcinomas with 56% lung metastasis, and it was confirmed that hepatocellular carcinoma (HCC) with 100% lung metastasis was produced by 24-week treatment with NMOR and additional treatment with diethylnitrosamine (DEN). In the present study, we modified the duration of NMOR to establish an animal model with a simple experimental protocol and an appropriate experimental duration which would facilitate further study of the mechanisms of metastasis and antimetastatic agents. The results revealed DEN exposure followed by a 16-week treatment with NMOR to be a most efficient method for the induction of HCC metastasizing to the lung. Loss of cadherin, demonstrated immunohistochemically, occurred in an early stage of carcinogenesis, and this was reflected in malignant conversion of primary lesions. This model, with its essential similarities to malignant tumor behavior in man, should find application not only for elucidation of the mechanisms underlying metastasis, but also in the development of anti-metastatic agents.     

Characterization of cytochrome P450 enzymes involved in drug oxidations in mouse intestinal microsomes

1. Cytochrome P450 (P450, CYP) enzymes involved in drug oxidations in mouse intestines were characterized for their role in the first-pass metabolism of xenobiotics. 2. Preparation of mouse intestinal microsomes using a buffer containing glycerol and protease inhibitors including (p-amidinophenyl) methanesulphonyl fluoride, EDTA, soybean trypsin inhibitor, aprotinin, bestatin and leupeptine gave the highest testosterone 6beta-hydroxylase activity among several preparation buffers tested in this study. Testosterone 6beta-hydroxylase activity catalysed by mouse intestinal microsomes subjected to freezing and thawing was lower than that catalysed by unfrozen intestinal microsomes. 3. Low but significant catalytic activities of nifedipine oxidation, midazolam 1'- and 4-hydroxylation, chlorzoxazone 6-hydroxylation, bufuralol 1'- and 6-hydroxylations and tolbutamide methylhydroxylation were observed in mouse intestinal microsomes. Testosterone 6beta-hydroxylation, chlorzoxazone 6-hydroxylation, and bufuralol 1'- and 6-hydroxylations were inhibited by ketoconazole, diethyldithiocarbamate and quinine respectively. 4. Immunoblot analysis using anti-rat CYP3A antibodies demonstrated two immunoreactive bands showing similar migration in mouse intestinal and hepatic microsomes, although studies using anti-CYP1A, anti-CYP2C, anti-CYP2D and anti-CYP2E1 antibodies did not detect any band in mouse intestinal microsomes. 5. The results suggest that mouse intestinal microsomes should be prepared with glycerol and several protease inhibitors and that Cyp3a enzymes probably play an important role in drug oxidations catalysed by mouse intestine.     

A case of bronchial squamous cell carcinoma in situ detected by sputum cytology

A 64-year-old man underwent a medical checkup in May 1996 and was evaluated as class V using sputum cytology. Chest X-ray examination, bronchoscopy and chest computed tomography (CT) demonstrated no abnormalities. Thereafter, the patient was followed up with chest X-ray, bronchoscopy and chest CT at 3-month intervals. In December 1996, chest CT showed an increased density at the mediastinal side of the left upper bronchus, B1+2. There were no findings on bronchoscopy, but subsequent exfoliative cytology demonstrated keratinized malignant cells in samples obtained from left upper bronchus, B1+2. Although, it was difficult to identify localization of the tumor, left upper lobectomy was performed and the diagnosis of squamous cell carcinoma in situ was finally made. Here, we report on the course of this patient and discuss the diagnostic usefulness of sputum cytology as well as the pathogenesis of lung squamous cell carcinoma.