A case of intra-peritoneal recurrence of colon carcinoma that responded remarkably to combined therapy of low-dose leucovorin and 5-fluorouracil

We treated a patient with intra-peritoneal recurrent tumor from colon cancer who responded completely to chemotherapy of combined low-dose Leucovorin (LV) and 5-fluorouracil (5-FU). The patient was a 75-year-old man. He underwent resection of the transverse colon, sigmoid colon and distal stomach for colon and gastric cancers. Nine months after the operation, his CEA level increased to 39.5 ng/ml and a CT scan revealed an intra-peritoneal tumor measuring about 5 cm. He received chemotherapy of 30 mg/day of LV that was injected in a bolus and 500 mg/day of 5-FU that was given i.v. by continuous infusion for 10 days. At the end of 2 cycles of this regimen, CT scan demonstrated complete tumor remission and the patient's CEA level decreased to normal level. After an additional cycle of this regimen, he received modulated chemotherapy combined with l-Leucovorin and 5-FU as an outpatient. However, after 3 months of treatment, a recurrent tumor was detected in the same portion and the first regimen was re-started for 5 days. After 4 cycles of treatment the tumor disappeared completely from a CT scan. It is important to investigate effective regimens that do not reduce the quality of life of the patient. This clinical experience suggests that a low-dose LV/5-FU therapy may be beneficial to patients with recurrent colon cancer. Further investigation is necessary to establish an effective regimen that can be given for a long period without adverse effects on quality of life.     

Rare mutations of p53, Ki-ras, and beta-catenin genes and absence of K-sam and c-erbB-2 amplification in N-methyl-N'-nitro-N-nitrosoguanidine-induced rat stomach cancers.

Rat stomach cancers induced by N-methyl-N'-nitro-N-nitrosoguanidine (MNNG) have been widely used as a model for human stomach cancers of the differentiated type. However, there has been little information regarding their molecular basis. In this study, we examined the genetic alterations reported in human stomach cancers in 10 rat stomach cancers that had been induced in male ACI/N rats by administering MNNG in the drinking water. One of the 10 cancers had a mutation of the p53 gene at the second position of codon 171 (Val --> Glu). However, none of the 10 cancers had mutations in codons 12, 13, or 61 of Ki-ras or in the N-terminal phosphorylation sites of the beta-catenin gene. Southern blot analysis showed no amplification of K-sam or c-erbB-2 in the seven cancers examined. Finally, we searched for microsatellite alterations in 12 loci in nine cancers, but no alterations were observed. As these genetic alterations are observed in only a minor fraction of human stomach cancers, further analysis of genetic and epigenetic alterations in MNNG-induced rat stomach cancers is needed to disclose the major mechanisms of stomach carcinogenesis.     

Strong expression of glutathione S-transferase placental form in early preneoplastic lesions and decrease with progression in hamster buccal pouch carcinogenesis

The objective of this work was to investigate the expression of glutathione S-transferase placental form (GST-P) in 9,10-dimethyl-1,2-benzanthracene (DMBA)-induced hamster buccal pouch carcinogenesis. Lesions were classified histopathologically into four categories, simple hyperplasia, papillary and nodular (PN) hyperplasia, papilloma and squamous cell carcinoma (SCC). Respective mean percentage GST-P positive areas were 81.6 +/- 7.3%, 76.1 +/- 7.3%, 25.8 +/- 4.9% and 1.9 +/- 1.2%, with significant (P < 0.001) differences confirmed between each of the lesions. These results indicate that GST-P is a useful positive marker for neoplastic lesions and that a decreased expression occurs with progression so that it may be predictive of future development of malignancy.     

Helicobacter pylori infection enhances glandular stomach carcinogenesis in Mongolian gerbils treated with chemical carcinogens

Helicobacter pylori (Hp) is thought to be a stomach carcinogen from epidemiological findings. To determine the effects of infection with the bacteria on experimental carcinogenesis, a study of the glandular stomach of Mongolian gerbils (MGs) was performed. Male MGs were treated with N-methyl-N'-nitro-N-nitrosoguanidine followed by inoculation with Hp or infected with Hp followed by N-methyl-N'-nitro-N-nitrosoguanidine administration. Animals were killed at week 50, and their excised stomachs underwent microbiological and histopathological examinations. In addition, a serological investigation was performed. The incidences of adenocarcinomas were significantly higher in animals treated with 60 or 300 p.p.m. N-methyl-N'-nitro-N-nitrosoguanidine for 10 weeks followed by Hp inoculation or Hp followed by 20 p.p.m. N-methyl-N'-nitro-N-nitrosoguanidine for 30 weeks than in the respective controls. Moreover, tumour-bearing animals had higher titres of anti-Hp antibodies than tumour-free animals. Of interest was the finding that a dose of 100 p.p.m. N-methyl-N'-nitro-N-nitrosoguanidine given to infected gerbils eradicated the Hp in about half the animals, with a concomitant reduction in the promoting effect. No tumours were found in animals infected with Hp without N-methyl-N'-nitro-N-nitrosoguanidine or non-treated gerbils. Hp infection enhances glandular stomach carcinogenesis in MGs treated with N-methyl-N'-nitro-N-nitrosoguanidine. Animals with high titres of anti-Hp antibodies are at greatest risk of developing neoplasms.     

A new thrombin-like enzyme, flavoviridiobin from the venom of Trimeresurus flavoviridis (habu)

Fibrinopeptide A and B releasing enzyme, flavoviridiobin, was isolated from the venom of Trimeresurus flavoviridis using Q-Sepharose, CM-Cellulose, and Sephadex G-75 column chromatographies. Homogeneity was established by the formation of a single band in polyacrylamide gel electrophoresis, isoelectric focusing, and Ouchterlony immunodiffusion. The enzyme has a molecular weight of 48,000, isoelectric point of 8.1, consists of 237 total amino acid residues, and demonstrates clotting activity. However, no tosyl-L-arginine methyl ester (TAME) hydrolytic and kinin-releasing activities were observed. This clotting enzyme was inhibited by p-amidinophenylmethanesulfonyl fluoride hydrochloride (p-APMSF), benzamidine, and beta-mercaptoethanol, suggesting that serine, acidic amino acids, and disulfide bonds are involved in the expression of the enzyme's clotting activity. This thrombin-like enzyme hydrolyzes B beta-chain of human fibrinogen at first, followed by hydrolysis A alpha-chain. The enzyme was stable over the pH range of 7-10 and was shown to be heat resistant.     

Effects of bile acids on development of pepsinogen-altered pyloric glands in rats

The effects of dietary bile acids on the development of pepsinogenaltered pyloric glands (PAPG) were examined. Male WKY/NCrj rats were given a single dose of 160 mg/kg body wt. of N-methyl-N'-nitro-N-nitrosoguanidine (MNNG) by gastric intubation and fed basal diet containing 0.3% sodium taurocholate (Na-TC), 0.3% sodium cholate (Na-C), 0.3% sodium glycocholate (Na-GC), 0.3% sodium tauroglycocholate, 0.3% sodium deoxycholate, 0.1% chenodeoxycholic acid or 0.5% lithocholic acid for 14 weeks. All rats also received 1 ml of saturated NaCl solution 4 times by i.g. intubation. At the end of week 16, the animals were killed, and the number of PAPG per cm of mucosal length was determined immunohistochemically. Na-TC, Na-C and Na-GC significantly increased the number of PAPG over the control value, suggesting that they may have activity to promote gastric carcinogenesis.     

Patterns of epithelial proliferation revealed by continuous administration of bromodeoxyuridine during urinary bladder carcinogenesis in rats

The patterns of epithelial proliferation in the urinary bladder during carcinogenesis were examined sequentially in rats given drinking water supplemented with 0.05% N-butyl-N-(4-hydroxybutyl)nitrosamine (BBN) for 12 weeks and then water without BBN for 18 weeks. Animals received 120 micrograms of bromodeoxyuridine (BrdU) per hour continuously via an osmotic minipump for 4 days before sacrifice and labeled cells were detected immunohistochemically using monoclonal antibody against BrdU. Two types of BBN-induced epithelial lesions were distinguishable: reversible changes characterized by proliferation of basal cells only, and irreversible changes with high and irregularly distributed incorporation of label throughout the epithelium. Simple hyperplasia, and papillary or nodular hyperplasia consisted of areas of reversible and/or irreversible changes, whereas papilloma and cancer consisted of areas of irreversible changes.     

Influences of diethylnitrosamine on longevity of surrounding hepatocytes and progression of transplanted persistent nodules during phenobarbital promotion of hepatocarcinogenesis

The possibility that phenobarbital (PB) selectively promotes liver nodule development by decreasing survival of surrounding hepatocytes previously exposed to diethylnitrosamine (DENA) was evaluated. Livers of F-344 rats were labelled with [3H-methyl]-thymidine (3H-TdR) during developmental or regenerative growth. Neonatal rats given 3H-TdR between days 3 and 12 were subjected at 12 weeks of age to partial hepatectomy (PH) followed 24 hr later by DENA (10 mg/kg) or saline. Subsequent administration of PB (0.1% in drinking water) for 28 weeks reduced total liver label to 46 +/- 10% (saline group) or 40 +/- 4% (DENA group). Adult male rats initiated with DENA (200 mg/kg) and later labelled with 3H-TdR after PH also lost total liver label during 28 weeks' promotion with PB (0.05% in water) at rates similar to those exhibited by noninitiated rats given PB, and by DENA-treated or control rats not given PB. Large persistent (12 weeks) liver nodules generated by DENA in the Solt-Farber model were transplanted as small fragments into the spleens of syngeneic rats previously given 0, 100 or 200 mg/kg of DENA. Subsequent exposure to PB (0.05% in drinking water for 40 weeks) or Aroclor 1254 (6 X 300 mg/kg per month) promoted nodule and cancer development only in livers of DENA-initiated recipients. Surviving transplanted nodules remained as small microscopic clusters even after 40 weeks of promotion. However, PB increased transplant survival (50% vs. 21% in controls) whereas Aroclor reduced it to 8%. These findings indicate that promotion of liver nodules by PB occurs without enhanced mortality of surrounding hepatocytes previously damaged by DENA. They further suggest that promoters such as PB and PCBs do not directly influence the progression of established persistent nodules.