Cloning and characterization of the CYP2D1-binding protein, retinol dehydrogenase

A CYP2D1-binding protein, 29 k-protein (p29), has been isolated and its N-terminal amino acid sequence has been reported (Ohishi et al. (1993) Biochim. Biophys. Acta 1158, 227-236). In this study, p29 cDNA was isolated by PCR with oligonucleotide probes designed from the N-terminal amino acid sequence and p29 was found to be a microsomal retinol dehydrogenase, a member of the short-chain alcohol dehydrogenase family which metabolize hydroxysteroids and prostaglandins. CYP2D1 and p29 were expressed in Saccharomyces cerevisiae to characterize these proteins. CYP2D1 had an absorption maximum at 448 nm in a CO-reduced form. Expressed p29 in yeast cells was detected with anti-p29 antibody. Solubilized CYP2D1 and p29 from yeast microsomes were mixed and applied to an anti-CYP2D1 antibody-binding column. Both proteins were retained in the column and eluted with glycine buffer (pH 2.8). However, when applied alone, p29 was not retained in the column. The findings indicated that CYP2D1 bound tightly with p29. Catalytic activities of p29 expressed in yeast were investigated. p29 had retinal reductase activity in the presence of NADPH. Addition of CYP2D1 and NADPH-P450 reductase increased the retinal reductase activity of p29. These findings suggest that the complex of CYP2D1, p29, and NADPH-P450 reductase has an important role in the metabolism of retinoids.

Tissue distributions of CYP2D1, 2D2, 2D3 and 2D4 mRNA in rats detected by RT-PCR

The tissue distributions of four isoforms (CYP2D1/5, 2D2, 2D3 and 2D4/18) in rat CYP2D subfamily were investigated. Twelve kinds of tissue (liver, kidney, brain, lung, heart, spleen, adrenal gland, small intestine mucosa, bladder, testis, ovary and gonecystis) were removed from Sprague-Dawley male and female rats. The expression of CYP2D mRNA in these tissues was detected by RT-PCR. Specific primers were designed to recognize the four isoforms individually. In liver, kidney and small intestine mucosa, the mRNA expression of all four CYP2D isoforms was detected as high-intensity PCR products. mRNA of CYP2D1/5 was expressed in all tissues used in this study except the brain, although the intensity of PCR products varied among tissues. mRNAs of CYP2D2 and CYP2D3 were mainly expressed in liver, kidney and small intestine mucosa, which were exposed to xenobiotics such as drugs, food components and environmental contaminations. mRNA of CYP2D4/18 was expressed in liver, kidney, small intestine mucosa and brain. In brain, only mRNA of CYP2D4/18 was expressed. CYP2D4/18 mRNA was also expressed in ovary, testis and gonecystis. The tissue distributions help to clarify the differences in physiological and pharmacological functions between CYP2D isoforms.

Adjuvant therapies in extended pancreatectomy for ductal adenocarcinoma of the pancreas

BACKGROUND/AIMS

The poor prognosis after pancreatic cancer resection is attributed to a high incidence of locoregional recurrence and hepatic metastasis. The present study was carried out in order to determine whether adjuvant therapies improve patient survival.

METHODOLOGY

Preoperative irradiation and postoperative liver perfusion chemotherapy have been added to the extended pancreatectomy procedure, and a retrospective analysis of 111 patients was performed.

RESULTS

Preoperative irradiation (n = 17) significantly decreased the incidence of locoregional recurrence but increased the incidence of hepatic metastasis, with no improvement in the 5-year survival rate (from 27% to 23%). In contrast, postoperative liver perfusion chemotherapy (n = 27) succeeded in improving the 5-year survival rate to 39% by significantly decreasing the incidence of hepatic metastasis.

CONCLUSION

These data suggest that the patients' survival rate may be increased when these two types of adjuvant therapy are combined with extended pancreatectomy.

Strain differences in CYP3A-mediated C-8 hydroxylation (1,3,7-trimethyluric acid formation) of caffeine in Wistar and Dark Agouti rats. Rapid metabolism of caffeine in debrisoquine poor metabolizer model rats

We observed significant strain differences [Dark Agouti (DA) > Wistar] in 1,3,7-trimethyluric acid formation (C-8 hydroxylation) during caffeine metabolism, though not in N-demethylations, in adult male DA and Wistar rats. In contrast, adult female and immature male rats of both DA and Wistar strains did not show significant differences in activity levels of C-8 hydroxylation. Kinetic studies using liver microsomes revealed that adult male DA rats have a larger Vmax for C-8 hydroxylation than do Wistar rats. Troleandomycin (TAO), known as a cytochrome P450 (CYP) 3A inhibitor, and an anti-rat CYP3A2 polyclonal antibody effectively reduced C-8 hydroxylation by rat liver microsomes in a concentration-dependent manner, suggesting that C-8 hydroxylation in rats is mediated largely by an isoform(s) of the CYP3A subfamily. Troleandomycin and the antibody did not inhibit the N-demethylations of caffeine by rat liver microsomes. Treatment of rats with CYP3A inducers caused a marked increase in C-8 hydroxylase activity. These results indicate that the rat CYP3A subfamily is capable of catalyzing C-8 hydroxylation of caffeine as is the case for human CYP3A4. The results of western blotting analysis using anti CYP3A antiserum showed that the staining intensity of the protein band in DA rat liver microsomes was higher than that in Wistar rat liver microsomes. We concluded that marked sex-dependent strain differences in C-8 hydroxylation of caffeine between Wistar and DA rats are due to the differences in the levels of expression of CYP3A in these strains of rats.

[Pre- and/or postoperative adjuvant therapy for hepatocellular carcinoma]

Pre- and/or postoperative adjuvant therapy for hepatocellular carcinoma (HCC) is discussed. There is a high recurrence rate of HCC of up to 50% or more within three years after hepatectomy. More than 80% of those recurrences are in the form of intrahepatic metastases. Therefore it is extremely important to administer successful adjuvant therapy to prevent intrahepatic recurrence. There are two types of intrahepatic recurrence: simple dissemination from the primary focus of HCC; and newly developed HCC in the remnant liver. TAE is one option for preoperative adjuvant therapy to prevent intrahepatic recurrence. Postoperative adjuvant chemotherapy via the hepatic artery has occasionally been administered, but it is not yet established as an effective adjuvant therapy. However, a report by Muto et al showed that retinoid administration can prevent intrahepatic recurrence of newly developed HCC after hepatectomy. On the other hand, adjuvant therapy must not be tooaggressive, because: 1) HCC develops mainly in cirrhotic liver (with poor liver function); and 2) locoregional therapy for intrahepatic recurrence results in good survival rats even after detection of an established recurrence.

Down-regulation of focal adhesion kinase, pp125FAK, in endothelial cell retraction during tumor cell invasion

Although endothelial cell retraction is required before tumor cell invasion, its molecular mechanism still remains obscure. We previously demonstrated that conditioned medium (CM) derived from a human pancreatic cancer cell line, PSN-1, induced endothelial cell retraction and facilitated tumor cell invasion. To investigate the molecular change of events in the transduction of extracellular signals during endothelial cell retraction, we examined the effect of the CM derived from PSN-1 cells on the tyrosine phosphorylation in endothelial cells. Immunoblot analyses revealed that the PSN-1 CM decreased tyrosine phosphorylation of a 120-130 kD protein, and induced the concomitant down-regulation of focal adhesion kinase, pp125FAK, during endothelial cell retraction in time- and dose-dependent fashions. These changes preceded endothelial cell retraction and were reversible after removal of the CM. Further quantitative densitometric analyses demonstrated that the extent of decrease in tyrosine phosphorylated 120-130 kD protein during the endothelial cell retraction was likely to be proportional to that of the down-regulation of pp125FAK. A tyrosine phosphorylated 120-130 kD protein immunoprecipitated by anti-phosphotyrosine antibody immunoreacted with anti-pp125FAK antibody. These results suggested that decreased amount of a tyrosine phosphorylated 120-130 kD protein probably due to the down-regulation of pp125FAK might be associated with the signal transduction pathway in the endothelial cells during their retraction. Furthermore, these findings were also observed in the CM from another four human cancer cell lines, suggesting the down-regulation of pp125FAK in endothelial cells during tumor cell invasion.

Activation of the beta-catenin gene by interstitial deletions involving exon 3 in primary colorectal carcinomas without adenomatous polyposis coli mutations

Among 222 primary colorectal cancers we examined, 58 showed no detectable APC mutations by the protein truncation test. We screened those 58 tumors for somatic mutations in the beta-catenin gene. Although amino acid substitutions in serine or threonine residues in exon 3 had been reported, we found no such mutations; however, in seven tumors, we detected somatic interstitial deletions of 234-760 bp, each of which included all or part of exon 3. Short nucleotide sequences at both ends of each deletion were either identical or complementary, indicating that repeated or inversely repeated sequences were involved in the somatic rearrangements. Reverse transcription-PCR experiments using RNAs isolated from three of these seven tumors detected transcripts that lacked exon 3, in addition to the normal transcript. In one of these cases, we confirmed accumulation of aberrant beta-catenin protein in cytoplasm and nuclei of cancer cells by Western and immunohistochemical analyses. This result suggested that, in the absence of a peptide encoded by exon 3, beta-catenin is stabilized and has a dominant oncogenic effect on colorectal tumorigenesis.

[Our initial experience with SMANCS in TAE for liver cancer]

To evaluate the efficacy and adverse reaction of SMANCS, we reviewed 10 cases treated by TAE with SMANCS among 896 cases treated by TAE for liver cancer during the past three years at our institute. Our criteria for using SMANCS were as follows: a) reduced effectiveness of past TAE with Lipiodol, hydrophilic drugs and gelatin sponge; b) sufficient caliber and blood flow in the hepatic artery; and c) good hepatic function. The 1- and 2-year survival rates after treatment with SMANCS were 50% and 25%, respectively. The 3- and 5-year survival rates after initial treatment (first TAE, etc.) were 40% and 20%, respectively. There were no significant complications in clinical course, however, subsequent hepatic arteriogram often showed arterial change that may interfere with further regional therapy for the liver.

A comparison of hepatic cytochrome P450 protein expression between infancy and postinfancy

We immunochemically measured the contents of 9 different cytochrome P450 (CYP) isoenzymes expressed in the liver and compared them between two groups: one group of 6 infant and 4 perinatal patients and one group of 10 patients after infancy (over 1 year old). CYP protein expressed in human liver can be divided into three groups on the basis of expression pattern: (a) CYP2A6, 2C9, 2D6, 2E1, and 3A were present in all samples and no difference was observed between the two groups; (b) CYP1A2, 2B6, and 2C8 were expressed more after infancy than during infancy; and (c) CYP3A7, which has been considered a major CYP enzyme in fetal liver microsomes, was expressed in all infants as well as the four perinatal patients, whereas it was detected in only 2 patients after infancy. These results implied that CYP2A6, 2C9, 2D6, 2E1, and 3A are already expressed during perinatal and infant period, while CYP1A2, 2B6, and 2C8 are expressed highly in subjects over 1 year old, and CYP3A7 disappeared after infancy.

Evidence that immature rat liver is capable of participating in steroidogenesis by expressing 17alpha-hydroxylase/17,20-lyase P450c17

Steroid hydroxylase cytochrome P450c17 has been previously purified from microsomal fractions of immature rat livers. In this study, we investigated the expression of P450c17 in rat livers to understand a role of steroidogenesis in the extrasteroidogenic tissue. Upon immunoblot analysis utilizing liver microsomes from rats, P450c17 was detected in 1 and 3 week old rats but not in adult rats. Data from immunohistochemical studies also showed a similar age-dependent expression of P450c17 and indicated that P450c17 detected in immature rat livers is localized in cells surrounding interlobular veins. This age-dependent expression of P450c17 in rat livers was observed in both sexes. Upon enzymatic analysis utilizing microsomal fractions from livers, levels of 17alpha-hydroxylase and 17,20-lyase activity for pregnenolone and progesterone increased by 3 weeks and dramatically reduced at 7 weeks, which is consistent with the expression level of P450c17. These data clearly indicate that P450c17 is expressed in immature rat liver to produce 17alpha-hydroxysteroids and C19-steroids. Based upon immunoblot analysis, the expression level of P450c17 in immature rat livers was approximately one third of that in testis. Compared expression level of P450c17 and total volume of organs between liver and testis, the total amount of steroid metabolites produced by liver P450c17 could be greater than that produced by gonadal P450c17. Because of the absence of P450c17 in rat adrenal glands, rat liver could be the major site for producing 17alpha-hydroxysteroids and C19-steroids in this particular period of life. Although physiological products formed by P450c17 in liver and their roles remain to be elucidated, this study suggests a large capacity of prepubertal rat liver for participating the production of steroid hormones and a putative importance of 17alpha-hydroxysteroids and C19-steroids, such as cortisol and androstendione, which are generally believed to be minor components of steroid hormones in rodents.

cis-Diamminedichloroplatinum induces peroxisomes as well as CYP4A1 in rat kidney

Effects of cis-diamminedichloroplatinum (cisplatin) on rat kidney were investigated. Clinical parameters in rat urine and blood were studied. Blood urea nitrogen (BUN) and creatinine in blood and K+ in urine increased, but Na+ in urine decreased. Contents of total P450 and metabolic activities towards lauric acid and arachidonic acid in rat renal microsomes were not changed by cisplatin treatment. The levels of P450 isozymes (CYP4A1, 4A2, 4A8 and 2C23) were determined in rat renal microsomes by immunoblotting. The levels of CYP4A2 and 4A8 which are lauric acid omega-hydroxylases were not changed, but the levels of CYP2C23 and 4A1 were increased significantly by cisplatin treatment. Effects of clofibrate, a typical inducer for CYP4A1, on rat kidney were compared with those of cisplatin. Clofibrate induced palmitoyl CoA oxidase (a marker enzyme of peroxysome), CYP4A1, and CYP4A2 and reduced triglyceride level in plasma. Cisplatin had similar effects to clofibrate and induced peroxysomes as well as CYP4A1, although the effects were at a lesser extent than those of clofibrate. The induction levels of CYP4A1 correlated with increased levels of BUN. The present findings suggest that induction of P450 by cisplatin may take part in the renal injury or nephrotoxicity of cisplatin.

Expression of four rat CYP2D isoforms in Saccharomyces cerevisiae and their catalytic specificity

We cloned four cDNAs belonging to the CYP2D subfamily to express these enzymes in yeast cells and to compare their catalytic activities simultaneously. Three are believed to be alleles of CYP2D1, 2D2, and 2D3, respectively, based on high nucleotide sequence similarity, while CYP2D4 had both sequences of CYP2D4 and CYP2D18. Expression plasmids carrying CYP2D cDNAs were transformed into Saccharomyces cerevisiae. Typical P450 CO-difference spectra with absorbance maximum at 448 nm were recorded with microsomal preparations from the yeast cells expressing the four CYP2D forms. A catalytic study of these CYP2D forms was done with debrisoquine, bufuralol, and lidocaine. CYP2D2 had the highest debrisoquine 4-hydroxylation (2.2 nmol/min/nmol P450) activity, similar to that (2.2 nmol/min/nmol) of human CYP2D6 expressed in yeast cells. CYP2D3 had high lidocaine N-deethylation (43 nmol/min/nmol P450) activity, and both CYP2D3 and 2D2 exhibited high lidocaine 3-hydroxylation (2.4 and 1.6 nmol/min/nmol P450, respectively) activity. Bufuralol 1'-hydroxylation catalytic capabilities were comparable among the four isoforms. The activity of CYP2D1 was relatively low toward the three substrates (debrisoquine, 0.091; bufuralol, 1.5; lidocaine 3-hydroxylation, 0.019; lidocaine N-deethylation, 2.8 nmol/min/nmol P450). These findings indicate that debrisoquine, a typical substrate for CYP2D forms, was mainly metabolized by CYP2D2 but not CYP2D1 in rat liver and that the CYP2D forms have different substrate specificity.

Irreversible inhibition of cytochrome P450 by nitric oxide

Nitric oxide (NO) modulates various metabolisms through interaction with thiol proteins and hemoproteins. Although NO interacts reversibly with iron moieties of heme proteins, including cytochrome P450 (P450), dynamic aspects of the formation, catalytic functions and fates of NO-P450 adducts remain to be elucidated. When incubated with NOC7, which spontaneously and stoichiometrically releases NO within 5 min, microsomal P450 rapidly formed nitrosyl-heme adducts as determined by the electron spin resonance method. The signal intensity for the complex increased with time, peaking at 30 min and decreasing to below detectable levels by 60 min of incubation. In contrast, the microsomal levels of low-spin ferric forms of P450 (g = 2.26) rapidly decreased during the initial 30 min but recovered time-dependently thereafter. Analysis by differential spectra (reduced form/CO-reduced form) revealed that on incubation with NOC7, the form of microsomal P450 also changed in a biphasic manner. To elucidate the mechanism for the decrease in the levels of P450, microsomal levels of P450 isozymes (CYPs) were determined by Western blot analysis using specific antibodies against CYP3A2 and CYP2C11, major isoforms found in male rat liver. Kinetic analysis revealed that no appreciable degradation of P450 proteins occurred during the incubation of microsomes with NOC7. The effect of NO on the catalytic activity of the enzymes was determined by using testosterone as substrate because hydroxylation of steroid hormones is one of the major functions of P450. When exposed to NO, the hydroxylation activity in microsomes rapidly decreased during the initial 10 min and then disappeared slowly. These results suggested that NO formed dissociable complexes with P450 isozymes and the catalytic functions of these isozymes were irreversibly inactivated after dissociation from their heme moiety.

Regional chemotherapy to prevent hepatic metastasis after resection of pancreatic cancer

BACKGROUND/AIMS

Liver metastasis is one of the major causes of cancer death after resection of pancreatic cancer. To deal with this problem, we developed a liver perfusion chemotherapy via the hepatic artery and portal vein. The present paper is designed to introduce the technique of this method and report on the promising results.

METHODOLOGY

Between 1987 and 1995, 98 consecutive patients with adenocarcinoma of the pancreas received an extended pancreatectomy, in which a wide range of lymphatic and connective tissue clearance was performed in addition to the conventional pancreatectomy, at Osaka Medical Center for Cancer and Cardiovascular Diseases. All patients were followed-up to determine whether and where cancer recurrence developed.

RESULTS

Excluding 4 patients who died of postoperative complications, our liver perfusion chemotherapy was performed on 27 patients. The other 67 patients did not receive this treatment. In the group that underwent liver perfusion chemotherapy, no patients experienced complications such as leucocytopenia (< 3000/mm3), thrombocytopenia (< 50,000/mm3), or liver disfunction. The cumulative survival rate differed remarkably between the two groups: 92% vs 62% at one year (p < 0.05); 51% vs 35% at three years (p < 0.05); and 41% vs 25% at five years (ns).

CONCLUSIONS

When this method was performed after an extended pancreatectomy for adenocarcinoma of the pancreas, our preliminary report (Am J Surg. 1994; 168:361-364) indicated that it was useful not only for preventing hepatic metastasis, but also for improving patients' survival rate. Since then, further positive and supportive results have been obtained in an additional investigation.

Genetic detection of colorectal cancer cells in circulation and lymph nodes

PURPOSE

This study was undertaken to investigate the clinical implications of detection of genetic alterations in blood and lymph nodes in colorectal cancer patients.

METHODS

The reverse transcriptase polymerase chain reaction product of the cytokeratin gene in blood was examined as a cancer cell-specific expression in 35 colorectal cancer patients. The K-ras or p53 gene mutations in the lymph nodes histopathologically negative for metastasis were studied by the mutant-allele-specific amplification method in 26 colorectal cancer patients.

RESULTS

The reverse transcriptase polymerase chain reaction assay was able to detect a cytokeratin reverse transcriptase polymerase chain reaction product at a concentration from a single to ten colon cancer cells per 10(6) normal peripheral blood mononuclear cells. Cytokeratin reverse transcriptase polymerase chain reaction products were detected in nine patients' blood samples, although none of the samples were cytologically detectable. The blood's cytokeratin positivity correlated with the invasive mode of the tumor (P < 0.05) and the presence of distant metastasis (P < 0.01). Two (50 percent) of four patients whose blood was positive for cytokeratin had recurrences. Of 17 patients with the K-ras or p53 gene mutation in primary tumors, 9 (53 percent) had the corresponding mutations in lymph nodes. Mutation positivity in lymph nodes correlated with the presence of lymphatic invasion of the primary tumor (P < 0.05). All patients with mutation-negative lymph nodes remained disease-free for more than two years after surgery.

CONCLUSION

Detection of cytokeratin reverse transcriptase polymerase chain reaction products in the blood and K-ras or p53 gene mutations in the lymph nodes histologically negative for metastasis may be applicable for clinical use, despite some limitations, and may serve as a useful clinical factor for stratifying patients who are at high or low risk for recurrence after surgery.

Association of cumulative allelic losses with tumor aggressiveness in hepatocellular carcinoma

BACKGROUND/AIMS

Loss of heterozygosity on various chromosomal arms has been reported in hepatocellular carcinoma and a multistep accumulation of genetic alteration has become accepted as the mechanism underlying progression of the disease. Although cumulative genetic alterations may imply more malignant tumors with poorer prognosis, the assumption requires further investigation.

METHODS

Presence of loss of heterozygosity was analyzed by microsatellite markers at 13 loci on six chromosomal arms in 56 hepatocellular carcinomas. Association with cumulative allelic losses and prognosis of the patient following curative resection was studied.

RESULTS

Frequency of allelic losses at each chromosomal arm was 31% on 1p, 20.6% on 4q, 17.5% on 8p, 17.5% on 13q, 25.5% on 16q and 17.4% on 17p. Thirty-three tumors (59%) presented loss of heterozygosity. Tumors with more allelic losses were significantly more likely to be un-infected by hepatitis C virus, and to be histologically poorly differentiated, to have higher alpha-feto protein value, to be advanced in T classification and in tumor stage. Patients with more than one loss of heterozygosity revealed poorer 3-year disease-free survival than those with one or no (p=0.0004). A multivariate Cox model analysis revealed cumulative loss of heterozygosity as an independent and influential factor for disease recurrence (relative risk, 2.66; 95% confidence interval, 1.23-5.75; p=0.013), followed by tumor stage.

CONCLUSIONS

Cumulative loss of heterozygosity reflects the multistep genetic mechanism of progression of hepatocellular carcinoma. The study confirms the potential significance of genetic analysis in the management of the disease.

Isolation, mapping and mutation analysis of a human cDNA homologous to the doc-1 gene of the Chinese hamster, a candidate tumor suppressor for oral cancer

We have isolated a human cDNA encoding a 115-amino-acid polypeptide that revealed 97% identity to a candidate tumor suppressor gene for oral cancer in Mesocricetus auratus (deleted in oral cancer-1; doc-1). It also showed a high degree of homology to a gene induced by TNF-alpha in Mus musculus. To investigate its possible role in esophageal carcinogenesis, we examined genetic alterations and expression levels of the gene in 13 esophageal carcinoma cell lines and 10 primary esophageal carcinomas. No mutation nor reduction of expression was observed in any of the 23 cancer materials examined. These results imply that the human doc-1 homologue is unlikely to play a significant role in esophageal carcinogenesis, although its role in the TNF-alpha signaling pathway remains unclear. We mapped DOC1 to chromosome band 12q24.31 by fluorescence in situ hybridization.

Mutagenic activation of urinary bladder carcinogens by CYP4B1 and the presence of CYP4B1 in bladder mucosa

We investigated the mutagenic activation of 2-naphthylamine (2-NA), 3,2'-dimethyl-4-aminobiphenyl (DMAB), and 3,3'-dichlorobenzidine (DCB), bladder carcinogens, by renal and bladder microsomes and by purified P450s using the umu gene expression system, which detects DNA damage. Mouse renal microsomes had high mutagenic activation toward DCB and low activity toward 2-NA. Purified mouse Cyp4b1 also had high mutagenic activity toward DCB. Anti-Cyp4b1 antibody efficiently inhibited DCB bioactivation by mouse renal microsomes with a high Cyp4b1 content. Lauric acid, a substrate of Cyp4b1, efficiently inhibited DCB bioactivation by renal and bladder microsomes of the mouse and by purified Cyp4b1. To assess the contribution of CYP4B1 to bladder carcinoma, further investigation was done with the umu test and an immunochemical study. Ten forms of purified rat P450s including rat CYP4B1 were used in the umu test for 2-NA, DMAB, and DCB. CYP4B1 had the highest activity toward DMAB and DCB. Other P450s had activities of less than 20% that of CYP4B1. CYP4B1 also activated 2-NA, but its activity was about 10% of that toward DMAB or DCB. Rat bladder epithelium was stained specifically with anti-Cyp4b1 antibody, indicating the presence of CYP4B1 in the rat bladder mucosa. Also, CYP4B1 mRNA was detected by northern blotting and reverse transcription-polymerase chain reaction (RT-PCR). These findings suggested that CYP4B1 could contribute to the initiation of carcinogenesis in rat and mouse bladder by activation of aromatic amines.

Selective deficiency of debrisoquine 4-hydroxylase activity in mouse liver microsomes

Cytochrome P450 enzymes belonging to the CYP2D subfamily have been shown to be one of determinants of the polymorphic drug oxidations in the human and the rat. Debrisoquine 4-hydroxylation is a typical reaction catalyzed by these enzymes. However, various strains of mice were observed to have much lower debrisoquine 4-hydroxylase activity than Wistar rats, whereas other monooxygenase activities in mice toward bunitrolol, propranolol, imipramine and amitriptyline, which are mediated by the CYP2D enzymes in the rat, were comparable to those of the rats. Immunoblot analysis of mouse liver microsomes with an antibody raised against a rat CYP2D enzyme indicated that the mouse liver contained a P450 enzyme(s) immunochemically related to the rat CYP2D enzyme. The antibody inhibited propranolol ring-hydroxylase and imipramine 2-hydroxylase activities, as well as testosterone 16alpha-hydroxylase activity, a typical reaction of mouse CYP2D9, but not debrisoquine 4-hydroxylase activity in mouse liver microsomes. We partially purified a P450 enzyme (designated P450 ML2d) from livers of male ddY mice by monitoring the cross-reactivity with the antibody. The partially purified enzyme was indicated to belong to the CYP2D subfamily from its N-terminal amino acid sequence, but the homology of the sequence to other CYP2D enzymes of the mouse (CYP2D9-11) was 62%, suggesting that P450 ML2d is a novel P450 enzyme. P450 ML2d had the oxidation activities for the rat CYP2D-substrates, such as propranolol 4-hydroxylation and imipramine 2-hydroxylation, in higher rates than those of the microsomes, but did not exhibit debrisoquine 4-hydroxylase activity. Our result is the first finding that a mouse CYP2D enzyme also metabolizes substrates for the rat CYP2D enzyme, in addition to steroids, but the enzyme had a limited specificity for the substrates of the CYP2D enzymes of the rat and the human.

Isozyme selective alterations of the expression of cytochrome P450 during regeneration of male rat liver following partial hepatectomy

1. During liver regeneration in the male rat, the metabolic activities of imipramine were differentially affected depending on the specific metabolic pathways. Imipramine N-demethylation was markedly reduced whereas 2-hydroxylation showed only a moderate reduction following partial hepatectomy. 2. A slight decline was observed in the hepatic microsomal content of CYP2D apoprotein, whereas a substantial decrease occurred in CYP2C11 content during liver regeneration. Since imipramine 2-hydroxylation and N-demethylation are mediated by CYP2D and 2C11 respectively, metabolic pathway-specific alterations in the activities of imipramine metabolism are explained by the isozyme selective alteration in the levels of CYPs in regenerating liver. 3. No significant effect of regeneration was observed on expression of CYP2B1 and 2E1 apoproteins. CYP3A2 apoprotein, one of the male-specific CYP isoforms, was significantly suppressed in regenerating liver showing a similar pattern of alteration to the levels of CYP2C11. The alteration pattern of the CYP1A1 level was different to the above with a moderate decline at the first day post-operation and a marked rebound thereafter. 4. In the partially hepatectomized male rate, no significant increase in androstenedione 5-alpha reductase activity, an activity predominant in the female rat, was detected. It is concluded that the pattern of alterations of hepatic oxidative metabolism during liver regeneration was not related to the functional feminization of the liver.

[A case report of preoperative intra-arterial infusion chemotherapy for pancreatic head carcinoma]

Intra-arterial infusion chemotherapy was given preoperatively to one patient with pancreatic head adenocarcinoma, in order to prevent local failure after surgery. Under an angiographic procedure, a catheter was placed in the gastroduodenal artery after embolizing the right gastric artery and gastroepiploic artery. Before surgery, 5-fluorouracil (250 mg/day) had been continuously infused for 2 weeks and bolus infusion of methotrexate (25 mg) with 5 micrograms of angiotensin-II had been performed every 3 days. As a results, the maximum diameter of the pancreatic tumor decreased from 3 cm to 2 cm on the CT-Scan. An extended pancreatoduodenectomy with portal vein reconstruction was performed. In histologic study, degenerative tumor cells were shown not only in the primary tumor but also in the extrapancreatic perineural invasion.

[Microwave coagulation therapy under mini thoracotomy for small recurrent hepatocellular carcinoma]

Transcatheter arterial embolization therapies (TAE) for multiple hepatocellular carcinomas (HCCs) were performed repeatedly, but had no effects on one or two of the tumors because of the development of collateral arteries. We report a case of which one of the tumors fed by collaterals showed good anti-cancer effects by microwave coagulation therapy (MCT) under mini-thoracotomy. The 70-year-old, male patient with HCC underwent two hepatic resections and one TAE before this admission. On the arteriogram, one of the tumors existing in S6, which was 2 cm in size, was supplied by the right 10th intercostal artery. We carried out MCT under mini-thoracotomy for the tumor in S6 two weeks after conventional hepatic embolization. First, two MCTs using a long electrode, 3 cm in size, were performed in the central area of the tumor, and eight MCTs by a short electrode, 2 cm in size, were done in the peripheral and surrounding area of the tumor. He was discharged 16 days after the therapy without any serious complications. On CT 3.5 months after therapy, no local recurrence of the tumor was recognized. MCT under mini-thoracotomy is a low-invasive, safe and effective therapeutic method for small HCC fed by collaterals.

[A case of huge liver metastasis from colon cancer successfully treated by hepatic intraarterial infusion of low-dose 5-FU]

A 71-year-old man with unresectable liver metastasis from colon cancer was treated by hepatic intraarterial infusion of low dose 5-FU (250 mg/body/day). The tumor measured 18 cm by ultrasonography and has reduced gradually to five cm during three years. Both serum CEA and CA 19-9 levels were as high as 49.9 ng/ml and 5,500 U/ml respectively, before treatment, but normalized. This case suggested that this hepatic intraarterial infusion of low-dose 5-FU might be effective to treat unresectable liver metastasis, especially with portal tumor thrombosis.

Detection of pancreatic and gastric cancer cells in peripheral and portal blood by amplification of keratin 19 mRNA with reverse transcriptase-polymerase chain reaction

Reverse transcriptase-polymerase chain reaction (RT-PCR) targeted at keratin 19 mRNA was applied to detect circulating cancer cells in the peripheral and portal blood of pancreatic and gastric cancer patients. Keratin 19 mRNA expression was studied by RT-PCR in cancer tissues (12 pancreatic and 15 gastric cancers) and in peripheral and/or portal blood samples from patients with pancreatic cancer (stage I, n = 5; stage II, n = 1; stage III, n = 15; stage IV, n = 19), gastric cancer (stage la,b, n = 28; stage II, n = 9; stage IIIa,b, n = 5; stage IVa,b, n = 7) and benign pancreatic diseases (n = 7). Peripheral blood samples from 50 healthy volunteers served as controls. RT-PCR was conducted in duplicate in each sample, and only samples showing keratin 19 transcript in both determinations were considered as being positive. All the pancreatic and gastric cancers, but none of the control blood samples, were found to be positive. Dilution study using pancreatic cancer cells serially mixed against peripheral blood showed that detection sensitivity was more than one cancer cell in 10(6) peripheral blood mononuclear cells. In pancreatic cancer patients, RT-PCR analysis of the portal blood samples gave positive results in one stage III and one stage IV patient, and that of peripheral blood samples gave positive results in 2 stage IV patients. No positive results were obtained in any of the blood samples from gastric cancer patients. Our results indicate that incidence of circulating cancer cells is unexpectedly very low even in advanced pancreatic and gastric cancer patients.

Detection of pancreatic and gastric cancer cells in peripheral and portal blood by amplification of keratin 19 mRNA with reverse transcriptase-polymerase chain reaction

Reverse transcriptase-polymerase chain reaction (RT-PCR) targeted at keratin 19 mRNA was applied to detect circulating cancer cells in the peripheral and portal blood of pancreatic and gastric cancer patients. Keratin 19 mRNA expression was studied by RT-PCR in cancer tissues (12 pancreatic and 15 gastric cancers) and in peripheral and/or portal blood samples from patients with pancreatic cancer (stage I, n = 5; stage II, n = 1; stage III, n = 15; stage IV, n = 19), gastric cancer (stage la,b, n = 28; stage II, n = 9; stage IIIa,b, n = 5; stage IVa,b, n = 7) and benign pancreatic diseases (n = 7). Peripheral blood samples from 50 healthy volunteers served as controls. RT-PCR was conducted in duplicate in each sample, and only samples showing keratin 19 transcript in both determinations were considered as being positive. All the pancreatic and gastric cancers, but none of the control blood samples, were found to be positive. Dilution study using pancreatic cancer cells serially mixed against peripheral blood showed that detection sensitivity was more than one cancer cell in 10(6) peripheral blood mononuclear cells. In pancreatic cancer patients, RT-PCR analysis of the portal blood samples gave positive results in one stage III and one stage IV patient, and that of peripheral blood samples gave positive results in 2 stage IV patients. No positive results were obtained in any of the blood samples from gastric cancer patients. Our results indicate that incidence of circulating cancer cells is unexpectedly very low even in advanced pancreatic and gastric cancer patients.