Role of P-glycoprotein as a secretory mechanism in quinidine absorption from rat small intestine

The intestinal transport of quinidine was characterized in rat small intestine, using the Ussing-type chamber under short-circuited conditions. In the short-circuited condition, quinidine transport was predominantly secretory and the transport rate in jejunum was 3.5 times larger in the secretory direction than that in the absorptive direction. The secretion of quinidine was found to be dependent upon its concentration and to be via a carrier-mediated system in both jejunum and ileum. Although the kinetic characteristic of the carrier-mediated secretion of quinidine was very similar in jejunum and ileum, its contribution was much greater in jejunum because of a higher passive diffusion component in ileum. The secretion of quinidine, well-known as an inhibitor of P-glycoprotein, was inhibited significantly and its absorption was enhanced significantly by several substrates of P-glycoprotein including verapamil, diltiazem, and digitoxin in jejunum. These phenomena were also observed by the addition of 2,4-dinitrophenol. Furthermore, the voltage-clamp studies indicated that the inhibition of quinidine secretion occurred in the transcellular pathway. On the other hand, neither tetraethylammonium nor p-aminohippuric acid affected the transport of quinidine. Quinidine was also recognized to inhibit the secretion and to promote the absorption of substrates of P-glycoprotein, chlorpromazine, and verapamil. These results strongly suggest that quinidine is not only an inhibitor but also a substrate of P-glycoprotein and that the P-glycoprotein-mediated secretory flux acts as a barrier to quinidine absorption in the small intestine, especially jejunum.

Protein-protein interactions between UDP-glucuronosyltransferase isozymes in rat hepatic microsomes

The interactions between UDP-glucuronosyltransferase (UGT) isozymes, UGT1s and UGT2B1, in rat hepatic microsomes were investigated using an immunopurification technique with anti-peptide antibodies and a chemical cross-linking strategy. A 50 kDa protein coimmunopurified with UGT1s was identified as UGT2B1 by amino-terminal sequencing and immunodetection with anti-peptide antibody against UGT2B1. Evidence for direct interaction of UGT2B1 with UGT1s was obtained by the loss of UGT2B1 adsorption to immunoaffinity column in Gunn rat hepatic microsomes, which lack all UGT1 isozymes. When the microsomes were treated with the chemical cross-linking reagent 1,6-bis(maleimido)-hexane, a cross-linked product with an apparent molecular mass of 120-130 kDa was obtained that immunostained with antibodies against UGT1s and UGT2B1, indicating the formation of a heterodimer containing one of the UGT1 isozymes and UGT2B1. The effects of UGT complex formation on the stimulation of glucuronidation of testosterone and uptake of UDP-glucuronic acid (UDP-GlcUA) by UDP-N-acetylglucosamine (UDP-GlcNAc) were examined. Alkaline pH-induced dissociation of the complexes was associated with the loss of UDP-GlcNAc-dependent stimulation of glucuronidation, suggesting that two functional states of UGTs with different kinetic parameters correspond to the monomer and oligomer form of UGTs in the membranes. The UDP-GlcNAc-dependent stimulation of UDP-GlcUA uptake into the microsomal vesicles also was affected by the extent of complex formation. These results suggest that complex formation of the UGT isozymes affects the UDP-GlcNAc-dependent stimulation of glucuronidation via stimulation of UDP-GlcUA uptake.

Degradation of insulin and calcitonin and their protection by various protease inhibitors in rat caecal contents: implications in peptide delivery to the colon

The objective of this study was to examine the metabolism of insulin and calcitonin, and their protection by various protease inhibitors, in the large intestine. Fresh caecal contents were prepared from non-fasted rats and the degradation of insulin and calcitonin was studied in a suspension of rat caecal contents, as a model of the content of the large intestine. Both insulin and calcitonin were metabolized in suspensions of rat caecal contents, but the degradation of calcitonin was much faster than that of insulin. The degradation of insulin was fastest at pH 6.8. Protease inhibitors such as camostat and aprotinin inhibited the degradation of insulin and calcitonin in rat caecal contents, which was consistent with the high chymotrypsin activity of these contents. These findings suggest that care should be taken when administering peptide drugs to the large intestine for colon-specific drug delivery because they can be degraded in rat caecal contents. Protease inhibitors might be useful for increasing the stability of these peptides in the large intestine, thereby improving their large-intestinal absorption to the systemic circulation.

Host distribution and response to antitumor alkylating agents of EMT-6 tumor cells from subcutaneous tumor implants

PURPOSE

Minimal residual tumor or minimal residual metastatic disease is a major clinical problem for detection and treatment. The purpose of the study was to develop a model system to detect the occurrence and response to therapy of minimal residual tumor in distant organs.

METHODS

Animals bearing subcutaneously growing established (day 8) murine EMT-6 mammary carcinoma tumors were treated with single doses of the antitumor alkylating agents, cyclophosphamide, melphalan, cis-diamminedichloroplatinum(II) (CDDP) or thiotepa. Tumors, livers, lungs, brain, spleen, blood and bone marrow were collected from the animals 24 h later and single-cell suspensions of these tissues were plated and cultured under conditions suitable for tumor cell colony growth.

RESULTS

Tumor cell colonies grew from each of the tissues with varying frequency ranging from about 6 x 10(3) tumor cell colonies per 10(6) cells plated from the liver, to about 2 tumor cell colonies per 10(6) cells plated from the brain. There was a wide range of sensitivity, spanning 2- to 3-log of the tumor cells, to the antitumor alkylating agents depending upon the tissue in which the tumor cells were located. Tumor cells in the circulating blood were most sensitive to the antitumor alkylating agents with no colony growth after treatment of the animals with any of the four drugs tested. The primary tumor growing subcutaneously in the upper hindleg of the animals was also relatively sensitive to each of the four antitumor alkylating agents tested. EMT-6 tumor cells in the spleen were very sensitive to cyclophosphamide, moderately sensitive to melphalan, less sensitive to CDDP and least sensitive to thiotepa. EMT-6 tumor cells in the bone marrow were moderately sensitive to cyclophosphamide, melphalan and thiotepa but less sensitive to CDDP. EMT-6 tumor cells in the lungs were relatively sensitive to thiotepa, moderately sensitive to cyclophosphamide and CDDP and least sensitive to melphalan. EMT-6 tumor cells in the liver or brain were least responsive to treatment of the host with any of the four antitumor alkylating agents tested.

CONCLUSIONS

Treatment of the tumor-bearing animals with the antiangiogenic combination, TNP-470/minocycline, markedly increased EMT-6 tumor cell killing by cyclophosphamide in the liver, lungs and bone marrow. These results indicate that location within the host is an important determinant in the response of tumor cells to therapy.

c-erbB-2 expression is predictive for lymphatic spread of clinical gastric carcinoma

BACKGROUND/AIMS

In patients with gastric carcinoma, the prognostic significance of c-erbB-2 oncogene expression was elucidated, but its role in the aggressive behavior of tumors is not clear.

PATIENTS AND METHODS

We asked whether or not cerbB-2 gene expression may have predictability with regard to the metastatic potential in 160 patients with gastric carcinoma using a immunohistochemical staining and a multivariate analysis.

RESULTS

c-erbB-2 immunoreactivity was observed in 11% (17/160) of tumors. Patients with c-erbB-2 product positive tumors had a significant shorter prognosis (p < 0.05), and were characterized by a high incidence of peritoneal dissemination (41%), liver metastasis (18%) and lymph node involvement (94%). In the multivariate logistic analysis revealed that c-erbB-2 expression was a significant risk factor related to lymph node involvement (p < 0.01).

CONCLUSIONS

Our multivariate analysis revealed that c-erbB-2 expression is linked to the metastatic potential in patients with gastric carcinoma.

Interaction of interleukin-11 with cytotoxic therapies in vitro against CEM cells and in vivo against EMT-6 murine mammary carcinoma

Interleukin-11(rhIL-11) is a cytokine that has been shown to enhance the recovery of bone marrow and intestinal crypt cells after cytotoxic insult with radiation or anticancer drugs. The current study examined the effects of rhIL-11 on the response of CEM human lymphoblastic leukemia cells and on the EMT-6 murine mammary carcinoma in vivo to cytotoxic anticancer therapies. Exposure of CEM cells to rhIL-11 for 24 hr did not alter the cytotoxicity of melphalan or radiation, increased the cytotoxicity of CDDP (100 muM) and 4-hydroperoxycyclophosphamide (50 betaM) and decreased the cytotoxicity of 5-fluorouracil and ara-C toward the cells. Treatment of mice bearing the EMT-6 tumor with rhIL-11 twice daily for 4 days prior to and the day of cytotoxic therapy resulted in no significant change in the tumor cell killing or bone marrow CFU-GM killing by melphalan, cyclophosphamide, thiotepa, CDDP, radiation, 5-fluorouracil or ara-C. Administration of rhIL-11 twice per day on days 7-18 to EMT-6 tumor bearing animals receiving high dose chemotherapy (melphalan, thiotepa or cyclophosphamide) as a single dose on day 7 followed by mobilized peripheral blood cells on day 8 and rhG-CSF on days 8-20, tended to prolong the tumor growth delay produced by the drugs. This rhIL-11 treatment also resulted in a more rapid recovery of white blood cells and granulocytes in the animals. Furthermore, animals treated with rhIL-11 had improved survival rates compared with animals receiving all other normal tissue support without rhIL-11.

Recurrences and related characteristics of gastric cancer

We analysed data on 1117 patients with gastric cancer who were treated by curative resection. Attention was focused on invasion and a recurrence of the cancer. Based on a univariate analysis, death following a recurrence and prognosis were related to age of the patients, size of the tumour, tumour location, tumour tissue differentiation, growth pattern, depth of invasion, lymphatic and vascular invasion and lymph node metastasis. In proportion to the growth potential, determined by the level of proliferating cell nuclear antigen (PCNA) labelling, the death related to a recurrence was increased and the prognosis was poorer. Multivariate analysis showed that the three factors of serosal invasion, PCNA labelling index and lymph node dissection were independent prognostic factors. When sites of recurrence were analysed regarding each depth of invasion, haematogenous recurrence, in particular in the liver, occurred even in cases of an early invasion and many types of recurrences, including peritoneal recurrence, were noted in patients with an advanced state of invasion.

Age-related characteristics of gastric carcinoma in young and elderly patients

BACKGROUND

The clinicopathologic features of young and elderly patients with gastric carcinoma have been analyzed.

METHODS

We analyzed the data from 174 patients with gastric carcinoma age 40 years and younger and from 356 patients with gastric carcinoma age 70 years and older who were surgically treated at the Department of Surgery II, Kyushu University, Japan.

RESULTS

The rate of multiple gastric carcinomas was 2.9% (5/174) for the young patients and 13.2% (47/356) for the elderly. In subjects older than 70 years, male patients predominated, tumors were smaller, differentiated lesions more common, vascular involvement more frequent, tumors were less infiltrative, and the rate of liver metastasis was higher. For patients younger than age 40 years, undifferentiated type with infiltrative growth was frequent and the rate of liver metastasis was higher. There were no differences in the positive rate of p53 overexpression and the proliferating activity of the cancer cells determined by PCNA LI, between the young and elderly patients. The survival rate after curative resection was lower for the elderly compared with that for the young patients; hematogenous recurrence was higher in the former.

CONCLUSIONS

The clinicopathological features of gastric carcinoma differed between the young and elderly patients, and these differences should be considered when age-oriented treatment is being designed.

Argyrophilic nucleolar organizer region in endoscopically obtained biopsy tissue: a useful predictor of nodal metastasis and prognosis in carcinoma of the stomach

BACKGROUND

Argyrophilic nucleolar organizer region (AgNOR) staining is a simple and economical technique for investigating proliferative activity. We examined AgNOR measured in biopsy specimens of carcinoma of the stomach in humans.

STUDY DESIGN

Argyrophilic nucleolar organizer region staining was done on 76 biopsy specimens and corresponding resected cancer tissues. All estimations were made at the invasive tumor margin.

RESULTS

Of the 76 cases, intratumoral heterogeneity of AgNOR count (more than 1.0 difference) between superficial and deep layers was recognized in six (7.9 percent) cases, all of which were advanced. In biopsy specimens, the AgNOR count ranged from 1.68 to 7.74 (mean, 3.79). A significant correlation was found between AgNOR counts of biopsied materials and those of resected specimens, both in early and advanced cases. Tumors with a high AgNOR count (greater than or equal to 3.79) were more likely to be of a larger size (p < 0.01), to have metastasized to lymph nodes (p < 0.01), and to be associated with a lower survival rate (p < 0.05) compared to tumors with low AgNOR counts.

CONCLUSIONS

Estimating the AgNOR count in endoscopically biopsied specimens at the margin of invasive gastric carcinoma is useful for assessing nodal metastasis and clinical prognosis. These preoperative estimates may aid in tailoring the operative procedure and administrating adjuvant therapy.

Age-related characteristics of gastric carcinoma in young and elderly patients

BACKGROUND

The clinicopathologic features of young and elderly patients with gastric carcinoma have been analyzed.

METHODS

We analyzed the data from 174 patients with gastric carcinoma age 40 years and younger and from 356 patients with gastric carcinoma age 70 years and older who were surgically treated at the Department of Surgery II, Kyushu University, Japan.

RESULTS

The rate of multiple gastric carcinomas was 2.9% (5/174) for the young patients and 13.2% (47/356) for the elderly. In subjects older than 70 years, male patients predominated, tumors were smaller, differentiated lesions more common, vascular involvement more frequent, tumors were less infiltrative, and the rate of liver metastasis was higher. For patients younger than age 40 years, undifferentiated type with infiltrative growth was frequent and the rate of liver metastasis was higher. There were no differences in the positive rate of p53 overexpression and the proliferating activity of the cancer cells determined by PCNA LI, between the young and elderly patients. The survival rate after curative resection was lower for the elderly compared with that for the young patients; hematogenous recurrence was higher in the former.

CONCLUSIONS

The clinicopathological features of gastric carcinoma differed between the young and elderly patients, and these differences should be considered when age-oriented treatment is being designed.

Effect of DNA conformation on cisplatin adduct formation

The anticancer drug cis-diamminedichloroplatinum(II) (cisplatin) has been shown previously to form adducts preferentially within internucleosomal or linker DNA rather than to DNA within the nucleosome. To determine whether other "open" regions of chromatin have an increased affinity for cisplatin, adduct formation within specific chromatin domains was analyzed. There was a significant increase in cisplatin-DNA adduct formation for DNA associated with the nuclear matrix (NM) compared with other chromatin domains and total unfractionated DNA. In contrast, treatment of the same cells with trans-diamminedichloroplatinum(II) (transplatin) did not result in preferential adduct formation. These findings led to the hypothesis that it might be possible to alter DNA to make it a more favorable target for cisplatin. The effect of arginine butyrate on cisplatin-DNA adduct formation was analyzed in human cancer cells. The combination of arginine butyrate and cisplatin resulted in a concentration-responsive increase in cisplatin-DNA adduct formation in PC-3 cells and an overall increase in cisplatin-DNA adduct formation in three other human cancer cell lines. The same combination also resulted in a significant increase in drug-induced cytotoxicity at a low concentration of cisplatin. These results suggest that chromatin configuration can affect cisplatin adduct formation.

Xenobiotic responsive element-mediated transcriptional activation in the UDP-glucuronosyltransferase family 1 gene complex

We have isolated genomic DNA clones containing rat UDP-glucuronosyltransferase family 1 (UGT1) sequences and have shown drug-responsive and tissue-specific alternative expression of multiple first exons (Emi, Y., Ikushiro, S., and Iyanagi, T. (1995) J. Biochem. (Tokyo) 117, 392-399). The UGT1 locus encodes at least nine UGT1 isoforms. UGT1A1 is a major 3-methylcholanthrene (MC)-inducible form in rat liver. In this report, we have identified a cis-acting element necessary for transcriptional activation of UGT1A1 in hepatocytes. A promoter region was fused to a chloramphenicol acetyltransferase gene, and the resultant construct was transiently transfected into hepatocytes. A DNA fragment carrying 1,100 nucleotides derived from the 5'-flanking region of the UGT1A1 gene was enough for MC induction. Unidirectional deletion of this region revealed that there existed one xenobiotic responsive element (XRE), TGCGTG, between -134 and -129. When a single base substitution was introduced into the XRE, MC-induced expression of the UGT1A1 gene was completely abolished. In addition, an XRE-deleted construct failed to respond to MC. Gel mobility shift assays showed MC-inducible binding of the nuclear aromatic hydrocarbon receptor-ligand complex to this motif. Gel shift-coupled DNase I protection analyses revealed that the GCGTG-core sequence was a target site of the liganded aromatic hydrocarbon receptor. These results suggest that the XRE participates in induction of the rat UGT1A1 gene by MC.

Identification and analysis of drug-responsive expression of UDP-glucuronosyltransferase family 1 (UGT1) isozyme in rat hepatic microsomes using anti-peptide antibodies

Expression of rat hepatic UDP-glucuronosyltransferase family 1 (UGT1) isozymes has been examined using anti-peptide antibodies raised against a conserved carboxyl-terminal portion of all isozymes and variable amino-terminal portions of each isozyme of the phenol cluster (UGT1A) and bilirubin cluster (UGT1B). Among the isozymes expressed in rat hepatic microsomes, UGT1B1 (54 kDa) of bilirubin cluster was found to be a major form and minor forms were identified as UGT1A1 (53 kDa), UGT1B2 (56 kDa), and UGT1B5 (57 kDa). Using a combination of 2D sodium dodecyl sulfate gel electrophoresis and immunoblotting, all the isozymes were found to be simultaneously lacked in Gunn rat hepatic microsomes. The effects of various drugs as inducer on the expression of each UGT1 isozyme were analyzed. The UGT1A1 and UGT1A2 of the phenol cluster isozymes were significantly induced in 3-methylcholanthrene-treated rats. The expression of UGT1B1 and the glucuronidation activity toward bilirubin in rat hepatic microsomes were induced two- to threefold by clofibrate and dexamethasone administration. On the other hand, the regulation of UGT1B2 and UGT1B5 expression was different from that of UGT1B1. These results clearly show the drug-responsive expression of each UGT1 isozyme using isozyme-specific antibodies for the first time.

Metabolism of peptide drugs by the microorganisms in rat cecal contents

The metabolism of insulin and calcitonin by microorganisms was examined in rat cecal contents. Both insulin and calcitonin were markedly degraded. Calcitonin was more susceptible to proteolysis in rat cecal contents than insulin. Calcitonin was also rapidly degraded in supernatant, while we found few degradation products of insulin. These findings suggest that care should be taken to metabolize the peptide drugs by microorganisms when they are administered to the large intestine for colon-specific drug delivery.

Clinicopathological features of patients who died with second primary cancer after curative resection for gastric cancer

The appearance of a second cancer in patients who had undergone curative operation for the first gastric cancer is one of the crucial problems for the clinician. We analysed data on 910 patients with gastric cancer treated with curative resection, with respect to the risk factors for second primary cancer and the prognosis. Of 910 patients, 69 (7.6%) died with a second primary cancer. In patients with a second primary cancer, there were more men and age was more advanced, compared to the survivors. The gastric tumor was larger, the serosal invasion was more prominent and lymphatic involvement was more frequent. The postoperative 5-year survival for patients with a second primary cancer was 60.9%, the 10-year rate was 31.9% and the 15-year was 19.6%. Multivariate analysis revealed that risk factors for a second primary cancer was advanced age, male sex and a larger tumor. Our findings suggest that during the follow-up of patients with gastric cancer treated by curative resection and risk factors, a second primary cancer may occur in other organs, in addition to a recurrence of the first cancer.

cDNA cloning of a putative G protein-coupled receptor from brain

Using degenerate oligonucleotide primers corresponding to conserved regions of the G-protein coupled receptor superfamily, we carried out a low-stringency polymerase chain reaction and obtained two novel partial-length clones from a rat brain cDNA library. We used one of these clones for conventional library screening and isolated a longer cDNA clone, designated as RBU-15, from another rat brain library. Although RBU-15 was truncated at its 5' end, Northern blot analysis revealed that the gene was expressed in the brain and spleen. Next, we isolated a full-length cDNA clone, designated as HB-954, from a human fetal brain library, using RBU-15 as a probe. The deduced amino acid sequence of HB-954 contained four putative glycosylation sites in the N-terminal part, seven transmembrane domains, and a large cytosolic domain in the C-terminal part. The protein products of RBU-15 and HB-954 likely belong to a distinctive subfamily, because no receptors in the superfamily were found to be closely related to them.

Drug-responsive and tissue-specific alternative expression of multiple first exons in rat UDP-glucuronosyltransferase family 1 (UGT1) gene complex

Genomic clones of UDP-glucuronosyltransferase family 1 (UGT1) were isolated from wild-type Wistar rats. The UGT1 locus spans > 120 kb and forms a gene complex. In this locus nine unique first exons encoding NH2-terminal portions of each isoform were located at intervals of approximately 10 kb and followed by only one set of commonly used exons (exons II, III, IV, and V) encoding the COOH-terminal portion. From sequence analyses of the unique first exons, the amino acid sequences of the isoforms were deduced and they were divided into two groups: the Bilirubin cluster (B cluster) and the Phenol cluster (A cluster). A and B clusters consisted of four (A1-A4) and five (B1-B5) isoform-specific exons, respectively. A2, A3, B3, and B4 were identified as previously uncharacterized forms, while A4 and B4 were pseudogenes. Isoform B1 was a major component in hepatic microsomes of untreated rats and was induced in clofibrate- and dexamethasone-administered rats. A slight but a significant amount of B1 mRNA was also detected in various tissues such as intestine. mRNAs coding for isoform A1 and isoform A2 were induced in livers of methylcholanthrene (MC)-treated rats. Induction of A1 mRNA was also observed in kidneys of MC-treated rats. A genomic clone containing the commonly used exons was also isolated from Gunn rats and a single base deletion was identified in exon IV. Isoforms of the UGT1 family are made from the complex gene locus by an alternative combination of one of the unique first exons with the commonly used exons.

Increased efficacy of chemo- and radio-therapy by a hemoglobin solution in the 9L gliosarcoma

Tissue oxygen tensions were measured in the rat 9L gliosarcoma under conditions of normal air breathing or carbogen breathing and after intravenous administration of a hemoglobin solution with air breathing or carbogen breathing. Administration of the hemoglobin decreased the level of hypoxia in the tumors. Treatment of the animals with the antiangiogenic combination of TNP-470 and minocycline also increased tumor oxygenation compared with untreated controls. Treatment with the antiangiogenic agents along with administration of the hemoglobin solution/carbogen breathing decreased the hypoxic fraction (% pO2 readings < or = 5 mmHg) from 71 % to 30%. Treatment of the tumor-bearing animals with BCNU or adriamycin modestly reduced hypoxia in the tumors, while treatment with fractionated radiation markedly increased hypoxia in the tumors. Tumor growth delay was used to assess the response of the subcutaneous tumor to the various treatment combinations. There was a strong correlation between increased therapeutic response and decreased tumor hypoxia. Tumor growth delay from BCNU increased from 5.3 days to 16.4 days with TNP-470/-minocycline/hemoglobin solution/carbogen. Similarly, the tumor growth delay from adriamycin increased from 3.9 days to 17.0 days with TNP-470/minocycline/hemoglobin solution/carbogen. Finally, the tumor growth delay from fractionated radiation increased from 4.8 days to 13.3 days with TNP-470/minocycline/hemoglobin solution/carbogen. When etanidazole was added to the complete radiation regimen, the tumor growth delay increased further to 20.5 days. These data show that the addition of non-toxic agents that increase tumor oxygenation to cytotoxic therapies can markedly increase therapeutic response.

Potentiation of cytotoxic therapies by TNP-470 and minocycline in mice bearing EMT-6 mammary carcinoma

The ability of the antiangiogenic agents TNP-470 and minocycline, singly or in combination, to potentiate the antitumor effects of several cytotoxic therapies was assessed in the murine EMT-6 mammary carcinoma as well as in two drug resistant sublines of that tumor designated EMT-6/CTX and EMT-6/CDDP. The antiangiogenic agents alone or in combination did not alter the growth of the tumors. However, their administration along with cyclophosphamide, CDDP, or thiotepa substantially increased the tumor growth delay produced by these cytotoxic therapies in tumors responsive to the drugs--the increase was about 2-fold for TNP-470 and minocycline together. In drug resistant tumors, treatment with the antiangiogenic agents did not reverse drug resistance but did increase the effect of the cytotoxic drugs. Treatment with TNP-470/minocycline also increased the oxygenation of each of the three tumors. Thus, TNP-470/minocycline administration increased the efficacy of fractionated radiation therapy, especially when used along with a perflubron emulsion oxygen delivery agent/carbogen. These results indicate that treatment regimens including therapies directed toward the proliferating normal cells within a tumor mass as well as therapies directed toward the malignant cells can produce improved outcomes.

Hyperthermia enhances the cytotoxicity against hypoxic cells of RP-170, a new 2-nitroimidazole nucleoside hypoxic cell sensitizer

The effect of the new hypoxic cell sensitizer, 1-[2-hydroxy-1-(hydroxymethyl)-ethoxy]methyl-2-nitroimidazole (RP-170), combined with heat against EMT6/KU cells, was determined under conditions of in vitro hypoxia. Heat-induced cytotoxicity for the EMT6/KU cells was increased to a greater extent under conditions of hypoxia and a normal pH of the medium. Hypoxia also reduced the surviving fraction of the cells treated either with RP-170 alone or with RP-170 plus heat. The concomitant treatment of RP-170 and heat inhibited the clonogenic activity of the EMT6/KU cells under conditions of in vitro hypoxia in all experimental groups, with a significant difference (p < 0.05). Therefore, RP-170 combined with exposure to heat may be an effective treatment for hypoxic cells in a solid tumor, as these cells are resistant to radiation and/or to many chemotherapeutic agents.

Hydralazine combined with hyperthermia enhances the effects of carboquone

Carboquone (CQ) and hyperthermia (HT) are capable of preferentially killing oxygen-deficient cells, both in vitro and in vivo. We examined effects of the combination of CQ and HT on an in vitro hypoxic system and on murine solid tumors using hydralazine (HYD), a vasoactive agent. Under in vitro hypoxic conditions, the combined cytotoxicity of CQ and HT (43 degrees C, for 1 h) was enhanced and the enhancement ratio (ER) for the IC90 of CQ was 21.4-, 9.4-, and 2.6-fold compared to that for CQ alone, CQ under hypoxic condition, and CQ plus HT under aerated cells, respectively. Five mg/kg i.p. HYD reduced the level of tumor blood flow in mice to about 20% of constant level and this reduction persisted for 1 h. In mice bearing B16 melanoma tumors, HYD enhanced tumor susceptibility of the combined therapy of CQ and HT. The ER which was a comparison of tumor growth time in the control group, was 2.3, 3.6 for the two combination groups of 1, 2 mg/kg i.p. CQ, HT (43 degrees C for 20 min), and 5 mg/kg i.p. HYD, respectively. Thus, hyperthermochemotherapy using CQ combined with HYD, seems to selectively attack a solid tumor.

Laser flow cytometric studies on the intracellular accumulation of anthracyclines when combined with heat

The effects of heat on intracellular accumulation of anthracyclines were investigated by laser flow cytometry analysis. Sarcoma-180 cells were exposed to Adriamycin (ADM), epirubicin (EPIR), daunomycin (DM), THP-Adriamycin (THP), ME-2303 (ME) and KRN-8602 (KRN) at 37 degrees C and at higher temperatures. There was a dose-dependent increase in the fluorescence intensity of all drugs at 37 degrees C, but heat varied the fluorescence intensity of each drug. At 43 degrees C the cellular fluorescence of ADM and EPIR increased by approximately 200%, but for DM the increase was 110-130%. The cellular fluorescence of THP and ME was little affected by heat, and heat reduced that of KRN to 80-90%. Each drug showed was unique in the relationship between drug exposure time and the fluorescence intensity at 37 degrees C and 43 degrees C. Cytotoxicity determined by the MTT assay was enhanced with heat in the cases of ADM and EPIR, but not with DM, THP, ME, or KRN. Thus, ADM and EPIR are expected to show enhanced antitumor activities when given in combination with hyperthermia.

L-histidinol potentiates hyperthermic cell-killing in-vitro

To clarify the effect of L-histidinol on hyperthermic killing of cells, HeLa and mouse sarcoma-180 (S-180) cells were exposed to heat in vitro in the presence of L-histidinol and the clonogenic surviving fraction of the cells was examined. After pretreating the cells with L-histidinol for 4 h, exposure of the cells to the combination of heat at 43-degrees-C and L-histidinol for various times (30 min to 4 h) reduced the surviving fraction more prominently than heat alone. Optimal concentrations to confer effective enhancement of heat on HeLa and S-180 cells were 9 mM and 3 mM, respectively. Those concentrations showed little toxicity of L-histidinol alone. Enhancement of the effect of heat by L-histidinol was observed only at 43-degrees-C, but not at 41 and 42-degrees-C. Flow cytometric DNA analysis was used to examine the cell cycle transit effect of L-histidinol. L-histidinol alone arrested the HeLa cells in G1-phase. Heat treatment at 43-degrees-C led to an accumulation of the cells in G2/M-phase and a decrease in the G1-phase fraction. The effect of combined treatment with heat and L-histidinol was complementary, in which L-histidinol attenuated the accumulation of the cells in G2/M-phase and prevented a decrease in the G1-phase fraction. Thus, L-histidinol has the capacity to potentiate hyperthermic cell killing in vitro by a mechanism that may be related to the cell cycle transit effect.

Use of the succinate dehydrogenase inhibition test in assessing the heat sensitivity of tumor cells

The in vitro succinate dehydrogenase (SD) inhibition (SDI) test was used to determine the heat sensitivity of tumor cell lines and human tumor cells. The tumor cells were exposed to heat in vitro and the decrease in SD activity was assayed using a colorimetric assay, the SDI test. With respect to survival curves of HeLa cells, the SDI test correlated well with the clonogenic assay and the dye exclusion assay. Decrease in the SD activity of HeLa cells after the heat treatment (41-44 degrees C, 10 min to 5 h) depended on both the temperature and the duration of heat exposure. S- and G2/M-phase-rich HeLa cells were more sensitive to heat than were the G1-phase-rich cells. The SDI test exhibited a wide variation in the heat sensitivity among four cell lines (HeLa, B-16, V-79, and a human GT-1 squamous cell carcinoma). Variation in heat sensitivity was also detected among individual tumor tissues obtained from clinical specimens of gastric, esophageal, and colorectal cancers. Gastric cancer tissues were more sensitive to heat than were esophageal and colorectal tissues. We recommended that if the SDI test is used to assess the heat sensitivity of clinical tumor tissues in vitro, appropriate therapy for individual patients can be designed.

Effect of hyperthermia on the activity of 1-[(4'-hydroxy-2'-butenoxy)methyl]-2-nitroimidazole, which is cytotoxic to hypoxic cells

The effect on EMT6/KU cells of a newly synthesized hypoxic cell sensitizer, 1-[(4'-hydroxy-2'-butenoxy)methyl]-2-nitroimidazole (RK28), combined with heat was determined in vitro under conditions of hypoxia. As compared with aerobic conditions, hypoxia produced a 1.30-fold increase in the cytotoxicity of the drug for mouse mammary EMT6/KU cells induced by 1 h heat treatment at 43 degrees C in medium with a normal pH. Hypoxia also reduced the surviving fraction of cells treated with both RK28 alone for 2 h and the same concentrations of RK28 and heat (43 degrees C) in combination. Those enhancement ratios corresponded to a 20.3- and > 345-fold increase, respectively. Moreover, concomitant treatment with RK28 and heat greatly inhibited the clonogenic activity of the EMT6/KU cells under conditions of in vitro hypoxia and in all experimental groups; there was a statistically significant difference in the time-response curves (P < 0.05). As hypoxic cells in a solid tumor are resistant to various anticancer drugs, RK28 combined with hyperthermia deserves further study for possible clinical applications.

Intracellular accumulation of free calcium in mouse tumor cells exposed to anticancer drugs

Alterations in concentrations of intracellular free calcium ([Ca2+]i) were examined in mouse sarcoma S-180 cells exposed to cisplatin, mitomycin C and adriamycin, as related to cell viability. The [Ca2+]i was measured using the fluorescent Ca2+ indicator, fura-2. During the first 24 hr of incubation of the cells in vitro, in the presence of the drugs, the [Ca2+]i was lower than in the control cells. After 24 hr of incubation, the [Ca2+]i began to increase at a time when the cell viability was reduced to 50% of the controls, and finally exceeded 1 microM with reduction to 10%. The increase in [Ca2+]i was reciprocal to the loss of the cell viability. Changes in Ca2+ concentrations in the medium did not alter the results. These findings suggest that in the presence of anticancer drugs there is an accumulation of free Ca2+ with a release of this ion from internal stores and that cell death follows disruption in the homeostasis of intracellular Ca2+.

Hyperthermia enhances the inhibition of tumor growth by 1-(2-tetrahydrofuryl)-5-fluorouracil/uracil (1:4) in tumors in mice and humans

The cytotoxicity of several antitumor drugs is enhanced by hyperthermia (HT). Using mouse Sarcoma-180 (S-180) tumors, the authors examined the effects of 5-fluorouracil (5-FU) and a combined oral preparation of 1-(2-tetrahydrofuryl)-5-fluorouracil (FT) and uracil in a molar ratio of 1:4 (UFT), in combination with HT. The antitumor effect of 5-FU was not enhanced significantly by HT. Growth inhibition by UFT plus HT was significantly greater than that by UFT alone, whereas inhibition by UFT alone was significantly greater than that by 5-FU. The intracellular metabolism of 5-FU and FT in whole homogenates of S-180 cells, human tumor cell lines (SC-2 and Lu-99), and five fresh human tumor tissues also was investigated. Conversion of FT to 5-FU, phosphorylation, and degradation of 5-FU were assayed with [3H]FT or [3H]5-FU, and the products were separated by thin-layer chromatography. The conversion of FT to 5-FU and the phosphorylation of 5-FU were more rapid at 43 degrees C than at 37 degrees C, whereas the degradation of 5-FU to 2-fluoro-beta-alanine remained unchanged. This acceleration of the active metabolism of FT and 5-FU may be one explanation for the enhanced effect of UFT by HT.

Postoperative chemotherapy for patients with advanced gastric cancer

The relationship between postoperative chemotherapy and survival time after gastric resection in patients with advanced gastric cancer was examined by retrospectively reviewing data on 916 patients treated in our clinics between 1965 and 1985. Of these patients, 738 were treated postoperatively with antitumor drugs. Postoperative chemotherapy was more often prescribed for those in the advanced stages of malignancy. Univariate analysis revealed that the survival time of patients given postoperative chemotherapy was shorter than for those not receiving chemotherapy, but there was no statistical significance. Multivariate analysis using the Cox regression analysis adjusted for sex, age, and other covariants indicated that operative curability, liver metastasis, serosal invasion, lymph node metastasis, peritoneal dissemination, and tumor size were the important prognostic factors. There was no correlation with postoperative chemotherapy. Our findings rule out any relationship between postoperative chemotherapy and length of survival time for patients with advanced gastric cancer undergoing gastric resection.

Metabolism of 1-(2-tetrahydrofuryl)-5-fluorouracil to 5-fluorouracil in partially hepatectomized rats

Changes in the metabolism of 1-(2-tetrahydrofuryl)-5-fluorouracil (tegafur) to 5-fluorouracil (5-FU) were examined in the plasma, lung, liver, stomach, small intestine, spleen and kidney in two-thirds partially hepatectomized rats. Concentrations of tegafur and 5-FU in plasma and tissues were determined 30 min after injecting 100 mg/kg of tegafur via the tail vein. The 5-FU concentration in the plasma remained unchanged for the first 7 days after hepatectomy. The tissue level of 5-FU was higher in the liver and kidney than in other organs examined, but there were no changes in levels of 5-FU in each organ examined. Our observations support the proposal that the conversion of tegafur to 5-FU is maintained in partially hepatectomized rats.

Resistance to anticancer drugs of well differentiated gastric adenocarcinoma with venous invasion

A comparison of the chemosensitivity of well-differentiated human gastric cancer tissues was made between histological venous invasion positive (v(+)) and negative (v(-)) tissues, using the succinate dehydrogenase inhibition (SDI) test. These tissues obtained at the time of surgery were exposed to six anticancer drugs: carboquone (CQ), adriamycin (ADM), mitomycin C (MMC), aclacinomycin A (ACR), cisplatin (DDP) and 5-fluorouracil (5-FU). Chemosensitivity was judged to be positive when the succinate dehydrogenase (SD) activity of the drug exposed cells decreased to below 50% of that of control cells. Decrease in the SD activity was more apparent in the v(-) tissues than in the v(+) tissues, exposed to the anticancer drugs and in particular to ADM (P less than 0.01), MMC (P less than 0.02) and DDP (P less than 0.05). The sensitivity rates to all six anticancer drugs were lower in the v(+) tissues. The resistance rates to all drugs tested were 0% in the v(-) tissues, but 21% in the v(+) tissues. In light of these observations, patients with gastric cancer of the well differentiated type and the histological venous invasion, will probably show a less positive response to cancer chemotherapy.

Prognosis for surgically treated gastric cancer patients is poorer for women than men in all patients under age 50

From 1965 to 1983, 1031 patients (689 men and 342 women) with advanced gastric cancer underwent gastric resection in our department. A retrospective study was done with special reference to the sex of the patients. The age, tumour size and location, Borrmann type, and histology were considered as the sex-related associations. The survival rate of women under age 50 years was lower than that of men, with a significant difference (P less than 0.01), and the 10-year survival rate was 39.2% for the men and 29.3% for the women. A multivariate analysis showed that the operative curability (relative risk: 2.11), lymph node metastasis (relative risk: 1.37), depth of invasion (relative risk: 1.30) and tumour size (relative risk: 1.05), all significant prognostic factors, differed between the men and women under age 50 years, and the survival rate for women was lower. Thus, early detection of gastric cancer is crucial to improve the survival of women under age 50 years. Postoperative chemotherapy may be considered for those with an advanced gastric cancer.

Epirubicin is equivalent to adriamycin in vitro against many cancer cells but more effective against gastric cancer cells

We compared the cytotoxic effects of two anthracycline derivatives, epirubicin (EPI) and adriamycin (ADM), against human tumor cells in vitro. Various tumor specimens, obtained at surgery, included 57 liver, 19 lung, 16 gastric, 10 colorectal and 7 breast cancer specimens. These tumor cells were exposed to the same concentration of EPI or ADM for 3 days. The chemosensitivity of each tumor cell type to each drug was then assayed using the in vitro succinate dehydrogenase inhibition (SDI) test. Sensitivity to the treatment was defined as a 50% or greater reduction in the succinate dehydrogenase (SD) activity of the tumor cells, relative to that of the control (untreated) cells. Each cell type, except for gastric cancer cells, was equally sensitive to EPI and ADM. Gastric cancer cells were more sensitive to EPI than to ADM (P less than 0.05). The rate of coincidence, the sum of the co-sensitive and co-resistant rates of all the tumors, was quite high (90.8%). Thus, these findings indicate that EPI and ADM are equally cytotoxic to each tumor cell type, but EPI is more cytotoxic than ADM to gastric cancer cells. Since EPI is reported to be less cardiotoxic than ADM, EPI may replace ADM in cancer chemotherapy.

Ultrastructural analysis of pulmonary alveolar proteinosis induced by methylnaphthalene in mice

Pulmonary alveolar proteinosis was induced at a 100% incidence in B6C3F1 female mice by twice weekly painting the back skin with methylnaphthalene for 30 weeks to give a total dose of 7.14 g/kg b.wt. Semithin sections were used for defining areas of type II pneumocyte hyperplasia and hypertrophy and associated proteinosis. Ultrastructurally, alveolar spaces were found to be filled with numerous myelinoid structures resembling the lamellar bodies of type II pneumocytes. Mononucleated giant cells (balloon cells, BC) containing numerous myelinoid structures, lipid droplets and many electron dense amorphous ascicular crystals were closely associated with this extracellular membranous material. Stacks of elastic fibers stained with tannic acid and bundles of collagen fibers were loose and discontinuous in the interstitium of affected areas. The following pathogenesis is hypothesized: type II pneumocytes produce increased amounts of lamellar bodies due to their hyperplasia and hypertrophy and develop to form BC which liberate numerous myelinoid structures on their rupture. Epidermal absorption of methylnaphthalene is an efficient reliable method of induction of this internal disease.

Cytotoxicity of mitomycin C and carboquone combined with hyperthermia against hypoxic tumor cells in vitro

Enhancement of the cytotoxicity of mitomycin C (MMC) and carboquone (CQ) by hypoxia at elevated temperature was examined using the SDI test of mouse Sarcoma 180 and Ehrlich cells and clonogenic assay of HeLa cells. When Sarcoma 180 and Ehrlich cells were incubated at 43 degrees C for 2-10 h, the hyperthermic effect was enhanced by hypoxia. The succinate dehydrogenase activity of the cells was reduced by hyperthermia to a greater extent in the presence of hypoxia (O2:5%) than under conditions of aeration (O2:20%). When the cells were exposed to various concentrations of MMC and CQ, under hypoxia, activity of the drugs was enhanced compared to the findings under conditions of aeration. The enhancement was prominent in case of drugs and hyperthermia combined. Clonogenicity of hypoxic HeLa cells was also reduced to a greater extent with this combination than in case of aerated cells. We tentatively speculate that hyperthermo-chemotherapy using MMC and CQ has a potential to attack selectively hypoxic cells present in a solid tumor.

Chronic toxicity carcinogenicity studies of triethanolamine in B6C3F1 mice

The chronic toxicity and carcinogenic potential of triethanolamine was examined in B6C3F1 mice. Triethanolamine, dissolved in distilled water at levels of 0 (control), 1, and 2%, was given to groups of 50 males and 50 females ad libitum in drinking water for 82 weeks. Neoplasms developed in all groups, including the control group, but no dose-related increase of the incidence of any tumor was observed in treated groups of both sexes. There were no adverse effects as regards survival of the mice, organ weights, and specific incidence of neoplasms in the treated, compared to the control group. This chronic toxicity test provides no evidence of carcinogenic potential of triethanolamine in B6C3F1 mice.

Adriamycin combined with hyperthermia and dipyridamole is cytotoxic both in vitro and in vivo

The cytotoxicity of adriamycin (ADM) combined with hyperthermia (Hyp) and/or dipyridamole (DP) was investigated using B16 melanoma cells in vitro and in vivo. When ADM was combined with Hyp at 43 degrees C or DP in a dose of 5 microM or with both, drug cytotoxicity enhanced the inhibition of colony formation and cell growth, and the effect was maximal when Hyp and DP were combined. Incubation with DP alone for 24 h, following ADM exposure, enhanced the toxicity even further (p less than 0.01). Measurement of intracellular levels of ADM in the B16 melanoma cells showed that Hyp and DP increased accumulation of ADM, and that DP, but not Hyp, significantly suppressed the ADM excretion (p less than 0.05). Growth of B16 melanoma implanted into subcutaneous tissue of the foot of C57BL mice was inhibited to a greater extent by the combination treatment of ADM and DP, ADM and Hyp, and also that of ADM, Hyp and DP, compared to the findings in cases of ADM or Hyp alone. As this trimodality treatment is effective both in vitro and in vivo, further study on possible clinical advantage is warranted.

Sarcoma-180 cells and human colorectal tumor cells under in vitro hypoxic conditions are more sensitive to mitomycin C and carboquone

The effects of oxygen concentration on the chemosensitivity of mouse sarcoma-180 (S-180) cells and human colorectal cancer tissues to mitomycin C (MMC) or carboquone (CQ) were determined in vitro, since evidence had been obtained that these drugs are more effective in HeLa cells. The results were as follows: (a) S-180 cells exposed to various concentrations of MMC or CQ for 2 h under conditions of normal aeration (about 20%) or hypoxia (5.0% and 0%) were then maintained under normal conditions of aeration for 3 days. Change of viability was assessed by succinate dehydrogenase (SD) activity. With exposure of the cells to MMC or CQ, under anoxic conditions (O2:0%), SD activity decreased to a greater extent than seen in the control cells. The value for CQ was from 61.5% to about 36.2%. (b) The decrease in the SD activity of 20 colorectal cancer tissues kept under conditions of anoxia was compared with findings under normally aerated conditions, following exposure to 30 microM of MMC or 1.6 microM of CQ. On exposure to MMC or CQ under anoxic conditions, SD activity decreased significantly, compared with normally aerated conditions (P less than 0.001 for MMC; P less than 0.05 for CQ). As colorectal cancer is less sensitive than other tissues to various chemotherapeutic agents, we recommend that MMC and CQ be prescribed to treat patients with these malignant lesions.

Hypoxia and acidity increase the cytotoxicity of mitomycin C and carboquone to human tumor cells in vitro

To clarify the influence of hypoxic and acidic environments on the cytotoxicity of mitomycin C (MMC) and carboquone (CQ), the cytotoxicity was assessed based on decreases in intracellular ATP levels of HeLa cells exposed to the drugs at various acidic pH (pH 5.8-6.8) and low oxygen tension (5% and 0% O2) in vitro. Hypoxia and acidity individually increased the cytotoxicity of MMC, although hypoxia no longer increased it under acidic conditions. On the other hand, the cytotoxicity of CQ was enhanced in the presence of hypoxic and acidic conditions, and even more so with their combination. We conclude that acidity is a determining factor and excels hypoxia in influencing the cytotoxicity of MMC and that these two factors act synergistically on CQ.

A protein-bound polysaccharide immunomodulator, PSK, does not suppress the conversion from 1-(2-tetrahydrofuryl)-5-fluorouracil to 5-fluorouracil in patients with gastric cancer

Effects of the immunomodulator PSK on the metabolism of 1-(2-tetrahydrofuryl)-5-fluorouracil (tegafur) to 5-fluorouracil (5-FU) were examined in 10 patients with advanced gastric cancer and who had undergone curative resection. PSK is a protein-bound preparation, extracted from Coriolus versicolor and belongs to Basidiomycetes. The 5-FU concentration in the plasma was 0.024 micrograms/ml at 15 min after the intravenous injection of 400 mg of tegafur and the area under the curve of 5-FU was 0.58 micrograms.h/ml. Following administration of PSK, 3 g/day for 8-14 months, there was no change in the plasma level of 5-FU, in any patient. As the clinical dose of PSK had no apparent influence on the metabolism of tegafur to 5-FU, the combination of PSK and tegafur can be prescribed to treat patients with advanced gastric cancer.

Lower survival rate for patients under 30 years of age and surgically treated for gastric carcinoma

We analysed data on 38 patients with gastric cancer aged 30 years and younger who were surgically treated in the Department of Surgery II, Kyushu University Hospital, between 1965 to 1985. These younger patients comprised 2.6% of the total 1,470 patients treated for gastric cancer during this 21-year period. The durations and the kinds of symptoms in the preoperative period varied with the patient. In patients under 30 years of age, the female patients predominated, and in addition, undifferentiated lesions were more common than the differentiated type, tumours were larger, serosal invasion was more prominent, lymphatic involvement was more common, tumours showed infiltrative growth and the rate of peritoneal dissemination was higher. Consequently the survival rates for these younger patients were poor. Detection at an early stage of the disease is mandatory if the survival rates of younger patients with gastric cancer are to improve.

The microtiter SDI test is more advantageous than the SDI test for assessing the chemosensitivity of human tumor cells

The in vitro succinate dehydrogenase inhibition (SDI) test was adapted to be used with microtiter plates and this microtiter SDI (mSDI) test was evaluated for clinical use of chemosensitivity testing, as compared to findings with the SDI test. The optimal conditions of the mSDI test were determined: (1) 2-5 x 10(4) cells/well; (2) enzymatic disaggregation of solid tumors with the use of a mixture of 0.2% pronase, 0.25% collagenase, 0.1% DNase for 20 min at 37 degrees C; (3) addition of 10 mM sodium succinate in the colorimetric reaction; and (4) use of dimethyl sulfoxide (DMSO) as a solvent for extraction of formazan product. Good correlations were observed between the mSDI and the SDI tests when S-180 cells (r = 0.890-0.996) or 16 human fresh tumor cells (r = 0.731-0.999) were exposed to six anti-cancer drugs (carboquone, adriamycin, mitomycin C, aclacinomycin A, cisplatin, 5-fluorouracil). Thus, the mSDI test facilitates testing of a large number of drugs with minimal amounts of specimens, and is expected to replace the SDI test for chemosensitivity testing of clinical tumor cells.

Dipyridamole combination chemotherapy can be used safely in treating gastric cancer patients

The feasibility of a combined chemotherapy using dipyridamole (DP) with adriamycin (ADM) and 5-fluorouracil (5-FU) was investigated. First, the chemosensitivity of gastric cancer tissues was determined by the succinate dehydrogenase inhibition test, which showed sensitivity to ADM and 5-FU is increased by DP. Next, a clinical trial of combined therapy of DP, ADM and 5-FU, as a post-operative adjuvant chemotherapy for gastric cancer patients, was performed. DP (50 mg) was given as a 1-h i.v. infusion, and ADM (20 mg) was given as a single i.v. injection. This treatment was started on post-operative day 10, and was repeated every 2 weeks. Simultaneously with these treatments, DP (300 mg) and 5-FU (150 mg) were administered post-operatively daily. A total of 63 courses of therapy in nine patients were performed. The adverse effects related to the DP infusion were flushing, headache, nausea and upper abdominal discomfort, all of a low grade. DP did not appear to alter the toxicity of ADM and 5-FU, and no severe adverse effect was noted for this combination therapy. The pharmacokinetics of DP were also investigated in five patients. The mean plasma concentration of DP increased 4.41 micrograms/ml and remained above 0.25 microgram/ml for over 6 h. This combination chemotherapy appears to be safe and may be useful clinically in treating cancer.

1-Hexylcarbamoyl-5-fluorouracil alters the expression of heat shock protein in HeLa cells

We determined the effect of 1-hexylcarbamoyl-5-fluorouracil (HCFU), a masked compound of 5-fluorouracil, on the expression of heat shock protein (HSP) in heat-treated HeLa cells. We used a monoclonal anti-72-kDa heat shock protein antibody. At 37 degrees C, HSP was predominant in the cytoplasm of cells and heating to 43 degrees C for 30 min increased the synthesis of HSP in the nucleus. When HeLa cells were treated with heat and HCFU, at a concentration which showed evidence of synergy, nuclear staining of the cells decreased. Thus, the altered expression of HSP by HCFU is related to a synergism between heat and HCFU.

Lung adenocarcinoma is more sensitive than gastric adenocarcinoma to anticancer drugs in vitro

The chemosensitivities of 26 lung adenocarcinoma tissues were compared to those of 110 gastric adenocarcinoma tissues, using the in vitro succinate dehydrogenase inhibition (SDI) test. Tumour tissues obtained at surgery were exposed to five different anticancer drugs: carboquone (CQ), adriamycin (ADM), mitomycin C (MMC), cisplatin (DDP) and 5-fluorouracil (5-FU). The lung adenocarcinomas showed a statistically significant reduction in succinate dehydrogenase (SD) activity, compared to the gastric adenocarcinomas, after exposure to each drug. The chemosensitivity was defined as a reduction in SD activity to 50% of control or less. Lesser degrees of reduction in SD activity were defined as drug resistance. The sensitivity rates to ADM, MMC and DDP, respectively, were significantly higher in the lung than in the gastric adenocarcinomas. Tumour cells from 22 (84.6%) of the 26 lung adenocarcinoma tissues showed a sensitivity to more than three drugs, whereas the rate was only 46.4% (51/110) for the gastric adenocarcinomas. The rate of resistance to all the drugs tested was 3.8% (1/26) for the lung adenocarcinomas, in contrast to the 20.9% (23/110) seen with the gastric adenocarcinomas. Thus, while adenocarcinomas of the lung and stomach both show clinical resistance to anticancer agents, the chemosensitivity of the lung tissues is greater. In the light of these observations, attention must be directed to improving specific drug delivery systems.

A different cytochrome P450 form is induced in primary cultures of rat hepatocytes

A 49-kDa protein (P49) was discovered in the primary cultures of rat hepatocytes. P49 cross-reacted with the antibodies against purified P450IIC11 [formerly P-450(M-1)]. P49 was located in microsomes and highly induced after plating of isolated hepatocytes on collagen-coated culture dishes. To characterize P49, cDNA clones were screened from a rat liver lambda gt11 expression library. From sequence analysis of the cloned cDNAs, the amino acid sequence of P49 was deduced, and the protein was identified as a previously uncharacterized form of cytochrome P450. P49 consists of 489 amino acids and shows approximately 60% similarity with the members of class IIC subfamily of rat cytochrome P450, such as P450IIC11 and P450IIC12 [formerly P-450(F-1)]. RNA blot analysis indicates that the mRNA translating P49 was induced approximately 20- to 30-fold at 70 hr in the primary cultures compared with the liver of adult rats. Induction of P49 was not affected by density of the plated cells and the presence or absence of several hormones, serum, or antibiotics in the culture medium. On the other hand, lower induction of P49 was seen when the hepatocytes were cultured on Matrigel-coated plates. Expression of P49 mRNA was low in the liver of adult rats and was not detectable in the livers of 1- and 2-week-old male and female rats. P49 is an additional form of cytochrome P450, which is induced in the primary culture of rat hepatocytes.