Showing papers in "Japanese Journal of Cancer Research in 1997"

Bovine Lactoferrin and Lactoferricin, a Peptide Derived from Bovine Lactoferrin, Inhibit Tumor Metastasis in Mice

Abstract: We investigated the effect of a bovine milk protein, lactoferrin (LF-B), and a pepsin-generated peptide of LF-B, lactoferricin (Lfcin-B), on inhibition of tumor metastasis produced by highly metastatic murine tumor cells, B16-BL6 melanoma and L5178Y-ML25 lymphoma cells, using experimental and spontaneous metastasis models in syngeneic mice. The subcutaneous (s.c.) administration of bovine apo-lactoferrin (apo-LF-B, 1 mg/mouse) and Lfcin-B (0.5 mg/mouse) 1 day after tumor inoculation significantly inhibited liver and lung metastasis of L5178Y-ML25 cells. However, human apolactoferrin (apo-LF-H) and bovine holo-lactoferrin (holo-LF-B) at the dose of 1 mg/mouse failed to inhibit tumor metastasis of L5178Y-ML25 cells. Similarly, the s.c. administration of apo-LF-B as well as Lfcin-B, but not apo-LF-H and holo-LF-B, 1 day after tumor inoculation resulted in significant inhibition of lung metastasis of B16-BL6 cells in an experimental metastasis model. Furthermore, in in vivo analysis for tumor-induced angiogenesis, both apo-LF-B and Lfcin-B inhibited the number of tumor-induced blood vessels and suppressed tumor growth on day 8 after tumor inoculation. However, in a long-term analysis of tumor growth for up to 21 days after tumor inoculation, single administration of apo-LF-B significantly suppressed the growth of B16-BL6 cells throughout the examination period, whereas Lfcin-B showed inhibitory activity only during the early period (8 days). In spontaneous metastasis of B16-BL6 melanoma cells, multiple administration of both apo-LF-B and Lfcin-B into tumor-bearing mice significantly inhibited lung metastasis produced by B16-BL6 cells, though only apo-LF-B exhibited an inhibitory effect on tumor growth at the time of primary tumor amputation (on day 21) after tumor inoculation. These results suggest that apo-LF-B and Lfcin-B inhibit tumor metastasis through different mechanisms, and that the inhibitory activity of LF-B on tumor metastasis may be related to iron (Fe3+)-saturation.

Photodynamic Effect of Polyethylene Glycol-modified Fullerene on Tumor

Abstract: Fullerene (C 60 ) efficiently generates singlet oxygen when irradiated with light, and thus should have a photodynamic effect on tumors, if it is accumulated in the tumor tissue. To explore tumor targeting of C 60 , we chemically modified the water-insoluble C 60 with polyethylene glycol (PEG), not only to make it soluble in water, but also to enlarge its molecular size. When injected intravenously into mice carrying a tumor mass in the back subcutis, the C 60 -PEG conjugate exhibited higher accumulation and more prolonged retention in the tumor tissue than in normal tissue. The conjugate was excreted without being accumulated in any specific organ. Following intravenous injection of C 60 -PEG conjugate or Photofrin® to tumor-bearing mice, coupled with exposure of the tumor site to visible light, the volume increase of the tumor mass was suppressed and the C 60 conjugate exhibited a stronger suppressive effect than Photofrin. Histological examination revealed that conjugate injection plus light irradiation strongly induced tumor necrosis without any damage to the overlying normal skin. The antitumor effect of the conjugate increased with increasing irradiation power and C 60 dose, and cures were achieved by treatment with a dose of 424 μg/kg at an irradiation power of 107 J/cm 2 . These findings indicate that PEG-modified C 60 is a candidate agent for photodynamic tumor therapy.

Mechanisms of Growth Inhibition of Human Lung Cancer Cell Line, PC‐9, by Tea Polyphenols

Abstract: (-)-Epigallocatechin gallate (EGCG), the main constituent of green tea, and green tea extract show growth inhibition of various cancer cell lines, such as lung, mammary, and stomach. We studied how tea polyphenols induce growth inhibition of cancer cells. Since green tea extract contains various tea polyphenols, such as EGCG, (-)-epigallocatechin (EGC), (-)-epicatechin gallate (ECG), and (-)-epicatechin (EC), the inhibitory potential of each tea polyphenol on the growth of a human lung cancer cell line, PC-9 cells, was first examined. EGC and ECG inhibited the growth of PC-9 cells as potently as did EGCG, but EC did not show significant growth inhibition. The mechanism of growth inhibition by EGCG was studied in relation to cell cycle regulation. Flow cytometric analysis revealed that treatment with 50 microM and 100 microM EGCG increased the percentages of cells in the G2-M phase from 13.8% to 15.6% and 24.1%, respectively. The DNA histogram after treatment with 100 microM EGCG was similar to that after treatment with genistein, suggesting that EGCG induces G2-M arrest in PC-9 cells. Moreover, we found by microautoradiography that [3H]EGCG was incorporated into the cytosol, as well as the nuclei. These results provide new insights into the mechanisms of action of EGCG and green tea extract as cancer-preventive agents in humans.

Auraptene, a citrus coumarin, inhibits 12-O-tetradecanoylphorbol-13-acetate-induced tumor promotion in ICR mouse skin, possibly through suppression of superoxide generation in leukocytes.

Abstract: Coumarin-related compounds, auraptene and umbelliferone, have been isolated from the cold-pressed oil of natsumikan (Citrus natsudaidai HAYATA), and tested as inhibitors of tumor promoter 12-O-tetradecanoylphorbol-13-acetate (TPA)-induced Epstein-Barr virus activation in Raji cells. The 50% inhibitory concentration (IC50) of auraptene (18 microM) was almost equal to that of genistein. Umbelliferone, which lacks a geranyloxyl group present in auraptene, was less active (IC50 = 450 microM). In a two-stage carcinogenesis experiment with 7,12-dimethylbenz[a] anthracene (topical application at 0.19 mumol) and TPA (topical application at 1.6 nmol) in ICR mouse skin, topical application of auraptene (at 160 nmol) significantly reduced tumor incidence and the numbers of tumors per mouse by 27% (P < 0.01) and 23% (P < 0.05), respectively. Auraptene at a concentration of 50 microM markedly suppressed superoxide (O2-) generation induced by 100 microM TPA in differentiated human promyelocytic HL-60 cells. Having no O2(-)-scavenging potential, auraptene may inhibit the multicomponent NADPH oxidase system. Inhibition of intracellular hydroperoxide formation in differentiated HL-60 cells by auraptene was also confirmed by flow-cytometric analysis using 2',7'-dichlorofluorescein diacetate as a fluorescence probe. Quantitative analyses using high-performance liquid chromatography showed the occurrence of auraptene not only in both the peels and sarcocarps of natsumikan, but also in those of hassaku orange (C. hassaku) and grapefruit (C. paradisi), and even in their bottled fresh juice form. These results indicate that auraptene is a chemopreventer of skin tumorigenesis, and implies that suppression of leukocyte activation might be the mechanism through which it inhibits tumor promotion.

Reduced expression of cyclin-dependent kinase inhibitor p27Kip1 is associated with advanced stage and invasiveness of gastric carcinomas.

Abstract: Reduced expression of a cyclin-dependent kinase inhibitor p27Kip1 has recently been shown to predict poor survival of patients with breast and colorectal cancers. We studied the expression of p27Kip1 in gastric carcinomas by northern blotting, western blotting and immunohistochemistry to determine whether lack of p27 has implications for aggressiveness of gastric cancer. Reduced expression of p27 was detected in 40% of the gastric carcinomas at the mRNA level, while it was detected in 57% at the protein level. No gross alterations of the p27 gene were observed in any of the cases examined by Southern blot analysis. Immunohistochemical studies revealed that the expression of p27 was well preserved in most of the gastric adenomas, whereas it was so in only 26% of the gastric carcinomas. Fifty-six percent of the carcinomas showed almost no p27-positive cells. Decrease of p27-positive cells significantly correlated with advanced stage, depth of tumor invasion and lymph node metastasis. The expression of p27 showed an inverse correlation with the expression of cyclin E. These findings suggest that reduction of p27Kip1 protein may reflect the progression of gastric carcinomas and may be an indicator of high-grade malignancy.

Infrequent genetic alterations of the PTEN/MMAC1 gene in Japanese patients with primary cancers of the breast, lung, pancreas, kidney, and ovary.

Abstract: In the present study, we searched for genetic alterations of the entire coding region of PTEN/MMACl, a recently isolated candidate tumor suppressor gene, in 178 specimens from Japanese patients with various malignant tumors by the polymerase chain reaction-single strand conformation polymorphism method. The samples consisted of 11 glioblastoma multiformes (GBMs), 14 astrocytomas, 47 breast cancers, 25 non-small cell lung cancers, 9 small cell lung cancers, 8 pancreatic cancers, 24 renal cell carcinomas, 20 ovarian cancers, and 20 metastatic lung tumors from various organs. Only one somatic frameshift mutation at codon 319 was observed in one (9%) of eleven GBMs. Our results suggest that mutation of the PTEN/MMAC1 gene does not play a major role in carcinogenesis, at least in the tumor types from Japanese patients analyzed in this study.

Inhibition of Azoxymethane‐initiated Colon Tumor by Bovine Lactoferrin Administration in F344 Rats

Abstract: The influence of bovine lactoferrin (bLF) on colon carcinogenesis was investigated in male F344 rats treated with azoxymethane (AOM). Following three weekly injections of AOM, the animals received 2 or 0.2% bLF for 36 weeks. No effects indicative of toxicity were noted, but significant reduction in both the incidence and number of adenocarcinomas of the large intestine was observed with both doses. Thus, the incidences of adenocarcinomas in the groups receiving 2% and 0.2% bLF were 15% and 25%, respectively, in contrast to the 57.5% control value (P < 0.01 and P < 0.05, respectively). The results indicate that bLF might find application for chemoprevention of colon cancer.

Antitumor activity of a novel quinoline derivative, TAS-103, with inhibitory effects on topoisomerases I and II

Abstract: A novel quinoline derivative, TAS-103 (6-[[2-(dimethylamino)ethyl]amino]-3-hydroxy-7H-indeno[2,1-c]quinolin -7-one dihydrochloride), was developed as an anticancer agent targeting topoisomerases (topo) I and II, with marked efficacy in solid tumors. TAS-103 inhibited topo I and II (IC50: 2 microM, 6.5 microM) at a concentration similar to or lower than those of previous agents, and had a strong cytotoxic effect on P388 and KB cells (IC50: 0.0011 microM, 0.0096 microM). TAS-103 stabilized topo I and II-DNA cleavable complexes in KB cells, generating a similar amount of topo II-DNA complex to that induced by etoposide (VP-16) but a smaller amount of topo I-DNA complex than that produced by camptothecin (CPT). In the in vivo study, intermittent i.v. administration was markedly effective against s.c.-implanted murine tumors. Furthermore, TAS-103 had marked efficacy against various lung metastatic tumors, and a broad antitumor spectrum in human tumor xenografts (derived from lung, colon, stomach, breast, and pancreatic cancer). The efficacy of TAS-103 was generally greater than that of irinotecan (CPT-11), VP-16, or cis-diamminedichloroplatinum (CDDP).

Apoptosis Induced by NS-398, a Selective Cyclooxygenase-2 Inhibitor, in Human Colorectal Cancer Cell Lines

Abstract: Recent studies have suggested that apoptosis is a key phenomenon in the chemopreventive action of nonsteroidal antiinflammatory drugs (NSAIDs), which exhibit cancer-preventive and tumor-regressive effects in the human colon. The effect of NS-398, N-(2-cyclohexyloxy-4-nitrophenyl)methanesulfonamide, which is a selective inhibitor of cyclooxygenase-2 (COX-2), on the induction of apoptosis in two human colorectal cancer cell lines (Colo320 and THRC) was determined. The apoptotic ratios (-fold vs. control value) of Colo320 in the presence of 100 microM indomethacin and NS-398 were 3.3 +/- 1.5 and 9.0 +/- 0.94, and those of THRC were 2.3 +/- 0.46 and 7.4 +/- 0.87, respectively. The ability of NS-398 to induce apoptosis is greater than that of indomethacin. Both indomethacin and NS-398 reduced the cell proliferation in a concentration-dependent manner. The IC50 values of NS-398 (54.8 +/- 3.6 and 77.2 +/- 4.9 microM) were significantly lower than those of indomethacin (206.3 +/- 43.0 and 180.3 +/- 22.6 microM) at P < 0.01 in Colo320 and THRC cell lines, respectively. These findings suggest that NS-398, a selective inhibitor of COX-2, is a possible candidate for a chemopreventive agent with a potent apoptosis-inducing effect and low ulcerogenic activity.

Antitumor activity of TZT-1027, a novel dolastatin 10 derivative.

Abstract: Dolastatin 10, a pentapeptide isolated from the marine mollusk Dolabella auricularia, has antitumor activity. TZT-1027, a dolastatin 10 derivative, is a newly synthesized antitumor compound. We evaluated its antitumor activity against a variety of transplantable tumors in mice. Intermittent injections of TZT-1027 were more effective than single or repeated injections in mice with P388 leukemia and B16 melanoma. Consequently, TZT-1027 shows schedule dependency. TZT-1027 was effective against P388 leukemia not only when administered i.p., but also when given i.v. However, although TZT-1027 given i.v. was active against murine solid tumors, TZT-1027 administered i.p. was ineffective against all the tumors tested with the exception of colon 26 adenocarcinoma. The i.v. injection of TZT-1027 at a dose of 2.0 mg/kg remarkably inhibited the growth of three murine solid tumors; colon 26 adenocarcinoma, B16 melanoma and M5076 sarcoma, with T/C values of less than 6%. The antitumor activities of TZT-1027 against these tumors were superior or comparable to those of the reference agents; dolastatin 10, cisplatin, vincristine, 5-fluorouracil (5-FU) and E7010. In experiments with drug-resistant P388 leukemia, TZT-1027 showed good activity against cisplatin-resistant P388 and moderate activity against vincristine- and 5-fluorouracil-resistant P388, but no activity against adriamycin-resistant P388. TZT-1027 was also effective against human xenografts, that is, tumor regression was observed in mice bearing MX-1 breast and LX-1 lung carcinomas. TZT-1027 at 10 microM almost completely inhibited the assembly of porcine brain microtubules. Therefore, its mechanism of antitumor action seems to be, at least in part, ascribable to the inhibition of microtubule assembly. Because of its good preclinical activity, TZT-1027 has been entered into phase I clinical trials.

Increased DNA Methyltransferase Expression Is Associated with an Early Stage of Human Hepatocarcinogenesis

Abstract: The present study was designed to determine whether changes in DNA methyltransferase (DNA MTase) expression are involved in hepatocarcinogenesis. We examined DNA MTase expression in normal liver tissue (with no remarkable histological findings), liver tissue showing chronic hepatitis or cirrhosis, which are generally thought to be precancerous conditions, and hepatocellular carcinomas (HCCs) using the reverse-transcriptase polymerase chain reaction assay. DNA MTase mRNA levels were significantly higher in liver tissue showing chronic hepatitis and cirrhosis (DNA MTase mRNA/β-actin mRNA ratio=0.30±0.22, n=24, P<0.01) than in normal liver tissue either from patients with liver metastatic lesions of colonic cancer (0.14±0.05, n= 6) or from patients with HCCs (0.16±0.07, n= 3). DNA MTase mRNA levels were even higher in HCC tissue (0.34±0.18, n=29). These results suggest that increased DNA MTase expression may be an early event during hepatocar-cinogenesis. DNA MTase is a potential target for HCC preventive therapy.

Suppression of intestinal polyp development by nimesulide, a selective cyclooxygenase-2 inhibitor, in Min mice.

Abstract: Nonsteroidal anti-inflammatory drugs (NSAIDs) suppress colon carcinogenesis in man and experimental animals. However, conventional NSAIDs inhibit both cyclooxygenase (COX) isoforms, COX-1 and COX-2, and cause gastrointestinal side-effects. Nimesulide, a selective inhibitor of COX-2, is much less ulcerogenic. We, therefore, examined its influence on the development of intestinal polyps in Min mice. Female Min mice at 4 weeks old were given 400 ppm nimesulide in their diet for 11 weeks. This treatment resulted in a significant reduction of the numbers of both small and large intestinal polyps, the total being 52% of that in untreated control Min mice. The size of the polyps in the nimesulide-treated group was also significantly decreased. The results suggest that nimesulide is a good candidate as a chemopreventive agent for human colon cancer with low toxicity.

Characterization of the Extracellular Domain in Vascular Endothelial Growth Factor Receptor‐1 (Flt‐1 Tyrosine Kinase)

Abstract: Flt-1 tyrosine kinase, vascular endothelial growth factor (VEGF) receptor-1, binds VEGF and a new VEGF-related ligand, placenta growth factor, but KDR/Flk-1 (VEGF receptor-2) binds only VEGF. To characterize the functional regions in the Flt-1 extracellular domain such as the ligand binding region and the dimer formation of the receptor, we constructed a series of mutants of the Flt-1 extracellular domain as soluble forms in a baculovirus system. We found that a region carrying the N-terminal 1st to 3rd immunoglobulin (Ig)-like domains of Flt-1 binds both ligands with high affinity. However, for dimer formation of soluble Flt-1, a region further downstream in the Flt-1 extracellular domain was required. Mutant Flt-1 receptors expressed in COS cells confirmed the requirement of the 4th to 7th Ig region for the activation of Flt-1 tyrosine kinase. Soluble Flt-1 carrying the N-terminal 1st to 3rd Ig region suppressed VEGF-dependent endothelial proliferation in vitro to the same level as the larger forms of soluble Flt-1, suggesting that the binding of one soluble Flt-1 molecule to one subunit of the VEGF homodimer may be sufficient to block the VEGF activity.

Overexpression of Cyclin‐dependent Kinase‐activating CDC25B Phosphatase in Human Gastric Carcinomas

Abstract: CDC25 phosphatases activate cyclin-dependent kinases by removing inhibitory phosphate groups on the molecules and positively regulate the cell cycle progression The expression of CDC25A, B and C was examined in gastric carcinoma cell lines and gastric carcinoma tissues by northern blotting and immunohistochemistry The gastric carcinoma cell lines expressed CDC25A, B and C mRNA at various levels The expression levels of CDC25B were generally higher than those of CDC25A and C Of the 40 gastric carcinomas, 70% of the tumors expressed CDC25B mRNA at higher levels than the corresponding normal mucosas, while 38% overexpressed CDC25A mRNA The CDC25C expression was at very low or undetectable levels No obvious correlation was detected between the expression of CDC25B and p53 gene mutations Immunohistochemically, CDC25-positive tumor cells were detected in 43 (78%) of 55 gastric carcinoma cases, of which 27 (49%) were strongly positive Strong expression of CDC25B protein was associated with advanced stage and deep invasion Furthermore, the incidence of strong expression was significantly higher in carcinomas with nodal metastasis than in those without metastasis These findings suggest that overexpression of CDC25B may favor development and progression and may be an indicator of malignant behavior of gastric carcinomas

Enhancement of tumor radio-response by irinotecan in human lung tumor xenografts.

Abstract: We investigated the ability of 7-ethyl-10-[4-(1-piperidino)-1-piperidino] carbonyloxycamptothecin (CPT-11) to increase tumor radio-response in vivo using human lung tumor xenografts. The xenografts were treated with (1) CPT-11 (10 mg/kg) intraperitoneally on days 1, 5 and 9, (2) single dose radiation (10 Gy/leg) on day 1, or (3) a combination regimen of both treatments in which radiation was given 1 h after the first dose of CPT-11. DNA flow cytometry studies were performed to define the cell cycle changes following treatment for 1 to 12 h with 0, 0.5, 2.0 or 8.0 ng/ml SN-38, the major active metabolite of CPT-11. In both small cell lung cancer (MS-1) and small cell/large cell carcinoma (LX-1) xenografts, combination treatment resulted in significant tumor regression compared with the use of CPT-11 (P = 0.0005, 0.0053) or radiation treatment (P = 0.00221, 0.0035) alone. Neither severe body weight loss nor enhanced skin reaction was observed following the combined treatment. In flow cytometry studies, the proportion of cells in G2/M-phase, the most radio-sensitive phase, increased after 1 h exposure to the lowest dose of SN-38 (0.5 ng/ml). These findings suggest that CPT-11 is a potent radiosensitizing agent, and that its activity is related to the cell cycle. This is the first report to indicate that CPT-11 serves as a radiosensitizer in vivo.

Nitric oxide synthase activity in human lung cancer

Abstract: Nitric oxide synthases (NOS) exist in human tumor cell lines and solid tumor tissues, and it has been suggested that NO may play important roles in growth, progression or metastasis of tumors. We investigated the activity and distribution of NOS in a series of human cancer and normal lung tissues. Seventy-two primary lung cancer samples (44 cases of adenocarcinoma, 18 of squamous cell carcinoma, 4 of large cell carcinoma, 2 of small cell carcinoma, 2 of adenosquamous carcinoma, and 2 of carcinoids) and corresponding normal lung samples were obtained from surgically treated patients. In normal lung tissues, little NOS activity was observed with no correlation between the patient's age and NOS activity. The total NOS activities in lung adenocarcinoma samples were significantly higher than those in other types of lung cancers of normal lung samples (P < 0.05). Analysis by tumor grade of the adenocarcinoma samples revealed no significant difference of NOS activity between grades. TNM classification showed that, although T stage did not correlate with NOS activity, cancer tissues from patients with N2 disease tended to have lower activity than those from patients with NO or N1 disease. Immunohistochemical studies revealed that the intensity of NOS immunoreactivity correlated with NOS activity. These results suggest that NO may play an important role in the metabolism and behavior of lung cancers, especially adenocarcinoma.

Promotion of Rat Hepatocarcinogenesis by Dimethylarsinic Acid: Association with Elevated Ornithine Decarboxylase Activity and Formation of 8‐Hydroxydeoxyguanosine in the Liver

Abstract: Arsenicals are epidemiologically significant chemicals in relation to induction of liver cancer in man. In the present study, we investigated the dose-dependent promotion potential of dimethylarsinic acid (DMAA), a major metabolite of inorganic arsenicals in mammals, in a rat liver carcinogenesis model. In experiment 1, glutathione-S-transferase placental form (GST-P)-positive foci, putative preneoplastic lesions, were employed as endpoints of a liver medium-term bioassay for carcinogens (Ito test). Starting 2 weeks after initiation with diethylnitrosamine, male F344 rats were treated with 0, 25, 50 or 100 ppm of DMAA in the drinking water for 6 weeks. All animals underwent two-thirds partial hepatectomy at week 3 after initiation. Examination of liver sections after termination at 8 weeks revealed dose-dependent increases in the numbers and areas of GST-P-positive foci in DMAA-treated rats as compared with controls. In experiment 2, ornithine decarboxylase activity, which is a biomarker of cell proliferation, was found to be significantly increased in the livers of rats treated with DMAA. In experiment 3, formation of 8-hydroxydeoxyguanosine, which is a marker of oxygen radical-mediated DNA damage, was significantly increased after administration of DMAA. These results indicate that DMAA has the potential to promote rat liver carcinogenesis, possibly via a mechanism involving stimulation of cell proliferation and DNA damage caused by oxygen radicals.

Stromal expression of MMP-9 and urokinase receptor is inversely associated with liver metastasis and with infiltrating growth in human colorectal cancer: a novel approach from immune/inflammatory aspect.

Abstract: MMP-9 (gelatinase B) and urokinase-type plasminogen activator receptor (u-PAR), which are involved in cancer cell invasion and metastasis, are reported to be predominantly expressed by immune/inflammatory cells in human colorectal cancers. To investigate their significance in cancer progression, we morphometrically analyzed the tissue expression of MMP-9 and u-PAR among different stages of colorectal cancer. The numbers of MMP-9- and u-PAR-positive cells along the invasive margin were significantly smaller in cases with liver metastasis than in cases without liver metastasis, and were also smaller in cases with an infiltrating margin than in cases with an expanding margin. Both variables were larger in colon cancer cases with conspicuous lymphocytic infiltration. These results indicated that the degree of tissue expression of MMP-9 and u-PAR by host cells is inversely associated with liver metastasis and an infiltrating growth pattern in human colorectal cancers. Essentially the same results were obtained for the number of macrophages distributed along the invasive margin. We also found that the expression pattern of MMP-9 was similar to that of MMP-8 (polymorphonuclear leukocyte collagenase). These data are consistent with clinicopathologic studies of host cells. Therefore, our data suggest a dual role of MMP-9 and u-PAR expression in colon cancer tissue; i.e., not only are these proteinases cancer-promoting factors, but also they are related to the host defensive mechanism when they are expressed by host cells.

Hypersensitivity to Mosquito Bites Conceals Clonal Lymphoproliferation of Epstein-Barr Viral DNA-positive Natural Killer Cells

Abstract: In order to clarify the relationship between Epstein-Barr (EB) virus and hypersensitivity to mosquito bites (HMB), and to search for the mechanism which induces EB virus-associated lymphoproliferative diseases, we investigated patients with HMB, using hematological, immunological and virological techniques. Among 5 cases of HMB, CD56+ cells had proliferated and CD3+ cells were diminished in 4 cases. Although anti-EB virus antibody titers were not consistent with chronic active EB virus infection, EB viral DNA was detected in the peripheral blood mononuclear cells in all 5 cases. Moreover, EB viral DNA-positive cells had proliferated monoclonally in 4 cases, and hiclonally in 1 case. It was proved that most of the EB viral DNA existed in natural killer (NK) cells through polymerase chain reaction analysis. These findings suggest that the basis of HMB may be clonal lymphoproliferation of EB viral DNA-positive NK cells and this hematological abnormality may induce the characteristic symptoms of HMB. In some cases, the proliferating NK cells can metamorphose into leukemic cells, and hemophagocytic syndrome, which has been assumed to be a complication of HMB, may then occur.

Detection of Carcinoembryonic Antigen-expressing Free Tumor Cells in Peritoneal Washes from Patients with Gastric Carcinoma by Polymerase Chain Reaction

Abstract: Cytological examination of peritoneal washes is a useful predictor of peritoneal recurrence in gastric carcinoma patients. In the present study, even more sensitive detection of free cancer cells could be achieved through amplification of carcinoembryonic antigen (CEA) mRNA by means of the reverse transcriptase-polymerase chain reaction (RT-PCR). CEA was first confirmed to be present in all the gastric cancer cell lines examined, irrespective of the differentiation degree, and absent in blood and mesothelium, indicating the specificity of this approach for detection of carcinoma cells in peritoneal lavage fluid. In sensitivity tests, CEA RT-PCR proved to be capable of detecting 10 carcinoma cells per sample. Peritoneal washes of 15 of 48 gastric carcinoma patients, including all 10 patients with positive cytology results, proved positive for CEA mRNA. None of the 5 patients with benign disease was positive. Moreover, a close association with the depth of cancer invasion was established. The results indicate that the assay is more sensitive for detection of free carcinoma cells in the peritoneal cavity than conventional cytology. This is the first study to suggest the feasibility of the RT-PCR method for prediction of peritoneal recurrence in gastric cancer patients.

Chemoprevention of Azoxymethane‐induced Rat Colon Carcinogenesis by a Xanthine Oxidase Inhibitor, 1′‐Acetoxychavicol Acetate

Abstract: In our studies to find natural compounds with chemopreventive efficacy in foods, using azoxymethane (AOM)‐induced colonic aberrant crypt foci and colonic mucosal cell proliferation as biomarkers, a x an thine oxidase inhibitor, 1′‐acetoxychavicol acetate (ACA), present in the edible plant Languas galanga from Thailand was found to be effective. This study was conducted to test the ability of ACA to inhibit AOM‐induced colon tumorigenesis when it was fed to rats during the initiation or post‐initiation phase. Male F344 rats were given three weekly s.c. injections of AOM (15mg/kg body weight) to induce colonic neoplasms. They were fed diet containing 100 or 500 ppm ACA for 4 weeks, starting one week before the first dosing of AOM (the initiation feeding). The other groups were fed the ACA diet for 34 weeks, starting one week after the last AOM injection (the post‐initiation feeding). At the termination of the study (week 38), AOM had induced 71% incidence of colonic adenocarcinoma (12/17 rats). The initiation feeding with ACA caused significant reduction in the incidence of colon carcinoma (54% inhibition by 100 ppm ACA feeding and 77% inhibition by 500 ppm ACA feeding, P=0.03 and P=0.001, respectively). The post‐initiation feeding with ACA also suppressed the incidence of colonic carcinoma (45% inhibition by 100 ppm ACA feeding and 93% inhibition by 500 ppm ACA feeding, P=0.06 and P=0.00003, respectively). Such inhibition was dose‐dependent and was associated with suppression of proliferation biomarkers, such as ornithine decarboxylase activity in the colonic mucosa, and blood and colonic mucosal polyamine contents. ACA also elevated the activities of phase II enzymes, glutathione S‐transferase (GST) and quinone reductase (QR), in the liver and colon. These results indicate that ACA could inhibit the development of AOM‐induced colon tumorigenesis through its suppression of cell proliferation in the colonic mucosa and its induction of GST and QR. The results confirm our previous finding that ACA feeding effectively suppressed the development of colonic aberrant crypt foci. These findings suggest possible chemopreventive ability of ACA against colon tumorigenesis.

Suppression of nitric oxide production in lipopolysaccharide-stimulated macrophage cells by omega 3 polyunsaturated fatty acids

Abstract: Although nitric oxide (NO) is an important biological mediator, its excessive production in inflammation is thought to be a causative factor for cellular injury and, over the long term, cancer. In the present study, the effects of several fatty acids on NO production in murine macrophage cell line RAW264 cells stimulated with lipopolysaccharide were examined. Suppression of NO production was observed with the omega 3 polyunsaturated fatty acids (PUFAs), docosahexaenoic acid, eicosapentaenoic acid and alpha-linolenic acid, in a dose-dependent fashion. In contrast, no inhibition was observed with omega 6 PUFA (linoleic acid), omega 9 PUFA (oleic acid) or a saturated fatty acid (stearic acid). Western and northern blot analyses suggested that suppression of the induction of inducible NO synthase gene expression is responsible for the inhibition of NO production by omega 3 PUFAs. The inhibitory effect of omega 3 PUFA on NO production in activated macrophages could contribute to their cancer chemopreventive influence.

Germline Mutations of the MEN1 Gene in Japanese Kindred with Multiple Endocrine Neoplasia Type 1

Abstract: Multiple endocrine neoplasia type 1 (MEN1) is an autosotnal dominant familial cancer syndrome. The responsible gene MEN1 has recently been isolated, and its germline mutations have been identified in affected individuals in the United States, Canada and Europe. We screened for MEN1 mutations by direct nucleotide sequencing of all protein-coding regions, and identified five distinct germline mutations in five among six Japanese kindreds with familial MEN1 or familial hyperparathyroidism. The mutations were dispersed across the gene. These findings suggest that, because of the absence of an obvious founder effect, the entire MEN1 gene region should be examined for germline mutations in the probands of MEN1 and related syndromes in Japanese families.

Anti-tumor efficacy of paclitaxel against human lung cancer xenografts.

Abstract: We examined paclitaxel for anti-tumor activity against human lung cancer xenografts in nude mice and compared its efficacy with that of cisplatin, currently a key drug for lung cancer chemotherapy. Five non-small cell lung cancers (A549, NCI-H23, NCI-H226, NCI-H460 and NCI-H522) and 2 small cell lung cancers (DMS114 and DMS273) were chosen for this study, since these cell lines have been well characterized as regards in vitro and in vivo drug sensitivity. These cells were exposed to graded concentrations of paclitaxel (0.1 to 1000 nM) for 48 h. The 50% growth-inhibitory concentrations (GI50) for the cell lines ranged from 4 to 24 nM, which are much lower than the achievable peak plasma concentration of paclitaxel. In the in vivo study, 4 cell lines (A549, NCI-H23, NCI-H460, DMS-273) were grown as subcutaneous tumors xenografts in nude mice. Paclitaxel was given intravenously as consecutive daily injections for 5 days at the doses of 24 and 12 mg/kg/day. Against every xenograft, paclitaxel produced a statistically significant tumor growth inhibition compared to the saline control. Paclitaxel at 24 mg/kg/day was more effective than cisplatin at 3 mg/kg/day with the same dosing schedule as above, although the toxicity of paclitaxel was similar to or rather lower than that of cisplatin, in terms of body weight loss. In addition, paclitaxel showed potent activity against 2 other lung cancer xenografts (NCI-H226 and DMS114). Therefore, paclitaxel showed more effective, wider-spectrum anti-tumor activity than cisplatin in this panel of 6 lung cancer xenografts. These findings support the potential utility of paclitaxel in the treatment of human lung cancer.

Transforming Growth Factor‐β and Hepatocyte Growth Factor Produced by Gastric Fibroblasts Stimulate the Invasiveness of Scirrhous Gastric Cancer Cells

Abstract: Scirrhous gastric carcinoma is characterized by cancer cells that infiltrate rapidly in the stroma with extensive growth of fibroblasts. In the present study, we examined the effect of gastric fibroblasts on the invasiveness of a scirrhous gastric cancer cell line, OCUM-2D, using an invasion assay. Gastric fibroblast-derived conditioned medium (CM) significantly stimulated the invasiveness of OCUM-2D cells, as did transforming growth factor-beta (TGF-beta) and hepatocyte growth factor (HGF). The stimulating activity of gastric fibroblast-derived CM was inhibited significantly by anti-TGF-beta neutralizing antibody or anti-HGF neutralizing antibody. TGF-beta and HGF were detected in the gastric fibroblast-derived CM, and TGF-beta receptor and C-met (HGF receptor) were expressed on OCUM-2D cells. Thus, TGF-beta and HGF produced by gastric fibroblasts appear to affect the invasiveness of scirrhous gastric cancer cells. TGF-beta was also detected in the conditioned medium derived from OCUM-2D cells, though HGF was not. TGF-beta appears to affect the invasiveness of OCUM-2D cells in both paracrine and autocrine fashions.

Expression of Human Telomerase RNA Is an Early Event of Stomach Carcinogenesis

Abstract: Expression of human telomerase RNA (hTR) and telomerase activity in gastric cancer and corresponding non-cancerous mucosa were studied. Telomerase activity was detected in 23 (88%) of 26 carcinoma tissues. Although all tumor specimens and non-cancerous mucosa expressed various levels of hTR, 21 (81%) of 26 cases expressed hTR at a higher level in the tumor than that in the corresponding mucosa. All 8 gastric carcinoma cell lines also expressed hTR at high levels. Nine (35%) of 26 non-cancerous mucosa showed telomerase activity and all of them contained intestinal metaplasia. The incidence of telomerase-positive mucosa in grade 2 intestinal metaplasia was significantly higher than that in grade 0 or grade 1 intestinal metaplasia, whereas hTR overexpression was found in grade 0 or grade 1 intestinal metaplasia as well as grade 2 intestinal metaplasia. The degree of Helicobacter pylori infection increased in parallel with the level of hTR expression and telomerase positivity. These results overall suggest that Helicobacter pylori infection may be a strong trigger for hTR overexpression in intestinal metaplasia, and this may lead to telomerase reactivation.

Inhibitory effects of dietary protocatechuic acid and costunolide on 7,12-dimethylbenz[a]anthracene-induced hamster cheek pouch carcinogenesis.

Abstract: The modifying effects of dietary exposure to two natural products, protocatechuic acid (PCA) and costunolide during the development of neoplasms in oral carcinogenesis initiated with 7,12-dimethylbenz[a]anthracene (DMBA) were investigated in male Syrian golden hamsters. All hamsters except those in the test chemical alone and control groups received DMBA (0.5%) in mineral oil to the right buccal pouch 3 times per week for 4 or 6 weeks. At 13 weeks of age, the groups exposed to DMBA were fed diet containing PCA or costunolide at a dose of 0.2 g/kg diet (200 ppm) for 17 weeks. The other groups consisted of hamsters given mineral oil alone for 6 weeks, or given 200 ppm PCA or costunolide alone, or untreated. All animals were necropsied at the termination of the experiment (week 24). PCA or costunolide significantly decreased the tumor burden (P < 0.001-P < 0.05) and the extent of dysplastic areas (%) (P < 0.001-P < 0.05). PCA significantly decreased the mean number of AgNORs/nucleus (P < 0.05). The BrdUrd-labeling index was reduced by dietary administration of test compounds, though not significantly. These results suggest that PCA and costunolide inhibited hamster buccal pouch carcinogenesis and such inhibition may be related to suppression of cell proliferation in the buccal mucosa. It was also found that telomerase activity expressed in neoplastic and preneoplastic lesions of hamster buccal pouch epithelium after DMBA treatment correlated with the histopathological degree of malignancy.

Inhibitory effects of diallyl disulfide or aspirin on 2-amino-1-methyl-6-phenylimidazo[4,5-b]pyridine-induced mammary carcinogenesis in rats.

Abstract: Modifying effects of diallyl disulfide (DAD), aspirin or DL-alpha-difluoromethylornithine (DFMO) on 2-amino-1-methyl-6-phenylimidazo[4,5-b]pyridine (PhIP)-induced mammary carcinogenesis in SD rats were investigated. A total of 166 female rats, 6 weeks old, were divided into 8 groups. They were fed a high fat diet throughout the experiment. Starting at 7 weeks of age, groups 1-4 were given PhIP (85 mg/kg body weight in corn oil) by gavage 8 times in 10 days, and groups 5-8 were given corn oil alone. For the beginning 4 weeks, groups 2 and 5 were given DAD at 200 ppm in diet. Similarly groups 3 and 6, and groups 4 and 7 were given aspirin (400 ppm) and DFMO (400 ppm), respectively. Mammary carcinomas were only recognized in groups 1-4 at the termination (25 weeks after the start of experiment). Multiplicity (mean number/rat) of neoplasms in group 2 (PhIP+DAD, 0.90/rat) and group 3 (PhIP+aspirin, 1.37/rat) was significantly smaller than that in group 1 (PhIP alone, 2.45/ rat) (P < 0.005 and P < 0.05, respectively). These results indicate that dietary intake of DAD or aspirin during the time corresponding to initiation phase has chemopreventive potential on PhIP-induced mammary carcinogenesis in rats.

Fibrotic Focus in Invasive Ductal Carcinoma of the Breast: A Histopathological Prognostic Parameter for Tumor Recurrence and Tumor Death within Three Years after the Initial Operation

Abstract: We investigated whether the presence of a fibrotic focus (FF) in the primary lesion and in lymph node metastasis is a good predictor of early tumor recurrence or death in patients with invasive ductal carcinoma (IDC). Multivariate relative risk (RR) of tumor recurrence and death according to the presence of FF in the primary tumor was estimated using the Cox proportional hazards regression model with adjustment for other prognostic factors (histologic grade, T classification, nodal status, tumor necrosis, DNA ploidy, c-erbB-2 protein expression, p53 protein expression, and labeling index of proliferating cell nuclear antigen). For the evaluation of the metastatic status in the axillary lymph nodes, RR of multivariate analysis was adjusted for the presence of FF in the metastatic tumor and the number of lymph nodes involved (1-3 and > 3). The presence of FF increased the RR of tumor recurrence significantly for the cases in all stages, and especially for those in stages I and II (RR = 6.9, P < 0.05 and RR = 25.0, P < 0.005, respectively). All cases that died of disease had FF. Among IDCs with FF, 24 cases had FF in lymph node metastasis. Significantly higher RRs of tumor recurrence and death were observed in cases with FF in lymph node metastasis than in those without it (RR = 2.0, P < 0.001 and RR = 5.9, P < 0.05, respectively). It was suggested that the presence of FF is an important predictor of early tumor recurrence or death in patients with IDCs. The presence of FF in lymph node metastatic lesions is also a significant prognostic parameter.