bluuebunny/crossref_metadata_2025 huggingface dataset:
Heterogeneous Breakpoints on the Immunoglobulin Genes Are Involved in Fusion with the 5′ Region of BCL2 in B‐Cell Tumors
Authors: Yonetani Noboru , Ueda Chiyoko , Akasaka Takashi , Nishikori Momoko , Uchiyama Takashi , Ohno Hitoshi
Published: August 2005

The 5′flanking region of the BCL2 gene (5′‐BCL2) is a breakpoint cluster of rearrangements with immunoglobulin genes (IGs). In contrast to t(14;18)(q32;q21) affecting the 3’region of BCL2, 5′‐BCL2 can fuse to not only the heavy chain gene (IGH), but also two light chain gene (IGL) loci. We report here cloning and sequencing of a total of eleven 5′‐BCL2/IGs junctional areas of B‐cell tumors, which were amplified by long‐distance polymerase chain reaction‐based assays. The breakpoints on 5′‐BCL2 were distributed from 378 to 2312 bp upstream of the translational initiation site and, reflecting the alteration of regulatory sequences of BCL2, 5′‐BCL2/IGs‐positive cells showed markedly higher levels of BCL2 expression than those of t(14;18)‐positive cells. In contrast, the breakpoints on the IGs were variable. Two 5′‐BCL2/IGH and two 5′‐BCL2/IGLK junctions occurred 5’of the joining (J) segments, suggesting operation of an erroneous variable (V)/diversity (D)/J and V/J rearrangement mechanism. However, two other 5′‐BCL2/IGH junctions affected switch regions, and the K‐deleting element, which is located 24 kb downstream of the constant region of IGLK, followed the 5′‐BCL2 in another case. One 5′‐BCL2/IGLK and two 5′‐BCL2/IGLλ junctions involved intronic regions where the normal recombination process does not occur. In the remaining one case, the 5′‐BCL2 fused 3’of a Vλ, gene that was upstream of another Vλ/Jλ complex carrying a non‐producing configuration, indicating that the receptor editing mechanism was likely involved in this rearrangement. Our study revealed heterogeneous anatomy of the 5′‐BCL2/IGs fusion gene leading to transcriptional activation of BCL2, and suggested that the mechanisms underlying the formation of this particular oncogene/IGs recombination are not identical to those of t(14;18).
Involvement of c‐Src in Carcinoma Cell Motility and Metastasis
Authors: Sakamoto Michiie , Takamura Masaaki , Ino Yoshinori , Miura Ayaka , Genda Takuya , Hirohashi Setsuo
Published: August 2005

Carcinoma cells exhibit dysfunction/dysregulation of cell adhesion systems that correlates with their abilities to migrate, invade, and metastasize. Here we show that the tyrosine kinase c‐Src is required for motility and metastasis of two carcinoma cell lines. Adherent KYN‐2 cells having a high level of c‐Src kinase activity become scattered, extend lamellipodia, and exhibit high motility. Expression of a dominant‐negative mutant form of c‐Src caused formation of stress fibers and focal adhesions, and markedly reduced motility. HCT15 cells extended lamellipodia and became scattered in response to lysophosphatidic acid stimulation in parallel with transient activation of c‐Src, which was inhibited by expression of a dominant‐negative mutant form of c‐Src or treatment with a specific Src kinase inhibitor. Furthermore, implantation of dominant‐negative c‐Src trans‐fectants into the peritoneal cavity of SCID mice resulted in reduced peritoneal dissemination compared with control transfectants. These findings indicate that c‐Src activation is critically involved in carcinoma cell migration and metastasis.
Epigenetic Regulation of the KAI1 Metastasis Suppressor Gene in Human Prostate Cancer Cell Lines
Authors: Sekita Nobuyuki , Suzuki Hiroyoshi , Ichikawa Tomohiko , Kito Hiroki , Akakura Koichiro , Igarashi Tatsuo , Nakayama Tsuyoshi , Watanabe Masatoshi , Shiraishi Taizo , Toyota Minoru , Yoshie Osamu , Ito Haruo
Published: August 2005

Expression of the KAI1 gene, a metastasis‐suppressor for prostate cancer, is reduced in all foci of prostatic metastasis. The altered regulatory mechanism is not strongly related to mutations or allelic losses of the KAI1 gene in prostate tumors. Since transcriptional silencing of genes has been found to be caused by epigenetic mechanisms, we have investigated the involvement of this epigenetic regulation of KAI1 expression in prostate cancers. The methylation status of the KAI1 promoter region was examined by restriction‐enzyme digestion and sequencing, after amplifying a 331‐bp fragment in the GC‐rich promoter region from 4 human prostate cancer cell lines treated with bisulfite. The same 4 cell lines were also exposed to various concentrations of the demethylating agent, 5‐aza‐2‐deoxycytidine (5‐AzaC) and/or the histone deacetylase inhibitor, trichostatin A (TSA). To clarify the influence of epigenetic modification on reduced KAI1 mRNA expression in the tumor cells, RT‐PCR and northern‐blot analyses were performed. Bisulfite‐sequencing data showed a few methylated CpG islands in the promoter. RT‐PCR analysis of 5‐AzaC and/or TSA‐treated cells indicated reversal of suppression of KAI1 transcription in two cell lines (PC‐3 and DU‐145), although the expression could not be detected by northern blots. From these results, it is suggested that epigenetic change is not the main mechanism of KAI1 down‐regulation, though there remains a possibility that methylation in a more upstream region might be associated with this regulation.
PI3‐kinase p85α Is a Target Molecule of Proline‐rich Antimicrobial Peptide to Suppress Proliferation of ras‐Transformed Cells
Authors: Tanaka Koji , Fujimoto Yoshinori , Suzuki Masako , Suzuki Yasuaki , Ohtake Takaaki , Saito Hiroyuki , Kohgo Yutaka
Published: August 2005

PR‐39, which is an endogenous antimicrobial peptide, can bind to Src homology 3 domains of the NADPH complex protein p47phox and the signaling adapter protein p!30Cas. Recently, we have reported that PR‐39 gene transduction altered invasive activity and actin structure of human hepatocellular carcinoma cells, suggesting that this peptide affects cellular signaling due to its prolinerich motif. In order to clarify the mechanism of the PR‐39 functions, we transfected the PR‐39 gene into mouse NIH3T3 cells which had already been transformed with human activated k‐ras gene. The PR‐39 gene transfectant showed a reorganization of actin structure and suppression of cell proliferation both in vitro and in vivo. Decreases of MAP (mitogen‐activated protein) kinase activity, cyclin Dl expression and JNK activity were observed in the PR‐39 gene transfectant. Co‐immunoprecipitation analysis revealed that PR‐39 binds to PI3‐kinase p85α, which is a regulatory subunit of PI3‐kinase and one of the effectors by which ras induces cytoskeletal changes and stimulates mitogenesis. The PI3‐kinase activity of the PR‐39 gene transfectant was decreased compared with that of the ras transformant. These results suggest that PR‐39 alters actin structure and cell proliferation rate by binding to PI3‐kinase p85α and suppressing the PI3‐kinase activity.
Close Correlation of 1‐β‐D‐Arabinofuranosylcytosine 5′‐Triphosphate, an Intracellular Active Metabolite, to the Therapeutic Efficacy of N4‐Behenoyl‐1‐β‐D‐arabinofuranosylcytosine Therapy for Acute Myelogenous Leukemia
Authors: Yamauchi Takahiro , Kawai Yasukazu , Goto Nobuyuki , Kishi Shinji , Imamura Shin , Yoshida Akira , Urasaki Yoshimasa , Fukushima Toshihiro , Iwasaki Hiromichi , Tsutani Hiroshi , Masada Mikio , Ueda Takanori
Published: August 2005

N
4‐Behenoyl‐l‐β‐D‐arabinofuranosylcytosine (BHAC), a prodrug of 1‐β ‐D‐arabinofuranosylcy‐tosine, is used effectively for the treatment of leukemia in Japan. BHAC therapy may be more effective if it is delivered in conjunction with monitoring of 1‐β ‐D‐arabinofuranosylcytosine 5′‐tri‐phosphate (ara‐CTP), the intracellular active metabolite of ara‐C derived from BHAC. However, previous monitoring methods for ara‐CTP were insufficiently sensitive. Here, using our new sensitive method, we evaluated the ara‐CTP pharmacokinetics in relation to the therapeutic response in 11 acute myelogenous leukemia patients who received a 2‐h infusion of BHAC (70 mg/m2) in combination remission induction therapy. ara‐CTP could be monitored at levels under 1 μM. BHAC maintained effective levels of plasma ara‐C and intracellular ara‐CTP for a longer time, even compared with historical values of high‐dose ara‐C. The area under the concentration‐time curve of ara‐CTP was significantly greater in the patients with complete remission than in the patients without response. This greater amount of ara‐CTP was attributed to the higher ara‐CTP concentrations achieved in the responding patients. There was no apparent difference of plasma ara‐C pharmacokinetics between the two groups. Thus, for the first tune, the ara‐CTP pharmacokinetics was evaluated in relation to the therapeutic effect of BHAC, and the importance of ara‐CTP was proven. Administration of optimal BHAC therapy may require monitoring of the ara‐CTP pharmacokinetics in each individual patient.
Augmented Adriamycin Sensitivity in Cells Transduced with an Antisense Tumor Necrosis Factor Gene Is Mediated by Caspase‐3 Downstream from Reactive Oxygen Species
Authors: Sasaki Masahiro , Kobayashi Daisuke , Watanabe Naoki
Published: August 2005

While transduction of an antisense tumor necrosis factor (TNF) gene sequence can augment the cytotoxicity of adriamycin (ADM) in human cancer cells, the specific effect of introducing this sequence on the signal transduction pathway leading to cell death remains unclear. In ADM‐resistant pancreatic carcinoma (PANC‐1) cells, both the antioxidant N‐acetyl‐L‐cysteine (NAC) and the caspase‐3 inhibitor acetyl‐L‐aspartyl‐L‐methionyl‐L‐glutaminyl‐L‐aspartyl‐aldehyde (Ac‐DMQD‐CHO) prevented ADM‐induced cytotoxicity. NAC additionally inhibited caspase‐3 activity induced by ADM treatment, while Ac‐DMQD‐CHO showed no suppressive effect on reactive oxygen species (ROS). Stable antisense‐TNF transfectants showed higher ADM sensitivity and greater ADM‐induced ROS production and caspase‐3 activity than mock transfectant or parent cells. These results indicate that increased caspase‐3 activity downstream from ROS production is among the mechanisms by which transduction of the antisense TNF sequence of augments ADM sensitivity of pancreatic carcinoma cells.
Evaluation of the Potential of p‐Boronophenylalaninol as a Boron Carrier in Boron Neutron Capture Therapy, Referring to the Effect on Intratumor Quiescent Cells
Authors: Masunaga Shin‐ichiro , Ono Koji , Kirihata Mitsunori , Takagaki Masao , Sakurai Yoshinori , Kinashi Yuko , Kobayashi Tooru , Nagasawa Hideko , Uto Yoshihiro , Hori Hitoshi
Published: August 2005

C57BL mice bearing EL4 tumors and C3H/He mice bearing SCC VII tumors received 5‐bromo‐2′‐deoxyuridine (BrdU) continuously for 5 days via implanted mini‐osmotic pumps to label all proliferating (P) cells. Three hours after oral administration of l‐p‐boronophenylalanine‐10B (BPA), or 30 min after intraperitoneal injection of sodium borocaptate‐10B (BSH) or l‐p‐boronophenylalaninol (BPA‐ol), a newly developed 10B‐containing α‐amino alcohol, the tumors were irradiated with thermal neutron beams. For the combination with mild temperature hyperthermia (MTH) and/or tirapazamine (TPZ), the tumors were heated at 40°C for 30 min immediately before neutron exposure, and TPZ was intraperitoneally injected 30 min before irradiation. The tumors were then excised, minced and trypsinized. The tumor cell suspensions thus obtained were incubated with cytochalasin‐B (a cytokinesis blocker), and the micronucleus (MN) frequency in cells without BrdU labeling (=quiescent (Q) cells) was determined using immunofluorescence staining for BrdU. Meanwhile, 6 h after irradiation, tumor cell suspensions obtained in the same manner were used for determining the apoptosis frequency in Q cells. The MN and apoptosis frequency in total (P+Q) tumor cells were determined from tumors that were not pretreated with BrdU. Without TPZ or MTH, BPA‐ol increased both frequencies most markedly, especially for total cells. However, as with BPA, the sensitivity difference between total and Q cells was much larger than with BSH. On combined treatment with both MTH and TPZ, this sensitivity difference was markedly reduced, similarly to when BPA was used. MTH increased the 10B uptake of all 10B‐compounds into both tumor cells. BPA‐ol has good potential as a 10B‐carrier in neutron capture therapy, especially when combined with both MTH and TPZ.
Helicobacter pylori Seropositivity among 963 Japanese Brazilians According to Sex, Age, Generation, and Lifestyle Factors
Authors: Ito Lucy S. , Oba Sueli M. , Hamajima Nobuyuki , Marie Suely K. N. , Uno Miyuki , Shinjo Samuel K. , Kino Aya , Lavilla Flávia , Inoue Manami , Tajima Kazuo , Tominaga Suketami
Published: August 2005

Seropositivity of anti–Helicobacter pylori antibody (HP+) was examined among Japanese Brazilians. The study was announced through 18 Japanese community culture associations in São Paulo, Curitiba, Mogi das Cruzes, and Mirandopolis in 2001. Among 969 participants, 963 individuals aged 33–69 years were analyzed. The overall HP+% was 48.1% (95% confidence interval, 44.9–51.3%). There was no difference in HP+% between 399 males and 564 females (49.6% and 47.0%, respectively). The HP+% increased with age; 35.3% for those aged 33–39 years, 46.2% for those aged 40–49 years, 46.5% for those aged 50–59 years, and 56.9% for those aged 60–69 years, but no differences were observed among the generations (Issei, Nisei, and Sansei) for each 10–year age group. Mogi das Cruzes, a rural area, showed a higher HP+%. Length of education was inversely associated with the positivity; the odds ratio (OR) relative to those with eight years or less of schooling was 0.61 (0.42–0.89) for those with 12 years or more. The associations with smoking and alcohol drinking were not significant. Fruit intake was associated with the HP+%; the OR relative to everyday intake was 1.38 (1.05–1.83) for less frequent intake, while intake frequencies of green tea, miso soup, and pickled vegetables (tsukemono) were not. Multivariate analysis including sex, 10–year age group, residence, education, and fruit intake showed that all factors except sex were significant. This is the largest study of HP infection among Japanese Brazilians, and the results indicated a similar pattern of age–specific infection rate to that for Japanese in Japan.
Dietary Protective and Risk Factors for Esophageal and Stomach Cancers in a Low‐epidemic Area for Stomach Cancer in Jiangsu Province, China: Comparison with Those in a High‐epidemic Area
Authors: Takezaki Toshiro , Gao Chang–Ming , Wu Jian‐Zhong , Ding Jian‐Hua , Liu Yian‐Ting , Zhang Yu , Li Su‐Ping , Su Ping , Liu Ti–Kan , Tajima Kazuo
Published: August 2005

Comparative epidemiological studies with ecological and case‐control approaches in high‐ and low‐epidemic areas of China have provided us with much evidence with regard to risk and benefit in the environment. To clarify how dietary factors are involved in esophageal and stomach cancer development, we performed a case‐control study in a low‐epidemic area, and compared the findings with those obtained earlier for a high‐epidemic area for stomach cancer in the same Jiangsu Province, China. We recruited 199 and 187 cases with esophageal and stomach cancers, respectively, and 333 population‐based common controls. Odds ratios (ORs) for esophageal and stomach cancers were calculated with adjustment for potential confounding factors, using an unconditional logistic model. Current and former smoking elevated the OR for esophageal cancer, along with high intake of pickled vegetables and broiled meat, while decreased ORs were observed for frequently consumed raw vegetables and garlic. With regard to stomach cancer, ORs were increased with frequent consumption of salty fish, leftover gruel, and broiled meat, and lowered by snap bean consumption. The present risk factors were common to the previously obtained results in the high‐epidemic area, and similarly distributed in each general population. While more protective factors were observed in the high‐epidemic area, their penetrance was much greater in the low‐epidemic area. The present study thus suggests that frequent vegetable and garlic consumption contributes to low mortality rates for esophageal and stomach cancers in a low‐epidemic area, counteracting similar exposure levels for risk factors as in the high‐epidemic area

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Anticarcinogenic Effect and Enhancement of Metastatic Potential of BALB/c 3T3 Cells by Ginsenoside Rh2
Authors: Tatsuka Masaaki , Maeda Masayo , Ota Takahide
Published: August 2005

It has been reported that ginsenoside Rh2, a purified ginseng saponin with a dammarane skeleton, has anticarcinogenic effects on mammalian cells. To determine the significance of these effects on multistage carcinogenesis, we utilized the BALB/c 3T3 cell system. In an in vitro two–stage neoplas–tic transformation assay, the initiating activity of 3–methylcholanthrene (3–MCA) was suppressed by Rh2 (>lxlO–5M) in both BALB/c 3T3 A31–1–1 cells and the more carcinogen–susceptible variant A31–1–13 cells. The suppressive effects in this concentration range were thought to be caused by suppression of DNA replication via indirect Cdk2 inhibition. On the other hand, the promotion steps of both the target cells were not affected by Rh2 even if the transformation frequency was enhanced by a tumor promoter, 12–O–tetradecanoylphorbol–13–acetate (TPA). To examine the other effects of Rh2 on carcinogenesis, we turned our attention to the metastatic phenotype. Using metastatic src–transformed A31–1–1 cells, we found that Rh2 augmented the metastatic potential in an experimental metastasis assay. These data indicate that Rh2 has diverse effects on the expression of the transformed phenotype in BALB/c 3T3 cells, but support the idea that growth suppression is likely to be a major mechanism of the anticarcinogenic effects of Rh2.
Relationship of the Microvascular Type to the Tumor Size, Arterialization and Dedifferentiation of Human Hepatocellular Carcinoma
Authors: Yamamoto Takatsugu , Hirohashi Kazuhiro , Kaneda Kenji , Ikebe Takashi , Mikami Shinichi , Uenishi Takahiro , Kanazawa Akishige , Takemura Shigekazu , Shuto Taichi , Tanaka Hiromu , Kubo Shoji , Sakurai Masami , Kinoshita Hiroaki
Published: August 2005

Unlike normal liver with the sinusoids, hepatocellular carcinomas (HCCs) possess capillaries. Whether these capillaries derive from the sinusoids remains unclear in human HCCs. This study aimed to examine sinusoidal capillarization in human HCCs and its relationship to the tumor size, arterialization and dedifferentiation. Thirty‐eight HCCs with a diameter of 10–140 mm were pathologically and angiographically examined. By electron microscopy, the microvasculature of tumors was classified into sinusoidal, intermediate and capillary types, which were all negative, partially positive and all positive, respectively, for four parameters, i.e., endothelial defenestration, continuous basement membrane, lack of Kupffer cells, and lack of lipid‐containing hepatic stellate cells. Well‐, moderately and poorly differentiated HCCs displayed sinusoidal/intermediate/capillary types, intermediate/capillary types and only capillary type, respectively, suggesting the transition from the sinusoids to capillaries in well‐differentiated (and probably moderately differentiated) HCCs. Furthermore, well‐differentiated HCCs with a diameter of less than 30 mm often received preferential portal venous blood, while moderately and poorly differentiated ones were all supplied with arterial blood, indicating a relationship between dedifferentiation and arterialization. In contrast, the microvascular type displayed no significant relationship with tumor size or arterialization in well‐differentiated HCCs. The present study has demonstrated that sinusoidal capillarization occurs in human well‐differentiated HCCs and seems to be related to dedifferentiation of parenchymal tumor cells, but not to tumor size or arterialization.
A Potential Use of a Synthetic Retinoid TAC‐101 as an Orally Active Agent That Blocks Angiogenesis in Liver Metastases of Human Stomach Cancer Cells
Authors: Oikawa Tsutomu , Murakami Koji , Sano Masaki , Shibata Jiro , Wierzba Konstanty , Yamada Yuji
Published: August 2005

TAC‐101 (4‐[3,5‐bis(trimethylsilyl)benzamido]benzoic acid) is a novel, synthetic retinoid that is effective against liver metastases of human gastrointestinal cancer cells such as the human stomach carcinoma line AZ‐521 in animal models, and is currently in use in phase I cancer trials. However, the mechanism of its antimetastatic action is still poorly understood. Tumor metastasis depends on angiogenesis, and various retinoids have been found to exhibit antiangiogenic activity. Based on these findings we here examined the antiangiogenic effects of TAC‐101. Oral administration of TAC‐101 (2‐8 mg/kg/day) resulted in a drastic suppression of the AZ‐521 cell‐induced angiogenesis in a mouse dorsal air sac assay system, compared to the vehicle alone. Immunohistochemical analysis with antibody against the endothelial marker CD31 revealed a significant reduction in microvessel density in liver metastases from animals treated with TAC‐101 (8 mg/kg p.o.), compared to liver metastases from the untreated control animals. The ability of TAC‐101 (8 mg/kg p.o.) to prevent experimental liver metastasis of AZ‐521 cells in athymic nude mice was comparable with that of the known angiogenesis inhibitor TNP‐470 (30 mg/kg s.c.). TAC‐101 also affected angiogenesis in chorioallantoic membranes and some functions of endothelial cells associated with angiogenesis, whereas the retinoid failed to suppress AZ‐521 cell proliferation directly. These data suggest that the TAC‐101 is an orally active antiangiogenic agent and that this antiangiogenic property may contribute to its efficacy against liver metastasis of human stomach cancer cells.
Reversal of Multidrug Resistance by Novel Nitrophenyl Pyrones, SNF4435C and D
Authors: Kurosawa Kazuhiko , Takahashi Kosaku , Tsuda Eisuke , Tomida Akihiro , Tsuruo Takashi
Published: August 2005

SNF4435C and D, novel immunosuppressants produced by a strain of Streptomyces spectabilis, were examined for their reversing effects in vitro on various multidrug‐resistant (MDR) tumor cells overexpressing P‐glycoprotein. These two compounds in the range of 3–10 [jM completely reversed the resistance of MDR variant cells, mouse leukemia P388 cells [vincristine (VCR)‐resistant P388/ VCR and adriamycin (ADM)‐resistant P388/ADM], human myelogenous leukemia K562 cells (VCR‐resistant K562/VCR and ADM‐resistant K562/ADM) and human ovarian cancer A2780 cells (ADM‐resistant AD10), against VCR. Both compounds moderately potentiated the sensitivity of the MDR cells to ADM but the reversal was not complete. SNF4435C and D significantly increased the intracellular accumulation of VCR in AD10 cells as potently as verapamil, cyclosporin A (CysA) and FK506, whereas the compounds exerted no effect on the accumulation of VCR in the drug‐sensitive parent cells. Moreover, SNF4435C unproved the chemotherapeutic efficacy of VCR in the treatment of P388/VCR‐bearing mice. When 10 mg/kg SNF4435C was administered intra‐peritoneally to the mice concurrently with 0.2 mg/kg VCR for every 5 days, a treated/control (T/C) value of 143% was obtained. These results suggest that the compounds are useful candidates or tools for MDR modification in cancer chemotherapy.
Decreased Expression of Bcl‐x Protein during Hepatocarcinogenesis Induced Exogenously and Endogenously in Rats
Authors: Hatanaka Yutaka , Nakae Dai , Mutai Mamoru , Hashizume Kaoru , Kamihara Yuki , Kinoshita Noriaki , Tani Yoichi , Danno Gen‐ichi , Ohta Shigeo , Konishi Yoichi , Ashida Hitoshi
Published: August 2005

Dysregulations of apoptosis have been widely recognized as important events in multi‐stage carcinogenesis. Bcl‐x, a member of the Bcl‐2 family, is known to act as a regulator of apoptosis. The present study was conducted to assess the role of altered Bcl‐x protein expression in exogenous and endogenous hepatocarcinogenesis in rats. In the short‐term exogenous models, male Fischer 344 rats, 6 weeks old, were given a single intraperitoneal injection of diethylnitrosamine (DEN) at a dose of 200 mg/kg body weight, partially hepatectomized at the end of week 3, administered phenobarbital at a concentration of 0.05% from the end of week 2 for 6 weeks, and sacrificed. In the livers, glutathione S‐transferase (GST‐P)‐positive, putative preneoplastic lesions were induced, and Bcl‐x protein expression was decreased in 24.7% of such lesions. The incidence of GST‐P‐positive lesions with decreased Bcl‐x increased depending on the size of the lesions; 18.9%, 32.4% and 86.5% in the lesions smaller than 0.03, between 0.03 and 0.3, and larger than 0.3 mm2, respectively. In GST‐P‐positive lesions larger than 0.3 mm2, both apoptosis induction and cell proliferation activity were enhanced when Bcl‐x protein expression was decreased. In the long‐term exogenous models, rats were given 10 mg/kg of DEN, partially hepatectomized 4 h after treatment, administered 0.5 mg/kg of colchicine at the end of days 1 and 3, subjected to a selection procedure, and sacrificed at the end of week 45. Hepatocellular carcinomas were induced with the decreased Bcl‐x protein expression. In the endogenous model, rats were fed a choline‐deficient, l‐amino acid‐defined diet for 16 or 80 weeks and sacrificed. Bcl‐x protein expression was decreased both in GST‐P‐positive lesions and hepatocellular carcinoma. These results suggest that this decrease of Bcl‐x protein might serve as an indicator of the advanced form of preneoplastic lesions, and that this decrease could also be associated with a potential to progress into carcinoma in both exogenous and endogenous hepatocarcinogenesis of rats.
Possible Involvement of Interferon Regulatory Factor 4 (IRF4) in a Clinical Subtype of Adult T‐Cell Leukemia
Authors: Imaizumi Yoshitaka , Kohno Tomoko , Yamada Yasuaki , Ikeda Shuichi , Tanaka Yuetsu , Tomonaga Masao , Matsuyama Toshifumi
Published: August 2005

Interferon regulatory factor (IRF) 4 is the lymphoid‐specific transcription factor that is required for the proliferation of mitogen‐activated T cells. IRF4 has been suggested to be involved in tuniorigenesis because the overexpression of IRF4 caused the transformation of Rat‐1 fibroblasts in vitro. Here, we show that IRF4 is constitutively expressed in adult T‐cell leukemia (ATL)‐derived cell lines, which were infected with human T‐cell leukemia virus type‐I, but hardly expressed the trans‐activator protein, Tax. Similarly, constitutive expression of IRF4 was demonstrated in freshly isolated peripheral blood mononuclear cells (PBMC) from patients with either acute or chronic ATL. However, the high‐level expression of IRF4 was specifically associated with acute ATL. With mitogen‐activated PBMC from healthy donors, cell cycle analyses revealed that the induction of IRF4 occurred prior to cell cycle progression and the cells that had entered the cell cycle were predominantly IRF4‐positive cells. In addition, ectopic expression of IRF4 in Rat‐1 fibroblasts increased the S and G2/M phase population significantly. Taken together, our results indicate that IRF4 is involved in the pathogenesis of ATL through its positive effect on the cell cycle, and that IRF4 can be used as a molecular marker of clinical subtype in ATL.
Eradication of Helicobacter pylori Restores Glutathione S‐Transferase Activity and Glutathione Levels in Antral Mucosa
Authors: van Oijen Arnoud H. A. M. , Verhulst Marie‐Louise , Roelofs Hennie M. J. , Peters Wilbert H. M. , de Boer Wink A. , Jansen Jan B. M. J.
Published: August 2005

Glutathione S‐transferases (GST) and glutathione peroxidases (GPO) are important in detoxification. GST activity in the mucosa of the gastrointestinal tract is inversely correlated with the development of gastrointestinal cancer. Helicobacter pylori (H. pylori) infection has been associated with gastric cancer. We studied GST activity and the substrate glutathione (GSH) in patients with H. pylori‐associated gastritis. GST activity and isoenzyme levels, GPO activity and GSH levels were studied in antral biopsies of 38 H./pyfori‐positive patients, before and after eradication treatment. In 31 patients in whom H. pylori was successfully eradicated, antral GST enzyme activity before therapy was 532 (465–598) nmol/mg protein‐min (mean and 95% confidence interval) and that after therapy was 759 (682–836) nmol/mg protein‐min (P<0.0001). Correspondingly, levels of GST α and GST‐P1 were higher after eradication (P<0.001). GSH concentration significantly increased: 21.2 (16.2–26.2) nmol/mg protein before and 27.1 (23.6–30.6) nmol/mg protein after therapy (P<0.05). In 7 patients in whom H. pylori was not eradicated, GST activity was 671 (520–823) nmol/mg protein min and 599 (348–850) nmol/mg protein before and after treatment respectively (P=0.32). GSH levels were 17.4 (9.0–25.7) nmol/mg protein and 18.2 (9.1–27.3) nmol/mg protein, respectively (P=0.84). No differences in antral GPO enzyme activity, both of selenium (Se)‐dependent and total GPO, before and after successful treatment were found. Eradication of H. pylori infection increases GST activity and GSH levels in antral mucosa. Low GST activity and GSH concentration due to H. pylori infection might play a role in gastric carcinogenesis.
CPT‐11 May Provide Therapeutic Efficacy for Esophageal Squamous Cell Cancer and the Effects Correlate with the Level of DNA Topoisomerase I Protein
Authors: Nakajima Yasuaki , Miyake Satoshi , Nagai Kagami , Kawano Tatsuyuki , Iwai Takehisa
Published: August 2005

CPT‐11 is a potent anti‐cancer drug and a specific inhibitor of DNA topoisomerase I (Topo I). In this study, we aim to evaluate the effects of CPT‐11 on esophageal squamous cell cancers (ESCC) and to determine the correlation between the effects and the levels of Topo I expression. We examined the growth‐inhibitory effect caused by SN‐38, an active metabolite of CPT‐11, in 14 human ESCC cell lines established from 10 primary and 4 metastatic lesions. CPT‐11 was considered effective against 5 cell lines from primary lesions and one from metastatic lesions, and thus may show therapeutic efficacy against both primary and metastatic ESCC tumors. Although Topo I mRNA levels in these 14 ESCC cell lines, as quantitated by northern blot analysis, showed no correlation with the IC50 values, Topo I protein levels, as quantitated by western blot analysis, showed an inverse correlation with the IC50 values. Topo I protein levels could be an indicator of sensitivity to CPT‐11. We also determined Topo I protein levels in 40 ESCC tumors and matched normal mucosae. Thirty‐four tumors showed 1.2‐22.3‐fold increases in Topo I levels. Two patients receiving pre‐operative chemotherapy and one receiving radiotherapy exhibited increased Topo I protein levels in their tumor lesions. It appeared that CPT‐11 could provide selective therapeutic efficacy against ESCC tumors. CPT‐11 may be effective for the treatment of metastatic ESCC tumors and as a second‐line anti‐cancer drug for ESCC.
Smoking and Risk of Premature Death among Middle‐aged Japanese: Ten‐year Follow‐up of the Japan Public Health Center‐based Prospective Study on Cancer and Cardiovascular Diseases (JPHC Study) Cohort I
Authors: Hara Megumi , Sobue Tomotaka , Sasaki Satoshi , Tsugane Shoichiro ,   for the JPHC Study Group
Published: August 2005

To update the evidence on the association between smoking and mortality, we analyzed data from a population‐based prospective study in Japan. In total, 19 950 men and 21 534 women aged 40–59 who reported their smoking history and had no serious disease at baseline survey were followed. During 1990–1999, 1014 men and 500 women died. Smokers were associated with an unhealthy life‐style. Relative risks (RRs) for selected cause of death due to smoking were slightly attenuated by adjusting for possible confounding factors. Age‐ and area‐adjusted RRs of male current smokers compared with never smokers were 1.66 (95% confidence intervals (CI): 1.40, 1.95) for all causes, 1.69 (1.31, 2.18) for all cancers, 1.67 (1.20, 2.34) for all circulatory system disease, and 1.63 (1.24, 2.15) for other causes, while those of females were 2.03 (1.52, 2.73), 2.06 (1.35, 3.15), 2.99 (1.75, 5.11), 1.31 (0.69, 2.51), respectively. After adjusting for multivariate variables, the corresponding RRs of male smokers were 1.55 (1.29, 1.86), 1.61 (1.20, 2.15), 1.41 (0.97, 2.03), and 1.61 (1.17, 2.19), against 1.89 (1.36, 2.62), 1.83 (1.14, 2.95), 2.72 (1.45, 5.07), and 1.39 (0.71, 2.73) for females. Twenty‐two percent of death from all causes, 25% of all cancer, and 17% of all circulatory system disease deaths, could be attributed to cigarette smoking in males, and 5%, 4%, and 11% in females, respectively. Cumulative dose as indicated by pack‐years was clearly associated with cancer death. These findings provided information as to the quantitative risk for premature death due to smoking among middle‐aged Japanese men and women, and showed that the elevated risk was not explained by the unhealthy lifestyle of smokers.
O6‐Methylguanine‐DNA Methyltransferase (MGMT) as a Determinant of Resistance to Camptothecin Derivatives
Authors: Okamoto Ryo , Takano Hiroshi , Okamura Tatsunori , Park Ji‐Seon , Tanimoto Keiji , Sekikawa Takashi , Yamamoto Wataru , Sparreboom Alex , Verweij Jaap , Nishiyama Masahiko
Published: August 2005

The precise mechanisms of resistance to camptothecin (CPT)‐derived DNA topoisomerase (topo I) inhibitors and the determinants remain unclear. We found that a DNA repair protein, O6‐methylguanine‐DNA methyltransferase(MGMT), participated in resistance to irinotecan hydrochloride (CPT‐11), its active metabolite SN‐38, and a novel CPT derivative, DX‐8951f. In 17 human cancer cell lines, MGMT gene expression level closely correlated with sensitivity to the CPT derivatives, and inhibition of MGMT activity by nontoxic 5 μM O6‐benzylguanine augmented the drug activity in relation to the MGMT expression levels in 8 cell lines examined. Transfection of pCR/MGMT‐sense into U‐251MG and pCR/MGMT‐antisense into T98G and HEC‐46 cells revealed that increased MGMT expression decreased the sensitivity to CPT‐11, SN‐38, and DX‐8951f, whereas repressed MGMT expression sensitized cells to the drugs. Western analysis revealed that treatment of MGMT‐expressing T98G cells with the drugs caused a decrease of both MGMT and topo I in a dose‐dependent manner. Although, in the transfectants, MGMT expression did not so closely correlate with the sensitivity to drugs as to nimustine hydrochloride (ACNU), MGMT is probably an important resistance determinant to CPT derivatives, and may play some role in the topo I‐mediated DNA damage and/or the repair process.
Effect of Functional Magnetic Particles on Radiofrequency Capacitive Heating: An in vivo Study
Authors: Shinkai Masashige , Ueda Kousuke , Ohtsu Shinji , Honda Hiroyuki , Kohri Kenjiro , Kobayashi Takeshi
Published: August 2005

Specific heating of magnetic particles in radiofrequency (RF) capacitive hyperthermia and its hyper‐thermic effect were investigated in an in vivo study. Magnetite cationic liposomes (MCLs) were injected into a rat tumor on the femur and 8 MHz‐RF capacitive heating was applied to the rat under‘mild heating’ conditions. Although the input power of RF capacitive heating was low under the same power conditions, the MCLs‐injected tumor was heated over 43°C, whereas it was only heated to 41°C in the case of the rats not injected with MCLs. A necrotic area in the tumor was observed in the heated rats. From the results of histological observation of the removed tissue, the necrotic area in the MCLs‐injected tumor was wider than that in MCLs‐free tumor. Complete tumor suppression was observed in 71% (5/7) of MCLs‐injected rats, and the hyperthermic effect was greatly improved by the MCLs.
Serum Copper/Zinc Superoxide Dismutase (Cu/Zn SOD) and Gastric Cancer Risk: a Case‐Control Study
Authors: Lin Yingsong , Kikuchi Shogo , Obata Yuki , Yagyu Kiyoko ,   Tokyo Research Group on Prevention of Gastric Cancer
Published: August 2005

We conducted a case‐control study to evaluate the association between serum levels of copper/zinc superoxide dismutase (Cu/Zn SOD) and the risk of gastric cancer. Cases were 214 patients who had been diagnosed with gastric cancer and controls were 120 persons who underwent medical checkups. Serum levels of Cu/Zn SOD were determined by enzyme‐linked immunosorbent assay (ELISA). Compared with the lowest quartile, the OR (odds ratio) was 4.54 (95% CI (confidence interval), 1.62–12.66) for the third quartile and 15.75 (95% CI, 5.84–42.46) for the highest quartile. With both early and advanced cancers, as well as with the intestinal and diffuse types, a significant increase in risk was observed with increasing levels of serum Cu/Zn SOD. Our case‐control study showed that serum levels of Cu/Zn SOD were significantly elevated in gastric cancer patients compared with apparently healthy controls, and higher Cu/Zn SOD levels may be associated with an increased risk of gastric cancer.
Lack of a Dose‐response Relationship for Carcinogenicity in the Rat Liver with Low Doses of 2‐Amino‐3,8‐dimethylimidazo[4,5‐f]quinoxaline or N‐Nitrosodiethylamine
Authors: Fukushima Shoji , Wanibuchi Hideki , Morimura Keiichirou , Wei Min , Nakae Dai , Konishi Yoichi , Tsuda Hiroyuki , Uehara Nobuaki , Imaida Katsumi , Shirai Tomoyuki , Tatematsu Masae , Tsukamoto Tetsuya , Hirose Masao , Furukawa Fumio , Wakabayashi Keiji , Totsuka Yukari
Published: August 2005

For a long period, it has been generally considered that carcinogens, particularly genotoxic ones, have no threshold in exerting their potential for cancer induction. However, the non‐threshold theory can be challenged with regard to assessment of cancer risk to humans. Here we show that a food‐derived, genotoxic hepatocarcinogen, 2‐amino‐3,8‐dimethylimidazo[4,5‐f]quinoxaline, forms DNA adducts at low doses, but does not induce glutathione S‐transferase placental form (GST‐P)‐positive foci (considered to be preneoplastic lesions) or 8‐hydroxy‐2′‐deoxyguanosine in rat liver. Moreover a N‐nitroso compound, N‐nitrosodiethylamine, at low doses was also found not to induce GST‐P‐positive foci in rat liver. These results imply that there is a no‐observed effect level for hepatocarcinogenesis by these genotoxic carcinogens.
Synergistic Promoting Effects of Helicobacter pylori Infection and High‐salt Diet on Gastric Carcinogenesis in Mongolian Gerbils
Authors: Nozaki Koji , Shimizu Nobuyuki , Inada Ken‐ichi , Tsukamoto Tetsuya , Inoue Manami , Kumagai Toshiko , Sugiyama Atsushi , Mizoshita Tsutomu , Kaminishi Michio , Tatematsu Masae
Published: August 2005

Helicobacter pylori (Hp) infection and high‐salt diet administration are both considered to be important factors in gastric carcinogenesis in man. To investigate the interaction of these two factors on gastric carcinogenesis, an experimental study of the carcinogenesis model was performed. Mongolian gerbils were treated with 20 ppm of N‐methyl‐N‐nitrosourea (MNU) in their drinking water for alternate weeks for a total of 5 weeks' exposure (groups 1, 2, 3 and 4) or were maintained as controls (groups 5, 6, 7 and 8). At week 11, the animals were inoculated with Hp (groups 1, 2, 5 and 6) or the vehicle alone (groups 3, 4, 7 and 8), and after week 12, animals were fed a 10% high salt diet (groups 1, 3, 5 and 7) or the control diet (groups 2, 4, 6 and 8). At week 50, the incidence of adenocarcinomas in group 1 (32.1%, 6 well‐differentiated, 2 poorly‐differentiated adenocarcinomas, and one signet‐ring cell carcinoma) was significantly higher than in groups 3 (0%) (P<0.005) and 4 (0%) (P<0.01). The incidence of adenocarcinomas in group 2 (11.8%, one well‐differentiated adenocarcinoma, and one signet‐ring cell carcinoma) was also higher than in groups 3 and 4. A high‐salt diet enhanced the effects of Hp infection on gastric carcinogenesis, and these two factors acted synergistically to promote the development of stomach cancers. Moreover, Hp infection promoted gastric carcinomas more than the high‐salt diet.
Frequent Epigenetic Silencing of the p16 Gene in Non‐small Cell Lung Cancers of Tobacco Smokers
Authors: Yanagawa Naoki , Tamura Gen , Oizumi Hiroyuki , Takahashi Nobumasa , Shimazaki Yasuhisa , Motoyama Teiichi
Published: August 2005

Epidemiological studies have demonstrated a causal link between tobacco smoking and lung cancer. We investigated the association between inactivation of the p16 gene and tobacco smoking in 51 non‐small cell lung cancers (NSCLCs). Aberrations of the p16 gene were studied by PCR single‐strand conformation polymorphism analysis, followed by direct sequencing, microsatellite analysis, methylation‐specific PCR, and immunohistochemistry. Mutations were detected in 3.9% (2/51) of the tumors; the tumors carrying mutations were from smokers. The incidences of loss of heterozygosity, homozygous deletion, and promoter methylation in 37 smokers vs. 14 non‐smokers were; 45.9% vs. 28.6%, 16.2% vs. 7.1%, and 35.1% vs. 7.1%, respectively. Among these, only the association between promoter methylation and tobacco smoking was statistically significant (P<0.05). Therefore, epigenetic aberration is considered to be a major causative event in p16 silencing by tobacco smoking. Loss of p16 protein expression was apparent in 49% (25/51) of the tumors, and was associated with tobacco smoking (P<0.05) and with histological type (P<0.05). These findings suggest that tobacco smoking leads to inactivation of the p16 gene mainly through the epigenetic mechanism, ultimately increasing the risk of NSCLC, especially the squamous cell histological type.
Differentially Regulated Genes as Putative Targets of Amplifications at 20q in Ovarian Cancers
Authors: Watanabe Takafumi , Imoto Issei , Katahira Tomoyuki , Hirasawa Akira , Ishiwata Isamu , Emi Mitsuru , Takayama Masaomi , Sato Akira , Inazawa Johji
Published: August 2005

Frequent amplification of DNA at 20q or part of 20q has been demonstrated by comparative genomic hybridization in ovarian cancer (OC), but the genetic target(s) of these amplification events remain unknown. We examined copy‐number changes with respect to six candidate genes, E2F1 (20q11.2), TGIF2 (20q11.2), AIB1 (20q12), PTPN1 (20q13.1), ZNF217 (20q13.2), and BTAK (20q13), and then measured transcription levels of each candidate in 18 OC cell lines. Three distinct cores of amplification were identified: 20q11.2, harboring E2F1 and TGIF2 (region I; 1 of 18 cell lines, 5.6%); 20q13.1, harboring PTPN1 (region II; 5 lines, 27.8%); and 20q13.2, harboring ZNF217 and BTAK (region III; 6 lines, 33.3%). Among the six genes examined, expression levels of PTPN1 and ZNF217 were significantly correlated with absolute copy‐number, and those of PTPN1 and TGIF2 were significantly correlated with copy‐number relative to the centromere of chromosome 20 (20cen). Among 19 primary OCs examined, moreover, we observed amplification of TGIF2, PTPN1 and ZNF217 in five (26.3%), ten (52.6%), and twelve (63.2%) tumors, respectively. Expression levels of PTPN1 and ZNF217 were significantly correlated with their copy‐numbers in those primary OCs. Our results suggest that 20q amplifications in OCs can be extensive and complex, probably due to synergistic or non‐synergistic amplification of separate regions of 20q, involving multiple, independently amplified targets.
Expression of Glycolipids Bearing Lewis Phenotypes in Tissues and Cultured Cells of Human Gynecological Cancers
Authors: Takehara Kyoko , Kubushiro Kaneyuki , Kiguchi Kazushige , Ishiwata Isamu , Tsukazaki Katsumi , Nozawa Shiro , Iwamori Masao
Published: August 2005

Transformation‐associated expression of Leb (Lewis antigen‐b) or LeY in human colorectal carcinomas has been well described. To examine the expression of glycosphingolipids (GSLs) bearing Lewis‐phenotypes in human gynecological carcinoma‐derived cells, we determined the concentrations of all GSLs. Although neither Leb nor LeY was present in HEC‐108 cells established from the poorly differentiated type of endometrial adenocarcinoma, other cell lines from moderately or well‐differentiated types expressed either Leb or LeY, or both, at concentrations of 0.01 to 0.03 μg per mg of dry cells, which comprised 0.3 to 1.3% of the total GSLs. In the cervical and ovarian carcinoma‐derived cell lines, Lewis phenotypes tended to be carried by nLc4Cer, which was accumulated in the cells without sialylation or fucosylation. These results indicated that expression of Leb‐ or LeY‐phenotypes was strongly dependent on the metabolic ability to supply the precursor GSLs. Both Leb and LeY were successfully detected by monoclonal antibody MSN‐1, which was a useful probe for the simultaneous detection of Leb and LeY. On application of MSN‐1, either Leb or LeY was detected in tissues from patients with well‐ and moderately differentiated types of endometrial adenocarcinoma at concentrations of 0.01 to 0.04 μg per mg of dry tissues, but not in the tissues of poorly differentiated type. Normal endometria at the follicular and luteal phases also contained the antigens, but the concentrations and the frequency of antigen expression were lower than those in the well‐ and moderately differentiated types of endometrial adenocarcinoma.
Development of Gene Therapy Using Prostate‐specific Membrane Antigen Promoter/Enhancer with Cre Recombinase/LoxP System for Prostate Cancer Cells under Androgen Ablation Condition
Authors: Ikegami Shusei , Tadakuma Takushi , Suzuki Satoshi , Yoshimura Ichiro , Asano Tomohiko , Hayakawa Masamichi
Published: August 2005

To enhance the efficacy of suicide gene therapy for prostate cancer under androgen deprivation, we designed a promoter system that consists of the prostate‐specific membrane antigen (PSMA) promoter/enhancer (PEPM) and Cre‐loxP DNA recombination system. We constructed two kinds of plasmids. One plasmid contains a Cre recombinase (Cre) under the control of PEPM and the other expresses CMV‐lox‐luciferase/herpes simplex virus thymidine kinase (TK). In PSMA‐positive LNCaP cells, the promoter activity of the PEPM‐Cre plus CMV‐lox‐luciferase demonstrated 800‐fold greater activity compared with that of the PSMA promoter alone. However, no enhancement of the promoter activity was observed in the PSMA‐negative cells. Furthermore, in contrast to prostate specific antigen promoter/enhancer (PP), the promoter activity of PEPM did not decrease when the LNCaP cells were cultured in charcoal‐stripped fetal bovine serum (CFBS). In an in vitro gene therapy model with LNCaP cells, the cell growth inhibition in the presence of ganciclovir (GCV) was more evident in the cells transfected with the PEPM‐Cre plus CMV‐lox‐TK than in the cells with the PP‐TK, and the difference in efficacy between the two plasmids was more remarkable when the cells were maintained in CFBS medium. The therapeutic effect of PEPM‐Cre plus CMV‐lox‐TK was also observed in xenografted LNCaP cells on nude mice when the plasmids were directly injected into tumors and GCV was administered intraperitoneally. These findings indicate that the combination of the PSMA promoter/enhancer and the Cre‐loxP system can enhance the PSMA promoter activity even under androgen ablation conditions and can exert its anti‐tumor effect both in vitro and in vivo.