Biomedical subjects

Masaki Kitajima

Publications and source records attributed to Masaki Kitajima.

246 records · Page 14Linked to original sources

PubMedDate not supplied

TZT-1027 elucidates antitumor activity through direct cytotoxicity and selective blockade of blood supply.

BACKGROUND: TZT-1027 is a newly developed antitumor agent derived from dolastatin 10. MATERIALS AND METHODS: The in vitro activity of TZT-1027 on MCF-7 and R-27 cells was evaluated by MTT assay. TZT-1027 1 mg/kg/week was administered i.v. for 4 weeks into nude mice bearing MCF-7 and R-27. Subsequently, primary cultured cells from xenografts were also used for CD-DST. Two mg of TZT-1027 or 40 mg docetaxel per kg were injected i.v. into nude mice bearing R-27. 0.2% Evans blue was injected to assess the blood flow. RESULTS: TZT-1027 suppressed the in vitro growth of MCF-7 cells, while R-27 cells were resistant to TZT-1027, although its in vivo antitumor activity was remarkable. TZT-1027 blockaded R-27 tumor blood flow immediately after injection; blood flow was not affected by docetaxel. CONCLUSION: TZT-1027 exerts its antitumor activity through direct cytotoxicity against MCF-7 cells and through selective blockade of tumor blood flow against R-27 cells.

Animals↗

PubMedDate not supplied

Thymidylate synthetase (TS) genotype and TS/dihydropyrimidine dehydrogenase mRNA level as an indicator in determining chemosensitivity to 5-fluorouracil in advanced gastric carcinoma.

BACKGROUND: One of the target enzymes of 5-fluorouracil (5-FU) is thymidylate synthetase (TS). The DNA sequence of the TS gene includes either double or triple tandem 28-bp repeats within the promoter region, such that TS genotypes can be classified as homozygous 3R/3R heterozygous 2R/3R or homozygous 2R/2R Several recent studies have shown that TS genotype affects mRNA expression, with 3R/3R homozygotes showing higher TS mRNA expression compared to the other genotypes. PURPOSE: We analyzed the TS genotype and TS and dihydropyrimidine dehydrogenase (DPD) mRNA expression levels in 22 advanced gastric carcinoma patients, and analyzed results with respect to patient 5-FU chemosensitivity, as detected by the tetrazolium-based colorimetric (MTT) assay and survival outcome. PATIENTS AND METHODS: Between September 2001 and April 2002, 22 Japanese patients with advanced gastric carcinoma were evaluated. Informed written consent was obtained from all patients and the study was approved by the ethical committee at our University Hospital Fresh surgical specimens from carcinoma lesions were enzymatically dissociated and incubated with 5-FU at a concentration of 50 microg/ml for 48 hours to determine the inhibition rate as detected by MTT assay. Normal and tumor tissue and peripheral blood samples were collected and stored at -80 degrees C until assay for TS genotype and TS and DPD mRNA level The TS genotype was assessed by PCR assay using peripheral monocytes, since monocyte genotypes represent the genotype of normal and tumor tissues. Quantification of TS and DPD mRNA levels was performed using real-time PCRP Survival outcome was assessed according to the disease-free survival period in cases with similar clinical backgrounds. RESULTS: TS genotyping revealed 19 3R/3R homozygotes and 3 2R/3R heterozygotes. After analysis of normal and tumor tissues, samples from homozygote 3R/3R cases showed higher TS mRNA expression than heterozygote 2R/3R cases, which was statistically significant at p<0.05. We also observed a statistically significant correlation in TS mRNA levels between normal and tumor tissues, while no significant correlation was observed for DPD mRNA levels between normal and tumor tissues. While no relationship between 5-FU chemosensitivity and TS genotype or mRNA expression was observed, cases with high DPD mRNA expression were resistant to 5-FU and exhibited poor survival outcomes. CONCLUSION: While TS genotype affected TS mRNA expression in both normal and tumor tissues in advanced gastric cancer, there is no relationship between TS genotype or mRNA expression level and 5-FU chemosensitivity. CONCLUSION: Our finding, that DPD mRNA expression appears to be a factor in determining 5-FU chemosensitivity and the survival outcome of advanced gastric cancer patients, is comparable with previous reports.

Aged↗

PubMedDate not supplied

Cyclooxygenase-2 gene induction causes CDDP resistance in colon cancer cell line, HCT-15.

Drug resistance to cisplatin (CDDP) would represent a major obstacle for cancer therapy. The adenosine triphosphate (ATP) binding cassette (ABC) family of transport proteins, such as the 170 kDa P-glycoprotein (multidrug resistance gene-1; MDR-1) and the 190 kDa multidrug resistance-associated proteins (MRPs), are associated with multidrug resistance, including resistance to CDDP. The purpose of the present study was to investigate the relationship between cyclooxygenase-2 (COX-2) expression and the level of chemosensitivity to CDDP. We established the COX-2-overexpressed colon cancer cell line TR-5 from HCT-15 cells. We quantified the expression of m-RNA for MRP-1 and MDR-1 by a real-time PCR method, determining that the values of each gene/standardized GAPDH in HCT-15 and TR-5 were 23+/-0.4 and 6.1+/-0.5 in MRP-1 (p<0.02) and 9.0+/-4.8 and 3.6+/-0.5 in MDR-1, respectively. With respect to chemosensitivity, survival rates for 3 microg/ml and 10 microg/ml of CDDP were 81.5+/-12.2% and 26.1+/-11.7% (IC50=6.5 microg/ml) for HCT-15 and 96.6+/-1.7% and 77.4+/-4.9% (IC50=18.5 microg/ml) for TR-5, respectively, thus TR-5 showed higher resistance to CDDP than HCT-15 did with statistical differences. We also demonstrated a successful re-sensitization to CDDP toxicity in TR-5 by means of the COX-2 selective inhibitor JTE-522, 4-(4-cyclohexyl-2-methyl-1, 3-oxazol-5-yl)-2-fluorobenzene sulfonamide, which markedly decreased the IC50 of CDDP for TR-5 (from 17.3+/-2.6 microg/ml to 8.6+/-2.5 microg/ml). In conclusion, COX-2 overexpression induced increased MRP-1 expression in a colon cancer cell line, TR-5, resulting in chemoresistance to CDDP that was approximately triple the level of chemoresistance observed in the original HCT-15 cells line, as measured by calculation of the IC50. We also confirmed the efficacy of pretreatment of TR-5 cells with the COX-2 selective inhibitor JTE-522 in restoring chemosensitivity of these cells to CDDP, suggesting a strategy for overcoming drug resistance to CDDP.

ATP Binding Cassette Transporter, Subfamily B, Mem↗

PubMedDate not supplied

Endoscopic ultrasonography of nonfunctioning pancreatic islet cell tumors with histologic correlation.

BACKGROUND/AIMS: Preoperative differentiation of benign and malignant pancreatic nonfunctioning islet cell tumors remains problematic. The present study aimed to evaluate endoscopic ultrasonography (EUS) features of benign and malignant tumors with histologic correlation. METHODOLOGY: Ten patients with surgically resected nonfunctioning pancreatic islet cell tumors were retrospectively reviewed. RESULTS: EUS demonstrated a homogenous hypoechoic (n=2) or hyperechoic (n=1) mass in the 3 benign tumors. EUS showed a hypoechoic mass with an irregular central hyperechoic portion (n=4), a hyperechoic mass with an irregular central hypoechoic portion (n=1), a cystic mass with a large irregular internal hypoechoic portion (n=1), or a hypoechoic mass within the entire lumen of the main pancreatic duct (MPD) (n=1) in the 7 malignant tumors. Histologically, the irregular central portions of the malignant tumors corresponded to necrosis, hemorrhage, fibrosis with hyalinosis, cystic degeneration, and/or calcification. Complete obstruction of the main pancreatic duct on EUS was observed in the 2 malignant tumors. The echogenicity of the tumors was closely associated with arrangement of tumor cells and quantity of fibrous stroma. CONCLUSIONS: Heterogeneous internal structures and complete obstruction of the main pancreatic duct are considered as important EUS features that are suggestive of malignancy in nonfunctioning pancreatic islet cell tumors.

Adult↗

PubMedDate not supplied

Long-term survival of intrahepatic cholangiocarcinoma with hilar lymph node metastasis and portal vein involvement.

We report the case of a very rare 6-year disease-free survivor of intrahepatic cholangiocarcinoma with hilar lymph node metastasis and portal vein involvement. A 76-year-old female with liver dysfunction was referred to our institution. Contrast-enhanced computed tomography showed a 5-cm low-density tumor with irregular marginal enhancement in the left and caudate lobes of the liver. Cholangiography revealed complete obstruction of the left hepatic bile duct. Angiography showed obstruction of the left branch of the portal vein. Metastasis to the hilar lymph nodes was disclosed at surgery. The patient underwent left hepatectomy with caudate lobectomy, resection of the extrahepatic bile duct, and lymphadenectomy. The total vascular exclusion of the liver was used for hepatectomy and reconstruction of the portal vein. Microscopically, the tumor was a poorly differentiated adenocarcinoma with many infiltrating lymphocytes, and extensive necrosis was present within the tumor. The experience gained in the present case suggests that aggressive surgery may be a potential approach to provide a hope of long-term survival for patients with intrahepatic cholangiocarcinoma despite the presence of regional lymph node metastasis and vascular invasion.

Aged↗

PubMedDate not supplied

Tyrosine kinase inhibitor SU6668 inhibits peritoneal dissemination of gastric cancer via suppression of tumor angiogenesis.

BACKGROUND: Peritoneal dissemination of cancer involves several steps, including tumor cell attachment, invasion and growth in the peritoneum. Tumor angiogenesis is a prerequisite for the growth of disseminated tumor. Vascular endothelial growth factor (VEGF) and its receptor are major regulators of angiogenesis. PURPOSE: We examined the cytotoxic effects of SU6668, an inhibitor of VEGF tyrosine kinase receptors, on in vitro gastric cancer cell lines and human umbilical vascular endothelial cells (HUVEC); we also examined the antitumor effects of SU6668 on human gastric cancer cells administered intraperitoneally into nude mice. MATERIALS AND METHODS: Direct cytotoxicity to gastric cancer cells (TMK-1, MKN-45 and MKN-74) and normal cells (HUVEC) was determined by the MTT assay and the bromodeoxyuridine (BrdU) incorporation assay, with and without VEGF-evoked growth stimulation in vitro. TMK-1 cells were transplanted intraperitoneally into nude mice, followed by twice daily oral administration of SU6668 (200 mg/kg/day) for two weeks starting on the first day after transplantation. Both the number and the wet weight of disseminated peritoneal tumor nodules were assessed. RESULTS: In the MTT assay, SU6668 demonstrated low-grade cytotoxicity to the cell growth of three gastric cancer cells, with a 50% inhibitory concentration (IC50) of 22.6 microg/ml for TMK-1, 31.8 microg/ml for MKN-45 and 26.7 microg/ml for MKN-74; HUVEC was sensitive to SU6668 with an IC50 of 8.9 microg/ml. In the BrdU assay, VEGF stimulated DNA synthesis in HUVEC, while the incorporation of BrdU was not affected by VEGF in gastric cancer cell lines. SU6668 inhibited VEGF-induced DNA synthesis in HUVEC, while BrdU incorporation of gastric cancer cell lines was inhibited by SU6668 without correlation to VEGF stimulation. Peritoneal dissemination of cancer in nude mice was significantly suppressed by SU6668 compared with a control group at the p<0.05 level. CONCLUSION: The mechanism of the antitumor activity of SU6668 may not involve direct toxicity to cancer cells, but may rather be an inhibitory effect on tumor angiogenesis, resulting in the inhibition of tumor dissemination in the peritoneum.

Adult↗

PubMedDate not supplied

The relationship between bone metastasis from human breast cancer and integrin alpha(v)beta3 expression.

BACKGROUND: Osteoclast activation plays an essential role in the development of bone metastasis (BM). Integrin alpha(v)beta3 mediates the attachment of osteoclasts to bone matrix, and it is overexpressed in bone-residing breast cancer cells. We studied BM from breast cancer in relation to its Integrin alpha(v)beta3 expression. MATERIALS AND METHODS: Integrin alpha(v)beta3 expression in 4 human breast cancer cell lines (MDA-MB-231, MDA-MB-435, MKL-4 and T-47D) was determined by immunohistochemistry, flow cytometry and reverse transcriptase-polymerase chain reaction (RT-PCR). RESULTS: Integrin alpha(v)beta3 was expressed in MDA-MB-231 and MDA-MB-435, but not in MKL-4 or T-47D, using both immunohistochemistry and flow cytometry. By RT-PCR, positive bands for both alpha(v) and beta3 subunits were identified in MDA-MB-231 and 435, while only the alpha(v) subunit mRNA was present in MKL-4 and T-47D. BM was common in vivo following inoculation with MDA-MB-231 or 435, but not with MKL-4. CONCLUSION: Integrin alpha(v)beta3 expression appears to play a key role in the development of BM from breast cancer.

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PubMedDate not supplied

A novel human monoclonal antibody derived from tumor-infiltrating lymphocytes in lung cancer inhibits cancer cell growth with morphological changes.

Tumor-infiltrating lymphocytes (TIL) were isolated from surgically resected human samples using hybridoma techniques, and human monoclonal antibodies (HuMoAbs) were produced. Stable antibody-producing hybridoma cell lines were established and, on the basis of reactivity to human cancer cell lines, a clone of HuMoAb, named HoAKs-1, was selected. By confocal microscopy, we confirmed that HoAKs-1 showed specific and intense reactivity to the cell membrane of HLC-1 and PANC-1, wheareas the antibody did not show reactivity to human umbilical vein endothelial cells (HUVECs). Using xenografts formed from epithelial cancer cell lines in nude mice, we also demonstrated a broad spectrum of reactivity of the antibody in 6 out of 14 xenografts. In addition, using surgically resected clinical specimens from two patients with lung cancer, we showed that HoAKs-1 had specific reactivity to cancerous lesions but not to normal sites. In an in vitro experiment, HoAKs-1 induced morphological changes with neurite-like cytoplasmic processes in MKN-45, HLC-1 and PANC-1, whereas no morphological alterations were observed in HUVECs. Growth inhibition rates by HoAKs-1 were 63% in HLC-1 and 47% in MKN-45, while no growth inhibition occurred in normal HUVECs. We confirmed that HoAKs-1 recognized a 55 kDa protein by determining the molecular weight of the HoAKs-1 reacting protein. In conclusion, we successfully produced a novel HuMoAb, HoAKs-1, which reacted specifically to cancer cells and inhibited cell growth with morphological changes. HoAKs-1 may have the potential to be utilized as an anticancer agent, without causing any immunological reaction in humans.

Animals↗

PubMedDate not supplied

Identification of a new breast cancer-related gene by restriction landmark genomic scanning.

BACKGROUND: Molecular genetic analyses have demonstrated the importance of the accumulation of genomic changes in the etiology of cancer and, additionally, have identified valuable genetic markers for certain cancers. Although several prognostic markers have already been identified for breast cancer, it is clear that others remain to be identified. MATERIALS AND METHODS: Fourteen breast cancer samples and non-cancerous counterparts were applied to restriction landmark genomic scanning (RLGS) and 6 breast cancer cell lines (MCF-7, MDA-MB-435, T-47D, MDA-MB-231, SK-BR-3 and BT-20) and 9 cancer tissue samples were applied to reverse transcnptionalpolymerase chain reaction (RT-PCR) for screening of novel genetic alterations. RESULTS: Two spots were identified on the RLGS profiles of cancerous tissue that differed from those of normal tissue. Nucleotide sequencing and homology search analysis showed that these spots represented the voltage-dependent calcium channel alpha1H subunit gene (CACNA1H gene) and a locus immediately downstream of the growth factor receptor-binding protein 7 (GRB7) gene. Expression of the CACNA1H gene was confirmed by RT-PCR. CONCLUSION: Two genes, Grb7 and CACNA1H, were identified by RLGS. The expression of CACNA1H in breast cancer was confirmed for the first time.

Adult↗

PubMedDate not supplied

Mechanisms of the growth-inhibitory effect of the RNase-EGF fused protein against EGFR-overexpressing cells.

BACKGROUND: We previously showed the usefulness of a fused protein of human pancreatic ribonuclease1 (hRNase1) with human epidermal growth factor (hEGF) for molecular targeting of EGF receptor (EGFR)-overexpressing cells. In this study, the mechanisms underlying the inhibition of cell growth by RNase-EGF fused proteins was confirmed. MATERIALS AND METHODS: Des.1-7 hRNase1 was genetically fused to hEGF. The fused proteins were expressed and isolated from Escherichia coli. The internalization of hRNase1-hEGF was confirmed by confocal fluorescence microscopy. The growth-inhibitory effect of the fused proteins was evaluated by MTT assay. RESULTS: FITC-labelled hRNase1-hEGF was internalized into EGFR-overexpressing A431 cells. The internalization was not observed in A431 cells pre-treated with hEGF and EGFR-deficient H69 cells. The growth-inhibitory effect of des.1-7 hRNase1-hEGF against A431 cells was statistically significantly more pronounced than that of hRNase1-hEGF. CONCLUSION: RNase-EGF fused proteins are internalized through EGFR and inhibit cell growth by exerting their ribonucleolytic activity in the cytosol.

Amino Acid Sequence↗

PubMedDate not supplied

Role of the MTT chemosensitivity test in the prognosis of gastric cancer patients after postoperative adjuvant chemotherapy.

The clinical usefulness of the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl tetrazolium bromide (MTT) chemosensitivity test (MTT assay; MTTA) in the selection of anticancer drugs against advanced gastric cancer (AGC) was evaluated. MTTA is widely used to predict patient responses to particular drugs, allowing for the selection of appropriate chemotherapeutic drugs and the avoidance of ineffective chemotherapeutic drugs, thereby improving patient survival. Since 1989, we have accumulated MTTA efficacy data from AGC patients. In this study, the present clinical roles of MTTA and the data from 202 patients with stage III or IV gastric cancer analyzed for survival outcome following surgery, with or without postoperative chemotherapy, evaluated by MTTA, are discussed. The patients were divided into 3 groups; an adapted group found to be sensitive to chemotherapy by MTTA, a non-adapted group found to be insensitive to chemotherapy by MTTA and a group that received no chemotherapy. For stage III gastric cancer patients, the adapted group had a statistically better survival rate compared to the other groups, while for stage IV patients, there was no difference in survival rate between any of the groups. However, further classification of stage IV patients as to the presence or absence of peritoneal dissemination (P) showed that the adapted group with P showed better prognoses than the other groups with P. The analysis of data collected since 2000 revealed that the 11 patients in the taxane-adapted group, who received chemotherapeutic regimens that included taxanes and were found to be sensitive to taxanes by MTTA, demonstrated better survival than the taxane non-adapted group (n=11) (p=0.045). In conclusion, MTTA results predicted patient prognoses, based on the selection of appropriate chemotherapy.

Adult↗

PubMedDate not supplied

A pilot study of combination chemotherapy with S-1 and low-dose cisplatin for highly advanced gastric cancer.

BACKGROUND: The surgical outcome for advanced gastric cancer, even following curative surgery, is associated with a poor prognosis. A pilot study in advanced gastric cancer patients was carried out using pre-operative chemotherapy with S-1 and low-dose cisplatin (CDDP) (TSLD). PATIENTS AND METHODS: Twenty-one patients with stage IV gastric cancer were treated with TSLD as the initial treatment, after informed consent had been obtained. Surgery was performed when curative resection was deemed feasible in selected patients who showed improvement in their tumors. Other regimens including CPT-11 or taxanes were utilized as second-line chemotherapy when the tumor showed no change or progressive disease following TSLD therapy. RESULTS: No patient had a complete response, while 11 had partial responses following TSLD therapy, yielding an overall response rate of 52.4%. Fifteen out of 21 (71.4%) underwent surgery following TSLD therapy, while curative surgery determined by histological investigation was performed in 10 out of 15 (47.6%) patients. No grade 4 toxicities or treatment-related deaths were observed. The following grade 3 toxicities were observed: neutropenia (6 patients), thrombocytopenia (1 patient) and anemia (1 patient). The other toxicities observed, including gastrointestinal toxicity, were grade 2 or less. The median survival time of all patients was 526 days, and 1- and 2-year survival rates were 64.9% and 41.7%, respectively. CONCLUSION: TSLD is a potent regimen with a low toxicity profile for highly advanced gastric cancer.

Adult↗