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Biomedical subjects

Susumu Kobayashi

Publications and source records attributed to Susumu Kobayashi.

At least 19 recordsLinked to original sources
PubMed2026

Development and validation of a plasma miRNA-CEA biomarker panel for early detection of lung cancer.

Lung cancer remains a leading cause of cancer-related mortality worldwide, underscoring the critical need for early detection to improve patient outcomes. This study aimed to develop and validate a plasma microRNA biomarker panel for the early detection of non-small cell lung cancer in a Japanese cohort. We enrolled 525 participants, comprising 261 LC cases and 264 non-LC controls, divided into optimization and validation cohorts. A 12-miRNA panel was optimized and further combined with CEA to enhance diagnostic performance. The miRNA-alone model demonstrated robust performance in both the optimization (AUC = 77.0%) and validation cohorts (AUC = 77.9%). Integration with CEA significantly improved accuracy, achieving AUCs of 86.2% in optimization and 84.9% in validation, with particularly high performance in late-stage cancers (AUC = 94.4%) and squamous cell carcinoma (AUC = 90.7%). Sensitivity and specificity thresholds were evaluated, enabling model customization for diverse clinical scenarios. These findings highlight the potential of the miRNA-CEA panel as a minimally invasive tool for early LC detection, especially in non-smoking populations.

Humans↗
PubMed2006

Carba analogs of cyclic phosphatidic acid are selective inhibitors of autotaxin and cancer cell invasion and metastasis.

Autotaxin (ATX, nucleotide pyrophosphate/phosphodiesterase-2) is an autocrine motility factor initially characterized from A2058 melanoma cell-conditioned medium. ATX is known to contribute to cancer cell survival, growth, and invasion. Recently ATX was shown to be responsible for the lysophospholipase D activity that generates lysophosphatidic acid (LPA). Production of LPA is sufficient to explain the effects of ATX on tumor cells. Cyclic phosphatidic acid (cPA) is a naturally occurring analog of LPA in which the sn-2 hydroxy group forms a 5-membered ring with the sn-3 phosphate. Cellular responses to cPA generally oppose those of LPA despite activation of apparently overlapping receptor populations, suggesting that cPA also activates cellular targets distinct from LPA receptors. cPA has previously been shown to inhibit tumor cell invasion in vitro and cancer cell metastasis in vivo. However, the mechanism governing this effect remains unresolved. Here we show that 3-carba analogs of cPA lack significant agonist activity at LPA receptors yet are potent inhibitors of ATX activity, LPA production, and A2058 melanoma cell invasion in vitro and B16F10 melanoma cell metastasis in vivo.

Antineoplastic Agents↗
PubMed2006

The impact of human EGFR kinase domain mutations on lung tumorigenesis and in vivo sensitivity to EGFR-targeted therapies.

To understand the role of human epidermal growth factor receptor (hEGFR) kinase domain mutations in lung tumorigenesis and response to EGFR-targeted therapies, we generated bitransgenic mice with inducible expression in type II pneumocytes of two common hEGFR mutants seen in human lung cancer. Both bitransgenic lines developed lung adenocarcinoma after sustained hEGFR mutant expression, confirming their oncogenic potential. Maintenance of these lung tumors was dependent on continued expression of the EGFR mutants. Treatment with small molecule inhibitors (erlotinib or HKI-272) as well as prolonged treatment with a humanized anti-hEGFR antibody (cetuximab) led to dramatic tumor regression. These data suggest that persistent EGFR signaling is required for tumor maintenance in human lung adenocarcinomas expressing EGFR mutants.

Adenocarcinoma↗
PubMed2006

Absence of the transcription factor CCAAT enhancer binding protein alpha results in loss of myeloid identity in bcr/abl-induced malignancy.

The lineage-determining transcription factor CCAAT enhancer binding protein alpha (C/EBPalpha) is required for myeloid differentiation. Decreased function or expression of C/EBPalpha is often found in human acute myeloid leukemia. However, the precise impact of C/EBPalpha deficiency on the maturation arrest in leukemogenesis is not well understood. To address this question, we used a murine transplantation model of a bcr/abl-induced myeloproliferative disease. The expression of bcr/abl in C/EBPalphapos fetal liver cells led to a chronic myeloid leukemia-like disease. Surprisingly, bcr/abl-expressing C/EBPalpha-/- fetal liver cells failed to induce a myeloid disease in transplanted mice, but caused a fatal, transplantable erythroleukemia instead. Accordingly, increased expression of the transcription factors SCL and GATA-1 in hematopoietic precursor cells of C/EBPalpha-/-R01-EY-11298 ) fetal livers was found. The mechanism for the lineage shift from myeloid to erythroid leukemia was studied in a bcr/abl-positive cell line. Consistent with findings of the transplant model, expression of C/EBPalpha and GATA-1 was inversely correlated. Id1, an inhibitor of erythroid differentiation, was identified as a critical direct target of C/EBPalpha. Down-regulation of Id1 by RNA interference impaired C/EBPalpha-induced granulocytic differentiation. Taken together, our study provides evidence that myeloid lineage identity of malignant hematopoietic progenitor cells requires the residual expression of C/EBPalpha.

Animals↗
PubMed2006

Enantioselective total synthesis of convolutamydines B and E.

[reaction: see text] The first enantioselective total synthesis of convolutamydines B and E has been achieved using our vinylogous Mukaiyama aldol reaction. The synthesis features highly diastereoselective vinylogous Mukaiyama aldol reaction with isatin instead of aldehydes to construct a chiral center of convolutamydines. Additionally, the absolute configuration of natural convolutamydine B has been determined as R by its CD spectrum.

Animals↗
PubMed2006

Anatomical study of the complications of intraoral vertico-sagittal ramus osteotomy.

PURPOSE: The present study was performed to determine the variations in anatomical features of the ramus and the course of the maxillary artery to reduce the risk of injury during intraoral vertico-sagittal ramus osteotomy (IVSRO). MATERIALS AND METHODS: The locations and sizes of anatomical features of the medial aspect of mandibular rami were measured in 94 bilateral sides of 47 dry mandibles as a control group, and the results were compared with 3-dimensional computed tomography images of 44 sides of 22 patients with prognathism. We also dissected 12 sides of 6 mandibles from cadavers in a simulated IVSRO procedure to determine the course of the maxillary artery near the medial aspect of the ramus. RESULTS: In the dry mandibles and patients with prognathism, the mandibular foramen was located slightly posterior to the center of the width of the mandibular ramus, and the lingula tip was located about one third the distance from the sigmoid notch to the inferior border of the ramus. The distance from the lateral margin of the mandibular foramen to the lateral surface of the mandibular ramus ranged from 3.1 to 4.4 mm. However, these distances showed various ranges. In the mandibles from Asian cadavers, the maxillary artery approached close to the ramus and passed lateral to the lower head of the lateral pterygoid muscle. CONCLUSIONS: The position of the mandibular foramen in rami varies among individuals and, therefore, should be confirmed preoperatively on axial CT images. In addition, the maxillary artery approaches close to the medial aspect of the sigmoid notch in many cases. Therefore, the medial aspect from the sigmoid notch should be exposed carefully in the IVSRO procedure to avoid damaging the maxillary artery.

Anthropometry↗
PubMed2006

Preferable operative age of choledochal dilation types to prevent patients with pancreaticobiliary maljunction from developing biliary tract carcinogenesis.

BACKGROUND: Pancreaticobiliary maljunction (PBM), which frequently accompanies choledochal dilation, is a high risk factor for biliary tract (gallbladder, bile duct) carcinoma because of the continuous reflux of pancreatic juice into the biliary tract. The aim of this study was to clarify the preferable operative age in PBM patients for the prevention of biliary tract carcinogenesis, with reference to the dilation types of bile ducts. METHODS: There were 165 PBM patients in total studied, including 92 pediatric patients (< or =15 y) (cystic, 63; spindle-like, 29; nondilation, 0) and 73 adult patients (>15 y) (cystic, 45; spindle-like, 18; nondilation, 10) who underwent operative excision of extrahepatic bile ducts or cholecystectomy. We investigated incidence by age of biliary tract malignancies and the risk according to types of dilation. RESULTS: In the pediatric group, no carcinoma case could be found preoperatively or postoperatively (mean follow-up period, 11.7 y). In the adult group, bile duct carcinomas could be detected in 6 cases of a cystic type (6 of 45; 13.3%) (3 preoperative, 3 postoperative). Among the bile duct carcinoma cases, the youngest patient was a 21-year-old woman who had undergone excision of an extrahepatic bile duct 3 years previously. Gallbladder carcinomas were detected in 16 patients: 3 of 45 cystic (6.7%), 6 of 18 spindle-like (33.3%), and 8 of 10 nondilation (80.0%), in whom the youngest patient was a 41-year-old woman with a spindle-like type. CONCLUSIONS: To prevent biliary tract carcinogenesis in PBM patients, cystic-dilated choledochus should be excised in childhood before the development to a precancerous stage. In spindle-like and nondilation types, cholecystectomy is absolutely necessary in early adulthood before age 40.

Abnormalities, Multiple↗
PubMed2006

Structural relationship of curcumin derivatives binding to the BRCT domain of human DNA polymerase lambda.

We previously reported that phenolic compounds, petasiphenol and curcumin (diferuloylmethane), were a selective inhibitor of DNA polymerase lambda (pol lambda) in vitro. The purpose of this study was to investigate the molecular structural relationship of curcumin and 13 chemically synthesized derivatives of curcumin. The inhibitory effect on pol lambda (full-length, i.e. intact pol lambda including the BRCA1 C- terminal [BRCT] domain) by some derivatives was stronger than that by curcumin, and monoacetylcurcumin (compound 13) was the strongest pol lambda inhibitor of all the compounds tested, achieving 50% inhibition at a concentration of 3.9 microm. The compound did not influence the activities of replicative pols such as alpha, delta, and epsilon. It had no effect on pol beta activity either, although the three-dimensional structure of pol beta is thought to be highly similar to that of pol lambda. Compound 13 did not inhibit the activity of the C-terminal catalytic domain of pol lambda including the pol beta-like core, in which the BRCT motif was deleted from its N-terminal region. MALDI-TOF MS analysis demonstrated that compound 13 bound selectively to the N-terminal domain of pol lambda, but did not bind to the C-terminal region. Based on these results, the pol lambda-inhibitory mechanism of compound 13 is discussed.

Amino Acid Motifs↗
PubMed2005

5-(Hydroxymethyl)-2-furfural: a selective inhibitor of DNA polymerase lambda and terminal deoxynucleotidyltransferase.

5-(Hydroxymethyl)-2-furfural (HMF), a pyrolysate of carbohydrate isolated from instant coffee (Coffea arabica L.), selectively inhibits the activities of mammalian DNA polymerase lambda (pol lambda) and terminal deoxynucleotidyltransferase (TdT) which are family X pols, in vitro. The compound influenced neither the activities of replicative DNA polymerases such as alpha, delta, and epsilon, nor even the activity of pol beta which is from the same family and thought to have a very similar three-dimensional structure to the pol beta-like region of pol lambda. Since parts of HMF such as furan, furfuryl alcohol, and 2-furaldehyde did not influence the activities of any enzymes tested, the substituted form of furan with a hyroxymethyl group and a formyl group might be important for the inhibition of pol lambda and TdT. The inhibitory effect of HMF on intact pol lambda (i.e., residues 1-575), a truncated pol lambda lacking the N-terminal BRCA1 C-terminus domain (133-575, del-1 pol lambda) and another truncated pol lambda lacking the N-terminal proline-rich region (245-575, del-2 pol lambda) was dose-dependent, and 50% inhibition was observed at a concentration of 26.1, 10.3, and 4.6 microM, respectively. The IC(50) value of HMF for TdT was the same as that for del-2 pol lambda (5.5 microM). The HMF-induced inhibition of both pol lambda and TdT activities was competitive with respect to both the DNA template-primer and the dNTP substrate. On the basis of these results, HMF was suggested to bind to the pol beta-like region of pol lambda and TdT.

Animals↗
PubMed2005

Apoptosis-inducing effect of epolactaene derivatives on BALL-1 cells.

Epolactaene, a neuritogenic compound in human neuroblastoma SH-SY5Y, induces apoptosis in a human leukemia B-cell line, BALL-1. The apoptosis-inducing activities of 34 epolactaene derivatives, including those of the newly synthesized alpha-alkyl-alpha,beta-epoxy-gamma-lactam derivative and cyclopropane derivatives, were also tested. The structure-activity relationships of the epolactaene derivatives as an inducer of apoptosis are described. The alpha-acyl-alpha,beta-epoxy-gamma-lactam moiety as well as the hydrophobicity derived from the long alkyl side chain are both important for activity. Compound 1e displayed the strongest activity among all the synthesized compounds with an IC50 value of 0.70 microM.

Apoptosis↗
PubMed2005

Camptothecin binds to a synthetic peptide identified by a T7 phage display screen.

An analysis of non-biotinylated camptothecin (CPT) binding to the C-20-biotinylated CPT binding peptide NSSQSARR was carried out using two methods, quartz-crystal microbalance (QCM) and surface plasmon resonance (SPR). The peptide was immobilized peptide on a sensor chip and showed a dissociation constant (KD) of approximately 0.1 microM against CPT in QCM and SPR experiments.

Amino Acid Sequence↗
PubMed2005

Electrophoretic separation of the synovial fluid proteins in patients with temporomandibular joint disorders.

OBJECTIVE: The present study was performed to characterize the patterns of protein expression in the synovial fluid (SF) of patients with temporomandibular joint disorders (TMD) by electrophoretic fractionation. STUDY DESIGN: Samples of the SF of 26 consecutive patients consisting of 16 with closed locking (CL group) and 10 with osteoarthritis (OA group), as well as 7 asymptomatic control subjects (AS group), were analyzed in the present study. SF samples were obtained from the upper compartment of the temporomandibular joint (TMJ) and equal quantities of SF protein were analyzed by sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE). RESULTS: The mean total protein concentrations in the SF from both of the TMD groups were higher than that in the AS group (1353 microg/mL in the CL group and 2485 microg/mL in the OA group vs 615 microg/mL in the AS group; P < .01). Moreover, the mean total SF protein concentration was higher in the OA group than in the CL group (P < .01). There was a correlation between the total protein concentration in the SF from both patient groups and the degree of expanded joint effusion (P = .003, r = 0.685). Approximately 22 different protein bands with molecular weights ranging from 14 to 700 kd were clearly discernible on electrophoresis. The relative amounts of specific proteins in the SF of the TMD group were also different from those in the AS group (P < .05). The major difference in total protein concentration appeared to be due to the increased abundance of relatively high molecular weight proteins (>140 kd) in the TMD patients as compared to the AS group. CONCLUSIONS: The SF of patients with TMD showed significant quantitative differences in total protein abundance as compared to healthy subjects. Moreover, this protein abundance was correlated strongly with the degree of expanded joint effusion. The major difference in total protein concentration appeared to be due to the increased abundance of relatively high molecular weight polypeptides in the TMD patients as compared to the healthy control subjects. These observations of changes in the pattern of protein expression may help in understanding the etiological factors involved in the pathophysiology of TMD.

Adolescent↗
PubMed2005

Monoacetylcurcumin: a new inhibitor of eukaryotic DNA polymerase lambda and a new ligand for inhibitor-affinity chromatography.

We previously reported that a phenolic compound, curcumin (diferuloylmethane), was a selective inhibitor of DNA polymerase lambda (pol lambda) in vitro [Y. Mizushina, M. Hirota, C. Murakami, T. Ishidoh, S. Kamisuki, N. Shimazaki, M. Takemura, M. Perpelescu, M. Suzuki, H. Yoshida, F. Sugawara, O. Koiwai, K. Sakaguchi, Some anti-chronic inflammatory compounds are DNA polymerase lambda-specific inhibitors, Biochem. Pharmacol. 66 (2003) 1935-1944.]. We also found that monoacetylcurcumin ([1E,4Z,6E]-7-(4''-acetoxy-3''-methoxyphenyl)-5-hydroxy-1-(4'-hydroxy-3'-methoxyphenyl)hepta-1,4,6-trien-3-on), a chemically synthesized derivative of curcumin, was a stronger pol lambda inhibitor than curcumin, achieving 50% inhibition at a concentration of 3.9microM. Monoacetylcurcumin did not influence the activities of replicative pols such as alpha, delta, and epsilon, and showed no effect even on the activity of pol beta, the three-dimensional structure of which is thought to be highly similar to that of pol lambda. The compound-induced inhibition of pol lambda activity was non-competitive with respect to both the DNA template-primer and the dNTP substrate. Monoacetylcurcumin did not inhibit the activity of the C-terminal catalytic domain of pol lambda including the pol beta-like core, in which the BRCT motif was deleted. The compound did not influence the activities of prokaryotic pols or other mammalian DNA metabolizing enzymes such as calf primase of pol alpha, calf terminal deoxynucleotidyl transferase, human telomerase, human immunodeficiency virus type-1 reverse transcriptase, T7 RNA polymerase, T4 polynucleotide kinase, and bovine deoxyribonuclease I. Therefore, we concluded that monoacetylcurcumin is a selective inhibitor of pol lambda and could be used as a chromatographic ligand to purify pol lambda. We then made a monoacetylcurcumin-conjugated column with epoxy-activated Sepharose 6B. In the column, pol lambda of full length was selectively adsorbed and eluted.

Animals↗
PubMed2005

Differential effects of gefitinib and cetuximab on non-small-cell lung cancers bearing epidermal growth factor receptor mutations.

BACKGROUND: Many patients with non-small-cell lung cancer (NSCLC) who achieve radiographic responses to treatment with the epidermal growth factor receptor (EGFR) tyrosine kinase inhibitors gefitinib and erlotinib have somatic mutations in the EGFR tyrosine kinase domain. However, little is known about the efficacy of cetuximab, an antibody against the EGFR extracellular domain, in EGFR mutant NSCLC. METHODS: NSCLC cell lines carrying wild-type EGFR (A549, H441, and H1666) or mutant EGFR (H3255, DFCILU-011, PC-9, and HCC827) were treated with various dilutions of gefitinib or cetuximab relative to maximal achievable serum concentration. Cell growth was analyzed by the MTS assay, with differences between dose-response curves analyzed nonparametrically. Apoptosis was analyzed by propidium iodide staining and immunoblotting for PARP. Phosphorylation of EGFR and the downstream signaling components ERK1/2 and Akt were analyzed by immunoblotting. Statistical tests were two-sided. RESULTS: Growth of NSCLC lines with wild-type EGFR was slightly (A549 and H441) or moderately (H1666) inhibited by gefitinib and cetuximab, and the effects of the two agents were similar. Both agents also induced no (H441) or moderate (H1666) apoptosis in NSCLC cells with wild-type EGFR. By contrast, gefitinib was statistically significantly more effective than cetuximab at inhibiting growth of EGFR mutant cells (H3255: P = .003, DFCILU-011: P = .011, and PC-9: P = .003), and gefitinib-treated EGFR mutant cells had higher levels of apoptosis than cetuximab-treated cells (mean fold increase in apoptosis by 1 microM of gefitinib and 10 microg/mL of cetuximab relative to control, H3255: 8.3 [95% confidence interval {CI} = 4.8 to 11.8] and 2.1 [95% CI = 2.0 to 2.2], respectively, P = .025; DFCILU-011: 5.7 [95% CI = 5.1 to 6.3] and. 0.9 [95% CI = 0.3 to 1.5], respectively, P < .001). Gefitinib treatment decreased EGFR, ERK1/2, and Akt phosphorylation in EGFR mutant cell lines whereas cetuximab had relatively little effect. Both gefitinib and cetuximab inhibited the growth of HCC827 cells, but gefitinib inhibited growth to a greater extent (P = .003). CONCLUSIONS: EGFR mutations in NSCLC cells are associated with sensitivity to gefitinib but not to cetuximab.

Adenocarcinoma↗
PubMed2005

An alternative inhibitor overcomes resistance caused by a mutation of the epidermal growth factor receptor.

Mutations of the epidermal growth factor receptor (EGFR) gene have been identified in non-small cell lung cancer specimens from patients responding to anilinoquinazoline EGFR inhibitors. However, clinical resistance to EGFR inhibitor therapy is commonly observed. Previously, we showed that such resistance can be caused by a second mutation of the EGFR gene, leading to a T790M amino acid change in the EGFR tyrosine kinase domain and also found that CL-387,785, a specific and irreversible anilinoquinazoline EGFR inhibitor, was able to overcome this resistance on the biochemical level. Here, we present the successful establishment of a stable Ba/F3 cell line model system for the study of oncogenic EGFR signaling and the functional consequences of the EGFR T790M resistance mutation. We show the ability of gefitinib to induce growth arrest and apoptosis in cells transfected with wild-type or L858R EGFR, whereas the T790M mutation leads to high-level functional resistance against gefitinib and erlotinib. In addition, CL-387,785 is able to overcome resistance caused by the T790M mutation on a functional level, correlating with effective inhibition of downstream signaling pathways. Similar data was also obtained with the use of the gefitinib-resistant H1975 lung cancer cell line. The systems established by us should prove useful for the large-scale screening of alternative EGFR inhibitor compounds against the T790M or other EGFR mutations. These data also support the notion that clinical investigations of compounds similar to CL-387,785 may be useful as a treatment strategy for patients with resistance to EGFR inhibitor therapy caused by the T790M mutation.

Animals↗
PubMed2005

EGFR mutation and resistance of non-small-cell lung cancer to gefitinib.

Mutations of the epidermal growth factor receptor (EGFR) gene have been identified in specimens from patients with non-small-cell lung cancer who have a response to anilinoquinazoline EGFR inhibitors. Despite the dramatic responses to such inhibitors, most patients ultimately have a relapse. The mechanism of the drug resistance is unknown. Here we report the case of a patient with EGFR-mutant, gefitinib-responsive, advanced non-small-cell lung cancer who had a relapse after two years of complete remission during treatment with gefitinib. The DNA sequence of the EGFR gene in his tumor biopsy specimen at relapse revealed the presence of a second point mutation, resulting in threonine-to-methionine amino acid change at position 790 of EGFR. Structural modeling and biochemical studies showed that this second mutation led to gefitinib resistance.

Aged↗