Correlation of MAP kinases with COX-2 induction differs between MKN45 and HT29 cells.

BACKGROUND: Mitogen-activated protein (MAP) kinases, including extracellular signal-regulated kinases (ERK),c-Jun NH2-terminal kinases (JNK) and p38 MAP kinase (p38 MAPK) are important intermediates of the signal-transduction pathway from the cell surface to the nucleus. Expression of cyclooxygenase (COX)-2, associated with proliferation, apoptosis or both of gastrointestinal cancer cells, is mediated through MAP kinase families. However, the correlation between respective MAP kinase signals and COX-2 in the proliferation of gastric and colon cancer cells has not been well elucidated. AIM: We examined the effect of selective inhibitors of MAP kinases and COX-2 on serum-induced proliferation of gastric (MKN45) and colon (HT29) cancer cells. METHODS: After 24-h serum starvation, cancer cells were stimulated with 2% serum and COX-2 inhibitors (NS398 10 micromol/L, or etodolac 100 micromol/L) or 1 h after preincubation with inhibitors for ERK (PD98059 20 micromol/L) or p38 MAPK (SB203580 10 micromol/L). Phosphorylated MAP kinases and COX-2 protein were evaluated by Western blotting, and the proliferation of cancer cells was estimated by 3H-thymidine incorporation. Transcription factors nuclear factor-kappaB and CREB were assayed by an electorophoretic mobility shift assay. RESULTS: Serum increased the proliferation of MKN45 and HT29 cells by 280% and 200%, respectively, compared with the control levels (100%). In both cancer cells, phosphorylated MAP kinases were increased within 30 min after stimulation. PD98059 and SB203580 inhibited the serum-induced proliferation of MKN45 by 21% and 51% and of HT29 by 81% and 69%, respectively. NS398 and etodolac inhibited the proliferation of HT29 by 21% and 41%, respectively, but not that of MKN45. PD98059 and SB203580 also suppressed serum-induced expression of COX-2 protein in HT29 cells. In addition to the activation of MAP kinases and COX-2, activities of nuclear factor-kappaB and CREB were also increased during HT29 cell proliferation. CONCLUSIONS: These results suggest that the correlation of MAP kinases with COX-2 induction for cell proliferation differs between MKN45 and HT29 cells.

Dominant-negative mutant of c-Jun gene transfer: a novel therapeutic strategy for colorectal cancer.

Activator protein-1 (AP-1), a transcription factor, is activated through many oncogenic signals. However, its biological role in colorectal cancer has not been fully elucidated. To investigate the role of AP-1 in colorectal cancer, we constructed an adenovirus-expressing TAM67, a dominant-negative mutant of c-Jun lacking the transactivation domain of wild c-Jun (DN-c-Jun), to inhibit endogenous AP-1. AP-1 DNA-binding activity was increased in colon cancer cells (HT-29 cells) by serum stimulation, followed by an increase in both [(3)H]thymidine incorporation and cell number. Transfection of Ad-DN-c-Jun to HT-29 cells significantly inhibited serum-induced cell proliferation in vitro. As shown by flow cytometric analysis, DN-c-Jun significantly inhibited entrance into S phase after serum stimulation, thereby leading to G(1) arrest. In vivo transfection of Ad-DN-c-Jun into xenografted HT-29 cell tumors in nude mice significantly decreased tumor volume on day 21 after treatment. A change was associated with decrease in Ki-67 labeling index. These observations together showed that AP-1 is a critical modulator for proliferation and cell cycle of HT-29 cells. We obtained the first evidence that DN-c-Jun gene transfer exerted a significant antitumor effect on colon cancer both in vitro and in vivo. DN-c-Jun gene transfer may be a new candidate for treatment of colorectal cancer.

Structure of the yeast nucleosome core particle reveals fundamental changes in internucleosome interactions.

Chromatin is composed of nucleosomes, the universally repeating protein-DNA complex in eukaryotic cells. The crystal structure of the nucleosome core particle from Saccharomyces cerevisiae reveals that the structure and function of this fundamental complex is conserved between single-cell organisms and metazoans. Our results show that yeast nucleosomes are likely to be subtly destabilized as compared with nucleosomes from higher eukaryotes, consistent with the idea that much of the yeast genome remains constitutively open during much of its life cycle. Importantly, minor sequence variations lead to dramatic changes in the way in which nucleosomes pack against each other within the crystal lattice. This has important implications for our understanding of the formation of higher order chromatin structure and its modulation by post-translational modifications. Finally, the yeast nucleosome core particle provides a structural context by which to interpret genetic data obtained from yeast. Coordinates have been deposited with the Protein Data Bank under accession number 1ID3.

A second primary esophageal cancer developing 7 years after chemoradiotherapy for advanced esophageal cancer.

We report a rare case of advanced carcinoma and a second primary carcinoma of the esophagus, both of which were successfully cured by chemotherapy and operation at different times. In 1991, a 38-year-old Japanese man was diagnosed with advanced esophageal cancer, which was unresectable because of the bronchial invasion of the tumor. He was given chemotherapy with cisplatin (CDDP), combined with radiotherapy. During a 4-year follow-up, neither regrowth of the primary tumor nor distant metastasis occurred. In 1995, esophagoscopy demonstrated a lugol-unstained region located 3 cm distal from the area of radiation to the primary lesion shown by esophagography. Histological examination of a biopsy specimen showed the mucosa to be normal. Nevertheless, yearly surveillance by endoscopy and histological examinations showed that the mucosa of the esophagus gradually began to demonstrate mild dysplasia, followed by severe dysplasia; in 1998, a diagnosis of squamous cell carcinoma was made. Esophagectomy with lymph node dissection was performed. Microscopic examination revealed that there had been pathologic complete response for the original advanced esophageal cancer.

Sequence-specific recognition of DNA in the nucleosome by pyrrole-imidazole polyamides.

The ability of DNA-binding proteins to recognize their cognate sites in chromatin is restricted by the structure and dynamics of nucleosomal DNA, and by the translational and rotational positioning of the histone octamer. Here, we use six different pyrrole-imidazole polyamides as sequence-specific molecular probes for DNA accessibility in nucleosomes. We show that sites on nucleosomal DNA facing away from the histone octamer, or even partially facing the histone octamer, are fully accessible and that nucleosomes remain fully folded upon ligand binding. Polyamides only failed to bind where sites are completely blocked by interactions with the histone octamer. Removal of the amino-terminal tails of either histone H3 or histone H4 allowed these polyamides to bind. These results demonstrate that much of the DNA in the nucleosome is freely accessible for molecular recognition in the minor groove, and also support a role for the amino-terminal tails of H3 and H4 in modulating accessibility of nucleosomal DNA.

Synthesis, characterization, solution stability, and X-ray crystal structure of the thiolatocobalamin gamma-glutamylcysteinylcobalamin, a dipeptide analogue of glutathionylcobalamin: insights into the enhanced Co-S bond stability of the natural product glutathionylcobalamin.

Glutathionylcobalamin (gamma-glutamylcysteinylglycinylcobalamin; gamma-GluCysGly-Cbl) is a natural product which functions as an intermediate in the biosynthesis of the active B(12) coenzymes adenosylcobalamin and methylcobalamin. Of interest to the present studies is glutathionylcobalamin's unique stability in comparison to other thiolatocobalamins, notably the > or =6 x 10(4) fold less stable cysteinylcobalamin, Cys-Cbl. In order to determine which parts of the glutathione tripeptide contribute to the overall stability of glutathionylcobalamin, two cysteine-containing dipeptides, which are truncated versions of glutathione, were used to synthesize their corresponding cobalamins, specifically gamma-glutamylcysteinylCbl (gamma-GluCys-Cbl) and cysteinylglycinylcobalamin (CysGly-Cbl). As with glutathionylCbl, the dipeptide gamma-GluCys-Cbl forms a stable thiolatocobalamin. However and most interestingly, CysGly-Cbl is observed to be unstable much like Cys-Cbl. The results require that the extra stability of glutathionylcobalamin and its congeners, compared to cysteinylcobalamin and its analogues, must be derived from destabilization by the gamma-NH(3)(+) group in cysteinylcobalamin, or stabilization by the gamma-NHC(=O)- amide linkage in glutathionylcobalamin, or both. To probe any ground-state structural basis for the possible stabilization in gamma-GluCys-containing cobalamins, gamma-GluCys-Cbl was crystallized and yielded the first X-ray structural determination of a true thiolatocobalamin, and only the second structure of a cobalamin containing a Co-S bond, the first example being Randaccio and co-workers' 1999 structure of the thioketone complex, thioureacobalamin, (NH(2))(2)CSCbl. Key features of the structure of gamma-glutamylcysteinylcobalamin include (i) a normal Co-S bond length of 2.267(2) A, (ii) a Co-N(axial) bond length of 2.049(6) A, (iii) two alternate conformations of the gamma-glutamylcysteinyl moiety, and (iv) folding of the corrin ring upward by 24.2 degrees, the highest degree of folding yet observed for a cobalamin. These results do not show any strong stabilization (e.g., no shortened Co-S bond), although it is not clear for certain what the effect is (stabilizing or destabilizing) of the elongated Co-N(axial) bond; instead, the crystallographic results suggest that the metastable Cys-Cbl probably has a Co-S cleavage transition state that is stabilized (along with, possibly, any ground-state destabilization of the Co-S bond). Overall, the results strongly suggest that placing a positive charge on the gamma-NH(3)(+) stabilizes the Co-S bond cleavage transition state, thereby setting the stage for the needed full thermolysis product and kinetic studies-as a function of the axial-base on-off equilibrium-that will be required to understand in even greater detail the unique stability of glutathionyl- (gamma-glutamylcysteinylglycinyl-) and gamma-glutamylcysteinylcobalamins.

Crystal structure of a nucleosome core particle containing the variant histone H2A.Z.

Activation of transcription within chromatin has been correlated with the incorporation of the essential histone variant H2A.Z into nucleosomes. H2A.Z and other histone variants may establish structurally distinct chromosomal domains; however, the molecular mechanism by which they function is largely unknown. Here we report the 2.6 A crystal structure of a nucleosome core particle containing the histone variant H2A.Z. The overall structure is similar to that of the previously reported 2.8 A nucleosome structure containing major histone proteins. However, distinct localized changes result in the subtle destabilization of the interaction between the (H2A.Z-H2B) dimer and the (H3-H4)(2) tetramer. Moreover, H2A.Z nucleosomes have an altered surface that includes a metal ion. This altered surface may lead to changes in higher order structure, and/or could result in the association of specific nuclear proteins with H2A.Z. Finally, incorporation of H2A.Z and H2A within the same nucleosome is unlikely, due to significant changes in the interface between the two H2A.Z-H2B dimers.

Necrotic but not apoptotic cell death releases heat shock proteins, which deliver a partial maturation signal to dendritic cells and activate the NF-kappa B pathway.

Dendritic cells (DC) are key components of innate and adaptive immune responses. The identity of endogenous signals that activate DC is a crucial and unresolved question. We report here that heat shock proteins (HSP), the most abundant and conserved mammalian molecules, constitute such an internal signal. Necrotic but not apoptotic cell death leads to release of HSP gp96, calreticulin, hsp90 and hsp70. HSP stimulate macrophages to secrete cytokines, and induce expression of antigen-presenting and co-stimulatory molecules on the DC. The HSP gp96 and hsp70 act differentially, and each induces some but not all molecules. HSP interact with these antigen-presenting cells through the highly conserved NF-kappa B pathway. As HSP are intracellular, abundant and soluble, their presence in the extra-cellular milieu and the consequent activation of antigen-presenting cells (APC) constitutes an excellent mechanism for response to cell death. As HSP are conserved from bacteria to mammals, the ability of HSP to activate APC provides a unified mechanism for response to internal and external stimuli.

Cell-retained isoforms of vascular endothelial growth factor (VEGF) are correlated with poor prognosis in osteosarcoma.

Vascular endothelial growth factor (VEGF) is a major angiogenic factor. Osteosarcoma is characterised by hypervascularity and metastatic potential. We examined VEGF mRNA expression, VEGF isoform pattern and VEGF receptor (flt-1 and KDR) by RT-PCR analysis in 30 osteosarcomas. All 30 osteosarcomas expressed VEGF mRNA. 17 osteosarcomas (57%) expressed flt-1 mRNA, whilst 20 (67%) expressed KDR mRNA. 6/30 (20%) osteosarcomas were positive for VEGF121 only, 8 (27%) for VEGF121 + VEGF165, and 16 (53%) for VEGF121 + VEGF165 + VEGF189. Patients with osteosarcomas with VEGF165 (n = 24) had significantly poorer prognosis in comparison with those without VEGF165 (P = 0.022, Wilcoxon's test). The osteosarcomas with VEGF165 had significantly increased vascularity assessed on sections immunostained for CD34 (P < 0.001, Mann-Whitney U test). Although VEGF165 is a soluble isoform, it is also retained on the cellular surface. These results suggest that cell-retained VEGF isoforms (VEGF165, VEGF189) might be essential for neovascularisation in osteosarcoma, whilst the soluble VEGF121 isoform is not sufficient to stimulate neovascularisation in this type of neoplasm.

Adenosylcobalamin-dependent ribonucleoside triphosphate reductase from Lactobacillus leichmannii. Rapid, improved purification involving dGTP-based affinity chromatography plus biophysical characterization studies demonstrating enhanced, "crystallographic level" purity.

Ribonucleoside triphosphate reductase (RTPR, EC 1.17.4.2) from Lactobacillus leichmannii is a 5'-deoxyadenosylcobalamin-dependent (AdoCbl; Coenzyme B12) enzyme. RTPR is also a prototypical adenosylcobalamin-dependent ribonucleotide reductase, one that, as its name indicates, converts ribonucleoside triphosphates (NTP) to deoxyribonucleoside triphosphates (dNTP). Upon substrate binding to RTPR, AdoCbl's cobalt-carbon bond is cleaved to generate cob(II)alamin, 5'-deoxyadenosine, and the cysteine (C408) derived thiyl radical. Five key cysteines (Cys 119, 408, 419, 731, and 736), from among the ten total cysteines, are involved in RTPR's catalytic mechanism. A critical examination of the RTPR isolation and purification literature suggested that the purification protocol currently used results in RTPR which contains 2040% microheterogeneity, along with minor contamination by other proteins. In addition, no report of crystalline RTPR has ever appeared. The literature indicates that irreversible cysteine oxidation (e.g., to -SO2H or -SO3H) is one highly plausible reason for the microheterogeneity of RTPR. The literature also indicates that improvement in the level of enzyme purity is the most effective next step in coaxing enzymes to crystallize that have previously failed to do so. A shortened, improved purification of RTPR has been developed, one involving a shorter purification time, a lower pH, a higher concentration of the more effective reductant DTT (all designed to help protect the cysteines from oxidation), and a final step utilizing our recently reported, improved dGTP-based affinity chromatography resin. The resultant RTPR is approximately 20-30% higher in both specific activity and in its ability to undergo single turnovers, and is homogeneous by mass spectrometry and dynamic light scattering. Additionally, the revised purification procedure eliminates > 30 proteins present in 2-3% amounts along with damaged RTPR that does not bind properly (i.e. tightly) to the dGTP-affinity resin. Finally, dGTP-based affinity chromatography purified RTPR has yielded the first reported, albeit small, single crystals of RTPR.

Surgery for abdominal aortic aneurysms associated with malignancy.

Of 148 patients treated for abdominal aortic aneurysms (AAA), 33 (22%) also had cancer. According to the classification of Szilagyi, there were 13 patients in group I, 19 in group II, and 1 in group IV. In group I, the mean interval between the cancer and AAA operations was 7 years (range 1-14 years). Aneurysmectomy was performed in 9 patients, wrapping in 2, and no operation in 2. In group II, a two-stage operation was performed in 8 patients, a single-stage operation in 4, only surgery for cancer in 4, and no operation in 3. Of 4 patients undergoing single-stage operations, 3 had colorectal cancer, and there were no postoperative complications such as graft infection or anastomotic breakdown. In group I, 6 of 13 patients died, but there were no cancer deaths. In group II, 9 of 19 patients died, 6 from progressive cancer. The group IV patient also died of cancer. These results suggest that if a patient can tolerate surgery for both diseases, a single-stage operation is preferable.

Synthesis of gamma-phosphate-linked nucleoside affinity chromatography resins for protein purification, including ribonucleoside triphosphate reductase.

Seven nucleotides linked through the gamma-phosphate to diamine hydrocarbons were synthesized and coupled to Sepharose for use in protein purification affinity chromatography. The synthesis involved converting the nucleotides to nucleoside-5'- trimetaphosphates using dicyclohexyl carbodiimide, followed by nucleophilic ring opening of the trimetaphosphate with an alpha, omega-diamino hydrocarbon to generate a gamma-phosphoamide linkage in each nucleotide.

Multidrug resistance mediated by overexpression of P-glycoprotein in human osteosarcoma in vivo.

We examined the expression levels of P-glycoprotein (P-Gp)/the human multidrug resistance gene (MDR1) and in vivo chemosensitivity in the 7 osteosarcoma xenografts. Three of seven (43%) osteosarcoma xenografts expressed MDR1 by reverse transcriptase-polymerase chain reaction (RT-PCR). The OSS-516R xenograft selected with vincristine (VCR) from the MDR1-negative xenograft OSS-516, which was sensitive to VCR and doxorubicin (DOX), acquired cross-resistance to DOX. In the OSS-516R, RT-PCR assay showed definite MDR1 expression and immunohistochemical analysis demonstrated P-Gp-positive tumor cells. These results suggest that P-Gp/MDR1 overexpression is related to multidrug resistance in human osteosarcoma in vivo.

Heat shock protein-peptide complexes, reconstituted in vitro, elicit peptide-specific cytotoxic T lymphocyte response and tumor immunity.

Heat shock protein (HSP) preparations derived from cancer cells and virus-infected cells have been shown previously to elicit cancer-specific or virus-specific immunity. The immunogenicity of HSP preparations has been attributed to peptides associated with the HSPs. The studies reported here demonstrate that immunogenic HSP-peptide complexes can also be reconstituted in vitro. The studies show that (a) complexes of hsp70 or gp96 HSP molecules with a variety of synthetic peptides can be generated in vitro; (b) the binding of HSPs with peptides is specific in that a number of other proteins tested do not bind synthetic peptides under the conditions in which gp96 molecules do; (c) HSP-peptide complexes reconstituted in vitro are immunologically active, as tested by their ability to elicit antitumor immunity and specific CD8+ cytolytic T lymphocyte response; and (d) synthetic peptides reconstituted in vitro with gp96 are capable of being taken up and re-presented by macrophage in the same manner as gp96- peptides complexes generated in vivo. These observations demonstrate that HSPs are CD8+ T cell response-eliciting adjuvants.

A case of malignant schwannoma with overexpression of multidrug resistance gene (MDR1) after chemotherapy.

A 19-year-old:female patient with malignant schwannoma in the right knee was treated by combination chemotherapy including lipophilic anticancer compounds (cyclophosphamide, doxorubicin, vincristine and dacarbazine). The tumor was radically removed after chemotherapy, but metastatic lesions were noted in the right inguinal nodes. The patient died due to the cachexic state six months after surgery. In human neoplasm, P-glycoprotein (P-Gp) encoded by human multidrug resistance gene MDR1 is known to be related with multidrug resistant phenotype. Northern blot analysis revealed apparent MDR1 expression in the metastatic lesion, while the primary lesion showed faint MDR1 expression detected by only reverse transcriptase-polymerase chain reaction. P-Gp positive tumor cells were immunohistochemically detected both in the metastatic lesion and the primary lesion. The P-Gp-positive tumor cells in the metastatic lesion showed anaplastic features with highly atypical nuclei. These results suggest that MDR1 overexpression is related to the multidrug resistance phenomenon in the malignant schwannoma with morphological differences.

A case of epithelioid hemangioendothelioma associated with an artery.

We report a case of epithelioid hemangioendothelioma (EHE) arising in the left elbow of a 67-year-old woman. The tumor was characterized by centrifugal growth and association with the brachial artery, causing complete occlusion. Immunohestochemical and electron microscopical features were typical of EHE. The patient was free of local recurrence or disease metastasis for more than 3 years after tumor resection, but subsequently died of respiratory failure due to a primary lung cancer.

A xenograft line of human teratocarcinoma established by serial transplantation in severe combined immunodeficient (SCID) mice.

We established a xenograft line of human teratocarcinoma (TC-1) and characterized the pluripotency of differentiation of the neoplastic cells. A teratocarcinoma specimen obtained from a primary mediastinal lesion (22-year-old male patient) was inoculated subcutaneously into severe combined immunodeficient (SCID) mice. The carcinoma formed tumors in the mice. We established a xenograft line by serial passage of the tumor in vivo. The primary tumor was composed of papillary and pseudoglandular nests of highly atypical epithelial cells with foci of glomeruloid structures. The metastatic cells showed apparent production of mucin and differentiation to striated muscle. The xenograft line TC-1 retained the basic histopathological features seen in the primary and metastatic cells. The xenograft line showed focal differentiation to cartilage through serial passages. Immunohistochemical studies with anti-alpha-fetoprotein (AFP) demonstrated positive immunoreactivity on the TC-1 cells. Serum AFP levels were also elevated in the TC-1-bearing SCID mice. The human teratocarcinoma xenograft line TC-1 will be useful for studying the differentiation mechanism in human totipotent stem cells.

Advantage of in vivo chemosensitivity assay to detect vincristine-resistance in a human epidermoid carcinoma xenograft.

We examined both in vitro and in vivo chemosensitivity of the human epidermoid carcinoma xenograft xeKB3-1-R which shows overexpression of the multidrug resistance gene (MDR1). XeKB3-1-R was sensitive to vincristine (VCR, 6%) and doxorubicin (DOX, 9%) in the adhesive tumor cell culture system in vitro. However, this xenograft showed decreased sensitivity to VCR (65%) and DOX (42%) in an in vivo chemosensitivity assay. The in vivo resistance of xeKB3-1-R to both VCR and DOX was reversed by coadministration of cyclosporin A (VCR 22%, DOX 11%). The xenograft xeKB3-1-R expressed significantly higher levels of MDR1 than xeKB3-1. The results confirmed that multidrug resistance in xeKB3-1-R was related to enhanced MDR1 expression in vivo. The observed discrepancies between in vitro and in vivo chemosensitivities suggest that the in vivo sensitivity assay more accurately reflects drug resistance as a result of low-level MDR1 overexpression in solid tumors.

A mechanism for the specific immunogenicity of heat shock protein-chaperoned peptides.

Endogenously synthesized antigenic determinants are generally presented on major histocompatibility complex (MHC) class I molecules, whereas exogenous determinants are presented by MHC class II molecules. Here, it is shown that exogenous antigens chaperoned by a heat shock protein can be channeled into the endogenous pathway, presented by MHC class I molecules, and recognized by CD8+ T lymphocytes. This pathway is functional only in a subset of macrophages among the cell types tested. These observations provide a basis for the tumor-specific and virus-specific immunogenicity of cognate heat shock protein preparations and offer a mechanism for the classical phenomenon of cross-priming.