Three growth factors (acidic, neutral and basic) were partially purified from platelet lysate by DE 52 cellulose chromatography. The basic factor was proved to be identical to PDGF hitherto reported. The growth promoting activity of these three factors for variouse cell lines was studied in vitro.Basic factor (PDGF) promoted growth of fibroblast (Swiss 3T3, SV 3T3) as has been described previouly, but had relatively less activity of growth promotion to malignant tumor cell lines (K562, HeLa and RPMI 4788).On contrast, acidic factor strongly stimulated the proliferation of tumor cells and, to less extent, of fibroblasts.Malignant cells (K562) were synchronized to pre S phase by addition of excess of thymidine and hydroxyurea, and thus synchronized cells were also proved to be more sensitive to acidic factor than to PDGF, indicating that the sensitivity is not related to cell cycle.
The adhesive properties of highly and weakly metastatic murine sarcoma (Meth A) clones were investigated. A highly metastatic clone, MH-02, preferentially adhered to type IV collagen-coated plastic dishes and to bovine pulmonary arterial endothelial cell-coated plastic dishes as compared to a weakly metastatic clone, ML-01. Pretreatment of MH-02 and ML-01 cells with antisera against MH-02 cells resulted in almost equivalent adhesiveness to type IV collagen. Preincubation of 125I-radiolabeled tumor cells with the antisera against MH-02 significantly reduced the arrest of MH-02 cells in the lung, but ML-01 cells were not affected. The number of pulmonary metastatic nodules of MH-02 cells was reduced to the same level as that of ML-01 cells by preincubation of the tumor cells with the antisera in an experimental metastasis experiment. These results indicated that the high metastatic ability of MH-02 can be attributed to its preferential adhesiveness to type IV collagen. The type IV collagen-binding proteins of MH-02 and ML-01 were analyzed by sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE) and autoradiography. Among several proteins which bound to type IV collagen, expression of a protein with a molecular weight of 29 kD was significantly greater in MH-02 than in ML-01. These results suggest that the greater adhesion of highly metastatic MH-02 cells to type IV collagen is due to enhanced expression of the type IV collagen-binding 29 kD protein.
The relation between chronic respiratory disease and infection with Chlamydia trachomatis in premature infants was investigated to ascertain the aetiological importance of intrauterine C trachomatis infection and chronic respiratory disease in premature infants. Serum IgM antibodies against C trachomatis were determined by enzyme linked fluorescence assay. Sections of lung tissues obtained by biopsy and at necropsy were also tested for the presence of antigens using fluorescein conjugated monoclonal antibodies to C trachomatis. Of 16 sera from premature infants with chronic respiratory diseases clinically diagnosed as bronchopulmonary dysplasia or the Wilson-Mikity syndrome, five had IgM antibodies to C trachomatis L2 strain by enzyme linked fluorescence assay (titre greater than or equal to 1/500). Of 37 sera from premature infants with extremely low birth weights, two had IgM antibodies to C trachomatis. No specific IgM antibody was detected in 31 neonates who showed raised serum IgM concentrations but who did not have respiratory tract symptoms. C trachomatis was identified from two specimens of lung tissue obtained at necropsy from premature infants with chronic respiratory disease positive for IgM antibody. These findings indicate the aetiological importance of intrauterine C trachomatis infection in chronic respiratory disease in premature infants.
Abstract Expression of various oncogenes ( ras, myc, erbB2, src, fyn, yes and sis ) in a high‐metastatic clone (MH‐02) derived from a murine methylcholanthrene‐induced fibrosarcoma A (Meth A) was compared with those of its parent clone (ML‐01) by Northern blot analysis. Two oncogenes, fyn , belonging to the tyrosine‐kinase family, and sis , belonging to the cellular‐growth‐factor family, were found to have higher signals (3.6‐fold and 1.8‐fold respectively) in MH‐02 than in ML‐01 cells. To explore the possibility that higher expression of these oncogenes is involved in enhanced metastasis of the MH‐02 clone, ML‐01 was transfected by a fyn vector and the metastatic potential of the transfectant was examined. Mice administered fyn ‐transfected ML‐01 cells had significantly increased metastatic nodules in the lung, as compared with those whose ML‐01 cells were transfected with control vector without the fyn gene. The result indicates that the fyn gene is one of the factors governing the metastatic potential of Meth A cells.
We treated two chronic phase chronic myelogenous leukemia patients with imatinib mesylate. Hematological complete remission and significant regression of bone marrow fibrosis were observed in both patients. The large amount of TGF-beta produced by increased bone marrow megakaryocytes might have caused the myelofibrosis, and it was revealed that imatinib mesylate brought about regression of the myelofibrosis by reducing the number of megakaryocytes in both patients.
In the present paper, we investigated the pathophysiological implication of TGF-beta from megakaryocytes or megakaryoblasts in the development of myelofibrosis. In the bone marrow of myelofibrosis, proliferation of megakaryocytes is often noticed. We therefore investigated the TGF-beta expression in the bone marrow megakaryocytes from 12 chronic myeloproliferative disorder patients with myelofibrosis by immunohistochemical analysis. About all the specimen showed strong positivity for TGF-beta. In order to examine whether megakaryoblasts produce TGF-beta, we then measured TGF-beta activity in the conditioned medium (CM) of megakaryoblasts from a patient with acute megakaryoblastic leukemia who had profound myelofibrosis. The CM showed strong collagen synthesis stimulating activity which was nullified by addition of anti TGF-beta antibody. Since TGF-beta exists as latent form in platelets, TGF-beta was considered to be altered from active to latent form during megakaryocytes differentiation. In this context, MEG-01, a megakaryoblastic cell line which produces active TGF-beta was underwent differentiation to produce platelet-like bleb with TPA treatment. During the differentiation, MEG-01 showed the decrease of active TGF-beta production and increase of latent TGF-beta together with the production of LTBP. These results suggest that megakaryoblasts produce active TGF-beta and may may cause myelofibrosis, while more differentiated megakaryocytes produce latent TGF-beta. Mechanism by which megakaryoblast escape from negative autocrine of active TGF-beta was also investigated. MEG-01 was found to express mutated p53 which is considered to be responsible for impaired signal transduction of TGF-beta.
Aberrant crypt foci of the colon are possible precursors of adenoma and cancer, but these lesions have been studied mainly in surgical specimens from patients who already had colon cancer.
