[Acute megakaryoblastic leukemia with complex chromosomal aberrations].

A case of acute megakaryoblastic leukemia with complex chromosomal aberrations is reported. A 63-year-old man was admitted to our hospital because of pancytopenia. Bone marrow aspiration resulted in a dry tap and biopsy showed hypoplastic marrow with fibrosis. Blast cells in the peripheral blood were identified as megakaryoblasts because they were positive for electron microscopic platelet peroxidase (PPO). In addition, monoclonal antibody, TP80, to platelet glycoprotein II b-III a reacted with in about 26% of the blast cells. Chromosomal analysis of the peripheral blood revealed a mosaic pattern of a normal karyotype and abnormal ones, including 44, XY, -5, -7, -18, 10q-, +marker.

The production of transforming growth factor-beta in acute megakaryoblastic leukemia and its possible implications in myelofibrosis.

Acute myelofibrosis is often associated with acute megakaryoblastic leukemia (AMKBL). Although the exact mechanism for the progression of myelofibrosis in AMKBL is unclear, certain humoral factors from megakaryoblastic cells, the precursors of platelets, may be involved in the enhancement of collagen synthesis by bone marrow fibroblasts. The present study, therefore, is an investigation of the possible pathogenic role of transforming growth factor-beta (TGF-beta), known to be a very potent collagen-stimulating factor found in platelets in the myelofibrosis of AMKBL. The results obtained were as follows: (1) Conditioned media from peripheral megakaryoblasts taken from an AMKBL patient and from established megakaryoblast cell lines (MEG-01) had much greater stimulatory effects on collagen synthesis in bone marrow fibroblasts than conditioned media from other leukemic cell types. (2) Based on an assessment of soft agar colony formation, there was greater TGF-beta activity in media that had been conditioned from megakaryoblasts than in media from other leukemic cell types. (3) When compared with other leukemic-cell types, megakaryoblasts showed substantially greater expression of TGF-beta mRNA that was hybridized at 2.5 kb with a TGF-beta cDNA probe, and TGF-beta polypeptides were detected at 13 Kd with anti-TGF-beta antibodies. (4) The addition of the anti-TGF-beta antibody inhibited the stimulatory effects of the megakaryoblast conditioned medium on collagen synthesis in bone marrow fibroblasts. These results clearly suggest that megakaryoblasts produce and secrete an active form of TGF-beta and stimulate collagen synthesis in bone marrow fibroblasts in a paracrine manner.

Expression of TGF-beta gene in adult T cell leukemia.

Peripheral mononuclear cells from adult T cell leukemia (ATL) patients were analyzed in comparison with other types of leukemia cells, for the expression of transforming growth factor-beta (TGF-beta) mRNA, for the presence of TGF-beta activity (colony stimulating activity for normal rat kidney fibroblasts [NRK]) in conditioned medium and for their susceptibility to exogenous TGF-beta. Highly elevated TGF-beta mRNA levels were observed in all five ATL cell samples tested; however, in three acute myelogenous leukemia (AML) samples, in one acute lymphatic leukemia (ALL), and one chronic myelogenous leukemia (CML), TGF-beta expression was relatively lower. In normal peripheral mononuclear cells TGF-beta mRNA was weakly detectable. Colony stimulating activity for NRK found in the conditioned medium from ATL cells as well as other leukemia cells correlated well with the levels of TGF-beta mRNA expression. In all three ATL samples tested, stimulation of 3H-thymidine uptake by purified TGF-beta from platelets was apparent. These results suggest that ATL cells are secreting active TGF-beta in a relatively high amount, as compared with other leukemia cells, and may proliferate in response to the factor via an autocrine manner. Furthermore, considering that TGF-beta stimulates bone resorption, we can speculate that the relatively high amount of TGF-beta in ATL cells contributes to the hypercalcemia frequently seen in ATL patients.

Growth promoting activity of PDGF, EGF and TGF-beta on highly metastatic subline of Meth A cells.

The response of a highly metastatic cell line of methylcholanthrene induced A fibrosarcoma (Meth A) to growth factors from platelets was examined. The highly metastatic cell subline (MH) proliferated more rapidly than its parental counterpart cell subline (ML) in a medium containing platelet lysate. However, when the three major growth factors from platelets, ie, platelet-derived growth factor, epidermal growth factor, and transforming growth factor-beta (PDGF, EGF, TGF-beta), were independently examined for their growth promoting activity, the former 2 growth factors preferentially stimulated the proliferation of ML and the latter growth factor rather suppressed the growth of both cells. On the other hand, the combined effects of these factors were more marked on MH. This combination effect was supported by the evidence that the number of receptors for EGF (which is probably an essential growth factor for the Meth A cell) was increased by pretreatment with PDGF or TGF-beta. Thus, the highly metastatic cells of MH were considered to be the most susceptible to growth factors released from platelets. This conclusion is consistent with the concept that platelets may play an important role in the formation of blood-borne metastasis by releasing growth factors to promote the proliferation of tumor cells, following aggregation with tumor cells.

Transferrin receptors in human cancerous tissues.

The clinical significance of radioreceptor assay for transferrin receptors of human cancerous tissues was evaluated. Fresh surgical specimens from various carcinoma tissues were solubilized with 1% Triton X-100 and the extracts were mixed with 125I-labelled diferric transferrin. The free transferrin and the receptor-bound transferrin were separated by 15% polyethylene glycol precipitation. The % specific transferrin binding to gastric, colonic, lung and mammary carcinoma tissues ranged between 3.9 and 13.9%, whereas those for normal stomach and colon were less than 2%. The concentrations of transferrin receptors in these cancerous tissues ranged between 3.7 and 28.3 pmole/g tissues. It was concluded that the amounts of transferrin receptors were significantly increased in all of the tumor tissue extracts examined and may thereby provide a useful marker for the diagnosis of malignancies.

Phosphorylation of hydroxylysine residues in collagen synthesized by cultured aortic smooth muscle cells.

O5-Phosphohydroxylysine was chemically synthesized and techniques were established for its identification by combined use of cation-exchange chromatography, thin-layer electrophoresis at pH 1.9 and 3.5, and thin-layer chromatography. Clean separation of phosphohydroxylysine from the other phospho amino acids, phosphoethanolamine, and phosphocholine was achieved. Conditions were also determined to permit hydrolysis of proteins in 2 M HCl without loss of the phosphono group of phosphohydroxylysine residues. Experiments were then performed showing that 32P was incorporated into the hydroxylysine residues of cell-associated collagens when cultured calf aorta medial smooth muscle cells were incubated with [32P]orthophosphate. In other experiments, the cells incorporated [3H]lysine into hydroxylysine residues of cell-associated collagen and then 32P into phosphohydroxylysine residues. The doubly labeled phosphohydroxylysine subsequently isolated showed nearly 1:1 stoichiometry with respect to incorporation of precursor lysine and phosphorus. Finally, in preliminary experiments done with a cell-free extract of the smooth muscle cells, 32P was transferred from [gamma-32P]ATP to hydroxylysine residues in several kinds of collagenous substrates. Thus, this work shows that smooth muscle cells have the capacity to phosphorylate hydroxylysine residues in their cell-associated collagens and provides preliminary evidence that a protein kinase is involved.

[Case of choriocarcinoma of a probable testicular origin with a good response to cis-diamminedichloroplatinum (CDDP)].

A case of choriocarcinoma responding well to cis-diamminedichloroplatinum (CDDP) was reported. A 24-year-old male was admitted to our hospital with chief complaints of upper abdominal discomfort and gynecomastia. Physical findings on admission included solid tumors in the upper abdomen and bilateral inguinal regions. The chest X-ray picture showed numerous coin lesions, and abdominal ultrasound examination revealed a widespread metastasis in the retroperitoneum. Blood chemical analysis pointed out the high levels of LH, HCG, and beta-subunit of HCG. The pathological diagnosis of the biopsied inguinal mass was choriocarcinoma. The patient was treated with CDDP, vincristine and bleomycin according to the protocol of Einhorn. After three courses of this therapy, serum HCG level was normalized and pulmonary metastatic lesions were diminished, although abdominal ultrasound examination showed remnants of the decreased tumor masses. The patient was transferred to the urological department for further cytoreductive therapy.