Implication of tyrosine kinase receptor and steel factor in cell density-dependent growth in cervical cancers and leukemias.

Cell-cell interaction is important in the expansion of leukemic cells and of solid tumors. Steel factor (SF) or Kit ligand is produced as a membrane-bound form (mSF) and a soluble form. Because both primary gynecological tumors and primary leukemic cells from patients with acute myeloblastic leukemia (AML) have been shown to coexpress c-Kit and SF, we addressed the question of whether mSF could contribute to cell interaction in these cancers. Investigations on primary cervical carcinomas have been hindered by the fact that the cells do not grow in culture. We report herein the establishment of two cervical carcinoma cell lines, CALO and INBL, that reproduce the pattern of SF/c-Kit expression observed in primary tumor samples. In addition, these cells exhibit marked density-dependent growth much in the same way as AML blasts. Using an antisense strategy with phosphorothioate-modified oligonucleotides that specifically target SF without affecting other surface markers, we provide direct evidence for a role of mSF and c-Kit in cell interaction and cell survival in these gynecological tumor cell lines as well as in primary AML blasts. Finally, our study defines the importance of juxtacrine stimulation, which may be as important, if not more, than autocrine stimulation in cancers.

Low-dose cytarabine and aclarubicin in combination with granulocyte colony-stimulating factor (CAG regimen) for previously treated patients with relapsed or primary resistant acute myelogenous leukemia (AML) and previously untreated elderly patients with AML, secondary AML, and refractory anemia with excess blasts in transformation.

We used the CAG regimen (low-dose cytarabine [10 mg/m2 per 12 hours, days 1-14], aclarubicin [14 mg/m2 per day, days 1-4], and granulocyte colony-stimulating factor [200 micrograms/m2 per day, days 1-14]) for the treatment of patients with primary resistant acute myelogenous leukemia (AML) and previously untreated elderly patients with AML, secondary AML, and refractory anemia with excess blasts in transformation (RAEB-T) in addition to relapsed AML. Forty-three of 69 (62%) patients achieved complete remission (CR), including 29 of 35 (83%) patients with relapsed AML, 1 of 8 patients with primary resistant AML, 5 of 8 elderly patients with previously untreated AML, and 8 of 18 patients with previously untreated secondary AML or RAEB-T. Ten of 22 (45%) patients > or = 65 years old achieved CR. The patients who achieved CR received at least 1 course of modified CAG therapy as the first consolidation therapy, followed by various second consolidation and intensification therapies. The median disease-free survival and overall survival were 8 and 15 months, respectively, for relapsed AML; 11 and 8 months for the elderly patients; and 8 and 17 months for secondary AML and RAEB-T. Myelosuppression was mild to moderate, and other than fever, severe nonhematologic toxicity was rare. CAG as the induction therapy seems promising for the treatment of various categories of poor-prognosis AML.

Mature and immature myeloid cells decrease the granulocyte colony-stimulating factor level by absorption of granulocyte colony-stimulating factor.

We studied the effects of polymorphonuclear neutrophils (PMN) and immature myeloid cells on the granulocyte colony-stimulating factor (G-CSF) level in vitro to better understand the regulatory mechanisms of neutropoiesis. Intact normal PMN decreased the G-CSF level after incubation with recombinant human (rh) G-CSF in a time- and dose-dependent manner. The percent reduction decreased as the concentration of rhG-CSF increased. However, the cell-free PMN-conditioned medium (PMN-CM) did not decrease the G-CSF level. The intact PMN also decreased the granulocyte-macrophage (GM)-CSF level after culture with rhGM-CSF, but did not affect the monocyte (M)-CSF level after culture with rhM-CSF. Normal bone marrow (BM) immature neutrophilic cells and G-CSF-dependent acute myeloid leukemic cells (OCI/AML la) also decreased the G-CSF level, whereas K-562 cells, which have no detectable G-CSF receptors, did not affect it. Phenylarsine oxide (PhAsO), an inhibitor of endocytosis of ligand receptor complex, abrogated this decreasing effect of intact PMN and OCI/AML la cells. These findings suggest that mature and immature myeloid cells negatively regulate neutropoiesis by, at least in part, decreasing the G-CSF level probably through receptor-mediated continual absorption and metabolism of G-CSF.

Preferential inhibitory effect of soluble factor(s) in human bone marrow stromal cells on proliferation of K562 leukemia cells versus normal myeloid progenitor cells.

We examined the effect of diffusible factors generated during the culture of the KM102 stromal cell line as well as in long-term bone marrow culture (LTBMC) on K562 leukemia cells, with respect to proliferation of clonogenic cells as well as total cells, and compared it with the effect on normal myeloid progenitors (CFU-GM). Proliferation of K562 cells plated in diffusion chambers was inhibited by coculture for 3-5 days in the fluid phase of stromal cell cultures or stromal cell-conditioned medium (CM), while CFU-GM proliferation was not inhibited under the same culture conditions. The inhibitory action was not attributed to the exhaustion of nutrients or growth promoting factors such as stem cell factor. These findings suggest that bone marrow stromal cells secrete diffusible molecule(s) which exert a preferential inhibitory effect on K562 leukemic cells vs. normal CFU-GM. Neutralization with antibodies against hematopoiesis-inhibiting cytokines such as TGF-beta 1, IFN-gamma, MIP-1 alpha and IL-4 which were detected in stromal cell-CM, failed to abrogate the inhibitory effect of KM102-CM on K562 cells. IL-1, TNF-alpha, IFN-alpha and lipopolysaccharides, known as stimulators of various cytokines from stromal cells, could not enhance the inhibitory activity. Further characterization of the factors may have implications for the treatment of leukemias.

[Comparison of low-dose cytosine arabinoside and aclarubicin in combination with granulocyte colony-stimulating factor to intermediate-dose cytosine arabinoside and mitoxantrone with or without etoposide in the treatment of relapsed acute myeloid leukemia].

We used a new chemotherapy regimen for the treatment of 18 consecutive patients with relapsed AML. The regimen consisted of low-dose cytosine arabinoside (Ara-C), low-dose aclarubicin and concurrent use of G-CSF (CAG regimen). Fifteen out of 18 patients (83%) achieved complete remission (CR). Median CR duration and median survival were 6 months and 15 months, respectively. These results were similar to those of previously reported salvage therapies for relapsed AML including intensive chemotherapy consisting of intermediate-dose Ara-C and sequential mitoxantrone with or without etoposide (MC/MEC), which we previously adopted. Myelosuppression and non-hematological toxicities were apparently lower and less frequent compared to MC/MEC. The CAG regimen seems promising for the treatment of relapsed AML with its low toxicity contributing to a high quality of life for the patient.

Concurrent use of granulocyte colony-stimulating factor with low-dose cytosine arabinoside and aclarubicin for previously treated acute myelogenous leukemia: a pilot study.

We used a new chemotherapy regimen for the treatment of 18 consecutive patients with relapsed AML (median age 44 years, range 18-74). The regimen consisted of low-dose cytosine arabinoside (10 mg/m2/12 h, usually day 1 to 14), low-dose aclarubicin (10-14 mg/m2/day, day 1 to 4), and concurrent use of G-CSF (200 micrograms/m2/day) (CAG regimen). Overall, 15/18 patients (83%) achieved complete remission (CR) after one or two courses, including eight out of ten refractory patients with early relapse, second or subsequent relapses, and/or resistant relapse. Two of three patients who relapsed, achieved CR again after reinduction with a modified CAG regimen. Fourteen of the 15 complete remitters received consolidation therapy with the CAG regimen modified, followed by oral busulfan in eight cases, and by allogeneic bone marrow transplantation in two cases. At a median follow-up of 12 months, median CR duration and survival were 6 months and 17 months, respectively. Myelosuppression in the first course of induction therapy was moderate to severe. However, severe non-hematologic toxicity (WHO grade > or = 3) was characteristically rare. Although this is a preliminary study, the CAG combination seems promising for the treatment of relapsed AML, with its low toxicity contributing to a higher quality of life for the patient.

Suppression of normal hematopoiesis in acute leukemia: effect of leukemic cells on bone marrow stromal cells and hematopoietic progenitor cells.

Effects of leukemic cells (LC) on bone marrow stromal cells and myeloid progenitor cells (CFU-C) were studied in vitro, using LC lines with different lineage characteristics. LC and/or LC-conditioned medium (LC-CM) inhibited the growth of a stromal cell line, KM-101, and adherent cells of a long-term bone marrow culture (LTBMC) established from normal bone marrow. The inhibition was more prominent when LC were cocultured directly with KM-101 cells than when LC were cultured separate from the KM-101 cell layer via membrane filtration, or when LC-CM was added to KM-101 cells or LTBMC. LC-CM also exerted an inhibitory effect on the ability of LTBMC adherent cells to bind CFU-C. Furthermore, LC-CM inhibited the growth and survival of early and late CFU-C, but not the growth of LC. All these inhibitory effects were seen irrespective of the lineage characteristics of LC, but not seen with CM prepared from normal bone marrow immature granulocytes or peripheral blood lymphocytes. Neither tumor necrosis factor-alpha nor interferon-alpha was detected in these LC-CM. These findings suggest that LC suppress normal hematopoiesis through the release of undefined substance(s) inhibiting the growth and/or survival of stromal cells and hemopoietic progenitor cells as well as the function of stromal cells.

[Amylase-producing plasma cell dyscrasia. Genomic analysis in a case of intramuscular tumor formation and a review of the literature].

We describe a 53-year-old male patient with multiple myeloma (IgA, kappa) who showed massive intramuscular tumors and hyperamylasemia of the salivary (S) type 10 months after initial diagnosis. Suspension culture of the abnormal plasma cells in the pleural fluid showed the production of S-amylase, which was confirmed by the expression of S-amylase mRNA comigrating with salivary gland mRNA. Cytogenetic analysis of the cells showed common abnormalities 1p+q-and 8q+. They expressed IL-6 mRNA, but not c-myc mRNA. Neither structural abnormality nor amplification was detected in the alleles of S amylase, and c-myc using Southern blot analysis. All of the eight patients with plasma cell dyscrasia with hyperamylasemia reported so far (including the present one) are Japanese, and showed S-type hyperamylasemia and extramedullary tumor formation at initial diagnosis or during the course of the disease. All of the four patients in whom cytogenetic analysis was performed had structural abnormalities of chromosome 1, on which the S-amylase gene is known to be located, although the break point were variable.

Comparative effects of G-CSF, GM-CSF and IL-3 on cytosine arabinoside- and daunorubicin-mediated cytotoxicity of acute myeloid leukemia cells and normal myeloid progenitors.

We carried out an in vitro study on the combined effects of three CSF (G-CSF, GM-CSF and IL-3) plus the cycle-specific chemotherapeutic drugs [cytosine arabinoside (Ara-C) and daunorubicin (DNR)] on the proliferation and cytotoxicity of blasts and clonogenic cells (CFU-AML) in the AML-193 cell line, in AML patients and in normal bone marrow CFU-GM. The number of surviving blasts and/or DNA synthesis in blasts treated with CSF plus Ara-C or DNR was greater than those treated without CSF in the AML-193 cell line, and in some AML patients. On the other hand, the Ara-C- and DNR-mediated cytotoxicity of CFU-AML was not abrogated by CSF in any instance, but rather, it was significantly enhanced by all the CSF in the majority of instances. Although the enhancement was clearer when Ara-C was used, compared with DNR, there were no significant differences among the enhancing effects of the CSF. Under the same culture conditions as those for CFU-AML, all of the CSF significantly enhanced the Ara-C-mediated cytotoxicity of day 7 normal CFU-GM, although to a lesser extent than in CFU-AML. However, none of the CSF significantly affected the Ara-C-mediated cytotoxicity of day 14 normal CFU-GM or the DNR-mediated cytotoxicity of day 7 or day 14 normal CFU-GM. These results suggest that in the selection of a strategy entailing combined use of cycle-specific drugs plus CSF to increase the antileukemic effectiveness of chemotherapy in AML, G-CSF is preferable to GM-CSF or IL-3, since it has fewer potential clinical side effects, and that, furthermore, DNR may be as useful as Ara-C.