bryostatin-1 and Leukemia--Hairy-Cell

We have previously reported that bryostation 1 (Bryo 1) induces differentiation of chronic lymphocytic leukemia (CLL) in vitro to a hairy cell (HC) stage. This study tests the hypothesis that Bryo 1-differentiated CLL cells are more susceptible to 2-chlorodeoxyadenosine (2-CdA) than parent CLL cells. A recently established EBV-negative CLL line (WSU-CLL) from a patient resistant to chemotherapy including fludarabine was used to test this hypothesis. Both Bryo 1 (10-1000 nM) and 2-CdA (5.6-22.4 microM) exhibited a dose-dependent growth inhibitory effect on the WSU-CLL cell line. In vitro, the sequential exposure to Bryo 1 (100 nM for 72 h) followed by 2-CdA (11.2 microM) resulted in significantly higher rates of growth inhibition than either agent alone. Changes in immunophenotype, enzymes, lipids, proteins, and the DNA of WSU-CLL cells were studied before and after Bryo 1 treatment. Bryo 1 induced a positive tartrate-resistant acid phosphatase reaction and two important markers, CD11c and CD25, after 72 h of culture, confirming the differentiation of CLL to HC. The Fourier transformation infrared spectroscopic analysis showed that the amount of membrane lipids significantly increased in Bryo 1-treated cells compared to controls after 24 h, whereas the protein content, as well as the DNA content, decreased. This finding supports the change of CLL to HC. To evaluate the in vivo efficacy of Bryo 1 and 2-CdA, we used a xenograft model of CLL in WSU-CLL-bearing mice with severe combined immune deficiency. s.c. tumors were developed by injection of 10(7) WSU-CLL cells, and fragments were then transplanted into a new batch of severe combined immunodeficient mice. Bryo 1 and 2-CdA at the maximum tolerated doses (75 micrograms/kg i.p. and 30 mg/kg s.c., respectively) were administered to the mice at different combinations and schedules. The survival in days, the tumor growth inhibition ratio, the tumor growth delay, and the log10 kill of the mice treated with Bryo 1 followed by 2-CdA were significantly better than the control and other groups. We conclude that the sequential treatment with Bryo 1 followed by 2-CdA resulted in higher antitumor activity and improved animal survival.

Topics: Acid Phosphatase; Aged; Animals; Antineoplastic Combined Chemotherapy Protocols; Apoptosis; Bryostatins; Cell Division; Cladribine; DNA, Neoplasm; Drug Administration Schedule; Drug Screening Assays, Antitumor; Humans; Lactones; Leukemia, Hairy Cell; Leukemia, Lymphocytic, Chronic, B-Cell; Lipid Metabolism; Macrolides; Male; Mice; Mice, SCID; Neoplasm Proteins; Neoplasm Transplantation; Spectroscopy, Fourier Transform Infrared; Transplantation, Heterologous; Tumor Cells, Cultured

B-Chronic lymphocytic leukemia (B-CLL) and hairy cell leukemia (HCL) are both differentiated B-cell lymphoproliferative disorders. Prior studies have suggested that phorbol esters and the macrocyclic lactone Bryostatin-1, which are both protein kinase-C activators, can induce the differentiation of B-CLL cells into HCL cells in vitro, as evidenced by morphology, phenotype and TRAP activity. The differentiating effect of all-trans retinoic acid on B-CLL cells has been less extensively studied. We studied the effects of incubating adherence purified B-CLL cells with phorbol myristic acetate (PMA), all-trans retinoic acid (ATRA), and Bryostatin-1. None of these agents induced a true HCL phenotype (CD5-, CD11c/CD25 coexpression) under the conditions studied.

Topics: Acid Phosphatase; Antigens, CD; Antigens, Neoplasm; B-Lymphocytes; Biomarkers, Tumor; Bryostatins; Cell Differentiation; Enzyme Activation; Humans; Immunophenotyping; Isoenzymes; Lactones; Leukemia, Hairy Cell; Leukemia, Lymphocytic, Chronic, B-Cell; Macrolides; Neoplastic Stem Cells; Protein Kinase C; Tartrate-Resistant Acid Phosphatase; Tetradecanoylphorbol Acetate; Tretinoin; Tumor Cells, Cultured

The phorbol esters induce differentiation of chronic lymphocytic leukemia (CLL) cells. Clinical use of this observation has been hampered by the fact that phorbol esters are also tumor promoters. In this study we demonstrate that another protein kinase C activator, without tumor promoting activity, has similar effects on CLL cells. Fresh leukemic cells from the peripheral blood of 13 patients with CLL were isolated and cultured in the absence (control) or presence of Bryostatin 1 or 12-0-tetradecanoylphorbol 13-acetate (TPA). Aliquots of cells were then analyzed after 24, 72 and 120 hours for morphological changes, acid phosphatase (ACP) and the co-expression of two hairy cell-associated surface antigens, CD22 and CD11c, by flow cytometry. Bryostatin 1 induced changes in shape and morphology similar to TPA, with adherence and increase in cell size, abundant cytoplasm and irregular cytoplasmic membrane. Both agents induced a statistically significant increase in the expression of CD22 and CD11c compared with control (p < 0.0008). There was no significant difference between the two agents in the degree of expression of these two markers. Both agents also induced ACP that was tartrate resistant (TRAP). These changes indicate that Bryostatin is as effective as TPA in inducing further differentiation of CLL cells to a hairy cell stage.

Topics: Acid Phosphatase; Aged; Aged, 80 and over; Antigens, CD; Antigens, Differentiation, B-Lymphocyte; Bryostatins; CD11 Antigens; Cell Adhesion Molecules; Cell Differentiation; Enzyme Activation; Female; Humans; Immunophenotyping; Lactones; Lectins; Leukemia, Hairy Cell; Leukemia, Lymphocytic, Chronic, B-Cell; Macrolides; Male; Middle Aged; Protein Kinase C; Sialic Acid Binding Ig-like Lectin 2; Tetradecanoylphorbol Acetate; Tumor Cells, Cultured