dolastatin-10 and Lymphoma--Large-B-Cell--Diffuse

We studied the antitumor effects of dolastatin 10, its structural modification, auristatin PE (TZT-1027), and vincristine alone and in combination with bryostatin 1 on a human diffuse large cell lymphoma line (WSU-DLCL2) in vitro and in vivo. WSU-DLCL2 cells were cultured in RPMI 1640 at a concentration of 2 x 10(5)/ml using a 24-well plate. Agents were added to triplicate wells, and cell count, viability, mitosis and apoptosis were assessed. Dolastatin 10 showed no apparent inhibition of cell growth at concentrations less than 500 pg/ ml. Auristatin PE showed significant growth inhibition at concentrations as low as 10 pg/ml, while vincristine had a minimal effect at 50 pg/ml. Dolastatin 10, auristatin PE and vincristine-treated cultures, at 50 pg/ml, exhibited 11, 1.7; 45, 11.8%; and 39, 25% mitosis and apoptosis, respectively. In the WSU-DLCL2 SCID mouse xenograft model, the efficacy of these agents alone or in combination with bryostatin 1 was evaluated. Tumor growth inhibition (T/C), tumor growth delay (T-C) and log10 kill for dolastatin 10, auristatin PE, vincristine and bryostatin 1 were 30%, 14 days and 1.4; 0.0%, 55 days and 5.5; 29.6%, 16 days and 1.6; and 39%, 7 days and 0.7, respectively. When given in combination, two out of five mice treated with auristatin PE + bryostatin 1 were free of tumors for 150 days and were considered cured. Dolastatin 10 + bryostatin 1 and vincristine + bryostatin 1 combinations were highly active but no cure was observed. We conclude that: (i) auristatin PE is more effective in this model than dolastatin 10, vincristine or bryostatin 1, (ii) auristatin PE can be administered at a concentration 10 times greater than dolastatin 10, and (iii) there is a synergistic effect between these agents and bryostatin 1, which is more apparent in the bryostatin 1 + auristatin PE combination. The use of these agents should be further explored clinically in the treatment of lymphoma.

Topics: Animals; Antineoplastic Combined Chemotherapy Protocols; Bryostatins; Depsipeptides; Drug Synergism; Humans; Lactones; Lymphoma, Large B-Cell, Diffuse; Macrolides; Mice; Mice, Inbred ICR; Oligopeptides; Time Factors; Tumor Cells, Cultured; Vincristine

The effects of dolastatin 10 (Dol10) and dolastatin 15 (Dol15) alone, and after treatment with bryostatin 1 (Bryo1), on human diffuse large cell lymphoma cell line (WSU-DLCL2) were studied. At a concentration of 1.0 ng/ml Dol10 and Dol15 showed significant growth inhibition (p < 0.05). This inhibition was intensified when the cells were pretreated for 24 h with 200 nM Bryo1. Bryo1, Dol10 and Dol15 induced apoptosis which was seen on morphological examination, by flow cytometry and DNA fragmentation on agarose gel electrophoresis. Cells pretreated with Bryo1 and then exposed to Dol10 showed an increase in apoptosis compared with cells that were treated with the Dol10, Dol15 alone. Immunocytochemistry revealed that WSU-DLCL2 cells express the bcl-2 oncoprotein constitutively. bcl-2 expression was decreased when cells were treated with Bryo1, Dol10 or Dol15 and abolished with the Bryo1/Dol10 combination. WSU-DLCL2 cells were negative for p53 protein expression, upon treatment with Bryo1 or Dol10, the expression of p53 was weak and moderate with the Bryo1/Dol10 combination. The inverse correlation between bcl-2 and p53 oncoprotein expression seems to be related to induction of apoptosis in this lymphoma cell line.

Topics: Antineoplastic Agents; Apoptosis; Bryostatins; Cell Division; Depsipeptides; DNA, Neoplasm; Electrophoresis, Agar Gel; Flow Cytometry; Humans; Immunohistochemistry; Lactones; Lymphoma, Large B-Cell, Diffuse; Macrolides; Oligopeptides; Protein-Tyrosine Kinases; Proto-Oncogene Proteins; Proto-Oncogene Proteins c-bcl-2; Tumor Cells, Cultured; Tumor Suppressor Protein p53