Bovine seminal ribonuclease exerts selective cytotoxicity toward neuroblastoma cells both sensitive and resistant to chemotherapeutic drugs.
BACKGROUND
Bovine seminal ribonuclease (BS-RNase) exerts selective cytotoxicity toward different types of tumor cells. In the present study, we tested the effects of BS-RNase on cultured neuroblastoma (NB) cells resistant to chemotherapeutic agents. The selectivity of the antitumoral activity of BS-RNase was evaluated using cultures of CD34+ hematopoietic stem cells.


METHODS
Human NB cell lines including IMR-32, UKF-NB-2 and UKF-NB-3 were selected for resistance against vincristine, doxorubicin or cisplatin by exposure to increasing concentrations of the respective drug. The cytotoxicity of the drugs to NB cells was evaluated using a clonogenic assay in a methylcellulose medium. Peripheral blood progenitor cells were obtained from adult healthy donors by positive selection using specific anti-CD34+ antibodies. The toxicity of BS-RNase to CD34+ cells was assessed in the direct clonogenic assay using methylcellulose medium or in ex vivo expansion culture supplemented with hematopoietic growth factors.


RESULTS
In the clonogenic assay it was shown that BS-RNase completely inhibits growth of both parental NB cells and their sublines resistant to chemotherapeutic drugs at concentrations (up to 50 micrograms/ml) which have no significant influence on the growth of colony-forming units, granulocyte macrophage and erythroid burst-forming units. Moreover, BS-RNase had no effect on the ex vivo expansion of total hematopoietic cells or of colony-forming cells from CD34+ progenitors.


CONCLUSIONS
BS-RNase is a highly efficient agent against NB cells resistant to chemotherapeutic drugs. The lack of toxicity to hematopoietic progenitor cells suggests that BS-RNase is also likely to have tolerable hematopoietic toxicity.
Cinatl
J
J
Institute of Medical Virology, Center of Hygiene, Frankfurt am Main, Germany. cinatl@em.uni-frankfurt.de
Cinatl
J
J
Kotchetkov
R
R
Matousek
J
J
Woodcock
B G
BG
Koehl
U
U
Vogel
J U
JU
Kornhuber
B
B
Schwabe
D
D
D020168:ATP Binding Cassette Transporter, Subfamily B, Member 1 / Q000235:genetics; D000328:Adult; D000818:Animals; D018952:Antigens, CD34 / Q000097:blood; D000970:Antineoplastic Agents / Q000633:toxicity*; D002417:Cattle; D002470:Cell Survival / Q000187:drug effects*; D002478:Cells, Cultured; D002945:Cisplatin / Q000633:toxicity; D004317:Doxorubicin / Q000633:toxicity; D018432:Drug Resistance, Multiple; D004722:Endoribonucleases / Q000633:toxicity*; D019450:Genes, MDR / Q000187:drug effects; D006412:Hematopoietic Stem Cells / Q000166:cytology / Q000187:drug effects*; D006801:Humans; D007700:Kinetics; D009447:Neuroblastoma / Q000235:genetics / Q000473:pathology*; D014407:Tumor Cells, Cultured; D014750:Vincristine / Q000633:toxicity
D020168:ATP Binding Cassette Transporter, Subfamily B, Member 1; D018952:Antigens, CD34; D000970:Antineoplastic Agents; D014750:Vincristine; D004317:Doxorubicin; D004722:Endoribonucleases; C032523:ribonuclease SPL; D002945:Cisplatin