Enhanced cytotoxic interaction between 5-fluorouracil and 4-hydroperoxycyclophosphamide against L1210 murine leukemic cells: applicability to ex vivo purging.
Eradication of contaminated tumor cells in bone marrow is a matter of utmost concern in the setting of autologous bone marrow transplantation. 4-Hydroperoxycyclophosphamide (4-HC) is often used for ex vivo chemical purging of contaminated tumor cells in bone marrow. The marrow from patients pretreated with 5-fluorouracil (5-FU) is enriched with multifactor-responsive high proliferative potential colony-forming cells. To develop an efficient ex vivo chemical purging system, we evaluated interaction between 4-HC and 5-FU. We investigated the antitumor effect of cyclophosphamide, a mother compound of 4-HC, and 5-FU against L1210 ascites tumor in B6D2F1 mice. The median lifespan of the mice treated with 4-HC or 5-FU alone was 8 and 12 days, respectively. The combination of both drugs significantly extended the median lifespan to 18.5 days. The median effect plot analysis indicated a synergistic cytotoxic interaction between 5-FU and 4-HC in 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl terazolium bromide (MTT) assay. Clonogenic assay also showed that combination of 4-HC and 5-FU significantly reduced L1210 leukemic colonies to 20% of untreated control. Bone marrow cells from the mice treated with 5-FU at 150 mg/kg body weight was resistant to 4-HC at concentrations as high as 0.2 microgram/ml, which was more than 70% inhibitory concentration for colony formation in L1210 leukemic cells. Findings suggest that sequential treatment with in vivo 5-FU followed by ex vivo 4-HC could selectively enhance antitumor effects of 4-HC in tumor cells remaining in bone marrow.
Mao
X Y
XY
Department of Pediatrics, Mie University, School of Medicine, Japan.
Higashigawa
M
M
M'Soka
T
T
Shimono
Y
Y
Nagata
T
T
Inamochi
H
H
Cao
D C
DC
Hori
H
H
Kawasaki
H
H
Sakurai
M
M
D000818:Animals; D000964:Antimetabolites, Antineoplastic / Q000008:administration & dosage; D000970:Antineoplastic Agents / Q000008:administration & dosage; D000971:Antineoplastic Combined Chemotherapy Protocols / Q000008:administration & dosage; D016465:Bone Marrow Purging; D002455:Cell Division / Q000187:drug effects; D003520:Cyclophosphamide / Q000008:administration & dosage / Q000031:analogs & derivatives*; D004357:Drug Synergism; D005472:Fluorouracil / Q000008:administration & dosage; D006412:Hematopoietic Stem Cells / Q000187:drug effects; D007939:Leukemia L1210 / Q000188:drug therapy* / Q000473:pathology; D008297:Male; D051379:Mice; D008810:Mice, Inbred C57BL; D008811:Mice, Inbred DBA; D014411:Neoplastic Stem Cells / Q000187:drug effects
C093853:4-hydroxyperoxycyclophosphamide; D000964:Antimetabolites, Antineoplastic; D000970:Antineoplastic Agents; D003520:Cyclophosphamide; D005472:Fluorouracil