Prominent induction of cyclin B1 in G2/M renal cancer cells with butyrolactone 1.
BACKGROUND
Butyrolactone 1 (BL) is a cyclin dependent kinase (CDK) inhibitor derived from Aspergillus terreus. None of the present drugs are effective for the treatment of renal cell carcinoma. The use of BL is expected to promote a new type therapy of renal cancer.


METHODS
We investigated three human renal cancer cell lines: ACHN, OS-RC-2 and RCC10RGB, using 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay and two-color flow cytometry. Simultaneous measurements of DNA content and cyclin expression allowed us to perform cell cycle specific analysis. Western blot analysis was performed using ACHN to represent cell lines.


RESULTS
BL inhibited cell proliferation and caused cell accumulation at G2/M phase associated with the emergence of the third peak. Moreover, BL induced cyclin B1 over-expression in G2/M cells. These changes were quite definite, whereas cyclins D1, E and A showed no changes at all. Cyclin B1 accumulation was confirmed by western blot analysis. The chronological observation revealed that the emergence of the third peak preceded the regression of the increased cyclin B1 positive G2/M cells. These results suggested that BL accelerated cyclin B1 accumulation in G2/M cells, which then shifted to G1 phase without cell division. New G1 cells started DNA synthesis most likely as endoreduplication to form the third peak and the mechanism of cyclin B1 accumulation converted into down-regulation.


CONCLUSIONS
BL induced significant cell kinetic interference in the tested human renal carcinoma cell lines. This might indicate the possibility of a new medical treatment modality for renal cancer.
Kasuya
Yutaka
Y
Department of Urology, University of Tokyo, Tokyo, Japan. kasuya@tmig.or.jp
Hosaka
Yoshio
Y
Matsushima
Hisashi
H
Goto
Toshitaka
T
Kitamura
Tadaichi
T
Okuyama
Akira
A
D015107:4-Butyrolactone / Q000031:analogs & derivatives* / Q000494:pharmacology*; D015153:Blotting, Western; D002453:Cell Cycle / Q000502:physiology; D045744:Cell Line, Tumor; D002470:Cell Survival; D019926:Cyclin B / Q000378:metabolism*; D056744:Cyclin B1; D018844:Cyclin-Dependent Kinases / Q000037:antagonists & inhibitors*; D016213:Cyclins / Q000378:metabolism; D004273:DNA, Neoplasm / Q000378:metabolism; D004791:Enzyme Inhibitors / Q000494:pharmacology*; D006801:Humans; D007680:Kidney Neoplasms / Q000378:metabolism* / Q000473:pathology / Q000503:physiopathology
C534699:CCNB1 protein, human; D019926:Cyclin B; D056744:Cyclin B1; D016213:Cyclins; D004273:DNA, Neoplasm; D004791:Enzyme Inhibitors; C082868:butyrolactone I; D018844:Cyclin-Dependent Kinases; D015107:4-Butyrolactone