[Promotive effect of decreased cyclin E threshold on cell proliferation].
OBJECTIVE
Many studies showed that high expression of Cyclin E promotes cell proliferation, but contrary data was also reported that cell proliferation didn't decrease with low expression of Cyclin E. In addition, we observed that many tumor cells have strong capability of proliferation with low expression of Cyclins, including Cyclin E. This study was to analyze effect of reduced Cyclin E threshold on proliferation of acute lymphocyte leukemia cell line MOLT-4 to explain the above phenomena.


METHODS
We have established the model of decreased Cyclin E threshold in MOLT-4 cells by treating cells with low concentration (5 mmol/L) of caffeine for 2, and 4 h. The positive rates of proliferation cell nuclear antigen (PCNA), Ki67, and DNA strand break induction by photolysis (SBIP) were analyzed by flow cytometry.


RESULTS
MOLT-4 cells presented sharply decrease of Cyclin E threshold, and increase of positive rates of PCNA, Ki67, and SBIP after treated with caffeine, especially at 2-h point.


CONCLUSIONS
Decrease of Cyclin E threshold was accompanied by increase of cell proliferation. MOLT-4 cells may remain high proliferation capability with low level of Cyclin expression.
Qin
Ji-Chao
JC
Center of Gastroenterological Surgery/Cancer Research Institute, Tongji Hospital, Tongji Medical College, University of Huazhong Science and Technology, Wuhan, Hubei 430 030, P.R. China.
Chen
Xiao-Xi
XX
Tao
De-Ding
DD
Feng
Yong-Dong
YD
Hu
Jun-Bo
JB
Gong
Jian-Ping
JP
D002110:Caffeine / Q000494:pharmacology*; D045744:Cell Line, Tumor; D049109:Cell Proliferation / Q000187:drug effects*; D019927:Cyclin E / Q000096:biosynthesis* / Q000235:genetics; D015536:Down-Regulation / Q000187:drug effects; D016193:G1 Phase; D015973:Gene Expression Regulation, Leukemic / Q000187:drug effects; D006801:Humans; D019394:Ki-67 Antigen / Q000378:metabolism; D054198:Precursor Cell Lymphoblastic Leukemia-Lymphoma / Q000235:genetics / Q000378:metabolism* / Q000473:pathology; D018809:Proliferating Cell Nuclear Antigen / Q000378:metabolism
D019927:Cyclin E; D019394:Ki-67 Antigen; D018809:Proliferating Cell Nuclear Antigen; D002110:Caffeine