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Updated: Aug 21, 2026

Studying Proteolysis of Cyclin B at the Single Cell Level in Whole Cell Populations
Published on: September 17, 2012
[Promotive effect of decreased cyclin E threshold on cell proliferation]
Ji-Chao Qin1, Xiao-Xi Chen, De-Ding Tao
1Center of Gastroenterological Surgery/Cancer Research Institute, Tongji Hospital, Tongji Medical College, University of Huazhong Science and Technology, Wuhan, Hubei 430 030, P.R. China.
Background & 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.
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