Standard and quantitative analysis of cyclin E threshold by cyclin E/DNA multiparameter flow cytometry / 华中科技大学学报（医学）（英德文版）

The threshold of cyclin E expression at G1/S boundary is a characteristic feature of cell cycle progressing. In this study, we tried to develop a quantitative approach to analyze cyclin E threshold by multiparameter flow cytometry. The expression of cyclin E in exponentially growing MOLT-4 cells was detected under different photomultiplier tube (PMT) voltages by cyclin E/DNA multiparameter flow cytometry. Additionally, cyclin E was detected in cells which were treated with caffeine and cycloheximide (CHX) under the same PMT voltage. Moreover, the expression of cyclin E in MOLT-4 cells was compared with that in JURKAT cells. Cyclin E threshold was quantified by formula B2/AxC (A, B, C indicates the minimum, threshold, and maximum of cyclin E fluorescence intensity, respectively). Results showed that in MOLT-4 cells, cyclin E threshold calculated by formula B2/AxC was invariable under different PMT settings. It was decreased in cells treated with caffeine and remained changeless in cells treated with cycloheximide. Cyclin E threshold in JURKAT cells was much lower than that in MOLT-4 cells. It was suggested that Formula B2/AxC we firstly set up could be used to analyze cyclin E expression threshold quantitatively.

Cyclin E, p27 and Mutant p53 do not Predict the Prognosis in AJCC Stage II Colorectal Carcinomas / 대한소화기학회지

BACKGROUND/AIMS: Carcinogenesis is characterized by the abnormal regulation of cell cycle. The abnormal expression of the regulators of cell cycle may be related to the prognosis. Since the clinical significance of the expression of the three proteins in colorectal carcinomas is still controversial, we evaluated the prognostic value of the expression of cyclin E, p27 and mutant p53 in stage II colorectal cancer. METHODS: The expression levels of cyclin E, p27 and mutant p53 proteins in 41 patients with stage II colorectal carcinomas were analyzed by immunohistochemistry. RESULTS: In the univariate analysis, the level of CEA at diagnosis was associated with disease relapse. In the multivariate analysis, the clinicopathological variables such as age, gender, site of primary tumor, tumor size, state of tumor differentiation and preoperative plasma CEA level were not associated with disease relapse. When Kaplan-Meier survival curves were constructed to determine the prognosis, cyclin E, p27 and mutant p53 expressions did not predict poor prognosis. CONCLUSIONS: Our results suggested that the expression of cyclin E, p27 and mutant p53 proteins did not predict the clinical outcome in the stage II colorectal carcinomas.

Cell cycle regulators during human atrial development

OBJECTIVES: The molecular mechanisms that regulate cardiomyocyte cell cycle and terminal differentiation in humans remain largely unknown. To determine which cyclins, cyclin dependent kinases (CDKs) and cyclin kinase inhibitors (CKIs) are important for cardiomyocyte proliferation, we have examined protein levels of cyclins, CDKs and CKIs during normal atrial development in humans. METHODS: Atrial tissues were obtained in the fetus from inevitable abortion and in the adult during surgery. Cyclin and CDK proteins were determined by Western blot analysis. CDK activities were determined by phosphorylation amount using specific substrate. RESULTS: Most cyclins and CDKs were high during the fetal period and their levels decreased at different rates during the adult period. While the protein levels of cyclin D1, cyclin D3, CDK4, CDK6 and CDK2 were still detectable in adult atria, the protein levels of cyclin E, cyclin A, cyclin B, cdc2 and PCNA were not detectable. Interestingly, p27KIP1 protein increased markedly in the adult period, while p21CIP1 protein in atria was detectable only in the fetal period. While the activities of CDK6, CDK2 and cdc2 decreased markedly, the activity of CDK4 did not change from the fetal period to the adult period. CONCLUSION: These findings indicate that marked reduction of protein levels and activities of cyclins and CDKs, and marked induction of p27KIP1 in atria, are associated with the withdrawal of cardiac cell cycle in adult humans.