Variation of Cyclin B1-like Protein During the Cell Cycle of Physarum polycephalum

Physarum polycephalum L., a naturally synchronized myxomycophyta, was demonstrated to contain a cyclin B1-like protein by Western blot and immunoelectron microscopy. The content and subcellular location of the protein varied during the cell cycle. The cyclin B1-like protein was first detected in the plasmodia of S phase while it did not appear in the nuclei until late G2 phase. The content of the protein in both the plasmodia and nuclei rose gradually onwards, peaked at metaphase and disappeared abruptly at ana-telophase. The protein was found to be distributed in both the cytoplasm and nuclei in late G2 phase and metaphase. In nuclei, the protein was mainly located in the chromosomal and nucleolar areas. The results suggest that the cyclin B1-like protein of P. polycephalum begins to be synthesized at S phase, enters the nuclei at late G2 phase, accumulates in both cytoplasm and nuclei onwards and breaks down at ana-telophase. The results also suggest that the cyclin B1-like protein acts as a cytoplasmic-nuclear protein during certain phases of the cell cycle.

Bcl-1 Rearrangement and Cyclin D1 Protein Expression in Multiple Myeloma Precursor Cells

The rearrangement of Bcl-1 gene (Bcl-1/IgH rearrangement) and expression of cyclin D1 in multiple myeloma (MM) precursor cells were studied and the role of cyclin D1 in the pathogenesis of MM was investigated. The BCL-1 rearrangement and cyclin D1 protein expression in 15 cases of MM were detected. By using hemi-nested polymerase chain reaction (PCR) the genomic DNA from fresh peripheral blood and bone marrow was amplified and the expression of cyclin D1 in the smears was detected by using immunohistochemical method. Ten volunteer with normal bone marrow served as control group. The results showed Bcl-1 rearrangement was detectable in 3/15 (20 %) MM patients and cyclin D, expression in 4/15 (27 % ) MM patients. BeLl-1 rearrangement and cyclin D1 protein expression were also detected in MM precursor cells. No overexpression of cyclin D1 or the rearrangement of the BeL-1 gene was found in the 10 volunteers. It was concluded that Bel-1 rearrangement and cyclin D1 protein overexpression were detected in MM precursor cells, speculating that overexpression of cyclin D1 protein may play an initial (critical) role in the pathogenesis of MM.

EXPRESSION OF p16,CYCLIN D1 AND RB PROTEIN IN GASTRIC CARCINOMA AND PREMALIGNANT LESIONS

Objective: To investigate the expression of p16, cyclin D1 and Rb protein in gastric carcinoma and premalignant lesions including dysplastic gastric mucosa and intestinal metaplasia gastric mucosa. Methods: Using SP immunohistochemical methods, the expression of pl6, cyclin D1 and Rb proteins was detected in 10 specimens of normal gastric mucosa, 15 specimens of dysplastic gastric mucosa, 15 specimens of intestinal metaplasia gastric mucosa, 30 specimens of gastric carcinoma. The clinical characteristics of the 30 patients with gastric carcinoma were analysed to explore the relationship between the parameter detected and biological action of gastric cancer. Results: Expression of p16 protein was detected in 90% of normal gastric mucosa, 86.67% of dysplastic gastric mucosa, 86.67% of intestinal metaplasia gastric mucosa, 36.67% of gastric carcinoma. The positive rate of p16 protein expression in gastric carcinoma is significantly lower than that in normal gastric mucosa and gastric premalignant lesions mucosa (P<0.01). Expression of cyclin D1 protein was detected in 10% of normal gastric mucosa, 20% of dysplastic gastric mucosa, 20% of intestinal metaplasia gastric mucosa, 53.33% of gastric carcinoma. The positive rate of cyclin D1, protein expression in gastric carcinoma is significantly higher than that in normal gastric mucosa and gastric premalignant lesions mucosa (P<0.05). Expression of Rb protein was detected in 90% of normal gastric mucosa, 80% of dysplastic gastric mucosa, 80% of intestinal metaplasia gastric mucosa, 50% of gastric carcinoma. The positive rate of Rb protein expression in gastric carcinoma is significantly lower than that in normal gastric mucosa (P<0.05). The expression of p16, cyclin D1 gene were associated with the degree of differentiation of gastric carcinoma, lymphnodes metastasis and distant metastasis. Conclusion: p16, Cyclin D1 and Rb gene play important role in gastric carcinoma genesis. The expression of p16, cyclin D1 and Rb gene have some value to the diagnosis at earlier stage of gastric cancer. Detection of expression of p16, cyclin D1 gene would be helpful to judge the prognosis of gastric cancer.

Effects of estradiol on cell cycle and cyclin proteins of vascular smooth muscle cells in rats

To study the effects of 17β-estradiol(E2) on the growth of cultured rat vascular smooth muscle cells (VSMC).Methods The cell cycle and the expressions of Cyclin D1 and CDK4 proteins were examined by flow cytometry in VSMC cultured in different concentrations (0～100 nmol/L) of 17β-estradiol with or without serum.Results Under serum-stimulating conditions,17β-estradiol(1,10,100 nmol/L) promoted VSMC proliferation by accelerating their cell cycle progression from G1 to S phases,and the cell rates at S were (31.89±9.14)%(35.90±4.59)% and (30.77±1.20)% respectively,significantly higher than the corresponding values of control cells (21.63±1.80)%.This was accompanied by the significantly increased expression of Cyclin D1 and CDK4 proteins.In the cultures without serum,however,high concentrations (10,100 nmol/L) of E2 induced a cell cycle arrest at G1 phase,which was characterizsed by decreased cell rates at S phase [(9.93±1.43)% and (8.76±1.80)% respectively,P<0.05] as compared with the corresponding control values and a down-regulation of expressions of Cyclin D1 and CDK4 proteins.Conclusion E2 can either promote or inhibit VSMC proliferation depending upon the presence or absence of serum mitogens.The underlying mechanism may be associated with the hormone’s action on the expression of Cyclin D1 and CDK4 which act as the G1 phase regulators.4 refs.

The expressions of Pin1, β-catenin and cyclin D1 in elderly lung carcinomas and their significance

Objective： To investigate the expressions and correlations of Pin1, β-catenin and cyclin D1 in elderly lung carcinomas. Methods： The expressions of Pin1, β-catenin and cyclin D1 were examined in the specimens of 92 elderly lung carcinomas and 10 normal lung tissues by immunohistochemistry and explored the relationship between the expression levels and clinicopathological factors. Results： （1） The overexpression of Pin1 and cyclin D1 in lung carcinomas was 46 （50%） cases and 60 （65.22%） cases respectively and 56 （60.82%） cases showed positive immunoreactivity for 13-catenin in the nuclear and （or） cytoplasmic fraction in tumor tissues. In normal tissue, the expressions of Pin1 and cyclin D1 were negative, the expression of β-catenin was lied in cell membrane. （2） In lung carcinomas the expressions of Pin1, β-catenin and cyclin D1 correlated with tumor differentiation （P 〈 0.05）. The pesitive expression rate and intensity of Pin1 correlated with tumor stage （P = 0.032） and lymph node positive disease （P = 0.041）. The expression of β-catenin correlated with lymph node positive disease （P = 0.012）. （3） High expression levels of Pin1 correlated with aberrant I]-catenin expression （P = 0.000） but did not show a correlation with cyclin D1 （P = 0.157）. Conclusion： In elderly lung carcinomas, the positive expression of Pin1 causes abnormal accumulation of β-catenin and actives its target gene, however, this target gene was not cyclin DI. The detection of Pin1 expression had some clinical significance in estimating prognosis of elderly patient with lung carcinomas.

BCL-1 Rearrangement in Acute Lymphocytic Leukemia and Its Clinical Significance

BCL 1 rearrangement (BCL 1/IgH gene rearrangement) in acute lymphocytic leukemia and its clinical significance was investigated. In 38 patients with acute lymphocytic leukemia (ALL), the genomic DNA of mononuclear cells isolated from peripheral blood and bone marrow was amplified by using hemi nested polymerase chain reaction (PCR) technique and the expression of cycline D1 protein of mononuclear cells was detected by using immunohistochemical method. Ten patients with acute granulocytic leukemia, 2 with chronic granulocytic leukemia and 10 with normal bone marrow served as control group. The results showed that BCL 1 rearrangement was detectable in 3 of 38 ALL patients (7.9 %) and cyclin D1 protein positive expression was detected in 4 ALL patients (10 5 %). Three ALL patients with BCL 1 rearrangement were all B cell leukemia (B ALL) and accompanied by cyclin D1 protein expression. No BCL 1/IgH rearrangement or cyclin D1 protein expression was detected in 12 patients with granulocytic leukemia and 10 cases of normal bone marrow. Leukocyte counts in peripheral blood of B ALL patients with BCL 1 rearrangement and(or) cyclin D1 protein expression were significantly increased and the patients had bad reaction to chemotherapy. It was concluded that: 1) BCL 1/IgH gene rearrangement were detected in acute B lymphocytic leukemia; 2) B ALL patients with BCL 1 rearrangement and(or) cyclin D1 protein expression had poor prognosis.

THE OVEREXPRESSION AND SIGNIFICANCE OF CYCLIN D1 AND P53 IN CERVICAL SQUAMOUS CELL CARCINOMAS

Objective To investigate the significance of overexpresson of cyclin D1 and P53 protein in cervical squamous cell carcinomas.Methods Fifty cases of invasive cervical squamous cell carcinomas and 10 cases of normal cervical squamous epithelia were investigated with immunihistochemical technique. Results The overexpression of cyclin D1 and P53 in invasive cervical carcinomas was 70% and 50%, respectively. There was no overexpression of them in the control group. The overexpression of cyclin D1 in grade Ⅱ and Ⅲ was much higher than that in gradeⅠ(P<0.05). The overexpresson of cyclin D1 in stage Ⅲ of cervical carcinoma was significantly higher than that in stage Ⅱ (P<0.05). The overexpression of P53 in grade Ⅱ and grade Ⅲ of cervical carcinoma was remarkably higher than that in grade Ⅰ (P<0.05).Conclusion The action point of both cyclin D1 and P53 may be at G1/S transition. The overexpression of them was associated with development and progression of cervical carcinoma probably in different mechanisms and different pathways.

Changes of the expression of CCNL2 gene during the differentiation of P19 cells to cardiac myocytes

Objective： To investigate the changes of cyclin L2（CCNL2） gene mRNA and protein during the differentiation of P19 cells to cardiac myocytes, and to explore the relationship between CCNL2 gene and the differentiation of cardiac myocytes. Methods： P19 cells were cultured with 0.9% DMSO for 18 days. Western blots of cardiac troponin I （cTnI） were used to identify cell differentiation. Total RNA was extracted from P19 cells during the process of differentiation at various time points：pre-differentiation（Day 0）, and Day 1 to Day 18. The expression levels of CCNL2 gene mRNA and protein were evaluated by RT-PCR and Western blot, respectively. Results： After being induced to differentiate by DMSO for 4 days in suspension, spontaneously and rhythmically beating ceils were seen at 8 day, which were cTnI-positive. In P19 cells, both the expression level of CCNL2 gene mRNA and protein were gradually down-regulated. Conclusion： Both the expression of CCNL2 gene and protein were down-regulated during the process of the differentiation of P19 cells into cardiac myocytes, suggesting a possible role for this cyclin in their differentiation.