Quantification of DNA-associated proteins inside eukaryotic cells using single-molecule localization microscopy.

Development of single-molecule localization microscopy techniques has allowed nanometre scale localization accuracy inside cells, permitting the resolution of ultra-fine cell structure and the elucidation of crucial molecular mechanisms. Application of these methodologies to understanding processes underlying DNA replication and repair has been limited to defined in vitro biochemical analysis and prokaryotic cells. In order to expand these techniques to eukaryotic systems, we have further developed a photo-activated localization microscopy-based method to directly visualize DNA-associated proteins in unfixed eukaryotic cells. We demonstrate that motion blurring of fluorescence due to protein diffusivity can be used to selectively image the DNA-bound population of proteins. We designed and tested a simple methodology and show that it can be used to detect changes in DNA binding of a replicative helicase subunit, Mcm4, and the replication sliding clamp, PCNA, between different stages of the cell cycle and between distinct genetic backgrounds.

Identification of biomarkers and pathway-related modules involved in ovarian cancer based on topological centralities.

PURPOSE: The present study was designed to explore the significant biomarkers and pathway-related modules for predicting the effects of eribulin relative to paclitaxel in ovarian cancer. METHODS: The gene expression data E-GEOD-50831 were downloaded from the European Bioinformatics Institute (EBI) database. Differentially expressed genes (DEGs) were screened. Subsequently, differential coexpression network was constructed. Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway analysis and pathway-related modules mining were conducted. Topological centralities (degree, betweenness, closeness and stress) analyses for coexpression network and pathway-related modules were performed to explore hub genes and the most significant pathways. Then, we verified our findings in an independent sample set via RT-PCR and Western blotting. RESULTS: Centralities results of ESCO1, CDC27and MCM4 ranked the top five. Moreover, among the top 10% hub genes, CDC27, MCM4 and SOS1 were pathway-enriched genes in two networks. A total of 5 and 6 pathway-related modules were obtained under two drugs treatment. Based analyses of degree, betweenness and other centralities, DNA replication pathway-related module was the most significant under paclitaxel treatment, while cell cycle pathway-related module was the most significant under eribulin treatment. RT-PCR and Western blotting results were consistent with the bioinformatics results. The expression level of MCM4 was remarkably decreased under eribulin treatment relative to paclitaxel. CONCLUSIONS: The inhibition of ovarian cancer growth by paclitaxel and eribulin might be connected with downregulation of cell cycle and DNA replication pathway. Moreover, MCM4 signature might be a potential biomarker to predict the effect of eribulin in ovarian cancer.

Comparative Study of the Minichromosome Maintenance Proteins Complex (MCM 4/5/6) in Ameloblastoma and Unicystic Ameloblastoma.

INTRODUCTION: Solid/conventional ameloblastoma (AM) and unicystic ameloblastoma (UAM) are the most frequent benign epithelial odontogenic tumors located in the maxillary region, and their treatment usually consists of extensive surgical resection. Therefore, it is relevant to study molecular markers to better understand the biological behavior of these tumors. The aim of this study was to describe and compare the expression of proteins related to cellular proliferation: Ki-67 and MCM4-6 complex. MATERIALS AND METHODS: An immunohistochemistry technique was performed, with antibodies against Ki-67, MCM4, MCM5, and MCM6, in 10 AM and 10 UAM tumors. The results were quantified using label index and analyzed statistically. RESULTS: AM and UAM had greater expression of MCM6, followed by MCM5, MCM4, and Ki-67 ( P < .05). Immunoexpression of Ki-67 and MCM5 was exclusively nuclear, whereas the expression of MCM4 and MCM6 was nuclear and cytoplasmic. CONCLUSION: The results suggest that MCM5 is a trustable cell proliferation marker with higher sensitivity compared with Ki-67 and may be useful to predict the biological behavior of AM and UAM. Despite this, further studies are necessary, including a correlation with clinical parameters to confirm these findings.

MCM4 and MCM7, potential novel proliferation markers, significantly correlated with Ki-67, Bmi1, and cyclin E expression in esophageal adenocarcinoma, squamous cell carcinoma, and precancerous lesions.

Minichromosomal maintenance (MCM) proteins are participants of DNA replication and may represent more accurate markers in determining the proliferative fraction within a tumor than proliferative marker Ki-67. Our study investigated the correlation between MCM4 and MCM7 expression and Ki-67, Bmi1, and cyclin E expression in esophageal adenocarcinoma, squamous cell carcinoma, and precancerous lesions. MCM4 and MCM7 expression had similar distribution as Ki-67 and Bmi1 expression in esophageal carcinoma and precancerous lesions. The mean percentage of MCM4, MCM7, and Ki-67 expression increased from squamous epithelium (5.5%, 7.3%, and 5.9%, respectively), to columnar cell metaplasia (11.2, 13.5%, and 3.4%), Barrett's esophagus (27.7%, 35.3%, and 8.3%), low-grade dysplasia (42.6%, 52.2%, and 12.9%), high-grade dysplasia (63.2%, 77.7%, and 29.6%), adenocarcinoma (61.3%, 75.5%, and 24.5%), and squamous cell carcinoma (74.1, 85.4%, and 36.3%). The percentages of MCM4 and MCM7 expression were significantly higher than Ki-67 expression. Using univariate analysis we found a high percentage of MCM4 expression (>70%) to be significantly associated with lymph node metastasis and shorter survival in the adenocarcinoma group. We also demonstrated the percentage of MCM4 and MCM7 expression to be significantly correlated with Ki-67, Bmi1, and cyclin E expression in esophageal carcinoma and precancerous lesions. MCM4 and MCM7 may serve as more sensitive proliferative markers for the evaluation of esophageal lesions.