Expression Of Minichromosome Maintenance Protein Research Articles

Minichromosome maintenance protein 5 - a promising prognostic marker of oral epithelial dysplasias and oral squamous cell carcinomas.

Early diagnosis is the single most effective means of reducing the mortality rate of oral cancer. This study was undertaken to assess the expression of minichromosome maintenance protein 5 (MCM5) in oral epithelial dysplasias and oral squamous cell carcinomas (OSCCs) and to evaluate their possible role as a biomarker for early diagnosis and prognosis of OSCC. A retrospective cross-sectional study. The study was conducted to assess the expression of MCM5 immunohistochemically in the tissue samples of oral epithelial dysplasias (n = 27) and OSCCs (n = 30) diagnosed between 2014 and 2019. The difference in the mean nuclear labelling index (LI) between the groups and the subgroups was analysed statistically using the Kruskal-Wallis test and the post hoc test, and the Dunn-Bonferroni multiple comparison analysis was conducted for pairwise comparison between the four main groups and the subgroups. The association between mean MCM5 LI and clinicopathological parameters was analysed using Spearman's rank correlation coefficient. A progressive increase in the nuclear expression of MCM5 protein (P-value <0.001) was noticed from normal oral mucosa through oral epithelial hyperplasia and oral epithelial dysplasia to OSCC. A significant correlation was also observed between the mean nuclear MCM5 LI of OSCC and TNM staging (R2 = 0.268, P = 0.029). Our findings suggest that MCM5 may be of great value in assessing the malignant potential of dysplastic lesions and may serve as biomarker of utility in the early diagnosis and prognosis of OSCC.

Cedrol, a Sesquiterpene Isolated from Juniperus chinensis, Inhibits Human Colorectal Tumor Growth associated through Downregulation of Minichromosome Maintenance Proteins.

Cedrol, a sesquiterpene alcohol, isolated from Juniperus chinensis has been reported to inhibit minichromosome maintenance (MCM) proteins as cancer biomarkers in human lung cancer in vitro. In the present study, we investigated the anti-cancer activity of cedrol in vitro and in vivo using human colorectal cancer HT29 cells and a human colorectal tumor xenograft model. Cedrol inhibited MCM protein expression and cell growth in HT29 cells, which are associated with G1 arrest and the induction of apoptosis. We demonstrated that cedrol effectively reduced HT29 tumor growth without apparent weight loss in a human tumor xenograft model. Compared with vehicle- and adriamycin-treated tumor tissues, cedrol induced changes in the tumor tissue structure, resulting in a reduced cell density within the tumor parenchyma and reduced vascularization. Moreover, the expression of MCM7, an important subunit of MCM helicase, was significantly suppressed by cedrol in tumor tissue. Collectively, these results suggest that cedrol may act as a potential anti-cancer agent for colorectal cancer by inhibiting MCM protein expression and tumor growth.

Expression of Minichromosome Maintenance Protein 2 (MCM2) in Oral Epithelial Dysplasia and Oral Squamous Cell Carcinoma: A Systematic Review.

The online version contains supplementary material available at 10.1007/s12070-022-03296-7.

Induction of Cell Cycle Arrest, Apoptosis, and Reducing the Expression of MCM Proteins in Human Lung Carcinoma A549 Cells by Cedrol, Isolated from Juniperus chinensis.

Proteins related to DNA replication have been proposed as cancer biomarkers and targets for anticancer agents. Among them, minichromosome maintenance (MCM) proteins, often overexpressed in various cancer cells, are recognized both as notable biomarkers for cancer diagnosis and as targets for cancer treatment. Here, we investigated the activity of cedrol, a single compound isolated from Juniperus chinensis, in reducing the expression of MCM proteins in human lung carcinoma A549 cells. Remarkably, cedrol also strongly inhibited the expression of all other MCM protein family members in A549 cells. Moreover, cedrol treatment reduced cell viability in A549 cells, accompanied by cell cycle arrest at the G1 phase, and enhanced apoptosis. Taken together, this study broadens our understanding of how cedrol executes its anticancer activity while demonstrating that cedrol has potential application in the treatment of human lung cancer as an inhibitor of MCM proteins.

Bioinformatics analysis of the transcriptional expression of minichromosome maintenance proteins as potential indicators of survival in patients with cervical cancer

BackgroundAs major regulators of DNA replication in eukaryotes, minichromosome maintenance (MCM) proteins play an important role in the initiation and extension of DNA replication. MCMs and their related genes may be new markers of cell proliferation activity, which is of great significance for the diagnosis and prognosis of cervical cancer.MethodsTo explore the role of MCMs and their related genes in cervical cancer, various bioinformatics methods were performed. First, the ONCOMINE and UALCAN databases were used to analyze the mRNA expression of different MCMs. The Human Protein Atlas database was used to analyze the protein expression of MCMs in normal and tumor tissues. The potential clinical value of MCMs was evaluated using the UALCAN, Kaplan-Meier plotter and cBioPortal databases. Then, the related genes and key coexpressed genes of MCMs were screened using GEPIA2 and cBioPortal analysis. For these genes, we used Metascape and the DAVID database to perform Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway enrichment analyses, construct the related molecular interaction network, and obtain the key subnetworks and related hub genes. The Kaplan-Meier plotter database was used for survival analysis of cervical cancer patients to evaluate and predict the potential clinical value of the hub genes. Moreover, multiple gene comparisons of the expression of MCMs and related genes in different cancer types also showed the clinical significance of these potential targets.ResultsThe mRNA and protein expression of MCMs increased in tumor tissue. Overexpression of MCM2/3/4/5/6/7/8/10 was found to be significantly associated with clinical cancer stage. Higher mRNA expression levels of MCM3/5/6/7/8 were found to be significantly associated with longer overall survival, and higher mRNA expression of MCM2/3/4/5/6/7/8 was associated with favorable OS. In addition, a high mutation rate of MCMs (71%) was observed. MCM2, MCM4, MCM8, MCM3 and MCM7 were the five genes with the most genetic alterations. In addition, the coexpressed genes and related genes of MCMs were successfully screened for enrichment analysis. These genes were significantly enriched in important pathways, such as the DNA replication, cell cycle, mismatch repair, spliceosome, and Fanconi anemia pathways. A protein-protein interaction network was successfully constructed, and a total of 13 hub genes (CDC45, ORC1, RPA1, CDT1, TARDBP, RBMX, SRSF3, SRSF1, RFC5, RFC2, MSH6, DTL, and MSH2) from 4 key subnetworks were obtained. These genes and MCM2/3/4/5/6/7/8 might have potential clinical value for the survival and prognosis of cervical cancer patients.ConclusionsThese findings promoted the understanding of the MCM protein family and clinically related molecular targets for cervical epithelial neoplasia and cervical cancer. Our results were helpful to evaluate the potential clinical value of MCMs and related genes in patients with cervical cancer.

Prognostic importance of expression of mini-chromosome maintenance proteins (MCMs) in patients with nasopharyngeal cancer treated with curative radiotherapy

ObjectiveThe prognostic importance of minichromosome maintenance complex expression in nasopharyngeal cancer is still unknown. We aimed to find whether minichromosome maintenance complex 2–7 expression may potentially be used to predict the prognosis of nasopharyngeal cancer patients treated with definitive radiotherapy. MethodsBetween April 2007 and July 2020, patients with nasopharyngeal cancer treated with radiotherapy were identified. Immunohistochemical analysis was performed on formalin-fixed paraffin-embedded tissues of cases. A single pathologist analyzed the histologic specimens of all patients. ResultsTotally, 67 patients were included. The median followup was 75.3 months. Higher tumor (T) stage was correlated with minichromosome maintenance complex 2 overexpression. Minichromosome maintenance complex s expression was also associated with histopathologic subgroups. According to univariate analysis, AJCC stage, histopathological subgroups, tumor response after treatment, minichromosome maintenance complex 2, 3, 5, 6 and 7 expression were the prognostic factors that predict overall survival. According to multivariate analysis minichromosome maintenance complex 7 expression was the only prognostic marker for both progression-free survival and overall survival. ConclusionThe overexpression of minichromosome maintenance complex 2, 3, 5, 6 and 7 indicated bad prognosis. Minichromosome maintenance complex 7 was an independent prognostic factor for survival outcomes in nasopharyngeal cancer and may be a potential therapeutic target for treatment.

KIF15 Expression in Tumor-associated Monocytes Is a Prognostic Biomarker in Hepatocellular Carcinoma.

Kinesin family member 15 (KIF15) participates in the transport of macromolecules in essential cellular processes. In this study we evaluated the clinical relevance of KIF15 expression in hepatocellular carcinoma (HCC). Association between KIF15 expression and clinical outcomes in HCC patients was analyzed using three independent cohorts. Localization of KIF15 expression was assessed by immunohistochemical analysis. Co-culture experiments were performed using healthy donor peripheral blood mononuclear cells (PBMC) and HCC cell lines. Immunohistochemical analysis showed that KIF15 was mainly expressed in inflammatory monocytes around cancer cells. Multivariate analysis indicated high KIF15 expression was an independent poor prognostic factor for survival. HCC cells with high expression of minichromosome maintenance protein 2 (MCM2) were located close to KIF15-expressing inflammatory monocytes. The proliferation ability of HCC cells was increased by co-culture with PBMC. High KIF15 expression in inflammatory monocytes in tumor tissues may serve as a prognostic marker for poor outcome in HCC.

Prognostic significance of minichromosome maintenance mRNA expression in human lung adenocarcinoma.

The minichromosome maintenance (MCM) gene family plays an essential role in DNA replication and cell cycle progression. However, MCM gene expression has not been well-studied in lung adenocarcinoma (LUAD). In the present study, the expression, prognostic value and functions of MCMs in LUAD were investigated using several databases and bioinformatic tools, including Oncomine, GEPIA, cBioPortal, CancerSEA and Kaplan-Meier plotter. It was demonstrated that the mRNA expression of MCM2, MCM4 and MCM10 were significantly increased in patients with LUAD. High mRNA expression of MCM2-5, MCM8 and MCM10 were associated with poor overall survival and progression-free survival. High MCM4 expression was associated with adverse post-progression survival. In addition, the Human Protein Atlas database showed that MCM protein expression was consistent with the mRNA expression. These results demonstrate that MCM2, MCM4 and MCM10 are potential prognostic markers and therapeutic targets for LUAD.

Abstract 3089: YAP and TAZ induce MCM protein expression to facilitate tumor-supporting properties in liver cancer

Abstract Overexpression and nuclear enrichment of the Hippo pathway-regulated transcriptional co-activator Yes-Associated Protein (YAP) is frequently detected in human hepatocellular carcinoma (HCC) and correlates with poor clinical outcome of cancer patients1. In mice, inducible overexpression of the constitutively active isoform YAPS127A induces hepatocellular proliferation leading to hepatomegaly followed by tumor formation within 12-15 weeks. How oncogenic YAP and its paralogue TAZ (syn. WWTR1, WW Domain Containing Transcription Regulator 1) induce uncontrolled proliferation in liver cells is not known, yet. Analysis of expression profiling data, derived from human liver cancer cells after siRNA-mediated inhibition of endogenous YAP, revealed that the Minichromosome Maintenance (MCMs) family members MCM2-7 were positively regulated. MCMs are key components of the pre-replication complex and involved in the formation of the replication fork, which is essential for efficient DNA duplication followed by mitosis2. We confirmed that silencing of YAP and TAZ by independent siRNAs reduced the mRNA and protein expression of MCM2-7 in liver cancer cell lines. In vitro analyses revealed that transcription factors of the TEAD family were the most relevant YAP binding partners needed for the transcriptional regulation of MCMs. Using chromatin immunoprecipitation and Dual Luciferase Reporter Assay, we showed that YAP, TAZ and TEAD4 directly bound the MCM promoter. First in vitro data suggested that viability of liver cancer cells, subjected to drug induced replication stress, was exclusively reduced in cells with reduced YAP, TAZ or MCM protein expression. Administration of the YAP/TAZ/TEAD inhibitor Verteporfin reduced the expression of all MCMs in liver cancer cells. Vice versa, the overexpression of YAPS127A in transgenic mice showed significantly increased levels of the proliferation marker Ki67 and MCM2-7. Expression data from 242 HCC patients illustrated an association between YAP and MCM mRNA levels, with elevated MCMs significantly correlating with worse overall survival and early cancer recurrence3. Immunohistochemical stains of HCC tissue micro-arrays revealed a highly significant correlation between Ki67 expression, nuclear YAP overexpression and nuclear MCM2-7 enrichment. In summary, our results strongly suggest that YAP and TAZ facilitate their tumor-supporting properties through the regulation of MCM2-6, a complete protein complex. We conclude that combined inhibition of YAP and TAZ or perturbation of MCM activity might represent an efficient therapeutic approach for the treatment of a subgroup of HCC patients. 1Tschaharganeh D, et al., Gastroenterol. 2013; 2Deegan TD, et al., Curr Opin Struct Biol. 2016; 3Roessler S, et al., Cancer Res. 2010. Citation Format: Maria Knaub, Sofia Weiler, Stefan Thomann, Peter Schirmacher, Kai Breuhahn. YAP and TAZ induce MCM protein expression to facilitate tumor-supporting properties in liver cancer [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2018; 2018 Apr 14-18; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2018;78(13 Suppl):Abstract nr 3089.

Cho/Cr ratio at MR spectroscopy as a biomarker for cellular proliferation activity and prognosis in glioma: correlation with the expression of minichromosome maintenance protein 2.

Magnetic resonance (MR) spectroscopy (1H-MRS) has been demonstrated to be useful in grading glioma, but the utility in assessing cellular proliferation activity and prognosis correlated with the expression of minichromosome maintenance protein 2 (MCM2) has not been reported. To explore the correlation between proton MR spectroscopy parameters (including choline [Cho]/creatine [Cr], N-acetyl aspartate [NAA]/Cr, and Cho/NAA ratios) and the expression of MCM2 and to further evaluate whether 1H-MRS can predict cell proliferative activity and provide prognostic information in high-grade gliomas (HGGs). Forty-three patients with histopathologically confirmed gliomas were involved in this study. All patients underwent 1H-MRS examination before surgery. Proliferative activity of gliomas was evaluated by MCM2 labeling index (LI). Pearson correlation analysis and empiric receiver operating characteristic (ROC) curves were performed. The Kaplan-Meier method and Cox regression were used for survival analysis. Significant correlation was observed between the Cho/Cr ratio and MCM2 LI ( r = 0.522, P < 0.01); however, there was no correlation between MCM2 LI and the Cho/NAA or NAA/Cr ratios ( r = 0.295, P = 0.55 and r = -0.042, P = 0.788, respectively). According to ROC analysis, MCM2 LI of 50% and Cho/Cr ratio of 2.68 represented the optimized cut-off values, respectively, to distinguish longer or shorter survival than 15 months in HGGs patients. Multivariate analysis revealed that both the Cho/Cr ratio and MCM2 expression were independent prognostic markers. Cho/Cr ratio has a potential in predicting the expression of MCM2 and can evaluate cell proliferative activity noninvasively. Both the Cho/Cr ratio and MCM2 expression are independent prognostic markers in patients with HGGs.

Expression of Minichromosome Maintenance Proteins in Actinic Keratosis and Squamous Cell Carcinoma.

Minichromosome maintenance (MCM) proteins are a group of proteins involved in DNA replication and cell-cycle regulation. Because they are associated with DNA through G1 into S phase, MCM proteins are potentially specific indicators of cell proliferation that could be valuable markers of dysplasia, and preinvasive and invasive malignant tumors. To analyze MCM protein expression patterns in actinic keratosis (AK), Bowen disease (BD), and cutaneous squamous cell carcinoma (SCC), we performed immunohistochemical staining of MCM2, -5, and -7 on tissue microarray blocks from 91 AK, 50 BD, and 174 SCC samples. The distribution and semiquantitatively assessed number of positive cells were analyzed in relation to the type of the lesion and the SCC prognostic parameters (grade, diameter, and thickness). Basal expression of all 3 proteins was observed more frequently in AK, whereas the distribution in BD was predominantly diffuse (P<0.001). All 3 proteins showed peripheral distribution in most well-differentiated SCC and diffuse distribution in poorly differentiated tumors (P<0.001). Using the 50% cut-off value, there was a statistically significant difference among AK, BD, and SCC (P<0.001). In addition, all MCM proteins showed highly significant differences (P<0.001) between well-differentiated SCC and both moderately and poorly differentiated SCC. The diffuse distribution and 50% cut-off value of positive cells revealed statistically significant associations of all MCM proteins with SCC thicker than 6 mm. Our results suggest a role for MCM proteins in the progression of in situ keratinocytic lesions and their association with high-risk features in SCC.

Deguelin inhibits proliferation and regulates the expression of MCM3-CDC45 in MCF-7 and H1299 cells in vitro

To observe the effects of deguelin on the proliferation of breast cancer MCF-7 cells and lung cancer H1299 cells in vitro and the expression of minichromosome maintenance protein 3 (MCM3) and CDC45 in the cells. MTT assay was used to evaluate the proliferation of MCF-7 and H1299 cells exposed to different concentrations of deguelin for 48, 72 or 96 h. The growth of the cells was observed microscopically and the changes of MCM3 and CDC45 expressions in MCF-7 and H1299 cells following deguelin treatment were detected with fluorescence quantitative PCR. The proliferation of MCF-7 cells was significantly inhibited by exposure to 0.25, 0.5, 1, 5, 10, 30, and 50 µmol/L deguelin for 48, 72, and 96 h in a concentration- and time-dependent manner. In MCF-7 cells, the IC50 of deguelin at 48, 72, and 96 h was 9, 3, and 2 µmol/L, respectively. Deguelin treatments of H1299 cells at 0.5, 1, 5, 10, 30, 50, and 100 µmol/L also resulted in a concentration- and time-dependent inhibition of the cell growth with an IC50 at 96 h of 2 µmol/L. Optical microscopy of the cells revealed a decreased number of viable cells with obvious cell shrinkage following deguelin treatments. The expression of MCM3 and CDC45 were significantly reduced in the cells after deguelin treatments. Deguelin can inhibit the proliferation of MCF-7 and H1299 cells in vitro and down-regulate the expression of MCM3 and CDC45 in the cells.

The expression and significance of minichromosome maintenance protein 2 in colorectal adenoma and colorectal carcinoma

Objective To explore the expression of minichromosome maintenance protein 2 (MCM2) in normal colorectal mucosa, colorectal adenomas and colorectal carcinoma, and to analyze the relationships among different histological types of colorectal adenomas and colorectal carcinoma. Methods Immunohistochemistry was used to exzamine the location and expression of MCM2 in the colorectal tissues, colorectal adenoma tissues and colorectal carcinoma tissues. Real-time fluorescent quantitative polymerase chain reaction (FQ-PCR) was used to detect MCM2 mRNA and connexin-32 mRNA expression. Results (1) Immunohistochemistry: The positive expression rate of MCM2 protein in normal colorectal mucosa, colorectal adenoma and colorectal carcinoma tissues was 16.7%, 55.0% and 80.0% respectively, with significant differences among them (P=0.031). The positive expression rate of MCM2 in tubular adenoma, mixed pattern of adenoma and villous adenoma was 40.0%, 65.0% and 75.0% respectively, also with significant differences among them (P=0.022). (2) FQ-PCR: The MCM2 mRNA expression in the normal colorectal mucosa, tubular adenoma, the mixed pattern of adenoma, villous adenoma, and colorectal carcinoma was 1.187±0.923, 4.126±1.339, 9.577±0.838, 22.150±4.077 and 48.020±4.811, respectively. The expression of MCM2 gradually increased in colorectal carcinoma, villous adenoma, the mixed pattern of adenoma, tubular adenoma, and normal colorectal mucosa (F=55.512, P=0.029). SNK multiple comparisons displayed that the differences about any two groups of the total mean showed statistical significance. Conclusion MCM2 is correlated with canceration of colorectal adenoma and the development of colorectal carcinoma. Detecting the expression of MCM2 can evaluate the progression of colorectal adenoma and the development of colorectal carcinoma. They may be the molecular biological indicators for predicting canceration of colorectal adenoma. Key words: Colorectal adenoma; Colorectal carcinoma; Immunohistochemistry; Minichromosome maintenance protein 2

DNA Replication Licensing Proteins for Early Detection of Lung Cancer

Background:To identify and characterize malignant and premalignant cells in sputum and matched tissue samples with reference to expression of minichromosome maintenance proteins (MCM2, MCM5) and cell division cycle protein 6 (CDC 6) and to assess their potential as biomarkers of premalignant and malignant lesions of the lung and associations with clinicopathological features.Methods:Expression of MCM2, MCM5 and 6 proteins in sputum samples and corresponding tissues was assessed by immunocytochemistry, and correlated with histological findings.Results:For characterization of malignant, metaplastic or dysplastic cells, CDC6 protein had the highest sensitivity of 87.7%. All the three markers together had a sensitivity of 94.4%. Furthermore these proteins could be employed to assess the proliferative potential of precancerous or atypical cells, as overexpression increasing with the stage of disease and degree of metastasis.Conclusion:The assessed markers can be utilized in routine cytopathology laboratories to supplement conventional morphological evaluation so that the sensitivity of sputum cytology can be enhanced. Potential applications in predicting the clinical behavior of lung lesions and predicting prognosis and survival deserve further attention.

Simvastatin exerts anti-hepatitis B virus activity by inhibiting expression of minichromosome maintenance protein 7 in HepG2.2.15 cells.

Simvastatin (SIM), a 3-hydroxy-3-methylglutaryl coenzymeA reductase inhibitor, has been reported to inhibit the activity of hepatitisB virus (HBV), however, the mechanism underlying its antiviral function remains unknown. Minichromosome maintenance (MCM)7, a component of the MCM complex, has been reported to act as an important host factor aiding virus genome replication in host cells. The present study demonstrated that downregulation of MCM7 inhibited the expression of proteins transferred by adenoviral vectors. This suggests an association between MCM7 and viral DNA expression. Thus, the current study aimed to investigate whether SIM affected MCM7 expression. Notably, the results of the present study indicated that following exposure to SIM the protein expression levels of MCM7 in HepG2.2.15, a human HBV‑transfected liver cell line, was decreased. In addition, the HBV DNA replication in the cell line was suppressed. As quantitative polymerase chain reaction experiments demonstrated that SIM did not downregulate the mRNA expression level of MCM7, the current study further investigated whether SIM affects the translation of MCM7. Western blot experiments indicated that SIM improved the activation of eukaryotic initiation factor‑2α (eIF2α), a protein synthesis initiation factor, and upregulated the upstream factors of eIF2α, protein kinase RNA‑like endoplasmic reticulum kinase, which is regulated by the liver kinaseB1 (LKB1)‑AMP‑activated protein kinase (AMPK) signaling pathway. These results indicated that SIM induced HBV downregulation via an MCM‑dependent mechanism, and SIM may inhibit MCM7 expression by increasing the phosphorylation of eIF2α, which is mediated by the LKB1-AMPK signaling pathway.

Androgen Receptor Represses the Expression of Minichromosome Maintenance Proteins: a Mechanism for Androgen Therapy in Castration Resistant Prostate Cancer

Standard treatment for metastatic prostate cancer is androgen deprivation therapy (ADT). Though this is often efficacious, for many patients, this invariably leads to the development of a more aggressive form of prostate cancer that is Castration Resistant Prostate Cancer (CRPC). Previous studies have shown that restoration of Androgen Receptor (AR, a member of nuclear receptor transcription factor family) activity plays a critical role in prostate cancer development and progression to CRPC. We have reported that in prostate cancer AR can function as both transcription activator and repressor. The latter suppressive function of AR is mediated by the recruitment of hypophosphorylated Retinoblastoma Protein (Rb), which results in negative regulation of the expression of Minichromosome Maintenance Proteins (MCMs). This protein family is composed of six distinct subunits (MCM2‐7) that form pre‐replication complex and are essential for replication initiation. Preliminary data of AR ChIP‐seq and Rb ChIP‐seq in CRPC cells showed the co‐binding on the promoters of MCM genes. Therefore downregulation the expression and activity of MCMs may be a potential mechanism for Rb‐dependent AR growth suppressive function in CRPC. We hypothesized that in CRPC cells, the AR activity stimulated by androgen treatment can have a repressive effect on the function of MCMs through recruitment of Rb to promoters, can subsequently suppress DNA replication process, and can thereby repress cancer cell proliferation. We alter Rb expression and phosphorylation as well as the expression of MCMs in prostate cancer cell lines (VCaP, LNCaP, and C4‐2) and then measure DNA replication by labeling newly replicated DNA with halogenated nucleotide precursors (BrdU, CldU, IdU) in conjunction with the expression level of MCMs, to determine the role of MCMs in AR mediated growth repressive function in CRPC. This AR growth repressive function may be mediated by downregulation of the expression and activity of MCMs through recruitment of hypophosphorylated Rb.Support or Funding InformationR00CA166507 (PI: Cai) 06/01/2015‐05/31/2017 (R00) NCI/NIH Molecular Basis of Androgen Receptor Mediated Gene Transcriptional Repression Objective: The aims of this project are to determine the molecular basis and functional importance for AR mediated repression of genes in prostate cancer cells. Aim 1. Determine the mechanisms of AR‐mediated repression on the subset of DNA synthesis and repair genes. Aim 2. Assess treatment with high dose androgen in combination with metabolic inhibitors on castration‐resistant PCa cell lines. Contact: Martinson O. Owusu 240‐276‐6297 martinson.owusu@mail.nih.gov

Correlation between levels of expression of minichromosome maintenance proteins, Ki-67 proliferation antigen and metallothionein I/II in laryngeal squamous cell cancer.

MCM2, MCM3 and MCM7 are minichromosome maintenance proteins found in dividing cells and they play a role in DNA synthesis. Increased MCM expression level is observed in cells of different cancer types. Additionally, metallothioneins (MT-I/II) are involved in control of cell proliferation and differentiation and changes of their expression are observed in many types of cancer. Ki-67 is known cancer cell proliferation antigen currently used in prognostic evaluation. The study material consisted of 83 laryngeal squamous cell cancer (LSCC) cases and 10 benign hypertrophic lesions of larynx epithelium as a control group. For the present study, laryngeal cancer cell line HEp-2 and human keratinocytes were employed, and to evaluate expression of all the markers, immunohistochemical method (IHC), immunofluorescence (IF) and western blot analysis were used. Statistical analysis showed strong positive correlation between expression of MCM2, MCM3, MCM7 and Ki-67 antigen in LSCC. Additionally, moderate positive correlation was observed between MCM3 and MT-I/II expression. In cancer cells, the level of expression of MCM3, MCM2, MCM7 and Ki-67 markers was increasing with the grade of LSCC malignancy. IF and western blot analysis showed higher MCM2, MCM3, MCM7 expression in HEp-2 cells in comparison to their expression in keratinocytes. MCM proteins might be useful markers of cell proliferation in LSCC.

Expression of mini-chromosome maintenance protein 7 (MCM7) in a poorly-differentiated canine prostate tumour

Expression of mini-chromosome maintenance protein 7 (MCM7) in a poorly-differentiated canine prostate tumour

Aurora kinase A outperforms Ki67 as a prognostic marker in ER-positive breast cancer

Background:Proliferation has emerged as a major prognostic factor in luminal breast cancer. The immunohistochemical (IHC) proliferation marker Ki67 has been most extensively investigated but has not gained widespread clinical acceptance.Methods:We have conducted a head-to-head comparison of a panel of proliferation markers, including Ki67. Our aim was to establish the marker of the greatest prognostic utility. Tumour samples from 3093 women with breast cancer were constructed as tissue microarrays. We used IHC to detect expression of mini-chromosome maintenance protein 2, Ki67, aurora kinase A (AURKA), polo-like kinase 1, geminin and phospho-histone H3. We used a Cox proportional-hazards model to investigate the association with 10-year breast cancer-specific survival (BCSS). Missing values were resolved using multiple imputation.Results:The prognostic significance of proliferation was limited to oestrogen receptor (ER)-positive breast cancer. Aurora kinase A emerged as the marker of the greatest prognostic significance in a multivariate model adjusted for the standard clinical and molecular covariates (hazard ratio 1.3; 95% confidence interval 1.1–1.5; P=0.005), outperforming all other markers including Ki67.Conclusion:Aurora kinase A outperforms other proliferation markers as an independent predictor of BCSS in ER-positive breast cancer. It has the potential for use in routine clinical practice.

Cell cycle regulation and proliferation in lichen sclerosus

IntroductionGenital lichen sclerosus (LS) is considered a potential precursor lesion of squamous cell carcinoma. We aimed to investigate the expression pattern of cell cycle regulators, tumour suppressor proteins and proliferation markers in genital LS as compared to extragenital LS (ELS) and healthy controls (HC). MethodsIn order to assess the expression of minichromosome maintenance protein 3 (MCM3), MCM7, Ki-67, cyclin D1, cyclin E, p16, p21, and p53, immunohistochemistry and immunofluorescence were performed on skin specimens obtained from the genital region of LS patients (short-standing LS, n=19; long-standing LS, n=15), patients with ELS (n=10), and HC (n=8). ResultsMedian protein expression of MCM3 and Ki-67 was significantly higher in LS when compared to ELS and HC. In patients with long-standing LS, the expression profiles of MCM3 and Ki-67 significantly correlated. Moreover, long-standing LS lesions showed significantly increased expression of p53 when compared to short-standing LS, ELS, and HS. Immunoreactivity of MCM7, p16, p21, cyclin D1 and cyclin E did not significantly differ between the groups. ConclusionsTumour suppressor proteins such as p53 are significantly overexpressed in genital LS when compared to extragenital disease and healthy skin. The significant p53 overexpression, particularly in long-standing genital lesions, may reflect the increased risk of malignant transformation and/or oxidative stress associated with LS. Moreover, we have demonstrated that proliferation markers such as Ki-67 and MCM3 are significantly up-regulated in genital LS as compared to controls. With regard to cell cycle regulation and proliferation rates, ELS significantly differs from its genital counterpart.