Minichromosome maintenance protein 7 as a potential prognostic factor for progression-free survival in high-grade serous carcinomas of the ovary

Prognostic and Clinical Significance of the Proliferation Marker MCM7 in Breast Cancer

INTRODUCTION

Minichromosome maintenance complex component 7 (MCM7) plays an essential role in proliferation and DNA replication of cancer cells. However, the expression and prognostic significance of MCM7 in breast cancer (BC) remain to be defined. In this study, we aimed to evaluate the role of MCM7 in BC.

METHODS

We conducted immunohistochemistry staining of MCM7 in 1,156 operable early-stage BC samples and assessed MCM7 at the transcriptomic levels using publicly available cohorts (n = 13,430). MCM7 expression was evaluated and correlated with clinicopathological parameters including Ki67 labelling index and patient outcome.

RESULTS

At the transcriptomic level, there was a significant association between high MCM7 mRNA levels and shorter patient survival in the whole cohort and in luminal BC class but not in the basal-like molecular subtype. High MCM7 protein expression was detected in 43% of patients and was significantly associated with parameters characteristic of aggressive tumour behaviour. MCM7 was independently associated with shorter survival, particularly in oestrogen receptor-positive (luminal) BC. MCM7 stratified luminal tumours with aggressive clinicopathological features into distinct prognostic groups. In endocrine therapy-treated BC patients, high MCM7 was associated with poor outcome, but such association disappeared with administration of adjuvant chemotherapy. Patients with high expression of Ki67 and MCM7 showed worst survival, while patients with double low expression BC showed the best outcome compared with single expression groups.

CONCLUSION

The current findings indicate that MCM7 expression has a prognostic value in BC and can be used to identify luminal BC patients who can benefit from adjuvant chemotherapy.

INTRODUCTION

Minichromosome maintenance complex component 7 (MCM7) plays an essential role in proliferation and DNA replication of cancer cells. However, the expression and prognostic significance of MCM7 in breast cancer (BC) remain to be defined. In this study, we aimed to evaluate the role of MCM7 in BC.

METHODS

We conducted immunohistochemistry staining of MCM7 in 1,156 operable early-stage BC samples and assessed MCM7 at the transcriptomic levels using publicly available cohorts (n = 13,430). MCM7 expression was evaluated and correlated with clinicopathological parameters including Ki67 labelling index and patient outcome.

RESULTS

At the transcriptomic level, there was a significant association between high MCM7 mRNA levels and shorter patient survival in the whole cohort and in luminal BC class but not in the basal-like molecular subtype. High MCM7 protein expression was detected in 43% of patients and was significantly associated with parameters characteristic of aggressive tumour behaviour. MCM7 was independently associated with shorter survival, particularly in oestrogen receptor-positive (luminal) BC. MCM7 stratified luminal tumours with aggressive clinicopathological features into distinct prognostic groups. In endocrine therapy-treated BC patients, high MCM7 was associated with poor outcome, but such association disappeared with administration of adjuvant chemotherapy. Patients with high expression of Ki67 and MCM7 showed worst survival, while patients with double low expression BC showed the best outcome compared with single expression groups.

CONCLUSION

The current findings indicate that MCM7 expression has a prognostic value in BC and can be used to identify luminal BC patients who can benefit from adjuvant chemotherapy.

Computational Screening of Natural Compounds for Identification of Potential Anti-Cancer Agents Targeting MCM7 Protein

Minichromosome maintenance complex component 7 (MCM7) is involved in replicative licensing and the synthesis of DNA, and its overexpression is a fascinating biomarker for various cancer types. There is currently no effective agent that can prevent the development of cancer caused by the MCM7 protein. However, on the molecular level, inhibiting MCM7 lowers cancer-related cellular growth. With this purpose, this study screened 452 biogenic compounds extracted from the UEFS Natural Products dataset against MCM protein by using the in silico art of technique. The hit compounds UEFS99, UEFS137, and UEFS428 showed good binding with the MCM7 protein with binding energy values of −9.95, −8.92, and −8.71 kcal/mol, which was comparatively higher than that of the control compound ciprofloxacin (−6.50). The hit (UEFS99) with the minimum binding energy was picked for molecular dynamics (MD) simulation investigation, and it demonstrated stability at 30 ns. Computational prediction of physicochemical property evaluation revealed that these hits are non-toxic and have good drug-likeness features. It is suggested that hit compounds UEFS99, UEFS137, and UEFS428 pave the way for further bench work validation in novel inhibitor development against MCM7 to fight the cancers.

Multi-Dimensional Scaling Analysis of Key Regulatory Genes in Prostate Cancer Using the TCGA Database

Prostate cancer (PC) is a polygenic disease with multiple gene interactions. Therefore, a detailed analysis of its epidemiology and evaluation of risk factors can help to identify more accurate predictors of aggressive disease. We used the transcriptome data from a cohort of 243 patients from the Cancer Genome Atlas (TCGA) database. Key regulatory genes involved in proliferation activity, in the regulation of stress, and in the regulation of inflammation processes of the tumor microenvironment were selected to test a priori multi-dimensional scaling (MDS) models and create a combined score to better predict the patients' survival and disease-free intervals. Survival was positively correlated with cortisol expression and negatively with Mini-Chromosome Maintenance 7 (MCM7) and Breast-Related Cancer Antigen2 (BRCA2) expression. The disease-free interval was negatively related to the expression of enhancer of zeste homolog 2 (EZH2), MCM7, BRCA2, and programmed cell death 1 ligand 1 (PD-L1). MDS suggested two separate pathways of activation in PC. Within these two dimensions three separate clusters emerged: (1) cortisol and brain-derived neurotrophic factor BDNF, (2) PD-L1 and cytotoxic-T-lymphocyte-associated protein 4 (CTL4); (3) and finally EZH2, MCM7, BRCA2, and c-Myc. We entered the three clusters of association shown in the MDS in several Kaplan-Meier analyses. It was found that only Cluster 3 was significantly related to the interval-disease free, indicating that patients with an overall higher activity of regulatory genes of proliferation and DNA repair had a lower probability to have a longer disease-free time. In conclusion, our data study provided initial evidence that selecting patients with a high grade of proliferation and DNA repair activity could lead to an early identification of an aggressive PC with a potentials for metastatic development.

Systemic Analysis of the DNA Replication Regulator MCM Complex in Ovarian Cancer and Its Prognostic Value

Microliposome maintenance (MCM) 2, MCM3, MCM4, MCM5, MCM6, and MCM7 are DNA replication regulators and are involved in the progression of multiple cancer types, but their role in ovarian cancer is still unclear. The purpose of this study is to clarify the biological function and prognostic value of the MCM complex in ovarian cancer (OS) progression. We analyzed DNA alterations, mRNA and protein levels, protein structure, PPI network, functional enrichment, and prognostic value in OC based on the Oncomine, cBioPortal, TCGA, CPTAC, PDB, GeneMANIA, DAVID, KEGG, and GSCALite databases. The results indicated that the protein levels of these DNA replication regulators were increased significantly. Moreover, survival analysis showed a prognostic signature based on the MCM complex, which performed moderately well in terms of OS prognostic prediction. Additionally, protein structure, functional enrichment, and PPI network analyses indicated that the MCM complex synergistically promoted OC progression by accelerating DNA replication and the cell cycle. In conclusion, our study suggested that the MCM complex might be a potential target and prognostic marker for OC patients.

Computational assessment of MCM2 transcriptional expression and identification of the prognostic biomarker for human breast cancer

Minichromosome maintenance protein 2 (MCM2) is a highly conserved protein from the MCM protein family that plays an important role in eukaryotic DNA replication as well as in cell cycle progression. In addition, it maintains the ploidy level consistency in eukaryotic cells, hence, mutations or alteration of this protein could result in the disintegration of the fine-tuned molecular machinery that can lead to uncontrolled cell proliferation. Moreover, MCM2 has been found to be an important marker for progression and prognosis in different cancers. Therefore, we aimed to analyze the MCM2 expression and the associated outcome in breast cancer (BC) patients based on the publicly available online databases. In this study, server-based gene expression analyses indicate the upregulation of MCM2 (p < 10^-6; fold change>2.0) in various BC subtypes as compared to the respective normal tissues. Besides, the evaluation of histological sections from healthy and cancer tissues showed strong staining signals indicating higher expression of MCM2 protein. The overexpression of MCM2 was significantly correlated to promoter methylation and was related to patients' clinical features. Further, mutation analysis suggested missense as the predominant type of mutation (71.4%) with 18 copy-number alterations and 0.2% mutation frequency in the MCM2 gene. This study revealed a significant correlation (Cox p ≤ 0.05) between the higher MCM2 expression and lower patient survival. Finally, we identified the co-expressed genes with gene ontological features and signaling pathways associated in BC development. We believe that this study will provide a basis for MCM2 to be a significant biomarker for human BC prognosis.

Proteomic analysis of transitional cell carcinoma-like variant of tubo-ovarian high-grade serous carcinoma

The current World Health Organization classification does not distinguish transitional cell carcinoma of the ovary (TCC) from conventional tubo-ovarian high-grade serous carcinoma (HGSC), despite evidence suggesting improved prognosis for patients with TCC; instead, it is considered a morphologic variant of HGSC. The immunohistochemical (IHC) markers applied to date do not distinguish between TCC and HGSC. Therefore, we sought to compare the proteomic profiles of TCC and conventional HGSC to identify proteins enriched in TCC. Prognostic biomarkers in HGSC have proven to be elusive, and our aim was to identify biomarkers of TCC as a way of reliably and reproducibly identifying patients with a favorable prognosis and better response to chemotherapy compared with those with conventional HGSC. Quantitative global proteome analysis was performed on archival material of 12 cases of TCC and 16 cases of HGSC using SP3 (single-pot, solid phase-enhanced, sample preparation)-Clinical Tissue Proteomics, a recently described protocol for full-proteome analysis from formalin-fixed paraffin-embedded tissues. We identified 430 proteins that were significantly enriched in TCC over HGSC. Unsupervised co-clustering perfectly distinguished TCC from HGSC based on protein expression. Pathway analysis showed that proteins associated with cell death, necrosis, and apoptosis were highly expressed in TCCs, whereas proteins associated with DNA homologous recombination, cell mitosis, proliferation and survival, and cell cycle progression pathways had reduced expression. From the proteomic analysis, three potential biomarkers for TCC were identified, claudin-4 (CLDN4), ubiquitin carboxyl-terminal esterase L1 (UCHL1), and minichromosome maintenance protein 7 (MCM7), and tested by IHC analysis on tissue microarrays. In agreement with the proteomic analysis, IHC expression of those proteins was stronger in TCC than in HGSC (p < 0.0001). Using global proteomic analysis, we are able to distinguish TCC from conventional HGSC. Follow-up studies will be necessary to confirm that these molecular and morphologic differences are clinically significant.

Expression and prognostic significance of MCM-3 and MCM-7 in salivary adenoid cystic carcinoma

This study sought to investigate minichromosome maintenance protein 3 (MCM3) and minichromosome maintenance protein 7 (MCM7) expression in salivary adenoid cystic carcinoma (SACC) samples, and to evaluate the relationship between clinicopathological characteristics and prognosis. The expressions of MCM3 and MCM7 were evaluated using immunohistochemistry of tissue sections from SACC patients, and statistical analyses were performed to evaluate the associations between MCM expression and clinicopathological variables and to analyze the disease-free survival (DFS) and prognostic factors. The positive expression rates of MCM3 and MCM7 in SACC were 98.8% and 96.6%, respectively. MCM3 expression correlated with T-stage and nerve invasion. MCM7 expression correlated with T-stage, adjacent tissue invasion, nerve invasion, and prognosis, and was negatively associated with DFS. However, there was no significant correlation between MCM3 expression and DFS. A kappa analysis demonstrated that MCM3 was closely associated with MCM7. MCM7 may be a favorable prognosis indicator in SACC.

Prognostic value of minichromosome maintenance mRNA expression in early-stage pancreatic ductal adenocarcinoma patients after pancreaticoduodenectomy

Background

The aim of the current study was to investigate the potential prognostic value of minichromosome maintenance (MCM) genes in patients with early-stage pancreatic ductal adenocarcinoma (PDAC) after pancreaticoduodenectomy by using the RNA-sequencing dataset from The Cancer Genome Atlas (TCGA).

Methods

An RNA-sequencing dataset of 112 early-stage PDAC patients who received a pancreaticoduodenectomy was obtained from TCGA. Survival analysis was used to identify potential prognostic values of MCM genes in PDAC overall survival (OS).

Results

Through mining public databases, we observed that MCM genes (MCM2, MCM3, MCM4, MCM5, MCM6, and MCM7) were upregulated in pancreatic cancer tumor tissue and have a strong positive coexpression with each other. Multivariate survival analysis indicated that a high expression of MCM4 significantly increased the risk of death in patients with PDAC, and time-dependent receiver operating characteristic analysis showed an area under the curve of 0.655, 0.587, and 0.509 for a 1-, 2-, and 3-year PDAC OS prediction, respectively. Comprehensive survival analysis of MCM4 using stratified and joint effects survival analysis suggests that MCM4 may be an independent prognostic indicator for PDAC OS. Gene set enrichment analysis indicated that MCM4 may participate in multiple biologic processes and pathways, including DNA replication, cell cycle, tumor protein p53, and Notch signaling pathways, thereby affecting prognosis of PDAC patients.

Conclusions

Our study indicates that MCM2–7 were upregulated in pancreatic cancer tumor tissues, and mRNA expression of MCM4 may serve as an independent prognostic indicator for PDAC OS prediction after pancreaticoduodenectomy.

RACK1 promotes lung cancer cell growth via an MCM7/RACK1/ Akt signaling complex

MCM7, a member of the miniature chromosome maintenance (MCM) protein family, is crucial for the initiation of DNA replication and proliferation in eukaryotic cells. In this report, we demonstrate that RACK1 regulates cell growth and cell cycle progression in human non-small-cell lung cancer by mediating MCM7 phosphorylation through an MCM7/RACK1/Akt signaling complex. RACK1 functions as a central scaffold that brings Akt into physical proximity with MCM7. Overexpression of RACK1 increases interactions between Akt and MCM7 and promotes Akt-dependent MCM7 phosphorylation, which in turn increases MCM7 binding to chromatin and MCM complex formation. Together, these changes promote DNA replication and cell proliferation. Our findings reveal a novel signaling pathway that regulates growth in non-small cell lung cancer.

MCM7 expression is correlated with histological subtypes of lung adenocarcinoma and predictive of poor prognosis

Emerging evidence has implicated that the abnormal expression of MCM3 and MCM7 contributes to tumor formation and progression. However, MCM3 and MCM7 protein expression in different subtypes of lung adenocarcinoma have not yet been reported. In the present study, we detected MCM7 and MCM3 protein level in five subtypes of lung adenocarcinoma by immunohistochemistry. The five subtypes can be divided into 3 grades-grade 1: lepidic adenocarcinoma, grade 2: acinar or papillary adenocarcinoma and grade 3: solid or micropapillary adenocarcinoma. The immunostaining showed that MCM7 level was lowest in the grade 1 subtype and highest in the grade 3 subtypes. The statistical analysis proved that MCM7 expression increased step wisely with the ascending of tumor grades. However, there is no significant relationship between MCM3 expression and tumor grades. In addition, we investigated the association of MCM7 and MCM3 expression with clinicopathological characteristics. The results showed that tumors with lymph node metastasis had higher MCM7 level than those without lymph node metastasis statistically (P<0.0001). MCM3 expression has no significant relationship with clinicopathological characteristics. In conclusion, our results suggested that MCM7 may be a useful biomarker for the pathological diagnosis of subtypes of lung adenocarcinoma and it also may be a potential prognostic marker for lung adenocarcinoma.

Lamin B2 binding to minichromosome maintenance complex component 7 promotes non-small cell lung carcinogenesis

We investigated the role of lamin B2 in non-small cell lung cancer (NSCLC). We detected higher lamin B2 expression in 20 NSCLC tumor tissues obtained from The Cancer Genome Atlas than in adjacent normal lung tissues. LMNB2-RNAi knockdown in A549 and H1299 NSCLC cells inhibited colony formation, cell proliferation and G1-S cell cycle progression while increasing apoptosis. LMNB2 overexpression had the opposite effects. Tumor xenograft experiments showed diminished tumor growth with LMNB2 knockdown H1299 cells than with controls. Yeast two-hybrid studies revealed minichromosome maintenance complex component 7 (MCM7) to be a binding partner of lamin B2, which was confirmed by co-immunoprecipitation and co-localization studies. Lamin B2 binding enhanced DNA binding and helicase activities of MCM7. Deletion analysis with MCM7-N, MCM7-M or MCM7-C mutant proteins showed that lamin B2 binds to the C-terminus of MCM7, and competes with the binding of the tumor suppressor retinoblastoma (RB) protein. Immunohistochemical analysis of 150 NSCLC patient samples revealed that both lamin B2 and MCM7 levels positively correlated with histological grade and tumor TNM stage. Moreover, high lamin B2 and MCM7 levels correlated with shorter overall survival of NSCLC patients. In sum, these results show that lamin B2 interaction with MCM7 promotes NSCLC progression.

The Expression of MCM7 is a Useful Biomarker in the Early Diagnostic of Gastric Cancer

The aim of this study was to investigate the expression of minichromosome maintenance complex component 7 (MCM7) in gastric mucosal lesions, further to find its potential effect as a biomarker to distinguish intraepithelial neoplasia from gastric mucosal lesions. MCM7 and Ki67 were detected in 93 cases of gastric mucosal lesions by immunohistochemistry. MCM7 and Ki67 expression in GT were lowest compared with other groups (P<0.001), meanwhile there were significant differences compared with Group IM and other groups in MCM7 and Ki67 expression (P<0.001). MCM7 and Ki67 expression in GSC were highest (P<0.05). Groups of LGN, HGN and GIC had no significant differences in MCM7 expression (P>0.05), but there was significant difference compared with Group LGN and Group GIC in Ki67 expression (P<0.05). MCM7 expression elevated with tumor grade increasing and had positive correlation with Ki67 significantly (r=0.940, P<0.001). Furthermore, in some cases, some tumor cells were immunoreactive to MCM7 but negative to Ki67. So we concluded that MCM7 is helpful for us to make differential diagnosis in pathological grade, MCM7 combination of Ki67 may serve as more sensitive proliferation markers for evaluation of gastric carcinoma and precancerous lesions.

Oncogenic activity of amplified miniature chromosome maintenance 8 in human malignancies

Miniature chromosome maintenance (MCM) proteins play critical roles in DNA replication licensing, initiation and elongation. MCM8, one of the MCM proteins playing a critical role in DNA repairing and recombination, was found to have over-expression and increased DNA copy number in a variety of human malignancies. The gain of MCM8 is associated with aggressive clinical features of several human cancers. Increased expression of MCM8 in prostate cancer is associated with cancer recurrence. Forced expression of MCM8 in RWPE1 cells, the immortalized but non-transformed prostate epithelial cell line, exhibited fast cell growth and transformation, while knocked down of MCM8 in PC3, DU145 and LNCaP cells induced cell growth arrest, and decreased tumor volumes and mortality of severe combined immunodeficiency mice xenografted with PC3 and DU145 cells. MCM8 bound cyclin D1 and activated Rb protein phosphorylation by cyclin-dependent kinase 4 in vitro and in vivo. The cyclin D1/MCM8 interaction is required for Rb phosphorylation and S phase entry in cancer cells. As a result, our study showed that copy number increase and overexpression of MCM8 may play critical roles in human cancer development.

MCM7 promotes cancer progression through cyclin D1-dependent signaling and serves as a prognostic marker for patients with hepatocellular carcinoma

DNA replication is a central procedure of cell proliferation, whereas aberrant DNA replication is indicated to be a driving force of oncogenesis. Minichromosome maintenance complex component 7 (MCM7) plays an essential role in initiating DNA replication. To investigate the potential oncogenic properties and prognostic value of MCM7 in hepatocellular carcinoma (HCC), we conducted immunohistochemistry staining of MCM7 in 153 HCC samples and found that MCM7 high expression level was associated with worse overall survival (OS) of HCC patients. Mechanistically, knockdown of MCM7 significantly inhibited cellular proliferation in vitro and HCC tumorigenicity in vivo. Cyclin D1 was proved to be regulated by MCM7–MAPK signaling pathway. Clinically, high expression of both MCM7 and cyclin D1 exhibited a relatively high sensitivity and specificity to predict worse outcome of HCC patients. Taken together, our results suggest that MCM7–cyclin D1 pathway may participate in cancer progression and serve as a biomarker for prognosis in HCC.

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 pre-cancerous 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.

miR-106b promotes cancer progression in hepatitis B virus-associated hepatocellular carcinoma

AIM: To investigate the effect of miR-106b on tumor progression in hepatitis B virus (HBV)-associated hepatocellular carcinoma (HCC).

METHODS: A total of 120 patients who underwent liver resection for HCC at National Cheng Kung University Hospital were enrolled in the present study. MicroRNA (miRNA) array was first used to screen the miRNA expression profiles in HCC patients. The clinical records were retrospectively analyzed, and correlations with the miRNA expression profiles were evaluated. The mRNA expression levels of the miR-106b-25 cluster (miR-106b, miR-93 and miR-25), and MCM7 in tumor and non-tumor samples were quantitated using quantitative real-time reverse transcription-polymerase chain reaction (q-RT-PCR) analysis, and correlations in the levels of miR-106b, miR-93 and miR-25 expression were calculated. Kaplan-Meier overall and disease-free survival rates of HBV-associated HCC patients were analyzed using the log-rank test based on miR-106b expression. The comparison of the miR-106b expression levels in patients with different clinical outcomes was analyzed using Mann-Whitney U tests. Furthermore, a hepatitis B virus X protein (HBx) expression plasmid was transfected into Huh7 and Hep 3B cells. The expression levels of the miR-106b-25 cluster and MCM7 in HBx-expressing Huh7 and Hep 3B cells were detected using q-RT-PCR.

RESULTS: miRNA array screening showed that miR-106b and its cluster, miR-93 and miR-25 were up-regulated in HCC patients (P < 0.01). The value of miR-106b expression in HBV-associated HCC patients was significantly higher than that in HCV- (P < 0.05) or non-B/non-C- (P < 0.001) associated HCC patients. The expression of the miR-106b-25 cluster was significantly higher in tumor tissue (P < 0.001) and associated with the host gene, MCM7, in clinical specimens from HBV-associated HCC patients. Furthermore, the expression levels of miR-106b, miR-93 and miR-25 were positively correlated in HBV-associated HCC tissues (miR-106 vs miR-93, r = 0.75; miR-93 vs miR-25, r = 0.69; miR-106b vs miR-25, r = 0.33). The overall and disease-free survival curves showed that high-miR-106b expression was correlated with the poor prognosis of HBV-associated HCC. HCC differentiation was significantly correlated with miR-106b expression (P < 0.05). Lower miR-106b expression levels resulted in the well differentiation of HCC. Moreover, the expression of the miR106b-25 cluster and MCM7 was up-regulated in Huh7 and Hep 3B cells after transfection with the HBx expression plasmid.

CONCLUSION: The data obtained in the present study suggests that HBx enhances miR-106b transcription to promote tumor progression in HBV-associated HCC.

Overexpression of CDT1 Is a Predictor of Poor Survival in Patients with Hepatocellular Carcinoma

BACKGROUND

Genomic instability is a common feature in hepatocellular carcinoma. Deregulation of replication licensing factors has been shown to trigger DNA damage response contributing to genomic instability. Overexpression of DNA replication licensing factors chromatin licensing and DNA replication factor 1 (CDT1) and minichromosome maintenance complex component 7 (MCM7) has been previously reported in several human cancers. The aim of the present study was to evaluate the expression and prognostic significance of CDT1 and MCM7 in association with DNA damage response markers and p53 in patients with hepatocellular carcinoma.

METHODS

Expression of CDT1, MCM7, p-H2A histone family member X (H2AX), phospho-ataxia telangiectasia-mutated (ATM)/ataxia telangiectasia rad3-related (ATR) substrate, and p53 was evaluated by immunohistochemistry on formalin-fixed paraffin-embedded surgical specimens from 111 patients who underwent hepatectomy for hepatocellular carcinoma. Statistical analysis was performed to evaluate associations between the studied proteins, clinicopathological parameters, and patient survival.

RESULTS

CDT1 expression correlated with p-H2AX (p = 0.038), while MCM7 correlated with p-H2AX and phospho-ATM/ATR substrate (p < 0.001). Increased CDT1 expression was associated with higher tumor grade (p = 0.006) and tumor-node-metastasis (TNM) stage (p = 0.033). High CDT1 expression correlated significantly with reduced overall survival (60.8 and 26.5 % vs 82.8 and 53.0 %, for low CDT1 expression, at 2 and 5 years, respectively, p = 0.012) and was identified by multivariate analysis as an independent predictor of poor overall survival (p = 0.049).

CONCLUSIONS

Overexpression of CDT1 and MCM7 in hepatocellular carcinoma correlates with DNA damage response, and CDT1 overexpression is a significant prognostic biomarker in hepatocellular carcinoma.

Similar protein expression profiles of ovarian and endometrial high-grade serous carcinomas

Background:

Ovarian and endometrial high-grade serous carcinomas (HGSCs) have similar clinical and pathological characteristics; however, exhaustive protein expression profiling of these cancers has yet to be reported.

Methods:

We performed protein expression profiling on 14 cases of HGSCs (7 ovarian and 7 endometrial) and 18 endometrioid carcinomas (9 ovarian and 9 endometrial) using iTRAQ-based exhaustive and quantitative protein analysis.

Results:

We identified 828 tumour-expressed proteins and evaluated the statistical similarity of protein expression profiles between ovarian and endometrial HGSCs using unsupervised hierarchical cluster analysis (P<0.01). Using 45 statistically highly expressed proteins in HGSCs, protein ontology analysis detected two enriched terms and proteins composing each term: IMP2 and MCM2. Immunohistochemical analyses confirmed the higher expression of IMP2 and MCM2 in ovarian and endometrial HGSCs as well as in tubal and peritoneal HGSCs than in endometrioid carcinomas (P<0.01). The knockdown of either IMP2 or MCM2 by siRNA interference significantly decreased the proliferation rate of ovarian HGSC cell line (P<0.01).

Conclusions:

We demonstrated the statistical similarity of the protein expression profiles of ovarian and endometrial HGSC beyond the organs. We suggest that increased IMP2 and MCM2 expression may underlie some of the rapid HGSC growth observed clinically.

TP53 mutations, tetraploidy and homologous recombination repair defects in early stage high-grade serous ovarian cancer

To determine early somatic changes in high-grade serous ovarian cancer (HGSOC), we performed whole genome sequencing on a rare collection of 16 low stage HGSOCs. The majority showed extensive structural alterations (one had an ultramutated profile), exhibited high levels of p53 immunoreactivity, and harboured a TP53 mutation, deletion or inactivation. BRCA1 and BRCA2 mutations were observed in two tumors, with nine showing evidence of a homologous recombination (HR) defect. Combined Analysis with The Cancer Genome Atlas (TCGA) indicated that low and late stage HGSOCs have similar mutation and copy number profiles. We also found evidence that deleterious TP53 mutations are the earliest events, followed by deletions or loss of heterozygosity (LOH) of chromosomes carrying TP53, BRCA1 or BRCA2. Inactivation of HR appears to be an early event, as 62.5% of tumours showed a LOH pattern suggestive of HR defects. Three tumours with the highest ploidy had little genome-wide LOH, yet one of these had a homozygous somatic frame-shift BRCA2 mutation, suggesting that some carcinomas begin as tetraploid then descend into diploidy accompanied by genome-wide LOH. Lastly, we found evidence that structural variants (SV) cluster in HGSOC, but are absent in one ultramutated tumor, providing insights into the pathogenesis of low stage HGSOC.

Prognostic significance of expression of MCM7 and CDX2 in stage Ⅱ colorectal cancer

AIM: To investigate the expression of mini-chromosome maintenance protein 7 (MCM7) and caudal-related homeobox gene 2 (CDX2) in stage Ⅱ colorectal cancer (CRC) and to analyze their correlation with pathological characteristics and prognosis.

METHODS: Immunohistochemistry was used to detect the expression of MCM7 and CDX2 in 220 pairs of stage Ⅱ CRC and adjacent normal tissues. Differential MCM7 and CDX2 expression was analyzed according to the donors' pathological features and prognosis.

RESULTS: MCM7 expression in CRC tissues was significantly higher than that in corresponding adjacent normal tissues (P < 0.001), whereas CDX2 abundance in malignant tissues was dramatically lower compared with corresponding normal counterparts (P < 0.01). Moreover, MCM7 was correlated inversely with tumor differentiation, whereas CDX2 was positively related to tumor differentiation. Kaplan-Meier survival analysis revealed that MCM7^-/CDX2⁺patients had a better outcome.

CONCLUSION: The elevated expression of MCM7 and decreased expression of CDX2 could be combined to act as a prognostic factor for stage Ⅱ CRC.

Prognostic significance of minichromosome maintenance proteins in breast cancer

A role for the minichromosome maintenance (MCM) proteins in cancer initiation and progression is slowly emerging. Functioning as a complex to ensure a single chromosomal replication per cell cycle, the six family members have been implicated in several neoplastic disease states, including breast cancer. Our study aim to investigate the prognostic significance of these proteins in breast cancer. We studied the expression of MCMs in various datasets and the associations of the expression with clinicopathological parameters. When considered alone, high level MCM4 overexpression was only weakly associated with shorter survival in the combined breast cancer patient cohort (n = 1441, Hazard Ratio = 1.31; 95% Confidence Interval = 1.11-1.55; p = 0.001). On the other hand, when we studied all six components of the MCM complex, we found that overexpression of all MCMs was strongly associated with shorter survival in the same cohort (n = 1441, Hazard Ratio = 1.75; 95% Confidence Interval = 1.31-2.34; p < 0.001), suggesting these MCM proteins may cooperate to promote breast cancer progression. Indeed, their expressions were significantly correlated with each other in these cohorts. In addition, we found that increasing number of overexpressed MCMs was associated with negative ER status as well as treatment response. Together, our findings are reproducible in seven independent breast cancer cohorts, with 1441 patients, and suggest that MCM profiling could potentially be used to predict response to treatment and prognosis in breast cancer patients.

MicroRNAs in the development and pathobiology of uterine leiomyomata: does evidence support future strategies for clinical intervention?

BACKGROUND

Human leiomyomata (fibroids) are benign tumors of the uterus, represent the most common neoplasms of reproductive-aged women and have a prevalence of ∼70% in the general population. This disorder conveys a significant degree of morbidity and remains the leading indication for hysterectomy in the USA. Prior investigations of aberrant microRNA (miRNA) expression in various malignancies have provided invaluable insight into the role of this class of small non-coding RNAs in tumor growth. Evidence of irregular miRNA expression in uterine fibroids has garnered recent interest for diagnostic and therapeutic applications. Since miRNA gene targets modulate several processes implicated in the genesis of uterine fibroids, more focused investigation has the potential to elucidate the functional significance of miRNA in the genesis and pathology of the disease.

METHODS

Comprehensive electronic searches of peer reviewed published literature in PubMed (US National Library of Medicine, National Institute of Health; http://www.ncbi.nlm.nih.gov/pubmed/) were performed for content related to the biologic functions of miRNA, the roles of miRNA in human disease and studies investigating miRNA in the context of uterine leiomyomata. Herein, this article will review the current evidence supporting the use of miRNA expression profiling as an investigative tool to assess the pathobiology of uterine fibroids and will discuss potential future applications of miRNAs as biomarkers and therapeutic targets.

RESULTS

Mounting evidence supports a functional role for miRNA as either indirect or direct regulators of gene expression which impacts the pathobiology of uterine fibroids. Specifically, miRNAs let-7, 200a, 200c, 93, 106b and 21 have been implicated in cellular proliferation, apoptosis, extracellular matrix turnover, angiogenesis and inflammation. Preliminary data provide evidence to suggest that respective in vitro miRNA expression in leiomyomata and myometrium is regulated by sex steroids.

CONCLUSIONS

Collectively, the identification of aberrantly expressed miRNAs in uterine leiomyomata and accumulating data derived from mining of gene target prediction models and recent functional studies support the concept that miRNAs might impact the genesis and progression of disease. However, the specific biologic functions of differential miRNA expression have yet to be confirmed in vivo. Further functional studies and developing miRNA technology may provide the basis for future applications of miRNAs in clinical medicine as biomarkers and therapeutic targets.

Novel ATPase Cu(2+) transporting beta polypeptide mutations in Chinese families with Wilson's disease

Wilson's disease (WD) is an autosomal recessive inherited disorder caused by mutations in the ATPase Cu(2+) transporting beta polypeptide gene (ATP7B). The detailed metabolism of copper-induced pathology in WD is still unknown. Gene mutations as well as the possible pathways involved in the ATP7B deficiency were documented. The ATP7B gene was analyzed for mutations in 18 Chinese Han families with WD by direct sequencing. Cell viability and apoptosis analysis of ATP7B small interfering RNA (siRNA)-treated human liver carcinoma (HepG2) cells were measured by 3-[4,5-dimethylthiazol-2-yl]-2,5-diphenyltetrazolium bromide (MTT) assay and Hoechst 33342 staining. Finally, the expression of B-cell CLL/lymphoma 2 (BCL2), BCL2-associated X protein (BAX), sterol regulatory element binding protein 1 (SREBP1), and minichromosome maintenance protein 7 (MCM7) of ATP7B siRNA-treated cells were tested by real-time polymerase chain reaction (real-time PCR) and Western blot analysis. Twenty different mutations including four novel mutations (p.Val145Phe, p.Glu388X, p.Thr498Ser and p.Gly837X) in the ATP7B gene were identified in our families. Haplotype analysis revealed that founder effects for four mutations (p.Arg778Leu, p.Pro992Leu, p.Ile1148Thr and p.Ala1295Val) existed in these families. Transfection of HepG2 cells with ATP7B siRNA resulted in decreased mRNA expression by 86.3%, 93.1% and 90.8%, and decreased protein levels by 58.5%, 85.5% and 82.1% at 24, 48 and 72 hours, respectively (All P<0.01). In vitro study revealed that the apoptotic, cell cycle and lipid metabolism pathway may be involved in the mechanism of WD. Our results revealed that the genetic cause of 18 Chinese families with WD and ATP7B deficiency-induce apoptosis may result from imbalance in cell cycle and lipid metabolism pathway.

Epidermal growth factor receptor potentiates MCM7-mediated DNA replication through tyrosine phosphorylation of Lyn kinase in human cancers

Epidermal growth factor receptor (EGFR) initiates a signaling cascade that leads to DNA synthesis and cell proliferation, but its role in regulating DNA replication licensing is unclear. Here, we show that activated EGFR phosphorylates the p56 isoform of Lyn, p56(Lyn), at Y32, which then phosphorylates MCM7, a licensing factor critical for DNA replication, at Y600 to increase its association with other minichromosome maintenance complex proteins, thereby promoting DNA synthesis complex assembly and cell proliferation. Both p56(Lyn) Y32 and MCM7 Y600 phosphorylation are enhanced in proliferating cells and correlated with poor survival of breast cancer patients. These results establish a signaling cascade in which EGFR enhances MCM7 phosphorylation and DNA replication through Lyn phosphorylation in human cancer cells.

MCM7 expression is altered in rat after spinal cord injury

Minichromosome maintenance protein 7 (MCM7), a member of the minichromosome maintenance protein family, is essential for eukaryotic DNA replication initiation and the early stage of the elongation process. MCM7 participates in the cell cycle control of genome duplication. While it is ubiquitously expressed in all tissues, the biological function of MCM7 in the central nervous system is still with limited acquaintance. In the present study, we performed a spinal cord injury (SCI) model in adult rats. Western blotting indicated a marked alteration of MCM7 after SCI. Immunohistochemistry analysis revealed a wide distribution of MCM7 in the spinal cord. Double immunofluorescence staining showed that MCM7 immunoreactivity was increased predominantly in neurons, astrocytes, and microglia after SCI. We also examined the expression profiles of active caspase-3, proliferating cell nuclear antigen (PCNA), and Ki67, whose changes were correlated with the expression profiles of MCM7. Moreover, colocalization of MCM7/active caspase-3 was detected in neuronal nuclei (NeuN), and colocalization of MCM7/PCNA was detected in NeuN, glial fibrillary acidic protein, and CD11b, respectively. Our results suggest that MCM7 might be implicated in the apoptosis of neuron and proliferation of astrocytes and microglia after SCI.

Expression of lysophosphatidic acid receptor 1 and relation with cell proliferation, apoptosis, and angiogenesis on preneoplastic changes induced by cadmium chloride in the rat ventral prostate

BACKGROUND

Lysophosphatidic acid (LPA) is a phospholipid growth factor involved in cell proliferation, differentiation, migration, inflammation, angiogenesis, wound healing, cancer invasion, and survival. This study was directed to evaluate the immunoexpression of LPA-1, cell proliferation, apoptosis, and angiogenesis markers in preneoplastic lesions induced with cadmium chloride in rat prostate.

METHODS

The following parameters were calculated in ventral prostate of normal rats and rats that received Cd in drinking water during 24 months: percentages of cells immunoreactive to LPA-1 (LILPA1), PCNA (LIPCNA), MCM7 (LIMCM7), ubiquitin (LIUBI), apoptotic cells (LIAPO), and p53 (LIp53); volume fraction of Bcl-2 (VFBcl-2); and length of microvessels per unit of volume (LVMV/mm3). Data were analyzed using Student's t-test and Pearson correlation test.

RESULTS

The LILPA1 in dysplastic lesions and normal epithelium of Cd-treated rats was significantly higher than those in the control group. Markers of proliferation were significantly increased in dysplastic lesions, whereas some apoptotic markers were significantly decreased. No significant differences between groups were found in VFBcl-2. Dysplastic lesions showed a significant increase of LIp53. The length of microvessels per unit of volume was elevated in dysplastic acini. Statistically significant correlations were found only between LILPA1 and LIUBI.

CONCLUSIONS

Our results suggest that LPA-1 might be implicated in dysplastic lesions induced by cadmium chloride development. More studies are needed to confirm its potential contribution to the disease.

MCM7 expression predicts post-operative prognosis for hepatocellular carcinoma

BACKGROUND

Dysregulation of minichromosome maintenance protein 7 (MCM7) was previously identified in multiple human malignancies. The clinical significance of MCM7 expression is yet to be delineated in patients with hepatocellular carcinoma (HCC).

METHODS

Paired cancerous and non-cancerous specimens from 87 patients with HCC who underwent resection were used for the immunohistochemical evaluation of MCM7 expression. Effect of sorafenib on the expression of MCM7 was tested in two human HCC cell lines SMMC-7721 and PLC/PRF/5.

RESULTS

Non-cancerous tissues were negative for immunohistochemical staining for MCM7 expression. Nuclear MCM7 was expressed in 42 of 87 HCC (48.2%) and was correlated with hepatitis B virus infection (P = 0.020), intrahepatic metastasis (P = 0.022) and vascular invasion (P = 0.013). Moreover, its expression was correlated with shorter overall survival (P = 0.033). Multivariate analysis showed that MCM7 expression was an independent prognostic factor for overall survival(P = 0.041). Sorafenib inhibited the expression of MCM7 in a concentration-dependent manner in vitro.

CONCLUSIONS

The current findings suggested that MCM7 expression may be a useful predictor of prognosis in patients with HCC after resection. Adjuvant therapy with sorafenib might be a valuable therapeutic strategy for MCM7-positive HCC patients.

miR-93/106b and their host gene, MCM7, are differentially expressed in leiomyomas and functionally target F3 and IL-8

miR-93/106b and their host gene minichromosome maintenance complex component 7 (MCM7) reside at chr7q22, a region frequently rearranged in leiomyomas. We explored the expression of miR-93/106b in leiomyoma and paired myometrium (n = 63) from untreated and patients exposed to hormonal therapies (GnRH agonist, Depo-Provera, and oral contraceptives) from African-Americans and Caucasians and their regulatory functions in isolated paired (n = 15) leiomyoma and myometrial smooth muscle cells and the leiomyosarcoma cell line. At tissue level leiomyomas expressed significantly lower levels of miR-93 and elevated MCM7 as compared with myometrium with limited racial influence or hormonal exposure on their expression. Assessing the regulatory function of miR-93/106b through doxycycline-inducible lentiviral transduction in a microarray analysis, tissue factor (F3) and IL8 were identified as their possible targets. At the tissue level, leiomyomas expressed a significantly lower level of F3 and an elevated IL-8 level, which exhibited an inverse relationship with miR-93 but with limited racial or hormonal influences. The gain of function of miR-93/106b in leiomyoma smooth muscle cells, myometrial smooth muscle cells, and the leiomyosarcoma cell line dose dependently repressed F3 and IL8 through direct interactions with their respective 3'-untranslated region and indirectly through F3 repression inhibited IL8, CTGF, and PAI-1 expression, confirmed by using small interfering RNA silencing or factor Vlla (FVIIa) activation of F3, as well as reducing the rate of proliferation, while increasing caspase-3/7 activity. We concluded that differential expression of miR-93/106b and their direct and/or indirect regulatory functions on F3, IL8, CTGF, and PAI-1 expression, with key roles in inflammation and tissue turnover may be of significance in the outcome of leiomyoma growth and associated symptoms.

Expression of DSG1 and DSC1 are prognostic markers in anal carcinoma patients

Background:

Our purpose was to investigate if dysregulation of cell adhesion molecules could be linked to prognosis in squamous cell carcinomas (SCCs) of the anal region.

Methods:

Protein expression of desmoglein-1 (DSG1), desmocollin-1 (DSC1) and E-cadherin was studied by immunohistochemistry in a cohort of 53 anal carcinoma patients treated by radiation alone or combined with 5-fluorouracil and mitomycin C.

Results:

Univariate analyses identified, among others, negative membranous DSG1 staining (P=0.009), negative cytoplasmic DSC1 staining (P=0.012) and negative DSG1 (membranous)+negative DSC1 (cytoplasmic) staining (P=0.004) to be associated with improved cancer-specific survival (CSS). On multivariate analyses positive DSG1 (membranous)+DSC1 (cytoplasmic) staining (HR 6.95, P=0.044), large tumour size and lymph node metastases (HR 6.44, P=0.004) and radiation without chemotherapy (HR 6.73 P=0.004) were associated with worse CSS. On univariate analysis, improved disease-free survival was associated with negative membranous staining of DSG1 (P=0.047), and negative DSG1 (membranous)+negative DSC1 (cytoplasmic) staining (P=0.025), among others.

Conclusion:

Membrane negativity for DSG1 and cytoplasmic negativity for DSC1 are favourable markers for CSS in SCCs of the anal region.