Minichromosome maintenance 2 (MCM2) immunoreactivity in stage III human gastric carcinoma: clinicopathological significance

Unwinding Helicase MCM Functionality for Diagnosis and Therapeutics of Replication Abnormalities Associated with Cancer: A Review

The minichromosome maintenance (MCM) protein is a component of an active helicase that is essential for the initiation of DNA replication. Dysregulation of MCM functions contribute to abnormal cell proliferation and genomic instability. The interactions of MCM with cellular factors, including Cdc45 and GINS, determine the formation of active helicase and functioning of helicase. The functioning of MCM determines the fate of DNA replication and, thus, genomic integrity. This complex is upregulated in precancerous cells and can act as an important tool for diagnostic applications. The MCM protein complex can be an important broad-spectrum therapeutic target in various cancers. Investigations have supported the potential and applications of MCM in cancer diagnosis and its therapeutics. In this article, we discuss the physiological roles of MCM and its associated factors in DNA replication and cancer pathogenesis.

MCM2 in human cancer: functions, mechanisms, and clinical significance

Background

Aberrant DNA replication is the main source of genomic instability that leads to tumorigenesis and progression. MCM2, a core subunit of eukaryotic helicase, plays a vital role in DNA replication. The dysfunction of MCM2 results in the occurrence and progression of multiple cancers through impairing DNA replication and cell proliferation.

Conclusions

MCM2 is a vital regulator in DNA replication. The overexpression of MCM2 was detected in multiple types of cancers, and the dysfunction of MCM2 was correlated with the progression and poor prognoses of malignant tumors. According to the altered expression of MCM2 and its correlation with clinicopathological features of cancer patients, MCM2 was thought to be a sensitive biomarker for cancer diagnosis, prognosis, and chemotherapy response. The anti-tumor effect induced by MCM2 inhibition implies the potential of MCM2 to be a novel therapeutic target for cancer treatment. Since DNA replication stress, which may stimulate anti-tumor immunity, frequently occurs in MCM2 deficient cells, it also proposes the possibility that MCM2 targeting improves the effect of tumor immunotherapy.

Identification of mini-chromosome maintenance 8 as a potential prognostic marker and its effects on proliferation and apoptosis in gastric cancer

Mini-chromosome maintenance (MCM) proteins play important roles in initiating eukaryotic genome replication. The MCM family of proteins includes several members associated with the development and progression of certain cancers. We performed online data mining to assess the expression of MCMs in gastric cancer (GC) and the correlation between their expression and survival in patients with GC. Notably, MCM8 expression was undoubtedly up-regulated in GC, and higher expression correlated with shorter overall survival (OS) and progression-free survival (PFS) in patients with GC. However, the role of MCM8 in GC has not been previously explored. Our in vitro experiments revealed that MCM8 knockdown inhibited cell growth and metastasis. Moreover, MCM8 knockdown induced apoptosis. Mechanistically, the expression levels of Bax and cleaved caspase-3 were increased, whereas Bcl-2 expression decreased. Additionally, we demonstrated that MCM8 knockdown suppressed tumorigenesis in vivo. Overall, these results suggest that MCM8 plays a significant role in GC progression.

Aquaporin-1 facilitates proliferation and invasion of gastric cancer cells via GRB7-mediated ERK and Ras activation

Gastric cancer, one of the most common malignant tumors of the digestive tract, is devoid of effective treatment owing to its highly invasive ability. Aquaporins (AQPs), transmembrane water channel proteins, has been shown to be involved in the malignancy of gastric cancer. This study aims to investigate the pathophysiological roles of AQP-1 in gastric cancer. We first demonstrated quantitative real-time polymerase chain reaction analysis and found up-regulation of AQP-1 in gastric cancer cell lines. Additionally, silence of AQP-1 inhibited cell proliferation via decrease of proliferating cell nuclear antigen (PCNA) and minichromosome maintenance complex component 2 (MCM2). Moreover, migration and invasion of gastric cancer cells were also suppressed by the interference of AQP-1. However, the tumorigenic mechanism of AQP-1 on gastric cancer is yet to be found. We demonstrated western blot analysis and found that knockdown of AQP-1 decreased protein expression of phospho (p)-GRB7 (growth factor receptor-bound protein 7) and led to a remarkable reduction of p-extracellular signal-regulated kinase (ERK) via inactivation of RAS. In general, our findings indicated that AQP-1 facilitates proliferation and invasion of gastric cancer cells via GRB7-mediated ERK and Ras activation, illuminating a novel AQP-1-RAS/ERK molecular axis as regulator in gastric cancer progression and suggesting potential implications in the treatment of gastric cancer.

MCM family in gastrointestinal cancer and other malignancies: From functional characterization to clinical implication

Despite the recent advances in cancer research and treatment, gastrointestinal (GI) cancers remain the most common deadly disease worldwide. The aberrant DNA replication serves as a major source of genomic instability and enhances cell proliferation that contributes to tumor initiation and progression. Minichromosome maintenance family (MCMs) is a well-recognized group of proteins responsible for DNA synthesis. Recent studies suggested that dysregulated MCMs lead to tumor initiation, progression, and chemoresistance via modulating cell cycle and DNA replication stress. Their underlying mechanisms in various cancer types have been gradually identified. Furthermore, multiple studies have investigated the association between MCMs expression and clinicopathological features of cancer patients, implying that MCMs might serve as prominent prognostic biomarkers for GI cancers. This review summarizes the current knowledge on the oncogenic role of MCM proteins and highlights their clinical implications in various malignancies, especially in GI cancers. Targeting MCMs might shed light on the potential for identifying novel therapeutic strategies.

Comprehensive Analysis of the Expression and Prognosis for MCMs in Human Gastric Cancer

PURPOSES

Minichromosome maintenance (MCM) proteins play an important role in replication and cell cycle progression. Even so, their expression and prognostic roles in cancer remain controversial.

METHODS

To address this issue, the study investigated the roles of MCMs in the prognosis of GC by using ONCOMINE, GEPIA2, UALCAN, Cancer Cell Line Encyclopedia (CCLE), the Human Protein Atlas, Kaplan-Meier Plotter, cBioPortal, GeneMANIA, and DAVID databases.

RESULTS

Over expressions of mRNA and cell lines were found in all members of the MCM family, and MCMs were found to be significantly associated with pathological tumor grades in GC patients. Besides, higher mRNA expressions of MCM1/5/7 were found to be significantly associated with shorter overall survival (OS) and progression-free survival (FP) in GC patients, while higher mRNA expression of MCM4/6/9 were connected with favorable OS and FP. Moreover, a high mutation rate of MCMs (68%) was also observed in GC patients.

CONCLUSIONS

The results indicated that MCM1/5/7 were potential targets of precision therapy for patients with GC. And MCM4/6/9 were new biomarkers for the prognosis of GC. The results of the study will contribute to supplement the existing knowledge, and help to explore therapeutic targets and enhance the accuracy of prognosis for patients with GC.

Metallothionein protein and minichromosome maintenance protein-2 expression in adrenocortical tumors

AIM

Some resected adrenal-confined adrenocortical carcinomas metastasize and others not. The present study was designed to evaluate the expression of metallothionein protein (MT) and minichromosome maintenance protein-2 (MCM2) in adrenocortical carcinomas and adrenocortical adenomas, and to test the correlation between this and adrenocortical carcinoma aggressiveness.

MATERIALS AND METHODS

The study comprised 14 patients operated on for adrenocortical carcinoma, 15 operated on for adrenocortical adenoma and 2 with normal adrenals. Hematoxylin-eosin staining was used for histological evaluation under light microscopy, and sequential sections were used for MCM2 and MT staining.

RESULTS

In normal adrenals, positive staining was weak for MT and zero for MCM2. Rates of positive staining for MT and MCM2 were significantly higher in adrenocortical carcinomas than in adrenocortical adenomas (P=0.008 and P<0.001, respectively). In adrenocortical carcinomas, a significant positive correlation was found between MCM2 staining and Weiss revisited score (P=0.022) but not for Weiss score, and a significant positive correlation was found between MCM2 and mitotic rate on histology (P=0.033). MCM2 but not MT staining was also shown to correlate significantly with stage IV carcinoma (P=0.008 and P=0.165, respectively).

CONCLUSION

MCM2 and MT are overexpressed in adrenocortical carcinoma, and MCM2 expression correlates significantly with metastatic disease.

Ki-67/MKI67 as a Predictive Biomarker for Clinical Outcome in Gastric Cancer Patients: an Updated Meta-analysis and Systematic Review involving 53 Studies and 7078 Patients

Gastric cancer (GC) threatens human health worldwide and we performed this meta-analysis to evaluate the clinical value of Ki-67/MKI67 in patients with GC. The combined hazard ratio (HR), odds ratio (OR) and 95% confidence interval (95% CI) were calculated to assess the relationships of Ki-67/MKI67 expression with prognoses and clinicopathological characteristics. Genes co-expressed with MKI67 were collected for Gene Ontology (GO), Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway and protein-protein interaction (PPI) network analyses. In total, 53 studies with 7078 patients were included in this study. The pooled HRs indicated that an elevated expression of Ki-67/MKI67 predicted an unfavorable overall survival (HR: 1.54, 95% CI: 1.33-1.78, P<0.0001) and disease-free survival (HR: 2.28, 95% CI: 1.43-3.64, P<0.0001) in GC patients. Additionally, in patients with advanced GC, a high Ki-67/MKI67 expression was also significantly connected with OS (HR: 1.37, 95% CI: 1.18-1.60, P<0.0001). The combined ORs showed that Ki-67/MKI67 expression was related to TNM stage (stage III/IV versus stage I/II: OR=1.93, 95% CI=1.34-2.78, P<0.0001), tumor differentiation (poor versus well/moderate: OR=1.94, 95% CI=1.32-2.85, P=0.001), lymph node metastasis (yes versus no: OR=1.67, 95% CI=1.23-2.25, P=0.001), distant metastasis (yes versus no: OR=1.67, 95% CI=1.24-2.26, P=0.001) and tumor invasion depth (T3/T4 versus T_is/T1/T2: OR=1.98, 95% CI=1.60-2.44, P<0.0001). The results of GO, KEGG pathway and PPI network analyses indicated that Ki-67/MKI67 may be involved in the development of GC via influencing P53 signaling pathway. Ki-67/MKI67 could be a potential indicator to predict the prognosis of patients with GC and identify high-risk cases. Detecting Ki-67/MKI67 expression in clinic may be helpful in optimizing individual treatment and further improving the survival expectancy of patients with GC.

The use of DNA repair genes as prognostic indicators of gastric cancer

DNA repair genes can be used as prognostic biomarkers in many types of cancer. We aimed to identify prognostic DNA repair genes in patients with gastric cancer (GC) by systematically bioinformatic approaches using web-based database. Global gene expression profiles from altogether 1,325 GC patients' samples from six independent datasets were included in the study. Clustering analysis was performed to screen potentially abnormal DNA repair genes related to the prognosis of GC, followed by unsupervised clustering analysis to identify molecular subtypes of GC. Characteristics and prognosis differences were analyzed among these molecular subtypes, and modular key genes in molecular subtypes were identified based on changes in expression correlation. Multivariate Cox proportional hazard analysis was used to find the independent prognostic gene. Kaplan-Meier method and log-rank test was used to estimate correlations of key DNA repair genes with GC patients'overall survival. There were 57 key genes significantly associated to GC patients' prognosis, and patients were stratified into three molecular clusters based on their expression profiles, in which patients in Cluster 3 showed the best survival (P < 0.05). After a three-phase training, test and validation process, the expression profile of 13 independent key DNA repair genes were identified can classify the prognostic risk of patients. Compared with patients with low-risk score, patients with high risk score in the training set had shorter overall survival (P < 0.0001). Furthermore, we verified equivalent findings by these key DNA repair genes in the test set (P < 0.0001) and the independent validation set (P = 0.0024). Our results suggest a great potential for the use of DNA repair gene profiling as a powerful marker in prognostication and inform treatment decisions for GC patients.

Expression of Minichromosome Maintenance Proteins (MCM) and Cancer Prognosis: A meta-analysis

Minichromosome maintenance proteins (MCM) played a critical role in replication and cell cycle progression. However, their prognostic roles in cancer remain controversial. Therefore, we performed a meta-analysis to investigate the prognostic value of MCMs in cancers. Totally 31 eligible articles with 7653 cancer patients were included in this meta-analysis. We evaluated the relationship between MCMs expression and overall survival (OS) in various cancer patients by using pooled hazard ratios (HRs) and risk ratios (RRs) with 95% confidence intervals (CIs). The meta-analysis showed that carriers with high expression of MCM5 and MCM7 were significantly associated with short OS for pooled HR (HR=1.04, 95% CI=1.01-1.08, P=0.020, HR=1.78, 95% CI=1.04-3.02, P=0.035, respectively). For pooled RR, individuals with increased MCM2 and MCM7 expression were significantly correlated with poor OS (RR=2.30, 95% CI=1.14-4.63, P=0.019; RR=3.52, 95% CI=2.01-6.18, P<0.001, respectively). The findings suggest that high expression of MCM2, MCM5 and MCM7 might serve as predictive biomarkers for poor prognosis in cancers.

The Human Replicative Helicase, the CMG Complex, as a Target for Anti-cancer Therapy

DNA helicases unwind or rearrange duplex DNA during replication, recombination and repair. Helicases of many pathogenic organisms such as viruses, bacteria, and protozoa have been studied as potential therapeutic targets to treat infectious diseases, and human DNA helicases as potential targets for anti-cancer therapy. DNA replication machineries perform essential tasks duplicating genome in every cell cycle, and one of the important functions of these machineries are played by DNA helicases. Replicative helicases are usually multi-subunit protein complexes, and the minimal complex active as eukaryotic replicative helicase is composed of 11 subunits, requiring a functional assembly of two subcomplexes and one protein. The hetero-hexameric MCM2-7 helicase is activated by forming a complex with Cdc45 and the hetero-tetrameric GINS complex; the Cdc45-Mcm2-7-GINS (CMG) complex. The CMG complex can be a potential target for a treatment of cancer and the feasibility of this replicative helicase as a therapeutic target has been tested recently. Several different strategies have been implemented and are under active investigations to interfere with helicase activity of the CMG complex. This review focuses on the molecular function of the CMG helicase during DNA replication and its relevance to cancers based on data published in the literature. In addition, current efforts made to identify small molecules inhibiting the CMG helicase to develop anti-cancer therapeutic strategies were summarized, with new perspectives to advance the discovery of the CMG-targeting drugs.

Meta-analysis of prognostic role of Ki-67 labeling index in gastric carcinoma

BACKGROUND

This meta-analysis aimed to elucidate the prognostic role of the Ki-67 labeling index (LI) in gastric cancer (GC).

METHODS

The current study included 3,615 GC patients in 20 eligible studies, and evaluated the prognostic role of Ki-67 LI in GC. Subgroup analysis was conducted based on depth of invasion and cutoff value for high Ki-67 LI.

RESULTS

A high Ki-67 LI correlated significantly with worse survival (hazard ratio [HR] = 1.214, 95% confidence interval [CI], 1.004-1.468). However, there was no significant correlation between high Ki-67 LI and worse survival in advanced GC (HR = 1.252, 95% CI, 0.801-1.956). The subgroup with cutoff value ≤25% showed a significant correlation with worse survival, but this was not seen in the subgroup with cutoff >25% (HR = 1.433, 95% CI, 1.094-1.876 vs. HR = 1.005, 95% CI, 0.801-1.262). In addition, in the 10% <Ki-67 LI ≤ 20% range, there was a significant correlation between high Ki-67 LI and worse overall survival (HR = 1.931, 95% CI, 1.013-3.310).

CONCLUSIONS

A high Ki-67 LI correlated significantly with a worse prognosis in GC patients. Further cumulative studies for the optimal cutoff value for high Ki-67 LI are needed before application in clinical practice.

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.

Minichromosome Maintenance (MCM) Family as potential diagnostic and prognostic tumor markers for human gliomas

Background

Gliomas are the most common type of all central nervous system tumors. Almost all patients diagnosed with these tumors have a poor prognostic outcome. We aimed to identify novel glioma prognosis-associated candidate genes.

Methods

We applied WebArrayDB software to span platform integrate and analyze the microarray datasets. We focused on a subset of the significantly up-regulated genes, the minichromosome maintenance (MCM) family. We used frozen glioma samples to predict the relationship between the expression of MCMs and patients outcome by qPCR and western blot.

Results

We found that MCMs expression was significantly up-regulated in glioma samples. MCM2-7 and MCM10 expressions were associated with WHO tumor grade. High MCM2 mRNA expression appeared to be strongly associated with poor overall survival in patients with high grade glioma. Furthermore, we report that MCM7 is strongly correlated with patient outcome in patients with WHO grade II-IV tumor. MCM3 expression was found to be up-regulated in glioma and correlated with overall survival in patients with WHO grade III tumor. MCM2, MCM3 and MCM7 expression levels were of greater prognostic relevance than histological diagnosis according to the current WHO classification system.

Conclusions

High expression of MCM 2, MCM3 and MCM7 mRNA correlated with poor outcome and may be clinically useful molecular prognostic markers in glioma.

Novel molecular markers of malignancy in histologically normal and benign breast

To detect the molecular changes of malignancy in histologically normal breast (HNB) tissues, we recently developed a novel 117-gene-malignancy-signature. Here we report validation of our leading malignancy-risk-genes, topoisomerase-2-alpha (TOP2A), minichromosome-maintenance-protein-2 (MCM2) and “budding-uninhibited-by-benzimidazoles-1-homolog-beta” (BUB1B) at the protein level. Using our 117-gene malignancy-signature, we classified 18 fresh-frozen HNB tissues from 18 adult female breast cancer patients into HNB-tissues with low-grade (HNB-LGMA; N = 9) and high-grade molecular abnormality (HNB-HGMA; N = 9). Archival sections of additional HNB tissues from these patients, and invasive ductal carcinoma (IDC) tissues from six other patients were immunostained for these biomarkers. TOP2A/MCM2 expression was assessed as staining index (%) and BUB1B expression as H-scores (0–300). Increasing TOP2A, MCM2, and BUB1B protein expression from HNB-LGMA to HNB-HGMA tissues to IDCs validated our microarray-based molecular classification of HNB tissues by immunohistochemistry. We also demonstrated an increasing expression of TOP2A protein on an independent test set of HNB/benign/reductionmammoplasties, atypical-ductal-hyperplasia with and without synchronous breast cancer, DCIS and IDC tissues using a custom tissue microarray (TMA). In conclusion, TOP2A, MCM2, and BUB1B proteins are potential molecular biomarkers of malignancy in histologically normal and benign breast tissues. Larger-scale clinical validation studies are needed to further evaluate the clinical utility of these molecular biomarkers.

Global molecular dysfunctions in gastric cancer revealed by an integrated analysis of the phosphoproteome and transcriptome

We integrated LC-MS/MS-based and protein antibody array-based proteomics with genomics approaches to investigate the phosphoproteome and transcriptome of gastric cancer cell lines and endoscopic gastric biopsies from normal subjects and patients with benign gastritis or gastric cancer. More than 3,000 non-redundant phosphorylation sites in over 1,200 proteins were identified in gastric cancer cells. We correlated phosphoproteome data with transcriptome data sets and reported the expression of 41 protein kinases, 5 phosphatases and 65 phosphorylated mitochondrial proteins in gastric cancer cells. Transcriptional expression levels of 190 phosphorylated proteins were >2-fold higher in gastric cancer cells compared to normal stomach tissue. Pathway analysis demonstrated over-presentation of DNA damage response pathway and underscored critical roles of phosphorylated p53 in gastric cancer. This is the first study to comprehensively report the gastric cancer phosphoproteome. Integrative analysis of the phosphoproteome and transcriptome provided an expansive view of molecular signaling pathways in gastric cancer.

MCM-2 and MCM-5 expression in gastric adenocarcinoma: clinical significance and comparison with Ki-67 proliferative marker

BACKGROUND

Minichromosome maintenance (MCM) proteins are essential components of DNA replication, being related to cell proliferation, and serve as useful biomarkers for cancer screening, surveillance and prognosis. The aim of the present study was to evaluate the clinical significance of MCM-2 and MCM-5 expression in gastric adenocarcinoma in comparison with Ki-67 proliferative marker.

METHODS

MCM-2, MCM-5 and Ki-67 expression was assessed immunohistochemically in 66 tumoral samples of gastric adenocarcinoma patients and was statistically analyzed in relation to clinicopathological characteristics and patient survival.

RESULTS

MCM-2 expression did not show significant associations with any clinicopathological parameters, while Ki-67 expression was merely significantly associated with tumor size (P = 0.0150). MCM-2 and Ki-67 expression were more frequently in intestinal (median values: 67.5 and 60%) compared to diffuse-type (median values: 60 and 45%) gastric adenocarcinoma cases without though reaching statistical significance (P > 0.05). MCM-5 expression was significantly associated with tumor size (P = 0.0295), presence of lymph node metastases (P = 0.0216) and tumor histopathological stage (P = 0.0098). Patients presenting high MCM-5 expression had significantly shorter survival times (log-rank test, P = 0.0042), whereas neither MCM-2 nor Ki-67 expression showed significant prognostic value (log-rank test, P = 0.9618 and P = 0.7174, respectively). In multivariate analysis, patient age, histopathological stage and grade of differentiation, but not MCM-5 expression, were identified as independent prognostic factors (Cox regression analysis, P = 0.0097, P = 0.0195, P = 0.0035 and P = 0.3245, respectively).

CONCLUSIONS

The present study showed that MCM-5 expression was associated with clinicopathological parameters in gastric adenocarcinoma. However, further studies highlighting the distinct impact of the two histopathological types, intestinal and diffuse, are warranted to delineate whether MCMs could be used as diagnostic and prognostic markers in gastric neoplasia.

Geminin, Ki67, and minichromosome maintenance 2 in gastric hyperplastic polyps, adenomas, and intestinal-type carcinomas: pathobiological significance

BACKGROUND

Geminin negatively regulates Cdt1 and induces the formation of prereplicative complexes by loading mini-chromosome maintenance proteins (Mcm) onto chromatin and limiting DNA replication to once per cell cycle. Recent studies have suggested that geminin expression is a marker of the S/G2/M phase of the cell cycle and is associated with a poor prognosis in various human malignancies. This study aimed to clarify the pathobiological role of geminin in intestinal-type gastric carcinoma, and its relationships with minichromosome maintenance 2 (Mcm2) and Ki67 expression.

METHODS

We performed western blot analysis of seven human gastric cancer cell lines, and immunohistochemical analysis of 72 gastric mucosal lesions and 128 surgically removed advanced intestinal-type gastric carcinomas. Double-labeling immuno-fluorescence was performed to identify the coexpression of geminin and Ki67.

RESULTS

Geminin was detected in all cell lines. Geminin labeling indices (LIs) in hyperplastic polyps, low-grade adenomas, high-grade adenomas, and intestinal-type adenocarcinomas were 3.9%, 10.5%, 18.6%, and 27.2%, respectively. The equivalent LIs for Ki67 and Mcm2 were 17.7%, 42.2%, 52.6%, and 59.7%; and 26.7%, 70.0%, 67.8%, and 77.8%, respectively. Double-labeling immunofluorescence revealed coexpression of geminin and Ki67 in both normal and tumor cells. The LI for geminin was significantly correlated with N stage, International Union Against Cancer (UICC) stage, Mcm2 LI, and Ki67 LI. Patients in stages I-IV and stage III with higher LIs for geminin (>25%) had significantly worse prognoses (P < 0.05 and P < 0.04, respectively). Univariate Cox regression analysis indicated that the overall survival of stage I-IV tumors was significantly correlated with high geminin LIs (relative risk [RR] = 1.94; P = 0.04).

CONCLUSIONS

Geminin expression might reflect the biological nature of gastric intramucosal neoplasms and could be a possible prognostic marker in advanced intestinal-type gastric carcinomas.

Minichromosome maintenance-7 and geminin are reliable prognostic markers in patients with oral squamous cell carcinoma: immunohistochemical study

BACKGROUND

Minichromosome maintenance (MCM) proteins act as the origin licensing machinery that regulates initiation of DNA replication. Geminin is a licensing repressor and prevents reinitiation of DNA replication by blocking reloading of MCM proteins at replication origins. Recent studies have proposed that MCM7 and geminin may be sensitive proliferative and prognostic markers of various malignant tumors. This study aimed to analyze the expression of MCM7 and geminin to clarify pathobiological significance in human oral squamous cell carcinomas (OSCCs).

METHODS

We performed immunohistochemical analysis on 10 specimens of normal oral epithelia, 50 lesions with dysplasia and 113 OSCCs. Labeling indices (LIs) for MCM7, geminin and Ki-67 were evaluated, comparing with clinicopathological profiles.

RESULTS

The mean LIs for MCM7 were 29.2% for normal epithelia, 32.2% for dysplasias, and 51.1% for OSCCs; the value was significantly higher in the last than in the former two (P < 0.01). The mean LIs for geminin were 6.8% for normal epithelia, 9.2% for dysplasias, and 21.3% for OSCCs; the value was significantly higher in the OSCCs (P < 0.01). The MCM7 LIs were correlated with the histological grade of OSCCs, in which the highest LIs were noted in the poorly differentiated type (P < 0.01). The survival rate was significantly lower in patients with a higher MCM7 LI (>49.5%) than in those with a lower LI (P < 0.05) at stage III-IV. However, the survival rate in the patients with a higher geminin LI (>19.5%) was significantly higher than in those with a lower LI (P < 0.05) at stage IV.

Expression of minichromosome maintenance 7 (MCM7) in small lung adenocarcinomas (pT1): Prognostic implication

Minichromosome maintenance (MCM) proteins, essential molecules in the initiation and elongation of DNA replication, have been considered to be good indicators of cell proliferation. We examined the expressions of MCM7 and Ki-67 in lung adenocarcinomas (ACs) with a diameter less than 3cm (pT1), to clarify their pathobiological significance. Immunohistochemistry was conducted to obtain labeling indices (LIs%) for MCM7, MCM2 and Ki-67 in 100 surgically removed pT1 ACs. The LIs were compared with clinicopathological profiles and overall survival rates. The mean LIs of MCM7 and Ki-67 were 20.2+/-15.2% and 13.7+/-11.2%, the value being higher in the former than in the latter (P<0.01). MCM7 LIs were significantly correlated with sex, histological grade, histological subtype, tumor size, LIs of Ki-67, MCM2 and P53 (P<0.05). LIs of MCM7 and Ki-67 were significantly higher in the 84 non-bronchioloalveolar carcinomas than in the 16 bronchioloalveolar carcinomas (P<0.01). Kaplan-Meier survival curves showed that patients with higher MCM7 LIs had poorer prognosis in the 100 pT1 ACs as well as in the 73 stage I ACs. Multivariate Cox regression analysis confirmed that the LIs of MCM7, but not the LIs of MCM2 and Ki-67, was an independent prognostic marker in the 73 stage I ACs. These results suggest that MCM7 is an independent prognostic marker, being more reliable than MCM2 or Ki-67 in human pT1 ACs as well as in human stage I ACs.