Aberrant expression of minichromosome maintenance protein-2 and Ki67 in laryngeal squamous epithelial lesions

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

The histopathological investigations of oral lesions are a basic approach for diagnosing ongoing cancer or pre-cancer associated pathological attributes in the dissected biopsy. The early detection and management of potentially malignant disorders of the lip and oral cavity that require intervention may reduce malignant transformations, or in case any malignancy is detected during surveillance, the appropriate treatment may improve survival rates. This would guide the clinicians to decide the appropriate treatment modality or lesion to achieve a more favorable prognosis. MCM2 protein is involved in DNA replication providing additional information about the prognosis of neoplasms. Some authors have pointed out that MCM proteins have been inversely correlated with salivary tumour differentiation and therefore could be an indicator of proliferation potential. Therefore, it is essential to find the expression of the MCM2 gene in oral leukoplakia and oral squamous cell carcinoma. Electronic databases like Ebscohost, Livivo, Google Scholar and PubMed were searched. Based on the inclusion and exclusion criteria, 2 reviewers (MS and SN) independently selected the relevant articles. Any disagreement was discussed until a consensus was reached. We used the QUADAS-2 tool to assess the quality of the included studies over four key domains: patient selection, index test, reference standard and flow and timing of participants through the study. 10 out of 57 titles were found to meet the eligibility criteria. Biopsied tissue with immunohistochemical staining or advanced diagnostic studies were included. A total of 901 samples were included in the study and different groups were normal oral mucosa (NOM), oral epithelial dysplasia (OED) and oral squamous cell carcinoma (OSCC). MCM2 proteins are useful diagnostic markers for distinguishing malignant from benign epithelial dysplasia and for early detection and diagnosis of OSCC as an adjunct to clinicopathological parameters.

Supplementary Information

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

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.

Immunohistochemical expression and evaluation of cyclin D1 and minichromosome maintenance 2 in oral squamous cell carcinoma and verrucous carcinoma

Background

The study of cell proliferation is important for assessing the tumor behavior, prognosis and patient survival of oral carcinomas. As literature search did not reveal sufficient studies of immunohistochemical expression of cyclin D1 and minichromosome maintenance 2 (MCM2) in oral squamous cell carcinoma (OSCC) and verrucous carcinoma (VC), the present study was undertaken.

Materials and Methods

The study group included 20 cases of histopathologically diagnosed OSCC, 10 cases of VC and 10 cases of normal mucosa (NM). All samples were evaluated for the expression of cyclin D1 and MCM2 using standard Immunohistochemistry (IHC) procedure.The present study involved both qualitative and quantitative analyses. Qualitative analysis was done by evaluation of intensity and area of staining. Quantitative analysis was done by calculating the percentage of positively stained cells and assessing the labeling index (LI). Data obtained were subjected to statistical analysis using SPSS statistical package (version 23.0).

Results

On evaluating and comparing the intensity of staining and area of staining of cyclin D1 and MCM2 between the study groups, statistically significant values (P < 0.05) were obtained using Kruskal-Wallis ANOVA. Comparison of LI of cyclin D1 and MCM2 in NM, OSCC and VC statistically significant results (P < 0.05) was obtained using Mann-Whitney U-test. Mean LI of MCM2 was found to be significantly higher than mean LI of cyclin D1 in all the study groups.

Conclusion

From the present study, we conclude that MCM2 has the potential to serve as a novel cell proliferation biomarker in OSCC and VC when compared to cyclin D1.

MCM-2, Ki-67, and EGFR downregulated expression levels in advanced stage laryngeal squamous cell carcinoma

We present the conceptual study investigated the capacity of minichromosome maintenance-2 (MCM-2), Ki-67, and epidermal growth factor receptor (EGFR) to assess the severity and progression of laryngeal squamous cell carcinoma (LSCC) disease and to study the correlations among these markers. A total of 30 patients with LSCC with immunohistochemistry (IHC) staining for MCM-2, Ki-67 and EGFR were examined. Mean expression levels of the three markers were evaluated for comparing between early and advanced stages of LSCC. The mean MCM-2, Ki-67, and EGFR expression levels were significantly decreased in advanced-stage compared with early-stage LSCC. Pearson correlation analysis showed a statistically significant correlation between the MCM-2 and Ki-67. Regarding subgroup analyses, MCM-2, Ki-67, and EGFR showed significant differences between early- and advanced-stage LSCC with non-recurrence, while for the recurrent subgroup LSCC, only MCM-2 revealed a significant difference between early- and advanced-stage LSCC. Altogether, these results support the role for downregulation of MCM-2, Ki-67 and EGFR in advanced-stage LSCC and correlation of MCM-2 and Ki-67 expressions that would be a promising strategy to predict prognosis of LSCC including severity and progression. We contextualize our findings and advocate the position of the biological markers, especially MCM-2, as an emerging evaluation tool for LSCC disease.

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.

Immunohistochemical Expression of MCM-2 in Oral Epithelial Dysplasias

BACKGROUND

Oral cancer is one of the most frequent cancers in the world. It arises from epithelial dysplasia. Hence, identifying these lesions in an early stage could prevent their malignant transformation. The aim of the present work was to assess the cell proliferative activity of minichromosome maintenance protein (MCM-2) in oral epithelial dysplastic lesions and to correlate the results with different grades of epithelial dysplasia in an attempt to use MCM-2 in the early detection of malignancy.

METHODS

MCM-2 expression was determined by the nuclear count in a total of 30 oral epithelial dysplastic specimens roughly classified into 10 cases of mild, moderate, and severe dysplasia. Five cases of early invasive squamous-cell carcinomas and 5 cases of epithelial hyperplasia were also included.

RESULTS

The MCM-2 immunostaining was found to increase gradually from mild to moderate to severe dysplasia and reached its maximum value in early invasive squamous cell carcinoma.

CONCLUSION

MCM-2 is of prognostic value in cases of oral dysplasia that have a tendency to undergo malignant transformation.

Assessment of Proliferative Index Between the Tumor Margin, Center of Tumor, and the Invasive Tumor Front of Oral Squamous Cell Carcinoma With the Help of Mcm-2: An Immunohistochemical Study

AIM

The knowledge of cellular proteins that involves cell cycle and its control system is essential for understanding tumor biology. Minichromosome maintenance protein (Mcm-2), a component of prereplicative complex, essential for initiating DNA replication, is deregulated in different malignant lesions, and is expressed throughout the whole cell cycle including the G0 and G1 phases. This characteristic cell cycle event is not found in other proliferative markers such as geminin, AgNOR, Ki-67, and proliferating cell nuclear antigen. The aim of the present study was to analyze and compare the expression of Mcm-2 in normal oral mucosa (NM) and oral squamous cell carcinomas at tumor margins (TM), the tumor center (TC), and the invasive tumor front (ITF), with correlation of clinicopathologic features.

MATERIALS AND METHODS

Tissues from 50 oral squamous cell carcinomas and 10 NM were archived retrospectively and stained with an antibody directed against the Mcm-2 antigen. A quantitative method was used to score the Mcm-2 expression in NM, TM, TC, and ITF. Nuclei labeling index for each case was estimated as the percentage of immunoreactive nuclei among 500 cells separately for NM, TM, TC, and ITF.

RESULTS

Nuclei labeling index increases progressively from NM (49.08%), TM (67.79%), and TC (76.87%) to ITF (87.77%).

CONCLUSIONS

Cell proliferation by Mcm-2 at the ITF had a strong positive relationship with TC, TM. Mcm-2, a pan-cell cycle marker, is more sensitive in comparison with other conventional proliferative markers, which can be a better prognostic indicator.

MCM-2 expression differentiates potentially malignant verrucous lesions from oral carcinomas

BACKGROUND

Mcm-2 is a biomarker belonging to Mcm family of proteins which has rarely been used in oral potentially malignant and malignant lesions of the verrucous type. The objective of this study is to assess the expression of Mcm-2 in Normal Oral Mucosa (NM), Verrucous Hyperplasia (VH), Verrucous Carcinoma (VC) and Oral Squamous Cell Carcinoma (OSCC) and compare it with the clinicopathological characteristics.

METHODOLOGY

A total of 70 formalin fixed paraffin embedded tissue samples (10 cases of Normal Mucosa NM- Group A, 10 cases of Verrucous Hyperplasia- VH without Dysplasia- Group B, 10 cases of Verrucous Hyperplasia- VH with Dysplasia- Group C, 20 cases of Verrucous Carcinoma VC-Group D, 20 cases of Oral Squamous Cell Carcinoma OSCC- Group E) were subjected to immunohistochemistry with Mcm-2 antibody. Statistical analysis was carried out with various tests like ANOVA, Tukey HSD, Chi-Square and Shapiro-Wilk test by using the SPSS software.

RESULTS

There was a significant difference in Mcm-2 expression with quantitative analysis among all the groups (p < 0.05). There was a significant progressive increase in nuclear Labelling Indices (nLI) from NM (49.08%), VC (60.45%), VH with Dysplasia (64.10%), and OSCC (89.22%).

CONCLUSION

The findings suggest that Mcm-2 may be a sensitive proliferation marker in oral potentially malignant and malignant lesions which may be useful for differentiating between VH with/ without dysplasia, VC and OSCC.

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.

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.

MCM2 expression in serrated polyps demonstrates aberrant cellular proliferation

In normal colonic epithelium, the proliferative zone is limited to the lower half of the colonic crypt. Evaluating the changes in the colonic epithelial proliferation can be useful in understanding pathophysiology of various diseases. Our aim was to investigate the proliferative compartment of serrated polyps (SPs) using MCM2, a protein involved in DNA replication, and assess for changes along the SP spectrum. Immunohistochemistry was performed on serrated polyps (16 microvesicular-type hyperplastic polyps (HP), 58 sessile serrated adenomas (SSA), 7 SSAs with dysplasia) and 6 sections of normal colon using anti-MCM2 antibody. Multiple sections of normal colon showed the following pattern for MCM2 and Ki-67 staining: positive nuclear staining of the lower half of the colonic crypts and/or slightly expanded to the lower two-thirds of the crypt. By MCM2, SPs show expansion of the proliferative compartments; 81.3% of HPs and 100% of SSAs showed some degree of full crypt MCM2 staining. SSAs with dysplasia showed consistent diffuse polyp staining. Aberrant staining in adjacent normal mucosa was also seen in SSAs with dysplasia and in a subset of non-dysplastic SSAs. By using MCM2, we show that serrated polyps exhibit changes in proliferation during progression along the pathway. HPs and SSAs show a similar highly proliferative profile. Aberrant proliferative cell staining patterns in adjacent normal colonic mucosa as seen in SSAs with dysplasia and a subset of SSAs suggest a field effect phenomenon. This indicates that changes in the colonic micro-environment may promote adenoma morphogenesis and predisposition to malignancy.

Minichromosome maintenance protein 7 and geminin expression: Prognostic value in laryngeal squamous cell carcinoma in patients treated with radiotherapy and cetuximab

BACKGROUND

Minichromosome maintenance protein 7 (MCM7) is a downstream of human epidermal growth receptor (HER1) signaling. We examined MCM7, geminin, and HER1 expression in patients with laryngeal squamous cell carcinoma (SCC) treated with radiotherapy and cetuximab.

METHODS

MCM7, geminin, and HER1 were evaluated by immunohistochemistry on 61 patients with laryngeal SCC. The follow-up (median, 32.1 months; range, 2-139 months) went from the beginning of therapy to tumor progression-free survival (PFS) and death (overall survival [OS]).

RESULTS

MCM7, but not geminin, was associated only with HER1 expression, whereas no association was found with other clinicopathological characteristics. Patients with MCM7 high - geminin high and MCM7 high - geminin low tumor status had a risk of progression 3.1 times and 17.7 times greater, respectively, than patients with MCM7 low - geminin high tumor status. Tumor site, MCM7, and geminin were independent determinants of PFS, whereas MCM7 was an independent prognostic marker of OS.

CONCLUSION

MCM7-geminin tumor status may be prognostic for patients with laryngeal SCC treated with cetuximab and radiotherapy. © 2016 Wiley Periodicals, Inc. Head Neck 39: 684-693, 2017.

MCM2 and TIP30 are prognostic markers in squamous cell/adenosquamous carcinoma and adenocarcinoma of the gallbladder

The clinicopathological and biological characteristics of squamous cell/adenosquamous carcinoma (SC/ASC) of the gallbladder remain to be fully elucidated, due to the fact that it is a rare gallbladder cancer subtype. In the current study, the expression of minichromosome maintenance complex component 2 (MCM2) and HIV‑1 tat interactive protein 2 (TIP30) was measured in 46 cases of SC/ASC and 80 adenocarcinomas (AC) using immunohistochemistry. Positive MCM2 and negative TIP30 expression were significantly associated with large tumor size, high TNM stage, invasion, lymph node metastasis and lack of surgical curability in SC/ASC and AC. Positive MCM2 and negative TIP30 expression were significantly associated with poor differentiation in AC, whereas only MCM2 was correlated with differentiation in SC/ASC. Univariate Kaplan‑Meier analysis demonstrated that positive MCM2 and negative TIP30 expression, the degree of differentiation, tumor size, TNM stage, invasion, lymph node metastasis and surgical curability were significantly associated with post‑operative survival in patients with SC/ASC and AC. Multivariate Cox regression analysis demonstrated that positive MCM2 and negative TIP30 expression, the degree of differentiation, tumor size, TNM stage, invasion, lymph node metastasis and lack of surgical curability were also independent predictors of poor prognosis in patients with SC/ASC and AC. These data suggest that positive MCM2 and negative TIP30 expression are closely correlated with the clinical, pathological and biological parameters, in addition to poor prognosis in patients with gallbladder cancer.

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.

Identification of key genes for laryngeal squamous cell carcinoma using weighted co-expression network analysis

Laryngeal squamous cell carcinoma (LSCC) is the most common malignant tumor in the head and neck, and can seriously affect the daily life of patients. To study the mechanisms of LSCC, the microarray of GSE51958 was analyzed in the present study. GSE51958 was downloaded from Gene Expression Omnibus, and included a collection of LSCC tissue samples and matched adjacent non-cancerous tissue samples from 10 patients. Differentially-expressed genes (DEGs) were identified using limma package. Next, a weighted co-expression network was constructed for the DEGs by WGCNA package in R. Modules of the weighted co-expression network were obtained through constructing a hierarchical clustering tree using the hybrid dynamic shear tree method. Using the clusterProfiler package, the potential functions of DEGs in the modules correlated with LSCC were predicted by pathway enrichment analysis. In total, 959 DEGs were screened from the LSCC samples compared with the adjacent non-cancerous samples, including 553 upregulated and 406 downregulated genes. The appointed black, brown, gray, pink and yellow modules were screened for the DEGs in the weighted co-expression network. For the DEGs in the brown and yellow modules, the enriched pathways were cytokine-cytokine receptor interaction and metabolic pathways, respectively. The DEGs in the pink module were involved in the majority of pathways. With high connectivity degrees in the pink module, TPX2, microtubule-associated (TPX2; degree, 25), minichromosome maintenance complex component 2 (MCM2; degree, 25), ubiquitin-like with PHD and ring finger domains 1 (UHRF1; degree, 22), cyclin-dependent kinase 2 (CDK2; degree, 20) and protein regulator of cytokinesis 1 (PRC1; degree, 20) may be involved in LSCC. Overall, In conclusion, from the integrated bioinformatics analysis of genes that may be associated with LSCC, 959 DEGs were obtained from LSCC samples compared with adjacent non-cancerous samples, and TPX2, MCM2, UHRF1, CDK2 and PRC1 were found to hold a possible association with the disease.

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.

Proteomic Study to Survey the CIGB-552 Antitumor Effect

CIGB-552 is a cell-penetrating peptide that exerts in vitro and in vivo antitumor effect on cancer cells. In the present work, the mechanism involved in such anticancer activity was studied using chemical proteomics and expression-based proteomics in culture cancer cell lines. CIGB-552 interacts with at least 55 proteins, as determined by chemical proteomics. A temporal differential proteomics based on iTRAQ quantification method was performed to identify CIGB-552 modulated proteins. The proteomic profile includes 72 differentially expressed proteins in response to CIGB-552 treatment. Proteins related to cell proliferation and apoptosis were identified by both approaches. In line with previous findings, proteomic data revealed that CIGB-552 triggers the inhibition of NF-κB signaling pathway. Furthermore, proteins related to cell invasion were differentially modulated by CIGB-552 treatment suggesting new potentialities of CIGB-552 as anticancer agent. Overall, the current study contributes to a better understanding of the antitumor action mechanism of CIGB-552.

Evaluation of Minichromosome Maintenance-3 (MCM3) in Oral Squamous Cell Carcinoma

STATEMENT OF THE PROBLEM

The expression of minichromosome maintenance-3 (MCM3) proteins and their diagnostic value in oral mucosal dysplasia and squamous cell carcinoma (SCC) is not well known.

PURPOSE

This study was conducted to evaluate the usefulness of minichromosome maintenance 3 (MCM3) as a biomarker for diagnosis of oral premalignant lesions and SCC.

MATERIALS AND METHOD

In this study, 31 oral SCC, 20 dysplastic epithelium and 20 controls were selected and immunohistochemical staining was done for MCM3. ANOVA, Tukey HSD, Mann-Whitney and Kruskal-Wallis tests were used to compare the groups and the correlation between different grades.

RESULTS

There was increasing trend of MCM3 from control to dysplastic epithelium and from dysplastic epithelium to SCC both in suprabasal layers and in total epithelial layers. MCM3 expression was elevated with increasing the grade of dysplasia, but there was no statistically significant difference (p= 0.93). The expression was also increased in high grades of SCC compared to lower grades.

CONCLUSION

MCM3 can be used as a useful biomarker in the diagnosis of premalignant lesions and oral SCC.

Gene expression profiling via bioinformatics analysis reveals biomarkers in laryngeal squamous cell carcinoma

The present study aimed to identify key genes and relevant microRNAs (miRNAs) involved in laryngeal squamous cell carcinoma (LSCC). The gene expression profiles of LSCC tissue samples were analyzed with various bioinformatics tools. A gene expression data set (GSE51985), including ten laryngeal squamous cell carcinoma (LSCC) tissue samples and ten adjacent non-neoplastic tissue samples, was downloaded from the Gene Expression Omnibus. Differential analysis was performed using software package limma of R. Functional enrichment analysis was applied to the differentially expressed genes (DEGs) using the Database for Annotation, Visualization and Integrated Discovery. Protein-protein interaction (PPI) networks were constructed for the protein products using information from the Search Tool for the Retrieval of Interacting Genes/Proteins. Module analysis was performed using ClusterONE (a software plugin from Cytoscape). MicroRNAs (miRNAs) regulating the DEGs were predicted using WebGestalt. A total of 461 DEGs were identified in LSCC, 297 of which were upregulated and 164 of which were downregulated. Cell cycle, proteasome and DNA replication were significantly over-represented in the upregulated genes, while the ribosome was significantly over-represented in the downregulated genes. Two PPI networks were constructed for the up- and downregulated genes. One module from the upregulated gene network was associated with protein kinase. Numerous miRNAs associated with LSCC were predicted, including miRNA (miR)-25, miR-32, miR-92 and miR-29. In conclusion, numerous key genes and pathways involved in LSCC were revealed, which may aid the advancement of current knowledge regarding the pathogenesis of LSCC. In addition, relevant miRNAs were also identified, which may represent potential biomarkers for use in the diagnosis or treatment of the disease.

MCM Paradox: Abundance of Eukaryotic Replicative Helicases and Genomic Integrity

As a crucial component of DNA replication licensing system, minichromosome maintenance (MCM) 2–7 complex acts as the eukaryotic DNA replicative helicase. The six related MCM proteins form a heterohexamer and bind with ORC, CDC6, and Cdt1 to form the prereplication complex. Although the MCMs are well known as replicative helicases, their overabundance and distribution patterns on chromatin present a paradox called the “MCM paradox.” Several approaches had been taken to solve the MCM paradox and describe the purpose of excess MCMs distributed beyond the replication origins. Alternative functions of these MCMs rather than a helicase had also been proposed. This review focuses on several models and concepts generated to solve the MCM paradox coinciding with their helicase function and provides insight into the concept that excess MCMs are meant for licensing dormant origins as a backup during replication stress. Finally, we extend our view towards the effect of alteration of MCM level. Though an excess MCM constituent is needed for normal cells to withstand stress, there must be a delineation of the threshold level in normal and malignant cells. This review also outlooks the future prospects to better understand the MCM biology.

Replication proteins and human disease

In this article, we discuss the significance of DNA replication proteins in human disease. There is a broad range of mutations in genes encoding replication proteins, which result in several distinct clinical disorders that share common themes. One group of replication proteins, the MCMs, has emerged as effective biomarkers for early detection of a range of common cancers. They offer practical and theoretical advantages over other replication proteins and have been developed for widespread clinical use.

Morphometric analysis of Ki-67 and p16 expression in laryngeal precursor lesions

Laryngeal precursor lesions represent areas of altered epithelium with an increased likelihood for progression to squamous cell carcinoma. The exact molecular mechanisms of malignant transformation of laryngeal mucosa are not completely clear, but are certainly due to deregulation of cell proliferation. To assess the potential value of the p16 and Ki-67 as markers of malignant progression, we undertook a retrospective immunohistochemical and morphometric analysis on biopsy specimens from patients with precancerous lesions in the larynx. Morphometric analysis of samples stained with p16 antibody showed epithelial cell positivity in 29 (100 %) of samples with simple hyperplasia, 31 (100 %) samples with basal/parabasal cell hyperplasia, 23 (88 %) samples with atypical hyperplasia and 20 (95 %) samples with in situ carcinoma. There was a significant difference in percentage of p16-positive cells between samples with simple hyperplasia and samples with in situ carcinoma. Morphometric analysis of samples stained with Ki-67 antibody showed epithelial cell positivity in 27 (93 %) of samples with simple hyperplasia, 30 (97 %) samples with basal/parabasal cell hyperplasia, 26 (100 %) samples with atypical hyperplasia and 18 (86 %) samples with in situ carcinoma. There was a significant difference not only in the percentage of Ki-67-positive cells between samples with simple hyperplasia and samples with in situ carcinoma, but also between samples with simple and basal/parabasal cell hyperplasia. Laryngeal epithelial precursor lesions show significantly opposite patterns in p16 and Ki-67 immunopositivity. Simple hyperplasia on average shows 12 % of Ki-67-positive cells and 46 % of p16-positive cells. In situ carcinoma on average shows 23 % of Ki-67-positive cells and 36 % of p16-positive cells.

Molecular Basis for Advances in Cervical Screening

Human papillomaviruses (HPVs) cause cervical lesions, which can, in some instances, progress to high-grade neoplasia and cancer. Around half a million cases of cervical cancer occur each year, with most occurring in developing countries where cervical cancer is a major cause of cancer-related death. The reduction in cervical cancer incidence in developed countries is largely attributed to the introduction of cervical screening. Cervical screening currently depends on the identification by cytology of abnormalities in cells taken from the surface of the cervix. The standard Pap test was developed >50 years ago, and despite modifications, still forms the basis of the test currently in use in most routine screening laboratories. Advances in our understanding of the molecular mechanisms that lead to the development of cervical cancer have been slow to impact on screening, despite the relatively high false-negative rates that can be associated with the conventional Pap smear. Improvements in screening strategies fall into a number of categories. Methods that improve cell presentation and attempt to eliminate artefacts/obscuring debris can be combined with image analysis systems in order to enhance diagnostic accuracy. Such approaches still rely on cytological evaluation and do not incorporate advances in our knowledge of how HPV causes cancer. By contrast, markers of virus infection or cell cycle entry, particularly those that offer some degree of prognostic significance, may be able to highlight abnormal cells more reliably than cytology, and could be combined with cytology to improve the detection rate. Our understanding of the molecular biology of HPV infection and the organization of the HPV life-cycle during cancer progression provides a rational basis for marker selection. The general assumption that persistent active infection by high-risk HPV types is the true precursor of cervical cancer provides the rationale for HPV DNA testing in conjunction with enhanced cytology, while the development of RNA-based approaches should allow active infections to be distinguished from those that are latent. The detection in superficial cells of marker combinations at the level of RNA or protein has the potential to predict disease status more precisely than the detection of markers in isolation. There is also a need for better prognostic markers if the predictive value of screening is to be improved. The potential to control infection by vaccination should reduce the incidence of HPV-associated neoplasia in the population, and this may cause a change in the way that screening is carried out. Nevertheless, the lack of a therapeutic vaccine, and the difficulties associated with eliminating infection by multiple high-risk HPV types, means that some form of screening will still be required as a preventive measure for the control of cervical cancer for the foreseeable future.

Diagnosis of bladder cancer by immunocytochemical detection of minichromosome maintenance protein-2 in cells retrieved from urine

Background:

We tested the accuracy of immunocytochemistry (ICC) for minichromosome maintenance protein-2 (MCM-2) in diagnosing bladder cancer, using cells retrieved from urine.

Methods:

Adequate samples were obtained from 497 patients, the majority presenting with gross haematuria (GH) or undergoing cystoscopic surveillance (CS) following previous bladder cancer. We performed an initial study of 313 patients, followed by a validation study of 184 patients. In all cases, presence/absence of bladder cancer was established by cystoscopy/biopsy.

Results:

In the initial study, receiver operator characteristic analysis showed an area under the curve of 0.820 (P<0.0005) for the GH group and 0.821 (P<0.01) for the CS group. Optimal sensitivity/specificity were provided by threshold values of 50+ MCM-2-positive cells in GH samples and 200+ cells in CS samples, based on a minimum total cell number of 5000. Applying these thresholds to the validation data set gave 81.3% sensitivity, 76.0% specificity and 92.7% negative predictive value (NPV) in GH and 63.2% sensitivity, 89.9% specificity and 89.9% NPV in CS. Minichromosome maintenance protein-2 ICC provided clinically relevant improvements over urine cytology, with greater sensitivity in GH and greater specificity in CS (P=0.05).

Conclusions:

Minichromosome maintenance protein-2 ICC is a reproducible and accurate test that is suitable for both GH and CS patient groups.

[Dysplasia and laryngeal carcinoma in situ]

Although the glottis is amenable to chemotherapy, currently most lesions from stage I laryngeal dysplasia up to carcinoma in situ are excised. This literature review presents selected molecular biological aspects especially in relation to dysplasia of the larynx and its therapy, as well as currently preferred biomarkers for chemotherapeutic prevention of laryngeal dysplasia.

Potential role of minichromosome maintenance protein 2 as a screening biomarker in esophageal cancer high-risk population in China

Minichromosome maintenance proteins are novel proliferative markers that have been proposed as diagnostic markers in many cancers. We evaluated the potential role of minichromosome maintenance protein 2 as a screening biomarker and compared it with proliferating cell nuclear antigen and Ki67 in a population survey of esophageal squamous cell carcinoma. A total of 299 esophageal samples from a high-risk region in China, including 171 from an endoscopy population survey, 30 from brushing cytology, and 98 from surgery and autopsy, underwent immunostaining with minichromosome maintenance protein 2, proliferating cell nuclear antigen, and Ki67 antibodies. Minichromosome maintenance protein 2 expression was confined to the proliferative compartment of normal and abnormal esophageal epithelium and particularly manifested in the surface layer of dysplasia and carcinoma in situ. The expression of proliferating cell nuclear antigen and Ki67 was positively correlated with that of minichromosome maintenance protein 2 (r(s) >0.39, P < .01); but their positive nuclei seldom reached the surface layer, and the labeling indices were significantly lower than those for minichromosome maintenance protein 2 in dysplasia (P < .05) and carcinoma in situ (P < .001). The sensitivity and specificity of minichromosome maintenance protein 2 in diagnosing dysplasia were 91.3% and 61.8%, respectively, higher than those for proliferating cell nuclear antigen (88.4% and 47.1%) and Ki67 (78.3% and 57.8%). Nine of 10 cancer and paracancerous surface-brushing samples expressed minichromosome maintenance protein 2, and the detection was higher than that for proliferating cell nuclear antigen (8/10 and 7/10) and Ki67 (7/10 and 7/10). However, none of 10 normal surface-brushing samples expressed the 3 markers. Minichromosome maintenance protein 2 is more sensitive and specific than proliferating cell nuclear antigen and Ki67 in indicating esophageal dysplasia. Minichromosome maintenance protein 2 immunostaining combined with surface brushing could be valuable in screening patients at high risk of cancer in mass surveys.

Immunohistochemical evaluation of Ki-67, PCNA and MCM2 proteins proliferation index (PI) in advanced gastric cancer

The current study objective was to assess the proliferation indices (PI) of Ki-67, PCNA and MCM2 proteins in advanced gastric cancer and in metastatic lymph node in correlation with certain clinicopathological features and with postoperative survival of patients. The study was conducted in a group of 100 patients with advanced gastric cancers. Involvement of local lymph nodes was present in 36 cases. Immunohistochemical investigations were carried out using monoclonal antibodies against Ki-67 (DAKO), PCNA (DAKO) and polyclonal antibody to MCM2 (Santa Cruz Biotechnology). Visualization of the antigen/antibody complex was performed using LSAB technique (biotin-streptavidin-peroxidase) followed by application of chromogene DAB (DAKO). Statistical analysis revealed no correlations of Ki-67, PCNA and MCM2 PI in tumour tissue or metastatic lymph node with patients' age and gender, tumour location, histological grade, macroscopic type according to Bormann's classification and histological grading by Lauren's and Goseki's classifications. Moreover, no correlation was observed of Ki-67 and MCM2 PI in tumour tissue with histological grading. No correlation was also noted between the proliferation indices of all the three proteins in the affected lymph node and grade of histological differentiation. Such clinicopathological parameters as patients' age and gender, histological grading by Lauren's and Goseki's classifications and lymph node involvement did not correlate with survival time of patients. Furthermore, no statistically significant correlation was shown of postoperative survival time with Ki-67 and MCM2 PI in tumour tissue and metastatic lymph nodes and with PCNA PI in the affected lymph nodes. However, a statistically significant correlation was found of Ki-67, PCNA and MCM2 PI in tumour tissue and metastatic lymph nodes with depth of wall invasion and local lymph node involvement. A statistically significant correlation was also noted between PCNA PI in the main mass of tumour and histological grading. The postoperative survival time of patients exhibited a statistically significant correlation with tumour location and macroscopic type according to Bormann's classification. Correlations on statistical borderline were noted between survival time and depth of gastric wall invasion and PCNA PI in the main mass of tumour.

Regulation of minichromosome maintenance gene family by microRNA-1296 and genistein in prostate cancer

The minichromosome maintenance (MCM) gene family is essential for DNA replication and is frequently upregulated in various cancers. Here, we examined the role of MCM2 in prostate cancer and the effect of microRNA-1296 (miR-1296), genistein, and trichostatin A (TSA) on the MCM complex. Profiling results showed that expression of MCM genes was higher in tumor samples. Genistein and TSA significantly downregulated the expression of all MCM genes. Genistein, TSA, and small interfering RNA duplexes caused a significant decrease in the S phase of the cell cycle. There was also downregulation of CDT1, CDC7, and CDK2 genes, which govern loading of the MCM complex on chromatin. We also found that miR-1296 was significantly downregulated in prostate cancer samples. In PC3 cells, inhibition of miR-1296 upregulated both MCM2 mRNA and protein, whereas overexpression caused a significant decrease in MCM2 mRNA, protein, and the S phase of the cell cycle. MCM genes are excellent anticancer drug targets because they are essential DNA replication factors that are highly expressed in cancer cells. This is the first report showing anti-MCM effect by miR-1296, genistein, and TSA. TSA is undergoing clinical trials as a prostate cancer treatment but has high toxicity. Genistein, a natural, nontoxic dietary isoflavone, may be an advantageous therapeutic agent for treating prostate cancer. The use of RNA interference is currently being implemented as a gene-specific approach for molecular medicine. The specific downregulation of oncogenes by miR may contribute to novel therapeutic approaches in the treatment of prostate cancer.

Global MYCN transcription factor binding analysis in neuroblastoma reveals association with distinct E-box motifs and regions of DNA hypermethylation

Background

Neuroblastoma, a cancer derived from precursor cells of the sympathetic nervous system, is a major cause of childhood cancer related deaths. The single most important prognostic indicator of poor clinical outcome in this disease is genomic amplification of MYCN, a member of a family of oncogenic transcription factors.

Methodology

We applied MYCN chromatin immunoprecipitation to microarrays (ChIP-chip) using MYCN amplified/non-amplified cell lines as well as a conditional knockdown cell line to determine the distribution of MYCN binding sites within all annotated promoter regions.

Conclusion

Assessment of E-box usage within consistently positive MYCN binding sites revealed a predominance for the CATGTG motif (p<0.0016), with significant enrichment of additional motifs CATTTG, CATCTG, CAACTG in the MYCN amplified state. For cell lines over-expressing MYCN, gene ontology analysis revealed enrichment for the binding of MYCN at promoter regions of numerous molecular functional groups including DNA helicases and mRNA transcriptional regulation. In order to evaluate MYCN binding with respect to other genomic features, we determined the methylation status of all annotated CpG islands and promoter sequences using methylated DNA immunoprecipitation (MeDIP). The integration of MYCN ChIP-chip and MeDIP data revealed a highly significant positive correlation between MYCN binding and DNA hypermethylation. This association was also detected in regions of hemizygous loss, indicating that the observed association occurs on the same homologue. In summary, these findings suggest that MYCN binding occurs more commonly at CATGTG as opposed to the classic CACGTG E-box motif, and that disease associated over expression of MYCN leads to aberrant binding to additional weaker affinity E-box motifs in neuroblastoma. The co-localization of MYCN binding and DNA hypermethylation further supports the dual role of MYCN, namely that of a classical transcription factor affecting the activity of individual genes, and that of a mediator of global chromatin structure.

DNA replication licensing factors and aneuploidy are linked to tumor cell cycle state and clinical outcome in penile carcinoma

PURPOSE

The DNA replication licensing machinery is integral to the control of proliferation, differentiation, and maintenance of genomic stability in human cells. We have analyzed replication licensing factors (RLF), together with DNA ploidy status, to investigate their role in progression of penile squamous cell carcinoma and to assess their utility as novel prognostic tools.

EXPERIMENTAL DESIGN

In a cohort of 141 patients, we linked protein expression profiles of the standard proliferation marker Ki67 and the RLFs Mcm2 and geminin to clinicopathologic variables, ploidy status, and clinical outcome.

RESULTS

Increased Ki67, Mcm2, and geminin levels were each significantly associated with arrested tumor differentiation (P < 0.0001) and aneuploidy (P < or = 0.01). Accelerated cell cycle progression was linked to increasing tumor size, stage, and depth of invasion. Aneuploid tumors significantly correlated with tumor grade (P < 0.0001). Biomarker expression and DNA ploidy status were significant predictors of locoregional disease progression [Mcm2 (P = 0.02), geminin (P = 0.02), Ki67 (P = 0.03), and aneuploidy (P = 0.03)] in univariate analysis. Importantly, aneuploidy was a strong independent prognosticator for overall survival (hazard ratio, 4.19; 95% confidence interval, 1.17-14.95; P = 0.03). Used in conjunction with conventional pathologic information, multiparameter analysis of these variables can stratify patients into low- or high-risk groups for disease progression (Harrell's c-index = 0.88).

CONCLUSIONS

Our findings suggest that RLFs and tumor aneuploidy may be used as an adjunct to conventional prognostic indicators, identifying men at high risk of disease progression. Our results also identify the DNA replication initiation pathway as a potentially attractive therapeutic target in penile squamous cell carcinoma.

Expression of Mcm2, geminin and Ki67 in normal oral mucosa, oral epithelial dysplasias and their corresponding squamous-cell carcinomas

Proteins necessary for the normal regulation of the cell cycle include minichromosome maintenance protein 2 (Mcm2) and geminin. These are overexpressed in several premalignant and malignant tumours. The Mcm2/Ki67 ratio can be used to estimate the population of cells that are in early G₁ (licensed to proliferate), and the geminin/Ki67 ratio can determine the relative length of G₁. A high ratio indicates a short G₁ and a high rate of cell proliferation. Mcm2 and geminin have been scarcely explored in oral epithelial dysplasia (OED) and oral squamous-cell carcinoma (OSCC). The purpose of this study was to identify the expression pattern of Mcm2, Ki67 and geminin in normal oral mucosa (NOM), OED and their subsequent OSCC, to determine if expression could help predict the prognosis of OED. Paraffin sections of 41 OED cases that progressed to carcinoma, 40 OED without malignant progression, 38 OSCC and 15 NOM were immunostained with antibodies against Mcm2, geminin and Ki67. Labelling indices (LIs) increased progressively from NOM, OED and OSCC (Mcm2, P<0.001; geminin, P<0.001 and Ki67, P<0.001). In all the OED cases (n=81) the levels of expression of Mcm2 (LI, 73.6), geminin (LI, 24.4) and Ki67 (LI, 44.5) were elevated indicating a constant cell-cycle re-entry. When the OED groups were compared, Mcm2 protein expression was higher in the OED with malignant progression (P=0.04), likewise there was a significant increase in the Mcm2/Ki67 and geminin/Ki67 ratios (P=0.04 and 0.02 respectively). Mcm2 and geminin proteins seem to be novel biomarkers of growth and may be useful prognostic tools for OED.

Improved screening for anal neoplasia by immunocytochemical detection of minichromosome maintenance proteins

PURPOSE

Early detection of anal intraepithelial neoplasia (AIN) and anal squamous cell carcinoma (SCC) by screening will improve clinical outcome. Assessment of anal cytology samples using routine Papanicolaou testing suffers from shortcomings in sensitivity and/or specificity, suggesting that screening tests based on biomarkers may be of value. We tested the suitability in this context of minichromosome maintenance (MCM) proteins, accurate markers of the deregulated cell cycle entry that characterizes malignancy and premalignancy.

EXPERIMENTAL DESIGN

We undertook an initial immunohistochemical study of 54 anal tissue samples and validated our findings using an independent prospective cohort study of 235 anal cytology samples from 144 subjects.

RESULTS

In the progression from normal anal epithelium through AIN to SCC, there was increasing expression of MCM2 and MCM5, including in the superficial epithelial third, the source of the majority of cells collected by anal swab. The median labeling indices (LI) for MCM2 and MCM5 in the superficial third of AIN2/3 and SCCs combined were 90.2% and 84.0%, respectively. MCM LIs in the superficial layers were significantly greater than LIs for Ki67, an alternative marker of cell cycle entry (P<0.0001). By immunocytochemistry using a mixture of anti-MCM2 and anti-MCM5 antibodies, immunopositive cells were readily identified in anal cytology samples, even at low magnification. MCM testing showed sensitivity for AIN2/3 of 84% (95% confidence interval, 75,93) and for AIN1/viral changes of 76% (68, 84), with overall specificity (for any lesion) of 77% (64, 90).

CONCLUSIONS

MCMs are promising biomarkers for improving detection of AIN and SCC in anal cytology samples.

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

BACKGROUND

The origin licensing factor minichromosome maintenance 2 (MCM2) has recently been identified as a critical regulator of proliferation in both normal and neoplastic cells. This study examined whether MCM2 expression was of prognostic relevance in patients with stage III gastric carcinoma and whether the expression of this marker showed any correlation with clinicopathological characteristics. In addition, we evaluated whether the expression of this proliferation marker was correlated with that of another marker, Ki-67, in gastric carcinoma.

METHODS

We examined the immunohistochemical expression of MCM2, Ki-67, and p53 in 103 surgically removed stage III gastric carcinomas, which consisted of 60 intestinal-type and 43 diffuse-type carcinomas. The labeling indices (LIs) of MCM2 and Ki-67 in cancer cells were compared with clinicopathological characteristics, p53 expression, and overall survival rates.

RESULTS

The mean MCM2 and Ki-67 LIs were 69.1 +/- 11.8% and 48.2 +/- 14.5%, respectively, in the intestinal carcinomas, and 43.7 +/- 9.9% and 24.9 +/- 11.0%, respectively, in the diffuse carcinomas. The LIs of these proteins revealed no significant association with clinicopathological characteristics or with p53 expression in the carcinomas. Kaplan-Meier survival curves showed that, in the patients with diffuse carcinoma, those with higher MCM2 LIs had a poorer prognosis (P < 0.05), but the MCM2 LI was not correlated with prognosis for those with intestinal carcinoma (P = 0.25). Ki-67 expression had no significant correlation with prognosis in either intestinal-type or diffuse-type carcinomas. Multivariate Cox regression analysis confirmed that MCM2 was an independent prognostic factor in patients with diffuse carcinoma.

CONCLUSION

Our data suggest that MCM2 is a useful prognostic marker in patients stage III diffuse-type gastric carcinoma.

MCM immunocytochemistry as a first line cervical screening test in developing countries: a prospective cohort study in a regional cancer centre in India

Cervical screening is not available for the majority of women in resource-poor countries. An important factor is a lack of skilled operators necessary for high-throughput assessment of the Papanicolaou (Pap) test currently in use. We compared the efficacy of immunocytochemistry for minichromosome maintenance (MCM) proteins vs standard Pap testing at detecting disease in 455 cervical smears processed in a typical Indian screening laboratory. Conventional (non-monolayer) smears were stained manually and then examined by a cytotechnologist and a cytopathologist. The MCM test was called positive when immunolabelled cells were identified as dyskaryotic by the Pap counterstain. The MCM test was read more quickly than the Pap test (approximately 2 vs 10 min) and there was 100% inter-observer agreement compared with 85% for Pap (P<0.0001). The MCM test detected 10 biopsy-proven cancers or pre-cancers that were not detected by Pap (P=0.002; P=0.016 excluding three cases where the Pap was deemed unsatisfactory on review). The cases in question included one recurrent squamous carcinoma and one adenocarcinoma in a screening patient who would have returned to 5 year recall. There were no false positive MCM test results. We propose that MCM immunocytochemistry has considerable advantages for cervical screening in developing countries like India.

FM-test: a fuzzy-set-theory-based approach to differential gene expression data analysis

Background

Microarray techniques have revolutionized genomic research by making it possible to monitor the expression of thousands of genes in parallel. As the amount of microarray data being produced is increasing at an exponential rate, there is a great demand for efficient and effective expression data analysis tools. Comparison of gene expression profiles of patients against those of normal counterpart people will enhance our understanding of a disease and identify leads for therapeutic intervention.

Results

In this paper, we propose an innovative approach, fuzzy membership test (FM-test), based on fuzzy set theory to identify disease associated genes from microarray gene expression profiles. A new concept of FM d-value is defined to quantify the divergence of two sets of values. We further analyze the asymptotic property of FM-test, and then establish the relationship between FM d-value and p-value. We applied FM-test to a diabetes expression dataset and a lung cancer expression dataset, respectively. Within the 10 significant genes identified in diabetes dataset, six of them have been confirmed to be associated with diabetes in the literature and one has been suggested by other researchers. Within the 10 significantly overexpressed genes identified in lung cancer data, most (eight) of them have been confirmed by the literatures which are related to the lung cancer.

Conclusion

Our experiments on synthetic datasets show that FM-test is effective and robust. The results in diabetes and lung cancer datasets validated the effectiveness of FM-test. FM-test is implemented as a Web-based application and is available for free at .

A minimally invasive immunocytochemical approach to early detection of oral squamous cell carcinoma and dysplasia

Squamous dysplasia of the oral cavity indicates increased risk of progression to squamous cell carcinoma (SCC). An important advance would be the development of a minimally invasive assay for identification of oral SCC and dysplasia. We have investigated the suitability in this context of immunostaining oral smears for minichromosome maintainance proteins (MCMs), sensitive and specific biomarkers of cell cycle entry. Immunohistochemical examination of 66 oral tissue samples showed a greater frequency of Mcm-2 expression in surface layers of moderate/severe dysplasia and SCC compared to benign keratosis/mild dysplasia. Immunocytochemistry for Mcm-2/Mcm-5 was performed on 101 oral smears. Conventional smears included 23 from normal mucosa, benign proliferative disease and mild dysplasia, all of which were MCM negative. Of 52 conventional smears of SCC tissue samples, 18 were inadequate. However, MCM-positive cells were present in 33/34 adequate samples. Of 26 liquid-based cytology smears, 19 out of 20 smears from SCC were adequate and all were MCM positive. Six smears from benign lesions were adequate and MCM negative. We conclude that MCMs are promising markers for early detection of oral SCC and dysplasia, particularly in a liquid-based cytology platform. Detection of MCMs would be amenable to automation and potentially applicable in the developing world. Further studies are now warranted.

Cell cycle phase distribution analysis in chronic lymphocytic leukaemia: a significant number of cells reside in early G1-phase

BACKGROUND AND AIMS

Chronic lymphocytic leukaemia (CLL) is a frequent non-Hodgkin lymphoma characterised by a heterogeneous clinical course. Assessment of cell cycle phase kinetics might be important for prediction of clinical behaviour and prognosis.

METHODS

Distribution of neoplastic cells in CLL within the cell cycle was evaluated by determining the labelling indices (LI, i.e. percentage of positive cells) of markers specific for late G1-phase (cyclin E), S-phase (cyclin A), and G2/M-phase (cyclin B1), and Mcm2, a novel marker of proliferative potential, in a large cohort of patients (n = 79) using tissue microarray (TMA) technology. Utilising a combination of these markers, an algorithm was developed--subtracting the combined LIs of cyclin E, cyclin A and cyclin B1 from the LI of Mcm2--to determine the percentage of tumour cells residing in early G1-phase, which is probably a critical state for the malignant potential of CLL.

RESULTS

27.11% of cells had acquired proliferative potential as indicated by expression of Mcm2. Only a small number of cells were found to be in late G1-phase (7.16%), S-phase (3.31%) or G2/M-phase (0.98%), while 15.66% of cells were considered to be in early G1-phase.

CONCLUSION

Cell cycle phase distribution can easily be assessed by immunohistochemistry in routinely processed paraffin-embedded specimens. A large number of neoplastic cells in CLL have proliferative potential, with a significant sub-population residing in early G1-phase. Estimates of these cells may identify cases likely to exhibit a more aggressive biological behaviour and adverse clinical course.

Immunohistochemical estimation of cell cycle phase in laryngeal neoplasia

We previously developed an immunohistochemical method for estimating cell cycle state and phase in tissue samples, including biopsies that are too small for flow cytometry. We have used our technique to examine whether primary abnormalities of the cell cycle exist in laryngeal neoplasia. Antibodies against the markers of cell cycle entry, minichromosome maintenance protein-2 (Mcm-2) and Ki67, and putative markers of cell cycle phase, cyclin D1 (G1-phase), cyclin A (S-phase), cyclin B1 (G2-phase) and phosphohistone H3 (Mitosis) were applied to paraffin-embedded sections of normal larynx (n=8), laryngeal dysplasia (n=10) and laryngeal squamous cell carcinoma (n=10). Cells expressing each marker were determined as a percentage of total cells, termed the labelling index (LI), and as a percentage of Mcm-2-positive cells, termed the labelling fraction (LF). The frequency of coexpression of each putative phase marker was investigated by confocal microscopy. There was a correlation between Mcm-2 and Ki67 LIs (ρ=0.93) but Mcm-2 LIs were consistently higher. All cells expressing a phase marker coexpressed Mcm-2, whereas Ki67 was not expressed in a proportion of these cells. The putative phase markers showed little coexpression. Labelling index values increased on progression from normal larynx through laryngeal dysplasia to squamous cell carcinoma for Mcm-2 (P=0.001), Ki67 (P=0.0002), cyclin D1 (P=0.015), cyclin A (P=0.0001) and cyclin B1 (P=0.0004). There was no evidence of an increase in the LF for any phase marker. Immunohistochemistry can be used to estimate cell cycle state and phase in laryngeal biopsies. Our data argues against primary cell cycle phase abnormalities in laryngeal neoplasia.

Prognostic value of p27Kip1 expression in Basaloid Squamous Cell Carcinoma of the larynx

Background

Very few reports have investigated the role of cell cycle regulators as biomarkers in Basaloid Squamous Cell Carcinoma (BSCC) of the larynx, a definite morphologic, uncommon, very aggressive variant of squamous cell carcinoma. Lower expression of Ki67/Mib-1, a proliferation marker highly expressed in the majority of tumours, and p53, a tumour suppressor protein that can induce an arrest of the G1-S transition, was related to a better prognosis in laryngeal BSCC. In the head and neck, p27^kip1, a member of the Cip1/Kip1 family of cyclin-dependent kinase inhibitors, has emerged as an independent prognostic factor, able to identify low-expressing tumours with unfavourable course. Up to date the role of this protein was never studied in BSCC. Aim of our study was to investigate the potential prognostic value of p27^kip1 levels and their correlation with Ki67/Mib-1 and p53 expression in BSCC of the larynx.

Methods

The retrospective study group consisted of 15 male and 1 female patients, affected by laryngeal BSCC, ranging in age from 44 to 69 years (mean 58). The tumour originated from the supraglottis in thirtheen cases and from the glottis in the remaining three. Ten patients had metastatic cervical lymph nodes at presentation and were classified as N+. Post surgical stage was IV in four patients, III in nine, II in two cases and I in the remaining one. Follow-up ranged from a minimum of 5 months up to 9 years. Paraffin-embedded tissue sections of each laryngeal tumour were analyzed for p27^kip, Ki67/Mib-1 and p53 expression by immunohistochemistry.

Results

The immunohistochemical study showed p27^kip1 expression in 40% of the patients with no evidence of disease (NED) and in none (0%) of the patients dead of disease (DOD), whilst p53 was expressed in 60% of patients in NED status and in 90% of patients in DOD status. Ki67/Mib-1 was positive in 80% of NED patients and in 100% of DOD patients. At multivariate analysis, performed by means of Discriminant analysis, low levels of p27^kip1 expression significantly correlated with poor prognosis (P < 0.05).

Conclusion

p27^kip1 protein has been shown to be a significant independent prognostic factor in laryngeal SCC. In our series of laryngeal BSCC the resulting data seem to confirm the clinical prognostic relevance of p27^kip1 low expression, which directly correlated with biological aggressiveness and consequent shortened survival.

Alteration of proliferation and apoptotic markers in normal and premalignant tissue associated with prostate cancer

Background

Molecular markers identifying alterations in proliferation and apoptotic pathways could be particularly important in characterizing high-risk normal or pre-neoplastic tissue. We evaluated the following markers: Ki67, Minichromosome Maintenance Protein-2 (Mcm-2), activated caspase-3 (a-casp3) and Bcl-2 to determine if they showed differential expression across progressive degrees of intraepithelial neoplasia and cancer in the prostate. To identify field effects, we also evaluated whether high-risk expression patterns in normal tissue were more common in prostates containing cancer compared to those without cancer (supernormal), and in histologically normal glands adjacent to a cancer focus as opposed to equivalent glands that were more distant.

Methods

The aforementioned markers were studied in 13 radical prostatectomy (RP) and 6 cystoprostatectomy (CP) specimens. Tissue compartments representing normal, low grade prostatic intraepithelial neoplasia (LGPIN), high grade prostatic intraepithelial neoplasia (HGPIN), as well as different grades of cancer were mapped on H&E slides and adjacent sections were analyzed using immunohistochemistry. Normal glands within 1 mm distance of a tumor focus and glands beyond 5 mm were considered "near" and "far", respectively. Randomly selected nuclei and 40 × fields were scored by a single observer; basal and luminal epithelial layers were scored separately.

Results

Both Ki-67 and Mcm-2 showed an upward trend from normal tissue through HGPIN and cancer with a shift in proliferation from basal to luminal compartment. Activated caspase-3 showed a significant decrease in HGPIN and cancer compartments. Supernormal glands had significantly lower proliferation indices and higher a-casp3 expression compared to normal glands. "Near" normal glands had higher Mcm-2 indices compared to "far" glands; however, they also had higher a-casp3 expression. Bcl-2, which varied minimally in normal tissue, did not show any trend across compartments or evidence for field effects.

Conclusion

These results demonstrate that proliferation and apoptosis are altered not only in preneoplastic lesions but also in apparently normal looking epithelium associated with cancer. Luminal cell expression of Mcm-2 appears to be particularly promising as a marker of high-risk normal epithelium. The role of apoptotic markers such as activated caspase-3 is more complex, and might depend on the proliferation status of the tissue in question.

Common markers of proliferation

When normal tissue and tumour samples are compared by microarray analysis, the biggest differences most often occur in the expression levels of genes that control cell proliferation. However, this difference is detected whenever mRNA samples that are taken from two cell populations with different proliferation rates are compared. Although the exact genes that comprise this 'proliferation signature' often differ, they are almost always genes that are involved in the fundamental process of cell proliferation. Can the proliferation signature be used to improve our understanding of the cell cycle and cancer pathogenesis, as well as being used as a biomarker for cancer diagnosis and prognosis?