Expression of cell cycle-regulated proteins pRB2/p130, p107, E2F4, p27, and pCNA in salivary gland tumors: prognostic and diagnostic implications

Role of E2F transcription factor in Oral cancer: Recent Insight and Advancements

The family of mammalian E2F transcription factors (E2Fs) comprise of 8 members (E2F1-E2F8) classified as activators (E2F1-E2F3) and repressors (E2F4-E2F8) primarily regulating the expression of several genes related to cell proliferation, apoptosis and differentiation, mainly in a cell cycle-dependent manner. E2F activity is frequently controlled via the retinoblastoma protein (pRb), cyclins, p53 and the ubiquitin-proteasome pathway. Additionally, genetic or epigenetic changes result in the deregulation of E2F family genes expression altering S phase entry and apoptosis, an important hallmark for the onset and development of cancer. Although studies reveal E2Fs to be involved in several human malignancies, the mechanisms underlying the role of E2Fs in oral cancer lies nascent and needs further investigations. This review focuses on the role of E2Fs in oral cancer and the etiological factors regulating E2Fs activity, which in turn transcriptionally control the expression of their target genes, thus contributing to cell proliferation, metastasis, and drug/therapy resistance. Further, we will discuss therapeutic strategies for E2Fs, which may prevent oral tumor growth, metastasis, and drug resistance.

Immunohistochemical analysis of proliferating cell nuclear antigen and minichromosome maintenance complex component 7 in benign and malignant salivary gland tumors

Background:

Proliferation markers have been used to determine the behavior and prognosis of benign and malignant tumors; this study was aimed to compare the immunohistochemical (IHC) expression of proliferating cell nuclear antigen (PCNA) and novel marker minichromosome maintenance complex component 7 (MCM7) in common salivary gland tumors including pleomorphic adenoma (PA), mucoepidermoid carcinoma (MEC), and adenoid cystic carcinoma (AdCC), to find a possible significant correlation between benign and malignant tumors.

Materials and Methods:

In this cross-sectional study, a total of 90 cases, including 30 PAs, 30 MECs, and 30 AdCCs, were collected. The IHC expressions of PCNA and MCM7 were evaluated. Their expressions were compared with each other and between benign and malignant tumors. Statistical analysis was performed by Chi-square and Tukey's test. P value was considered 0.05.

Results:

Out of 30 cases of PA, 28 cases (93.3%) were PCNA positive and 28 cases (93.3%) were MCM7 positive. In the AdCC cases, 29 cases (96.6%) were PCNA positive and 29 cases (96.6%) were MCM7 positive. In the MEC cases, all cases (100%) were PCNA positive and 23 cases (76.6%) were MCM7 positive. The labeling index (LI) of MCM7 and PCNA was evaluated, and this index was lower in MCM7 LI than PCNA in all tumors. The MCM7 and PCNA expression showed a significant difference in PA and MEC (P < 0.001).

Conclusion:

PCNA expression was higher than MCM7 expression in salivary gland tumors. However, more studies are needed to evaluate the malignant activity of these tumors with group of markers such as MCM family members.

Analysis of Differentially Expressed Long Non-coding RNAs and the Associated TF-mRNA Network in Tongue Squamous Cell Carcinoma

Accumulating evidence indicates that long non-coding RNAs (lncRNAs) play crucial roles in tongue squamous cell carcinoma (TSCC) tumorigenesis. However, the comprehensive regulation of lncRNAs-transcription factors (TFs)-messenger RNAs (mRNAs) in TSCC remains largely unknown. The purpose of this study was to identify aberrantly expressed lncRNAs and the associated TF-mRNA network in TSCC. To explore lncRNA and mRNA expression profiles and their biological functions in TSCC, we surveyed the lncRNA and mRNA expression profiles of TSCC and adjacent tissues using next-generation RNA sequencing in six patients. Thousands of significantly differentially expressed lncRNAs (DELs) and mRNAs (DEGs) were identified. Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway enrichment analyses were performed to demonstrate the principal functions of the significantly dysregulated lncRNAs and genes. A total of 40 DELs were screened between TSCC and adjacent non-cancerous tissues. Results obtained from GEPIA and StarBase confirmed the expression levels of nine pivotal DELs obtained in our study. Three of the nine deregulated DELs were identified to have a significant impact on the overall survival of TSCC patients, which were evaluated with GEPIA and StarBase. LncMAP was used to predict the lncRNA-TF-mRNA triplets in TSCC. Furthermore, based on these results, we established lncRNA-TF-mRNA coexpression networks for the up- and downregulated lncRNAs using Cytoscape. We also found that among the nine pivotal lncRNAs, there is limited research on the abnormally expressed lncRNAs, including RP11-54H7.4, CTD-2545M3.8, RP11-760H22.2, RP4-791M13.3, and LINC01405, in TSCC pathogenesis. This is the first study to show that RP11-54H7.4, LINC00152, and LINC01405 can be acted as a prognostic target for TSCC. Our findings provide a novel perspective and lay the foundation for future research on the potential roles of lncRNAs, TFs, and mRNAs in TSCC. Verification of the potential lncRNA-TF-mRNA regulatory networks will provide a more comprehensive understanding of the pathogenesis of TSCC.

An evidence-based analysis of the management of N0 neck in patients with cancer of the parotid gland

Introduction: Management of clinically negative neck (cN0) in patients with parotid gland cancer is controversial. Treatment options can include observation, elective neck dissection or elective radiotherapy. Areas covered: We addressed the treatment options for cN0 patients with parotid gland cancer. A literature review was undertaken to determine the optimal management of this group of patients. Expert opinion: Patients with parotid carcinoma and clinically negative neck have various options for their management. The analysis of tumor stage, histology and grade is essential to better define patients at risk for occult lymph node metastasis. These patients can be managed by surgery, radiotherapy or their combination, depending on the presence of risk factors, the moment at which such risk factors are detected, patient-related clinical conditions, medical provider expertise and institutional facilities.

XPO1 inhibition by selinexor induces potent cytotoxicity against high grade bladder malignancies

Treatment options for high grade urothelial cancers are limited and have remained largely unchanged for several decades. Selinexor (KPT-330), a first in class small molecule that inhibits the nuclear export protein XPO1, has shown efficacy as a single agent treatment for numerous different malignancies, but its efficacy in limiting bladder malignancies has not been tested. In this study we assessed selinexor-dependent cytotoxicity in several bladder tumor cells and report that selinexor effectively reduced XPO1 expression and limited cell viability in a dose dependent manner. The decrease in cell viability was due to an induction of apoptosis and cell cycle arrest. These results were recapitulated in in vivo studies where selinexor decreased tumor growth. Tumors treated with selinexor expressed lower levels of XPO1, cyclin A, cyclin B, and CDK2 and increased levels of RB and CDK inhibitor p27, a result that is consistent with growth arrest. Cells expressing wildtype RB, a potent tumor suppressor that promotes growth arrest and apoptosis, were most susceptible to selinexor. Cell fractionation and immunofluorescence studies showed that selinexor treatment increased nuclear RB levels and mechanistic studies revealed that RB ablation curtailed the response to the drug. Conversely, limiting CDK4/6 dependent RB phosphorylation by palbociclib was additive with selinexor in reducing bladder tumor cell viability, confirming that RB activity has a role in the response to XPO1 inhibition. These results provide a rationale for XPO1 inhibition as a novel strategy for the treatment of bladder malignancies.

MAPK/AP-1 pathway regulates benzidine-induced cell proliferation through the control of cell cycle in human normal bladder epithelial cells

Bladder cancer is the most common malignancy of the urinary tract. Long-term exposure to benzidine is one of the major causes of bladder cancer. However, the mechanism of benzidine-induced bladder cancer is not yet sufficiently characterized. Dysregulated cell proliferation serves a critical role in cancer initiation and development; whether benzidine promotes cell proliferation, and the role of MAPKs in this process, have not previously been investigated. The present study aimed to investigate the benzidine-induced modulation of intracellular mitogen-activated protein kinases (MAPKs) and activator protein-1 (AP-1) signaling cascades on cell proliferation in SV-40 immortalized human uroepithelial cells (SV-HUC-1). It was identified that benzidine exposure enhanced the proliferation of SV-HUC-1 cells, promoted the transition of cells from G1 to S phase and altered the expression level of cell cycle-associated genes at the mRNA and protein levels. Furthermore, exposure of the SV-HUC-1 cells to benzidine was associated with the activation of MAPKs, including extracellular regulated protein kinases 1 and 2, p38 and Jun N-terminal kinase. The downstream target of MAPKs, AP-1 monomers, was also activated. Benzidine-induced proliferation was reversed by MAPK-specific inhibitors. Thus, the present study demonstrated that benzidine enhances the proliferation of bladder cells via activating the MAPK/AP-1 pathway, which may provide novel insights into the molecular mechanisms of benzidine-initiated bladder tumorigenesis, as well as cancer prevention.

Identification of genes and pathways in nasopharyngeal carcinoma by bioinformatics analysis

Nasopharyngeal carcinoma is a metastatic malignant tumor originating from nasopharyngeal epithelium. Lacking or nonspecific symptoms of patients with early stage nasopharyngeal carcinoma have significantly reduced the accuracy of diagnosing and predicting nasopharyngeal carcinoma development. This study aimed to identify gene signatures of nasopharyngeal carcinoma and uncover potential mechanisms. Two gene expression profiles (GSE12452 and GSE13597) containing 56 nasopharyngeal carcinoma samples and 13 normal control samples were analyzed to identify the differentially expressed genes. In total, 179 up-regulated genes and 238 down-regulated genes were identified. Functional and pathway enrichment analysis showed that up-regulated genes were significantly involved in cell cycle, oocyte meiosis, DNA replication and p53 signaling pathway, while down-regulated genes were enriched in Huntington's disease,metabolic pathways. Subsequently, the top 10 hub genes, TOP2A (topoisomerase (DNA) II alpha), CDK1 (cyclin-dependent kinase 1), CCNB1 (cyclin B1), PCNA (proliferating cell nuclear antigen), MAD2L1 (mitotic arrest deficient 2 like 1), BUB1 (budding uninhibited by benzimidazoles 1 homolog), CCNB2 (cyclin B2), AURKA (aurora kinase A), CCNA2 (cyclin A2), CDC6 (cell division cycle 6 homolog), were identified from protein-protein interaction network. Furthermore, Module analysis revealed that the ten hub genes except TOP2A were belonged to module 1, indicating the upregulation of these hub genes associated molecular pathways in nasopharyngeal carcinoma might activate nasopharyngeal carcinoma pathogenesis. In conclusion, this study indicated that the identified differentially expressed genes and hub genes enrich our understanding of the molecular mechanisms of nasopharyngeal carcinoma, which could eventually translate into additional biomarkers to facilitate the early diagnosis and therapeutic approaches.

Inhibition of Rb Phosphorylation Leads to mTORC2-Mediated Activation of Akt

The retinoblastoma (Rb) protein exerts its tumor suppressor function primarily by inhibiting the E2F family of transcription factors that govern cell-cycle progression. However, it remains largely elusive whether the hyper-phosphorylated, non-E2F1-interacting form of Rb has any physiological role. Here we report that hyper-phosphorylated Rb directly binds to and suppresses the function of mTORC2 but not mTORC1. Mechanistically, Rb, but not p107 or p130, interacts with Sin1 and blocks the access of Akt to mTORC2, leading to attenuated Akt activation and increased sensitivity to chemotherapeutic drugs. As such, inhibition of Rb phosphorylation by depleting cyclin D or using CDK4/6 inhibitors releases Rb-mediated mTORC2 suppression. This, in turn, leads to elevated Akt activation to confer resistance to chemotherapeutic drugs in Rb-proficient cells, which can be attenuated with Akt inhibitors. Therefore, our work provides a molecular basis for the synergistic usage of CDK4/6 and Akt inhibitors in treating Rb-proficient cancer.

RB1 dual role in proliferation and apoptosis: cell fate control and implications for cancer therapy

Inactivation of the retinoblastoma (RB1) tumor suppressor is one of the most frequent and early recognized molecular hallmarks of cancer. RB1, although mainly studied for its role in the regulation of cell cycle, emerged as a key regulator of many biological processes. Among these, RB1 has been implicated in the regulation of apoptosis, the alteration of which underlies both cancer development and resistance to therapy. RB1 role in apoptosis, however, is still controversial because, depending on the context, the apoptotic cues, and its own status, RB1 can act either by inhibiting or promoting apoptosis. Moreover, the mechanisms whereby RB1 controls both proliferation and apoptosis in a coordinated manner are only now beginning to be unraveled. Here, by reviewing the main studies assessing the effect of RB1 status and modulation on these processes, we provide an overview of the possible underlying molecular mechanisms whereby RB1, and its family members, dictate cell fate in various contexts. We also describe the current antitumoral strategies aimed at the use of RB1 as predictive, prognostic and therapeutic target in cancer. A thorough understanding of RB1 function in controlling cell fate determination is crucial for a successful translation of RB1 status assessment in the clinical setting.

pRb2/p130 localizes to the cytoplasm in diffuse gastric cancer

pRb2/p130 is a key tumor suppressor, whose oncosuppressive activity has mainly been attributed to its ability to negatively regulate cell cycle by interacting with the E2F4 and E2F5 transcription factors. Indeed, pRb2/p130 has been found altered in various cancer types in which it functions as a valuable prognostic marker. Here, we analyzed pRb2/p130 expression in gastric cancer tissue samples of diffuse histotype, in comparison with their normal counterparts. We found a cytoplasmic localization of pRb2/p130 in cancer tissue samples, whereas, in normal counterparts, we observed the expected nuclear localization. pRb2/p130 cytoplasmic delocalization can lead to cell cycle deregulation, but considering the emerging involvement of pRb2/p130 in other key cellular processes, it could contribute to gastric tumorigenesis also through other mechanisms. Our data support the necessity of further investigations to verify the possibility of using pRb2/p130 as a biomarker or potential therapeutic target for diffuse gastric cancer.

Correlation of EGFR, pEGFR and p16INK4 expressions and high risk HPV infection in HIV/AIDS-related squamous cell carcinoma of conjunctiva

Background

Squamous cell carcinoma of conjunctiva has increased tenfold in the era of HIV/AIDS. The disease pattern has also changed in Africa, affecting young persons, with peak age-specific incidence of 30-39 years, similar to that of Kaposi sarcoma, a well known HIV/AIDS defining neoplasm. In addition, the disease has assumed more aggressive clinical course. The contributing role of exposure to high risk HPV in the development of SCCC is still emerging.

Objective

The present study aimed to investigate if immunohistochemical expressions of EGFR, pEGFR and p16, could predict infection with high risk HPV in HIV-related SCCC.

Methods

FFPE tissue blocks of fifty-eight cases diagnosed on hematoxylin and eosin with SCCC between 2005-2011, and subsequently confirmed from medical records to be HIV positive at the department of human pathology, UoN/KNH, were used for the study. Immunohistochemistry was performed to assess the expressions of p16INK4A, EGFR and pEGFR. This was followed with semi-nested PCR based detection and sequencing of HPV genotypes. The sequences were compared with the GenBank database, and data analyzed for significant statistical correlations using SPSS 16.0. Ethical approval to conduct the study was obtained from KNH-ERC.

Results

Out of the fifty-eight cases of SCCC analyzed, twenty-nine (50%) had well differentiated (grade 1), twenty one (36.2%) moderately differentiated (grade 2) while eight (13.8%) had poorly differentiated (grade 3) tumours. Immunohistochemistry assay was done in all the fifty eight studied cases, of which thirty nine cases (67.2%) were positive for p16INK4A staining, forty eight cases (82.8%) for EGFR and fifty one cases (87.9%) showed positivity for p-EGFR. HPV DNA was detected in 4 out of 40 SCCC cases (10%) in which PCR was performed, with HPV16 being the only HPV sub-type detected. Significant statistical association was found between HPV detection and p16INK4 (p=0.000, at 99% C.I) and EGFR (p=0.028, at 95% C.I) expressions, but not pEGFR. In addition, the expressions of these biomarkers did not show any significant association with tumor grades.

Conclusion

This study points to an association of high risk HPV with over expressions of p16INK4A and EGFR proteins in AIDS-associated SCCC.

Correlation of β-catenin, but not PIN1 and cyclin D1, overexpression with disease-free and overall survival in patients with cancer of the parotid gland

BACKGROUND

Malignant tumors of the salivary glands comprise about 3% to 5% of all head and neck carcinomas. The purpose of our study was to find possible predictive and/or prognostic markers for parotid cancer.

METHODS

A total of 46 tissue samples of carcinomas of the parotid gland were immunohistochemically stained for ß-catenin, cyclin D1, and PIN1. The factors were analyzed regarding their prognostic value for disease-free and overall survival.

RESULTS

An overexpression of the cytoplasmatic ß-catenin was linked to a statistically significant worse outcome regarding disease-free (p = .0296) and overall survival (p = .0416). The 5-year overall survival was 83.9% in patients without and 0% in patients presenting with overexpression of cytoplasmatic ß-catenin. Additionally, Union Internationale Contre le Cancer (UICC) stage correlated with overall survival (p = .0306) and disease-free survival (DFS; p = .0473).

CONCLUSION

Multivariate analysis showed that overexpression of cytoplasmatic ß-catenin and the UICC stage are 2 independent prognostic markers for survival in patients with parotid cancer.

The importance of oncogenic transcription factors for oral cancer pathogenesis and treatment

Oral squamous cell carcinoma is a major cause of morbidity and mortality worldwide. Current experimental evidence shows that most important risk factors for oral cancer include tobacco use and excessive alcohol consumption and less well-defined risks include viral infection and a diet deficient in antioxidants. The positive correlation between various risk/etiologic factors of oral cancer and the activation of various transcription factors (TFs) has been reported in the literature. Although initially, TFs were considered to be very difficult targets for use in clinical treatment, recent technological advances have provided the ability to control these factors of cancer progression. This review focuses on the role of oncogenic transcription factors in oral cancer, their modes of activation through various biological pathways, the promises and pitfalls in viewing them as potent oncotargets, the way they can be controlled based on the current understanding, and the future research to be done in this area.

Takahashi R, Nagai T, Yoshida M, Suzuki F, Obikane H, Yamashina M, Matsubayashi J. Immunohistochemical analysis of salivary gland tumors: application for surgical pathology practice

Salivary gland tumors are relatively uncommon and there exists a considerable diagnostic difficulty owing to their diverse histological features in individual lesions and the presence of a number of types and variants, in addition to overlapping histological patterns similar to those observed in different tumor entities. The classification is complex, but is closely relevant to the prognostic and therapeutic aspects. Although hematoxylin-eosin staining is still the gold standard method used for the diagnosis, immunohistochemistry (IHC) can enhance the accuracy and be a helpful tool when in cases to investigate the subjects that cannot be assessed by histological examination, such as the cell nature and differentiation status, cell proliferation, and tumor protein expression. This review depicts on the practical diagnostic utility of IHC in salivary gland tumor pathology under the following issues: assessment of cell differentiation, focusing on neoplastic myoepithelial cells; discrimination of histologically mimic tumor groups; diagnosis of specific tumor types, e.g., pleomorphic adenoma, adenoid cystic carcinoma, and salivary duct carcinoma; and evaluation of malignancy and prognostic factors. IHC plays a limited, even though important, role in the diagnosis of salivary gland tumors, but is often useful to support the histological assessment. However, unfortunately few tumor type-specific markers are still currently available. For these reasons, IHC should be considered a method that can be used to assist the final diagnosis, and its results themselves do not directly indicate a definitive diagnosis.

PP2A interaction with Rb2/p130 mediates translocation of Rb2/p130 into the nucleus in all-trans retinoic acid-treated ovarian carcinoma cells

One of the mechanisms by which all-trans retinoic acid (ATRA) has been shown to suppress the growth of CAOV3 ovarian carcinoma cells involves an increase in the accumulation of Rb2/p130 protein, a member of the retinoblastoma family of tumor suppressors. This increase in accumulation of RB2/p130 by ATRA results from increased stability of Rb2/p130 protein as a result of an increase in dephosphorylation of the protein by the serine/threonine phosphatase PP2A. We show that upon ATRA treatment, PP2A interacts with the Rb2/p130 C-terminus and specifically dephosphorylates two residues (S1080 and T1097) adjacent to NLS1 and NLS2 of Rb2/p130. Moreover, co-immunoprecipitation studies reveal that Rb2/p130 can form a complex with the nuclear transport proteins, importin α and importin β, binding to the same dephosphorylated NLS1 and NLS2 sites. Finally, mutation of S1080 and T1097 results in retension of Rb2/p130 in the cytoplasm. Our studies suggest that one mechanism by which ATRA treatment of CAOV3 cells induces G0/G1 arrest involves the recruitment of PP2A to the C-terminus of Rb2/p130, resulting in the dephosphorylation of the S1080 and T1097 adjacent to the NLS and the subsequent interaction of Rb2/p130 with importins leading to transport of the Rb2/p130 to the nucleus where it inhibits cell-cycle progression.

Clinical significance of P27 and PCNA expression in hilar cholangiocarcinoma

AIM: To analyze the clinical significance of P27 and proliferating cell nuclear antigen (PCNA) expression in hilar cholangiocarcinoma.

METHODS: The expression of P27 and PCNA was detected by immunohistochemistry in 44 hilar cholangiocarcinoma specimens and 8 normal bile duct tissue specimens.

RESULTS: The positive rates of P27 and PCNA expression in hilar cholangiocarcinoma were 77.2% and 100%, respectively. P27 expression had a significant correlation with histological grade, lymph node metastasis and perineural invasion. PCNA expression was associated with histological grade, lymph node metastasis and vascular invasion. The survival of patients with low or absent P27 expression was significantly lower than that of patients with high P27 expression. PCNA expression in grade III and IV cancer was associated with poor survival when compared with that in grade II cancer.

CONCLUSION: P27 and PCNA expression is associated with the development and progression of hilar cholangiocarcinoma and can be used as prognostic markers for the disease.

pRb2/p130 protein expression and RBL2 mutation analysis in Burkitt lymphoma from Uganda

Background

The members of the retinoblastoma protein family, pRb, p107 and pRb2 (p130), are central players in controlling the cell cycle. Whereas disturbed function of pRb is commonly seen in human cancers, it is still an open question whether pRb2 is involved in tumorigenic processes. However, altered subcellular localization of pRb2 and mutations in the pRb2-encoding gene RBL2 have been described for some tumours, including Burkitt lymphomas (BL).

Methods

We retrieved 51 biopsy specimens of endemic BL cases from Uganda. The expression of pRb2 was determined by immunohistochemistry. Exons 19-22 of the RBL2 gene, the region known to contain a nuclear localization signal, were screened for mutations by PCR amplification and direct DNA sequencing.

Results

Nearly all of our cases (84.0%) were positive for pRb2 protein expression although this protein is a marker for growth arrest and Burkitt lymphoma is characterized by a high proliferation rate. Of the positive cases, 73.8% were scored as expressing the protein at a high level. Subcellular pRb2 localization was predominantly nuclear and no cases with expression restricted to the cytoplasm were observed. We did not detect any RBL2 mutations in the part of the gene that encodes the C-terminal end of the protein.

Conclusion

The majority of endemic BL cases from Uganda express pRb2, but somatic RBL2 mutations affecting the protein's nuclear localization signal appear to be rare.

The expression of novel gene URG4 in osteosarcoma: correlation with patients' prognosis

AIMS

Up-regulated gene 4 (URG4) is a novel gene that may be associated with the onset of tumorigenesis and cell cycle regulation. The present study examined for the first time the expression of URG4 in osteosarcoma, which is one of the most rapidly growing sarcomas, and investigated its prognostic value in both disease-free and overall survival of the patients.

METHODS

The expression of URG4 in osteosarcoma tissues was examined by immunohistochemistry in 46 patients who underwent surgical operation for osteosarcoma; the correlation of URG4 with proliferating cell nuclear antigen index (PCNA) and microvessel count (MVC) was analysed, and the prognostic value of URG4 in patients was investigated.

RESULTS

URG4 was highly expressed in 40 of 46 (86.96%) osteosarcoma specimens with cytoplasmic staining, and also increased in the specimens with recurrence (p < 0.05) and metastasis (p < 0.05). The mean disease-free survival and overall survival were 50.25 and 54.08 months for patients with over-expressed URG4, compared with 69.54 and 70.01 months for those with low expression. URG4 was also found to be highly related with PCNA, while no significant relationship was found between URG4 and MVC.

CONCLUSIONS

URG4 may play important roles in the development of osteosarcoma, and might be a useful molecular marker for predicting the prognosis of osteosarcoma.

Importance of Ezh2 polycomb protein in tumorigenesis process interfering with the pathway of growth suppressive key elements

An understanding of the mechanisms that uncover the dynamic changes in the distribution of the chromatin modifying enzymes and regulatory proteins on their target loci could provide further insight into the phenomenon of malignant transformation. Based on the current available data, it seems more and more clear that an abnormal expression of Ezh2, a member of the Polycomb group (PcG) protein, may be involved in the tumorigenesis process, in addition, different studies identify Ezh2 as a potential marker that distinguish aggressive prostate and breast cancer from indolent one. Recent investigation show that ectopic expression of Ezh2 provides proliferative advantage to primary cells through interaction with the pathways of key elements that control cell growth arrest and differentiation, like members of the retinoblastoma (Rb) family. Here, we outline how these pathways converge and we review the recent advances on the molecular mechanisms that promote cell cycle progression through deregulation of Ezh2 protein level, providing novel links between cancer progression and chromatin remodeling machineries.

Increased severity of alcoholic liver injury in female verses male rats: a microarray analysis

Alcoholic liver disease (ALD) is an increasingly recognized condition that may progress to end-stage liver disease. In addition to alcohol consumption, genetic factors, dietary fatty acids, gender and viral infection potentiate the severity of alcoholic liver injury. In humans, significant gender differences in susceptibility to ALD are observed. In the intragastric infusion rat model of ALD, female rats developed more severe liver injury than males. To understand the effect of gender on the development of more severe ALD in female rats, we performed a microarray based expression profiling of genes in rats fed with fish oil and ethanol diet. A large number of genes showed significant changes in female livers compared to males. The upregulated genes in female liver were involved in proteosome endopeptidase activity, catalytic activity, lipid metabolism, alcohol metabolism, mitochondrial and oxidoreductase activity. The downregulated genes were involved in oxidoreductase activity, chaperone activity, and electron transport activity in the female liver as demonstrated by biological theme analysis. Ingenuity computational pathway analysis tools were used to identify specific regulatory networks of genes operative in promoting liver injury. These networks allowed us to identify a large cluster of genes involved in lipid metabolism, development, cellular growth and proliferation, apoptosis, carcinogenesis and various signaling pathways. Genes listed in this article that were significantly increased or decreased (expression two fold or more) were assigned to pathological functional groups and reviewed for relevance to establish hypotheses of potential mechanisms involved in ALD in female liver injury.

Novel p53/p130 Axis in Bladder Tumors

OBJECTIVES

To identify the relationships between key components of the proliferative and apoptotic pathways in bladder tumors.

METHODS

A tissue array of 88 bladder tumors was assembled. Immunohistochemical analyses were used to investigate the relationship between nine different parameters: stage, proliferation (Ki67), apoptosis (in situ DNA nick end labeling), the anti-apoptotic protein Bcl-2, tumor suppressors p53 and retinoblastoma protein (Rb), the Rb-related protein p130, cyclin E, and the cyclin-dependent kinase inhibitor p27. The protein expression in each tumor was reported as the percentage of positively staining cells.

RESULTS

The analysis focused on Stage 1 to 3 tumors. Analysis found that p53 expression increased progressively with stage, and Rb and p27 decreased with increasing stage. Overall, the cyclin E levels correlated with the proliferative index. Cyclin E levels were low in Stage 1 tumors and elevated in Stage 2 tumors, but were decreased in Stage 3 tumors. Multivariate analysis uncovered a correlation between cyclin E and proliferation (Ki67) and a weak correlation between p53 and Bcl-2 and between p27 and Rb. A strong correlation was found between the expression of p53 and p130, which was apparent in Stages 1 and 3, but not in Stage 2. Furthermore, high levels of p130 protein were detected primarily in the cytoplasm.

CONCLUSIONS

These results suggest a novel p53/p130 axis in bladder tumors.

Enhanced cell survival of gastric cancer cells by a novel gene URG4

Upregulated gene 4 (URG4), a novel gene located on 7 chromosome (7p13), was found to contribute to hepatocarcinogenesis. However, the role of URG4 in the gastric carcinogenesis still remains unclear. In the present study, URG4 was found by immunohistochemistry to be upregulated in human gastric cancer tissues compared with matched adjacent nonneoplastic tissues. The proliferating cell nuclear antigen index is higher in gastric cancer tissues with high URG4 expression than in those with low URG4 expression. The growth of GES-1 cells, which are immortalized human gastric epithelial mucosa cells with baseline URG4 expression, was accelerated by URG4 induction. Downregulation of URG4 through URG4 small interfering RNA (siRNA) in SGC7901 and MKN28 cells, which had high endogenous URG4 expression, suppressed cell proliferation in both of these cells. URG4-siRNA also inhibited the proliferation of SGC7901 and MKN28 cells in soft agar and tumor formation in nude mice. Overexpression of URG4 in GES cells upregulated cyclin D1, whereas repression of URG4 in SGC7901 and MKN28 cells downregulated cyclin D1. The data suggested that URG4 played an important role in the development of human gastric cancer by regulating the expression of cyclin D1 and might be used as a potential therapeutic target for gastric cancer.

Basal cell adenocarcinoma of the oral minor salivary glands: review of the literature and presentation of two cases

Basal cell adenocarcinoma (BCA) is an unusual salivary gland malignancy that very rarely affects the minor glands. Here we present 2 cases of BCA arising in the minor salivary glands of the left cheek and junction of the hard and soft palate, respectively. The patients were both women aged 66 and 42 years. The tumors assumed a tubular-trabecular and a solid-membranous pattern, respectively. Both tumors showed immunopositivity for S-100, Bcl-2, and cytokeratin 7. One tumor was also immunopositive for epithelial membrane antigen and carcinoembryonic antigen, and the other tumor was reactive with p53 and vimentin. Both tumors were surgically removed. A comprehensive literature review revealed only 21 previously reported cases of BCA of oral minor salivary glands. This is an exceptionally rare salivary gland tumor, which, despite its low-grade behavior, demands complete surgical removal with adequate margins. Immunohistochemical studies may complement a thorough histopathologic analysis in discriminating BCA from other salivary gland tumors.

RB family members as predictive and prognostic factors in human cancer

The retinoblastoma family members--pRb, pRb2/p130 and p107--are tumor suppressor genes involved in controlling four major cellular processes: growth arrest, apoptosis, differentiation and angiogenesis. Molecular genetic studies have identified abnormalities of these tumor suppressor genes in a large proportion of human cancers. These genetic alterations have emerged as significant factors in the pathogenesis and progression of many types of tumors and are therefore likely to provide relevant information to assess risk in cancer patients. There is a pressing clinical need to identify prognostic and predictive factors for patients with cancer, because there is an undeniable importance in being able to determine which patients will have a favorable outcome without further therapy (prognostic factor) and which will need some additional treatment (predictive factor). This review examines the predictive and/or prognostic role of each retinoblastoma family member in human cancer.