Expression of Bmi-1 is a prognostic marker in bladder cancer

Correlations between C-myc expression, BMI-1 expression, and vaginal microecology with HPV-DNA load in patients with different cervical lesions

OBJECTIVE

To investigate the correlations between the expressions of proto-oncogenes C-myc and B-cell-specific Moloney leukemia virus integration site-1 (BMI-1), vaginal microecology, and human papillomavirus-DNA (HPV-DNA) load in patients with different cervical lesions.

METHODS

A total of 51 patients with cervix squamous cell carcinoma (CSCC), 72 patients with cervical intraepithelial neoplasia (CIN) and 50 patients with normal cervix (NC) who were diagnosed or admitted between Jan. 1st 2020 and Dec. 31st 2022 at the Suzhou Hospital of Integrated Traditional Chinese and Western Medicine were selected and divided into three groups, i.e., the CSCC group, the CIN group and the NC group, for a retrospective analysis. Hybrid capture 2 (hc2) was used to detect the HPV-DNA load in each group. Immunohistochemistry was performed to detect C-myc and BMI-1 expressions in each group. The indicators of vaginal microecology in patients were compared among groups to analyze the correlations between C-myc, BMI-1 expressions, vaginal microecology and HPV-DNA load.

RESULTS

The HPV-DNA load and expression levels of positive C-myc and BMI-1 in the CSCC group were all higher than those of the CIN and NC groups (P<0.05). The detection rate of lactobacillus in the CSCC group was lower than that of the CIN and NC groups. The percentages of leukocyte esterase (LE) positivity and pH ≥4.6 were higher in the CSCC group than those in the CIN and NC groups (P<0.05). The difference in the detection rate of spores among the three groups was not significant (P>0.05). Both C-myc and BMI-1 scores were positively correlated with HPV-DNA load in the 173 samples.

CONCLUSION

The proto-oncogenes C-myc and BMI-1 were highly expressed in the cervical tissues of CIN and CSCC patients, whose vaginal microecology was also altered. Both may play an important role in the progression of cervical lesions.

Role of O-GlcNAcylation on cancer stem cells: Connecting nutrient sensing to cell plasticity

Tumor growth and metastasis can be promoted by a small sub-population of cancer cells, termed cancer stem-like cells (CSCs). While CSCs possess capability in self-renewing and differentiating, the hierarchy of CSCs during tumor growth is highly plastic. This plasticity in CSCs fate and function can be regulated by signals from the tumor microenvironment. One emerging pathway in CSCs that connects the alteration in microenvironment and signaling network in cancer cells is the hexosamine biosynthetic pathway (HBP). The final product of HBP, UDP-N-acetylglucosamine (UDP-GlcNAc), is utilized for glycosylating of membrane and secreted proteins, but also nuclear and cytoplasmic proteins by the post-translational modification O-GlcNAcylation. O-GlcNAcylation and its enzyme, O-GlcNAc transferase (OGT), are upregulated in nearly all cancers and been linked to regulate many cancer cell phenotypes. Recent studies have begun to connect OGT and O-GlcNAcylation to regulation of CSCs. In this review, we will discuss the emerging role of OGT and O-GlcNAcylation in regulating fate and plasticity of CSCs, as well as the potential in targeting OGT/O-GlcNAcylation in CSCs.

The Crucial Roles of Bmi-1 in Cancer: Implications in Pathogenesis, Metastasis, Drug Resistance, and Targeted Therapies

B-cell-specific Moloney murine leukemia virus integration region 1 (Bmi-1, also known as RNF51 or PCGF4) is one of the important members of the PcG gene family, and is involved in regulating cell proliferation, differentiation and senescence, and maintaining the self-renewal of stem cells. Many studies in recent years have emphasized the role of Bmi-1 in the occurrence and development of tumors. In fact, Bmi-1 has multiple functions in cancer biology and is closely related to many classical molecules, including Akt, c-MYC, Pten, etc. This review summarizes the regulatory mechanisms of Bmi-1 in multiple pathways, and the interaction of Bmi-1 with noncoding RNAs. In particular, we focus on the pathological processes of Bmi-1 in cancer, and explore the clinical relevance of Bmi-1 in cancer biomarkers and prognosis, as well as its implications for chemoresistance and radioresistance. In conclusion, we summarize the role of Bmi-1 in tumor progression, reveal the pathophysiological process and molecular mechanism of Bmi-1 in tumors, and provide useful information for tumor diagnosis, treatment, and prognosis.

Long non-coding RNA NR2F2-AS1: its expanding oncogenic roles in tumor progression

Long non-coding RNA (LncRNA) is a new type of non-coding RNA whose transcription is more than 200 nucleotides in length and can be up to 100 kb. The crucial regulatory function of lncRNAs in different cellular processes is now notable in many human diseases, especially in different steps of tumorigenesis, making them clinically significant. This research tried to collect all evidence obtained so far regarding Nuclear Receptor subfamily 2 group F member 2 Antisense RNA 1 (NR2F2-AS1) to explore its role in carcinogenesis and molecular mechanism in several cancers. Collecting evidence value an oncogenic role for NR2F2-AS1, whose dysregulation changes the status for cancerous cells to gain the supremacy toward cellular proliferation, dissemination, and ultimately migration. The NR2F2-AS1 acts as competitive endogenous RNA (ceRNA) and contains several microRNA response elements (MREs) for different microRNAs involved in various pathways such as PI3K/AKT, Wnt/β-catenin, and TGF-β. This clinically makes NR2F2-AS1 a remarkable lncRNA which contributes to cancer progression and invasion and perhaps could be a candidate as a prognostic marker or even a therapeutic target.

BMI1 promotes osteosarcoma proliferation and metastasis by repressing the transcription of SIK1

Background

Osteosarcoma (OS) is the most common malignant tumor of bone, and the clinical efficacy of current treatments and associated survival rates need to be further improved by employing novel therapeutic strategies. Although various studies have shown that BMI1 protein is universally upregulated in OS cells and tissues, its specific role and underlying mechanism have not yet been fully explored.

Methods

Expression of BMI1 protein in OS cells was detected by western blot. The effect of BMI1 on proliferation and migration of OS cells (143B and U-2OS cell lines) was investigated in vitro using CCK-8, colony formation and transwell assays, and in vivo using subcutaneous tumorigenesis and lung metastasis assays in xenograft nude mice. Expression of epithelial–mesenchymal transition (EMT)-associated proteins was detected by immunofluorescence imaging. Bioinformatic analysis was performed using ENCODE databases to predict downstream targets of BMI1. SIK1 mRNA expression in osteosarcoma cells was detected by quantitative real-time reverse transcription PCR (qPCR). Chromatin immunoprecipitation-qPCR (ChIP-qPCR) was used to investigate expression of BMI1-associated, RING1B-associated, H2AK119ub-associated and H3K4me3-associated DNA at the putative binding region of BMI1 on the SIK1 promoter in OS cells.

Results

Using both in vitro and in vivo experimental approaches, we found that BMI1 promotes OS cell proliferation and metastasis. The tumor suppressor SIK1 was identified as the direct target gene of BMI1 in OS cells. In vitro experiments demonstrated that SIK1 could inhibit proliferation and migration of OS cells. Inhibition of SIK1 largely rescued the altered phenotypes of BMI1-deficient OS cells. Mechanistically, we demonstrated that BMI1 directly binds to the promoter region of SIK1 in a complex with RING1B to promote monoubiquitination of histone H2A at lysine 119 (H2AK119ub) and inhibit H3K4 trimethylation (H3K4me3), resulting in inhibition of SIK1 transcription. We therefore suggest that BMI1 promotes OS cell proliferation and metastasis by inhibiting SIK1.

Conclusions

Our results reveal a novel molecular mechanism of OS development promoted by BMI1 and provides a new potential target for OS treatment.

CASC5 is a potential cancer-testis gene in human urinary bladder transitional cell carcinoma

Urinary Bladder cancer (UBC) is a diversified disease with an array of clinicopathological attributes. Several studies have shown that cancer susceptibility candidate 5 (CASC5) plays important roles in various types of malignancies; however its expression and clinical significance in human UBC remain largely unknown. This research study was intended to explore mRNA/protein expression pattern of CASC5 as a member of the cancer-testis (CT) gene family and assess its clinical utility in diagnostic management of patients with UBC. Quantitative real-time PCR (qRT-PCR) and immunohistochemistry (IHC) was employed to appraise the detailed expression profile of CASC5 in patients with UBC. The mRNA over expression of CASC5 was detected in testis tissue and relatively high frequency 59.2% (45 of 76) of CASC5 mRNA was detected in UBC tissues. CASC5 mRNA relative mean fold expression was also significantly (p < 0.01) higher in the muscle-invasive tumor tissues compared to non-muscle-invasive tumor tissues (12.26 ± 9.53 vs. 4.64 ± 2.50, p = 0.005). Heterogeneous staining pattern of CASC5 protein was exclusively detected using IHC. The frequency of CASC5 protein over expression was detected in 67.7% (44 of 65) UBC patients and negative in benign prostatic hyperplasia (BPH). Further, CASC5 protein expression was significantly (p < 0.001) associated with cigarette smoking habit in UBC patients. Our study findings testified that CASC5 over expression among patients with UBC as compared to controls and concludes that CASC5 is a potential CT gene in UBC.

RNF144A deficiency promotes PD-L1 protein stabilization and carcinogen-induced bladder tumorigenesis

RNF144A is a DNA damage-induced E3 ubiquitin ligase that targets proteins involved in genome instability for degradation, e.g., DNA-PKcs and BMI1. RNF144A is frequently mutated or epigenetically silenced in cancer, providing the rationale to evaluate RNF144A loss of function in tumorigenesis. Here we report that RNF144A-deficient mice are more prone to the development of bladder tumors upon carcinogen exposure. In addition to DNA-PKcs and BMI1, we identify the immune checkpoint protein PD-L1 as a novel degradation target of RNF144A, since these proteins are expressed at higher levels in Rnf144a KO tumors. RNF144A interacts with PD-L1 in the plasma membrane and intracellular vesicles and promotes poly-ubiquitination and degradation of PD-L1. Therefore, Rnf144a KO stabilizes PD-L1 and leads to a reduction of tumor-infiltrating CD8⁺ T cell populations in the BBN-induced bladder tumors. The bladder tumors developed in WT and Rnf144a KO mice primarily express CK5 and CK14, markers of basal cancer subtype, as expected in BBN-induced bladder tumors. Intriguingly, the Rnf144a KO tumors also express GATA3, a marker for the luminal subtype, suggesting that RNF144A loss of function promotes features of cellular differentiation. Such differentiation features in Rnf144a KO tumors likely result from a decrease of EGFR expression, consistent with the reported role of RNF144A in maintaining EGFR expression. In summary, for the first time our study demonstrates the in vivo tumor suppressor activity of RNF144A upon carcinogenic insult. Loss of RNF144A promotes the expression of DNA-PKcs, BMI1 and PD-L1, likely contributing to the carcinogen-induced bladder tumorigenesis.

Betulinic acid induces autophagy-dependent apoptosis via Bmi-1/ROS/AMPK-mTOR-ULK1 axis in human bladder cancer cells

Betulinic acid (BA), a pentacyclic triterpenoid isolated from tree bark, exhibits antitumor effects against solid malignancies and triggers autophagy and/or apoptosis in human cancer cells. Nonetheless, the relationship between autophagy and apoptosis and the potential modulatory actions of BA on autophagy-dependent bladder cancer cell death remain unclear. The present study showed that BA exposure significantly suppressed viability, proliferation, and migration of EJ and T24 human bladder cancer cells. These effects reflected caspase 3-mediated apoptosis and could be attenuated or abolished by inhibiting ROS production with N-acetyl-L-cysteine, inhibiting autophagy with chloroquine, or silencing ATG7 with targeted siRNA. BA-induced autophagy was evidenced by epifluorescence imaging of lentivirus-induced expression of mCherry-GFP-LC3B and increased expression of two autophagy-related proteins, LC3B-II and TEM. Moreover, enhanced AMPK phosphorylation and decreased mTOR and ULK-1 phosphorylation suggested BA activates autophagy via the AMPK/mTOR/ULK1 pathway. Accordingly, exposure to dorsomorphin (Compound C), an AMPK inhibitor, and AICAR, an AMPK activator, respectively inhibited and stimulated BA-induced autophagy in EJ and T24 cells. The effects of Bmi-1 overexpression in vitro and decreased Bmi-1 expression in BA-treated T24 cell xenografts in nude mice suggested that downregulation of Bmi-1 is the underlying mechanism in BA-mediated, autophagy-dependent apoptosis.

Bladder Cancer-related microRNAs With In Vivo Efficacy in Preclinical Models

Progressive and metastatic bladder cancer remain difficult to treat. In this review, we critique seven up-regulated and 25 down-regulated microRNAs in order to identify new therapeutic entities and corresponding targets. These microRNAs were selected with respect to their efficacy in bladder cancer-related preclinical in vivo models. MicroRNAs and related targets interfering with chemoresistance, cell-cycle, signaling, apoptosis, autophagy, transcription factor modulation, epigenetic modification and metabolism are described. In addition, we highlight microRNAs targeting transmembrane receptors and secreted factors. We discuss druggability issues for the identified targets.

BMI1 activates P-glycoprotein via transcription repression of miR-3682-3p and enhances chemoresistance of bladder cancer cell

Chemoresistance is the most significant reason for the failure of cancer treatment following radical cystectomy. The response rate to the first-line chemotherapy of cisplatin and gemcitabine does not exceed 50%. In our previous research, elevated BMI1 (B-cell specific Moloney murine leukemia virus integration region 1) expression in bladder cancer conferred poor survival and was associated with chemoresistance. Herein, via analysis of The Cancer Genome Atlas database and validation of clinical samples, BMI1 was elevated in patients with bladder cancer resistant to cisplatin and gemcitabine, which conferred tumor relapse and progression. Consistently, BMI1 was markedly increased in the established cisplatin- and gemcitabine-resistant T24 cells (T24/DDP&GEM). Functionally, BMI1 overexpression dramatically promoted drug efflux, enhanced viability and decreased apoptosis of bladder cancer cells upon treatment with cisplatin or gemcitabine, whereas BMI1 downregulation reversed this effect. Mechanically, upon interaction with p53, BMI1 was recruited on the promoter of miR-3682-3p gene concomitant with an increase in the mono-ubiquitination of histone H2A lysine 119, leading to transcription repression of miR-3682-3p gene followed by derepression of ABCB1 (ATP binding cassette subfamily B member 1) gene. Moreover, suppression of P-glycoprotein by miR-3682-3p mimics or its inhibitor XR-9576, could significantly reverse chemoresistance of T24/DDP&GEM cells. These results provided a novel insight into a portion of the mechanism underlying BMI1-mediated chemoresistance in bladder cancer.

BMI-1 Expression Heterogeneity in Endometriosis-Related and Non-Endometriotic Ovarian Carcinoma

BMI-1 is a key component of stem cells, which are essential for normal organ development and cell phenotype maintenance. BMI-1 expression is deregulated in cancer, resulting in the alteration of chromatin and gene transcription repression. The cellular signaling pathway that governs BMI-1 action in the ovarian carcinogenesis sequences is incompletely deciphered. In this study, we set out to analyze the immunohistochemical (IHC) BMI-1 expression in two different groups: endometriosis-related ovarian carcinoma (EOC) and non-endometriotic ovarian carcinoma (NEOC), aiming to identify the differences in its tissue profile. Methods: BMI-1 IHC expression has been individually quantified in epithelial and in stromal components by using adapted scores systems. Statistical analysis was performed to analyze the relationship between BMI-1 epithelial and stromal profile in each group and between groups and its correlation with classical clinicopathological characteristics. Results: BMI-1 expression in epithelial tumor cells was mostly low or negative in the EOC group, and predominantly positive in the NEOC group. Moreover, the stromal BMI-1 expression was variable in the EOC group, whereas in the NEOC group, stromal BMI-1 expression was mainly strong. We noted statistically significant differences between the epithelial and stromal BMI-1 profiles in each group and between the two ovarian carcinoma (OC) groups. Conclusions: Our study provides solid evidence for a different BMI-1 expression in EOC and NEOC, corresponding to the differences in their etiopathogeny. The reported differences in the BMI-1 expression of EOC and NEOC need to be further validated in a larger and homogenous cohort of study.

Assessment of clinicopathological and prognostic relevance of BMI-1 in patients with colorectal cancer: A meta-analysis

B-cell-specific Moloney leukemia virus insertion site 1 (BMI-1) is one of the stemness markers. The prognostic and clinicopathological effects of BMI-1 expression in colorectal cancer (CRC) have been in dispute with different studies. Eligible studies were retrieved from international databases up to December 2019. Studies with a relationship between the clinicopathological and prognostic value of CRC patients with BMI-1 expression were selected. The correlations in the random-effect model were evaluated using the hazard ratios, odds ratio, and 95% confidence intervals (CIs). A total of nine studies comprising Asian cases (seven studies) and European cases (two studies) covering 1,294 samples of CRC were included for this meta-analysis. The analysis suggested that in Asian cases, increased expression of BMI-1 was associated with poor overall survival (OS) and death-free survival, whereas in European populations, high expression of BMI-1 was associated with better OS. Also, overexpression of BMI-1 in the Asian population was associated with the tumor size, distant metastasis, and patient's gender and age. Results suggested that high expression of BMI-1 can be involved in the progression and invasion of CRC, and so its inhibitor-based therapies could be used to prevent the progression of CRC.

Prognostic Significance of ALDH1, Bmi1, and OCT4 Expression in Oral Epithelial Dysplasia and Oral Squamous Cell Carcinoma

BACKGROUND

Increasing evidence suggests the involvement of cancer stem cells (CSCs) in both oral epithelial dysplasia (OED) and oral squamous cell carcinoma (OSCC). Among the various CSC markers, aldehyde dehydrogenase (ALDH) 1, B cell-specific Moloney murine leukaemia virus integration site 1 (Bmi1), and octamer-binding protein 4 (OCT4) have been noted to increase in OSCC. The aim of the study was to analyze ALDH1, Bmi1, and OCT4 expression in OED and OSCC with clinicopathologic correlation and survival analysis.

METHODS

A total of 40 cases each of OED and OSCC were retrieved from departmental archives. Expression of ALDH1, Bmi1, and OCT4 was analyzed using immunohistochemistry and was correlated with clinicopathological parameters. A follow-up ranging from 6 to 52 months was considered for Kaplan-Meier survival analysis. The log-rank test was performed to analyze significant difference in survival rates.

RESULTS

The expression levels of ALDH1, Bmi1, and OCT4 increased significantly from OED through OSCC (P < .05). The expression of ALDH1 and OCT4 showed a significant correlation with lymph node metastasis. Positive cases of ALDH1 showed a significantly reduced survival rate compared to cases showing negative expression. Kaplan-Meier survival analysis showed a significant reduction of survival rate (P = .00) in patients showing a positive expression for all the 3 markers.

CONCLUSION

ALDH1 and OCT4 could be used as individual prognostic markers for assessing prognosis. ALDH1, Bmi1, and OCT4 could be used as a collective panel of markers to enable surgeons in predicting the prognosis of patients and thereby carry out prompt follow-up for such cases.

BSA-bounded p-cresyl sulfate potentiates the malignancy of bladder carcinoma by triggering cell migration and EMT through the ROS/Src/FAK signaling pathway

Para-cresyl sulfate (P-CS), a major uremic toxin derived from the metabolites of tyrosine and phenylalanine through liver, existed in the blood of patients with chronic kidney disease (CKD). CKD increases the malignancy in bladder cancers; however, effects of P-CS on bladder cancers are not fully understood. P-CS is conjugated with BSA physiologically, and this study aims to investigate the effects and possible underlying mechanisms of BSA-bounded P-CS on human bladder cancer cells. With P-CS treatment, the intracellular ROS increased in bladder cancer cells. ROS then triggered epithelial-mesenchymal transition (EMT), stress fiber redistribution, and cell migration. With specific inhibitors, the key signals regulating P-CS-treated migration are Src and FAK. This study provided a clinical clue that patients with higher serum P-CS have a higher risk of malignant urothelial carcinomas, and a regulatory pathway of how P-CS regulates bladder cancer migration.

The expression and prognostic value of stem cell markers Bmi-1, HESC5:3, and HES77 in human papillomavirus-positive and -negative oropharyngeal squamous cell carcinoma

Human papillomavirus is detected in over 50% of oropharyngeal squamous cell carcinomas. Human papillomavirus-positive oropharyngeal squamous cell carcinomas differ from human papillomavirus-negative tumors, and both expression patterns are classified as distinct entities. The Bmi-1 oncogene is a well-known member of the mammalian polycomb-group family. HESC5:3 and HES77 are newly developed monoclonal antibodies produced against undifferentiated embryonic stem cells. Our aim was to explore their roles in both human papillomavirus-positive and -negative oropharyngeal squamous cell carcinomas. Our cohort comprised 202 consecutive oropharyngeal squamous cell carcinoma patients diagnosed and treated with curative intent. We used tissue microarray tumor blocks to study the immunohistochemical expression of Bmi-1, HESC5:3, and HES77. We compared the expressions of these stem cell markers with p16 immunoexpression and human papillomavirus status, as well as with other characteristics of the tumor, and with patients' clinical data and follow-up data. Human papillomavirus- and p16-positive tumors expressed less Bmi-1 and more HESC5:3 than the negative tumors. HES77 expression was high in human papillomavirus-positive oropharyngeal squamous cell carcinoma, but it did not correlate with p16 positivity. In our multivariable model, Bmi-1 and HESC5:3 were still associated with human papillomavirus, but the association between human papillomavirus and HES77 remained absent. In conclusion, Bmi-1, HESC5:3, and HES77 may have a different role in human papillomavirus-positive and human papillomavirus-negative tumors. There was no correlation between Bmi-1, HESC5:3, and HES77 expression and survival.

β-Arrestins Regulate Stem Cell-Like Phenotype and Response to Chemotherapy in Bladder Cancer

β-Arrestins are classic attenuators of G-protein-coupled receptor signaling. However, they have multiple roles in cellular physiology, including carcinogenesis. This work shows for the first time that β-arrestins have prognostic significance for predicting metastasis and response to chemotherapy in bladder cancer. β-Arrestin-1 (ARRB1) and β-arrestin-2 (ARRB2) mRNA levels were measured by quantitative RT-PCR in two clinical specimen cohorts (n = 63 and 43). The role of ARRBs in regulating a stem cell-like phenotype and response to chemotherapy treatments was investigated. The consequence of forced expression of ARRBs on tumor growth and response to Gemcitabine in vivo were investigated using bladder tumor xenografts in nude mice. ARRB1 levels were significantly elevated and ARRB2 levels downregulated in cancer tissues compared with normal tissues. In multivariate analysis only ARRB2 was an independent predictor of metastasis, disease-specific-mortality, and failure to Gemcitabine + Cisplatin (G+C) chemotherapy; ∼80% sensitivity and specificity to predict clinical outcome. ARRBs were found to regulate stem cell characteristics in bladder cancer cells. Depletion of ARRB2 resulted in increased cancer stem cell markers but ARRB2 overexpression reduced expression of stem cell markers (CD44, ALDH2, and BMI-1), and increased sensitivity toward Gemcitabine. Overexpression of ARRB2 resulted in reduced tumor growth and increased response to Gemcitabine in tumor xenografts. CRISPR-Cas9-mediated gene-knockout of ARRB1 resulted in the reversal of this aggressive phenotype. ARRBs regulate cancer stem cell-like properties in bladder cancer and are potential prognostic indicators for tumor progression and chemotherapy response.

Stem-Like Signature Predicting Disease Progression in Early Stage Bladder Cancer. The Role of E2F3 and SOX4

The rapid development of the cancer stem cells (CSC) field, together with powerful genome-wide screening techniques, have provided the basis for the development of future alternative and reliable therapies aimed at targeting tumor-initiating cell populations. Urothelial bladder cancer stem cells (BCSCs) that were identified for the first time in 2009 are heterogenous and originate from multiple cell types; including urothelial stem cells and differentiated cell types—basal, intermediate stratum and umbrella cells Some studies hypothesize that BCSCs do not necessarily arise from normal stem cells but might derive from differentiated progenies following mutational insults and acquisition of tumorigenic properties. Conversely, there is data that normal bladder tissues can generate CSCs through mutations. Prognostic risk stratification by identification of predictive markers is of major importance in the management of urothelial cell carcinoma (UCC) patients. Several stem cell markers have been linked to recurrence or progression. The CD44v8-10 to standard CD44-ratio (total ratio of all CD44 alternative splicing isoforms) in urothelial cancer has been shown to be closely associated with tumor progression and aggressiveness. ALDH1, has also been reported to be associated with BCSCs and a worse prognosis in a large number of studies. UCC include low-grade and high-grade non-muscle invasive bladder cancer (NMIBC) and high-grade muscle invasive bladder cancer (MIBC). Important genetic defects characterize the distinct pathways in each one of the stages and probably grades. As an example, amplification of chromosome 6p22 is one of the most frequent changes seen in MIBC and might act as an early event in tumor progression. Interestingly, among NMIBC there is a much higher rate of amplification in high-grade NMIBC compared to low grade NMIBC. CDKAL1, E2F3 and SOX4 are highly expressed in patients with the chromosomal 6p22 amplification aside from other six well known genes (ID4, MBOAT1, LINC00340, PRL, and HDGFL1). Based on that, SOX4, E2F3 or 6q22.3 amplifications might represent potential targets in this tumor type. Focusing more in SOX4, it seems to exert its critical regulatory functions upstream of the Snail, Zeb, and Twist family of transcriptional inducers of EMT (epithelial–mesenchymal transition), but without directly affecting their expression as seen in several cell lines of the Cancer Cell Line Encyclopedia (CCLE) project. SOX4 gene expression correlates with advanced cancer stages and poor survival rate in bladder cancer, supporting a potential role as a regulator of the bladder CSC properties. SOX4 might serve as a biomarker of the aggressive phenotype, also underlying progression from NMIBC to MIBC. The amplicon in chromosome 6 contains SOX4 and E2F3 and is frequently found amplified in bladder cancer. These genes/amplicons might be a potential target for therapy. As an existing hypothesis is that chromatin deregulation through enhancers or super-enhancers might be the underlying mechanism responsible of this deregulation, a potential way to target these transcription factors could be through epigenetic modifiers.

Bmi1 inhibition enhances the sensitivity of pancreatic cancer cells to gemcitabine

As the standard therapy for pancreatic cancer, gemcitabine shows limited efficacy in pancreatic cancer patients because of chemoresistance. Aberrant expression of Bmi1 has been reported to activate multiple growth-regulatory pathways and confer anti-apoptotic abilities to many cancer cells. However, the role of Bmi1 in response of pancreatic cancer cells towards gemcitabine resistance remains elusive. In this study, we found that certain dose of gemcitabine treatment induced Bmi1 expression in pancreatic cancer cells. Knockdown of Bmi1 enhanced ROS production and promoted the cytotoxic effect of gemcitabine. The increased oxidative stress upon gemcitabine treatment could disrupt mitochondrial membrane and decrease mitochondrial membrane potential, eventually leading to apoptosis. Bmi1 inhibition also suppressed the activation of NF-κB signaling and the expressions of downstream molecules in pancreatic cancer cells treated with gemcitabine. Moreover, we observed Bmi1 inhibition sensitized the pancreatic xenograft tumors to gemcitabine in vivo. Taken together, our study demonstrated that Bmi1 could decrease the sensitivity of pancreatic cancer cells to gemcitabine through increasing oxidative stress and inhibiting NF-κB signaling, thus Bmi1 may serve as a promising target for sensitizing pancreatic cancer cells to chemotherapy.

Desethylamiodarone-A metabolite of amiodarone-Induces apoptosis on T24 human bladder cancer cells via multiple pathways

Bladder cancer (BC) is a common malignancy of the urinary tract that has a higher frequency in men than in women. Cytostatic resistance and metastasis formation are significant risk factors in BC therapy; therefore, there is great interest in overcoming drug resistance and in initiating research for novel chemotherapeutic approaches. Here, we suggest that desethylamiodarone (DEA)–a metabolite of amiodarone—may have cytostatic potential. DEA activates the collapse of mitochondrial membrane potential (detected by JC-1 fluorescence), and induces cell death in T24 human transitional-cell bladder carcinoma cell line at physiologically achievable concentrations. DEA induces cell cycle arrest in the G0/G1 phase, which may contribute to the inhibition of cell proliferation, and shifts the Bax/Bcl-2 ratio to initiate apoptosis, induce AIF nuclear translocation, and activate PARP-1 cleavage and caspase-3 activation. The major cytoprotective kinases—ERK and Akt—are inhibited by DEA, which may contribute to its cell death-inducing effects. DEA also inhibits the expression of B-cell-specific Moloney murine leukemia virus integration site 1 (BMI1) and reduces colony formation of T24 bladder carcinoma cells, indicating its possible inhibitory effect on metastatic potential. These data show that DEA is a novel anti-cancer candidate of multiple cell death-inducing effects and metastatic potential. Our findings recommend further evaluation of its effects in clinical studies.

Analysis of the Epithelium-Mesenchymal Transition Process on Oral Squamous Cell Carcinomas

The aim of this study is to evaluate the immunohistochemical expression of E-cadherin, N-cadherin and Bmi-1, and their association with clinical parameters and with the degree of histopathological differentiation in oral squamous cell carcinomas. 65 squamous cell carcinoma samples were used for constructing a tissue microarray block, and then immunohistochemistry was performed for different markers. A semi-quantitative analysis of the amount of positive tumor cells was performed by two blind and calibrated observers (Kappa>0.75). The statistical Mann-Whitney and Kruskal-Wallis tests were used to evaluate the data. The correlation between variables was investigated by the Spearman test, and the significance level set at p<0.05. We observed higher expression of Bmi-1 in tumors located in the palate (p<0.0001). In addition, poorly differentiated tumors had a greater amount of Bmi-1 positive cells (p=0.0011). Regarding the other correlations between variables, no significant associations were detected. In conclusion, poorly differentiated squamous cell carcinomas located in the palate have higher immunostaining of Bmi-1, which can characterize activation of the Epithelial-Mesenchymal Transition process in these tumors.

Nano-delivery system targeting to cancer stem cell cluster of differentiation biomarkers

Cancer stem cells (CSCs) are one of the most important origins of cancer progression and metastasis. CSCs have unique self-renewal properties and diverse cell membrane receptors that induced the resistance to the conventional chemotherapeutic agents. Therefore, the therapeutic removal of CSCs could result in the cancer cure with lack of recurrence and metastasis. In this regard, targeting CSCs in accordance to their specific biomarkers is a talented attitude in cancer therapy. Various CSCs surface biomarkers have been described, which some of them exhibited similarities on different cancer cell types, while the others are cancer specific and have just been reported on one or a few types of cancers. In this review, the importance of CSCs in cancer development and therapeutic response has been stated. Different CSCs cluster of differentiation (CD) biomarkers and their specific function and applications in the treatment of cancers have been discussed, Special attention has been made on targeted nano-delivery systems. In this regard, several examples have been illustrated concerning specific natural and artificial ligands against CSCs CD biomarkers that could be decorated on various nanoparticulated drug delivery systems to enhance therapeutic index of chemotherapeutic agents or anticancer gene therapy. The outlook of CSCs biomarkers discovery and therapeutic/diagnostic applications was discussed.

Cancer stem cells and epithelial-mesenchymal transition in urothelial carcinoma: Possible pathways and potential therapeutic approaches

There is growing evidence of the presence of cancer stem cells in urothelial carcinoma. Cancer stem cells have the ability to self-renew and to differentiate into all cell types of the original heterogeneous tumor. A panel of diverse cancer stem cell markers might be suitable for simulation studies of urothelial cancer stem cells and for the development of optimized treatment protocols. The present review focuses on the advances in recognizing the markers of urothelial cancer stem cells and possible therapeutic targets. The commonly reported markers and pathways that were evaluated include CD44, CD133, ALDH1, SOX2 & SOX4, BMI1, EZH1, PD-L1, MAGE-A3, COX2/PGE2/STAT3, AR, and autophagy. Studies on the epithelial-mesenchymal transition-related pathways (Shh, Wnt/β-catenin, Notch, PI3K/Akt, TGF-β, miRNA) are also reviewed. Most of these markers were recognized through the expression patterns of cancer stem cell-rich side populations. Their regulative role in the development and differentiation of urothelial cancer stem cells was confirmed in vitro by functional analyses (e.g. cell migration, colony formation, sphere formation), and in vivo in xenograft experiments. Although a small number of these pathways are targeted by currently available drugs or drugs that are the currently being tested in clinical trials, a clear treatment approach has not been developed for most pathways. A greater understanding of the mechanisms that control the proliferation and differentiation of cancer stem cells is expected to lead to improvements in targeted therapy.

B-cell specific Moloney leukemia virus insert site 1 and peptidyl arginine deiminase IV positively regulate carcinogenesis and progression of esophageal squamous cell carcinoma

High expression of B-cell specific Moloney leukemia virus insert site 1 (Bmi-1) and peptidyl arginine deiminase IV (PADI4) is associated with esophageal carcinoma. However, few studies have investigated the association between the Bmi-1 and PADI4 genes. The aim of the present study was to evaluate the expression of Bmi-1 and PADI4 and identify the association between the Bmi-1 and PADI4 genes in esophageal squamous cell carcinoma (ESCC) tissues. Bmi-1 and PADI4 gene expression levels were measured using immunohistochemistry, western blotting and reverse transcription-quantitative polymerase chain reaction in ESCC tissues from 86 patients who had not received pre-operative chemoradiation. The results revealed that the Bmi-1 and PADI4 genes had increased expression in carcinoma tissues compared with pericarcinous tissue (P<0.05). Bmi-1 gene expression was revealed to be associated with differentiation degree, clinical stage and lymph node metastasis (P<0.05), but had no association with gender, age or depth of invasion (P>0.05). The expression of PADI4 was associated with clinical stage, depth of invasion and lymph node metastasis (P<0.05), but was not associated with gender, age or differentiation degree (P>0.05). In addition, there was a positive association between Bmi-1 and PADI4 gene expression in ESCC (P<0.05). These results indicated that Bmi-1 and PADI4 positively regulate carcinogenesis and progression of ESCC.

Risk stratification using Bmi-1 and Snail expression is a useful prognostic tool for patients with upper tract urothelial carcinoma

OBJECTIVES

To investigate the expression levels of E-cadherin, Snail, Twist and Bmi-1 in the human upper tract urothelial carcinoma, and to assess whether these factors could be prognostic markers.

METHODS

Immunohistochemistry was carried out to determine the expression of E-cadherin, Snail, Twist and Bmi-1 in upper tract urothelial carcinoma samples from 144 patients that underwent total nephroureterectomy between January 1995 and December 2010. The patient population had a median age of 71 years, and comprised 104 men and 40 women, with a median follow-up period of 40 months. The prognostic value of these markers was assessed by univariate and multivariate analysis. A risk stratification analysis was carried out.

RESULTS

Snail and Bmi-1 expression predicted worse overall survival (P = 0.0075 and 0.0035), cancer-specific survival (P = 0.0919 and 0.0085) and recurrence-free survival (P = 0.0360 and 0.0817, respectively) compared with tumors that lacked Snail and Bmi-1 expression. Additionally, clinical parameters, grade, stage and lymphovascular invasion correlated with overall survival, cancer-specific survival and recurrence-free survival. Multivariate analysis showed that Bmi-1 expression was among the most significant factors in predicting cancer-specific survival (P = 0.0333). The combination of Snail, Bmi-1 and pathological stage was the most useful prognostic biomarker for upper tract urothelial carcinoma.

CONCLUSION

Risk stratification by epithelial-mesenchymal transition and cancer stem cell-regulated genes, such as Snail and Bmi-1, might be useful prognostic markers for upper tract urothelial carcinoma.

A Polycomb-mir200 loop regulates clinical outcome in bladder cancer

Bladder cancer (BC) is a highly prevalent disease, ranking fifth in the most common cancers worldwide. Various miRNAs have recently emerged as potential prognostic biomarkers in cancer. The miR-200 family, which repressed the epithelial-to-mesenchymal transition (EMT), is repressed in multiple advanced cancers. However, its expression and function in BC is still poorly understood. Here we show that miR-200 family displays increased expression, probably due to the activation of specific oncogenic signaling pathways, and reduced promoter methylation, in BC compared to normal bladder samples. Furthermore, we show that the expression of these miRNAs is decreased in high grade and stage tumors, and the down-regulation is associated with patient's poor clinical outcome. Our data indicate that the miR-200 family plays distinct roles in Non-Muscle (NMIBC) and Muscle-Invasive BC (MIBC). In MIBC, miR-200 expression post transcriptionally regulates EMT-promoting transcription factors ZEB1 and ZEB2, whereas suppresses BMI1 expression in NMIBC. Interestingly, we show that increased EZH2 and/or BMI1 expression repress the expression of miR-200 family members. Collectively, these findings support a model of BC progression through a coordinated action between the Polycomb Repression Complex (PRC) members repressing the miR-200 expression, which ultimately favors invasive BC development. Since pharmacological inhibition of EZH2 in BC cell lines lead to increased miR-200 expression, our findings may support new therapeutic strategies for BC clinical management.

B-cell-specific Moloney murine leukemia virus integration site 1: potential stratification factor and therapeutic target for epithelial ovarian cancer

Epithelial ovarian cancer, a vexing challenge for clinical management, still lacks biomarkers for early diagnosis, precise stratification, and prognostic evaluation of patients. B-cell-specific Moloney murine leukemia virus integration site 1 (BMI1), a member of the polycomb group of proteins, engages in diverse cellular processes, including proliferation, differentiation, senescence, and stem cell renewal. In addition, BMI1, as a cancer stem-cell marker, participates in tumorigenesis through various pathways. Rewardingly, recent studies have also revealed a relationship between BMI1 expression and the clinical grade/stage, therapy response, and survival outcome in a majority of human malignancies, including epithelial ovarian cancer. Therefore, BMI1 might serve as a potential stratification factor and treatment target for epithelial ovarian cancer, pending evidence from further investigations.

BMI1: A Biomarker of Hematologic Malignancies

BMI1 oncogene is a catalytic member of epigenetic repressor polycomb group proteins. It plays a critical role in the regulation of gene expression pattern and consequently several cellular processes during development, including cell cycle progression, senescence, aging, apoptosis, angiogenesis, and importantly self-renewal of adult stem cells of several lineages. Preponderance of evidences indicates that deregulated expression of PcG protein BMI1 is associated with several human malignancies, cancer stem cell maintenance, and propagation. Importantly, overexpression of BMI1 correlates with therapy failure in cancer patients and tumor relapse. This review discusses the diverse mode of BMI1 regulation at transcriptional, posttranscriptional, and posttranslational levels as well as at various critical signaling pathways regulated by BMI1 activity. Furthermore, this review highlights the role of BMI1 as a biomarker and therapeutic target for several subtypes of hematologic malignancies and the importance to target this biomarker for therapeutic applications.

Significance of BMI1 and FSCN1 expression in colorectal cancer

BACKGROUND/AIMS

Colorectal cancer (CRC) is the third most common type of cancer in terms of incidence and the fourth in cause of death world-wide, underscoring the need to identify novel biomarkers for early diagnosis, as well as improved disease stratification and treatment choices.

PATIENTS AND METHODS

The Gene Expression Omnibus (GSE21510) and the Cancer Genome Atlas (TCGA) CRC datasets were utilized in the current study. GeneSpring 13.0 was used for normalization and analysis. The log-rank test was used to compare the outcome between expression groups.

RESULT

Significant upregulation of BMI1 (2.3 FC, P = 3.7 × 10-18) and FSCN1 (1.3 FC,P = 4.7 × 10-3) was observed in CRC. High BMI1 expression was associated with reduced overall survival (OS) [Hazard ratio (HR), 1.87; 95% CI. 1.17-3.03; P= 0.009] and reduced disease-free survival (DFS) [HR, 162; 95% CI 1.01-2.63;P = 0.045]. Similarly, high expression of FSCN1 was associated with reduced OS (HR, 2.0; 95% CI, 1.24-3.2; P= 0.0044) and reduced DFS (HR, 1.60; 95% CI, 0.99-2.57;P = 0.055). Importantly, BMI1high/FSCN1high patients experienced the worst OS (HR, 3.17; 95% CI, 1.77-6.15; P= 0.0002) and DFS (HR, 2.34; 95% CI, 1.27-4.67,P = 0.0078). Using pathway analyses, tumors overexpressing BMI1 were enriched in zinc finger proteins and genes involved in DNA binding and regulation of transcription, whereas tumors expressing FSCN1 were enriched in genes involved in cell migration.

CONCLUSION

Our data revealed poor OS and DFS in CRC patients overexpressing BMI1 or FSCN1 and suggest that these two markers in combination may represent superior prognostic marker to either one. Targeting BMI1 and FSCN1 may also provide potential therapeutic opportunity in CRC.

Polycomb Repressor Complex 1 Member, BMI1 Contributes to Urothelial Tumorigenesis through p16-Independent Mechanisms

Urothelial carcinoma (UC) causes significant morbidity and remains the most expensive cancer to treat because of the need for repeated resections and lifelong monitoring for patients with non-muscle-invasive bladder cancer (NMIBC). Novel therapeutics and stratification approaches are needed to improve the outlook for both NMIBC and muscle-invasive bladder cancer. We investigated the expression and effects of B Lymphoma Mo-MLV Insertion Region 1 (BMI1) in UC. BMI1 was found to be overexpressed in most UC cell lines and primary tumors by quantitative real-time polymerase chain reaction and immunohistochemistry. In contrast to some previous reports, no association with tumor stage or grade was observed in two independent tumor panels. Furthermore, upregulation of BMI1 was detected in premalignant bladder lesions, suggesting a role early in tumorigenesis. BMI1 is not located within a common region of genomic amplification in UC. The CDKN2A locus (which encodes the p16 tumor suppressor gene) is a transcriptional target of BMI1 in some cellular contexts. In UC cell lines and primary tissues, no correlation between BMI1 and p16 expression was observed. Retroviral-mediated overexpression of BMI1 immortalized normal human urothelial cells (NHUC) in vitro and was associated with induction of telomerase activity, bypass of senescence, and repression of differentiation. The effects of BMI1 on gene expression were identified by expression microarray analysis of NHUC-BMI1. Metacore analysis of the gene expression profile implicated downstream effects of BMI1 on α4/β1 integrin-mediated adhesion, cytoskeleton remodeling, and CREB1-mediated transcription.

Knockdown of Bmi1 inhibits bladder cancer cell growth both in vitro and in vivo by blocking cell cycle at G1 phase and inducing apoptosis

Bmi1 is a member of the polycomb group family of proteins, and it drives the carcinogenesis of various cancers and governs the self-renewal of multiple types of stem cells. However, its role in the initiation and progression of bladder cancer is not clearly known. The present study aimed to investigate the function of Bmi1 in the development of bladder cancer. Bmi1 expression was detected in human bladder cancer tissues and their adjacent normal tissues (n=10) by immunohistochemistry, qRT-PCR and Western blotting, respectively. Bmi1 small interference RNA (siRNA) was synthesized and transfected into human bladder carcinoma cells (EJ) by lipofectamine 2000. The Bmil expression at mRNA and protein levels was measured in EJ cells transfected with Bmil siRNA (0, 80, 160 nmol/L) by qRT-PCR and Western blotting, respectively. Cell viability and Ki67 expression (a marker of cell proliferation) were determined in Bmi1 siRNA-transfected cells by CCK-8 assay and qRT-PCR, respectively. Cell cycle of transfected cells was flow-cytometrically determined. Immunofluorescence and Western blotting were used to detect the expression levels of cell cycle-associated proteins cyclin D1 and cyclin E in the cells. Pro-apoptotic proteins Bax and caspase 3 and anti-apoptotic protein Bcl-2 were detected by Western blotting as well. Additionally, xenograft tumor models were established by inoculation of EJ cells (infected with Bmil shRNA/pLKO.1 lentivirus or not) into nude mice. The tumor volumes were measured every other day for 14 days. The results showed that the Bmil expression was significantly increased in bladder tumor tissues when compared with that in normal tissues (P<0.05). Perturbation of Bmi1 expression by using siRNA could significantly inhibit the proliferation of EJ cells (P<0.05). Bmi1 siRNA-transfected EJ cells were accumulated in G1 phase and the expression levels of cyclin D1 and cyclin E were down-regulated. Bax and caspase-3 expression levels were significantly increased and Bcl-2 levels decreased after Bmi1 knockdown. Tumor volume was conspicuously reduced in mice injected with EJ cells with Bmi1 knockdown. Our findings indicate that Bmi1 is a potential driver oncogene of bladder cancer and it may become a potential treatment target for human bladder cancer.

Expression of Oct3/4 and Nanog in the head and neck squamous carcinoma cells and its clinical implications for delayed neck metastasis in stage I/II oral tongue squamous cell carcinoma

BACKGROUND

The side population (SP) of cancer cells is reportedly enriched with cancer stem cells (CSCs), however, the functional role and clinical relevance of CSC marker molecules upregulated in the SP of head and neck squamous carcinoma (HNSCC) cells are yet to be elucidated. Patients with clinical stage I/II (T1-2N0M0) tongue squamous cell carcinoma (TSCC) typically undergo partial glossectomy; however, development of delayed neck metastasis (DNM) tends to reduce their survival. In the present study, we aimed to determine the CSC markers in the SP of HNSCC cells along with their functions in cellular behaviors, and to clarify the association of these markers with DNM.

METHODS

Flow cytometry was applied to isolate SP from main population (MP) in HNSCC cells. The expression of the CSC markers was examined by semi-quantitative RT-PCR and immunocytochemistry. In vitro proliferation, migration, and invasion assays were performed to assess cellular behaviors. Clinicopathological factors and immunohistochemical expressions of Oct3/4 and Nanog were evaluated using surgical specimens from 50 patients with stage I/II TSCC.

RESULTS

SPs were isolated in all three cell lines examined. Expression levels of Oct3/4 and Nanog were higher in SP cells than MP cells. Additionally, cell migration and invasion abilities were higher in SP cells than MP cells, whereas there was no difference in proliferation. Univariate analysis showed that expression of Oct3/4 and Nanog, vascular and muscular invasion, and mode of invasion were significantly correlated with DNM. Multivariate logistic regression revealed that Oct3/4 expression (risk ratio = 14.78, p = 0.002) and vascular invasion (risk ratio = 12.93, p = 0.017) were independently predictive of DNM. Regarding the diagnostic performance, Oct3/4 showed the highest accuracy, sensitivity, and NPV of 82.0 %, 61.5 %, and 86.8 %, respectively, while vascular invasion showed the highest specificity and PPV of 94.6 % and 71.4 %, respectively.

CONCLUSION

These results suggest that Oct3/4 and Nanog represent probable CSC markers in HNSCC, which contribute to the development of DNM in part by enhancing cell motility and invasiveness. Moreover, along with vascular invasion, expression of Oct3/4 can be considered a potential predictor for selecting patients at high risk of developing DNM.

Inhibition of Lon blocks cell proliferation, enhances chemosensitivity by promoting apoptosis and decreases cellular bioenergetics of bladder cancer: potential roles of Lon as a prognostic marker and therapeutic target in baldder cancer

ATP-dependent Lon protease within mitochondrial matrix contributes to the degradation of abnormal proteins. The oxidative or hypoxic stress which represents the stress phenotype of cancer leads to up-regulation of Lon. However, the role of Lon in bladder cancer remains undefined. Here, we found that Lon expression in bladder cancer tissues was significantly higher than those in noncancerous tissues; down-regulation of Lon in bladder cancer cells significantly blocked cancer cell proliferation via suppression c-Jun N-terminal kinase (JNK) phosphorylation due to decreased reactive oxygen species (ROS) production and enhanced the sensitivity of bladder cancer cells to chemotherapeutic agents by promoting apoptosis. We further found that Lon down-regulation in bladder cancer cells decreased cellular bioenergetics as determined by measuring aerobic respiration and glycolysis using extracellular flux analyzer. The tissue microarray (TMA) results showed that high expression of Lon was related to the T and TNM stage, as well as histological grade of bladder cancer patients. We also demonstrated that Lon was an independent prognostic factor for overall survival of bladder cancer. Taken together, our data suggest that Lon could serve as a potential diagnostic biomarker and therapeutic target for treatment of bladder cancer, as well as for prediction of the effectiveness of chemotherapy.

BMI-1, a promising therapeutic target for human cancer

BMI-1 oncogene is a member of the polycomb-group gene family and a transcriptional repressor. Overexpression of BMI-1 has been identified in various human cancer tissues and is known to be involved in cancer cell proliferation, cell invasion, distant metastasis, chemosensitivity and patient survival. Accumulating evidence has revealed that BMI-1 is also involved in the regulation of self-renewal, differentiation and tumor initiation of cancer stem cells (CSCs). However, the molecular mechanisms underlying these biological processes remain unclear. The present review summarized the function of BMI-1 in different human cancer types and CSCs, and discussed the signaling pathways in which BMI-1 is potentially involved. In conclusion, BMI-1 may represent a promising target for the prevention and therapy of various cancer types.

Deregulation of miR-128 in ovarian cancer promotes cisplatin resistance

OBJECTIVE

Platinum-based chemotherapy is the standard treatment in advanced ovarian cancer, but most patients will relapse with drug-resistant disease. MicroRNAs have been demonstrated to function in chemoresistance in cancers. In this study, we focused on the role of miR-128 in cisplatin-resistant ovarian cancer.

MATERIALS AND METHODS

The expression of miR-128 RNA and its targeted genes, the polycomb ring finger oncogene Bmi-1 and ATP-binding cassette subfamily C member 5 (ABCC5), were investigated in the epithelial ovarian cancer cells and ovarian carcinomas.

RESULTS

miR-128 expression was significantly reduced in the cisplatin-resistant human epithelial ovarian cancer cell line SKOV3/CP compared with parental SKOV3 cells and decreased upon treatment with cisplatin in a concentration-dependent manner in SKOV3, OVCAR3, and PEO14 cells. Overexpression of miR-128 resensitized SKOV3/CP cells to cisplatin and reduced the expression of cisplatin-resistant-related proteins ABCC5 and Bmi-1, whereas miR-128 inhibitors increased cisplatin resistance in SKOV3 cells. Cisplatin combined with miR-128 agomirs inhibited the growth of SKOV3/CP xenograft tumors more effectively than cisplatin alone. Diminished expression of ABCC5 and Bmi-1 and higher cisplatin concentrations were observed in tumor tissue of mice treated with miR-128 agomirs in addition to cisplatin.

CONCLUSIONS

Taken together, our findings suggest that miR-128 may act as a promising therapeutic target for improvement of tumor sensitivity to cisplatin.

High peritumoral Bmi-1 expression is an independent prognosticator of poor prognosis in renal cell carcinoma

B lymphoma Mo-MLV insertion region 1 homolog (Bmi-1) is a transcriptional repressor, which plays important roles in the development of cancers, but the function of Bmi-1 in kidney tumorigenesis and its prognostic values remain unclear. This study aims to investigate prognostic values of the intratumoral and peritumoral expression of Bmi-1 in patients with renal cell carcinoma. Expression of Bmi-1 was assessed by immunohistochemistry in specimens containing paired tumor and peritumoral renal tissue from 241 patients who had undergone curative nephrectomy at Zhongshan Hospital from 2005 to 2007. The association of Bmi-1 expression with clinical and pathological parameters and outcomes was investigated. Specific expression of Bmi-1 was found both in peritumoral and intratumoral tissues. High expression of Bmi-1 in peritumoral but not intratumoral is significantly associated with poor overall survival (OS) (P < 0.001) and relapse-free survival (RFS) (P = 0.003). Furthermore, Bmi-1 expression was identified as an independent prognostic factor for OS, and combination of peritumoral Bmi-1 and tumor node metastasis (TNM) stage had a better power to predict the patients' death and disease recurrence. High peritumoral Bmi-1 expression can serve as an independent prognostic biomarker and could be a novel therapeutic target for renal cell carcinoma (RCC).

The Polycomb group protein RING1B is overexpressed in ductal breast carcinoma and is required to sustain FAK steady state levels in breast cancer epithelial cells

In early stages of metastasis malignant cells must acquire phenotypic changes to enhance their migratory behavior and their ability to breach the matrix surrounding tumors and blood vessel walls. Epigenetic regulation of gene expression allows the acquisition of these features that, once tumoral cells have escape from the primary tumor, can be reverted. Here we report that the expression of the Polycomb epigenetic repressor Ring1B is enhanced in tumoral cells that invade the stroma in human ductal breast carcinoma and its expression is coincident with that of Fak in these tumors. Ring1B knockdown in breast cancer cell lines revealed that Ring1B is required to sustain Fak expression in basal conditions as well as in Tgfβ-treated cells. Functionally, endogenous Ring1B is required for cell migration and invasion in vitro and for in vivo invasion of the mammary fat pad by tumoral cells. Finally we identify p63 as a target of Ring1B to regulate Fak expression: Ring1B depletion results in enhanced p63 expression, which in turns represses Fak expression. Importantly, Fak downregulation upon Ring1B depletion is dependent on p63 expression. Our findings provide new insights in the biology of the breast carcinoma and open new avenues for breast cancer prognosis and therapy.

Silencing BMI1 eliminates tumor formation of pediatric glioma CD133+ cells not by affecting known targets but by down-regulating a novel set of core genes

Clinical outcome of children with malignant glioma remains dismal. Here, we examined the role of over-expressed BMI1, a regulator of stem cell self-renewal, in sustaining tumor formation in pediatric glioma stem cells. Our investigation revealed BMI1 over-expression in 29 of 54 (53.7%) pediatric gliomas, 8 of 8 (100%) patient derived orthotopic xenograft (PDOX) mouse models, and in both CD133⁺ and CD133⁻ glioma cells. We demonstrated that lentiviral-shRNA mediated silencing of suppressed cell proliferation in vitro in cells derived from 3 independent PDOX models and eliminated tumor-forming capacity of CD133⁺ and CD133⁻ cells derived from 2 PDOX models in mouse brains. Gene expression profiling showed that most of the molecular targets of BMI1 ablation in CD133⁺ cells were different from that in CD133- cells. Importantly, we found that silencing BMI1 in CD133⁺ cells derived from 3 PDOX models did not affect most of the known genes previously associated with the activated BMI1, but modulated a novel set of core genes, including RPS6KA2, ALDH3A2, FMFB, DTL, API5, EIF4G2, KIF5c, LOC650152, C20ORF121, LOC203547, LOC653308, and LOC642489, to mediate the elimination of tumor formation. In summary, we identified the over-expressed BMI1 as a promising therapeutic target for glioma stem cells, and suggest that the signaling pathways associated with activated BMI1 in promoting tumor growth may be different from those induced by silencing BMI1 in blocking tumor formation. These findings highlighted the importance of careful re-analysis of the affected genes following the inhibition of abnormally activated oncogenic pathways to identify determinants that can potentially predict therapeutic efficacy.

Histone modifications: Targeting head and neck cancer stem cells

Head and neck squamous cell carcinoma (HNSCC) is the sixth most common cancer worldwide, and is responsible for a quarter of a million deaths annually. The survival rate for HNSCC patients is poor, showing only minor improvement in the last three decades. Despite new surgical techniques and chemotherapy protocols, tumor resistance to chemotherapy remains a significant challenge for HNSCC patients. Numerous mechanisms underlie chemoresistance, including genetic and epigenetic alterations in cancer cells that may be acquired during treatment and activation of mitogenic signaling pathways, such as nuclear factor kappa-light-chain-enhancer-of activated B cell, that cause reduced apoptosis. In addition to dysfunctional molecular signaling, emerging evidence reveals involvement of cancer stem cells (CSCs) in tumor development and in tumor resistance to chemotherapy and radiotherapy. These observations have sparked interest in understanding the mechanisms involved in the control of CSC function and fate. Post-translational modifications of histones dynamically influence gene expression independent of alterations to the DNA sequence. Recent findings from our group have shown that pharmacological induction of post-translational modifications of tumor histones dynamically modulates CSC plasticity. These findings suggest that a better understanding of the biology of CSCs in response to epigenetic switches and pharmacological inhibitors of histone function may directly translate to the development of a mechanism-based strategy to disrupt CSCs. In this review, we present and discuss current knowledge on epigenetic modifications of HNSCC and CSC response to DNA methylation and histone modifications. In addition, we discuss chromatin modifications and their role in tumor resistance to therapy.

miR-200c inhibits invasion, migration and proliferation of bladder cancer cells through down-regulation of BMI-1 and E2F3

Background

MicroRNA-200c (miR-200c) is one of the short noncoding RNAs that play crucial roles in tumorigenesis and tumor progression. It also acts as considerable modulator in the process of epithelial-to-mesenchymal transition (EMT), a cell development regulating process that affects tumor development and metastasis. However, the role of miR-200c in bladder cancer cells and its mechanism has not been well studied. The purpose of this study was to determine the potential role of miR-200c in regulating EMT and how it contributed to bladder cancer cells in invasion, migration and proliferation.

Methods

Real-time reverse transcription-PCR was used to identify and validate the differential expression of MiR-200c involved in EMT in 4 bladder cancer cell lines and clinical specimens. A list of potential miR-200 direct targets was identified through the TargetScan database. The precursor of miR-200c was over-expressed in UMUC-3 and T24 cells using a lentivirus construct, respectively. Protein expression and signaling pathway modulation were validated through Western blot analysis and confocal microscopy, whereas BMI-1 and E2F3, direct target of miR-200c, were validated by using the wild-type and mutant 3′-untranslated region BMI-1/E2F3 luciferase reporters.

Results

We demonstrate that MiR-200c is down-regulated in bladder cancer specimens compared with adjacent ones in the same patient. Luciferase assays showed that the direct down-regulation of BMI-1 and E2F3 were miR-200c-dependent because mutations in the two putative miR-200c-binding sites have rescued the inhibitory effect. Over-expression of miR-200c in bladder cancer cells resulted in significantly decreased the capacities of cell invasion, migration and proliferation. miR-200c over-expression resulted in conspicuous down-regulation of BMI-1and E2F3 expression and in a concomitant increase in E-cadherin levels.

Conclusions

miR-200c appears to control the EMT process through BMI-1 in bladder cancer cells, and it inhibits their proliferation through down-regulating E2F3. The targets of miR-200c include BMI-1 and E2F3, which are a novel regulator of EMT and a regulator of proliferation, respectively.

Electronic supplementary material

The online version of this article (doi:10.1186/s12967-014-0305-z) contains supplementary material, which is available to authorized users.

Validation of Bmi1 as a therapeutic target of hepatocellular carcinoma in mice

Bmi1 is a member of the polycomb group family of proteins, and it drives the carcinogenesis of various cancers and governs the self-renewal of multiple types of stem cells. Our previous studies have revealed that Bmi1 acts as an oncogene in hepatic carcinogenesis in an INK4a/ARF locus independent manner. However, whether Bmi1 can be used as a potential target for hepatocellular carcinoma treatment has not been fully confirmed yet. Here, we show that perturbation of Bmi1 expression by using short hairpin RNA can inhibit the tumorigenicity and tumor growth of hepatocellular carcinoma cells both in vitro and in vivo. Importantly, Bmi1 knockdown can block the tumor growth, both in the initiating stages and the fast growing stages. Cellular biology analysis revealed that Bmi1 knockdown induces cell cycle arrest and apoptosis. Our findings verify Bmi1 as a qualified treatment target for hepatocellular carcinoma (HCC) and support Bmi1 targeting treatment with chemotherapeutic agents.

Prognostic role of high Bmi-1 expression in Asian and Caucasian patients with solid tumors: a meta-analysis

Recently, many studies have shown that the B-cell-specific moloney leukemia virus insertion site 1 (Bmi-1) exhibits altered expression in various cancers and may serve as prognostic biomarkers. We performed a meta-analysis to evaluate the prognostic role of Bmi-1 expression in solid cancers. Studies were recruited by searching PubMed, Embase and the Cochrane Library. Thirty-nine articles including 40 studies were involved in this meta-analysis. Our results indicated that the Bmi-1 showed the opposite prognostic effect in Asian and Caucasian populations. High Bmi-1 expression as a negative predictor for overall survival (OS) in Asian patients (HR=1.96, 95% CI 1.62-2.36), but a positive predictor in Caucasian populations (HR=0.77, 95% CI 0.63-0.93). Furthermore, we took a further subgroup analysis based on tumor type in these two populations, respectively. In Asian cases, high expression of Bmi-1 was associated with poor OS in oesophageal carcinoma (HR=1.93, 95% CI 1.52-2.46), gastric cancer (HR=1.50, 95% CI 1.22-1.85), lung cancer (HR=1.73, 95% CI 1.05-2.85), cervical cancer (HR=2.80, 95% CI 2.26-3.47) and colorectal cancer (HR=3.36, 95% CI 2.19-5.15), rather than in breast cancer and HCC. In Caucasian populations, high expression of Bmi-1 was associated with better OS in breast cancer (HR=0.70, 95% CI 0.51-0.97), but it showed no significance in oesophageal carcinoma. In conclusion, high Bmi-1 expression was significantly associated with poor survival in Asian patients with oesophageal carcinoma, gastric cancer, lung cancer, colorectal cancer and cervical carcinoma, whereas high level of Bmi-1 can predict better prognosis in Caucasian patients with breast cancer.

Frequent expression of zinc-finger protein ZNF165 in human urinary bladder transitional cell carcinoma

The aim of the study is to evaluate mRNA/protein expression of zinc finger protein 165 (ZNF165) in transitional cell carcinomas (TCCs) of urinary bladder and correlate its expression with the clinicopathological characteristics of patients. In this study, the methods of quantitative real-time polymerase chain reaction (qRT-PCR) and immunohistochemistry (IHC) were utilized to evaluate mRNA/protein expression of ZNF165 in TCC. Independent Student's t test, ANOVA and Chi-square (χ(2)) were used to analyze the data statistically. We observed overexpression of ZNF165 mRNA in testis and majority (59.2%) of TCC patients. ZNF165 mRNA expression was also detected in adjacent noncancerous tissues (ANCTs) and some other normal tissues. Relative mean fold expression of ZNF165 mRNA was found to be significantly (p<0.01) higher in muscle-invasive bladder cancer (MIBC) as compared to non-muscle-invasive bladder cancer (NMIBC) patients. (12.11±9.57 vs. 5.72±2.61, p=0.009). ZNF165 protein expression was demonstrated on archival formalin-fixed, paraffin-embedded (FFPE) bladder tissues using IHC and nuclear staining pattern was detected. No significant difference was observed in protein expression of ZNF165 between the two groups (NMIBC and MIBC patients) (61.1% vs. 55.2%, p=0.629). No significant protein expression of ZNF165 was observed among ANCTs and benign prostatic hyperplasia (BPH) used as control. Our study results suggest that ZNF165 mRNA/protein expression was observed in TCC of human urinary bladder and might be used as a novel diagnostic biomarker and as well a vaccine target in development of urinary bladder cancer specific immunotherapy.

Expression of B-cell-specific Moloney murine leukemia virus integration site 1 mRNA and protein in gastric cancer

OBJECTIVE

To investigate the role of B-cell-specific Moloney murine leukemia virus integration site 1 (Bmi-1) in gastric cancer (GC) and its relationship with the clinicopathological features of GC.

METHODS

Laser capture microdissection combined with real-time polymerase chain reaction and Western blot were used to determine the expressions of Bmi-1, the cellular homologue of avian myelocytomatosis virus (c-Myc), enhancer of Zeste homolog 2 (EZH2), phosphatase and tensin homologue (PTEN) and epithelial cadherin (E-cadherin) in 20 GC specimens and the adjacent non-cancerous gastric tissues.

RESULTS

The mRNA and protein expressions of Bmi-1 in GC were increased compared with those of the non-cancerous gastric tissues (P = 0.012 and P = 0.000, respectively). Bmi-1 mRNA expression was positively correlated with tumor size, degree of tumor differentiation, invasion and lymph node metastasis. At both mRNA and protein levels, Bmi-1 was positively correlated with c-Myc and EZH2, but negatively correlated with PTEN and E-cadherin.

CONCLUSION

Bmi-1 might be involved in GC at both transcription and translation levels.

The expressions of stem cell markers: Oct4, Nanog, Sox2, nucleostemin, Bmi, Zfx, Tcl1, Tbx3, Dppa4, and Esrrb in bladder, colon, and prostate cancer, and certain cancer cell lines

Uncontrolled self-renewal plays a direct function in the progression of different types of carcinomas. The same molecular pathway that manages self-renewal in normal stem cells also seems to manage cancer stem cells. Here, we examine the expressions of self-renewal regulatory factors Oct4, Nanog, Sox2, nucleostemin, Zfx, Esrrb, Tcl1, Tbx3, and Dppa4 in tissue samples of colon, prostate, and bladder carcinomas as well as cancer cell lines HT-29, Caco-2, HT-1376, LNCaP, and HepG2. We used reverse transcriptase polymerase chain reaction to examine expressions of the above mentioned regulatory factors in cancer cell lines HT-29, Caco-2, HT-1376, LNCaP, and HepG2 and in 20 tumor tissue samples. Total RNA was isolated by the ISOGEN method. RNA integrity was checked by agarose gel electrophoresis and spectrophotometry. Expressions of Oct4 and nucleostemin at the protein level were determined by immunocytochemistry. A significant relationship was found between tumor grade and self-renewal gene expression. Expressions of stem cell specific marker genes were detected in all examined cancer cell lines, in 40% to 100% of bladder cancer samples, and in 60% to 100% of colon and prostate cancer samples. Oct4 expressed in 100% of tumor tissue samples. Our data show that stem cell markers Oct4, Nanog, Sox2, nucleostemin, Bmi, Zfx, Esrrb, Tcl1, Tbx3, and Dppa4 significantly express in cancer cell lines and cancer tissues. Hence, these markers might be useful as potential tumor markers in the diagnosis and/or prognosis of tumors.

Knockdown of Bmi1 inhibits the stemness properties and tumorigenicity of human bladder cancer stem cell-like side population cells

B-cell-specific Moloney murine leukemia virus insertion site 1 (Bmi1) is directly involved in cell growth, proliferation and self-renewal of cancer stem cells (CSCs). The aim of the present study was to assess the role of Bmi1 in the maintenance of stemness properties and tumorigenicity of human bladder CSC-like side population (SP) cells. SP cells were sorted by flow cytometry using Hoechst 33342 staining. Bmi1 mRNA and protein expression in SP and non-SP (NSP) cells was analyzed by quantitative PCR, immunofluorescence and western blotting. The stemness properties of SP cells included cell proliferation, migration, self-renewal, chemotherapy resistance and cell cycle progression were assessed. Tumor formation was also assessed in human bladder cancer xenografts after Bmi1 silencing. The mRNA expression of Bmi1 was upregulated in SP cells when compared with that in the NSP cells. Knockdown of Bmi1 in SP cells resulted in inhibition of cell proliferation, migration and tumor sphere formation, enhanced sensitivity to cisplatin, and cell cycle arrest in the G0/G1 phase. Bmi1 knockdown inhibited cell cycle progression through derepression of the p16INK4a/p14ARF locus. Bmi1-siRNA SP cells failed to produce tumors in recipient mice, while typical urothelial carcinoma formed from subcutaneously injected scramble-siRNA SP cells. Bmi1 is crucial for the maintenance of stemness properties and tumorigenicity of human bladder CSC-like cells. Bmi1 may be a potential therapeutic target for the eradication of CSCs in bladder cancer.

Immunohistochemical expression and prognostic relevance of Bmi-1, a stem cell factor, in epithelial ovarian cancer

Ovarian cancer is the fourth most common cause of cancer-related death in women. Bmi-1 is a stem cell factor implicated in many human malignancies with poor outcome. Few published reports on the expression of Bmi-1 in epithelial ovarian cancer were either experimental or performed on cell lines. This study evaluates the immunohistochemical expression of Bmi-1 protein in epithelial ovarian cancer tissue specimens and its relevance to the clinicopathologic prognostic variables and patient survival. Forty cases of epithelial ovarian cancer were selected according to the availability of paraffin-embedded tissue and the clinicopathologic and survival data. Immunohistochemistry was performed for anti-Bmi-1 antibody. Low and high Bmi-1 expression groups were compared with age, tumor stage, laterality, grade, histology, and patient survival. Bmi-1 expression was detected in 72.5% of cases, of which 42.5% had high expression. High Bmi-1 expression strongly associated with advanced International Federation of Gynecology and Obstetrics stages (P = .007), bilaterality (P = .01), and higher Gynecologic Oncology Group grades (P = .031) and carcinomas of serous histology (P = .027). It had no association with patient age. Bmi-1 expression displayed a significant inverse association with patient overall and mean survival (P = .006, P < .001). These observations suggested correlation between increased Bmi-1 expression and clinical progression in ovarian epithelial cancer.