Overexpression of EZH2 and loss of expression of PTEN is associated with invasion, metastasis, and poor progression of gallbladder adenocarcinoma

Mechanisms of Ferroptosis-Related Genes in Gallbladder Cancer Based on Bioinformatics Analysis

Gallbladder Cancer (GBC) is a lethal malignancy with limited treatment options and poor prognosis. Recent studies have emphasized the role of ferroptosis, a regulated form of cell death, in various cancers, including GBC. We applied bioinformatics methodologies on four GBC datasets to identify differentially expressed genes (DEGs). An intersection of DEGs from the four datasets with ferroptosis and GBC-associated genes was done to identify key ferroptosis-related genes in GBC. GSVA pathway enrichment analysis and immune cell infiltration assessment were conducted to explore their functional roles and interactions. Seven ferroptosis-related genes, EZH2, MUC1, PVT1, GOT1, CDO1, LIFR, and TFAP2A, were identified to be related to GBC. These genes were associated with vital signaling pathways like the G2/M checkpoint and DNA repair and showed significant correlations with immune cell infiltration in GBC. Receiver Operating Characteristic (ROC) curve analysis revealed their high diagnostic potential, with Area Under the Curve (AUC) values ranging from 0.796 to 0.953. Our findings underscore the pivotal role of ferroptosis in GBC and the potential of ferroptosis-related genes as diagnostic biomarkers. This study lays a foundation for further research into ferroptosis-based therapeutic strategies for GBC.

Evaluation of Tazemetostat as a Therapeutically Relevant Substance in Biliary Tract Cancer

Biliary tract cancer (BTC) is a gastrointestinal malignancy associated with a poor survival rate. Current therapies encompass palliative and chemotherapeutic treatment as well as radiation therapy, which results in a median survival of only one year due to standard therapeutic ineffectiveness or resistance. Tazemetostat is an FDA-approved inhibitor of enhancer of Zeste homolog 2 (EZH2), a methyltransferase involved in BTC tumorigenesis via trimethylation of histone 3 at lysine 27 (H3K27me3), an epigenetic mark associated with silencing of tumor suppressor genes. Up to now, there are no data available regarding tazemetostat as a possible treatment option against BTC. Therefore, the aim of our study is a first-time investigation of tazemetostat as a potential anti-BTC substance in vitro. In this study, we demonstrate that tazemetostat affects cell viability and the clonogenic growth of BTC cells in a cell line-dependent manner. Furthermore, we found a strong epigenetic effect at low concentrations of tazemetostat, which was independent of the cytotoxic effect. We also observed in one BTC cell line that tazemetostat increases the mRNA levels and protein expression of the tumor suppressor gene Fructose-1,6-bisphosphatase 1 (FBP1). Interestingly, the observed cytotoxic and epigenetic effects were independent of the mutation status of EZH2. To conclude, our study shows that tazemetostat is a potential anti-tumorigenic substance in BTC with a strong epigenetic effect.

CircTP63 promotes cell proliferation and invasion by regulating EZH2 via sponging miR-217 in gallbladder cancer

Background

Gallbladder cancer (GBC) is the most common biliary tract malignancy and has a poor prognosis in patients with GBC. CircRNA TP63 (circTP63) has been implicated in cell proliferation and invasion in some tumor progress. The study aims to investigate the clinical significance and functional role of circTP63 expression in GBC.

Methods

The expression of circTP63 in GBC tissues or cells was detected by qRT-PCR and the association between circTP63 expression and prognosis of GBC patients was analyzed. CCK8 assay, flow cytometry analysis, transwell assay and in vivo studies were used to evaluate the cell proliferation and invasion abilities after circTP63 knockdown in GBC cells. Luciferase reporter assays and RNA pull-down assay were used to determine the correlation between circTP63 and miR-217 expression. Besides, western blot analysis was also performed.

Results

In the present study, we showed that circTP63 expression was upregulated in GBC tissues and cells. Higher circTP63 expression was associated with lymph node metastasis and short overall survival (OS) in patients with GBC. In vitro, knockdown of circTP63 significantly inhibited cell proliferation, cell cycle progression, migration and invasion abilities in GBC. Besides, we demonstrated that knockdown of circTP63 inhibited GBC cells Epithelial-Mesenchymal Transition (EMT) process. In vivo, knockdown of circTP63 inhibited tumor growth in GBC. Mechanistically, we demonstrated that circTP63 competitively bind to miR-217 and promoted EZH2 expression and finally facilitated tumor progression.

Conclusions

Our findings demonstrated that circTP63 sponged to miR-217 and regulated EZH2 expression and finally facilitated tumor progression in GBC. Thus, targeting circTP63 may be a therapeutic strategy for the treatment of GBC.

Enhancer of Zeste Homolog 2 (EZH2) in Malignant Progression of Gallbladder Carcinoma

PURPOSE

Data related to the role of epigenetic modifications in gallbladder carcinoma (GBC) is limited. We intended to assess the role of crucial epigenetic modifiers pertaining to histone modification and DNA-methylation system in gallbladder carcinogenesis.

METHODS

The expression of EZH2, H3K27me3, and DNA methyltransferases (DNMTs) was analyzed by immunohistochemistry in cases of GBC (n = 39), gallbladder dysplasia (GBD, n = 12), and benign mucosa (BM, n = 16). A semi-quantitative scoring system was used for assessing the immunohistochemical expression.

RESULTS

The expression of EZH2 was significantly higher in cases of GBC than GBD (p value 0.001). The cases of BM were negative. Its expression was also higher in poorly differentiated tumors and positively correlated with the proliferative activity (MIB-1 labeling index) (p value 0.03 and 0.01, respectively). There was no significant difference in the expression levels of H3K27me3, DNMT-1, and DNMT-3B among GBC, GBD, and BM cases. Although GBC cases with strong EZH2 expression showed a shorter overall survival, the difference was not statistically significant.

CONCLUSION

This study highlights the crucial role of the key epigenetic regulators EZH2 in the pathobiology and evolution of gallbladder carcinogenesis. Given the reversibility of epigenetic alterations, EZH2 may be a novel therapeutic target for gallbladder carcinogenesis.

Long Non-Coding RNAs in Biliary Tract Cancer-An Up-to-Date Review

The term long non-coding RNA (lncRNA) describes non protein-coding transcripts with a length greater than 200 base pairs. The ongoing discovery, characterization and functional categorization of lncRNAs has led to a better understanding of the involvement of lncRNAs in diverse biological and pathological processes including cancer. Aberrant expression of specific lncRNA species was demonstrated in various cancer types and associated with unfavorable clinical characteristics. Recent studies suggest that lncRNAs are also involved in the development and progression of biliary tract cancer, a rare disease with high mortality and limited therapeutic options. In this review, we summarize current findings regarding the manifold roles of lncRNAs in biliary tract cancer and give an overview of the clinical and molecular consequences of aberrant lncRNA expression as well as of underlying regulatory functions of selected lncRNA species in the context of biliary tract cancer.

Contemporary Tailored Oncology Treatment of Biliary Tract Cancers

Biliary tract cancers (BTCs) are poor prognosis malignancies with limited treatment options. Capecitabine has recently emerged as an effective agent in the adjuvant setting; however, treatment of advanced disease is still limited to first-line cisplatin and gemcitabine chemotherapy. Recent global efforts in genomic profiling and molecular subtyping of BTCs have uncovered a wealth of genomic aberrations which may carry prognostic significance and/or predict response to treatment, and several targeted agents have shown promising results in clinical trials. As such, the uptake of comprehensive genomic profiling for patients with BTCs and the expansion of basket trials to include these patients are growing. This review describes the currently approved systemic therapies for BTCs and provides insight into the emerging targeted and immunotherapeutic agents, as well as conventional chemotherapeutic regimes, currently being investigated in clinical trials.

Molecular pathways and potential biomarkers in gallbladder cancer: A comprehensive review

The most common malignancy of the biliary tract, gallbladder cancer (GBC) often has a dismal prognosis. The aggressive nature of the tumor, delayed diagnosis at advanced stages of the disease, and lack of effective treatment options are some of the factors that contribute to a poor outcome. Early detection and accurate assessment of disease burden is critical to optimize management and improve long-term survival, as well as identify patients for adjuvant therapy and clinical trials. With recent advances in the understanding of the molecular pathogenesis of GBC, several specific diagnostic and biomarkers have been proposed as being of diagnostic and prognostic importance. Indeed, identification of novel diagnostic and prognostic markers has an important role in early diagnosis and development of targeted therapies among patients with GBC. Next-generation sequencing technology and genomewide data analysis have provided novel insight into understanding the molecular pathogenesis of biliary tract cancers, thereby identifying potential biomarkers for clinical use. We herein review available GBC biomarkers and the potential clinical implications in the management of GBC.

Targeting the PI3K/AKT/mTOR pathway in biliary tract cancers: A review of current evidences and future perspectives

Biliary tract cancers (BTCs) are a group of invasive neoplasms, with increasing incidence and dismal prognosis. In advanced disease, the standard of care is represented by first-line chemotherapy with cisplatin and gemcitabine. In subsequent lines, no clear recommendations are currently available, highlighting the need for novel therapeutic approaches. The PI3K/AKT/mTOR pathway is a core regulator of cell metabolism, growth and survival, and is involved in BTCs carcinogenesis and progression. Mutations, gene copy number alterations and aberrant protein phosphorylation of PI3K, AKT, mTOR and PTEN have been thoroughly described in BTCs and correlate with poor survival outcomes. Several pre-clinical evidences state the efficacy of PI3K/AKT/mTOR pathway inhibitors in BTCs, both in vitro and in vivo. In the clinical setting, initial studies with rapamycin analogs have shown interesting activity with an acceptable toxicity profile. Novel strategies evaluating AKT and PI3K inhibitors have risen serious safety concerns, pointing out the need for improved patient selection and increased target specificity for the clinical development of these agents, both alone and in combination with chemotherapy. This review extensively describes the role of the PI3K/AKT/mTOR pathway in BTCs and examines the rationale of its targeting in these tumors, with particular focus on clinical activity, toxicities and perspectives on further development of PI3K/AKT/mTOR pathway inhibitors.

Targeting phosphoinositide-3-kinase pathway in biliary tract cancers: A remedial route?

Biliary tract cancers (BTC) are aggressive tumours with a low survival rate. At the advent of the genomic era, various genetic mutations in cell signalling pathways have been incriminated in carcinogenesis. Genomic analysis studies have connected main components of the phosphoinositide-3-kinase (PI3K) signalling pathway to BTC. PI3K pathway playing a central role in cell signalling and being deregulated in various tumours has been studied as a target for chemotherapy. Novel compounds have also been identified in preclinical trials that specifically target the PI3K pathway in BTCs, but these studies have not accelerated to clinical use. These novel compounds can be examined in upcoming studies to validate them as potential therapeutic agents, as further research is required to combat the growing need for adjuvant chemotherapy to successfully battle this tumour type. Furthermore, these molecules could also be used along with gemcitabine, cisplatin and 5-fluorouracil to improve sensitivity of the tumour tissue to chemotherapy. This review focuses on the basics of PI3K signalling, genetic alterations of this pathway in BTCs and current advancement in targeting this pathway in BTCs. It emphasizes the need for gene-based drug screening in BTC. It may reveal various novel targets and drugs for amelioration of survival in patients with BTC and serve as a stepping stone for further research.

Anti-tumor effects of NVP-BKM120 alone or in combination with MEK162 in biliary tract cancer

There are currently no clinically validated therapeutic targets for biliary tract cancer (BTC). Despite promising results in other cancers, compounds targeting the phosphatidylinositol 3-kinase (PI3K)/AKT pathway, alone or in combination with Ras/Raf/MEK pathway inhibitors, have not been evaluated in BTC. Here, we examined the effects of a pan-PI3K inhibitor (BKM120) with or without a MEK inhibitor (MEK162), on eight human BTC cell lines carrying mutations in K-Ras and/or the PI3K catalytic subunit, PI3KCA. BKM120 inhibited the colony-forming ability and migration of BTC cells carrying wild-type (WT) PI3KCA and either mutant (MT) or WT K-Ras, but not of cells carrying mutations in both genes. In K-Ras-WT cells, BKM120 decreased the phosphorylation of Akt, its downstream effector kinase p70S6K, and the translational repressor 4E-BP1. Interestingly, BKM120 did not induce cell cycle arrest or suppress PI3K signaling via restoration of p-4E-BP1 in cells with PIK3CA and K-Ras double mutations. Notably, the resistance of dual K-Ras/PI3KCA-mutant cells to BKM120 was overcome by treatment with a combination of BKM120 and MEK162. Our findings thus support the clinical development of BKM120 monotherapy or BKM120/MEK162 combination therapy for the treatment of BTC.

HDAC8 Prevents Anthrax Lethal Toxin-induced Cell Cycle Arrest through Silencing PTEN in Human Monocytic THP-1 Cells

Anthrax lethal toxin (LeTx) is a cytotoxic virulence factor that causes cell cycle arrest and cell death in various cell types. However, susceptibility to the cytotoxic effects varies depending on cell types. In proliferating monocytes, LeTx has only transient cytotoxic effects due to activation of the phosphoinositide 3-kinase (PI3K)-AKT-mediated adaptive responses. To date, the mechanism of LeTx in activating PI3K-AKT signaling axis is unknown. This study shows that the histone deacetylase 8 (HDAC8) is involved in activating PI3K-AKT signaling axis through down-regulating the phosphatase and tensin homolog 1 (PTEN) in human monocytic THP-1 cells. The HDAC8-specific activator TM-2-51 and inhibitor PCI-34051 enhanced and prevented, respectively, AKT activation and cell cycle progression in LeTx-treated cells. Furthermore, HDAC8 induced tri-methylation of histone H3 lysine 27 (H3K27me3), which is known to suppress PTEN expression, through at least in part down-regulating the H3K27me3 eraser Jumonji Domain Containing (JMJD) 3. Importantly, the JMJD3-specific inhibitor GSK-J4 induced AKT activation and protected cell cycle arrest in LeTx-treated cells, regardless the presence of HDAC8 activity. Collectively, this study for the first time demonstrated that HDAC8 activity determines susceptibility to cell cycle arrest induced by LeTx, through regulating the PI3K-PTEN-AKT signaling axis.

Deregulated MicroRNAs in Biliary Tract Cancer: Functional Targets and Potential Biomarkers

Biliary tract cancer (BTC) is still a fatal disease with very poor prognosis. The lack of reliable biomarkers for early diagnosis and of effective therapeutic targets is a major demanding problem in diagnosis and management of BTC. Due to the clinically silent and asymptomatic characteristics of the tumor, most patients are diagnosed at an already advanced stage allowing only for a palliative therapeutic approach. MicroRNAs are small noncoding RNAs well known to regulate various cellular functions and pathologic events including the formation and progression of cancer. Over the last years, several studies have shed light on the role of microRNAs in BTC, making them potentially attractive therapeutic targets and candidates as biomarkers. In this review, we will focus on the role of oncogenic and tumor suppressor microRNAs and their direct targets in BTC. Furthermore, we summarize and discuss data that evaluate the diagnostic power of deregulated microRNAs as possible future biomarkers for BTC.

Prognostic value of high EZH2 expression in patients with different types of cancer: a systematic review with meta-analysis

Enhancer of zeste homologue 2 (EZH2) is a potential independent mechanism for epigenetic silencing of tumor suppressor genes in cancer. We conducted an electronic search on PubMed, EMBASE, Web of Science, and Cochrane library to perform this up-to-date meta-analysis. Fifty-one studies with a total of 9444 patients were included. The prevalence of high EZH2 expression was 0.54 (95% CI: 0.47-0.61). High EZH2 expression was significantly associated with poorer prognosis [overall survival: HR 1.54 (95% CI: 1.30-1.78), P < 0.000; disease free survival: HR 1.35 (95% CI: 1.00-1.71), P < 0.000]. In breast cancer, high EZH2 expression correlated with histological types [OR: 1.53 (95CI: 1.13-2.06); P < 0.006], histological grade [OR: 1.62 (95CI: 1.35-1.95); P < 0.000], estrogen receptor (ER) negativity [OR: 2.05 (95CI: 1.67-2.52); P < 0.000], progesterone receptor (PgR) negativity [OR: 1.42 (95CI: 1.03-1.96); P = 0.034], HER-2 positivity [OR: 1.35 (95CI: 1.08-1.69); P = 0.009], and high p53 expression [OR: 1.66 (95CI: 1.07-2.59); P = 0.024]. These results suggest that high EZH2 expression may be a promising prognostic factor to different cancers. High EZH2 expression tends to correlate with pathological types, histological grade, ER negativity, PgR negativity, HER-2 positivity and p53 high expression in breast cancer.

Long non-coding RNA MINCR promotes gallbladder cancer progression through stimulating EZH2 expression

The regulation of MYC-regulated long non-coding RNAs has been reported to contribute to certain types of cancers. However, the role of MYC-induced long non-coding RNA (MINCR) in the tumorigenesis of gallbladder cancer (GBC) is still largely unknown. In this study, we discovered that MINCR was markedly upregulated in GBC tissues compared with adjacent normal tissues. High MINCR expression levels in GBC were positively associated with tumor volume and lymph node metastasis and were negatively correlated with overall survival (OS). Upregulation of MINCR and enhancer of zeste homolog 2 (EZH2) in GBC coincided with the downregulation of miR-26a-5p in GBC. Mechanistically, MINCR/miR-26a-5p/EZH2 axis was found to be involved in cell proliferation, cell invasive and apoptosis in GBC cells. Moreover, knockdown of MINCR suppressed cell proliferation, decreased S-phase cell numbers, increased cell apoptosis, and inhibited cell invasion by inhibiting the epithelial-mesenchymal transition (EMT) phenomenon in GBC cells. In vivo, tumor volumes were significantly decreased in the MINCR silencing group compared with those in the control group. These results demonstrated that MINCR could potentially be a therapeutic target as well as a prognostic marker in GBC.

Expression of PTEN and Its Correlation with Proliferation Marker Ki-67 in Head and Neck Cancer

Introduction

PTEN is part of large family of tyrosine phosphatases and has been found inactivated in a wide variety of human cancers.

Aims

In the present study we have tried to determine the association of the expression patterns of this gene with carcinogenesis.

Methods

First, a systematic review was carried out to ascertain the importance of the PTEN gene and its role in carcinogenesis. In the second phase, a case-control study was designed using different expression analysis techniques. Expression of PTEN mRNA was analyzed using reverse transcriptase polymerase chain reaction (RT-PCR).

Results

Significantly downregulated expression of PTEN was observed in patients with head and neck cancer (HNC) compared to adjacent normal-tissue controls. These results were confirmed with quantitative polymerase chain reaction (qPCR). Significant downregulation of the gene was observed in HNC patients compared to adjacent normal-tissue controls. PTEN expression was correlated with different histopathological parameters of the study cohort by Spearman's correlation coefficient and a significant negative correlation was observed with pT stage (r = −0.271*; p<0.02) and grade (r = −0.228*; p<0.02) of HNC tissues. Furthermore, the expression variations of PTEN were correlated with the expression pattern of the proliferation marker Ki-67. Significantly (p<0.008) upregulated expression of Ki-67 was observed in HNC patients compared with adjacent normal-tissue controls This upregulation of Ki-67 was confirmed at the protein level by immunohistochemistry in HNC patients. When Spearman's correlation was carried out a significant negative correlation was observed between PTEN and Ki-67 (r = −0.230*; p<0.03).

Conclusions

Our data suggest that downregulation of PTEN and overexpression of Ki-67 may contribute to the initiation and progression of HNC.

Power of PTEN/AKT: Molecular switch between tumor suppressors and oncogenes

An increasing amount of evidence has shown that tumor suppressors can become oncogenes, or vice versa, but the mechanism behind this is unclear. Recent findings have suggested that phosphatase and tensin homolog (PTEN) is one of the powerful switches for the conversion between tumor suppressors and oncogenes. PTEN regulates a number of cellular processes, including cell death and proliferation, through the phosphoinositide 3-kinase/protein kinase B/mammalian target of rapamycin (PI3K/AKT/mTOR) pathway. Furthermore, a number of studies have suggested that PTEN deletions may alter various functions of certain tumor suppressor and oncogenic proteins. The aim of the present review was to analyze specific cases driven by PTEN loss/AKT activation, including aberrant signaling pathways and novel drug targets for clinical application in personalized medicine. The findings illustrate how PTEN loss and/or AKT activation switches MDM2-dependent p53 downregulation, and induces conversion between oncogene and tumor suppressor in enhancer of zeste homolog 2, BTB domain-containing 7A, alternative reading frame 2, p27 and breast cancer 1, early onset, through multiple mechanisms. This review highlights the genetic basis of complex drug targets and provides insights into the rationale of precision cancer therapy.

Advances in biomarkers of biliary tract cancers

Tumor biomarkers can be applied for early diagnosis or precise treatment, thereby leading to personalized treatment and better outcomes. Biliary tract cancers (BTCs) are a group of cancers that occurs in different locations and have different clinical or genetic properties. Though the incidence of BTCs is rare, BTCs are among the most lethal cancers in the world and all have very low 5-year survivals. Lack of efficient early diagnostic approaches or adjuvant therapies for BTCs are main reasons. These urge us to broaden the researches into BTC biomarkers. Although few progresses of diagnostic biomarkers for BTCs have been achieved, there are still some advances in prognostic, predictive and therapeutic areas. In this review, we will focus on these achievements.

Effects of PTEN gene alteration in patients with gallbladder cancer

Gallbladder cancer (GBC) is an aggressive malignancy usually diagnosed in an advanced stage. We investigated the effects of alterations of the phosphatase and tensin homologue (PTEN) gene on the occurrence and development of GBC, which has not been previously reported. A total 141 cases of GBC were analyzed for mutation, expression, and methylation across the nine exons of the PTEN gene. DNA sequencing methods were applied for mutation detection, whereas protein expression and methylation status were evaluated by immunohistochemical and methylation-specific PCR analysis, respectively. Novel PTEN mutations were observed in 6.3% of cases (9/141), and they included two silent mutations. In mutant cases, according to changes in codons, the respective amino acid sequences were also changed, which caused of proteins. A high percentage (72%) of loss of protein expression was observed more often in cases than in control samples. Interestingly, all nine cases with mutations showed loss of PTEN expression, whereas four of these nine cases showed positive promoter methylation. Hypermethylation was significantly more common in older patients than in younger ones (P<0.02). These findings suggest that PTEN mutations and inactivation may play an important role in the development and progression of gallbladder carcinoma.

Inactivation of tumor suppressor gene pten in early and advanced gallbladder cancer

Background

PTEN is a tumor suppressor gene that regulates the PTEN/PI3k/AKT/mTOR pathway, which is frequently altered in human cancers including gallbladder cancer (GBC). To determine the frequency of PTEN expression in GBC and to establish its relation to clinical and morphological parameters and survival in GBC.

Methods

The immunohistochemical expression of PTEN was studied in 108 GBC. All the cases included areas of non-tumor mucosa adjacent to the tumor.

Results

The group was comprised of 108 patients, 91 women (84.3 %) and 17 men (15.7 %) with an average age of 65.2 years (SD ± 12.3 years). Thirty-five cases (33 %) were early carcinomas (EC) and the remaining 73 (67 %) were advanced cases (AC). All the internal controls were positive (moderate or intense in 96.3 %). Only in three AC (4.1 %) was there a complete absence of PTEN immunohistochemical expression. There were no significant differences in relation between PTEN expression and tumor infiltration or degree of differentiation. The three patients with PTEN inactivation died before 10 months; however, the other patients with AC had a survival of 53 % at 10 months.

Discussion

Loss of PTEN expression was observed in 4.1 % of the advanced GBC. All the patients with this alteration died before 10 months. PTEN inactivation could be a rare event, but with a poor prognosis in advanced GBC.

Enhancer of zeste homolog 2 as an independent prognostic marker for cancer: a meta-analysis

Background

Novel biomarkers are of particular interest for predicting cancer prognosis. This study aimed to explore the associations between enhancer of zeste homolog 2 (EZH2) and patient survival in various cancers.

Methods

Relevant literature was retrieved from PubMed and Web of Science databases. Pooled hazard ratios (HRs), odds ratios (ORs), and 95% confidence intervals (CIs) were calculated.

Results

Forty-nine studies (8,050 patients) were included. High EZH2 expression was significantly associated with shorter overall (hazard ratio [HR] 1.74, 95% CI: 1.46–2.07), disease-free (HR 1.59, 95% CI: 1.27–1.99), metastasis-free (HR 2.19, 95% CI: 1.38–3.47), progression-free (HR 2.53, 95% CI: 1.52–4.21), cancer-specific (HR 3.13, 95% CI: 1.70–5.74), and disease-specific (HR 2.29, 95% CI: 1.56–3.35) survival, but not recurrence-free survival (HR 1.38, 95% CI: 0.93–2.06). Moreover, EZH2 expression significantly correlated with distant metastasis (OR 3.25, 95% CI: 1.07–9.87) in esophageal carcinoma; differentiation (OR 3.00, 95% CI: 1.37–6.55) in non-small cell lung cancer; TNM stage (OR 3.18, 95% CI: 2.49–4.08) in renal cell carcinoma; and histological grade (OR 4.50, 95% CI: 3.33–6.09), estrogen receptor status (OR 0.15, 95% CI: 0.11–0.20) and progesterone receptor status (OR 0.30, 95% CI: 0.23–0.39) in breast cancer.

Conclusions

Our results suggested that EZH2 might be an independent prognostic factor for multiple survival measures in different cancers.

The role of CD29-ILK-Akt signaling-mediated epithelial-mesenchymal transition of liver epithelial cells and chemoresistance and radioresistance in hepatocellular carcinoma cells

Hepatocellular carcinomas (HCC) are aggressive cancers, and the prognosis of HCC patients is poor. This study investigated the roles of CD29 in epithelial-mesenchymal transition (EMT) and chemoresistance and radioresistance in HCC tumors. CD29 expression in HCC and peritumoral tissues was measured by immunohistochemistry. CD29 overexpression was established by an adenovirus-carrying CD29 gene expression cassette, while silencing of CD29 expression was established by an adenovirus-carrying shRNA. Western blot was used to measure protein expression, and MTT was used to analyze cell viability. Xenograft HCC mouse model was established by inoculating isolated CD29(+) and CD29(-) HCC tumor cells. Significantly higher percentage of positive CD29 expression was observed in HCC tissues compared to peritumoral tissues. Xenograft CD29(+) tumors grew more quickly than CD29(-) tumors. CD29(+) tumors were more resistant to radiotherapy and cisplatin therapy than CD29(-) tumors. Overexpression of CD29 significantly increased the resistance of CD29(-) tumors to radiation and cisplatin treatment. In contrast, silencing of CD29 expression significantly sensitized CD29(+) tumors to irradiation and cisplatin treatment. Overexpression of CD29 decreased E-cadherin, but increased fibronectin, vimentin, ILK activity, Akt Ser(473) phosphorylation, and mTORC1 protein expression in Hep G2 and THLE-3 cells. Moreover, overexpression of CD29 significantly increased the resistance of Hep G2 and THLE-3 cells to starvation, radiation, and cisplatin treatments. This study suggests that CD29 plays a crucial role in the resistance of HCC to chemo/radiotherapy and EMT of liver epithelial cells.

Role of aberrant PI3K pathway activation in gallbladder tumorigenesis

The PI3K/AKT pathway governs a plethora of cellular processes, including cell growth, proliferation, and metabolism, in response to growth factors and cytokines. By acting as a unique lipid phosphatase converting phosphatidylinositol-3,4,5,-trisphosphate (PIP3) to phosphatidylinositol-4,5,-bisphosphate (PIP2), phosphatase and tensin homolog (PTEN) acts as the major cellular suppressor of PI3K signaling and AKT activation. Recently, PI3K mutations and loss/mutation of PTEN have been characterized in human gallbladder tumors; whether aberrant PTEN/PI3K pathway plays a causal role in gallbladder carcinogenesis, however, remains unknown. Herein we show that in mice, deregulation of PI3K/AKT signaling is sufficient to transform gallbladder epithelial cells and trigger fully penetrant, highly proliferative gallbladder tumors characterized by high levels of phospho-AKT. Histopathologically, these mouse tumors faithfully resemble human adenomatous gallbladder lesions. The identification of PI3K pathway deregulation as both an early event in the neoplastic transformation of the gallbladder epithelium and a main mechanism of tumor growth in Pten heterozygous and Pten mutant mouse models provides a new framework for studying in vivo the efficacy of target therapies directed against the PI3K pathway, as advanced metastatic tumors are often addicted to “trunkular” mutations.

Targeting specific molecular pathways holds promise for advanced gallbladder cancer therapy

Gallbladder cancer is the most common and aggressive malignancy of the biliary tract. The complete surgical resection is the only potentially curative approach in early stage; however, most cases are diagnosed in advanced stages and the response to traditional chemotherapy and radiotherapy is extremely limited, with modest impact in overall survival. The recent progress in understanding the molecular alterations of gallbladder cancer has shown great promise for the development of more effective treatment strategies. This has mainly resulted from the identification of molecular alterations in relevant intracellular signaling pathways-Hedgehog, PI3K/AKT/mTOR, Notch, ErbB, MAPK and angiogenesis-which are potential tailored targets for gallbladder cancer patients. This review discusses the recent remarkable progress in understanding the molecular alterations that represent novel prognosis molecular markers and therapeutic targets for gallbladder cancer, which will provide opportunities for research and for developing innovative strategies that may enhance the benefit of conventional chemotherapy, or eventually modify the fatal natural history of this orphan disease.

The role of polycomb repressive complexes in biliary tract cancer

INTRODUCTION

Polycomb group proteins are major epigenetic regulators that modify histone tails. They are organized in two multi-protein complexes called polycomb repressive complex (PRC) 1 and 2. Aberrant PRC activity is known to contribute to the development and aggressiveness of many cancers. Biliary tract cancer (BTC) is a rare malignancy associated with high chemoresistance and poor clinical outcome. Here we review the role of the PRC complexes and the effects of RNAi and drug-mediated inhibition of PRC1 and PRC2 in BTC.

AREAS COVERED

This review gives a short overview of the composition, biochemical functions and oncogenic role of PRC complexes. We then focus on and summarize the results of current studies that address the role of PRC in BTC. Finally, we discuss options and results of therapeutic targeting of PRC in BTC.

EXPERT OPINION

Pharmacological inhibition of the two PRC complexes seems to be a promising strategy for treatment of BTC. To date, only few studies have addressed the therapeutic effect of PRC inhibition in BTC. Therefore, it will be important to test established PRC inhibitors, such as DZNep, as well as newly developed drugs, for example, PTC209, to gain more insight into the role of the PRC complexes in BTC and potentially to develop new therapeutic strategies.

MicroRNA-101 inhibits the metastasis of osteosarcoma cells by downregulation of EZH2 expression

MicroRNAs (miRNAs) are a class of small non‑coding RNA molecules, which play regulatory roles at the post-transcriptional level by suppressing the translation of protein‑coding genes or inducing mRNA cleavage. Dysregulated expression of miRNAs is involved in multiple types of cancers and plays important roles in regulating various biological processes including metastasis. miR-101 is downregulated in various types of cancer and functions as a suppressor of cell migration and invasion. Meanwhile, enhancer of zeste homolog 2 (EZH2) is associated with the metastatic potential of several aggressive tumors. In the present study, we reported that ectopic overexpression of miR-101 downregulated the expression level of EZH2 and significantly inhibited migration and invasion of osteosarcoma cells. In addition, knockdown of EZH2 by siRNA showed the same effect of miR-101 on migration and invasion. To conclude, these results indicate that miR-101 may act as a tumor suppressor in osteosarcoma, as it has a suppressive role in cell migration and invasion by targeting EZH2.

A genetic model for gallbladder carcinogenesis and its dissemination

Gallbladder cancer, although regarded as the most common malignancy of the biliary tract, continues to be associated with a dismal overall survival even in the present day. While complete surgical removal of the tumour offers a good chance of cure, only a fraction of the patients are amenable to curative surgery owing to their delayed presentation. Moreover, the current contribution of adjuvant therapies towards prolonging survival is marginal, at best. Thus, understanding the biology of the disease will not only enable a better appreciation of the pathways of progression but also facilitate the development of an accurate genetic model for gallbladder carcinogenesis and dissemination. This review provides an updated, evidence-based model of the pathways of carcinogenesis in gallbladder cancer and its dissemination. The model proposed could serve as the scaffolding for elucidation of the molecular mechanisms involved in gallbladder carcinogenesis. A better understanding of the pathways involved in gallbladder tumorigenesis will serve to identify patients at risk for the cancer (and who thus could be offered prophylactic cholecystectomy) as well as aid oncologists in planning the most suitable treatment for a particular patient, thereby setting us on the vanguard of transforming the current treatment paradigm for gallbladder cancer.

Effects of EZH2 gene on the growth and migration of hepatocellular carcinoma HepG2 cells

OBJECTIVE

To investigate the effects of EZH2 gene on the growth and migration of hepatocellular carcinoma HepG2 cell in vitro and in vivo.

METHODS

EZH2 shRNA plasmid vectors were constructed and transfected into HepG2 cells. A model of EZH2 gene-silencing HepG2 cell lines was constructed, and the experimental cells were classified into 3 groups: HepG2 blank control group, HepG2-V vector control group and HepG2-EZH2 (-) group. The mRNA and protein expressions of EZH2 in these three cells were detected by real-time fluorogenic quantitative PCR and Western blotting, respectively. Cell proliferation was analyzed by MTT assay. Cells were inoculated subcutaneously in nude mice, and the growth of tumor cells in vivo was observed. Transwell chamber assay was performed to observe any change in the migration ability of cells.

RESULTS

The mRNA expression of HepG2 and HepG2-V was 100% and (95.27±10.87)%, respectively. Compared with the control group, the mRNA level of HepG2-EZH2 (-) were significantly decreased to (20.55±13.21)% (P<0.001). Similarly, the EZH2 protein expression were inhibited in HepG2-EZH2 (-) cells. The inhibition rate of tumor growth was 36.3% in vitro and 52.5% in vivo. The migration rate of the HepG2-EZH2 (-) group [(7.15±1.13)%] was significantly lower than those in the HepG2 group [(14.57±4.32)%] and the HepG2-V group [(15.21±5.22)%], with significant differences (both P<0.05).

CONCLUSIONS

EZH2 silencing can effectively inhibit the proliferation and growth of HepG2 cells in vitro and in vivo and inhibit cell migration. Therefore, the EZH2 gene may be a novel target for the treatment of liver cancer.

EZH2 expression in invasive lobular carcinoma of the breast

Background

Invasive lobular carcinoma (ILC) is the second most common histologic type of breast cancer, but the prognosis of ILC is still controversial. Enhancer of Zeste homolog 2 (EZH2), the catalytic subunit of the Polycomb repressive complex 2 (PRC2), is frequently overexpressed in various cancers. This study evaluated the relationship between clinicopathologic characteristics and EZH2 expression.

Methods

We retrospectively reviewed the medical records of 54 patients with ILC and selected 49 cases of ILC. Immunohistochemistry for EZH2 was undertaken.

Results

We defined ILC as discohesive cells with a linear or nonlinear growth pattern. No statistically significant difference was found for most variables, including multifocality, menstrual status, body mass index, tumor stage (pT), lymph node stage (pN), estrogen receptor, and progesterone receptor. In contrast, nuclear grade was statistically significant and EZH2 expression was associated with high nuclear grade. In total, 80% of nuclear grade 3 cases had an EZH2 score of 4, and 86% of nuclear grade 1 cases had EZH2 scores of 1 and 2. Our cases had a score of 3 for tubule formation and a score of 1 for mitosis, and so the histologic grading consisted of grades 1 (7 cases) and 2 (42 cases) depending on the nuclear grade.

Conclusion

Although EZH2 could not predict survival in our study, EZH2 expression was associated with a high nuclear grade. Most ILCs have histologic grade 2 with nuclear grade 2 or 3. Therefore, our opinion is that if ILC is diagnosed by separating the classic type and variants and considering both EZH2 expression and nuclear grade, EZH2 overexpression could help and the Nottingham grading system would be more accurate prognostic factor.

Enhancer of zeste homolog 2 expression is associated with metastasis and adverse clinical outcome in clear cell renal cell carcinoma: a comparative study and review of the literature

CONTEXT

Enhancer of zeste homolog 2 (EZH2), a histone methyltransferase mediating chromatin condensation and epigenetic modulation, is overexpressed in various human carcinomas and is associated with adverse clinicopathologic characteristics and biologic behavior. The expression of EZH2 in renal cell carcinomas (RCCs) has not been fully characterized yet.

OBJECTIVE

To evaluate the prognostic role of EZH2 in RCC by analyzing the immunohistochemical staining pattern of the marker in relation to pathologic features and clinical outcome.

DESIGN

We correlated the immunolabeling of EZH2 with multiple clinicopathologic features, including Fuhrman nuclear grade, pathologic stage, metastatic status, and clinical outcome in 223 clear cell RCCs (CRCCs) and 21 papillary RCCs, by using tissue microarrays of primary and metastatic cases.

RESULTS

Most CRCCs (75%) showed positive EZH2 staining, with most primary tumors showing focal staining in comparison to nonfocal staining in metastatic cases. In primary tumors, EZH2 expression was associated with higher nuclear grade and lower pathologic stage. Metastatic tumors showed a higher number of positive cases (81% versus 67%) and a more diffuse and more intense pattern of staining than primary CRCCs. For the 22 locally advanced primary tumors (T3/4) and 43 metastatic RCCs, patients who experienced RCC-related deaths significantly overexpressed the marker in comparison to patients who did not experience RCC-related mortality.

CONCLUSIONS

By showing that EZH2 expression is associated with increased metastatic potential and a worse clinical outcome, this study suggests that EZH2 can serve as a prognostic biomarker for RCC, thus confirming it as a key molecule driving oncogenesis and metastasis.

State-of-the-art in the management of locally advanced and metastatic gallbladder cancer

PURPOSE OF REVIEW

Gallbladder carcinoma (GBC), classified as a biliary tract cancer (BTC) along with intrahepatic and extrahepatic cholangiocarcinomas, is a rare disease in Western countries, but a highly prevalent disease in Chile, other countries in Latin America, India and Japan. It commonly presents at an advanced stage, and has limited therapeutic options. Cisplatin/gemcitabine has emerged as the first-line standard of care for patients with advanced BTCs, but the prognosis remains poor. Development of molecularly targeted therapies in advanced BTC remains challenging.

RECENT FINDINGS

Comprehension of the molecular events in gallbladder carcinogenesis may provide a novel targeted therapeutic approach, and early stage clinical trials with targeted therapies appear promising, although the relationship between subsets of patients with positive responses to therapy and tumor genetics requires further exploration. Recent developments in targeted therapeutics, directed against several key signalling pathways in BTC, including epidermal growth factor receptor, angiogenesis, and the mitogen-activated protein kinase pathway will be discussed, in addition to the potential application of prognostic factors and markers.

SUMMARY

The future therapeutic spectrum for BTC and GBC will likely encompass novel combinations of targeted therapies with cytostatics in scientifically and molecularly directed schedules, thus permitting fewer mechanisms of escape for tumor cells.

A single nucleotide polymorphism in EZH2 predicts overall survival rate in patients with cholangiocarcinoma

Cholangiocarcinoma (CCA) is a deadly disease arising from the malignant transformation of cholangiocytes. Enhancer of zeste homolog 2 (EZH2) is overexpressed in poorly differentiated CCA. Functional single nucleotide polymorphisms (SNPs) in this gene may affect the role of EZH2 in cholangiocarcinogenesis and chemoresistance. The aim of the current study was to evaluate the correlation between EZH2 SNPs and clinical outcome. Using PROMO3.0, GeneCard and MicroSNiper, 4 EZH2 SNPs with functional relevance in CCA were selected in silico. These SNPs were studied in genomic DNA extracted from the blood samples of 75 patients with advanced CCA, who were treated with epirubicin-cisplatin-xeloda (ECX regimen). SNP genotyping was performed with specific PCR assays. The rs887569 TT genotype was correlated with a significantly longer overall survival (OS; TT vs. CT-CC, P=0.026). Moreover, the TT genotype revealed a trend toward a significant association with a reduced risk of mortality (HR, 0.59; 95% CI, 0.33-1.05; P=0.075), by multivariate analysis. These results support future studies on the role of rs887569 EZH2 SNP as a possible predictive marker of OS in advanced CCA patients.

Connective tissue growth factor immunohistochemical expression is associated with gallbladder cancer progression

CONTEXT

Gallbladder cancer (GBC) is an aggressive neoplasia associated with late diagnosis, unsatisfactory treatment, and poor prognosis. Molecular mechanisms involved in GBC pathogenesis remain poorly understood. Connective tissue growth factor (CTGF) is thought to play a role in the pathologic processes and is overexpressed in several human cancers, including GBC. No information is available about CTGF expression in early stages of gallbladder carcinogenesis. Objective.- To evaluate the expression level of CTGF in benign and malignant lesions of gallbladder and its correlation with clinicopathologic features and GBC prognosis.

DESIGN

Connective tissue growth factor protein was examined by immunohistochemistry on tissue microarrays containing tissue samples of chronic cholecystitis (n = 51), dysplasia (n = 15), and GBC (n = 169). The samples were scored according to intensity of staining as low/absent and high CTGF expressers. Statistical analysis was performed using the χ(2) test or Fisher exact probability test with a significance level of P < .05. Survival analysis was assessed by the Kaplan-Meier method and the log-rank test.

RESULTS

Connective tissue growth factor expression showed a progressive increase from chronic cholecystitis to dysplasia and then to early and advanced carcinoma. Immunohistochemical expression (score ≥2) was significantly higher in advanced tumors, in comparison with chronic cholecystitis (P < .001) and dysplasia (P = .03). High levels of CTGF expression correlated with better survival (P = .04).

CONCLUSIONS

Our results suggest a role for CTGF in GBC progression and a positive association with better prognosis. In addition, they underscore the importance of considering the involvement of inflammation on GBC development.

Suppression of Wnt1-induced mammary tumor growth and lower serum insulin in offspring exposed to maternal blueberry diet suggest early dietary influence on developmental programming

Despite the well-accepted notion that early maternal influences persist beyond fetal life and may underlie many adult diseases, the risks imposed by the maternal environment on breast cancer development and underlying biological mechanisms remain poorly understood. In this study, we investigated whether early exposure to blueberry (BB) via maternal diet alters oncogene Wnt1-induced mammary tumorigenesis in offspring. Wnt1-transgenic female mice were exposed to maternal Casein (CAS, control) or blueberry-supplemented (CAS + 3%BB) diets throughout pregnancy and lactation. Offspring were weaned to CAS and mammary tumor development was followed until age 8 months. Tumor incidence and latency were similar for both groups; however, tumor weight at killing and tumor volume within 2 weeks of initial detection were lower (by 50 and 60%, respectively) in offspring of BB- versus control-fed dams. Dietary BB exposure beginning at weaning did not alter mammary tumor parameters. Tumors from maternal BB-exposed offspring showed higher tumor suppressor (Pten and Cdh1) and lower proproliferative (Ccnd1), anti-apoptotic (Bcl2) and proangiogenic (Figf, Flt1 and Ephb4) transcript levels, and displayed attenuated microvessel density. Expression of Pten and Cdh1 genes was also higher in mammary tissues of maternal BB-exposed offspring. Mammary tissues and tumors of maternal BB-exposed offspring showed increased chromatin-modifying enzyme Dnmt1 and Ezh2 transcript levels. Body weight, serum insulin and serum leptin/adiponectin ratio were lower for maternal BB-exposed than control tumor-bearing offspring. Tumor weights and serum insulin were positively correlated. Results suggest that dietary influences on the maternal environment contribute to key developmental programs in the mammary gland to modify breast cancer outcome in adult progeny.

MiR-26a enhances metastasis potential of lung cancer cells via AKT pathway by targeting PTEN

Lung cancer is the leading cause of cancer related death, 90% of lung cancer patients die of metastasis. Many microRNAs (miRNAs) are deregulated in cancer. They are involved in tumorigenesis and function as oncogenes or tumor suppressor genes. Recent studies show that miRNAs may be responsible for tumor metastasis. Several functional studies show that miR-26a plays an important role in carcinogenesis; however, none of these studies is related to tumor metastasis. In the present study, we investigated the effect of miR-26a on metastasis potential of lung cancer cells. Our data showed that miR-26a expression level was higher in lymph node metastasis tumor tissues than in primary tumor tissues. Ectopic expression of miR-26a dramatically enhanced lung cancer cell migration and invasion abilities. Metastasis-related genes matrix metallopeptidase 2 (MMP-2), vascular endothelial growth factor (VEGF), Twist and β-catenin were upregulated. Phosphatase and tensin homolog (PTEN) was a direct target of miR-26a. Further mechanistic study revealed that miR-26a increased AKT phosphorylation and nuclear factor kappa B (NFκB) transcriptional activation. Our study demonstrated that miR-26a enhanced lung cancer cell metastasis potential via modulation of metastasis-related gene expression, and activation of AKT pathway by PTEN suppression, suggesting that miR-26a might be a potential therapeutic candidate in patients with metastatic lung cancer.

Immunohistochemical study of Dicer and Drosha expression in the benign and malignant lesions of gallbladder and their clinicopathological significances

Dicer and Drosha are two key enzymes that are involved in the processing of miRNA production. Their expressions in gallbladder cancer have not been investigated. In this study, we studied Dicer and Drosha expression in 21 non-dysplastic gallbladder epithelia and 108 gallbladder adenocarcinomas by immunohistochemical staining. The clinicopathological significance of Dicer and Drosha expressions was analyzed. We demonstrated that the percent of positive Dicer or Drosha expression was significantly lower in gallbladder adenocarcinoma than that in non-dysplastic gallbladder epithelia (p<0.01). The percent of positive Dicer and Drosha expression was significantly lower in poorly differentiated adenocarcinoma with lymph node metastasis, invasiveness, and no resection than in well-differentiated adenocarcinoma without metastasis, invasiveness, and with radical resection (p<0.05 or p<0.01). Univariate Kaplan-Meier analysis showed that loss of Dicer and Drosha expression was associated with decreased overall survival (p<0.05 or p<0.01). Multivariate Cox regression analysis showed that loss of Dicer and Drosha expression was an independent poor-prognostic predictor in patients with gallbladder adenocarcinoma. In conclusion, loss of Dicer and Drosha expression is closely related to the metastasis, invasion, and poor-prognosis in gallbladder adenocarcinoma.