The dark side of ZNF217, a key regulator of tumorigenesis with powerful biomarker value

The recently described oncogene ZNF217 belongs to a chromosomal region that is frequently amplified in human cancers. Recent findings have revealed that alternative mechanisms such as epigenetic regulation also govern the expression of the encoded ZNF217 protein. Newly discovered molecular functions of ZNF217 indicate that it orchestrates complex intracellular circuits as a new key regulator of tumorigenesis. In this review, we focus on recent research on ZNF217-driven molecular functions in human cancers, revisiting major hallmarks of cancer and highlighting the downstream molecular targets and signaling pathways of ZNF217. We also discuss the exciting translational medicine investigating ZNF217 expression levels as a new powerful biomarker, and ZNF217 as a candidate target for future anti-cancer therapies.     

Prognostic and therapeutic impact of the chromosome 20q13.2 ZNF217 locus amplification in ovarian clear cell carcinoma

BACKGROUND:

The goal of this study was to examine the clinical significance of ZNF217 amplification and assess whether ZNF217 could be a potential therapeutic target in ovarian clear cell carcinoma (OCCC).

METHODS:

ZNF217 expression and amplification in OCCC was assessed by immunohistochemistry, fluorescence in situ hybridization, and clinical data collected via a retrospective chart review. ZNF217 gene knockdown using silencing RNA (siRNA) was used to assess ZNF217 functions in OCCC cell lines.

RESULTS:

Gene amplification was identified in 12 of 60 (20.0%) OCCCs. ZNF217 copy number correlated significantly with ZNF217 protein expression (r = 0.341; P<.01). ZNF217 amplification correlated significantly with shorter progression‐free (P = .0042) and overall (P = .0199) survival. There were nonsignificant trends between high ZNF217 protein expression and poor progression‐free (P = .2594) and overall (P = .2199) survival. Multivariate analysis revealed ZNF217 gene amplification to be an independent prognostic factor for progression‐free and overall survival after standard platinum agent‐based chemotherapy (P = .0339 and P = .031, respectively). Profound growth inhibition and apoptosis were observed in ZNF217 siRNA‐treated cancer cells with gene amplification compared with cancer cells with ZNF217 moderate expression without ZNF217 gene amplification or with low ZNF217 expression.

CONCLUSION:

These findings indicate that ZNF217 overexpression is critical to growth and survival of OCCCs with ZNF217 gene amplification. Furthermore, they suggest that ZNF217 siRNA‐induced phenotypes depend on amplification status of OCCCs. Therefore, ZNF217‐targeted therapy may benefit OCCC patients with ZNF217 amplification. Cancer 2011. © 2011 American Cancer Society.     

Identification of ZNF217, hnRNP‐K,VEGF‐A and IPO7 as targets for microRNAs that are downregulated in prostate carcinoma

In primary prostate cancer (PCa), a major cause of cancer‐related death in men, the expression of various microRNAs (miRNAs) is deregulated. We previously detected several miRNAs, for example, miR‐24 and miR‐22, as significantly downregulated in PCa (Szczyrba et al., Mol Cancer Res 2010;8:529‐38). An in silico search predicted that zinc finger protein 217 (ZNF217) and importin 7 (IPO7) were potential target genes of these miRNAs. Additionally, for two genes that are deregulated in PCa (heterogeneous nuclear ribonucleoprotein K, hnRNP‐K, and vascular endothelial growth factor A, VEGF‐A), we identified two regulatory miRNAs, miR‐205 and miR‐29b. The regulation of the 3′‐untranslated regions of the four genes by their respective miRNAs was confirmed by luciferase assays. As expected, the upregulation of ZNF217, hnRNP‐K, VEGF‐A and IPO7 could be verified at the protein level in the PCa cell lines LNCaP and DU145. ZNF217 and IPO7, which had not yet been studied in PCa, were analyzed in more detail. ZNF217 mRNA is overexpressed in primary PCa samples, and this overexpression translates to an elevated protein level. However, IPO7 was upregulated at the protein level alone. The inhibition of ZNF217 and IPO7 by siRNA resulted in reduced proliferation of the PCa cell lines. ZNF217 could thus be identified as an oncogene that is overexpressed in PCa and affects the growth of PCa cell lines, whereas the function of IPO7 remains to be elucidated in greater detail.     

ZNF217 is Overexpressed and Enhances Cell Migration and Invasion in Colorectal Carcinoma

Background: To investigate the expression and clinical significance of zinc finger protein 217 (ZNF217)in human colorectal carcinoma (CRC). Materials and Methods: The expression of ZNF217 in 60 CRCtissues and matched tumor adjacent tissues, collected between January 2013 and June 2014, was assessedimmunohistochemically. The relationship between the expression of ZNF217 and clinicopathlogical features wasanalyzed by Pearson chi-square test. In addition, siRNA was used to down-regulate the expression of ZNF217 inCRC cells. The effects of ZNF217 for cell migration and invasion were measured by wound healing assay andtranswell assay, respectively. Results: The expression level of ZNF217 was significantly higher in CRC tissuesthan in tumor adjacent tissues (p<0.05), positively correlating with tumor size, lymphatic metastasis and advancedTNM stage (p<0.05). Down-regulation of ZNF217 in CRC cells could significantly suppress cell migration andinvasion. Conclusions: ZNF217 is overexpressed in colorectal carcinoma tissues and is associated with tumormalignant clinicopathological features. ZNF217 may promote CRC progression by inducing cell migration andinvasion.     

Understanding the roles of N6-methyladenosine writers,readers and erasers in breast cancer

Breast cancer is believed to be driven by epigenetic regulation of genes implicated in cell proliferation, survival, and differentiation. Recently, aberrant N⁶-methyladenosine (m⁶A) decorations turned up as crucial epigenetic regulator for malignant breast cancer, which may serve as new targets for breast cancer treatment. Here we briefly outline the functions of m⁶A and its regulatory proteins, including m⁶A “writers,” “readers,” and “erasers” on RNA life fate, recapitulate the latest breakthroughs in understanding m⁶A modification and its regulatory proteins, and the underlying molecular mechanisms that contribute to the carcinogenesis and the progression of breast cancer, so as to provide potential epigenetic targets for diagnosis, treatment and prognosis in breast cancer.     

Research progress concerning m6A methylation and cancer

N6-methyladenosine (m⁶A) methylation is a type of methylation modification on RNA molecules, which was first discovered in 1974, and has become a hot topic in life science in recent years. m⁶A modification is an epigenetic regulation similar to DNA and histone modification and is dynamically reversible in mammalian cells. This chemical marker of RNA is produced by m⁶A ‘writers’ (methylase) and can be degraded by m⁶A ‘erasers’ (demethylase). Methylated reading protein is the ‘reader’, that can recognize the mRNA containing m⁶A and regulate the expression of downstream genes accordingly. m⁶A methylation is involved in all stages of the RNA life cycle, including RNA processing, nuclear export, translation and regulation of RNA degradation, indicating that m⁶A plays a crucial role in RNA metabolism. Recent studies have shown that m⁶A modification is a complicated regulatory network in different cell lines, tissues and spatio-temporal models, and m⁶A methylation is associated with the occurrence and development of tumors. The present review describes the regulatory mechanism and physiological functions of m⁶A methylation, and its research progress in several types of human tumor, to provide novel approaches for early diagnosis and targeted treatment of cancer.     

Downregulation of miR‐217 correlates with resistance of ph+ leukemia cells to ABL tyrosine kinase inhibitors

This study found that long‐term exposure of chronic myelogenous leukemia (CML) K562 cells to BCR/ABL thyrosine kinase inhibitors (TKI) caused drug‐resistance in association with an increase in levels of DNA methyltransferases (DNMT) and a decrease in levels of microRNA miR‐217. These observations are clinically relevant; an increase in levels of DNMT3A in association with downregulation of miR‐217 were noted in leukemia cells isolated from individuals with BCR/ABL TKI‐resistant Philadelphia chromosome positive acute lymphoblastic leukemia (Ph⁺ ALL) and CML. Further studies with TKI‐resistant K562 cells found that forced expression of miR‐217 inhibited expression of DNMT3A through a miR‐217‐binding site within the 3′‐untranslated region of DNMT3A and sensitized these cells to growth inhibition mediated by the TKI. Of note, long‐term exposure of K562 cells to dasatinib (10 nM) together with 5‐Aza‐2′‐deoxycytidine (5‐AzadC) (0.1 μM) potently inhibited proliferation of these cells in association with upregulation of miR‐217 and downregulation of DNMT3A in vitro. In addition, a decrease in levels of DNMT3A and an increase in levels of miR‐217 were noted in K562 tumors growing in immune‐deficient mice that were treated with the combination of 5‐AzadC and dasatinib. Taken together, Ph⁺ leukemia cells acquire TKI resistance via downregulation of miR‐217 and upregulation of DNMT3A. Inhibition of DNMT3A by forced expression of miR‐217 or 5‐AzadC may be useful to prevent drug resistance in individuals who receive TKI.     

Multi-colour FISH in oesophageal adenocarcinoma—predictors of prognosis independent of stage and grade

Background:

Oesophageal adenocarcinoma or Barrett''s adenocarcinoma (EAC) is increasing in incidence and stratification of prognosis might improve disease management. Multi-colour Fluorescence in situ hybridisation (FISH) investigating ERBB2, MYC, CDKN2A and ZNF217 has recently shown promising results for the diagnosis of dysplasia and cancer using cytological samples.

Methods:

To identify markers of prognosis we targeted four selected gene loci using multi-colour FISH applied to a tissue microarray containing 130 EAC samples. Prognostic predictors (P1, P2, P3) based on genomic copy numbers of the four loci were statistically assessed to stratify patients according to overall survival in combination with clinical data.

Results:

The best stratification into favourable and unfavourable prognoses was shown by P1, percentage of cells with less than two ZNF217 signals; P2, percentage of cells with fewer ERBB2- than ZNF217 signals; and P3, overall ratio of ERBB2-/ZNF217 signals. Median survival times for P1 were 32 vs 73 months, 28 vs 73 months for P2; and 27 vs 65 months for P3. Regarding each tumour grade P2 subdivided patients into distinct prognostic groups independently within each grade, with different median survival times of at least 35 months.

Conclusions:

Cell signal number of the ERBB2 and ZNF217 loci showed independence from tumour stage and differentiation grade. The prognostic value of multi-colour FISH-assays is applicable to EAC and is superior to single markers.     

N6-methyladenosine (m6A) RNA modification in tumor immunity

Growing evidence supports that cancer progression is closely associated with the tumor microenvironment and immune evasion. Importantly, recent studies have revealed the crucial roles of epigenetic regulators in shaping the tumor microenvironment and restoring immune recognition. N⁶-methyladenosine (m⁶A) modification, the most prevalent epigenetic modification of mammalian mRNAs, has essential functions in regulating the processing and metabolism of its targeted RNAs, and therefore affects various biological processes including tumorigenesis and progression. Recent studies have demonstrated the critical functions and molecular mechanisms underlying abnormal m⁶A modification in the regulation of tumor immunity. In this review, we summarize recent research progress in the potential roles of m⁶A modification in tumor immunoregulation, with a special focus on the anti-tumor processes of immune cells and involvement in immune-associated molecules and pathways. Furthermore, we review current knowledge regarding the close correlation between m⁶A-related risk signatures and the tumor immune microenvironment landscape, and we discuss the prognostic value and therapeutic efficacy of m⁶A regulators in a variety of cancer types.     

microRNA-217 inhibits tumor progression and metastasis by downregulating EZH2 and predicts favorable prognosis in gastric cancer

microRNA-217 (miR-217) is frequently dysregulated in cancer. Here, we report that miR-217 levels were lower in tumor tissue compared with the adjacent normal tissue. Low levels of miR-217 were associated with aggressive tumor phenotypes and poor overall survival in gastric cancer patients. The ectopic expression of miR-217 inhibited cell proliferation, migration and invasion in vitro and tumor growth and metastasis in vivo, whereas knockdown of endogenous miR-217 increased cell proliferation and invasion. Further experiments revealed that Polycomb group protein enhancer of zeste homolog 2 (EZH2) was a direct target of miR-217 in gastric cancer cells. Knockdown of EZH2 mimicked the tumor-suppressive effects of miR-217 in gastric cancer cells, whereas the reintroduction of EZH2 abolished its effects. Taken together, these results demonstrated that miR-217 may be used as a prognostic marker, and the newly identified miR-217-EZH2 axis may be a potential target in the development of therapeutic strategies for gastric cancer patients.     

Gene-specific fluorescence in-situ hybridization analysis on tissue microarray to refine the region of chromosome 20q amplification in melanoma

Several comparative genomic hybridization studies provide evidence for overrepresentation of the long arm of chromosome 20 in malignant melanoma. These studies also suggest that chromosome 20q contains genes that may contribute to melanoma pathogenesis. To refine the region of 20q amplification and to identify potential candidate genes involved in melanoma or even in melanoma progression from these regions, we combined fluorescence in-situ hybridization with MYBL2, ZNF217, CYP24 and STK6 specific probes (chromosomal region 20q13.1-q13.2) with high-throughput tissue microarray consisting of 280 primary melanomas and melanoma metastases. Low-level amplification ranging from 0.5 to 2.0% was detected for the tumor-related genes of interest. Higher frequencies of gain when compared with amplification were detected for MYBL2, ZNF217, CYP24 and STK6. Aneusomy of centromere 20 was observed in 29.9% of the analyzed tumors. A significantly higher frequency of ZNF217, CYP24 and STK6 total copy-number increase, as well as aneusomy of centromere 20, was found in the group of metastases when compared with the group of primary melanomas. Despite the technological advantage of fluorescence in-situ hybridization on tissue microarray, which allows refining regions of amplification, we were not able to recognize any of the MYBL2, ZNF217, CYP24 and STK6 genes as a particular relevant gene for melanoma tumorigenesis.     

Decreased RNA m6A methylation enhances the process of the epithelial mesenchymal transition and vasculogenic mimicry in glioblastoma

RNA N⁶-methyladenosine (m⁶A) modification is gradually thought to be an active participant in the considerable biological processes of glioblastoma (GB), providing us with a novel insight for exploring this disease. However, the role of RNA m⁶A modification during the epithelial mesenchymal transition (EMT) or vasculogenic mimicry (VM) progression has not been investigated in GB. Here we performed a research to validate the impact exerted by AlkB homolog 5 (ALKBH5), one of “erasers” for RNA m⁶A and methyltransferase-like 3 (METTL3) which adds m⁶A modification to the RNAs on the progression of EMT and VM in GB. In this study, we demonstrate that the m⁶A levels of RNAs were reduced in GB cells and glioma tissues. Patients with high mRNA expression of ALKBH5 acquired relatively shorter median overall survival (OS) time, while patients with relatively high expression of MEETL3 prolonged their disease free survival. ALKBH5 enhanced GB cell proliferation and influenced cell cycle in vitro. Decreased RNA m⁶A methylation enhanced the progression of the EMT and VM in glioblastoma cells. ALKBH5 strengthened glioblastoma growth and enhanced the EMT and VM process of glioblastoma in vivo. Our study uncovers that RNA m⁶A methylation suppresses the process of EMT and VM in glioblastoma, providing a new perspective to seek for a potential therapeutic target for GB.     

99mTc-MIBI SPECT compared with201TI SPECT for the detection of breast cancer and lymph node metastasis

A comparative study of²⁰¹Tl and^99mTc-methoxy-2 isobutyl isonitrile (^99mTc-MIBI) was performed in 39 breast tumors.²⁰¹Tl scintigraphy was carried out in 24 breast tumors and^99mTc-MIBI scintigraphy in 15. The sensitivity of²⁰¹Tl for malignant tumors was 100% (22/22), but specificity was 0% (0/2). On^99mTc-MIBI scintigraphy, the sensitivity for malignant tumors was 83.3% (10/l2) and specificity was 100% (3/3).^99mTc-MIBI might be more useful for the diagnosis of breast tumors, because the tumor/background ratio of^99mTc-MIBI was significantly higher than that of²⁰¹T1. In addition,²⁰¹Tl scintigraphy and^99mTc-MIBI scintigraphy showed the same degree of accuracy (93.3%) in detecting lymph node metastasis. Moreover, when either ultrasonography (US) with²⁰¹Tl or^99mTc-MIBI scintigraphy was positive for lymph node metastasis, the accuracy of detection became 94.4%. The combined use of ultrasonography and scintigraphy might improve the accuracy of diagnosis of lymph node metastasis.     

ZNF217 confers resistance to the pro-apoptotic signals of paclitaxel and aberrant expression of Aurora-A in breast cancer cells

Background  

ZNF217 is a candidate oncogene located at 20q13, a chromosomal region frequently amplified in breast cancers. The precise mechanisms involved in ZNF217 pro-survival function are currently unknown, and utmost importance is given to deciphering the role of ZNF217 in cancer therapy response.