Zinc-finger protein 545 inhibits cell proliferation as a tumor suppressor through inducing apoptosis and is disrupted by promoter methylation in breast cancer

The diagnostic significance of the ZNF gene family in pancreatic cancer: a bioinformatics and experimental study

Background: Pancreatic adenocarcinoma (PAAD) is among the most devastating of all cancers with a poor survival rate. Therefore, we established a zinc finger (ZNF) protein-based prognostic prediction model for PAAD patients. Methods: The RNA-seq data for PAAD were downloaded from The Cancer Genome Atlas (TCGA) and the Gene Expression Omnibus (GEO) databases. Differentially expressed ZNF protein genes (DE-ZNFs) in PAAD and normal control tissues were screened using the "lemma" package in R. An optimal risk model and an independent prognostic value were established by univariate and multivariate Cox regression analyses. Survival analyses were performed to assess the prognostic ability of the model. Results: We constructed a ZNF family genes-related risk score model that is based on the 10 DE-ZNFs (ZNF185, PRKCI, RTP4, SERTAD2, DEF8, ZMAT1, SP110, U2AF1L4, CXXC1, and RMND5B). The risk score was found to be a significant independent prognostic factor for PAAD patients. Seven significantly differentially expressed immune cells were identified between the high- and low-risk patients. Then, based on the prognostic genes, we constructed a ceRNA regulatory network that includes 5 prognostic genes, 7 miRNAs and 35 lncRNAs. Expression analysis showed ZNF185, PRKCI and RTP4 were significantly upregulated, while ZMAT1 and CXXC1 were significantly downregulated in the PAAD samples in all TCGA - PAAD, GSE28735 and GSE15471 datasets. Moreover, the upregulation of RTP4, SERTAD2, and SP110 were verified by the cell experiments. Conclusion: We established and validated a novel, Zinc finger protein family - related prognostic risk model for patients with PAAD, that has the potential to inform patient management.

The role and application of transcriptional repressors in cancer treatment

Gene expression is modulated through the integration of many regulatory elements and their associated transcription factors (TFs). TFs bind to specific DNA sequences and either activate or repress transcriptional activity. Through decades of research, it has been established that aberrant expression or functional abnormalities of TFs can lead to uncontrolled cell division and the development of cancer. Initial studies on transcriptional regulation in cancer have focused on TFs as transcriptional activators. However, recent studies have demonstrated several different mechanisms of transcriptional repression in cancer, which could be potential therapeutic targets for the development of specific anti-cancer agents. In the first section of this review, "Emerging roles of transcriptional repressors in cancer development," we summarize the current understanding of transcriptional repressors and their involvement in the molecular processes of cancer progression. In the subsequent section, "Therapeutic applications," we provide an updated overview of the available therapeutic targets for drug discovery and discuss the new frontier of such applications.

Developing ZNF Gene Signatures Predicting Radiosensitivity of Patients with Breast Cancer

Adjuvant radiotherapy is one of the main treatment methods for breast cancer, but its clinical benefit depends largely on the characteristics of the patient. This study aimed to explore the relationship between the expression of zinc finger (ZNF) gene family proteins and the radiosensitivity of breast cancer patients. Clinical and gene expression data on a total of 976 breast cancer samples were obtained from The Cancer Genome Atlas (TCGA) database. ZNF gene expression was dichotomized into groups with a higher or lower level than the median level of expression. Univariate and multivariate Cox regression analyses were used to evaluate the relationship between ZNF gene expression levels and radiosensitivity. The Molecular Taxonomy Data of the International Federation of Breast Cancer (METABRIC) database was used for validation. The results revealed that 4 ZNF genes were possible radiosensitivity markers. High expression of ZNF644 and low expression levels of the other 3 genes (ZNF341, ZNF541, and ZNF653) were related to the radiosensitivity of breast cancer. Hierarchical cluster, Cox, and CoxBoost analysis based on these 4 ZNF genes indicated that patients with a favorable 4-gene signature had better overall survival on radiotherapy. Thus, this 4-gene signature may have value for selecting those patients most likely to benefit from radiotherapy. ZNF gene clusters could act as radiosensitivity signatures for breast cancer patients and may be involved in determining the radiosensitivity of cancer.

KRAB-ZFP Transcriptional Regulators Acting as Oncogenes and Tumor Suppressors: An Overview

Krüppel-associated box zinc finger proteins (KRAB-ZFPs) constitute the largest family of transcriptional factors exerting co-repressor functions in mammalian cells. In general, KRAB-ZFPs have a dual structure. They may bind to specific DNA sequences via zinc finger motifs and recruit a repressive complex through the KRAB domain. Such a complex mediates histone deacetylation, trimethylation of histone 3 at lysine 9 (H3K9me3), and subsequent heterochromatization. Nevertheless, apart from their repressive role, KRAB-ZFPs may also co-activate gene transcription, likely through interaction with other factors implicated in transcriptional control. KRAB-ZFPs play essential roles in various biological processes, including development, imprinting, retroelement silencing, and carcinogenesis. Cancer cells possess multiple genomic, epigenomic, and transcriptomic aberrations. A growing number of data indicates that the expression of many KRAB-ZFPs is altered in several tumor types, in which they may act as oncogenes or tumor suppressors. Hereby, we review the available literature describing the oncogenic and suppressive roles of various KRAB-ZFPs in cancer. We focused on their association with the clinicopathological features and treatment response, as well as their influence on the cancer cell phenotype. Moreover, we summarized the identified upstream and downstream molecular mechanisms that may govern the functioning of KRAB-ZFPs in a cancer setting.

ZNF471 modulates EMT and functions as methylation regulated tumor suppressor with diagnostic and prognostic significance in cervical cancer

Cervical cancer (CC) is a leading cause of cancer-related death among women in developing countries. However, the underlying mechanisms and molecular targets for therapy remain to be fully understood. We investigated the epigenetic regulation, biological functions, and clinical utility of zinc-finger protein 471 (ZNF471) in CC. Analysis of cervical tissues and five independent public datasets of CC showed significant hypermethylation of the ZNF471 gene promoter. In CC cell lines, promoter DNA methylation was inversely correlated with ZNF471 expression. The sensitivity and specificity of the ZNF471 hypermethylation for squamous intraepithelial lesion (SIL) vs tumor and normal vs tumor was above 85% with AUC of 0.937. High methylation and low ZNF471 expression predicted poor overall and recurrence-free survival. We identified -686 to +114 bp as ZNF471 promoter, regulated by methylation using transient transfection and luciferase assays. The promoter CpG site methylation of ZNF471 was significantly different among cancer types and tumor grades. Gal4-based heterologous luciferase reporter gene assays revealed that ZNF471 acts as a transcriptional repressor. The retroviral mediated overexpression of ZNF471 in SiHa and CaSki cells inhibited growth, proliferation, cell migration, invasion; delayed cell cycle progression in vitro by increasing cell doubling time; and reduced tumor growth in vivo in nude mice. ZNF471 overexpression inhibited key members of epithelial-mesenchymal transition (EMT), Wnt, and PI3K-AKT signaling pathways. ZNF471 inhibited EMT by directly targeting vimentin as analyzed by bioinformatic analysis, ChIP-PCR, and western blotting. Thus, ZNF471 CpG specific promoter methylation may determine the prognosis of CC and could function as a potential tumor suppressor by targeting EMT signaling.

Depression and stress levels increase risk of liver cancer through epigenetic downregulation of hypocretin

Recent studies suggest that Hypocretin (HCRT, Orexin) are involved in stress regulation of depression through the hypothalamic-pituitary-adrenal (HPA) axis. However, the molecular mechanism by which Hypocretin regulate neurobiological responses is unknown. Herein, the effects of chronic stress on the epigenetic modification of HCRT and its association with depression were explored with regard to a potential role in cancer progression. In the study, Sprague Dawley (SD) rats were used to establish an animal model of cancer with depression by administrating n-nitrosodiethylamine (DEN) and chronic unpredictable mild stress (CUMS). RNA-sequencing was used to detect differentially expressed genes in the hippocampus of rats and quantitative real-time polymerase chain reaction (qRT-PCR) was used to validate the results of RNA-sequencing. The status of HCRT promoter methylation was assessed by methylation specific polymerase chain reaction. Behavioral tests showed that rats exposed to CUMS had significant depressive-like behaviors. The number of liver tumors and tumor load in depressed rats exposed to CUMS was higher than in SD rats without CUMS. RNA-sequencing revealed that HCRT was one of the most siginificantly downregulated gene in the hippocampus of SD rats with CUMS compared to non-stressed group, which was validated by qRT-PCR. HCRT mRNA expression was downregulated and the promoter for HCRT was hyper-methylated in those with depression. These results identified a critical role for chronic psychological stressors in tumorigenesis and cancer progression, via epigenetic HCRT downregulation. Such epigenetic downregulation may be the molecular basis for the association of cancer with depression.

The tumor suppressor Zinc finger protein 471 suppresses breast cancer growth and metastasis through inhibiting AKT and Wnt/β-catenin signaling

Background

Zinc-finger protein 471 (ZNF471) is a member of the Krüppel-associated box domain zinc finger protein (KRAB-ZFP) family. ZNF471 is methylated in squamous cell carcinomas of tongue, stomach and esophageal. However, its role in breast carcinogenesis remains elusive. Here, we studied its expression, functions, and molecular mechanisms in breast cancer.

Methods

We examined ZNF471 expression by RT-PCR and qPCR. Methylation-specific PCR determined its promoter methylation. Its biological functions and related molecular mechanisms were assessed by CCK-8, clonogenicity, wound healing, Transwell, nude mice tumorigenicity, flow cytometry, BrdU-ELISA, immunohistochemistry and Western blot assays.

Results

ZNF471 was significantly downregulated in breast cell lines and tissues due to its promoter CpG methylation, compared with normal mammary epithelial cells and paired surgical-margin tissues. Ectopic expression of ZNF471 substantially inhibited breast tumor cell growth in vitro and in vivo, arrested cell cycle at S phase, and promoted cell apoptosis, as well as suppressed metastasis. Further knockdown of ZNF471 verified its tumor-suppressive effects. We also found that ZNF471 exerted its tumor-suppressive functions through suppressing epithelial-mesenchymal transition, tumor cell stemness and AKT and Wnt/β-catenin signaling.

Conclusions

ZNF471 functions as a tumor suppressor that was epigenetically inactivated in breast cancer. Its inhibition of AKT and Wnt/β-catenin signaling pathways is one of the mechanisms underlying its anti-cancer effects.

Function and mechanism exploration of zinc finger protein 64 in lung adenocarcinoma cell growth and metastasis

This paper aims to discover the effect of Zinc Finger Protein 64 (ZFP64) and Notch pathway on lung adenocarcinoma cell. ZFP64 expression in cancer tissue and overall survival analysis was identified by TCGA-LUAD. ZFP64 expressions in tumor tissue (n = 30) and adjacent tissue (n = 30), and in human nontumorigenic bronchial epithelial cell line BEAS-2B and human lung adenocarcinoma cell lines (H23, H1975, H2228, and H2085) were measured via quantitative real-time polymerase chain reaction (qRT-PCR). H1975 cell viability, cell cycle progression, and migration after transfection or under Notch inhibitor MK-0752 treatment were detected through MTT assay, flow cytometer, and wound healing assay, respectively. Expressions of notch intracellular domain (NICD) and hairy and enhancer of split 1 (Hes-1) in H1975 cell were determined by western blot. Epithelial-mesenchymal transition (EMT)-related proteins (E-Cadherin and Vimentin) expressions were identified through qRT-PCR and western blot. ZFP64 expression in lung adenocarcinoma tissue and lung adenocarcinoma cell lines was higher and related to poor prognosis. After transfection, H1975 cell viability, migration, and expressions of Vimentin, NICD and Hes-1 were upregulated yet cell percentage in G0/G1 phase, E-cadherin expression was downregulated by overexpressed ZFP64. However, Notch inhibitor MK-0752 inhibited the effects of overexpressed ZFP64 on H1975 cell viability, cell cycle, migration, EMT progress, and Notch pathway activation. Overexpressed ZFP64 promoted the development of lung adenocarcinoma cells by activating Notch pathway.

19q13 KRAB zinc-finger protein ZNF471 activates MAPK10/JNK3 signaling but is frequently silenced by promoter CpG methylation in esophageal cancer

Zinc-finger proteins (ZFPs) are the largest transcription factor family in mammals, involved in the regulation of multiple physiologic processes including cell differentiation, proliferation, apoptosis and neoplastic transformation. Approximately one-third of ZFPs are Krüppel-associated box domain (KRAB)-ZFPs.

Methods: ZNF471 expression and methylation were detected by reverse-transcription PCR and methylation-specific PCR. The impact and mechanism of ectopic ZNF471 expression in esophageal squamous cell carcinoma (ESCC) cells was evaluated in vitro and in vivo.

Results: We identified a 19q13 KRAB-ZFP, ZNF471, as a methylated target in ESCC. We further found that ZNF471 is significantly downregulated in ESCC tissues compared with adjacent non-cancer tissues, due to its aberrant promoter CpG methylation, and further confirmed by methylation analysis and treatment with demethylation agent. Restoration of ZNF471 expression in silenced ESCC cells significantly altered cell morphology, induced apoptosis and G0/G1 arrest, and inhibited tumor cell colony formation, viability, migration and invasion. Importantly, ZNF471 was found to activate the expression of MAPK10/JNK3 and PCDH family genes, and further enhance MAPK10 signaling and downstream gene expression through binding to the MAPK10/JNK3 promoter.

Conclusion: Our results demonstrate that ZNF471 is an important tumor suppressor and loss of ZNF471 functions hampers MAPK10/JNK3 signaling during esophageal carcinogenesis.

Methylation-regulated ZNF545 inhibits growth of the p53-mutant KYSE150 cell line by inducing p21 and Bax

The Krüppel-associated box zinc-finger protein 545 (ZNF545) was recently identified as a tumor suppressor in esophageal squamous cell carcinoma (ESCC). However, the role of ZNF545 in the tumorigenesis of esophageal cancer cells expressing loss-of-function mutant p53 has not been elucidated. In the present study, the role of ZNF545 in esophageal tumors and the p53-mutant ESCC cell line, KYSE150, was investigated. ZNF545 mRNA was significantly downregulated in tumors when compared with adjacent normal tissues. Methylated ZNF545 was detected in 76.6% of tumor tissues compared with 28.1% of adjacent normal tissues. Combined pharmacological treatment of KYSE150 cells with a demethylating reagent and deacetylase inhibitor restored the expression of ZNF545. Ectopic expression of ZNF545 activated p53 transcription and upregulated the protein expression levels of pivotal effectors p21 and Bax, which are associated with cell proliferation and apoptosis, respectively, in p53-mutant KYSE150 cells; while suppressing colony formation and inducing apoptosis. ZNF545 was therefore proposed as a potential tumor suppressor responsible for inhibiting the growth of p53-mutant ESCC cell lines. In addition, tumor-specific methylation of ZNF545 may represent an epigenetic diagnostic biomarker and a therapeutic target in patients with esophageal cancer.

ZFP57 suppress proliferation of breast cancer cells through down-regulation of MEST-mediated Wnt/β-catenin signalling pathway

Activation of oncogenes by promoter hypomethylation plays an important role in tumorigenesis. Zinc finger protein 57 (ZFP57), a member of KRAB-ZFPs, could maintain DNA methylation in embryonic stem cells (ESCs), although its role and underlying mechanisms in breast cancer are not well understood. In this study, we found that ZFP57 had low expression in breast cancer, and overexpression of ZFP57 could inhibit the proliferation of breast cancer cells by inhibiting the Wnt/β-catenin pathway. MEST was validated as the direct target gene of ZFP57 and MEST may be down-regulated by ZFP57 through conserving DNA methylation. Furthermore, overexpression of MEST could restore the tumour-suppressed and the Wnt/β-catenin pathway inactivated effects of ZFP57. ZFP57-MEST and the Wnt/β-catenin pathway axis are involved in breast tumorigenesis, which may represent a potential diagnostic biomarker, and provide a new insight into a novel therapeutic strategy for breast cancer patients.

The expression signature of cancer-associated KRAB-ZNF factors identified in TCGA pan-cancer transcriptomic data

The KRAB-ZNF (Krüppel-associated box domain zinc finger) gene family is composed of a large number of highly homologous genes, gene isoforms, and pseudogenes. The proteins encoded by these genes, whose expression is often tissue-specific, act as epigenetic suppressors contributing to the addition of repressive chromatin marks and DNA methylation. Due to its high complexity, the KRAB-ZNF family has not been studied in sufficient detail, and the involvement of its members in carcinogenesis remains mostly unexplored. In this study, we aimed to provide a comprehensive description of cancer-associated KRAB-ZNFs using publicly available The Cancer Genome Atlas pan-cancer datasets. We analyzed 6727 tumor and normal tissue samples from 16 cancer types. Here, we showed that a small but distinctive cluster of 16 KRAB-ZNFs is commonly upregulated across multiple cancer cohorts in comparison to normal samples. We confirmed these observations in the independent panels of lung and breast cancer cell lines and tissues. This upregulation was also observed for most of the KRAB-ZNF splicing variants, whose expression is simultaneously upregulated in tumors compared to normal tissues. Finally, by analyzing the clinicopathological data for breast and lung cancers, we demonstrated that the expression of cancer-associated KRAB-ZNFs correlates with patient survival, tumor histology, and molecular subtyping. Altogether, our study allowed the identification and characterization of KRAB-ZNF factors that may have an essential function in cancer biology and thus potential to become novel oncologic biomarkers and treatment targets.

The epigenetically downregulated factor CYGB suppresses breast cancer through inhibition of glucose metabolism

Background

Recent studies suggested the globin family member cytoglobin (CYGB) as a potential tumor suppressor; however, the mechanism by which CYGB suppresses cancer is elusive. We investigated the role and mechanism of CYGB in suppressing breast cancer.

Methods

CYGB expression was examined by reverse transcription PCR, quantitative reverse transcription PCR and open database analysis. Promoter methylation was examined by methylation-specific PCR. Metabolomics and proteomics were analyzed by gas chromatography-mass spectrometry and isobaric tags for relative and absolute quantitation, respectively. The effects and mechanisms of ectopic CYGB expression in breast cancer cells were assessed with molecular biological and cellular approaches in vitro and with a xenograft tumor model in nude mice.

Results

CYGB expression was downregulated in breast cancer tissues and cell lines, which was associated with promoter methylation. Ectopic CYGB expression suppressed proliferation, migration, invasion and induced apoptosis in breast cancer cell lines MCF7 (p53WT) and MB231 (p53mt) in vitro, and inhibited xenograft tumor growth in vivo. By proteomics and metabolomics analysis, glucose metabolism was found to be one of the main pathways suppressed by CYGB. The CYGB-expressing cells had lower ATP and compromised glycolysis. Additionally, CYGB suppressed key glucose metabolism factors including GLUT1 and HXK2 in p53-dependent and -independent manners. Restoration of GLUT1 or HXK2 expression attenuated CYGB-mediated proliferation suppression and apoptosis induction.

Conclusions

CYGB is a potential tumor suppressor in breast cancer that is epigenetically suppressed. The results for the first time suggest that CYGB suppresses breast cancer through inhibiting glucose metabolism, which could be exploited for breast cancer prevention and therapy.

Electronic supplementary material

The online version of this article (10.1186/s13046-018-0979-9) contains supplementary material, which is available to authorized users.

The 19q13 KRAB Zinc-finger protein ZFP82 suppresses the growth and invasion of esophageal carcinoma cells through inhibiting NF-κB transcription and inducing apoptosis

AIM

To study the epigenetic alternations and biological functions of ZFP82 in esophageal squamous cell carcinoma.

MATERIALS & METHODS

Analysis of ZFP82 expression was carried out by quantitative real-time PCR. Cell function was tested by MTS cell proliferation assay, transwell assay and flow cytometry. Gene mechanisms were studied by reverse transcription-PCR (RT-PCR), quantitative real-time PCR, luciferase reporter assay and Western blot.

RESULTS

ZFP82 promoter methylation was downregulated in esophageal squamous cell carcinoma. ZFP82 ectopic expression suppressed cell function and regulated NF-κB phosphorylation and genes involved in cell cycle arrest and apoptosis. Moreover, ZFP82 methylation was correlated with age, tumor stage and outcome.

CONCLUSION

ZFP82 is a tumor suppressor and is disrupted by promoter CpG methylation during esophageal carcinogenesis.

Protocadherin 17 functions as a tumor suppressor suppressing Wnt/β-catenin signaling and cell metastasis and is frequently methylated in breast cancer

Protocadherins play important roles in the regulation of cell adhesion and signaling transduction. Aberrant expression of protocadherins has been shown to be associated with multiple tumorigenesis. We previously identified PCDH17, encoding protocadherin 17, as a frequently methylated and downregulated tumor suppressor gene (TSG) in gastric and colorectal cancers. Here, we examined the abnormalities and functions of PCDH17 in breast cancer pathogenesis. We used PCR and immunohistochemistry to check its expression pattern in breast tumor cell lines and primary tumors. Methylation-specific PCR (MSP) was applied to examine its promoter methylation status in breast tumor cell lines and primary tumors. The biological functions of PCDH17 in breast tumor cells were assessed using in vitro and in vivo assays. We found that PCDH17 was frequently downregulated or silenced in 78% (7/9) of breast tumor cell lines, as well as 89% (32/36) of primary tumors. Downregulation of PCDH17 in breast cancer was mainly due to the methylation of its promoter. Ectopic expression of PCDH17 in breast tumor cells inhibited cell proliferation and mobility through arresting cell cycle and inducing apoptosis. In breast tumor cells, PCDH17 significantly suppressed the active β-catenin level and its downstream target gene expression. Thus, we found that PCDH17 functions as a tumor suppressor inhibiting Wnt/β-catenin signaling and metastasis in breast cancer but is frequently methylated in primary tumors which could be a potential biomarker.

Integrated Genomic Characterization of Pancreatic Ductal Adenocarcinoma

We performed integrated genomic, transcriptomic, and proteomic profiling of 150 pancreatic ductal adenocarcinoma (PDAC) specimens, including samples with characteristic low neoplastic cellularity. Deep whole-exome sequencing revealed recurrent somatic mutations in KRAS, TP53, CDKN2A, SMAD4, RNF43, ARID1A, TGFβR2, GNAS, RREB1, and PBRM1. KRAS wild-type tumors harbored alterations in other oncogenic drivers, including GNAS, BRAF, CTNNB1, and additional RAS pathway genes. A subset of tumors harbored multiple KRAS mutations, with some showing evidence of biallelic mutations. Protein profiling identified a favorable prognosis subset with low epithelial-mesenchymal transition and high MTOR pathway scores. Associations of non-coding RNAs with tumor-specific mRNA subtypes were also identified. Our integrated multi-platform analysis reveals a complex molecular landscape of PDAC and provides a roadmap for precision medicine.

Zinc finger protein 307 functions as a tumor‑suppressor and inhibits cell proliferation by inducing apoptosis in hepatocellular carcinoma

Zinc finger protein 307 (ZNF307) is a new Krüppel-associated box zinc-finger protein gene and a member of the zinc-finger family of transcriptional factors. Notably, the role of ZNF307 and its underlying mechanisms involved in hepatocarcinogenesis are poorly investigated. In the present study, we found that the expression of ZNF307 was significantly downregulated in hepatocellular carcinoma (HCC) tissues, compared with that in adjacent non-tumor tissues. In vitro studies further demonstrated that ectopic expression of ZNF307 in HCC cell lines Bel7402 and HCCLM3 significantly reduced cell proliferation, migration and invasive ability. Concordantly, knockdown of ZNF307 increased cell proliferation, migration and invasive ability of HCC cell lines MHCC97L and QGY7701. In vivo functional studies showed that upregulation of ZNF307 expression in Bel7402 cells led to a suppression of tumorigenicity in mice, while knockdown of ZNF307 in MHCC97L cells resulted in reverse. effects. Importantly, flow cytometric analysis showed that ZNF307 overexpression increased the incidence of apoptosis, while ZNF307 knockdown decreased the incidence of apoptosis. Consistently, key regulators in apoptosis, such as caspase-3, BAX and BCL-2 were also regulated by ZNF307. Therefore, our results indicate that ZNF307 may serve as a tumor suppressor and inhibits cell proliferation of HCC via inducing apoptosis.

Zinc-finger protein 545 is inactivated due to promoter methylation and functions as a tumor suppressor through the Wnt/β-catenin, PI3K/AKT and MAPK/ERK signaling pathways in colorectal cancer

The transcription factor, zinc-finger protein 545 (ZNF545), that belongs to the Kruppel-associated box zinc-finger protein (KRAB-ZFP) family, acts as a tumor suppressor and is inactivated by promoter methylation in cancers such as nasopharyngeal carcinoma, breast cancer, and gastric cancer, but its role in colorectal cancer (CRC) is unknown. The purpose of this study was to characterize the ZNF545 expression, methylation status, biological function, and related molecular mechanisms in CRC. The results showed that ZNF545 was expressed in adult normal colorectal tissues, but downregulated or silenced in CRC cell lines, and this mechanism was reversed by demethylation treatment with 5-aza-2′-deoxycytidine and trichostatin A. The results also showed that the expression of ZNF545 in primary CRC tissues was significantly downregulated compared to adjacent tissues (p<0.05). Overexpression of ZNF545 caused CRC cell cycle arrest and apoptosis, suppressed cell proliferation, and suppressed colony formation and migration in vitro, showing that ZNF545 can function as a tumor suppressor. This function was also shown in nude mice. Furthermore, Wnt/β-catenin, phosphatidylinositol 3 kinase/protein kinase B (PI3K/AKT), and mitogen-activated protein kinases/extracellular signal-regulated kinase (MAPK/ERK) signaling pathways participated in the regulation of ZNF545 in CRC cells. Together, the results suggested that ZNF545 functions as a tumor suppressor in CRC and is frequently inactivated by promoter methylation.

Dickkopf-related protein 2 induces G0/G1 arrest and apoptosis through suppressing Wnt/β-catenin signaling and is frequently methylated in breast cancer

Dickkopf-related protein 2 (DKK2) is one of the antagonists of Wnt/β-catenin signaling, with its downregulation reported in multiple cancers. However, how DKK2 contributes to breast tumorigenesis remains unclear. We examined its expression and promoter methylation in 10 breast tumor cell lines, 98 primary tumors, and 21 normal breast tissues. Compared with normal tissues, DKK2 was frequently silenced in breast cell lines (7/8). DKK2 promoter methylation was detected in 77.8% of cell lines and 86.7% of breast tumors; while rarely detected in normal breast tissues (19%), indicating common DKK2 methylation in breast cancer. Ectopic expression of DKK2 changed breast tumor cell morphology, inhibited cell proliferation and colony formation by inducing G0/G1 cell cycle arrest and apoptosis, and suppressed tumor cell migration by reversing epithelial-mesenchymal transition (EMT) and downregulating stem cell markers. Moreover, restored expression of DKK2 in MCF7 cells disrupted the microtube formation of human umbilical vein endothelial cells on Matrigel®. In vivo, the growth of MDA-MB-231 cells in nude mice was markedly decreased after stable expression of DKK2. DKK2 suppressed canonical Wnt/β-catenin signaling by inhibiting β-catenin activity with decreased active β-catenin protein. Thus, our findings demonstrate that DKK2 functions as a tumor suppressor through inhibiting cell proliferation and inducing apoptosis via regulating Wnt signaling during breast tumorigenesis.

ZNF545 suppresses human hepatocellular carcinoma growth by inhibiting NF-kB signaling

Hepatocellular carcinoma (HCC) is one of the most common cancers and the second leading cause of cancer related death worldwide. ZNF545 is located in the chromosome 19q13.13, which is frequent loss of heterozygosity in human astrocytoma. Methylation of ZNF545 was found frequently in a few kinds of cancers. While the function of ZNF545 in human HCC remains unclear. The purpose of this study is to explore the function and mechanism of ZNF545 in human HCC. Restoration of ZNF545 expression suppressed cell proliferation, migration and invasion, induced G1/S arrest and apoptosis in SNU449 and Huh7 cells. Further study suggested that ZNF545 suppressed HCC cell growth by inhibiting NF-kB signaling. These results were further validated by siRNA knocking down technique in ZNF545 highly expressed HXBF344 cells. In vivo, ZNF545 suppressed tumor growth in SNU449 cell xenograft mice. In conclusion, ZNF545 suppresses human HCC growth by inhibiting NF-kB signaling.

Low BIK outside-inside-out interactive inflammation immune-induced transcription-dependent apoptosis through FUT3-PMM2-SQSTM1-SFN-ZNF384

Eighteen different Pearson mutual-positive-correlation BIK-activatory molecular feedback upstream and downstream networks were constructed from 79 overlapping of 376 GRNInfer and 98 Pearson under BIK CC ≥ 0.25 in low normal adjacent tissues of Taiwan compared with high lung adenocarcinoma. Our identified BIK interactive total feedback molecular network showed FUT3 [fucosyltransferase 3 (galactoside 3(4)-L-fucosyltransferase Lewis blood group)], PMM2 (phosphomannomutase 2), SQSTM1 (sequestosome 1), SFN_2 [REX2 RNA exonuclease 2 homolog (S. cerevisiae)] and ZNF384 (zinc finger protein 384) in low normal adjacent tissues of lung adenocarcinoma. BIK interactive total feedback terms included mitochondrial envelope, endomembrane system, integral to membrane, Golgi apparatus, cytoplasm, nucleus, cytosol, intracellular signaling cascade, mitochondrion, extracellular space, inflammation, immune response, apoptosis, cell differentiation, cell cycle, regulation of cell cycle, cell proliferation, estrogen-responsive protein Efp controls cell cycle and breast tumors growth, induction or regulation of apoptosis based on integrative GO, KEGG, GenMAPP, BioCarta and disease databases in low normal adjacent tissues of lung adenocarcinoma. Therefore, we propose low BIK outside-inside-out interactive inflammation immune-induced transcription-dependent apoptosis through FUT3-PMM2-SQSTM1-SFN-ZNF384 in normal adjacent tissues of lung adenocarcinoma.

Epigenetic identification of ZNF545 as a functional tumor suppressor in multiple myeloma via activation of p53 signaling pathway

The KRAB-zinc-finger protein ZNF545 was recently identified as a potential suppressor gene in several tumors. However, the regulatory mechanisms of ZNF545 in tumorigenesis remain unclear. In this study, we investigated the expression and roles of ZNF545 in multiple myeloma (MM). ZNF545 was frequently downregulated in MM tissues compared with non-tumor bone marrow tissues. ZNF545 expression was silenced by promoter methylation in MM cell lines, and could be restored by demethylation treatment. ZNF545 methylation was detected in 28.3% of MM tissues, compared with 4.3% of normal bone marrow tissues. ZNF545 transcriptionally activated the p53 signaling pathway but had no effect on Akt in MM, whereas ectopic expression of ZNF545 in silenced cells suppressed their proliferation and induced apoptosis. We therefore identified ZNF545 as a novel tumor suppressor inhibiting tumor growth through activation of the p53 pathway in MM. Moreover, tumor-specific methylation of ZNF545 may represent an epigenetic biomarker for MM diagnosis, and a potential target for specific therapy.