PHF19 activates hedgehog signaling and promotes tumorigenesis in hepatocellular carcinoma.

Aberrant activation of Hedgehog-Gli1 signaling and accumulation of Gli1 in hepatocellular carcinoma (HCC) are frequently observed. However, the mechanisms leading to the overactivation of this signaling pathway are not fully understood. In this study, we show that the short isoform of PHD finger protein 19 (PHF19) interacts with ß-TrCP, the E3 ligase of Gli1, and that knocking down PHF19 promotes the ubiquitination of Gli1. In a biological function study, PHF19 was found to promote the growth of HCC cells both in liquid culture and in soft agar. Moreover, knocking out PHF19 in a HCC mouse model (MycF/F) using the hydrodynamic method inhibited tumorigenesis and improved survival. Taken together, these results demonstrate that PHF19 promotes the growth of HCC cells by activating the Hedgehog signaling pathway.

Downregulation of PHF19 inhibits cell growth and migration in gastric cancer.

Objectives: The PHD Finger Protein 19 (PHF19), as a sub-component of polycomb repressive complex 2 (PRC2), has been identified to be associated with various biological processes. Aberrant expression of PHF19 has implicated in several cancer types. This study aims to investigate its function and clinical significance in gastric cancer for the first time.Methods: The expression of PHF19 was evaluated by quantitative real-time PCR (qRT-PCR) and immunohistochemistry. PHF19 was silenced by small interference RNAs and lentiviral particles in gastric cancer cells. Then cell growth was measured by CCK-8 assays, colony formation and in a mouse model. Transwell and wound healing assays were performed to detect cell migration. Western blot analysis was used to explore the downstream signaling factors in PHF19-silenced cells, xenograft tumors and gastric cancer samples.Results: PHF19 was frequently upregulated in gastric cancer tissues compared with adjacent normal stomach tissues and this upregulation was correlated with tumor cell differentiation and poor outcome of gastric cancer patients. Functionally, the silencing of PHF19 in gastric cancer cells led to decreased cell growth and migration. Stable knockdown of PHF19 inhibited the tumorigenicity of gastric cancer cells in nude mice model. Western blot results demonstrated that phosphorylated AKT and ERK were reduced upon PHF19 downregulation, implying the two signaling pathways possibly mediate the oncogenic roles of PHF19.Conclusions: We identified PHF19 as an oncogene candidate and provided a new potential drug target for gastric cancer.

miR-211 sponges lncRNA MALAT1 to suppress tumor growth and progression through inhibiting PHF19 in ovarian carcinoma.

Accumulating evidence has indicated that microRNAs (miRNAs) play an important role in the occurrence and progression of ovarian cancer (OC). However, the function of miRNAs implicated in OC remains unclear. This study investigated the potential role of miR-211 in OC. Gene Expression Omnibus database analysis indicated that miR-211 expression was significantly down-regulated in OC tissues compared with normal specimens. In addition, miR-211 overexpression apparently inhibited proliferation, migration, xenograft growth, and induced apoptosis in HEY-T30 and SKOV3 cells. Moreover, PHF19, a component of the polycomb group of proteins, was found to be a direct target of miR-211 based on the luciferase reporter assay and Western blot analysis. Consistently, survival analysis indicated that high PHF19 expression was associated with shorter survival time in patients with OC. Importantly, silence of PHF19 reduced proliferation, induced cell cycle arrest, promoted apoptosis, suppressed migration, and inhibited xenograft growth in SKOV3 cells. Restoration of PHF19 expression markedly reversed the inhibitory effect of miR-211 on OC. Moreover, our results indicate that the long noncoding RNA MALAT1 could sponge miR-211 as a competing endogenous RNA and potentially up-regulate PHF19 expression, thus facilitating the OC progression. These findings suggest that the MALAT1/miR-211/PHF19 axis may act as a key mediator in OC and provide new insight into the prevention of this disease.-Tao, F., Tian, X., Ruan, S., Shen, M., Zhang, Z. miR-211 sponges lncRNA MALAT1 to suppress tumor growth and progression through inhibiting PHF19 in ovarian carcinoma.

microRNA-124a suppresses PHF19 over-expression, EZH2 hyper-activation, and aberrant cell proliferation in human glioma.

Enhancer of Zeste 2 (EZH2) is the key enzymatic factor in Polycomb Repressive Complex 2 (PRC2), a transcriptional repressor which contributes to oncogenesis. Recent research has revealed the key role of aberrant EZH2 hyper-activity in human gliomas. Here, we examined the role of the lesser-known PRC2-associated PHD Finger Protein 19 (PHF19) in human glioma. We found that PHF19 transcript and protein levels were significantly elevated in human glioma tumors, which was negatively associated with expression of the anti-PHF19 microRNA miR-124a. miR-124a over-expression in the A172 and U251MG glioma cell lines and patient glioma cells suppressed PHF19 expression, EZH2 activation, and cell proliferation. However, miR-124a did not suppress cell proliferation with PHF19 silencing or mutation. Knockdown of PHF19 suppressed EZH2 phosphorylation and proliferation of glioma cells. Co-immunoprecipitation confirmed that PHF19 forms the PRC2 with EZH2, EED, and SUZ12. In a nude murine model, subcutaneous and orthotopic xenograft tumor growth was significantly inhibited by miRNA-124a or PHF19 shRNA. In conclusion, miR-124a suppresses PHF19 over-expression, EZH2 hyper-activation, and aberrant glioma cell proliferation. Targeting PHF19 via miR-124a agomir therapy may block aberrant EZH2 hyper-activity in these tumors.

Tudor: a versatile family of histone methylation 'readers'.

The Tudor domain comprises a family of motifs that mediate protein-protein interactions required for various DNA-templated biological processes. Emerging evidence demonstrates a versatility of the Tudor family domains by identifying their specific interactions to a wide variety of histone methylation marks. Here, we discuss novel functions of a number of Tudor-containing proteins [including Jumonji domain-containing 2A (JMJD2A), p53-binding protein 1 (53BP1), SAGA-associated factor 29 (SGF29), Spindlin1, ubiquitin-like with PHD and RING finger domains 1 (UHRF1), PHD finger protein 1 (PHF1), PHD finger protein 19 (PHF19), and SAWADEE homeodomain homolog 1 (SHH1)] in 'reading' unique methylation events on histones in order to facilitate DNA damage repair or regulate transcription. This review covers our recent understanding of the molecular bases for histone-Tudor interactions and their biological outcomes. As deregulation of Tudor-containing proteins is associated with certain human disorders, pharmacological targeting of Tudor interactions could provide new avenues for therapeutic intervention.

Tissue-Specific Tumour Suppressor and Oncogenic Activities of the Polycomb-like Protein MTF2.

The Polycomb repressive complex 2 (PRC2) is a conserved chromatin-remodelling complex that catalyses the trimethylation of histone H3 lysine 27 (H3K27me3), a mark associated with gene silencing. PRC2 regulates chromatin structure and gene expression during organismal and tissue development and tissue homeostasis in the adult. PRC2 core subunits are associated with various accessory proteins that modulate its function and recruitment to target genes. The multimeric composition of accessory proteins results in two distinct variant complexes of PRC2, PRC2.1 and PRC2.2. Metal response element-binding transcription factor 2 (MTF2) is one of the Polycomb-like proteins (PCLs) that forms the PRC2.1 complex. MTF2 is highly conserved, and as an accessory subunit of PRC2, it has important roles in embryonic stem cell self-renewal and differentiation, development, and cancer progression. Here, we review the impact of MTF2 in PRC2 complex assembly, catalytic activity, and spatiotemporal function. The emerging paradoxical evidence suggesting that MTF2 has divergent roles as either a tumour suppressor or an oncogene in different tissues merits further investigations. Altogether, our review illuminates the context-dependent roles of MTF2 in Polycomb group (PcG) protein-mediated epigenetic regulation. Its impact on disease paves the way for a deeper understanding of epigenetic regulation and novel therapeutic strategies.

Polycomb-like Proteins in Gene Regulation and Cancer.

Polycomb-like proteins (PCLs) are a crucial group of proteins associated with the Polycomb repressive complex 2 (PRC2) and are responsible for setting up the PRC2.1 subcomplex. In the vertebrate system, three homologous PCLs exist: PHF1 (PCL1), MTF2 (PCL2), and PHF19 (PCL3). Although the PCLs share a similar domain composition, they differ significantly in their primary sequence. PCLs play a critical role in targeting PRC2.1 to its genomic targets and regulating the functionality of PRC2. However, they also have PRC2-independent functions. In addition to their physiological roles, their dysregulation has been associated with various human cancers. In this review, we summarize the current understanding of the molecular mechanisms of the PCLs and how alterations in their functionality contribute to cancer development. We particularly highlight the nonoverlapping and partially opposing roles of the three PCLs in human cancer. Our review provides important insights into the biological significance of the PCLs and their potential as therapeutic targets for cancer treatment.

High PHD Finger Protein 19 (PHF19) expression predicts poor prognosis in colorectal cancer: a retrospective study.

BACKGROUND: Colorectal cancer (CRC) is the third most common cancer all around the world, and it seriously threats human health. PHF19 has been proved to be closely related to the prognosis of patients in a variety of malignant tumors, but the effect of PHF19 on the prognosis evaluation of CRC patients has not been confirmed. METHODS: In our study, we used GEO, TCGA database and IHC to verify the PHF19 expression in CRC samples. Survival analysis of PHF19 based on TCGA, GEO series, and our own CRC sample were performed. Cox regression was performed to reveal the relationship between PHF19 and prognosis. Co-expression was performed to find genes related to PHF19 expression. GO/KEGG enrichment analysis and GSEA analysis were used to confirm the most relevant signal pathway to PHF19. Next, cell experiments were performed to verify the effect of PHF19 on the proliferation, invasion and metastasis of CRC. Then, Western blot was used to verify the protein expression of the above two phenotypes. Finally, tumor formation experiments in nude mice were used to verify the role of PHF19 of tumor proliferation in vivo. RESULTS: We found that PHF19 was significantly over-expressed in tumors compared with normal tissues. Kaplan-Meier (K-M) analysis indicated that high PHF19 in CRC associated with poor overall survival (OS) in CRC patients. Clinical correlation analysis showed that high expression of PHF19 was closely related to t umor progression in CRC patients, especially infiltration and metastasis. Bioinformatics revealed that PHF19 might affect tumor malignant phenotype by regulating the cell cycle in CRC. CCK-8 and clonal formation experiment showed that the proliferative ability of tumor cells was promoted. Flow cytometry showed that the cell cycle accelerated the transition from G1 to S phase. Western blot found that Cyclin D1, CDK4, and CDK6 expression were up-regulated. Transwell and wound-healing experiment found that invasive and migratory abilities was promoted after the over-expression of PHF19. Western blot showed that the expression of key proteins of Epithelial-Mesenchymal Transition (EMT) changed. Tumor formation experiments in nude mice showed that overexpression of PHF19 could promote tumor proliferation in vivo. CONCLUSION: Our research proved that PHF19 could be an independent prognostic factor for CRC, PHF19 promoted the proliferative ability and the invasion and metastasis of CRC by up-regulating the expression of key molecules related to cell cycle and EMT pathway in vitro, promoting tumor proliferation in vivo.

Polycomb Factor PHF19 Controls Cell Growth and Differentiation Toward Erythroid Pathway in Chronic Myeloid Leukemia Cells.

Polycomb group (PcG) of proteins are a group of highly conserved epigenetic regulators involved in many biological functions, such as embryonic development, cell proliferation, and adult stem cell determination. PHD finger protein 19 (PHF19) is an associated factor of Polycomb repressor complex 2 (PRC2), often upregulated in human cancers. In particular, myeloid leukemia cell lines show increased levels of PHF19, yet little is known about its function. Here, we have characterized the role of PHF19 in myeloid leukemia cells. We demonstrated that PHF19 depletion decreases cell proliferation and promotes chronic myeloid leukemia (CML) differentiation. Mechanistically, we have shown how PHF19 regulates the proliferation of CML through a direct regulation of the cell cycle inhibitor p21. Furthermore, we observed that MTF2, a PHF19 homolog, partially compensates for PHF19 depletion in a subset of target genes, instructing specific erythroid differentiation. Taken together, our results show that PHF19 is a key transcriptional regulator for cell fate determination and could be a potential therapeutic target for myeloid leukemia treatment.

PHD Finger Protein 19 Promotes Cardiac Hypertrophy via Epigenetically Regulating SIRT2.

Epigenetic regulations essentially participate in the development of cardiomyocyte hypertrophy. PHD finger protein 19 (PHF19) is a polycomb protein that controls H3K36me3 and H3K27me3. However, the roles of PHF19 in cardiac hypertrophy remain unknown. Here in this work, we observed that PHF19 promoted cardiac hypertrophy via epigenetically targeting SIRT2. In angiotensin II (Ang II)-induced cardiomyocyte hypertrophy, adenovirus-mediated knockdown of Phf19 reduced the increase in cardiomyocyte size, repressed the expression of hypertrophic marker genes Anp and Bnp, as well as inhibited protein synthesis. By contrast, Phf19 overexpression promoted Ang II-induced cardiomyocyte hypertrophy in vitro. We also knocked down Phf19 expression in mouse hearts in vivo. The results demonstrated that Phf19 knockdown reduced Ang II-induced decline in cardiac fraction shortening and ejection fraction. Phf19 knockdown also inhibited Ang II-mediated increase in heart weight, reduced cardiomyocyte size, and repressed the expression of hypertrophic marker genes in mouse hearts. Further mechanism studies showed that PHF19 suppressed the expression of SIRT2, which contributed to the function of PHF19 during cardiomyocyte hypertrophy. PHF19 bound the promoter of SIRT2 and regulated the balance between H3K27me3 and H3K36me3 to repress the expression of SIRT2 in vitro and in vivo. In human hypertrophic hearts, the overexpression of PHF19 and downregulation of SIRT2 were observed. Of importance, PHF19 expression was positively correlated with hypertrophic marker genes ANP and BNP but negatively correlated with SIRT2 in human hypertrophic hearts. Therefore, our findings demonstrated that PHF19 promoted the development of cardiac hypertrophy via epigenetically regulating SIRT2.

Insights into high-risk multiple myeloma from an analysis of the role of PHF19 in cancer.

Despite  improvements in outcome, 15-25% of newly diagnosed multiple myeloma (MM) patients have treatment resistant high-risk (HR) disease with a poor survival. The lack of a genetic basis for HR has focused attention on the role played by epigenetic changes. Aberrant expression and somatic mutations affecting genes involved in the regulation of tri-methylation of the lysine (K) 27 on histone 3 H3 (H3K27me3) are common in cancer. H3K27me3 is catalyzed by EZH2, the catalytic subunit of the Polycomb Repressive Complex 2 (PRC2). The deregulation of H3K27me3 has been shown to be involved in oncogenic transformation and tumor progression in a variety of hematological malignancies including MM. Recently we have shown that aberrant overexpression of the PRC2 subunit PHD Finger Protein 19 (PHF19) is the most significant overall contributor to HR status further focusing attention on the role played by epigenetic change in MM. By modulating both the PRC2/EZH2 catalytic activity and recruitment, PHF19 regulates the expression of key genes involved in cell growth and differentiation. Here we review the expression, regulation and function of PHF19 both in normal and the pathological contexts of solid cancers and MM. We present evidence that strongly implicates PHF19 in the regulation of genes important in cell cycle and the genetic stability of MM cells making it highly relevant to HR MM behavior. A detailed understanding of the normal and pathological functions of PHF19 will allow us to design therapeutic strategies able to target aggressive subsets of MM.

Comprehensive Pan-Cancer Genomic Analysis Reveals PHF19 as a Carcinogenic Indicator Related to Immune Infiltration and Prognosis of Hepatocellular Carcinoma.

Background: As a crucial constituent part of Polycomb repressive complex 2, PHD finger protein 19 (PHF19) plays a pivotal role in epigenetic regulation, and acts as a critical regulator of multiple pathophysiological processes. However, the exact roles of PHF19 in cancers remain enigmatic. The present research was primarily designed to provide the prognostic landscape visualizations of PHF19 in cancers, and study the correlations between PHF19 expression and immune infiltration characteristics in tumor microenvironment. Methods: Raw data in regard to PHF19 expression were extracted from TCGA and GEO data portals. We examined the expression patterns, prognostic values, mutation landscapes, and protein-protein interaction network of PHF19 in pan-cancer utilizing multiple databases, and investigated the relationship of PHF19 expression with immune infiltrates across TCGA-sequenced cancers. The R language was used to conduct KEGG and GO enrichment analyses. Besides, we built a risk-score model of hepatocellular carcinoma (HCC) and validated its prognostic classification efficiency. Results: On balance, PHF19 expression was significantly higher in cancers in comparison with that in noncancerous samples. Increased expression of PHF19 was detrimental to the clinical prognoses of cancer patients, especially HCC. There were significant correlations between PHF19 expression and TMB or MSI in several cancers. High PHF19 levels were critically associated with the infiltration of myeloid-derived suppressor cells (MDSCs) and Th2 subsets of CD4+ T cells in most cancers. Enrichment analyses revealed that PHF19 participated in regulating carcinogenic processes including cell cycle and DNA replication, and was correlated with the progression of HCC. Intriguingly, GSEA suggested that PHF19 was correlated with the cellular components including immunoglobulin complex and T cell receptor complex in HCC. Based on PHF19-associated functional gene sets, an eleven-gene prognostic signature was constructed to predict HCC prognosis. Finally, we validated pan-cancer PHF19 expression, and its impacts on immune infiltrates in HCC. Conclusion: The epigenetic related regulator PHF19 participates in the carcinogenic progression of multiple cancers, and may contribute to the immune infiltration in tumor microenvironment. Our study suggests that PHF19 can serve as a carcinogenic indicator related to prognosis in pan-cancer, especially HCC, and shed new light on therapeutics of cancers for clinicians.

ZNF750 exerted its Antitumor Action in Oral Squamous Cell Carcinoma by regulating E2F2.

Cell cycle activator E2F transcription factor 2 (E2F2) play a key role in tumor development and metastasis. Previous RNA sequence analysis (GSE134835) revealed E2F2 was significantly reduced by Zinc-finger protein 750 (ZNF750) in oral squamous cell carcinoma (OSCC). This study was aimed to determine the involvement of E2F2 in antitumor action of ZNF750. The nude mouse xenograft model was established by subcutaneously injection of stable cell line CAL-27oeZNF750 or CAL-27shZNF750. Xenograft tumor volume and tumor weight was measured. The expression of E2F2, transcriptional repressors such as enhancer of zeste 2 (Ezh2), PHD finger protein 19 (PHF19), and the genes related to cell proliferation or metastasis was studied in vivo or in vitro. Luciferase assay was performed to investigate regulation effect of ZNF750 on E2F2 luciferase activity. The involvement of E2F2 in the antitumor action of ZNF750 was studied by cotransduced ZNF750 with E2F2 lentivirus. The tumor growth and metastasis was repressed by ZNF750 manifested by reduced tumor size, tumor weight and the genes related to cell proliferation and metastasis. However, all of these were reversed by knockdown of the ZNF750 gene. Furthermore, E2F2 luciferase activity was inhibited by ZNF750. E2F2 partly blocked the antitumor action of ZNF750 manifested by increased self-renewal, invasion, migration, elevated Ezh2 and MMP13 protein expression in ZNF750 + E2F2 groups. However, silenced E2F2 further enhanced the antitumor action of ZNF750. ZNF750 depressed E2F2 activity and played a critical role in regulating transcriptional repressors for inhibiting the OSCC growth and metastasis in OSCC.

PHF19 mediated regulation of proliferation and invasiveness in prostate cancer cells.

The Polycomb-like protein PHF19/PCL3 associates with PRC2 and mediates its recruitment to chromatin in embryonic stem cells. PHF19 is also overexpressed in many cancers. However, neither PHF19 targets nor misregulated pathways involving PHF19 are known. Here, we investigate the role of PHF19 in prostate cancer cells. We find that PHF19 interacts with PRC2 and binds to PRC2 targets on chromatin. PHF19 target genes are involved in proliferation, differentiation, angiogenesis, and extracellular matrix organization. Depletion of PHF19 triggers an increase in MTF2/PCL2 chromatin recruitment, with a genome-wide gain in PRC2 occupancy and H3K27me3 deposition. Transcriptome analysis shows that PHF19 loss promotes deregulation of key genes involved in growth, metastasis, invasion, and of factors that stimulate blood vessels formation. Consistent with this, PHF19 silencing reduces cell proliferation, while promotes invasive growth and angiogenesis. Our findings reveal a role for PHF19 in controlling the balance between cell proliferation and invasiveness in prostate cancer.

PHD Finger Protein 19 Enhances the Resistance of Ovarian Cancer Cells to Compound Fuling Granule by Protecting Cell Growth, Invasion, Migration, and Stemness.

Ovarian cancer is one of the most common gynecological malignancies in women worldwide with a poor survival rate. We have previously reported that compound fuling granule (CFG), a traditional Chinese medicinal preparation used to treat ovarian cancer in China for over 20 years, significantly promotes cell cycle arrest, apoptosis, senescence, TGFß-induced invasion and migration, tumor growth, and distant metastasis in ovarian cancer cells. However, the underlying mechanisms are not clear. In the present study, we found that PHF19 expression in ovarian cancer cells positively correlated with their resistance ability to CFG. In addition, PHF19 overexpression increased the resistance of HEY-T30 and SKOV3 cells to CFG, while knockdown of PHF19 enhanced their sensitivity to CFG. Moreover, CFG significantly inhibited the expression of PHF19 both in mRNA and protein levels in these cells. Gain of function and loss of function experiments further proved that PHF19 is a crucial mediator involved in the ovarian cancer progression, including cell proliferation, invasion, migration, and stemness. Importantly, rescue the expression of PHF19 reverted CFG-induced suppression in ovarian cancer cell growth, EMT and stemness, while PHF19 knockdown accelerated CFG's anti-tumor effect. Overall, our results provide a series of evidence to reveal that PHF19 is critical suppressor for CFG's anti-tumor effect in ovarian cancer.

hPCL3S promotes proliferation and migration of androgen-independent prostate cancer cells.

Polycomb repressive complex 2 (PRC2) allows the deposition of H3K27me3. PRC2 facultative subunits modulate its activity and recruitment such as hPCL3/PHF19, a human ortholog of Drosophila Polycomb-like protein (PCL). These proteins contain a TUDOR domain binding H3K36me3, two PHD domains and a "Winged-helix" domain involved in GC-rich DNA binding. The human PCL3 locus encodes the full-length hPCL3L protein and a shorter isoform, hPCL3S containing the TUDOR and PHD1 domains only. In this study, we demonstrated by RT-qPCR analyses of 25 prostate tumors that hPCL3S is frequently up-regulated. In addition, hPCL3S is overexpressed in the androgen-independent DU145 and PC3 cells, but not in the androgen-dependent LNCaP cells. hPCL3S knockdown decreased the proliferation and migration of DU145 and PC3 whereas its forced expression into LNCaP increased these properties. A mutant hPCL3S unable to bind H3K36me3 (TUDOR-W50A) increased proliferation and migration of LNCaP similarly to wt hPCL3S whereas inactivation of its PHD1 domain decreased proliferation. These effects partially relied on the up-regulation of genes known to be important for the proliferation and/or migration of prostate cancer cells such as S100A16, PlexinA2, and Spondin1. Collectively, our results suggest hPCL3S as a new potential therapeutic target in castration resistant prostate cancers.

Transcription factor Phf19 positively regulates germinal center reactions that underlies its role in rheumatoid arthritis.

The Polycomb Repressive Complex 2 (PRC2) component PHD Finger Protein 19 (phf19) gene has been identified to be associated with rheumatoid arthritis (RA) risk. Here we show that Phf19 is highly expressed in murine germinal centers (GCs) and RA patients. To investigate the function of Phf19 in lymphocytes, we generated RAG1-deficient mice reconstituted with Phf19 or control-vector transduced bone marrow (BM) cells. Lymphogenesis in primary lymphoid tissues of Phf19-RM is normal, however, Phf19-RM form enlarged GCs and generate more antibody-secreting cells (ASCs). Overexpression of Phf19 promotes proliferation and survival of GC B cells and Tfh cells in vivo. The uncovered Phf19-dependent targets include the genes encoding cyclin D2, the prosurvival factor Bcl-xL and CD40-CD40 ligand axis, their regulation by Phf19 could partially elucidate the advantages observed in Phf19-overexpressing GCs. Our results underscore an unrecognized but critical function for Phf19 in GCs formation and antibody generation, and implicate the potential role of Phf19 in RA pathogenesis.