Ring1 And YY1 Binding Protein Research Articles

Glucose-induced RYBP suppresses tumor cell aerobic glycolysis and migration

RYBP (Ring 1 and YY1 binding protein) has been frequently reported to play an important role during body development, stem cell differentiation, apoptosis and tumorigenesis, but whether RYBP carries out additional functions remains mysterious. Here, we demonstrated that RYBP protein levels elevate with increasing glucose concentration in cell culture medium in human tumorigenic cell lines, but an opposite trend was observed in non-tumorigenic cells. Mechanistic exploration disclosed that glucose inhibits polyubiquitination and proteasomal degradation, leading to RYBP stabilization in tumor cells. Further study showed that RYBP inhibits the glycolysis of tumor cells, as both extracellular acidification rate (ECAR) and lactate production increase when RYBP is knocked down, and decrease when RYBP is over-expressed, and this effect is unrelated to the glucose uptake ability of tumor cells. The functional study showed that RYBP is involved in the regulation of glucose on tumor cell migration. Compared to low glucose culture and their wildtypes, high glucose significantly enhanced tumor cell migration in RYBP knockdown or knockout tumor cells. Taken together, our current study uncovered a previously unknown function of RYBP in tumor metabolism, and this finding will enhance the exploration of the interplay between RYBP and nutrients during tumor cell metabolic reprogramming.

RYBP contributes to improved prognosis in colorectal cancer via regulation of cell cycle, apoptosis and oxaliplatin sensitivity.

Ring1 and YY‑1 binding protein (RYBP) is a member of the polycomb repressive complex 1 and serves as a transcriptional suppressor via epigenetic modification. RYBP has a tumour‑suppressive role in solid tumours, but its function in colorectal cancer (CRC) remains unknown. The present study evaluated the expression of RYBP using immunohistochemistry in 140cases of primary CRC and 11patient‑matched cases of liver metastases. Using CRC cell lines with different TP53 gene status such as HCT116 (TP53wt/wt), HCT116 (TP53‑/‑), SW48 and DLD‑1 cells, proliferation, cell cycle progression and apoptosis, as well as the effect of RYBP on oxaliplatin sensitivity, were assessed. Clinical data showed that low RYBP expression was significantly associated with risk of distant metastasis and recurrence, and patients with high RYBP expression demonstrated significantly better cancer‑specific and disease‑free survival. Invitro experiments revealed that RYBP suppressed cell proliferation by inducing cell cycle arrest and apoptosis in TP53 wild‑type cells. In addition, endogenous RYBP overexpression enhanced sensitivity to oxaliplatin. Therefore, RYBP may contribute to improved prognosis in CRC by regulating the cell cycle, apoptosis and oxaliplatin sensitivity via the p53‑mediated pathway.

The intrinsically disordered, epigenetic factor RYBP binds to the citrullinating enzyme PADI4 in cancer cells

RYBP (Ring1 and YY 1 binding protein) is a multifunctional, intrinsically disordered protein (IDP), best described as a transcriptional regulator. It exhibits a ubiquitin-binding functionality, binds to other transcription factors, and has a key role during embryonic development. RYBP, which folds upon binding to DNA, has a Zn-finger domain at its N-terminal region. By contrast, PADI4 is a well-folded protein and it is one the human isoforms of a family of enzymes implicated in the conversion of arginine to citrulline. As both proteins intervene in signaling pathways related to cancer development and are found in the same localizations within the cell, we hypothesized they may interact. We observed their association in the nucleus and cytosol in several cancer cell lines, by using immunofluorescence (IF) and proximity ligation assays (PLAs). Binding also occurred in vitro, as measured by isothermal titration calorimetry (ITC) and fluorescence, with a low micromolar affinity (~1 μM). AlphaFold2-multimer (AF2) results indicate that PADI4's catalytic domain interacts with the Arg53 of RYBP docking into its active site. As RYBP sensitizes cells to PARP (Poly (ADP-ribose) polymerase) inhibitors, we applied them in combination with an enzymatic inhibitor of PADI4 observing a change in cell proliferation, and the hampering of the interaction of both proteins. This study unveils for the first time the possible citrullination of an IDP, and suggests that this new interaction, whether it involves or not citrullination of RYBP, might have implications in cancer development and progression.

Polycomb protein RYBP activates transcription factor Plagl1 during in vitro cardiac differentiation of mouse embryonic stem cells.

RING1 and YY1 binding protein (RYBP) is primarily known to function as a repressor being a core component of the non-canonical polycomb repressive complexes 1 (ncPRC1s). However, several ncPRC1-independent functions of RYBP have also been described. We previously reported that RYBP is essential for mouse embryonic development and that Rybp null mutant embryonic stem cells cannot form contractile cardiomyocytes (CMCs) in vitro. We also showed that PLAGL1, a cardiac transcription factor, which is often mutated in congenital heart diseases (CHDs), is not expressed in Rybp-null mutant CMCs. However, the underlying mechanism of how RYBP regulates Plagl1 expression was not revealed. Here, we demonstrate that RYBP cooperated with NKX2-5 to transcriptionally activate the P1 and P3 promoters of the Plagl1 gene and that this activation is ncPRC1-independent. We also show that two non-coding RNAs residing in the Plagl1 locus can also regulate the Plagl1 promoters. Finally, PLAGL1 was able to activate Tnnt2, a gene important for contractility of CMCs in transfected HEK293 cells. Our study shows that the activation of Plagl1 by RYBP is important for sarcomere development and contractility, and suggests that RYBP, via its regulatory functions, may contribute to the development of CHDs.

RYBP Sensitizes Cancer Cells to PARP Inhibitors by Regulating ATM Activity.

Ring1 and YY1 Binding Protein (RYBP) is a member of the non-canonical polycomb repressive complex 1 (PRC1), and like other PRC1 members, it is best described as a transcriptional regulator. Previously, we showed that RYBP, along with other PRC1 members, is also involved in the DNA damage response. RYBP inhibits recruitment of breast cancer gene 1(BRCA1) complex to DNA damage sites through its binding to K63-linked ubiquitin chains. In addition, ataxia telangiectasia mutated (ATM) kinase serves as an important sensor kinase in early stages of DNA damage response. Here, we report that overexpression of RYBP results in inhibition in both ATM activity and recruitment to DNA damage sites. Cells expressing RYBP show less phosphorylation of the ATM substrate, Chk2, after DNA damage. Due to its ability to inhibit ATM activity, we find that RYBP sensitizes cancer cells to poly-ADP-ribose polymerase (PARP) inhibitors. Although we find a synergistic effect between PARP inhibitor and ATM inhibitor in cancer cells, this synergy is lost in cells expressing RYBP. We also show that overexpression of RYBP hinders cancer cell migration through, at least in part, ATM inhibition. We provide new mechanism(s) by which RYBP expression may sensitize cancer cells to DNA damaging agents and inhibits cancer metastasis.

RYBP regulates Pax6 during in vitro neural differentiation of mouse embryonic stem cells

We have previously reported that RING1 and YY1 binding protein (RYBP) is important for central nervous system development in mice and that Rybp null mutant (Rybp−/−) mouse embryonic stem (ES) cells form more progenitors and less terminally differentiated neural cells than the wild type cells in vitro. Accelerated progenitor formation coincided with a high level of Pax6 expression in the Rybp−/− neural cultures. Since Pax6 is a retinoic acid (RA) inducible gene, we have analyzed whether altered RA signaling contributes to the accelerated progenitor formation and impaired differentiation ability of the Rybp−/− cells. Results suggested that elevated Pax6 expression was driven by the increased activity of the RA signaling pathway in the Rybp−/− neural cultures. RYBP was able to repress Pax6 through its P1 promoter. The repression was further attenuated when RING1, a core member of ncPRC1s was also present. According to this, RYBP and PAX6 were rarely localized in the same wild type cells during in vitro neural differentiation. These results suggest polycomb dependent regulation of Pax6 by RYBP during in vitro neural differentiation. Our results thus provide novel insights on the dynamic regulation of Pax6 and RA signaling by RYBP during mouse neural development.

Re-expression of circ_0043610 contributes to trophoblast dysfunction through the miR-558/RYBP pathway in preeclampsia.

An increasing number of data have shown the pathogenesis of preeclampsia (PE) involves circular RNA (circRNA). The study aims to investigate the function and the potential mechanism of circ_0043610 in PE. The study was performed on two human placental trophoblastic cell lines (JEG-3 and HTR-8/SVneo). The expression of circ_0043610, microRNA-558 (miR-558), and RING1 and YY1 binding protein (RYBP) was detected by quantitative real-time polymerase chain reaction. The protein levels of N-cadherin, E-cadherin, and RYBP were assessed by Western blotting. Cell viability, proliferation, apoptosis, invasion, and migration were evaluated by cell counting kit-8, 5-Ethynyl-29-deoxyuridine, flow cytometry analysis, transwell invasion assay, and wound-healing assay, respectively. Dual-luciferase reporter assay, RNA immunoprecipitation assay, and RNA pull-down assay were performed to identify the associations among circ_0043610, miR-558, and RYBP. Compared with normal placental controls, the increased expression of circ_0043610 and RYBP and the decreased miR-558 expression were detected in PE placental tissues. The overexpression of circ_0043610 led to decreased trophoblast cell proliferation, invasion, and migration but increased cell apoptosis. Mechanistically, circ_0043610 acted as a miR-558 sponge, and miR-558 bound to RYBP. Besides, miR-558 introduction remitted circ_0043610-mediated effects in JEG-3 and HTR-8/SVneo cells. Moreover, RYBP participated in the regulation of miR-558 on trophoblast cell behaviors. Further, the ectopic expression of circ_0043610 led to RYBP upregulation through miR-558. Circ_0043610 induced RYBP production to promote trophoblast dysfunction by binding to miR-558 in PE.

The transcribed ultraconserved region uc.160+ enhances processing and A-to-I editing of the miR-376 cluster: hypermethylation improves glioma prognosis.

Transcribed ultraconserved regions (T‐UCRs) are noncoding RNAs derived from DNA sequences that are entirely conserved across species. Their expression is altered in many tumor types, and, although a role for T‐UCRs as regulators of gene expression has been proposed, their functions remain largely unknown. Herein, we describe the epigenetic silencing of the uc.160+ T‐UCR in gliomas and mechanistically define a novel RNA–RNA regulatory network in which uc.160+ modulates the biogenesis of several members of the miR‐376 cluster. This includes the positive regulation of primary microRNA (pri‐miRNA) cleavage and an enhanced A‐to‐I editing on its mature sequence. As a consequence, the expression of uc.160+ affects the downstream, miR‐376‐regulated genes, including the transcriptional coregulators RING1 and YY1‐binding protein (RYBP) and forkhead box P2 (FOXP2). Finally, we elucidate the clinical impact of our findings, showing that hypermethylation of the uc.160+ CpG island is an independent prognostic factor associated with better overall survival in lower‐grade gliomas, highlighting the importance of T‐UCRs in cancer pathophysiology.

A preliminary investigation into the immune cell landscape of schistosome-associated liver fibrosis in humans.

Schistosomiasis is a widespread helminth disease that poses a heavy social and economic burden on people worldwide. Advanced schistosomiasis often develops into schistosome‐associated liver fibrosis, the pathogenesis of which remains unclear. This study aimed preliminarily to profile immune cells of schistosome‐associated liver fibrosis using single‐cell RNA sequencing. Three patient groups were enrolled, including an Schistosomiasis japonicum (SJ) group (n = 1), a chronic liver failure (CLF) group (n = 3) and a healthy control (HC) group (n = 2), revealing 17 cell clusters out of 20 093 cells. From these limited datasets, it was observed that T cell(1), mononuclear phagocytes‐1 and dendritic cells (DCs) were higher in the SJ group. CAVIN2+ MP(2) was the predominant cell type in the MP subset of the SJ group (53%), and was higher than that in both the CLF (8%) and HC (1%) groups. Kupffer cell marker genes (CD163, MARCO and TIMD4) were enriched in caveolae‐associated protein 2 (CAVIN2)+ MP(2), which was also an important source of TGFB1. The KEGG pathways of CAVIN2 + MP(2) indicated that they were associated with lysosome, endocytosis, phagosome and antigen processing and presentation. The preliminary study showed that granzyme B (GZMB)+ T cell(1) and ankyrin repeat domain‐containing protein 36B+ T cell(3) were the most common T cells in the SJ group (50% and 32%, respectively). The KEGG pathways of GZMB + T cell(1) were mainly related to natural killer cell‐mediated cytotoxicity. The percentage of ring1 and YY1 binding protein (RYBP)+ DC(1) was higher in the SJ group (57%) than in the CLF (16%) and HC (6%) groups. The KEGG pathway of RYBP + DC(1) was related to Fc gamma R‐mediated phagocytosis and antigen processing and presentation. Overall, CAVIN2 + Kupffer cells were the main source of TGFB1, consisting primarily of mononuclear phagocytes in the livers of the SJ group subjects and potentially playing an irreplaceable role in hepatic fibrosis of schistosomiasis.

Knockdown of miR-125b-5p inhibits the proliferation and invasion of gastric carcinoma cells by targeting RYBP.

Gastric carcinoma, one of the most aggressive and lethal human malignancies, is associated with poor prognosis despite progress in therapeutic strategies. This study examined the potential function and mechanism of action of microRNA-125b-5p (miR-125b-5p) in the pathogenesis of gastric carcinoma. We recognized that miR-125b-5p was elevated in gastric carcinoma, and its decreased expression was associated with a better prognosis. Loss-of-function assays showed that miR-125b-5p suppression inhibited the proliferative and invasive abilities of gastric cancer cells. Furthermore, RING1 and YY1-binding protein (RYBP) was found to be target gene for miR-125b-5p action; miR-125b-5p negatively regulates RYBP expression. According to the results of rescue experiments, RYBP downregulation partially counteracted the miR-125b-5p silence-mediated inhibitory function in gastric cancer progression. Collectively, these data elucidated the molecular mechanisms of the miR-125b-5p/RYBP axis in gastric cancer invasion and growth.

The nuclear localization sequence of the epigenetic factor RYBP binds to human importin α3

RYBP (Ring1 and YY1 binding protein, UniProt ID: Q8N488) is an epigenetic factor with a key role during embryonic development; it does also show an apoptotic function and an ubiquitin binding activity. RYBP is an intrinsically disordered protein (IDP), with a Zn-finger domain at its N-terminal region, which folds upon binding to DNA. It is predicted that RYBP has a nuclear localization sequence (NLS), comprising residues Asn58 to Lys83, to allow for nuclear translocation. We studied in this work the ability of intact RYBP to bind Impα3 and its truncated species, ΔImpα3, without the importin binding domain (IBB), by using fluorescence and circular dichroism (CD). Furthermore, the binding of the peptide matching the isolated NLS region of RYBP (NLS-RYBP) was also studied using the same methods and isothermal titration calorimetry (ITC), and in silico molecular docking. Moreover, we carried out experiments with NLS-RYBP in the absence or in the presence of NaCl (140 mM). Our results show that RYBP interacted with Impα3 and ΔImpα3, causing protein precipitation. The NLS-RYBP also interacted with both importin species (dissociation constant in the low micromolar range), at low or high ionic strength, as shown by intrinsic fluorescence and ITC. These findings indicate that the NLS region, which was mainly unfolded in isolation in solution, was essentially responsible for the binding of RYBP to each of the importin species. Furthermore, the molecular simulations predict that the anchoring of NLS-RYBP takes place in the major binding site for the NLS of cargo proteins bound to Impα3. Taken together, our findings pinpoint the theoretical predictions of the NLS region in RYBP and, more importantly, suggest that this IDP relies on an importin for its nuclear translocation.

Upregulated miR‑411‑5p levels promote lymph node metastasis by targeting RYBP in head and neck squamous cell carcinoma.

Metastasis is the primary cause of the high mortality rates in head and neck squamous cell carcinoma (HNSCC). MicroRNA (miR)-411-5p has been discovered to serve an important role in cancer metastases. However, to the best of our knowledge, the association between miR-411-5p expression levels and HNSCC metastasis has not been thoroughly investigated. The present study aimed to research the function of miR-411-5p in HNSCC metastasis. The results of the present study revealed that miR-411-5p expression levels were upregulated in patients with HNSCC with lymph node metastasis and the upregulated expression levels of miR-411-5p were positively associated with the metastatic potential of HNSCC. Moreover, miR-411-5p promoted HNSCC cell migration, invasion and epithelial-mesenchymal transition (EMT). The results of the dual-luciferase reporter assays identified RING1 and YY1 binding protein (RYBP) as a functional downstream target gene for miR-411-5p. Therefore, whether miR-411-5p downregulated the expression levels of RYBP in HNSCC cells was subsequently investigated. Notably, the silencing of RYBP expression restored the stimulatory effects of miR-411-5p on HNSCC cell migration, invasion and EMT. In addition, the mRNA expression levels of miR-411-5p and RYBP were found to be inversely correlated in HNSCC samples. In conclusion, the results of the present study indicated that the miR-411-5p-mediated downregulation of RYBP expression levels may exert an important role in HNSCC metastasis and may provide a novel target for the treatment of HNSCC.

MiR-769-5p functions as an oncogene by down-regulating RYBP expression in gastric cancer.

The purpose of this study was to detect the relative expression level of micro-ribonucleic acid (miR)-769-5p in gastric cancer (GC) tissues and cells, and to investigate the clinical significance, biological function, and mechanism of miR-769-5p in GC. The relative expression level in 62 cases of GC tissues and paracancerous tissues was detected by quantitative Real Time-Polymerase Chain Reaction (qRT-PCR). The correlation between miR-769-5p expression and clinicopathological characteristics of GC patients was analyzed by Chi-square test. Besides, the relative expression level of miR-769-5p in GC cells and the interference efficiency of si-miR-769-5p were detected by qRT-PCR, and the biological function of miR-769-5p was studied by in vitro experiments [Thiazolyl Blue Tetrazolium Bromide (MTT), flow cytometry, 5-ethynyl-2'-deoxyuridine (EdU)]. Next, the effect of miR-769-5p on the tumorigenicity of GC cells in vivo was investigated by nude mouse tumorigenicity assay. Moreover, the downstream target genes of miR-769-5p were predicted by bioinformatics. Finally, qRT-PCR and Western blotting were used to screen the downstream target genes. In the 62 cases of GC tissues, the expression of miR-769-5p was upregulated in 48 cases. MiR-769-5p was divided into high-expression group and low-expression group. Chi-square analysis showed that the high expression of miR-769-5p was positively correlated with tumor-node-metastasis (TNM) stage (p=0.005), lymph node metastasis (p=0.010), and infiltration depth (p=0.011) in patients with GC. The results of qRT-PCR indicated that the expression of miR-769-5p was upregulated in GC cells. In vitro experiments (MTT, flow cytometry, EdU) results showed that after interfering in the expression of miR-769-5p, the proliferation ability of GC cells was decreased, and apoptosis was increased. Furthermore, the results of in vivo experiments manifested that the tumorigenic ability of GC cells declined after interference in the expression of miR-769-5p. Finally, the results of qRT-PCR and Western blotting revealed that the expression of RING1 and YY1-binding protein (RYBP) was regulated by miR-769-5p. The expression of miR-769-5p is upregulated in GC and positively correlated with TNM stage in GC patients. By regulating the expression of RYBP, the proliferation of GC cells was promoted, and the apoptosis was inhibited.

Evolving Role of RING1 and YY1 Binding Protein in the Regulation of Germ-Cell-Specific Transcription.

Separation of germline cells from somatic lineages is one of the earliest decisions of embryogenesis. Genes expressed in germline cells include apoptotic and meiotic factors, which are not transcribed in the soma normally, but a number of testis-specific genes are active in numerous cancer types. During germ cell development, germ-cell-specific genes can be regulated by specific transcription factors, retinoic acid signaling and multimeric protein complexes. Non-canonical polycomb repressive complexes, like ncPRC1.6, play a critical role in the regulation of the activity of germ-cell-specific genes. RING1 and YY1 binding protein (RYBP) is one of the core members of the ncPRC1.6. Surprisingly, the role of Rybp in germ cell differentiation has not been defined yet. This review is focusing on the possible role of Rybp in this process. By analyzing whole-genome transcriptome alterations of the Rybp-/- embryonic stem (ES) cells and correlating this data with experimentally identified binding sites of ncPRC1.6 subunits and retinoic acid receptors in ES cells, we propose a model how germ-cell-specific transcription can be governed by an RYBP centered regulatory network, underlining the possible role of RYBP in germ cell differentiation and tumorigenesis.

Generation of Rybp homozygous knockout murine ES cell line GIBHe001-A-1 by using CRISPR/Cas9 technology.

RYBP (Ring1 and YY1 Binding Protein) is critical for pluripotency and differentiation of embryonic stem cells (ESCs). RYBP depletion disturbs both neural and myocardial differentiation of ESCs. Moreover, low level of RYBP is correlated with diseases such as glioblastoma. To study the biological function of RYBP in neural differentiation of ESCs, here we generated Rybp homozygous knockout murine ESC line based on Sox1-GFP reporter using CRISPR/Cas9 genome editing technology. The last two exons of Rybp gene in which contain 115 amino acids have been replaced with PGK-Pruo by homologous recombination.

MicroRNA-769-5p contributes to the proliferation, migration and invasion of hepatocellular carcinoma cells by attenuating RYBP

Hepatocellular carcinoma (HCC) is the commonest primary liver cancer with highly aggressive features. MicroRNAs (miRNAs) are demonstrated to play important roles in the tumorigenesis and progression of HCC. miR-769-5p is a recently identified cancer-associated miRNA. But, the expression level of miR-769-5p and its function in HCC are unexplored. In this study, we found that miR-769-5p expression was obviously increased in HCC samples compared to adjacent noncancerous liver tissues. Additionally, we revealed that miR-769-5p was over-expressed in HCC cells as compared with LO2 cells. Notably, HCC tissues from patients with tumor size ≥5 cm, venous infiltration and advanced tumor stages showed higher levels of miR-769-5p compared to those from corresponding controls. Interestingly, our data indicated that HCC patients highly expressing miR-769-5p had significant shorter survivals. Next, functional experiments verified that miR-769-5p knockdown markedly suppressed HCC cell proliferation, migration and invasion. Conversely, ectopic expression of miR-769-5p promoted these biological behaviors of Hep3B cells. Furthermore, depletion of miR-769-5p repressed the growth and metastasis of HCCLM3 cells in vivo. Importantly, miR-769-5p inversely modulated RING1 and YY1 binding protein (RYBP) by directly binding to 3’ untranslated region (UTR) in HCC cells. The expression of RYBP mRNA was down-regulated in HCC tissues and negatively correlated with miR-769-5p level. RYBP overexpression remarkably inhibited the proliferation, migration and invasion of HCCLM3 cells. Accordingly, knockdown of RYBP partially abolished miR-769-5p silencing-induced tumor suppressive effects on HCCLM3 cells. In summary, our study revealed the up-regulated expression of miR-769-5p, which contributed to HCC progression possibly by targeting RYBP.

ETS1 targets RYBP transcription to inhibit tumor cell proliferation

ETS1 (E26 transformation specific-1) is the founding member of ETS transcriptional factor family. It transcriptionally modulates numerous gene expressions, and is involved in cellular differentiation, tissue remodeling, angiogenesis, drug resistance and tumorigenesis. ETS1 is usually regarded as an oncogene. However, its apoptosis-inducing activity was also frequently reported. Here, we identified RYBP (Ring1 and YY1 binding protein), a critical epigenetic regulator and apoptosis enhancer, as a novel transcriptional target of ETS1. Specifically, we found that overexpression of ETS1 up-regulates the promoter activity of RYBP in HEK293T and tumor cells from different tissue origins, indicating a universal transcriptional regulatory effect. Subsequently, both overexpression and RNA interfering experiments demonstrated that ETS1 positively modulates RYBP expression from both mRNA and protein levels. Bioinformatics analysis combined with site-directed mutagenesis suggested that there probably exist a multiple of ETS1 binding sites in RYBP promoter region, and chromatin immunoprecipitation assay validates the physical association between ETS1 protein and RYBP promoter region. Functional studies showed that ectopic expression of ETS1 significantly suppresses tumor cell proliferation. However, this inhibitory effect was partially compromised when RYBP was concomitantly knocked down by its specific short hairpin RNA. Meanwhile, we provide evidence to demonstrate that cyclin-dependent kinase inhibitor p21 is possibly involved in this regulatory loop. Taken together, our current study identified RYBP as a new transcriptional target which is utilized by ETS1 to carry out its tumor cell growth inhibitory effect.

Overexpression of RYBP inhibits proliferation, invasion, and chemoresistance to cisplatin in anaplastic thyroid cancer cells via the EGFR pathway.

Ring1 and YY1 binding protein (RYBP), a new member of the polycomb group protein family, has been reported to play an important role in various biological processes. Recently, more and more studies have demonstrated an implication of RYBP in cancer development. However, the specific role of RYBP in anaplastic thyroid cancer (ATC) remains unknown. In this study, we investigated for the first time the expression pattern and biological functions of RYBP in ATC. We showed that RYBP was lowly expressed in ATC tissues and cell lines. We also found that overexpression of RYBP inhibited ATC cell proliferation, invasion, and cisplatin resistance. Furthermore, we observed that upregulation of RYBP decreased the phosphorylation of EGFR and ERK1/2 in ATC cells. Taken together, our data indicated that RYBP might be considered as a promising therapeutic target for the treatment of ATC.

Multiple roles of Ring 1 and YY1 binding protein in physiology and disease.

Ring 1 and YY1 binding protein (RYBP) was first identified in 1999, and its structure includes a conserved Npl4 Zinc finger motif at the N‐terminus, a central region that is characteristically enriched with arginine and lysine residues and a C‐terminal region enriched with serine and threonine amino acids. Over nearly 20 years, multiple studies have found that RYBP functions as an organ developmental adaptor. There is also evidence that RYBP regulates the expression of different genes involved in various aspects of biological processes, via a mechanism that is dependent on interactions with components of PcG complexes and/or through binding to different transcriptional factors. In addition, RYBP interacts directly or indirectly with apoptosis‐associated proteins to mediate anti‐apoptotic or pro‐apoptotic activity in both the cytoplasm and nucleus of various cell types. Furthermore, RYBP has also been shown to act as tumour suppressor gene in different solid tumours, but as an oncogene in lymphoma and melanoma. In this review, we summarize our current understanding of the functions of this multifaceted RYBP in physiological and pathological conditions, including embryonic development, apoptosis and cancer, as well as its role as a component of polycomb repressive complex 1.

RYBP Inhibits Progression and Metastasis of Lung Cancer by Suppressing EGFR Signaling and Epithelial-Mesenchymal Transition

Lung cancer (LC) is a common lethal malignancy with rapid progression and metastasis, and Ring1 and YY1 binding protein (RYBP) has been shown to suppress cell growth in human cancers. This study aimed to investigate the role of RYBP in LC progression and metastasis. In this study, a total of 149 LC patients were recruited, and the clinical stage of their tumors, metastasis status, survival time, presence of epidermal growth factor receptor (EGFR) mutation, and RYBP expression levels were measured. RYBP silencing and overexpression were experimentally performed in LC cell lines and in nude mice, and the expressions of genes in EGFR-related signaling pathways and epithelial-mesenchymal transition (EMT) were detected. The results showed that RYBP was downregulated in LC compared with adjacent normal tissues, and low RYBP expression was associated with a more severe clinical stage, high mortality, high metastasis risk, and poor survival. Cell proliferation and xenograft growth were inhibited by RYBP overexpression, whereas proliferation and xenograft growth were accelerated by RYBP silencing. EGFR and phosphorylated-EGFR levels were upregulated when RYBP was silenced, whereas EGFR, p-EGFR, p-AKT, and p-ERK were downregulated when RYBP was overexpressed. Low RYBP expression was related to a high metastasis risk, and metastasized tumors showed low RYBP levels. Cell migration and invasion were promoted by silencing RYBP but were inhibited by overexpressed RYBP. In addition, the EMT marker vimentin showed diminished expression, and E-cadherin was promoted by the overexpression of RYBP. In conclusion, our data suggest that RYBP suppresses cell proliferation and LC progression by impeding the EGFR-ERK and EGFR-AKT signaling pathways and thereby inhibiting cell migration and invasion and LC metastasis through the suppression of EMT.