PEG10 plays a crucial role in human lung cancer proliferation, progression, prognosis and metastasis

Roles of PEG10 in cancer and neurodegenerative disorder (Review)

Paternally expressed gene 10 (PEG10) is an imprinting gene. In addition to its known roles in placental development, as well as mouse embryonic stem cell and trophoblast stem cell differentiation, PEG10 has recently been shown to have significance in cancers. High expression of PEG10 is observed in various cancer types and is associated with poor prognosis. Of note, disruption of PEG10 expression leads to increased apoptosis, as well as decreased proliferation, invasion and migration of cancer cells. PEG10 is expected to become a target for cancer and neurodegenerative disorder therapy. This article reviewed the latest progress in the role of PEG10 in cancers.

Evolutionary dynamics of PEG10 and its interacting proteins during early and late-stage placental development in ruminants

Ruminants play a crucial role in dairy farming, pharmaceuticals, and embryonic stem cell research; thus, it is vital to prevent pregnancy loss and improve reproductive outcomes through a better understanding of placental development. Paternally-expressed gene 10 (PEG10) is a conserved gene essential for placental development in mammals, but its function in ruminants is not well understood. To develop insights into its role in placental development, this study investigated the gene structure and expression of PEG10 in cattle and goats. We found that PEG10's structure was conserved across species, and in the placenta, it retained the ability to bind to its own mRNA. Transcript analysis revealed differential expression patterns of PEG10 at early and late stages of placental development. We identified 70 proteins potentially interacting with PEG10 that were involved in biological processes like metabolism, signal transduction, cell proliferation, and immune responses. These proteins were grouped into seven clusters, associated with pathways such as amino acid degradation, the TCA cycle, longevity regulation, cardiomyopathy, proteasome function, and biosynthesis. Our findings suggest that PEG10 regulates placental development in ruminants by interacting with key proteins like CAST, ITGA6, and FTL, which are responsible for critical cellular processes in placental function.

Abrogation of USP9X Is a Potential Strategy to Decrease PEG10 Levels and Impede Tumor Progression in Cutaneous T-Cell Lymphoma

Advanced-stage cutaneous T-cell lymphomas (CTCLs) are notorious for their highly aggressive behavior, resistance to conventional treatments, and poor prognosis, particularly when large-cell transformation occurs. PEG10 has been recently proposed as a potent driver for large-cell transformation in CTCL. However, the targeting of PEG10 continues to present a formidable clinical challenge that has yet to be addressed. In this study, we report an important post-translational regulatory mechanism of PEG10 in CTCL. USP9X, a deubiquitinase, interacted with and deubiquitinated PEG10, thereby stabilizing PEG10. Knockdown of USP9X or pharmacological targeting of USP9X resulted in a prominent downregulation of PEG10 and its downstream pathway in CTCL. Moreover, USP9X inhibition conferred tumor cell growth disadvantage and enhanced apoptosis in vitro, an effect that occurred in part through its regulation on PEG10. Furthermore, we demonstrated that inhibition of USP9X obviously restrained CTCL tumor growth in vivo and that high expression of USP9X is associated with poor survival in patients with CTCL. Collectively, our findings uncover USP9X as a key post-translational regulator in the stabilization of PEG10 and suggest that targeting PEG10 stabilization through USP9X inhibition may represent a promising therapeutic strategy for advanced-stage CTCL.

Pan-cancer analysis identified OAS1 as a potential prognostic biomarker for multiple tumor types

Background

2',5'-oligoadenylate synthetase 1 (OAS1), has been reported as a tumor driver gene in breast carcinoma and pancreatic carcinoma. However, the role of OAS1 in most tumors has not been reported.

Methods

The original data of 35 tumor types were down load from the TCGA (The Cancer Genome Atlas) database and Human Protein Atlas (HPA) database. TIMER2, Kmplot, UALCAN, and TISIDB tools were used to investigate the expression and function of OAS1, and the role of OAS1 in prognosis, diagnostic value, and immune characteristics of pan-cancer. LUAD and PRAD cell lines, A549, H1975, PC-3 and C4-2 were utilized to perform cell function tests.

Results

OAS1 expression was up-regulated in 12 tumor types and down-regulated in 2 tumor types. High OAS1 expression was correlated with poor prognosis in 6 tumor types, while high OAS1 expression was correlated with good prognosis in 2 tumor types. OAS1 was correlated with molecular subtypes in 8 tumor types and immune subtypes in 12 tumor types. OAS1 was positively associated with the expression of numerous immune checkpoint genes and tumor mutational burden (TMB). OAS1 had potential diagnostic value in 15 tumor types. Silence of OAS1 significantly inhibited the cell proliferation ability, and promoted G2/M cell cycle arrest of LUAD and PRAD cells. Meanwhile, silence of OAS1 enhanced cisplatin-induced apoptosis of LUAD and PRAD cells, but weakened cell migration.

Conclusion

This pan-cancer study suggests that OAS1can be used as a molecular biomarker for prognosis in pan-cancer and may play an important role in tumor immune response.

CircRNA-Associated CeRNAs Regulatory Axes in Retinoblastoma: A Systematic Scoping Review

Retinoblastoma (RB) is one of the most common childhood cancers caused by RB gene mutations (tumor suppressor gene in various patients). A better understanding of molecular pathways and the development of new diagnostic approaches may lead to better treatment for RB patients. The number of studies on ceRNA axes is increasing, emphasizing the significance of these axes in RB. Circular RNAs (circRNAs) play a vital role in competing endogenous RNA (ceRNA) regulatory axes by sponging microRNAs and regulating gene expression. Because of the broadness of ceRNA interaction networks, they may assist in investigating treatment targets in RB. This study conducted a systematic scoping review to evaluate verified loops of ceRNA in RB, focusing on the ceRNA axis and its relationship to circRNAs. This scoping review was carried out using a six-step strategy and the Prisma guideline, and it involved systematically searching the publications of seven databases. Out of 363 records, sixteen articles were entirely consistent with the defined inclusion criteria and were summarized in the relevant table. The majority of the studies focused on the circRNAs circ_0000527, circ_0000034, and circTET1, with approximately two-fifths of the studies focusing on a single circRNA. Understanding the many features of this regulatory structure may help elucidate RB's unknown causative factors and provide novel molecular potential therapeutic targets and medical fields.

Transcriptional regulator CTR9 promotes hepatocellular carcinoma progression and metastasis via increasing PEG10 transcriptional activity

Cln Three Requiring 9 (CTR9), a scaffold protein of the polymerase-associated factor-1 (PAF1) complex (PAF1c), is primarily localized in the nucleus of cells. Recent studies show that CTR9 plays essential roles in the development of various human cancers and their occurrence; however, its regulatory roles and precise mechanisms in hepatocellular carcinoma (HCC) remain unclear. In this study, we investigated the roles of CTR9 using in vitro assays and a xenograft mouse model. We found that CTR9 protein is upregulated in tumor tissues from HCC patients. Knockdown of CTR9 substantially reduced HCC cell proliferation, invasion, and migration, whereas its overexpression promoted these activities. In addition, in vitro results revealed that CTR9 silencing dramatically increased cell cycle regulators, p21 and p27, but markedly decreased matrix metalloproteinases, MMP2 and MMP9, with these outcomes reversed upon CTR9 overexpression. Furthermore, the underlying molecular mechanism suggests that CTR9 promoted the oncogene paternally expressed gene 10 (PEG10) transcription via its promoter region. Finally, the oncogenic roles of CTR9 were confirmed in a xenograft mouse model. This study confirms that CTR9, an oncoprotein that promotes HCC cell proliferation, invasion, and migration, increases tumor growth in a xenograft mouse model. CTR9 could be a novel therapeutic target. Further investigation is warranted to verify CTR9 potential in novel therapies for HCC.

MYCN and MAX alterations in Wilms tumor and identification of novel N-MYC interaction partners as biomarker candidates

BACKGROUND

Wilms tumor (WT) is the most common renal tumor in childhood. Among others, MYCN copy number gain and MYCN P44L and MAX R60Q mutations have been identified in WT. MYCN encodes a transcription factor that requires dimerization with MAX to activate transcription of numerous target genes. MYCN gain has been associated with adverse prognosis in different childhood tumors including WT. The MYCN P44L and MAX R60Q mutations, located in either the transactivating or basic helix-loop-helix domain, respectively, are predicted to be damaging by different pathogenicity prediction tools, but the functional consequences remain to be characterized.

METHODS

We screened a large cohort of unselected WTs for MYCN and MAX alterations. Wild-type and mutant protein function were characterized biochemically, and we analyzed the N-MYC protein interactome by mass spectrometric analysis of N-MYC containing protein complexes.

RESULTS

Mutation screening revealed mutation frequencies of 3% for MYCN P44L and 0.9% for MAX R60Q that are associated with a higher risk of relapse. Biochemical characterization identified a reduced transcriptional activation potential for MAX R60Q, while the MYCN P44L mutation did not change activation potential or protein stability. The protein interactome of N-MYC-P44L was likewise not altered as shown by mass spectrometric analyses of purified N-MYC complexes. Nevertheless, we could identify a number of novel N-MYC partner proteins, e.g. PEG10, YEATS2, FOXK1, CBLL1 and MCRS1, whose expression is correlated with MYCN in WT samples and several of these are known for their own oncogenic potential.

CONCLUSIONS

The strongly elevated risk of relapse associated with mutant MYCN and MAX or elevated MYCN expression corroborates their role in WT oncogenesis. Together with the newly identified co-expressed interactors they expand the range of potential biomarkers for WT stratification and targeting, especially for high-risk WT.

Short-term personal PM2.5 exposure and change in DNA methylation of imprinted genes: Panel study of healthy young adults in Guangzhou city, China

DNA methylation (DNAm) plays a significant role in deleterious health effects inflicted by fine particulate matter (PM_2.5) on the human body. Recent studies have reported that DNAm of imprinted control regions (ICRs) in imprinted genes may be a sensitive biomarker of environmental exposure. Less is known about specific biomarkers of imprinted genes after PM_2.5 exposure. The relationship between PM_2.5 and its chemical constituents and DNAm of ICRs in imprinted genes after short-term exposure was investigated to determine specific human biomarkers of its adverse health effects. A panel study was carried out in healthy young people in Guangzhou, China. Mixed-effects models were used to evaluate the influence of PM_2.5 and its constituent exposure on DNAm while controlling for potential confounders. There was no significant correlation between DNAm and personal PM_2.5 exposure mass. DNAm changes in eight ICRs (L3MBTL1, NNAT, PEG10, GNAS Ex1A, MCTS2, SNURF/SNRPN, IGF2R, and RB1) and a non-imprinted gene (CYP1B1) were significantly associated with PM_2.5 constituents. Compared to non-imprinted genes, imprinted gene methylation was more susceptible to interference with PM_2.5 constituent exposure. Among those genes, L3MBTL1 was the most sensitive to personal PM_2.5 constituent exposure. Moreover, transition metals derived from traffic sources (Cd, Fe, Mn, and Ni) significantly influenced DNAm of the imprinted genes, suggesting the importance of more targeted measures to reduce toxic constituents. Bioinformatics analysis indicated that imprinted genes (RB1) may be correlated with pathways and diseases (non-small cell lung cancer, glioma, and bladder cancer). The present study suggests that screening the imprinted gene for DNAm can be used as a sensitive biomarker of PM_2.5 exposure. The results will provide data for prevention of PM_2.5 exposure and a novel perspective on potential mechanisms on an epigenetic level.

Gene networks and transcriptional regulators associated with liver cancer development and progression

BACKGROUND

Treatment options for hepatocellular carcinoma (HCC) are limited, and overall survival is poor. Despite the high frequency of this malignoma, its basic disease mechanisms are poorly understood. Therefore, the aim of this study was to use different methodological approaches and combine the results to improve our knowledge on the development and progression of HCC.

METHODS

Twenty-three HCC samples were characterized by histological, morphometric and cytogenetic analyses, as well as comparative genomic hybridization (aCGH) and genome-wide gene expression followed by a bioinformatic search for potential transcriptional regulators and master regulatory molecules of gene networks.

RESULTS

Histological evaluation revealed low, intermediate and high-grade HCCs, and gene expression analysis split them into two main sets: GE1-HCC and GE2-HCC, with a low and high proliferation gene expression signature, respectively. Array-based comparative genomic hybridization demonstrated a high level of chromosomal instability, with recurrent chromosomal gains of 1q, 6p, 7q, 8q, 11q, 17q, 19p/q and 20q in both HCC groups and losses of 1p, 4q, 6q, 13q and 18q characteristic for GE2-HCC. Gene expression and bioinformatics analyses revealed that different genes and gene regulatory networks underlie the distinct biological features observed in GE1-HCC and GE2-HCC. Besides previously reported dysregulated genes, the current study identified new candidate genes with a putative role in liver cancer, e.g. C1orf35, PAFAH1B3, ZNF219 and others.

CONCLUSION

Analysis of our findings, in accordance with the available published data, argues in favour of the notion that the activated E2F1 signalling pathway, which can be responsible for both inappropriate cell proliferation and initial chromosomal instability, plays a pivotal role in HCC development and progression. A dedifferentiation switch that manifests in exaggerated gene expression changes might be due to turning on transcriptional co-regulators with broad impact on gene expression, e.g. POU2F1 (OCT1) and NFY, as a response to accumulating cell stress during malignant development. Our findings point towards the necessity of different approaches for the treatment of HCC forms with low and high proliferation signatures and provide new candidates for developing appropriate HCC therapies.

Emodin enhances cisplatin sensitivity in non-small cell lung cancer through Pgp downregulation

Cisplatin resistance is one of the main causes of chemotherapy failure and tumor progression in non-small cell lung cancer (NSCLC). Emodin has been demonstrated to induce NSCLC cell apoptosis and act as a potential cancer therapeutic agent. However, whether emodin could affect NSCLC cell sensitivity toward cisplatin remains unclear. The present study aimed to determine the effect of emodin and cisplatin combination on the chemosensitivity of NSCLC cells. A549 and H460 cells were treated with different concentrations of cisplatin and/or emodin. Cell Counting Kit-8, fluorescence microscopy, immunofluorescence assays and flow cytometry were used to determine cell proliferation, drug efflux, DNA damage level and cell apoptosis, respectively. P-glycoprotein (Pgp) and multidrug resistance-associated protein 1 (MRP1) expression was detected by western blotting. The results demonstrated that emodin and cisplatin inhibited the proliferation of A549 and H460 cells. Furthermore, emodin inhibited the drug efflux in A549 and H460 cells in a dose-dependent manner. In addition, emodin enhanced cisplatin-induced apoptosis and DNA damage in A549 and H460 cells. Emodin also decreased Pgp expression in A549 and H460 cells in a dose-dependent manner; however, it had no effect on MRP1 expression. Taken together, the results from the present study demonstrated that emodin can increase A549 and H460 cell sensitivity to cisplatin by inhibiting Pgp expression. Emodin may therefore be considered as an effective adjuvant for cisplatin treatment.

Differential Expression of PEG10 Contributes to Aggressive Disease in Early Versus Late-Onset Colorectal Cancer

BACKGROUND

Colorectal cancer is a leading cause of cancer-related death. Early onset colorectal cancer (age ≤45 y) is increasing and associated with advanced disease. Although distinct molecular subtypes of colorectal cancer have been characterized, it is unclear whether age-related molecular differences exist.

OBJECTIVE

We sought to identify differences in gene expression between early and late-onset (age ≥65 y) colorectal cancer.

DESIGN

We performed a review of our institution's colorectal cancer registry and identified patients with colorectal cancer with tissue specimens available for analysis. We used the Cancer Genome Atlas to initially identify differences in gene expression between early and late-onset colorectal cancer. In vitro experiments were performed on 2 colorectal cancer cell lines.

SETTINGS

The study was conducted at a tertiary medical center.

PATIENTS

Patients with early onset (n = 28) or late onset (age ≥65 y; n = 38) at time of diagnosis were included.

MAIN OUTCOME MEASURES

The primary outcome was differential gene expression in patients with early versus late-onset colorectal cancer. The secondary outcome was patient mortality.

RESULTS

Seven genes had increased expression in younger patients using The Cancer Genome Atlas. Only PEG10 was sufficiently expressed with quantitative polymerase chain reaction and had increased expression in our early onset group. Multivariable linear regression analysis identified age as a significant independent predictor of increased PEG10 expression. Outcomes data from The Cancer Genome Atlas suggests that PEG10 is associated with poor overall survival. In vitro studies in HCT-116 and HT-29 cell lines showed that PEG10 contributes to cellular proliferation and invasion in colorectal cancer.

LIMITATIONS

Tissue samples were from formalin-fixed, paraffin-embedded sections. Many patients did not have mutational status for review.

CONCLUSIONS

PEG10 is differentially expressed in early onset colorectal cancer and may functionally contribute to tumor cell proliferation and invasion. An increase in PEG10 expression correlates with decreased overall survival. See Video Abstract at http://links.lww.com/DCR/B343. LA EXPRESIÓN DIFERENCIAL DE PEG10 CONTRIBUYE A LA ENFERMEDAD AGRESIVA EN EL CÁNCER COLORRECTAL DE INICIO TEMPRANO VERSUS INICIO TARDÍO: El cáncer colorrectal es una de las principales causas de muerte relacionada con el cáncer. El cáncer colorrectal de inicio temprano (edad ≤45 años) está en aumento y asociado con enfermedad avanzada. Aunque se han caracterizado distintos subtipos moleculares del cáncer colorrectal, no está claro si existen diferencias moleculares relacionadas con la edad.Se buscó identificar diferencias en la expresión génica entre el cáncer colorrectal de inicio temprano y tardío (edad ≥ 65 años).Realizamos una revisión del registro de cáncer colorrectal de nuestra institución e identificamos pacientes con cáncer colorrectal con muestras de tejido disponibles para su análisis. Utilizamos el Atlas del Genoma del Cáncer para identificar inicialmente las diferencias en la expresión génica entre el cáncer colorrectal de inicio temprano y de inicio tardío. Se realizaron experimentos in vitro en dos líneas celulares de cáncer colorrectal.El estudio se realizó en un centro médico de tercer nivel.Se incluyeron pacientes con inicio temprano (n = 28) e inicio tardío (edad ≥65 años, n = 38) al momento del diagnóstico.El resultado primario fue la expresión diferencial de genes en pacientes con cáncer colorrectal de inicio temprano versus tardío. El resultado secundario fue la mortalidad de los pacientes.Siete genes aumentaron su expresión en pacientes más jóvenes usando el Atlas del Genoma del Cáncer. Solo PEG10 se expresó suficientemente con la reacción en cadena de la polimerasa cuantitativa y tuvo una mayor expresión en nuestro grupo de inicio temprano. El análisis de regresión lineal multivariable identificó la edad como un predictor independiente significativo del aumento de la expresión de PEG10. Los datos de resultados de el Atlas del Genoma del Cáncer sugieren que PEG10 está asociado con una pobre supervivencia general. Los estudios in vitro en líneas celulares HCT-116 y HT-29 mostraron que PEG10 contribuye a la proliferación e invasión celular en el cáncer colorrectal.Las muestras de tejido fueron de portaobjetos embebidos en parafina fijados con formalina. Muchos pacientes no tenían el estado de mutación para su revisión.El PEG10 se expresa diferencialmente en el cáncer colorrectal de inicio temprano y puede contribuir funcionalmente a la proliferación e invasión de células tumorales. El aumento en la expresión de PEG10 se correlaciona con la disminución de la supervivencia general. Consulte Video Resumen en http://links.lww.com/DCR/B343.

Functional Study of the Retrotransposon-Derived Human PEG10 Protease

Paternally expressed gene 10 (PEG10) is a human retrotransposon-derived imprinted gene. The mRNA of PEG10 encodes two protein isoforms: the Gag-like protein (RF1_PEG10) is coded by reading frame 1, while the Gag-Pol-like polyprotein (RF1/RF2_PEG10) is coded by reading frames 1 and 2. The proteins are translated by a typical retroviral frameshift mechanism. The protease (PR) domain of RF2_PEG10 contains an -Asp-Ser-Gly- sequence, which corresponds to the consensus -Asp-Ser/Thr-Gly- active-site motif of retroviral aspartic proteases. The function of the aspartic protease domain of RF2_PEG10 remains unclear. To elucidate the function of PEG10 protease (PR_PEG10), we designed a frameshift mutant (_fsRF1/RF2_PEG10) for comparison with the RF1/RF2_PEG10 form. To study the effects of PR_PEG10 on cellular proliferation and viability, mammalian HEK293T and HaCaT cells were transfected with plasmids coding for either RF1/RF2_PEG10, the frameshift mutant (_fsRF1/RF2_PEG10), or a PR active-site (D370A) mutant _fsRF1/RF2_PEG10. Our results indicate that _fsRF1/RF2_PEG10 overexpression results in increased cellular proliferation. Remarkably, transfection with _fsRF1/RF2_PEG10 had a detrimental effect on cell viability. We hypothesize that PR_PEG10 plays an important role in the function of this retroviral remnant, mediating the proliferation of cells and possibly implicating it in the inhibition of apoptosis.

Curcumin Inhibits the Migration and Invasion of Non-Small-Cell Lung Cancer Cells Through Radiation-Induced Suppression of Epithelial-Mesenchymal Transition and Soluble E-Cadherin Expression

Radiotherapy has been reported to cause cancer metastasis. Thus, a new strategy for radiotherapy must be developed to avoid this side effect. A549 cells were exposed to radiation to induce an epithelial-mesenchymal transition (EMT) cell model. Real-time PCR and western blotting were used to detect mRNA and protein expression levels, and Transwell invasion and wound healing assays were used to detect cell migration and invasion. ELISA was used to detect soluble E-cadherin (sE-cad) secretion. siRNA was used to silence MMP9 expression. The results show that A549R cells exhibited an EMT phenotype with increased E-cadherin, N-cadherin, Snail, Slug, vimentin and Twist expression and decreased pan-keratin expression. sE-cad levels were increased in A549R cells and in the serum of NSCLC patients with distant metastasis. Exogenous sE-cad treatment and sE-cad overexpression promoted A549R and A549 cell migration and invasion. In contrast, blocking sE-cad attenuated A549 cell migration and invasion. Curcumin inhibited sE-cad expression and reversed EMT induced by radiation. Furthermore, curcumin suppressed sE-cad-enhanced A549 and A549R cell migration and invasion. Curcumin inhibited MMP9 expression, and silencing MMP9 suppressed sE-cad expression. Taken together, we found a nonclassic EMT phenomenon induced by radiation. Curcumin inhibits NSCLC migration and invasion by suppressing radiation-induced EMT and sE-cad expression by decreasing MMP9 expression.

Weighted gene expression profiles identify diagnostic and prognostic genes for lung adenocarcinoma and squamous cell carcinoma

OBJECTIVE

To construct a diagnostic signature to distinguish lung adenocarcinoma from lung squamous cell carcinoma and a prognostic signature to predict the risk of death for patients with nonsmall-cell lung cancer, with satisfactory predictive performances, good stabilities, small sizes and meaningful biological implications.

METHODS

Pathway-based feature selection methods utilize pathway information as a priori to provide insightful clues on potential biomarkers from the biological perspective, and such incorporation may be realized by adding weights to test statistics or gene expression values. In this study, weighted gene expression profiles were generated using the GeneRank method and then the LASSO method was used to identify discriminative and prognostic genes.

RESULTS

The five-gene diagnostic signature including keratin 5 (KRT5), mucin 1 (MUC1), triggering receptor expressed on myeloid cells 1 (TREM1), complement C3 (C3) and transmembrane serine protease 2 (TMPRSS2) achieved a predictive error of 12.8% and a Generalized Brier Score of 0.108, while the five-gene prognostic signature including alcohol dehydrogenase 1C (class I), gamma polypeptide (ADH1C), alpha-2-glycoprotein 1, zinc-binding (AZGP1), clusterin (CLU), cyclin dependent kinase 1 (CDK1) and paternally expressed 10 (PEG10) obtained a log-rank P-value of 0.03 and a C-index of 0.622 on the test set.

CONCLUSIONS

Besides good predictive capacity, model parsimony and stability, the identified diagnostic and prognostic genes were highly relevant to lung cancer. A large-sized prospective study to explore the utilization of these genes in a clinical setting is warranted.

Prediction of relapse and prognosis by expression levels of long noncoding RNA PEG10 in glioma patients

BACKGROUND

Long noncoding RNA paternally expressed 10 (lncRNA PEG10) is highly expressed in a variety of human cancers and related to the clinical prognosis of patients. However, to date there has been no previous study evaluating the prognostic significance of lncRNA PEG10 in gliomas. In the present study, we investigated the expression levels of lncRNA PEG10 to determine the prognostic value of this oncogene in human gliomas.

METHODS

Expression levels of lncRNA PEG10 were detected by real-time polymerase chain reaction in a hospital-based study cohort of 147 glioma patients and 23 cases of patients with craniocerebral trauma tissues. Associations of lncRNA PEG10 expression with clinicopathological variables and clinical outcome of glioma patients were investigated.

RESULTS

The results indicated that expression levels of lncRNA PEG10 were significantly increased in human gliomas compared to normal control brain tissues. In addition, lncRNA PEG10 expression was progressively increased from pathologic grade I to IV (P = .009) and correlated with the Karnofsky performance status (P = .018) in glioma patients. Furthermore, we also found that glioma patients with increased expression of lncRNA PEG10 had a higher risk to relapse and a statistically significant shorter overall survival (OS) than patients with reduced expression of lncRNA PEG10. In multivariate analysis, expression level of lncRNA PEG10 was found to be an independent prognostic factor for both progression-free survival and OS in glioma patients.

CONCLUSIONS

LncRNA PEG10 served as an oncogene and played crucial roles in the progression of glioma. Molecular therapy targeted on lncRNA PEG10 might bring significant benefits to the clinical outcome of malignant glioma.

Phosphorylated E2F1 is stabilized by nuclear USP11 to drive Peg10 gene expression and activate lung epithelial cells

Phosphorylation affects ubiquitination, stability, and activity of transcriptional factors, thus regulating various cellular functions. E2F transcriptional factor 1 (E2F1) regulates paternally expressed imprinted gene 10 (Peg10) expression, thereby promoting cell proliferation. However, the effect of E2F1 stability on Peg10 expression and the molecular regulation of E2F1 stability by its phosphorylation have not been well demonstrated. Here, we describe a new pathway in which phosphorylation of E2F1 by GSK3β increases E2F1 association with the deubiquitinating enzyme, ubiquitin-specific protease 11 (USP11), which removes K63-linked ubiquitin chains thereby preventing E2F1 degradation in the nuclei. Downregulation of USP11 increases E2F1 ubiquitination and reduces E2F1 stability and protein levels, thereby decreasing Peg10 mRNA levels. Physiologically, USP11 depletion suppresses cell proliferation and wound healing in lung epithelial cells, and these effects are reversed by E2F1 and PEG10 overexpression. Thus, our study reveals a new molecular model that phosphorylation promotes substrate stability through increasing its association with a deubiquitinating enzyme. The data suggest that GSK3β and USP11 act in concert to modulate E2F1 abundance and PEG10 expression in lung epithelial cells to affect cell wound healing. This study provides new therapeutic targets to lessen lung injury by improving lung epithelial cell repair and remodeling after injury.

PEG10 counteracts signaling pathways of TGF-β and BMP to regulate growth, motility and invasion of SW1353 chondrosarcoma cells

Recently, we reported highly active transforming growth factor (TGF)-β and bone morphogenetic protein (BMP) signaling in human chondrosarcoma samples and concurrent downregulation of paternally expressed gene 10 (PEG10). PEG10 expression was suppressed by TGF-β signaling, and PEG10 interfered with the TGF-β and BMP-SMAD pathways in chondrosarcoma cells. However, the roles of PEG10 in bone tumors, including chondrosarcoma, remain unknown. Here, we report that PEG10 promotes SW1353 chondrosarcoma cell growth by preventing TGF-β1-mediated suppression. In contrast, PEG10 knockdown augments the TGF-β1-induced motility of SW1353 cells. Individually, TGF-β1 and PEG10 siRNA increase AKT phosphorylation, whereas an AKT inhibitor, MK2206, mitigates the effect of PEG10 silencing on cell migration. SW1353 cell invasion was enhanced by BMP-6, which was further increased by PEG10 silencing. The effect of siPEG10 was suppressed by inhibitors of matrix metalloproteinase (MMP). BMP-6 induced expression of MMP-1, -3, and -13, and PEG10 lentivirus or PEG10 siRNA downregulated or further upregulated these MMPs, respectively. PEG10 siRNA increased BMP-6-induced phosphorylation of p38 MAPK and AKT, whereas the p38 inhibitor SB203580 and MK2206 diminished SW1353 cell invasion by PEG10 siRNA. SB203580 and MK2206 impeded the enhancing effect of PEG10 siRNA on the BMP-6-induced expression of MMP-1, -3, and -13. Our findings suggest dual functions for PEG10: accelerating cell growth by suppressing TGF-β signaling and inhibiting cell motility and invasion by interfering with TGF-β and BMP signaling via the AKT and p38 pathways, respectively. Thus, PEG10 might be a molecular target for suppressing the aggressive phenotypes of chondrosarcoma cells.

TSG101 promotes the proliferation, migration and invasion of hepatocellular carcinoma cells by regulating the PEG10

The tumour susceptibility gene 101 (TSG101) is reported to play important roles in the development and progression of several human cancers. However, its potential roles and underlined mechanisms in human hepatocellular carcinoma (HCC) are still needed to be further clarified. In the present study, we reported that knock down of TSG101 suppressed the proliferation, migration and invasion of HCC cells, while overexpression of TSG101 facilitated them. Molecularly, the results revealed that knock down of TSG101 significantly decreased the cell cycle related regulatory factor p53 and p21. In another point, knock down of TSG101 also obviously decreased the level of metallopeptidase inhibitor TIMP1 (Tissue inhibitors of metalloproteinases 1), which results in inhibition of MMP2, MMP7 and MMP9. In contrast, overexpression of TSG101 had opposite effects. The iTRAQ proteomics analysis identified that oncogenic protein PEG10 (Paternally expressed gene 10) might be a potential downstream target of TSG101. Further investigation showed that TSG101 interacted with PEG10 and protected it from proteasomal degradation thereby regulating the expression of p53, p21 and MMPs. Finally, we found that both TSG101 and PEG10 proteins are up-regulated and presented a direct correlation in HCC patients. In conclusion, these results suggest that TSG101 is up-regulated in human HCC patients, which may accelerate the proliferation, migration and invasion of HCC cells through regulating PEG10.

PEG10 as an oncogene: expression regulatory mechanisms and role in tumor progression

Cancer is a major public health problem as one of the leading causes of death worldwide. Deciphering the molecular regulation mechanisms of tumor progression can make way for tumor diagnosis and therapy. Paternally expressed gene 10 (PEG10), located on human chromosome 7q21.3, has turned out to be an oncogene implicated in the proliferation, apoptosis and metastasis of tumors. PEG10 has been found to be positively expressed in a variety of cancers with seemingly complex expression regulation mechanisms. In this review, we focus on the most vital factors influencing PEG10 expression and recapitulate some of the currently known and potential mechanisms of PEG10 affecting tumor progression, as understanding the molecular regulatory mechanisms of tumor progression can provide potential PEG10 related diagnosis and biomarker specific targeted therapies.

Prognostic value of PEG10 in Asian solid tumors: A meta-analysis

BACKGROUND

The involvement of paternally expressed gene 10 (PEG10) in the development of solid tumors has been demonstrated. However, the available data have not yet been fully analyzed. We conducted this meta-analysis to evaluate the correlations between PEG10 and the clinicopathological characteristics in patients with solid tumors.

METHODS

An electronic search for relevant articles was conducted in PubMed, Web of Science, Cochrane Library, EMBASE, Chinese CNKI, and Wan Fang. The relationships between PEG10 and the clinicopathological features and prognosis of patients with cancer were determined using pooled odds ratios and hazard ratios with 95% confidence interval (CI).

RESULTS

Ten studies comprising 1014 patients were included. The pooled analyses indicated the significant association of PEG10 overexpression with the risk of cancer, differentiation, lymph node metastasis and advanced TNM stage, but not with gender in cancer patients. Moreover, a high level of PEG10 expression correlated with poor prognosis and could be used as an independent prognostic biomarker for patients with solid tumors.

CONCLUSIONS

PEG10 expression is associated with advanced clinicopathological characteristics and can be used as a prognostic biomarker in patients with solid tumors.

Profiling, clinicopathological correlation and functional validation of specific long non-coding RNAs for hepatocellular carcinoma

Background

Hepatocellular carcinoma (HCC) is one of the most prevalent and aggressive malignancies worldwide. Studies seeking to advance the overall understanding of lncRNA profiling in HCC remain rare.

Methods

The transcriptomic profiling of 12 HCC tissues and paired adjacent normal tissues was determined using high-throughput RNA sequencing. Fifty differentially expressed mRNAs (DEGs) and lncRNAs (DELs) were validated in 21 paired HCC tissues via quantitative real-time PCR. The correlation between the expression of DELs and various clinicopathological characteristics was analyzed using Student’s t-test or linear regression. Co-expression networks between DEGs and DELs were constructed through Pearson correlation co-efficient and enrichment analysis. Validation of DELs’ functions including proliferation and migration was performed via loss-of-function RNAi assays.

Results

In this study, we identified 439 DEGs and 214 DELs, respectively, in HCC. Furthermore, we revealed that multiple DELs, including NONHSAT003823, NONHSAT056213, NONHSAT015386 and especially NONHSAT122051, were remarkably correlated with tumor cell differentiation, portal vein tumor thrombosis, and serum or tissue alpha fetoprotein levels. In addition, the co-expression network analysis between DEGs and DELs showed that DELs were involved with metabolic, cell cycle, chemical carcinogenesis, and complement and coagulation cascade-related pathways. The silencing of the endogenous level of NONHSAT122051 or NONHSAT003826 could significantly attenuate the mobility of both SK-HEP-1 and SMMC-7721 HCC cells.

Conclusion

These findings not only add knowledge to the understanding of genome-wide transcriptional evaluation of HCC but also provide promising targets for the future diagnosis and treatment of HCC.

TGF-β signalling and PEG10 are mutually exclusive and inhibitory in chondrosarcoma cells

Histological distinction between enchondroma and chondrosarcoma is difficult because of a lack of definitive biomarkers. Here, we found highly active transforming growth factor-β (TGF-β) and bone morphogenetic protein (BMP) signalling in human chondrosarcomas compared with enchondromas by immunohistochemistry of phosphorylated SMAD3 and SMAD1/5. In contrast, the chondrogenic master regulator SOX9 was dramatically down-regulated in grade 1 chondrosarcoma. Paternally expressed gene 10 (PEG10) was identified by microarray analysis as a gene overexpressed in chondrosarcoma SW1353 and Hs 819.T cells compared with C28/I2 normal chondrocytes, while TGF-β1 treatment, mimicking higher grade tumour conditions, suppressed PEG10 expression. Enchondroma samples exhibited stronger expression of PEG10 compared with chondrosarcomas, suggesting a negative association of PEG10 with malignant cartilage tumours. In chondrosarcoma cell lines, application of the TGF-β signalling inhibitor, SB431542, increased the protein level of PEG10. Reporter assays revealed that PEG10 repressed TGF-β and BMP signalling, which are both SMAD pathways, whereas PEG10 knockdown increased the level of phosphorylated SMAD3 and SMAD1/5/9. Our results indicate that mutually exclusive expression of PEG10 and phosphorylated SMADs in combination with differentially expressed SOX9 is an index to distinguish between enchondroma and chondrosarcoma, while PEG10 and TGF-β signalling are mutually inhibitory in chondrosarcoma cells.

The H19-PEG10/IGF2BP3 axis promotes gastric cancer progression in patients with high lymph node ratios

We previously demonstrated that the lymph node ratio (LNR) is a prognostic factor associated with EGFR expression, among first priority genes amplified or overexpressed in cancer. Here, we investigated the associations between high LNR and second, third, and fourth priority genes. We performed mRNA expression microarray analysis of tumor tissue from patients with stage III gastric cancer and high or low LNRs. Candidate high LNR-associated genes were further evaluated in 39 patients with stage III gastric cancer. The functional relevance of these genes was evaluated in gastric cancer cell lines. We focused on five genes: H19,PEG10, IGF2BP3, CD177, and PGA3. H19 and PEG10 were confirmed as high LNR-associated genes. H19, PEG10, and IGF2BP3 were found to promote each other’s expression. Knocking down H19 or PEG10 using RNAi decreased cell proliferation, invasion, anchorage-independent growth, and chemoresistance. These genes had a mutual relationship in MKN7 cells. H19 knockdown decreased expression of epithelial-mesenchymal transition-associated genes in MKN74 cells to suppress transformation. Thus, H19 promotes epithelial-mesenchymal transition in gastric cancer and is a potential therapeutic target.

Expression of Radioresistant Gene PEG10 in OSCC Patients and Its Prognostic Significance

Background:

Oral squamous cell carcinoma (OSCC) is one of the most common forms of cancer occurring worldwide. PEG10 is well known as a paternally expressed gene from a newly recognized imprinted region at human chromosome 7q21. Previous study had demonstrated that the significant expression of PEG10 was found in radioresistant OSCC cell line and its expression was significantly associated with poor survival in several cancers. Therefore it has been evaluated as a potential marker in OSCC patients undergoing radiotherapy.

Objective:

This study was conducted to analyze the mRNA expression of PEG10 in OSCC and its expression in relation to clinicpathological features, radiotherapy treatment response and survival.

Methods:

This study included tissue specimens obtained via biopsy of 118 patients with OSCC who were recommended for radiotherapy treatment and 80 healthy control tissues analysis of mRNA expression of PEG10 was done by real-time quantitative reverse transcriptase-polymerase chain reaction (qRT-PCR). Patients were treated with 70 Gy of radiation dose by shrinking field technique using Cobalt-60 teletherapy machine.

Results:

Significantly higher mRNA expression of PEG10 was found in OSCC patients when compared with matched controls. High level of PEG10 mRNA expression showed a significant correlation with lymph node metastasis (p = 0.0047) and tumor stage (p = 0.0499). Multivariate Cox regression analysis revealed that high level of mRNA expression of PEG10 was significantly associated with poor survival (p < 0.05). Our research demonstrated that the expression of PEG10 was higher in radioresistant tumor.

Conclusion:

We observed significantly increased expression of PEG10 in context of lymph node status, advanced stage and poor survival in our study. Thus PEG10 gene can be used as potential predictive and prognostic biomarker in OSCC patients undergoing radiotherapy.

PEG10 overexpression induced by E2F-1 promotes cell proliferation, migration, and invasion in pancreatic cancer

Background

Overexpression of paternally expressed gene-10 (PEG10) is known to promote the progression of several carcinomas, however, its role in pancreatic cancer (PC) is unknown. We investigated the expression and function of PEG10 in PC.

Methods

PEG10 expression and correlation with PC progression was assessed in cancerous tissues and paired non-cancerous tissues. Further, the role of PEG10 in PC cell progression and the underlying mechanisms were studied by using small interfering RNA (Si-RNA).

Results

PEG10 expression was significantly higher in cancerous tissues and correlated with PC invasion of vessels and Ki-67 expression. Si-RNA mediated PEG10 knockdown resulted in inhibition of proliferation and G0/G1 cell cycle arrest, which was mediated by p21 and p27 upregulation. A decrease in PC cell invasion and migration, mediated by ERK/MMP7 pathway, was observed in PEG10 knockdown group. Further, findings of ChIP assay suggested that E2F-1 could directly enhance the expression of PEG10 through binding to PEG10 promoter.

Conclusions

In conclusion, PEG10 was identified as a prognostic biomarker for PC and E2F-1 induced PEG10 could promote PC cell proliferation, invasion, and metastasis.

A machine learning classifier trained on cancer transcriptomes detects NF1 inactivation signal in glioblastoma

BACKGROUND

We have identified molecules that exhibit synthetic lethality in cells with loss of the neurofibromin 1 (NF1) tumor suppressor gene. However, recognizing tumors that have inactivation of the NF1 tumor suppressor function is challenging because the loss may occur via mechanisms that do not involve mutation of the genomic locus. Degradation of the NF1 protein, independent of NF1 mutation status, phenocopies inactivating mutations to drive tumors in human glioma cell lines. NF1 inactivation may alter the transcriptional landscape of a tumor and allow a machine learning classifier to detect which tumors will benefit from synthetic lethal molecules.

RESULTS

We developed a strategy to predict tumors with low NF1 activity and hence tumors that may respond to treatments that target cells lacking NF1. Using RNAseq data from The Cancer Genome Atlas (TCGA), we trained an ensemble of 500 logistic regression classifiers that integrates mutation status with whole transcriptomes to predict NF1 inactivation in glioblastoma (GBM). On TCGA data, the classifier detected NF1 mutated tumors (test set area under the receiver operating characteristic curve (AUROC) mean = 0.77, 95% quantile = 0.53 - 0.95) over 50 random initializations. On RNA-Seq data transformed into the space of gene expression microarrays, this method produced a classifier with similar performance (test set AUROC mean = 0.77, 95% quantile = 0.53 - 0.96). We applied our ensemble classifier trained on the transformed TCGA data to a microarray validation set of 12 samples with matched RNA and NF1 protein-level measurements. The classifier's NF1 score was associated with NF1 protein concentration in these samples.

CONCLUSIONS

We demonstrate that TCGA can be used to train accurate predictors of NF1 inactivation in GBM. The ensemble classifier performed well for samples with very high or very low NF1 protein concentrations but had mixed performance in samples with intermediate NF1 concentrations. Nevertheless, high-performing and validated predictors have the potential to be paired with targeted therapies and personalized medicine.

Identification of the potential biomarkers for the metastasis of rectal adenocarcinoma

Rectal cancer is a common malignant tumor of the digestive tract, with a high incidence and high mortality. This study aimed to identify the potential biomarkers and therapeutic targets for rectal adenocarcinoma (RAC) metastasis. The expression profiling of RAC patients with metastasis and RAC patients without metastasis was downloaded from The Cancer Genome Atlas (TCGA) database. The datasets were used to identify the genes associated with RAC metastasis. Fifty up-regulated genes and seventeen down-regulated genes were identified in the primary tumor loci of RAC metastasis compared with non-metastasis. Sixty-seven dysregulated gens were conducted to construct the protein-protein network, and CCND3 was the hub protein. The dysregulated genes were significantly enriched in pancreatic secretion, cell adhesion molecules pathways, response to vitamin D of biological process, and retinoid binding of molecular function. Quantitative real-time polymerase chain reaction results demonstrated that CCND3, AQP3, PEG10, and RAB27B had the up-regulated tendency in RAC metastasis; ADCY1 had the down-regulated tendency in RAC metastasis. CCND3, AQP3, PEG10, RAB27B, and ADCY1 might play essential roles in the metastasis process of RAC through pancreatic secretion and cell adhesion molecules pathways. The five genes could be potential diagnosis biomarkers or therapeutic targets for RAC metastasis.

PEG10 is imperative for TGF-β1-induced epithelial‑mesenchymal transition in hepatocellular carcinoma

Substantial evidence indicates that transforming growth factor-beta 1 (TGF-β1) plays a vital role in epithelial-mesenchymal transition (EMT). PEG10 has been shown involved in invasion and metastasis of tumors. The present study investigated the role of PEG10 in TGF-β1-triggered EMT in hepatocellular carcinoma (HCC) progression. Immunohistochemistry and real-time PCR were used to measure the expression level of PEG10 in clinical HCC tissues with or without lymph node metastasis, and normal tissues. The results showed that PEG10 expression is higher in HCC tissues and associated with overall survival (OS) and lymph node metastasis. Moreover, PEG10 expression level was remarkably higher in hepatic cancer cells than the normal hepatic cell line L02. In the present study, we constructed an adenovirus vector containing the coding area of PEG10 (Ad-PEG10) and infected HepG2 cells and found that overexpression of PEG10 promoted the cell migration, invasion ability and EMT of HepG2 cells. TGF-β1 acted on HepG2 cells by enhancing cell migration, invasion, EMT and upregulating PEG10 expression level. However, cells pretreated with adenovirus vector of PEG10 shRNAs (Ad-shRNA1 and Ad-shRNA2) did not occur EMT prior to TGF-β1 stimulation. Moreover, TGF-β1 did not increase the migration and invasion of cells with PEG10 knockdown and overexpression of PEG10 confers chemoresistance to HepG2 cells. Accordingly, sufficient PEG10 expression level is essential for TGF-β1 induced EMT and associated with the chemoresistance in HepG2 cells.

PEG10 promotes human breast cancer cell proliferation, migration and invasion

Paternally expressed imprinted gene 10 (PEG10), derived from the Ty3/Gypsy family of retrotransposons, has been implicated as a genetic imprinted gene. Accumulating evidence suggests that PEG10 plays an important role in tumor growth in various cancers, including hepatocellular carcinoma, lung cancer and prostate cancer. However, the correlation between PEG10 and breast cancer remains unclear. In the present study, we evaluated and characterized the role of PEG10 in human breast cancer proliferation, cell cycle, clone formation, migration and invasion. The expression level of PEG10 was significantly elevated in breast cancer tissues and associated with distant metastasis and poor clinical outcome. Gene set enrichment analysis indicated that high expression of PEG10 could enrich cell cycle-related processes in breast cancer tissues. Ectopic overexpression of PEG10 in breast cancer cells enhanced cell proliferation, cell cycle, clone formation along with migration and invasion. Cell-to-cell junction molecule E-cadherin was downregulated and matrix degradation proteases MMP-1, MMP-2, MMP-9 were up-regulated after PEG10 overexpression. Our results demonstrated that PEG10 is a crucial oncogene and has prognostic value for breast cancer, which could be applied in breast cancer diagnosis and targeting therapy in future.

Silencing of Paternally Expressed Gene 10 Inhibits Trophoblast Proliferation and Invasion

Paternally expressed gene 10 (PEG10) is an imprinted and monoallelic expressed gene. Previous study using a knockout mouse model revealed a crucial role of PEG10 in placental development, yet the exact function of PEG10 during placentation remains to be elucidated. In this study, denuded chorionic villi were prepared from first trimester human placentas, and transduced with PEG10 small interference RNA (siRNA) or non-targeting control sequence by lentiviral infection. Immunohistochemical staining revealed that silencing of PEG10 in the chorionic villous explants resulted in reduced immune-reactivity to CK7, Ki67 and integrin α5, implying that silencing of PEG10 impaired the proliferation of villous trophoblasts and may interfere with the activity of extravillous trophoblasts. We further investigated the role of PEG10 in the proliferation, migration and invasion of JEG-3 trophoblast cell line and the primary chorionic villous cells. PEG10-silenced JEG-3 cells and primary chorionic villous cells displayed a reduced proliferation rate and impaired invasiveness in vitro. Silencing of PEG10 in trophoblast cells led to upregulated expression of tissue inhibitor of metalloproteinase-1 (TIMP-1) as well as downregulated expression of matrix metalloproteinase (MMP)-2 and MMP-9. Furthermore, knockdown of TIMP-1 reversed the suppressed invasiveness of PEG10 siRNA-transduced JEG-3 cells. In conclusion, our study demonstrates that PEG10 plays an important role in trophoblast proliferation and promotes trophoblast invasion through TIMP-1.

Long noncoding RNA PEG10 regulates proliferation and invasion of esophageal cancer cells

Long chain noncoding RNAs (LncRNAs), a class of noncoding RNA nucleotides longer than 200 bp, have important roles in a variety of biological processes. Accumulating evidence has confirmed the involvement of LncRNAs in cancer initiation, development and progression. We investigated the expression of LncRNA PEG10 in a cohort of esophageal carcinomas to assess its impact on esophageal cancer cell proliferation, apoptosis and invasion. Quantitaive reverse transcription polymerase chain reaction assays were used to quantify LncRNA PEG10 expression levels in 43 paired EC samples and adjacent non-neoplastic tissues. Cell growth, apoptosis and Transwell invasion assays were used to evaluate the effects of LncRNA PEG10 on esophageal cancer cells. LncRNA PEG10 was expressed at higher levels in esophageal cancer tissues than in adjacent non-neoplastic tissues (P<0.05). This relatively high expression was significantly associated with the occurrence of lymph node metastases (P<0.05). Apoptosis and migration rates were significantly decreased in two esophageal cancer cell lines (EC9706 and KYSE150) transfected with si-LncRNA PEG10 (P<0.05). Downregulation of LncRNA PEG10 decreased the expression of PEG10 (P<0.05). Our results indicated that LncRNA PEG10 is upregulated in esophageal cancer tissues, and its downregulation inhibits proliferation and invasion, and promotes apoptosis in esophageal cancer cells. LncRNA PEG10 may serve as a therapeutic agent in esophageal cancer.