Tribofilm Formation of Zinc Dialkyldithiophosphate as Oil Additives Impregnated in Porous Polyimide under Different Contacts.

To improve the tribological properties of porous polyimide (PPI), ZDDP-mixed PAO4 was impregnated in PPI (denoted as ZPPI), and the tribological properties of ZPPI under single- and double-contacts were investigated. In the single-contact of ZPPI-steel, a rough and thick tribofilm was formed on the steel ball, which could protect the steel surface but resulted in large fluctuations in the friction coefficient. In the double-contact of ZPPI-steel-steel, ZDDP formed a uniform and thinner tribofilm on steel surfaces, leading to a lower friction. ZDDP could inhibit the formation of iron oxides significantly in the double-contact, while the antioxidant effect of ZDDP in the single-contact of ZPPI-steel was not obvious. ZnS and ZnO generated from ZDDP were adsorbed in the ZPPI pores, which aggravated the blackening of the ZPPI worn surface.

The Predictive Value of CD3+/CD8+ Lymphocyte Infiltration and PD-L1 Expression in Colorectal Cancer.

AIM: The immune system plays an important role in tumor development and treatment. In this study, we aimed to determine the relationships among the expressions of PD-L1, CD3, CD8, MMR proteins, clinicopathological features, and prognosis of CRC. METHODS: Immunohistochemistry was used to determine the expression of PD-L1, CD3, and CD8 in 771 patients with CRC. RESULTS: The expression of PD-L1 in TC was related to the right colon, adenocarcinoma, and dMMR, and in IC, it was related to younger CRC patients and the TNM stage. The expression of CD3 and CD8 in tumor-infiltrating lymphocytes was related to lymph node metastasis and the TNM stage. The expression of PD-L1 in TC and IC was correlated with the infiltration of CD3+ and CD8+ lymphocytes. Univariate survival analysis showed that the expression of PD-L1 in TC, IC, and dMMR was related to a better prognosis. Multivariate survival analysis showed that age, TNM stage, and dMMR were independent prognostic factors for CRC. The OS of the chemotherapy was significantly higher than that of the non-chemotherapy in III-IV TNM stage patients; CRC patients with positive PD-L1 expression in TC or IC and dMMR did not benefit from chemotherapy. CONCLUSIONS: PD-L1 expression in TC and IC was closely related to the density of CD3 and CD8 infiltration in tumor-infiltrating lymphocytes. The expression of CD3 and CD8 in tumor-infiltrating lymphocytes and the expression of PD-L1 in IC were linked to the TNM stage of CRC patients. PD-L1 expression in TC and IC and MMR status may act as an important biomarker for guiding the postoperative treatment of III-IV TNM stage CRC patients.

Immunosuppressive effect of small extracellular vesicle PD-L1 is restricted by co-expression of CD80.

BACKGROUND: The PD-L1 on tumor cell-derived small extracellular vesicles (sEVs) can suppress the proliferation and cytokine production of T cells. However, PD-L1 can also be expressed by non-tumor cells. The present study is designed to test whether immunocytes release immunosuppressive PD-L1-positive sEVs. METHODS: sEVs were isolated from different clinical samples of head and neck squamous cell carcinoma (HNSCC) patients, the level and cellular origins of PD-L1-positive sEVs were assessed. Co-expression of CD80 on PD-L1-positive sEVs was examined to evaluate the immunosuppressive and tumor-promotive effects. RESULTS: PD-L1-positive sEVs in HNSCC patients had various cellular origins, including tumor cell, T cell, B cell, dendritic cell and monocyte/macrophage. However, PD-L1-positive sEVs derived from immune cells did not exert immunosuppressive functions due to the co-expression of CD80. It was verified that co-expression of CD80 disrupted the binding of sEV PD-L1 to its receptor PD-1 on T cells and attenuated the immunosuppression mediated by sEV PD-L1 both in vitro and in vivo. CONCLUSION: The study suggests that PD-L1-positive sEVs have the cellular origin and functional heterogeneity. Co-expression of CD80 could restrict the immunosuppressive effect of sEV PD-L1. A greater understanding of PD-L1-positive sEV subsets is required to further improve their clinical application.

Systemic development of wheat-Thinopyrum elongatum translocation lines and their deployment in wheat breeding for Fusarium head blight resistance.

Fusarium head blight (FHB), mainly caused by Fusarium graminearum, is one of the most destructive diseases of wheat (Triticum aestivum) around the world. FHB causes significant yield losses and reduces grain quality. The lack of resistance resources is a major bottleneck for wheat FHB resistance breeding. As a wheat relative, Thinopyrum elongatum contains many genes that can be used for wheat improvement. Although the novel gene Fhb-7EL was mapped on chromosome 7EL of Th. elongatum, successful transfer of the FHB resistance gene into commercial wheat varieties has not been reported. In this study, we developed 836 wheat-Th. elongatum translocation lines of various types by irradiating the pollen of the wheat-Th. elongatum addition line CS-7EL at the flowering stage, among which 81 were identified as resistant to FHB. By backcrossing the FHB-resistant lines with the main cultivar Jimai 22, three wheat-Th. elongatum translocation lines, Zhongke 1878, Zhongke 166, and Zhongke 545, were successfully applied in wheat breeding without yield penalty. Combining karyotype and phenotype analyses, we mapped the Fhb-7EL gene to the distal end of chromosome 7EL. Five molecular markers linked with the FHB resistance interval were developed, which facilitates molecular marker-assisted breeding. Altogether, we successfully applied alien chromatin with FHB resistance from Th. elongatum in wheat breeding without yield penalty. These newly developed FHB-resistant wheat-Th. elongatum translocation lines, Zhongke 1878, Zhongke 166, and Zhongke 545, can be used as novel resistance resources for wheat breeding.

Bioinspired gelatin nano-film implanted into composite scaffold exhibiting both expandable adhesion and enhanced proliferation.

Tissue engineering technology provides a new treatment to the cartilage damage. Recent progress has focused on coating strategies with the printed scaffold surface, using various materials such as bioactive nanocomposites. However, the fracture and exfoliation of printed scaffolds remain challenges due to their poor adhesion on smooth substrates. These limitations can be offset by developing a versatile film. Here, inspired by the mechanism of the wet adhesion of snails, we introduced a biomimetic nanoscale gelatin film between a smooth conductive slide and a scaffold, which enhanced early cell adhesion rates through water absorption, swelling and adhesion. A bionic technique of preparing gelatin nanofilms and PVP/PCL 3D scaffolds, which involved E-Jet atomization deposition and E-Jet printing techniques based on the electrohydrodynamic effect, was investigated. It is found that the composite scaffold with 400 nm gelatin nanofilm significantly enhances cell attachment (from 62 % to 87 %) and proliferation (increased 6.5 times in 7 days). Collectively, this study highlights the combination of biomimetic nanoscale adhesive film in promoting cell adhesion and cartilage differentiation, which benefiting from water absorption and swelling of gelatin nanofilm. This work provides a new idea for the potential application in the orthopedics field.

Stabilizing and upregulating Axin with tankyrase inhibitor reverses 5-fluorouracil chemoresistance and proliferation by targeting the WNT/caveolin-1 axis in colorectal cancer cells.

Chemoresistance is a main obstacle for colorectal cancer treatment. In this study, we evaluated the effects and mechanisms of the WNT/ß-catenin signaling pathway on the chemoresistance of SW480 and SW620 colorectal cancer cells. The activity of ß-catenin was activated/inhibited by the small molecule compound GSK-3 inhibitor 6-bromo-indirubin-3'-oxime and the tankyrase inhibitor XAV939. The downstream target genes of the WNT/ß-catenin signaling pathway were screened using a cDNA microarray and bioinformatics analysis. Apoptosis induced by 5-Fu, cell cycle distribution and expression levels of WNT/ß-catenin/TCF12/caveolin-1 and multidrug resistance proteins were examed by flow cytometry and western blot after ß-catenin activation/inhibition and caveolin-1 overexpression/interference. The effect and mechanism of XAV939 on proliferation and apoptosis induced by 5-Fu in xenograft tumors of nude mice were evaluated by immunohistochemistry and TUNEL staining. 6-Bromo-indirubin-3'-oxime treatment increased ß-catenin expression by regulating GSK-3ß phosphorylation, accompanied by upregulation of TCF12, caveolin-1, P-gp, and MRP2 and downregulation of apoptosis induced by 5-Fu. Conversely, XAV939 treatment decreased ß-catenin expression by upregulating Axin, accompanied by downregulation of TCF12, Caveolin-1, P-gp, and MRP2 and upregulation of apoptosis induced by 5-Fu. The caveolin-1 gene was identified as an important downstream gene of the WNT/ß-catenin signaling pathway. Caveolin-1 overexpression upregulated ß-catenin expression, increased P-gp and MRP2 expression and decreased apoptosis induced by 5-Fu; conversely, caveolin-1 interference caused the opposite effects. In addition, in vivo experiments showed that XAV939 treatment reduced ß-catenin expression, increased apoptosis induced by 5-Fu and repressed xenograft tumor growth. Our findings suggested that inhibition of WNT/ß-catenin/TCF12/caveolin-1 provides a new promising therapeutic strategy for colorectal cancer treatment.

The predictive value and correlation of ß-catenin, CMTM6, and PD-L1 expression in colorectal cancer.

CMTM6 is a major regulator of PD-L1 expression. Aberrant Wnt pathway signaling occurs in most sporadic colorectal cancers (CRC). However, the significance and correlation of ß-catenin, CMTM6, and PD-L1 immunohistochemical expression in CRC is still unknown and need to be further verified. We evaluated the expression levels of ß-catenin, CMTM6, PD-L1, and MMR (mismatch repair) proteins by immunohistochemistry in CRC tissue microarray (TMA), and evaluated the association among ß-catenin, CMTM6, PD-L1 expression, MMR status, and clinicopathological features in 704 CRC patients. Positive expression of PD-L1 in tumor cells (TC) is associated with more frequent dMMR (mismatch repair deficient) status, CMTM6 expression, right colon, and younger CRC patients. The expression of PD-L1 in tumor-infiltrating immune cells (IC) is associated with a higher frequency of adenocarcinoma, ß-catenin, and CMTM6 expression. In univariate analysis, age, histological subtype, histologic grade, lymphatic metastasis, TNM stage, MMR status, and expression of PD-L1 protein in IC were significantly associated with the overall survival. In multivariate analysis, age, histologic grade, TNM stage, MMR status, and expression of PD-L1 protein in IC were independent prognostic factors. The overall survival of the adjuvant chemotherapy group was significantly higher than those non-chemotherapy in TNM stage III-IV CRC patients, but no significant overall survival improvement was found in the positive PD-L1 in TC, positive PD-L1 in IC, positive CMTM6, low ß-catenin expression, or dMMR status subgroups. Expression of CMTM6 and PD-L1 in CRC are positively associated with ß-catenin and reliable biomarkers for the prediction of responding to chemotherapy. The expression of ß-catenin/CMTM6/PD-L1 and MMR status may be valuable biomarkers for guiding different treatment strategies in CRC patients.

Biomimetic Water-Repelling Surfaces with Robustly Flexible Structures.

Biomimetic liquid-repelling surfaces have been the subject of considerable scientific research and technological application. To design such surfaces, a flexibility-based oscillation strategy has been shown to resolve the problem of liquid-surface positioning encountered by the previous, rigidity-based asymmetry strategy; however, its usage is limited by weak mechanical robustness and confined repellency enhancement. Here, we design a flexible surface comprising mesoscale heads and microscale spring sets, in analogy to the mushroomlike geometry discovered on springtail cuticles, and then realize this through three-dimensional projection microstereolithography. Such a surface exhibits strong mechanical robustness against ubiquitous normal and shear compression and even endures tribological friction. Simultaneously, the surface elevates water repellency for impacting droplets by enhancing impalement resistance and reducing contact time, partially reaching an improvement of ∼80% via structural tilting movements. This is the first demonstration of flexible interfacial structures to robustly endure tribological friction as well as to promote water repellency, approaching real-world applications of water repelling. Also, a flexibility gradient is created on the surface to directionally manipulate droplets, paving the way for droplet transport.

Author Correction: Epstein-Barr virus-encoded microRNA BART1 induces tumour metastasis by regulating PTEN-dependent pathways in nasopharyngeal carcinoma.

An amendment to this paper has been published and can be accessed via a link at the top of the paper.

Lnc-M2 controls M2 macrophage differentiation via the PKA/CREB pathway.

Long noncoding RNAs (lncRNAs) play an indispensable role in the process of M1 macrophage via regulating the development of macrophages and their responses to bacterial pathogens and viral infections. However, there are few studies on the lncRNA-mediated functions and regulatory mechanisms of M2 macrophage polarization. In this study, we found a number of differentially expressed lncRNAs between human monocyte derived M0 and M2 macrophages according to array analysis and quantitative polymerase chain reaction (qPCR) validation. The lncRNA RP11-389C8.2 (we named lnc-M2 in this study) was observed to be highly expressed in M2 macrophages. In Situ Localization and Quantification Analysis showed that lnc-M2 was expressed in the nucleus and cytosolic compartments of M2 macrophages. Notably, lnc-M2 knockdown enhanced the phagocytic ability of M2 macrophages. Ulteriorly, the results of RNA-Protein interaction experiments indicated that protein kinase A (PKA) was a lnc-M2 associated RNA-binding protein (RBP). Western blot showed that phosphorylated cAMP response element binding protein (p-CREB), a well-known key downstream transcription factor of PKA, was lowly phosphorylated in lnc-M2-silencing M2 macrophages. Furthermore, we found that transcriptional factor Signal Transducer And Activator Of Transcription 3 (STAT3) promoted lnc-M2 transcription along with the up-regulation of epigenetic histone modification markers at the lnc-M2 promoter locus, indicating that STAT3 activated lnc-M2 and eventually facilitated the process of M2 macrophage differentiation via the PKA/CREB pathway. Collectively, our date provide evidence that the transcription factor STAT3 can promote the transcription of lnc-M2 and facilitated the process of M2 macrophage differentiation via the PKA/CREB pathway. This study highlights a novel mechanism underlying the M2 macrophage differentiation.

[Evaluation of pre-harvest sprouting resistance of wheat varieties from different ecological regions.] / 不同生态区小麦品种的穗发芽抗性评价.

The pre-harvest sprouting (PHS) resistance of 137 wheat varieties from different regions was evaluated and the relative germination index (RGI) was calculated. The relationships between PHS and grain quality traits, amylase activity and related gene expression level of these varieties were analyzed. The results showed that wheat varieties from the middle and lower reaches of Yangtze River Valley winter wheat region had the lowest RGI value and the highest ratio of resistant pre-harvest sprouting wheat varieties, followed by the varieties from the upper reach of Yangtze River Valley winter wheat region and from the Yellow and Huai River Valley. Red-grain wheat had lower RGI than white-grain wheat. RGI was positively correlated with seed length, seed width, and spikelet number, but not correlated with other grain traits (panicle type, ear color, ear length, and spikelet density, grain per spike and 1000-grain weight). RGI was negatively associated with the test weight, dough development time, and flour yield, but not with other quality indices (protein content, wet gluten content, water absorption, stability time, sedimentation, extension area, extensibility and max resistance). Amylase activity of different varieties increased with seed imbibition time. RGI was positively associated with α-amylase activity after germinating for 24-72 hours. The cluster analysis results of resistant varieties were consistent with the PHS resistance evaluation after 48 hours. RGI was positively associated with the related gene expression with seed imbibition time.

Chinese Wheat Mosaic Virus-Induced Gene Silencing in Monocots and Dicots at Low Temperature.

Virus-induced gene silencing (VIGS) is an important tool for functional genomics studies in plants. With this method, it is possible to target most endogenous genes and downregulate the messenger RNA (mRNA) in a sequence-specific manner. Chinese wheat mosaic virus (CWMV) has a bipartite, single-strand positive RNA genome, and can infect both wheat and Nicotiana benthamiana, and the optimal temperature for systemic infection in plants is 17°C. To assess the potential of the virus as a vector for gene silencing at low temperature, a fragment of the N. benthamiana or wheat phytoene desaturase (PDS) gene was expressed from a modified CWMV RNA2 clone and the resulting photo bleaching in infected plants was used as a reporter for silencing. Downregulation of PDS mRNA was also measured by quantitative reverse-transcriptase polymerase chain reaction (RT-qPCR). In experiments using fragments of PDS ranging from 500 to 1500 nucleotides, insert length influenced the stability and the efficiency of VIGS. The CWMV induced silencing system was also used to suppress miR165/166 and miR3134a through expression of miRNA target mimics. The relative expression levels of mature miR165/166 and miR3134a decreased whereas the transcript levels of their target genes increased. Interestingly, we also found the CWMV-induced silencing system was more efficient compare with the vector based on Barley stripe mosaic virus (BSMV) or Foxtail mosaic virus (FoMV) in wheat or the vector based on TRV in N. benthamiana at 17°C. In summary, the CWMV vector is effective in silencing endogenous genes and miRNAs at 17°C, thereby providing a powerful tool for gene function analysis in both N. benthamiana and wheat at low temperature.

A regulatory mutant on TRIM26 conferring the risk of nasopharyngeal carcinoma by inducing low immune response.

The major histocompatibility complex (MHC) is most closely associated with nasopharyngeal carcinoma (NPC), but the complexity of its genome structure has proven challenging for the discovery of causal MHC loci or genes. We conducted a targeted MHC sequencing in 40 Cantonese NPC patients followed by a two-stage replication in 1065 NPC cases and 2137 controls of Southern Chinese descendent. Quantitative RT-PCR analysis (qRT-PCR) was used to detect gene expression status in 108 NPC and 43 noncancerous nasopharyngeal (NP) samples. Luciferase reporter assay and chromatin immunoprecipitation (ChIP) were used to assess the transcription factor binding site. We discovered that a novel SNP rs117565607_A at TRIM26 displayed the strongest association (OR = 1.909, Pcombined = 2.750 × 10-19 ). We also observed that TRIM26 was significantly downregulated in NPC tissue samples with genotype AA/AT than TT. Immunohistochemistry (IHC) test also found the TRIM26 protein expression in NPC tissue samples with the genotype AA/AT was lower than TT. According to computational prediction, rs117565607 locus was a binding site for the transcription factor Yin Yang 1 (YY1). We observed that the luciferase activity of YY1 which is binding to the A allele of rs117565607 was suppressed. ChIP data showed that YY1 was binding with T not A allele. Significance analysis of microarray suggested that TRIM26 downregulation was related to low immune response in NPC. We have identified a novel gene TRIM26 and a novel SNP rs117565607_A associated with NPC risk by regulating transcriptional process and established a new functional link between TRIM26 downregulation and low immune response in NPC.

Low concentration trifluoperazine promotes proliferation and reduces calcium-dependent apoptosis in glioma cells.

Glioma patients constitute the greatest percentage of depressed neoplasm patients. These patients often require antidepressant treatment, but the effect of antidepressant drugs on glioma cells requires further evaluation. In the present study, we evaluated the effect of trifluoperazine (TFP) on the proliferation and apoptosis of glioma cells. Transcriptomic and bioinformatics analysis results suggested that antidepressant drugs, especially TFP, may upregulate the drug-resistant ability of glioma cells. A low concentration of TFP upregulated the viability of glioma cells. Colony formation and EdU assays confirmed that TFP treatment accelerates glioma cell proliferation, but no significant difference was found in the cell cycle distribution of glioma cells after treatment with TFP or control. Flow cytometry and TUNEL staining results suggested that TFP treatment decreased apoptosis in glioma cells. In addition, TFP treatment downregulated the intracellular Ca2+ concentration of glioma cells. In vivo experimental results indicated that TFP treatment promoted proliferation and reduced apoptosis in xenograft tumours in nude mice. Taken together, our results suggest that a low concentration of TFP promotes proliferation and reduces apoptosis in glioma cells both in vitro and in vivo. The potential harmful effects of antidepressant drugs on gliomas require further evaluation before their use in glioma patients.

GSK-3ß inhibitor 6-bromo-indirubin-3'-oxime promotes both adhesive activity and drug resistance in colorectal cancer cells.

Multi-targets inhibitor 6-bromo-indirubin-3'-oxime (BIO) has diverse biological effects on cancer cells. The key component of the ß-catenin destruction complex glycogen synthase kinase 3ß (GSK-3ß), one of the major target for BIO, polyubiquitination and degradation of the main oncoprotein ß-catenin in colorectal cancer (CRC). In the present study, we evaluated the effect of BIO on drug resistance and biological properties of CRC cells. Whole-genome transcriptional profiling revealed that differentially expressed genes were mainly centered on well-characterized signaling pathways including stem cell, cell adhesion and cell growth in BIO-treated CRC cells. BIO treatment downregulated migration and invasion abilities of CRC cells, accompanying with MMP-9 downregulated and E-cadherin upregulated CRC cells. BIO treatment decreased apoptosis induced by 5-Fu/DDP in CRC SW480 cells. In addition, BIO treatment reversed the 5-Fu-induced CD133+ cell downregulation trend in CRC SW620 cells. After incubation with BIO, the expression levels of EpCAM, TERT and DCAMKL-1 proteins were upregulated in CRC cells. BIO treatment downregulated the activity of GSK-3ß, upregulated and transported ß-catenin to the nucleus in CRC cells. Our findings reveal that BIO treatment upregulated stemness, adhesive and chemoresistance of CRC cells. GSK-3ß inhibition and WNT/ß-catenin activation by BIO, may partly result in the biological behavior alterations in CRC cells.

miR-181a-5p, an inducer of Wnt-signaling, facilitates cell proliferation in acute lymphoblastic leukemia.

Uncontrolled Wnt signaling causes leukemia. Inactivation of Wnt antagonists could play an important role in leukemia progression by activating the Wnt/ß-catenin pathway. Wnt inhibitory factor-1 (WIF1) is one of the important Wnt antagonists. Few miRNAs have been reported to directly target this gene in hematopoiesis. Here, we observed that miR-181a-5p expression was markedly overexpressed in several leukemia cell lines and acute lymphoblastic leukemia (ALL) samples compared with that noted in normal peripheral blood mononuclear cells. MTT assays, soft agar colony formation assays and flow cytometry analysis collectively showed that ectopic expression of miR-181a-5p induced ALL cell growth and proliferation. Furthermore, a mechanistic study disclosed that miR-181a-5p directly downregulated WIF1 expression by binding to its 3'-UTR, and further activated Wnt/ß­catenin signaling. These findings provide a novel mechanistic insight into the role of miR-181a-5p in ALL cell growth and proliferation and implicate miR-181a-5p as an attractive candidate for ALL therapy.

Comparative profiling between primary colorectal carcinomas and metastases identifies heterogeneity on drug resistance.

Metastases cause recurrence and mortality for patients with colorectal carcinomas (CRC). In present study, we evaluated heterogeneity on drug resistance and its underlying mechanism between metastatic and primary CRC. Immunohistochemical results from clinical tissue microarray (TMA) suggested that the expression concordance rates of cancer stem cells (CSCs) and drug resistance relative proteins between lymph-node metastatic and primary CRC foci were low. The apoptotic and proliferation indexes in metastasis CRC specimens were decreased compared with primary. In vitro experimental results indicated that the migration and invasion abilities were upregulated in metastatic cells SW620 compared with primary cells SW480, the cellular efflux ability and WNT/ß-catenin activity were also upregulated in SW620 cells. After 5-fluorouracil (5-Fu) treatment, the reduction in the proportion of cell apoptosis, CD133 and TERT expression levels in SW620 were lower than that in SW480 cells. Bioinformatics analysis in whole-genome transcriptional profiling results between metastatic and primary CRC cells suggested that differentially expressed genes were mainly centered on well-characterized signaling pathways including WNT/ß-catenin, cell cycle and cell junction. Collectively, heterogeneity of drug resistant was present between metastatic and primary CRC specimens and cell lines, the abnormal activation of WNT/ß-catenin signaling pathway could be a potential molecular leading to drug resistant ability enhancing in metastatic CRC cells.

Higher methylation intensity induced by EBV LMP1 via NF-κB/DNMT3b signaling contributes to silencing of PTEN gene.

Phosphatase and tensin homolog (PTEN) is a major tumor suppressor and usually silenced via the deletion, insertion and mutation. We previously discovered its inactivation via aberrant CpG island methylation. Here, we provide further evidence that EBV latent membrane protein 1(LMP1) can induce a higher intensity of DNA methylation at PTEN CpG islands, inactivating PTEN at the cellular and molecular level. Initially, increased methylation intensity of PTEN CpG islands was observed in EBV-infected nasopharyngeal carcinoma (NPC) cells, accompanied by decreased PTEN expression. In NPC tissue samples showing the methylation at PTEN promoter, LMP1 was highly expressed in higher methylation intensity group relative to lower intensity group, and DNA methyltransferase 3b (DNMT3b) expression was positively correlated with LMP1 expression. Moreover, transfection of LMP1 gene into EBV-negative NPC cells demonstrated that LMP1 up-regulated DNMT3b expression, leading to a higher intensity of PTEN CpG island methylation. Mechanistically, computational prediction and luciferase reporter assay identified a functional NF-κB binding site on DNMT3b promoter and the mutated NF-κB binding site abolished LMP1-mediated DNMT3b activation. Chromatin immunoprecipitation displayed that NF-κB p65 subunit constitutively bound to DNMT3b promoter, supporting the activation of DNMT3b by EBV LMP1 via NF-κB signaling. Furthermore, the expression level of DNMT3b was observed to be increased in the nuclei of LMP1-expressing NPC cells, and a NF-κB inhibitor, PDTC, counteracted LMP1-mediated DNMT3b overexpression. Thus, this study first reports that LMP1-mediated NF-κB can up-regulate DNMT3b transcription, thereby leading to relatively higher methylation intensity at PTEN CpG islands, and ultimately silencing major tumor suppressor PTEN.