Tumor cell-derived exosomes mediating hsa_circ_0001739/lncRNA AC159540.1 facilitate liver metastasis in colorectal cancer.

BACKGROUND: The current study probed into how tumor cell-derived exosomes (Exos) mediated hsa_circ_0001739/lncRNA AC159540.1 to manipulate microRNA (miR)-218-5p/FTO-N6-methyladenosine (m6A)/MYC signal axis in liver metastasis in colorectal cancer (CRC). METHODS: hsa_circ_0001739 and lncRNA AC159540.1 were identified as the upstream regulator of miR-218-5p using ENCORI and LncBase databases. Expression patterns of miR-218-5p, hsa_circ_0001739, lncRNA AC159540.1, FTO, and MYC were detected, accompanied by loss-and-gain-of function assays to examine their effects on CRC cell biological functions. SW480 cells-derived Exos were purified, followed by in vitro studies to uncover the effect of hsa_circ_0001739/lncRNA AC159540. RESULTS: miR-218-5p was downregulated while hsa_circ_0001739/lncRNA AC159540.1 was upregulated in CRC tissues and cells. Silencing of hsa_circ_0001739/lncRNA AC159540.1 restrained the malignant phenotypes of CRC cells. Exos-mediated hsa_circ_0001739/lncRNA AC159540.1 competitively inhibited miR-218-5p to elevate FTO and MYC. The inducing role of Exos-mediated hsa_circ_0001739/lncRNA AC159540.1 in CRC was also validated in vivo. CONCLUSION: Conclusively, Exos-mediated circ_0001739/lncRNA AC159540.1 regulatory network is critical for CRC, offering a theoretical basis for CRC treatment.

sMicroRNA-28-5p acts as a metastasis suppressor in gastric cancer by targeting Nrf2.

The transcription factor nuclear factor (erythroid-2)-related factor 2 (Nrf2) can principally serve a mode of protection for both the normal cells and cancer cells from cellular stress, and elevates cancer cell survival. microRNA-28 (miR-28) has been involved in the regulation of Nrf2 expression in breast epithelial cells. However, no comprehensive analysis has been conducted regarding the function of miR-28-5p regulating Nrf2 in gastric cancer (GC). In this study, we aimed to evaluate their interaction and biological roles in the migration and invasion of GC cells. The expression of Nrf2 in the cancer tissues harvested from 42 patients with GC was examined by an array of molecular techniques comprising of Immunohistochemical staining, RT-qPCR and Western blot analysis. Kaplan-Meier method was adopted for analysis of the correlation of Nrf2 with the prognosis of GC patients. Interaction between miR-28-5p and Nrf2 was determined using the bioinformatics analysis and dual luciferase reporter gene assay. Gain- and loss-of-function studies of miR-28-5p and Nrf2 were conducted to elucidate their effects on GC cell migration, invasion and metastasis, as well as expression pattern of several epithelial-mesenchymal transition (EMT)-related proteins. Results indicated that the expression pattern of Nrf2 was significantly upregulated in GC tissues and indicative of poor prognosis of GC patients. miR-28-5p was verified to target Nrf2 and downregulate its expression. GC cells with overexpression of miR-28-5p or Nrf2 knockdown exhibited a marked reduction in the migrated and invasive abilities, along with the N-cadherin expression yet an increase of E-cadherin expression. Furthermore, miR-28-5p exerted an inhibitory function on the metastatic and tumorigenicity of GC cells. In conclusion, miR-28-5p is a comprehensive tumor suppressor that inhibits GC cell migration and invasion through repressing the Nrf2 expression. Therefore, miR-28-5p may serve as a potential biomarker for the prognosis of GC and a novel therapeutic target in advanced GC.

Germline Polymorphisms and Length of Survival of Nasopharyngeal Carcinoma: An Exome-Wide Association Study in Multiple Cohorts.

Germline polymorphisms are linked with differential survival outcomes in cancers but are not well studied in nasopharyngeal carcinoma (NPC). Here, a two-phase association study is conducted to discover germline polymorphisms that are associated with the prognosis of NPC. The discovery phase includes two consecutive hospital cohorts of patients with NPC from Southern China. Exome-wide genotypes at 246 173 single nucleotide polymorphisms (SNPs) are determined, followed by survival analysis for each SNP under Cox proportional hazard regression model. Candidate SNP is replicated in another two independent cohorts from Southern China and Singapore. Meta-analysis of all samples (n = 5553) confirms that the presence of rs1131636-T, located in the 3'-UTR of RPA1, confers an inferior overall survival (HR = 1.33, 95% CI = 1.20-1.47, P = 6.31 × 10-8). Bioinformatics and biological assays show that rs1131636 has regulatory effects on upstream RPA1. Functional studies further demonstrate that RPA1 promotes the growth, invasion, migration, and radioresistance of NPC cells. Additionally, miR-1253 is identified as a suppressor for RPA1 expression, likely through regulation of its binding affinity to rs1131636 locus. Collectively, these findings provide a promising biomarker aiding in stratifying patients with poor survival, as well as a potential drug target for NPC.

Prognostic implications of a molecular classifier derived from whole-exome sequencing in nasopharyngeal carcinoma.

The aim of this study was to use whole-exome sequencing to derive a molecular classifier for nasopharyngeal carcinoma (NPC) and evaluate its clinical performance. We performed whole-exome sequencing on 82 primary NPC tumors from Sun Yat-sen University Cancer Center (Guangzhou cohort) to obtain somatic single-nucleotide variants, indels, and copy number variants. A novel molecular classifier was then developed and validated in another NPC cohort (Hong Kong cohort, n = 99). Survival analysis was estimated by the Kaplan-Meier method and compared using the log-rank test. Cox proportional hazards model was adopted for univariate and multivariate analyses. We identified three prominent NPC genetic subtypes: RAS/PI3K/AKT (based on RAS, AKT1, and PIK3CA mutations), cell-cycle (based on CDKN2A/CDKN2B deletions, and CDKN1B and CCND1 amplifications), and unclassified (based on dominant mutations in epigenetic regulators, such as KMT2C/2D, or the Notch signaling pathway, such as NOTCH1/2). These subtypes differed in survival analysis, with good, intermediate, and poor progression-free survival in the unclassified, cell-cycle, and RAS/PI3K/AKT subgroups, respectively, among the Guangzhou, Hong Kong, and combined cohorts (n = 82, P = 0.0342; n = 99, P = 0.0372; and n = 181, P = 0.0023; log-rank test). We have uncovered genetic subtypes of NPC with distinct mutations and/or copy number changes, reflecting discrete paths of NPC tumorigenesis and providing a roadmap for developing new prognostic biomarkers and targeted therapies.

X-chromosome association study reveals genetic susceptibility loci of nasopharyngeal carcinoma.

BACKGROUND: The male predominance in the incidence of nasopharyngeal carcinoma (NPC) suggests the contribution of the X chromosome to the susceptibility of NPC. However, no X-linked susceptibility loci have been examined by genome-wide association studies (GWASs) for NPC by far. METHODS: To understand the contribution of the X chromosome in NPC susceptibility, we conducted an X chromosome-wide association analysis on 1615 NPC patients and 1025 healthy controls of Guangdong Chinese, followed by two validation analyses in Taiwan Chinese (n = 562) and Malaysian Chinese (n = 716). RESULTS: Firstly, the proportion of variance of X-linked loci over phenotypic variance was estimated in the discovery samples, which revealed that the phenotypic variance explained by X chromosome polymorphisms was estimated to be 12.63% (non-dosage compensation model) in males, as compared with 0.0001% in females. This suggested that the contribution of X chromosome to the genetic variance of NPC should not be neglected. Secondly, association analysis revealed that rs5927056 in DMD gene achieved X chromosome-wide association significance in the discovery sample (OR = 0.81, 95% CI 0.73-0.89, P = 1.49 × 10-5). Combined analysis revealed rs5927056 for DMD gene with suggestive significance (P = 9.44 × 10-5). Moreover, the female-specific association of rs5933886 in ARHGAP6 gene (OR = 0.62, 95%CI: 0.47-0.81, P = 4.37 × 10-4) was successfully replicated in Taiwan Chinese (P = 1.64 × 10-2). rs5933886 also showed nominally significant gender × SNP interaction in both Guangdong (P = 6.25 × 10-4) and Taiwan datasets (P = 2.99 × 10-2). CONCLUSION: Our finding reveals new susceptibility loci at the X chromosome conferring risk of NPC and supports the value of including the X chromosome in large-scale association studies.

Universal screening for Lynch syndrome in a large consecutive cohort of Chinese colorectal cancer patients: High prevalence and unique molecular features.

The prevalence of Lynch syndrome (LS) varies significantly in different populations, suggesting that ethnic features might play an important role. We enrolled 3330 consecutive Chinese patients who had surgical resection for newly diagnosed colorectal cancer. Universal screening for LS was implemented, including immunohistochemistry for mismatch repair (MMR) proteins, BRAFV600E mutation test and germline sequencing. Among the 3250 eligible patients, MMR protein deficiency (dMMR) was detected in 330 (10.2%) patients. Ninety-three patients (2.9%) were diagnosed with LS. Nine (9.7%) patients with LS fulfilled Amsterdam criteria II and 76 (81.7%) met the revised Bethesda guidelines. Only 15 (9.7%) patients with absence of MLH1 on IHC had BRAFV600E mutation. One third (33/99) of the MMR gene mutations have not been reported previously. The age of onset indicates risk of LS in patients with dMMR tumors. For patients older than 65 years, only 2 patients (5.7%) fulfilling revised Bethesda guidelines were diagnosed with LS. Selective sequencing of all cases with dMMR diagnosed at or below age 65 years and only of those dMMR cases older than 65 years who fulfill revised Bethesda guidelines results in 8.2% fewer cases requiring germline testing without missing any LS diagnoses. While the prevalence of LS in Chinese patients is similar to that of Western populations, the spectrum of constitutional mutations and frequency of BRAFV600E mutation is different. Patients older than 65 years who do not meet the revised Bethesda guidelines have a low risk of LS, suggesting germline sequencing might not be necessary in this population.

Genomic and transcriptomic landscapes of Epstein-Barr virus in extranodal natural killer T-cell lymphoma.

Extranodal natural killer T-cell lymphoma (nasal type; NKTCL) is an aggressive malignancy strongly associated with Epstein-Barr virus (EBV) infection. However, the role of EBV in NKTCL development is unclear, largely due to the lack of information about EBV genome and transcriptome in NKTCL. Here, using high-throughput sequencing, we obtained whole genome (n = 27) and transcriptome datasets (n = 18) of EBV derived from NKTCL tumor biopsies. We assembled 27 EBV genomes and detected an average of 1,152 single nucleotide variants and 44.8 indels (<50 bp) of EBV per sample. We also identified frequent focal EBV genome deletions and integrated EBV fragments in the host genome. Moreover, Phylogenetic analysis revealed that NKTCL-derived EBVs are closely clustered; transcriptome analysis revealed less activation of both latent and lytic genes and larger amount of T-cell epitope alterations in NKTCL, as compared with other EBV-associated cancers. Furthermore, we observed transcriptional defects of the BARTs miRNA by deletion, and the disruption of host NHEJ1 by integrated EBV fragment, implying novel pathogenic mechanisms of EBV. Taken together, we reported for the first time global mutational and transcriptional profiles of EBV in NKTCL clinical samples, revealing important somatic events of EBV and providing insights to better understanding of EBV's contribution in tumorigenesis.

High serum uric acid concentration predicts poor survival in patients with breast cancer.

BACKGROUND: Uric acid is a product of purine metabolism. Recently, uric acid has gained much attraction in cancer. In this study, we aim to investigate the clinicopathological and prognostic significance of serum uric acid concentration in breast cancer patients. METHODS: A total of 443 female patients with histopathologically diagnosed breast cancer were included. After a mean follow-up time of 56months, survival was analysed using the Kaplan-Meier method. To further evaluate the prognostic significance of uric acid concentrations, univariate and multivariate Cox regression analyses were applied. RESULTS: Of the clinicopathological parameters, uric acid concentration was associated with age, body mass index, ER status and PR status. Univariate analysis identified that patients with increased uric acid concentration had a significantly inferior overall survival (HR 2.13, 95% CI 1.15-3.94, p=0.016). In multivariate analysis, we found that high uric acid concentration is an independent prognostic factor predicting death, but insufficient to predict local relapse or distant metastasis. Kaplan-Meier analysis indicated that high uric acid concentration is related to the poor overall survival (p=0.013). CONCLUSIONS: High uric acid concentration predicts poor survival in patients with breast cancer, and might serve as a potential marker for appropriate management of breast cancer patients.

Genetic risk of extranodal natural killer T-cell lymphoma: a genome-wide association study.

BACKGROUND: Extranodal natural killer T-cell lymphoma (NKTCL), nasal type, is a rare and aggressive malignancy that occurs predominantly in Asian and Latin American populations. Although Epstein-Barr virus infection is a known risk factor, other risk factors and the pathogenesis of NKTCL are not well understood. We aimed to identify common genetic variants affecting individual risk of NKTCL. METHODS: We did a genome-wide association study of 189 patients with extranodal NKTCL, nasal type (WHO classification criteria; cases) and 957 controls from Guangdong province, southern China. We validated our findings in four independent case-control series, including 75 cases from Guangdong province and 296 controls from Hong Kong, 65 cases and 983 controls from Guangdong province, 125 cases and 1110 controls from Beijing (northern China), and 60 cases and 2476 controls from Singapore. We used imputation and conditional logistic regression analyses to fine-map the associations. We also did a meta-analysis of the replication series and of the entire dataset. FINDINGS: Associations exceeding the genome-wide significance threshold (p<5 × 10(-8)) were seen at 51 single-nucleotide polymorphisms (SNPs) mapping to the class II MHC region on chromosome 6, with rs9277378 (located in HLA-DPB1) having the strongest association with NKTCL susceptibility (p=4·21 × 10(-19), odds ratio [OR] 1·84 [95% CI 1·61-2·11] in meta-analysis of entire dataset). Imputation-based fine-mapping across the class II MHC region suggests that four aminoacid residues (Gly84-Gly85-Pro86-Met87) in near-complete linkage disequilibrium at the edge of the peptide-binding groove of HLA-DPB1 could account for most of the association between the rs9277378*A risk allele and NKTCL susceptibility (OR 2·38, p value for haplotype 2·32 × 10(-14)). This association is distinct from MHC associations with Epstein-Barr virus infection. INTERPRETATION: To our knowledge, this is the first time that a genetic variant conferring an NKTCL risk is noted at genome-wide significance. This finding underlines the importance of HLA-DP antigen presentation in the pathogenesis of NKTCL. FUNDING: Top-Notch Young Talents Program of China, Special Support Program of Guangdong, Specialized Research Fund for the Doctoral Program of Higher Education (20110171120099), Program for New Century Excellent Talents in University (NCET-11-0529), National Medical Research Council of Singapore (TCR12DEC005), Tanoto Foundation Professorship in Medical Oncology, New Century Foundation Limited, Ling Foundation, Singapore National Cancer Centre Research Fund, and the US National Institutes of Health (1R01AR062886, 5U01GM092691-04, and 1R01AR063759-01A1).

An extended genome-wide association study identifies novel susceptibility loci for nasopharyngeal carcinoma.

To further identify novel susceptibility loci of nasopharyngeal carcinoma (NPC), we here extended our previous genome-wide association study (GWAS) by boosting statistical power with larger sample size and validating more SNPs in the ranking list based on the GWAS P-values. The discovery stage consisting of 463,250 SNPs in 1,583 cases and 2,979 controls of southern Chinese ancestry revealed 1,257 top SNPs to be associated with NPC, which were brought forward for validation in 1,925 cases and 1,947 controls of southern Chinese. Further, 11 SNPs were selected for another independent validation in 3,538 cases and 3,644 controls of southern Chinese. The joint analysis with 7,046 cases and 8,570 controls resulted in two associations surpassing genome-wide significance (P < 5 × 10-8), including TERT-CLPTM1L at chromosome 5p15 (rs401681; P = 2.65 × 10-14; odds ratio, OR = 0.82) and CIITA at chromosome 16p13 (rs6498114; P = 4.01 × 10-9; OR = 0.87). Conditional analysis revealed that rs401681 accounts for all the tested associations at TERT-CLPTM1L locus, which has been linked with multiple cancers' susceptibilities. Moreover, bioinformatics analyses showed that both SNPs are located in the regulatory regions and correlated with the expression of nearby genes (rs401681 for CLPTM1L and TERT, and rs6498114 for CIITA). CLPTM1L and TERT have been implicated in cancers, and CIITA is considered as the "master control factor" for the expression of NPC-associated MHC class II genes. These suggested that both SNPs might be functional. Altogether, our findings expand our understanding of the genetic contribution to NPC risk and provide novel biological insights into NPC pathogenesis.

Genetic susceptibility to the endemic form of NPC.

Nasopharyngeal carcinoma (NPC) is a malignancy with remarkably high prevalence in East Asia. Lines of evidence have suggested the involvement of genetic lesions in the etiology of NPC, together with the contributions of Epstein-Barr virus infection and environmental exposures. Linkage and association studies, either based on candidate genes or genome-wide levels, have been conducted to dissect the genetic variants that contribute to NPC risk. This review summarizes the current findings of genetic susceptibility to NPC, and points out some future challenges on discovery of other risk variants to explain the missing heritability of NPC.

A GWAS Meta-analysis and Replication Study Identifies a Novel Locus within CLPTM1L/TERT Associated with Nasopharyngeal Carcinoma in Individuals of Chinese Ancestry.

BACKGROUND: Genetic loci within the major histocompatibility complex (MHC) have been associated with nasopharyngeal carcinoma (NPC), an Epstein-Barr virus (EBV)-associated cancer, in several GWAS. Results outside this region have varied. METHODS: We conducted a meta-analysis of four NPC GWAS among Chinese individuals (2,152 cases; 3,740 controls). Forty-three noteworthy findings outside the MHC region were identified and targeted for replication in a pooled analysis of four independent case-control studies across three regions in Asia (4,716 cases; 5,379 controls). A meta-analysis that combined results from the initial GWA and replication studies was performed. RESULTS: In the combined meta-analysis, rs31489, located within the CLPTM1L/TERT region on chromosome 5p15.33, was strongly associated with NPC (OR = 0.81; P value 6.3 × 10(-13)). Our results also provide support for associations reported from published NPC GWAS-rs6774494 (P = 1.5 × 10(-12); located in the MECOM gene region), rs9510787 (P = 5.0 × 10(-10); located in the TNFRSF19 gene region), and rs1412829/rs4977756/rs1063192 (P = 2.8 × 10(-8), P = 7.0 × 10(-7), and P = 8.4 × 10(-7), respectively; located in the CDKN2A/B gene region). CONCLUSIONS: We have identified a novel association between genetic variation in the CLPTM1L/TERT region and NPC. Supporting our finding, rs31489 and other SNPs in this region have been reported to be associated with multiple cancer sites, candidate-based studies have reported associations between polymorphisms in this region and NPC, the TERT gene has been shown to be important for telomere maintenance and has been reported to be overexpressed in NPC, and an EBV protein expressed in NPC (LMP1) has been reported to modulate TERT expression/telomerase activity. IMPACT: Our finding suggests that factors involved in telomere length maintenance are involved in NPC pathogenesis.

A single nucleotide polymorphism in the Epstein-Barr virus genome is strongly associated with a high risk of nasopharyngeal carcinoma.

BACKGROUND: Epstein-Barr virus (EBV) commonly infects the general population and has been associated with nasopharyngeal carcinoma (NPC), which has a high incidence in certain regions. This study aimed to address how EBV variations contribute to the risk of NPC. METHODS: Using logistic regression analysis and based on the sequence variations at EBV-encoded RPMS1, a multi-stage association study was conducted to identify EBV variations associated with NPC risk. A protein degradation assay was performed to characterize the functional relevance of the RPMS1 variations. RESULTS: Based on EBV-encoded RPMS1 variations, a single nucleotide polymorphism (SNP) in the EBV genome (locus 155391: G>A, named G155391A) was associated with NPC in 157 cases and 319 healthy controls from an NPC endemic region in South China [P < 0.001, odds ratio (OR) = 4.47, 95% confidence interval (CI) 2.71-7.37]. The results were further validated in three independent cohorts from the NPC endemic region (P < 0.001, OR = 5.20, 95% CI 3.18-8.50 in 168 cases vs. 241 controls, and P < 0.001, OR = 5.27, 95% CI 4.06-6.85 in 726 cases vs. 880 controls) and a non-endemic region (P < 0.001, OR = 7.52, 95% CI 3.69-15.32 in 58 cases vs. 612 controls). The combined analysis in 1109 cases and 2052 controls revealed that the SNP G155391A was strongly associated with NPC (P(combined) < 0.001, OR = 5.27, 95% CI 4.31-6.44). Moreover, the frequency of the SNP G155391A was associated with NPC incidence but was not associated with the incidences of other EBV-related malignancies. Furthermore, the protein degradation assay showed that this SNP decreased the degradation of the oncogenic RPMS1 protein. CONCLUSIONS: Our study identified an EBV variation specifically and significantly associated with a high risk of NPC. These findings provide insights into the pathogenesis of NPC and strategies for prevention.

Association of CELF2 polymorphism and the prognosis of nasopharyngeal carcinoma in southern Chinese population.

Nasopharyngeal carcinoma (NPC) is a malignancy with high metastatic potential and loco-regional recurrence. The overall survival of NPC has been limited from further improvement partly due to the lack of effective biomarker for accurate prognosis prediction and precise treatments. Here, in light of the implication of CELF gene family in cancer prognosis, we selected 112 tagging single nucleotide polymorphisms (SNPs) located in six members of the family and tested their associations with the clinical outcomes in a discovery cohort of 717 NPC patients. Survival analyses under multivariate cox proportional hazards model and Kaplan-Meier curve revealed five promising SNPs, which were further validated in another independent sample of 1,520 cases. Combined analysis revealed that SNP rs3740194 in CELF2 was significantly associated with the decreased risk of death with a Hazard ratio (HR) of 0.69 (95% confidence interval [CI] = 0.58-0.82, codominant model). Moreover, rs3740194 also showed a significant association with superior metastasis-free survival (HR = 0.69, 95% CI = 0.57-0.83, codominant model). Taken together, our findings suggested that genetic variant of rs3740194 in CELF2 gene might be a valuable predictor for NPC prognosis, and potentially useful in the personalized treatment of NPC.

NOP14 suppresses breast cancer progression by inhibiting NRIP1/Wnt/ß-catenin pathway.

NOP14, which is functionally conserved among eukaryotes, has been implicated in cancer development. Here, we show that NOP14 is poorly expressed in breast cancer cells and invasive breast cancer tissues. In vivo and in vitro studies indicated that NOP14 suppressed the tumorigenesis and metastasis of breast cancer cells. Further investigations revealed that NOP14 enhanced ERα expression and inhibited the Wnt/ß-catenin pathway by up-regulating NRIP1 expression. Survival analysis indicated that low NOP14 expression was significantly associated with poor overall survival (P = 0.0006) and disease-free survival (P = 0.0007), suggesting that NOP14 is a potential prognostic factor in breast cancer. Taken together, our findings reveal that NOP14 may suppress breast cancer progression and provide new insights into the development of targeted therapeutic agents for breast cancer.

Exome sequencing and digital PCR analyses reveal novel mutated genes related to the metastasis of pancreatic ductal adenocarcinoma.

Pancreatic ductal adenocarcinoma (PDAC) is one of the most malignant cancers with more than 94% mortality rate mainly due to the widespread metastases. To find out the somatically mutated genes related to the metastasis of PDAC, we analyzed the matched tumor and normal tissue samples from a patient diagnosed with liver metastatic PDAC using intensive exome capture-sequencing analysis (> 170× coverage). Searching for the somatic mutations that drive the clonal expansion of metastasis, we identified 12 genes with higher allele frequencies (AFs) of functional mutations in the metastatic tumor, including known genes KRAS and TP53 for metastasis. Of the 10 candidate genes, 6 (ADRB1, DCLK1, KCNH2, NOP14, SIGLEC1, and ZC3H7A), together with KRAS and TP53, were clustered into a single network (p value = 1 × 10(-22)) that is related to cancer development. Moreover, these candidate genes showed abnormal expression in PDAC tissues and functional impacts on the migration, proliferation, and colony formation abilities of pancreatic cancer cell lines. Furthermore, through digital PCR analysis, we revealed potential genomic mechanisms for the KRAS and TP53 mutations in the metastatic tumor. Taken together, our study shows the possibility for such personalized genomic profiling to provide new biological insight into the metastasis of PDAC.

A genome-wide association study in Han Chinese identifies new susceptibility loci for ankylosing spondylitis.

To identify susceptibility loci for ankylosing spondylitis, we performed a two-stage genome-wide association study in Han Chinese. In the discovery stage, we analyzed 1,356,350 autosomal SNPs in 1,837 individuals with ankylosing spondylitis and 4,231 controls; in the validation stage, we analyzed 30 suggestive SNPs in an additional 2,100 affected individuals and 3,496 controls. We identified two new susceptibility loci between EDIL3 and HAPLN1 at 5q14.3 (rs4552569; P = 8.77 × 10(-10)) and within ANO6 at 12q12 (rs17095830; P = 1.63 × 10(-8)). We also confirmed previously reported associations in Europeans within the major histocompatibility complex (MHC) region (top SNP, rs13202464; P < 5 × 10(-324)) and at 2p15 (rs10865331; P = 1.98 × 10(-8)). We show that rs13202464 within the MHC region mainly represents the risk effect of HLA-B*27 variants (including HLA-B*2704, HLA-B*2705 and HLA-B*2715) in Chinese. The two newly discovered loci implicate genes related to bone formation and cartilage development, suggesting their potential involvement in the etiology of ankylosing spondylitis.

Direct sequencing and characterization of a clinical isolate of Epstein-Barr virus from nasopharyngeal carcinoma tissue by using next-generation sequencing technology.

Epstein-Barr virus (EBV)-encoded molecules have been detected in the tumor tissues of several cancers, including nasopharyngeal carcinoma (NPC), suggesting that EBV plays an important role in tumorigenesis. However, the nature of EBV with respect to genome width in vivo and whether EBV undergoes clonal expansion in the tumor tissues are still poorly understood. In this study, next-generation sequencing (NGS) was used to sequence DNA extracted directly from the tumor tissue of a patient with NPC. Apart from the human sequences, a clinically isolated EBV genome 164.7 kb in size was successfully assembled and named GD2 (GenBank accession number HQ020558). Sequence and phylogenetic analyses showed that GD2 was closely related to GD1, a previously assembled variant derived from a patient with NPC. GD2 contains the most prevalent EBV variants reported in Cantonese patients with NPC, suggesting that it might be the prevalent strain in this population. Furthermore, GD2 could be grouped into a single subtype according to common classification criteria and contains only 6 heterozygous point mutations, suggesting the monoclonal expansion of GD2 in NPC. This study represents the first genome-wide analysis of a clinical isolate of EBV directly extracted from NPC tissue. Our study reveals that NGS allows the characterization of genome-wide variations of EBV in clinical tumors and provides evidence of monoclonal expansion of EBV in vivo. The pipeline could also be applied to the study of other pathogen-related malignancies. With additional NGS studies of NPC, it might be possible to uncover the potential causative EBV variant involved in NPC.

Correlation of Skp2 overexpression to prognosis of patients with nasopharyngeal carcinoma from South China.

S-phase kinase-associated protein 2 (Skp2), which plays a role in cell cycle regulation, is commonly overexpressed in a variety of human cancers and associated with poor prognosis. However, its role in nasopharyngeal carcinoma (NPC) is not well understood. In this study, we examined the clinical significance of Skp2, with a particular emphasis on overall survival (OS) and disease-free survival (DFS), in NPC cases in South China, where NPC is an epidemic. Additionally, we explored the function of Skp2 in maintaining a cancer stem cell-like phenotype in NPC cell lines. Skp2 expression was assessed for 127 NPC patients using tissue microarrays and immunohistochemistry and analyzed together with clinicopathologic features, OS, and DFS. Skp2 expression was detectable, or positive, in 75.6% of patients. Although there was no correlation between Skp2 and any clinicopathologic factor, Skp2 expression significantly portended inferior OS (P = 0.013) and DFS (P = 0.012). In the multivariate model, Skp2 expression remained significantly predictive of poor OS [P = 0.009, risk ratio (RR) = 4.06] and DFS (P = 0.008, RR = 3.56), and this was also true for clinical stage (P = 0.012 and RR=3.201 for OS; P = 0.002 and RR=1.94 for DFS) and sex (P = 0.016 and RR=0.31 for OS; P = 0.006 and RR = 0.27 for DFS). After Skp2 knockdown, a colony formation assay was used to evaluate the self-renewal property of stem-like cells in the NPC cell lines CNE-1 and CNE-2. The colony formation efficiency in CNE-1 and CNE-2 cells was decreased. In Skp2-transfected CNE-1 and CNE-2 cells, side population (SP) proportion was increased as detected by flow cytometry. Skp2 is an independent prognostic marker for OS and DFS in NPC. Skp2 may play a role in maintaining the cancer stem cell-like phenotype of NPC cell lines.