Efficacy and Safety of Locoregional Radiotherapy With Chemotherapy vs Chemotherapy Alone in De Novo Metastatic Nasopharyngeal Carcinoma: A Multicenter Phase 3 Randomized Clinical Trial

Importance

The role of locoregional radiotherapy in patients with de novo metastatic nasopharyngeal carcinoma (mNPC) is unclear.

Objective

To investigate the efficacy and safety of locoregional radiotherapy in de novo mNPC.

Design, Setting, and Participants

Patients with biopsy-proven mNPC, who demonstrated complete or partial response (RECIST v1.1) following 3 cycles of cisplatin and fluorouracil chemotherapy, were enrolled. Eligible patients were randomly assigned (1:1) to receive either chemotherapy plus radiotherapy or chemotherapy alone. Overall, 126 of 173 patients screened were eligible to the study, and randomized to chemotherapy plus radiotherapy (n = 63) or chemotherapy alone (n = 63). Median (IQR) follow-up duration was 26.7 (17.2-33.5) months.

Interventions

The chemotherapy regimens were fluorouracil continuous intravenous infusion at 5 g/m2 over 120 hours and 100 mg/m2 intravenous cisplatin on day 1, administered every 3 weeks for 6 cycles. Patients assigned to the chemotherapy plus radiotherapy group received intensity-modulated radiotherapy (IMRT) after chemotherapy.

Main Outcomes and Measures

The primary end point of the study was overall survival (OS). The secondary end point was progression-free survival (PFS) and safety.

Results

Overall, 126 patients were enrolled (105 men [83.3%] and 21 women [16.7%]; median [IQR] age, 46 [39-52] years). The 24-month OS was 76.4% (95% CI, 64.4%-88.4%) in the chemotherapy plus radiotherapy group, compared with 54.5% (95% CI, 41.0%-68.0%) in the chemotherapy-alone group. The study met its primary end point of improved OS (stratified hazard ratio [HR], 0.42; 95% CI, 0.23-0.77; P = .004) in favor of chemotherapy plus radiotherapy. Progression-free survival was also improved in the chemotherapy plus radiotherapy group compared with the chemotherapy-alone group (stratified HR, 0.36; 95% CI, 0.23-0.57). No significant differences in acute hematological or gastrointestinal toxic effects were observed between the treatment arms. The frequency of acute grade 3 or higher dermatitis, mucositis, and xerostomia was 8.1%, 33.9%, and 6.5%, respectively, in the chemotherapy plus radiotherapy group. The frequency of late severe grade 3 or higher hearing loss and trismus was 5.2% and 3.4%, respectively, in the chemotherapy plus radiotherapy group.

Conclusions and Relevance

In this randomized clinical trial, radiotherapy added to chemotherapy significantly improved OS in chemotherapy-sensitive patients with mNPC.

Trial Registration

ClinicalTrials.gov Identifier: NCT02111460.

Effect of dietary taurine supplementation on metabolome variation in plasma of Nile tilapia

Taurine has been considered as an essential nutrient for many aquaculture species. While dietary taurine supplementation is highly recommended, novelty studies on taurine metabolism in fish are needed. The present study aimed to provide insight into the molecular mechanisms involved in multiple metabolome changes in Nile tilapia (Oreochromis niloticus) by studying plasma metabolic profile changes in response to graded levels of dietary taurine supplementation. The analysis used proton nuclear magnetic resonance-based metabolomics. Four groups of tilapias were fed with four diets supplemented with 0.0, 0.4, 0.8 and 1.2% taurine for 84 days. Fish plasma was sampled at multiple time points to provide an accurate snapshot of specific metabolic profiles during growth. Under the effect of taurine supplementation, 21 and 12 metabolites in tilapia plasma shown significant changes in terms of time-dependence and diet-dependence, respectively. These metabolic changes in tilapia plasma were mainly associated with energy and amino acid metabolism, lipids, nucleotides and protein metabolism. The results indicate that 0.8% taurine supplementation could significantly improve the carbohydrate synthesis, protein digestion and absorption, and fat deposition of tilapia and thereby promoted growth and development of tilapia.

Genome-wide association study identifies genetic susceptibility loci and pathways of radiation-induced acute oral mucositis

Background

Radiation-induced oral mucositis (OM) is one of the most common acute complications for head and neck cancer. Severe OM is associated with radiation treatment breaks, which harms successful tumor management. Radiogenomics studies have indicated that genetic variants are associated with adverse effects of radiotherapy.

Methods

A large-scale genome-wide scan was performed in 1467 nasopharyngeal carcinoma patients, including 753 treated with 2D-CRT from Genetic Architecture of the Radiotherapy Toxicity and Prognosis (GARTP) cohort and 714 treated with IMRT (192 from the GARTP and 522 newly recruited). Subgroup analysis by radiotherapy technique was further performed in the top associations. We also performed physical and regulatory mapping of the risk loci and gene set enrichment analysis of the candidate target genes.

Results

We identified 50 associated genomic loci and 64 genes via positional mapping, expression quantitative trait locus (eQTL) mapping, chromatin interaction mapping and gene-based analysis, and 36 of these loci were replicated in subgroup analysis. Interestingly, one of the top loci located in TNKS, a gene relevant to radiation toxicity, was associated with increased OM risk with OR = 3.72 of the lead SNP rs117157809 (95% CI 2.10–6.57; P = 6.33 × 10⁻⁶). Gene set analyses showed that the 64 candidate target genes were enriched in the biological processes of regulating telomere capping and maintenance and telomerase activity (Top P = 7.73 × 10⁻⁷).

Conclusions

These results enhance the biological understanding of radiotherapy toxicity. The association signals enriched in telomere function regulation implicate the potential underlying mechanism and warrant further functional investigation and potential individual radiotherapy applications.

Long-Term Survival and Prognostic Factors in Locoregionally Advanced Nasopharyngeal Carcinoma Patients Treated with TPF Induction Chemotherapy followed by Cisplatin-Combined Concurrent Chemoradiotherapy

Purpose: The objective of this study was to report long-term results of docetaxel, cisplatin, and 5-fluorouracil (TPF) induction chemotherapy followed by concurrent chemoradiotherapy (CCRT) in patients with locoregionally advanced nasopharyngeal carcinoma (NPC) and identify prognostic factors for this group of patients. Materials and Methods: From December 2010 to January 2015, 109 patients with locoregionally advanced (III-IVB) NPC were included. Patients were scheduled to complete TPF induction chemotherapy followed by cisplatin based CCRT. Failure-free survival (FFS), overall survival (OS), locoregional failure-free survival (LRFFS) and distant failure-free survival (DFFS) served as clinical outcomes. Kaplan-Meier method, Cox proportional hazards model and receiver operating characteristic (ROC) curves were used for analyzing. Results: With a median follow-up of 60.2 months (range, 7.9-91.6 months), 3-year FFS, OS, LRFFS, and DFFS were 76.8%, 85.1%, 88.3%, and 84.1%, respectively. The highest incidence rate of recurrence and metastasis were in the first year after treatment. Multivariate analyses showed that age, total time of radiation therapy (RTT), and total time of therapy (TTT) were independent prognostic factors for FFS and OS. Body mass index (BMI), RTT and TTT were significant variables predicting DFFS. TTT was the only independent prognostic factor for LRFFS. Conclusion: This study indicated that TPF regimen produced encouraging results in Asian patients with locoregionally advanced nasopharyngeal carcinoma. Toxicity was tolerable and reversible. However, overall treatment time is an important factor that we should take into consideration when make plans of induction chemotherapy related treatment.

Genome-Wide Association Study of Susceptibility Loci for Radiation-Induced Brain Injury

BACKGROUND

Radiation-induced brain injury is a nonnegligible issue in the management of cancer patients treated by partial or whole brain irradiation. In particular, temporal lobe injury (TLI), a deleterious late complication in nasopharyngeal carcinoma, greatly affects the long-term life quality of these patients. Although genome-wide association studies (GWASs) have successfully identified single nucleotide polymorphisms (SNPs) associated with radiation toxicity, genetic variants contributing to the radiation-induced brain injury have not yet been assessed.

METHODS

We recruited and performed follow-up for a prospective observational cohort, Genetic Architecture of Radiotherapy Toxicity and Prognosis, using magnetic resonance imaging for TLI diagnosis. We conducted genome-wide association analysis in 1082 patients and validated the top associations in two independent cohorts of 1119 and 741 patients, respectively. All statistical tests were two-sided.

RESULTS

We identified a promoter variant rs17111237 (A > G, minor allele frequency [MAF] = 0.14) in CEP128 associated with TLI risk (hazard ratio = 1.45, 95% confidence interval = 1.26 to 1.66, Pcombined=3.18 × 10-7) which is in moderate linkage disequilibrium (LD) with rs162171 (MAF = 0.18, R2 = 0.69), the top signal in CEP128 (hazard ratio = 1.46, 95% confidence interval = 1.29-1.66, Pcombined= 6.17 × 10-9). Combining the clinical variables with the top SNP, we divided the patients into different subgroups with varying risk with 5-year TLI-free rates ranging from 33.7% to 95.5%. CEP128, a key component of mother centriole, tightly interacts with multiple radiation-resistant genes and plays an important role in maintaining the functional cilia, which otherwise will lead to a malfunction of the neural network. We found that A > G alteration at rs17111237 impaired the promoter activity of CEP128 and knockdown of CEP128 decreased the clonogenic cell survival of U87 cells under radiation. Noteworthy, 12.7% (27/212) of the GWAS-based associated genes (P < .001) were enriched in the neurogenesis pathway.

CONCLUSIONS

This three-stage study is the first GWAS of radiation-induced brain injury that implicates the genetic susceptibility gene CEP128 involved in TLI development and provides the novel insight into the underlying mechanisms of radiation-induced brain injury.

ZWINT is the next potential target for lung cancer therapy

PURPOSE

We aimed to analyze the expression of ZWINT, NUSAP1, DLGAP5, and PRC1 in tumor tissues and adjacent tissues with public data.

METHODS

The expression patterns of four genes were detected in cancer tissues and adjacent tissues by qRT-PCR. The overall survival analysis was used to explore these genes in lung adenocarcinoma and squamous cell carcinoma patients. Knockdown assays were used to select the most suitable gene among these four genes. Cell function assays with the knockdown gene were conducted in A549 and NCL H226 cells. The role of the knockdown gene in lung cancer was dissected in a mice tumor model. Transcriptome sequencing analyses with the knockdown gene were analyzed.

RESULTS

Overexpression of these genes was significantly detected in cancer tissues (P < 0.01). Overall survival revealed that high expression of these genes is closely related with poor prognosis of lung adenocarcinoma patients (P < 0.05). Knockdown of ZWINT reduced proliferation in NCI H226 and A549 cells (P < 0.05). Knockdown also inhibited cell migration, invasion, apoptosis, and colony formation (P < 0.05). ZWINT knockdown reduced tumor volume (P < 0.05). Transcriptome sequencing of ZWINT knockdown-treated A549 and NCI H226 cells indicated that 100 and 426 differentially expressed genes were obtained, respectively. Gene ontology analysis suggested that binding, biological regulation, and multicellular organismal processes were the most enriched. KEGG analysis revealed that TNF, P53, and PI3K signal networks would be the most potential ZWINT-related pathways and were identified by Western blot analysis.

CONCLUSIONS

ZWINT may be a novel target for lung cancer therapy.

Association between genetic variants in the XPG gene and gastric cancer risk in a Southern Chinese population

Xeroderma pigmentosum group G (XPG) recognizes and excises DNA damage on the 3' side during the DNA repair process. Previous studies indicated that XPG gene polymorphisms may associate with gastric cancer susceptibility, but results were inconsistent. We evaluated the association of five potentially functional XPG polymorphisms (rs2094258 C>T, rs751402 C>T, rs2296147 T>C, rs1047768 T>C, and rs873601 G>A) with gastric cancer susceptibility in 1142 gastric cancer cases and 1173 controls. Odds ratios (ORs) and 95% confidence intervals (CIs) were calculated using logistic regression models. Overall, no significant association was detected between any of selected polymorphism and gastric cancer risk. However, we found that individuals carrying 3-4 risk genotypes were at significantly higher risk of gastric cancer than those with 0-2 risk genotypes (OR=1.32, 95% CI=1.04-1.68, P=0.021). The stratification analysis revealed that the cumulative effect of risk genotypes (3-4 vs. 0-2) on gastric cancer were more prominent among subgroups older than 58 years and men. In conclusion, our results indicated that none of the selected XPG polymorphism could significantly alter gastric cancer susceptibility alone. These polymorphisms might collectively confer increased gastric cancer susceptibility. These findings would be strengthened by larger prospective multicenter studies involving different ethnic populations.

Erratum to: Low expression of ULK1 is associated with operable breast cancer progression and is an adverse prognostic marker of survival for patients

Erratum to: Breast Cancer Res Treat (2012),134:549–560,DOI 10.1007/s10549-012-2080-y. In the original publication of the article, Fig. 5c was published incorrectly. The authors apologize for this error and the correct Fig. 5c is given below.

Polymorphisms in the XPC gene and gastric cancer susceptibility in a Southern Chinese population

Previous studies have reported that XPC gene polymorphisms may modify the individual susceptibility to gastric cancer. In this case-control study with a total of 1,142 cases and 1,173 controls, four potentially functional polymorphisms were genotyped in the XPC gene (rs2228001 A>C, rs2228000 C>T, rs2607775 C>G, and rs1870134 G>C) by Taqman assays and their associations were analyzed with the risk of gastric cancer in a Southern Chinese population. No significant association between any of XPC polymorphisms and gastric cancer risk was detected except for a borderline association with the rs2228000 CT/TT genotype (crude odds ratio =0.86, 95% confidence interval =0.73-1.02, P=0.088) when compared to the rs2228000 CC genotype. Further stratified analysis revealed that the protective effect of rs2228000 CT/TT on the risk of gastric cancer was only significant among subjects older than 58 years. In summary, results indicated that genetic variations in XPC gene may play a weak effect on gastric cancer susceptibility in Southern Chinese population, which warrants further confirmation in larger prospective studies with different ethnic populations.

Household inhalants exposure and nasopharyngeal carcinoma risk: a large-scale case-control study in Guangdong, China

BACKGROUND

Epidemiological studies show that cigarette smoking increase the risk of nasopharyngeal carcinoma (NPC), however, whether other common, potentially adverse household inhalants increase NPC risk remains uncertain.

METHODS

We conducted a large case-control study to explore the effects of household inhalants, such as incense, mosquito coil, cooking fumes, and wood combustion, on NPC risk. We recruited 1,845 cases and 2,275 controls from Guangdong province, a high-risk area for NPC in China, to obtain the demographic data and relevant exposure information through face-to-face interviews.

RESULTS

We found that incense burning was associated with NPC risk by comparing frequent incense use with never using incense [OR and 95% confidence interval (CI) = 1.73, (1.43, 2.09)]. Wood fuel use was also associated with NPC risk compared with non-wood fire use [OR and 95% CI = 1.95, (1.65, 2.31)]. More intriguingly, we observed a significant addictive interaction between frequent incense burning and heavy cigarette smoking on NPC risk [synergistic index (SI) = 1.67; 95% CI: 1.01, 2.76]. We also found a significant joint effect between wood fuel use and NPC family history for NPC risk (SI = 1.77; 95% CI: 1.06, 2.96). However, neither mosquito oil nor cooking fumes were associated with NPC risk.

CONCLUSIONS

Our study shows that incense smoke is not only the potential independent risk factor but also co-contributes with cigarette smoking to NPC risk. Moreover, wood combustion is another potential environmental risk factor and exerts a joint effect with NPC family history on NPC.

New surgical staging system for patients with recurrent nasopharyngeal carcinoma based on the AJCC/UICC rTNM classification system

BACKGROUND

Recurrent tumour, node and metastasis (rTNM) stage system does not have an outstanding prognostic value for survival outcome of patients with recurrent nasopharyngeal carcinoma (rNPC) and it cannot aid the clinicians to choose the most suitable treatment for these patients.

METHODS

In total, 894 rNPC patients were consecutively enroled. All recurrent (r) tumour (T) stages (rT) and node (N) stages (rN) were stratified as resectable and unresectable based on the imaging data of the head and neck. These stages were re-subdivided into surgical T stages (sT) and surgical N stages (sN) with similar clinical characteristics and death risks and were re-integrated into a new 'surgical' stage using a Cox proportional hazards model.

RESULTS

The 5-year overall survival (OS) was 72.0%, 55.1%, 21.1% and 10.1% in 'surgical' stages I, II, III and IV, respectively (P<0.001). The 'surgical' stage was a significant independent prognostic factor for OS (hazard ratio [HR] 1.78, P<0.001) and exhibited enhanced prognostic value compared with the rTNM staging system (area under receiver operating characteristics 0.68 versus 0.63, P<0.001). Endoscopic nasopharyngectomy and intensity-modulated radiation therapy were significant independent positive prognostic factors for the OS of patients with primary lesions in 'surgical' stage I/II and 'surgical' stage III, respectively (P<0.05). A combination of aggressive treatments for loco-regional lesions exhibited a beneficial trend for OS of patients with 'surgical' stage IV (P>0.05).

CONCLUSIONS

Compared with the rTNM stage system, the 'surgical' staging system exhibited enhanced prognostic value for rNPC patient survival and could aid clinicians in choosing the most suitable treatment for rNPC patients.

Association of MTHFR C677T and A1298C polymorphisms with non-Hodgkin lymphoma susceptibility: evidence from a meta-analysis

Methylenetetrahydrofolate reductase (MTHFR) is an important enzyme involved in folate metabolism and DNA synthesis. A number of studies have examined the association of MTHFR C677T and A1298C polymorphisms with non-Hodgkin lymphoma (NHL) susceptibility; however, the conclusions were contradictory. We searched available publications assessing the polymorphisms of MTHFR and NHL susceptibility from MEDLINE, EMBASE and CBM. Genotype-based mRNA expression analysis was performed using data from 270 individuals with three different ethnicities. Ultimately, a total of 7448 cases and 11146 controls from 25 studies were included for the C677T polymorphism, 6173 cases and 9725 controls from 19 studies for the A1298C polymorphism. Pooled results indicated that neither C677T nor A1298C polymorphism was associated with NHL susceptibility. However, C677T polymorphism showed a statistically significantly increased risk for Caucasians, but a decreased risk for Asians in the subgroup analysis by ethnicity. The same variants may confer increased susceptibility to develop follicular lymphoma (FL). Moreover, A1298C polymorphism was associated with increased NHL risk for Asians. This meta-analysis indicated that C677T polymorphism was associated with altered NHL susceptibility for Caucasians, Asians and FL. Increased NHL risk was also shown for A1298C among Asians. These findings warrant validation in large and well-designed prospective studies.

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.

Pretreatment lifestyle behaviors as survival predictors for patients with nasopharyngeal carcinoma

BACKGROUND

Lifestyle behaviors have been widely reported to influence the survival of patients with head and neck cancer. However, the relationship between pretreatment lifestyle behaviors and survival among patients with nasopharyngeal carcinoma (NPC) is unclear.

METHODS

A prospective cohort study was designed to determine the relationship between lifestyle behaviors and survival in 1,533 NPC patients recruited from October 2005 to October 2007. Pretreatment lifestyle behaviors (such as body-mass index [BMI], smoking, alcohol, diet) of the patients were investigated. Univariate and multivariate proportional-hazards models were used to assess the impact of lifestyle behaviors on patient survival.

RESULTS

Smoking was a predictor of survival; both current smokers (hazard ratio [HR] = 1.88; 95% CI, 1.33 to 2.65) and heavy smokers (≥ 25 Pack-years; HR = 1.84; 95% CI, 1.30 to 2.60) showed associations with poor survival. Higher BMI was significantly associated with a lower risk of death (P(trend) = 0.002). Compared with under/normal-weight patients (BMI less than 22.99 kg/m(2)), the multivariate HR for survival was 0.66 (95% CI, 0.48 to 0.90) and 0.47 (95% CI, 0.23 to 0.97) for overweight and obese patients, respectively. No alcohol intake and high fruit intake were associated with favorable survival in the univariate analysis but lost significance in the multivariate model.

CONCLUSION

Our findings indicate that pretreatment lifestyle behaviors, especially smoking status and BMI, as easily available data, provide prognostic value for survival in NPC patients.

Pretreatment levels of peripheral neutrophils and lymphocytes as independent prognostic factors in patients with nasopharyngeal carcinoma

BACKGROUND

The purpose of this study was to evaluate the counts and percentages of differential leukocytes as prognostic indicators in patients with nasopharyngeal carcinoma (NPC).

METHODS

This study consisted of 1410 cases identified from an established prospective cohort of 1533 patients with NPC between October 2005 and October 2007 in the Sun Yat-Sen University Cancer Center. Multivariate Cox proportional hazards analyses were applied.

RESULTS

A high percentage of lymphocyte was significantly associated with a favorable prognosis of NPC (highest vs lowest quartile, hazard ratio [HR], 95% confidence interval [CI] for overall and progression-free survival, HR, 0.71; 95% CI, 0.48-1.06; HR, 0.61; 95% CI, 0.43-0.86, respectively), whereas a high neutrophil percentage (HR, 1.62; 95% CI, 1.06-2.46; HR, 1.55; 95% CI, 1.10-2.18, respectively), and a neutrophil/lymphocyte ratio (NLR; HR, 1.57; 95% CI, 1.04-2.39; HR, 1.68; 95% CI, 1.19-2.38, respectively), were significantly related to a poor prognosis of NPC.

CONCLUSION

Pretreatment NLR and percentages of lymphocyte and neutrophil are independent prognostic factors and may serve as clinically convenient and useful biomarkers for survival of patients with NPC.

Use of a posterior pedicle nasal septum and floor mucoperiosteum flap to resurface the nasopharynx after endoscopic nasopharyngectomy for recurrent nasopharyngeal carcinoma

BACKGROUND

Endoscopic nasopharyngectomy is a new salvage treatment for locally recurrent nasopharyngeal carcinoma (NPC). However, how to resurface the nasopharyngeal defects in endoscopic endonasal approaches to avoid persistent postoperative headache, to the best of our knowledge, has not been reported.

METHODS

From September 2009 to August 2010, we used a modified posterior pedicle nasal septum and floor mucoperiosteum flap (nasal septum and floor flap, NSFF) after endoscopic nasopharyngectomy in 12 patients with locally recurrent NPC. Most of the nasal septum and floor mucoperiosteum, except for the posterior pedicle, was harvested to cover the nasopharyngeal defects.

RESULTS

All NSFFs successfully covered the entire nasopharyngeal defects and relined the nasopharynx with good functional recovery. The nasopharyngeal wounds recovered in 28 days (range, 14 to 56 days), and the donor-site wounds recovered in 46.5 days (range, 24-84 days). No reconstruction-related complications or disease recurrences were observed.

CONCLUSION

The NSFF is a safe and promising reconstructive option to resurface the nasopharyngeal defect after endoscopic nasopharyngectomy in patients with locally recurrent NPC.

Human genetic variants of homologous recombination repair genes first found to be associated with Epstein-Barr virus antibody titers in healthy Cantonese

Epstein-Barr virus (EBV) infection is a major risk factor for nasopharyngeal carcinoma (NPC). Despite high prevalence of infection among the general population worldwide, only a small proportion of infected individuals presents with seropositivity for EBV-specific IgA antibodies. This seropositive subgroup of EBV carriers has an elevated cumulative risk for NPC during their lifetime. Previous studies reported that the host homologous recombination repair (HRR) system participates in EBV lytic replication, suggesting a potential mechanism to influence EBV reactivation status and thus seropositivity. To investigate whether genetic variants of HRR genes are associated with the serostatus in a healthy population, we investigated the association between seropositivity for anti-VCA-IgA and 156 tagging SNPs in 35 genes connected with HRR in an observational study among 755 healthy Cantonese speakers in southern China. Six variant alleles of MDC1, RAD54L, TP53BP1, RPA1, LIG3 and RFC1 exhibited associations with seropositivity (p(trend) from 0.0085 to 0.00027). Our study provides evidence that genetic variation within the HRR might affect an individual's propensity for EBV seropositive status of anti-VCA IgA antibody.

A case-control and a family-based association study revealing an association between CYP2E1 polymorphisms and nasopharyngeal carcinoma risk in Cantonese

Nasopharyngeal carcinoma (NPC) is rare in most parts of the world but is more prevalent in Southern China, especially in Guangdong. The cytochrome P450 2E1 (CYP2E1) has been recognized as one of the critically important enzymes involved in oxidizing carcinogens and is probably to be associated with NPC carcinogenesis. To systematically investigate the association between genetic variants in CYP2E1 and NPC risk in Cantonese, two independent studies, a family-based association study and a case-control study, were conducted using the haplotype-tagging single-nucleotide polymorphism approach. A total of 2499 individuals from 546 nuclear families were initially genotyped for the family-based association study. Single-nucleotide polymorphisms (SNPs) rs9418990, rs915908, rs8192780, rs1536826, rs3827688 and one haplotype h2 (CGTGTTAA) were revealed to be significantly associated with the NPC phenotype (P = 0.045-0.003 and P = 0.003, respectively). To follow up the initial study, a case-control study including 755 cases and 755 controls was conducted. Similar results were observed in the case-control study in individuals <46 years of age and had a history of cigarette smoking, with odds ratios (ORs) of specific genotypes ranging from 1.88 to 2.99 corresponding to SNP rs9418990, rs3813865, rs915906, rs2249695, rs8192780, rs1536826, rs3827688 and of haplotypes h2 with OR = 1.65 (P = 0.026), h5 (CCCGTTAA) with OR = 2.58 (P = 0.007). The values of false-positive report probability were <0.015 for six SNPs, suggesting that the reported associations are less probably to be false. This study provides robust evidence for associations between genetic variants of CYP2E1 and NPC risk.

Sequence Variants in Toll-Like Receptor 10 Are Associated with Nasopharyngeal Carcinoma Risk

Nasopharyngeal carcinoma (NPC) is a common malignancy in southern China and Southeast Asia. Genetic susceptibility is a major factor in determining the individual risk of NPC in these areas. To test the association between NPC and variants in Toll-like receptor 10 (TLR10), we conducted a hospital-based case-control study in a Cantonese-speaking population in Guangdong province. Seven single nucleotide polymorphisms in TLR10, selected with a tagging algorithm, were genotyped. When assessing each unique haplotype compared with the most common haplotype, "GAGTGAA," with the expectation-maximization algorithm in Haplo.stats, the risk of developing NPC was significantly elevated among men who carried the haplotype "GCGTGGC" (P = 0.005). After adjusting for age, gender, and VCA-IgA antibody titers, this association was more significant (P = 0.0007). To further assess the overall differences of haplotype frequency profiles between cases and healthy controls, the global score test, considering all haplotypes and adjusting for age, gender, and VCA-IgA antibody titers, gave a haplo score of 27.52 with P = 0.002. The haplotype specific odds ratio was 2.66 (confidence interval, 1.34-3.82) for GCGTGGC. We concluded that in this Cantonese population-based study, haplotype GCGTGGC with frequency of 11.4% in TLR10 was found to be associated with NPC and this association was statistically significant after adjusting for age, gender, and VCA-IgA antibody titers. It is possible that this is not a causal haplotype for NPC; rather, it is in strong linkage disequilibrium with a causal single nucleotide polymorphism in close proximity.

Expression of chemokine receptor CXCR4 in nasopharyngeal carcinoma: pattern of expression and correlation with clinical outcome

Nasopharyngeal carcinoma (NPC) is a tumor derived from epithelial cells and Epstein-Barr virus infection has been reported to be a cause of this disease. Chemokine receptor CXCR4 was found to be involved in HIV infection and was highly expressed in human malignant breast tumors and the ligand for CXCR4, CXCL12 (SDF-1), exhibited high expression in organs in which breast cancer metastases are often found. The metastatic pattern of NPC is quite similar to that of malignant breast tumors. In this study, we investigated the expression of CXCR4 in nasopharyngeal carcinoma (NPC) tissues by immunohistostaining. We found different staining patterns, which included localization in the nucleus, membrane, cytoplasm or a combination of them. The staining intensity was also variable among samples. The metastatic rates in patients with high compared to low or absent expression was 38.6% versus 19.8%, respectively (P = 0.004). High expression of CXCR4 was associated with poor overall survival (OS = 67.05% versus 82.08%, P = 0.0225). These results suggest that CXCR4 may be involved in the progression of NPC and that a high level of CXCR4 expression could be used as a prognostic factor.

Genetic polymorphisms of CYP2A13 and its relationship to nasopharyngeal carcinoma in the Cantonese population

Nasopharyngeal carcinoma (NPC) is characterized by a high prevalence in Southern China, especially among Cantonese individuals of the Guangdong Province. Epidemiological studies have suggested that frequent exposure to high levels of nitrosamine from preserved foods such as salted fish could be a risk factor for NPC. Cytochrome P450 encompasses a family of enzymes that metabolize carcinogens and CYP2A13, a member of this family, is expressed predominantly in the respiratory tract with the highest levels in the nasal mucosa. In an effort to test whether a correlation exists between CYP2A13 genetic polymorphism and the risk of developing NPC, we sequenced all nine exons and the exon-intron junctions of the CYP2A13 gene in 45 NPC patients. We identified a total of 21 single nucleotide polymorphism (SNPs), including 7 novel SNPs. The most frequent functional variant allele was 74A-1757G-3375T-7233G with a haplotype frequency of 7.8% in the 45 NPC cases. In addition, a stop codon mutation was detected in one case. We then selected the 3 most frequent SNPs and one stop codon mutation to expand our study to a case-control analysis within the Cantonese population. A novel haplotype consisting 8 SNPs in introns, and four additional novel SNPs were identified; but no correlation between CYP2A13 genetic polymorphism and individual susceptibility to NPC was observed.

The Aalpha6 locus: its relation to mating-type regulation of sexual development in Schizophyllum commune

We have isolated and examined the Aalpha6 mating-type locus of Schizophyllum commune as a first step toward resolving a functional difference between this locus and the Aalpha loci previously studied. Our analyses show Aalpha6 to be remarkably similar to the Aalpha loci of known structure. The locus is composed of two, divergently transcribed genes similar in size to known Z and Y genes of the Aalpha loci. We have termed the two genes, Z6 and Y6, on the basis of their demonstrated mating activities and encoded protein motifs. The Z6 gene encodes a homeodomain-related sequence, two acidic regions and a predicted coiled-coil motif. The Y6 gene encodes a homeodomain, predicted coiled-coil motif, two regions with homology to the Abeta locus gene V6, a basic region encoding a putative nuclear localization sequence and a serine-rich region. The Z6 and Y6 proteins share these features with the other known Z and Y proteins, respectively. One of the two amino acid sequences with homology to the AbetaV6 protein has not previously been reported.

Schizophyllum commune A alpha mating-type proteins, Y and Z, form complexes in all combinations in vitro

Tha A alpha locus of the basidiomycete fungus, Schizophyllum commune, regulates sexual development via proteins Y and Z. Each A alpha mating type encodes unique Y and Z isoforms. We used two isoforms of Y (Y4 and Y5) and two isoforms of Z (Z4 and Z5) in affinity assays of protein binding. These assays identified two types of protein interactions. Each full-length Y or Z protein binds to itself and other Y or Z proteins regardless of the A alpha mating type from which they are encoded (i.e., mating-type independent binding). A second type of binding, detected with partial-length polypeptides, occurs only between N-terminal regions of Y and Z proteins encoded from different A alpha mating types (e.g., Y4Z5 or Y5Z4); we refer to this binding as mating-type dependent binding. Deletion analysis shows that the Y4 specificity domain (an N-terminal region conferring recognition uniqueness to the Y4 isoform) is essential for mating-type dependent binding. Other regions of Y and Z are involved in mating-type independent binding. These results, obtained in vitro, raise the possibility that either of several protein complexes composed of Y and/or Z proteins may occur in vivo.

Cloning and characterization of a Schizophyllum gene with A beta 6 mating-type activity

The A-pathway of development in the basidiomycete fungus Schizophyllum commune may be activated by either of two mating-type loci, A alpha and A beta. A alpha consists of two multiallelic genes, Y and Z. Y contains a putative homeodomain; Z contains a homeodomain-related region. Non-self combinations of Y and Z form heteromultimers which are thought to be transcription factors of developmental genes. To more completely understand A-regulated development it is necessary to address the issue of functional redundancy, i.e., how do two different mating loci, A alpha and A beta, both manage to regulate the same pathway. Here we report the structure of a gene with A beta 6 activity. This gene, denoted A beta V6, encodes a deduced polypeptide of 640 amino-acids with a homeodomain motif. V6 also contains a 20-amino acid sequence that is conserved in A alpha Y1, Y3 and Y4. Except for the homeodomain and the conserved sequence, the deduced V6 polypeptide shows no significant identity to A alpha Y, A alpha Z, or other known proteins. The presence of a homeodomain suggests that V, like Y and Z, may be a regulatory protein for genes in the A-pathway. Thus while A alpha and A beta encode different proteins, the general mechanism by which A alpha and A beta components signal A-regulated development may be similar.

Mammalian mitochondrial intermediate peptidase: structure/function analysis of a new homologue from Schizophyllum commune and relationship to thimet oligopeptidases

Mitochondrial intermediate peptidase (MIP) is a component of the mitochondrial protein import machinery required for maturation of nuclear-encoded precursor proteins targeted to the mitochondrial matrix or inner membrane. We previously characterized this enzyme in rat (RMIP) and Saccharomyces cerevisiae (YMIP) and showed that MIP activity is essential for mitochondrial function in yeast. We have now defined the structure of a new MIP homologue (SMIP) from the basidiomycete fungus Schizophyllum commune. SMIP includes 4 exons of 523, 486, 660, and 629 bp separated by 3 short introns. The predicted SMIP, YMIP, and RMIP sequences share 31-37% identity and 54-57% similarity over 700 amino acids. When SMIP and RMIP were expressed in a yeast mip1 delta mutant, they were both able to rescue the respiratory-deficient phenotype caused by genetic inactivation of YMIP, indicating that the function of this enzyme is conserved in eukaryotes. Moreover, the MIP sequences show 20-24% identity and 40-47% similarity to a family of oligopeptidases from bacteria, yeast, and mammals. MIP and these proteins are characterized by a highly conserved motif, F-H-E-X-G-H-(X)2-H-(X)12-G-(X)5-D-(X)2-E-X-P-S-(X)3-E-X, centered around a zinc-binding site and appear to represent a new family of genes associated with proteolytic processing in the mitochondrial and cytosolic compartments.

The A alpha mating-type transcripts of Schizophyllum commune

A alpha 1, A alpha 3, and A alpha 4 ds- and ss-DNA probes from the polymorphic A alpha mating-type locus of Schizophyllum commune were used to probe Northern blots of poly(A+) RNA extracted from strains of various A alpha mating types. The purpose of these experiments was to identify, map, and characterize the transcripts produced from the regions of the A alpha locus. The transcripts unique to A alpha mating type map colinear with the open reading frames identified from DNA sequence and are encoded within the fragments which activate the A developmental pathway in transformation. These data confirm the existence and structure of the previously hypothesized Y and Z A alpha mating-type genes. Transcripts from the Y and Z genes are present in vegetative cells of homokaryons and dikaryons and in cells of the fruiting bodies. The presence of the transcripts throughout the life cycle is consistent with the model of Y and Z proteins as "master switches" of A-regulated development.