Nasopharyngeal carcinoma in situ

Functional polymorphism in the 5'-UTR of CR2 is associated with susceptibility to nasopharyngeal carcinoma

Epstein-Barr virus (EBV)-associated nasopharyngeal carcinoma (NPC) is a squamous cell cancer endemic in Southern China and Southeast Asia. It has been shown that inflammatory and immune responses during EBV infection contribute to the development of NPC. The complement receptor 2 (CR2) gene plays central roles during inflammatory and immune responses and, therefore, is a good candidate susceptibility gene for NPC. We performed PCR-based sequencing to identify multiple single-nucleotide polymorphisms (SNPs) within the exon regions of the CR2 gene in a Cantonese population. Two SNPs were screened in 528 NPC patients and 408 normal individuals to perform a case-control study matched according to age, gender and residence. Furthermore, we cloned the entire 5′-UTR and entire CR2 promoter into a luciferase report system and compared the luciferase activities between the different allelic constructs. A SNP in the 5′-UTR of CR2 (24 T/C, rs3813946) showed a significant association (P<0.01) with NPC in the Cantonese population studied. The subjects were categorized into 2 age groups: group 1, age ≤45 years and group 2, age >45 years. In group 1, the allelic frequencies of 24 T/C in the patients were significantly different from those of the controls (P=0.0034). The odds ratio (OR=1.81) also indicated a higher risk of NPC in individuals who carried the minor allele C. All constructs exerted allelic differences on luciferase activities, but only the susceptible allele +24C construct showed increased activity. Our findings implicate CR2 as a susceptibility gene for NPC and suggest that enhanced CR2 expression may be involved in the oncogenesis and development of NPC.

Genetic polymorphisms of TLR3 are associated with Nasopharyngeal carcinoma risk in Cantonese population

Background

Nasopharyngeal carcinoma is endemic in Southern China, displays a strong relationship with genetic susceptibility and associates with Epstein-Barr virus infection. Toll-like receptor 3 (TLR3) plays an important role in the antivirus response. Therefore, we examined the association between TLR3 gene polymorphisms and NPC susceptibility.

Methods

We performed a case-control study of 434 NPC cases and 512 healthy controls matched on age, sex and residence. Both cases and controls are of Cantonese origin from Southern China. Genetic variants in TLR3 were determined by polymerase chain reaction (PCR)-based DNA direct sequencing and four SNPs were genotyped in all samples.

Results

Our results showed that allele C for SNP 829A/C increased NPC risk significantly ((p = 0.0068, OR = 1.49, 95%CI:1.10–2.00). When adjusted for age, gender and VCA-IgA antibody titers, the NPC risk was reduced significantly among individuals who carried the haplotype "ATCT" compared to those who carried the most common haplotype "ACCT" (p = 0.0054, OR = 0.028; 95% CI (0.002–0.341).

Conclusion

The TLR3 polymorphisms may be relevant to NPC susceptibility in the Cantonese population, although the reduction in NPC risk is modest and the biological mechanism of the observed association merits further investigation.

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.

In vivo real-time diagnosis of nasopharyngeal carcinoma in situ by contact rhinoscopy

BACKGROUND

Nasopharyngeal dysplasia or nasopharyngeal carcinoma in situ (NPCIS) lesions have rarely been reported. Timely diagnosis of the preinvasive lesion may improve prognosis. Contact endoscopy has been documented to accurately differentiate normal cells of the nasopharynx from malignant cells and allows a real-time diagnosis of primary and recurrent nasopharyngeal carcinoma (NPC) in a clinical setting. However, the role of contact endoscopy in the diagnosis of NPCIS is unknown.

METHODS

The superficial cells of the nasopharynx in a patient with NPCIS were examined in vivo under local anaesthesia by use of a contact rhinoscope. The contact endoscopic findings were correlated with the histologic findings of the biopsy.

RESULTS

The atypical cells of the lesion were magnified and visualized under contact endoscopy. Histopathologic analysis of the biopsied tissue confirmed the presence of NPCIS staining positively for Epstein-Barr virus (EBV)-encoded RNA (EBER). No cell-free EBV DNA was detected in the sera of the patient.

CONCLUSIONS

Contact endoscopy can accurately identify the atypical cells of a tiny preinvasive lesion in the nasopharynx in a clinical setting, which may not be evident in routine imaging examination.

Classification of in vivo autofluorescence spectra using support vector machines

An algorithm based on support vector machines (SVM), the most recent advance in pattern recognition, is presented for use in classifying light-induced autofluorescence collected from cancerous and normal tissues. The in vivo autofluorescence spectra used for development and evaluation of SVM diagnostic algorithms were measured from 85 nasopharyngeal carcinoma (NPC) lesions and 131 normal tissue sites from 59 subjects during routine nasal endoscopy. Leave-one-out cross-validation was used to evaluate the performance of the algorithms. An overall diagnostic accuracy of 96%, a sensitivity of 94%, and a specificity of 97% for discriminating nasopharyngeal carcinomas from normal tissues were achieved using a linear SVM algorithm. A diagnostic accuracy of 98%, a sensitivity of 95%, and a specificity of 99% for detecting NPC were achieved with a nonlinear SVM algorithm. In a comparison with previously developed algorithms using the same dataset and the principal component analysis (PCA) technique, the SVM algorithms produced better diagnostic accuracy in all instances. In addition, we investigated a method combining PCA and SVM techniques for reducing the complexity of the SVM algorithms.

Epstein-Barr virus: induction and control of cell transformation

Epstein-Barr virus (EBV), a ubiquitous human herpes virus, is associated with an increasing number of lymphoid and epithelial malignancies. The ability of the virus to establish life-long persistent infections and induce growth transformation is related to the function of a set of viral proteins that are variously expressed in both normal and malignant cells. Recent evidence indicates that these viral proteins are able to usurp cellular pathways that promote the cell growth and survival, while impairing anti-viral immune responses. Elucidation of the mechanisms by which EBV induces cell transformation and escapes host immune control provides the rational background for the design of new strategies of intervention for EBV-related malignancies.

Nasopharyngeal carcinoma in situ (NPCIS)--pathologic and clinical perspectives

BACKGROUND

Dysplasia or carcinoma in situ lesions (NPCIS) of the nasopharynx have rarely been reported. The prevalence, biologic behavior, and the transformation period of the pure preinvasive lesions have not been fully explained.

METHODS

All cases of NPCIS were retrospectively reviewed during the period between 1990 and 2000. The clinical features of all cases were studied. The biopsy samples were examined using light microscopy and in situ hybridization (ISH) for EBV-encoded RNA (EBER). The sera taken before and after the transformation were analyzed for anti-viral capsid antigen (VCA) EBV titers and circulating cell-free EBV DNA concentration.

RESULTS

Three cases of NPCIS were identified. Two of the three cases subsequently developed into invasive NPC after initial presentation. The interval of transformation varied from 40 to 48 months. In all three cases, the specimens showed abnormal findings on light microscopy and positive staining for EBER. Elevated anti-VCA titers were present in two of the preinvasive lesions. No cell-free EBV DNA was detected in the sera of these patients during the preinvasive phase of the disease.

CONCLUSIONS

Preinvasive NPC is a rare but distinct entity. Its transformation period can be as long as 4 to 5 years. Elevated anti-VCA titers, in the presence of abnormal cells on light microscopy, should alert the pathologist to perform ISH EBER studies to diagnose this rare condition.