Dietary risk factors for nasopharyngeal carcinoma in Maghrebian countries

Traditional Cantonese diet and nasopharyngeal carcinoma risk: a large-scale case-control study in Guangdong, China

BACKGROUND

Nasopharyngeal carcinoma (NPC) is rare in most parts of the world but is a common malignancy in southern China, especially in Guangdong. Dietary habit is regarded as an important modifier of NPC risk in several endemic areas and may partially explain the geographic distribution of NPC incidence. In China, rapid economic development during the past few decades has changed the predominant lifestyle and dietary habits of the Chinese considerably, requiring a reassessment of diet and its potential influence on NPC risk in this NPC-endemic area.

METHODS

To evaluate the association between dietary factors and NPC risk in Guangdong, China, a large-scale, hospital-based case-control study was conducted. 1387 eligible cases and 1459 frequency matched controls were recruited. Odds ratios (ORs) and the corresponding 95% confidence intervals (CIs) were estimated using a logistic regression model, adjusting for age, sex, education, dialect, and habitation household type.

RESULTS

Observations made include the following: 1) consumption of canton-style salted fish, preserved vegetables and preserved/cured meat were significantly associated with increased risk of NPC, with enhanced odds ratios (OR) of 2.45 (95% CI: 2.03-2.94), 3.17(95% CI: 2.68-3.77) and 2.09 (95% CI: 1.22-3.60) respectively in the highest intake frequency stratum during childhood; 2) consumption of fresh fruit was associated with reduced risk with a dose-dependent relationship (p = 0.001); and 3) consumption of Canton-style herbal tea and herbal slow-cooked soup was associated with decreased risk, with ORs of 0.84 (95% CI: 0.68-1.03) and 0.58 (95% CI: 0.47-0.72) respectively in the highest intake frequency stratum. In multivariate analyses, these associations remained significant.

CONCLUSIONS

It can be inferred that previously established dietary risk factors in the Cantonese population are still stable and have contributed to the incidence of NPC.

Indole-3-carbinol inhibits nasopharyngeal carcinoma

This study explored the effects of indole-3-carbinol on the proliferation of human nasopharyngeal carcinoma, both in vitro and in vivo, and the underlying mechanisms in inducing apoptosis of CNE1 cells. Proliferation, apoptosis, malondialdehyde, superoxide dismutase, glutathione peroxidase, expressions of caspase-9, and caspase-3 in human nasopharyngeal carcinoma cells CNE1 were examined. Indole-3-carbinol suppressed proliferation, induced apoptosis, decreased malondialdehyde level, increased the activity of superoxide dismutase and glutathione peroxidase, and up-regulated the expression of active fragments of caspase-9 and caspase-3 both in vitro and in vivo. It was concluded that indole-3-carbinol could inhibit proliferation and induce apoptosis of CNE1 cells and inhibit tumor growth in mice. Increased activity of superoxide dismutase and glutathione peroxidase and activated expression of caspase-9 and caspase-3 were also observed in indole-3-carbinol-treated tumors or tumor cells, suggesting that stress- and apoptosis-related molecules are involved in the indole-3-carbinol-induced apoptosis and inhibition of tumor growth.

Head and neck cancer in a developing country: a population-based perspective across 8 years

Head and neck cancer (HNC) has been studied in different regions of the world but little is known about its incidence patterns in the Middle East and Egypt. In this study from Egypt's only population-based registry, we analyzed data from 1999 to 2006, to estimate incidence, incidence rate ratios (IRRs) and 95% confidence intervals (CIs) categorized by age, district and subsites. Overall urban incidence of HNC was twice or more that of rural incidence for both males (IRR=2.59; 95% CI=2.26, 2.97) and females (IRR=2.00; 95% CI=1.64, 2.43). Highest urban-rural difference for males was seen in 40-49years (IRR=2.79; 95% CI=1.92, 4.05) and for females in 30-39years (IRR=2.94; 95% CI=1.60, 5.40). Among subsites, highest incidence among males was for larynx (1.53/10(5)) and among females for gum and mouth (0.48/10(5)). Maximum urban-rural difference in males was for paranasal sinus (IRR=4.66; 95% CI=1.88, 11.54) and in females for lip (IRR=8.91; 95% CI=1.89, 41.98). The study underscores the patterns of HNC incidence in Egypt while indicating the need for future analytical studies investigating specific risk factors of HNC in this population.

Quantitative analysis of BCL2 mRNA expression in nasopharyngeal carcinoma: an unfavorable and independent prognostic factor

Programmed cell death plays a vital role in a wide variety of physiological processes. Defects in apoptotic cell death contribute to neoplastic diseases by preventing or delaying normal cell death. BCL2 (Bcl-2) is an anti-apoptotic gene with marked up-regulation in various malignancies, such as breast cancer, in which expression of the BCL2 protein has been proposed as a prognostic tumor biomarker. The purpose of the current study was to investigate mRNA expression of the BCL2 gene in nasopharyngeal carcinoma (NPC) biopsies and assess its prognostic value. For this purpose, total RNA was isolated from 89 malignant and hyperplastic nasopharyngeal biopsies from Tunisian patients. After testing the quality of the extracted RNA, cDNA was prepared by reverse transcription. A highly sensitive real-time PCR methodology for BCL2 mRNA quantification was developed using SYBR® Green chemistry. GAPDH served as an endogenous control gene. Relative quantification analysis was performed using the comparative C (T) (2(-∆∆CT)) method. High BCL2 mRNA levels were detected in advanced-stage nasopharyngeal tumors (p = 0.030). Furthermore, BCL2 mRNA expression was strongly associated with lymph node involvement (p = 0.009) and presence of distal metastases (p = 0.013). Survival analysis demonstrated that patients with BCL2-positive nasopharyngeal tumors have significantly shorter disease-free and overall survival (p = 0.011 and p = 0.028, respectively). The major contribution of the current study is the quantification and evaluation, for the first time, of the prognostic significance of the BCL2 mRNA expression in nasopharyngeal carcinoma (NPC) patients. Our results suggest that mRNA expression levels of BCL2 may represent a novel unfavorable and independent tumor biomarker for nasopharyngeal carcinoma.

[Juvenile nasopharyngeal carcinoma: anatomoclinic, biologic, therapeutic and evolutive aspects]

Nasopharyngeal carcinoma (NPC) represents one of the most frequent epithelial tumours of the child in intermediate risk regions. In the Maghreb, it represents the first cancer of teenagers of 15-20 years old. The Epstein Barr virus (EBV) is the most important etiologic factor. Its role in the pathogeneses of NPC has been confirmed by several studies. Young NPCs are characterized by a low rate of EBV antibodies and a high level of LMP1 cell expression than in adult's NPC. The undifferentiated carcinoma nasopharyngeal type (UCNT) represents the most frequent histological type. Immunohistochemical analyses of North Africa early onset NPC is characterized by a weak expression of bcl-2 and p53 and a strong expression of LMP1 and c-kit what makes them different from the adult's NPC. Clinically, cervical node involvement is constantly present. Juvenile NPC is characterized by a very important locoregional extension as well as a high rate of distant metastases. More than 15% of patients had metastases at diagnosis. Radiotherapy is still the standard therapy of NPC. Only some retrospectives studies have been published to determine the benefit, the type and the timing of the chemotherapy in the treatment of juvenile NPC. Metastatic relapses constitute the main cause of death at these young patients. An improvement of the prognosis can be waited with concomitant chemotherapy and intensity modulated radiotherapy. However, randomized multi institutional studies are necessary to standardize the treatment of the NPC in childhood.

Epstein-barr virus infection and multiple sclerosis: a review

Epstein-Barr virus (EBV) infection results in a life-long persistence of the virus in the host's B-lymphocytes and has been associated with numerous cancers including Burkitt's lymphoma, Hodgkin lymphoma, and nasopharyngeal carcinoma. There is considerable evidence that EBV infection is a strong risk factor for the development of multiple sclerosis. Early age at primary EBV infection is typically asymptomatic, but primary infection during adolescence or adulthood often manifests as infectious mononucleosis, which has been associated with a two- to threefold increased risk of MS. Most importantly, MS risk is extremely low in individuals who are EBV negative, but it increases several folds following EBV infection. Additional evidence supporting a role for EBV in MS pathogenesis includes the observations of elevated antibodies to EBV antigens (especially EBV nuclear antigen-1) prior to the onset of MS, and an increased risk of MS among EBV-positive children. The biological mechanism by which EBV may cause MS is not known, but several possibilities are discussed.

Risk factors for the occurrence of undifferentiated carcinoma of nasopharyngeal type: A case-control study

Introduction. The incidence rate of nasopharyngeal carcinoma in Serbia is less than one per 100,000 citizens, which classifies it as a region with low incidence for this disease. Objective. The aim of this study was to test some hypotheses of the risk factors for undifferentiated carcinoma of nasopharyngeal type (UCNT) in the low incidence population. Methods. A case-control study was used for the research. The study included 45 cases with histopathological diagnosis of UCNT and 90 controls. Cases and the controls were individually matched by sex, age (?3 years), and place of residence (city-village). Data were gathered about sociodemographic characteristics, occupational exposure to harmful agents, habits, diet, personal history, and family history. In the analysis of the data, conditional univariate and multivariate logistic regression analyses were applied. Results. According to the results of multivariate logistic regression analysis UCNT was significantly positively associated with 'passive smoking' of tobacco in the family during childhood, frequent consumption of industrially manufactured food additives for enhancing flavour and frequent consumption of white bread. UCNT was significantly negatively associated with frequent consumption of margarine, olive oil and cornbread. Conclusion. In our low incidence population, an independent risk factor for the occurrence of UCNT was 'passive smoking' of tobacco in the family during childhood, use of industrially manufactured food with additives for enhancing flavour and consumption of white bread. Multicentric study enrolling a greater number of cases would be desirable.

Methylation associated inactivation of RASSF1A and its synergistic effect with activated K-Ras in nasopharyngeal carcinoma

Background

Epigenetic silencing of tumor suppressor genes associated with promoter methylation is considered to be a hallmark of oncogenesis. RASSF1A is a candidate tumor suppressor gene which was found to be inactivated in many human cancers. Although we have had a prelimilary cognition about the function of RASSF1A, the exact mechanisms about how RASSF1A functions in human cancers were largely unknown. Moreover, the effect of mutated K-Ras gene on the function of RASSF1A is lacking. The aim of this study was to investigate the expression profile and methylation status of RASSF1A gene, and to explore its concrete mechanisms as a tumor suppressor gene in Nasopharyngeal Carcinoma.

Methods

We examined the expression profile and methylation status of RASSF1A in two NPC cell lines, 38 primary nasopharyngeal carcinoma and 14 normal nasopharyngeal epithelia using RT-PCR and methylated specific PCR(MSP) respectively. 5-aza-dC was then added to confirm the correlation between hypermethylation status and inactivation of RASSF1A. The NPC cell line CNE-2 was transfected with exogenous pcDNA3.1(+)/RASSF1A plasmid in the presence or absence of mutated K-Ras by liposome-mediated gene transfer method. Flow cytometry was used to examine the effect of RASSF1A on cell cycle modulation and apoptosis. Meanwhile, trypan blue dye exclusion assays was used to detect the effect of RASSF1A transfection alone and the co-transfection of RASSF1A and K-Ras on cell proliferation.

Results

Promoter methylation of RASSF1A could be detected in 71.05% (27/38) of NPC samples, but not in normal nasopharyngeal epithelia. RASSF1A expression in NPC primary tumors was lower than that in normal nasopharyngeal epithelial (p < 0.01). Expression of RASSF1A was down-regulated in two NPC cell lines. Loss of RASSF1A expression was greatly restored by the methyltransferase inhibitor 5-aza-dC in CNE-2. Ectopic expression of RASSF1A in CNE-2 could increase the percentage of G0/G1 phase cells (p < 0.01), inhibit cell proliferation and induce apoptosis (p < 0.001). Moreover, activated K-Ras could enhance the growth inhibition effect induced by RASSF1A in CNE-2 cells (p < 0.01).

Conclusion

Expression of RASSF1A is down-regulated in NPC due to the hypermethylation of promoter. Exogenous expression of RASSF1A is able to induce growth inhibition effect and apoptosis in tumor cell lines, and this effect could be enhanced by activated K-Ras.

Cannabis, tobacco and domestic fumes intake are associated with nasopharyngeal carcinoma in North Africa

Background:

The lifestyle risk factors for nasopharyngeal carcinoma (NPC) in North Africa are not known.

Methods:

From 2002 to 2005, we interviewed 636 patients and 615 controls from Algeria, Morocco and Tunisia, frequency-matched by centre, age, sex, and childhood household type (urban/rural). Conditional logistic regression was used to evaluate the association of lifestyles with NPC risk, controlling for socioeconomic status and dietary risk factors.

Results:

Cigarette smoking and snuff (tobacco powder with additives) intake were significantly associated with differentiated NPC but not with undifferentiated carcinoma (UCNT), which is the major histological type of NPC in these populations. As demonstrated by a stratified permutation test and by conditional logistic regression, marijuana smoking significantly elevated NPC risk independently of cigarette smoking, suggesting dissimilar carcinogenic mechanisms between cannabis and tobacco. Domestic cooking fumes intake by using kanoun (compact charcoal oven) during childhood increased NPC risk, whereas exposure during adulthood had less effect. Neither alcohol nor shisha (water pipe) was associated with risk.

Conclusion:

Tobacco, cannabis and domestic cooking fumes intake are risk factors for NPC in western North Africa.

Comparison of treatment results between adult and juvenile nasopharyngeal carcinoma

PURPOSE

Nasopharyngeal carcinoma (NPC) has a bimodal age distribution. In contrast to the adult variant, little is known about the juvenile form. This study examined the treatment results between adult (aNPC) and juvenile NPC (jNPC) patients for future treatment considerations in jNPC.

METHODS AND MATERIALS

The jNPC population included 53 patients treated at two institutions between 1972 and 2004. The aNPC population included 84 patients treated at one institution. The patients had received a median dose of 66 Gy of external beam radiotherapy and 72% underwent chemotherapy. The mean follow-up for surviving patients was 12.6 years for jNPC and 6.6 years for aNPC.

RESULTS

The jNPC patients presented with more advance stages than did the aNPC patients (92% vs. 67% Stage III-IV, p = .006). However, jNPC patients had significantly better overall survival (OS) than did aNPC patients. The 5-year OS rate was 71% for jNPC and 58% for aNPC (p = .03). The jNPC group also demonstrated a trend for greater relapse-free survival than the aNPC group (5-year relapse-free survival rate, 69% vs. 49%; p = .056). The pattern of failure analysis revealed that the jNPC patients had greater locoregional control and freedom from metastasis but the differences were not statistically significant. Univariate analysis for OS revealed that age group, nodal classification, and chemotherapy use were significant prognostic factors. Age group remained significant for OS on multivariate analysis, after adjusting for N classification and treatment.

CONCLUSION

Despite more advance stage at presentation, jNPC patients had better survival than did aNPC patients. Future treatment strategies should take into consideration the long-term complications in these young patients.

Association of MICA-129 polymorphism with nasopharyngeal cancer risk in a Tunisian population

Major histocompatibility complex (MHC) class I chain-related A (MICA) molecules mediate natural killer (NK) cell activation and T lymphocyte co-stimulation. A polymorphic methionine (met) to valine (val) variation at amino acid position 129 of the alpha2 heavy chain domain is in linkage disequilibrium with other allelic changes and seems to categorize MICA alleles into strong and weak binder of NKG2D receptor and thereby to influence effector cell function. We investigated here whether MICA-129 dimorphism is associated with susceptibility to/or resistance against developing nasopharyngeal cancer (NPC). DNA from 130 NPC patients and 180 healthy individuals from Tunisia were genotyped for MICA-129 variation. We found a higher frequency of MICA-129 val/val genotype in patients than in controls (corrected p value = 0.02) that could suggest a tumor escape mechanism because of failure to activate NK cells by MICA-129 val allele or absence of NK cell activation because of absence of MICA-129 met allele in individuals otherwise predisposed to viral/environmental factors.

Recurrent overexpression of c-IAP2 in EBV-associated nasopharyngeal carcinomas: critical role in resistance to Toll-like receptor 3-mediated apoptosis

The oncogenic process leading to nasopharyngeal carcinoma (NPC) requires the combination of genetic and epigenetic alterations, latent infection by the Epstein-Barr virus and local inflammation. A transcriptome analysis of NPC xenografts identified the gene encoding the cellular inhibitor of apoptosis protein 2 (c-IAP2) among the top five most intensely expressed. Consistently, the very high levels of the c-IAP2 protein were detected in 11 of 13 NPC biopsies. RMT 5265, a structural analog of second mitochondria-derived activator of caspase (SMAC), induced the rapid degradation of c-IAP2 in nasopharyngeal epithelial cells, whether malignant or not, but blocked clonal cell growth in NPC cells only. In short-term experiments, RMT 5265 induced apoptosis in a fraction of NPC cells, and this apoptosis was dramatically enhanced when RMT 5265 was combined with Toll-like receptor 3 (TLR3) stimulation. By contrast, the cooperative effect with tumor necrosis factor alpha was only marginal. The apoptosis induced by the combination of RMT 5265 and TLR3 stimulation was mediated by caspase-8 and associated with a decrease in the cellular content of the long isoform of FLICE-like inhibitory protein. Similar caspase-8 activation was obtained when siRNA knockdown of c-IAP2 was combined with TLR3 stimulation. In conclusion, c-IAP2 has a specific protective function in NPC cells challenged by TLR3 agonists. This protective function is probably important to make NPC cells tolerant to their own production of small viral RNAs, which are potential agonists of TLR3. Our data will help to design a rational use of IAP inhibitors in NPC patients.