Noureddine Bouaouina

Leptin and leptin receptor polymorphisms are associated with increased risk and poor prognosis of breast carcinoma

BackgroundLeptin (LEP) has been consistently associated with angiogenesis and tumor growth. Leptin exerts its physiological action through its specific receptor (LEPR). We have investigated whether genetic variations in LEPand LEPRhave implications for susceptibility to and prognosis in breast carcinoma.MethodsWe used the polymerase chain reaction and restriction enzyme digestion to characterize the variation of the LEPand LEPRgenes in 308 unrelated Tunisian patients with breast carcinoma and 222 healthy control subjects. Associations of the clinicopathologic parameters and these genetic markers with the rates of the breast carcinoma-specific overall survival (OVS) and the disease free survival (DFS) were assessed using univariate and multivariate analyses.ResultsA significantly increased risk of breast carcinoma was associated with heterozygous LEP (-2548) GA(OR = 1.45; P = 0.04) and homozygous LEP (-2548) AA(OR = 3.17; P = 0.001) variants. A highly significant association was found between the heterozygous LEPR 223QRgenotype (OR = 1.68; P = 0.007) or homozygous LEPR 223RRgenotype (OR = 2.26; P = 0.001) and breast carcinoma.Moreover, the presence of the LEP (-2548) Aallele showed a significant association with decreased disease-free survival in breast carcinoma patients, and the presence of the LEPR 223Rallele showed a significant association with decreased overall survival.ConclusionOur results indicated that the polymorphisms in LEPand LEPRgenes are associated with increased breast cancer risk as well as disease progress, supporting our hypothesis for leptin involvement in cancer pathogenesis.

Genetic variation in the tumor necrosis factor-? promoter region and in the stress protein hsp70-2: Susceptibility and prognostic implications in breast carcinoma

BACKGROUND Tumor necrosis factor-alpha (TNF-alpha) and stress proteins (heat shock proteins) are determining factors in the immune response to tumor cells. The authors designated a large study to investigate the susceptibility and prognostic implications of the genetic variation in TNF-alpha and hsp70-2 in breast carcinoma. METHODS The authors used the polymerase chain reaction and restriction enzyme digestion to characterize the variation of the TNF-alpha promoter region and that of the hsp70-2 gene in 243 unrelated Tunisian patients with breast carcinoma and 174 healthy control subjects. Associations of the clinicopathologic parameters and the genetic markers with the rates of the breast carcinoma specific overall survival and the disease free survival (DFS) were assessed using univariate and multivariate analyses. RESULTS A highly significant association was found between TNF2 homozygous genotype and breast carcinoma (relative risk [RR], 4.44; P = 0.006). A high relative risk of breast carcinoma was found to be associated with one hsp70-2 homozygous genotype (P2/P2; RR, 7.12; P = 0.0001). The TNF2 homozygous genotype showed a significant association with reduced DFS and/or overall survival by univariate test. Conversely, P2-hsp70-2 homozygous genotype associated with increased overall survival but not with DFS. Multivariate analysis retained significance for TNF2 homozygous genotype as an independent prognostic indicator for both DFS (RR, 2.75; P = 0.01) and overall survival (RR, 4.08; P = 0.01). CONCLUSIONS Genetic variation in TNF-alpha and hsp70-2 may represent not only markers for the increased risk of breast carcinoma but also may predict the clinical outcome.

Combined effects of IL-8 and CXCR2 gene polymorphisms on breast cancer susceptibility and aggressiveness

BackgroundInterleukin-8 (IL-8/CXCL-8) is a prototype of the ELR+CXC chemokines that play an important role in the promotion and progression of many human cancers including breast cancer. We have recently showed the implication of polymorphism (-251) T/A of IL-8 gene in the susceptibility and prognosis of breast carcinoma. IL-8 acts through its CXCR1 and CXCR2 receptors. CXCR2, expressed on the endothelial cells, is the receptor involved in mediating the angiogenic effects of ELR+CXC chemokines and in particular IL-8.In the current study, we investigated the susceptibility and prognostic implications of the genetic variation in CXCR2 in breast carcinoma. We also confirmed the implication of IL-8 (-251) T/A polymorphism in a larger cohort. Finally, we combined the IL-8 and CXCR2 variant alleles and analyzed their effects in breast cancer risk and prognosis.MethodsWe used the allele-specific polymerase chain reaction to characterize the variation of IL-8 and CXCR2 for 409 unrelated Tunisian patients with breast carcinoma and 301 healthy control subjects. To estimate the relative risks, Odds ratios and 95% confidence intervals were calculated using unconditional logistic regression after adjusting for the known risk factors for breast cancer. Associations of the genetic marker with the rates of breast carcinoma-specific overall survival and disease-free survival were assessed using univariate and multivariate analyses.ResultsA highly significant association was found between the homozygous CXCR2 (+ 1208) TT genotype (adjusted OR = 2.89; P = 0.008) and breast carcinoma. A significantly increased risk of breast carcinoma was associated with IL-8 (-251) A allele (adjusted OR = 1.86; P = 0.001). The presence of two higher risk genotypes (the TA and TT in IL-8, and the TT in CXCR2) significantly increased the risk of developing breast carcinoma (adjusted OR = 4.15; P = 0.0004).The CXCR2 (+ 1208) T allele manifested a significant association with an aggressive phenotype of breast carcinoma as defined by a large tumor size, a high histological grade, and auxiliarys lymph node metastasis. A significant association between the IL-8 (-251) A allele and the aggressive form of breast carcinoma was also found.Moreover, the presence of the IL-8 (-251) A and/or the CXCR2 (+ 1208) T allele showed a significant association with a decreased overall survival and disease-free survival in breast carcinoma patients.ConclusionOur results indicated that the polymorphisms in IL-8 and CXCR2 genes are associated with increased breast cancer risk, as well as disease progress, supporting our hypothesis for IL-8 and ELR+CXC chemokine receptor (CXCR2) involvement in breast cancer pathogenesis.

Dietary risk factors for nasopharyngeal carcinoma in Maghrebian countries

North Africa is one of the major Nasopharyngeal Carcinoma (NPC) endemic regions. Specific food items unique to this area were implicated to be associated with NPC risk, but results were inconsistent. Here we have performed a large‐scale case‐control study in the Maghrebian population from Tunisia, Algeria and Morocco. From 2002 to 2005, interviews were conducted on 636 cases and 615 controls. Controls were hospitalized individuals from 15 non‐cancer hospital departments, or friends and family members of non‐NPC cancer subjects, matched by center, childhood household type (rural or urban), age and sex. Conditional logistic regression is used to evaluate the risk of factors. In results, consumption of rancid butter, rancid sheep fat and preserved meat not spicy (mainly quaddid) were associated with significantly increased risk of NPC, while consumption of cooked vegetables and industrial preserved fish was associated with reduced risk. Other foods such as fresh citrus fruits and spicy preserved meat (mainly osban) in childhood, industrial made olive condiments in adulthood, were marginally associated. In multivariate analyses, only rancid butter, rancid sheep fat and cooked vegetables were significantly associated with NPC. In regard to possible causative substances, our results implicate the involvement of butyric acid, a potential Epstein‐Barr virus (EBV) activator.

Polymorphism of the stress protein HSP70-2 gene is associated with the susceptibility to the nasopharyngeal carcinoma

Several studies have shown statistical evidence of association between nasopharyngeal carcinoma (NPC) and specific human leukocyte antigen (HLA) alleles and highlighted the presence of candidate genes for this cancer within or nearby the HLA. Given their chromosomal location within HLA and their determining role in the immune response to tumor cells, we designed a case-controlled study to investigate the potential association of the genetic variation of the tumor necrosis factor-alpha (TNF-alpha) and that of the heat shock protein 70-2 (HSP70-2) with NPC. We used the polymerase chain reaction and restriction enzyme digestion to characterize the variation of the TNF-alpha promoter region and that of the HSP70-2 gene in 140 Tunisian patients with primary NPC and 274 healthy control subjects. No association was found between genetic variations in TNF-alpha and the risk of NPC in Tunisians. In contrast, a significant relative risk of NPC was found associated with the HSP70-2 homozygous genotype (P2/P2) (OR=2.309; P=0.006). The P2/P2 genotype of the HSP70-2 gene may be a marker of increased risk of NPC in Tunisians.

Implication of Xenobiotic Metabolizing Enzyme gene (CYP2E1, CYP2C19, CYP2D6, mEH and NAT2) Polymorphisms in Breast Carcinoma

BackgroundXenobiotic Metabolizing Enzymes (XMEs) contribute to the detoxification of numerous cancer therapy-induced products. This study investigated the susceptibility and prognostic implications of the CYP2E1, CYP2C19, CYP2D6, mEH and NAT2 gene polymorphisms in breast carcinoma patients.MethodsThe authors used polymerase chain reaction and restriction enzyme digestion to characterize the variation of the CYP2E1, CYP2C19, CYP2D6, mEH and NAT2 gene in a total of 560 unrelated subjects (246 controls and 314 patients).ResultsThe mEH (C/C) mutant and the NAT2 slow acetylator genotypes were significantly associated with breast carcinoma risk (p = 0.02; p = 0.01, respectively). For NAT2 the association was more pronounced among postmenopausal patients (p = 0.006). A significant association was found between CYP2D6 (G/G) wild type and breast carcinoma risk only in postmenopausal patients (p = 0.04). Association studies of genetic markers with the rates of breast carcinoma specific overall survival (OVS) and the disease-free survival (DFS) revealed among all breast carcinoma patients no association to DFS but significant differences in OVS only with the mEH gene polymorphisms (p = 0.02). In addition, the mEH wild genotype showed a significant association with decreased OVS in patients with axillary lymph node-negative patients (p = 0.03) and with decreasesd DFS in patients with axillary lymph node-positive patients (p = 0.001). However, the NAT2 intermediate acetylator genotype was associated with decreased DFS in axillary lymph node-negative patients.ConclusionThe present study may prove that polymorphisms of some XME genes may predict the onset of breast carcinoma as well as survival after treatment.

Autoantibodies to tubulin are specifically associated with the young age onset of the nasopharyngeal carcinoma.

By far the highest incidence of the Epstein‐Barr virus (EBV)‐associated nasopharyngeal carcinomas in young subjects was found in North Africa, a region of intermediate risk for adults. We used the immunofluorescence analysis and ELISA to characterize the presence of IgG autoantibodies to the cytoskeleton and nuclear proteins in sera of 82 Tunisian patients with primary nasopharyngeal carcinoma and those of 82 healthy subjects. To assess the specificity of the sera autoreactivity, inhibition tests were carried out using free autoantigens. Analysis of sera autoreactivity in patients with nasopharyngeal carcinoma and in control subjects showed that 23% of the patients had serum reactivity against more than 1 autoantigen tested compared to 1.2% in the control group (p = 10−4). The most frequent auto reactivity in patients sera was found with tubulin and nuclear proteins (19.5% and 22% respectively vs. 6.1% and 1.2% in controls). The IgG auto reactivity inhibition studies indicate that all autoantigens, except native DNA, showed low values of IC50 (concentration of antigen causing 50% inhibition of the antibody binding) reflecting the high affinity of these IgG autoantibodies. When patients and controls were stratified according to their age, IgG autoantibodies to tubulin were found specifically associated with the young age onset of the nasopharyngeal carcinoma (age under 25 years). IgG auto reactivity comparison before and after cancer therapy showed that only anti‐tubulin reactivity was significantly affected by treatment. Our results demonstrate that the autoantibodies to the cytoskeleton and nuclear proteins are associated with the nasopharyngeal carcinoma in Tunisians. The anti‐tubulin IgG autoantibodies may represent a serologic marker for the nasopharyngeal carcinoma in children and adolescents Tunisians.

Associations between HLA class I alleles and the prevalence of nasopharyngeal carcinoma (NPC) among Tunisians.

The high prevalence of nasopharyngeal cancer (NPC) in Southern Asia and Mediterranean Northern Africa suggests genetic predisposition among other factors. While Human Leukocyte Antigen (HLA) haplotypes have been conclusively associated with NPC predisposition in Asians, Northern African Maghrebians have been less intensely studied. However, low resolution serological methods identified weak positive associations with HLA-B5, B13 and B18 and a negative with HLA-B14. Using sequence based typing (SBT), we performed a direct comparison of HLA class I frequencies in a cohort of 136 Tunisian patients with NPC matched for gender, age and geographical residence to 148 normal Tunisians. The bimodal age distribution of NPC in Maghrebians was also taken into account. HLA frequencies in normal Tunisians were also compared with those of Northern Moroccan Berbers (ME) to evaluate whether the Tunisian population in this study could be considered representative of other Maghrebian populations. HLA-B14 and -Cw08 were negatively associated with NPC (odd ratio = 0.09 and 0.18 respectively, Fisher p2-value = 0.0001 and = 0.003). Moreover, positive associations were observed for HLA-B-18, -B51 (split of -B5) and -B57 (p2-value < 0.025 in all) confirming previous findings in Maghrebs. The HLA-B14/Cw*08 haplotype frequency (HF) was 0.007 in NPC patients compared to 0.057 in both Tunisian (OR = 0.12; p2-value = 0.001) and Moroccan controls. This study confirms several previous associations noted by serologic typing between HLA class I alleles and the prevalence of NPC in Maghrebians populations. In addition, we identified a putative haplotype rare in Tunisian patients with NPC that may serve as a genetic marker for further susceptibility studies.

XRCC1 and hOGG1 genes and risk of nasopharyngeal carcinoma in North African countries

Although genetic susceptibility to nasopharyngeal carcinoma (NPC) has been recognized for a long time, little is known about the responsible genes. X‐Ray repair cross‐complementing protein 1 (XRCC1) and human 8‐oxo‐guanine glycosylase 1 (hOGG1) genes are involved in deoxyribonucleic acid (DNA) repair and were found associated with NPC risk in three Asian case–control studies. The objective of the present study was to test these genes in a sample from North Africa, one of the major NPC endemic regions in the world. Three single nucleotide polymorphisms (SNPs) in the XRCC1 gene and one SNP in the hOGG1 gene were genotyped in 598 NPC cases from Morocco, Algeria, and Tunisia and 545 controls frequency matched by recruitment center, age, sex, and urban/rural household. The genotype and allelic distributions for the hOGG1 326Ser/Cys SNP and for the XRCC1 399Arg/Trp, 280Arg/His, and 194Arg/Trp SNPs did not differ significantly among NPC cases and controls. The XRCC1 194Trp allele frequency was significantly lower in the North African population than in Asian population (f = 0.04 vs. 0.31 in Cantonese Chinese and 0.21 Han Chinese). The hOGG1 326Ser allele frequency was significantly higher in the North African population (f = 0.73) than in Asian populations (f = 0.39 in Taiwanese). The results of the present study obtained from a large sample indicate that the XRCC1 and hOGG1 genes are unlikely to play a role in the susceptibility to NPC in North Africans. Our results do not corroborate those found in Asian population on smaller samples. Mol. Carcinog.

Interleukin-10 and interferon-gamma gene polymorphisms in patients with nasopharyngeal carcinoma.

Nasopharyngeal carcinoma (NPC) is a multifactorial disease. Cytokines driving the immune response seem to be disturbed in NPC patients. Since interleukin‐10 (IL‐10) is known to reduce the production of interferon‐gamma (IFN‐γ), we supposed that genetic differences in IL‐10 and IFN‐γ expression could be a mechanism by which NPC cells escape antitumour immune response. As the production of each cytokine is affected by the genetic background, we investigated the possible association between single nucleotide polymorphisms in genes of IL‐10 and IFN‐γ with NPC. Different IL‐10 –1082 G/A and IFN‐γ+874 Τ/Α genotypes were determined in 160 patients with nasopharyngeal carcinoma and 197 healthy controls. No association was found either for each SNP studied alone or for the combined analysis for both IL‐10 and IFN‐γ polymorphisms among NPC patients in comparison with controls. Compared with individuals from high incidence countries, we noted huge significant differences in genotype distribution between individuals from low and intermediate NPC incidence countries. Polymorphisms of the IL‐10 and IFN‐γ do not appear to be associated with NPC risk in the Tunisian population. Nevertheless, we strongly believe that the relationship between cytokines polymorphisms and NPC susceptibility deeply depends on the ethnicity.