Concurrent NRAS-BRAF variants in metastatic colorectal cancer: a Tunisian case report.

Target therapy for metastatic colorectal cancer needs the determination of KRAS, NRAS, and BRAF mutation status to identify patients resistant to anti-EGFR treatment. RAS genes (KRAS/NRAS) are mutated in 40-60% of metastatic colorectal cancer and BRAF in 5-10%. The presence of a double mutation in RAS and BRAF is rare. Therefore, RAS and BRAF mutations were considered exclusive. Herein, we describe a novel concomitant NRAS/BRAF mutation identified in a series of 865 colorectal cancer patients.

Matrix metalloproteinase 3 and 9 as genetic biomarkers for the occurrence of cardiovascular complications in coronary artery disease: a prospective cohort study.

BACKGROUND: Matrix metalloproteinases (MMPs) are widely expressed in atherosclerosis lesions. The disequilibrium of MMPs driving to an overexpression or a lack of its level can be influenced by genetic variations. MMP-3 and MMP-9 may be affected by specific polymorphisms like - 1612 5 A/6A and the - 1562 C/T respectively. We aim in the present study to investigate prospectively the association between the - 1612 5 A/6A MMP-3 and - 1562 C/T MMP-9 polymorphisms and clinical outcomes in patients with coronary artery disease (CAD). This study is elaborated to reveal whether one of these polymorphisms is a probable predictor of cardiovascular complications in this CAD cohort. METHODS AND RESULTS: A total of 168 patients with CAD were prospectively followed up over a period of 5 years. Genotypes for the MMP-3 (-1612 5 A/6A) and MMP-9 (-1562 C/T) polymorphisms were performed using PCR-RFLP. Their levels were measured by ELISA in Sandwich test during the follow-up period, 39 cardiovascular outcomes occurred with 21 repeat targets for revascularization, 3 patients with Myocardial infarction, 8 for heart failure, 5 for Stroke and 2 for cardiovascular mortality. The MMP-3 5 A/6A polymorphism was related to the disease on the contrary of the MMP-9 -1562 C/T. Patients carrying the 5 A allele had a higher level of MMP-3 level and those who carried the 6 A allele had lower level (p = 0.04). After applied multivariable Cox-hazard models we revealed that the 6 A allele is independently associated to the disease complication. Kaplan-Meier survival test revealed that individuals having the 6 A allele had a lower survival rate than those with the 5 A allele (p = 0.04). CONCLUSION: Our study suggests the disruption of the MMP-3 level may be due to the existence of the polymorphism - 1612 residing in its promoter region. MMP-3 can be considered as a marker of diagnosis and prediction in cardiovascular events.

Soluble MICA and anti-MICA Antibodies as Biomarkers of Nasopharyngeal Carcinoma Disease.

The MHC class I chain-related molecule A (MICA) is a ligand for the activating natural killer (NK) cell receptor NKG2D. A part from its genetic diversity, MICA is characterized by the presence of membrane-bound and soluble isoform (sMICA) and by the propensity to elicit antibody-mediated allogeneicity (MICA Abs). Altogether such properties are important in the cancer setting. Here, we investigated whether MICA polymorphism, serum level of sMICA and MICA antibodies (Abs) may influence nasopharyngeal carcinoma (NPC) risk. 274 NPC naïve of treatment patients and 275 healthy individuals, all originating from Tunisia were included and genotyped. Among them, 160 sera from patients and 51 from controls were analyzed for the sMICA level by ELISA and were tested for the presence of MICA Abs by Luminex assay. The statistical analysis showed that: (1) we extend and confer our previous finding concerning Val/Val association with risk of NPC (p = .02, OR = 1.56; 95%CI [1.12-2.11]). (2) The higher level of sMICA characterized patients advanced stage of the disease. (3) The 18 (78%) of patients having MICA Abs exhibit all a non-advanced stage of the tumor extension at presentation. MICA129 Met /Val, sMICA and MICA Abs could be potential biomarkers of prediction, the diverse staging of NPC and hence prognostic and treatment.

MICA-129 Met/Val polymorphism could be a genetic biomarker for Familial Breast Cancer in the Tunisian population.

Identification of candidate genes associated with susceptibility of breast cancer can have a significant impact at a cancer management national healthcare systems level, making genetic testing more affordable and cost-effective. We have previously shown that the major histocompatibility complex class I-related chain A (MICA) was related to breast cancer and plays an important role in modulating immune response mechanisms through NKG2D receptor activation. Compared to our previous study, in this work, we recruited a new cohort composed of 354 unrelated Tunisian women affected by breast cancer and 380 age-matched women as controls, all genotyped for MICA-129 Met/Val (rs 1051792). Subsequently, we exanimated the distribution of this polymorphism in ten families. As a result, an association was found between the Val allele and Val/Val genotype and the risk of breast cancer (p = 2.5 × 10-15 ; OR = 2.40; p = 6.5 × 10-13 ; OR = 3.03, respectively). Stratified analysis with age and family history of cancer revealed an association between the Val/Val genotype and younger patients <40 years (p = .003; OR = 2.03). Among those patients having a family history of cancer, 68% had a Val/Val genotype (p = .02; OR = 1.82). In the family study, an analyse of pedigrees revealed that the majority of families showed the development of breast cancer at a young age. Moreover, all patients diagnosed with early-onset breast cancer had a Val/Val genotype. Our results lead us to propose that this polymorphism may be an inherited genetic biomarker contributing to an increased breast cancer risk in Tunisian women.

The Impact of HLA-G 3'UTR Polymorphisms in Breast Cancer in a Tunisian Population.

Human leukocyte antigens G and E (HLA-G and HLA-E) are nonclassical major histocompatibility complex (MHC) class I molecules. These molecules play an important role in immune surveillance by inhibiting natural killer and cytotoxic T cells responsible for immune escape. The expression of HLA-G and HLA-E has been associated with several diseases including tumor. The main objective of the study is to evaluate the impact of three HLA-G 3'UTR potential polymorphisms: +3187 A > G (rs9380142), +3142 G > C (rs1063320), +2960 14-base pair (bp) Insertion/Deletion (Ins/Del) (rs66554220), and the HLA-E*01:01/01:03 A > G (rs1264457) polymorphism in Tunisian breast cancer population. A total of 355 patients and 381 controls were genotyping for HLA-G and HLA-E polymorphisms using a Taq Man assay. +3142 C allele and +3142 C/C genotype were significantly associated with increased risk of breast cancer (p = 0.00002; OR = 1.58; 95% CI = 27-1.97) (49% versus 35%; p = 0.0001; OR = 1.79; 95% CI = 1.32-2.44). In addition, Del allele and the homozygous state for Del/Del genotype confer a risk for breast cancer (52% versus 45%, p = 0.006; OR = 1.33, 95% CI = 1.08-1.64) (28% versus 22%, p = 0.039; OR = 1.43, 95% CI = 0.90-2.25). However, no statistical significant differences were reported for HLA-G + 3187 A > G and HLA-E variations and breast cancer in a Tunisian population. The found results indicate that HLA-G may play an important role in the breast cancer.

MDM2 344T>A polymorphism; could it be a predictive marker of anthracycline resistance?

PURPOSE: To find a possible association between the Mouse Double Minute 2(MDM2) 344T>A, alone and in combination with p53 72 Arg/Pro polymorphism, and resistance to anthracycline-based chemotherapy of breast cancer in Tunisia. METHODS: This study enrolled 542 patients with invasive ductal carcinoma (IDC) treated with anthracycline-based chemotherapy. Genomic DNA was isolated from whole blood, using the phenol chloroform method. Anthracycline response was scored according to the World Health Organization (WHO). MDM2 344T>A polymorphism was genotyped using real time polymerase chain reaction (RT-PCR) with the TaqMan method. Data was statistically analyzed using the x2 test. RESULTS: Response was evaluated in 400 patients, of whom a quarter was found to be resistant to chemotherapy. Genetic data revealed that resistance to anthracycline-based chemotherapy did not seem to be correlated with 344T>A polymorphism in the studied population. Also, no significant association was found between the single nucleotide polymorphism (SNP) 344T>A status and clinicopathologic parameters (p>0.05 for all comparisons). Moreover, analysis of p53 rs1042522 and MDM2 rs1196333 combination showed no significant association between these two genetic variants and anthracycline resistance (p=0.2). CONCLUSIONS: Our findings provide no evidence indicating that SNP 344 T>A may affect response to anthracycline-based chemotherapy. However, the results obtained from the combination of SNPs 344T>A of MDM2 and 72 Arg/Pro of p53, do not support the hypothesis of the prominent role of common p53 and MDM2 variations in the genetic mechanisms of chemotherapy resistance in breast cancer.

Impact of toll-like receptor 4 variations on nasopharyngeal carcinoma risk and survival in tunisian population.

INTRODUCTION: The Toll-like receptor 4 (TLR4), an important member of the host's innate immune response, is coded by a polymorphic gene. This polymorphism could be a predisposing factor for NasoPharyngeal Carcinoma (NPC). AIM: To determine the association between TLR4 gene polymorphisms and the susceptibility to NPC in a cohort of Tunisian affected patients. METHODS: Genomic DNAs from 245 unrelated patients affected by undifferentiated carcinoma type (UCNT) and 264 unrelated healthy controls were genotyped for the five single nucleotides polymorphisms (SNPs) of TLR4 locus (4434 A>G (rs1927914),7263 G>C (rs10759932), 6134 A>G(rs4986790), 8851C>T (rs 4986791), 5272 T>C(rs11536889), +8469 T>C (rs11536891)) by Taqman® 5'-nuclease assay. RESULTS: Among all polymorphisms studied, only the rs4986790 G and rs4986791 T alleles were significantly more prevalent in patients' group than controls (45% vs. 38%; p=0.03; pc=0.06) and increased the risk of the NPC (OR=1.3, 95% CI=1.01-1.69). Also, we found that the frequency of the rs4986790 AA and rs4986791 TT genotypes was significantly higher in controls than in patients (25.7% vs 37%; p=0.006, pc=0.02) and conferred a protector factor in NPC (OR= 0.59, 95% CI= 0.39-0.87). Further, based on the Kaplan-Meier survival curve we observed also the positive effect ofrs1927914 AA genotype on a prognostic of NPC (p=0.006; pc=0.01). CONCLUSION: Our study demonstrated that impaired production of TLR4 seems to be a risk factor of NPC development but functional studies are needed to confirm these findings. As to rs1927914 AA appears to be a good biomarker for better survival in a patient with NPC.

[Phenotypic and molecular changes of hemoglobinopathies in cancer]. / Variation phénotypique et moléculaire des hémoglobinopathies en milieu carcinologique.

BACKGROUND: The abnormalities of the haemoglobin divide into qualitative abnormalities and quantitative abnormalities. This variant contains polymorphisms often useful as markers of population. At present more than 693 types of abnormal haemoglobin are listed. This hemoglobinopathies can arise at reached subjects of cancerous pathologies. AIM: To bring to report association hémoglobinopathies-cancers. METHODS: Our study was realized to the Institute Salah azaiz (ISA) concerning hémoglobinopathies in carcinologic environment over a period spreading out of May 2004 in February 2008. The phenotypic and biochemical study of haemoglobin revealed the presence of 328 carriers of abnormalities of the haemoglobin on a total of 10550 patients followed to ISA. 7 types of abnormalities of the haemoglobin were identified (HbS, Hb C, Hb O arab, Hb D, Hb G, fast mutant and ß thalassemia. RESULTS: The sickle cell line represents the most wide-spread hémoglobinopathie (51.3 %). 48.2 % of the carrier subjects of abnormalities of the haemoglobin are followed for malignant pathologies. Among these hemoglobinopathies, we revealed the presence of two fast mutants of the haemoglobin corresponding to the haemoglobin Bangkok. This type of rare mutant is described for the first time in Tunisia. According to the genotypic study by these two cases, the haemoglobin Bangkok results from the replacement at the level of the chain ß some aspartic acid by the wisteria, further to a transfer at the level of the codon 56. A phenotypic study family revealed the presence of similar transfers at certain members of the family. CONCLUSION: Our work allowed us to notice a relatively important frequency of rare abnormalities of the haemoglobin at patients presenting varied tumoral processes.

Tumor DNA hypomethylation of LINE-1 is associated with low tumor grade of breast cancer in Tunisian patients.

DNA hypomethylation of long interspersed repetitive DNA retrotransposon (LINE-1) and Alu repeats elements of short interspersed elements family (SINEs) is an early event in carcinogenesis that causes transcriptional activation and leads to chromosomal instability. In the current study, DNA methylation levels of LINE-1 and Alu repeats were analyzed in tumoral tissues of invasive breast cancer in a Tunisian cohort and its association with the clinicopathological features of patients was defined. DNA methylation of LINE-1 and Alu repeats were analyzed using pyrosequencing in 61 invasive breast cancers. Median values observed for DNA methylation of LINE-1 and Alu repeats were considered as the cut-off (59.81 and 18.49%, respectively). The results of the current study demonstrated a positive correlation between DNA methylation levels of LINE-1 and Alu repeats (rho=0.284; P<0.03). DNA hypomethylation of LINE-1 was also indicated to be associated with low grade (P=0.023). To the best of our knowledge, the current study is the first study regarding DNA methylation of LINE-1 and Alu repeats element in breast cancer of the Tunisian population. The results of the current study suggest that, since hypomethylation of LINE-1 is associated with low grade, it could be used as a biomarker for prognosis for patients with breast cancer.

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.

A genome-wide RNAi screen reveals essential therapeutic targets of breast cancer stem cells.

Therapeutic resistance is a major clinical challenge in oncology. Evidence identifies cancer stem cells (CSCs) as a driver of tumor evolution. Accordingly, the key stemness property unique to CSCs may represent a reservoir of therapeutic target to improve cancer treatment. Here, we carried out a genome-wide RNA interference screen to identify genes that regulate breast CSCs-fate (bCSC). Using an interactome/regulome analysis, we integrated screen results in a functional mapping of the CSC-related processes. This network analysis uncovered potential therapeutic targets controlling bCSC-fate. We tested a panel of 15 compounds targeting these regulators. We showed that mifepristone, salinomycin, and JQ1 represent the best anti-bCSC activity. A combination assay revealed a synergistic interaction of salinomycin/JQ1 association to deplete the bCSC population. Treatment of primary breast cancer xenografts with this combination reduced the tumor-initiating cell population and limited metastatic development. The clinical relevance of our findings was reinforced by an association between the expression of the bCSC-related networks and patient prognosis. Targeting bCSCs with salinomycin/JQ1 combination provides the basis for a new therapeutic approach in the treatment of breast cancer.

[Biological investigation of thyroid cancer]. / Exploration biologique du cancer de la thyroide.

Thyroid carcinomas represent the most common endocrine malignancy, and several biological markers are proposed according to the different types of this cancer: for papillary cancer, thyroglobulin constitutes an excellent prognostic factor and rearrangements of ret oncogene can be useful in diagnosis. In sporadic medullary carcinoma, calcitonin is a diagnosis marker of choice, and coupled with ACE, can prevent relapse. Regarding familial medullary carcinoma, mutation screening in ret oncogene leads to early detection of new cases.

Are HLA-E*0103 alleles predictive markers for nasopharyngeal cancer risk?

BACKGROUND: Nasopharyngeal carcinoma (NPC) is a particular entity of head neck cancer, tightly related to Epstein-Barr virus infection and thus to HLA genes. In this study, we aimed to analyze HLA-E polymorphism in NPC advent and prognosis. 130 unrelated patients with CNP and 180 unrelated and healthy controls were included in our study. HLA-E genotyping was performed by PCR/RFLP method; SPSS (13.0) was used for statistical analysis, and survival curbs were established with the "Kaplan-Meier" method (Log Rank<0.05). RESULTS: We found a significant difference within HLA-E*103 variants between patients and controls: E*1031 and E*1032 were associated with CNP (OR=1.613, p=0.013 and OR=1.0809, p=0.055), and E*1033 with controls (OR=0.254, p<10(-4)). CONCLUSION: Our study reveals that HLA-E polymorphism is associated with nasopharyngeal cancer. HLA-E expression studies could be used to understand the implication of E*103 variants.

[Genetic polymorphism of cytochrome P450 2E1 and the risk of nasopharyngeal carcinoma]. / Polymorphisme génétique du cytochrome P450 2E1 et le risque du cancer du nasopharynx.

Cytochrome P450 2E1 (CYP2E1) is a detoxifying enzyme that belongs to the phase I metabolism of xenobiotics. This enzyme is encoded by a highly polymorphic gene whose common polymorphism corresponds to the substitution of cytosine (C) and thymine (T) at position -1019 (rs2031920). This polymorphism has been identified in several cancers including nasopharyngeal cancer (NPC). The study involved 124 patients with nasopharyngeal carcinoma, compared with 166 healthy controls. The presence or absence of the polymorphism is determined by PCR-RFLP. The frequency comparison between the two groups is determined by the χ(2) test. The analysis of our results showed a significant difference between the two groups regarding the mutant genotype (C2/C2) (5% vs. 0.5%, P=0.04) and has a risk factor for NPC in Tunisia (OR=8.39; CI 95% [0.99-388.1]). Also, the C2 allele was significantly associated with the group of patients than the control group (6% vs. 2%, P=0.016) and increased three times the risk of NPC in Tunisia (OR=2.99, CI 95% [1.12-8.79]). Our results confirm the results reported in other populations and emphasize the importance of the involvement of this gene in the development of detoxification of the NPC, which seems more and more strongly associated with environmental factors.

Role of p53 Codon72 SNP in breast cancer risk and anthracycline resistance.

BACKGROUND/AIM: We undertook a case-control and a case-case study to examine the possible association of p53 codon72 polymorphism with the breast cancer risk and resistance to anthracycline-based chemotherapy. PATIENTS AND METHODS: Case-control study: This study enrolled 175 patients with breast cancer treated at the Salah Aziez Institute and 159 healthy Tunisian women (matched for age, ethnicity and origin), used as a control, with no clinical evidence of any neoplastic disorder. Case-Case study: 400 breast cancer patients, with invasive ductal carcinoma (IDC) treated with anthracycline based-chemotherapy. Genomic DNA was isolated from whole-blood leucocytes using the phenol-chloroform method. Anthracycline response was scored according to the World Health Organization (WHO) criteria. P53 codon72 polymorphism was genotyped using real-time polymerase chain reaction (RT-PCR) with the TaqMan method. Data were statistically analyzed using the Chi-square test. RESULTS: Clinical data revealed that among the 400 patients, one quarter was resistant to chemotherapy treatment. Genetic data revealed that the p53 Arg72Pro genotype was found to be greatly associated with breast cancer risk (p<0.001), as well as tumor site (p=0.046). However, resistance to anthracycline-based chemotherapy does not seem to be correlated with p53 codon72 polymorphism in our population. Also, the distribution of tumor size, lymph node involvement and tumor grade was not significantly different among the polymorphic variants. CONCLUSION: We conclude that p53 codon72 polymorphism is involved in susceptibility to developing breast cancer. It may be a factor of progression when breast sites are taken into account. However, there is no evidence indicating that Arg72Pro SNP may influence response to anthracycline-based chemotherapy.

Polymorphisms in oxidative stress-related genes are associated with nasopharyngeal carcinoma susceptibility.

Nasopharyngeal carcinoma (NPC) is a complex multifactorial disorder involving both genetic and environmental factors. Polymorphisms of genes encoding nitric oxide synthase (NOS) and antioxidant glutathione-S transferases (GSTs) have been associated with various tumors. We examined the combined role of NOS3, NOS2 and GST polymorphisms in NPC risk in Tunisians. We found that NOS3−786C allele and −786 CC genotype, NOS3+894T allele and +894 GT+TT genotypes, NOS2−277 G allele and −277 GG genotype, and GSTT1 del/del genotype, are more prevalent in NPC patients as compared to healthy controls. Our results suggest that genetically driven dysfunction in red­ox stress pathway could augment the risk in NPC-susceptible individuals.

[Immunogenetics of nasopharyngeal carcinoma]. / Immunogénétique du cancer du nasopharynx.

Nasopharyngeal carcinoma (NPC) is a complex multifactorial disorder involving both genetic and environmental factors. Genetic predisposition linked to the immune system has been associated with various tumors. This involves genetic diversity of the genes encoding the molecules of the immune response such as inflammation and anti-tumor surveillance. In this work, we examined the impact of the immunogenetic diversity on the risk of the NPC in different populations studied. These data show that the interindividual variability of the genetic regulation of immune processes increases the risk of NPC in individuals previously predisposed due to other risk factors (genetic / environmental). This synthesis, in addition to the predictive aspects, could provide innovative research for the development of new therapeutic approaches.

[Nasopharyngeal carcinoma in Tunisian children: retrospective epidemiological, clinical and biological study about 48 cases]. / Le carcinome du nasopharynx chez l'enfant tunisien: étude rétrospective épidémiologique, clinique et biologique, à propos de 48 cas.

OBJECTIVE: Report epidemiological, clinical and biological aspects of nasopharyngeal carcinoma in Tunisian children. PATIENTS AND METHODS: Our retrospective study from 1994 to 2001 included all children treated for nasopharyngeal carcinoma in the Salah Azaïz Cancer Institute of Tunis. Initial investigation consisted of ENT and general examination, nasopharyngeal CT-scan, abdominal echography, chest X-ray and bone scintigraphy. Biological markers included blood-count, erythrocytes sedimentation and serum lactic dehydrogenase. All children received neoadjuvant chemotherapy (adriamycin, cisplatin) and irradiation therapy. RESULTS: There were 48 children with a median age of 13,7 years and a sex ratio of 1,4 (28/20). Lesions are staged T2, T3 and T4 in 2,1 %, 18,7% and 79,2% of cases. All patients have cervical palpable nodes at diagnosis classified as N1 (8,3%), N2 (33.3%) and N3 (58.3%). A significant correlation was found between serum lactic dehydrogenase and the N stage (p = 0.02). After follow up, recurrence of disease was noted for three children, persistent disease for two children and metastatic disease in five cases. The overall and relapse free survival at 5 years were 79.1% and 68.9% respectively. Patients aged 13 or lower had poorer 5 overall survival rate (72.3%) than older age group (84.2%).