Nejla Stambouli

MicroRNAs 146a and 147b Biomarkers for Colorectal Tumor’s Localization

The recently identified class of microRNAs (miRs) provided a new insight into cancer research, since abnormalities of members of microRNAs family have been found in various types of cancer. However, the relationship between five miRNAs (miR146a, miR155, miR21, miR135a, and miR147b) and colorectal cancer remains unclear. In the present study, we examined expression of these miRNAs in 25 pair-matched colon cancer tissues and normal colon mucosa. The expression levels of miR146a, miR155, miR21, miR135a, and miR147b were quantified by real-time PCR. We found that miR21, miR146a, and miR135a were all expressed at higher levels in colon tumors. On the other hand, miR146a and miR147b expressions are significantly higher in left colon compared to right colon. These two miRs, especially miR146a, seemed to be markers for the left colon tumors. Moreover, significant proportional and inverse correlations were found between miR expressions in tumor and healthy tissue, and the correlations profiles were different depending on cancer localization. Taken together, these results lead us to suggest the presence of different mechanisms regulating miRs expression and consequently their target genes in left and right colon. So the pathway of colorectal carcinogenesis would be different according to the site of the tumor.

Positive link between variant Toll-like receptor 4 (Asp299Gly and Thr399Ile) and colorectal cancer patients with advanced stage and lymph node metastasis

Toll-like receptors (TLRs) are considered as major endotoxin-signaling receptor and as crucial sensors of innate immunity. TLRs recognize pathogen-associated molecular patterns; induce effectors genes involving inflammatory cytokines and therefore initiation of adaptative immune responses against pathogens. Recently, it has been shown that TLRs are involved in tumor progression. In fact, increased level of TLR4 is associated with progression of colon malignancies. Even, TLR4 polymorphism has been shown associated with susceptibility to have colorectal cancer. Our study aimed to investigate an association between TLR4 Asp299Gly (D299G) and Thr399Ile (T399I) polymorphisms in Tunisian patients with colorectal cancer. Using a primer extension method (SNaPshot), we genotyped two variants of TLR4 D299G and T399I in 100 patients with colorectal cancer and 140 healthy controls in Tunisian population. Interesting, we noted a significant association between T399I polymorphism and tumor differentiation (p = 0.027) and tumor architecture (p = 0.02) in colorectal cancer (CRC) patients. We also showed a significant association of D299G with an increased risk of advanced stage (p = 0.03). Finally, we observed a positive link between D299G and T399I polymorphisms and CRC patients with lymph node (p = 0.00024; p = 0.0005, respectively) and metastasis (p = 0.001; p = 0.002, respectively). However, we found no evidence to support a significant association between TLR4 D299G and T399I polymorphisms and colorectal cancer susceptibility. Our findings suggest that TLR4 D299G and T399I polymorphisms are significantly associated with clinical features variables. TLR4 polymorphisms may serve as biomarker of disease progression. Therefore, our results need confirmation in even larger studies.

Breast Cancer in Tunisia: Association of Body Mass Index with Histopathological Aspects of Tumors

BACKGROUND Previous studies have suggested a link between obesity and breast cancer (BC). However, there is no universal consensus, especially in population based studies. Because only few studies have been conducted on African women, we aimed here to assess the relationship between BMI at time of diagnosis and the BC histopathological features among Tunisian patients according to menopausal status using a hospital-based prospective cohort study. MATERIALS AND METHODS Clinical and pathological data were collected from 262 patients stratified on four groups according to their BMI. The relationship between BMI and histopathological features at diagnosis was analysed using univariate and multivariate analysis. Receiver-operating characteristic (ROC) curves were used to evaluate the performance of BMI in predicting of high tumor grade, in comparison to ki-67 index of proliferation. RESULTS Obesity was correlated with larger tumors, advanced grade and with ER-PR- Her2+ BC subtype. An association of BMI with tumor size and tumor grade was observed in both premenopausal and postmenopausal women. Additionally, a significant association between BMI and ER+, ER+PR+Her2+ and ER-PR-Her2+ status was revealed for premenopausal patients, while only ER+PR+Her2+ was associated with BMI for postmenopausal women. Finally, our results showed that compared to Ki67 proliferation index, BMI is a useful prognostic marker of high grade BC tumors. CONCLUSIONS These data are the first to show that in Tunisia obese women suffering from BC have significantly larger tumors and advanced tumor grade and that higher BMI might influence tumor characteristics and behavior.

Experimental and Computational Studies Indicate Specific Binding of pVHL Protein to Aurora-A Kinase

Overexpression of Aurora-A kinase is commonly detected in many cancers, whereas the von Hippel-Lindau protein (pVHL) is frequently mutated or absent in renal cell carcinoma and is involved in the Ub proteasome complex, an important degradation pathway. In order to establish a link between Aurora-A overexpression and lack of pVHL protein, we hypothesized that pVHL regulates Aurora-A expression through a physical interaction. We present the first evidence, from both biological assays and computational biology techniques, that human pVHL binds strongly to Aurora-A kinase. Extensive molecular modeling, docking, and dynamic simulations demonstrate that the structure of the pVHL protein would allow it to bind to the TPX2 binding region of Aurora-A. In view of Aurora-As importance as a therapeutic target for the treatment of cancer, this observation provides novel insights into the Aurora-A/pVHL pathway. In addition, the detailed Aurora-A/pVHL binding structure obtained will be valuable for the design of future Aurora-A inhibitors as therapeutic agents.

Influence of socioeconomic lifestyle factors and genetic polymorphism on type 2 diabetes occurrences among Tunisian Arab and Berber groups of Djerba Island

Type 2 diabetes mellitus (T2DM) is characterized by three major metabolic abnormalities: impaired insulin-stimulated glucose uptake in muscle and adipose tissues, alterations in glucose-stimulated insulin secretion, and increased hepatic glucose production. Both genetic and environmental factors contribute to its development. The insulin gene (INS), insulin receptor gene (INSR), and insulin receptor substrate 1 gene (IRS1), identified by polymerase chain reaction and digestion with selected restriction enzymes PstI, NsiI, and BstnI, have been proposed as T2DM candidate genes. To determine the contribution of genetic and environmental factors on the occurrence of T2DM, we examined the frequency of T2DM among two ethnically diverse populations, Arabs and Berbers, who have shared the same environment, the island of Djerba, for thousands of years. Both populations have a high prevalence of obesity,T2DM, and a high consanguinity rate. A total of 162 T2DM men and women were matched to 110 healthy male and female controls. Results showed that the NsiI polymorphism in INSR and BstnI polymorphism of IRS1 were significantly associated with T2DM only among the Berber group. The PstI polymorphism in INS, was not associated with T2DM in either group. Sedentary lifestyles, lower physical activity, and lower educational levels were associated with T2DM among the Berber group. These findings suggest that the insulin receptor gene and lifestyle factors in combination may contribute to the occurrence of T2DM in the Berber portion of this island population.

Structural analysis of two novel mutations in MCFD2 gene causing combined coagulation factors V and VIII deficiency

Combined factor V and factor VIII deficiency (F5F8D) is a rare autosomal recessive bleeding disorder reported usually in the context of consanguinous marriage. F5F8D is characterized by mild-tomoderate bleeding and coordinate reduction in plasma FV and FVIII levels, as well as platelet FV level (OMIM 227300) [1]. The disease is caused by mutations in genes encoding lectin mannose binding protein (LMAN1) and multiple coagulation factor deficiency 2 (MCFD2), which are the components of the endoplasmic reticulum (ER)-Golgi intermediate compartment (ERGIC-53) involved in the FV and FVIII intracellular transport [1, 2]. LMAN1 is a type-I integral membrane protein that was first described as a 53-kDa marker of the ERGIC [3], whereas MCFD2 is a soluble luminal protein

Involvement of IL17A, IL17F and IL23R Polymorphisms in Colorectal Cancer Therapy

IL23/IL17 pathway plays an important role in the development of inflammatory bowel diseases (IBD). In general, the genes encoding the cytokines are genetically polymorphic and polymorphisms in genes IL23R and IL17 have been proved to be associated with its susceptibility to inflammatory diseases as well as cancer including colorectal cancer. Moreover, it has been shown that these interleukins are involved in anti-tumor or pro-tumor effects of various cancers. Previously, we showed that there is a significant association between IL17A, IL17F and IL23R polymorphisms as well as the occurrence of colorectal cancer and the clinical features of the disease. The purpose of the present work is to investigate an association between IL17A, IL17F and IL23R polymorphisms in 102 Tunisian patients with colorectal cancer treatment. The association was analyzed by statistical tools. We found that patients with mutated genotypes of IL17A G197A SNP could be a risk factor for the inefficiency of chemotherapy and radiotherapy. Unlike IL17F variant, patients with wild type genotypes require surgery and adjuvant chemotherapy. On the one hand, we found no evidence that supports a significant association between IL23R polymorphism and the combined genotypes of these three genes and the colorectal cancer treatment. On the other hand, we showed that there is an important interaction between IL17A/IL17F polymorphisms and the stage of the disease as well as its treatment. Finally, patients with IL17F wild type genotype highlighted that there is a valid longer OS without all treatments and with radiotherapy and a neoadjuvant chemotherapy. In contrast, we observed that there are no relationships between IL17A, IL23R and the survival of these patients neither with nor without the treatment. Our results suggest that polymorphisms in IL17A and IL17F genes may be a predictive source of colorectal cancer therapy type. Therefore, IL17F may serve as an independent prognostic factor for overall survival in patients with colorectal cancer.

Structural insight into the binding complex: β-arrestin/CCR5 complex

The chemokine receptor 5 (CCR5) belongs to the superfamily of serpentine G protein-coupled receptors (GPCRs). The DRY motif (Asp, Arg, Tyr) of the intracellular loop 2 (ICL2), which is highly conserved in the GPCRs has been shown to be essential for the stability of folding of CCR5 and the interaction with β-arrestin. But the molecular mechanism by which it recognizes and interacts with β-arrestin has not been elucidated. In the present study, we described the active state of the β-arrestin structure using normal mode analysis and characterized the binding cleft of CCR5-ICL2 with β-arrestin using SABRE© docking tool and molecular dynamics simulation. Based on our computational results, we proposed a mode of binding between the ICL2 loop of CCR5 and β-arrestin structure, and modeled the energetically stable β-arrestin/CCR5 complex. In view of CCR5’s importance as a therapeutic target for the treatment of HIV, this observation provides novel insight into the β-arrestin/CCR5 pathway. As a result, the current computational study of the detailed β-arrestin/CCR5 binding complex could provide the rationale for the development of next generation of HIV peptide inhibitors as therapeutic agents.

The impact of smoking and polymorphic enzymes of xenobiotic metabolism on the stage of bladder tumors: a generalized ordered logistic regression analysis.

Cigarette smoking is the predominant risk factor for bladder cancer in males and females. The tobacco carcinogens are metabolized by various xenobiotic metabolizing enzymes such as N-acetyltransferases (NAT) and glutathione S-transferases (GST). Polymorphisms in NAT and GST genes alter the ability of these enzymes to metabolize carcinogens. In this paper, we conduct a statistical analysis based on logistic regressions to assess the impact of smoking and metabolizing enzyme genotypes on the risk to develop bladder cancer using a case–control study from Tunisia. We also use the generalized ordered logistic model to investigate whether these factors do have an impact on the progression of bladder tumors.

Diagnosis System for Predicting Bladder Cancer Recurrence Using Association Rules and Decision Trees

In this work we present two methods based on Association Rules (ARs) for the prediction of bladder cancer recurrence. Our objective is to provide a system which is on one hand comprehensible and on the other hand with a high sensitivity. Since data are not equitably distributed among the classes and since errors costs are asymmetric, we propose to handle separately the cases of recurrence and those of no-recurrence. ARs are generated from each training set using an associative classification approach. The rules’ uncertainty is represented by a confidence degree. Several symptoms of low intensity can be complementary and mutually reinforcing. This phenomenon is taken into account thanks to aggregate functions which strengthen the confidence degrees of the fired rules. The first proposed classification method uses these ARs to predict the bladder cancer recurrence. The second one combines ARs and decision tree: the original base of ARs is enriched by the rules generated from a decision tree. Experimental results are very satisfactory, at least with the AR’s method. The sensibility rates are improved in comparison with some other approaches. In addition, interesting extracted knowledge was provided to oncologists.