Protective Effect of Tunisian Flaxseed Oil against Bleomycin-Induced Pulmonary Fibrosis in Rats.

The aims of this study are to investigate the preventive effect of flaxseed oil (FO) on bleomycin (BLM)-induced pulmonary fibrosis (PF). Thirty adult male Wistar rats (180-220 g) were randomly divided into three groups. The control group (G1) received no treatment, the group (G2) received only intratracheally BLM, and the group (G3) received FO (2 mL/kg body weight) once a day for 60 days + BLM (4 mg/kg body weight "bw"). Our results demonstrated that FO protected against BLM-induced PF, by increasing proline, fructose, glucose, glyceride, choline, lactate, and malate metabolites in bronchoalveolar lavage fluid (Balf) which are involved in anti-inflammatory reactions. Also, FO-treatment reduced the score of fibrosis and the inflammatory index and revealed a decrease in tumor growth factor beta (TGFß) density in alveoli, inflammatory infiltrate and fibrocytes, comparatively to the BLM group. As well, our data demonstrated that acute BLM-induced fibrosis was accompanied by an oxidative stress in lung tissue as assessed by an increase of lipid peroxidation as well as antioxidant enzyme activities depletion such as superoxide dismutase (SOD) and catalase (CAT). The FO treatment reversed all disturbances of BLM-induced oxidative stress parameters, and increased fatty acids levels promoting anti-inflammatory reactions especially in erythrocytes (linoleic, α-linolenic, docosapentaenoic acids).

Hypericum Humifusum Leaves Attenuates Hepatic Ischemia-Reperfusion Injury in a Rat Model.

INTRODUCTION: Effective prevention strategies require specific actions during the different phases of ischemia-reperfusion (I-R) injury. The objective of our study is to evaluate the effect of aqueous extract of Hypericum humifusum leaves (HHL) on liver I-R model in Rat. MATERIAL AND METHODS: Animals were subjected to 90 min of hepatic ischemia followed by reperfusion (120 min). HHL extract (25 mg/mL/kg) was injected 15 min before reperfusion. To evaluate the effect of HHL extract on I-R, we have monitored transaminases levels, Malondialdehyde (MDA) concentration, histological lesions (apoptosis and necrosis) and compared the results to a reference oxidant vitamin E. RESULTS: The determination of total phenol extracts of HHL was 59.91 ± 0.35 mg of Gallic Acid/g dry plant material with higher antioxidant activity (91.73% ± 1.67) compared to vitamin E (87.42%). Using aqueous extract of HHL, we noted a significant decrease of AST and ALT [1129 UI (585/1995) and 768 UI (335/1375)] compared to no-treated group [5,585.5 UI (5,035/12,070) and 8,099.5 UI (5,040/12,326)] as a decrease in MDA content [85.7% protection (50.9/91.5)]. HHL extract reduce the damage induced by I-R of 48.7% (27/48.7) and 96.1% (95.7/96.5) for necrosis and apoptosis lesions respectively. CONCLUSION: HHL aqueous extract have potential to protect liver from the damage effect induced by I-R better than vitamin E solution.

Nigella sativa, a traditional Tunisian herbal medicine, attenuates bleomycin-induced pulmonary fibrosis in a rat model.

The present study investigated the effects of Nigella sativa oil (NSO) on bleomycin (BLM)-induced lung fibrosis in rats. The rat model of pulmonary fibrosis (PF) was established by intratracheal instillation of BLM, and the effect of 1ml/kg oral NSO treatment once daily observed. The effect of NSO was studied over a period of 50daysusing 1H RMN analysis on the urine and broncho alveolar lavage fluid (Balf) of the rats. Histopathological (inflammation and fibrosis) and immunohistochemical (TGF-ß1 density) changes were evaluated. Results found that the BLM group showed a significant increase in inflammatory index (II), fibrosis score (FS) and TGF-ß1 distribution in the lung inflammatory infiltrate, accompanied by a decreased urinary secretion of Krebs cycle intermediates, including acetate, pyruvate, carnitine, trimethylamine-N-oxide and succinate. However, at the same time point, NSO treated rats had a reduced II and FS, and had an increased urinary secretion of histidine, fumarate, allantoin and malate. In conclusion, NSO treatment attenuated the effects of BLM-induced PF, by supporting lung, liver and kidney activity in resisting PF. These findings provide an insight into the preventive and therapeutic potential of NSO in the treatment of PF.

Protective Effect of Pistacia lentiscus Oil Against Bleomycin-Induced Lung Fibrosis and Oxidative Stress in Rat.

We aimed in the present study to investigate the protective effect of Pistacia lentiscus oil against bleomycin-induced lung fibrosis as well as the involvement of oxidative stress in such protection. In this respect, adult male Wistar rats were used and divided into three groups of twenty each: control (NaCl, 0.9%), bleomycin, and bleomycin (4 mg/kg b.w.) + P. lentiscus oil (3 g/kg, b.w.). Animals were pretreated for 30 days before the induction of fibrosis by bleomycin and 1 wk after the induction of fibrosis. The oil principal compounds detected by gas chromatography analysis are: Linoleic and palmitic acids (70.6 and 24.7%, respectively). Our data demonstrated that P. lentiscus oil protected against bleomycin-induced fibrosis as evidenced by TGFß immunostaining increase in lungs fibrocytes as well as inflammatory infiltrate. We also showed that acute bleomycin-induced fibrosis was accompanied by an oxidative stress in lung tissue as assessed by an increase of lipid peroxidation as well as antioxidant enzyme activities depletion such as superoxide dismutase (SOD) and catalase (CAT). More importantly, P. lentiscus oil treatment reversed all bleomycin-induced oxidative stress parameters disturbances. In conclusion, we suggest that P. lentiscus oil had potent protective effects against bleomycin-induced fibrosis due in part to its antioxidant properties.

Protective effect of Ulva lactuca extract during hepatic cold preservation in rats.

Introduction In recent years, many marine resources have drew attention in the research for bio-active compounds to develop new drugs and health foods. (1) Marine algae are now considered as a rich source of antioxidants (2). It is known that seaweeds contain numerous bioactive substances that have the ability to lower cholesterol, reduce blood pressure, promote healthy digestion; and antioxidant activity (3). Natural antioxidants are interesting compounds due to their properties which help prevent oxidative stress (4), among other potentially beneficial actions. For instance, several biological effects have been attributed to flavonoids, such as anti-tumoral, anti-inflammatory, anti-ischemic and anti-aggregate plaquetary activities. These activities are believed to be in part related to the antioxidant properties of the compounds, namely in scavenging radical oxygen species (ROS). (5, 6) The cold ischemia constitute a situation of oxidative stress in touch with liberation of oxygenated radicals, these situations incited the researchers to find means for the improvement of the conservation of organs allowing to prolong the durations of the cold ischemia of certain organs (in particular the liver) with conservation of the maximum functional value. However, the constant efforts led by the teams of transplantation to develop transplants, the conservation of organs remains a problem to be resolved. (7) Conservation solution of organ appears as being a stemming to remedy the fatal effects of the ischemia-reperfusion. For our part, we think that seaweeds have not delivered their secrets and yet especially that the marine environment of the Tunisian coast still remains little exploited in spite of the big variety of the fauna and the flora of the coast. We envisage in this work, to study a sort of seaweed collected on the Tunisian quotation in the region of "Chott Meriem" (North West of Tunisia). The purpose of our work is to estimate the capacity of extracts stemming from the green seaweed Ulva lactuca to improve the conservation solution of organs against the hepatic effects of ischemia.

Animal model of liver ischemia reperfusion: biochemical and histological evaluation.

INTRODUCTION: During last years, significant progress was made in the comprehension of the hepatic lesions after Ischemia-Reperfusion episode in order to improve the Results in practice clinical. AIM: To avoid or reduce the damage induced by Ischemia-Reperfusion, we developed a model of hepatic Ischemia-Reperfusion with variable periods of reperfusion from 0 to 24 hours.  METHODS: Our study related to rats Wistar males.  Six various groups were studied: the first reference group (without neither ischemia and reperfusion), the second group with ischemia of 90 min and without reperfusion and the 3end , 4end, 5end and 6end groups in addition to ischemia, underwent a reperfusion of 30 min, 2h, 6h and 24h respectively.  The damage of hepatic Ischemia-Reperfusion was evaluated by a biochemical test based on the proportioning of transaminases and an anatomopathologic study by optical microscopy for the determination of the degree of hepatic attack.  RESULTS: The RESULTS obtained seem to show an aggravation of the liver lesions and an increase in the plasmatic rates of AST and ALT in relation with the duration of the reperfusion.  Indeed, the maximum of damage was observed after 2 hours of reperfusion. We observed a reduction in the lesions after 6h and 24h of reperfusion.  CONCLUSION: Our work enabled us to describe a simple model of hepatic Ischemia-Reperfusion with functional, biochemical and anatomopathologic tests.

Effect of Pistacia lentiscus oil on experimental pulmonary fibrosis.

Background - Idiopathic pulmonary fibrosis (IPF) is a chronic disease characterized by histopathological lesions in lung tissue. This is the most common and most severe idiopathic interstitial pneumonias. Current treatments are based on the combination of corticosteroids and immunosuppressants, but their effectiveness is still debated. Purpose of work - Testing the preventive effect of Pistacia Lentiscus oil, known for its antioxidant, anti-mutagenic and anti-proliferative effects, on a model of experimental lung fibrosis. Methods - Two groups of rats received an intratracheal injection of bleomycin (4.5 mg / kg). The first group, control (n = 20 rats), has received no treatment. The second group was treated with Pistacia Lentiscus oil (n = 20 rats) for 30 days before fibrosis induction, by daily gavage oil Pistacia Lentiscus oil (3,33ml / kg). This treatment was continued for 10 days. At the end of the experimental period, all rats were sacrificed and the lung tissue was examined histopathologically and immunostained for TGFß. Results - The chromatographic profile oil Pistacia Lentiscus oil shows the dominance of two fatty acids that are linoleic acid and palmitic acid representing respectively 70.57 and 24.67%. Our results also show a decrease in the distribution of TGFß both at the level of the inflammatory infiltrate and at the level of the pulmonary parenchyma histiocytes of rats treated with Pistacia Lentiscus oil compared with control rats. However, these changes are not accompanied by statistically significant changes of fibrosis score and inflammatory index. Conclusion - Our results are interesting to consider. Further studies using higher doses of Pistacia Lentiscus oil are important to conduct.

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.

Means of evaluation and protection from doxorubicin-induced cardiotoxicity and hepatotoxicity in rats.

OBJECTIVES: This work is aimed on the study of doxorubicin cardiotoxicity and hepatotoxicity in rats and the evaluation of protective effect of trimetazidine administrated concomitantly with doxorubicin for 3 days. MATERIALS AND METHODS: Male Wistar rats used were subjected to different types of treatment (3 days); A: Control, B: Doxorubicin treatment and C: Trimetazidine and doxorubicin treatment. After sacrifice, tissular distribution of doxorubicin, cardiac scintigraphy, histological examination of the myocardium, and evaluation of liver function were assessed. RESULTS: Obtained results show that doxorubicin has a high affinity to tissues especially the heart. It causes hepatotoxicity and cardiotoxicity marked by a significant increase of aspartate aminotransaminase (AST) and alanine aminotransaminase (ALT) levels and drop of the left ventricular ejection fraction (EF LV ) by scintigraphy. Histological examination showed general alteration of myocardium structure. Concomitant administration of trimetazidine attenuates significantly the cardiotoxicity and hepatotoxity induced by doxorubicin. CONCLUSION: We have evaluated the protective effect of trimetazidine on an animal model of doxorubicin-induced cardiotoxicity and hepatotoxicity. The evaluation of these effects were assessed by several means; tissular distribution of doxorubicin, histological examination, assessment of liver function, and EF LV by scintigraphy that characterizes the originality of this study.

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.

Obesity and renal cancer: Role of adipokines in the tumor-immune system conflict.

Epidemiological studies link obesity, as measured by increased body mass index (BMI) to the incidence of renal cell carcinoma (RCC) as well as to the cancer-related mortality of RCC patients. RCC is the third cancer most robustly associated with increased BMI. Understanding the role of the adipose tissue in renal carcinogenesis is therefore of major importance for the development of novel paradigms of RCC prevention and treatment. Here, we discuss the current knowledge on the impact of obesity on the development and progression of RCC as well as the role of adipose tissue-derived hormones (adipokines) in the conflict between growing tumors and the immune system.

Significant association between interleukin-17A polymorphism and colorectal cancer.

Interleukin (IL) 17A is an inflammatory cytokine expressed by Th 17 cells and plays a role in tissue inflammation by inducing release of proinflammatory and neutrophil-mobilizing cytokines. We have investigated the association between colorectal cancer and polymorphisms of IL17A (rs2275913. G197A). The study was performed in 241 subjects (102 with colorectal cancer and 139 healthy controls). Genotypes were determined by fluorescent-based restriction fragment length polymorphism method. The association between the molecular features at the gene in relation to tumor and patient clinical characteristics was analyzed. There was a significant difference between the genotype frequencies of IL17A G197A of control subjects (GG 68.34 % and GA + AA 31.65 %) and patients with colorectal cancer (GG 47.05 % and GA + AA 52.94 %) (p = 0.001 with odds ratio (OR) 2.45 (1.43-4.11)). IL17A G197A polymorphism is particularly associated with colon cancer. Indeed, the IL17A GG genotype could be considered as a protective factor against colon cancer (p = 0.00001) with OR 3.77 (2.04-6.99). We have noted a significant association of IL17A G197A polymorphism not only with tumor localization (p = 0.003) but also with tumor differentiation (p = 0.0005) in CRC patients. We have also showed a significant association of G197A variant with an increased risk of advanced stage (p = 0.005). Our result suggests that the A allele of IL17A gene is involved in susceptibility to colorectal cancer and is associated with clinical features as tumor location, tumor differentiation, and TNM stage. IL17A polymorphism may serve as biomarker of disease location and progression.

Significant association between IL23R and IL17F polymorphisms and clinical features of colorectal cancer.

Th17cells are involved in inflammatory and autoimmune diseases. These cells may be involved in pathological processes mainly producing pro-inflammatory cytokines. Recently, it was shown that the IL23/IL17 pathway plays an important role in the development of inflammatory bowel disease. In general, genes encoding cytokines are genetically polymorphic and polymorphisms in genes IL23R el IL17F were shown associated with susceptibility to Crohn's disease and ulcerative colitis which in their turn are considered as risk factors for developing colorectal cancer (CRC). Our approach is to study IL17F and IL23R polymorphisms as risk factor associated with CRC in the Tunisian population in patients and healthy controls. Interesting, we noted a significant association between IL17F and IL23R polymorphisms and tumor location (p=0.0001 and p=0.049, respectively), tumor histology (p=0.007 and p=0.049, respectively) and tumor architecture (p=0.0000000001 and p=0.07, respectively) in CRC patients. We also showed a significant association of IL17F variant with an increased risk of TNM stage III/IV (p=0.007), showing an increased risk of advanced stage. Finally, we observed a positive link between IL17F polymorphism and CRC patients with lymph nodes (p=0.0000000001) and metastasis (p=0.00000009). However, we found no evidence to support a significant association between IL17F and IL23R polymorphisms and colorectal cancer susceptibility. Our findings suggest that IL17F and IL23R polymorphisms were significantly associated with clinical features variables. The IL17F cytokine appear to be involved in the control of tumor growth and invasion of gastrointestinal tumors. IL17 and IL23 polymorphisms or those of their receptors as important determinants of susceptibility to colorectal cancer are still subject to questioning.

TP53 mutations in colorectal cancer from Tunisia: relationships with site of tumor origin, microsatellite instability and KRAS mutations.

Loss of TP53 function through gene mutation is a critical event in the development and progression of colorectal cancer (CRC). Here we examined 51 primary CRC tumors from Tunisia for mutations in TP53 exons 4-9 using PCR-direct sequencing. TP53 status and mutation site/type were than correlated with nuclear protein accumulation, familial and clinicopathologic variables and data on KRAS mutations and microsatellite instability (MSI-H). The TP53 mutation analysis was possible in the tumor of 47 patients and a deleterious somatic mutation has been detected in 59.6% of the patients (28/47) including 20 (71.4%) missense mutations, 7 nonsense mutations (25%) and 1 (3.6%) frameshift mutation. 89.3% (25/28) of the detected mutations were in exons 5-8, whereas 10.7% (3/28) were in exon 4. Among the 27 non frameshift mutations, 89% (24/27) were transitions and 11% (3/27) were transversions. 64.3% (18/27) of the altered amino acids corresponded to arginine. 74% (20/27) were G>C to A>T transitions, and more than half (14/27) occur at hotspots codons with CpG sites. TP53 mutations correlated closely with TP53 accumulation (p = 0.0090) and inversely with MSI phenotype (p = 0.0658). A KRAS somatic mutation was identified in 25% (7/28) of the TP53 mutated tumors. All these mutations were G>A transitions in codon 12 and all the tumors with combined alterations but one were distally located and MSS. In conclusion, frequency and types of TP53 mutations and correlations with TP53 protein accumulation, and MSI were as reported for non-Tunisian patients. However, no significant associations have been detected between TP53 mutations and clinicopathological data in Tunisian patients as previously reported.

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.

[Immunohistochemical analysis of mismatch repair proteins in colorectal adenomas]. / Analyse immunohistochimique des protéins de réparation de I'ADN dans les adénomes colorectaux.

BACKGROUND: The deficiency of mismatch repair system is one of the main pathways in colorectal cancer. This system consists mainly of four proteins: MLH1, MSH2, MSH6 and PMS2. Colorectal cancer develops in the majority of cases from precancerous lesions called adenomas. Only few studies have reported on the deficiencies of these proteins in adenomas. AIM: In this study we used immunohistochemistry staining in colorectal adenomas to assay functional status of MLH1, MSH2, MSH6, and PMS2 proteins. METHODS: 102 adenomas from 93 patients were collected in our institution during six years (2007-2012). The immunohistochemical technique was performed with 4 antibodies: MLH1, MSH2, MSH6 and PMS2. The loss of expression was retained if adenomatous cells were not stained with positive internal control. Staining was considered as abnormal if nucleus of adenomatous cells showed low nuclear staining and / or heterogeneous one, while positive internal control had normal staining. RESULTS: Loss of expression of MSH2 and MSH6 in adenomatous cells was found in only 1 case which was a tubular adenoma 3mm high-grade dysplasia. Abnormal staining of the adenomatous cells was noted in 23 cases (22.5%) for MSH2 and in 8 cases (7.8%) for MSH6. No cases showed loss of expression of MLH1 and PMS2. Abnormal expression of MSH2 and MSH6 was not correlated with sex of patients, the location of the adenoma, its grade of dysplasia and its histological type. CONCLUSIONS: Loss of Mismatch repair proteins expression is a rare event in adenomas. However, the abnormal expression levels are higher in our study compared to those reported in the literature. This could reflect a higher rate of microsatellite instability in our patients. Multicenter and larger studies with molecular biology techniques are needed.

KRAS mutations in colorectal cancer from Tunisia: relationships with clinicopathologic variables and data on TP53 mutations and microsatellite instability.

Mutations in KRAS gene are among the critical transforming alterations occurring during CRC tumorigenesis. Here we screened 51 primary CRC tumors from Tunisia for mutations in KRAS (codons 12 and 13) using PCR-direct sequencing. Our aim was to analyze tumor mutation frequencies and spectra in Tunisian patients with CRC. KRAS status and mutation site/type were than correlated with familial and clinicopathologic variables and data on TP53 mutations and nuclear protein accumulation and microsatellite instability (MSI). A KRAS somatic mutation has been detected in the CRC tumor of 31.5 % (16/51) of the patients. 81.2 % had a single mutation at codon 12 and 23 % had a single mutation at codon 13. The most common single mutation (50 %) was a G>A transition in codon 12 (c.35G>A; p.Gly12Asp). 81.25 % of the KRAS mutations were transitions and 23 % were transversions. All the mutations in codon 13 were a c.38G>A transition, whereas both G>A transitions and G>T and G>C transversions were found in codon 12. The mutation spectrum was different between MSS and MSI-H tumors and more varied mutations have been detected in MSS tumors. Some amino acid changes were detected only in MSS tumors, i.e. p.Gly12Ser, p.Gly12Cys and p.Gly12Ala. Whereas, the KRAS mutation p.Gly13Asp have been detected only in MSI-H. 43.75 % of the patients harboured combined mutations in KRAS and TP53 genes and the tumor of 71.42 % of them showed TP53 overexpression. In conclusion, the frequency and types of KRAS mutations were as reported for non-Tunisian patients. However, no significant associations have been detected between KRAS mutations and clinicopathologic variables and MSI in Tunisian patients as previously reported.