Stromal cell derived factor-1 and CXCR4 expression in colorectal cancer promote liver metastasis.

BACKGROUND: Recent studies suggest that SDF-1 and CXCR4 are expressed in certain cancer cells, and malignant cells use this chemokine/receptor system to promote tumor progression and metastasis. However, the pathophysiological significance of their expression in colorectal cancer (CRC) tissue has not been fully elucidated. OBJECTIVE: The purpose of this study was to assess SDF-1/CXCR4 expression and to explore its contribution to colorectal cancer. METHODS: We examined SDF-1 and CXCR4 mRNA expression in 124 primary colorectal tumour and 35 liver metastases tissues and matched adjacent noncancerous tissues by reverse transcriptase PCR (RT-PCR). Furthermore, their expression was analyzed by immunohistochemistry. The relationship between SDF-1/CXCR4 expression and clinicopathological features were analyzed by appropriate statistics. X2 test and Kaplan-Meier analysis were used to investigate the correlation between the ligand-receptor expression and prognosis of colorectal cancer patients. RESULTS: The relative mRNA expression of SDF-1 and CXCR4 was significantly elevated in colorectal cancer tissues as compared with adjacent noncancerous tissues (P < 0.001). The high expression of proteins expression in colorectal cancer tissues was significantly correlated with tumor grade (P = 0.0001), clinical stage (P < 0.05), and lymphatic invasion (P < 0.05). Furthermore, patients with CXCR4 nuclear-type expression showed more frequent lymph node metastasis (p = 0.021), advanced clinical stage (p = 0.001) and lymphatic invasion (p = 0.03) than those with cytoplasm staining-type. Kaplan-Meier survival analysis revealed that high expression of the couple SDF-1/CXCR4 correlated with poor prognosis of colorectal cancer patients (P < 0.001). CONCLUSION: SDF-1 and CXCR4 may play an important role in the progression of colorectal cancer. The present data suggest that there is a significant association between SDF-1/CXCR4 to enhance the liver metastases causing poor prognosis. Those proteins may potentially be used as an independent biomarker for the prognostic evaluation of colon cancer in the Tunisian cohort.

Relationship between SDF-1G801A polymorphism and its expression in Tunisian patients with colorectal cancer.

The aim was to evaluate the relationship between SDF-1G801A polymorphism and its immunohistochemical expression in colorectal cancer tissues in the Tunisian cohort. The molecular and immunohistochemical analysis showed that SDF-1G801A polymorphic variant was higher in CRC patients with TNM stage II and III, the SDF-1 expression was significantly increased from normal mucosa to primary tumor (p < 0.05). CRC patients have higher frequency of A allele (52.01%) than controls (26.8%) (P = 0.0001). Thus, SDF-1 polymorphism is a risk factor of colorectal cancer susceptibility in our population, the polymorph genotype of SDF-1 maybe associated with clinical manifestations in CRC patients in Tunisia.

Biological significance of promoter hypermethylation of p14/ARF gene: relationships to p53 mutational status in Tunisian population with colorectal carcinoma.

One of the most important pathways which are frequently affected in colorectal cancer is p53/ (MDM2)/p14ARF pathway. We aim to determine the methylation pattern of p14/ARF in relation to mutation of p53. This correlation was studied to investigate whether their alterations could be considered as a predictor factor of prognosis in colorectal cancer and whether it can be useful in early-stage diagnosis. Statistical analyses show that p14/ARF hypermethylation was correlated with rectum location (p = 0.004), primary TNM stage (p = 0.016), and advanced Astler-Coller stage (p = 0.024). The RT-PCR that revel 31 % of patients did not express p14/ARF mRNA or at very low level. A high concordance between CpG hypermethylation and the low levels (p < 0.005) was shown. In addition, our analyses demonstrate that patients with mutation in the p53 gene have a lack of the protein expression (p < 0.005). This category with negative expression of p53 had a shorter survival rate (p < 0.005). On the one hand, MSP pattern of p14/ARF were correlated with a lack of p53 expression (p = 0.007). We found that p53/p14ARF pathway was frequently deregulated among our patients. In our study, we demonstrate that hypermethylation of p14/ARF occurs early during CRC tumorogenesis. However, we did not find correlation between p14/ARF and survival. These results suggest that p14/ARF methylation pattern may constitute a predictor factor of CRC in early stage but it could not be considered as a prognostic factor. On the other hand and because of the reversibility of the methylation mechanism, it may be appropriate to target the demethylation of p14/ARF to develop new drogues for CRC.

Relationship between MDM2 and p53 alterations in colorectal cancer and their involvement and prognostic value in the Tunisian population.

BACKGROUND: The prevalence of p53 mutations in colorectal cancer could reach 90%. The most important regulator of this protein that was identified originally was the Murine Double Minute2 (MDM2) oncoprotein, by which the levels of p53 were fixed through an autoregulatory feedback loop. In cancer cases, the overexpression of MDM2 deregulates this feedback, and the signaling pathway between MDM2 and p53 is blocked. MATERIALS AND METHODS: We genotyped 167 patients and 167 healthy blood donors to determinate the mutational status of MDM2 and p53. Immunohistochemical analysis was performed on tumor and normal mucosa. RESULTS: The MDM2 polymorphism study showed a higher distribution of MDM2 SNP309 in tumors compared with healthy controls. At the same time, the majority of samples with SNP309 indicated a positive expression of MDM2 protein in the tumor. In this case, we found a first significant association between p53 expression and the single-strand conformational polymorphism analysis and a second association between the MDM2 polymorphism and p53 mutation. Moreover, the nuclear overexpression of MDM2 and SNP309 was significantly related to a higher mortality rate. CONCLUSIONS: In this work we wanted to highlight the role, which is becoming increasingly important, of MDM2. In fact, we conclude that the effects of MDM2 SNP309 may be considered a valuable prognostic marker to predict poor outcome for Tunisian patients with colorectal cancer.

The prognostic value of the immunohistochemical expression and mutational pattern of the key mediator of Wnt signaling: beta-catenin in Tunisian patients with colorectal carcinoma.

Beta-catenin plays a critical role with E-cadherin in cell-cell adhesion and is also a key molecule of the highly conserved Wnt signaling pathway that regulates cell proliferation and differentiation. Abrogation of this pathway is implicated in the carcinogenesis of several malignancies, especially colorectal cancer. The objective of this study was to determine the prognostic value of ß-catenin/E-cadherin complex in Tunisian patients with colorectal cancer. Matched primary tumors from 150 patients with sporadic colorectal adenocarcinomas were stained for ß-catenin and E-cadherin by using immunohistochemistry. Deletion of exon 3 of CTNNB1 gene was performed by polymerase chain reaction. Our results showed that ß-catenin and E-cadherin expressions were related inversely to tumor differentiation. Furthermore, the nuclear expression of ß-catenin was considerably increased in advanced colorectal adenocarcinomas and was highly associated with shorter survival of patients. Deletion of exon 3 of CTNNB1 was identified in 2 cases by using polymerase chain reaction and was significantly related to tumor invasion and aberrant expression of E-cadherin. The major finding of this study is that activation of ß-catenin gene by deletions involving exon 3 may be considered as an advanced event in colorectal tumorigenesis in Tunisian patients, in contrast to some worldwide studies. Moreover, disruption of ß-catenin/E-cadherin complex may be considered as a dependent predictor of disease outcome.

Stromal cell-derived factor 1 polymorphism in patients infected with HIV and implications for AIDS progression in Tunisia.

BACKGROUND: An interesting finding in the epidemiology of human immunodeficiency virus (HIV) infection is that certain mutations in genes coding for chemokines, and their receptors and ligands, may confer resistance or susceptibility to HIV-1 infection and acquired immunodeficiency syndrome (AIDS) progression. The mutation most frequently studied is stromal cell-derived factor (SDF)1-3'A, a single nucleotide polymorphism in the 3' untranslated region at the 801 position of the SDF1 gene, which seems to be associated with susceptibility or resistance to diseases, including AIDS. We examined the frequency of the above polymorphisms in the Tunisian population, and evaluated their contribution to a protective genetic background against HIV infection and progression. METHODS AND MATERIALS: One hundred forty blood samples from HIV-infected patients from the Cellular Immunology Research Laboratory at the National Blood Transfusion Center were compared with those of 164 random blood donors from the same center. Genotyping was initially performed by polymerase chain reaction (PCR) analysis. SDF1 PCR product genomic regions were further subjected to restriction fragment length polymorphism analysis for genotype determination. Screening for the SDF1 polymorphism in the HIV-infected population yielded 56 heterozygous (40%), 52 mutation homozygous (37.1%), and 32 wild-type homozygous (22.8%) subjects. In contrast, in our healthy population, we found 70/164 heterozygous (42.6%), nine mutation homozygous (5.4%), and 85 wild-type homozygous (51.8%) subjects. The allele frequencies in the HIV-infected and healthy populations were f(SD1 3'A) = 57.1%, f(SDF1) = 42.8%, f(SDF1 3'A) = 26.8%, and f(SDF1) = 73.1%, respectively. The allelic and genotypic frequencies of the SDF1 3'A in our population show significantly higher distribution profiles compared with those observed in other Caucasian, European, and African American populations. Our results were examined by χ(2) test and appear to confirm an association between polymorphism and AIDS progression. A higher odds ratio (>1) was found for the SDF1-3'A allele than for the wild-type allele (<1). CONCLUSION: This result seems to confirm that the SDF1-3'A allele is associated with acceleration and progression from HIV infection to AIDS in the Tunisian population.