Molecular and immunohistochemical analysis of BRAF gene in primary cutaneous melanoma: Discovery of novel mutations.

BACKGROUND: Determination of BRAF status is mandatory for targeted therapy but it is not currently available in most developing countries. AIM: We aimed to analyze BRAF mutations in a series of cutaneous melanoma of Tunisian patients and to compare BRAF V600E mutation detection by immunohistochemistry to DNA sequencing. PATIENTS AND METHODS: Archival formalin fixed paraffin embedded tissues from 28 patients with primary cutaneous melanoma were evaluated for the BRAF mutations by Sanger sequencing and immunohistochemistry. RESULTS: BRAF mutations were detected in 19/28 (68%) of analyzed tumors. The sensitivity and specificity of immunohistochemistry compared to DNA sequencing for identification of the BRAF V600E mutation were 100%. We found five novel mutations, one of them had deleterious effect. CONCLUSION: The present study shows an intermediate frequency of mutations of the BRAF gene in cutaneous melanoma of Tunisian patients, and supports the use of immunohistochemistry as a screening test for the assessment of the BRAF V600E status in the management of melanoma in clinical practice.

ALK protein expression in pulmonary adenocarcinoma of Tunisian patients.

BACKGROUND: It is now necessary to determine ALK status in order to use targeted therapy. AIM: herein, we assess immunohistochemical profile of ALK protein in a series of Tunisian patients with pulmonary adenocarcinoma. MATERIALS AND METHODS: ALK protein expression was studied applying the D5F3 antibody with a fully automated Ventana CDx technique on a series of 19 patients. RESULTS: Positive ALK expression was found in one case (5.2%) corresponding to a papillary adenocarcinoma which showed a strong granular and homogenous cytoplasmic staining. The patient was a 30-years-old woman. CONCLUSION: The frequency of positive ALK expression based on immunohistochemistry in our series was similar to that reported in the world literature.

Prognostic value of immunohistochemical expression profile of epidermal growth factor receptor in urothelial bladder cancer.

We studied epidermal growth factor receptor (EGFR) expression profile in urothelial bladder carcinoma (UBC) which is a complex and heterogeneous disease with a large spectrum of histological aspects and deadly potential. Using immunohistochemistry (IHC), all GI tumors and pTa cases showed a low expression profile of EGFR. However, we note that when the stage of disease is advanced, tumors over-express EGFR. Indeed, 5% and 25% of GII and GIII tumors over-expressed EGFR, respectively. Further, 0% of pTa, 9,5% of pT1, 15% of pT2, 50% of pT3, and 90% of pT4 tumors were shown to be high EGFR expression (HEE). Moreover, we found a statistically significant correlation between the EGFR over-expression and grade and stage (P < 0.05). Thus, EGFR over-expression could be a potential prognostic marker to predict poor outcome in Tunisian patients with UBC.

Relationship between p73 polymorphism and the immunohistochemical profile of the full-length (TAp73) and NH2-truncated (ΔNp73) isoforms in Tunisian patients.

BACKGROUND: We examined the association of one linked GC/AT polymorphism at p73 with the risk of colorectal cancer. AIM: In this study, we investigated whether this polymorphism was related to the risk of colorectal cancer, and whether there were relationships between the polymorphism and loss of heterozygosity, protein expression, or clinicopathologic variables. MATERIALS AND METHODS: The p73 genotypes were determined by polymerase chain reaction-restriction fragment length polymorphism in 150 Tunisian patients with colorectal cancer and in 204 healthy control subjects. Immunohistochemistry was performed on normal mucosa, primary tumor, and metastasis. RESULTS: The frequencies of the genotypes were 52% for wild-type (GC/GC), 31% for heterozygotes (GC/AT), and 17% for variants(AT/AT) in patients, and 54%, 35%, and 11% in controls, respectively. There were no significant differences of the frequencies of the 3 genotypes between the patients and controls (P=0.11). We did not find any relationship of the genotypes with clinicopathologic features of patients. We found that patients with the GC/GC genotype had a significantly more favorable clinical outcome than the patients with the AT variants (AT/AT or GC/AT genotype). There were no significant difference between tumoral immunostaining and p73 polymorphism (P=0.16) but we found that the samples carrying the AT allele showed a tendency to be more stained in tumor. No loss of heterozygosity was observed at p73 locus. Our results suggest that the AT/AT genotype is significantly associated with poor prognosis in colorectal cancer. All these findings suggest that p73 polymorphism analysis may provide useful prognostic information for colorectal cancer patients.

Association of a p73 exon 2 GC/AT polymorphism with colorectal cancer risk and survival in Tunisian patients.

We examined the association of one linked GC/AT polymorphism at p73 with the risk of colorectal cancer. In the present study, we investigated whether this polymorphism was related to the risk of colorectal cancer, and whether there were relationships between the polymorphism and LOH, protein expression or clinicopathological variables. The p73 genotypes were determined by PCR-restriction fragment length polymorphism in 150 Tunisians patients with colorectal cancer and in 204 healthy control subjects. Immunohistochemistry was performed on normal mucosa, primary tumour and metastasis. The frequencies of the genotypes were 52% for wild-type (GC/GC), 31% for heterozygotes (GC/AT) and 17% for variants (AT/AT) in patients, and 54%, 35% and 11% in controls, respectively. There were no significant differences of the frequencies of the three genotypes between the patients and controls (p = 0.11). We did not find any relationship of the genotypes with clinicopathological features of patients. We found that patients with the AT/AT genotype had a significantly worse clinical outcome than those with the GC/AT and GC/GC genotype. There were no significant differences between tumoural immunostaining of the total p73 and p73 polymorphism (p = 0.16). However, we found a significant difference between the expression profile of DeltaNp73 isoform and frequencies of the three genotypes (p = 0.0001). No LOH was observed at p73 locus. Our results suggest that the AT/AT genotype is significantly associated with poor prognosis in colorectal cancer. All these findings suggest that p73 polymorphism analysis may provide useful prognostic information for colorectal cancer patients.