Increased ß­catenin and c-myc expression predict aggressive growth of non-functioning pituitary adenomas: An assessment using a tissue microarray-based approach.

Non-functional pituitary adenomas (NFPAs) account for 80% of pituitary adenomas with the majority of these exhibiting recurrences post-surgery. Overexpression of ß-catenin and c­myc is common in numerous invasive tumors. The present study sought to investigate the correlation of ß­catenin and c­myc expression levels with aggressive growth and recurrence of NFPAs, using immunohistochemical examination of tissue microarrays. Tissue microarrays comprised 212 NFPAs specimens and 10 healthy specimens as controls. NFPAs were categorized as non­aggressive or aggressive. Immunohistochemical examination was performed to determine the expression of ß­catenin and c­myc. Correlation of the expression levels of ß­catenin and c­myc with clinicopathological parameters, including aggressiveness and recurrence, were assessed by univariate, multivariate and logistic regression analysis. Increased expression of ß­catenin and c­myc was detected in the majority of aggressive NFPAs specimens (71.1 and 88.7%, respectively). There was a significant positive correlation between ß­catenin and c­myc expression and aggressiveness [P=0.001, Odds Ratio (OR)=4.011; P<0.001, OR=30.833]. Only ß­catenin expression demonstrated a significant correlation with recurrence in NFPAs (P=0.021, OR=2.571). ß­catenin and c­myc were demonstrated to be potential biomarkers for aggressive NFPAs and in the future, ß-catenin may serve as a marker for aggressive behavior and recurrence in NFPAs.

Assessment and biological significance of JC polyomavirus in colorectal cancer in Tunisia.

PURPOSE: Several reports have indicated the presence of JC polyomavirus (JCV) in many human tumors, including colorectal cancers (CRCs). The presence of JCV infection in CRC patients has not been investigated in African countries. METHODS: We examined the prevalence and the biological significance of JCV in Tunisian CRC patients. The presence of JCV was assessed by polymerase chain reaction (PCR) in a series of 105 CRCs and 89 paired non-tumor colonic mucosa samples from Tunisian patients. Results were correlated with the clinicopathological features and immunohistochemical expression of ß-catenin, p53, and the proliferation marker Ki-67. RESULTS: JCV DNA was detected in 58.1% (61/105) of CRC and in only 14.6% (13/89) of paired non tumor colonic mucosa samples (p=0.03). The presence of JCV was significantly correlated with tumor differentiation (p=0.03). Moreover, JCV presence was significantly correlated with nuclear accumulation of ß-catenin (p=0.008) and p53 accumulation (p=0.0001). Multivariate logistic regression analysis showed that tumor differentiation, ß-catenin and p53 accumulation were independent parameters significantly associated with the presence of JCV in CRC (p=0.04; p=0.05; p=0.001, respectively). CONCLUSION: We support a role of JCV in colorectal carcinogenesis in Tunisian patients, especially of well differentiated morphology.

Immunohistochemical assessment of E-cadherin and beta-catenin in trichofolliculomas and trichoepitheliomas.

BACKGROUND: Trichofolliculomas and trichoepitheliomas are benign skin neoplasms originating from hair follicle cells. They result from defects in the signaling pathways that regulate hair follicle morphogenesis and regeneration. Thus they seem to be an excellent model of these processes. It is known that the E-cadherin/beta-catenin system of adhesion molecules plays a crucial role in the maintenance of tissue architecture. AIM: The aim of the present study was to investigate their involvement in benign hair follicle tumor development. METHODS: Semiquantitative intensity of expression were examined in formalin-fixed and paraffin-embedded tissue sections of 53 trichoepitheliomas, 15 trichofolliculomas and 19 normal skin samples by indirect immunohistochemistry. RESULTS: The intensity of E-cadherin/beta-catenin expression in tumor cells did not differ from controls. However, normal hair follicles cells exhibited membranous E-cadherin/beta-catenin expression, whereas both types of tumors, particularly trichoepitheliomas, showed E-cadherin/beta-catenin expression with a predominantly cytoplasmic localization. CONCLUSIONS: We suggest that this dystopic distribution of the E-cadherin/beta-catenin complex in hair follicle tumor cells may be a marker of cell-cell adhesion disruption which may contribute to the tumor formation.