148 research outputs found
Detection of BRAF mutation in thyroid papillary carcinomas by mutant allele-specific PCR amplification (MASA).
Objective: The somatic point mutation in the BRAF gene, which results in a valine-to-glutamate sub-
stitution at residue 600 (BRAF
V600E
), is an ideal hallmark of papillary thyroid carcinoma (PTC). How-
ever, its prevalence is varyingly reported in different studies, and its expression in the follicular variant
PTC is controversial, reducing its potential usefulness as diagnostic marker.
Design and methods: We developed an assay based on mutant allele-specific PCR amplification (MASA)
to detect BRAF mutation. We compared the sensitivity of MASA, single-strand conformation poly-
morphism (SSCP) and direct DNA sequencing of PCR products. Then, we used MASA 78 to analyze
78 archival thyroid tissues, including normal samples, follicular adenomas, follicular carcinomas and
PTC.
Results: The MASA assay proved to be a more sensitive method than SSCP and DNA sequencing of
PCR products. BRAF mutation was found by MASA in 19/43 (44.2%) of PTC, including 14/31
(45.2%) classic forms and 5/12 (41.7%) follicular variants. No mutations of BRAF were detected
in the normal thyroid tissues, nor in follicular adenomas or follicular carcinomas. No correlation
was found between BRAF mutation and clinicopathologic features nor with recurrence during a post-
operative follow-up period of 4–11 years. BRAF
V600E
significantly correlated with absence of node
metastasis.
Conclusions: BRAF
V600E
is present in PTC, both in the classic form and in follicular variant with simi-
lar prevalence. No correlation was found between BRAF mutation and aggressive clinical behavior.
MASA-PCR proved to be a specific, sensitive and reliable method to detect BRAF T1799A in DNA
extracted from different sources, including cytologic samples obtained either fresh or from archival
glass slides. We propose this method as a useful tool to improve accuracy of preoperative diagnosis
identifying PTC from biopsies with indeterminate cytologic findings
Skp2 expression is associated with high risk and elevated Ki67 expression in gastrointestinal stromal tumours
BACKGROUND: Gastrointestinal stromal tumors (GIST) exhibit an unpredictable clinical course and can rapidly progress to lethality. Predictions about the biological behavior of GIST are based on a number of canonical clinical and pathologic parameters whose validity in distinguishing between a benign and a malignant tumour is still imperfect. The aim of our study was to investigate the role of morphologic parameters and expression of cells cycle regulators as prognosticators in GIST. METHODS: We performed an immunohistochemical analysis for Ki67, p27Kip1, Jab1, and Skp2, on a Tissue Microarray (TMA) containing 94 GIST. Expression of the above proteins was correlated to classically used prognosticators, as well as to risk groups. Clinical significance of histologic and immunohistochemical features were evaluated in 59 patients for whom follow-up information was available. RESULTS: Overexpression of Ki67 and Skp2, and p27Kip1 loss directly correlated with the high risk group (p = 0.03 for Ki67 and Skp2, p = 0.05 for p27Kip1). Jab1 expression did not exhibit correlation with risk. In 59 cases provided with clinical follow-up, high cellularity, presence of necrosis, and Ki67 overexpression were predictive of a reduced overall survival in a univariate model. The same parameters, as well as mitotic rate, tumour size, and p27Kip1 loss were indicative of a shortened relapse free survival interval. High cellularity, and high mitotic rate retained their prognostic significance by multivariate analysis. CONCLUSION: Our data suggest that a number of histologic parameters in combination with immunohistochemical expression of cell cycle regulators can facilitate risk categorization and predict biologic behavior in GIST. Importantly this study demonstrates, for the first time, that Skp2 expression correlates with Ki67 expression and high risk in GIST
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