These findings demonstrate that ras mutations are a marker for aggressive cancer behavior and indicate a possible role of ras genotyping to identify thyroid carcinoma subsets associated with poor prognosis.

The phosphatidylinositol 3V-kinase (PI3K) pathway is frequently activated in thyroid carcinomas through the constitutive activation of stimulatory molecules (e.g., Ras) and/or the loss of expression and/or function of the inhibitory PTEN protein that results in Akt activation. Recently, it has been reported that somatic mutations within the PI3K catalytic subunit, PIK3CA, are common (25-40%) among colorectal, gastric, breast, ovarian cancers, and high-grade brain tumors. Moreover, PIK3CA mutations have a tendency to cluster within the helical (exon 9) and the kinase (exon 20) domains. In this study, 13 thyroid cancer cell lines, 80 well-differentiated thyroid carcinomas of follicular (WDFC) and papillary (WDPC) type, and 70 anaplastic thyroid carcinomas (ATC) were investigated, by PCR-direct sequencing, for activating PIK3CA mutations at exons 9 and 20. Nonsynonymous somatic mutations were found in 16 ATC (23%), two WDFC (8%), and one WDPC (2%). In 18 of the 20 ATC cases showing coexisting differentiated carcinoma, mutations, when present, were restricted to the ATC component and located primarily within the kinase domain. Three cell lines of papillary and follicular lineage (K1, K2, and K5) were also found mutated. In addition, activation of Akt was observed in most of the ATC harboring PIK3CA mutations. These findings indicate that mutant PIK3CA is likely to function as an oncogene among ATC and less frequently well-differentiated thyroid carcinomas. The data also argue for a role of PIK3CA targeting in the treatment of ATC patients. (Cancer Res 2005; 65(22): 10199-207)

The activation of the APC/b-catenin signalling pathway due to b-catenin mutations has been implicated in the development of a subset of endometrial carcinomas (ECs). However, up to 25% of ECs have b-catenin nuclear accumulation without evidence of b-catenin mutations, suggesting alterations of other molecules that can modulate the Wnt pathway, such as APC, g-catenin, AXIN1 and AXIN2. We investigated the expression pattern of b-and g-catenin in a group of 128 endometrial carcinomas, including 95 endometrioid endometrial carcinomas (EECs) and 33 non-endometrioid endometrial carcinomas (NEECs). In addition, we evaluated the presence of loss of heterozygosity and promoter hypermethylation of the APC gene and mutations in the APC, b-and g-catenin, AXIN1, AXIN2, and RAS genes, and phospho-Akt expression. No APC mutations were detected but LOH at the APC locus was found in 24.3% of informative cases. APC promoter 1A hypermethylation was observed in 46.6% of ECs, and was associated with the endometrioid phenotype (P=0.034) and microsatellite instability (P=0.008). Neither LOH nor promoter hypermethylation of APC was associated with nuclear catenin expression. Nuclear b-catenin expression was found in 31.2% of EECs and 3% of NEECs (P=0.002), and was significantly associated with b-catenin gene exon 3 mutations (P50.0001). b-catenin gene exon 3 mutations were associated with the endometrioid phenotype, and were detected in 14 (14.9%) EECs, but in none of the NEECs (P=0.02). g-catenin nuclear expression was found in 10 ECs; it was not associated with the histological type but was associated with more advanced stages (P=0.042). No mutations in g-catenin, AXIN1 and 2 genes were detected in this series. Neither RAS mutations nor phospho-Akt expression, which were found in 16 and 27.6% of the cases, respectively, were associated with bcatenin nuclear expression. Our results demonstrated a high prevalence of alterations in molecules of the APC/ b-catenin pathway, but only mutations in b-catenin gene are associated with aberrant nuclear localization of bcatenin.

BRAF(V600E)'alone' does not represent a marker for poor outcome, however, when associated with alterations in other genes identifies a subset of PTCs with increased risk of recurrence and decreased survival.

The cyclin-dependent kinase inhibitor p27KIP1 has been proposed as a valuable prognostic indicator for a variety of human neoplasms. Immunohistochemical reactivity for p27KIP1 and the proliferation marker Ki67/Mib1 were investigated in 90 thyroid carcinomas of follicular cell origin. The neoplasms were divided into three prognostic groups on the basis of their morphologic features: group 1, well-differentiated papillary or follicular carcinomas with favorable pathologic features (43 papillary carcinomas and 4 minimally invasive follicular carcinomas); group 2, papillary or follicular carcinomas with unfavorable pathologic features (21 poorly differentiated carcinomas and 2 papillary carcinomas, tall cell variant); and group 3, undifferentiated, or anaplastic, carcinomas. p27KIP1 expression (p = 0.007) and Ki67/Mib1 labeling index (p = 0.02) showed a strong correlation with the subdivision of the thyroid carcinomas in the three prognostic groups with a significant linear trend for tumors with low p27KIP1 (p = 0.002) and high Ki67/Mib1 labeling index (p = 0.005) to segregate into the unfavorable categories (groups 2 and 3). Low p27KIP1 expression, but not cellular proliferation, was related to adverse prognostic factors, such as large tumor size (p = 0.03) and extrathyroidal extension (p = 0.01), but the correlation was not independent of the subdivision in the three groups. Low p27KIP1 expression (p = 0.03) and high proliferative rate (p = 0.02) were associated with poor survival, reflecting the close association between patient morbidity and mortality rates and tumor differentiation. No significant association could be seen between p27KIP1 or cellular proliferation and clinicopathologic parameters (e.g., age, sex, tumor size, extrathyroidal extension, vascular invasion, lymph node metastases, distant metastases, tumor stage, and survival rate) within any of the groups, or the histologic diagnosis of papillary versus follicular carcinoma irrespective of their degree of differentiation. Modulation of p27KIP1 and cellular proliferation patterns in thyroid carcinoma correlate with tumor differentiation and support the morphologic classification of thyroid carcinoma into prognostically relevant categories.