Tumour recurrence and enlargement in patients with craniopharyngioma with and without GH replacement therapy during more than 10 years of follow-up.

OBJECTIVE: Most patients who have been treated for craniopharyngioma (CP) are GH deficient (GHD). GH replacement therapy (GHRT) may stimulate tumour regrowth; and one of the concerns with long-term GHRT is the risk of tumour progression. Therefore, the objective was to study tumour progression in CP patients on long-term GHRT. DESIGN: Case-control study. PATIENTS AND METHODS: The criteria for inclusion of cases were: i) GHD caused by CP; ii) GHRT >3 years; and iii) regular imaging. This resulted in 56 patients (mean age at diagnosis 25±16 years) with a mean duration of GHRT of 13.6±5.0 years. As controls, 70 CP patients who had not received GHRT were sampled with regard to follow-up, gender, age at diagnosis and initial radiation therapy (RT). RESULTS: The 10-year tumour progression-free survival rate (PFSR) for the entire population was 72%. There was an association (hazard ratio, P value) between PFSR and initial RT (0.13, 0.001) and residual tumour (3.2, 0.001). The 10-year PFSR was 88% for the GHRT group and 57% for the control group. Substitution with GHRT resulted in the following associations to PFSR: GHRT (0.57, 0.17), initial RT (0.16, <0.001), residual tumour (2.6, <0.01) and gender (0.57, 0.10). Adjusted for these factors, the 10-year PFSR was 85% for the GHRT group and 65% for the control group. CONCLUSIONS: In patients with CP, the most important prognostic factors for the PFSR were initial RT and residual tumour after initial treatment. Long-term GHRT did not affect the PFSR in patients with CP.

Lithium stimulates proliferation in cultured thyrocytes by activating Wnt/beta-catenin signalling.

BACKGROUND: Lithium, clinically used in the treatment of bipolar disorders, is well known to induce thyroid growth. However, the mechanism involved is only incompletely characterized. Although it is conventionally believed that thyroid proliferation depends on the thyroid-stimulating hormone (TSH)/cAMP/cAMP response element binding protein (CREB) pathway, recent data indicate that Wnt/beta-catenin signalling may be of critical importance. In other cell types lithium activates canonical Wnt signalling by GSK-3beta inhibition, which in turn stabilizes cytosolic free beta-catenin. Here we investigated the potential modulation of Wnt/beta-catenin signalling under lithium treatment in primary and neoplastic human thyrocytes. METHODS: Primary (S18) and neoplastic (NPA, FTC133) thyrocytes treated with and without LiCl were analysed using Western blotting, immunoprecipitation, reporter-gene assay, MTT proliferation assay and transfection studies. RESULTS: LiCl dose-dependently inhibited GSK-3beta, stabilized free beta-catenin and inhibited beta-catenin degradation. Furthermore, LiCl altered the assembly of adherens junction by upregulating the E-cad-herin repressor, Snail, and downregulated E-cadherin expression. At a dose of 5 mM, LiCl significantly increased the proliferative potency of thyrocytes, which appeared to be mediated by beta-catenin, since nuclear beta-catenin stimulated T-cell factor/lymphoid enhancer factor (TCF/LEF)-mediated transcription and upregulated downstream targets like cyclin D1. To characterize the specificity of Wnt/beta-catenin-driven thyrocyte proliferation, we transfected primary thyrocytes and FTC133 cells with dominant negative TCF4 to block Wnt-dependent pathways or with dominant negative CREB to inhibit the TSH/cAMP cascade. In cells transfected with dominant negative CREB lithium-stimulated proliferation was unchanged whereas blocking Wnt/beta-catenin by dominant negative TCF4 reduced proliferation by approx. 50%. CONCLUSION: Our data indicate that Wnt/beta-catenin signalling is of major importance in the control of lithium-dependent thyrocyte proliferation.

Wnt-5a has tumor suppressor activity in thyroid carcinoma.

Stabilization of beta-catenin by inhibition of its phosphorylation is characteristic of an activation of the canonical Wnt/beta-catenin signaling pathway and is associated with various human carcinomas. It contrasts to an as yet incompletely characterized action of an alternative noncanonical Wnt signaling pathway on neoplastic transformation. The aim of the present study was to test the effects of a member of the noncanonical Wnt signaling pathway, Wnt-5a, in primary thyroid carcinomas and in thyroid carcinoma cell lines. Compared to normal tissue Wnt-5a mRNA expression was clearly increased in thyroid carcinomas. Immunohistochemically, a bell-shaped response was observed with low to undetectable levels in normal tissue and in anaplastic tumors whereas differentiated thyroid carcinomas showed strong positive immunostaining for Wnt-5a. Transfection of Wnt-5a in a thyroid tumor cell line FTC-133 was able to reduce proliferation, migration, invasiveness and clonogenicity in these cells. These effects of Wnt-5a are associated with membranous beta-catenin translocation and c-myc oncogene suppression and are mediated through an increase in intracellular Ca(2+) release, which via CaMKII pathways promotes beta-catenin phosphorylation. Specific inhibition of beta-catenin phosphorylation by W-7, a calmodulin inhibitor, or by KN-93, a CaMKII inhibitor, supports these findings whereas PKC inhibitors were without effect. This interaction occurs downstream of GSK-3 beta as no Wnt-5a effect was seen on the Ser(9) phosphorylation of GSK-3 beta. Our data are compatible with the hypothesis that Wnt-5a serves as an antagonist to the canonical Wnt-signaling pathway with tumor suppressor activity in differentiated thyroid carcinomas.