RAS/BRAF mutational status in familial non-medullary thyroid carcinomas: A retrospective study.

There are contrasting views on whether familial non-medullary thyroid carcinomas (FNMTCs) are characterized by aggressive behavior, and limited evidence exists on the prognostic value of BRAF and RAS mutations in these tumors. Thus, in the present study, clinicopathological features were analyzed in 386 non-medullary thyroid carcinomas (NMTCs), subdivided in 82 familial and 304 sporadic cases. Furthermore, the RAS and BRAF mutational statuses were investigated in a subgroup of 34 FNMTCs to address their clinical and biological significance. The results demonstrated that, compared with sporadic NMTCs, FNMTCs are characterized by significantly higher rates of multicentricity and bilaterality and are more frequently associated with chronic autoimmune thyroiditis. Notably, a statistically significant difference in the rates of multicentricity was observed by subgrouping familial tumors according to the number of relatives involved; those with ≥3 affected relatives were more likely to be multicentric. Furthermore, the FNMTC cohort exhibited higher rates of tumors >4 cm in size with extrathyroidal or lymph node involvement. However, no significant difference was observed. Similarly, no differences were observed with respect to the age of onset or the patient outcome. The mutational profiling exhibited a rate of 58.8% for BRAF V600E mutations in familial tumors, which is at the upper limit of the mutational frequency observed in historical series of sporadic thyroid cancer. A high rate of NRAS mutations (17.6%) was also observed, mostly in the follicular variant histotype. Notably, compared with BRAF/RAS-wild type FNMTCs, the familial carcinomas bearing BRAF or NRAS mutations exhibited slightly higher rates of bilaterality and multicentricity, in addition to increased frequency of locally advanced stage or lymph node involvement. The present data support the theory that FNMTCs are characterized by clinicopathological features that resemble a more aggressive phenotype and suggest that RAS/BRAF mutational analysis deserves to be further evaluated as a tool for the identification of FNMTCs with a potentially unfavorable prognosis.

Mitotane and Carney Complex: ten years follow-up of a low-dose mitotane regimen inducing a sustained correction of hypercortisolism.

OBJECTIVE: Primary pigmented nodular adrenocortical disease (PPNAD), an uncommon cause of Cushing's syndrome, is frequently associated with a wider clinical spectrum, the Carney complex (CC), a multiple endocrine neoplasia syndrome. DESIGN: We evaluated a low-dose mitotane regimen for treating severe hypercortisolism in a 27-year-old woman with CC. She presented with severe hypercortisolism and a history of surgeries for breast ductal adenoma, atrial cardiac myxomas with cerebral and peripheral arterial embolism, and near-total thyroidectomy because of an oxyphilic adenoma. The patient refused further surgery for adrenalectomy. RESULTS: During the first 7 months of mitotane (Lysodren, HRA Pharma, Paris, France), the daily oral dose was progressively increased from 0.5 to 4 g/day and then stopped because of the appearance of sustained signs of hypoadrenalism, that required a replacement therapy with 5 mg of prednisone o.d. A 10-month mitotane off-therapy follow-up was performed and when an increase in urine free cortisol (UFC) was noted, the mitotane regimen was restarted at lower doses (0.750-1 g/day). Serum morning cortisol levels and UFC were then maintained within the normal range, with plasma mitotane ranging between 2 and 4 mg/L. A sustained regression of Cushing's features without inducing hypoadrenalism was achieved, which still persists after 122 months of follow-up. Minimal initial gastric discomfort was the only side effect of which the patient complained and only during the first higher dose mitotane course. CONCLUSIONS: Long-term administration of a low maintenance dose of mitotane may be suggested as treatment for hypercortisolism in CC patients who refuse or are at high risk for surgical adrenalectomy.

A novel mutation in calcium-sensing receptor gene associated to hypercalcemia and hypercalciuria.

BACKGROUND: Familial Hyperparathyroidism (HPT) and Familial benign Hypocalciuric Hypercalcemia (FHH) are the most common causes of hereditary hypercalcemia. FHH has been demonstrated to be caused by inactivating mutations of calcium-sensing receptor (CaSR) gene, involved in PTH regulation as well as in renal calcium excretion. CASE PRESENTATION: In two individuals, father and son, we found a novel heterozygous mutation in CaSR gene. The hypercalcemia was present only in father, which, by contrast to the classic form of FHH showed hypercalciuria (from 300 to 600 mg/24 h in different evaluations) and a Calcium/Creatinine ratio of 0.031, instead of low or normal calciuria (<0.01 typical finding in FHH). His son showed the same mutation in CaSR gene, but no clinical signs or hypercalcemia although serum ionized calcium levels were close to the upper limit of normal values (1.30 mmol/L: normal range: 1.12-1.31 mmol/L). Sequence analysis revealed a point mutation at codon 972 of CaSR gene (chromosome 3q), located within cytoplasmic domain of the CaSR, that changes Threonine with Methionine. The father was treated with Cinacalcet 90 mg/day, with a decrease of total serum calcemia from an average value of 12.2 mg/dl to 10.9 mg/dl. CONCLUSION: This is a case of a novel inactivating point mutation of CaSR gene that determines an atypical clinical presentation of FHH, characterized by hypercalcemia, hypercalciuria and inadequate normal PTH levels. Functional assay demonstrated that the 972 M variant influenced the maturation of the protein, in terms of the post-translational glycosylation. The impairment of the receptor activity is in keeping with the specific localization of the 972 residue in the C-terminal tail, assigned to the intracellular signalling, that on the basis of the our findings appears to be differently modulated in parathyroid gland and in kidney.

Role of UBC9 in the regulation of the adipogenic program in 3T3-L1 adipocytes.

The small ubiquitin-like modifier-conjugating enzyme UBC9, involved in protein modification through covalent attachment of small ubiquitin-like modifier and other less defined mechanisms, has emerged as a key regulator of cell proliferation and differentiation. To explore the role of UBC9 in adipocyte differentiation, the UBC9 protein levels were examined in differentiating 3T3-L1 cells. UBC9 mRNA and protein levels were increased 2.5-fold at d 2 and then gradually declined to basal levels at d 8 of differentiation. In addition, UBC9 was expressed predominantly in the nucleus of preadipocytes but shifted to cytoplasmic compartments after d 4, after induction of differentiation. UBC9 knockdown was then achieved in differentiating 3T3-L1 preadipocytes using a specific small interfering RNA. Oil-Red-O staining demonstrated accumulation of large triglyceride droplets in approximately 90% of control cells, whereas lipid droplets were smaller and evident in only 30% of cells treated with the UBC9-specific small interfering RNA. CCAAT/enhancer-binding protein (C/EBP)-δ, peroxisome proliferator-activated receptor-γ, and C/EBPα mRNA levels were increased severalfold 2-6 d after induction of differentiation in control cells, whereas the expression of these transcription factors was significantly lower in the presence of UBC9 gene silencing. Adenovirus-mediated overexpression of a catalytically inactive mutant UBC9 protein in 3T3-L1 cells resulted in no changes in expression of adipogenic transcription factors and conversion to mature adipocytes as compared with control. In conclusion, UBC9 appears to play an important role in adipogenesis. The temporal profile of UBC9 induction and its ability to affect C/EBPδ mRNA induction support a role for this protein during early adipogenesis.

Involvement of the p66Shc protein in glucose transport regulation in skeletal muscle myoblasts.

The p66(Shc) protein isoform regulates MAP kinase activity and the actin cytoskeleton turnover, which are both required for normal glucose transport responses. To investigate the role of p66(Shc) in glucose transport regulation in skeletal muscle cells, L6 myoblasts with antisense-mediated reduction (L6/p66(Shc)as) or adenovirus-mediated overexpression (L6/p66(Shc)adv) of the p66(Shc) protein were examined. L6/(Shc)as myoblasts showed constitutive activation of ERK-1/2 and disruption of the actin network, associated with an 11-fold increase in basal glucose transport. GLUT1 and GLUT3 transporter proteins were sevenfold and fourfold more abundant, respectively, and were localized throughout the cytoplasm. Conversely, in L6 myoblasts overexpressing p66(Shc), basal glucose uptake rates were reduced by 30% in parallel with a approximately 50% reduction in total GLUT1 and GLUT3 transporter levels. Inhibition of the increased ERK-1/2 activity with PD98059 in L6/(Shc)as cells had a minimal effect on increased GLUT1 and GLUT3 protein levels, but restored the actin cytoskeleton, and reduced the abnormally high basal glucose uptake by 70%. In conclusion, p66(Shc) appears to regulate the glucose transport system in skeletal muscle myoblasts by controlling, via MAP kinase, the integrity of the actin cytoskeleton and by modulating cellular expression of GLUT1 and GLUT3 transporter proteins via ERK-independent pathways.