Relação entre a via de sinalização da leptina e a progressão de carcinomas papilíferos de tireoide em crianças e adolescentes

Abstract

Thyroid cancer is the most common endocrine gland neoplastic malignancy and its incidence has increased in many countries in recent years, Brazil included. Thyroid cancer is rare in children and adolescents and it accounts for 2% of the cases. Its histologically more frequent type is papillary carcinoma. The prognosis in this population is excellent, with survival rates superior to 95%. However, when diagnosed, this part of the population has clinical and pathological characteristics of advanced disease, such as capsular invasion, extrathyroidal extension and lymph node metastasis. Leptin is a hormone produced mainly by adipose tissue, participating in the regulation of food uptake and energy expenditure and it has been associated with the prognostic factor of hematologic, pancreas, breast and thyroid tumors. There are reports about the action of this hormone as an angiogenic and mitogenic factor. The goal of this study is to assess the association between thyroid papillary carcinoma in children and adolescents and the leptin signaling pathway proteins through ObR, pJAK2 and pSTAT3 immunofluorescence, related to data that point to the prognosis of the disease. This study included 52 patients and the expression and staining were assessed in consensus by two pathologists. The staining profile was punctiform and multifocal for both the non-neoplastic adjacent tissue as well as the tumor tissue. Scores were assigned for immunostaining (1-10% and >10%) and possible associations among ObR, pJAK2 and pSTAT3 were analyzed, with qualitative demographic variables or clinical and pathological features. All the cases presented relevant staining (>10%) in the non-neoplastic tissue for the three proteins while in the neoplastic tissue there was staining for ObR in 53% of the cases, 47% for pJAK2 and 71% for pSTAT3. ObR was 6.2 times more frequent in patients without lymph node metastasis. The tumor size was inversely related to relevant staining for pJAK2 and pSTAT3. This study shows that ObR is related to less lymph node metastasis and pJAK-pSTAT3 to smaller tumor size, suggesting that the leptin signaling pathway in thyroid cancer in children and adolescents may play an important role in the prevention of tumorigenesis.