Ultrastructural and Molecular Evidence of Macroautophagy in Functioning PitNETs and Experimental Pituitary Tumors.

Introduction: Macroautophagy is a lysosome-mediated degradation process that controls the quality of cytoplasmic components and organelles, with its regulation depending on autophagy-related proteins (Atg) and with Beclin1/Atg6 and microtubule-associated protein light chain 3 (LC3/Atg8) being key players in the mammalian autophagy. As reports on this mechanism in the field of pituitary neuropathology and neuroendocrinology are scarce, our study analyzed the ultrastructural signs of macroautophagy and the expression of Beclin1 and LC3 proteins in human functioning PitNETs and in experimental pituitary tumors.

Methods: A group of humans functioning PitNETs and an experimental lactotroph model in rats of the F344 strain stimulated with estradiol benzoate (BE) were used.

[Update on mechanisms of pituitary tumorigenesis.].

Pituitary adenomas are intracranial neoplasms that originate from the adeno-pituitary cells, are mostly benign and slow growing. However, a small percentage can be aggressive and spread locally and / or remotely as malignancies. In recent years, progress has been made in understanding the biology of pituitary tumors, identifying mutations in the germline, somatic lines, and epigenetic mechanisms.

Association of PTP4A3 expression and tumour size in functioning pituitary adenoma: a descriptive study.

Background: PTP4A3 is a subclass of a protein tyrosine phosphatase super family and is expressed in a range of epithelial neoplasms. We evaluated PTP4A3 expression and its association with clinicopathological parameters in different types of functioning pituitary adenomas.

Methods: A total of 34 functioning pituitary adenomas samples were evaluated in this observational study.

Trastuzumab inhibits pituitary tumor cell growth modulating the TGFB/SMAD2/3 pathway.

In pituitary adenomas, early recurrences and resistance to conventional pharmacotherapies are common, but the mechanisms involved are still not understood. The high expression of epidermal growth factor receptor 2 (HER2)/extracellular signal-regulated kinase (ERK1/2) signal observed in human pituitary adenomas, together with the low levels of the antimitogenic transforming growth factor beta receptor 2 (TBR2), encouraged us to evaluate the effect of the specific HER2 inhibition with trastuzumab on experimental pituitary tumor cell growth and its effect on the antiproliferative response to TGFB1. Trastuzumab decreased the pituitary tumor growth as well as the expression of ERK1/2 and the cell cycle regulators CCND1 and CDK4.