Giovanni Tulipano1, Andrea Giustina2. 1. Unit of Pharmacology, Department of Molecular and Translational Medicine, University of Brescia, Viale Europa 11, 25123, Brescia, Italy. giovanni.tulipano@unibs.it. 2. Division of Endocrinology, IRCCS San Raffaele Hospital, San Raffaele Vita- Salute University - Head, Milan, Italy.
Abstract
PURPOSE: The aim of this work was to investigate possible direct effects of the somatostatin analog octreotide on autophagy markers and markers of cellular metabolic activity using in vitro cultured rat pituitary tumor cells (GH3 cell line). METHODS: We measured two markers of the autophagic flux in cell lysates by Western blot and MTT reductive activity, total cellular ATP levels, pyruvate dehydrogenase (PDH) complex activity in cells lysates as markers of cell viability related to metabolic activity. RESULTS: Octreotide (100 nM) treatment induced autophagy activation (increased LC3-I protein lipidation) and enhanced the autophagic flux (SQSTM1/p62 protein downregulation) in GH3 cells in different incubation media, in detail in Hank's balanced salt solution (HBSS) as well as in maintenance medium with serum. We did not observe any decrease of redox activity and energy production related to the induction of autophagy by octreotide. On the other hand, short-term treatments with octreotide in HBSS tended to enhance MTT reduction activity and to increase PDH complex enzymatic activity and ATP levels measured in GH3 cell lysates. CONCLUSIONS: We provided evidence that octreotide can affect autophagy in pituitary tumor cells. The observed effects of octreotide were not related to a decrease of cellular metabolic activity. Finally, the induction of autophagy was either short-lived or overshadowed by other factors in the long term and this limit does not help clarifying their real impact on the pharmacological activity of somatostatin analogs.
PURPOSE: The aim of this work was to investigate possible direct effects of the somatostatin analog octreotide on autophagy markers and markers of cellular metabolic activity using in vitro cultured ratpituitary tumor cells (GH3 cell line). METHODS: We measured two markers of the autophagic flux in cell lysates by Western blot and MTT reductive activity, total cellular ATP levels, pyruvate dehydrogenase (PDH) complex activity in cells lysates as markers of cell viability related to metabolic activity. RESULTS:Octreotide (100 nM) treatment induced autophagy activation (increased LC3-I protein lipidation) and enhanced the autophagic flux (SQSTM1/p62 protein downregulation) in GH3 cells in different incubation media, in detail in Hank's balanced salt solution (HBSS) as well as in maintenance medium with serum. We did not observe any decrease of redox activity and energy production related to the induction of autophagy by octreotide. On the other hand, short-term treatments with octreotide in HBSS tended to enhance MTT reduction activity and to increase PDH complex enzymatic activity and ATP levels measured in GH3 cell lysates. CONCLUSIONS: We provided evidence that octreotide can affect autophagy in pituitary tumor cells. The observed effects of octreotide were not related to a decrease of cellular metabolic activity. Finally, the induction of autophagy was either short-lived or overshadowed by other factors in the long term and this limit does not help clarifying their real impact on the pharmacological activity of somatostatin analogs.
Authors: Erika Peverelli; Andrea G Lania; Giovanna Mantovani; Paolo Beck-Peccoz; Anna Spada Journal: Endocrinology Date: 2009-04-02 Impact factor: 4.736
Authors: Shlomo Melmed; Marcello D Bronstein; Philippe Chanson; Anne Klibanski; Felipe F Casanueva; John A H Wass; Christian J Strasburger; Anton Luger; David R Clemmons; Andrea Giustina Journal: Nat Rev Endocrinol Date: 2018-09 Impact factor: 43.330