phenanthrenes and Pituitary-Neoplasms

Triptolide, an effective component derived from Tripterygium wilfordii, has been well recognized to process a broad-spectrum antitumor activities in various tumor types. However, the potential role of triptolide in pituitary adenomas remains unknown. The aim of this study was to investigate the precise role of triptolide and underlying mechanism in regulating pituitary adenoma cell viability, migration and invasion.. We use mouse pituitary adenoma cells (TtT/GF and AtT20 cells) as the experiment model and treated them with varying concentrations of triptolide. The corresponding inhibitory effects on cell viability, migration, invasion and apoptosis were examined respectively, and the underlying mechanism was determined by investigating ADAM12 (a disintegrin and metalloprotease 12)/EGFR signaling.. Triptolide significantly inhibited cell viability, migration and invasion in TtT/GF and AtT20 cells in a dose-dependent manner. Mechanistically, triptolide significantly reduced ADAM12 expression at protein levels and attenuated ADAM12/EGFR signaling. Meanwhile, triptolide treatment combined with ADAM12 silencing enhanced the suppression effects on cell viability, migration and invasion, and those effects were restored following ADAM12-rescued. Moreover, triptolide suppressed the tumorigenesis of TtT/GF and AtT20 cells in vivo.. Our research provides evidence that triptolide inhibits pituitary adenoma cell viability, migration and invasion via ADAM12/EGFR signaling pathway. These findings suggest a potential role for triptolide in treating pituitary adenomas.

Topics: ADAM12 Protein; Adenoma; Animals; Antineoplastic Agents, Alkylating; Cell Line, Tumor; Cell Movement; Cell Survival; Diterpenes; Epoxy Compounds; ErbB Receptors; Mice; Phenanthrenes; Pituitary Gland; Pituitary Neoplasms; Signal Transduction

Triptolide is a principal diterpene triepoxide from the Chinese medical plant Tripterygium wilfordii Hook. f., whose extracts have been utilized in dealing with diverse diseases in traditional Chinese medicine for centuries. Recently, the antitumor effect of triptolide has been found in several pre-clinical neoplasm models, but its effect on pituitary corticotroph adenomas has not been investigated so far. In this study, we are aiming to figure out the antitumor effect of triptolide and address the underlying molecular mechanism in AtT20 murine corticotroph cell line. Our results demonstrated that triptolide inhibited cell viability and colony number of AtT20 cells in a dose- and time-dependent pattern. Triptolide also suppressed proopiomelanocortin (Pomc) mRNA expression and extracellular adrenocorticotropic hormone (ACTH) secretion in AtT20 cells. Flow cytometry prompted that triptolide leaded to G2/M phase arrest, apoptosis program and mitochondrial membrane depolarization in AtT20 cells. Moreover, dose-dependent activation of caspase-3 and decreased Bcl2/Bax proportion were observed after triptolide treatment. By western blot analysis we found that triptolide impeded phosphorylation of NF-κB p65 subunit and extracellular signal-regulated kinase (ERK), along with reduction of cyclin D1, without any impact on other NF-κB related protein expression like total p65, p50, IκB-α, p-IκB-α. Furthermore, the mouse xenograft model revealed the inhibition of tumor growth and hormone secretion after triptolide administration. Altogether this compound might be a potential pharmaceutical choice in managing Cushing's disease.

Topics: Animals; Apoptosis; Cell Cycle Checkpoints; Cell Line, Tumor; Cell Proliferation; Cell Survival; Clone Cells; Corticotrophs; Diterpenes; Epoxy Compounds; Female; Hormones; MAP Kinase Signaling System; Mice; Mice, Nude; Mitochondria; NF-kappa B; Phenanthrenes; Pituitary Neoplasms; Pro-Opiomelanocortin; Signal Transduction; Transcription, Genetic

ATP-sensitive K+ (KATP) channels have been characterized in pituitary GH3 cells with the aid of the patch-clamp technique. In the cell-attached configuration, the presence of diazoxide (100 microM) revealed the presence of glibenclamide-sensitive KATP channel exhibiting a unitary conductance of 74 pS. Metabolic inhibition induced by 2,4-dinitrophenol (1 mM) or sodium cyanide (300 microM) increased KATP channel activity, while nicorandil (100 microM) had no effect on it. In the inside-out configuration, Mg-ATP applied intracellularly suppressed the activity of KATP channels in a concentration-dependent manner with an IC50 value of 30 microM. The activation of phospholipase A2 caused by mellitin (1 microM) was found to enhance KATP channel activity and further application of aristolochic acid (30 microM) reduced the mellitin-induced increase in channel activity. The challenging of cells with 4,4'-dithiodipyridine (100 microM) also induced KATP channel activity. Diazoxide, mellitin and 4,4'-dithiodipyridine activated the KATP channels that exhibited similar channel-opening kinetics. In addition, under current-clamp conditions, the application of diazoxide (100 microM) hyperpolarized the membrane potential and reduced the firing rate of spontaneous action potentials. The present study clearly indicates that KATP channels similar to those seen in pancreatic beta cells are functionally expressed in GH3 cells. In addition to the presence of Ca(2+)-activated K+ channels, KATP channels found in these cells could thus play an important role in controlling hormonal release by regulating the membrane potential.

Topics: 2,4-Dinitrophenol; Action Potentials; Adenoma; Adenosine Triphosphate; Animals; Aristolochic Acids; Calcium Chloride; Diazoxide; Disulfides; Enzyme Activation; Ion Transport; Magnesium; Melitten; Nicorandil; Phenanthrenes; Phospholipases A; Phospholipases A2; Pituitary Gland, Anterior; Pituitary Neoplasms; Potassium; Potassium Channels; Pyridines; Rats; Sodium Cyanide; Tumor Cells, Cultured