Metformin Reduces NGF-Induced Tumour Promoter Effects in Epithelial Ovarian Cancer Cells
PHARMACEUTICALS
Authors: Garrido, Maritza P.; Salvatierra, Renato; Valenzuela-Valderrama, Manuel; Vallejos, Christopher; Bruneau, Nicole; Hernandez, Andrea; Vega, Margarita; Selman, Alberto; Quest, Andrew F. G.; Romero, Carmen
Abstract
Epithelial ovarian cancer (EOC) is a lethal gynaecological neoplasm characterized by rapid growth and angiogenesis. Nerve growth factor (NGF) and its high affinity receptor tropomyosin receptor kinase A (TRKA) contribute to EOC progression by increasing the expression of c-MYC, survivin and vascular endothelial growth factor (VEGF) along with a decrease in microRNAs (miR) 23b and 145. We previously reported that metformin prevents NGF-induced proliferation and angiogenic potential of EOC cells. In this study, we sought to obtain a better understanding of the mechanism(s) by which metformin blocks these NGF-induced effects in EOC cells. Human ovarian surface epithelial (HOSE) and EOC (A2780/SKOV3) cells were stimulated with NGF and/or metformin to assess the expression of c-MYC, beta-catenin, survivin and VEGF and the abundance of the tumor suppressor miRs 23b and 145. Metformin decreased the NGF-induced transcriptional activity of MYC and beta-catenin/T-cell factor/lymphoid enhancer-binding factor (TCF-Lef), as well as the expression of c-MYC, survivin and VEGF in EOC cells, while it increased miR-23b and miR-145 levels. The preliminary analysis of ovarian biopsies from women users or non-users of metformin was consistent with these in vitro results. Our observations shed light on the mechanisms by which metformin may suppress tumour growth in EOC and suggest that metformin should be considered as a possible complementary therapy in EOC treatment.
Acute and chronic lithium treatment increases Wnt/beta-catenin transcripts in cortical and hippocampal tissue at therapeutic concentrations in mice
METABOLIC BRAIN DISEASE
Authors: De-Paula, Vanessa J.; dos Santos, Carla Cristine C.; Luque, Maria Carolina A.; Ali, Taccyana M.; Kalil, Jorge E.; Forlenza, Orestes V.; Cunha-Neto, Edecio
Abstract
Lithium activates Wnt/beta-catenin signaling leading to stabilization of free cytosolic beta-catenin. The aim of the present study is to evaluate the in vivo effect of acute and chronic lithium treatment on the expression of beta-catenin target genes, addressing its transcripts HIG2, Bcl-xL, Cyclin D1, c-myc, in cortical and hippocampal tissue from adult mice. Lithium doses were established to yield therapeutic working concentrations. In acute treatment, mice received a 300 mu L of a 350 mg/kg solution of LiCl by gavage, and were euthanized after 2 h, 6 h and 12 h. To determine the effect of chronic treatment, animals were continuously fed either with chow supplemented with 2 g/kg Li2CO3, or regular chow (controls), being euthanized after 30 days. All animals had access to drinking water and 0.9% saline ad libitum. After acute and chronic treatments samples of peripheral blood were obtained from the tail vein for each animal, and serum concentrations of lithium were determined. All transcripts were up-regulated in cortical and hippocampal tissues of lithium-treated mice, both under acute and chronic treatments. There was a positive correlation between serum lithium concentrations and the increment in the expression of all transcripts. This effect was observed in all time points of the acute treatment (i.e., 2, 6 and 12 hours) and also after 30 days. We conclude that Wnt/beta-catenin transcriptional response (HIG2, Bcl-xL, Cyclin D1 and c-myc) is up-regulated in the mouse brain in response to acute and chronic lithium treatment at therapeutic concentrations.