Metformin inhibits lithocholic acid-induced interleukin 8 upregulation in colorectal cancer cells by suppressing ROS production and NF-kB activity

Abstract

Metformin, an inexpensive, well-tolerated oral agent that is a commonly used first-line treatment for type 2 diabetes, has become the focus of intense research as a potential anticancer agent. In this study, we describe the inhibitory effect of metformin in interleukin 8 (IL-8) upregulation by lithocholic acid (LCA) in HCT116 colorectal cancer (CRC) cells. Pharmacological inhibition studies indicated that reactive oxygen species (ROS) were involved in LCA-induced IL-8 upregulation through activation of the transcription factor NF-κB. Metformin was demonstrated to block LCA-stimulated ROS production, in turn suppressing NF-κB signaling that was critical for IL-8 upregulation. An NADPH oxidase assay proved that the inhibitory effect of metformin on ROS production was derived from its strong suppression of NADPH oxidase, a key producer of ROS in cells. Compared with conditioned media (CM) derived from HCT116 cells treated with LCA, CM derived from HCT116 cells pretreated with metformin and then treated with LCA lost all stimulatory effect on endothelial cell proliferation and tubelike formation. In conclusion, metformin inhibited NADPH oxidase, which in turn suppressed ROS production and NF-κB activation to prevent IL-8 upregulation stimulated by LCA; this prevention thus obstructed endothelial cell proliferation and tubelike formation.

Effect of Astaxanthin on Activation of Autophagy and Inhibition of Apoptosis in Helicobacter pylori-Infected Gastric Epithelial Cell Line AGS

“…To determine the effects on autophagy, the cells were pre-treated with compound C (10 μM) or metformin (10 mM) for 1 h before H. pylori stimulation. Pretreatment time periods for astaxanthin, compound C, and metformin were adapted from previous studies [ 33 , 34 , 35 , 36 , 37 ].…”

Metformin in colorectal cancer: molecular mechanism, preclinical and clinical aspects

“….Metformin (1–4 mM, 24–72 h) reduces EMT in HCT116 sphere cells via inactivation of Wnt3α/β-catenin signaling (with reduction of Vimentin and increased epithelial marker). Consequently, metformin promotes sensitization of HCT116 sphere cells towards 5-FU treatment (25 μg/mL).[39, 44, 47, 48, 50, 52]Caco-2 and HCT116 cellsAddition of metformin to 5-ASA (48 h) inhibits the Caco-2 (13 mM of metformin and 2.5 mM of 5-ASA) and HCT-116 cells proliferation (13 mM of metformin and 2.5 mM of 5-ASA) and induces apoptosis by inducing oxidative stress and NF-κB inflammatory responses.[40]DLD-1, HT-29, Colo205 and HCT116Metformin (2.5–10 mM) did not decrease the cell viability but sensitizes the cells towards TRAIL (50 ng/mL) that is followed with induction of extrinsic and intrinsic apoptosis through the suppression of Mcl-1 by promoting the dissociation of Noxa from Mcl-1 that activates E3 ligase Mule.[41]HT-29, SW620, and HCT116 cellsMetformin addition to sirolimus synergistically promotes the reduction cell viability (48 h) via downregulation of p-mTOR, p-70S6K, p-4EBP1, livin, survivin, E-cadherin, TGF-β, and pSmad3.[42]HT-29 and HCT116 cellsSingle exposure (24 h) either 1,25D3 (10–1000 nM) or metformin (1–20 mM) reduces the cell viability in HCT116 (p53 wild-type), HCT116 (p53 − / − ), and HT-29 (p53 mutant). Both 1,25D3 and metformin synergistically promotes apoptosis, and autophagy irrespective of the p53 status in all of the cells tested via AMPK, intracellular ROS, Bcl-2, and increasing LC3II:LC3I ratio.…”

“…Carcinogenesis through angiogenesis can be associated with promotion of inflammation by the augmentation of intracellular ROS. Metformin addition (10 mM) significantly suppresses lithocholic acid (LCA, 30 μM)-induced intracellular ROS level in HCT116 cells [50] via the inhibition of NADPH oxidase that consequently inactivates NF-κB and concomitantly downregulates IL-8. Moreover, the metformin-treated conditioned media inhibits HUVEC endothelial cell proliferation and tube-like formation as compared to LCA-treated conditioned media, suggesting metformin anti-angiogenic activity.…”

Salidroside inhibits MAPK, NF-κB, and STAT3 pathways in psoriasis-associated oxidative stress via SIRT1 activation

“…Nuclear factor-κB (NF-κB) is an essential inflammatory mediator in the pathogenesis of psoriasis; increased expression of NF-κB has been demonstrated in psoriatic lesions [4]. ROS can activate NF-κB through the phosphorylation of the inhibitor of kappa B kinase (IKK) complex [43,44]. Studies indicate that H 2 O 2 , imported via AQP3, participates in the activation of the NF-κB signaling pathway in keratinocytes and is involved in the pathogenesis of psoriasis [45].…”