Novel Adiponectin Receptor Agonist Inhibits Cholangiocarcinoma via Adenosine Monophosphate-activated Protein Kinase

BACKGROUND

Cholangiocarcinoma (CCA) has a poor prognosis and only limited palliative treatment options. The deficiency of adiponectin and adenosine monophosphate-activated protein kinase (AMPK) signaling was reported in several malignancies, but the alteration of these proteins in CCA is still unclear.

OBJECTIVES

This study aimed to assess the role of adiponectin and AMPK signaling in CCA. Furthermore, AdipoRon, a novel adiponectin receptor (AdipoR) agonist, was evaluated in vitro and in vivo as a new anti-tumor therapy for CCA.

METHODS

The expression of AdipoR1 and p-AMPKα in human tissue microarrays (TMAs) was evaluated by immunohistochemistry staining (IHC). The effect of 2-(4-Benzoylphenoxy)-N-[1-(phenylmethyl)- 4-piperidinyl]-acetamide (AdipoRon) was investigated in vitro with proliferation, crystal violet, migration, invasion, colony formation, senescence, cell cycle and apoptosis assays and in vivo using a CCA engineered mouse model (AlbCre/LSL-KRASG12D/p53L/L). RT-qPCR and western blot methods were applied to study molecular alterations in murine tissues.

RESULTS

AdipoR1 and p-AMPKα were impaired in human CCA tissues, compared to adjacent non-tumor tissue. There was a positive correlation between the AdipoR1 and p-AMPKα levels in CCA tissues. Treatment with AdipoRon inhibited proliferation, migration, invasion and colony formation and induced apoptosis in a time- and dose-dependent manner in vitro(p<0.05). In addition, AdipoRon reduced the number of CCA and tumor volume, prolonged survival, and decreased metastasis and ascites in the treated group compared to the control group (p<0.05).

CONCLUSIONS

AdipoR1 and p-AMPKα are impaired in CCA tissues, and AdipoRon effectively inhibits CCA in vitro and in vivo. Thus, AdipoRon may be considered as a potential anti-tumor therapy in CCA.

Identification of a novel adiponectin receptor and opioid receptor dual acting agonist as a potential treatment for diabetic neuropathy

Diabetic neuropathy (DN) is a long-term complication of diabetes mellitus, affecting different periphery nerve systems including sensory and motor neurons. Hyperglycemia is the major cause of DN with symptoms such as weakness of balance or coordination, insensitivity to sensation, weakness of the muscles as well as numbness and pain in limbs Analgesic drug such as opioids can be effective to relief neuropathy pain but there is no effective treatment. Adiponectin is an anti-diabetic adipokine, which possesses insulin-sensitizing and neuroprotective effects. In this project, we aim to identify an agent which is dual acting to opioid and adiponectin receptors. Within a virtual screening repositioning campaign, a large collection of compounds with different structures comprehensive of adipoRon-like piperidine derivatives was screened by docking. Recently developed opioid receptor benzomorphanic agonists finally emerged as good ligands to adiponectin receptors showing some 2D and 3D structural similarities with AdipoRon. Particularly, we have identified (+)-MML1017, which has high affinity to the same binding domain of AdipoR1 and AdipoR2 as AdipoRon. Our western blot results indicate (+)-MML1017 activates AMPK phosphorylation through both adipoR1 and adipoR2 in neuronal cell line. Moreover, pretreatment of (+)-MML1017 can improve the cell viability with motor neurons under hyperglycermic conditions. The (+)-MML1017 also activates μ-opioid receptor cells in a concentration-dependent manner. Our study identified a novel compound having dual activity on opioid receptors and adiponectin receptors that may have analgesic effects and neuroprotective effects to treat diabetic neuropathy.

Hepatoprotective effects of AdipoRon against d-galactosamine-induced liver injury in mice

Adiponectin is an antidiabetic and antiatherogenic adipokine, which plays distinct roles in the balance of energy homoeostasis. As an insulin sensitizing hormone, adiponectin exerts multiple biological effects by the specific receptors (AdipoR1 and AdipoR2), through activation of AMP-activated protein kinase (AMPK) and peroxisome proliferator-activated receptor (PPAR)α pathways. AdipoRon, an orally active synthetic small-molecule AdipoR agonist, shows very similar effects to adiponectin in vitro and in vivo, which could be a promising therapeutic approach for obesity-related disorders. In view of the regulatory effects of adiponectin or AdipoRon on inflammatory response and energy metabolism, they might be endowed a curative potential for tissue damage. Hence, its effects and possible mechanism were investigated. In vitro studies on hepatocytes (L02) and macrophages (RAW264.7) suggested a protective and anti-inflammatory potential of AdipoRon. The effects were verified in acute hepatic injury mice induced by d-galactosamine (D-GalN): hepatic lesions were restored by AdipoRon or bicyclol (positive reference drug) pretreatment, which were characterized by a significant increase in serological and hepatic biomarkers (AST, ALT, MDA and NOSs). Besides, AdipoRon attenuated the inflammation in the liver, characterized by the dwindling proinflammatory macrophage infiltration, as well as the shrinkage of tumor necrosis factor-α (TNF-α), transforming growth factor beta 1 (TGF-β1), interleukin-1 beta (IL-1β) and interleukin-6 (IL-6); meanwhile conversely promoted AMPK activation by phosphorylation. Combined with liver histopathology, these results demonstrated the hepatoprotective effects of AdipoRon against D-GalN-induced damage, which might be ascribed to the attenuation of inflammation, inhibition of free radical reactions, as well as enhancement of liver energy metabolism.