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Objective To discover antitumor drugs showing a synergistic effect with the cannabinoid receptor agonist sildenafil mesylate (WIN55212-2), so as to provide a new strategy for potential drug combinations for improving the life quality of cancer patients. Methods Firstly, the antitumor activity was tested for the combination of cannabinoid receptor 1 (CB1R) receptor agonist WIN55212-2 with each of 25 antitumor drugs using three tumor cell lines with high CB1R, HepG2, DU145 and HCT-8, by highthroughput assay. Then, the in vitro tumor colony-forming assay and 3D tumor spheroid assay were conducted to confirm the synergistic effect for the effective drug combination. Flow cytometry was used to investigate the effect of the synergistic drug combination on the apoptosis and cell cycle progression. Results Three drugs showed a synergistic inhibitory effect on the proliferation of tested tumor cells by combining with WIN55212-2, and among them, the combination of exemestane with WIN55212-2 displayed best effect, which showed a dose-dependent synergistic antitumor effect in the in vitro tumor colony-forming test and 3D tumor spheroid assay (CI＜1).Compared with the single-exemestane treatment, the combination of exemestane with WIN55212-2 significantly increased the apoptosis of HepG2 cells (P＜0.01) and caused G2/M phase arrest of the HepG2 cells. Conclusion The study is the first to report that the combination of exemestane with WIN55212-2 showed a synergistic anti-tumor activity on HepG2 cells, which was likely related to the promotion of apoptosis and induction of cell cycle arrest.
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Objective To explore the protective effects of cannabinoid analogues WIN55212-2 on paraquat poisoned mice. Methods Totally 35 healthy male C57BL/6 mice were randomly(random number) divided into four groups: PQ group (paraquat poisoned, n=10), WIN 1 mg group (PQ+WIN55212-21 mg n=10), WIN 2 mg group (PQ+WIN55212-22 mg, n=10), control group (n=5).The PQ poisoned animal models were established in the PQ group, WIN 1 mg group and WIN 2 mg group by intraperitoneally injection of paraquat with a concentration of 20 mg/kg. Intraperitoneal injection of WIN55212-2 (containing Tween 80 cosolvent) at the concentration of 1 mg/kg and 2 mg/kg was performed 1 h before PQ exposure in the two interfered groups. Equivalent volume of saline was given to the control group. WIN55212-2 was injected twice a week from the second week. In the acute phase (14 d), 5 mice were randomly sacrificed in the PQ group, WIN 1 mg group and WIN 2 mg group, and 3 mice were sacrificed in the control group to obtain blood sample, bronchoalveolar lavage fluid (BALF) and lung tissue. All the remaining mice were executed on day 28, and the tissue samples were collected as mentioned above. HE staining and Masson staining were performed to observe the changes of lung tissues after PQ poisoning. Changes of TNF-α, IL-6 and TGF-β in plasma and BALF were measured by ELISA. Results In the acute phase, the pathological sections of lung tissues in the PQ group, WIN 1 mg group and WIN 2 mg group showed diffuse inflammation, which was improved after the intervention of WIN5522-2, especially in the WIN 1 mg group. IL-6 levels of BALF in the PQ group, WIN 1 mg group, WIN 2 mg group and the control group were (1024.77±124.74)U/L, (620.48±99.76)U/L, (823.29±157.88) U/L, and (180.42±20.22)U/L, respectively. IL-6 levels in the WIN 1 mg group and the WIN 2 mg group were statistically lower than those in the PQ group (P=0.021, P=0.016). However, no difference was found between the two intervention groups(P=0.114). The similar condition was also found in TNF-α in BALF and plasma. In the chronic phase, mice in the PQ group, WIN 1 mg group and WIN 2 mg group showed fibrosis in tissue by HE and Masson staining, and the inflammatory condition was improved after the intervention of WIN5522-2, which was more obvious in the WIN 1 mg group. In BALF, TNF-α level was (321.64±50.54)U/L, (260.23±48.19)U/L, (278.89±29.40)U/L, (89.76 ± 10.87)U/L in the PQ group, WIN 1 mg group, WIN 2 mg group and the control group. Differences were found between the WIN 1 mg group and the control group and the WIN 2 mg group. Similar differences were also observed in plasma TNF-α, but not in TGF-β. Conclusions A small dose of WIN55212-2 can improve the general condition of PQ poisoning mice, and reduce the inflammatory and fibrosis-related cytokines levels in PQ poisoning mice.
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BACKGROUND: WIN55212-2 is a synthetic cannabinoid agonist and selective to cannabinoid 1 (CB1) receptors, which are distributed mainly in the central nervous system. Opioid receptors and CB1 receptors have several similarities in terms of their intracellular signal transduction mechanisms, distributions, and pharmacological action. Several studies have therefore sought to describe the functional interactions between opioids and cannabinoids at the cellular and behavioral levels. The present study investigated agonist-stimulated [35S]GTPgammaS binding by WIN55212-2 in rat brain membranes and determined the antagonism by selective opioid antagonists at the level of receptor-ligand interaction and intracellular signal transduction. METHODS: Sprague-Dawley rats (male, n = 20) were euthanized for the preparation of brain membranes. In agonist-stimulated [35S]GTPgammaS binding by WIN55212-2, the values of EC50 and maximum stimulation (% over basal) were determined in the absence or presence of the micro, kappa and delta opioid receptor antagonists naloxone (20 nM), norbinaltorphimine (3 nM), and naltrindole (3 nM), respectively. Ke values for opioid antagonist inhibition in the absence or presence of each opioid receptor antagonist were calculated using the following equation: [nanomolar antagonist] / (dose ratio of EC50 - 1). RESULTS: In WIN55212-2-stimulated [35S]GTPgammaS binding in the rat brain membranes, the values of EC50 and maximum stimulation (% over basal) were 154 +/- 39.5 nM and 27.6 +/- 5.3% over basal, respectively. Addition of selective opioid antagonists did not produce a significant rightward shift in the WIN55212-2 concentration-response curve, and Ke values were not applicable. CONCLUSIONS: Our results suggest that the functional activity of WIN55212-2-stimulated [35S]GTPgammaS binding was not affected by opioid antagonists in the rat brain membranes. Although the exact mechanism remains unclear, our results may partially elucidate their actions.