Revealing the effect of 6-gingerol, 6-shogaol and curcumin on mPGES-1, GSK-3β and β-catenin pathway in A549 cell line

Abstract

Background and aim: In our study, anticancer effects of 6-gingerol, 6-shogaol from ginger and curcumin from turmeric were investigated and the results were compared with each other. We aimed to reveal their effects on microsomal prostaglandine E2 synthase 1 (mPGES-1) which is related with cancer progression and inflammation as well as β-catenin and glycogen synthase kinase 3β (GSK-3β) that are the main components of Wnt/GSK3 pathway. As it is known activation of GSK-3β and high levels of mPGES-1 pathway leads to cell proliferation and aggravates cancer progression. Therefore both of them are potential targets for cancer therapy. 6-shogaol and 6-gingerol' s effect on this pathway is not known very well up to now while curcumin that is known as an mPGES-1 inhibitor has anticancer properties via this pathway and many other pathways. Besides being in Zingiberaceae family, ginger's 6-gingerol and 6-shogaol have a molecular similarity with turmeric's curcumin. In our study we investigated their effects using a popular non small lung cancer cell line named A549 which expresses mPGES-1 and has active GSK3β pathway. IL-1β was used for inducing mPGES-1 and enabling the cancer characteristics such as cell proliferation. So compounds that inactivates or decreases the level of these components might be potential anticancer agents.

Materials and methods: A549 cells were incubated with interleukin 1β (IL-1β) for 24 h in order to maintain mPGES-1 enzyme induction. Experiments were performed both on IL-1β and non-IL-1β group. Real time cell analysis was performed to determine the cytotoxicity. Samples for western blotting and RT-PCR were collected after 24 h incubation with compounds to determine the amount of mPGES-1, GSK-3β, p-GSK-3β, β-catenin protein and mRNA. PGE2 which is the end product of mPGES-1 was measured by using ELISA kit.

Results: As a result of cell profile assay, cells exposed to IL-1β proliferate faster than non-IL-1β ones. This shows that induced mPGES-1 might play a role through GSK3β pathway and 24 h IC50 value of 6-shogaol is 62 μM. IL-1β increased protein and mRNA levels of mPGES-1, p-GSK-3β, β-catenin and GSK-3β in control group. Effects of curcumin and 6-shogaol on these parameters were against IL-1β's effect while 6-gingerol was not effective at all. Furthermore, 6-shogaol and curcumin might be effective on GSK3β pathway via lowering PGE2 levels.

Conclusion: We saw that 6-shogaol is as effective as curcumin on this pathway and our study shows that 6-shogaol might show its anticancer properties via mPGES-1 and GSK3β pathway. May be these results might used for designing in vivo studies in future.

Keywords: 6-Gingerol; 6-Shogaol; A549; GSK-3β; mPGES-1; β-Catenin.