Abstract A111: Plant galactolipid dLGG suppresses lung metastasis of melanoma through modulating endothelial-mesenchymal transition extravasation and oxylipins dynamics
Authors: Yang Chung-Chih , Chang Meng-Ting , Shyur Lie-Fen 
Published: May 2016

A galactolipid 1,2-di-O-linolenoyl-3-O-ß-galactopyranosyl-sn-glycerol (designated dLGG) isolated from medicinal plant Crassocephalum rabens (Asteraceae) was demonstrated to be anti-inflammatory and anti-melanoma tumor growth in syngeneic mouse system in our laboratory. In this study, an experimental lung metastasis mouse model using a B16 melanoma cell clone (designated B16COX-2/Luc) carrying COX-2 promoter driven luciferase reporter gene was established to monitor the cancer cell growth and metastasis in animals and the dLGG effect. Our data showed that dLGG (20 mg/kg BW, dLGG−20), cisplatin (2 mg/kg BW, CP−2), and combination drug treatment (CP−2+dLGG−20) significantly inhibited lung metastasis of melanoma in mice from 100% at tumor control group to 9.2%, 43.1%, and 4.1%, respectively, as determined by bioluminescence intensity. The dLGG (30±8 days), cisplatin (35±9 days) and combination treatment group (29±7 days) mice showed longer mean survival time than tumor control group (22±1 days)(P&lt;0.02). Immunohistochemistry study on lung tissues showed that dLGG and CP+dLGG combination treatment inhibited the expression of cell proliferation (PCNA), cell invasion (MMP2 and MMP9), and cell metastasis (COX-2, CXCR4 and CD9) markers, but less effective in cisplatin group. We investigated the underlying mechanism of dLGG on inhibiting melanoma cell activity, including endothelial-mesenchymal transition (EMT), and extravasation through tight junction permeability. Our data showed that EMT markers expression, such as effector vimentin, regulator snail, and inducer TGF-ß, ß-catenin and TNF-α were down-regulated in dLGG-treated melanoma cells. Melanoma culture medium (CM) induced tight junction permeability in HUVECs monolayer which was attenuated by dLGG treatment. Furthermore, VEGF-induced melanoma cell extravasation via activation of FAK/PI3K/AKT pathway could be also inhibited by dLGG treatment. Oxylipins, a specific group of lipid mediators, play a crucial role in inflammation and are also implied in cancer and other diseases. We have established oxylipin metabolomics platform using UPLC/triple-quadrupole mass spectrometry coupled with partial least squares discriminant analysis (PLS-DA), to investigate the role of oxylipins involved in melanoma lung metastasis mice. The results of serum oxylipins analysis showed that cisplatin treatment not only induced significantly on anti-inflammatory 11,12-EET, but also increased proinflammatory 11-HETE and LTB4 (10- to 20-fold), relative to the tumor control. dLGG alone or dLGG and cisplatin combination treatment increased the anti-inflammatory EPA, EETs, 15-HEPE and 17-HDOHE (2- to 13-fold) in mouse serum. This study sheds light on the novel activity and the underlying molecular mechanisms of phytoagent dLGG on inhibition of melanoma cell EMT, tight junction permeability, and extravasation that support in part the in vivo therapeutic effect of dLGG on melanoma lung metastasis.

Citation Format: Chung-Chih Yang, Meng-Ting Chang, Lie-Fen Shyur. Plant galactolipid dLGG suppresses lung metastasis of melanoma through modulating endothelial-mesenchymal transition extravasation and oxylipins dynamics. [abstract]. In: Proceedings of the AACR-NCI-EORTC International Conference: Molecular Targets and Cancer Therapeutics; 2015 Nov 5-9; Boston, MA. Philadelphia (PA): AACR; Mol Cancer Ther 2015;14(12 Suppl 2):Abstract nr A111.