No abstract

Though Dieckol, a phlorotannin of Ecklonia cava, was known to have antioxidant, anticancer, antidiabetic, and anti-inflammatory effects, the underlying antifibrotic mechanism of Dieckol still remains unclear until now. Thus, in the current study, the inhibitory mechanism of Dieckol on liver fibrosis was elucidated mainly in hepatic stellate cells (HSCs). Dieckol exerted cytotoxicity in LX-2, HSC-T6, and HepG2 cells with the reduced fibrosis features of large, spread out, and flattened polygonal shapes in LX-2 cells compared to untreated control. Dieckol attenuated the expression of α-SMA and TGF-β1, increased sub-G1 phase population, and induced caspase-3 activation and cleavages of PARP in HSCs. Furthermore, Dieckol decreased phosphorylation of ERK, p38, AKT, NF-kB, and IkB and activated the microRNA(miR)134 level and JNK phosphorylation in HSCs. Conversely, JNK inhbitor SP600125 reversed the effect of Dieckol on PARP, p-NF-kB, α -SMA, and p-JNK in LX-2 cells. Likewise, miR134 overexpression mimic enhanced phosphorylation of JNK and NF-kB and reduced the expression of α-SMA and PARP cleavage, while miR134 inhibitor reversed the ability of Dieckol to cleave PARP and attenuate the expression of α-SMA in LX-2 cells. Overall, our findings suggest that Dieckol suppresses liver fibrosis via caspase activation and miR134 mediated JNK activation and NF-kB inhibition.

Lambertianic acid (LA) is a biologically active compound from the leaves of Pinus koraiensis. In the present study, apoptotic mechanisms of LA plus TNF-related apoptosis-inducing ligand (TRAIL) were elucidated in non-small cell lung cancer cells (NSCLCs). Cytotoxicity assay, flow cytometry, immunoprecipitation and Western blotting were performed. Here, combined treatment of LA and TRAIL increased cytotoxicity, sub-G1 population and cleaved poly (ADPribose) polymerase (PARP) and caspase3/8/9 in A549 and H1299 cells compared to LA or TRAIL alone. Furthermore, combined treatment of LA and TRAIL significantly decreased anti-apoptotic proteins such as B-cell lymphoma 2 (Bcl-2), Fas-like inhibitor protein (FLIP) and X-linked inhibitor of apoptosis protein (XIAP) and enhanced the activation of pro-apoptotic proteins Bid compared to LA or TRAIL alone. In addition, combined treatment of LA and TRAIL upregulated the expression of Death receptor 4 (DR4) and downregulated phosphorylation of nuclear factor kappa-light-chainenhancer of activated B cells (p-NF-B), inhibitory protein of kB family (p-IB) and FLIP in A549 and H1299 cells along with disrupted binding of XIAP with caspase3 or NF-B. Overall, these findings suggest that lambertianic acid enhances TRAIL-induced apoptosis via inhibition of XIAP/NF-B in TRAIL resistant NSCLCs.