Anti-proliferative Effects of Pinocembrin Isolated From Anomianthus dulcis on Hepatocellular Carcinoma Cells.

BACKGROUND: Hepatocellular carcinoma (HCC) is the most prevalent primary liver cancer. Anomianthus dulcis (Dunal) J.Sinclair (syn. Uvaria dulcis) has been used in Thai traditional medicine in various therapeutic indications. Phytochemical constituents of A. dulcis have been isolated and identified. However, their effects on liver cancer and the associated mechanisms have not been elucidated. METHODS: Dry flowers of A. dulcis were extracted using organic solvents, and chromatographic methods were used to purify the secondary metabolites. The chemical structures of the pure compounds were elucidated by analysis of spectroscopic data. Cytotoxicity against HCC cells was examined using SRB assay, and the effects on cell proliferation were determined using flow cytometry. The mechanisms underlying HCC inhibition were examined by molecular docking and verified by Western blot analysis. RESULTS: Among 3 purified flavonoids, pinocembrin, pinostrobin, and chrysin, and 1 indole alkaloid (3-farnesylindole), only pinocembrin showed inhibitory effects on the proliferation of 2 HCC cell lines, HepG2 and Li-7, whereas chrysin showed specific toxicity to HepG2. Pinocembrin was then selected for further study. Flow cytometric analyses revealed that pinocembrin arrested the HCC cell cycle at the G1 phase with a minimal effect on cell death induction. Pinocembrin exerted the suppression of STAT3, as shown by the molecular docking on STAT3 with a better binding affinity than stattic, a known STAT3 inhibitor. Pinocembrin also suppressed STAT3 phosphorylation at both Tyr705 and Ser727. Cell cycle regulatory proteins under the modulation of STAT3, namely cyclin D1, cyclin E, CDK4, and CDK6, are substantially suppressed in their expression levels. CONCLUSION: Pinocembrin extracted from A. dulcis exerted a significant growth inhibition on HCC cells via suppressing STAT3 signaling pathways and its downstream-regulated genes.

Induction of apoptotic cell death of cholangiocarcinoma cells by tiliacorinine from Tiliacora triandra: A mechanistic insight.

BACKGROUND: Cholangiocarcinoma (CCA) exhibits poor response to the present chemotherapeutic agents and frequently develops drug resistance. Finding novel anticancer drugs might enhance patient outcomes. Tiliacorinine, a bisbenzylisoquinoline alkaloid from the Thai medicinal plant Tiliacora triandra, effectively induced apoptosis of human CCA cell lines and inhibited tumor growth in mice. Here, we elucidate further the molecular mechanisms underlining the cytotoxicity of tiliacorinine and its implication in overcoming gemcitabine-resistance of CCA cells. METHODS: Cytotoxicity of tiliacorinine against CCA cell lines was assessed using MTT assay. The molecular signaling was determined using Western blot analysis. Molecular docking simulations were applied to predict the binding affinity and orientation of tiliacorinine to the possible binding site(s) of the target proteins. RESULTS: Tiliacorinine induced apoptotic cell death of CCA cells in a dose- and time-dependent manner. Tiliacorinine significantly suppressed the expression of anti-apoptotic proteins, Bcl-xL and XIAP; activated apoptotic machinery proteins, caspase-3, caspase-9, and PARP; and decreased the levels of pAkt and pSTAT3. EGF/EGFR activation model and molecular docking simulations revealed EGFR, Akt, and STAT3 as potent targets of tiliacorinine. Molecular docking simulations indicated a strong binding affinity of tiliacorinine to the ATP-binding pockets of EGFR, PI3K, Akt, JAK2, and SH2 domain of STAT3. Tiliacorinine could synergize with gemcitabine and restore the cytotoxicity of gemcitabine against gemcitabine-resistant CCA cells. CONCLUSION: Tiliacorinine effectively induced apoptosis via binding and blocking the actions of EGFR, Akt, and STAT3. GENERAL SIGNIFICANCE: Tiliacorinine is a novel multi-kinase inhibitor and possibly a potent anti-cancer agent, in cancers with high activation of EGFR.

Daidzein Hydroxylation by CYP81E63 Is Involved in the Biosynthesis of Miroestrol in Pueraria mirifica.

White Kwao Krua (Pueraria candollei var. mirifica), a Thai medicinal plant, is a rich source of phytoestrogens, especially isoflavonoids and chromenes. These phytoestrogens are well known; however, their biosynthetic genes remain largely uncharacterized. Cytochrome P450 (P450) is a large protein family that plays a crucial role in the biosynthesis of various compounds in plants, including phytoestrogens. Thus, we focused on P450s involved in the isoflavone hydroxylation that potentially participates in the biosynthesis of miroestrol. Three candidate P450s were isolated from the transcriptome libraries by considering the phylogenetic and expression data of each tissue of P. mirifica. The candidate P450s were functionally characterized both in vitro and in planta. Accordingly, the yeast microsome harboring PmCYP81E63 regiospecifically exhibited either 2' or 3' daidzein hydroxylation and genistein hydroxylation. Based on in silico calculation, PmCYP81E63 had higher binding energy with daidzein than with genistein, which supported the in vitro result of the isoflavone specificity. To confirm in planta function, the candidate P450s were then transiently co-expressed with isoflavone-related genes in Nicotiana benthamiana. Despite no daidzein in the infiltrated N. benthamiana leaves, genistein and hydroxygenistein biosynthesis were detectable by liquid Chromatography with tandem mass spectrometry (LC-MS/MS). Additionally, we demonstrated that PmCYP81E63 interacted with several enzymes related to isoflavone biosynthesis using bimolecular fluorescence complementation studies and a yeast two-hybrid analysis, suggesting a scheme of metabolon formation in the pathway. Our findings provide compelling evidence regarding the involvement of PmCYP81E63 in the early step of the proposed miroestrol biosynthesis in P. mirifica.

1'-Acetoxychavicol Acetate from Alpinia galanga Represses Proliferation and Invasion, and Induces Apoptosis via HER2-signaling in Endocrine-Resistant Breast Cancer Cells.

Estrogen receptor-positive breast cancer patients have a good prognosis, but 30% of these patients will experience recurrence due to the development of resistance through various signaling pathways. This study aimed to evaluate the mode of anticancer effects of 1'-acetoxychavicol acetate, which is isolated from the rhizomes of Alpinia galanga in estrogen receptor positive (MCF7) human epidermal growth factor receptor 2-overexpressed (MCF7/HER2), and endocrine-resistant breast cancer cells (MCF7/LCC2 and MCF7/LCC9). 1'-Acetoxychavicol acetate showed antiproliferation in a concentration- and time-dependent fashion and had higher potency in human epidermal growth factor receptor 2-overexpressed cell lines. This was associated with down-regulation of human epidermal growth factor receptor 2, pERK1/2, pAKT, estrogen receptor coactivator, cyclin D1, and MYC proto-oncogene while in vivo and significant reduction in the tumor mass of 1'-acetoxychavicol acetate-treated zebrafish-engrafted breast cancer groups. The anti-invasive effects of 1'-acetoxychavicol acetate were confirmed in vitro by the matrigel invasion assay and with down-regulation of C - X-C chemokine receptor type 4, urokinase plasminogen activator, vascular endothelial growth factor, and basic fibroblast growth factor 2 genes. The down-regulation of urokinase plasminogen activator and fibroblast growth factor 2 proteins was also validated by molecular docking analysis. Moreover, 1'-acetoxychavicol acetate-treated cells exhibited lower expression levels of the anti-apoptotic Bcl-2 and Mcl-1 proteins in addition to enhanced stress-activated kinases/c-Jun N-terminal kinase 1/2 and poly-ADP ribose polymerase cleavage, indicating apoptotic cell induction by 1'-acetoxychavicol acetate. Moreover, 1'-acetoxychavicol acetate had higher potency in human epidermal growth factor receptor 2-overexpressed cell lines regarding its inhibition on human epidermal growth factor receptor 2, pAKT, pERK1/2, PSer118, and PSer167-ERα proteins. Our findings suggest 1'-acetoxychavicol acetate mediates its anti-cancer effects via human epidermal growth factor receptor 2 signaling pathway.