Da Hyun Lee

The synthetic compound 2′-hydroxy-2,4,6′-trimethoxychalcone overcomes P-glycoprotein-mediated multi-drug resistance in drug-resistant uterine sarcoma MES-SA/DX5 cells

The antitumor activity of a novel synthetic chalcone derivative, 2′-hydroxy-2,4,6′-trimethoxychalcone (1H3MC), was evaluated using the multi-drug-resistant human uterine sarcoma MES-SA/Dx5 cells. Treatment with 1H3MC reduced P-glycoprotein expression in a time-dependent manner and inhibited MES-SA/Dx5 cell proliferation. Cisplatin alone had no effect on cell viability, but combined treatment with cisplatin and 1H3MC exhibited synergistic cytotoxicity. Furthermore, the combination of cisplatin and 1H3MC synergistically cleaved both caspase-3 and its substrate protein, poly(ADP-ribose) polymerase, which resulted in the fragmentation of genomic DNA, a hallmark of apoptosis. These results suggest that 1H3MC is a promising adjuvant agent for overcoming P-glycoprotein-mediated multi-drug resistance in cancer cells.

C-C motif chemokine receptor 1 (CCR1) is a target of the EGF-AKT-mTOR-STAT3 signaling axis in breast cancer cells

The CC motif chemokine receptor 1 (CCR1) has been implicated in tumor invasion and metastasis in numerous cancers. However, the detailed mechanism of CCR1 upregulation in metastatic tumor cells is poorly understood. The aim of this study was to clarify the regulatory mechanism underlying transcriptional activation of the CCR1 gene in response to epidermal growth factor (EGF) stimulation in breast cancer cells. CCR1 was highly expressed in human breast invasive ductal carcinoma (IDC) compared to adjacent normal tissues. Upon EGF stimulation, CCR1 expression was upregulated at the transcriptional level. Promoter analysis showed that signal transducer and activator of transcription 3 (STAT3) is necessary for EGF-induced CCR1 promoter activation, and STAT3 silencing abrogated EGF-induced CCR1 transcription. Pharmacological inhibition and short hairpin RNA-mediated knockdown experiments showed that AKT-dependent mammalian target of rapamycin (mTOR) activation was involved in the phosphorylation of serine-727 of STAT3, which in turn stimulated the transcription of the CCR1 gene. In conclusion, the AKT-mTOR-STAT3 signaling axis contributes to EGF-induced CCR1 expression, which promotes invasion and metastasis in breast cancer cells. We propose that the AKT-mTOR-STAT3 axis is a potential therapeutic target for blocking the invasion and metastasis of breast cancers.

α-Pinene inhibits tumor invasion through downregulation of nuclear factor (NF)-κB-regulated matrix metalloproteinase-9 gene expression in MDA-MB-231 human breast cancer cells

Abstract 2,6,6-Trimethylbicyclo[3.1.1]hept-2-ene (α-Pinene) is an organic compound of the terpene class found in the essential oil of many plants. In this study, the inhibitory effect of α-pinene on tumor invasion in highly metastatic MDA-MB-231 human breast cancer cells was evaluated. α-Pinene inhibited tumor necrosis factor (TNF)-α-induced invasiveness of MDA-MB-231 cells as revealed by three-dimensional spheroid invasion assay. Further analysis showed that α-pinene reduced TNFα-induced matrix metalloproteinase-9 gene promoter activation and mRNA expression in a dose-dependent manner. In addition, α-pinene treatment attenuated TNFα-induced nuclear factor κB (NF-κB) activation and NF-κB-dependent transcriptional activity. These results suggest that α-pinene has a significant effect on the inhibition of tumor invasion and may potentially be developed into an anti-metastatic drug.

Erratum to: Anti-invasive effect of β-myrcene, a component of the essential oil from Pinus koraiensis cones, in metastatic MDA-MB-231 human breast cancer cells

The invasive potential of malignant tumor cells is critical for their metastasis. This study was undertaken to evaluate the anti-invasive activity of β-myrcene, a natural compound found in the essential oil from Pinus koraiensis cones (EOPC), in metastatic MDA-MB-231 human breast cancer cells. Among four major constituents that included α-pinene, β-myrcene, 3-carene, and d-limonene, β-myrcene showed the most potent inhibition of tumor necrosis factor-α (TNFα)-induced nuclear factor κB (NF-κB) activity. Pretreatment with β-myrcene suppressed TNFα-induced phosphorylation of inhibitor of κB kinase and NF-κB as well as matrix metalloproteinase-9 (MMP-9) gene expression in a dose-dependent fashion. Furthermore, β-myrcene inhibited TNFα-induced invasion of MDA-MB-231 cells as determined by three-dimensional spheroid invasion assays. These findings suggest that EOPC may promote anti-metastatic activity in breast cancer cells through its downregulation of NF-κB-mediated MMP-9 expression.

Identification of flavonoids from Eriodictyon californicum and their cytotoxicity against HCT116 colon cancer cells

The extract of Eriodictyon californicum has been widely used as an essential emollient, and as an anti-inflammatory, antibacterial, and antifungal agent. In this study, antitumor effects of E. californicum were evaluated against HCT116 human colon cancer cells. Treatment with the ethyl acetate extract of E. californicum (EEC) inhibited the short-term viability and long-term clonogenicity of HCT116 cells. We identified several flavonoids, including rosmarinic acid and luteolin, from the EEC by using high-performance liquid chromatography and nuclear magnetic resonance. Luteolin inhibited clonogenicity, activated caspase-7, and induced apoptosis of HCT116 cells. These findings suggest that EEC contains bioactive flavonoids that exhibit antitumor activities.

Agerarin, identified from Ageratum houstonianum , stimulates circadian CLOCK-mediated aquaporin-3 gene expression in HaCaT keratinocytes

The juice of Ageratum houstonianum is used in folk medicine as an external wound healing aid for skin injuries. However, the active component of A. houstonianum and its mode of action in skin wound healing has not been investigated. This study was conducted to investigate the effect of A. houstonianum ethanolnolic extract (AHE) on the expression of aquaporin-3 (AQP3), an integral membrane protein for water and glycerol transport in keratinocytes, and to identify the structure of the A. houstonianum bioactive compound. Here, we show that AHE increased AQP3 gene expression at the transcriptional level through the p38 MAPK pathway in HaCaT cells. Furthermore, AHE ameliorated suppression of AQP3 expression caused by ultraviolet B (UVB) irradiation. Agerarin (6,7-dimethoxy-2,2-dimethyl-2H-chromene) was identified as the bioactive compound responsible for the up-regulation of AQP3 expression by enhancing the expression of the transcription factor circadian locomotor output cycles kaput (CLOCK). In conclusion, agerarin is a bioactive compound in AHE responsible for CLOCK-mediated AQP3 expression in keratinocytes.

Aurora kinase A inhibitor TCS7010 demonstrates pro‑apoptotic effect through the unfolded protein response pathway in HCT116 colon cancer cells

Aurora kinase A (AURKA) is essential for regulating mitosis and is frequently amplified in various cancer cell types. However, the effect of AURKA inhibition on the induction of apoptosis remains unclear. In the present study, it was reported that treatment with TCS7010, a specific inhibitor of AURKA, resulted in the accumulation of cells in the sub-G0/G1 phase of the cell cycle and increased the percentage of annexin V-binding cells. The cleavage of caspase-2, caspase-7, and poly(ADP-ribose)polymerase (PARP) significantly increased in a time-dependent manner following TCS7010 treatment. In addition, TCS7010 resulted in the production of reactive oxygen species (ROS) and stimulation of the unfolded protein response (UPR), leading to the upregulation of CCAAT/enhancer-binding protein-homologous protein (CHOP), and its downstream target BCL2 like 11 (BIM). Pretreatment with N-acetylcystein, a ROS scavenger, significantly abrogated TCS7010-induced accumulation of CHOP, BIM, cleaved caspase-7 and cleaved PARP. These results suggest that TCS7010 triggers apoptosis through the ROS-mediated UPR signaling pathway.

The chalcone derivative HymnPro generates reactive oxygen species through depletion of intracellular glutathione

Abstract2-Hydroxy-4-methoxy-2′,3′-benzochalcone (HymnPro), a chalcone derivative, induces cell cycle arrest at the G2/M phase followed by caspase-dependent apoptosis. Structurally, HymnPro contains a α-β olefin that can act as a Michael acceptor, and that is involved in the depletion of cellular glutathione. However, the effect of HymnPro on the generation of reactive oxygen species (ROS) is still unknown. In the present study, we observed that treatment of Capan-1 pancreatic cancer cells with HymnPro resulted in a dose-dependent accumulation of ROS, owing to the depletion of intracellular glutathione. Treatment with ROS scavenger N-acetylcycteine prevented HymnPro-induced caspase activation and cell death, but had little effect on G2/M cell cycle arrest and microtubule assembly. Our results suggest that HymnPro causes tubulin binding-mediated cell cycle arrest at the G2/M phase as well as ROS-mediated caspase activation.

A methoxyflavanone derivative, 2′,3′,4′-trimethoxy-5,6-naphthoflavanone, inhibits proliferation of HCT116 human colon cancer cells by inducing G2/M cell cycle arrest and apoptosis

A methoxylated flavanone derivative, 2′,3′,4′-trimethoxy-5,6-naphthoflavanone (TMNF), was synthesized, and its anti-proliferative activity was evaluated. In HCT116 colon cancer cells, TMNF inhibited cellular proliferation and triggered cytotoxicity. A flow cytometry assay showed that TMNF caused cell cycle arrest at the G2/M phase with a concomitant decrease in the population of G1 phase cells. Furthermore, TMNF caused accumulation of p53 and its downstream target, Bax, and stimulated cleavage of caspase-7 and poly(ADP-ribose) polymerase. These data suggest that methoxylated naphthoflavanone can be an attractive pharmacophore for further development of therapeutic adjuvants.

A synthetic naphthochalcone, 2-hydroxy-2,3,4-trimethoxy-5,6-naphthochalcone, triggers caspase-dependent apoptosis in HCT116 human colon cancer cells

A novel synthetic naphthochalcone, 2′-hydroxy-2,3,4-trimethoxy-5′,6′-naphthochalcone (HTN), was evaluated for its antitumor activity. The clonogenicity of both Capan-1 pancreatic and HCT116 colon cancer cells was reduced by HTN treatment. Flow cytometry assay showed that HTN induced cell cycle arrest at the G2/M phase at 24 h of treatment and then accumulated sub-G0/G1 phase population at 48 h post-treatment in HCT116 cells. Furthermore, HTN stimulated the cleavages of caspase-9, caspase-7, and poly(ADP-ribose) polymerase (PARP), suggesting that HTN triggers apoptotic cell death through a mitochondriamediated caspase-dependent pathway. These results suggest that methoxylated naphthochalcone may have a potential as a drug candidate for the treatment of human colon cancer.