Byoungduck Park

Effects of geniposide on hepatocytes undergoing epithelial–mesenchymal transition in hepatic fibrosis by targeting TGFβ/Smad and ERK-MAPK signaling pathways

Liver fibrosis results from increased deposition of type-I collagen within the hepatic extracellular space and constitutes a common cardinal signature in all forms of liver injury, regardless of etiology. Transforming growth factor β1 (TGF-β1) plays a crucial role in the pathogenesis of liver fibrosis. Geniposide is recognized as being useful against hyperlipidemia and fatty liver. However, its cellular mechanism and anti-fibrotic effect in TGF-β1-induced hepatocytes have not been explored. In the present study, we investigated its anti-epithelial-mesenchymal transition (EMT) mechanism by examining the effect of geniposide on TGF-β1-induced hepatocytes. The effect of geniposide on TGF-β1-induced AML12 cells was assessed using Western blotting, quantitative real-time PCR, immunofluorescence staining and DNA binding activity. We found that geniposide significantly inhibited TGF-β1-induced mRNA and protein expression of type-I collagen. Cells treated concurrently with TGF-β1 and geniposide retained high levels of localized E-cadherin expression with no increase in vimentin. Treatment with geniposide almost completely blocked the phosphorylation of Smad2/3, extracellular signal-regulated kinase (ERK) and Akt in AML12 cells. Taken together, these results suggest that geniposide may suppress TGF-β1-induced EMT in hepatic fibrosis by inhibiting the TGFβ/Smad and ERK-mitogen-activated protein kinase (MAPK) signaling pathways. Our results may help researchers better understand the pathogenesis of liver fibrosis so they can develop novel therapeutic strategies for treatment of liver diseases.

Triptolide, a diterpene, inhibits osteoclastogenesis, induced by RANKL signaling and human cancer cells.

Most bone-related diseases are characterized by excessive bone resorption by osteoclasts. Receptor activator of nuclear factor-kappa B (NF-κB) ligand (RANKL) has emerged as a major mediator of bone resorption, commonly associated with cancer and chronic inflammatory diseases. Thus inhibitors of RANKL signaling have a potential in preventing bone loss. In the present study, we investigated the ability of triptolide, a diterpenoid isolated from Thunder of God Vine, to inhibit signaling by receptor activator of NF-κB (RANK) and its ligand (RANKL) and to modulate osteoclastogenesis induced by RANKL and human cancer cells. We found that triptolide suppressed RANKL-induced differentiation of precursor cells to osteoclasts, and also inhibited osteoclast formation induced by human breast tumor cells (MDA-MB-231), multiple myeloma cells (U266) and prostate tumor cells (PC-3). Triptolide inhibited RANKL-induced NF-κB activation in osteoclast precursor cells by inhibiting IκBα kinase activation, IκBα phosphorylation, and IκBα degradation. Our results suggest that triptolide effectively inhibits RANKL-induced NF-κB activation and RANKL- and tumor cell-induced osteoclastogenesis. This warrants further study of triptolide as a potential therapy for osteoporosis and cancer-associated bone loss.

Suppression of Th2 chemokines by crocin via blocking of ERK‐MAPK/NF‐κB/STAT1 signalling pathways in TNF‐α/IFN‐γ‐stimulated human epidermal keratinocytes

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Pomolic Acid Inhibits Invasion of Breast Cancer Cells Through the Suppression of CXC Chemokine Receptor Type 4 Expression.

High mortality of cancer‐mediated deaths is due to metastasis. CXC chemokine receptor type 4 (CXCR4) signaling has been demonstrated to be involved in migration of breast cancer. Thus, identification of CXCR4 inhibitor has been challenged constantly as an anticancer drug. This study is aimed to investigate the CXCR4 inhibitor that could inhibit tumor metastasis from natural products. We demonstrated that pomolic acid (PA), a component of Euscaphis japonica, could downregulate CXCR4 expression in breast cancer cells. Treatment with proteasomal and lysosomal inhibitors did not show significant effects on PAs ability. When we further explored the molecular mechanism, suppression of CXCR4 occurred at transcriptional level and was correlated with inhibition of nuclear factor‐kappaB (NF‐κB) activation. Downregulation of CXCR4 by PA was accompanied by the inhibition of CXC motif chemokine 12 (CXCL12)‐induced invasion of breast cancer cells. Overall, our results indicate that PA, as a novel inhibitor of CXCR4, can be a promising therapeutic agent for treatment of cancer metastasis. J. Cell. Biochem. 117: 1296–1307, 2016.

Phosphorylation of Smac by Akt promotes the caspase‐3 activation during etoposide‐induced apoptosis in HeLa cells

The Akt, family of serine/threonine protein kinases functions as key regulators of multiple aspects of cell behavior, such as survival, proliferation, migration, and carcinogenesis. Notably, Akt exerts its anti‐apoptotic effects through the phosphorylation of numerous substrates related with cell cycle, genome stability, and cancer development. In this report, nevertheless, we focused our view on the novel role of Akt which involves in a pro‐apoptotic action by phosphorylating second mitochondria derived activator of caspases (Smac) protein during etoposide‐induced apoptotic processes. Our data reveals that Akt could bind to and phosphorylate Smac at serine residue 67, which enhances the ability of Smac to interact with the cytosolic X‐chromosome linked IAP (XIAP) protein. The cellular interaction of wild‐type Smac with XIAP was enhanced with similar activation kinetics of Akt activity, while this interaction was markedly attenuated in cells expressing the phosphorylation‐defective mutant S67A‐Smac during etoposide‐induced apoptosis. Moreover, we provide the evidence indicating that the phosphorylation of Smac at ser‐67 markedly upregulates the caspase‐3 activity by promoting the interaction of Smac with XIAP. Taken together, we propose that the phosphorylation of Smac by Akt might be a novel mechanism that involves in amplification of caspase cascade pathway during etoposide‐induced apoptosis in HeLa cells.

Carnosic acid induces apoptosis through inactivation of Src/STAT3 signaling pathway in human renal carcinoma Caki cells

Carnosic acid (CA), the major bioactive compound of Rosmarinus officinalis L., has been reported to possess anti-inflammatory and anticancer activities. However, the molecular mechanisms underlying the anticancer effects of CA remain poorly understood. In the present study, we investigated that CA significantly reduced the viability of human renal carcinoma Caki cells. CA-induced apoptosis was connected with the cleavage of caspase-9, -7 and -3, and that of PARP. Moreover, CA increased the expression of pro-apoptotic protein Bax and diminished the expression of anti-apoptotic protein Bcl-2 and Bcl-xL, thereby releasing cytochrome c into the cytosol. Treatment with CA in Caki cells also induced the expression of p53 and its target gene product, p27, through down-regulation of Murine double minute-2 (Mdm2). Furthermore, CA generated reactive oxygen species (ROS), and pretreatment with ROS scavenger N-acetyl cysteine (NAC) abrogated CA-induced cleavage of PARP and expression of p53. One of the key oncogenic signals is mediated through signal transducer and activator of transcription-3 (STAT3), which promotes abnormal cell proliferation. Incubation of cells with CA markedly diminished the phosphorylation of STAT3 and its upstream, Src, and reduced the expression of STAT3 responsive gene products, such as D-series of cyclins and survivin. Taken together, the present study revealed that CA induced apoptosis in Caki cells by induction of p53 and suppression of STAT3 signaling.

Asiatic acid attenuates methamphetamine-induced neuroinflammation and neurotoxicity through blocking of NF-kB/STAT3/ERK and mitochondria-mediated apoptosis pathway

BackgroundMethamphetamine (METH) is a commonly abused drug that may result in neurotoxic effects. Recent studies have suggested that involvement of neuroinflammatory processes in brain dysfunction is induced by misuse of this drug. However, the mechanism underlying METH-induced inflammation and neurotoxicity in neurons is still unclear. In this study, we investigated whether asiatic acid (AA) effected METH-mediated neuroinflammation and neurotoxicity in dopaminergic neuronal cells. And we further determined whether the effect involved in the nuclear factor kappa-light-chain-enhancer of activated B cells (NF-κB) and signal transducer and activator of transcription (STAT)3 and extracellular signal-regulated kinase (ERK) pathway.MethodsWe used the human dopaminergic neuroblastoma SH-SY5Y cell line, murine microglial BV2 cell line, and primary culture of rat embryo mesencephalic neurons. Pro-inflammatory cytokine production was monitored by ELISA and RT/real-time PCR. The cell cycle distribution and mitochondrial membrane integrity was analyzed by flow cytometry. We used immunoblotting, DNA-binding activity, and immunofluorescence staining to analyze the effect of AA on activation of the NF-κB, STAT3, MAPK-ERK, and apoptosis signaling pathways.ResultsMETH induced TNF receptor (TNFR) expression and led to morphological changes of cells. Additionally, this drug increased pro-inflammatory cytokine (TNFα and IL-6) expression. AA significantly suppressed METH-induced TNFR expression in concentration dependent. Increased secretion of TNFα and IL-6 was inhibited in METH-stimulated neuronal cells by AA administration. AA showed significant protection against METH-induced translocation of NF-κB/STAT3 and ERK phosphorylation. AA inhibited METH-induced proteolytic fragmentation of caspase-3 and PARP. The pro-apoptotic protein Bax was significantly decreased, while the anti-apoptotic protein Bcl-xL was increased by AA treatment in METH-stimulated cells. A similar protective effect of AA on mitochondrial membrane integrity was also confirmed by flow cytometry and immunofluorescence staining.ConclusionsBased on the literatures and our findings, AA is a promising candidate for an anti-neurotoxic agent, and it can potentially be used for the prevention and treatment of various neurological disorders.

SB365, Pulsatilla saponin D, suppresses the growth of gefitinib-resistant NSCLC cells with Met amplification

Clinical treatment using epidermal growth factor receptor-tyrosine kinase inhibitors (EGFR-TKIs) such as gefitinib or erlotinib has been applied in patients with non-small cell lung cancers (NSCLCs). Unfortunately, acquired drug resistance emerges in these patients due to the amplification of the Met proto-oncogene, which may be a compensatory mechanism of NSCLCs against EGFR inhibition. To overcome this resistance, identification of new small-molecule natural compounds is crucial for cancer therapeutics. In this regard, SB365, saponin D from the root of Pulsatilla koreana which has been used as a traditional medicine in Korea for several diseases, has attracted wide interest. In the present study, SB365 effectively suppressed the proliferation of gefitinib-resistant HCC827GR NSCLC cells with Met amplification. Notably, our data revealed that SB365 inhibited the phosphorylation of Met and the downstream signaling pathway required for growth and survival in the Met-amplified HCC827GR cells. Moreover, SB365 suppressed the anchorage-independent growth, migration and invasion along with induction of apoptosis in the HCC827GR cells. Therefore, these results suggest that SB365 is good candidate as a natural product for use in the treatment of Met-amplified NSCLCs.

Ascochlorin suppresses MMP-2-mediated migration and invasion by targeting FAK and JAK-STAT signaling cascades†

Human glioblastomas express higher levels of matrix metalloprotease‐2 (MMP‐2) than low‐grade brain tumors and normal brain tissues. Ascochlorin (ASC) has anti‐metastatic, anti‐angiogenic, and synergistic effect in various types of cancer cells. However, it remains unknown whether ASC can affect cell migration and invasion in malignant human glioma cells. In this study, we found that ASC indeed inhibits cell migration and invasion in U373MG and A172. ASC significantly suppresses the MMP‐2 gelatinolytic activity and expression in U373MG and A172. To determine the molecular mechanism by which ASC suppressed cell migration and invasion, we investigated whether ASC could modulate metastasis via focal adhesion kinase (FAK) and janus kinase (JAK)/signal transducer and activator of transcription (STAT) signaling, a potential drug target. ASC strongly inhibits the phosphorylation of FAK, and treatment with a FAK inhibitor significantly suppresses cancer cell migration in the presence of ASC. In addition, ASC significantly decreased phosphorylation of JAK2/STAT3, cancer cell migration and nuclear translocation of STAT3. Taken together, these results suggest that ASC inhibits cell migration and invasion by blocking FAK and JAK/STAT signaling, resulting in reduced MMP‐2 activity. J. Cell. Biochem. 119: 300–313, 2018.

Hispolon from Phellinus linteus induces apoptosis and sensitizes human cancer cells to the tumor necrosis factor-related apoptosis-inducing ligand through upregulation of death receptors.

The tumor necrosis factor-related apoptosis-inducing ligand (TRAIL) is a potent anticancer agent possessing the ability to induce apoptosis in various cancer cells but not in non‑malignant cells. However, certain type of cancer cells are resistant to TRAIL‑induced apoptosis and some acquire resistance after the first treatment. So development of an agent that can reduce or avoid resistance in TRAIL‑induced apoptosis has garnered significant attention. The present study evaluated the anticancer potential of hispolon in TRAIL‑induced apoptosis and indicated hispolon can sensitize cancer cells to TRAIL. As the mechanism of action was examined, hispolon was found to activate caspase‑3, caspase‑8 and caspase‑9, while downregulating the expression of cell survival proteins such as cFLIP, Bcl‑2 and Bcl‑xL and upregulating the expression of Bax and truncated Bid. We also found hispolon induced death receptors in a non‑cell type‑specific manner. Upregulation of death receptors by hispolon was found to be p53-independent but linked to the induction of CAAT enhancer binding protein homologous protein (CHOP). Overall, hispolon was demonstrated to potentiate the apoptotic effects of TRAIL through downregulation of anti‑apoptotic proteins and upregulation of death receptors linked with CHOP and pERK elevation.