Baicalein inhibits the invasion and metastatic capabilities of hepatocellular carcinoma cells via down-regulation of the ERK pathway. PLoS One. 2013;8:e72927. [PMID: 24039823 PMCID: PMC3765161 DOI: 10.1371/journal.pone.0072927]

Suppression of the TGF-β/Smad signaling pathway and inhibition of hepatic stellate cell proliferation play a role in the hepatoprotective effects of curcumin against alcohol-induced hepatic fibrosis

The hepatoprotective effects of curcumin against alcohol-induced hepatic fibrosis have rarely been discussed and its mechanisms of action in alcohol-induced liver disease remain unknown. In this study, serum alkaline phosphatase (ALP), aspartate aminotransferase (AST) and alanine aminotransferase (ALT) levels were measured to assess hepatic function; histopathological and immunohistochemical observations were used to evaluate pathological and specific molecular changes in liver tissue and flow cytometry was used to detect the apoptosis in cultured hepatic stellate cells (HSCs), the major fibrogenic cells in the liver; PCR and western blot analysis were employed to evaluate the changes in the expression of molecules and signaling pathways. We demonstrate that curcumin alleviates alcohol-induced hepatic fibrosis by affecting the HSCs. We found that the administration of curcumin inhibited alcohol-induced HSC proliferation and even induced HSC apoptosis by stimulating endoplasmic reticulum (ER) stress. We also found that by suppressing the transforming growth factor-β (TGF-β)/Smad signaling pathway, the administration of curcumin impaired the production of extracellular matrix proteins in alcohol-stimulated HSCs. These results indicate that curcumin exerts its hepatoprotective effects against alcohol-induced hepatic fibrosis by inhibiting the proliferation and inducing the apoptosis of HSCs by stimulating ER stress and deactivating HSCs by suppressing the TGF-β/Smad signaling pathway.

Interleukin 17A promotes gastric cancer invasiveness via NF-κB mediated matrix metalloproteinases 2 and 9 expression

Interleukin 17A (IL-17A), as a pro-inflammatory cytokine, is involved in pathology of inflammatory diseases and tumor microenvironment. The aim of this study is to investigate the effect of IL-17A on the invasiveness of gastric cancer (GC). In the study, we found that IL-17A could promote the migration and invasion of GC cells. Furthermore, after treated with IL-17A, the expressions and activities of matrix metalloproteinase 2 (MMP-2) and MMP-9 were upregulated, while the expressions of TIMP-1 and TIMP-2 were downregulated. Moreover, the nuclear/overall fractions of p65 and p50 were dramatically elevated by IL-17A. Pretreatment with helenalin, a nuclear factor-κB (NF-κB) inhibitor, was proved to abolish the promoting effect of IL-17A on the invasion ability of GC cells and upregulation of MMP-2 and MMP-9. In conclusion, our findings illustrated that IL-17A could promote the invasion of GC cells by activating NF-κB pathway, and subsequently upregulating the expression of MMP-2 and MMP-9. These results may lead to the identification of new diagnostic markers and therapeutic targets of GC.

Baicalein induces apoptosis and autophagy via endoplasmic reticulum stress in hepatocellular carcinoma cells

BACKGROUND

Hepatocellular carcinoma (HCC) remains a disastrous disease and the treatment for HCC is rather limited. Separation and identification of active compounds from traditionally used herbs in HCC treatment may shed light on novel therapeutic drugs for HCC.

METHODS

Cell viability and colony forming assay were conducted to determine anti-HCC activity. Morphology of cells and activity of caspases were analyzed. Antiapoptotic Bcl-2 family proteins and JNK were also examined. Levels of unfolded protein response (UPR) markers were determined and intracellular calcium was assayed. Small interfering RNAs (siRNAs) were used to investigate the role of UPR and autophagy in baicalein-induced cell death.

RESULTS

Among four studied flavonoids, only baicalein exhibited satisfactory inhibition of viability and colony formation of HCC cells within water-soluble concentration. Baicalein induced apoptosis via endoplasmic reticulum (ER) stress, possibly by downregulating prosurvival Bcl-2 family, increasing intracellular calcium, and activating JNK. CHOP was the executor of cell death during baicalein-induced ER stress while eIF2 α and IRE1 α played protective roles. Protective autophagy was also triggered by baicalein in HCC cells.

CONCLUSION

Baicalein exhibits prominent anti-HCC activity. This flavonoid induces apoptosis and protective autophagy via ER stress. Combination of baicalein and autophagy inhibitors may represent a promising therapy against HCC.

Baicalein ameliorates inflammatory-related apoptotic and catabolic phenotypes in human chondrocytes

Osteoarthritis (OA), characterized by progressive destruction of articular cartilage, is the most common form of human arthritis and a major concern for aging societies worldwide. In OA, pro-inflammatory cytokines such as interleukin (IL)-1β and tumor necrosis factor (TNF)-α can trigger the caspase cascade to promote apoptosis and activate NF-κB to induce catabolic factors in chondrocytes. Here, the anti-apoptotic and anti-catabolic effects of baicalein on human OA chondrocytes treated by a mixture of IL-1β and TNF-α (IT) were investigated in vitro. In cultured chondrocytes, baicalein pretreatment attenuated apoptosis in a concentration-dependent manner in response to IT stimulation. Mechanistically, the anti-apoptotic effects of baicalein result from inhibition of nitric oxide production and downstream caspase signaling pathway. Moreover, administration of baicalein significantly reduced matrix metalloproteinase (MMP) 3 and MMP13 secretion in chondrocytes stimulated with IT. The anti-catabolic effects of baicalein were further demonstrated by the recovery of the glycosaminoglycan and type II collagen (COLII) deposition by histological analysis in IT-treated mouse articular cartilage explants. These findings suggest that baicalein might be a promising novel therapeutic agent for OA by virtue of its suppression of apoptosis and MMP secretion in OA chondrocytes.

Baicalein reduces the invasion of glioma cells via reducing the activity of p38 signaling pathway

Baicalein, one of the major flavonids in Scutellaria baicalensis, has historically been used in anti-inflammatory and anti-cancer therapies. However, the anti-metastatic effect and related mechanism(s) in glioma are still unclear. In this study, we thus utilized glioma cell lines U87MG and U251MG to explore the effect of baicalein. We found that administration of baicalein significantly inhibited migration and invasion of glioma cells. In addition, after treating with baicalein for 24 h, there was a decrease in the levels of matrix metalloproteinase-2 (MMP-2) and MMP-9 expression as well as proteinase activity in glioma cells. Conversely, the expression of tissue inhibitor of metalloproteinase-1 (TIMP-1) and TIMP-2 was increased in a dose-dependent manner. Moreover, baicalein treatment significantly decreased the phosphorylated level of p38, but not ERK1/2, JNK1/2 and PI3K/Akt. Combined treatment with a p38 inhibitor (SB203580) and baicalein resulted in the synergistic reduction of MMP-2 and MMP-9 expression and then increase of TIMP-1 and TIMP-2 expression; and the invasive capabilities of U87MG cells were also inhibited. However, p38 chemical activator (anisomycin) could block these effects produced by baicalein, suggesting baicalein directly downregulate the p38 signaling pathway. In conclusion, baicalein inhibits glioma cells invasion and metastasis by reducing cell motility and migration via suppression of p38 signaling pathway, suggesting that baicalein is a potential therapeutic agent for glioma.

Luteoloside suppresses proliferation and metastasis of hepatocellular carcinoma cells by inhibition of NLRP3 inflammasome

The inflammasome is a multi-protein complex which when activated regulates caspase-1 activation and IL-1β secretion. Inflammasome activation is mediated by NLR proteins that respond to stimuli. Among NLRs, NLRP3 senses the widest array of stimuli. NLRP3 inflammasome plays an important role in the development of many cancer types. However, Whether NLRP3 inflammasome plays an important role in the process of hepatocellular carcinoma (HCC) is still unknown. Here, the anticancer effect of luteoloside, a naturally occurring flavonoid isolated from the medicinal plant Gentiana macrophylla, against HCC cells and the underlying mechanisms were investigated. Luteoloside significantly inhibited the proliferation of HCC cells in vitro and in vivo. Live-cell imaging and transwell assays showed that the migration and invasive capacities of HCC cells, which were treated with luteoloside, were significantly inhibited compared with the control cells. The inhibitory effect of luteoloside on metastasis was also observed in vivo in male BALB/c-nu/nu mouse lung metastasis model. Further studies showed that luteoloside could significantly reduce the intracellular reactive oxygen species (ROS) accumulation. The decreased levels of ROS induced by luteoloside was accompanied by decrease in expression of NLRP3 inflammasome resulting in decrease in proteolytic cleavage of caspase-1. Inactivation of caspase-1 by luteoloside resulted in inhibition of IL-1β. Thus, luteoloside exerts its inhibitory effect on proliferation, invasion and metastasis of HCC cells through inhibition of NLRP3 inflammasome. Our results indicate that luteoloside can be a potential therapeutic agent not only as an adjuvant therapy for HCC, but also, in the control and prevention of metastatic HCC.

Induction of apoptosis by total flavonoids from Scutellaria barbata D. Don in human hepatocarcinoma MHCC97-H cells via the mitochondrial pathway

Scutellaria barbata D. Don, a traditional Chinese medicine, reportedly possesses antitumor activity against a variety of tumors. In the present study, we investigated the cytotoxic effect of total flavonoids from S. barbata (TF-SB) on human hepatocarcinoma cells and the underlying molecular mechanisms regarding the effect were explored. TF-SB treatment significantly reduced the cell viability of human HCC MHCC97-H cells in a dose-dependent manner. Further flow cytometric analysis showed that the apoptosis rate of MHCC97-H cells increased and the mitochondrial membrane potential (∆ψm) of MHCC97-H cells decreased after TF-SB treatment. DNA ladder showed that TF-SB induced a significant increase in DNA fragmentation in MHCC97-H cells. Reverse transcription PCR and Western blot analysis revealed that the expression levels of Smac, Apaf-1, Cytochrome c, Caspase-9, and Caspase-3 were upregulated in a dose-dependent manner and after treatment with different concentrations of TF-SB for 48 h. These results suggest that TF-SB induces apoptosis in MHCC97-H cells through the mitochondrial pathway.