Hispidulin induces ER stress-mediated apoptosis in human hepatocellular carcinoma cells in vitro and in vivo by activating AMPK signaling pathway.

Hispidulin (4',5,7-trihydroxy-6-methoxyflavone) is a phenolic flavonoid isolated from the medicinal plant S. involucrata, which exhibits anti-neoplastic activity against several types of cancer. However, the mechanism underlying its anti-cancer activity against hepatocellular carcinoma (HCC) has not been fully elucidated. In this study, we investigated whether and how hispidulin-induced apoptosis of human HCC cells in vitro and in vivo. We showed that hispidulin (10, 20 µmol/L) dose-dependently inhibited cell growth and promoted apoptosis through mitochondrial apoptosis pathway in human HCC SMMC7721 cells and Huh7 cells. More importantly, we revealed that its pro-apoptotic effects depended on endoplasmic reticulum stress (ERS) and unfolded protein response (UPR), as pretreatment with salubrinal, a selective ERS inhibitor, or shRNA targeting a UPR protein CHOP effectively abrogated hispidulin-induced cell apoptosis. Furthermore, we showed that hispidulin-induced apoptosis was mediated by activation of AMPK/mTOR signaling pathway as pretreatment with Compound C, an AMPK inhibitor, or AMPK-targeting siRNA reversed the pro-apoptotic effect of hispidulin. In HCC xenograft nude mice, administration of hispidulin (25, 50 mg/kg every day, ip, for 27 days) dose-dependently suppressed the tumor growth, accompanied by inducing ERS and apoptosis in tumor tissue. Taken together, our results demonstrate that hispidulin induces ERS-mediated apoptosis in HCC cells via activating the AMPK/mTOR pathway. This study provides new insights into the anti-tumor activity of hispidulin in HCC.

Hispidulin mediates apoptosis in human renal cell carcinoma by inducing ceramide accumulation.

Hispidulin, a polyphenolic flavonoid extracted from the traditional Chinese medicinal plant S involucrata, exhibits anti-tumor effects in a wide array of human cancer cells, mainly through growth inhibition, apoptosis induction and cell cycle arrest. However, its precise anticancer mechanisms remain unclear. In this study, we investigated the molecular mechanisms that contribute to hispidulin-induced apoptosis of human clear-cell renal cell carcinoma (ccRCC) lines Caki-2 and ACHN. Hispidulin (10, 20 µmol/L) decreased the viability of ccRCC cells in dose- and time-dependent manners without affecting that of normal tubular epithelial cells. Moreover, hispidulin treatment dose-dependently increased the levels of cleaved caspase-8 and caspase-9, but the inhibitors of caspase-8 and caspase-9 only partly abrogated hispidulin-induced apoptosis, suggesting that hispidulin triggered apoptosis via both extrinsic and intrinsic pathways. Moreover, hispidulin treatment significantly inhibited the activity of sphingosine kinase 1 (SphK1) and consequently promoted ceramide accumulation, thus leading to apoptosis of the cancer cells, whereas pretreatment with K6PC-5, an activator of SphK1, or overexpression of SphK1 significantly attenuated the anti-proliferative and pro-apoptotic effects of hispidulin. In addition, hispidulin treatment dose-dependently activated ROS/JNK signaling and led to cell apoptosis. We further demonstrated in Caki-2 xenograft nude mice that injection of hispidulin (20, 40 mg·kg-1·d-1, ip) dose-dependently suppressed tumor growth accompanied by decreased SphK1 activity and increased ceramide accumulation in tumor tissues. Our findings reveal a new explanation for the anti-tumor mechanisms of hispidulin, and suggest that SphK1 and ceramide may serve as potential therapeutic targets for the treatment of ccRCC.

Physcion inhibits the metastatic potential of human colorectal cancer SW620 cells in vitro by suppressing the transcription factor SOX2.

AIM: Physcion, an anthraquinone derivative, exhibits hepatoprotective, anti-inflammatory, anti-microbial and anti-cancer activities. In this study we examined whether and how physcion inhibited metastatic potential of human colorectal cancer cells in vitro. METHODS: Human colorectal cancer cell line SW620 was tested. Cell migration and invasion were assessed using a wound healing and Transwell assay, respectively. The expression levels of transcription factor SOX2 in the cells were modulated with shRNA targeting SOX2 and SOX2 overexpressing plasmid. The expression of target molecules involved in epithelial-mesenchymal transition (EMT) process and the signaling pathways was determined with Western blots or qRT-PCR. ROS levels were measured using DCF-DA. RESULTS: Physcion (2.5, 5 mol/L) did not affect the cell viability, but dose-dependently inhibited the cell adhesion, migration and invasion. Physcion also inhibited the EMT process in the cells, as evidenced by the increased epithelial marker E-cadherin expression, and by decreased expression of mesenchymal markers N-cadherin, vimentin, fibronectin and α-SMA, as well as transcriptional repressors Snail, Slug and Twist. Physcion suppressed the expression of SOX2, whereas overexpression of SOX2 abrogated the inhibition of physcion on metastatic behaviors. Physcion markedly increased ROS production and phosphorylation of AMPK and GSK3ß in the cells, whereas the AMPK inhibitor compound C or the ROS inhibitor NAC abolished the inhibition of physcion on metastatic behaviors. CONCLUSION: Physcion inhibits the metastatic potential of human colorectal cancer cells in vitro via activating ROS/AMPK/GSK3ß signaling pathways and suppressing SOX2.

Effects of Ginkgo biloba extract EGb761 on human colon adenocarcinoma cells.

AIMS: To investigate the effect of Ginkgo biloba extract (EGb761) on cell proliferation and apoptosis in human colon cancer cells. METHODS: Human colon cancer cell lines (HT-29) were cultured and incubated with various concentrations (0-320 mg/l) of EGb 761 solution for up to 72 h. Cell viability, cell apoptosis, cell cycle, expression of caspase-3, the mRNA levels of p53, and Bcl-2 were assessed. RESULTS: EGb 761 inhibited the growth of HT-29 cells in a time-dose-dependent manner. At 80 and 320 mg/L, EGb 761 increased the number of cells in the G0/G1 phase and reduced cells in the G2/M and S phase. EGb 761 treatment also increased the apoptosis ratio of the HT-29 cells. EGb 761 treatment was associated with an increase in caspase-3 activities, reduction in bcl-2 mRNA expression and elevation in p53 mRNA expression. CONCLUSION: EGb 761 inhibits the progression of human colon cancer cells. Its therapeutic effect may be related to enhanced caspase-3 activities, up-regulation of p53 and down-regulation of bcl-2 genes.

Purple sweet potato pigments scavenge ROS, reduce p53 and modulate Bcl-2/Bax to inhibit irradiation-induced apoptosis in murine thymocytes.

AIMS: Purple sweet potato (PSP) pigments were proved to protect murine thymocytes from (60)Co γ-ray-induced mitochondria-mediated apoptosis in our previous study. In this study, we further investigated the effect of PSP pigments on apoptosis related ROS, p53 and Bcl-2 family. METHODS: Cell viability was analyzed by MTT. Apoptosis was certified by DNA ladder detection. Reactive oxygen species (ROS) were detected using 2',7',- dichlorofluorescein diacetate (DCFH-DA) probe. P53, Bcl-2 and Bax proteins were analyzed by western blot. The activities of caspase-3 and caspase-9 were determined by fluorogenic substrates detection. RESULTS: PSP pigments treatment prior to 4Gy (60)Co γ-ray irradiation increased the cell viability and decrease the apoptosis. In the presence of PSP pigments, ROS was scavenged and followed by a p53-depression. A shift in Bcl-2/Bax ratio towards anti-apoptosis was observed as a result of p53-depression. The activities of caspase-9 and caspase-3 were reduced by PSP pigments pretreatment. CONCLUSIONS: PSP pigments have a cytoprotective activity against γ radiation. The protective effect of PSP pigments may be involving ROS scavenging, p53 depression and Bcl-2/Bax modulation in a caspase-dependent mitochondrial way.

Cytotoxicity of natural extract from Tegillarca granosa on ovarian cancer cells is mediated by multiple molecules.

PURPOSE: To determine the cellular and molecular mechanism of cytotoxicity induced by Haishengsu (HSS), nature extract from Tegillarca granosa, toward human ovarian cancer cell lines SKOV-3 and OVCAR-3. METHODS: The cytotoxic effects of HSS on two ovarian cancer cell lines were tested by XTT assay. Cell apoptosis and cell cycle arrest induced by HSS were demonstrated by DNA ladder assay and flow cytometric analysis, respectively. RT-PCR or flow cytometric analysis was used to investigate the expression of bcl-2, caspase-3, p53, beta-catenin, E-cadherin, CD24, and CD44. RESULTS: Continuous exposure to HSS for 48 h produced cytotoxic effects on both cell lines in a concentration dependent manner, which was accompanied by apoptosis and cell cycle arrest. Apoptosis associated gene bcl-2 and caspase-3, tumor metastasis associated gene ?-catenin, but not E-cadherin, and CD24, but not CD44, were involved in the effect of growth inhibition induced by HSS. Although p53 mediated apoptosis induced by HSS in OVCAR-3 cells, it was not required in SKOV-3 cells. CONCLUSION: HSS has a potential cytotoxic effect on human ovarian cancer cells, which was mediated by multiple signal molecules including bcl-2, caspase-3, beta-catenin, and CD24. These findings will provide a theoretical basis for HSS's potential clinical application as a novel marine anti-cancer agent.

Combined enzymatic hydrolysis and selective fermentation for green production of alginate oligosaccharides from Laminaria japonica.

Alginate oligosaccharides (AOS) showed various biological activities. Traditional protocol for producing AOS was a multiple-step and high-pollution procedure. In this study, a rapid and efficient AOS producing method was developed directly from Laminaria japonica. Natural sun-dried L. japonica with a feed ratio of 1:7 (w/v) was pretreated using cellulase with a dry weight of 3%, for releasing the fermentable sugars (8.5 g/L glucose and 15.2 g/L mannitol). Then, the engineered yeast Yarrowia lipolytica strain with alginate lyase activity was grown using an algae-based medium. After fermentation for 72 h, glucose and mannitol were completely consumed, and 71.8 mM AOS was extracted from the fermentation supernatant. The degree of polymerization (DP) was ranging from 2 to 3. The recovery yield of AOS was about 91.7%. The purity of the extracted AOS was 92.6%. Overall, our work provided new insights for the development of green biotechnologies for oligosaccharide production from seaweed.

Tegillarca granosa extract Haishengsu inhibits tumor activity via a mitochondrial­mediated apoptotic pathway.

Haishengsu (HSS) is an active natural extract isolated from Tegillarca granosa, which has previously been demonstrated to inhibit the proliferation of several types of cancer cells in vitro. Our previous study indicated that HSS may induce apoptosis to suppress growth of human hepatocellular carcinoma BEL­7402 cells by activating Fas pathway. The present study demonstrated that HSS treatment induces the in vitro apoptosis of BEL­7402 cells via the mitochondrial­mediated apoptotic pathway detected by DNA fragmentation assay, caspase activity assay and transmission electron microscopy assay, and inhibits tumor xenograft growth in vivo. Alterations in apoptotic regulatory proteins were detected, including decreased expression of B­cell lymphoma2 (Bcl­2), upregulation of Bcl­2­associated X protein and mitochondrial cytochrome c release, and downstream activation of apoptotic signaling. Furthermore, apoptotic induction was caspase­dependent, as indicated by cleavage of the caspase substrate, poly (ADP­ribose) polymerase. Oral administration of 62.5­250 mg/kg HSS markedly educed the growth of hepatocellular carcinoma tumor xenografts in nude mice. In addition, immunohistochemical staining for caspase­3 protein and transmission electron microscopy further indicated the induction of apoptosis in these tumor tissues. Taken together, the present study demonstrated that HSS may effectively induce apoptosis to suppress the growth of BEL­7402 cells in vitro and in vivo, and therefore may hold promise for further development as a novel cancer therapy.

Hispidulin inhibits hepatocellular carcinoma growth and metastasis through AMPK and ERK signaling mediated activation of PPARγ.

Hispidulin, a phenolic flavonoid, exerts potent cytotoxicity towards a variety of human cancers. However, the effects of hispidulin on hepatocellular carcinoma (HCC) and underlying molecular mechanisms of its action remain elusive. The present study investigated the effect of hispidulin on HCC in experimental models, including tumor cell lines and mouse tumor xenograft. Results demonstrated that hispidulin was cytotoxic and anti-proliferative to HCC cell lines (SMMC7721 and Bel7402). Hispidulin activated caspase-3 and triggered apoptosis in HCC cells. Moreover, hispidulin inhibited cell migration and invasion by inhibiting the expression of matrix metalloproteinases (MMP-2, MMP-9) and by inducing tissue inhibitor of metalloproteinase-3 (TIMP-3) expression. Hispidulin activated peroxisome proliferator-activated receptor γ (PPARγ) signaling which mainly contributed to its cytotoxicity in HCC cells. Remarkably, GW9662 (a PPARγ inhibitor) or PPARγ targeting siRNA significantly abrogated the anti-proliferative, pro-apoptotic, and anti-metastatic effects of hispidulin in HCC cells. Furthermore, hispidulin induced activation of PPARγ which was associated with increased phosphorylation of AMPK, ERK, JNK in HCC cells. Compound C (an AMPK inhibitor) or PD98059 (a MEK inhibitor) partly reversed the effects of hispidulin on PPARγ signaling in HCC cells. In contrast, no significant changes in PPARγ signaling were observed in HCC cells pretreated with SP600125 (a JNK inhibitor), while SP6000125 significantly inhibited the anti-cancer effects of hispidulin in HCC cells. Hispidulin administration effectively suppressed Bel7402 xenograft tumor growth and lung metastasis in vivo. Our findings indicate that PPARγ activation by hispidulin effectively suppressed HCC cell growth and metastasis both in vitro and in vivo.

Hispidulin suppresses tumor growth and metastasis in renal cell carcinoma by modulating ceramide-sphingosine 1-phosphate rheostat.

Sphingosine 1-phosphate (S1P) rheostat is considered as a key signal that determines cell fate. This study aimed to report that hispidulin, a polyphenolic flavonoid, exerted anti-growth and anti-metastasis effects against renal cell carcinoma (RCC) by modulating the balance of ceramide-S1P. In vitro studies showed that hispidulin could effectively inhibit cell proliferation, cell migration, cell invasion, and epithelial-mesenchymal transition, and promote cell apoptosis in Caki-2 and A498 cell lines. Moreover, it also increased the ceramide/S1P ratio. Consistent with the in vitro findings, the efficacy of hispidulin in vivo showed that it effectively suppressed tumor growth and lung metastasis. Furthermore, the results revealed that hispidulin significantly suppressed the activity of sphingosine kinase 1 (Sphk1) in RCC cells; however, no significant change was observed in the mRNA or protein expression of Sphk1. The overexpression of Sphk1 could significantly abrogate the anti-growth and anti-metastasis effects of hispidulin, whereas the siRNA-targeting Sphk1 or Sphk1 inhibitor was able to augment the anticancer effects of hispidulin against RCC. Moreover, hispidulin interfered with the phosphorylation and translocation of Sphk1, leading to inhibitory effects of Sphk1 activity. In summary, the findings suggested that hispidulin suppressed tumor growth and metastasis by inhibiting the Sphk1 activity and consequently modulating ceramide-S1P rheostat. It also presented a new explanation for the antitumor mechanisms of hispidulin against RCC.

Purple sweet potato pigments protect murine thymocytes from 6°Co γ-ray-induced mitochondria-mediated apoptosis.

PURPOSE: Purple sweet potato (PSP) pigments have been widely accepted as antioxidants but their radioprotective effect still remains unclear. In this study we investigated the effect of PSP pigments on 6°Co γ-ray-induced mitochondria-mediated apoptosis in murine thymocytes. MATERIALS AND METHODS: The murine thymocytes were pretreated by PSP pigments before exposure to 4 Gy 6°Co γ-rays. Flow cytometry analysis was used to measure apoptotic cells and mitochondrial membrane potential. Reactive oxygen species (ROS) were detected using 2',7',-dichlorofluorescein diacetate (DCFH-DA) probe and the activity of antioxidant enzymes was tested by biochemical assay after irradiation. Cytochrome c, caspase-3 and poly ADP-ribose polymerase (PARP) were measured by Western blotting. RESULTS: After treatment with PSP pigments and exposure to 4 Gy radiation the apoptosis of thymocytes was reduced and the mitochondrial transmembrane potential was maintained compared to control cells. In the presence of PSP pigments, ROS were reduced and the activities of glutathione peroxidase (GSH-px) and superoxide dismutase (SOD) were protected and in some cases increased. All the pro-apoptotic proteins (cytochrome oxidase, caspase 3 and PARP) decreased in PSP pigments pretreated thymocytes compared to irradiated cells in the absence of PSP pigments. CONCLUSIONS: Pre-treatment with PSP pigments significantly inhibited 6°Co γ-ray-induced mitochondria-mediated apoptosis. This radioprotective effect might be related to ROS scavenging, the enhancement of the activity of antioxidant enzymes, the maintenance of mitochondrial transmembrane potential, and the sequential inhibition of cytochrome c release and downstream caspase and PARP cleavage.

Inhibitory effect of polypeptide from Chlamys farreri on ultraviolet A-induced oxidative damage on human skin fibroblasts in vitro.

We have previously reported that polypeptide from Chlamys farreri (PCF) inhibits the oxidative damage of ultraviolet A (UVA) on HeLa cells in vitro [Acta Pharm. Sin. 23 (2002) 961]. To further elucidate a possible role for PCF on UVA-damaged normal human cells, we established the oxidative damage models of normal human dermal fibroblasts (NHDF) exposed to UVA to study the protective effect of PCF on human dermal fibroblasts in vitro. In this study, 3-[4,5-dimethylthiazol-2-yl]-2,5-diphenyltetrazolium bromide (MTT) method was used to detect the cell viability. The intracellular superoxide dismutase (SOD), glutathione peroxidase (GSH-px), catalase (CAT), xanthine oxidase (XOD), malondialdehyde (MDA), reactive oxygen species (ROS), total antioxidative capacity (T-AOC), and anti-superoxide anion capacity (A-ASC) were measured. The effect of PCF on UVA-induced apoptosis were investigated by Annexin V-FITC assay. Intracellular calcium was determined with the calcium-sensitive fluorochrome Fluo-3, and mitochondrial transmembrane potential with rhodamine 123. Comet assay was employed to detect the UVA-induced DNA damage. The ultrastructure of cell was observed under transmission electron microscope. The results indicated that PCF could greatly enhance the viability of NHDF and markedly promote SOD, GSH-px, T-AOC, and A-ASC, while the amounts of MDA and ROS, the activity of XOD were decreased. PCF could inhibit UVA-induced apoptosis and DNA damage in NHDF. The concentration of cellular free calcium was decreased and the mitochondrial transmembrane potential was increased by PCF. In ultrastructure of NHDF, PCF could greatly decrease UVA-induced damage, especially membrane. Our results suggest that the supplementation of PCF appears to reduce the UVA-induced normal human dermal fibroblasts damage efficiently. It may be involved in the PCF's abilities of scavenging oxygen free radical, inhibiting lipid peroxidation, increasing antioxidative enzymes, decreasing intracellular calcium and protection of membrane structure in NHDF irradiated by UVA.

Protective effect of polypeptide from Chlamys farreri on mitochondria in human dermal fibroblasts irradiated by ultraviolet B.

AIM: To study the effect of polypeptide from Chlamys farreri (PCF) on mitochondria of human dermal fibroblasts irradiated by ultraviolet B (UVB) in vitro. METHODS: Malondialdehyde (MDA) and antioxidant enzymes including superoxide dismutase (SOD) and glutathione peroxidase (GSH-PX) were determined by biochemical methods. Mitochondrial transmembrane potential was measured by flow cytometry. Ultrastructure of fibroblasts was observed with transmission electron microscope. RESULTS: UVB (1.176 x 10(-4) J/cm(2)) induced mitochondria damage in dermal fibroblast and PCF (0.25%-1%) reduced the damage in a concentration-dependent manner. Furthermore, PCF also concentration-dependently maintained the stability of mitochondrial transmembrane potential. PCF was able to reduce the MDA formation caused by UVB, meanwhile increased the activities of SOD and GSH-PX. The differences among the PCF groups and UVB model group were significant (P<0.05, P<0.01). CONCLUSION: The UVB-induced mitochondria damage was alleviated by PCF in human dermal fibroblasts.