Yih-Shou Hsieh

Cyanidin 3-Glucoside and Peonidin 3-Glucoside Inhibit Tumor Cell Growth and Induce Apoptosis In Vitro and Suppress Tumor Growth In Vivo

Abstract: Dietary polyphenols, including anthocyanins, are suggested to be involved in the protective effects of fruits and vegetables against cancer. However, anticancer effects of peonidin 3-glucoside have not been clearly demonstrated, with only limited studies being available concerning the inhibitory effect of cyanidin 3-glucoside for tumor cell growth. Therefore, in this study, we have isolated and identified the two bioactive compounds, peonidin 3-glucoside and cyanidin 3-glucoside, from Oryza sativa L. indica, to treat various cancer cells. The results showed that, among analyzed cell lines, HS578T was the most sensitive to peonidin 3-glucoside and cyanidin 3-glucoside. Treatment with peonidin 3-glucoside or cyanidin 3-glucoside resulted in a strong inhibitory effect on cell growth via G2/M arrest. Regarding cell cycle–related proteins, peonidin 3-glucoside treatment resulted in down-regulation of protein levels of cyclin-dependent kinase (CDK)-1, CDK-2, cyclin B1, and cyclin E, whereas cyanidin 3-glucoside could decrease the protein levels of CDK-1, CDK-2, cyclin B1, and cyclin D1. In addition, cyanidin 3-glucoside or peonidin 3-glucoside also induced caspase-3 activation, chromatin condensation, and cell death. Furthermore, anthocyanins from O. sativa L. indica were evidenced by their inhibition on the growth of Lewis lung carcinoma cells in vivo.

Silibinin inhibits the invasion of human lung cancer cells via decreased productions of urokinase-plasminogen activator and matrix metalloproteinase-2†

Cancer metastasis, involving multiple processes and various cytophysiological changes, is a primary cause of cancer death and may complicate the clinical management, even lead to death. Silibinin is a flavonoid antioxidant and wildly used for its antihepatotoxic properties and recent studies have revealed pleiotropic anticancer and antiproliferative capabilities of silibinin. In this study, we first observed that silibinin exerted a dose‐ and time‐dependent inhibitory effect on the invasion and motility, but hardly on the adhesion, of highly metastatic A549 cells in the absence of cytotoxicity. To look at the precise involvement of silibinin in cancer metastasis, A549 cells were treated with silibinin at various concentrations, up to 100 μM, for a defined period and then subjected to gelatin zymography, casein zymography and Western blot to investigate the impacts of silibinin on metalloproteinase‐2 (MMP‐2), urokinase plasminogen activator (u‐PA), and tissue inhibitor of metalloproteinase‐2 (TIMP‐2), respectively. The results showed that a silibinin treatment may decrease the expressions of MMP‐2 and u‐PA in a concentration‐ and time‐dependent manner and enhance the expression of TIMP‐2. Further analysis with semi‐quantitative RT‐PCR showed that silibinin may regulate the expressions of MMP‐2 and u‐PA on the transcriptional level while on the translational or post‐translational level for TIMP‐2.

Silibinin Inhibits Invasion of Oral Cancer Cells by Suppressing the MAPK Pathway

Oral squamous cell carcinoma (OSCC) is the most common malignancy of the oral cavity. Here, we provide molecular evidence associated with the anti-metastatic effect of silibinin by showing a marked inhibition of the invasion and motility of SCC-4 tongue cancer cells, with 89% and 66.4% of inhibition, respectively, by 100 μM of silibinin. This effect was associated with a reduced expression of MMP-2 and u-PA, together with an enhanced expression of TIMP-2 and PAI-1. Silibinin also exerted an inhibitory effect on the phosphorylation of ERK1/2. Additionally, pre-treatment of SCC-4 cancer cells with 10 and 20 μM of U0126, a specific MEK inhibitor, resulted in a reduced expression of MMP-2 (18.7 and 51.4%) and u-PA (19.2 and 48.9%) concomitantly with a marked inhibition of cell invasion (13.7 and 45.7%). Finally, silibinin was evidenced by its inhibition of the metastasis of Lewis lung carcinoma (LLC) cells in vivo. These results suggested that silibinin can reduce the invasion and metastasis of tumor cells, and such a characteristic may be of great value in the development of a potential cancer therapy.

Increased tissue inhibitor of metalloproteinase-1 expression and inhibition of gelatinase A activity in buccal mucosal fibroblasts by arecoline as possible mechanisms for oral submucous fibrosis

Oral submucous fibrosis (OSF) is a pre-malignant fibrotic lesion of the mouth in areca quid chewers. It is probably a consequence of disturbances in the hemeostatic equilibrium between synthesis and degradation of extracellular matrix molecules (ECM). To date, there has been little research about the role of tissue inhibitors of metalloproteinase (TIMPs) and matrix metalloproteinases (MMPs) in the pathogenesis of OSF. In the present study, we examined the activity of TIMPs from cells cultured from OSF and normal buccal mucosa. OSF specimens were found to have higher TIMP-1 expression than normal buccal mucosal fibroblasts (BMFs) by Western blots. To verify whether arecoline, a major areca nut alkaloid, could affect TIMP or MMP production by human BMFs, Western blots and gelatine zymography were used. Arecoline was found to elevate TIMP-1 expression at the concentration level under 20 microg/ml in a dose-dependent manner. The amount of TIMP-1 was about 2.7 fold at a concentration level of 10 microg/ml compared with control. From gelatin zymograms, the main gelatinolytic proteinase secreted by the human BMFs was MMP-2, and only minimal amounts of MMP-9 could be detectable from zymogram. In addition, arecoline was found to inhibit MMP-2 secretion and production at the concentration level of 40 microg/ml. The gelatinolytic activity of MMP-2 was about 54% at a concentration level of 80 microg/ml compared with control. Taken together, it was found that arecoline acted not only as an inhibitor on gelatinolytic activity of MMP-2, but also a stimulator for TIMP-1 activity. These synergistic effects may contribute to the ECM components accumulation in the areca quid associated OSF.

p38 Mitogen-Activated Protein Kinase Pathway Is Involved in Protein Kinase Cα–Regulated Invasion in Human Hepatocellular Carcinoma Cells

Protein kinase Calpha (PKCalpha) has been suggested to play an important role in tumorigenesis, invasion, and metastasis. In this study, we investigated the signal pathways selectively activated by PKCalpha in human hepatocellular carcinoma (HCC) cells to determine the role of mitogen-activated protein kinases (MAPK) in PKCalpha-mediated HCC migration and invasion. A stable SK-Hep-1 cell clone (siPKCalpha-SK) expressing DNA-based small interfering RNA (siRNA) PKCalpha was established and was then characterized by cell growth, migration, and invasion. The expression of PKCalpha was decreased in siPKCalpha-SK, and cell growth, migration, and invasion were reduced. These changes were associated with the decrease in p38 MAPK phosphorylation level, but not in c-jun-NH(2)-kinase-1/2 (JNK-1/2) and extracellular signal-regulated kinase-1/2 (ERK-1/2). This phenomenon was confirmed in the SK-Hep-1 cells treated with antisense PKCalpha olignucleotide. The p38 MAPK inhibitor SB203580 or dominant negative p38 mutant plasmid (DN-p38) was used to evaluate the dependency of p38 MAPK in PKCalpha-regulated migration and invasion. Attenuation of cell migration and invasion was revealed in the SK-Hep-1 cells treated with the SB203580 or DN-p38, but not with ERK-1/2 inhibitor PD98059 or JNK-1/2 inhibitor SP600125. Overexpression of constitutively active MKK6 or PKCalpha may restore the inactivation of p38 and the attenuation of cell migration and invasion in siPKCalpha-SK. Similar findings were observed in the stable HA22T/VGH cell clone expressing siRNA PKCalpha. This study provides new insight into the role of p38 MAPK in PKCalpha-mediated malignant phenotypes, especially in PKCalpha-mediated cancer cell invasion, which may have valuable implications for developing new therapies for some PKCalpha-overexpressing cancers.

Antimetastatic effects of Terminalia catappa L. on oral cancer via a down-regulation of metastasis-associated proteases

The incidence and mortality of oral cancer in Taiwan have been increased during the last decade, which could be mainly resulted from the difficulty in treatment related to metastasis. As a potential and popular folk medicine, Terminalia catappa leaves have been proven to possess various biological benefits including anti-cancer activities. However, the detailed effects and molecular mechanisms of T. catappa leaves on the metastasis of oral cancer cells were still unclear. Thus, SCC-4 oral cancer cells were subjected to a treatment with ethanol extracts of T. catappa leaves (TCE) and then analyzed for the effect of TCE on the migration and invasion. Modified Boyden chamber assays revealed that TCE treatment significantly inhibited the cell migration/invasion capacities of SCC-4 cells. Furthermore, results of zymography and western blotting showed that activities and protein levels of MMP-2, MMP-9 and u-PA were all inhibited by TCE. Further studies indicated that TCE may inhibit phosphorylation of ERK1/2, JNK1/2 and Akt while the expression of nuclear protein NF-kappaB, c-Jun and c-Fos were inhibited as well. EMSA assay revealed that the DNA-binding activity with AP-1 and NF-kappaB was also decreased by TCE. In conclusion, TCE may serve as a powerful chemopreventive agent against oral cancer metastasis.

Reduction of PKCα decreases cell proliferation, migration, and invasion of human malignant hepatocellular carcinoma

Protein kinase C (PKC) superfamily play key regulatory roles on the development of cancer. However, the exact role of these enzymes in human hepatocellular carcinoma (HCC) has not been well established. Using the RT‐PCR and Western blotting to analyze the levels of PKC isoforms mRNA and protein in the five different differentiated hepatoma cell lines, we found that PKCα was highly expressed in the poor‐differentiated HCC cell lines (SK‐Hep‐1 and HA22T/VGH) as compared with that in the well‐differentiated HCC cell lines (PLC/PRF/5, Hep3B, and HepG2). When treated with PKCα antisense oligonucleotides (ODN), both HA22T/VGH and SK‐Hep‐1 cells lines showed the reduction of PKCα expression, as well as a deceleration in the growth rate and in the level of cyclin D1, but the increase in the levels of p53 and p21WAF1/CIP1. Moreover, the reduction of PKCα expression also inhibited the migratory and invasive potential of both HA22T/VGH and SK‐Hep‐1 cells lines, and revealed a down‐regulation of several migration/invasion‐related genes (MMP‐1, u‐PA, u‐PAR, and FAK). These phenomenon were also confirmed by DNA‐based small interfering RNA (siRNA) PKCα and PKCα/β specific inhibitor Go6976. Thus, the results indicated that PKCα may be associated with regulation of cell proliferation/migration/invasion in human poorly differentiated HCC cells, suggesting a role for the PKCα in the malignant progression of human HCC. J. Cell. Biochem. 103: 9–20, 2008.

Luteolin Induces Apoptosis in Oral Squamous Cancer Cells

Oral squamous cell carcinoma is the most common malignancy of the oral cavity, and treatment approaches are inadequate. Luteolin, a natural flavonoid compound, has been shown to have anti-tumorigenic properties on various types of tumors. Therefore, we hypothesized that luteolin has anti-tumorigenic properties for oral squamous cell carcinoma, and may provide effective chemotherapy. Results revealed that luteolin reduced the viability of SCC-4 cells and induced apoptosis by decreasing the expression of cyclin-dependent kinase (CDKs), cyclins, and phosphor- retinoblastoma (p-Rb) anti-apoptotic protein, but increased the expression of pro-apoptotic proteins and activated caspase 9 and 3, with a concomitant increase in the levels of cleaved poly-ADP-ribose polymerase (PARP). Combination treatment of luteolin with paclitaxel enhanced the cytotoxic effect of paclitaxel in SCC-4 cells, and continuous administration of luteolin suppressed the growth of xenograft tumors in nude mice. These results suggest that luteolin could be an effective chemotherapeutic agent for the treatment of oral squamous cell carcinoma.

Effects of silymarin on the resolution of liver fibrosis induced by carbon tetrachloride in rats

Summary.  Silymarin, a standardized extract of the milk thistle (Silybum marianum), has a long tradition as a herbal remedy, and was introduced as a hepatoprotective agent a few years ago. However, the therapeutic effects of silymarin remain undefined. Carbon tetrachloride (CCl4) is a xenobiotic used extensively to induce oxidative stress and is one of the most widely used hepatic toxins for experimental induction of liver fibrosis in the laboratory. In this study, we investigated the restoration of the CCl4‐induced hepatic fibrosis by high dose of silymarin in rats. After treatment with oil (as normal group; n = 6) or CCl4 [as model (n = 7) and therapeutic (n = 7) groups] by intragastric delivery for 8 weeks for the induction of liver fibrosis, the rats in the normal and model group were administered orally normal saline four times a week for 3 weeks whilst the therapeutic group received silymarin (200 mg/kg). The histopathological changes were observed with Masson staining. The results showed that the restoration of the CCl4‐induced damage of liver fibrosis in the therapeutic group was significantly increased as compared to that in the model group. Moreover, silymarin significantly decreased the elevation of aspartate aminotransferase (AST), alanine aminotransferase, and alkaline phosphatase in serum, and also reversed the altered expressions of α‐smooth muscle actin in liver tissue. Therefore, these findings indicated that silymarin may have the potential to increase the resolution of the CCl4‐induced liver fibrosis in rats.

Alteration in the expression of protein kinase C isoforms in human hepatocellular carcinoma

This study was designed to investigate the alterations of individual protein kinase C (PKC) isoforms in human liver cancer. Surgical specimens of hepatocellular carcinoma and adjacent normal tissues were extracted into cytosolic and membranous fractions. The level of membrane-bound PKCalpha in the cancer tissue was significantly lower than that in the adjacent normal tissue and consistent with the change in PKC activity. In addition, there was a significant negative correlation between PKCalpha and tumor size. In both cytosolic and membrane fractions, levels of PKCdelta and PKCzeta was significantly higher in the cancer tissue than those in the adjacent normal liver tissue. The alterations in the PKC isoforms signify their roles in the hyperproliferation in liver cancer.