We examined the anti-cancer effect of genistein, a soy-derived isoflavone, in human bladder transitional cell carcinoma T24 cells. According to our data, genistein induced G2/M phase arrest of the cell cycle and apoptosis. Genistein down-regulated the levels of cyclin A and cyclin B1, but up-regulated the levels of p21WAF1/CIP1, cyclin-dependent kinase (Cdk) inhibitor, that was complexed with Cdc2 and Cdk2. Furthermore, genistein induced the activation of caspases (caspase-3, -8 and -9), and cleavage of poly (ADP-ribose) polymerase cleavage. However, genistein-induced apoptosis was significantly inhibited by a pan-caspase inhibitor, indicating that the induction of apoptosis by genestein was caspase-dependent. In addition, genistein increased the cytosolic release of cytochrome c by increasing the Bax/Bcl-2 ratio and destroying mitochondria integrity. Moreover, genistein inactivated the phosphoinositide 3-kinase (PI3K)/Akt signaling pathway, while LY294002, a PI3K/Akt inhibitor, increased the apoptosis-inducing effect of genistein. Genistein further increased the accumulation of reactive oxygen species (ROS), which was significantly suppressed by N-acetyl cysteine (NAC), a ROS scavenger, and in particular, NAC prevented genistein-mediated inactivation of PI3K/Akt signaling, G2/M arrest and apoptosis. Therefore, the present results indicated that genistein promoted apoptosis induction in human bladder cancer T24 cells, which was associated with G2/M phase cell cycle arrest via regulation of ROS-dependent PI3K/Akt signaling pathway.

It is well known that fucoidan, a natural sulfated polysaccharide present in various brown algae, mediates anticancer effects through the induction of cell cycle arrest and apoptosis. Nevertheless, the role of tumor suppressor p53 in the mechanism action of fucoidan remains unclear. Here, we investigated the anticancer effect of fucoidan on two p53 isogenic HCT116 (p53+/+ and p53−/−) cell lines. Our results showed that inhibition of cell viability, induction of apoptosis and DNA damage by treatment with fucoidan were similar in two cell lines. Flow cytometric analysis revealed that fucoidan resulted in G1 arrest in the cell cycle progression, which correlated with the inhibition of phosphorylation of retinoblastoma protein (pRB) and concomitant association of pRB with the transcription factor E2Fs. Furthermore, treatment with fucoidan obviously upregulated the expression of cyclin-dependent kinase (CDK) inhibitors, such as p21WAF1/CIP1 and p27KIP1, which was paralleled by an enhanced binding with CDK2 and CDK4. These events also commonly occurred in both cell lines, suggesting that fucoidan triggered G1 arrest and apoptosis in HCT116 cells by a p53-independent mechanism. Thus, given that most tumors exhibit functional p53 inactivation, fucoidan could be a possible therapeutic option for cancer treatment regardless of the p53 status.

Osteoarthritis (OA) is a degenerative joint disease that is characterized by irreversible articular cartilage destruction by inflammatory reaction. Among inflammatory stimuli, interleukin-1β (IL-1β) is known to play a crucial role in OA pathogenesis by stimulating several mediators that contribute to cartilage degradation. Recently, the marine brown alga Sargassum serratifolium has been reported to exhibit antioxidant and anti-inflammatory effects in microglial and human umbilical vein endothelial cell models using lipopolysaccharide and tumor necrosis factor-α, but its beneficial effects on OA have not been investigated. This study aimed to evaluate the anti-osteoarthritic effects of ethanol extract of S. serratifolium (EESS) in SW1353 human chondrocytes and, in parallel, primary rat articular chondrocytes. Our results showed that EESS effectively blocked the generation of reactive oxygen species in IL-1β-treated SW1353 and rat primary chondrocytes, indicating that EESS has a potent antioxidant activity. EESS also attenuated IL-1β-induced production of nitric oxide (NO) and prostaglandin E₂, major inflammatory mediators in these cells, which was associated with the inhibition of inducible NO synthase and cyclooxygenase-2 expression. Moreover, EESS downregulated the level of gene expression of matrix metalloproteinase (MMP)-1, -3 and -13 in SW1353 chondrocytes treated with IL-1β, resulting in their extracellular secretion reduction. In addition, the IL-1β-induced activation of nuclear factor-kappa B (NF-κB) was restored by EESS. Furthermore, EESS reduced the activation of p38 mitogen-activated protein kinase (MAPK) and phosphatidylinositol-3-kinase (PI3K)/Akt signaling pathways upon IL-1β stimulation. These results indicate that EESS has the potential to exhibit antioxidant and anti-inflammatory effects through inactivation of the NF-κB, p38 MAPK, and PI3K/Akt signaling pathways. Collectively, these findings demonstrate that EESS may have the potential for chondroprotection, and extracts of S. serratifolium could potentially be used in the prevention and treatment of OA.

Oxidative stress in chondrocytes plays a critical role in the pathogenesis of osteoarthritis as an important cause of articular cartilage degradation. Sargassum serratifolium C. Agardh, a marine brown algae, is known to have potent antioxidant activity. Nevertheless, no study has been conducted yet on the protective efficacy against oxidative stress in chondrocytes. Therefore, the aim of the current study is to investigate the mechanism of the antioxidative effect of ethanol extract of S. serratifolium (EESS) on DNA damage and apoptosis induced by hydrogen peroxide (H₂O₂) in SW1353 human chondrocytes. For this purpose, SW1353 cells exposed to H₂O₂ in the presence or absence of EESS were applied to cell viability assay, comet assay, immunoblotting and flow cytometry analyses. Our results showed that EESS effectively attenuated H₂O₂-induced cytotoxicity and DNA damage associated with the inhibition of reactive oxygen species (ROS) accumulation. EESS also weakened the mitochondria membrane permeabilization by H₂O₂, and recovered H₂O₂-induced decreased expression of anti-apoptotic Bcl-2 and pro-caspase-3, and degradation of poly (ADP-ribose) polymerase. In addition, EESS increased not only expression, but also phosphorylation of nuclear factor-erythroid 2 related factor 2 (Nrf2), and promoted the expression of heme oxygenase-1 (HO-1), a critical target enzyme of Nrf2, but decreased the expression of kelch-like ECH-associated protein-1; however, the inhibition of HO-1 activity by zinc protoporphyrin abolished the antioxidant potential induced by EESS against H₂O₂-mediated oxidative stress. Therefore, the results of this study suggest that the antioxidant efficacy of EESS in chondrocytes is at least involved in the Nrf2/HO-1 signaling pathway-dependent mechanism.

Excessive bone resorption by osteoclasts causes bone loss-related diseases and reactive oxygen species (ROS) act as second messengers in intercellular signaling pathways during osteoclast differentiation. In this study, we explored the protective effects of fermented oyster extract (FO) against receptor activator of nuclear factor-κB (NF-κB) ligand (RANKL)-induced osteoclast differentiation in murine monocyte/macrophage RAW 264.7 cells. Our results showed that FO markedly inhibited RANKL-induced activation of tartrate-resistant acid phosphatase and formation of F-actin ring structure. Mechanistically, FO has been shown to down-regulate RANKL-induced expression of osteoclast-specific markers by blocking the nuclear translocation of NF-κB and the transcriptional activation of nuclear factor of activated T cells c1 (NFATc1) and c-Fos. Furthermore, FO markedly diminished ROS production by RANKL stimulation, which was associated with blocking the expression of nicotinamide adenine dinucleotide phosphate oxidase 1 (NOX1) and its regulatory subunit Rac-1. However, a small interfering RNA (siRNA) targeting NOX1 suppressed RANKL-induced expression of osteoclast-specific markers and production of ROS and attenuated osteoclast differentiation as in the FO treatment group. Collectively, our findings suggest that FO has anti-osteoclastogenic potential by inactivating the NF-κB-mediated NFATc1 and c-Fos signaling pathways and inhibiting ROS generation, followed by suppression of osteoclast-specific genes. Although further studies are needed to demonstrate efficacy in in vivo animal models, FO may be used as an effective alternative agent for the prevention and treatment of osteoclastogenic bone diseases.

Cordycepin (3'-deoxyadenosine), a major bioactive compound of Cordyceps militaris, has many pharmacological actions, such as anti-inflammatory and anticancer activities. In this study, the relationship between inhibition of cell motility and anti-invasive activity by cordycepin in LNCaP human prostate carcinoma cells was investigated. Within the concentration range that was not cytotoxic, cordycepin time-dependently inhibited cell motility and invasiveness of LNCaP cells. The inhibitory effects of cordycepin on cell invasiveness were associated with tightening of tight junctions (TJs), which was demonstrated by an increase in transepithelial electrical resistance (TER). Immunoblotting indicated that cordycepin decreases levels of claudin proteins, which are major components of TJs that play a key role in control and selectivity of paracellular transport. Furthermore, cordycepin inhibited the expression and activity of matrix metalloproteinase (MMP)-2 and MMP-9, and simultaneously increased levels of tissue inhibitor of metalloproteinase (TIMP)-1 and TIMP-2. These effects were related to inactivation of the phosphoinositide 3-kinase (PI3K)/Akt pathway in LNCaP cells. These findings suggest that cordycepin inhibits the migration and invasion of LNCaP cells by downregulating the activity of TJs and MMPs, possibly in association with suppression of Akt activation.