Su-Bin Yu

α-Mangostin Induces Apoptosis and Cell Cycle Arrest in Oral Squamous Cell Carcinoma Cell

Mangosteen has long been used as a traditional medicine and is known to have antibacterial, antioxidant, and anticancer effects. Although the effects of α-mangostin, a natural compound extracted from the pericarp of mangosteen, have been investigated in many studies, there is limited data on the effects of the compound in human oral squamous cell carcinoma (OSCC). In this study, α-mangostin was assessed as a potential anticancer agent against human OSCC cells. α-Mangostin inhibited cell proliferation and induced cell death in OSCC cells in a dose- and time-dependent manner with little to no effect on normal human PDLF cells. α-Mangostin treatment clearly showed apoptotic evidences such as nuclear fragmentation and accumulation of annexin V and PI-positive cells on OSCC cells. α-Mangostin treatment also caused the collapse of mitochondrial membrane potential and the translocation of cytochrome c from the mitochondria into the cytosol. The expressions of the mitochondria-related proteins were activated by α-mangostin. Treatment with α-mangostin also induced G1 phase arrest and downregulated cell cycle-related proteins (CDK/cyclin). Hence, α-mangostin specifically induces cell death and inhibits proliferation in OSCC cells via the intrinsic apoptosis pathway and cell cycle arrest at the G1 phase, suggesting that α-mangostin may be an effective agent for the treatment of OSCC.

Delphinidin induces apoptosis and inhibits epithelial‐to‐mesenchymal transition via the ERK/p38 MAPK‐signaling pathway in human osteosarcoma cell lines

Delphinidin is major anthocyanidin that is extracted from many pigmented fruits and vegetables. This substance has anti‐oxidant, anti‐inflammatory, anti‐angiogenic, and anti‐cancer properties. In addition, delphinidin strongly suppresses the migration and invasion of various cancer cells during tumorigenesis. Although delphinidin has anti‐cancer effects, little is known about its functional roles in osteosarcoma (OS). For these reasons, we have demonstrated the effects of delphinidin on OS cell lines. The effects of delphinidin on cell viability and growth of OS cells were assessed using the MTT assay and colony formation assays. Hoechst staining indicated that the delphinidin‐treated OS cells were undergoing apoptosis. Flow cytometry, confocal microscopy, and a western blot analysis also indicated evidence of apoptosis. Inhibition of cell migration and invasion was found to be associated with epithelial‐to‐mesenchymal transition (EMT), observed by using a wound healing assay, an invasion assay, and a western blot analysis. Furthermore, delphinidin treatment resulted in a profound reduction of phosphorylated forms of ERK and p38. These findings demonstrate that delphinidin treatment suppressed EMT through the mitogen‐activated protein kinase (MAPK) signaling pathway in OS cell lines. Taken together, our results suggest that delphinidin strongly inhibits cell proliferation and induces apoptosis. Delphinidin treatment also suppresses cell migration and prevents EMT via the MAPK‐signaling pathway in OS cell lines. For these reasons, delphinidin has anti‐cancer effects and can suppress metastasis in OS cell lines, and it might be worth using as an OS therapeutic agent.

XIAP inhibitor embelin induces autophagic and apoptotic cell death in human oral squamous cell carcinoma cells

Embelin is an active ingredient of traditional herbal remedies for cancer and other diseases. Recently, it has been suggested that autophagy may play an important role in cancer therapy. However, little data are available regarding the role of autophagy in oral cancers. Therefore, we conducted this study to examine whether Embelin modulates autophagy in Ca9‐22. Our results showed that Embelin had anticancer activity against the Ca9‐22 human tongue squamous cell, and we observed that autophagic vacuoles were formed by MDC and AO. We also analyzed Embelin‐treated Ca9‐22 cells for the presence of biochemical markers and found that it directly affected the conversion of LC3‐II, the degradation of p62/SQSTM1, full‐length cleavage formation of ATG5‐ATG12 complex and Beline‐1, and caspase activation. Rescue experiments using an autophagy inhibitor showed Embelin‐induced cell death in Ca9‐22, confirming that autophagy acts as a pro‐death signal. Furthermore, Embelin exhibited anticancer activity against Ca9‐22 via both autophagy and apoptosis. These findings suggest that Embelin may potentially contribute to oral cancer treatment and provide useful information for the development of a new therapeutic agent.

Propofol protects against oxidative-stress-induced COS-7 cell apoptosis by inducing autophagy

Background In oxidative stress, reactive oxygen species (ROS) production contributes to cellular dysfunction and initiates the apoptotic cascade. Autophagy is considered the mechanism that decreases ROS concentration and oxidative damage. Propofol shows antioxidant properties, but the mechanisms underlying the effect of propofol preconditioning (PPC) on oxidative injury remain unclear. Therefore, we investigated whether PPC protects against cell damage from hydrogen peroxide (H2O2)-induced oxidative stress and influences cellular autophagy. Method COS-7 cells were randomly divided into the following groups: control, cells were incubated in normoxia (5% CO2, 21% O2, and 74% N2) for 24 h without propofol; H2O2, cells were exposed to H2O2 (400 µM) for 2 h; PPC + H2O2, cells pretreated with propofol were exposed to H2O2; and 3-methyladenine (3-MA) + PPC + H2O2, cells pretreated with 3-MA (1 mM) for 1 h and propofol were exposed to H2O2. Cell viability was determined using 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide thiazolyl blue (MTT) reduction. Apoptosis was determined using Hoechst 33342 staining and fluorescence microscopy. The relationship between PPC and autophagy was detected using western blot analysis. Results Cell viability decreased more significantly in the H2O2 group than in the control group, but it was improved by PPC (100 µM). Pretreatment with propofol effectively decreased H2O2-induced COS-7 cell apoptosis. However, pretreatment with 3-MA inhibited the protective effect of propofol during apoptosis. Western blot analysis showed that the level of autophagy-related proteins was higher in the PPC + H2O2 group than that in the H2O2 group. Conclusion PPC has a protective effect on H2O2-induced COS-7 cell apoptosis, which is mediated by autophagy activation.

Cytoprotective effect of flavonoid-induced autophagy on bisphosphonate mediated cell death in osteoblast

With rapid economic growth and further developments in medical science, the entry into the aging population is currently increasing, as is the number of patients with metabolic diseases, such as hypertension, hyperlipidemia, heart disease, and diabetes. The current treatments for metabolic bone diseases, which are also on the rise, cause negative side effects. Bisphosphonates, which are used to treat osteoporosis, inhibit the bone resorption ability of osteoclasts and during prolonged administration, cause bisphosphonate‐related osteonecrosis of the jaw (BRONJ). Numerous studies have shown the potential role of natural plant products as flavonoids in the protection against osteoporosis and in the influence of bone remodeling. Autophagy occurs after the degradation of cytoplasmic components within the lysosome and serves as an essential cytoprotective response to pathologic stress caused by certain diseases. In the present study, we hypothesized that the cytoprotective effects of flavonoids might be related to those associated with autophagy, an essential cytoprotective response to the pathologic stress caused by certain diseases, in osteoblasts. We demonstrated the cytoprotective effect of flavonoid‐induced autophagy against the toxicity of zoledronate and the induction of autophagy by flavonoids to support osteogenic transcription factors, leading to osteoblast differentiation and bone formation. Further studies are necessary to clarify the connections between autophagy and osteogenesis. It would be helpful to shed light on methodological challenges through molecular biological studies and new animal models. The findings of the current study may help to delineate the potential role of flavonoids in the treatment of metabolic bone disease.

Luteolin Induces Apoptosis via Mitochondrial Pathway and Inhibits Invasion and Migration of Oral Squamous Cell Carcinoma by Suppressing Epithelial-Mesenchymal Transition Induced Transcription Factors

Oral squamous cell carcinoma (OSCC) is the most common type of oral malignancy. Numerous therapies have been proposed for its cure. Research is continually being conducted to develop new forms of treatment as current therapies are associated with numerous side-effects. Luteolin, a common dietary flavonoid, has been demonstrated to possess strong anti-cancer activity against various human cancer cell lines. Nevertheless, research into luteolin-based anticancer activity against oral cancer remains scarce. Thus, the objective of this study was to assess the effect of luteolin as an anti-cancer agent. After treatment with luteolin, Ca9-22 and CAL-27 oral cancer cells showed condensed nuclei and enhanced apoptotic rate with evidence of mitochondria-mediated apoptosis. Epithelial-mesenchymal transition (EMT) is closely related to tumor migration and invasion. Luteolin suppressed cancer cell invasion and migration in the current study. Elevated expression of E-cadherin, an adherens junction protein, was evident in both cell lines after luteolin treatment. Luteolin also significantly inhibited transcription factors (i.e., N-cadherin, Slug, Snail, Twist, and ZEB-1) that regulated expression of tumor suppressors such as E-cadherin based on Western blot analysis and quantitative PCR. Thus, luteolin could induce mitochondrial apoptosis and inhibit cancer cell invasion and migration by suppressing EMT-induced transcription factors.

Induction of Apoptosis and Inhibition of Epithelial Mesenchymal Transition by α-Mangostin in MG-63 Cell Lines

Osteosarcoma is the most common bone primary malignant tumor and nearly 30% of patients still die from osteosarcoma due to metastasis or recurrence. Thus, it is necessary to develop effective new chemotherapeutic agents for osteosarcoma treatment. α-Mangostin is a xanthone derivative shown to have antioxidant and anticarcinogen properties. However, the molecular mechanisms underlying the antimetastatic effects of osteosarcoma remain unclear. In metastasis progression, epithelial mesenchymal transition (EMT) is a process that plays important roles in development, cell polarity, and increased invasion and migration. This study focused on the induction of apoptosis and inhibition of EMT process by α-mangostin in human osteosarcoma cell line MG63. α-Mangostin treatments on MG63 cells not only showed the several lines of evidence of apoptotic cell death but also inhibited cell migration, invasion, and EMT-inducing transcription factor. In conclusion, we demonstrate that the α-mangostin induces apoptosis via mitochondrial pathway and suppresses metastasis of osteosarcoma cells by inhibiting EMT.

Cordycepin Accelerates Osteoblast Mineralization and Attenuates Osteoclast Differentiation In Vitro

Bone homeostasis destruction is triggered by the uncontrolled activity of osteoblasts and osteoclasts. Targeting both the regulation of bone formation and resorption is a promising strategy for treating bone disorders. Cordycepin is a major component of Chinese caterpillar fungus Cordyceps militaris. It exerts a variety of biological actions in various cells and animal models. However, its function on bone metabolism remains unclear. In the present study, we discovered a dual-action function of cordycepin in murine MC3T3-E1 and RAW264.7 cells. MC3T3-E1 cells were cultured in an osteogenic medium in the presence of 1 μM cordycepin for up two weeks. Cordycepin was used for effects of osteoblast and osteoclast differentiation. Cell viability was measured using the MTT assay. Osteoblast differentiation was confirmed by alizarin red staining, ALP activity, western blot, and real-time PCR. Osteoclast differentiation and autophagic activity were confirmed via TRAP staining, pit formation assay, confocal microscopy, western blot, and real-time PCR. Cordycepin promoted osteoblast differentiation, matrix mineralization, and induction of osteoblast markers via BMP2/Runx2/Osterix pathway. On the other hand, RAW264.7 cells were differentiated into osteoclast by RANKL treatment for 72 h. 1 μM cordycepin significantly inhibited RANKL-induced osteoclast formation and resorption activity through disturbing the actin ring-formatted sealing zone and activating cathepsin K and MMP9. These findings indicate that cordycepin might be an innovative dual-action therapeutic agent for bone disease caused by an imbalance of osteoblasts and osteoclasts.

Propofol protects human keratinocytes from oxidative stress via autophagy expression

Background The skin consists of tightly connected keratinocytes, and prevents extensive water loss while simultaneously protecting against the entry of microbial pathogens. Excessive cellular levels of reactive oxygen species can induce cell apoptosis and also damage skin integrity. Propofol (2,6-diisopropylphenol) has antioxidant properties. In this study, we investigated how propofol influences intracellular autophagy and apoptotic cell death induced by oxidative stress in human keratinocytes. Method The following groups were used for experimentation: control, cells were incubated under normoxia (5% CO2, 21% O2, and 74% N2) without propofol; hydrogen peroxide (H2O2), cells were exposed to H2O2 (300 µM) for 2 h; propofol preconditioning (PPC)/H2O2, cells pretreated with propofol (100 µM) for 2 h were exposed to H2O2; and 3-methyladenine (3-MA)/PPC/H2O2, cells pretreated with 3-MA (1 mM) for 1 h and propofol were exposed to H2O2. Cell viability, apoptosis, and migration capability were evaluated. Relation to autophagy was detected by western blot analysis. Results Cell viability decreased significantly in the H2O2 group compared to that in the control group and was improved by propofol preconditioning. Propofol preconditioning effectively decreased H2O2-induced cell apoptosis and increased cell migration. However, pretreatment with 3-MA inhibited the protective effect of propofol on cell apoptosis. Autophagy was activated in the PPC/H2O2 group compared to that in the H2O2 group as demonstrated by western blot analysis and autophagosome staining. Conclusion The results suggest that propofol preconditioning induces an endogenous cellular protective effect in human keratinocytes against oxidative stress through the activation of signaling pathways related to autophagy.