Induction of apoptosis in human hepatoblastoma cells by tetrandrine via caspase-dependent Bid cleavage and cytochrome c release

Growth-Suppressive and Apoptosis-Inducing Effects of Tetrandrine in SW872 Human Malignant Liposarcoma Cells via Activation of Caspase-9, Down-Regulation of XIAP and STAT-3, and ER Stress

Liposarcoma is a rare and heterogeneous soft tissue malignant tumor and has a significant impact on mortality with a poor prognosis. To date, there is no effective treatment for liposarcoma, whereas surgical resection is only the gold treatment with numerous adverse effects. Here we investigated whether tetrandrine inhibits the growth of SW872 human malignant liposarcoma cells. Of note, tetrandrine at 10 μM vastly inhibited growth and induced apoptosis, as evidenced by increased nuclear DNA fragmentation and sub-G1 population of SW872 cells. Mechanistically, treatment with tetrandrine led to activation of caspase-9/3 in SW872 cells, and z-VAD-fmk, a pan-caspase inhibitor, attenuated the tetrandrine-induced apoptosis and growth suppression in SW872 cells. In addition, tetrandrine treatment resulted in down-regulation of XIAP andSTAT-3 in SW872 cells, and importantly knockdown of STAT-3 caused a significant reduction of the cell survival. Tetrandrine also had abilities to up-regulate not only the expression of GRP78 and ATF-4 but also the phosphorylation of eIF-2α in SW872 cells. In summary, these results demonstrated that tetrandrine has strong growth-suppressive and apoptosis-inducing effects on SW872 cells, which are mediated through control of the intrinsic caspase pathway, down-regulation of XIAP and STAT-3, and triggering ER stress.

Targeting the two-pore channel 2 in cancer progression and metastasis

The importance of Ca²⁺ signaling, and particularly Ca²⁺ channels, in key events of cancer cell function such as proliferation, metastasis, autophagy and angiogenesis, has recently begun to be appreciated. Of particular note are two-pore channels (TPCs), a group of recently identified Ca²⁺-channels, located within the endolysosomal system. TPC2 has recently emerged as an intracellular ion channel of significant pathophysiological relevance, specifically in cancer, and interest in its role as an anti-cancer drug target has begun to be explored. Herein, an overview of the cancer-related functions of TPC2 and a discussion of its potential as a target for therapeutic intervention, including a summary of clinical trials examining the TPC2 inhibitors, naringenin, tetrandrine, and verapamil for the treatment of various cancers is provided.

Ginkgolic Acid Suppresses Nasopharyngeal Carcinoma Growth by Inducing Apoptosis and Inhibiting AKT/NF-κB Signaling

Even though nasopharyngeal carcinoma (NPC) is not common worldwide, it is a major public health burden in endemic areas. Distant metastasis often leads to a poor prognosis for NPC; therefore, new and effective anticancer strategies are needed. Ginkgolic acid (GA) is small-molecule compound existing in Ginkgo biloba that has various biologically relevant activities, including antitumor properties; however, its effects and mechanism of action in NPC are unknown. The effects of GA on NPC and such underlying mechanisms were investigated using 5-8F and CNE2 cells and NP69 human immortalized nasopharyngeal epithelial cells in this study. Moreover, the xenograft models were built to examine GA's effection in vivo. GA treatment decreased the survival and invasive capacity of 5-8F and CNE2 and induced their apoptosis, which varied with dose; this was accompanied by downregulation of B cell lymphoma (Bcl)2, upregulation of Bcl2-associated X protein, and activation of poly-ADP ribose polymerase, and caspase-9/-3. G0/G1 phase arrest was induced by GA in NPCs. It also reduced the expression of cyclin-dependent kinase 6 and its regulators cyclin D2 and cyclin D3. GA inhibited the activation of protein kinase B/nuclear factor signaling; this effect was potentiated with GA and 5-fluorouracil (5-FU), which also enhanced 5-FU-induced apoptosis. In summary, GA may be effective as an adjuvant to conventional chemotherapy drugs in preventing the progression of NPC.

Tetrandrine: a review of its anticancer potentials, clinical settings, pharmacokinetics and drug delivery systems

OBJECTIVES

Tetrandrine, a natural bisbenzylisoquinoline alkaloid, possesses promising anticancer activities on diverse tumours. This review provides systematically organized information on cancers of tetrandrine in vivo and in vitro, discuss the related molecular mechanisms and put forward some new insights for the future investigations.

KEY FINDINGS

Anticancer activities of tetrandrine have been reported comprehensively, including lung cancer, colon cancer, bladder cancer, prostate cancer, ovarian cancer, gastric cancer, breast cancer, pancreatic cancer, cervical cancer and liver cancer. The potential molecular mechanisms corresponding to the anticancer activities of tetrandrine might be related to induce cancer cell apoptosis, autophagy and cell cycle arrest, inhibit cell proliferation, migration and invasion, ameliorate metastasis and suppress tumour cell growth. Pharmaceutical applications of tetrandrine combined with nanoparticle delivery system including liposomes, microspheres and nanoparticles with better therapeutic efficiency have been designed and applied encapsulate tetrandrine to enhance its stability and efficacy in cancer treatment.

SUMMARY

Tetrandrine was proven to have definite antitumour activities. However, the safety, bioavailability and pharmacokinetic parameter studies on tetrandrine are very limited in animal models, especially in clinical settings. Our present review on anticancer potentials of tetrandrine would be necessary and highly beneficial for providing guidelines and directions for further research of tetrandrine.

Effect of Heat Treatment on the Anticancer Activity of Houttuynia cordata Thunb Aerial Stem Extract in Human Gastric Cancer SGC-7901 Cells

Gastric cancer is one of the most common malignant tumors in the world, and prevention through diet is one of the ways to control. Houttuynia cordata thunb.(HCT) is a plant having medicine and food function, has many biological properties. However, the effect of food style on the anticancer activity of HCT is not clear. So, we investigate the effect of heat treatment on anticancer activity of HCT. HCT extracts (heated aerial stem, heated subterraneous stem, heated leaves defined as HAS, HSS, HL, respectively, and not heated defined as NAS, NSS, NL, respectively) were obtained, and their inhibited activity were detected by alamar blue assay. The cell apoptosis was detected by DAPI staining and flow cytometry analysis. Western blot was performed to test the expression of apoptotic related protein. HCT showed the anticancer activity in four human tumor cell lines. Interestingly, heat treatment could increase the anticancer activity. In SCG-7901 cells, heat treatment increased anticancer activity of AS by 2-14 folds and induced apoptosis through regulating the intrinsic signaling pathways. Intriguingly, the caspase nine specific inhibitor blocked AS-reduced cell viability. Heat treatment increased the anticancer activity of HCT, and can be used as a dietary style for prevention of gastric cancer.

The Biological Activity of Natural Alkaloids against Herbivores, Cancerous Cells and Pathogens

The growing incidence of microorganisms that resist antimicrobials is a constant concern for the scientific community, while the development of new antimicrobials from new chemical entities has become more and more expensive, time-consuming, and exacerbated by emerging drug-resistant strains. In this regard, many scientists are conducting research on plants aiming to discover possible antimicrobial compounds. The secondary metabolites contained in plants are a source of chemical entities having pharmacological activities and intended to be used for the treatment of different diseases. These chemical entities have the potential to be used as an effective antioxidant, antimutagenic, anticarcinogenic and antimicrobial agents. Among these pharmacologically active entities are the alkaloids which are classified into a number of classes, including pyrrolizidines, pyrrolidines, quinolizidines, indoles, tropanes, piperidines, purines, imidazoles, and isoquinolines. Alkaloids that have antioxidant properties are capable of preventing a variety of degenerative diseases through capturing free radicals, or through binding to catalysts involved indifferent oxidation processes occurring within the human body. Furthermore, these entities are capable of inhibiting the activity of bacteria, fungi, protozoan and etc. The unique properties of these secondary metabolites are the main reason for their utilization by the pharmaceutical companies for the treatment of different diseases. Generally, these alkaloids are extracted from plants, animals and fungi. Penicillin is the most famous natural drug discovery deriving from fungus. Similarly, marines have been used as a source for thousands of bioactive marine natural products. In this review, we cover the medical use of natural alkaloids isolated from a variety of plants and utilized by humans as antibacterial, antiviral, antifungal and anticancer agents. An example for such alkaloids is berberine, an isoquinoline alkaloid, found in roots and stem-bark of Berberis asculin P. Renault plant and used to kill a variety of microorganisms.

Tetrandrine (TET) Induces Death Receptors Apo Trail R1 (DR4) and Apo Trail R2 (DR5) and Sensitizes Prostate Cancer Cells to TRAIL-Induced Apoptosis

TNF-related apoptosis-inducing ligand (TRAIL) selectively induces apoptosis in cancer cells, but not in normal cells; as such, it is a promising therapeutic agent. However, therapeutic resistance limits its clinical use in many malignancies, including prostate cancer. Strategies to sensitize cancer cells to TRAIL are urgently needed. We demonstrate here that small-molecule tetrandrine (TET) potentially sensitizes previously resistant (LNCaP and C4-2B cells) and mildly sensitive (PC3 cells) prostate cancer cells to TRAIL-induced apoptosis, and they do so by upregulating mRNA expression and protein levels of death receptors Apo Trail R1 (DR4) and Apo Trail R2 (DR5). Using shRNA knockdown, we show critical requirement of DR4 and DR5 in sensitization of prostate cancer cells to TRAIL. We show that double knockdown of DR4 and DR5 abrogated the apoptotic effects of TET and TRAIL. We also demonstrate that TET-induced DR4 and DR5 expression is independent of p53 status. Given that loss of p53 is associated with progression of prostate cancer to CRPC and NEPC, our results show that TET, by acting as a TRAIL-sensitizing agent in prostate cancer, could serve as a potential therapeutic agent in CRPC and NEPC, for which there is no cure to date. Mol Cancer Ther; 17(6); 1217-28. ©2018 AACR.

Tetrandrine, a Chinese plant-derived alkaloid, is a potential candidate for cancer chemotherapy

Cancer is a disease caused by the abnormal proliferation and differentiation of cells governed by tumorigenic factors. Chemotherapy is one of the major cancer treatment strategies, and it functions by targeting the physiological capabilities of cancer cells, including sustained proliferation and angiogenesis, the evasion of programmed cell death, tissue invasion and metastasis. Remarkably, natural products have garnered increased attention in the chemotherapy drug discovery field because they are biologically friendly and have high therapeutic effects. Tetrandrine, isolated from the root of Stephania tetrandra S Moore, is a traditional Chinese clinical agent for silicosis, autoimmune disorders, inflammatory pulmonary diseases, cardiovascular diseases and hypertension. Recently, the novel anti-tumor effects of tetrandrine have been widely investigated. More impressive is that tetrandrine affects multiple biological activities of cancer cells, including the inhibition of proliferation, angiogenesis, migration, and invasion; the induction of apoptosis and autophagy; the reversal of multidrug resistance (MDR); and the enhancement of radiation sensitization. This review focuses on introducing the latest information about the anti-tumor effects of tetrandrine on various cancers and its underlying mechanism. Moreover, we discuss the nanoparticle delivery system being developed for tetrandrine and the anti-tumor effects of other bisbenzylisoquinoline alkaloid derivatives on cancer cells. All current evidence demonstrates that tetrandrine is a promising candidate as a cancer chemotherapeutic.

Tetrandrine Induces Apoptosis of Human Nasopharyngeal Carcinoma NPC-TW 076 Cells through Reactive Oxygen Species Accompanied by an Endoplasmic Reticulum Stress Signaling Pathway

Nasopharyngeal carcinoma (NPC) is an epithelial malignancy of the head and neck and the incidence is higher in Southeast Asia. Tetrandrine (TET) is a bisbenzylisoquinoline alkaloid, a natural product, and exhibits biological activities including action against many human cancer cell lines. However, the molecular mechanism of TET-induced cell apoptosis in human NPC cells is still unclear. In the present study, we investigated TET-induced apoptotic cell death and associated possible signal pathways on human nasopharyngeal carcinoma NPC-TW 076 cells in vitro. Phase contrast microscopy was used to examine cell morphology and DAPI staining was used to examine chromatin condensation. Flow cytometry assay was used to measure total viable cells, cell cycle and sub-G₁ phase distribution, reactive oxygen species (ROS), Ca²⁺, and mitochondria membrane potential (ΔΨm) in NPC-TW 076 cells. Results indicate that TET induced cell death through the cell morphological changes, caused G₀/G₁ phase arrest, increased ROS and Ca²⁺ production, and finally caused apoptotic cell death in NPC-TW 076 cells. There was no influence on the level of ΔΨm after TET treatment. Western blotting indicated that TET increased endoplasmic reticulum (ER) stress associated protein expression such as GADD153, GRP78, ATF-6α and ATF-6 βwhich indicated that TET induced cell death through ER stress. ER stress is a potential target in cancer treatment, so the ability of TET to induce ER stress response and to activate programming cell death in NPC-TW 076 cells make this molecule become a promising anticancer agent.

Tetrandrine suppresses human glioma growth by inhibiting cell survival, proliferation and tumour angiogenesis through attenuating STAT3 phosphorylation

Tetrandrine (Tet), a bisbenzylisoquinoline alkaloid, has been reported to possess anti-tumour activity. However, its effects on human glioma remain unknown. In this study, we demonstrated that Tet inhibited human glioma cell growth in vitro and in vivo. It has been hypothesised that Tet inhibits glioma growth by affecting glioma cell survival, proliferation and vasculature in and around the xenograft tumour in the chick CAM model and signal transducer and activator of transcription 3 (STAT3) mediated these activities. Therefore, we conducted a detailed analysis of the inhibitory effects of Tet on cell survival using a TUNEL assay and flow cytometric analysis; on cell proliferation based on the expression of proliferating cell nuclear antigen; and on angiogenesis using a CAM anti-angiogenesis assay. We used western blotting to investigate the role of STAT3 on the anti-glioma activities of Tet. The results revealed that Tet inhibited survival and proliferation in human glioma cells, impaired tumour angiogenesis and decreased the expression of phosphorylated STAT3 and its downstream proteins. In sum, our data indicate that STAT3 is involved in Tet-induced the regression of glioma growth by activating tumour cell apoptosis, inhibiting glioma cell proliferation and inhibiting angiogenesis.

Inhibition of AKT/FoxO3a signaling induced PUMA expression in response to p53-independent cytotoxic effects of H1: A derivative of tetrandrine

PUMA (p53 unregulated modulator of apoptosis), a BH3-only Bcl-2 family member, can be induced by p53-dependent and p53-independent manners. It plays an important role as regulator of cellular apoptosis. Herein, we evaluate the effects of H1 (a derivative of tetrandrine) on induction of PUMA and underlie its potential mechanism in p53-independent cytotoxic response. Anti-proliferative activity and evidently cytotoxic activity of H1 were observed in wild-type and p53 null cells. Further studies demonstrated that H1 resulted in an increase of cleaved PARP, decease of survivin and elevation of p-H2AX. What is more, H1 significantly induced PUMA expression in a concentration- and time-dependent manner and caused an increase of Bax/Bcl-2 ratio in p53 null cells. Of note, knockdown of PUMA attenuated cytotoxic activity of H1. Further studies demonstrated that inhibition of AKT/FoxO3a signaling contributed to H1-mediated PUMA induction. Targeted suppression of AKT/FoxO3a signaling by siRNA could overcome H1-mediated PUMA induction. In addition, H1 significantly suppressed NF-κB activity and caused an increase of early apoptotic and late apoptotic cells, and elevated caspase-3 activity. Taken together, we found that inhibition of AKT/FoxO3a signaling may contribute to H1-mediated PUMA induction, suggesting that inhibition of AKT/FoxO3a signaling result in PUMA expression in response to p53-independent cytotoxic effects of H1.

c-Jun NH2-terminal kinase-induced proteasomal degradation of c-FLIPL/S and Bcl2 sensitize prostate cancer cells to Fas- and mitochondria-mediated apoptosis by tetrandrine

Tetrandrine, a constituent of Chinese herb Stephania tetrandra, causes cell death in prostate cancer, but the molecular mechanisms leading to apoptosis is not known. Here we demonstrated that tetrandrine selectively inhibits the growth of prostate cancer PC3 and DU145 cells compared to normal prostate epithelial PWR-1E cells. Tetrandrine-induced cell death in prostate cancer cells is caused by reactive oxygen species (ROS)-mediated activation of c-Jun NH2-terminal kinase (JNK1/2). JNK1/2-mediated proteasomal degradation of c-FLIPL/S and Bcl2 proteins are key events in the sensitization of prostate cancer cells to Fas- and mitochondria-mediated apoptosis by tetrandrine. Tetrandrine-induced JNK1/2 activation caused the translocation of Bax to mitochondria by disrupting its association with Bcl2 which was accompanied by collapse of mitochondrial membrane potential (MMP), cytosolic release of cytochrome c and Smac, and apoptotic cell death. Additionally, tetrandrine-induced JNK1/2 activation increased the phosphorylation of Bcl2 at Ser70 and facilitated its degradation via the ubiquitin-mediated proteasomal pathway. In parallel, tetrandrine-mediated ROS generation also caused the induction of ligand-independent Fas-mediated apoptosis by activating procaspase-8 and Bid cleavage. Inhibition of procaspase-8 activation attenuated the cleavage of Bid, loss of MMP and caspase-3 activation suggest that tetrandrine-induced Fas-mediated apoptosis is associated with the mitochondrial pathway. Furthermore, most of the signaling effects of tetrandrine on apoptosis were significantly attenuated in the presence of antioxidant N-acetyl-l-cysteine, thereby confirming the involvement of ROS in these events. In conclusion, the results of the present study indicate that tetrandrine-induced apoptosis in prostate cancer cells is initiated by ROS generation and that both intrinsic and extrinsic pathway contributes to cell death.

An efficient Trojan delivery of tetrandrine by poly(N-vinylpyrrolidone)-block-poly(ε-caprolactone) (PVP-b-PCL) nanoparticles shows enhanced apoptotic induction of lung cancer cells and inhibition of its migration and invasion

Earlier studies have demonstrated the promising antitumor effect of tetrandrine (Tet) against a series of cancers. However, the poor solubility of Tet limits its application, while its hydrophobicity makes Tet a potential model drug for nanodelivery systems. We report on a simple way of preparing drug-loaded nanoparticles formed by amphiphilic poly(N-vinylpyrrolidone)-block-poly(ε-caprolactone) (PVP-b-PCL) copolymers with Tet as a model drug. The mean diameters of Tet-loaded PVP-b-PCL nanoparticles (Tet-NPs) were between 110 nm and 125 nm with a negative zeta potential slightly below 0 mV. Tet was incorporated into PVP-b-PCL nanoparticles with high loading efficiency. Different feeding ratios showed different influences on sizes, zeta potentials, and the drug loading efficiencies of Tet-NPs. An in vitro release study shows the sustained release pattern of Tet-NPs. It is shown that the uptake of Tet-NPs is mainly mediated by the endocytosis of nanoparticles, which is more efficient than the filtration of free Tet. Further experiments including fluorescence activated cell sorting and Western blotting indicated that this Trojan strategy of delivering Tet in PVP-b-PCL nanoparticles via endocytosis leads to enhanced induction of apoptosis in the non-small cell lung cancer cell A549 line; enhanced apoptosis is achieved by inhibiting the expression of anti-apoptotic Bcl-2 and Bcl-xL proteins. Moreover, Tet-NPs more efficiently inhibit the ability of cell migration and invasion than free Tet by down-regulating matrix metalloproteinases (MMP)-2 and MMP-9, as well as up-regulating tissue inhibitor of MMP-3 (TIMP-3). Therefore, data from this study not only confirms the potential of Tet in treating lung cancer but also offers an effective way of improving the anticancer efficiency of Tet by nanodrug delivery systems.

Tetrandrine Suppresses Cancer Angiogenesis and Metastasis in 4T1 Tumor Bearing Mice

Metastasis remains the most deadly aspect of cancer and still evades direct treatment. Thus, there is a great need to develop new treatment regimens to suppress tumor cells that have escaped surgical removal or that may have already disseminated. We have found that tetrandrine (TET) exhibits anticolon cancer activity. Here, we investigate the inhibition effect of TET to breast cancer metastasis, angiogenesis and its molecular basis underlying TET's anticancer activity. We compare TET with chemotherapy drug doxorubicin in 4T1 tumor bearing BALB/c mice model and find that TET exhibits an anticancer metastatic and antiangiogenic activities better than those of doxorubicin. The lung metastatic sites were decreased by TET, which is confirmed by bioluminescence imaging in vivo. On the other hand, laser doppler perfusion imaging (LDI) was used for measuring the blood flow of tumor in 4T1-tumor bearing mice. As a result, the local blood perfusion of tumor was markedly decreased by TET after 3 weeks. Mechanistically, TET treatment leads to a decrease in p-ERK level and an increase in NF-κB levels in HUVECs. TET also regulated metastatic and angiogenic related proteins, including vascular endothelial growth factor, hypoxia-inducible factor-1α, integrin β5, endothelial cell specific molecule-1, and intercellular adhesion molecule-1 in vivo.

Enhanced in vitro and in vivo therapeutic efficacy of codrug-loaded nanoparticles against liver cancer

Paclitaxel (Ptx), one of the most widely used anticancer agents, has demonstrated extraordinary activities against a variety of solid tumors. However, the therapeutic response of Ptx is often associated with severe side effects caused by its nonspecific cytotoxic effects and special solvents (Cremophor EL(®)). The current study reports the stable controlled release of Ptx/tetrandrine (Tet)-coloaded nanoparticles by amphilic methoxy poly(ethylene glycol)-poly(caprolactone) block copolymers. There were three significant findings. Firstly, Tet could effectively stabilize Ptx-loaded nanoparticles with the coencapsulation of Tet and Ptx. The influence of different Ptx/Tet feeding ratios on the size and loading efficiency of the nanoparticles was also explored. Secondly, the encapsulation of Tet and Ptx into nanoparticles retains the synergistic anticancer efficiency of Tet and Ptx against mice hepatoma H22 cells. Thirdly, in the in vivo evaluation, intratumoral administration was adopted to increase the site-specific delivery. Ptx/Tet nanoparticles, when delivered intratumorally, exhibited significantly improved antitumor efficacy; moreover, they substantially increased the overall survival in an established H22-transplanted mice model. Further investigation into the anticancer mechanisms of this nanodelivery system is under active consideration as a part of this ongoing research. The results suggest that Ptx/Tet-coloaded nanoparticles could be a potential useful chemotherapeutic formulation for liver cancer therapy.

Alkaloids isolated from natural herbs as the anticancer agents

Alkaloids are important chemical compounds that serve as a rich reservoir for drug discovery. Several alkaloids isolated from natural herbs exhibit antiproliferation and antimetastasis effects on various types of cancers both in vitro and in vivo. Alkaloids, such as camptothecin and vinblastine, have already been successfully developed into anticancer drugs. This paper focuses on the naturally derived alkaloids with prospective anticancer properties, such as berberine, evodiamine, matrine, piperine, sanguinarine, and tetrandrine, and summarizes the mechanisms of action of these compounds. Based on the information in the literature that is summarized in this paper, the use of alkaloids as anticancer agents is very promising, but more research and clinical trials are necessary before final recommendations on specific alkaloids can be made.

Enhancement of radiosensitivity and the potential mechanism on human esophageal carcinoma cells by tetrandrine

The purposes of this study were to test the effect of tetrandrine, alone or combined with radiation, on human esophageal cancer cell line TE1 (TE1 cells) and investigate the potential antitumor mechanism. Human esophageal cancer cell line TE1 was tested by methyl thiazolyl tetrazolium assay for cell proliferation, colony-forming assay for cell radiosensitivity, flow cytometry assay for cell cycle distribution, and western blot assay for cell cycle protein expression. When treated alone, tetrandrine had a time- and concentration-dependent cytotoxic effect on TE1 cells. The dose-enhancement ratio for combined tetrandrine and radiation was markedly increased when compared with tetrandrine alone. Further, expression of cyclin B1 protein increased after addition of tetrandrine when compared with radiation only. Radiation-induced G2 arrest was abrogated with treatment of tetrandrine. In conclusion, tetrandrine can enhance the radiosensitivity of TE1 cells and this may involve relief of radiation-induced G2/M arrest in TE1 cells.

Isoegomaketone induces apoptosis through caspase-dependent and caspase-independent pathways in human DLD1 cells

Isoegomaketone (IK) is an essential oil component of Perilla frutescens (L.), but the mechanism by which IK induces apoptosis has never been studied. The purpose of this study was to elucidate the IK-induced apoptotic pathway in DLD1 human colon cancer cells. We observed that IK treatment over 24 h significantly inhibited cell viability in a dose-dependent manner. We also found that IK triggered cleavage of PARP. Moreover, IK treatment resulted in cleavage of caspase-8, -9, and -3 in a dose- and time-dependent manner. IK treatment also resulted in cleavage of Bid and translocation of Bax, and triggered the release of cytochrome c from the mitochondria to the cytoplasm. Furthermore, it resulted in the translocation of apoptosis inducing factor (AIF), a caspase-independent mitochondrial apoptosis factor, from the mitochondria into the nucleus. Overall, these results suggest that IK induces apoptosis through caspase-dependent and capase-independent pathways in DLD1 cells.

Tetrandrine inhibits Wnt/β-catenin signaling and suppresses tumor growth of human colorectal cancer

As one of the most common malignancies, colon cancer is initiated by abnormal activation of the Wnt/β-catenin pathway. Although the treatment options have increased for some patients, overall progress has been modest. Thus, there is a great need to develop new treatments. We have found that bisbenzylisoquinoline alkaloid tetrandrine (TET) exhibits anticancer activity. TET is used as a calcium channel blocker to treat hypertensive and arrhythmic conditions in Chinese medicine. Here, we investigate the molecular basis underlying TET's anticancer activity. We compare TET with six chemotherapy drugs in eight cancer lines and find that TET exhibits comparable anticancer activities with camptothecin, vincristine, paclitaxel, and doxorubicin, and better than that of 5-fluorouracil (5-FU) and carboplatin. TET IC₅₀ is ≤5 μM in most of the tested cancer lines. TET exhibits synergistic anticancer activity with 5-FU and reduces migration and invasion capabilities of HCT116 cells. Furthermore, TET induces apoptosis and inhibits xenograft tumor growth of colon cancer. TET treatment leads to a decrease in β-catenin protein level in xenograft tumors, which is confirmed by T-cell factor/lymphocyte enhancer factor and c-Myc reporter assays. It is noteworthy that HCT116 cells with allelic oncogenic β-catenin deleted are less sensitive to TET-mediated inhibition of proliferation, viability, and xenograft tumor growth. Thus, our findings strongly suggest that the anticancer effect of TET in colon cancer may be at least in part mediated by targeting β-catenin activity. Therefore, TET may be used alone or in combination as an effective anticancer agent.

CWJ-081, a novel 3-arylisoquinoline derivative, induces apoptosis in human leukemia HL-60 cells partially involves reactive oxygen species through c-Jun NH2-terminal kinase pathway

In the present study, we investigated the effect of a novel 3-arylisoquinoline derivative 3-(6-ethyl-benzo[1,3]dioxol-5-yl)-7,8-dimethoxy-2-methyl-2H-isoquinolin-1-one (CWJ-081) on the induction of apoptosis and the putative molecular mechanism of its action in human leukemia cells. Treatment with CWJ-081 exhibited a characteristic feature of apoptosis including externalization of phosphatidylserine and formation of DNA fragmentation in human leukemia cell lines (HL-60, U-937, K-562). In addition, stimulation of HL-60 cells with CWJ-081 induced a series of intracellular events: (1) the activations of caspase-8, -9, and -3; (2) the cleavage of poly (ADP-ribose) polymerase-1 (PARP-1); (3) the loss of mitochondrial membrane potential (ΔΨ(m)); (4) the release of cytochrome c; and (5) the modulation of Bcl-2 family proteins. We further demonstrated that CWJ-081 induces reactive oxygen species (ROS) production and c-Jun NH(2)-terminal kinase (JNK) activation. Pretreatment with the antioxidant N-acetyl-L-cysteine (NAC) markedly inhibited the CWJ-081-induced JNK activation and apoptosis. Moreover, CWJ-081-induced apoptosis was suppressed in the presence of SP600125, a specific JNK inhibitor. Taken together, these data suggest that CWJ-081 induces apoptosis via the mitochondrial apoptotic pathway in HL-60 cells, and ROS-mediated JNK activation plays a key role in the CWJ-081-induced apoptosis.

Transcriptional profiling and Wnt signaling activation in proliferation of human hepatic stellate cells induced by PDGF-BB

BACKGROUND/AIMS

This study aimed to better understand gene expression profiles of human hepatic stellate cell (HSC) activation and the relationship with the Wnt signaling pathway.

METHODS

The global transcript levels in platelet derived growth factor-BB (PDGF-BB)-stimulated hTERT HSCs were analyzed using oligonucleotide microarrays. Oligonucleotide microarrays with 19K human oligo chips were performed to obtain gene expression profiles associated with proliferation in human hTERT HSCs. The microarray data was verified by real time quantitative PCR and expression of the components of Wnt signaling was analyzed by Western blot.

RESULTS

Microarray data showed 243 up-regulated and 265 down-regulated genes in PDGF-BB-treated HSCs. The changes in expression of glypican3 and BH3 interacting domain death agonist (BID) mRNA in real time quantitative PCR, especially among the highly up- or down-regulated genes, were statistically consistent with the microarray data. The Wnt signaling pathway components, frizzled10 (FZD10) and calcium/calmodulindependent protein kinase II alpha (CAMK2A), showed increased expression in the short time course microarray and the up-regulation of FZD10 also occurred at the protein level. Our data showed various gene expression profiles during activation of human HSC.

CONCLUSIONS

The up-regulated expression of FZD10 and CAMK2A suggests that the Wnt/Ca(2+) signaling pathway is active in hTERT HSCs and may participate in HSC activation and proliferation.

NF-kappaB-dependent anti-inflammatory activity of urolithins, gut microbiota ellagic acid-derived metabolites, in human colonic fibroblasts

Previous studies have reported the anti-inflammatory properties of pomegranate extracts, suggesting that ellagitannins (ET) and ellagic acid (EA) are the main anti-inflammatory compounds. However, both ET and EA are metabolised in vivo by the gut microbiota to yield urolithins (Uro) which can be found in the gut and in systemic bloodstream. The present study was carried out to evaluate the individual effect of EA and their microbiota-derived metabolites Uro on colon fibroblasts upon IL-1beta treatment as an in vitro inflammation model. Uro-A and Uro-B (10 microm) inhibited PGE2 production (85 and 40 %, respectively) after IL-1beta stimulation, whereas EA did not show any effect. Uro-A, but not Uro-B, down-regulated cyclo-oxygenase-2 (COX-2) and microsomal PGE synthase-1 (mPGES-1) mRNA expression and protein levels. Both Uro inhibited NF-kappaB translocation to nucleus. Slight but significant effects were found in the activation of mitogen-activated protein kinase (MAPK) pathways. Uro-A lowered c-Jun N-terminal kinase phosphorylation state, and both Uro inhibited p38 activation. No metabolites derived from Uro or EA were found in the cell media upon incubation of EA or Uro with the cells, and only traces of the compounds were found inside the cells. The present results suggest that Uro, mainly Uro-A, are the main compounds that are responsible for the pomegranate anti-inflammatory properties. The mechanism of action implicated seems to be via the inhibition of activation of NF-kappaB and MAPK, down-regulation of COX-2 and mPGES-1 expressions, and consequently,via the reduction of PGE2 production. Taking into account that Uro did not enter the cells, a competitive binding for IL-1beta membrane receptor cannot be discarded.

alpha-Bisabolol induces dose- and time-dependent apoptosis in HepG2 cells via a Fas- and mitochondrial-related pathway, involves p53 and NFkappaB

In this study, the apoptotic effect of alpha-bisabolol, a sesquiterpene, against human liver carcinoma cell line HepG2 was investigated. MTT assay showed alpha-bisabolol could effectively induce cytotoxicity in several human cancer cell lines (PC-3, Hela, ECA-109 and HepG2). The results of nuclei morphology examination, DNA fragmentation detection, flow cytometry analysis and cleavage of poly(ADP-ribose) polymerase and caspases indicated alpha-bisabolol might induce dose- and time-dependent apoptosis in HepG2 cells. Western blot data also showed a cascade activation of caspases-8,-9,-3 and promoted expression of Fas, implying caspase-8 might function as an upstream regulator, and the Fas-related pathway might be involved in this process. Preparation of mitochondrial/cytosol fraction followed with immunoblot analysis showed the release of chromosome c from mitochondria, down-regulated expression of Bcl-2 and translocation of Bax, Bak and Bid, suggesting the mitochondrial-related pathway might be involved in alpha-bisabolol-induced apoptosis either. Detection of accumulation of nuclear wild-type p53 and up-regulated expression of NFkappaB indicated these two key regulator with transcriptional decision-making function in various signaling pathways might also play a role in alpha-bisabolol-induced apoptosis in HepG2 cells.

Fangchinoline induced G1/S arrest by modulating expression of p27, PCNA, and cyclin D in human prostate carcinoma cancer PC3 cells and tumor xenograft

Prostate cancer (PCA) is the most common invasive malignancy and the second leading cause of cancer-related death in males. The present study investigated the effects of fangchinoline (Fan), an important compound in Stephania Tetradra S. Moore (Fenfangji) with pain-relieving, blood pressure-depressing, and antibiotic activities, on human PCA. It was found that Fan inhibited human prostate cancer cell lines (PC3) cell proliferation in a dose- and time-dependent manner. Studies of cell-cycle progression showed that the anti-proliferative effect of Fan was associated with an increase in the G1/S phase of PC3 cells. Western blot results indicated that Fan-induced G1/S phase arrest was mediated through inhibition of cyclin-regulated signaling pathways. Fan induced p27 expression and inhibited cyclin D and proliferating cell nuclear antigen (PCNA) expression in PC3 cells. Increased exposure time to Fan caused apoptosis of PC3 cells, which was associated with up-regulation of pro-apoptotic proteins Bax and caspase 3, and down-regulation of anti-apoptotic protein Bcl-2. Furthermore, Fan had anti-tumorigenic activity in vivo, including reduction of tumor volume and pro-apoptotic and anti-proliferative effects in a PC3 nude mouse xenograft. Taking all this together, it can be concluded that Fan is an effective anti-proliferative agent that modulates cell growth regulators in prostate cancer cells.

Effect of prenatal tetrandrine administration on transforming growth factor-beta1 level in the lung of nitrofen-induced congenital diaphragmatic hernia rat model

PURPOSE

Tetrandrine (Tet) is a bisbenzylisoquinoline alkaloid isolated from the root of Stephania tetrandra, which has been used in traditional Chinese medicine to treat patients with silicosis, asthma, and pulmonary hypertension, and others and can be used as a pulmonary therapeutic agent. We hypothesized that it can also improve the lung growth in congenital diaphragmatic hernia (CDH) for its multiple biological effects. There are increasing evidences that suggest transforming growth factor beta1(TGF-beta1) plays a crucial role in fetal lung growth and morphogenesis. The aim of this study was to evaluate the effect of prenatal administration of Tet and to investigate its possible mechanism on the expression of TGF-beta1 in the lung of nitrofen-induced CDH rat model.

METHODS

A CDH model was induced in pregnant Sprague-Dawley rats by administration of nitrofen on day 9.5 of gestation (Ed9.5 term, day 22). Tetrandrine (30 mg/kg) was given through gavage (once a day, for 3 days) on Ed11.5. Accordingly, there were 3 groups as follows: control (n = 9), CDH (n = 9), and CDH + Tet (n = 9). All the fetuses were delivered by cesarean delivery on Ed16.5, 18.5, and 21.5, respectively, to check if diaphragmatic hernia existed on each fetus, then the lung tissue weight (LW) and body weight (BW) of each fetus were recorded. Histologic evaluations and TGF-beta1 immunohistochemistry staining in the lung sample were performed for image analysis.

RESULTS

Diaphragmatic hernia was observed in 95 of the 112 rat fetuses in CDH and CDH + Tet groups on Ed18.5 and Ed21.5 (84.8%), the incidence between the 2 groups had no statistical significance (P = .642). Lung weight/body weight in the CDH group and the CDH + Tet group were lower than that in the control group (P < .01), and LW/BW in the CDH group was lower than that in the CDH + Tet group (P < .05). Observed under the light microscope and electron microscope, marked hypoplasia of the lungs in fetuses among the CDH groups was observed, in contrast to improvement of the lungs in CDH + Tet fetuses. Statistical differences in morphological parameters (percentage of alveoli area, counting bronchus) were found even on Ed16.5 when diaphragm had not closed (P < .01). The number of type II pneumocytes and lamellar bodies in each group had no significant difference (P > .05). The immunoreactivity of TGF-beta1 in CDH group and CDH + Tet group were markedly stronger than that in the control group (P < .01). In addition, TGF-beta1 expression in the CDH group was stronger than that in the CDH + Tet group (P < .01).

CONCLUSION

Nitrofen can interfere with lung development early in the fetal rat development before and separate from diaphragm development, and increased expression of TGF-beta1 in the lung of CDH rat model may suppress lung growth and development. Prenatal treatment with Tet can improve the growth of the lung of the nitrofen-induced CDH fetuses and its mechanism seems to be involved in downregulating the expression of TGF-beta1. It is a likely new approach to treat CDH and its coexistent lung hypoplasia by maternal Tet administration.

Stephania tetrandra prevents and regresses liver fibrosis induced by carbon tetrachloride in rats

BACKGROUND AND AIM

There is currently no safe and effective treatment for liver fibrosis. We have previously shown that Stephania tetrandra (ST) and Salvia miltiorrhiza (SM) suppress cell proliferation and enhance apoptosis of hepatic stellate cell (HSC) in vitro. In this study, we aimed to investigate the anti-fibrotic effect of these two herbs in vivo.

METHODS

Liver fibrosis was induced by carbon tetrachloride (CCl(4)) injection in rats for 5 weeks. SM, ST or SM + ST was gavaged on day 1 of CCl(4) administration to study the preventive effects of herbs on hepatic fibrosis. In a separate study designed to assess possible fibrosis regression, rats were randomly allocated to be treated with SM, ST or SM + ST when fibrosis was established. Liver injury and collagen content were assessed. HSC activation and apoptosis were determined.

RESULTS

As compared with the CCL(4)-only rats, serum ALT was significantly lower in CCl(4)-treated rats that received either SM (P < 0.01) or ST (P < 0.01). Administration of ST significantly prevented (P < 0.01) or reversed the hepatic fibrosis (P < 0.01) induced by CCL(4). Moreover, rats treated with ST had reduced protein expression of alpha-SMA both in prevention (P < 0.05) and in regression (P < 0.01) experiments. The double-color staining of alpha-SMA and TUNEL showed that ST increased HSC apoptosis. However, co-treatment of SM + ST did not increase the antifibrotic effect of ST.

CONCLUSIONS

Stephania tetrandra safely and effectively prevents and reverses hepatic fibrosis through activating HSC apoptosis in rats.

Prenatal tetrandrine treatment can reverse the abnormal conditions in the lung of newborn with congenital diaphragmatic hernia

Pulmonary hypoplasia and persistent pulmonary hypertension are the most important reasons for the high morbidity and mortality of congenital diaphragmatic hernia (CDH). Despite surgical advances and advances in neonatal intensive care, the mortality still remains high. Then the research on how to improve prenatal fetal lung growth has become a focus. Some researches involved in fetal surgery, tracheal occlusion, prenatal use of corticosteroids etc., have been carried out in CDH animal models and humans. But the results either showed no benefit for the outcome of CDH or were unproved. Tetrandrine is a bisbenzylisoquinoline alkaloid isolated from the root of Stephania tetrandra. It has been used in traditional Chinese medicine for several decades to treat patients with silicosis, asthma and pulmonary hypertension etc. Some researches showed that prenatal tetrandrine administration can improve the lung development in CDH rat models. We hypothesize that prenatal treatment with tetrandrine can reverse the abnormal condition in the lung of newborn with CDH, and thus decrease the mortality.

Tetrandrine protects mice from concanavalin A-induced hepatitis through inhibiting NF-kappaB activation

Tetrandrine (TET) is the major pharmacologically active compound of Chinese herb Stephania tetrandra S Moore, which has been used traditionally for the treatment of rheumatic disorders, silicosis and hypertension. Concanavalin A (ConA)-induced hepatitis (CIH) is a T-cell-dependent hepatitis and a well-established animal model for studying the mechanisms and therapy of immune-mediated hepatotoxicity. The aim of this study was to investigate whether TET could protect mice from CIH. C57BL/6 mice were injected with ConA to induce CIH pretreated with or without TET. Liver injury was assessed biochemically and histologically. Levels of plasma cytokines and the expressions of chemokine messenger RNA (mRNA) in the liver were determined. We found that pretreatment of mice with TET markedly reduced plasma transaminase release and the severity of liver damage. We further investigated the mechanisms of the protective effects of TET. When CIH-induced mice pretreated with TET, the increases of plasma concentrations of TNF-alpha, IFN-gamma, IL-12 and IL-4 were dramatically attenuated; at the same time, IFN-inducible protein-10 and macrophage inflammatory protein-1alpha expressions in liver were decreased. Furthermore, TET inhibited NF-kappaB activity, the critical transcriptional factor of the above mentioned inflammatory cytokines, by preventing the activation of IkappaBalpha kinasealpha (IKKalpha) and then inhibiting phosphorylation of IkappaBalpha to stabilize IkappaBalpha in intrahepatic leukocytes. In conclusion, TET is able to prevent T-cell-mediated liver injury in vivo. The beneficial effect may depend on suppressing the production of various inflammatory mediators in the liver through inhibiting of NF-kappaB activation.

Effects of tetrandrine on apoptosis and radiosensitivity of nasopharyngeal carcinoma cell line CNE

Tetrandrine is known to exert antitumor effect, however, little is known about its effect on nasopharyngeal carcinoma cells. In this study, we tested tetrandrine-induced apoptosis and radiosensitivity in nasopharyngeal carcinoma cell line CNE and investigated the possible mechanisms. Using flow cytometry and DNA electrophoresis, we found that tetrandrine could induce cell apoptosis. Further, it was shown that the level of Bcl-2 mRNA decreased and Bax mRNA increased after addition of tetrandrine by using reverse transcription-polymerase chain reaction. X-ray-induced G2 arrest was abrogated by treatment with tetrandrine, as detected by flow cytometry and mitotic index. The accumulation of cyclinB1 protein and the suppression of Cdc2 tyrosine-15 and Cdc25C serine-216 phosphorylation were detected in irradiated cells treated with tetrandrine using Western blot analysis. Taken together, these results show that tetrandrine can induce apoptosis and abrogate radiation-induced G2 arrest in CNE cells.

Synergistic interaction between tetrandrine and chemotherapeutic agents and influence of tetrandrine on chemotherapeutic agent-associated genes in human gastric cancer cell lines

PURPOSE

Tetrandrine (Tet), a bis-benzylisoquinoline alkaloid that was isolated from the dried root of Hang-Fang-Chi (Stephania tetrandra S. Moore), is well known as processing a marked antitumor effect in vitro and in vivo. The aim of this study was to assess the interaction between tetrandrine and chemotherapeutic agents widely used in gastric cancer treatment, and to investigate the influence of tetrandrine on chemotherapeutic agent-associated gene expression and apoptosis.

METHODS

Synergistic interaction on human gastric cancer BGC-823 and MKN-28 cells was evaluated using the combination index (CI) method. The double staining with both Annexin-V-FITC and PI was employed to distinguish the apoptotic cells from living cells. Expression of chemotherapeutic agent-associated genes, i.e., excision repair cross-complementing 1 (ERCC1), thymidylate synthase (TS), class III beta-tubulin (beta-tubulin III) and tau, of BGC-823 cells with or without tetrandrine treatment were measured by real-time quantitative PCR.

RESULTS

Tetrandrine had a synergistic effect on the cytotoxicity of chemotherapeutic agents in both two gastric cancer cell lines. The combination of tetrandrine and chemotherapeutic agents could also induce apoptosis in a synergistic manner. Tetrandrine could suppress the mRNA expression of ERCC1, TS, beta-tubulin III and tau. Most prominently, ERCC1, TS and beta-tubulin III mRNA levels were markedly suppressed at 0.29-, 0.12- and 0.60-fold, respectively, by the presentation of tetrandrine.

CONCLUSION

Tetrandrine appears a promising candidate for combining with three chemotherapeutic agents. The possible mechanisms might be the synergistic apoptotic effect and the downregulation of chemotherapeutic agent-associated genes.

Antifibrotic effects of tetrandrine on hepatic stellate cells and rats with liver fibrosis

BACKGROUND

Anti-inflammation strategies are one of the proposed therapeutic approaches to hepatic fibrosis. Tetrandrine (C(38)H(42)O(8)N(2), molecular weight: 622; Tet), an alkaloid isolated from the Chinese medicinal herb Stephania tetrandra, has been shown to exert anti-inflammatory activity in pulmonary diseases. The purpose of the present study was to investigate the in vitro and in vivo effects of Tet on hepatic fibrosis.

METHODS

A cell line of rat hepatic stellate cells (HSC-T6) was stimulated with transforming growth factor-beta1 (TGF-beta1) or tumor necrosis factor-alpha (TNF-alpha). The inhibitory effects of Tet on the nuclear factor kappaB (NFkappaB) signaling cascade and molecular markers including intercellular adhesion molecule-1 (ICAM-1) and alpha-smooth muscle actin (alpha-SMA) secretion were assessed. Fibrosis was induced by dimethylnitrosamine (DMN) administration in rats for 4 weeks. Fibrotic rats were randomly assigned to one of the four groups: vehicle (0.7% carboxyl methyl cellulose, CMC), Tet (1 mg/kg), Tet (5 mg/kg), or silymarin (50 mg/kg), each given by gavage twice daily for 3 weeks starting after 1 week of DMN administration. At the end of the study, liver tissues were scored for fibrosis and analyzed for molecular markers of fibrosis.

RESULTS

Tetrandrine (0.5-5.0 micromol/L) concentration-dependently inhibited NFkappaB transcriptional activity induced by TNF-alpha, including IkappaBalpha phosphorylation and mRNA expressions of ICAM-1 in HSC-T6 cells. In addition, Tet also inhibited TGF-beta1-induced alpha-SMA secretion and collagen deposition in HSC-T6 cells. Fibrosis scores of livers from DMN-treated rats with high-dose Tet (1.3 +/- 0.3) were significantly reduced in comparison with DMN-treated rats receiving saline (2.0 +/- 0.2). Hepatic collagen content of DMN rats was significantly reduced by either Tet or silymarin treatment. Double-staining results showed that alpha-SMA- and NFkappaB-positive cells were decreased in the fibrotic livers by Tet and silymarin treatment. In addition, mRNA expression of ICAM-1, alpha-SMA, and TGF-beta1 was attenuated by Tet treatment. Moreover, levels of plasma aspartate aminotransferase and alanine aminotransferase activities were reduced by Tet and silymarin treatment.

CONCLUSION

Tetrandrine exerts antifibrotic effects in both HSC-T6 cells and in rats with DMN-induced fibrosis.

Tetrandrine concentrations not affecting oxidative phosphorylation protect rat liver mitochondria from oxidative stress

The effects of tetrandrine (6,6', 7,12-tetramethoxy-2, 2'-dimethyl-berbaman) on the mitochondrial function were assessed on oxidative stress, mitochondrial permeability transition (MPT), and bioenergetics of rat liver mitochondria. At concentrations lower than 100 nmol/mg protein, tetrandrine decreased the hydrogen peroxide formation, the extent of lipid peroxidation, the susceptibility to Ca(2+)-induced opening of MPT pore, and inhibited the inner membrane anion channel activity, not significantly affecting the mitochondrial bioenergetics. High tetrandrine concentrations (100-300 nmol/mg protein) stimulated succinate-dependent state 4 respiration, while some inhibition was observed for state 3 and p-trifluoromethoxyphenylhydrazone-uncoupled respirations. The respiratory control ratio and the transmembrane potential were depressed but the adenosine diphosphate to oxygen (ADP/O) ratio was less affected. A slight increase of the inner mitochondrial membrane permeability to H(+) and K(+) by tetrandrine was also observed. It was concluded that low concentrations of tetrandrine afford protection against liver mitochondria injury promoted by oxidative-stress events, such as hydrogen peroxide production, lipid peroxidation, and induction of MPT. Conversely, high tetrandrine concentrations revealed toxicological effects expressed by interference with mitochondrial bioenergetics, as a consequence of some inner membrane permeability to H(+) and K(+) and inhibition of the electron flux in the respiratory chain. The direct immediate protective role of tetrandrine against mitochondrial oxidative stress may be relevant to clarify the mechanisms responsible for its multiple pharmacological actions.

Inhibitory effects of tetrandrine combined with octreotide on proliferation of gastric cancer cell lines cultured in vitro

AIM: To observe the inhibitory effects of tetrandrine (Tet), octreotide alone and in combination on the gastric cancer cell lines cultured in vitro, and to explore their possible mechanisms.

METHODS: The human gastric cell lines SGC7901 and MKN45 were cultured in vitro. The influences of Tet, octreotide alone and in combination on both kinds of the cells were observed by MTT spectrophotometry, and their effects on the concentration of cytosolic free Ca²⁺ were measured by Fura-2/AM.

RESULTS: Octreotide at high concentrations such as 2.4×10^-5, 2.4×10^-6mol/L, and Tet at concentrations of 10-160 μmol/L significantly inhibited the proliferation of SGC7901 and MKN45 cells, and the inhibitory rates (IR) were 40.76%, 23.2% and 30.5-70.0% for the former, respectively, and 24.9%, 21.7% and 20.4-79.01% for the latter, respectively (P < 0.05 or P < 0.01). Different concentrations of octreotide (2.4×10^-6, 2.4×10^-9, 2.4×10^-12 mol/L) increased the IR of Tet (10 μmol/L) for SGC7901 and MKN45 cells from 32.8% and 27.0% to 50.5% and 60.3%, 55.0% and 47.7%, 67.8% and 63.0%, respectively (P < 0.05 or P < 0.01). The concentrations of free Ca²⁺ in SGC 7901 and MKN 45 cells were significantly reduced as compared with those in the normal controls (394.2±18.4 nmol/L vs 505.0±15.8 nmol/L, 412.1±20.8 nmol/L vs 512.0±16.0 nmol/L, both P < 0.01), and similar results were found in octreotide (2.4×10^-6 mol/L) group (SGC7901: 450.8±20.1 nmol/L, P < 0.01; MKN45: 413.1±10.4 nmol/L, P < 0.01). However, octreotide combined with Tet could not reduce the concentration of free Ca²⁺ to a lower degree.

CONCLUSION: Tet inhibits the proliferation of gastric cancer cell lines cultured in vitro in a dose-dependent manner, and the reduction of the cytosolic free Ca²⁺ concentration may be involved in its anti-proliferation mechanism. The antiproliferation of octreotide at high concentrations may relate to its anti-calcium effect. Different concentrations of octreotide can enhance the anti-proliferation of Tet at low doses, which may not relate to the reduction of the cytosolic calcium concentration.

The dietary hydrolysable tannin punicalagin releases ellagic acid that induces apoptosis in human colon adenocarcinoma Caco-2 cells by using the mitochondrial pathway

Polyphenol-rich dietary foodstuffs have attracted attention due to their cancer chemopreventive and chemotherapeutic properties. Ellagitannins (ETs) belong to the so-called hydrolysable tannins found in strawberries, raspberries, walnuts, pomegranate, oak-aged red wine, etc. Both ETs and their hydrolysis product, ellagic acid (EA), have been reported to induce apoptosis in tumour cells. Ellagitannins are not absorbed in vivo but reach the colon and release EA that is metabolised by the human microflora. Our aim was to investigate the effect of a dietary ET [pomegranate punicalagin (PUNI)] and EA on human colon cancer Caco-2 and colon normal CCD-112CoN cells. Both PUNI and EA provoked the same effects on Caco-2 cells: down-regulation of cyclins A and B1 and upregulation of cyclin E, cell-cycle arrest in S phase, induction of apoptosis via intrinsic pathway (FAS-independent, caspase 8-independent) through bcl-XL down-regulation with mitochondrial release of cytochrome c into the cytosol, activation of initiator caspase 9 and effector caspase 3. Neither EA nor PUNI induced apoptosis in normal colon CCD-112CoN cells (no chromatin condensation and no activation of caspases 3 and 9 were detected). In the case of Caco-2 cells, no specific effect can be attributed to PUNI since it was hydrolysed in the medium to yield EA, which entered into the cells and was metabolised to produce dimethyl-EA derivatives. Our study suggests that the anticarcinogenic effect of dietary ETs could be mainly due to their hydrolysis product, EA, which induced apoptosis via mitochondrial pathway in colon cancer Caco-2 cells but not in normal colon cells.

Upregulation of Fas/Fas ligand-mediated apoptosis by gossypol in an immortalized human alveolar lung cancer cell line

Gossypol has wide antineoplastic effects in vitro, but its effects on human lung cancer have not been explored. To evaluate the activity of gossypol against alveolar cell lung cancer and to provide information on the mechanism of action, we examined the effects of gossypol on the proliferation of A549 cells indirectly using an XTT assay and on the distribution of cells within the phases of the cell cycle using flow cytometry. We also examined several factors that may affect apoptosis, including p53, p21/WAF1, Fas receptor, Fas ligand (FasL) and caspase 8 activity. The results showed that gossypol inhibited proliferation of A549 cells at a concentration of 0.5 micromol/L after 12 h treatment. The effect was both dose- and time-dependent by the induction of apoptosis without the effect of p53 and p21/WAF1. Upregulation of Fas/FasL, in association with the activation of downstream caspase 8 activity, was observed following treatment with gossypol. The Fas/FasL pathway accounted for 75% of gossypol-mediated apoptosis. We suggest that the Fas/FasL apoptotic system is the major pathway for gossypol-mediated apoptosis of A549 cells. Gossypol had no effect on the distribution of A549 cells within the phases of the cell cycle. In conclusion, gossypol inhibited A549 cells mainly by induction of the Fas/FasL apoptotic pathway, but not the p53 and p21/WAF1 pathway.

The antiproliferative activity of saponin-enriched fraction from Bupleurum Kaoi is through Fas-dependent apoptotic pathway in human non-small cell lung cancer A549 cells

Bupleuri Radix (Chai-hu in Chinese and Saiko in Japanese) is one of the most important traditional Chinese crude drugs for treating hepatitis malaria and intermittent fever. B. kaoi is one of the Bupleurum spp. families locally found in Taiwan. The effects of saponin-enriched fraction (SEF) from Bupleurum Kaoi in human non-small cell lung cancer A549 cells were investigated in this study. An enhancement in Fas and its two forms of ligands, membrane-bound Fas ligand (mFasL) and soluble Fas ligand (sFasL), was responsible for the apoptotic effect induced by SEF. Taken together, our study suggests that the activity of the Fas/Fas ligand apoptotic system may participate in the antiproliferative activity of SEF in A549 cells.

Tetrandrine induces early G1 arrest in human colon carcinoma cells by down-regulating the activity and inducing the degradation of G1-S-specific cyclin-dependent kinases and by inducing p53 and p21Cip1

Tetrandrine is an antitumor alkaloid isolated from the root of Stephania tetrandra. We find that micromolar concentrations of tetrandrine irreversibly inhibit the proliferation of human colon carcinoma cells in MTT and clonogenic assays by arresting cells in G(1). Tetrandrine induces G(1) arrest before the restriction point in nocodazole- and serum-starved synchronized HT29 cells, without affecting the G(1)-S transition in aphidicolin-synchronized cells. Tetrandrine-induced G(1) arrest is followed by apoptosis as shown by fluorescence-activated cell sorting, terminal deoxynucleotidyl transferase-mediated nick end labeling, and annexin V staining assays. Tetrandrine-induced early G(1) arrest is mediated by at least three different mechanisms. First, tetrandrine inhibits purified cyclin-dependent kinase 2 (CDK2)/cyclin E and CDK4 without affecting significantly CDK2/cyclin A, CDK1/cyclin B, and CDK6. Second, tetrandrine induces the proteasome-dependent degradation of CDK4, CDK6, cyclin D1, and E2F1. Third, tetrandrine increases the expression of p53 and p21(Cip1) in wild-type p53 HCT116 cells. Collectively, these results show that tetrandrine arrests cells in G(1) by convergent mechanisms, including down-regulation of E2F1 and up-regulation of p53/p21(Cip1).

The proliferative inhibition and apoptotic mechanism of Saikosaponin D in human non-small cell lung cancer A549 cells

Saikosaponin D is a saponin extract derived from several species of Bupleurum (Umbelliferae), which is used for the treatment of various liver diseases in traditional Chinese medicine. In this study, we report that Saikosaponin D inhibits the cell growth of human lung cancer cell line A549 and provide a molecular understanding of this effect. The results showed that Saikosaponin D inhibited the proliferation of A549 by inducing apoptosis and blocking cell cycle progression in the G1 phase. ELISA assay showed that Saikosaponin D significantly increased the expression of p53 and p21/WAF1 protein, contributing to cell cycle arrest. An enhancement in Fas/APO-1 and its two form ligands, membrane-bound Fas ligand (mFasL) and soluble Fas ligand (sFasL), as well as Bax protein, was responsible for the apoptotic effect induced by Saikosaponin D. Taken together, our study suggests that the induction of p53 and activity of the Fas/FasL apoptotic system may participate in the antiproliferative activity of Saikosaponin D in A549 cells.

Tetrandrine-induced apoptosis is mediated by activation of caspases and PKC-δ in U937 cells

Tetrandrine, which is isolated from Chinese herb Stephania tetrandrae, possesses anti-inflammatory, immunosuppressive, and cytoprotective properties. Though it was previously shown that tetrandrine causes a G1 blockade and apoptosis in various cell types, however, the mechanism by which tetrandrine initiates apoptosis remains poorly understood. In present study, we investigated the mechanisms of apoptosis induced by tetrandrine in U937 leukemia cells. Tetrandrine inhibited U937 cell growth by inducing apoptosis. After treatment of U937 cells with tetrandrine (10microM) for 24h, alteration of cell morphology, chromatin fragmentation, cytochrome c release, and caspase activation were observed. Tetrandrine also induced early oxidative stress, which resulted in activation of JNK, but not ERK and p38 MAPK. A broad-spectrum caspase inhibitor and antioxidants significantly blocked tetrandrine-induced caspase-3 activation. However, inhibition of the JNK activity with SP600125 did not block tetrandrine-induced apoptosis. Tetrandrine-induced apoptosis of U937 cells also required activity of PKC-delta, because pretreatment with a specific PKC-delta inhibitor greatly blocked tetrandrine-induced caspase-3 activation. In addition, the apoptotic response to tetrandrine was significantly attenuated in dominant-negative PKC-delta transfected MCF-7 cells, suggesting that PKC-delta plays an important role in tetrandrine-induced apoptosis and can induce caspase activation. These results suggest that tetrandrine induces oxidative stress, JNK activation, and caspase activation. However, JNK activation by ROS is not involved in the tetrandrine-induced apoptosis. In addition, tetrandrine induces caspase-dependent generation of a catalytically active fragment of PKC-delta, and this fragment also appears to play a role in the activation of caspases.