Salinomycin simultaneously induces apoptosis and autophagy through generation of reactive oxygen species in osteosarcoma U2OS cells.

Salinomycin, a polyether antibiotic, acts as a highly selective potassium ionophore. It was reported to anticancer activity on various cancer cell lines. In this study, salinomycin was examined on apoptosis and autophagy through generation of reactive oxygen species (ROS) in osteosarcoma U2OS cells. Apoptosis, autophagy, mitochondrial membrane potential (MMP) and ROS were analyzed using flow cytometry. Also, expressions of apoptosis- and autophagy-related proteins were determined by western blotting. As a result, salinomycin triggered apoptosis of U2OS cells, which was accompanied by change of MMP and cleavage of caspases-3 and poly (ADP-ribose) polymerase. And salinomycin increased the expression of autophagy-related protein and accumulation of acidic vesicular organelles (AVO). Salinomycin-induced ROS production promotes both apoptosis and autophagy, as evidenced by the result that treatment of N-acetyl-l-cysteine (NAC), a ROS scavenger, attenuated both apoptosis and autophagy. In addition, inhibition of autophagy by 3-methyladenine (3 MA) enhanced the salinoymcin-induced apoptosis. Taken together, these results suggested that salinomycin-induced autophagy, as a survival mechanism, might be a potential strategy through ROS regulation in cancer therapy.

Silibinin induces mitochondrial NOX4-mediated endoplasmic reticulum stress response and its subsequent apoptosis.

BACKGROUND: Silibinin, a biologically active compound of milk thistle, has chemopreventive effects on cancer cell lines. Recently it was reported that silibinin inhibited tumor growth through activation of the apoptotic signaling pathway. Although various evidences showed multiple signaling pathways of silibinin in apoptosis, there were no reports to address the clear mechanism of ROS-mediated pathway in prostate cancer PC-3 cells. Several studies suggested that reactive oxygen species (ROS) play an important role in various signaling cascades, but the primary source of ROS was currently unclear. METHODS: The effect of silibinin was investigated on cell growth of prostate cell lines by MTT assay. We examined whether silibinin induced apoptosis through production of ROS using flow cytometry. Expression of apoptosis-, endoplasmic reticulum (ER)-related protein and gene were determined by western blotting and RT-PCR, respectively. RESULTS: Results showed that silibinin triggered mitochondrial ROS production through NOX4 expression and finally led to induce apoptosis. In addition, mitochondrial ROS caused ER stress through disruption of Ca(2+) homeostasis. Co-treatment of ROS inhibitor reduced the silibinin-induced apoptosis through the inhibition of NOX4 expression, resulting in reduction of both Ca(2+) level and ER stress response. CONCLUSIONS: Taken together, silibinin induced mitochondrial ROS-dependent apoptosis through NOX4, which is associated with disruption of Ca(2+) homeostasis and ER stress response. Therefore, the regulation of NOX4, mitochondrial ROS producer, could be a potential target for the treatment of prostate cancer.

Pipernonaline from Piper longum Linn. induces ROS-mediated apoptosis in human prostate cancer PC-3 cells.

The antiproliferation effects of pipernonaline, a piperine derivative, were investigated on human prostate cancer PC-3 cells. It inhibited growth of androgen independent PC-3 and androgen dependent LNCaP prostate cells in a dose-dependent (30-90 µM) and time-dependent (24-48 h) manner. The growth inhibition of PC-3 cells was associated with sub-G(1) and G(0)/G(1) accumulation, confirmed by the down-regulation of CDK2, CDK4, cyclin D1 and cyclin E, which are correlated with G(1) phase of cell cycle. Pipernonaline up-regulated cleavage of procaspase-3/PARP, but did not change expression of proapoptotic bax and antiapoptotic bcl-2 proteins. Its caspase-3 activation was confirmed by the caspase-3 assay kit. In addition, pipernonaline caused the production of reactive oxygen species (ROS), increase of intracellular Ca(2+), and mitochondrial membrane depolarization, which these phenomena were reversed by N-acetylcysteine, a ROS scavenger. The results suggest that pipernonaline exhibits apoptotic properties through ROS production, which causes disruption of mitochondrial function and Ca(2+) homeostasis and leads to its downstream events including activation of caspase-3 and cleavage of PARP in PC-3 cells. This is the first report of pipernonaline toward the anticancer activity of prostate cancer cells, which provides a role for candidate agent as well as the molecular basis for human prostate cancer.

Salinomycin-induced apoptosis of human prostate cancer cells due to accumulated reactive oxygen species and mitochondrial membrane depolarization.

The anticancer activity of salinomycin has evoked excitement due to its recent identification as a selective inhibitor of breast cancer stem cells (CSCs) and its ability to reduce tumor growth and metastasis in vivo. In prostate cancer, similar to other cancer types, CSCs and/or progenitor cancer cells are believed to drive tumor recurrence and tumor growth. Thus salinomycin can potentially interfere with the end-stage progression of hormone-indifferent and chemotherapy-resistant prostate cancer. Androgen-responsive (LNCaP) and androgen-refractive (PC-3, DU-145) human prostate cancer cells showed dose- and time-dependent reduced viability upon salinomycin treatment; non-malignant RWPE-1 prostate cells were relatively less sensitive to drug-induced lethality. Salinomycin triggered apoptosis of PC-3 cells by elevating the intracellular ROS level, which was accompanied by decreased mitochondrial membrane potential, translocation of Bax protein to mitochondria, cytochrome c release to the cytoplasm, activation of the caspase-3 and cleavage of PARP-1, a caspase-3 substrate. Expression of the survival protein Bcl-2 declined. Pretreatment of PC-3 cells with the antioxidant N-acetylcysteine prevented escalation of oxidative stress, dissipation of the membrane polarity of mitochondria and changes in downstream molecular events. These results are the first to link elevated oxidative stress and mitochondrial membrane depolarization to salinomycin-mediated apoptosis of prostate cancer cells.

Effect of Phellius linteus water extract on benign prostatic hyperplasia.

Benign prostatic hyperplasia (BPH) is one of the most common diseases among elderly men. As the old-age population is increasing recently, it is to our interest to observe the growing BPH within them. In BPH, the dihydrotestosterone (DHT) acts as promotes prostate growth. It inhibits enzyme 5α-reductase that is involved in the conversion of testosterone to the DHT activity which reduces the excessive prostate growth. Through experiments, the effects of Phellius linteus water extract performed on the BPH rats were induced by testosterone treatments. For 12 weeks, Sprague-Dawley rats were treated with testosterone for the induction of BPH. Rats were divided into four experimental groups: the not treated group (N), the testosterone injection and D.W treatment group (TN), the testosterone injection and Phellinus linteus treatment group (TP) and testosterone injection and finasteride treatment group (TF). Prostate weight, volume and weight ratio in the TP group and the TF group were significantly lower than the TN group. Testosterone and DHT levels in the TN group were significantly higher than that of the N group. And the TP group was significantly decreased than that of the TN group. While prostates of control rats revealed severe acinar gland atrophy and stromal proliferation; the TP and TF groups showed trophic symptoms and were lined by flattened epithelial cells, thus, the stromal proliferation is relatively low as compared to the TN group. These suggest that Phellinus linteus water extracts may be an useful remedy for treating the benign prostatic hyperplasia.

Topical application of Pleurotus eryngii extracts inhibits 2,4-dinitrochlorobenzene-induced atopic dermatitis in NC/Nga mice by the regulation of Th1/Th2 balance.

Pleurotus eryngii is a nutritional and medicinal food rich in polysaccharides that enhance the host immune system as a response to various diseases. The present study investigated the effects of P. eryngii extracts (PEE) on the progress of atopic dermatitis (AD)-like skin lesions in NC/Nga mice induced by 2,4-dinitrochlorobenzene (DNCB). We evaluated skin dermatitis severity, ear thickness, histopathological examination, and cytokines level in DNCB-applied mice treated with PEE. Continuous treatment of PEE inhibited the development of the AD-like skin lesions. PEE suppressed DNCB-induced dermatitis severity, serum level of IgE and thymus and activation-regulated chemokine (TARC), and mRNA expression of TNF-α, INF-γ, IL-4, IL-5, and IL-13 in mice. In addition, PEE reduced thickness of the dermis and dermal infiltration of inflammatory cells and mast cells in histopathological examination. These results indicate that PEE inhibits allergic contact dermatitis through the modulating of T helper (Th)1 and Th2 responses and diminishing the inflammatory cells and mast cells infiltration in the skin lesions in NC/Nga mice.

Inhibitory effect of Pleurotus eryngii extracts on the activities of allergic mediators in antigen-stimulated mast cells.

Pleurotus eryngii is an edible mushroom native to Europe, the Middle East, and North Africa, and is also grown in parts of Asia. The present study investigated the anti-allergy potential of P. eryngii extract (PEE) in antigen-stimulated RBL-2H3 mast cells. PEE inhibited allergy markers, including release of hexosaminidase and histamine, in antigen-sensitized RBL-2H3 cells. PEE also suppressed the expression and production of interleukin-4 and reduced antigen-induced NFAT and NF-κB transcriptional activity in antigen-sensitized mast cells. Moreover, PEE decreased the levels of proinflammatory cytokines and COX-2 and iNOS expression in antigen-sensitized mast cells. Finally, PEE suppressed antigen-induced signal protein phosphorylation of Lyn, PLCγ2, PKC, Akt, and MAP kinases. Taken together, these results suggest that P. eryngii extract may provide insight into the prevention and treatment of allergic and inflammatory diseases.

Ethyl acetate extract of Psidium guajava inhibits IgE-mediated allergic responses by blocking FcεRI signaling.

Psidium guajava (P. guajava) is an important food crop and medicinal plant with antioxidant, anti-inflammatory, and anti-allergic activities, supporting its traditional uses. However, its precise effects remain unknown. We investigated the effects of P. guajava ethyl acetate extract (PGEA) on IgE-mediated allergic responses in rat mast RBL-2H3 cells. PGEA reduced antigen (DNP-BSA)-induced release of ß-hexosaminidase and histamine in IgE-sensitized RBL-2H3 cells. In addition, it inhibited antigen-induced IL-4 and TNF-α mRNA expression and protein production in IgE-sensitized RBL-2H3 cells. PGEA also suppressed antigen-induced COX-2 mRNA and protein expression in these cells, as well as antigen-induced activation of NFAT and reactive oxygen species. Moreover, it inhibited antigen-induced activation of NF-κB and degradation of IκB-α. To identify the mechanisms underpinning the inhibition of degranulation and cytokine production by PGEA, we examined the activation of intracellular FcεRI signaling molecules. PGEA suppressed antigen-induced phosphorylation of Syk, LAT, Gab2, and PLCγ2 but not Lyn, and inhibited antigen-induced phosphorylation of downstream signaling intermediates including MAP kinases and Akt. Collectively, the anti-allergic effects of PGEA in vitro suggest its possible therapeutic application to inflammatory allergic diseases, in which its inhibition of inflammatory cytokine production and FcεRI-dependent signaling events in mast cells may be hugely beneficial.

Identification of potential DREB2C targets in Arabidopsis thaliana plants overexpressing DREB2C using proteomic analysis.

The dehydration responsive element binding protein 2C (DREB2C) is a dehydration responsive element/C-repeat (DRE/CRT)-motif binding transcription factor that induced by mild heat stress. Previous experiments established that overexpression of DREB2C cDNA driven by the cauliflower mosaic virus 35S promoter (35S:DREB2C) resulted in increased heat tolerance in Arabidopsis. We first analyzed the proteomic profiles in wild-type and 35S:DREB2C plants at a normal temperature (22 degrees C), but could not detect any differences between the proteomes of wild-type and 35S:DREB2C plants. The transcript level of DREB2C in 35S:DREB2C plants after treatment with mild heat stress was increased more than two times compared with expression in 35S:DREB2C plants under unstressed condition. A proteomic approach was used to decipher the molecular mechanisms underlying thermotolerance in 35S:DREB2C Arabidopsis plants. Eleven protein spots were identified as being differentially regulated in 35S:DREB2C plants. Moreover, in silico motif analysis showed that peptidyl-prolyl isomerase ROC4, glutathione transferase 8, pyridoxal biosynthesis protein PDX1, and elongation factor Tu contained one or more DRE/CRT motifs. To our knowledge, this study is the first to identify possible targets of DREB2C transcription factors at the protein level. The proteomic results were in agreement with transcriptional data.