Glioblastoma multiforme (GBM) is the most malignant and aggressive primary brain tumor in adults. Despite concerted efforts to improve current therapies, the prognosis of glioblastoma remains very poor. Alantolactone, a sesquiterpene lactone compound, has been reported to exhibit antifungal, antibacteria, antihelminthic, and anticancer properties. In this study, we found that alantolactone effectively inhibits growth and triggers apoptosis in glioblastoma cells in a time‐ and dose‐dependent manner. The alantolactone‐induced apoptosis was found to be associated with glutathione (GSH) depletion, reactive oxygen species (ROS) generation, mitochondrial transmembrane potential dissipation, cardiolipin oxidation, upregulation of p53 and Bax, downregulation of Bcl‐2, cytochrome c release, activation of caspases (caspase 9 and 3), and cleavage of poly (ADP‐ribose) polymerase. This alantolactone‐induced apoptosis and GSH depletion were effectively inhibited or abrogated by a thiol antioxidant, N‐acetyl‐L‐cysteine, whereas other antioxidant (polyethylene glycol (PEG)‐catalase and PEG‐superoxide‐dismutase) did not prevent apoptosis and GSH depletion. Alantolactone treatment inhibited the translocation of NF‐κB into nucleus; however, NF‐κB inhibitor, SN50 failed to potentiate alantolactone‐induced apoptosis indicating that alantolactone induces NF‐κB‐independent apoptosis in glioma cells. These findings suggest that the sensitivity of tumor cells to alantolactone appears to results from GSH depletion and ROS production. Furthermore, our in vivo toxicity study demonstrated that alantolactone did not induce significant hepatotoxicity and nephrotoxicity in mice. Therefore, alantolactone may become a potential lead compound for future development of antiglioma therapy. © © 2012 IUBMB Life, 64(9): 783–794, 2012

The early maize (Zea mays) seed undergoes several developmental stages after double fertilization to become fully differentiated within a short period of time, but the genetic control of this highly dynamic and complex developmental process remains largely unknown. Here, we report a high temporal-resolution investigation of transcriptomes using 31 samples collected at an interval of 4 or 6 h within the first six days of seed development. These time-course transcriptomes were clearly separated into four distinct groups corresponding to the stages of double fertilization, coenocyte formation, cellularization, and differentiation. A total of 22,790 expressed genes including 1415 transcription factors (TFs) were detected in early stages of maize seed development. In particular, 1093 genes including 110 TFs were specifically expressed in the seed and displayed high temporal specificity by expressing only in particular period of early seed development. There were 160, 22, 112, and 569 seed-specific genes predominantly expressed in the first 16 h after pollination, coenocyte formation, cellularization, and differentiation stage, respectively. In addition, network analysis predicted 31,256 interactions among 1317 TFs and 14,540 genes. The high temporal-resolution transcriptome atlas reported here provides an important resource for future functional study to unravel the genetic control of seed development.

Isoalantolactone, a sesquiterpene lactone compound possesses antifungal, antibacteria, antihelminthic and antiproliferative activities. In the present study, we found that isoalantolactone inhibits growth and induces apoptosis in pancreatic cancer cells. Further mechanistic studies revealed that induction of apoptosis is associated with increased generation of reactive oxygen species, cardiolipin oxidation, reduced mitochondrial membrane potential, release of cytochrome c and cell cycle arrest at S phase. N-Acetyl Cysteine (NAC), a specific ROS inhibitor restored cell viability and completely blocked isoalantolactone-mediated apoptosis in PANC-1 cells indicating that ROS are involved in isoalantolactone-mediated apoptosis. Western blot study showed that isoalantolactone increased the expression of phosphorylated p38 MAPK, Bax, and cleaved caspase-3 and decreased the expression of Bcl-2 in a dose-dependent manner. No change in expression of phosphorylated p38 MAPK and Bax was found when cells were treated with isoalantolactone in the presence of NAC, indicating that activation of these proteins is directly dependent on ROS generation. The present study provides evidence for the first time that isoalantolactone induces ROS-dependent apoptosis through intrinsic pathway. Furthermore, our in vivo toxicity study demonstrated that isoalantolactone did not induce any acute or chronic toxicity in liver and kidneys of CD1 mice at dose of 100 mg/kg body weight. Therefore, isoalantolactone may be a safe chemotherapeutic candidate for the treatment of human pancreatic carcinoma.

Drought is a major abiotic stress that affects plant growth, production, and survival. Plants have evolved sophisticated and highly complex reactions to drought stress, including large-scale transcriptome reconfiguration. Foxtail millet (Setaria italica) is a member of the Poaceae family. Because of its outstanding tolerance to drought stress foxtail millet has the potential to become a new model organism. To enrich our knowledge of the processes that contribute to drought resistance, we have used a deep sequencing approach to generate a genome-wide transcriptome of foxtail millet after exposure to simulated drought stress. A large number of differentially expressed genes were characterized; in particular, we examined the roles of small interfering RNAs (siRNAs) and long noncoding RNAs (lncRNAs) in response to a water-deficit condition. These RNAs have remained largely unexplored in previous studies of stress-induced transcriptomes. We found that the reduced levels of 24-nt siRNA flanking genes were associated, for the most part, with proximal up-regulated genes, indicating a potential effect of 24-nt siRNAs on drought-regulated gene expression. Several lncRNAs that responded to the simulated drought stress were also identified, and we found that one of them shared sequence conservation and colinearity with its counterpart in sorghum (Sorghum bicolor). Our findings provide new insights into drought-induced changes in the foxtail millet transcriptome.

Dracorhodin perchlorate has been recently shown to induce apoptotic cell death in cancer cells. However, the molecular mechanisms underlying these effects are unknown in human gastric tumor cells. In this study, effects of Dracorhodin perchlorate on cell viability, cell cycle, and apoptosis were investigated in SGC-7901 cells. The results showed that Dracorhodin perchlorate induced cellular and DNA morphological changes and decreased the viability of SGC-7901 cells. Dracorhodin perchlorate-mediated cell cycle arrest was associated with a marked decrease in protein levels of phosphorylated retinoblastoma and E2F1. Dracorhodin perchlorate-induced apoptosis is mediated via upregulation of p53, inhibiting the activation of PI3K/Akt, and NF-κB, thereby decreasing the expression of the anti-apoptotic proteins, Bcl-2 and Bcl-XL. Interestingly, we also found that Dracorhodin perchlorate significantly suppressed the IGF-1-induced phosphorylation of Akt in the stably expressing EGFP-Akt recombinant CHO-hIR cells and inhibited TNF-induced NF-κB transcriptional activity in the NF-κBp65-EGFP recombinant U2OS cells, indicating that inhibition of PI3K/Akt and NF-κB may provide a molecular basis for the ability of Dracorhodin perchlorate to induce apoptosis. Dracorhodin perchlorate induced up-regulation of p53, thereby resulting in the activation of its downstream targets p21 and Bax following the dissipation of mitochondrial membrane potential and activation of caspase-3 and its substrate, PARP. Moreover, Dracorhodin perchlorate dramatically enhanced the wortmannin- and TNF-induced apoptosis in SGC-7901 cells. These results reveal functional interplay among the PI3K/Akt, p53 and NF-κB pathways that are frequently deregulated in cancer and suggest that their simultaneous targeting by Dracorhodin perchlorate could result in efficacious and selective killing of cancer cells.

Artemisia argyi is a widely used medicinal plant in China. The present study was designed to identify the bioactive constituents with antiglioma activity from leaves of Artemesia argyi. A bioactivity guided approach based on MTT assay for cells growth inhibition led to the isolation of a flavonoid, “jaceosidin” from ethanol extract of leaves of Artemesia argyi. The growth inhibitory effect of jaceosidin was explored using flow cytometry and Western blot studies. Our results showed that jaceosidin exerts growth inhibitory effect by arresting the cells at G2/M phase and induction of apoptosis. Furthermore, our study revealed that induction of apoptosis was associated with cell cycle arrest at G2/M phase, upregulation of p53 and Bax, decrease in mitochondrial membrane potential, release of cytochrome c, and activation of caspase 3. This mitochondrial-caspase-3-dependent apoptosis pathway was confirmed by pretreatment with caspase 3 inhibitor, Ac-DEVD-CHO. Our findings suggested that jaceosidin induces mitochondrial-caspase-3-dependent apoptosis in U87 cells by arresting the cell cycle at G2/M phase.

SummaryAquaporin-8 (AQP8) is a water channel expressed extensively in male and female reproductive systems. But its physiological functions are largely unknown. In the present study, we first found significantly increased number of offspring delivered by AQP8 2/2 mothers compared with wild-type mothers in crossmating experiments. Comparison of ovulation in the two genotypes demonstrated that AQP8 2/2 ovaries released more oocytes (9.5 6 1.9 vs. 7.1 6 2.1 in normal ovulation and 37.8 6 6.7 vs. 27.9 6 5.7 in superovulation). Histological analysis showed increased number of corpus luteums in mature AQP8 2/2 ovaries, suggesting increased maturation and ovulation of follicles. By RT-PCR, western blot and immunohistochemistry analyses, we determined the expression of AQP8 in mouse ovarian granulosa cells. Granulosa cells isolated from AQP82/2 mice showed 45% of decreased membrane water permeability than wild-type mice. As the atresia of ovarian follicles is primarily due to apoptosis of granulosa cells, we analyzed the apoptosis of isolated granulosa cells from wild-type and AQP82/2 mice. The results indicated significantly lower apoptosis rate in AQP8 2/2 granulosa cells (21.3 6 3.6% vs. 32.6 6 4.3% in AQP81/1 granulosa cells). Taken together, we conclude that AQP8 deficiency increases the number of mature follicles by reducing the apoptosis of granulosa cells, thus increasing the fertility of female mice. This discovery may offer new insight of improving female fertility by reducing granulosa cell apoptosis through AQP8 inhibition. IUBMBIUBMB Life, 62(11): 852-857, 2010

Pseudolaric acid B (PLAB) is one of the major bioactive components of Pseudolarix kaempferi. It has been reported to exhibit inhibitory effect on cell proliferation in several types of cancer cells. However, there is no report elucidating its effect on glioma cells and organ toxicity in vivo. In the present study, we found that PLAB inhibited growth of U87 glioblastoma cells in a dose-dependent manner with IC50 ~10 μM. Flow cytometry analysis showed that apoptotic cell death mediated by PLAB was accompanied with cell cycle arrest at G2/M phase. Using Western blot, we found that PLAB induced G2/M phase arrest by inhibiting tubulin polymerization in U87 cells. Apoptotic cell death was only partially inhibited by pancaspase inhibitor, z-VAD-fmk, which suggested that PLAB-induced apoptosis in U87 cells is partially caspase-independent. Further mechanistic study demonstrated that PLAB induced caspase-dependent apoptosis via upregulation of p53, increased level of proapoptotic protein Bax, decreased level of antiapoptotic protein Bcl-2, release of cytochrome c from mitochondria, activation of caspase-3 and proteolytic cleavage of poly (ADP-ribose) polymerase (PARP) and caspase-independent apoptosis through apoptosis inducing factor (AIF). Furthermore, in vivo toxicity study demonstrated that PLAB did not induce significant structural and biochemical changes in mouse liver and kidneys at a dose of 25 mg/kg. Therefore, PLAB may become a potential lead compound for future development of antiglioma therapy.