Casticin suppresses self-renewal and invasion of lung cancer stem-like cells from A549 cells through down-regulation of pAkt

A subpopulation of cancer stem cells is recognized as the cause of tumorigenesis and spreading. To investigate the effects of casticin （5,3＇-dihydroxy-3,6,7,4＇-tetramethoxyflavone）, derived from Fructus Viticis Simplicifoliae, on lung cancer stem cells, we isolated and identified a subpopulation of lung cancer stem-like cells （LCSLCs） from non-small-cell lung carcinoma A549 cells with the features including self- renewal capacity and high invasiveness in vitro, elevated tumorigenic activity in vivo, and high expression of stemness markers CD133, CD44, and aldehyde dehydrogenase 1 （ALDH1）, using serum-free suspension sphere-forming culture method. We then found that casticin could suppress the proliferation of LCSLCs in a concentration-dependent manner with an IC50 value of 0.4 μmol/L, being much stronger than that in parental A549 cells. In addition, casti- cin could suppress the self-renewal and invasion of LCSLCs concomitant with decreased CD133, CD44, and ALDH1 protein expression and reduced MMP-9 activity. Further experiments showed that casticin suppressed self-renewal and invasion at least partly through down-regulation of Akt phosphorylation. In conclusion, casticin suppressed the characteristics of LCSLCs, suggesting that casticin may be a candidate compound for curing lung cancer via elim- inating cancer stem cells.     

Mechanism of taurine-induced apoptosis in human colon cancer cells

Taurine （Tau） has been shown to possess cancer therapeutic effect through induction of apoptosis, while the underlying molecular mechanism of its anti-cancer effect is not well understood. PUMA （p53-upregulated modulator of apoptosis） plays an important role in the process of apoptosis induction in a variety of human tumor ceils in both p53- dependent and -independent manners. However, whether PUMA is involved in the process of Tau-induced apoptosis in cancer cells has not been well studied. In the present study, we treated human colorectal cancer cells HT-29 （mutant p53） and LoVo （wild-type p53） with different concentrations of Tau, which led to the repression of cell proliferation and induction of apoptosis in both cell fines. Meanwhile, we also observed the increased expression of PUMA and high Bax/Bcl-2 ratios. To determine the role of PUMA in Tau-induced apoptosis, we used small interfering RNA interference to suppress PUMA expression. As a result, apoptosis was decreased in response to Tau treatment. All these results indicated that PUMA plays a critical role in Tauinduced apoptosis pathway in human colorectal cancer ceils. Demonstration of the molecular mechanism involved in the anti-tumor effect of Tau may be useful in the therapeutic target selection for p53-deficient colorectal cancer.     

De-oncogenic HPV E6/E7 vaccine gets enhanced antigenicity and promotes tumoricidal synergy with cisplatin

In order to develop more effective therapeutic vaccines against cancers with high-risk human papillomavirus （HPV） infection, it is crucial to enhance the immunogenicity, eliminate the oncogenicity of oncoproteins, and take a combination of ET- and E6-containing vaccines. It has been shown recently that PE（AIII）-E7-KDEL3 （E7）, a fusion protein containing the HPVI6 oncoprotein E7 and the trans- location domain of Pseudomonas aeruginosa exotoxin A, is effective against TC-1 tumor cells inoculated in mice, there- fore, we engineered PE（AIII）-E6-CRL-KDEL3 （E6）, the deoncogenic versions of the E7 and E6 fusion proteins [i.e. PE（AIII）-E7（d）-KDEL3, E7（d）, and PE（AIII）-E6（d）-CRL- KDEL3, E6（d）] and tested the immunoefficacies of these fusion proteins as mono- and bivalent vaccines. Results indicated that the E7（d） get higher immunogenicity than its wild type and the E6 fusion proteins augmented the im- munogenicity and antitumor effects of their E7 counterparts. Furthermore, the bivalent vaccine system E7（d） plus E6（d）, in the presence of cisplatin, showed the best tumori- static and tumoricidal effects against established tumors in vivo. Therefore, it can be concluded that this novel therapeutic vaccine system, upon further optimization, may shed new light on clinical management of HPV-related carcinomas.     

Effect of Smac and Taxol on non-small-cell lung cancer

A series of structurally unique second mitochondria-derived activator of caspases （Smacs） that act as antagonists of the inhibitor of apoptosis proteins （IAPs） directly have been discovered. They play crucial roles in mitochondrial apoptosis pathways and promote chemotherapy-induced apoptosis. In this study, we constructed a eukaryotic expression vector pcDNA3.1/Smac and transfected it into A549 human lung cancer cells. Then we analyzed the cell invasive and cloning ability, as well as cell apoptosis induced by Taxol. The results showed that over-expressed Smac significantly inhibited A549 cell invasive and cloning ability and promoted apoptosis following Taxol treatment. This finding provides a potential approach for the biological therapy of lung cancer.     

Mechanism of immunomodulatory drugs＇ action in the treatment of multiple myeloma

Although immunomodulatory drugs （IMiDs）, such as thal- idomide, lenalidomide, and pomalidomide, are widely used in the treatment of multiple myeloma （MM）, the molecular mechanism of IMiDs＇ action is largely unknown. In this review, we will summarize recent advances in the application of IMiDs in MM cancer treatment as well as their effects on immunomodulatory activities, anti-angiogenic activities, intervention of cell surface adhesion molecules between myeloma cells and bone marrow stromal cells, anti-inflam- matory activities, anti-proliferation, pro-apoptotic effects, cell cycle arrest, and inhibition of cell migration and metastasis. In addition, the potential IMiDs＇ target protein, IMiDs＇ target protein＇s functional role, and the potential molecular mechanisms of IMiDs resistance will be discussed. We wish, by presentation of our naive discussion, that this review article will facilitate further investigation in these fields.     

CEACAM6 promotes tumor migration,invasion, and metastasis in gastric cancer

Carcinoembryonic antigen-related cell adhesion molecule 6 （CEACAM6） shows increased expression in a wide variety of human cancers, and its over-expression is associated with enhanced migration, invasion, and in vivo metastasis. Here, we reported that CEACAM6 was up-regulated in gastric cancer （GC） cell lines and tumor tissues. Overexpression of CEACAM6 in MKN-45 and SGC-7901 GC cells promoted migration and invasion in vitro and metastasis in athymic mice, whereas migration and invasion of MKN-28 and SNU-16 GC cells were suppressed by knockdown of CEACAM6. We also observed that steroid receptor coactivator （C-SRC） phosphorylation was increased when CEACAM6 was over-expressed in SGC-7901 cells. Taken together, these results suggested that CEACAM6 functions as an oncoprotein in GC and may be an important metastatic biomarker and therapeutic target.     

Cell Wall,Cytoskeleton, and Cell Expansion in Higher Plants

To accommodate two seemingly contradictory biological roles in plant physiology, providing both the rigid structural support of plant cells and the adjustable elasticity needed for cell expansion, the composition of the plant cell wall has evolved to become an intricate network of cellulosic, hemicellulosic, and pectic polysaccharides and protein. Due to its complexity, many aspects of the cell wall influence plant cell expansion, and many new and insightful observations and technologies are forthcoming. The biosynthesis of cell wall polymers and the roles of the variety of proteins involved in polysaccharide synthesis continue to be characterized. The interactions within the cell wall polymer network and the modification of these interactions provide insight into how the plant cell wall provides its dual function. The complex cell wall architecture is controlled and organized in part by the dynamic intracellular cytoskeleton and by diverse trafficking pathways of the cell wall polymers and cell wall-related machinery. Meanwhile, the cell wall is continually influenced by hormonal and integrity sensing stimuli that are perceived by the cell. These many processes cooperate to construct, maintain, and manipulate the intricate plant cell wall--an essential structure for the sustaining of the plant stature, growth, and life.     

MiRNA-218, a new regulator of HMGB1, suppresses cell migration and invasion in non-small cell lung cancer

MieroRNAs （miRNAs） function as negative regulators of gene expression involved in cancer metastasis. The aim of this study is to investigate the potential roles of miR-218 in non-small cell lung cancer and validate its regulation mech- anism. Functional studies showed that miR-218 overexpres- sion inhibited cell migration and invasion, but had no effect on cell viability. Enhanced green fluorescent protein reporter assay, real-time polymerase chain reaction and western blot analysis confirmed that miR-218 suppressed the expression of high mobility group box-1 （HMGB1） by directly targeting its 31-untranslated region. Accordingly, silencing of HMGBI accorded with the effects of miR-218 on cell migration and invasion, and overexpression of HMGB1 can restore cell migration and invasion which were reduced by miR-218. In conclusion, these findings demon- strate that miR-218 functions as a tumor suppressor in lung cancer. Furthermore, miR-218 may act as a potential thera- peutic biomarker for metastatic lung cancer patients.     

Dissecting the Heat Stress Response in Chlamydomonas by Pharmaceutical and RNAi Approaches Reveals Conserved and Novel Aspects

To study how conserved fundamental concepts of the heat stress response （HSR） are in photosynthetic eukaryotes, we applied pharmaceutical and antisense/amiRNA approaches to the unicellular green alga Chlamydomonas reinhardtii. The Chlamydomonas HSR appears to be triggered by the accumulation of unfolded proteins, as it was induced at ambient temperatures by feeding cells with the arginine analog canavanine. The protein kinase inhibitor staurosporine strongly retarded the HSR, demonstrating the importance of phosphorylation during activation of the HSR also in Chlamydomonas. While the removal of extracellular calcium by the application of EGTA and BAPTA inhibited the HSR in moss and higher plants, only the addition of BAPTA, but not of EGTA, retarded the HSR and impaired thermotoler- ance in Chlamydomonas. The addition of cycloheximide, an inhibitor of cytosolic protein synthesis, abolished the attenu- ation of the HSR, indicating that protein synthesis is necessary to restore proteostasis. HSP90 inhibitors induced a stress response when added at ambient conditions and retarded attenuation of the HSR at elevated temperatures. In addition, we detected a direct physical interaction between cytosolic HSP90A/HSP70A and heat shock factor 1, but surprisingly this interaction persisted after the onset of stress. Finally, the expression of antisense constructs targeting chloroplast HSP70B resulted in a delay of the cell＇s entire HSR, thus suggesting the existence of a retrograde stress signaling cascade that is desensitized in HSP7OB-antisense strains.     

Redox Regulation of Arabidopsis Mitochondrial Citrate Synthase

Citrate synthase has a key role in the tricarboxylic （TCA） cycle of mitochondria of all organisms, as it cata- lyzes the first committed step which is the fusion of a carbon-carbon bond between oxaloacetate and acetyl CoA. The regulation of TCA cycle function is especially important in plants, since mitochondrial activities have to be coordinated with photosynthesis. The posttranslational regulation of TCA cycle activity in plants is thus far almost entirely unexplored. Although several TCA cycle enzymes have been identified as thioredoxin targets in vitro, the existence of any thioredoxin-dependent regulation as known for the Calvin cycle, yet remains to be demonstrated. Here we have investigated the redox regulation of the Arabidopsis citrate synthase enzyme by site-directed mutagenesis of its six cysteine residues. Our results indicate that oxidation inhibits the enzyme activity by the formation of mixed disulfides, as the partially oxidized citrate synthase enzyme forms large redox-dependent aggregates. Furthermore, we were able to demonstrate that thioredoxin can cleave diverse intraas well as intermolecular disulfide bridges, which strongly enhances the activity of the enzyme. Activity measurements with the cysteine variants of the enzyme revealed important cysteine residues affecting total enzyme activity as well as the redox sensitivity of the enzyme.     

Hypoxia and cancer cell metabolism

The past decade has witnessed a rapid accumulation of evi- dence showing that hypoxic microenvironment, which is typical during cancer development, plays key roles in regu- lating cancer cell metabolism. In this review, we will focus on the role of hypoxic response, particularly, its master regulator hypoxia-inducible factor-I, in regulating glucose, lipid, as well as amino acid metabolism in cancer cells. We will also discuss the therapeutic opportunities by targeting specific pathways that facilitate metabolic reprogramming in cancer cells.     

Organelle pH in the Arabidopsis Endomembrane System

The pH of intracellular compartments is essential for the viability of cells. Despite its relevance, little is known about the pH of these compartments. To measure pH in vivo, we have first generated two pH sensors by combining the improved-solubility feature of solubility-modified green fluorescent protein （GFP） （smGFP） with the pH-sensing capabil- ity of the pHluorins and codon optimized for expression in Arabidopsis. PEpHluorin （plant-solubility-modified ecliptic pHluorin） gradually loses fluorescence as pH is lowered with fluorescence vanishing at pH 6.2 and PRpHluorin （plant- solubility-modified ratiomatric pHluorin）, a dual-excitation sensor, allowing for precise measurements. Compartment- specific sensors were generated by further fusing specific sorting signals to PEpHluorin and PRpHluorin. Our results show that the pH of cytosol and nucleus is similar （pH 7.3 and 7.2）, while peroxisomes, mitochondrial matrix, and plastidial stroma have alkaline pH. Compartments of the secretory pathway reveal a gradual acidification, spanning from pH 7.1 in the endoplasmic reticulum （ER） to pH 5.2 in the vacuole. Surprisingly, pH in the trans-Golgi network （TGN） and mul- tivesicular body （MVB） is, with pH 6.3 and 6.2, quite similar. The inhibition of vacuolar-type H＋-ATPase （V-ATPase） with concanamycin A （ConcA） caused drastic increase in pH in TGN and vacuole. Overall, the PEpHluorin and PRpHluorin are excellent pH sensors for visualization and quantification of pH in vivo, respectively.     

How does the host-specialized aphid deal with food deficiency？

Aphis gossypii Glover shows obvious host specialization, with cucurbit- and cotton-specialized biotypes or host races in many regions. Because its annual natal hostcrops senesce earlier the cucurbit-specialized biotype may suffer food deficiency. The method this biotype uses to overcome this challenge is still poorly understood. In orderto understand the potential of the cucurbit-specialized biotype aphids in host shift and usage, the performance of this biotype on cotton （Gossypium hirsutum）, a common butpoor quality host plant, was explored in this study. The cucurbit-specialized aphids could establish populations on cotton only when these plants had at least nine leaves, and subsequent populations developed rather slowly. The presence of whitefly populations on cotton improved the success rate of cucurbit-specialized aphids. The cucurbit-specialized aphidswere mainly distributed on the older leaves of cotton, with only a few settling on the upper leaves. The cucurbit-specialized aphids reared on cotton for 40, 54 and 61 days stillmaintained strong preference for their natal host plant, cucumber （Cucumis sativus）, rather than cotton, and their net reproductive rates and intrinsic rates of natural increase weredramatically lower when they were transferred onto new six-leaf cotton plants or detached leaves. Therefore, we concluded that the cucurbit-specialized aphids have the potentialto utilize mature or whitefly-stressed cotton plants, but that this feeding experience on cotton did not alter their specialization for cucurbits. Some cotton plants could act as atemporary host for the cucurbit-specialized aphids to overcome food deficiency arising from senescing cucurbits.     

Plastid Signals and the Bundle Sheath： Mesophyll Development in Reticulate Mutants

The development of a plant leaf is a meticulously orchestrated sequence of events producing a complex organ comprising diverse cell types. The reticulate class of leaf variegation mutants displays contrasting pigmentation between veins and interveinal regions due to specific aberrations in the development of mesophyll cells. Thus, the reticulate mutants offer a potent tool to investigate cell-type-specific developmental processes. The discovery that most mutants are affected in plastid-localized, metabolic pathways that are strongly expressed in vasculature-associated tis- sues implicates a crucial role for the bundle sheath and their chloroplasts in proper development of the mesophyll cells. Here, we review the reticulate mutants and their phenotypic characteristics, with a focus on those in Arabidopsis thali- ana. Two alternative models have been put forward to explain the relationship between plastid metabolism and meso- phyll cell development, which we call here the supply and the signaling hypotheses. We critically assess these proposed models and discuss their implications for leaf development and bundle sheath function in C3 species. The characteriza- tion of the reticulate mutants supports the significance of plastid retrograde signaling in cell development and highlights the significance of the bundle sheath in C3 photosynthesis.     

Knights in Action： Lectin Receptor-Like Kinases in Plant Development and Stress Responses

The Receptor-Like Kinase （RLK） is a vast protein family with over 600 genes in Arabidopsis and 1100 in rice. The Lectin RLK （LecRLK） family is believed to play crucial roles in saccharide signaling as well as stress perception. All the LecRLKs possess three domains： an N-terminal lectin domain, an intermediate transmembrane domain, and a C-terminal kinase domain. On the basis of lectin domain variability, LecRLKs have been subgrouped into three subclasses： L-, G-, and C-type LecRLKs. While the previous studies on LecRLKs were dedicated to classification, comparative structural analysis and expression analysis by promoter-based studies, most of the recent studies on LecRLKs have laid special emphasis on the potential of this gene family in regulating biotic/abiotic stress and developmental pathways in plants, thus mak- ing the prospects of studying the LecRLK-mediated regulatory mechanism exceptionally promising. In this review, we have described in detail the LecRLK gene family with respect to a historical, evolutionary, and structural point of view. Furthermore, we have laid emphasis on the LecRLKs roles in development, stress conditions, and hormonal response. We have also discussed the exciting research prospects offered by the current knowledge on the LecRLK gene family. The multitude of the LecRLK gene family members and their functional diversity mark these genes as both interesting and worthy candidates for further analysis, especially in the field of crop improvement.