Maspin is a deoxycholate-inducible, anti-apoptotic stress-response protein differentially expressed during colon carcinogenesis

Increased maspin expression in the colon is related to colon cancer risk and patient survival. Maspin is induced by the hydrophobic bile acid, deoxycholate (DOC), which is an endogenous carcinogen and inducer of oxidative stress and DNA damage in the colon. Persistent exposure of colon epithelial cells, in vitro, to high physiologic levels of DOC results in increased constitutive levels of maspin protein expression associated with the development of apoptosis resistance. When an apoptosis-resistant colon epithelial cell line (HCT-116RC) developed in the authors’ laboratory was treated with a maspin-specific siRNA probe, there was a statistically significant increase in apoptosis compared to treatment with an siRNA control probe. These results indicate, for the first time, that maspin is an anti-apoptotic protein in the colon. Immunohistochemical evaluation of maspin expression in human colonic epithelial cells during sporadic colon carcinogenesis (131 human tissues evaluated) indicated a statistically significant increase in maspin protein expression beginning at the polyp stage of carcinogenesis. There was no statistically significant difference in maspin expression between hyperplastic/adenomatous polyps and colonic adenocarcinomas. The absence of “field defects” in the non-neoplastic colonic mucosa of patients with colonic neoplasia indicates that maspin may drive the growth of tumors, in part, through its anti-apoptotic function

Deoxycholate, an Endogenous Cytotoxin/Genotoxin, Induces the Autophagic Stress-Survival Pathway: Implications for Colon Carcinogenesis

We report that deoxycholate (DOC), a hydrophobic bile acid associated with a high-fat diet, activates the autophagic pathway in non-cancer colon epithelial cells (NCM-460), and that this activation contributes to cell survival. The DOC-induced increase in autophagy was documented by an increase in autophagic vacuoles (detected using transmission electron microscopy, increased levels of LC3-I and LC3-II (western blotting), an increase in acidic vesicles (fluorescence spectroscopy of monodansycadaverine and lysotracker red probes), and increased expression of the autophagic protein, beclin-1 (immunohistochemistry/western blotting). The DOC-induced increase in beclin-1 expression was ROS-dependent. Rapamycin (activator of autophagy) pre-treatment of NCM-460 cells significantly (P < .05) decreased, and 3-MA (inhibitor of autophagy) significantly (P < .05) increased the cell loss caused by DOC treatment, alone. Rapamycin pre-treatment of the apoptosis-resistant colon cancer cell line, HCT-116RC (developed in our laboratory), resulted in a significant decrease in DOC-induced cell death. Bafilomycin A1 and hydroxychloroquine (inhibitors of the autophagic process) increased the DOC-induced percentage of apoptotic cells in HCT-116RC cells. It was concluded that the activation of autophagy by DOC has important implications for colon carcinogenesis and for the treatment of colon cancer in conjunction with commonly used chemotherapeutic agents

Disruption of Dnmt1/PCNA/UHRF1 Interactions Promotes Tumorigenesis from Human and Mice Glial Cells

Global DNA hypomethylation is a hallmark of cancer cells, but its molecular mechanisms have not been elucidated. Here, we show that the disruption of Dnmt1/PCNA/UHRF1 interactions promotes a global DNA hypomethylation in human gliomas. We then demonstrate that the Dnmt1 phosphorylations by Akt and/or PKC abrogate the interactions of Dnmt1 with PCNA and UHRF1 in cellular and acelluar studies including mass spectrometric analyses and the use of primary cultured patient-derived glioma. By using methylated DNA immunoprecipitation, methylation and CGH arrays, we show that global DNA hypomethylation is associated with genes hypomethylation, hypomethylation of DNA repeat element and chromosomal instability. Our results reveal that the disruption of Dnmt1/PCNA/UHRF1 interactions acts as an oncogenic event and that one of its signatures (i.e. the low level of mMTase activity) is a molecular biomarker associated with a poor prognosis in GBM patients. We identify the genetic and epigenetic alterations which collectively promote the acquisition of tumor/glioma traits by human astrocytes and glial progenitor cells as that promoting high proliferation and apoptosis evasion

Control of glioma cell death and differentiation by PKM2–Oct4 interaction

International audienceGlioma stem cells are highly resistant to cell death and as such are supposed to contribute to tumor recurrence by eluding anticancer treatments. Here, we show that spheroids that contain rat neural stem cells (NSCs) or rat glioma stem cells (cancer stem cells, CSCs) express isoforms 1 and 2 of pyruvate kinase (PKM1 and PKM2); however, the expression of PKM2 is considerably higher in glioma spheroids. Silencing of PKM2 enhances both apoptosis and differentiation of rat and human glioma spheroids. We establish that PKM2 was implicated in glioma spheroid differentiation through its interaction with Oct4, a major regulator of self-renewal and differentiation in stem cells. The small molecule Dichloroacetate (DCA), a pyruvate dehydrogenase kinase inhibitor, increases the amount of PKM2/Oct4 complexes and thus inhibited Oct4-dependent gene expression. Taken together, our results highlight a new molecular pathway through which PKM2 can manage gliomagenesis via the control of glioma stemness by Oct4

Ultra sensitive biosensor based on impedance spectroscopy at microwave frequencies for cell scale analysis

International audienceThis paper presents an original approach for biological cell discrimination using impedance spectroscopy analysis at microwave frequencies. The proposed method allows label-free analysis at the cell scale using high frequency electromagnetic waves as a non-invasive probe to analyze the intracellular medium. In the present case, the biosensor design takes advantage of classical planar microwave filter topology, where coupling zones present high sensitivity to tiny dielectric perturbations. With proper design, these specific areas can be used as an electromagnetic (EM) detector. In the present work, biosensor sensitivity allows reaching selective biological sample detection and bio-impedance measurements down to single-cell analysis. As presented in this paper, this concept has been experimentally validated with characterisations conducted on biological cancerous stem cells (cells considered at a low differentiation degree) and U87 glial cells (differentiated cells); both coming from human nervous system. Stem cells are almost similar in shape and size as differentiated cells. They are therefore quite difficult to identify using a microscope, and studies focusing on their differentiation mechanisms are very challenging. Cell chemical labeling would have been suitable if we would have been sure that used label will not induce an unwanted cell differentiation. To the contrary, EM impedance measurements show a significant difference between stem and differentiated cells dielectric permittivity. Therefore, such measurements can be an efficient approach to determine cell differentiation degree in a non-invasive way. As a label-free approach, the high frequency impedance spectroscopy could be very interesting for accurate discrimination of un-differentiated cells. Indeed, stem cells are currently the subject of a large research effort in the biologist community; especially in case of cancers, where cancerous stem cells are suspected to be the origin of most of tumor recurrences. Hence, based on this identification technique, a new diagnostic analysis could be developed for early cancer recurrence prevention

Nice Thinking! An Educational Intervention That Teaches Children to Think Gratefully

Gratitude is essential to social life and well-being. Although research with youth populations has gained momentum recently, only two gratitude interventions have been conducted in youth, targeting mostly adolescents. In the current research, we tested a new intervention for promoting gratitude among the youngest children targeted to date. Elementary school classrooms (of 8- to 11-year-olds) were randomly assigned either to an intervention that educated children about the appraisal of benefit exchanges or to a control condition. We found that children's awareness of the social-cognitive appraisals of beneficial social exchanges (i.e., grateful thinking) can be strengthened and that this, in turn, makes children more grateful and benefits their well-being in terms of increased general positive affect. A daily intervention produced evidence that this new approach induced gratitude immediately (2 days later) and led children to express gratitude more behaviorally (i.e., they wrote 80\% more thank-you cards to their Parent Teacher Association). A weekly intervention induced gratitude up to 5 months later and additionally showed an effect on well-being (i.e., positive affect). Evidence thus supported the effectiveness of this intervention. Results are discussed in terms of implications for positive youth development and academic functioning