Thermostable Direct Hemolysin Downregulates Human Colon Carcinoma Cell Proliferation with the Involvement of E-Cadherin, and β-Catenin/Tcf-4 Signaling

BACKGROUND: Colon cancers are the frequent causes of cancer mortality worldwide. Recently bacterial toxins have received marked attention as promising approaches in the treatment of colon cancer. Thermostable direct hemolysin (TDH) secreted by Vibrio parahaemolyticus causes influx of extracellular calcium with the subsequent rise in intracellular calcium level in intestinal epithelial cells and it is known that calcium has antiproliferative activity against colon cancer. KEY RESULTS: In the present study it has been shown that TDH, a well-known traditional virulent factor inhibits proliferation of human colon carcinoma cells through the involvement of CaSR in its mechanism. TDH treatment does not induce DNA fragmentation, nor causes the release of lactate dehydrogenase. Therefore, apoptosis and cytotoxicity are not contributing to the TDH-mediated reduction of proliferation rate, and hence the reduction appears to be caused by decrease in cell proliferation. The elevation of E-cadherin, a cell adhesion molecule and suppression of β-catenin, a proto-oncogene have been observed in presence of CaSR agonists whereas reverse effect has been seen in presence of CaSR antagonist as well as si-RNA in TDH treated cells. TDH also triggers a significant reduction of Cyclin-D and cdk2, two important cell cycle regulatory proteins along with an up regulation of cell cycle inhibitory protein p27(Kip1) in presence of CaSR agonists. CONCLUSION: Therefore TDH can downregulate colonic carcinoma cell proliferation and involves CaSR in its mechanism of action. The downregulation occurs mainly through the involvement of E-cadherin-β-catenin mediated pathway and the inhibition of cell cycle regulators as well as upregulation of cell cycle inhibitors

DIPG-01. Targeting p300: A master regulator of childhood diffuse intrinsic pontine glioma (DIPG)

Abstract Diffuse intrinsic pontine gliomas (DIPG) are heterogeneous, highly aggressive, accounting for ~10% of all childhood central nervous system tumors that are poorly understood. The heterogeneity of the cell populations could contribute to major variability in tumor growth and chemoresistance followed by inadequate treatment responses. Approximately 80% of DIPG patients harbor mutations on lysine-27 of histone-3 (H3K27M), which forms heterotypic nucleosomes with normal, acetylated-H3K27 (H3K27ac), and colocalizes with bromodomain proteins to sites of active transcription. p300 (or EP300) bromodomain has recently been exploited as a potential therapeutic target in other cancer, with a small molecule inhibitor showing antiproliferative activity. Bromodomain inhibitors (BrDi) have been suggested as a potential therapeutic target for DIPG too which showed antiproliferative activity in vitro. We therefore hypothesize that p300 bromodomain inhibition is a potential therapeutic strategy that must be urgently explored in DIPG. p300 is a multi-domain enhancer protein, expressed in 80% of gliomas, responsible for H3K27ac mark and localizes to sites of H3K27ac enrichment, where it serves as an essential binding partner of histones to various transcription factors. p300 interacts with BMI-1, a polycomb repressive complex 1 (PRC1) group of transcription factor, through an intermediate protein NANOG, which promotes cell proliferation in head-neck squamous cell carcinoma. However, immunohistochemical study demonstrated that there is no NANOG expression found in DIPG patient samples. Therefore, we propose that p300 and BMI-1 interact with each other directly or through an intermediate molecule, essential for tumor growth and thus can be considered as a possible therapeutic target for DIPG. The overall outcome of this research will reveal the unexplored mechanisms of DIPG cell proliferation to overcome chemoresistance in sick children and develop drug/combination against this deadly malignancy, which can be used for future clinical trials.</jats:p

Influence of the Physiological Age and Position of the Nodal Explants on Micropropagation of Field-Grown Dendrocalamus Strictus Nees

An efficient and reproducible protocol for plant regeneration through in vitro culture of Dendrocalamus strictus is reported. Murashige and Skoog\u27s (MS) basal medium supplemented with N6-benzyladenine and adenine sulphate resulted in high frequency of shoot organogenesis. Nodal explants obtained from mature field-grown culms of selected elite genotype of D. strictus produced multiple shoots. Percent regeneration and number of multiple shoots was directly correlated with the nodal segments from which explants were collected. Best regeneration response was noted from 1st and 2nd positions from the basal end of the secondary branches. The effect of physiological age of the donor plant on axillary shoot multiplication was studied for three consecutive years. The regeneration frequency declined with the maturity of the donor plant. Roots and monopodial type micro-rhizomes were induced in medium containing half strength of MS macrosalts supplemented with indole-3-butyric acid and regenerants were successfully transplanted in the soil. © 2004 Society for Biology and Biotechnology

Downregulation of Human Colon Carcinoma Cell (COLO-205) Proliferation Through PKG-MAP Kinase Mediated Signaling Cascade by E. Coli Heat Stable Enterotoxin (STa), a Potent Anti-Angiogenic and Anti-Metastatic Molecule

It was reported earlier that Escherichia coli heat stable enterotoxin (STa), a major causative agent of secretory diarrhea, can also inhibit the proliferation of colon carcinoma cells with the involvement of cGMP mediated calcium influx. In the present study it is shown that E. coli STa inhibits cell proliferation in the colonic carcinoma cell line COLO-205 by the PKG-ERK44/42 mediated signaling pathway. This enterotoxin negatively regulates cell proliferation by downregulating the activity of ERK44/42(MAPK) and subsequently the activity of a transcription regulatory protein cMyc. The antiproliferative effect of STa was reversed by LY83583, a guanylate cyclase (GC) inhibitor and KT5823, a PKG inhibitor. Thus suggesting the involvement of cGMP dependent protein kinase (PKG) in the downregulation of ERK44/42 and subsequent inactivation of cMyc activity. Moreover, it has been shown that a specific ERK44/42 inhibitor, PD98059, also inhibits cMyc activation and cell proliferation, which further confirms the involvement of ERK44/42 in the activation of cMyc. It is also shown that E. coli STa significantly inhibits the vascular endothelial growth factor (VEGF, a potent angiogenic factor) expression in COLO-205 cells and also downregulates vascular cell adhesion molecule-1 (VCAM-1, a potent metastatic factor) expression on the COLO-205 cell surface. So it is reported for the first time that E. coli STa inhibits the proliferation of the colonic carcinoma cell line COLO-205 by the PKG-ERK44/42 mediated pathway and it may have a role against the development of colon carcinoma. Copyright © 2007 John Wiley & Sons, Ltd

Assessment of knowledge, attitude and practices among Accredited Social Health Activists (ASHAs) towards COVID-19: a descriptive cross-sectional study in Tripura, India

AbstractWith the surge in COVID-19 cases, community healthcare workers (CHW) remain pivotal for proper dissemination of awareness of disease transmission and infection control measures among the communities in low- and middle-income countries. In this context, lack of adequate knowledge and appropriate attitude among the CHW can directly influence the COVID-19 management programme. Therefore, the present study was designed to assess the knowledge, attitude and practices towards COVID-19 among the CHW of India known as Accredited Social Health Activists (ASHAs). A descriptive cross-sectional was conducted in the state of Tripura, Northeast India, among ASHAs with 14-, 4- and 3-item self-administered questionnaire for knowledge, attitude and practice. Around 61.2% of participants had the mean correct answer rate and the mean score of knowledge was 8.57± 2.25 (±SD). As per Bloom’s cut-off, it was observed that only 10% of the ASHAs had adequate knowledge, 30.9% showed positive attitude and 88% adhered to the good practices. It was observed that the indigenous ASHAs were 1.79 times more likely to adhere to the good practice of wearing masks during filed visits in the community (OR: 1.791, 95% CI: 1.059-3.028, p=0.030). Multinomial regression analysis showed that practice was significantly associated with fear of getting infected during service and the community’s fearfulness of ASHAs spreading the disease. Urgent addressing of the provisions of support, guidance and training of grassroot level healthcare workers in rural tough terrains can ensure robust output from the existing community healthcare workers in future pandemic-like emergencies.</jats:p

Role of Yersinia Enterocolitica Heat-Stable Enterotoxin (Y-STa) on Differential Regulation of Nuclear and Cytosolic Calcium Signaling in Rat Intestinal Epithelial Cells

The heat-stable enterotoxin (Y-STa) produced by the pathogenic strains of Yersinia enterocolitica is a causative agent of secretory diarrhea. We have reported earlier that Y-STa-induced inositol trisphosphate-mediated cytosolic calcium rise occurs in rat intestinal epithelial cells. In the present communication, the involvement of a nuclear calcium store in the action mechanism of Y-STa in rat intestinal epithelial cells has been shown. Calcium imaging with time series confocal microscopy shows that Y-STa stimulates both the nuclear and cytosolic calcium levels in rat intestinal epithelial cells where a rise in nuclear calcium precedes the cytosolic events. Moreover, Y-STa stimulates both cytosolic and nuclear inositol trisphosphate (IP3) levels in a time-dependent manner. Western blot and immunocytochemical analysis reveal a higher density of IP3 receptor type II in the nuclear membrane compared to the cytosol, which may be the cause of an early rise of the nuclear calcium level. Therefore, it is suggested that Y-STa regulates the nuclear and cytosolic calcium signals in a distinct temporal manner in rat intestinal epithelial cells. © 2008 Springer Science+Business Media B.V