Prostaglandin E2 reduces radiation-induced epithelial apoptosis through a mechanism involving AKT activation and bax translocation

Prostaglandin E(2) (PGE(2)) synthesis modulates the response to radiation injury in the mouse intestinal epithelium through effects on crypt survival and apoptosis; however, the downstream signaling events have not been elucidated. WT mice receiving 16,16-dimethyl PGE(2) (dmPGE(2)) had fewer apoptotic cells per crypt than untreated mice. Apoptosis in Bax(–/–) mice receiving 12 Gy was approximately 50% less than in WT mice, and the ability of dmPGE(2) to attenuate apoptosis was lost in Bax(–/–) mice. Positional analysis revealed that apoptosis in the Bax(–/–) mice was diminished only in the bax-expressing cells of the lower crypts and that in WT mice, dmPGE(2) decreased apoptosis only in the bax-expressing cells. The HCT-116 intestinal cell line and Bax(–/–) HCT-116 recapitulated the apoptotic response of the mouse small intestine with regard to irradiation and dmPGE(2). Irradiation of HCT-116 cells resulted in phosphorylation of AKT that was enhanced by dmPGE(2) through transactivation of the EGFR. Inhibition of AKT phosphorylation prevented the reduction of apoptosis by dmPGE(2) following radiation. Transfection of HCT-116 cells with a constitutively active AKT reduced apoptosis in irradiated cells to the same extent as in nontransfected cells treated with dmPGE(2). Treatment with dmPGE(2) did not alter bax or bcl-x expression but suppressed bax translocation to the mitochondrial membrane. Our in vivo studies indicate that there are bax-dependent and bax-independent radiation-induced apoptosis in the intestine but that only the bax-dependent apoptosis is reduced by dmPGE(2). The in vitro studies indicate that dmPGE(2), most likely by signaling through the E prostaglandin receptor EP(2), reduces radiation-induced apoptosis through transactivation of the EGFR and enhanced activation of AKT and that this results in reduced bax translocation to the mitochondria

Ethnopharmacological Approaches to Wound Repair

Wound is breaking of the skin by a physical injury. Wound healing is a connective tissue response along with the repair process which immediately comes after the injury. It occurs as a sequence of phases such as haemostasis, inflammation, proliferation, and remodelling and causes series of interactions between the extracellular matrix, cytokine mediators, and different cell types. For rapid healing several medicinal plants were reported in ethnobotanical studies. Traditional remedies which claimed to have wound healing potential are widely used in developing countries due to their accessibility and low cost. However, these remedies should be evaluated for their efficacy and safety before their utilization. In this context, the papers selected for this special issue include scientifically evaluated information and lead to development of novel drugs for rapid healing of wounds.We would like to thank the authors for their contributions for this special issue. This special issue contains twelve papers. T. Lin et al. investigated the wound healing effect of tocopherol in diabetic rats.This study has proven thewound healing potential of tocopherol cream by increasing the rate of wound closure and total protein content significantly in diabetic condition

Role of STAT3 in pancreatic cancer

Pancreatic cancer remains a serious and deadly disease, impacting people globally. There remain prominent gaps in the current understanding of the disease, specifically regarding the role of the signal transducer and activator of transcription (STAT) family of proteins in pancreatic tumors. STAT proteins, particularly STAT3, play important roles in pancreatic cancer, especially pancreatic ductal adenocarcinoma (PDAC), which is the most prevalent histotype. The role of STAT3 across a continuum of molecular processes, such as PDAC tumorigenesis and progression, immune escape, drug resistance and stemness, and modulation of the tumor microenvironment (TME), are only a tip of the iceberg. In some ways, the role of STAT3 in PDAC may hold greater importance than that of oncogenic Kirsten rat sarcoma virus (KRAS). This makes STAT3 a highly attractive target for developing targeted therapies for the treatment of pancreatic cancer. In this review, the current knowledge of STAT3 in pancreatic cancer has been summarized, particularly relating to STAT3 activation in cancer cells, cells of the TME, and the state of targeting STAT3 in pre-clinical and clinical trials of PDAC

Curcumin Induces Cell Death in Esophageal Cancer Cells through Modulating Notch Signaling

Curcumin inhibits the growth of esophageal cancer cell lines; however, the mechanism of action is not well understood. It is becoming increasingly clear that aberrant activation of Notch signaling has been associated with the development of esophageal cancer. Here, we have determined that curcumin inhibits esophageal cancer growth via a mechanism mediated through the Notch signaling pathway.In this study, we show that curcumin treatment resulted in a dose and time dependent inhibition of proliferation and colony formation in esophageal cancer cell lines. Furthermore, curcumin treatment induced apoptosis through caspase 3 activation, confirmed by an increase in the ratio of Bax to Bcl2. Cell cycle analysis demonstrated that curcumin treatment induced cell death and down regulated cyclin D1 levels. Curcumin treatment also resulted in reduced number and size of esophagospheres. Furthermore, curcumin treatment led to reduced Notch-1 activation, expression of Jagged-1 and its downstream target Hes-1. This reduction in Notch-1 activation was determined to be due to the down-regulation of critical components of the γ-secretase complex proteins such as Presenilin 1 and Nicastrin. The combination of a known γ-secretase inhibitor DAPT and curcumin further decreased proliferation and induced apoptosis in esophageal cancer cells. Finally, curcumin treatment down-regulate the expressions of Notch-1 specific microRNAs miR-21 and miR-34a, and upregulated tumor suppressor let-7a miRNA.Curcumin is a potent inhibitor of esophageal cancer growth that targets the Notch-1 activating γ-secretase complex proteins. These data suggest that Notch signaling inhibition is a novel mechanism of action for curcumin during therapeutic intervention in esophageal cancers

Inhibition of angiogenesis- and inflammation-inducing factors in human colon cancer cells in vitro and in ovo by free and nanoparticle-encapsulated redox dye, DCPIP

<p>Abstract</p> <p>Background</p> <p>The redox dye, DCPIP, has recently shown to exhibit anti-melanoma activity <it>in vitro </it>and <it>in vivo</it>. On the other hand, there is increasing evidence that synthetic nanoparticles can serve as highly efficient carriers of drugs and vaccines for treatment of various diseases. These nanoparticles have shown to serve as potent tools that can increase the bioavailability of the drug/vaccine by facilitating absorption or conferring sustained and improved release. Here, we describe results on the effects of free- and nanoparticle-enclosed DCPIP as anti-angiogenesis and anti-inflammation agents in a human colon cancer HCT116 cell line <it>in vitro</it>, and in induced angiogenesis <it>in ovo</it>.</p> <p>Results</p> <p>The studies described in this report indicate that (a) DCPIP inhibits proliferation of HCT116 cells <it>in vitro</it>; (b) DCPIP can selectively downregulate expression of the pro-angiogenesis growth factor, VEGF; (c) DCPIP inhibits activation of the transcriptional nuclear factor, NF-κB; (d) DCPIP can attenuate or completely inhibit VEGF-induced angiogenesis in the chick chorioallantoic membrane; (e) DCPIP at concentrations higher than 6 μg/ml induces apoptosis in HCT116 cells as confirmed by detection of caspase-3 and PARP degradation; and (f) DCPIP encapsulated in nanoparticles is equally or more effective than free DCPIP in exhibiting the aforementioned properties (a-e) in addition to reducing the expression of COX-2, and pro-inflammatory proteins IL-6 and IL-8.</p> <p>Conclusions</p> <p>We propose that, DCPIP may serve as a potent tool to prevent or disrupt the processes of cell proliferation, tissue angiogenesis and inflammation by directly or indirectly targeting expression of specific cellular factors. We also propose that the activities of DCPIP may be long-lasting and/or enhanced if it is delivered enclosed in specific nanoparticles.</p

Impact of HuR inhibition by the small molecule MS-444 on colorectal cancer cell tumorigenesis.

Colorectal cancer (CRC) is the third most common cancer and a leading cause of cancer-related mortality. Observed during CRC tumorigenesis is loss of post-transcriptional regulation of tumor-promoting genes such as COX-2, TNFα and VEGF. Overexpression of the RNA-binding protein HuR (ELAVL1) occurs during colon tumorigenesis and is abnormally present within the cytoplasm, where it post-transcriptionally regulates genes through its interaction with 3\u27UTR AU-rich elements (AREs). Here, we examine the therapeutic potential of targeting HuR using MS-444, a small molecule HuR inhibitor. Treatment of CRC cells with MS-444 resulted in growth inhibition and increased apoptotic gene expression, while similar treatment doses in non-transformed intestinal cells had no appreciable effects. Mechanistically, MS-444 disrupted HuR cytoplasmic trafficking and released ARE-mRNAs for localization to P-bodies, but did not affect total HuR expression levels. This resulted in MS-444-mediated inhibition of COX-2 and other ARE-mRNA expression levels. Importantly, MS-444 was well tolerated and inhibited xenograft CRC tumor growth through enhanced apoptosis and decreased angiogenesis upon intraperitoneal administration. In vivo treatment of MS-444 inhibited HuR cytoplasmic localization and decreased COX-2 expression in tumors. These findings provide evidence that therapeutic strategies to target HuR in CRC warrant further investigation in an effort to move this approach to the clinic

Enteric infection coupled with chronic Notch pathway inhibition alters colonic mucus composition leading to dysbiosis, barrier disruption and colitis

Intestinal mucus layer disruption and gut microflora modification in conjunction with tight junction (TJ) changes can increase colonic permeability that allows bacterial dissemination and intestinal and systemic disease. We showed previously that Citrobacter rodentium (CR)-induced colonic crypt hyperplasia and/or colitis is regulated by a functional cross-talk between the Notch and Wnt/β-catenin pathways. In the current study, mucus analysis in the colons of CR-infected (108 CFUs) and Notch blocker Dibenzazepine (DBZ, i.p.; 10μmol/Kg b.w.)-treated mice revealed significant alterations in the composition of trace O-glycans and complex type and hybrid N-glycans, compared to CR-infected mice alone that preceded/ accompanied alterations in 16S rDNA microbial community structure and elevated EUB338 staining. While mucin-degrading bacterium, Akkermansia muciniphila (A. muciniphila) along with Enterobacteriaceae belonging to Proteobacteria phyla increased in the feces, antimicrobial peptides Angiogenin-4, Intelectin-1 and Intelectin-2, and ISC marker Dclk1, exhibited dramatic decreases in the colons of CR-infected/DBZ-treated mice. Also evident was a loss of TJ and adherens junction protein immuno-staining within the colonic crypts that negatively impacted paracellular barrier. These changes coincided with the loss of Notch signaling and exacerbation of mucosal injury. In response to a cocktail of antibiotics (Metronidazole/ ciprofloxacin) for 10 days, there was increased survival that coincided with: i) decreased levels of Proteobacteria, ii) elevated Dclk1 levels in the crypt and, iii) reduced paracellular permeability. Thus, enteric infections that interfere with Notch activity may promote mucosal dysbiosis that is preceded by changes in mucus composition. Controlled use of antibiotics seems to alleviate gut dysbiosis but may be insufficient to promote colonic crypt regeneration.R01-CA18532

Nanoparticle-based delivery of siDCAMKL-1 increases microRNA-144 and inhibits colorectal cancer tumor growth via a Notch-1 dependent mechanism

<p>Abstract</p> <p>Background</p> <p>The development of effective drug delivery systems capable of transporting small interfering RNA (siRNA) has been elusive. We have previously reported that colorectal cancer tumor xenograft growth was arrested following treatment with liposomal preparation of siDCAMKL-1. In this report, we have utilized Nanoparticle (NP) technology to deliver DCAMKL-1 specific siRNA to knockdown potential key cancer regulators. In this study, mRNA/miRNA were analyzed using real-time RT-PCR and protein by western blot/immunohistochemistry. siDCAMKL-1 was encapsulated in Poly(lactide-<it>co</it>-glycolide)-based NPs (NP-siDCAMKL-1); Tumor xenografts were generated in nude mice, treated with NP-siDCAMKL-1 and DAPT (γ-secretase inhibitor) alone and in combination. To measure <it>let-7a </it>and <it>miR-144 </it>expression <it>in vitro</it>, HCT116 cells were transfected with plasmids encoding the firefly luciferase gene with <it>let-7a </it>and <it>miR-144 </it>miRNA binding sites in the 3'UTR.</p> <p>Results</p> <p>Administration of NP-siDCAMKL-1 into HCT116 xenografts resulted in tumor growth arrest, downregulation of proto-oncogene c-Myc and Notch-1 via <it>let-7a </it>and <it>miR-144 </it>miRNA-dependent mechanisms, respectively. A corresponding reduction in <it>let-7a </it>and <it>miR-144 </it>specific luciferase activity was observed <it>in vitro</it>. Moreover, an upregulation of EMT inhibitor <it>miR-200a </it>and downregulation of the EMT-associated transcription factors ZEB1, ZEB2, Snail and Slug were observed <it>in vivo</it>. Lastly, DAPT-mediated inhibition of Notch-1 resulted in HCT116 tumor growth arrest and down regulation of Notch-1 via a <it>miR-144 </it>dependent mechanism.</p> <p>Conclusions</p> <p>These findings demonstrate that nanoparticle-based delivery of siRNAs directed at critical targets such as DCAMKL-1 may provide a novel approach to treat cancer through the regulation of endogenous miRNAs.</p

Helicobacter Pylori's Plasticity Zones Are Novel Transposable Elements

BACKGROUND:Genes present in only certain strains of a bacterial species can strongly affect cellular phenotypes and evolutionary potentials. One segment that seemed particularly rich in strain-specific genes was found by comparing the first two sequenced Helicobacter pylori genomes (strains 26695 and J99) and was named a "plasticity zone". PRINCIPAL FINDINGS:We studied the nature and evolution of plasticity zones by sequencing them in five more Helicobacter strains, determining their locations in additional strains, and identifying them in recently released genome sequences. They occurred as discrete units, inserted at numerous chromosomal sites, and were usually flanked by direct repeats of 5'AAGAATG, a sequence generally also present in one copy at unoccupied sites in other strains. This showed that plasticity zones are transposable elements, to be called TnPZs. Each full length TnPZ contained a cluster of type IV protein secretion genes (tfs3), a tyrosine recombinase family gene ("xerT"), and a large (>or=2800 codon) orf encoding a protein with helicase and DNA methylase domains, plus additional orfs with no homology to genes of known function. Several TnPZ types were found that differed in gene arrangement or DNA sequence. Our analysis also indicated that the first-identified plasticity zones (in strains 26695 and J99) are complex mosaics of TnPZ remnants, formed by multiple TnPZ insertions, and spontaneous and transposable element mediated deletions. Tests using laboratory-generated deletions showed that TnPZs are not essential for viability, but identified one TnPZ that contributed quantitatively to bacterial growth during mouse infection and another that affected synthesis of proinflammatory cytokines in cell culture. CONCLUSIONS:We propose that plasticity zone genes are contained in conjugative transposons (TnPZs) or remnants of them, that TnPZ insertion is mediated by XerT recombinase, and that some TnPZ genes affect bacterial phenotypes and fitness