Expression of phospho-ERK1/2 and PI3-K in benign and malignant gallbladder lesions and its clinical and pathological correlations

Abstract Background An increasing number of studies have shown that ERK and PI3-K/AKT signaling pathways are involved in various human cancers including hepatocellular carcinoma and cholangiocarcinoma. However, few studies have examined gallbladder cancer specimens, and little is known about the clinical and pathological significance of ERK1/2 and PI3-K/AKT signaling changes in gallbladder adenocarcinoma. In this study, we examined phospho-ERK1/2 (p-ERK1/2) and PI3K expression and analyzed its clinicopathological impact in gallbladder adenocarcinoma. Methods Immunohistochemistry was used to detect and compare the frequency of p-ERK1/2 and PI3-K expression in gallbladder adenocarcinoma, peri-tumor tissues, adenomatous polyps, and chronic cholecystitis specimens. Results The positive staining for p-EKR1/2 and PI3-K were 63/108 (58.3%) and 55/108 (50.9%) in gallbladder adenocarcinoma; 14/46 (30.4%) and 5/46 (10.1%) in peri-tumor tissues; 3/15 (20%) and 3/15 (20%) in adenomatous polyps; and 4/35 (11.4%) and 3/35 (8.6%) in chronic cholecystitis. The positive rate of p-ERK1/2 or PI3-K in gallbladder adenocarcinoma was significantly higher than that in peri-tumor tissue (both, P P P P P P P P = 0.062) was associated with decreased overall survival. Multivariate Cox regression analysis showed that increased p-ERK1/2 expression was an independent prognostic predictor in gallbladder carcinoma (P = 0.028). Conclusion Increased expression of p-ERK1/2 and PI3K might contribute to gallbladder carcinogenesis. p-ERK1/2 over-expression is correlated with decreased survival and therefore may serve as an important biological marker in development of gallbladder adenocarcinoma.</p

Mechanisms of c-Myc Degradation by Nickel Compounds and Hypoxia

Nickel (Ni) compounds have been found to cause cancer in humans and animal models and to transform cells in culture. At least part of this effect is mediated by stabilization of hypoxia inducible factor (HIF1a) and activating its downstream signaling. Recent studies reported that hypoxia signaling might either antagonize or enhance c-myc activity depending on cell context. We investigated the effect of nickel on c-myc levels, and demonstrated that nickel, hypoxia, and other hypoxia mimetics degraded c-myc protein in a number of cancer cells (A549, MCF-7, MDA-453, and BT-474). The degradation of the c-Myc protein was mediated by the 26S proteosome. Interestingly, knockdown of both HIF-1α and HIF-2α attenuated c-Myc degradation induced by Nickel and hypoxia, suggesting the functional HIF-1α and HIF-2α was required for c-myc degradation. Further studies revealed two potential pathways mediated nickel and hypoxia induced c-myc degradation. Phosphorylation of c-myc at T58 was significantly increased in cells exposed to nickel or hypoxia, leading to increased ubiquitination through Fbw7 ubiquitin ligase. In addition, nickel and hypoxia exposure decreased USP28, a c-myc de-ubiquitinating enzyme, contributing to a higher steady state level of c-myc ubiquitination and promoting c-myc degradation. Furthermore, the reduction of USP28 protein by hypoxia signaling is due to both protein degradation and transcriptional repression. Nickel and hypoxia exposure significantly increased the levels of dimethylated H3 lysine 9 at the USP28 promoter and repressed its expression. Our study demonstrated that Nickel and hypoxia exposure increased c-myc T58 phosphorylation and decreased USP28 protein levels in cancer cells, which both lead to enhanced c-myc ubiquitination and proteasomal degradation

TRAPPC4-ERK2 Interaction Activates ERK1/2, Modulates Its Nuclear Localization and Regulates Proliferation and Apoptosis of Colorectal Cancer Cells

The trafficking protein particle complex 4 (TRAPPC4) is implicated in vesicle-mediated transport, but its association with disease has rarely been reported. We explored its potential interaction with ERK2, part of the ERK1/2 complex in the Extracellular Signal-regulated Kinase/ Mitogen-activated Protein Kinase (ERK-MAPK) pathway, by a yeast two-hybrid screen and confirmed by co-immunoprecipitation (Co-IP) and glutathione S-transferase (GST) pull-down. Further investigation found that when TRAPPC4 was depleted, activated ERK1/2 specifically decreased in the nucleus, which was accompanied with cell growth suppression and apoptosis in colorectal cancer (CRC) cells. Overexpression of TRAPPC4 promoted cell viability and caused activated ERK1/2 to increase overall, but especially in the nucleus. TRAPPC4 was expressed more highly in the nucleus of CRC cells than in normal colonic epithelium or adenoma which corresponded with nuclear staining of pERK1/2. We demonstrate here that TRAPPC4 may regulate cell proliferation and apoptosis in CRC by interaction with ERK2 and subsequently phosphorylating ERK1/2 as well as modulating the subcellular location of pERK1/2 to activate the relevant signaling pathway

Radiation-Induced c-Jun Activation Depends on MEK1-ERK1/2 Signaling Pathway in Microglial Cells

Radiation-induced normal brain injury is associated with acute and/or chronic inflammatory responses, and has been a major concern in radiotherapy. Recent studies suggest that microglial activation is a potential contributor to chronic inflammatory responses following irradiation; however, the molecular mechanism underlying the response of microglia to radiation is poorly understood. c-Jun, a component of AP-1 transcription factors, potentially regulates neural cell death and neuroinflammation. We observed a rapid increase in phosphorylation of N-terminal c-Jun (on serine 63 and 73) and MAPK kinases ERK1/2, but not JNKs, in irradiated murine microglial BV2 cells. Radiation-induced c-Jun phosphorylation is dependent on the canonical MEK-ERK signaling pathway and required for both ERK1 and ERK2 function. ERK1/2 directly interact with c-Jun in vitro and in cells; meanwhile, the JNK binding domain on c-Jun is not required for its interaction with ERK kinases. Radiation-induced reactive oxygen species (ROS) potentially contribute to c-Jun phosphorylation through activating the ERK pathway. Radiation stimulates c-Jun transcriptional activity and upregulates c-Jun-regulated proinflammatory genes, such as tumor necrosis factor-α, interleukin-1β, and cyclooxygenase-2. Pharmacologic blockade of the ERK signaling pathway interferes with c-Jun activity and inhibits radiation-stimulated expression of c-Jun target genes. Overall, our study reveals that the MEK-ERK1/2 signaling pathway, but not the JNK pathway, contributes to the c-Jun-dependent microglial inflammatory response following irradiation

New Insights into the Mechanisms of Embryonic Stem Cell Self-Renewal under Hypoxia: A Multifactorial Analysis Approach

Previous reports have shown that culturing mouse embryonic stem (mES) cells at different oxygen tensions originated different cell proliferation patterns and commitment stages depending on which signaling pathways are activated or inhibited to support the pluripotency state. Herein we provide new insights into the mechanisms by which oxygen is influencing mES cell self-renewal and pluripotency. A multifactorial approach was developed to rationally evaluate the singular and interactive control of MEK/ERK pathway, GSK-3 inhibition, and LIF/STAT3 signaling at physiological and non-physiological oxygen tensions. Collectively, our methodology revealed a significant role of GSK-3-mediated signaling towards maintenance of mES cell pluripotency at lower O2 tensions. Given the central role of this signaling pathway, future studies will need to focus on the downstream mechanisms involved in ES cell self-renewal under such conditions, and ultimately how these findings impact human models of pluripotency

Point Mutations in c-Myc Uncouple Neoplastic Transformation from Multiple Other Phenotypes in Rat Fibroblasts

Deregulation of c-Myc (Myc) occurs in many cancers. In addition to transforming various cell types, Myc also influences additional transformation-associated cellular phenotypes including proliferation, survival, genomic instability, reactive oxygen species production, and metabolism. Although Myc is wild type in most cancers (wtMyc), it occasionally acquires point mutations in certain lymphomas. Some of these mutations confer a survival advantage despite partially attenuating proliferation and transformation. Here, we have evaluated four naturally-occurring or synthetic point mutations of Myc for their ability to affect these phenotypes, as well as to promote genomic instability, to generate reactive oxygen species and to up-regulate aerobic glycolysis and oxidative phosphorylation. Our findings indicate that many of these phenotypes are genetically and functionally independent of one another and are not necessary for transformation. Specifically, the higher rate of glucose metabolism known to be associated with wtMyc deregulation was found to be independent of transformation. One mutation (Q131R) was greatly impaired for nearly all of the studied Myc phenotypes, yet was able to retain some ability to transform. These findings indicate that, while the Myc phenotypes examined here make additive contributions to transformation, none, with the possible exception of increased reliance on extracellular glutamine for survival, are necessary for achieving this state

Myc proteins in brain tumor development and maintenance

Myc proteins are often deregulated in human brain tumors, especially in embryonal tumors that affect children. Many observations have shown how alterations of these pleiotropic Myc transcription factors provide initiation, maintenance, or progression of tumors. This review will focus on the role of Myc family members (particularly c-myc and Mycn) in tumors like medulloblastoma and glioma and will further discuss how to target stabilization of these proteins for future brain tumor therapies

E6-mediated activation of JNK drives EGFR signalling to promote proliferation and viral oncoprotein expression in cervical cancer

Human papillomaviruses (HPV) are a major cause of malignancy worldwide, contributing to ~5% of all human cancers including almost all cases of cervical cancer and a growing number of ano-genital and oral cancers. HPV-induced malignancy is primarily driven by the viral oncogenes, E6 and E7, which manipulate host cellular pathways to increase cell proliferation and enhance cell survival, ultimately predisposing infected cells to malignant transformation. Consequently, a more detailed understanding of viral-host interactions in HPV-associated disease offers the potential to identify novel therapeutic targets. Here, we identify that the c-Jun N-terminal kinase (JNK) signalling pathway is activated in cervical disease and in cervical cancer. The HPV E6 oncogene induces JNK1/2 phosphorylation in a manner that requires the E6 PDZ binding motif. We show that blockade of JNK1/2 signalling using small molecule inhibitors, or knockdown of the canonical JNK substrate c-Jun, reduces cell proliferation and induces apoptosis in cervical cancer cells. We further demonstrate that this phenotype is at least partially driven by JNK-dependent activation of EGFR signalling via increased expression of EGFR and the EGFR ligands EGF and HB-EGF. JNK/c-Jun signalling promoted the invasive potential of cervical cancer cells and was required for the expression of the epithelial to mesenchymal transition (EMT)-associated transcription factor Slug and the mesenchymal marker Vimentin. Furthermore, JNK/c-Jun signalling is required for the constitutive expression of HPV E6 and E7, which are essential for cervical cancer cell growth and survival. Together, these data demonstrate a positive feedback loop between the EGFR signalling pathway and HPV E6/E7 expression, identifying a regulatory mechanism in which HPV drives EGFR signalling to promote proliferation, survival and EMT. Thus, our study has identified a novel therapeutic target that may be beneficial for the treatment of cervical cancer

Stimulus responsive graphene scaffolds for tissue engineering

Tissue engineering (TE) is an emerging area that aims to repair damaged tissues and organs by combining different scaffold materials with living cells. Recently, scientists started to engineer a new generation of nanocomposite scaffolds able to mimic biochemical and biophysical mechanisms to modulate the cellular responses promoting the restoration of tissue structure or function. Due to its unique electrical, topographical and chemical properties, graphene is a material that holds a great potential for TE, being already considered as one of the best candidates for accelerating and guiding stem cell differentiations. Although this is a promising field there are still some challenges to overcome, such as the efficient control of the differentiation of the stem cells, especially in graphene-based microenvironments. Hence, this chapter will review the existing research related to the ability of graphene and its derivatives (graphene oxide and reduced graphene oxide) to induce stem cell differentiation into diverse lineages when under the influence of electrical, mechanical, optical and topographic stimulations