Recent evidence indicates that human cytomegalovirus (HCMV) infection occurs in a high percentage of human malignant gliomas in vivo, as the HCMV immediate early-1 (IE1) protein is detected in >90% of these tumors. The HCMV IE1 protein is essential for viral infection and has potent transactivating and oncomodulatory properties. To investigate a potential role of HCMV in glioma biology, we stably expressed the HCMV IE1 gene product in immortalized and malignant human glial cells. Here we show that stable IE1 expression can differentially affect the growth of human glioblastoma cells, resulting in either growth proliferation or arrest. IE1 expression led to dysregulation of phosphatidylinositol 3-kinase/AKT activity, Rb phosphorylation, and expression of the p53 family of proteins. In U87 and U118 glioblastoma cells, IE1 induced cellular proliferation paralleled by reduction in steady-state expression level of Rb and p53 family proteins (including p53, p63, or p73) and simultaneous induction of the phosphatidylinositol 3-kinase/AKT signaling pathway. In contrast, IE1 expression in LN229 and U251 glioblastoma cells and immortalized human astrocytes was associated with increased expression of p53 family proteins, accompanied by growth arrest or lack of enhanced proliferation. Moreover, IE1 promoted cell cycle entry and DNA synthesis of human glioma cells on both stable expression in tumor-derived cell lines as well as transient expression in primary glioblastoma cells. These findings indicate that HCMV IE1 can significantly affect important oncogenic signaling pathways in glioblastoma cells. [Cancer Res 2008;68(3):724-30]
Given our previous findings that human cytomegalovirus (HCMV) nucleic acids and proteins are expressed in human malignant glioma in vivo, we investigated cellular signaling events associated with HCMV infection of human glioma and astroglial cells. HCMV infection caused rapid activation of the phosphatidylinositol-3 kinase (PI-3K) effector AKT kinase in human astro-glial and fibroblast cells, and induced tyrosine phosphorylation of phospholipase Cgamma (PLCgamma). Co-immunoprecipitation experiments revealed association of the p85 regulatory subunit of PI-3K with a high-molecular weight protein phosphorylated on tyrosine, following short-term exposure to HCMV. In contrast to a previous report, we were unable to confirm the identity of this high-molecular weight protein as being the epidermal growth factor receptor (EGFR). Stimulation of glioma and fibroblast cell lines over-expressing EGFR with HCMV (whole virus) or soluble glycoprotein B did not induce tyrosine phosphorylation of the receptor, as did the genuine ligand, EGF. Furthermore, we found that expression levels of the human ErbB1-4 receptors were not rate-limiting for HCMV infection. Dispensability of EGFR function during early HCMV infection was substantiated by demonstration of viral immediate early gene expression in cells lacking the EGFR gene, indicating that HCMV may promote oncogenic signaling pathways independently of EGFR activation. Among non-receptor cellular kinases, HCMV infection induced phosphorylation of focal adhesion kinase (FAK) Tyr397, which is indispensable for integrin-mediated cell migration and invasion. HCMV-induced FAK activation was paralleled by increased extracellular matrix-dependent migration of human malignant glioma but not normal astro-glial cells, suggesting that HCMV can selectively augment glioma cell invasiveness.
We present a novel method of obtaining the energy eigenvalue spectrum for a Hamiltonian whose interaction term is a polynomial in one independent variable. The method is simple in concept and can be easily implemented on a minicomputer with a Basic compiler. The method extends the range of potentials for which the energy spectra is easily obtained and is therefore of value to students in introductory quantum mechanics. To show the utility of the method we use it to obtain the energy spectra for the anharmonic oscillator and for a non-Hermitian Hamiltonian.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.