Browsing by Subject "animal model"

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Open Access
Adenosine A2A receptors intrinsically regulate CD8+ T cells in the tumor microenvironment
(American Association for Cancer Research Inc., 2014) Cekic, C.; Linden J.
Adenosine A2A receptor (A2AR) blockade enhances innate and adaptive immune responses. However, mouse genetic studies have shown that A2AR deletion does not inhibit the growth of all tumor types. In the current study, we showed that growth rates for ectopic melanoma and bladder tumors are increased in Adora2a-/- mice within 2 weeks of tumor inoculation. A2AR deletion in the host reduced numbers of CD8+ T cells and effector-memory differentiation of all T cells. To examine intrinsic functions in T cells, we generated mice harboring a T-cell-specific deletion of A2AR. In this host strain, tumor-bearing mice displayed increased growth of ectopic melanomas, decreased numbers of tumor-associated T cells, reduced effector-memory differentiation, and reduced antiapoptotic IL7Rα (CD127) expression on antigen-experienced cells. Intratumoral pharmacologic blockade similarly reduced CD8+ T-cell density within tumors in wild-type hosts. We found that A2AR-proficient CD8+ T cells specific for melanoma cells displayed a relative survival advantage in tumors. Thus, abrogating A2AR signaling appeared to reduce IL7R expression, survival, and differentiation of T cells in the tumor microenvironment. One implication of these results is that the antitumor effects of A2AR blockade that can be mediated by activation of cytotoxic T cells may be overcome in some tumor microenvironments as a result of impaired T-cell maintenance and effector-memory differentiation. Thus, our findings imply that the efficacious application of A2AR inhibitors for cancer immunotherapy may require careful dose optimization to prevent activation-induced T-cell death in tumors. ©2014 AACR.
Open Access
Herpes simplex virus 1 amplicon vector-mediated siRNA targeting epidermal growth factor receptor inhibits growth of human glioma cells in vivo
(2005) Saydam O.; Glauser, D.L.; Heid I.; Turkeri G.; Hilbe, M.; Jacobs, A.H.; Ackermann, M.; Fraefel, C.
In primary glioblastomas and other tumor types, the epidermal growth factor receptor (EGFR) is frequently observed with alterations, such as amplification, structural rearrangements, or overexpression of the gene, suggesting an important role in glial tumorigenesis and progression. In this study, we investigated whether posttranscriptional gene silencing by vector-mediated RNAi to inhibit EGFR expression can reduce the growth of cultured human gli36 glioma cells. To "knock down" EGFR expression, we have created HSV-1-based amplicons that contain the RNA polymerase III-dependent H1 promoter to express double-stranded hairpin RNA directed against EGFR at two different locations (pHSVsiEGFR I and pHSVsiEGFR II). We demonstrate that both pHSVsiEGFR I and pHSVsiEGFR II mediated knock-down of transiently transfected full-length EGFR or endogenous EGFR in a dose-dependent manner. The knock-down of EGFR resulted in the growth inhibition of human glioblastoma (gli36-luc) cells both in culture and in athymic mice in vivo. Cell cycle analysis and annexin V staining revealed that siRNA-mediated suppression of EGFR induced apoptosis. Overall HSV-1 amplicons can mediate efficient and specific posttranscriptional gene silencing. Copyright © The American Society of Gene Therapy.
Open Access
Induction of potent protection against acute and latent herpes simplex virus infection in mice vaccinated with dendritic cells
(2013) Ghasemi, M.; Erturk, M.; Buruk, K.; Sonmez, M.
Background aims. Dendritic cells (DCs) are the most potent antigen presenting cells of the immune system and have been under intense study with regard to their use in immunotherapy against cancer and infectious disease agents. In the present study, DCs were employed to assess their value in protection against live virus challenge in an experimental model using lethal and latent herpes simplex virus (HSV) infection in Balb/c mice. Methods. DCs obtained ex vivo in the presence of granulocyte-macrophage colony-stimulating factor and interleukin-4 were loaded with HSV-1 proteins (DC/HSV-1 vaccine). Groups of mice were vaccinated twice, 7 days apart, via subcutaneous, intraperitoneal or intramuscular routes with DC/HSV-1 and with mock (DC without virus protein) and positive (alum adjuvanted HSV-1 proteins [HSV-1/ALH]) control vaccines. After measuring anti-HSV-1 antibody levels in blood samples, mice were given live HSV-1 intraperitoneally or via ear pinna to assess the protection level of the vaccines with respect to lethal or latent infection challenge. Results. Intramuscular, but not subcutaneous or intraperitoneal, administration of DC/HSV-1 vaccine provided complete protection against lethal challenge and establishment of latent infection as assessed by death and virus recovery from the trigeminal ganglia. It was also shown that the immunity was not associated with antibody production because DC/HSV-1 vaccine, as opposed to HSV-1/ALH vaccine, produced very little, if any, HSV-1-specific antibody. Conclusions. Overall, our results may have some impact on the design of vaccines against genital HSV as well as chronic viral infections such as hepatitis B virus, hepatitis C virus and human immunodeficiency virus. © 2013, International Society for Cellular Therapy.
Open Access
MST1 is a multifunctional caspase-independent inhibitor of androgenic signaling
(2011) Cinar, B.; Collak F.K.; Lopez, D.; Akgul, S.; Mukhopadhyay, N.K.; Kilicarslan, M.; Gioeli, D.G.; Freeman, M.R.
The MST1 serine - threonine kinase, a component of the RASSF1-LATS tumor suppressor network, is involved in cell proliferation and apoptosis and has been implicated in cancer. However, the physiologic role of MST1 in prostate cancer (PCa) is not well understood. Here, we investigated the possibility of a biochemical and functional link between androgen receptor (AR) and MST1 signaling. We showed that MST1 forms a protein complex with AR and antagonizes AR transcriptional activity as shown by coimmunoprecipitation (co-IP), promoter reporter analysis, and molecular genetic methods. In vitro kinase and site-specific mutagenesis approaches indicate that MST1 is a potent AR kinase; however, the kinase activity of MST1 and its proapoptotic functions were shown not to be involved in inhibition of AR. MST1 was also found in AR - chromatin complexes, and enforced expression of MST1 reduced the binding of AR to a well-characterized, androgen-responsive region within the prostate-specific antigen promoter. MST1 suppressed PCa cell growth in vitro and tumor growth in mice. Because MST1 is also involved in regulating the AKT1 pathway, this kinase may be an important new link between androgenic and growth factor signaling and a novel therapeutic target in PCa. ©2011 AACR.
Open Access
Resveratrol affects histone 3 lysine 27 methylation of vessels and blood biomarkers in DOCA salt-induced hypertension
(Kluwer Academic Publishers, 2015) Han, S.; Uludag, M.O.; Usanmaz, S.E.; Ayaloglu-Butun F.; Akcali, K.C.; Demirel-Yilmaz, E.
Hypertension is a risk factor for the cardiovascular diseases. Although, several drugs are used to treat hypertension, the success of the antihypertensive therapy is limited. Resveratrol decreases blood pressure in animal models of hypertension. This study researched the mechanisms behind the effects of resveratrol on hypertension. Hypertension was induced by using the deoxycorticosterone acetate (DOCA)-induced (15 mg/kg twice per week, subcutaneously) salt-sensitive hypertension model of Wistar rats. Hypertension caused a decrease in endothelium-dependent relaxations of the isolated thoracic aorta. Resveratrol treatment (50 mg/l in drinking water) prevented DOCA salt-induced hypertension, but did not improve endothelial dysfunction. Plasma nitric oxide (NO), asymmetric dimethylarginine (ADMA), total antioxidant capacity (TAC) and hydrogen sulfide (H2S) levels were not changed by DOCA salt application. However, treatment of resveratrol significantly decreased ADMA and increased TAC and H2S levels. NO level in circulation was not significantly changed by resveratrol. DOCA salt application and resveratrol treatment also caused an alteration in the epigenetic modification of vessels. Staining pattern of histone 3 lysine 27 methylation (H3K27me3) in the aorta and renal artery sections was changed. These results show that preventive effect of resveratrol on DOCA salt-induced hypertension might due to its action on the production of some blood biomarkers and the epigenetic modification of vessels that would focus upon new aspect of hypertension prevention and treatment. © 2014, Springer Science+Business Media Dordrecht.
Open Access
Variation in the attachment of Streptococcus pneumoniae to human pharyngeal epithelial cells after treatment with S-carboxymethylcysteine
(2008) Suer, E.; Sayrac, S.; Sarinay, E.; Ozturk H.E.; Turkoz, M.; Ichinose, A.; Nagatake, T.; Ahmed, K.
S-carboxymethylcysteine (S-CMC) is a mucolytic agent that can prevent respiratory infection by decreasing the attachment of respiratory pathogens to human pharyngeal epithelial cells (HPECs). Streptococcus pneumoniae is a major cause of respiratory infections. A previous study revealed that treatment of S. pneumoniae with S-CMC caused a decrease in the attachment of this bacterium to HPECs. In the present study we found that the effect of S-CMC varied according to hosts and strains. S-CMC treatment altered the surface structure of S. pneumoniae, resulting in a decrease of attachment, without affecting the virulence of the bacteria. © 2008 Japanese Society of Chemotherapy and The Japanese Association for Infectious Diseases.