Human Sulfatase 2 inhibits in vivo tumor growth of MDA-MB-231 human breast cancer xenografts.

BACKGROUND: Extracellular human sulfatases modulate growth factor signaling by alteration of the heparin/heparan sulfate proteoglycan (HSPG) 6-O-sulfation state. HSPGs bind to numerous growth factor ligands including fibroblast growth factors (FGF), epidermal growth factors (EGF), and vascular endothelial growth factors (VEGF), and are critically important in the context of cancer cell growth, invasion, and metastasis. We hypothesized that sulfatase activity in the tumor microenvironment would regulate tumor growth in vivo. METHODS: We established a model of stable expression of sulfatases in the human breast cancer cell line MDA-MB-231 and purified recombinant human Sulfatase 2 (rhSulf2) for exogenous administration. In vitro studies were performed to measure effects on breast cancer cell invasion and proliferation, and groups were statistically compared using Student's t-test. The effects of hSulf2 on tumor progression were tested using in vivo xenografts with two methods. First, MDA-MB-231 cells stably expressing hSulf1, hSulf2, or both hSulf1/hSulf2 were grown as xenografts and the resulting tumor growth and vascularization was compared to controls. Secondly, wild type MDA-MB-231 xenografts were treated by short-term intratumoral injection with rhSulf2 or vehicle during tumor growth. Ultrasound analysis was also used to complement caliper measurement to monitor tumor growth. In vivo studies were statistically analyzed using Student's t test. RESULTS: In vitro, stable expression of hSulf2 or administration of rhSulf2 in breast cancer cells decreased cell proliferation and invasion, corresponding to an inhibition of ERK activation. Stable expression of the sulfatases in xenografts significantly suppressed tumor growth, with complete regression of tumors expressing both hSulf1 and hSulf2 and significantly smaller tumor volumes in groups expressing hSulf1 or hSulf2 compared to control xenografts. Despite significant suppression of tumor volume, sulfatases did not affect vascular density within the tumors. By contrast, transient exogenous treatment of MDA-MB-231 xenografts with rhSulf2 was not sufficient to inhibit or reverse tumor growth. CONCLUSION: These data indicate that in vivo progression of human breast cancer xenografts can be inhibited with sulfatase expression, and therapeutic effect requires constant delivery at the tumor site. Our results support a direct effect of sulfatases on tumor growth or invasion, rather than an effect in the stromal compartment.

Modified vaccinia virus ankara recombinants are as potent as vaccinia recombinants in diversified prime and boost vaccine regimens to elicit therapeutic antitumor responses.

Cancer vaccine regimens use various strategies to enhance immune responses to specific tumor-associated antigens (TAAs), including the increasing use of recombinant poxviruses [vaccinia (rV) and fowlpox (rF)] for delivery of the TAA to the immune system. However, the use of replication competent vectors with the potential of adverse reactions have made attenuation a priority for next-generation vaccine strategies. Modified vaccinia Ankara (MVA) is a replication defective form of vaccinia virus. Here, we investigated the use of MVA encoding a tumor antigen gene, carcinoembryonic antigen (CEA), in addition to multiple costimulatory molecules (B7-1, intercellular adhesion molecule-1, and lymphocyte function-associated antigen-3 designated TRICOM). Vaccination of mice with MVA-CEA/TRICOM induced potent CD4+ and CD8+ T-cell responses specific for CEA. MVA-CEA/TRICOM could be administered twice in vaccinia naïve mice and only a single time in vaccinia-immune mice before being inhibited by antivector-immune responses. The use of MVA-CEA/TRICOM in a diversified prime and boost vaccine regimen with rF-CEA/TRICOM, however, induced significantly greater levels of both CD4+ and CD8+ T-cell responses specific for CEA than that seen with rV-CEA/TRICOM prime and rF-CEA/TRICOM boost. In a self-antigen tumor model, the diversified MVA-CEA/TRICOM/rF-CEA/ TRICOM vaccination regimen resulted in a significant therapeutic antitumor response as measured by increased survival, when compared with the diversified prime and boost regimen, rV-CEA/TRICOM/rF-CEA/TRICOM. The studies reported here demonstrate that MVA, when used as a prime in a diversified vaccination, is clearly comparable with the regimen using the recombinant vaccinia in both the induction of cellular immune responses specific for the "self"-TAA transgene and in antitumor activity.

Heterologous prime/boost immunization of rhesus monkeys by using diverse poxvirus vectors.

As the diversity of potential immunogens increases within certain classes of vectors, the possibility has arisen of employing heterologous prime/boost immunizations using diverse members of the same family of vectors. The present study was initiated to explore the use of divergent pox vectors in a prime/boost regimen to elicit high-frequency cellular immune responses to human immunodeficiency virus type 1 envelope and simian immunodeficiency virus gag in rhesus monkeys. We demonstrated that monkeys vaccinated with a recombinant modified vaccinia virus Ankara (rMVA) prime/recombinant fowlpox virus (rFPV) boost regimen and monkeys vaccinated with a recombinant vaccinia virus prime/rFPV boost regimen developed comparable cellular immune responses that were greater in magnitude than those elicited by a homologous prime/boost with rMVA. Nevertheless, comparable magnitude recall cellular immune responses were observed in monkeys vaccinated with heterologous and homologous recombinant poxvirus following challenge with the CXCR4-tropic SHIV-89.6P. Consistent with this finding, comparable levels of containment of viral replication and CD4(+) T-lymphocyte preservation were seen in these groups of recombinant poxvirus-vaccinated monkeys. This study supports further exploration of combining recombinant vectors of the same family in prime/boost immunization strategies to optimize vaccine-elicited cellular immune responses.

A recombinant vector expressing transgenes for four T-cell costimulatory molecules (OX40L, B7-1, ICAM-1, LFA-3) induces sustained CD4+ and CD8+ T-cell activation, protection from apoptosis, and enhanced cytokine production.

The role of OX40L on the activation of T cells was investigated using poxvirus vectors expressing OX40L alone or in combination with three other T-cell costimulatory molecules: B7-1, ICAM-1, and LFA-3. Poxvirus vector-infected cells were used to stimulate nai;ve or activated CD4(+) and CD8(+) T cells. These studies demonstrate that (a) OX40L plays a role in sustaining the long-term proliferation of CD8(+) T cells in addition to the known effect on CD4(+) T cells following activation, (b) OX40L enhances the production of Th1 cytokines (IL-2, IFN-gamma, and TNF-alpha) from both CD4(+) and CD8(+) while no change in IL-4 expression was observed, and (c) the anti-apoptotic effect of OX40L on T cells is likely the result of sustained expression of anti-apoptotic genes while genes involved in apoptosis are inhibited. In addition, these are the first studies to demonstrate that the combined use of a vector driving the expression of OX40L with three other costimulatory molecules (B7-1, ICAM-1, and LFA-3) both enhances initial activation and then further potentiates sustained activation of nai;ve and effector T cells.

Mature CD83(+) dendritic cells infected with recombinant gp100 vaccinia virus stimulate potent antimelanoma T cells.

BACKGROUND: Mature dendritic cells (DCs) are potent antigen-presenting cells that activate naive T lymphocytes and initiate cellular immune responses. The ability of CD83(+) mature DCs infected with vaccinia virus encoding the gp100 melanoma transgene (rV-gp100) to stimulate an antimelanoma CD8(+) T-cell response was investigated. METHODS: Monocyte-derived immature or CD83(+) mature DCs were infected with rV-gp100. The activation state of the DCs and the expression of gp100 protein were evaluated by flow cytometry. The reactivity of antimelanoma CD8(+) T cells was confirmed by measuring specific interferon gamma secretion by using enzyme-linked immunosorbent assay in a mixed-tumor lymphocyte culture. RESULTS: Both immature and CD83(+) mature DCs expressed gp100 protein when the DCs were infected with rV-gp100. Calcium-signaling agents were required to induce maturation of both infected and noninfected immature DCs. Only rV-gp100-infected CD83(+) DCs induced CD8(+) T cells, after a single stimulation that recognized both peptide-pulsed target cells to multiple gp100 epitopes and a melanoma cell line that endogenously expressed gp100 antigen. CONCLUSIONS: CD83(+) DCs transduced with rV-gp100 are capable of generating a strong CD8(+) T-cell response against melanoma tumor cells. Expression of melanoma antigens by mature DCs offers the potential advantage of presenting multiple endogenously processed T-cell epitopes and using multiple HLA restriction elements for antimelanoma vaccine therapy.

Direct relationship between suppression of virus-specific immunity and emergence of cytomegalovirus disease in simian AIDS.

Although opportunistic infections like cytomegalovirus (CMV) are common sequelae of end-stage AIDS, the immune events leading to CMV reactivation in human immunodeficiency virus (HIV)-infected individuals are not well defined. The role of cellular and humoral CMV-specific immune responses in immune control of latent CMV infection was evaluated prospectively in a cohort of 11 simian immunodeficiency virus (SIV)-infected CMV-seropositive rhesus macaques, 6 of whom had histologic evidence of CMV disease at death. Macaques with CMV disease differed from macaques without CMV disease in having significantly higher levels of plasma SIV RNA and CMV DNA and significantly lower titers of anti-CMV binding antibodies (Abs) at the time of death. A significant decline in anti-CMV Abs and CMV-specific CD4(+) and CD8(+) T lymphocytes over time was observed in the macaques with CMV disease, but not in the macaques without CMV disease. Reduction in CMV-specific CD8(+) T lymphocytes and anti-CMV neutralizing Abs was significantly correlated with a decline in CMV-specific CD4(+) T lymphocytes. Although declines in CMV-specific T lymphocytes alone were sufficient for reactivation of low-level CMV viremia, high-level viremia (>1,000 copies of CMV DNA per ml of plasma) was observed when anti-CMV neutralizing and binding Abs had also declined. Thus, the occurrence of CMV reactivation-associated disease in AIDS is associated with suppression of both cellular and humoral CMV-specific immune responses. The underlying mechanism may be a dysfunction of memory B and CD8(+) T lymphocytes associated with SIV-induced impairment of CMV-specific CD4(+) T-cell help.

Síntesis de partículas 10S en células infectadas con aftovirus / Synthesis of 105 particles in cells infected with aphtovirus

Mediante experiencias de marcación radioactiva en células BHK21 o de riñón fetal bovino infectadas con Aftovirus, se detectó una fracción viral de coeficiente de sedimentación 10S. Por su coeficiente de sedimentación se trataría de un trímero, el cual precedería a las procápsides en el proceso morfogenético. La estructura resultante de la unión de 20 trímeros permitiría explicar las características distintivas del género Aftovirus