IGF-IR-dependent expression of Survivin is required for T-antigen-mediated protection from apoptosis and proliferation of neural progenitors.

The insulin-like growth factor-1 receptor (IGF-IR) and the human polyomavirus JCV protein, T-antigen cooperate in the transformation of neuronal precursors in the cerebellum, which may be a contributing factor in the development of brain tumors. Because it is not clear why T-antigen requires IGF-IR for transformation, we investigated this process in neural progenitors from IGF-IR knockout embryos (ko-IGF-IR) and from their wild-type nontransgenic littermates (wt-IGF-IR). In contrast to wt-IGF-IR, the brain and dorsal root ganglia of ko-IGF-IR embryos showed low levels of the antiapoptotic protein Survivin, accompanied by elevated numbers of apoptotic neurons and an earlier differentiation phenotype. In wt-IGF-IR neural progenitors in vitro, induction of T-antigen expression tripled the expression of Survivin and accelerated cell proliferation. In ko-IGF-IR progenitors induction of T-antigen failed to increase Survivin, resulting in massive apoptosis. Importantly, ectopic expression of Survivin protected ko-IGF-IR progenitor cells from apoptosis and siRNA inhibition of Survivin activated apoptosis in wt-IGF-IR progenitors expressing T-antigen. Our results indicate that reactivation of the antiapoptotic Survivin may be a critical step in JCV T-antigen-induced transformation, which in neural progenitors requires IGF-IR.

Induction of an antiinflammatory effect and prevention of cartilage damage in rat knee osteoarthritis by CF101 treatment.

OBJECTIVE: Studies have suggested that rheumatoid arthritis (RA) and osteoarthritis (OA) share common characteristics. The highly selective A(3) adenosine receptor agonist CF101 was recently defined as a potent antiinflammatory agent for the treatment of RA. The purpose of this study was to examine the effects of CF101 on the clinical and pathologic manifestations of OA in an experimental animal model. METHODS: OA was induced in rats by monosodium iodoacetate, and upon disease onset, oral treatment with CF101 (100 microg/kg given twice daily) was initiated. The A(3) adenosine receptor antagonist MRS1220 (100 microg/kg given twice daily) was administered orally, 30 minutes before CF101 treatment. The OA clinical score was monitored by knee diameter measurements and by radiographic analyses. Histologic analyses were performed following staining with hematoxylin and eosin, Safranin O-fast green, or toluidine blue, and histologic changes were scored according to a modified Mankin system. Signaling proteins were assayed by Western blotting; apoptosis was detected via immunohistochemistry and TUNEL analyses. RESULTS: CF101 induced a marked decrease in knee diameter and improved the changes noted on radiographs. Administration of MRS1220 counteracted the effects of CF101. CF101 prevented cartilage damage, osteoclast/osteophyte formation, and bone destruction. In addition, CF101 markedly reduced pannus formation and lymphocyte infiltration. Mechanistically, CF101 induced deregulation of the NF-kappaB signaling pathway, resulting in down-regulation of tumor necrosis factor alpha. Consequently, CF101 induced apoptosis of inflammatory cells that had infiltrated the knee joints; however, it prevented apoptosis of chondrocytes. CONCLUSION: CF101 deregulated the NF-kappaB signaling pathway involved in the pathogenesis of OA. CF101 induced apoptosis of inflammatory cells and acted as a cartilage protective agent, which suggests that it would be a suitable candidate drug for the treatment of OA.

The A3 adenosine receptor agonist CF502 inhibits the PI3K, PKB/Akt and NF-kappaB signaling pathway in synoviocytes from rheumatoid arthritis patients and in adjuvant-induced arthritis rats.

The A(3) adenosine receptor (A(3)AR) is over-expressed in inflammatory cells and was defined as a target to combat inflammation. Synthetic agonists to this receptor, such as IB-MECA and Cl-IB-MECA, exert an anti-inflammatory effect in experimental animal models of adjuvant- and collagen-induced arthritis. In this study we present a novel A(3)AR agonist, CF502, with high affinity and selectivity at the human A(3)AR. CF502 induced a dose dependent inhibitory effect on the proliferation of fibroblast-like synoviocytes (FLS) via de-regulation of the nuclear factor-kappa B (NF-kappaB) signaling pathway. Furthermore, CF502 markedly suppressed the clinical and pathological manifestations of adjuvant-induced arthritis (AIA) in a rat experimental model when given orally at a low dose (100 microg/kg). As is typical of other G-protein coupled receptors, the A(3)AR expression level was down-regulated shortly after treatment with agonist CF502 in paw and in peripheral blood mononuclear cells (PBMCs) derived from treated AIA animals. Subsequently, a decrease in the expression levels of protein kinase B/Akt (PKB/Akt), IkappaB kinase (IKK), I kappa B (IkappaB), NF-kappaB and tumor necrosis factor-alpha (TNF-alpha) took place. In addition, the expression levels of glycogen synthase kinase-3 beta (GSK-3beta), beta-catenin, and poly(ADP-ribose)polymerase (PARP), known to control the level and activity of NF-kappaB, were down-regulated upon treatment with CF502. Taken together, CF502 inhibits FLS growth and the inflammatory manifestations of arthritis, supporting the development of A(3)AR agonists for the treatment of rheumatoid arthritis.

The A3 adenosine receptor agonist CF102 induces apoptosis of hepatocellular carcinoma via de-regulation of the Wnt and NF-kappaB signal transduction pathways.

The A3 adenosine receptor (A(3)AR) is highly expressed in tumors and was suggested as a target for cancer treatment. In this study, we show that A(3)AR is highly expressed in tumor tissues and in peripheral blood mononuclear cells (PBMCs) derived from patients with HCC, as well as from HCC tumor-bearing rats. The high expression level of the receptor was directly correlated to overexpression of NF-kappaB, known as a transcription factor of A(3)AR. CF102, a synthetic highly selective agonist to A(3)AR induced a marked dose response inhibition of tumor growth in N1S1 HCC tumor rats, via de-regulation of the NF-kappaB and the Wnt signal transduction pathways, resulting in apoptosis of tumor cells. Taken together, A(3)AR is highly expressed in tumors and PBMCs of HCC patients and tumor-bearing rats. CF102 induced apoptosis and tumor growth inhibition. These data suggest A(3)AR as a novel targeted therapy to treat HCC.