Docosahexaenoic acid reduces inflammation and joint destruction in mice with collagen-induced arthritis.

OBJECTIVE: This study was designed to determine the anti-inflammatory activity of docosahexaenoic acid (DHA), alone and in combination with eicosapentaenoic acid (EPA), in a murine model of rheumatoid arthritis, collagen induced arthritis (CIA). METHODS: The CIA was induced in DBA/1OlaHsd mice by the injection of bovine type II collagen in Freunds's complete adjuvant on days 0 and 21. Mice were fed modified diets containing DHA and/or EPA for 4 weeks prior to the initial collagen injection until study termination at day 45. The severity of CIA was assessed by measuring erythema, edema and mobility of the digits on the fore and hind paws, as well as histology. The level of serum anti-collagen antibodies was determined by ELISA. The ex vivo effects of DHA and/or EPA on splenocyte proliferation and cytokine production were evaluated by BrdU method and ELISA. RESULTS: Prophylactic treatment with DHA, and not DHA/EPA, significantly reduced arthritis severity and joint damage. Treatment with DHA also decreased anti-collagen (CII) antibodies in vivo, downregulated interleukin-1ß, interferonγ and upregulated protective interleukin-10 ex vivo. CONCLUSION: Prophylactic treatment with DHA was efficacious in a mouse model of rheumatoid arthritis and may be a useful intervention strategy against inflammatory arthritis.

Transgenic E2F1 expression in the mouse brain induces a human-like bimodal pattern of tumors.

The Rb/E2F pathway is deregulated in most human brain tumors, and the finding that loss of E2F1 reduced pituitary tumorigenesis in Rb(+/-) mice suggests that loss of pRb induces brain tumors by activating E2F1. We therefore investigated the role of E2F1 in the development and maintenance of brain cancer using a transgenic mouse model engineered to express E2F1 specifically within glial cells (GFAP-tgE2F1). GFAP-tgE2F1 mice developed a highly penetrant phenotype characterized by neurologic defects, and examination of the brains revealed the presence of brain tumors in 20% of these animals. Importantly, the distribution of tumors according to mouse age suggests the existence of a bimodal pattern of tumor development, forcing a comparison with the human disease. Mice, at an early age, with deregulated E2F1 show the formation of embryonal brain tumors such as medulloblastoma, choroid plexus carcinoma, and primary neuroectodermal tumor. Conversely, at an older age, mice escaping embryonal tumor formation present with malignant gliomas, which are typically identified in the human adult population. Thus, this study offers the first evidence for a global role of E2F1 in the formation and maintenance of multilineage brain tumors, irrefutably establishing E2F1 as an oncogene in the brain.

A novel CRM1-dependent nuclear export signal in adenoviral E1A protein regulated by phosphorylation.

Adenoviral E1A is a versatile protein that can reprogram host cells for efficient viral replication. The nuclear import of E1A is mediated by a nuclear localization signal; however, whether E1A can be actively exported from the nucleus is unknown. We first reported a CRM1-dependent nuclear export signal (NES) in E1A that is conserved in the group C adenoviruses. We showed that CRM1 and E1A coimmunoprecipitated and that blockage of CRM1 function by leptomycin B or small interfering RNA resulted in the nuclear localization of E1A. Through mutational analyses, we identified an active canonical NES element within the E1A protein spanning amino acids 70-80. We further demonstrated that phosphorylation of adjacent serine (S)89 resulted in the cytoplasmic accumulation of E1A. Interestingly, coincident with the accumulation of cells in the S/G2/M phase and histone H1 phosphorylation, E1A was relocated to the cytoplasm at the late stage of the viral cycle, which was blocked by the CDC2/CDK2 inhibitor roscovitine. Importantly, titration of the progenies of the viruses in infected cells showed that the replication efficiency of the NES mutant adenovirus was up to 500-fold lower than that of the wild-type adenovirus. Collectively, our data demonstrate the existence of a NES in E1A that is modulated by the phosphorylation of the S89 residue and the NES plays a role for an efficient viral replication in the host cells.

Downmodulation of E1A protein expression as a novel strategy to design cancer-selective adenoviruses.

Oncolytic adenoviruses are being tested as potential therapies for human malignant tumors, including gliomas. Here we report for the first time that a mutation in the E1A gene results in low levels of E1A protein, conditioning the replication of mutant adenoviruses specifically to cancer cells. In this study, we compared the oncolytic potencies of three mutant adenoviruses encompassing deletions within the CR1 (Delta-39), CR2 (Delta-24) regions, or both regions (Delta-24/39) of the E1A protein. Delta-39 and Delta-24 induced a cytopathic effect with similar efficiency in glioma cells and a comparable capacity for replication. Importantly, the activity of Delta-39 was significantly attenuated compared to Delta-24 in proliferating normal human astrocytes. Direct analyses of the activation of E2F-1 promoter demonstrated the inability of Delta-39 to induce S-phase-related transcriptional activity in normal cells. Interestingly, E1A protein levels in cells infected with Delta-39 were remarkably downmodulated. Furthermore, protein stability studies revealed enhanced degradation of CR1 mutant E1A proteins, and inhibition of the proteasome activity resulted in the striking rescue of E1A levels. We conclude that the level of E1A protein is a critical determinant of oncolytic phenotype and we propose a completely novel strategy for the design and construction of conditionally replicative adenoviruses.

Mammary tumor modifiers in BALB/cJ mice heterozygous for p53.

BALB/c mice are predisposed to developing spontaneous mammary tumors, which are further increased in a p53 heterozygous state. C57BL/6J mice are resistant to induced mammary tumors and develop less than 1% mammary tumors in both wild-type and p53+/- states. To map modifiers of mammary tumorigenesis, we have established F1 and F2 crosses and backcrosses to BALB/cJ (N2-BALB/cJ) and C57BL/6J (N2-C57BL/6J) strains. All cohorts developed mammary carcinomas in p53+/- females, suggesting that multiple loci dominantly and recessively contributed to mammary tumorigenesis. We mapped two modifiers of mammary tumorigenesis in the BALB/cJ strain. Mtsm1 (mammary tumor susceptibility modifier), a dominant-acting modifier, is located on chromosome 7. Mtsm1 is suggestive for linkage to mammary tumorigenesis (p = 0.001). We have analyzed the Mtsm1 region to locate candidate genes by comparing it to a rat modifier region, Mcs3, which shares syntenic conservation with Mtsm1. Expression data and SNPs were also taken into account. Five potential candidate genes within Mtsm1 are Aldh1a3, Chd2, Nipa2, Pcsk6, and Tubgcp5. The second modifier mapped is Mtsm2, a recessive-acting modifier. Mtsm2 is located on chromosome X and is significantly linked to mammary tumorigenesis (p = 1.03 x 10(-7)).