Use of the site-specific retargeting jump-in platform cell line to support biologic drug discovery

Biologics represent a fast-growing class of therapeutics in the pharmaceutical sector. Discovery of therapeutic antibodies and characterization of peptides can necessitate high expression of the target gene requiring the generation of clonal stably transfected cell lines. Traditional challenges of stable cell line transfection include gene silencing and cell-to-cell variability. Our inability to control these can present challenges in lead isolation. Recent progress in site-specific targeting of transgene to specific genomic loci has transformed the ability to generate stably transfected mammalian cell lines. In this article, we describe how the use of the Jump-In platform (Life Technologies, Carlsbad, CA) has been applied to drug discovery projects. It can easily and rapidly generate homogeneous high-expressing cell pools with a high degree of reproducibility. Their use in cell-based screening to identify specific binders, identify binding to relevant species variants, or detect functionally relevant therapeutic antibodies is central in driving drug discovery.

Abstract 1616: Survivin regulates endothelial cell proliferation, survival and angiogenesis

Background - Survivin is a member of the inhibitor of apoptosis protein (IAP) family, and is reported to be overexpressed in a number of human cancers with high unmet medical need including breast, non-small-cell lung (NSCLC), colorectal, gastric, glioblastoma, and pancreatic cancers. Multiple studies have described survivin as a key regulator of tumour cell proliferation, survival and drug resistance, which has led to the advancement of survivin inhibitors, including antisense and small molecule drugs, and cancer vaccines, into clinical testing. In the tumour micro-environment, survivin overexpression has also been reported in tumour blood vessels and conditional deletion of survivin in endothelial cells results in murine embryonic lethality secondary to haemorrhage and defective vascular development. We therefore hypothesised that inhibition of survivin function in endothelial cells could have anti-angiogenic or vascular disruptive effects.

Methods and Results - To better understand the role of survivin in primary endothelial cells we designed siRNAs capable of targeting multiple isoforms of human survivin. Using high content imaging assays we demonstrated that the siRNA were highly selective for survivin, inhibited the expression of multiple survivin splice variants, and had potent in vitro effects on endothelial cells. Survivin knockdown resulted in inhibition of cell cycle progression with the formation of enlarged, multi-nucleated cells, and in reduced endothelial cell survival. Survivin knockdown also impaired the formation of tube-like networks in vitro when co-cultured with human fibroblasts, but did not disrupt more established networks.

Conclusion These data show an important role for survivin in primary endothelial cells, and suggest that targeted inhibition of survivin may have anti-angiogenic effects, but may not disrupt more established blood vessels.

Citation Format: Cath Eberlein, Grace Opoku-Ansah, James Legg, Tim London, Frank Gebhardt, Gareth Davies, Natalie Tigue, Matthew McCourt, Julia White, Darren Cross, Ute Schaeper, Viia E. Valge-Archer. Survivin regulates endothelial cell proliferation, survival and angiogenesis. [abstract]. In: Proceedings of the 104th Annual Meeting of the American Association for Cancer Research; 2013 Apr 6-10; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2013;73(8 Suppl):Abstract nr 1616. doi:10.1158/1538-7445.AM2013-1616

Chromosome abnormalities in peripheral blood cells of hepatitis B virus chronic carriers

Cytogenetic analysis of metaphase chromosome spreads from peripheral blood cells of hepatitis B virus (HBV) chronic carriers and HBV-negative individuals of the same ethnic origin revealed a significantly higher incidence of chromosome breaks and other mitotic aberrations in the HBV chronic carriers. The highest incidence of chromosome breaks was found in chronic carriers who evidenced circulating HBV. Such an association between HBV and these genetic lesions assumes importance in light of the known correlation between HBV chronic carrier status and the high risk of hepatocellular carcinogenesis, where a mutagenic effect of HBV cannot be excluded.

The localization of Australia antigen by immunofluorescence

We have studied the localization of Australia antigen, a particulate substance associated with hepatitis, by means of the fluorescent antibody technique. Preparations were made from 61 liver biopsy specimens taken from patients with infectious hepatitis, serum hepatitis, and a variety of other diseases. When tested with fluorescein-conjugated rabbit anti-Au(1) antisera all 26 patients who had Au(1) in their serum had specific fluorescence in their liver cells. The fluorescence appeared in three forms: as discrete particles within the nucleus, diffuse fluorescence of the entire nucleus, and fluorescence of the nuclear rim. Occasionally there were also fluorescent particles in the cytoplasm. Other specimens were tested with the fluorescent antibody including a variety of human tissues, buffy coat smears, peripheral lymphocyte cultures, and cells obtained from bile and duodenal drainage. Among these specimens, fluorescence was found in the cytoplasm of a few cells in the bone marrow of two patients with hepatitis and Au(1) in their serum, and in the liver, spleen, mesentery, and testis of one patient with leukemia, chronic hepatitis, and Au(1) in his serum. We have shown that the presence of fluorescent particles in the liver cells is strongly associated with the presence of Au(1) in the serum and the diagnosis of viral hepatitis. We believe that this study adds support to the hypothesis that Australia antigen is an antigenic determinant of a virus capable of causing hepatitis.