Glutamine depletion by crisantaspase hinders the growth of human hepatocellular carcinoma xenografts

Background: A subset of human hepatocellular carcinomas (HCC) exhibit mutations of β-catenin gene CTNNB1 and overexpress Glutamine synthetase (GS). The CTNNB1-mutated HCC cell line HepG2 is sensitive to glutamine starvation induced in vitro with the antileukemic drug Crisantaspase and the GS inhibitor methionine-L-sulfoximine (MSO). Methods: Immunodeficient mice with subcutaneous xenografts of the CTNNB1-mutated HCC cell lines HepG2 and HC-AFW1 were treated with Crisantaspase and/or MSO, and tumour growth was monitored. At the end of treatment, tumour weight and histology were assessed. Serum and tissue amino acids were determined by HPLC. Gene and protein expression were estimated with RT-PCR and western blot and GS activity with a colorimetric method. mTOR activity was evaluated from the phosphorylation of p70S6K1. Results: Crisantaspase and MSO depleted serum glutamine, lowered glutamine in liver and tumour tissue, and inhibited liver GS activity. HepG2 tumour growth was significantly reduced by either Crisantaspase or MSO, and completely suppressed by the combined treatment. The combined treatment was also effective against xenografts of the HC-AFW1 cell line, which is Crisantaspase resistant in vitro. Conclusions: The combination of Crisantaspase and MSO reduces glutamine supply to CTNNB1-mutated HCC xenografts and hinders their growth

A922 Sequential measurement of 1 hour creatinine clearance (1-CRCL) in critically ill patients at risk of acute kidney injury (AKI)

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The Specification and Global Reprogramming of Histone Epigenetic Marks during Gamete Formation and Early Embryo Development in C. elegans

In addition to the DNA contributed by sperm and oocytes, embryos receive parent-specific epigenetic information that can include histone variants, histone post-translational modifications (PTMs), and DNA methylation. However, a global view of how such marks are erased or retained during gamete formation and reprogrammed after fertilization is lacking. To focus on features conveyed by histones, we conducted a large-scale proteomic identification of histone variants and PTMs in sperm and mixed-stage embryo chromatin from C. elegans, a species that lacks conserved DNA methylation pathways. The fate of these histone marks was then tracked using immunostaining. Proteomic analysis found that sperm harbor ?2.4 fold lower levels of histone PTMs than embryos and revealed differences in classes of PTMs between sperm and embryos. Sperm chromatin repackaging involves the incorporation of the sperm-specific histone H2A variant HTAS-1, a widespread erasure of histone acetylation, and the retention of histone methylation at sites that mark the transcriptional history of chromatin domains during spermatogenesis. After fertilization, we show HTAS-1 and 6 histone PTM marks distinguish sperm and oocyte chromatin in the new embryo and characterize distinct paternal and maternal histone remodeling events during the oocyte-to-embryo transition. These include the exchange of histone H2A that is marked by ubiquitination, retention of HTAS-1, removal of the H2A variant HTZ-1, and differential reprogramming of histone PTMs. This work identifies novel and conserved features of paternal chromatin that are specified during spermatogenesis and processed in the embryo. Furthermore, our results show that different species, even those with diverged DNA packaging and imprinting strategies, use conserved histone modification and removal mechanisms to reprogram epigenetic information

HPV31 E7 facilitates replication by activating E2F2 transcription through its interaction with HDACs

The E7 proteins of human papillomaviruses (HPVs) contribute to oncogenesis by associating with Rb family members as well class I histone deacetylases (HDACs). The binding of HDACs is also important for the maintenance of viral episomes during the differentiation-dependent productive life cycle. The effects of E7 and other viral proteins on E2F family members were examined in differentiating keratinocytes. E7 was found to specifically activate E2F2 transcription in suprabasal keratinocytes through its ability to bind HDACs. Chromatin immunoprecipitation assays demonstrated that, in differentiating cells, E7 acts to inhibit HDAC binding to the E2F2 promoter resulting in activation of expression. Reduction of E2F2 levels through the use of siRNA confirmed that E2F2 expression facilitated HPV replication but its loss did not affect cell proliferation. Our study demonstrates a mechanism by which binding of HDACs to E7 directly modulates viral replication and identifies E2F2 as a possible target for antiviral therapies