Three phenotypically distinct processes-somatic hypermutation, gene conversion, and switch recombination-remodel the functionally rearranged immunoglobulin (Ig) loci in B cells. Somatic hypermutation and switch recombination have recently been shown to depend on the activation-induced deaminase (AID) gene product. Here, we show that the disruption of the AID gene in the chicken B cell line DT40 completely blocks Ig gene conversion and that this block can be complemented by reintroduction of the AID complementary DNA. This demonstrates that the AID master gene controls all B cell-specific modifications of vertebrate Ig genes.

BackgroundThe antiangiogenic agent cilengitide disrupts integrin binding to the extracellular matrix leading to apoptosis of activated endothelial cells. Integrins are also widely expressed in malignant glioma and integrin inhibitors may directly target tumor cells in this disease. Aim of the current study was to investigate effects of cilengitide on endothelial and glioma cells on molecular and cellular levels.ResultsCilengitide caused dose-dependent detachment of endothelial cells from cell culture dishes. Proliferation of endothelial cells was significantly inhibited while the proportion of apoptotic cells was increased. Incubation of integrin-expressing glioma cells with cilengitide caused rounding and detachment after 24 hours as observed with endothelial cells. Cilengitide inhibited proliferation and induced apoptosis in glioma cells with methylated MGMT promotor when given alone or in combination with temozolomide. In endothelial as well as glioma cells cilengitide inhibited phosphorylation of FAK, Src and Akt. Assembly of cytoskeleton and tight junctions was heavily disturbed in both cell types.ConclusionCilengitide inhibits integrin-dependent signaling, causes disassembly of cytoskeleton, cellular detachment and induction of apoptosis in endothelial and glioma cells thereby explaining the profound activity of integrin inhibitors in gliomas. The combination of cilengitide with temozolomide exerted additive effects in glioma cells as observed clinically.

Despite recent advances in the treatment of metastatic castration-resistant prostate cancer (CRPC), outcome of patients remains poor due to the development of drug resistance. Thus, new drugs are urgently needed. We investigated efficacy, toxicity and mechanism of action of marine triterpene glycoside frondoside A (FrA) using CRPC cell lines in vitro and in vivo. FrA revealed high efficacy in human prostate cancer cells, while non-malignant cells were less sensitive. Remarkably, proliferation and colony formation of cells resistant to enzalutamide and abiraterone (due to the androgen receptor splice variant AR-V7) were also significantly inhibited by FrA. The marine compound caused cell type specific cell cycle arrest and induction of caspase-dependent or -independent apoptosis. Up-regulation or induction of several pro-apoptotic proteins (Bax, Bad, PTEN), cleavage of PARP and caspase-3 and down-regulation of anti-apoptotic proteins (survivin and Bcl-2) were detected in treated cells. Global proteome analysis revealed regulation of proteins involved in formation of metastases, tumor cell invasion, and apoptosis, like keratin 81, CrkII, IL-1b and cathepsin B. Inhibition of pro-survival autophagy was observed following FrA exposure. In vivo, FrA inhibited tumor growth of PC-3 and DU145 cells with a notable reduction of lung metastasis, as well as circulating tumor cells in the peripheral blood. Increased lymphocyte counts of treated animals might indicate an immune