PO-446 Anti-tumour efficiency of 20A, a novel G-quadruplex ligand, in in vitro and in vivocancer models: ATM and autophagy interplay

Abstract

a new angle in the MTR approach, by administering an oral prodrug of gemc, Oral Gem, to improve gemc's therapeutic properties, but also cover patients' quality of life. Material and methods The A549 lung cancer cell line was used to establish an in vitro model that simulated the MTD versus the MTR conditions. Cells were cultured either in presence of a high concentration of gemc or in medium in which lower concentrations were added daily in order to study alterations in the expression of various angiogenic factors. Additionally, an in vivo xenografted animal model was set up to study the effects of MTR chemotherapy on tumour's expansion, toxicity of the drug and angiogenesis. Results and discussions Daily addition of gemc in A549 cells led to a decreased expression of VEGFA, a well-established angiogenic factor, compared to the high dose incubation. In NOD/SCID xenografted mice, the MTR administration of Oral Gem led to a decreased expression of VEGFA and CD31, a marker found on endothelial cells, suggesting a suppressed angiogenic profile. Finally, MTR administration of Oral Gem led to an increase in the expression levels of Thrombospondin-1, an anti-angiogenic factor, compared to MTD chemotherapy. Conclusion MTR administration of Oral Gem limits the formed vessels around the tumour combining restriction of angiogenesis and vessel normalisation. In contrast, MTD chemotherapy seems to enhance the angiogenic potential around the tumour site, serving tumour's establishment and expansion. Introduction Recent studies indicate that E7107, a spliceosome inhibitor, causes altered splicing of key genes in CLL. We evaluated the effect of E7107 on cell viability and key proteins in the p53 pathway. Material and methods Eight leukaemia/lymphoma cell lines and eight primary CLL samples (6 wild-type and 2 mutant for SF3B1) were exposed to E7107 (H3 Biomedicine) for 72 and 48 hours. Cell viability was assessed by XTT assay. To understand the effect of splicing modulation on key proteins in the p53 pathway, including p21 and MDM2, five B-cell lines were treated with E7107 for 24 hours. Results and discussions E7107 decreased cell viability at low nanomolar concentrations in all CLL samples (mean LC 50 =10.5±2.0 nM; but >300 nM in two healthy PBMC controls). No correlation between drug sensitivity and SF3B1 status was observed in CLL samples (p=0.5). Six out of eight cell lines were sensitive to E7107 (mean GI 50 =6±1.8 nM). The GI 50 values were 60.2 and 203.5 nM for the resistant HEL and HAL-01 cells, respectively. The most frequently mutated regions of the SF3B1 gene, exons 14, 15 and 16, had no mutations detected by Sanger sequencing. There was no correlation between drug sensitivity and TP53 status. PO-445Western immunoblot revealed a marked decrease of MDM2 protein level in all cell lines, accompanied by a reciprocal concentration-dependent increase in p53. The normal molecular weight p21 disappeared at higher doses of E7107, with concomitant appearance of a high molecular weight p21 isoform (~30 kDa) in TP53 wild-type ce...