Mechanisms of resistance to a PI3K inhibitor in gastrointestinal stromal tumors: an omic approach to identify novel druggable targets

MicroRNA-based recombinant AAV vector assembly improves efficiency of suicide gene transfer in a murine model of lymphoma

Recent success in clinical trials with recombinant Adeno-associated virus (AAV)-based gene therapy has redirected efforts in optimizing AAV assembly and production, to improve its potency. We reasoned that inclusion of a small RNA during vector assembly, which specifically alters the phosphorylation status of the packaging cells may be beneficial. We thus employed microRNAs (miR-431, miR-636) identified by their ability to bind AAV genome and also dysregulate Mitogen-activated protein kinase (MAPK) signaling during vector production, by a global transcriptome study in producer cells. A modified vector assembly protocol incorporating a plasmid encoding these microRNAs was developed. AAV2 vectors packaged in the presence of microRNA demonstrated an improved gene transfer potency by 3.7-fold, in vitro. Furthermore, AAV6 serotype vectors encoding an inducible caspase 9 suicide gene, packaged in the presence of miR-636, showed a significant tumor regression (~2.2-fold, P < .01) in a syngeneic murine model of T-cell lymphoma. Taken together, we have demonstrated a simple but effective microRNA-based approach to improve the assembly and potency of suicide gene therapy with AAV vectors.

Casticin inhibits nasopharyngeal carcinoma growth by targeting phosphoinositide 3-kinase

Background

Casticin, an isoflavone compound extracted from the herb Fructus Viticis, has demonstrated anti-inflammatory and anticancer activities and properties. The aim of this study was to investigate the effects and mechanisms of casticin in nasopharyngeal carcinoma (NPC) cells and to determine its potential for targeted use as a medicine.

Methods

NPC cells were used to perform the experiments. The CCK‑8 assay and colony formation assays were used to assess cell viability. Flow cytometry was used to measure the cell cycle and apoptosis analysis (annexin V/PI assay). A three-dimensional (3D) tumour sphere culture system was used to characterize the effect of casticin on NPC stem cells. In silico molecular docking prediction and high-throughput KINOME scan assays were used to evaluate the binding of casticin to phosphoinositide 3-kinase (PI3K), including wild-type and most of mutants variants. We also used the SelectScreen assay to detect the IC50 of ATP activity in the active site of the target kinase. Western blotting was used to evaluate the changes in key proteins involved cell cycle, apoptosis, stemness, and PI3K/protein kinase B (AKT) signalling. The effect of casticin treatment in vivo was determined by using a xenograft mouse model.

Results

Our results indicate that casticin is a new and novel selective PI3K inhibitor that can significantly inhibit NPC proliferation and that it induces G2/GM arrest and apoptosis by upregulating Bax/BCL2 expression. Moreover, casticin was observed to affect the self-renewal ability of the nasopharyngeal carcinoma cell lines, and a combination of casticin with BYL719 was observed to induce a decrease in the level of the phosphorylation of mTORC1 downstream targets in BYL719-insensitive NPC cell lines.

Conclusion

Casticin is a newly emerging selective PI3K inhibitor with potential for use as a targeted therapeutic treatment for nasopharyngeal carcinoma. Accordingly, casticin might represent a novel and effective agent against NPC and likely has high potential for combined use with pharmacological agents targeting PI3K/AKT.