Histone deacetylase inhibitor inducible gene expression for drugs screening and suicide gene therapy

Objectives Histone deacetylase inhibitors (HDACi) such as trichostatin A (TSA) has been shown to inhibit cancer cell proliferation, induce apoptosis and regulate the expression of genes involved in cell cycle. The cell cycle regulated genes, p21 and Gadd45, could be up-regulated and induced by TSA. This study aimed to establish a TSA-inducible reporter gene system for HDACi drug screen and gene therapy.

Methods A p21-driven reporter composed of p21 promoter, luciferase (Fluc), DsRed monomer (DsRedm) and truncated HSV-1 thymidine kinase SR39 mutant (ttkSR39) gene, was constructed and transfected into the NSCLC cell line H1299 after DNA sequencing verification. Several putative stably p21-driven reporter expressed cells were obtained after G418 drug selection and the fluorescent microscopic examination. TSA was applied to these stable cell lines, and its effect was determined by luciferase assay and ³H-FEAU uptake. The stably p21-driven reporter expressed cell clones were inoculated in SCID mice, and optical imaging and microPET imaging with ¹²⁴I-FEAU were performed.

Results The p21-driven reporter expressed H1299 cells grew well in G418-containing culture medium. In vitro study of treatment with TSA showed remarkable increase in luciferase and TK activity. In vivo study confirmed the H1299-transfected p21-driven reporter tumor xenograft has obvious luciferase activity and ¹²⁴I-FEAU uptake.

Conclusions The p21-driven reporter stably expressed clones are TSA-inducible. These clones could be used for HDACi drugs screening and could be combined with GCV for suicide gene therapy.