Infectious delivery of the 132 kb CDKN2A/CDKN2B genomic DNA region results in correctly spliced gene expression and growth suppression in glioma cells

The expression of genes from genomic loci can be relatively complex, utilizing exonic, intronic and flanking sequences to regulate tissue and developmental specificity. Infectious bacterial artificial chromosomes (iBACs) have been shown to deliver and express large genomic loci ( up to 135 kb) into primary cells for functional analyses. The delivery of large genomic DNA inserts allows the expression of complex loci and of multiple splice variants. Herein, we demonstrate for the first time that an iBAC will deliver and correctly express in human glioma cells the entire CDKN2A/CDKN2B genomic region, which encodes for at least three important cell-cycle regulatory proteins (p16(INK4a), p14(ARF) and p15(INK4b)). Two of these proteins are expressed from overlapping genes, utilizing alternative splicing and promoter usage. The delivered locus expresses each gene at physiological levels and cellular responses ( apoptosis versus growth arrest) occur dependent on cellular p53 status, as expected. The work further demonstrates the potential of the iBAC system for the delivery of genomic loci whose expression is mediated by complex splicing and promoter usage both for gene therapy applications and functional genomics studies.