Targeting TdT gene expression in Molt-4 cells by PNA-octaarginine conjugates.

Peptide nucleic acid (PNA) is an amide based structural nucleic acid mimic with potential applications in gene therapeutic drug discovery. In the present study, we evaluated and compared the effects on gene expression, cell viability and apoptosis of two antisense PNA-d-octaarginine conjugates, targeting sequences at the AUG translation start site or the 5'-UTR of the TdT (terminal deoxynucleotidyl transferase) gene, as well as a sense oligomer corresponding to the 5'-UTR-antisense, in Molt-4 cells. The protein level of TdT was determined by flow cytometry, and qPCR was used for mRNA expression analysis. Mismatch PNAs were used as control to address the sequence/target spcifity of the biological effects. The results showed that treatment with the AUG- and to slightly lesser extent with the 5'-UTR-antisense PNAs reduced the TdT mRNA as wel as the protein level, whereas only very low effect was observed for the 5'-UTR-sense PNA. A parallel effect was observed on reduced cell survival and increased rate of apoptosis. Our findings suggest that antisense PNAs can inhibit expression of the TdT gene and induce apoptosis in Molt-4 cells.