Figure 1.

O6-Methylguanine-DNA methyltransferase (MGMT) inhibiting lentiviral vectors. The pLKO.1 vectors contain all necessary cis-elements for packaging, reverse transcription and integration, which are required to genetically modify infected cells. Elements required for the production of the capsid and envelope proteins are deleted making the produced viral particles replication-incompetent. (a) Two small hairpin RNA (shRNA) sequence targeting the MGMT mRNA and one control sequence were cloned into the pLKO.1 lentiviral backbone after the human U6 promoter allowing expression of shRNAs in target cells. (b) For intratumoral applications, the luciferase reporter gene under the control of a cytomegalovirus (CMV) promoter was introduced subsequently (pLKO.1-CMVLuc-shRNA). cPPT, central polypurine tract; hPGK, human phosphoglycerate kinase promoter; RSV, rous sarcoma virus promoter; RRE, rev responsive element; Psi, lentiviral packaging signal.