Efficient expression of bioactive murine IL12 as a self-processing P2A polypeptide driven by inflammation-regulated promoters in tumor cell lines

Interleukin 12 (IL12) is a heterodimeric proinflammatory cytokine that has shown promise as an anticancer agent. However, despite encouraging results in animal models, clinical trials involving IL12 have been unsuccessful due to toxic side effects associated with its systemic administration, prompting investigation into new delivery methods to confine IL12 expression to the tumor environment. In this study we used the self-cleaving property of the 2A peptide to express both codon-optimized murine IL12 subunits (muIL12opt) as a self-processing polypeptide (muIL12opt-P2A). We cloned muIL12opt-P2A driven by different inflammation-induced lentiviral expression systems to transduce murine tumor cell lines commonly employed in syngeneic tumor models. We confirmed the inducibility of these systems in vitro and in vivo and demonstrated the successful expression of both IL12 subunits and the release of bioactive IL12 upon proinflammatory stimulation in vitro. Therefore, IL12 release driven by these inflammation-regulated expression systems might be useful not only to address the impact of IL12 expression in the tumor environment but also to achieve a local IL12 release controlled by the inflammation state of the tumor, thus avoiding toxic side effects associated with systemic administration.