A lipoplexed formulation consisting of short-interfering RNAs (siRNAs) directed against protein kinase N3 (PKN3) encapsulated in catiogenic and fusiogenic lipids with potential antineoplastic activity. Upon administration, catiogenic and fusiogenic lipids promote anti-PKN3 siRNA Atu02 uptake by tumor cells; the siRNAs moieties are subsequently released once inside the cell. The siRNAs bind to PKN3 mRNAs, which may result in the inhibition of translation and expression of the PKN3 protein and, so, growth inhibition of tumor cells that overexpress PKN3. The protein kinase C-related molecule PKN3, downstream in the phosphoinositide-3-kinase (PI3K) signaling pathway, is upregulated in many tumor cells and plays an important role in invasive cell growth and metastasis.