Combined silencing of K-ras and Akt2 oncogenes achieves synergistic effects in inhibiting pancreatic cancer cell growth in vitro and in vivo

Cancer is a complex disease involving multiple oncogenes with diverse actions. Inhibiting only one oncogene is unlikely to eliminate the malignancy of cancer cells. The goal of this study was to investigate whether synergistic effects can be achieved by combined silencing of two oncogenes, K-ras and Akt2, which are key players in the Ras/MAPK and PI3K/Akt signaling pathways. The pancreatic cancer cell line, Panc-1, was selected for these studies as it has elevated expression of K-ras and Akt2. Compared with inhibiting each oncogene alone, simultaneously silencing the two oncogenes with RNA interference (RNAi) more effectively inhibited Panc-1 cell proliferation and colony formation, induced a significantly higher percentage of apoptosis and resulted in greater inhibition of c-myc expression in vitro. Furthermore, when delivered by polyethyleneimine into Panc-1 tumors in nude mice, RNAi simultaneously targeting K-ras and Akt2 inhibited tumor growth more efficiently than RNAi targeting the individual oncogenes. Therefore, RNAi simultaneously silencing the oncogenes K-ras and Akt2 may offer potential opportunities for pancreatic cancer gene therapy.