Objective: Bax is a pro-apoptotic molecule that functions as a tumor suppressor, and Bax gene therapy is investigated for various tumor cells. Gene transfer by mRNA lipofection is more efficient than plasmid DNA lipofection. We examined the antitumor effect of Bax mRNA gene therapy for a human squamous cell carcinoma using systemic administration of a cationic liposome.

Material and method: Bax mRNA was produced from a Bax plasmid by in vitro synthesis. In vitro , transfection efficiency was evaluated using a GFP assay, the level of Bax protein expression was determined by Western blotting, and apoptosis was detected with a TUNEL assay in KB cells, a human head and neck squamous cell carcinoma cell line. In vivo , liposome-Bax mRNA was administered via the tail vein in nude mice. Tumor growth inhibition was evaluated by measuring the tumor volume.

Results: In Bax mRNA treated group, the cell transfection efficiency was 77.0%, expression of Bax protein was elevated, and TUNEL-positive cells significantly increased, with an apoptosis index of 38.0%. The mean tumor volume in mice that received liposome-Bax mRNA was 35.9% of that in the saline control group on day 20, and tumor growth was inhibited compared to liposome-Bax plasmid treatment.

Conclusion: Bax mRNA therapy has a stronger antitumor effect than Bax gene therapy using a plasmid. Systemic administration was effective compared to the local injection that we examined in the past. These results suggest that Bax mRNA lipofection may be a viable treatment for human squamous cell carcinoma.

Conflict of interest: None declared.