Bax mRNA therapy using cationic liposomes for human malignant melanoma.

Background: Bax is a pro-apoptotic molecule that functions as a tumor suppressor and Bax gene therapy has been examined for various cancers. Gene transfer by mRNA lipofection is more efficient than plasmid DNA lipofection and, in the present study, we examined the anti-tumor effects in human malignant melanoma cells (HMGs) using Bax mRNA lipofection.

Methods: Bax protein expression, cell growth inhibition, caspase-3 activity and apoptosis were examined in vitro. Liposome-Bax mRNA was applied locally once every 5 days for a total of five times to peripheral HMG tumors transplanted in nude mice. Tumor growth inhibition was evaluated by measuring the tumor volume and apoptosis was detected using a terminal deoxynucleotidyl transferase-mediated dUTP nick end labelling (TUNEL) assay.

Results: Enhanced expression of Bax protein was observed following Bax mRNA transfer and cell survival was 59.8%. Caspase-3 activity and TUNEL-positive cells increased significantly following Bax mRNA lipofection compared to Bax plasmid transfer. In mice, tumor growth increased only slightly during liposome-Bax mRNA administration and the tumor volume on day 30 (10 days after completion of administration) was 36.7% of that in the saline control group. By contrast, Bax plasmid transfection resulted in little change in tumor growth compared to controls.

Conclusions: Bax mRNA therapy using liposomes has stronger anti-tumor effects than Bax gene therapy using a plasmid, and the results suggest that Bax mRNA lipofection may be a viable treatment for malignant melanoma.