Inhibition of human lung carcinoma cell growth by apoptosis induction using Semliki Forest virus recombinant particles

We have utilised cell cultures and growth of tumours in nude mice to assess further the potential of the Semliki Forest virus (SFV) vector as a cancer therapy agent This vector is a transient RNA-based expression vector, and we have previously shown that SFV and its derived Vector can induce p53-ind ependent apoptosis by expression of the nonstructural region of the virus g enome. Apoptosis induction is therefore an inherent property of the vector and is not dependent on heterologous gene expression. SFV recombinant suici de particles (rSFV) were shown to induce apoptosis in H358a cells, which ar e human non-small cell lung carcinoma cells deleted in p53. EGFP-expressing rSFV also inhibited the growth of developing H358a spheroids. Direct injec tion of rSFV into H358a tumours subcutaneously implanted as xenografts in n u/nu mice inhibited tumour growth, and in some cases caused complete regres sion. It is concluded that tumour growth suppression induced by rSFV was du e to apoptosis induction and that the vector has an inherent cell death-pro moting and antitumour activity. These results, as well as previous work by other authors on targeting and immune stimulation using alphavirus vectors, indicate that SFV recombinant particles in particular have considerable po tential for further exploitation as a cancer therapy agent.