Synthetic bacterial messenger RNA can be used to prepare autologous, allogenic or direct nucleic acid cancer vaccines. Cancer cells are transfected either in vitro or in vivo with mRNA obtained from DNA that encodes an immunogenic bacterial protein. An immune response to the cancer is generated from direct administration of the mRNA in vivo or administration of vaccines prepared from cancer cells in vitro. Codon modification of the mRNA can optimize expression of an immunogenic polypeptide in cancer cells.