In this paper, we describe an effective method by which shCOX-2-expressing vectors can be delivered into CRC cells (in vitro) and in COX-2-overexpressing colonic tissues (ex vivo), using invasive E. coli strains to achieve a strong COX-2 silencing mediated by RNAi, coupled to anti-tumour effects. The gene discussed is PTGS2; the disease is colorectal carcinoma.