Chimeric Enzyme/Prodrug Therapy as Novel Gene Therapy for Breast Cancer

摘要

We have constructed a series of artificial chimeric genes each composed of atumor-associated CD44 alternative splicing unit (ASU) which includes alternatively spliced exons and flanking introns and exons and the cytosine deaminase (CD) gene. The selective expression of active CD44/CD chimeric protein potentially enables tumor-specific killing via the RNA metabolism of alternative splicing following administration of the prodrug 5-FC. Insertion of the CD44 transmembrane region between 5'CD44 encoding exons and 3'-CD cDNA anchors the chimeric protein to the cell membrane while partitioning CD44 to the extracellular and CD to the intracellular compartments, respectively and results in no significant loss of CD enzymatic function. This modification makes it possible to introduce specific therapeutic receptor or antigen sites located outside the membrane allowing for recognition of cancer cells surviving the toxicity of the 5-FU anabolite.