Regulated expression of the diphtheria toxin A chain by a tumor-specific chimeric transcription factor results in selective toxicity for alveolar rhabdomyosarcoma cells.
Alveolar rhabdomyosarcoma (ARMS) cells often harbor one of two unique chromosomal translocations, either t(2;13)(q35;q14) or t(1;13)(p36;q14). The chimeric proteins expressed from these rearrangements, PAX3-FKHR and PAX7-FKHR, respectively, are potent transcriptional activators. In an effort to exploit these unique cancer-specific molecules to achieve ARMS-specific expression of therapeutic genes, we have studied the expression of a minimal promoter linked to six copies of a PAX3 DNA binding site, prs-9. In transient transfections, expression of the prs-9-regulated reporter genes was approximately 250-fold higher than expression of genes lacking the prs-9 sequences in cell lines derived from ARMS, but remained at or below baseline levels in other cells. High expression of these prs-9-regulated genes was also observed in a cancer cell line that lacks t(2;13) but was stably transfected with a plasmid expressing PAX3-FKHR. Transfection of a plasmid containing the diphtheria toxin A chain gene regulated by prs-9 sequences (pA3-6PED) was selectively cytotoxic for PAX3-FKHR-expressing cells. This was shown by inhibition of gene expression from cotransfected plasmids and by direct cytotoxicity after transfected cells were isolated by cell sorting. Gene transfer of pA3-6PED may thus be useful as a cancer-specific treatment strategy for t(2;13)- or t(1;13)-positive ARMS. Furthermore, gene transfer of fusion protein-regulated toxin genes might also be applied to the treatment of other cancers that harbor cancer-specific chromosomal translocations involving transcription factors.
Massuda
E S
ES
Division of Pediatric Hematology/Oncology, University of Wisconsin Children's Hospital and Comprehensive Cancer Center, Madison, WI 53792, USA.
Dunphy
E J
EJ
Redman
R A
RA
Schreiber
J J
JJ
Nauta
L E
LE
Barr
F G
FG
Maxwell
I H
IH
Cripe
T P
TP
D004268:DNA-Binding Proteins / Q000235:genetics; D004167:Diphtheria Toxin / Q000235:genetics* / Q000633:toxicity; D000071161:Forkhead Box Protein O1; D051858:Forkhead Transcription Factors; D015972:Gene Expression Regulation, Neoplastic; D018014:Gene Transfer Techniques; D015316:Genetic Therapy; D006367:HeLa Cells; D018398:Homeodomain Proteins; D006801:Humans; D009124:Muscle Proteins / Q000235:genetics; D009419:Nerve Tissue Proteins / Q000235:genetics; D051763:PAX7 Transcription Factor; D011993:Recombinant Fusion Proteins / Q000235:genetics*; D018232:Rhabdomyosarcoma, Alveolar / Q000235:genetics / Q000378:metabolism / Q000628:therapy; D014157:Transcription Factors / Q000235:genetics
D004268:DNA-Binding Proteins; D004167:Diphtheria Toxin; C085126:FOXO1 protein, human; D000071161:Forkhead Box Protein O1; D051858:Forkhead Transcription Factors; D018398:Homeodomain Proteins; D009124:Muscle Proteins; D009419:Nerve Tissue Proteins; D051763:PAX7 Transcription Factor; C497321:PAX7 protein, human; D011993:Recombinant Fusion Proteins; D014157:Transcription Factors