An intron promotes the anti-bcr-abl activities of a retrovirally expressed ribozyme in chronic myeloid leukemia cells.
Ribozymes have been developed to cleave the bcr-abl transcripts and thereby suppress transforming activities of chronic myelogenous leukemia (CML) cells. However, the intracellular efficacy of vector-dependent ribozymes usually depends in part on their expression cassettes, which may affect their intracellular trafficking and distribution. In order to test effects of an intron in pre-fusion ribozyme on the anti-bcr-abl activities in CML cells, retroviral vectors harboring ribozyme expression cassettes with (RzI) or without (Rz) an intron-encoding sequence were used to transduce K562 cells. In terms of both reduction of the target bcr-abl mRNA and suppression of colony formation in soft agar and xenograft growth on SCID mice, the anti-bcr-abl efficacy of the RzI fusion ribozyme was significantly superior to that of Rz. These results also correlate with more cytoplasmic accumulation of the RzI fusion ribozymes than that of the Rz. This study suggests activities of a RNA polymerase II-driven fusion ribozyme against its targeted spliced mRNA are improved by incorporating an intron in its pre-splicing transcript. Noticeably, the improvement is contributed in part by subcellular co-localization.
Liu
Jin-Hwang
JH
Division of Medical Oncology, Taipei Veterans General Hospital and National Yang-Ming University, Taipei, Taiwan, ROC. jhliu@vghtpe.gov.tw
Wu
Suh-Chin
SC
Chen
Wei-Shone
WS
Yen
Chueh-Chuan
CC
Yang
Muh-Hwa
MH
Tsai
Ying-Chieh
YC
Chen
Po-Min
PM
D000818:Animals; D001483:Base Sequence; D002452:Cell Count; D003593:Cytoplasm / Q000378:metabolism; D016044:Fusion Proteins, bcr-abl / Q000037:antagonists & inhibitors* / Q000096:biosynthesis / Q000235:genetics; D018628:Gene Dosage; D005822:Genetic Vectors / Q000235:genetics / Q000494:pharmacology; D006801:Humans; D007438:Introns / Q000235:genetics*; D020014:K562 Cells; D015464:Leukemia, Myelogenous, Chronic, BCR-ABL Positive / Q000201:enzymology / Q000235:genetics / Q000378:metabolism*; D051379:Mice; D016513:Mice, SCID; D008969:Molecular Sequence Data; D016337:RNA, Catalytic / Q000096:biosynthesis / Q000235:genetics* / Q000378:metabolism*; D012190:Retroviridae / Q000235:genetics; D013997:Time Factors; D014158:Transcription, Genetic; D014161:Transduction, Genetic
D016337:RNA, Catalytic; D016044:Fusion Proteins, bcr-abl