SCID MOUSE MODEL 3405 Characterization of A - NB 4 Cells and Organ Injiltration

Acute promyelocytic leukemia (APL) is an interesting model for cancer research because of the presence of the specific PML-RARa fusion gene associated with the clinical response t o retinoic acid differentiation therapy. To better understand and improve differentiation induction with retinoic acid, we have established a human APL-ascites model in SCID mice using the NB4 human APL cell line. NB4 (1 x 10’ cells) were transplanted into the peritoneum (IP) of SCID mice for 1 month. NB4 ascites cells (A-NB4) appeared, which were then engrafted in SClD mice periodically for 18 passages at an interval of 3 to 4 weeks with a 100% success rate of tumor induction. The mean survival times of SClD mice transplanted with 1 x lo8 A-NB4 cells was 21.6 5 2.3 days. Analysis of the biologic characteristics of ninth passage NB4 ascitic cells was performed and they were found to have the