CD5+CD23+ leukemic cell populations in TCL1 transgenic mice show significantly increased proliferation and Akt phosphorylation

B-cell chronic lymphocytic leukemia (B-CLL) is the most common adult leukemia. Deregulation of the T-cell leukemia/lymphoma 1 ( TCL1 ) oncogene in mouse B cells causes a CD5-positive leukemia similar to aggressive human B-CLLs. We recently reported that levels of TCL1 expression in B-CLL are regulated by miR-29 and miR-181 that target 3′ UTR of TCL1 . To determine whether treatment with microRNAs targeting TCL1 can inhibit B-CLL in mice, we generated TCL1 transgenic mice using a construct containing the 3′ and 5′ UTRs of TCL1 under B-cell-specific Eμ promoter (Eμ- TCL1 FL). At the age of 16–20 months, these mice showed B-CLL-like disease. Immunophenotyping revealed accumulation of CD5+CD23+B220+ population in spleens and lymph nodes. Our results show that CD5+CD23+ B-cell populations from Eμ- TCL1 FL mice actively proliferate and show significantly increased levels of phospho-Akt. Eμ- TCL1 FL mice showed immunological abnormalities similar to human B-CLL, including hypoimmunoglobulinemia, abnormal levels of cytokines and impaired immune response. These findings revealed biochemical and immunological similarities between Tcl1-driven B-CLL in mice and human B-CLL.