MOLECULAR EVALUATION OF ZNF224 MRNA EXPRESSION IN CML PATIENTS AS A NOVEL DETERMINANT OF TKI RESPONSIVENESS

The transcription factor Wilms’ tumor gene 1, WT1, is implicated both in normal developmental processes and in the generation of a variety of solid tumors and hematological malignancies. WT1 is highly expressed in leukemia cells and its overexpression is associated with a poor response to therapy. Recently the Krüppel-like zinc-finger protein, ZNF224 was identified as a novel WT1-interacting factor involved in WT1 transcriptional regulation. ZNF224 itself could be modulated by cytosine arabinoside (ara-C), a drug widely used in the treatment of myeloid leukemia and that ZNF224 overexpression increases susceptibility to apoptosis of Ph+ K562 cell lines. In our retrospective analysis we evaluated the relative expression of ZNF224 mRNA in 30 adult patients with BCR-ABL–positive chronic phase chronic myeloid leukaemia (CP-CML) as a determinant of imatinib sensitivity. Methods: Response to tyrosine kinase inhibitor (TKI) imatinib is assessed with standardized real quantitative polymerase chain reaction and/or cytogenetics at 3, 6, and 12 months. Response to the therapy was classified as optimal, warning, and failure, according to the recent ELN criteria. We compared the ZNF224 expression at diagnosis with molecular response over the first 12 month of imatinib therapy. Sample have been selected, for retrospective analysis, for them interim molecular results a 12 month, showing 15 patients in optimal response (OR), 10 patients in a warning response (WR) and 5 patients in failure response (FR). 5 healthy donors (HDs) were included to the study. All patients signed informed consent in accordance with the Declaration of Helsinki. RT-qPCR results were normalized by the expression of ABL mRNA (Normalized mRNA copy Number: NCN).Results:ZNF224 mRNA were significantly up-regulated in PB samples at diagnosis of patients with OR compared to patients with WR/FR, (1.13±0.76 vs 0.62±0.25 NCN,respectively; p=0.05). Interesting the ZNF224 mRNA expression in HDs was significantly higher (2.11±0.98 NCN vs OR patients, p=0.05 and WR/FR patients; p=0.0005). The treatment for 12 month with imatinib increase the ZNF224 expression in both CML categories (2.91±1.72 NCN in OR and1.77±1.52 NCN in WR/FR; p=0.05). Conclusions:We observed that the OR patients express a significantly higher number of copies of the ZNF224 transcript than WR/FR. Furthermore, in both groups of patients at diagnosis, ZNF224 protein levels are lower than those after therapy with TKI at 12 months