CCN3 expression is reduced in human BCR-ABL⁺ cell lines and can be reversed in K562 cells treated with imatinib or siRNA to BCR-ABL. (A) RNA was extracted from human CML cell lines (K562, KU812, LAMA), BCR-ABL^- cells (HL60), and NBM, and subjected to real-time PCR to identify the level of BCR-ABL () and CCN3 (□) expression. Level of gene expression is shown as Ct values (n = 3). (B) K562 cells were treated with imatinib (1 μM) for 96 hours, and gene expression was analyzed by real-time PCR. Fold changes in BCR-ABL () and CCN3 (□) expression as a result of imatinib treatment are shown (n = 3; P = .001). (C) K562 cells were treated with siRNA directed to BCR-ABL (0.5 μg/10⁶ cells) for 24 hours. Real-time PCR was used to identify changes in BCR-ABL () and CCN3 (□) transcripts, which are shown as fold change in expression (n = 3; P = .001). (D) Levels of BCR-ABL () and CCN3 (□) transcripts were compared using real-time PCR in human CML cells that are sensitive (LAMA84-s) and resistant (LAMA84-r) to imatinib. Alterations in BCR-ABL and CCN3 expression as a result of imatinib resistance are shown as fold changes (n = 3; P = .001).