Validation of CIP2A as a Biomarker of Subsequent Disease Progression and Treatment Failure in Chronic Myeloid Leukaemia.

Background: It would be clinically useful to prospectively identify the risk of disease progression in chronic myeloid leukaemia (CML). Overexpression of cancerous inhibitor of protein phosphatase 2A (PP2A) (CIP2A) protein is an adverse prognostic indicator in many cancers.

Methods: We examined CIP2A protein levels in diagnostic samples from the SPIRIT2 trial in 172 unselected patients, of whom 90 received imatinib and 82 dasatinib as first-line treatment.

CIP2A- and SETBP1-mediated PP2A inhibition reveals AKT S473 phosphorylation to be a new biomarker in AML.

PP2A inhibition occurs in AML by 2 different pathways: CIP2A in normal karyotype patients and SETBP1 in adverse karyotype patients. AKT phosphorylation is a predictor of survival, and diagnostic levels of AKT could be a novel biomarker in AML.

Evidence that the pregnane X and retinoid receptors PXR, RAR and RXR may regulate transcription of the transporter hOCT1 in chronic myeloid leukaemia cells.

The expression and activity of the uptake transporter human organic cation transporter 1 (hOCT1; SLC22A1) is an independent predictor of response to imatinib treatment in patients with chronic myeloid leukaemia (CML). We have recently shown that peroxisome proliferator-activated receptor (PPAR) activation can increase the killing effect of imatinib in CML cells, due to upregulated hOCT1 gene expression and increased imatinib uptake. To investigate the role of activation of nuclear receptors other than PPAR in the transcriptional regulation of hOCT1, CML cells were treated with agonists for 13 adopted orphan receptors and endocrine receptors.