• c-Myc inhibition decreases CIP2A and reduces BCR-ABL1 tyrosine kinase activity in chronic myeloid leukemia.

      Lucas, Claire; Harris, Robert; Giannoudis, Athina; Clark, Richard; University of Liverpool, Royal Liverpool University hospital (Ferrata Storti Foundation, 2015-05-01)
      NA
    • CIP2A- and SETBP1-mediated PP2A inhibition reveals AKT S473 phosphorylation to be a new biomarker in AML

      Hills, Robert; Burnett, Alan; Lucas, Claire; Scott, Laura; Carmell, Natasha; Holcroft, Alison; Clark, Richard; University of Liverpool, Royal Liverpool University hospital, University of Cardiff (American Society for Hematology, 2018-04-27)
      Key Points PP2A inhibition occurs in AML by 2 different pathways: CIP2A in normal karyotype patients and SETBP1 in adverse karyotype patients. AKTS473 phosphorylation is a predictor of survival, and diagnostic levels of AKTS473 could be a novel biomarker in AML.
    • Comment on "PP2A inhibition sensitizes cancer stem cells to ABL tyrosine kinase inhibitors in BCR-ABL human leukemia".

      Perrotti, Danilo; Agarwal, Anupriya; Lucas, Claire; Narla, Goutham; Neviani, Paolo; Odero, Maria D.; Ruvolo, Peter P.; Verrills, Nicole M. (American Association for the Advancement of Science, 2019-07-17)
      LB100 does not sensitize CML stem cells to tyrosine kinase inhibitor–induced apoptosis.
    • Comment on PP2A inhibition sensitizes cancer stem cells to ABL tyrosine kinase inhibitors in BCR-ABL human leukemia

      Perrotti, D; Agarwal, A; Lucas, Claire; Narla, g; Nevanini, p; Odero, m; Ruvolo, p; Verrills, n; University of Maryland; Imperial College London; Oregon Health and Science University; University of Chester; University of Michigan; University of Southern California; University of Navarra; MD Anderson Cancer Center; University of Newcastle (AAAS, 2019-07-17)
      LB100 does not sensitize CML stem cells to tyrosine kinase inhibitor–induced apoptosis.
    • High CIP2A levels correlate with an antiapoptotic phenotype that can be overcome by targeting BCL-XL in chronic myeloid leukemia. Leukemia

      Lucas, Claire; Milani, Mateus; Butterworth, Michael; Carmell, Natasha; Scott, Laura; Clark, Richard; Cohen, Gerald; Varadarajan, Shankar; University of Liverpool (Nature, 2016-02-29)
      Cancerous inhibitor of protein phosphatase 2A (CIP2A) is a predictive biomarker of disease progression in many malignancies, including imatinib-treated chronic myeloid leukemia (CML). Although high CIP2A levels correlate with disease progression in CML, the underlying molecular mechanisms remain elusive. In a screen of diagnostic chronic phase samples from patients with high and low CIP2A protein levels, high CIP2A levels correlate with an antiapoptotic phenotype, characterized by downregulation of proapoptotic BCL-2 family members, including BIM, PUMA and HRK, and upregulation of the antiapoptotic protein BCL-XL. These results suggest that the poor prognosis of patients with high CIP2A levels is due to an antiapoptotic phenotype. Disrupting this antiapoptotic phenotype by inhibition of BCL-XL via RNA interference or A-1331852, a novel, potent and BCL-XL-selective inhibitor, resulted in extensive apoptosis either alone or in combination with imatinib, dasatinib or nilotinib, both in cell lines and in primary CD34(+) cells from patients with high levels of CIP2A. These results demonstrate that BCL-XL is the major antiapoptotic survival protein and may be a novel therapeutic target in CML.
    • Low leukotriene B4 receptor 1 leads to ALOX5 downregulation at diagnosis of chronic myeloid leukemia

      Lucas, Claire; Harris, Robert; McDonald, Elizabeth; Giannoudis, Athina; Clark, Richard; University of Liverpool, Royal Liverpool University hospital, (Ferrata Storti Foundation, 2014-11-01)
      ALOX5 is implicated in chronic myeloid leukemia development in mouse leukemic stem cells, but its importance in human chronic myeloid leukemia is unknown. Functional ALOX5 was assessed using an LTB4 ELISA and ALOX5, and LTB4R1 mRNA expression was determined via a TaqMan gene expression assay. LTB4R1 and 5-LOX protein levels were assessed by cell surface flow cytometry analysis. At diagnosis ALOX5 was below normal in both blood and CD34(+) stem cells in all patients. On treatment initiation, ALOX5 levels increased in all patients except those who were destined to progress subsequently to blast crisis. LTB4 levels were increased despite low ALOX5 expression, suggesting that the arachidonic acid pathway is functioning normally up to the point of LTB4 production. However, the LTB4 receptor (BLT1) protein in newly diagnosed patients was significantly lower than after a period of treatment (P<0.0001). The low level of LTB4R1 at diagnosis explains the downregulation of ALOX5. In the absence of LTB4R1, the arachidonic acid pathway intermediates (5-HEPTE and LTA4) negatively regulate ALOX5. ALOX5 regulation is aberrant in chronic myeloid leukemia patients and may not be important for the development of the disease. Our data suggest caution when extrapolating mouse model data into human chronic myeloid leukemia.
    • Second generation tyrosine kinase inhibitors prevent disease progression in high-risk (high CIP2A) chronic myeloid leukaemia patients.

      Lucas, Claire; Harris, Robert; Holcroft, Alison; Scott, Laura; Carmell, Natasha; McDonald, Elizabeth; Polydoros, Fotis; Clark, Richard (Nature, 2015-03-13)
      High cancerous inhibitor of PP2A (CIP2A) protein levels at diagnosis of chronic myeloid leukaemia (CML) are predictive of disease progression in imatinib-treated patients. It is not known whether this is true in patients treated with second generation tyrosine kinase inhibitors (2G TKI) from diagnosis, and whether 2G TKIs modulate the CIP2A pathway. Here, we show that patients with high diagnostic CIP2A levels who receive a 2G TKI do not progress, unlike those treated with imatinib (P=<0.0001). 2G TKIs induce more potent suppression of CIP2A and c-Myc than imatinib. The transcription factor E2F1 is elevated in high CIP2A patients and following 1 month of in vivo treatment 2G TKIs suppress E2F1 and reduce CIP2A; these effects are not seen with imatinib. Silencing of CIP2A, c-Myc or E2F1 in K562 cells or CML CD34+ cells reactivates PP2A leading to BCR-ABL suppression. CIP2A increases proliferation and this is only reduced by 2G TKIs. Patients with high CIP2A levels should be offered 2G TKI treatment in preference to imatinib. 2G TKIs disrupt the CIP2A/c-Myc/E2F1 positive feedback loop, leading to lower disease progression risk. The data supports the view that CIP2A inhibits PP2Ac, stabilising E2F1, creating a CIP2A/c-Myc/E2F1 positive feedback loop, which imatinib cannot overcome.