Gene expression profiling of pre-HPCs derived from CML-iPSCs
Ontology highlight
ABSTRACT: Properties of cancer stem cells (CSC) involved in drug-resistance and relapse have significant effect on clinical outcome. Although tyrosine kinase inhibitors (TKIs) have dramatically improved survival of patients with chronic myelogenous leukemia (CML), TKIs have not fully cure CML due to TKI-resistant CML stem cells. Moreover, the relapse after discontinuation of TKIs has not been predicted in CML patients with best TKI-response. In our study, pre-hematoopoietic progenitor cells (pre-HPCs), a model of CML stem cells derived from CML-iPSCs identified a novel antigen of TKI-resistant CML cells. Even in the fraction reported as TKI-sensitive, the antigen+ cells showed TKI-resistance in CML patients. In addition, residual CML cells in patients with optimal TKI-response were concentrated in the antigen+ population.
Project description:Chronic myeloid leukaemia (CML) is a clonal haemopoietic stem cell (HSC) disorder associated with the BCR-ABL oncogene, which encodes a constitutively active tyrosine kinase. We have demonstrated the existence of CML HSC which are resistant to the tyrosine kinase inhibitors (TKI). We have hypothesised that CML stem cells are dependent on key survival pathways that are induced by TKI treatment. In order to elucidate these key survival pathways, we have investigated the transcriptional differences between CML stem/progenitor cells (CD34+38-) treated with TKIs (imatinib, dasatinib and nilotinib) at different time points (8 hours and 7 days, in the absence of growth factors) and by carrying out RNA profiling for the different populations. CD34+38- cells were isolated from chronic phase patient samples. >100ng of total RNA was amplified prior to analysis that was carried out with Affymetrix Human Gene 1.0 ST array.
Project description:An approximately 60% of chronic myeloid leukemia (CML) patients who achieved a deep molecular response for more than 2 years maintained a major molecular response after discontinuation of imatinib. These findings indicate the possibility that a portion of CML patients treated with Tyrosine kinase inhibitors (TKIs) could discontinue TKI therapy, although long-term prognosis and/or adverse events after TKIs cessation remain unclear. Recent reports showed that transient musculoskeletal pain occurs in approximately 30% of CML patients after stopping imatinib. To ascertain the factors underlying musculoskeletal events after TKI cessation, we investigated exosomal miRNA in five CML patients who did not experience musculoskeletal events and five patients with musculoskeletal pain after stopping TKIs.
Project description:Current treatment for CML involves tyrosine kinase inhibitors (TKIs), which turned it into a managable disease. In a transcriptional profile of TKI-resistant versus newly diagnosed CML patient samples, G0S2 was shown to be profoundly downregulated.
Project description:The development of different generations of BCR-ABL1 tyrosine kinases inhibitors (TKIs) has led the overall survival (OS) of the chronic myeloid leukemia (CML) patients to become almost similar to that of a control population without leukemia, but the TKI therapy can be successfully discontinued only in half of those who are achieving a deep molecular response, that eans in approximately 15-20% of the entire population. In addition, although few, there are CML patients who show resistance to TKI therapy, are prone to progress to more advanced phases of the disease and die of CML related causes. Therefore, implementing an alternative approach for targeting TKI resistant leukemic cells would be of the essence in trying to solve these problems. Dihydroorotate dehydrogenase (DHODH) is a druggable enzyme in the de novo pyrimidine biosynthesis pathway that is located in the inner membrane of mitochondria. Here, we found that CML CD34+ cells and CML cell lines are vulnerable to DHODH inhibition mediated by Meds433, a new and potent DHODH inhibitor recently developed by our group. Meds433 significantly activated the apoptotic pathway and suppressed cell growth of CML cells in vitro and in vivo in a xenograft mice model. Moreover, inhibition of DHODH led to the reduction of amino acids and induction of huge metabolic stress in CML CD34+. Altogether, our study shows that targeting pyrimidine synthesis is a promising approach for targeting CML stem/progenitor cells, helping more patients to achieve good molecular response and possibly successful treatment discontinuation.
Project description:Tyrosine kinase inhibitors (TKI) are highly effective in treatment of chronic myeloid leukemia (CML) but do not eliminate leukemia stem cells (LSC), which remain a potential source of relapse. TKI treatment effectively inhibits BCR-ABL kinase activity in CML LSC, suggesting that additional kinase-independent mechanisms contribute to LSC preservation. We investigated whether signals from the bone marrow (BM) microenvironment protect CML LSC from TKI treatment. Coculture with human BM mesenchymal stromal cells (MSC) significantly inhibited apoptosis and preserved CML stem/progenitor cells following TKI exposure, maintaining colony forming ability and engraftment potential in immunodeficient mice. We found that the N-Cadherin receptor plays an important role in MSC-mediated protection of CML progenitors from TKI. N-Cadherin-mediated adhesion to MSC was associated with increased cytoplasmic N-Cadherin-β-catenin complex formation, as well as enhanced β-catenin nuclear translocation and transcriptional activity. Increased exogenous Wnt-mediated β-catenin signaling played an important role in MSC-mediated protection of CML progenitors from TKI treatment. Our results reveal a close interplay between N-Cadherin and the Wnt-β-catenin pathway in protecting CML LSC during TKI treatment. Importantly, these results reveal novel mechanisms of resistance of CML LSC to TKI treatment, and suggest new targets for treatment designed to eradicate residual LSC in CML patients.
Project description:Tyrosine kinase inhibitors (TKIs) have revolutionized chronic myelogenous leukemia (CML) management. Disease eradication, however, is hampered by innate resistance of leukemia initiating cells (LICs) to TKI-induced killing, which also provides the basis for subsequent emergence of TKI-resistant mutants. We report that EZH2, the catalytic subunit of Polycomb Repressive Complex 2 (PRC2), is overexpressed in CML LICs, required for colony formation, and survival and cell cycle progression of CML cell lines. A critical role for Ezh2 is supported by genetic studies in a mouse CML model. Inactivation of Ezh2 in conventional conditional mice and through CRISPR/Cas9-mediated gene editing prevents initiation and maintenance of disease and survival of LICs, irrespective of BCR/ABL1 mutational status, and extends survival. Expression of the Ezh2 homolog Ezh1 is reduced in Ezh2-deficient CML LICs, creating a scenario resembling complete loss of PRC2. EZH2-dependence of CML LICs raises prospects for improved therapy of TKI-resistant CML and/or eradication of disease by addition of EZH2 inhibitors.
Project description:Tyrosine kinase inhibitors (TKIs) targeting the BCR-ABL1 fusion tyrosine kinase have revolutionized the treatment of chronic myeloid leukemia (CML). However, the development of TKI resistance and the subsequent transition from the chronic phase (CP) to blast crisis (BC) threaten CML patients. Accumulating evidence suggests that translational control is crucial for cancer development and progression. Here, we performed high throughput CRISPR/Cas9 screening and identified poly(A) binding protein cytoplasmic 1 (PABPC1) as a driver for CML-BC progression. PABPC1 preferentially improved the translation efficiency of multiple leukemogenic mRNAs with long and highly structured 5' untranslated regions, including BCR-ABL1 and its TKI-resistant mutants, through forming biomolecular condensates. Inhibiting PABPC1 significantly suppressed CML cell proliferation and attenuated disease progression, but did not affect normal hematopoiesis seriously. More importantly, we identified two novel PABPC1 inhibitors, 1,10-Phen and ML324, which inhibited BC progression and overcame TKI resistance in murine and human CML. Overall, our work identified PABPC1 as a selective translation enhancing factor in CML-BC, the genetic or pharmacological inhibition of which overcame TKI resistance and suppressed BC progression in CML.
Project description:Tyrosine kinase inhibitors (TKIs) targeting the BCR-ABL1 fusion tyrosine kinase have revolutionized the treatment of chronic myeloid leukemia (CML). However, the development of TKI resistance and the subsequent transition from the chronic phase (CP) to blast crisis (BC) threaten CML patients. Accumulating evidence suggests that translational control is crucial for cancer development and progression. Here, we performed high throughput CRISPR/Cas9 screening and identified poly(A) binding protein cytoplasmic 1 (PABPC1) as a driver for CML-BC progression. PABPC1 preferentially improved the translation efficiency of multiple leukemogenic mRNAs with long and highly structured 5' untranslated regions, including BCR-ABL1 and its TKI-resistant mutants, through forming biomolecular condensates. Inhibiting PABPC1 significantly suppressed CML cell proliferation and attenuated disease progression, but did not affect normal hematopoiesis seriously. More importantly, we identified two novel PABPC1 inhibitors, 1,10-Phen and ML324, which inhibited BC progression and overcame TKI resistance in murine and human CML. Overall, our work identified PABPC1 as a selective translation enhancing factor in CML-BC, the genetic or pharmacological inhibition of which overcame TKI resistance and suppressed BC progression in CML.
Project description:Tyrosine kinase inhibitors (TKIs) targeting the BCR-ABL1 fusion tyrosine kinase have revolutionized the treatment of chronic myeloid leukemia (CML). However, the development of TKI resistance and the subsequent transition from the chronic phase (CP) to blast crisis (BC) threaten CML patients. Accumulating evidence suggests that translational control is crucial for cancer development and progression. Here, we performed high throughput CRISPR/Cas9 screening and identified poly(A) binding protein cytoplasmic 1 (PABPC1) as a driver for CML-BC progression. PABPC1 preferentially improved the translation efficiency of multiple leukemogenic mRNAs with long and highly structured 5' untranslated regions, including BCR-ABL1 and its TKI-resistant mutants, through forming biomolecular condensates. Inhibiting PABPC1 significantly suppressed CML cell proliferation and attenuated disease progression, but did not affect normal hematopoiesis seriously. More importantly, we identified two novel PABPC1 inhibitors, 1,10-Phen and ML324, which inhibited BC progression and overcame TKI resistance in murine and human CML. Overall, our work identified PABPC1 as a selective translation enhancing factor in CML-BC, the genetic or pharmacological inhibition of which overcame TKI resistance and suppressed BC progression in CML.
Project description:Tyrosine kinase inhibitors (TKIs) targeting the BCR-ABL1 fusion tyrosine kinase have revolutionized the treatment of chronic myeloid leukemia (CML). However, the development of TKI resistance and the subsequent transition from the chronic phase (CP) to blast crisis (BC) threaten CML patients. Accumulating evidence suggests that translational control is crucial for cancer development and progression. Here, we performed high throughput CRISPR/Cas9 screening and identified poly(A) binding protein cytoplasmic 1 (PABPC1) as a driver for CML-BC progression. PABPC1 preferentially improved the translation efficiency of multiple leukemogenic mRNAs with long and highly structured 5' untranslated regions, including BCR-ABL1 and its TKI-resistant mutants, through forming biomolecular condensates. Inhibiting PABPC1 significantly suppressed CML cell proliferation and attenuated disease progression, but did not affect normal hematopoiesis seriously. More importantly, we identified two novel PABPC1 inhibitors, 1,10-Phen and ML324, which inhibited BC progression and overcame TKI resistance in murine and human CML. Overall, our work identified PABPC1 as a selective translation enhancing factor in CML-BC, the genetic or pharmacological inhibition of which overcame TKI resistance and suppressed BC progression in CML.