Erosion Of The Chronic Myeloid Leukemia Stem Cell Pool By PPARγ Agonists

Blood ◽  
2013 ◽  
Vol 122 (21) ◽  
pp. 5197-5197
Author(s):  
Stephane Prost ◽  
Francis Relouzat ◽  
Marc Spenchian ◽  
Gérald Massonnet ◽  
Jean-Paul Beressi ◽  
...  

Abstract Whether cancer is maintained by a small number of stem cells or is composed of proliferating cells with approximate phenotypic equivalency is a central question in cancer biology. In the stem cell hypothesis, relapse after treatment may occur by failure to eradicate cancer stem cells. The chronic myeloid leukemia (CML) is quintessential to this hypothesis. CML is a myeloproliferative disorder that results from dysregulated tyrosine kinase activity of the fusion oncoprotein BCR-ABL. During the chronic phase, this sole genetic abnormality (chromosomal translocation Ph1+: t(9;22)(q34;q11)) at the stem cell level causes increased proliferation of myeloid cells without loss of their capacity to differentiate. Without treatment, most patients progress to the blast phase when additional oncogenic mutations result in a fatal acute leukemia made of proliferating immature cells. Imatinib mesylate and other tyrosine kinase inhibitors (TKIs) that target the kinase activity of BCR-ABL have improved patient survival dramatically. However, fewer than 10% of patients reach the stage of complete molecular response (CMR), defined when BCR-ABL transcripts become undetectable in blood cells3. Failure to reach CMR results from the inability of TKIs to eradicate quiescent CML leukemia stem cells (LCSs). Here we show that the residual CML LSC pool can be gradually purged by the glitazones, antidiabetic drugs that are agonists of peroxisome proliferator-activated receptor gamma (PPARg). We found that activation of PPARg by the glitazones decreases expression of STAT5 and its downstream targets HIF2α and CITED2, which are key guardians of CML LSC's quiescence and stemness. When pioglitazone was temporarily given to three CML patients in chronic residual disease in spite of continuous treatment with imatinib, all of them achieved sustained CMR, up to 4.7 years after withdrawal of pioglitazone. This suggests that clinically relevant cancer eradication may become a generally attainable goal by combination therapy that erodes the cancer stem cell pool. Disclosures: No relevant conflicts of interest to declare.

2020 ◽  
Vol 52 (10) ◽  
pp. 1663-1672
Author(s):  
Chun Shik Park ◽  
H. Daniel Lacorazza

Abstract Chronic myeloid leukemia is a hematological cancer driven by the oncoprotein BCR-ABL1, and lifelong treatment with tyrosine kinase inhibitors extends patient survival to nearly the life expectancy of the general population. Despite advances in the development of more potent tyrosine kinase inhibitors to induce a durable deep molecular response, more than half of patients relapse upon treatment discontinuation. This clinical finding supports the paradigm that leukemia stem cells feed the neoplasm, resist tyrosine kinase inhibition, and reactivate upon drug withdrawal depending on the fitness of the patient’s immune surveillance. This concept lends support to the idea that treatment-free remission is not achieved solely with tyrosine kinase inhibitors and that new molecular targets independent of BCR-ABL1 signaling are needed in order to develop adjuvant therapy to more efficiently eradicate the leukemia stem cell population responsible for chemoresistance and relapse. Future efforts must focus on the identification of new targets to support the discovery of potent and safe small molecules able to specifically eradicate the leukemic stem cell population. In this review, we briefly discuss molecular maintenance in leukemia stem cells in chronic myeloid leukemia and provide a more in-depth discussion of the dual-specificity kinase DYRK2, which has been identified as a novel actionable checkpoint in a critical leukemic network. DYRK2 controls the activation of p53 and proteasomal degradation of c-MYC, leading to impaired survival and self-renewal of leukemia stem cells; thus, pharmacological activation of DYRK2 as an adjuvant to standard therapy has the potential to induce treatment-free remission.


Leukemia ◽  
2020 ◽  
Vol 34 (6) ◽  
pp. 1613-1625 ◽  
Author(s):  
Ross Kinstrie ◽  
Gillian A. Horne ◽  
Heather Morrison ◽  
David Irvine ◽  
Chinmay Munje ◽  
...  

AbstractThe introduction of BCR-ABL tyrosine kinase inhibitors has revolutionized the treatment of chronic myeloid leukemia (CML). A major clinical aim remains the identification and elimination of low-level disease persistence, termed “minimal residual disease”. The phenomenon of disease persistence suggests that despite targeted therapeutic approaches, BCR-ABL-independent mechanisms exist which sustain the survival of leukemic stem cells (LSCs). Although other markers of a primitive CML LSC population have been identified in the preclinical setting, only CD26 appears to offer clinical utility. Here we demonstrate consistent and selective expression of CD93 on a lin−CD34+CD38−CD90+ CML LSC population and show in vitro and in vivo data to suggest increased stem cell characteristics, as well as robust engraftment in patient-derived xenograft models in comparison with a CD93− CML stem/progenitor cell population, which fails to engraft. Through bulk and single-cell analyses of selected stem cell and cell survival-specific genes, we confirmed the quiescent character and demonstrate their persistence in a population of CML patient samples who demonstrate molecular relapse on TKI withdrawal. Taken together, our results identify that CD93 is consistently and selectively expressed on a lin−CD34+CD38−CD90+ CML LSC population with stem cell characteristics and may be an important indicator in determining poor TKI responders.


1999 ◽  
Vol 189 (9) ◽  
pp. 1399-1412 ◽  
Author(s):  
Shaoguang Li ◽  
Robert L. Ilaria ◽  
Ryan P. Million ◽  
George Q. Daley ◽  
Richard A. Van Etten

The product of the Philadelphia chromosome (Ph) translocation, the BCR/ABL oncogene, exists in three principal forms (P190, P210, and P230 BCR/ABL) that are found in distinct forms of Ph-positive leukemia, suggesting the three proteins have different leukemogenic activity. We have directly compared the tyrosine kinase activity, in vitro transformation properties, and in vivo leukemogenic activity of the P190, P210, and P230 forms of BCR/ABL. P230 exhibited lower intrinsic tyrosine kinase activity than P210 and P190. Although all three oncogenes transformed both myeloid (32D cl3) and lymphoid (Ba/F3) interleukin (IL)-3–dependent cell lines to become independent of IL-3 for survival and growth, their ability to stimulate proliferation of Ba/F3 lymphoid cells differed and correlated directly with tyrosine kinase activity. In a murine bone marrow transduction/transplantation model, the three forms of BCR/ABL were equally potent in the induction of a chronic myeloid leukemia (CML)–like myeloproliferative syndrome in recipient mice when 5-fluorouracil (5-FU)–treated donors were used. Analysis of proviral integration showed the CML-like disease to be polyclonal and to involve multiple myeloid and B lymphoid lineages, implicating a primitive multipotential target cell. Secondary transplantation revealed that only certain minor clones gave rise to day 12 spleen colonies and induced disease in secondary recipients, suggesting heterogeneity among the target cell population. In contrast, when marrow from non– 5-FU–treated donors was used, a mixture of CML-like disease, B lymphoid acute leukemia, and macrophage tumors was observed in recipients. P190 BCR/ABL induced lymphoid leukemia with shorter latency than P210 or P230. The lymphoid leukemias and macrophage tumors had provirus integration patterns that were oligo- or monoclonal and limited to the tumor cells, suggesting a lineage-restricted target cell with a requirement for additional events in addition to BCR/ABL transduction for full malignant transformation. These results do not support the hypothesis that P230 BCR/ABL induces a distinct and less aggressive form of CML in humans, and suggest that the rarity of P190 BCR/ABL in human CML may reflect infrequent BCR intron 1 breakpoints during the genesis of the Ph chromosome in stem cells, rather than intrinsic differences in myeloid leukemogenicity between P190 and P210.


Blood ◽  
1968 ◽  
Vol 32 (2) ◽  
pp. 271-277 ◽  
Author(s):  
HIDEAKI MIZOGUCHI ◽  
YASUSADA MIURA ◽  
FUMIMARO TAKAKU ◽  
KIKU NAKAO

Abstract It is shown that an in vitro system of assaying the size of an erythropoietin-responsive stem cell pool could be applied to the spleens of polycythemic mice after irradiation and bone marrow transplantation. With this method, the presence of erythropoietin-responsive cells in the spleen was first detected on the second day after transplantation. Therefore, it is considered probable that colony-forming cells and erythropoietin-responsive cells are at different stages of maturation or cell cycle. Furthermore, necessity of erythropoietin for further differentiation of transplanted stem cells into erythroblasts is also suggested.


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