Growth Of Chronic Myeloid Leukemia Research Articles

INNO-406 inhibits the growth of chronic myeloid leukemia and promotes its apoptosis via targeting PTEN.

Chronic myeloid leukemia (CML) is a myeloproliferative neoplasm. INNO-406 is a novel tyrosine kinase inhibitor (TKI) that possess specific Lyn kinase inhibitory activity with no or limited activity against other sarcoma (Src) family member kinases. The present study aimed to confirm the anti-tumor effect of INNO-406 on CML cells, and elucidate the underlying molecular mechanism. CML cells were treated by INNO-406 at the concentration of 5, 25, 50, 100μM at the indicated time. Cell proliferation was measured by MTT. Cell apoptosis were detected by Western blot and flow cytometry, respectively. As suggested by the findings, INNO-406 significantly inhibited the proliferation and induced apoptosis of CML cells. In addition, INNO-406 promoted the expression level of PTEN. Rescue experiment revealed that PTEN knockdown reversed the effect of INNO-406 which indicated the correlation between INNO-406 and PTEN. Further study determined that PTEN inhibited the phosphorylation of AKT and 4EBP1 and subsequently altered the expression of apoptotic proteins including bax, cytoplasmic cytochrome c (cyto-c), cleaved caspase3 and bcl-2. In vivo study further confirmed that INNO-406 inhibited the growth of CML cells by targeting PTEN. Based on the above findings, this work extended our understanding of INNO-406 in the therapy of CML and its molecular mechanism.

Down-regulating NQO1 promotes cellular proliferation in K562 cells via elevating DNA synthesis

BackgroundNQO1 protein acts as a cellular protective system, on account of its role as a quinone reductase and redox regulator. Nonetheless, new NQO1 roles are emerging—including its regulation of the cellular proliferation of many tumor cells—and this enzyme has been found to relate to the incidence of various diseases, including chronic myeloid leukemia. However, the mechanisms through which NQO1 influences leukemia progression remain unclear. Martial and methodsThe current study looks to name NQO1 as a novel molecular target that modulates DNA synthesis and chronic myeloid leukemia growth. Results and conclusionOur results indicate that the frequency of the T allele of NQO1 polymorphism in chronic myeloid leukemia patients is higher than that among healthy East Asian individuals (0.492 vs. 0.419) and much higher than the average level of the general population (0.492 vs. 0.289) (1000 Genomes). Functionally, NQO1 knockdown increases the protein expression of the TOP2A and MCM complex, and consequently promotes DNA synthesis and K562 cell growth. NQO1 knockdown also promotes tumorigenesis in a xenograft model. NQO1 overexpression, on the other hand, was found to have the opposite effects. SignificanceOur results show that NQO1 downregulation promotes K562 cellular proliferation via the elevation of DNA synthesis.

Abstract 2633: Vitamin D3 analog inecalcitol synergizes with tyrosine kinase inhibitors (TKI) and selectively inhibit the growth of chronic myeloid leukemia (CML) progenitors: Development of a clinically applicable leukemic stem cell targeting strategy

Abstract Tyrosine kinase inhibitor (TKI) therapies have profoundly changed the natural history of chronic myeloid leukemia (CML) and prolonged survival. However, in vitro and in vivo data suggest strongly that the eradication of the most primitive CML stem cells will not be possible by the use of TKI therapies alone. The mechanisms of this inefficiency might involve cell autonomous (activation of alternate signaling, reduced BCR-ABL expression) or non-cell autonomous (niche-related) pathways. It would therefore be of major interest to determine if compounds targeting CML progenitors and stem cells can be used in combination with TKI. Few targeted therapies have been so far shown to be clinicaly acceptable. We have used for this purpose Inecalcitol (19, nor 14 epi 23-yne-1,25 (OH)2D3) (ICC),a vitamin D3 analog, which has been shown to exert antiproliferative effects in several types of cancer cell lines. CD34+ cells isolated from CML patients at diagnosis (n = 15) were tested in clonogenic assays (500 CD34+ cells / dish in triplicate). Interestingly, ICC alone is highly efficient to inhibit the clonogenic growth in the majority of the CML patients at diagnosis (10/ 15 patients). The combination of ICC with either Imatinib Mesylate (IM), Dasatinib (DA) or Nilotinib (NIL) in clonogenic assays showed a synergistic effect for the inhibition of CFC growth (10 - 25% CFC survival) using IM (n = 15 patients). In the same conditions, we have not observed any significant inhibitory effect of IM and ICC combination in cord-blood derived progenitors (n = 3). To determine the effects of these combinations in the most primitive stem cells, we have performed long-term cultures initiating cell (LTC-IC) assays using purified CD34+ cells (4.104 cells / dish) from CML patients with half medium changes each week for 5 weeks. The combination was tested in 6 (ICC+ IM) and 4 (ICC + DA / NIL) CML samples. As a control, CD34+ cells from cord blood were used. In CML samples tested with the combination of either IM / ICC (n = 6) or DA/ NIL and ICC (n = 4), CML LTC-IC derived progenitors were highly inhibited (ICC and IM) or undetectable (ICC and DA or NIL). Short-term cultures of CML CD34+ cells in the presence of 5 growth factors with or without ICC showed that ICC induced the expression of myeloid markers and highly favored the appearance of double positive CD14/CD15 cells. Experiments are underway to determine if ICC interferes with the expression of the components of SHH pathway (Smo, Ptched, Gli). as well as the gene expression profiling of CML cells treated with ICC. Thus, these results establish that ICC, a clinically used derivative of vitamin D3 has a clear activity in CML progenitors by itself and a major synergistic effect with TKI. A clinical phase 2 trial aiming to confirm the synergistic effect of ICC and TKI is ongoing in CML patients treated with imatinib. Citation Format: Ali G. Turhan, Hyacinthe Johnson Ansah, Patricia Hugues, Camille Debord, Remi Delansorne, Agnes Guerci-Bresler, Jean Francois Dufour Lamartinie, Annelise Bennaceur-Griscelli. Vitamin D3 analog inecalcitol synergizes with tyrosine kinase inhibitors (TKI) and selectively inhibit the growth of chronic myeloid leukemia (CML) progenitors: Development of a clinically applicable leukemic stem cell targeting strategy. [abstract]. In: Proceedings of the 106th Annual Meeting of the American Association for Cancer Research; 2015 Apr 18-22; Philadelphia, PA. Philadelphia (PA): AACR; Cancer Res 2015;75(15 Suppl):Abstract nr 2633. doi:10.1158/1538-7445.AM2015-2633

Highlights from Recent Cancer Literature

Highlights from Recent Cancer Literature

Hypoxia Selects Bortezomib-Resistant Stem Cells of Chronic Myeloid Leukemia

We previously demonstrated that severe hypoxia inhibits growth of Chronic Myeloid Leukemia (CML) cells and selects stem cells where BCR/Ablprotein is suppressed, although mRNA is not, so that hypoxia-selected stem cells, while remaining leukemic, are independent of BCR/Abl signaling and thereby refractory to Imatinib-mesylate. The main target of this study was to address the effects of the proteasome inhibitor Bortezomib (BZ) on the maintenance of stem or progenitor cells in hypoxic primary cultures (LC1), by determining the capacity of LC1 cells to repopulate normoxic secondary cultures (LC2) and the kinetics of this repopulation. Unselected K562 cells from day-2 hypoxic LC1 repopulated LC2 with rapid, progenitor-type kinetics; this repopulation was suppressed by BZ addition to LC1 at time 0, but completely resistant to day-1 BZ, indicating that progenitors require some time to adapt to stand hypoxia. K562 cells selected in hypoxic day-7 LC1 repopulated LC2 with stem-type kinetics, which was largely resistant to BZ added at either time 0 or day 1, indicating that hypoxia-selectable stem cells are BZ-resistant per se, i.e. before their selection. Furthermore, these cells were completely resistant to day-6 BZ, i.e. after selection. On the other hand, hypoxia-selected stem cells from CD34-positive cells of blast-crisis CML patients appeared completely resistant to either time-0 or day-1 BZ. To exploit in vitro the capacity of CML cells to adapt to hypoxia enabled to detect a subset of BZ-resistant leukemia stem cells, a finding of particular relevance in light of the fact that our experimental system mimics the physiologically hypoxic environment of bone marrow niches where leukemia stem cells most likely home and sustain minimal residual disease in vivo. This suggests the use of BZ as an enhanced strategy to control CML. in particular to prevent relapse of disease, to be considered with caution and to need further deepening.