Somervaille, T. C. P. & Cleary, M. L. Identification and characterization of leukemia stem cells in murine MLL-AF9 acute myeloid leukemia. Cancer Cell 10, 257-268

Stanford University, Stanford, California, United States
Cancer Cell (Impact Factor: 23.52). 11/2006; 10(4):257-68. DOI: 10.1016/j.ccr.2006.08.020
Source: PubMed
Using a mouse model of human acute myeloid leukemia (AML) induced by the MLL-AF9 oncogene, we demonstrate that colony-forming cells (CFCs) in the bone marrow and spleen of leukemic mice are also leukemia stem cells (LSCs). These self-renewing cells (1) are frequent, accounting for 25%-30% of myeloid lineage cells at late-stage disease; (2) generate a phenotypic, morphologic, and functional leukemia cell hierarchy; (3) express mature myeloid lineage-specific antigens; and (4) exhibit altered microenvironmental interactions by comparison with the oncogene-immortalized CFCs that initiated the disease. Therefore, the LSCs responsible for sustaining, expanding, and regenerating MLL-AF9 AML are downstream myeloid lineage cells, which have acquired an aberrant Hox-associated self-renewal program as well as other biologic features of hematopoietic stem cells.

Full-text preview

Available from:
Identification and characterization of leukemia stem cells in
murine MLL-AF9 acute myeloid leukemia
Tim C.P. Somervaille
and Michael L. Cleary
Department of Pathology, Stanford University School of Medicine, Stanford, California 94305
Using a mouse model of human acute myeloid leukemia (AML) induced by the MLL-AF9 oncogene, we demonstrate that
colony-forming cells (CFCs) in the bone marrow and spleen of leukemic mice are also leukemia stem cells (LSCs). These
self-renewing cells (1) are frequent, accounting for 25%–30% of myeloid lineage cells at late-stage disease; (2) generate
a phenotypic, morphologic, and functional leukemia cell hierarchy; (3) express mature myeloid lineage-specific antigens;
and (4) exhibit altered microenvironmental interactions by comparison with the oncogene-immortalized CFCs that initiated
the disease. Therefore, the LSCs responsible for sustaining, expanding, and regenerating MLL-AF9 AML are downstream
myeloid lineage cells, which have acquired an aberrant Hox-associated self-renewal program as well as other biologic
features of hematopoietic stem cells.
Acute myeloid leukemia (AML) is a clonal neoplastic disorder
that originates from a single transformed cell, which has pro-
gressively acquired critical genetic or epigenetic changes that
disrupt key growth-regulatory pathways (Hanahan and Wein-
berg, 2000). Within the leukemia clone, there is significant cellu-
lar morphologic, phenotypic, and functional heterogeneity anal-
ogous to the hierarchical organization of normal hematopoiesis.
Notably, only a subfraction of cells are proposed to be leukemia
stem cells (LSCs) with the ability to self-renew extensively, and
to initiate, sustain, or regenerate the disease. Conversely, the
majority of cells are either transitional cells with limited prolifer-
ative capacity or more differentiated end cells (Mackillop et al.,
1983; Kummermehr, 2001). Evidence for a hierarchical cellular
organization of human AML derives from studies showing that
only a small proportion of AML cells are clonogenic in in vitro
culture (Buick et al., 1977), and that an even smaller fraction of
AML blood blasts, defined by a CD34
surface pheno-
type, can transfer disease to immune-deficient mice (Lapidot
et al., 1994; Bonnet and Dick, 1997). Since normal human hema-
topoietic stem cells (HSCs) are also CD34
, these and
other observations (Miyamoto et al., 2000; Hope et al., 2003)
have been taken to suggest that AML LSCs originate from and
reside exclusively within the most immature bone marrow
(BM) progenitor compartment. However, this lineal relationship,
which has important pathogenic and clinical implications, may
not always hold true. For example, a recent study of blastic
transformation of chronic myeloid leukemia proposed that cells
with a granulocyte-macrophage progenitor (GMP) cell pheno-
type were candidate LSCs (Jamieson et al., 2004).
Elimination of the LSC compartment within the leukemia clone
is likely to be essential, and probably sufficient, for cure of dis-
ease, and thus increasing efforts have focused on attempting
to define the unique biological properties of AML LSCs by com-
parison with the transit and end cell compartments within the
leukemia, as well as with normal hematopoietic stem and pro-
genitor cells. However, an essential prerequisite for defining
these unique properties, so that targeted chemo- and immuno-
therapeutic strategies may be developed, is an accurate deter-
mination of the phenotype as well as the frequency of LSCs
within the AML clone. To date, such efforts have primarily
focused on xenografting human leukemia cells into immune-
deficient mice. A complementary, but currently unexploited,
approach is to characterize LSCs in mouse genetic models of
human leukemia, which have proven to be invaluable tools in
defining the mechanisms of disease pathogenesis. Two recent
studies have demonstrated that AML may be initiated by expres-
sion of MLL-ENL or MOZ-TIF2 in progenitor cells with limited
self-renewal capacity, as well as in HSCs (Cozzio et al., 2003;
Huntly et al., 2004). However, these studies did not address
the critical issue of whether the respective murine leukemias
An essential prerequisite for the development of more effective targeted therapies in AML is a characterization of the frequency and
biological properties of LSCs. In a mouse model of human MLL-AF9 AML, we have defined the size and lineal derivation of the LSC com-
partment, the extent of which was significantly underestimated by limit dilution analysis. Our findings support a revision of the prevailing
hypothesis that AML LSCs are always rare and solely located within the most immature bone marrow stem/progenitor compartment.
Furthermore, LSCs exhibit markedly different microenvironmental interactions, compared with cells simply immortalized by MLL-AF9,
indicating that acquisition of sensitivity to stromal cell-derived survival and proliferative signals is a critical feature of LSCs, in addition
to their extensive self-renewal capabilities.
CANCER CELL 10, 257–268, OCTOBER 2006 ª2006 ELSEVIER INC. DOI 10.1016/j.ccr.2006.08.020 257
Page 1
were sustained by a small fraction of self-renewing Lin
and/or progenitor cells, as predicted by current models of AML
based on NOD/SCID transplantation assays, or alternatively,
whether the LSC compartment is larger and altogether distinct
from the normal stem and progenitor compartment.
We report here the identification and characterization of LSCs
in a mouse model of AML initiated by MLL-AF9, a frequently
occurring MLL fusion oncogene typically associated with the
FAB-M4 or M5 subtypes of human AML (Swansbury et al.,
1998). Our studies indicate that LSCs are neither rare nor synon-
ymous with the stem and progenitor cells targeted by initiating
MLL mutations. Rather, LSCs in this model are frequent, located
almost exclusively downstream of the normal progenitor com-
partment by immunophenotype, and constitute myeloid lineage
cells that have acquired an aberrant self-renewal program as
well as other biologic features of HSCs, including substantially
altered microenvironmental interactions.
MLL-AF9-immortalized colony-forming cells display high
leukemia-initiating potential
The leukemogenic potential of single MLL-AF9-immortalized
colony-forming cells (CFCs) was evaluated using a retroviral
transduction/transplantation assay that reproducibly reads out
the properties of MLL fusion oncogenes (Lavau et al., 1997).
BM stem and progenitor cells (c-kit
) from EGFP transgenic
mice were transduced with MLL-AF9 and serially replated in
semisolid medium (Figures 1A and 1B). At the end of the third
round of culture, individual colonies were isolated and ex-
panded further in either liquid or semisolid media (Figure 1A).
Fourteen lines (representative of ten unique clones) (Figure 1C)
were randomly selected and injected (10
cells) into separate
sublethally irradiated, wild-type recipients. All mice developed
AML, with a median latency of 84.5 days (range 60–121) (Figures
1D and 1E; Tables S1 and S2 in the Supplemental Data available
with this article online). Southern blot analysis demonstrated
that each leukemia was clonally identical to its respective in-
jected cell population (Figure 1C). Therefore, immortalized
colony-forming cells (ICs) transformed by MLL-AF9 in vitro con-
sistently possess the potential to initiate leukemias in vivo, dem-
onstrating a high correlation of CFC activity with leukemogenic
potential in this model of AML.
LSCs are frequent in mice with MLL-AF9 myeloid
A similar approach was employed to analyze the leukemogenic
potential of CFCs derived from leukemic mice (Figure 2A).
Using semisolid culture assays, the CFC frequencies in the
BM and spleens of leukemic mice were 29.8% 6 4.1% and
Figure 1. MLL-AF9-immortalized CFCs have high
leukemogenic potential
A: Schematic illustration of the experimental
approach employed to assess the correlation
of leukemogenic potential with CFC activity of
MLL-AF9-immortalized cells. BM stem and pro-
genitor cells (c-kit
) were transduced with MLL-
AF9 and then serially replated in methylcellulose
medium every 5 days, with G418 drug selection
in the first round. Single colonies (33 total over
five experiments) with either type I (16 each) or
type II (17 each) morphology (Lavau et al.,
1997) were plucked and individually expanded
in liquid (29) or semisolid (4) medium, and 10
cells were then transplanted into syngeneic re-
cipient mice. Single CFCs routinely expanded
to 10
progeny cells within 12–15 days.
B: The mean (6SEM) number of colonies (R1000
cells) per 10,000 cells plated in each round is indi-
cated. The clonogenic potential of progenitors
transduced with empty vector was exhausted
by the end of round two (data not shown). The
mean (6SEM) frequency of CFCs at the time of
transplant in the 14 lines derived from single
plucked colonies is indicated in the last column
C: Southern blot analysis (left panel) demon-
strates the integration sites in 14 separate trans-
planted lines derived from single immortalized
CFCs (neo probe of Stu1-digested genomic
DNA). A median of three integration sites per
clone is observed. Comparison of the integration
sites (right panel) in three representative paired
transplanted lines (L) with their respective AML
cells (A) confirmed that they were clonally
D: Survival curve of animals transplanted with
cells (10
) derived from single MLL-AF9-immortal-
ized CFCs.
E: Representative cytospin of splenocytes (May
Grunwald Giemsa stain) from a mouse with
Page 2

You are reading a preview. Would you like to access the full-text?

support from the Children’s Health Initiative of the Packard Foundation and
PHS grants CA55029 and CA116601.
Received: March 14, 2006
Revised: July 27, 2006
Accepted: August 28, 2006
Published: October 16, 2006
Ailles, L.E. , Gerhard, B., Kawagoe, H., and Hogge, D.E. (1999). Growth char-
acteristics of acute myelogenous leukemia progenitors that initiate malignant
hematopoiesis in nonobese diabetic/severe combined immunodeficient
mice. Blood 94, 1761–1772.
Ayton, P.M., and Cleary, M.L. (2001). Molecular mechanisms of leukemogen-
esis mediated by MLL fusion proteins. Oncogene 20, 5695–5707.
Bhowmick, N.A., Neilson, E.G., and Moses, H.L. (2004). Stromal fibroblasts in
cancer initiation and progression. Nature 432, 332–337.
Blair, A., and Sutherland, H.J. (2000). Primitive acute myeloid leukemia cells
with long-term proliferative ability in vitro and in vivo lack surface expression
of c-kit (CD117). Exp. Hematol. 28, 660–671.
Blair, A., Hogge, D.E., Ailles, L.E., Lansdorp, P.M., and Sutherland, H.J.
(1997). Lack of expression of Thy- 1 (CD90) on acute myeloid leukemia cells
with long-term proliferative ability in vitro and in vivo. Blood 89, 3104–3112.
Boggs, D.R. (1984). The total marrow mass of the mouse: A simplified
method of measurement. Am. J. Hematol. 16, 277–286.
Bonnet, D., and Dick, J.E. (1997). Human acute myeloid leukemia is orga-
nized as a hierarchy that originates from a primitive hematopoietic cell.
Nat. Med. 3, 730–737.
Bonnet, D., Bhatia, M., Wang, J.C., Kapp, U., and Dick, J.E. (1999). Cytokine
treatment or accessory cells are required to initiate engraftment of purified
primitive human hematopoietic cells transplanted at limiting doses into
NOD/SCID mice. Bone Marrow Transplant. 23, 203–209.
Buick, R.N., Till, J.E., and McCulloch, E.A. (1977). Colony assay for prolifer-
ative blast cells circulating in myeloblastic leukaemia. Lancet 1, 862–863.
Cancelas, J.A., Lee, A.W., Prabhakar, R., Stringer, K.F., Zheng, Y., and Wil-
liams, D.A. (2005). Rac GTPases differentially integrate signals regulating
hematopoietic stem cell localization. Nat. Med. 11 , 886–891.
Camargo, F.D., Chambers, S.M., Drew, E., McNagny, K.M., and Goodell,
M.A. (2006). Hematopoietic stem cells do not engraft with absolute efficien-
cies. Blood 107, 501–507.
Castor, A., Nilsson, L., Astrand-Grundstrom, I., Buitenhuis, M., Ramirez, C.,
Anderson, K., Strombeck, B., Garwicz, S., Bekassy, A.N., Schmiegelow, K.,
et al. (2005). Distinct patterns of hematopoietic stem cell involvement in acute
lymphoblastic leukemia. Nat. Med. 11, 630–637.
Collins, L.S., and Dorshkind, K. (1987). A stromal cell line from myeloid long-
term bone marrow cultures can support myelopoiesis and B lymphopoiesis.
J. Immunol. 138, 1082–1087.
Cozzio, A., Passegue, E., Ayton, P.M., Karsunky, H., Cleary, M.L., and Weiss-
man, I.L. (2003). Similar MLL-associated leukemias arising from self-renew-
ing stem cells and short-lived myeloid progenitors. Genes Dev. 17, 3029–
DiMartino, J.F., Ayton, P.M., Chen, E.H., Naftzger, C.C., Young, B.D., and
Cleary, M.L. (2002). The AF10 leucine zipper is required for leukemic transfor-
mation of myeloid progenitors by MLL-AF10. Blood 99, 3780–3785.
Feuring-Buske, M., Gerhard, B., Cashman, J., Humphries, R.K., Eaves, C.J.,
and Hogge, D.E. (2003). Improved engraftment of human acute myeloid
leukemia progenitor cells in beta 2-microglobulin-deficient NOD/SCID mice
and in NOD/SCID mice transgenic for human growth factors. Leukemia 17,
Giles, F.J., Keating, A., Goldstone, A.H., Avivi, I., Willman, C.L., and Kantar-
jian, H.M. (2002). Acute myeloid leukemia. Hematology Am. Soc. Hematol.
Educ. Program, 73–110.
Gu, Y., Filippi, M., Cancelas, J.A., Siefring, J.E., Williams, E.P., Jasti, A.C.,
Harris, C.E., Lee, A.W., Prabhakar, R., Atkinson, S.J., et al. (2003). Hemato-
poietic cell regulation by Rac1 and Rac2 guanosine triphosphatases. Sci-
ence 302, 445–449.
Hanahan, D., and Weinberg, R.A. (2000). The hallmarks of cancer. Cell 100,
Hewitt, H.B., Blake, E., and Proter, E.H. (1973). The effect of lethally irradiated
cells on the transplantability of murine tumours. Br. J. Cancer 28, 123–135.
Hewitt, H.B., Blake, E.R., and Walder, A.S. (1976). A critique of the evidence
for active host defence against cancer, based on personal studies of 27
murine tumours of spontaneous origin. Br. J. Cancer 33, 241–259.
Hill, R.P., and Milas, L. (1989). The proportion of stem cells in murine tumors.
Int. J. Radiat. Oncol. Biol. Phys. 16, 513–518.
Hope, K.J., Jin, L., and Dick, J.E. (2003). Human acute myeloid leukemia
stem cells. Arch. Med. Res. 34, 507–514.
Huntly, B.J., Shigematsu, H., Deguchi, K., Lee, B.H., Mizuno, S., Duclos, N.,
Rowan, R., Amaral, S., Curley, D., Williams, I.R., et al. (2004). MOZ-TIF2, but
not BCR-ABL, confers properties of leukemic stem cells to committed mu-
rine hematopoietic progenitors. Cancer Cell 6, 587–596.
Ito, K., Hirao, A., Arai, F., Matsuoka, S., Takubo, K., Hamaguchi, I., No-
miyama, K., Hosokawa, K., Sakurada, K., Nakagata, N., et al. (2004). Regu-
lation of oxidative stress by ATM is required for self-renewal of haemato-
poietic stem cells. Nature 431, 997–1002.
Jamieson, C.H., Ailles, L.E., Dylla, S.J., Muijtjens, M., Jones, C., Zehnder,
J.L., Gotlib, J., Li, K., Manz, M.G., Keating, A., et al. (2004). Granulocyte-
macrophage progenitors as candidate leukemic stem cells in blast-crisis
CML. N. Engl. J. Med. 351, 657–667.
Johnson, J.J., Chen, W., Hudson, W., Yao, Q., Taylor, M., Rabbitts, T.H., and
Kersey, J.H. (2003). Prenatal and postnatal myeloid cells demonstrate step-
wise progression in the pathogenesis of MLL fusion gene leukemia. Blood
101, 3229–3235.
Kodama, H., Nose, M., Niida, S., and Nishikawa, S. (1994). Involvement of the
c-kit receptor in the adhesion of hematopoietic stem cells to stromal cells.
Exp. Hematol. 22, 979–984.
Krivtsov, A.V., Twomey, D., Feng, Z., Stubbs, M.C., Wang, Y., Faber, J., Lev-
ine, J.E., Wang, J., Hahn, W.C., Gilliland, D.G., et al. (2006). Transformation
from committed progenitor to leukemia stem cell initiated by MLL-AF9.
Nature 442, 818–822.
Kummermehr, J.C. (2001). Tumour stem cells—The evidence and the ambi-
guity. Acta Oncol. 40, 981–988.
Lapidot, T., Sirard, C., Vormoor, J., Murdoch, B., Hoang, T., Caceres-Cortes,
J., Minden, M., Paterson, B., Caligiuri, M.A., and Dick, J.E. (1994). A cell ini-
tiating human acute myeloid leukaemia after transplantation into SCID mice.
Nature 367, 645–648.
Lavau, C., Szilvassy, S.J., Slany, R., and Cleary, M.L. (1997). Immortalization
and leukemic transformation of a myelomonocytic precursor by retrovirally
transduced HRX-ENL. EMBO J. 16, 4226–4237.
Mackillop, W.J., Ciampi, A., Till, J.E., and Buick, R.N. (1983). A stem cell
model of human tumor growth: Implications for tumor cell clonogenic assays.
J. Natl. Cancer Inst. 70, 9–16.
Miller, C.L., and Eaves, C.J. (1997). Expansion in vitro of adult murine hema-
topoietic stem cells with transplantable lympho-myeloid reconstituting abil-
ity. Proc. Natl. Acad. Sci. USA 94, 13648–13653.
Miyamoto, T., Weissman, I.L., and Akashi, K. (2000). AML1/ETO-expressing
nonleukemic stem cells in acute myelogenous leukemia with 8;21 chromo-
somal transl ocation. Proc. Natl. Acad. Sci. USA 97, 7521–7526.
Orimo, A., Gupta, P.B., Sgroi, D.C., Arenzana-Seisdedos, F., Delaunay, T.,
Naeem, R., Carey, V.J., Richardson, A.L., and Weinberg, R.A. (2005). Stromal
fibroblasts present in invasive human breast carcinomas promote tumor
Page 11
growth and angiogenesis through elevated SDF-1/CXCL12 secretion. Cell
121, 335–348.
Pearce, D.J., Taussig, D., Zibara, K., Smith, L.L., Ridler, C.M., Preudhomme,
C., Young, B.D., Rohatiner, A.Z., Lister, T.A., and Bonnet, D. (2006). AML en-
graftment in the NOD/SCID assay reflects the outcome of AML: Implications
for our understanding of the heterogeneity of AML. Blood 107, 1166–1173.
Peled, A., Petit, I., Kollet, O., Magid, M., Ponomaryov, T., Byk, T., Nagler, A.,
Ben-Hur, H., Many, A., Shultz, L., et al. (1999). Dependence of human stem
cell engraftment and repopulation of NOD/SCID mice on CXCR4. Science
283, 845–848.
Shultz, L.D., Lyons, B.L., Burzenski, L.M., Gott, B., Chen, X., Chaleff, S.,
Kotb, M., Gillies, S.D., King, M., Mangada, J., et al. (2005). Human lymphoid
and myeloid cell development in NOD/LtSz-scid IL2R gamma null mice en-
grafted with mobilized human hemopoietic stem cells. J. Immunol. 174,
Swansbury, G.J., Slater, R., Bain, B.J., Moorman, A.V., and Secker-Walker,
L.M. (1998). Hematological malignancies with t(9;11)(p21-22;q23)—A labora-
tory and clinical study of 125 cases. European 11q23 Workshop participants.
Leukemia 12, 792–800.
Szilvassy, S.J., Ragland, P.L., Miller, C.L., and Eaves, C.J. (2003). The mar-
row homing efficiency of murine hematopoietic stem cells remains constant
during ontogeny. Exp. Hematol. 31, 331–338.
Terskikh, A.V., Miyamoto, T., Chang, C., Diatchenko, L., and Weissman, I.L.
(2003). Gene expression analysis of purified hematopoietic stem cells and
committed progenitors. Blood 102, 94–101.
Trott, K.R. (1994). Tumour stem cells: The biological concept and its applica-
tion to cancer treatment. Radiother. Oncol. 30, 1–5.
Verlinden, S.F., van Es, H.H., and van Bekkum, D.W. (1998). Serial bone mar-
row sampling for long-term follow up of human hematopoiesis in NOD/SCID
mice. Exp. Hematol. 26, 627–630.
Wang, J., Iwasaki, H., Krivtsov, A., Febbo, P.G., Thorner, A.R., Ernst, P.,
Anastasiadou, E., Kutok, J.L., Kogan, S.C., Zinkel, S.S., et al. (2005). Condi-
tional MLL-CBP targets GMP and models therapy-related myeloproliferative
disease. EMBO J. 24, 368–381.
Yang, F.C., Atkinson, S.J., Gu, Y., Borneo, J.B., Roberts, A.W., Zheng, Y.,
Pennington, J., and Williams, D.A. (2001). Rac and Cdc42 GTPases control
hematopoietic stem cell shape, adhesion, migration and mobilization.
Proc. Natl. Acad. Sci. USA 98, 5614–5618.
Yuan, Y., Shen, H., Franklin, D.S., Scadden, D.T., and Cheng, T. (2004). In
vivo self-renewing divisions of haematopoietic stem cells are increased in
the absence of the early G1-phase inhibitor, p18INK4C. Nat. Cell Biol. 6,
Page 12
    • "Recurrent mutations in transcription factors (TFs) and epigenetic regulators identified in AML (Dö hner et al., 2015; Cancer Genome Atlas Research Network, 2013) suggest that aberrant transcriptional circuits are a common feature of leukemogenesis. Collectively, these circuits drive oncogenic gene expression programs that inhibit differentiation and activate self-renewal, generating leukemia stem cells (LSCs) responsible for the initiation and propagation of disease (Chao et al., 2008; Reya et al., 2001; Somervaille and Cleary, 2006). In leukemias with rearrangements of the Mixed Lineage Leukemia (MLL) gene, activation of a self-renewal circuit involving the Hox gene cluster is a key aspect in the transformation of committed myeloid progenitor cells (Krivtsov et al., 2009). "
    [Show abstract] [Hide abstract] ABSTRACT: Leukemia stem cells (LSCs) have the capacity to self-renew and propagate disease upon serial transplantation in animal models, and elimination of this cell population is required for curative therapies. Here, we describe a series of pooled, in vivo RNAi screens to identify essential transcription factors (TFs) in a murine model of acute myeloid leukemia (AML) with genetically and phenotypically defined LSCs. These screens reveal the heterodimeric, circadian rhythm TFs Clock and Bmal1 as genes required for the growth of AML cells in vitro and in vivo. Disruption of canonical circadian pathway components produces anti-leukemic effects, including impaired proliferation, enhanced myeloid differentiation, and depletion of LSCs. We find that both normal and malignant hematopoietic cells harbor an intact clock with robust circadian oscillations, and genetic knockout models reveal a leukemia-specific dependence on the pathway. Our findings establish a role for the core circadian clock genes in AML.
    No preview · Article · Apr 2016 · Cell
  • Source
    • "Label-retention assays are used for cell-cycle kinetics and utilize the incorporation of DNA analogs, like BrdU and EdU, for DNA labeling. The labeled DNA is tracked and label retention is determined over time; low label retention indicates high cell proliferation [21]. Side population assays discriminate stem-like cell populations based on the dye efflux properties of ABC transporters [22]. "
    [Show abstract] [Hide abstract] ABSTRACT: Cancer Stem Cells (CSC) hypothesis cites cancer stem cells as the main culprits of tumor initiation, propagation, metastasis and failure of conventional therapy. An accurate description of these cells will strengthen our knowledge about tumor development and clinical aspects. Since cancer stem cells make a minority subpopulation of tumors, their detection and characterization is a critical step. Nowadays in vitro and in vivo assays have been developed addressing the self-renewal and differentiation of cancer stem cells. Furthermore, in vivo studies take advantage of advanced molecular imaging technology to facilitate their detection and come new knowledge of the behavior of these cells.
    Full-text · Article · Mar 2016 · Drug Discovery Today
  • Source
    • "See alsoFigure S1 and Tables S1–S3. cells (LSCs) (Krivtsov et al., 2006; Somervaille and Cleary, 2006) (Figures S2J and S2K). Interestingly, effects on apoptosis were less pronounced, as higher concentrations of both compounds were required for pronounced apoptotic effect in MLL leukemia cells (Figure 2G ). "
    [Show abstract] [Hide abstract] ABSTRACT: Chromosomal translocations affecting mixed lineage leukemia gene (MLL) result in acute leukemias resistant to therapy. The leukemogenic activity of MLL fusion proteins is dependent on their interaction with menin, providing basis for therapeutic intervention. Here we report the development of highly potent and orally bioavailable small-molecule inhibitors of the menin-MLL interaction, MI-463 and MI-503, and show their profound effects in MLL leukemia cells and substantial survival benefit in mouse models of MLL leukemia. Finally, we demonstrate the efficacy of these compounds in primary samples derived from MLL leukemia patients. Overall, we demonstrate that pharmacologic inhibition of the menin-MLL interaction represents an effective treatment for MLL leukemias in vivo and provide advanced molecular scaffold for clinical lead identification. Copyright © 2015 Elsevier Inc. All rights reserved.
    Full-text · Article · Mar 2015 · Cancer cell
Show more