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Acute B lymphoblastic leukaemia-propagating cells are present at high frequency in diverse lymphoblast populations.

Rehe K, Wilson K, Bomken S, Williamson D, Irving J, den Boer ML, Staa M, Schrappe M, Hall AG, Heidenreich O, Vormoor J - EMBO Mol Med (2012)

Bottom Line: Here, we demonstrate in a wide range of primary patient samples and patient samples previously passaged through mice that leukaemia-propagating cells are found in all populations defined by high or low expression of the lymphoid differentiation markers CD10, CD20 or CD34.The frequency of leukaemia-propagating cells and their engraftment kinetics do not differ between these populations.Together, these findings suggest that there is no stem cell hierarchy in acute B lymphoblastic leukaemia.

View Article: PubMed Central - PubMed

Affiliation: Newcastle Cancer Centre at the Northern Institute for Cancer Research, Newcastle University, Newcastle upon Tyne, UK.

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Self-renewal gene expression in CD34high and CD34low B-ALL blastsExpression of TERT in CD34high and CD34low umbilical cord blood cells and leukaemic blasts. Umbilical cord blood shows higher expression of TERT in immature CD34high cells whilst no difference is seen between immature CD34high and CD34low blasts. TERT expression in blasts is comparable with, or higher than, that in CD34high umbilical cord blood progenitor cells. Expression values are 2-ΔCt using GAPDH as the reference gene. For purity of cells sorted for CD34 expression, see Supporting Information Fig S6.The PCA using a haematopoietic “self-renewal” signature containing 59 genes (213 probes) (Kim et al, 2009) also failed to separate CD34high and CD34low B-ALL populations (Supporting Information Fig S4). Here, we show the heatmap of the expression of 41 selected probes from this “self-renewal” signature.PCA plot generated using an AML “stem cell” signature (Eppert et al, 2011) that separates Lin-CD34highCD38low blasts (dark purple symbols) from more mature CD34low (pink symbols) blasts in AML (Gentles et al, 2010) but fails to detect any significant differences in “self-renewal” gene expression amongst the leukaemic subpopulations (black & white symbols) in B-ALL.
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fig03: Self-renewal gene expression in CD34high and CD34low B-ALL blastsExpression of TERT in CD34high and CD34low umbilical cord blood cells and leukaemic blasts. Umbilical cord blood shows higher expression of TERT in immature CD34high cells whilst no difference is seen between immature CD34high and CD34low blasts. TERT expression in blasts is comparable with, or higher than, that in CD34high umbilical cord blood progenitor cells. Expression values are 2-ΔCt using GAPDH as the reference gene. For purity of cells sorted for CD34 expression, see Supporting Information Fig S6.The PCA using a haematopoietic “self-renewal” signature containing 59 genes (213 probes) (Kim et al, 2009) also failed to separate CD34high and CD34low B-ALL populations (Supporting Information Fig S4). Here, we show the heatmap of the expression of 41 selected probes from this “self-renewal” signature.PCA plot generated using an AML “stem cell” signature (Eppert et al, 2011) that separates Lin-CD34highCD38low blasts (dark purple symbols) from more mature CD34low (pink symbols) blasts in AML (Gentles et al, 2010) but fails to detect any significant differences in “self-renewal” gene expression amongst the leukaemic subpopulations (black & white symbols) in B-ALL.

Mentions: The candidate gene we chose to test this hypothesis was TERT, encoding the reverse transcriptase protein subunit of telomerase. Telomerase restores telomeres and prevents replicative senescence. TERT protein supports the maintenance and expansion of normal and cancer stem cells both by telomerase-dependent and -independent mechanisms (Stewart et al, 2002). Moreover, our previous experiments showed that its expression is induced and maintained by key leukaemic fusion oncogenes, supporting its significant role in leukaemic propagation (Gessner et al, 2010). Unfortunately, the low expression levels of TERT may impede detection by gene expression arrays. We, therefore, analysed expression of TERT in CD34high and phenotypically more mature CD34low blasts using quantitative RT-PCR. In the absence of telomerase-independent alternative lengthening of telomeres, only blasts with TERT expression should possess the ability for long-term leukaemia propagation. As predicted, TERT mRNA levels in normal human umbilical cord blood were approximately five times higher in immature CD34high as compared with mature CD34low cells. In contrast, there were no differences in TERT expression between CD34high and CD34low leukaemic blasts (Fig 3A).


Acute B lymphoblastic leukaemia-propagating cells are present at high frequency in diverse lymphoblast populations.

Rehe K, Wilson K, Bomken S, Williamson D, Irving J, den Boer ML, Staa M, Schrappe M, Hall AG, Heidenreich O, Vormoor J - EMBO Mol Med (2012)

Self-renewal gene expression in CD34high and CD34low B-ALL blastsExpression of TERT in CD34high and CD34low umbilical cord blood cells and leukaemic blasts. Umbilical cord blood shows higher expression of TERT in immature CD34high cells whilst no difference is seen between immature CD34high and CD34low blasts. TERT expression in blasts is comparable with, or higher than, that in CD34high umbilical cord blood progenitor cells. Expression values are 2-ΔCt using GAPDH as the reference gene. For purity of cells sorted for CD34 expression, see Supporting Information Fig S6.The PCA using a haematopoietic “self-renewal” signature containing 59 genes (213 probes) (Kim et al, 2009) also failed to separate CD34high and CD34low B-ALL populations (Supporting Information Fig S4). Here, we show the heatmap of the expression of 41 selected probes from this “self-renewal” signature.PCA plot generated using an AML “stem cell” signature (Eppert et al, 2011) that separates Lin-CD34highCD38low blasts (dark purple symbols) from more mature CD34low (pink symbols) blasts in AML (Gentles et al, 2010) but fails to detect any significant differences in “self-renewal” gene expression amongst the leukaemic subpopulations (black & white symbols) in B-ALL.
© Copyright Policy - open-access
Related In: Results  -  Collection

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fig03: Self-renewal gene expression in CD34high and CD34low B-ALL blastsExpression of TERT in CD34high and CD34low umbilical cord blood cells and leukaemic blasts. Umbilical cord blood shows higher expression of TERT in immature CD34high cells whilst no difference is seen between immature CD34high and CD34low blasts. TERT expression in blasts is comparable with, or higher than, that in CD34high umbilical cord blood progenitor cells. Expression values are 2-ΔCt using GAPDH as the reference gene. For purity of cells sorted for CD34 expression, see Supporting Information Fig S6.The PCA using a haematopoietic “self-renewal” signature containing 59 genes (213 probes) (Kim et al, 2009) also failed to separate CD34high and CD34low B-ALL populations (Supporting Information Fig S4). Here, we show the heatmap of the expression of 41 selected probes from this “self-renewal” signature.PCA plot generated using an AML “stem cell” signature (Eppert et al, 2011) that separates Lin-CD34highCD38low blasts (dark purple symbols) from more mature CD34low (pink symbols) blasts in AML (Gentles et al, 2010) but fails to detect any significant differences in “self-renewal” gene expression amongst the leukaemic subpopulations (black & white symbols) in B-ALL.
Mentions: The candidate gene we chose to test this hypothesis was TERT, encoding the reverse transcriptase protein subunit of telomerase. Telomerase restores telomeres and prevents replicative senescence. TERT protein supports the maintenance and expansion of normal and cancer stem cells both by telomerase-dependent and -independent mechanisms (Stewart et al, 2002). Moreover, our previous experiments showed that its expression is induced and maintained by key leukaemic fusion oncogenes, supporting its significant role in leukaemic propagation (Gessner et al, 2010). Unfortunately, the low expression levels of TERT may impede detection by gene expression arrays. We, therefore, analysed expression of TERT in CD34high and phenotypically more mature CD34low blasts using quantitative RT-PCR. In the absence of telomerase-independent alternative lengthening of telomeres, only blasts with TERT expression should possess the ability for long-term leukaemia propagation. As predicted, TERT mRNA levels in normal human umbilical cord blood were approximately five times higher in immature CD34high as compared with mature CD34low cells. In contrast, there were no differences in TERT expression between CD34high and CD34low leukaemic blasts (Fig 3A).

Bottom Line: Here, we demonstrate in a wide range of primary patient samples and patient samples previously passaged through mice that leukaemia-propagating cells are found in all populations defined by high or low expression of the lymphoid differentiation markers CD10, CD20 or CD34.The frequency of leukaemia-propagating cells and their engraftment kinetics do not differ between these populations.Together, these findings suggest that there is no stem cell hierarchy in acute B lymphoblastic leukaemia.

View Article: PubMed Central - PubMed

Affiliation: Newcastle Cancer Centre at the Northern Institute for Cancer Research, Newcastle University, Newcastle upon Tyne, UK.

Show MeSH
Related in: MedlinePlus