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LSK derived LSK- cells have a high apoptotic rate related to survival regulation of hematopoietic and leukemic stem cells.

Peng C, Chen Y, Shan Y, Zhang H, Guo Z, Li D, Li S - PLoS ONE (2012)

Bottom Line: Here we show that the Lin(-)Sca-1(+)c-Kit(-) (LSK(-)) cell population derived from HSC-containing Lin(-)Sca-1(+)c-Kit(+) (LSK) cells has significantly higher numbers of apoptotic cells.In contrast, the LSK(-) population is reduced in CML mice, and depletion of leukemia stem cells (LSCs; BCR-ABL-expressing HSCs) by deleting Alox5 or by inhibiting heat shock protein 90 causes an increase in this LSK(-) population.These results indicate a potential function of the LSK(-) cells in the regulation of LSK cells and LSCs.

View Article: PubMed Central - PubMed

Affiliation: Division of Hematology/Oncology, Department of Medicine, University of Massachusetts Medical School, Worcester, Massachusetts, United States of America.

ABSTRACT
A balanced pool of hematopoietic stem cells (HSCs) in bone marrow is tightly regulated, and this regulation is disturbed in hematopoietic malignancies such as chronic myeloid leukemia (CML). The underlying mechanisms are largely unknown. Here we show that the Lin(-)Sca-1(+)c-Kit(-) (LSK(-)) cell population derived from HSC-containing Lin(-)Sca-1(+)c-Kit(+) (LSK) cells has significantly higher numbers of apoptotic cells. Depletion of LSK cells by radiation or the cytotoxic chemical 5-fluorouracil results in an expansion of the LSK(-) population. In contrast, the LSK(-) population is reduced in CML mice, and depletion of leukemia stem cells (LSCs; BCR-ABL-expressing HSCs) by deleting Alox5 or by inhibiting heat shock protein 90 causes an increase in this LSK(-) population. The transition of LSK to LSK(-) cells is controlled by the Icsbp gene and its downstream gene Lyn, and regulation of this cellular transition is critical for the survival of normal LSK cells and LSCs. These results indicate a potential function of the LSK(-) cells in the regulation of LSK cells and LSCs.

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Related in: MedlinePlus

An increase in LSK − CD150− cells reflects apoptosis of HSCs.(A) The LSK− cell population is basically CD150-negative. LSK+ (Lin−Sca1+c-Kit+) cells and LSK− (Lin−Sca1+c-Kit−) cells from bone marrow of B6 mice were stained with CD150, and analyzed by FACS. (B) High apoptotic rates in bone marrow LSK−CD150− cells. LSK+ and LSK− cells from bone marrow of B6 mice were stained with CD150, further labeled with 7AAD and Annexin V, and analyzed by FACS. Apoptotic rate for each cell population was indicated. (C) An increase in LSK−CD150− cells reflects apoptosis of HSCs. B6 mice were treated with irradiation or 5-FU for different days as indicated. LSK+ and LSK− cells from bone marrow of B6 mice were stained with CD150, were further labeled with 7AAD and Annexin V, and analyzed by FACS.
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pone-0038614-g003: An increase in LSK − CD150− cells reflects apoptosis of HSCs.(A) The LSK− cell population is basically CD150-negative. LSK+ (Lin−Sca1+c-Kit+) cells and LSK− (Lin−Sca1+c-Kit−) cells from bone marrow of B6 mice were stained with CD150, and analyzed by FACS. (B) High apoptotic rates in bone marrow LSK−CD150− cells. LSK+ and LSK− cells from bone marrow of B6 mice were stained with CD150, further labeled with 7AAD and Annexin V, and analyzed by FACS. Apoptotic rate for each cell population was indicated. (C) An increase in LSK−CD150− cells reflects apoptosis of HSCs. B6 mice were treated with irradiation or 5-FU for different days as indicated. LSK+ and LSK− cells from bone marrow of B6 mice were stained with CD150, were further labeled with 7AAD and Annexin V, and analyzed by FACS.

Mentions: CD150 is a major SLAM family receptor expressed on HSCs and has been shown to be a useful cell surface marker for classifying LSK cells into a highly enriched stem cell population [15]. To more clearly show the relationship between the apoptotic LSK− cell population and HSCs, we further narrowed down the LSK and LSK− populations by adding CD150 analysis, and re-validated our 5-FU and irradiation experiments shown in Fig. 2. We found that in normal B6 mice, about 1/4 (23.2%) of bone marrow LSK cells in the lineage-negative (Lin−) population were CD150 positive and 3/4 (76.8%) of these cells were CD150 negative (Fig. 3A); both cell populations had similar apoptotic rates (3.4% and 3.5%; Fig. 3B). In contrast, greater than 90% the LSK− cells were CD150−, with only about 5.4% of CD150+ cells; both populations also had similar apoptotic rates (13% and 14%; Fig. 3B), which were much higher than those for the LSK cells. Thus, the addition of CD150 staining to LSK+ and LSK− cells gave the same result as the one obtained without using the CD150 marker (Fig. 2A, D). In addition, because almost all cells in the LSK− population are CD150− (Fig. 3A), the addition of CD150 staining would not change the result for the apoptotic rate of this cell population. To further emphasize this point, we repeated our 5-FU and irradiation experiments (Fig. 2) by adding the CD150 staining to LSK+ and LSK− cells. Comparing to untreated mice (Day 0) in which LSK− cells were basically negative for CD150 (about 95% of LSK− cells were CD150−), both treatments caused a remarkable increase in the LSK−CD150− population as expected and also surprisingly in the LSK−CD150+ population, suggesting that a significant number of HSCs (LSK+CD150+) made a quick transition after irradiation or 5-FU treatment to become apoptotic LSK− cells, presumably without having time to turn down CD150 expression. In contrast, in a normal situation there are few LSK−CD150+ cells (Fig. 3A). The increase of the LSK−CD150− population after irradiation or 5-FU treatment accompanied with the decrease of the LSK+CD150+ population. This result, in addition to the fact that LSK− cells are basically negative for CD150, demonstrates that an increase in the LSK− population detected without using the CD150 marker should accurately reflect cellular transition of HSCs and LSCs to the LSK− population and apoptosis of these stem cells. Therefore, we excluded the use of the CD150 marker in the rest of our experiments in this study.


LSK derived LSK- cells have a high apoptotic rate related to survival regulation of hematopoietic and leukemic stem cells.

Peng C, Chen Y, Shan Y, Zhang H, Guo Z, Li D, Li S - PLoS ONE (2012)

An increase in LSK − CD150− cells reflects apoptosis of HSCs.(A) The LSK− cell population is basically CD150-negative. LSK+ (Lin−Sca1+c-Kit+) cells and LSK− (Lin−Sca1+c-Kit−) cells from bone marrow of B6 mice were stained with CD150, and analyzed by FACS. (B) High apoptotic rates in bone marrow LSK−CD150− cells. LSK+ and LSK− cells from bone marrow of B6 mice were stained with CD150, further labeled with 7AAD and Annexin V, and analyzed by FACS. Apoptotic rate for each cell population was indicated. (C) An increase in LSK−CD150− cells reflects apoptosis of HSCs. B6 mice were treated with irradiation or 5-FU for different days as indicated. LSK+ and LSK− cells from bone marrow of B6 mice were stained with CD150, were further labeled with 7AAD and Annexin V, and analyzed by FACS.
© Copyright Policy
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC3366951&req=5

pone-0038614-g003: An increase in LSK − CD150− cells reflects apoptosis of HSCs.(A) The LSK− cell population is basically CD150-negative. LSK+ (Lin−Sca1+c-Kit+) cells and LSK− (Lin−Sca1+c-Kit−) cells from bone marrow of B6 mice were stained with CD150, and analyzed by FACS. (B) High apoptotic rates in bone marrow LSK−CD150− cells. LSK+ and LSK− cells from bone marrow of B6 mice were stained with CD150, further labeled with 7AAD and Annexin V, and analyzed by FACS. Apoptotic rate for each cell population was indicated. (C) An increase in LSK−CD150− cells reflects apoptosis of HSCs. B6 mice were treated with irradiation or 5-FU for different days as indicated. LSK+ and LSK− cells from bone marrow of B6 mice were stained with CD150, were further labeled with 7AAD and Annexin V, and analyzed by FACS.
Mentions: CD150 is a major SLAM family receptor expressed on HSCs and has been shown to be a useful cell surface marker for classifying LSK cells into a highly enriched stem cell population [15]. To more clearly show the relationship between the apoptotic LSK− cell population and HSCs, we further narrowed down the LSK and LSK− populations by adding CD150 analysis, and re-validated our 5-FU and irradiation experiments shown in Fig. 2. We found that in normal B6 mice, about 1/4 (23.2%) of bone marrow LSK cells in the lineage-negative (Lin−) population were CD150 positive and 3/4 (76.8%) of these cells were CD150 negative (Fig. 3A); both cell populations had similar apoptotic rates (3.4% and 3.5%; Fig. 3B). In contrast, greater than 90% the LSK− cells were CD150−, with only about 5.4% of CD150+ cells; both populations also had similar apoptotic rates (13% and 14%; Fig. 3B), which were much higher than those for the LSK cells. Thus, the addition of CD150 staining to LSK+ and LSK− cells gave the same result as the one obtained without using the CD150 marker (Fig. 2A, D). In addition, because almost all cells in the LSK− population are CD150− (Fig. 3A), the addition of CD150 staining would not change the result for the apoptotic rate of this cell population. To further emphasize this point, we repeated our 5-FU and irradiation experiments (Fig. 2) by adding the CD150 staining to LSK+ and LSK− cells. Comparing to untreated mice (Day 0) in which LSK− cells were basically negative for CD150 (about 95% of LSK− cells were CD150−), both treatments caused a remarkable increase in the LSK−CD150− population as expected and also surprisingly in the LSK−CD150+ population, suggesting that a significant number of HSCs (LSK+CD150+) made a quick transition after irradiation or 5-FU treatment to become apoptotic LSK− cells, presumably without having time to turn down CD150 expression. In contrast, in a normal situation there are few LSK−CD150+ cells (Fig. 3A). The increase of the LSK−CD150− population after irradiation or 5-FU treatment accompanied with the decrease of the LSK+CD150+ population. This result, in addition to the fact that LSK− cells are basically negative for CD150, demonstrates that an increase in the LSK− population detected without using the CD150 marker should accurately reflect cellular transition of HSCs and LSCs to the LSK− population and apoptosis of these stem cells. Therefore, we excluded the use of the CD150 marker in the rest of our experiments in this study.

Bottom Line: Here we show that the Lin(-)Sca-1(+)c-Kit(-) (LSK(-)) cell population derived from HSC-containing Lin(-)Sca-1(+)c-Kit(+) (LSK) cells has significantly higher numbers of apoptotic cells.In contrast, the LSK(-) population is reduced in CML mice, and depletion of leukemia stem cells (LSCs; BCR-ABL-expressing HSCs) by deleting Alox5 or by inhibiting heat shock protein 90 causes an increase in this LSK(-) population.These results indicate a potential function of the LSK(-) cells in the regulation of LSK cells and LSCs.

View Article: PubMed Central - PubMed

Affiliation: Division of Hematology/Oncology, Department of Medicine, University of Massachusetts Medical School, Worcester, Massachusetts, United States of America.

ABSTRACT
A balanced pool of hematopoietic stem cells (HSCs) in bone marrow is tightly regulated, and this regulation is disturbed in hematopoietic malignancies such as chronic myeloid leukemia (CML). The underlying mechanisms are largely unknown. Here we show that the Lin(-)Sca-1(+)c-Kit(-) (LSK(-)) cell population derived from HSC-containing Lin(-)Sca-1(+)c-Kit(+) (LSK) cells has significantly higher numbers of apoptotic cells. Depletion of LSK cells by radiation or the cytotoxic chemical 5-fluorouracil results in an expansion of the LSK(-) population. In contrast, the LSK(-) population is reduced in CML mice, and depletion of leukemia stem cells (LSCs; BCR-ABL-expressing HSCs) by deleting Alox5 or by inhibiting heat shock protein 90 causes an increase in this LSK(-) population. The transition of LSK to LSK(-) cells is controlled by the Icsbp gene and its downstream gene Lyn, and regulation of this cellular transition is critical for the survival of normal LSK cells and LSCs. These results indicate a potential function of the LSK(-) cells in the regulation of LSK cells and LSCs.

Show MeSH
Related in: MedlinePlus