Leukemic stromal hematopoietic microenvironment negatively regulates the normal hematopoiesis in mouse model of leukemia.
OBJECTIVE
Leukemic microenvironment has a major role in the progression of leukemia. Leukemic cells can induce reversible changes in microenvironmental components, especially the stromal function which results in improved growth conditions for maintaining the malignant leukemic cells. This study aimed to investigate the survival advantage of leukemic cells over normal hematopoietic cells in stromal microenvironment in long term.


METHODS
The mice were injected intraperitoneally with N-N' ethylnitrosourea (ENU) to induce leukemia; the mice received injection of normal saline were used as control. At 180 days after ENU induction, the mice were killed and the bone marrows were cultured for 19 days. Colony-forming assays were used to analyze the formation of various cell colonies. The expression of Sca-1, CD146, VEGFR2, CD95, pStat3, pStat5, and Bcl-xL in marrow cells were detected by flow cytometry.


RESULTS
Long-term leukemic bone marrow culture showed abnormal elongated stromal fibroblasts with almost absence of normal hematopoietic cells. Adherent cell colonies were increased, but CFU-F and other hematopoietic cell colonies were significantly decreased in leukemia group (P<0.001). Primitive progenitor-specific Sca-1 receptor expression was decreased with subsequent increased expression of CD146 and VEGFR-2 in leukemic bone marrow cells. Decreased Fas antigen expression with increased intracellular pStat3, pStat5 and Bcl-xL proteins were observed in leukemic bone marrow cells.


CONCLUSIONS
Stromal microenvironment shows altered morphology and decreased maturation in leukemia. Effective progenitor cells are decreased in leukemia with increased leukemia-specific cell population. Leukemic microenvironment plays a role in promoting and maintaining the leukemic cell proliferation and survivability in long term.
Department of Biochemistry and Medical Biotechnology, Stem Cell Research and Application Unit, Calcutta School of Tropical Medicine, Calcutta, India.
Pratima
P
Basak
Sumanta
S
Chatterjee
Prosun
P
Das
Madhurima
M
Das
Jacintha Archana
JA
Pereira
Ranjan Kumar
RK
Dutta
Malay
M
Chaklader
Samaresh
S
Chaudhuri
Sujata
S
Law
D000818:Animals; D000950:Antigens, Ly / Q000378:metabolism; D001854:Bone Marrow Cells / Q000378:metabolism / Q000473:pathology*; D051929:CD146 Antigen / Q000378:metabolism; D002452:Cell Count; D002478:Cells, Cultured; D003114:Colony-Forming Units Assay; D015672:Erythroid Precursor Cells / Q000378:metabolism / Q000473:pathology; D005038:Ethylnitrosourea; D005260:Female; D005347:Fibroblasts / Q000378:metabolism / Q000473:pathology; D055014:Granulocyte-Macrophage Progenitor Cells / Q000378:metabolism / Q000473:pathology; D006098:Granulocytes / Q000378:metabolism / Q000473:pathology; D006410:Hematopoiesis; D006412:Hematopoietic Stem Cells / Q000378:metabolism / Q000473:pathology*; D007938:Leukemia / Q000139:chemically induced / Q000378:metabolism / Q000473:pathology*; D008297:Male; D008565:Membrane Proteins / Q000378:metabolism; D051379:Mice; D023461:Myeloid Progenitor Cells / Q000378:metabolism / Q000473:pathology; D010641:Phenotype; D050796:STAT3 Transcription Factor / Q000378:metabolism; D050799:STAT5 Transcription Factor / Q000378:metabolism; D059016:Tumor Microenvironment / Q000502:physiology*; D040301:Vascular Endothelial Growth Factor Receptor-2 / Q000378:metabolism; D051020:bcl-X Protein / Q000378:metabolism; D019014:fas Receptor / Q000378:metabolism
D000950:Antigens, Ly; C494812:Bcl2l1 protein, mouse; D051929:CD146 Antigen; C074650:Ly6a protein, mouse; D008565:Membrane Proteins; D050796:STAT3 Transcription Factor; D050799:STAT5 Transcription Factor; C494087:Stat3 protein, mouse; D051020:bcl-X Protein; D019014:fas Receptor; D040301:Vascular Endothelial Growth Factor Receptor-2; D005038:Ethylnitrosourea