Role of Chk1 in the differentiation program of hematopoietic stem cells
Hematopoietic stem cells (HSC) isolated from umbilical cord blood (UCB) were treated with ionizing radiation (IR) and sensitivity and IR induced checkpoints activation were investigated. No difference in the sensitivity and in the activation of DNA damage pathways was observed between CD133+ HSC and cells derived from them after ex vivo expansion. Chk1 protein was very low in freshly isolated CD133+ cells, and undetectable in ex vivo expanded UCB CD133+ cells. Chk1 was expressed only on day 3 of the ex vivo expansion. This pattern of Chk1 expression was corroborated in CD133+ cells isolated from peripheral blood apheresis collected from an healthy donor. Treatment with a specific Chk1 inhibitor resulted in a strong reduction in the percentage of myeloid precursors (CD33+) and an increase in the percentage of lymphoid precursors (CD38+) compared to untreated cells, suggesting a possible role for Chk1 in the differentiation program of UCB CD133+ HSC.
KeywordsStem and progenitor cells Umbilical cord blood Chk1 DNA damage Differentiation
We thank Dr Patrick Casara and Dr John Hickman who respectively synthesized and kindly provided the Chk1 inhibitor compound. A special thank to JD Baggott that kindly edited the paper. This study was supported by grants from “Fondazione I1 Sangue”, Ministero della Salute, Istituto Superiore di Sanità, Sixth FP “Thercord”, Foundation Novussanguis and Jérome Lejeune. The generous contribution of the Italian Association for Cancer Research and of FIRB is also gratefully acknowledged.
- 8.Gluckman E, Broxmeyer HA, Auerbach AD, Friedman HS, Douglas GW, Devergie A, Esperou H, Thierry D, Socie G, Lehn P (1989) Hematopoietic reconstitution in a patient with Fanconi’s anemia by means of umbilical-cord blood from an HLA-identical sibling. N Engl J Med 321:1174–1178PubMedCrossRefGoogle Scholar
- 11.Lazzari L, Lucchi S, Rebulla P, Porretti L, Puglisi G, Lecchi L, Sirchia G (2001) Long-term expansion and maintenance of cord blood haematopoietic stem cells using thrombopoietin, Flt3-ligand, interleukin (IL)-6 and IL-11 in a serum-free and stroma-free culture system. Br J Haematol 112:397–404CrossRefPubMedGoogle Scholar
- 12.De Felice L, Di Pucchio T, Mascolo MG, Agostini F, Breccia M, Guglielmi C, Ricciardi MR, Tafuri A, Screnci M, Mandelli F, Arcese W (1999) Flt3LP3nduces the ex-vivo amplification of umbilical cord blood committed progenitors and early stem cells in short-term cultures. Br J Haematol 106:133–141CrossRefPubMedGoogle Scholar
- 20.Tse AN, Rendahl KG, Sheikh T, Cheema H, Aardalen K, Embry M, Ma S, Moler EJ, Ni ZJ, Lopes de Menezes DE, Hibner B, Gesner TG, Schwartz GK (2007) CHIR-124, a novel potent inhibitor of Chk1, potentiates the cytotoxicity of topoisomerase I poisons in vitro and in vivo. Clin Cancer Res 13:591–602CrossRefPubMedGoogle Scholar
- 21.Zabludoff SD, Deng C, Grondine MR, Sheehy AM, Ashwell S, Caleb BL, Green S, Haye HR, Horn CL, Janetka JW, Liu D, Mouchet E, Ready S, Rosenthal JL, Queva C, Schwartz GK, Taylor KJ, Tse AN, Walker GE, White AM (2008) AZD7762, a novel checkpoint kinase inhibitor, drives checkpoint abrogation and potentiates DNA-targeted therapies. Mol Cancer Ther 7:2955–2966CrossRefPubMedGoogle Scholar
- 28.Pierelli L, Scambia G, Fattorossi A, Bonanno G, Battaglia A, Rumi C, Marone M, Mozzetti S, Rutella S, Menichella G, Romeo V, Mancuso S, Leone G (1998) Functional, phenotypic and molecular characterization of cytokine low-responding circulating CD34+ haemopoietic progenitors. Br J Haematol 102:1139–1150CrossRefPubMedGoogle Scholar