Autocrine GM-CSF transcription in the leukemic progenitor cell line KG1a is mediated by the transcription factor ETS1 and is negatively regulated through SECTM1 mediated ligation of CD7

作者：Bade Doeding Christina; Goettmann Wiebke; Baigger Anja; Farren Matthew; Lee Kelvin P; Blasczyk Rainer; Huyton Trevor^*

来源：Biochimica et Biophysica Acta-General Subjects, 2014, 1840(3): 1004-1013.

DOI：10.1016/j.bbagen.2013.10.043

• CD7
• SECTM1
• GM-CSF
• ETS1
• Hematopoietic progenitors
• Acute myeloid leukemia

Background: CD7 expression is found on similar to 30% of acute myeloblastic leukemias (AML). The leukemic progenitor cell line KG1a (CD7+) constitutively expresses GM-CSF while the parental KG1 (CD7-) cell line does not. This study focuses on the molecular basis of CD7 mediated GM-CSF regulation. %26lt;br%26gt;Methods: KG1a cells were treated with recombinant SECTM1-Fc protein, the PI3K kinase inhibitors wortmannin, LY292004, or PI4K activator spermine. Stable KG1-CD7+, KG1a-shCD7, KG1a-shETS1 as well as KG1a-GFP, KG1a-PKC beta II-GFP cell lines were generated and the levels of CD7, GM-CSF and ETS-1 mRNA and protein were compared by real-time-PCR, western blotting, flow cytometry and ELISA. %26lt;br%26gt;Results: SECTM1 is expressed in Human Bone Marrow Endothelial Cells (HBMEC) and its expression can be up-regulated by both IFN-gamma. KG1 a cells demonstrated high expression levels of CD7 and ETS-1 allowing a constitutative signaling through the PI3K/Atk pathway to promote GM-CSF expression, while KG1 cells with low expression of CD7 and ETS-1 showed low GM-CSF expression. On KG1a cells GM-CSF expression could be negatively regulated by PI3K inhibitors or by recombinant SECTM1-Fc. Overexpression of CD7 in KG1 cells was insufficient to promote GM-CSF expression, while silencing of CD7 or ETS-1 resulted in reduced GM-CSF expression levels. Differentiation capable KG1a cells overexpressing PKC beta II illustrated complete loss of CD7, but maintained normal levels of both ETS-1 and GM-CSF expression. %26lt;br%26gt;Conclusion: These findings add an additional layer to the previously described autocrine/paracrine signaling between leukemic progenitor cells and the bone marrow microenvironment and highlight a role for SECTM1 in both normal and malignant hematopoiesis. %26lt;br%26gt;General Significance: This work shows that SECTM1 secreted from bone marrow stromal cells may interact with CD7 to influence GM-CSF expression in leukemic cells.

• 出版日期2014-3