Bone marrow NG2+/Nestin+ mesenchymal stem cells drive DTC dormancy via TGF-β2

Menée une vitro et à l'aide de modèles murins, cette étude met en évidence un mécanisme par lequel les cellules souches mésenchymateuses exprimant la nestine et le protéoglycane NG2 favorisent, via le facteur de croissance TGF-bêta2, la dormance des cellules cancéreuses mammaires disséminées dans la moelle osseuse

Résumé en anglais

In the bone marrow (BM) microenvironment, where breast cancer (BC)-disseminated tumor cells (DTCs) can remain dormant for decades, NG2+/Nestin+ mesenchymal stem cells (MSCs) promote hematopoietic stem cell quiescence. Here we reveal that periarteriolar BM-resident NG2+/Nestin+ MSCs can also instruct BC DTCs to enter dormancy. NG2+/Nestin+ MSCs produce transforming growth factor (TGF)-β2 and bone morphogenetic protein (BMP)7 and activate a quiescence pathway dependent on TGFBRIII and BMPRII, which via p38-kinase, results in p27 induction. Genetic depletion of MSCs or conditional knockout of TGF-β2 in MSCs using an NG2-CreER driver led to bone metastatic outgrowth of otherwise dormant p27+/Ki67− DTCs. Also, patients with estrogen receptor-positive BC without systemic recurrence displayed higher frequency of TGF-β2 and BMP7 detection in the BM. Our results provide direct proof that hematopoietic stem cell dormancy niches control BC DTC dormancy and suggest that aging or extrinsic factors that affect the NG2+/Nestin+ MSC niche homeostasis may result in a break from dormancy and BC bone relapse.