Genistein-induced differentiation of breast cancer stem/progenitor cells through a paracrine mechanism.

It is believed that breast cancer stem cells (BCSCs), like normal stem cell counterparts, have the capacity of self-renewal and differentiation. Simultaneously, estrogen receptor (ER)-negative (-) BCSCs are affected by surrounding differentiated ER-positive (+) tumor cells by virtue of paracrine signaling within the tumor micro-environment. Genistein (GEN), as a sort of phytoestrogen, can act on ER+ breast cancer cells but the role of GEN in the differentiation of neighboring ER- BCSCs has not been defined. Transwell co-culture system was utilized so as to elaborate the interaction between well-differentiated ER+ breast cancer cells (MCF-7) and ER- breast cancer stem/progenitor cells (mammospheres derived from MDA-MB-231 cells). GEN-induced differentiation of BCSCs was analyzed by mammospheres formation assay, flow cytometry and RT-PCR after a 3 day solo-culture or co-culture. We find that GEN sized 2 µM, and 40 nM, effectively promotes morphological alteration of mammospheres, reduces the ratio of subset of CD44+/CD24-/ESA+ cells and upregulates the expression of differentiated cell markers of mammospheres in co-culture system, but not in solo-culture condition. Besides, we demonstrate that the differentiation-inducing effect of GEN on mammospheres is associated with PI3K/Akt and MEK/ERK signaling pathways which are activated by amphiregulin released from ER+ cancer cells. These results indicate that GEN was able to induce the differentiation of breast cancer stem/progenitor cells through interaction with ER+ cancer cells by a paracrine mechanism.

[Combined use of autologous micro-morselized bone with bone morphogenetic protein and type I collagen graft in repairing rabbit bone defects].

OBJECTIVE: To study the effect of combined use of autologous micro-morselized bone with bone morphogenetic protein(BMP) and type I collagen graft on the treatment of segmental bone defects. METHODS: The bulk bone of rabbit iliac crest was ground into micro-morselized bone, which was combined with BMP and type I collagen. The model of 1.5 cm bone defect was established in the middle shaft of the radius. Fifty-six rabbits were assigned to four repairing methods: autologous micro-morselized bone graft with BMP and type I collagen, autologous micro-morselized bone graft with type I collagen, autologous micro-morselized bone graft alone, and control group. The defect-repairing capability of each group was assessed by radiographic, histological, bone densitometry and biomechanical studies. RESULTS: X-ray manifested that at the end of 8 weeks after operation, the bone defect treated with autologous micro-morselized bone graft with BMP and type I collagen was repaired completely, and at the end of 12 weeks after operation the bone defect treated with autologous micro-morselized bone and type I collagen was cured completely, but the bone defect treated with autologous micro-morselized alone was completely repaired. No healing was found in the control group. In the bone densitometry detection, the material with BMP exhibited the strongest defect-repairing capability in terms of amount increased and quality of the new bone at the end of 8 weeks and 12 weeks. The group with BMP has the best mechanical strength of all groups at the end of 12 weeks. CONCLUSION: Autologous micro-morselized bone graft with BMP/type I collagen and autologous micro-morselized bone graft with type I collagen prove to be effective in repairing segmental bone defects. The autologous micro-morselized bone combined BMP and type I collagen is an excellent bone repairing material considering the satisfactory osteogenesis, osteo-conduction, and osteo-induction seen in this method.