Objective        To investigate the effect and conceivable mechanism of 2-methoxyestradiol (2-MeOE2) on the proliferation

migration and radiosensitivity of nasopharyngeal carcinoma (NPC) CNE-2 stem cells in vitro. Methods        Pre-identified and collected NPC CNE-2 stem cells from our group were used for this study. Nasopharyngeal carcinoma stem cells (NPCSCs) were treated by 2-MeOE2 at different concentrations (0

4 and 8 μmol/L). After the treatment

the cells were further irradiated by X-rays at the doses of 0

2

4 and 8 Gy. Total proteins were extracted in 0

24 and 48 h after the cells treated by 2-MeOE2 (4 μmol/L). Western blotting and colony formation assay were used to detect protein expression of HIF-1α and NF-κB p65 and radiosensitivity of CNE-2 and NPCSC. CCK-8 assay and transwell assay were used to measure the proliferation and migration of NPCSC. Results        Western blot results showed that HIF-1α and NF-κB p65 were increasingly expressed in the NPCSCs compared with the parental CNE-2 cells (P0.01). Radiation-related parameters D0

Dq

N and SF2 had higher values in

NPCSCs than in CNE-2 cells. After treatment

the proliferation and migration capabilities of NPCSCs were decreased significantly along with increased 2-MeOE2 concentration (P0.01). 2-MeOE2 treatment also increased radiosensitivity in NPCSCs

showing  sensitivity enhancment ratio (SER) values of 1.19 and 1.39 at 4 and 8 μmol/L of 2-MeOE2

respectively. Moreover

the protein expression of HIF-1α and NF-κB p65 was decreased significantly along increased concentration and delayed harvested time

suggesting their expression patterns were concentration- and time-dependent (P0.01). Conclusion      Compared with CNE-2 cells

NPCSCs have higher protein expression of HIF-1α and NF-κB p65

and are resist to radiotherapy. 2-MeOE2 could effectively reduce the proliferation and migration

and sensitize the radioresistance to NPC CNE-2 stem cells

which  might mechanistically relate to 2-MeOE2 inhibition of expression of HIF-1α and NF-κB p65.