Side population cells from HXO-Rb44 retinoblastoma cell line have cancer-initiating property

AIM: To ascertain whether side population (SP) cells in HXO-Rb44 retinoblastom a cell line have cancer stem cell-like property in vitro and in vivo. METHODS: We analyzed and sorted SP from HXO-Rb44 retinoblastom a cell line by Hoechst 33342 staining on flow cytometry. SP and NSP cells were determ ined their ability of proliferation and self-renewal by SP reanalysis, soft agar assay and tum or sphere assay in vitro. Clone form ation was detected by seeding HXO-Rb44 and HXO-Rb44-RFP cells into soft agar. The expression of ABCG2, MDRI, Bmi-1 and Oct-4 was determined by RT-PCR between SP and non-SP (NSP) cells. Moreover, they were injected into nude mice to determine their tumorigency in vivo. RESULTS: SP from HXO-Rb44 retinoblastom a cell line could grow clonally in soft agarassays and form tumor spheres from single cells in conditioned media. The expressions of ABCG2, MDRI, Bmi-1 and Oct-4 were significantly higher in SP than NSP cells. As few as SP cells resulted in tumor formation in 6 of 12 injected sites, however, the injection of NSP cells failed to form new tumor. CONCLUSION: SP cells isolated by Hoechst 33342 from the HXO-Rb44 retinoblastom a cell line had property of high tum origency in vivo and in vitro. Therefore, SP might be a target while developing retinoblastom a therapies. Copyright International Journal of Ophthalmology Press.