Dysplasia of human prostate CD133^hi sub-population in NOD-SCIDS is blocked by c-myc anti-sense

BACKGROUND. The CD133^hi sub-population of prostate epithelial cells has been demonstrated to possess tumor-initiating capacity consistent with that of the cancer stem cell theory. However, the involvement of oncogenes such as c-myc has not been fully elucidated in the CD133^hi sub-population. METHODS. We have isolated primary prostate cell strains (IBC-10a) and immortalized them by transfection with hTERT. The in vitro and in vivo tumorigenic capacity of isolated CD133^hi and CD133^lo cells was evaluated with respect to c-myc expression using specific sense and antisense oligonucleotides. RESULTS. Freshly immortalized cells consisted of <3.3% CD133^hi/CD24^hi sub-population (SP). "Prostaspheres" generated from single CD133^hi cells in the presence of EGF consisted of ∼10% CD133^hi SPs in 12-21 day cultures. A single Prostasphere generated from single CD133^hi cells (6-10 cell stage at day 6 injected i.t) produced dysplastic lesions in NOD-SCID mice (n = 4/ 5). Treatment of Prostaspheres from CD133^hi SPs in vitro with c-myc or cyclin D1 anti-sense oligonucleotides totally blocked colony forming ability and growth. Furthermore, treatment of fully formed, 6-day Prostaspheres for 48 hr with c-myc anti-sense significantly reduced c-myc expression and their ability to generate lesions in NOD-SCIDs (n = 10 Prostaspheres injected i.t./mouse). CONCLUSIONS. These data demonstrate for the first time that a single CD133^hi cell is competent to generate Prostaspheres in vitro and that CD133^hi Prostaspheres require c-myc to grow and form dysplastic lesions in vivo.