The In Vitro Effect Of Novel Chemotherapeutics On Retinoblastoma

Purpose:1,To investigate the role of cancer stem cells in retinoblastoma chemoresistance.2,To identify novel active drugs with higher efficacy and to develop better chemotherapeutics.Methods:We have established a new continuous cell line named FD-RB, and demonstrated its characteristics as tumor stem-like cells in our previous work. Y79 is another cell line chosen in this study. Using Cell Counting Kit-8, we tested the in vitro efficacy of novel chemotherapeutics (including a topoisomerase I inhibitor named Topotecan and a glycolytic inhibitor named 2-deoxy-D-glucose) to both Y79 and FD-RB. The efficacy of tradition chemotherapeutics (including carboplatin and vincristine) is used as matched control. Cell viabilities of Y79 and FD-RB under every concentration was analysed by t-test. Then we compared the 50% inhibiting concentration of each drug. After selecting the most effective drug in vitro, we tested the efficacy of topotecan combined with DG-2 and of DG-2 combined with carboplatin for the treatment of Y79 and FD-RB, and assessed the cell viabilities under different drug combination. The effect of combination chemotherapeutics is compared with the effect of single chemotherapeutics. Then we investigated the interaction between these combined agents.Results:The drug tolerance of FD-RB in vitro is inferior to that of Y79, the difference has statistics significance (P<0.05); Among four tested drugs, topotecan has a good cell-killing effect second only to vincristine, its IC50 Y79 is about 6.52umol/L,and its IC50 ED-RB is about 0.026umol/L. DG-2 can effectively kill both Y79 and FD-RB even under normoxia. Combined topotecan and DG-2 may attenuate their efficacy. No interaction between DG-2 and Carboplatin was determined. The combined effect of this two agents is simply accumulated.Conclusion:Cancer stem cells may not be the only reason that leads to chemoresistance and treatment failure. The resistance of CSCs can also be affected by many aspects. Topotecan has good cell-killing effect to both Y79 and FD-RB in vitro, and it has a potential value in treating recurrent or metastasis Rb. DG-2 can inhibit the growth of Y79 and FD-RB in vitro even under normoxia condition, while it can also reduce the hypoxia-related chemoresistance. So it may have a good prospect in Rb treatment. The efficacy of topotecan combined with DG-2 in vivo must be further confirmed.