Abstract:

Objective To discuss the correlation between Akt activity and the chemosensitivity of retinoblastoma SO-Rb50 cells to carboplatin. Design Experimental study. Participants SO-Rb50 cell line. Methods Cytotoxicity of carboplatin was determined using a standard colorimetric cell counting kit-8(CCK-8) assay. Western Blot was used to detect the changes of Akt, p-Akt, caspase 3, bax, p21 expression with drug treatments. Flow cytometer was used to examine the cell cycle distribution before and after drug treatments. Main Outcome Measures IC50 values，expression of proteins，cell percentage of each phase of cell cycle. Results IC50 value of carboplatin on SO-Rb50 cells was （30.1±5.9）mg/L. Preincubating cells with LY294002 to inhibit Akt activity, IC50 values to carboplatin were lowered to （16.3±0.83）mg/L for 5μM and （8.64±0.11）mg/L for 10 μM LY294002. Treated with Carboplatin or LY294002 alone or their combinations for 48 hours, p-Akt expressions of cells were all reduced. caspase-3, bax expressions were all increased and p21 expressions were increased only with carboplatin treatment. The percentage of each cell phase did not change much due to the application of LY294002 alone, while the exposure to carboplatin caused a significant accumulation of cells in G2/M phase [from (0.34±0.34)% to (43.62±11.01)%] with a concomitant reduction in G0/G1 phase [from (57.89±2.16)% to (12.11±2.87)%], and the additive combination with LY294002 did not further alter the cell percentage of each cell phase. Conclusion Inhibition of Akt activity can increase the sensitivity of SO-Rb50 cells to carboplatin and Akt may be a target for reducing drug resistance that improves the treatment for retinoblastoma.

Key words: retinoblastoma/drug therapy, Carboplatin, Akt