Small interfering RNA (siRNA)-mediated silencing of the M2 subunit of ribonucleotide reductase: a novel therapeutic strategy in ovarian cancer.

Objective: To investigate the effects of small interfering RNA (siRNA)-mediated silencing of the ribonucleotide reductase M2 subunit (RRM2) on the apoptosis and the drug sensitivity of cisplatin-resistant SKOV3/DDP cells.

Methods: Small interfering RNA transfection was mediated by lipofectamine 2000 to silence RRM2 gene. Messenger RNA (mRNA), and protein expression levels of RRM2 were evaluated by real-time polymerase chain reaction and Western blot after transfection. The cell growth inhibition rate was evaluated by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide. The cellular apoptosis and cycling was identified by flow cytometry (FCM).

Results: The messenger RNA and protein expression levels of RRM2 markedly decreased after the RRM2 siRNA transfection. The half inhibition concentration of cisplatin in RRM2-RNA interference cells (interference group) was lower than that in RRM2-negative cells (noninterference group) and the SKOV3/DDP cells (blank control group) (P = 0.032). Small interfering RNA-mediated inhibition of RRM2 effectively induced G1/S-phase cell cycle arrest and increased drug (gemcitabine and cisplatin)-induced apoptotic fraction at 72 hours ( (96% ± 3.0)%) after transfection (P < 0.05).

Conclusion: Small interfering RNA-mediated RRM2 knockdown significantly reversed SKOV3/DDP cell resistance to cisplatin. RNA interference technology combined with gemcitabine and cisplatin can effectively improve the apoptosis rate of the cisplatin-resistant ovarian cancer cell, which is expected to become the first-line treatment options for the cisplatin-resistant ovarian cancer.