Dicer1 Downregulation Induced Autophagy Mediates Cisplatin Chemoresistance Of Ovarian Carcinoma Cell C13K

【Objectives】 The RNASE III endonuclease Dicer1 mainly locating in the cell cytoplasm is one of the key enzymes of micro RNA biogenesis. In the study of ovarian tumors, ovarian cancer patients with Dicer1 gene abnormal regulation have been suggested to be poor of prognostic value in ovarian cancers. But, so far, little is known about the influence of Dicer1 expression in ovarian cancer cell on the biological characteristics of ovarian cancer and chemotherapy drug resistance. Therefore, the main aims of our study were to investigate down-regulation of Dicer1 can induce autophagy involving chemoresistance in ovarian cancer cell C13 K.【Methods】 The methods of this experience as follows:(One) the effects of reduced Dicer1 expression in ovarian cancer cells(C13K) on cisplatin(c DDP) sensitivity were measured by CCK8 in ovarian cancer cells.(Two) Downregulation of Dicer1 expression in C13 K was performed through transfection of Dicer1-si RNA. Western blot was used to detect expression of Dicer1 and autophagy related protein in ovarian cancer cell line C13 K with downregulation Dicer1.(Three) By electron microscopy and confocal laser scanning microscope, we observed autophagy with Dicer1 downregulation in ovarian cancer cell.(Four) After transfection of Dicer1 small interfering(si) RNA and autophagy-related protein 5-si(ATG5-si), the effect on cisplatin-induced apoptosis was evaluated via flow cytometry.(Five) We observed Dicer1 and autophagy expression levels in ovarian cancer samples through TCGA data.【Results】 According to the above experimental data and phenomena can get the following results:(One) By CCK8, we could find that downregulation Dicer1 in ovarian cancer cell C13 K was more resistant to cisplatin.(Two) si RNA and Western blot found that after downregulation expression level of Dicer1 in ovarian cancer cell(C13K), apoptosis related protein such as Caspase3, c-PARP were lower.(Three)Knockdown of cytoplasmic Dicer1 gene by Dicer1 si RNA transfection in C13 K Notably increased the number of autophagic vesicles by ultrastructural electron microscopy and confocal laser scanning microscope.(Four)TCGA data analysis shown expression level of cytoplasmic Dicer1 in ovarian cancer species was positively related with the response to cisplatin based therapy, while ATG5 contrary.(Five)Downregulation expression of Dicer1 mediated cisplatin resistance was reversed through inhibition of autophagy. Downregulation level of ATG5 significantly increased cisplatin-induced apoptosis.【Conclusions】 Based on above experimental data, we can conclude that downregulation of Dicer1 expression induced autophagy was involved cisplatin chemoresistance and this may be novel potential therapeutic target for ovarian tumors that are refractory to conventional treatment.