Na+,K+-ATPase inhibitor induces cell cycle arrest in liver cancer HepG2 cells by regulating expression of DNA damage Mre11/Rad50/Nbs1 complex / 中国药理学通报

ABSTRACT

Aim To explore the relationship between Mre11/Rad50/Nbs1 ( MRN ) complex focus formation and DNA double-strand breaks( DSBs) caused by cinob-ufagin in human hepatocellular carcinoma HepG2 cells. Methods The Na+,K+-ATPaseα1 subunit expression level in liver cancer tissues was detected by immunohis-tochemistry. After HepG2 cells were treated with 5μmol·L-1 cinobufagin for 6, 12 and 24 h, the drug-in-duced DSBs were assessed by single cell gel electro-phroesis ( SCGE ) , the gene transcription and protein levels of Mrel1, Nbs1, Rad50 and p53 were evaluated by Real time-PCR and Western blot. The cell cycle in parallel was analyzed by flow cytometry. Results The Na+, K+-ATPase α1 subunit expression level in liver cancer tissues was significantly increased compared with the tissue adjacent to carcinoma ( P <0. 05 ) . The 5μmol · L-1 cinobufagin could induce the DSBs in a time-dependent manner (P <0. 05), and it could up-regulate the gene expression levels of Mre11, Nbs1, Rad50 and p53 in HepG2 cells ( P<0. 05 ) . The pro-portions of HepG2 cells in S phase were ( 21. 32 ± 4. 21) % in the control group, and (33. 25 ± 5. 72) %, (56. 72 ± 6. 29) % and (67. 32 ± 9. 42) % in HepG2 cells treated with 5 μmol · L-1 cinobufagin for 6, 12 and 24 h, respectively. The proportions of cells in S phase in cinobufagin groups were significantly increased compared with the control group ( P<0. 05 ) . Conclu-sion Cinobufagin could induce the cell cycle arrest in liver cancer HepG2 cells by activation of Mre11/Rad50/Nbs1 Complex.