ABSTRACT
Aim To set up leukemic K562/ADM cells with stable tolerance to 15 fimol • L_1 ADM induced in vitro by long-term and continuous stepwise increment of adriamycin (ADM) concentration, to observe the sensitivity to other chemotherapy drugs and the relationship between autophagy and drug resistance.Methods MTT assay was used to detect the sensitivity of cells to chemotherapy drugs.The morphological changes of autophagy were observed by transmission electron microscope and fluorescence microscopy.Cell apoptosis analysis was performed using Annexin-V/PI double staining and flow cytometry ( FCM ).The expressions of autophagy and drug resistance associated proteins were tested by Western blot.Results K562/ADM cells were cross-resistance to the other chemotherapeu-tics besides adriamyciri, such as pirarubicin, daunoru- bicin, 5-flurouracil, vincristine but not arsenic triox- ide.The number of autophagosomes, the fluorescence intensity of monodansylcadaverine (MDC) and the expression of LC3-H ,Beclin-l in K562/ADM cells were significantly higher than those in K562 cells.The inhibition of autophagy by 3-MA significantly increased the sensitivity of K562/ADM cells to ADM, and 3-MA also effectively inhibited the expressions of drug resistance related proteins P-gp, MRP1 and BCRP in K562/ADM cells.Conclusions The K562/ADM cells resistant to adriamycin occur multidrug resistance, and the drug resistanceis closely related to the level of autophagy.
ABSTRACT
The present study was conducted to investigate the effects of gossypol acetic acid (GAA) on the proliferation of human mucoepidermoid carcinoma cell line MEC-1 in vitro and its possible molecular mechanisms of DNA double-strand breaks (DSB). MTT assay was performed to test the inhibition of proliferation of MEC-1 cells by GAA. DSB and γH2AX foci formation induced by GAA were detected by neutral comet assay and immunostaining. GAA (5-40 μmol/L) inhibited the growth of MEC-1 cells in a dose- and time-dependent manner. One of the indexes of comet assay, percentage of head DNA was decreased, however other indexes, including tail length, percentage of tail DNA, tail moment (TM) and Olive tail moment (OTM) were increased when treated with 2.5- 40 μmol/L GAA for 24 h or 20 μmol/L GAA for 3-48 h, compared with those in control. The percentage of γH2AX-positive cells was also increased when MEC-1 was treated with 2.5-20 μmol/L GAA for 24 h or 20 μmol/L GAA for 3-48 h, compared with that in control. All these results show that GAA inhibits the proliferation of MEC-1, and DSB maybe one of the mechanisms of inhibitory effect of GAA on the growth of tumor cells.