Effect Of Curcumin On Proliferation Of Doxorubicin-resistant Human Anaplastic Thyroid Carcinoma Cell Line HTh74Rdox And Its Mechanism

Objectives:To investigate the effect and possible mechanism of curcumin on proliferation of doxorubicin-resistant thyroid anaplastic carcinoma(ATC)cell line HTh74Rdox.Methods:Thyroid anaplastic carcinoma cell line HTh74 and its doxorubicin-resistant cell line HTh74Rdox were treated with various concentrations of doxorubicin for 48h.The cell viability was determined by MTT method,then IC50(half inhibitory concentration)of these two cell lines and resistance index of HTh74Rdox cells were calculated.HTh74 and HTh74Rdox cells were treated with various concentrations of curcumin,then the morphological changes of cells were observed by inverted microscope and the cell viability was measured by MTT assay.The expression of cleaved-caspase-3,p-AMPK?(Thrl72),p-mTOR,p-S6K and p-Akt in HTh74Rdox cells was detected by western blot after curcumin treatment.HTh74 and HTh74Rdox cells were treated with various concentrations of curcumin and doxorubicin for 24h,then MTT method was determined.The expression of octamer-binding transcription factor 4(OCT4),ATP binding cassette subfamily G member 2(ABCG2),Multidrug resistance 1(MDR1)and multidrug resistance-associated protein 1(MRP1)genes in HTh74Rdox cell were detected by qPCR after curcumin treatment.Results:The IC50 of doxorubicin to HTh74 cells was 148.77±17.47 ng/ml,while that of HTh74Rdox cells was up to 2011±109.42 ng/ml.The resistance index of HTh74Rdox cells to doxorubicin was 13.59±0.98.After treated by various concentrations of curcumin,the morphological of HTh74 and HTh74Rdox cells changed significantly,and the cell viability of both cell lines were significantly inhibited.Moreover,HTh74Rdox cells were more sensitive to curcumin.The expression of p-mTOR,p-S6K and p-Akt was significantly inhibited.The expressions of p-mTOR,p-S6K and p-Akt were significantly inhibited and p-AMPK?(Thr172),cleaved-caspase-3 was significantly activated after 6-hour incubation with curcumin in a dose-dependent manner.The activity of two cells treated with curcumin combined with doxorubicin was significantly lower than those treated with doxorubicin alone.The expression of ABCG2,OCT4,MDR1 and MRP1 decreased significantly in HTh74Rdox cells treated by different concentrations of curcumin in a dose-dependent manner.Conclusions:Doxorubicin-resistant HTh74Rdox cells are more sensitive to curcumin than HTh74 cells,probably because curcumin significantly inhibited expression of related proteins of mTOR signaling pathway protein expression in HTh74Rdox cells.Curcumin can suppress the expression of stem cell markers and drug-resistant genes in HTh74Rdox cells,thus enhancing the inhibitory effect of doxorubicin on HTh74Rdox cells.