Reversal of multidrug resistance in drug-resistant human gastric cancer cell line SGC7901/VCR by antiprogestin drug mifepristone

Abstract

AIM:To explore the reversal effect of mifepristone on multidrug resistance (MDR) in drug-resistant human gastric cancer cell line SGC7901/VCR and its mechanisms. METHODS:Expression of multidrug resistance-associated protein(MRP) was detected using reverse transcriptionpolymerase chain reaction(RT-PCR). Flow cytometry was used to assay the expression of P-glycoprotein(P-gp), Bcl-2, Bax, and the mean fluorescent intensity of intracellular rhodamine 123 in the cells. Meanwhile, the protein levels of Bcl-2 and Bax were also detected by Western blotting analysis. The sensitivity of cells to the anticancer agent, vincrimycin(VCR), and the intracellular [ 3 H]VCR accumulation were determined by tetrazolium blue (MTT) assay and a liquid scintillation counter, respectively. RESULTS:Expression of MRP and P-gp in SGC7901/VCR cells was 6.04-and 8.37-fold higher as compared with its parental SGC7901 cells, respectively. After treatment with 1, 5, 10, and 20 µmol/L mifepristone, SGC7901/VCR cells showed a 1.34-, 2.29-, 3.11-, and 3.71-fold increase in the accumulation of intracellular VCR, a known substrate of MRP, and a 1.03-, 2.04-, 3.08-, and 3.68-fold increase in the retention of rhodamine 123, an indicator of P-gp function, respectively. MTT assay revealed that the resistance of SGC7901/VCR cells to VCR was 11.96-fold higher than that of its parental cells. The chemosensitivity of SGC7901/VCR cells to VCR was enhanced by 1.02-, 7.19-, 12.84-, and 21.17-fold after treatment with mifepristone at above-mentioned dose. After 96 h of incubation with mifepristone 10 µmol/L, a concentration close to plasma concentrations achievable in human, the expression of Bcl-2 protein was decreased to (9.21±0.65)% from (25.32±1.44)%, whereas the expression of Bax protein was increased to (19.69±1.13)% from (1.24±0.78)% (P<0.01). Additionally, the effects of mifepristone on the expression of Bcl-2 and Bax proteins in SGC7901/VCR cells were further demonstrated by Western blotting analysis. CONCLUSION:Mifepristone has potent reversal effect on MDR in SGC7901/VCR via inhibiting the function of MRP and P-gp, modulating the expression of Bcl-2 and Bax proteins, and enhancing the sensitivity to anticancer agent VCR.Li DQ, Wang ZB, Bai J, Zhao J, Wang Y, Hu K, Du YH. Reversal of multidrug resistance in drug-resistant human gastric cancer cell line SGC7901/VCR by antiprogestin drug mifepristone.

Small‐molecule inhibitors of multidrug resistance‐associated protein 1 and related processes: A historic approach and recent advances

“…Using human gastric cancer cells (SGC7901/VCR) overexpressing MRP1 and P‐gp simultaneously, Li et al. observed similar effects . Mifepristone up to 20 μM led to [ 3 H]vincristine accumulation to the level of the parental cell line SGC7901, and sensitized the resistant cell line completely with respect to this antineoplastic drug.…”

“…In the previous two sections, many substrates of MRP1 have already been described, such as LTC 4 , or GSH . Besides, some inhibitors got attention since they have been widely used as standard inhibitors of this transporter, such as MK571, or BSO .…”

Reversal of multidrug resistance in vincristine-resistant human gastric cancer cell line SGC7901/VCR by LY980503

“…SGC7901/VCR is an established VCR-resistant cell sub-line selected by stepwise exposure of parental SGC7901 cells to increasing concentrations of VCR. Several reports have proved that the VCR-resistant SGC7901/VCR cells possess the characteristics of MDR with over-expression of Pgp [7][8][9][10][11][12] . The SGC7901/VCR cell line has been successfully used as an in vitro MDR reversal model by several study groups [10][11][12] .…”

The fight for a life‐saving drug: a personal perspective

“…Interestingly, in addition to the medical uses mentioned earlier, recent developments in overseas research indicate that mifepristone has potential use in some gastric cancers as well, 14,15 and it also has viability for use as a helper-dependent adenovirus vector in gene therapy for cancer treatments. 16 The more research I did, the more fascinated by this drug I became.…”