| Objective:To investigate whether 15-PGDH is related to multidrug resistance process of human breast cancer cell MCF-7/ADR, the effects of 15-PGDH and related mechanisms were explored by detecting the expressions of 15-PGDH, upstream gene COX-2,MDR related genes P-gp and BCRP, and the production of PGE2 in both MCF-7 and MCF-7/ADR cells.The MDR reversal effects of 15-PGDH induction drugs were observed in human breast cancer cells.These help to concern 15-PGDH as an new target of MDR reversal.Methods:Human breast cancer cell lines MCF-7 and MCF-7/ADR were used as the experiment subjects, ADM of various concentrations was added to sustain the resistance status of MCF-7/ADR,and then cell morphology were observed and resistance index was detected with MTT assay. RT-PCR, ELISA and Western blot were used to detect the expressions of 15-PGDH, COX-2 and cell supernatant PGE2 levels in both MCF-7 and MCF-7/ADR cells.The proliferation and apoptosis effects of four 15-PGDH induction drugs (indomethacin, ibuprofen, pioglitazone, dexamethasone) in both cells were detected by MTT assay and Hochest33258 stain respectively. The reversal effects of multidrug resistance to ADM and Taxol by these 15-PGDH induction drugs were detected by MTT assay in MCF-7/ADR cell.After both cells were treated with four 15-PGDH inducion drugs,the mRNA expressions of 15-PGDH, COX-2, and MDR related genes P-gp and BCRP were observed by RT-PCR, and the protein expressions of 15-PGDH and COX-2 were observed by Western blot, and the PGE2 levels in cell supernatant were examined by ELISA assay.Results:(1)After ADM was added to sustain the MDR status, the profile of MCF-7/ADR cell was more clear than before, black particles and vacuoles in cytoplasm were increased.The extent of resistance was increased, and the resistance index rose from 23.26 to 46.21.(2) 15-PGDH mRNA and protein levels in MCF-7/ADR were obviously lower than MCF-7,whereas COX-2 mRNA and protein expressions were higher than MCF-7,and PGE2 in MCF-7/ADR cell supernatant was significantly higher than MCF-7.(3)Four 15-PGDH induction drugs had various degrees of anti-proliferation effects to MCF-7 and MCF-7/ADR cells in a dose dependent manner, and had various degrees of MDR reversal effects at low-toxic dose levels(indomethacin 100μmol/L, ibuprofen 200μmol/L, pioglitazone 20μmol/L, and dexamethasone 100 nmol/L).Reversal index to ADM were 2.90,2.01,1.87 and 1.61,reversal index to Taxol were 1.67,2.0,1.28 and 1.03.The cell apoptosis induction effects of ADM and Taxol were increased markedly when combined with four drugs.(4) Compared with control group, indomethacin and ibuprofen increased 15-PGDH mRNA expression and decreased COX-2 mRNA expression in both cells.Pioglitazone could not affect 15-PGDH and COX-2 mRNA expression in MCF-7,while increased 15-PGDH mRNA expression, and dcreased COX-2 mRNA expression in MCF-7/ADR cell.Dexamethasone could not change 15-PGDH mRNA expression in MCF-7,but increased it in MCF-7/ADR and reduced COX-2 mRNA in both cells.(5)After treated with four 15-PGDH induction drugs,15-PGDH protein expression was increased in MCF-7/ADR cells, whereas ibuprofen decreased it and others could not change it in MCF-7.Indomethacin, ibuprofen and pioglitazone reduced COX-2 protein expression in both cells, and dexamethasone could only reduce COX-2 protein expression in MCF-7.(6) All four 15-PGDH induction drugs could reduce supernatant PGE2 levels in both cells, there was no significant difference between different drug groups.(7) P-gp mRNA expression in MCF-7/ADR was higher than MCF-7,BCRP mRNA expression between two cells had no significant difference; All four 15-PGDH induction drugs could reduce P-gp mRNA expression in MCF-7 except pioglitazone, only dexamethasone could reduce P-gp mRNA expression in MCF-7/ADR cell.Pioglitazone and dexamethasone could decrease BCRP mRNA expression in MCF-7/ADR, other induction drugs had no effects on P-gp and BCRP mRNA expression in both cells.Conclusions:We conclude that(1)As the same with COX-2,15-PGDH participates in the process of MDR in human breast cancer cell MCF-7/ADR via regulation of PGE2.(2) 15-PGDH induction drugs (indomethacin, ibuprofen, pioglitazone, and dexamethasone) have cell anti-proliferation and MDR reversal effects on MCF-7 and MCF-7/ADR cells, the sensitivity of chemotherapy and cell apoptosis induction effect of anticancer drugs like ADM and Taxol can be enhanced when combined with the four 15-PGDH induction drugs in MCF-7/ADR cell. Its mechanism is related to increasing 15-PGDH mRNA transcription, protein expression, and/or decreasing COX-2 mRNA transcription, protein expression in cells,and ultimately reducing PGE2 concentration in cell supernatant which is the product regulated by both 15-PGDH and COX-2, finally induce cell apoptosis.Decreasing the dowmtream MDR related genes P-gp and BCRP mRNA transcription may not be the main mechanism of resistance reversal effect of these four drugs.
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