Study Of The Reversal Effect Of Octreotide-paclitaxel Conjugate On Paclitaxel Resistant Human Ovarian Cancer A2780/Taxol By P38 MAPK Pathway

Part 1 Reversal Effect of Octreotide-Paclitaxel Conjugate on the Paclitaxel Resistance in Human Ovarian Cancer Cells A2780/Taxol by p38MAPK Signaling Pathway in VitroObjective:To investigate the possible mechanism of p38MAPK signaling pathway in octreotide-paclitaxel conjugate(our laboratory pre-synthesis,patent number:ZL 20131 0232603.X)reversing the resistance of paclitaxel in human ovarian cancer cells A2780/Taxol.Methods:1)A2780/Taxol cells were divided into eight groups:①Control group:RPMI1640 complete culture medium;②OCT group:RPMI1640 with 10μg/ml OCT;③OC group:RPMI1640 with 10μg/ml OCT and 0.234μg/ml CSS;④PTX group:RPMI1640 with 8μg/ml PTX;⑤PO group:RPMI1640 with 10μg/ml OCT and 8μg/ml PTX;⑥POC group:RPMI1640 with 10μg/ml OCT and 8μg/ml PTX and 0.234μg/ml CSS;⑦P-0 group:RPMI1640 with 20μg/ml PTX-OCT;⑧P-OC group:RPMI1640 with 20μg/ml PTX-OCT and 0.234μg/ml CSS;2)The phosphorylation level of p38MAPK and the expression level of VEGF were detected in A2780/Taxol cells.Flow cytometry was used to detect the apoptosis in A2780/Taxol cells.The expression of βⅢ tubulin in A2780/Taxol cells was detected by immunohistochemistry.Results:After 24 hours of multiple drug intervention,the activity of p38MAPK signal pathway in P-O group was markedly decreased..The protein expression level of VEGF was down-regulated simultaneously.The apoptotic rate in P-O group was highest(9.65%)βⅢ tubulin density and number with lighter stain.After the treatment of P-OC,there was enhanced expression of P-p38MAPK and significant VEGF expression.The apoptotic rate decreased(3.95%)and βⅢ tubulin particle density and number increased with deepened dye..Conclusions:Octreotide-paclitaxel conjugate can reverse the paclitaxel resistance of A2780/Taxol cells by inhibiting the activity of p38MAPK signaling pathway.Part 2 Reversal Effect of Octreotide-Paclitaxel Conjugate on the Paclitaxel Resistance in Human Ovarian Cancer Cells A2780/Taxol by p38MAPK Signaling Pathway in Nude Mice ExperimentObjective:To investigate the effect of p38MAPK signaling pathway in octreotide-paclitaxel conjugate reversing the resistance of paclitaxel in human ovarian cancer cells A2780/Taxol in nude mice.Methods:(1)A2780/Taxol cells were inoculated into the right armpit of nude mice by subcutaneous injection of 2×106 cells.80 nude mice were randomly allocated into 8 groups.(2)Nude mice were treated with different drugs through tail vein simultaneously one time for three weeks:①Control group:only saline 0.1ml;②OCT group:150nmol/kg OCT 0.1ml;③OC group:150nmol/kg + CSS 1.282nmol/kg 0.1ml;④PTX group:150nmol/kg PTX 0.1ml;⑤PO group:150 nmol/kg OCT +PTX 150 nmol/kg;⑥POC group:150 nmol/kg OCT + PTX 150 nmol/Kg + CSS 1.282nmol/kg 0.1ml;⑦P-0 group:150 nmol/kg P-O;⑧P-OC group:150 nmol/kg octreotide-paclitaxel + CSS 1.282nmol/kg 0.1ml.Nude mice were sacrificed at the beginning on the fourth week.(3)The phosphorylation level of p38MAPK and the expression level of VEGF was detected in nude mice A2780/Taxol cells.Flow cytometry was used to detect the apoptosis A2780/Taxol in nude mice and immunohistochemistry was used to detect the expression of βⅢ tubulin in nude mice.Results:All of the nude mice inoculated with A2780/Taxol cells showed tumorigenicity after one week with the average diameter of tumor was 0.8cm.Side effects such as nausea,sluggishness,diarrhea and tumor ulceration were not observed in all groups.P-O group had the most significant tumor volume reduction,mean volume was 0.73cm3(P<0.05compared with other experimental groups).The activity of p38MAPK signal pathway in P-O group was the lowest.There was a simultaneous down regulation of the protein expression level of VEGF.The highest apoptotic rate in P-O group was observed(10.56%).βⅢ tubulin density,number decreased with lighter staining Post P-OC intervention showed a significant volume increase of transplanted tumor,average volume was 1.65cm3,compared with other experimental groups P<0.05.The expression of P-p38MAPK was increased so as to the expression of VEGF.The rate of apoptosis decreased(5.05%)and βⅢ tubulin particle density and number increased with deepened dyeing.Conclusions:Octreotide-paclitaxel conjugate inhibits p38MAPK signaling pathway and reverse the paclitaxel resistance in human ovarian cancer A2780/Taxol in nude mice.