通过体内外实验评估二硫键共价载紫杉醇胶束[P(PEGMEA)-co-P(PDPHEMA)-g-PTX，简称二硫键紫杉醇]对乳腺癌的抑瘤效果。

(1)用0.0001、0.001、0.01、0.1、1、10、50、100、500 μg/ml二硫键紫杉醇溶液分别处理MCF-7细胞，用MTT法检测在490 nm波长处的吸光度值(D)，并计算药物的半数抑制浓度(IC₅₀)。(2)用10 μg/ml胶束、紫杉醇及二硫键紫杉醇分别处理4种细胞系(MCF-7、MDA-MB-231、MCF-10A、U937),用MTT法检测在490 nm波长处的D值，并用流式细胞仪评估MDA-MB-231细胞凋亡情况。(3)利用MDA-MB-231细胞构建荷瘤裸鼠模型。选择荷瘤裸鼠18只，随机分为胶束组、紫杉醇组、二硫键紫杉醇组3组，每组6只，分别给药5 mg/kg；另选18只，随机分为3组，每组6只，胶束组给药16 mg/kg，紫杉醇给药5 mg/kg，二硫键紫杉醇给药16 mg/kg(载药率30.9%，含紫杉醇5 mg/kg)。分别记录肿瘤体积及重量，检测血常规，对肿瘤及重要内脏器官行病理检查。多组间比较采用单因素方差分析，两两比较采用LSD法；若数据不满足正态分布和方差齐性，用M(P₂₅～P₇₅)表示，采用非参数检验进行分析。

(1)二硫键紫杉醇对MCF-7细胞活力抑制作用呈浓度依赖关系(IC₅₀＝6.13 μg/ml)。(2)在MCF-7、MDA-MB-231、MCF-10A、U937细胞系，3组(胶束组、紫杉醇组、二硫键紫杉醇组)的D值比较，差异均有统计学意义(F＝133.152、139.673、17.364、14.900，P均<0.050)，两两比较中紫杉醇组、二硫键紫杉醇组分别与胶束组比较差异均有统计学意义(P均<0.050)，但二硫键紫杉醇组与紫杉醇组比较，差异无统计学意义(P＝0.091、0.071、0.188、0.616)。胶束组、紫杉醇组、二硫键紫杉醇组的MDA-MB-231细胞凋亡率分别为46.35%(45.20%～52.38%)、45.60%(45.03%～46.93%)、11.70%(11.00%～12.60%)，差异有统计学意义(P＝0.003)。胶束组与紫杉醇组，胶束组与二硫键紫杉醇组间比较差异均有统计学意义(P均<0.017)；紫杉醇组与二硫键紫杉醇组比较差异无统计学意义(P＝0.423)。(3)给荷瘤裸鼠注射5 mg/kg相应药物后，胶束组、紫杉醇组、二硫键紫杉醇组肿瘤体积分别为(5 465±1 105) mm³、(3 590±877) mm³、(4 125± 792) mm³，差异有统计学意义(F＝7.264，P＝0.005)，肿瘤质量分别为(6.29±1.31) g 、(3.62±1.03) g、(4.58±0.92) g，差异也有统计学意义(F＝10.167，P＝0.001)；紫杉醇组与二硫键紫杉醇组在肿瘤体积和质量方面的差异均无统计学意义(P＝0.345、0.296)。胶束组给药16 mg/kg，紫杉醇给药5 mg/kg，二硫键紫杉醇给药16 mg/kg后，裸鼠肿瘤体积分别为(3 251±679) mm³、(1 936±399) mm³、(1 637±371) mm³，差异有统计学意义(F＝16.100，P<0.001)；肿瘤质量分别为(3.02±0.48) g、(2.00±0.18) g、(2.00±0.18) g，差异也有统计学意义(F＝18.147，P<0.001)；紫杉醇组与二硫键紫杉醇组在肿瘤体积和质量方面的差异均无统计学意义(P＝0.385、1.000)。紫杉醇组裸鼠在给药2周后开始精神萎靡，活动量减少并死亡2只，其余2组裸鼠状态较好。3组裸鼠的红细胞、白细胞及血小板数量比较，差异均无统计学意义(F＝1.424、1.845、2.257，P＝0.276、0.197、0.144)。HE染色结果显示，紫杉醇组和二硫键紫杉醇组肿瘤组织内均可见广泛坏死灶。

二硫键紫杉醇胶束在体内外对乳腺癌细胞具有与紫杉醇相似的抑制作用，不良反应小，且有效抑制剂量更低。

To evaluate the inhibition of disulfide bond paclitaxel polymeric micelle[P(PEGMEA)-co-P(PDPHEMA)-g-PTX, DBPM] on breast cancer by in vivo and in vitro experiments.

(1) MCF-7 cells were treated with 0.0001, 0.001, 0.01, 0.1, 1, 10, 50, 100, 500 μg/ml DBPM solution, and the optical density at the wavelength of 490 nm was measured by MTT method and 50%inhibition concentration (IC₅₀) was calculated. (2) Four cell lines (MCF-7, MDA-MB-231, MCF-10A, U937) were treated with 10 μg/ml micelle, paclitaxel and DBPM, respectively. The optical density at the wavelength of 490 nm was detected by MTT method. Flow cytometry was used to evaluate the apoptosis of MDA-MB-231 cells. (3) MDA-MB-231 cells were used to establish a mouse model of tumor. Eighteen nude mice were randomly divided into three groups (n=6). The mice in each group were administered with 5 mg/kg micelle, paclitaxel and DBPM, respectively. Another eighteen nude mice were randomly divided into three groups (n=6). The mice in each group were administered with 16 mg/kg micelle, 5 mg/kg paclitaxel and 16 mg/kg disulfide paclitaxel (loading rate 30.9%, 5 mg/kg paclitaxel), respectively. Tumor volume and weight were recorded separately. The blood routine of mice was measured. Tumors and other internal organs were pathologically analyzed. One-way analysis of variance was used for comparison between multiple groups. The LSD method was used for pairwise comparison. If no normal distribution and the homogeneity of variance were observed, the data was expressed as M(P₂₅-P₇₅) and analyzed by nonparametric tests.

(1) The inhibitory effect of DBPM on MCF-7 cells was concentration-dependent (IC₅₀=6.13 μg/ml). (2) In the MCF-7, MDA-MB-231, MCF-10A, U937 cell lines, the optical density of cells was significantly different among three groups (micelle group, paclitaxel group, DBPM group) (F=133.152, 139.673, 17.364, 14.900, P<0.050). There was a significant difference comparing micelle group with paclitaxel(P<0.050) or DBPM group (P<0.050), while no significant difference was observed between DBPM group and paclitaxel group (P=0.091, 0.071, 0.188, 0.616). The apoptotic rate of MDA-MB-231 cells in micelle group, paclitaxel group and DBPM group was 46.35%(45.20%-52.38%), 45.60%(45.03%-46.93%) and 11.70%(11.00%-12.60%), respectively, indicating a significant difference (P=0.003). Both paclitaxel group and DBPM group presented a significant difference compared with micelle group (both P<0.017), while there was no significant difference between paclitaxel group and DBPM group (P=0.423). (3) After injecting the corresponding drugs of 5 mg/kg into the mice, the tumor volume was (5 465±1 105) mm^3, (3 590±877) mm³ and (4 125± 792) mm³ in micelle group, paclitaxel group and DBPM group, respectively, suggesting a significant difference (F=7.264, P=0.005), and the tumor weight was (6.29±1.31) g, (3.62±1.03) g, (4.58±0.92) g in micelle group, paclitaxel group and DBPM group, respectively, suggesting a significant difference (F=10.167, P=0.001). There was no significant difference in tumor volume and weight between paclitaxel group and DBPM group (P=0.345, P=0.296). After the administration of 16 mg/kg micelle, 5 mg/kg paclitaxel and 16 mg/kg DBPM, the tumor volume was (3 251±679)mm^3, (1 936±399)mm³ and (1 637±371)mm³ in micelle group, paclitaxel group and DBPM group, respectively, suggesting a significant difference (F=16.100, P<0.001); the tumor weight was (3.02±0.48) g, (2.00±0.18) g, (2.00±0.18) g in micelle group, paclitaxel group and DBPM group, respectively, suggesting a significant difference (F=18.147, P<0.001). There was no significant difference in tumor volume and weight between paclitaxel group and DBPM group (P=0.385, 1.000). The nude mice in paclitaxel group had depression and reduced activities after 2 weeks of administration and 2 mice died later. The mice in other two groups were in good condition. There was no significant difference in the number of red blood cells, white blood cells and platelets of nude mice among three groups (F=1.424, 1.845, 2.257, P=0.276, 0.197, 0.144). HE staining results showed extensive necrosis in the tumor tissues of mice from paclitaxel group and DBPM group.

DBPM has inhibitory effect on breast cancer cells similar to paclitaxel both in vitro and in vivo. Its application has less adverse reactions and lower effective inhibitory dose.