白桦脂酸对人宫颈癌裸鼠移植瘤的抑制作用及机制

Effect and mechanism of betulinic acid on the growth of human cervical cancer HeLa cells in nude mice

目的探讨白桦脂酸(BA)对人宫颈癌HeLa细胞株裸鼠皮下移植瘤生长的抑制作用及其机制。方法将4×106个HeLa细胞接种于裸鼠右肩背部皮下,建立人宫颈癌裸鼠皮下移植瘤模型,24只荷瘤裸鼠随机分为BA高剂量(80mg/kg)、中剂量(40mg/kg)、低剂量(20mg/kg)组及空白对照组(含溶剂),每组6只,隔日腹腔注射连续给药21d,停药24 h后处死裸鼠,测量裸鼠体重、移植瘤体积、瘤重,计算抑瘤率;光镜下观察移植瘤组织形态学变化;TUNEL法检测肿瘤细胞凋亡指数;免疫组化法检测瘤组织内caspase-3、CytoC蛋白表达。结果裸鼠处死后,BA处理组的移植瘤体积均明显小于空白对照组(P<0.01),其中高、中、低剂量组抑瘤率分别为56.2%、40.4%和24.6%(P<0.01);HE染色法显示BA处理组小鼠的移植瘤组织出现明显凋亡及坏死改变;TUNEL检测对照组和BA低、中、高剂量组的凋亡指数分别为(8.36±2.78)%、(20.98±3.01)%、(28.74±4.77)%和(39.34±6.15)%(P<0.05);免疫组化法示BA处理组的肿瘤组织caspase-3、CytoC蛋白表达水平较空白对照组明显升高(P<0.01)。结论 BA对人宫颈癌HeLa细胞移植瘤的生长具有明显的抑制作用,其机制可能与上调caspase-3、CytoC蛋白的表达及诱导细胞凋亡有关。

Objective To explore the inhibitory action and mechanism of betulinic acid （BA） on the growth of nude mice with HeLa cells subcutaneously transplanted tumor. Methods Nude mice model with transplanted tumor of human cervical cancer HeLa cells were established successfully by injecting HeLa cells（4 x 106） under the right axillary subcutaneously. Twenty-four nude mice were divided into 4 groups randomly ,control group（ including solvents） , BA high dosage group （80mg/kg） , BA medium dosage group （40mg/kg） and BA low dosage group（20mg/kg）. Each group was 6. All the mice were medicated by intraperitoneal injection once every two days for 21 days. Then all mice were sacrificed 24h after the final medication, and the transplanted tumor mass volume and weight were measured to calculate the tumor inhibitory rate ; the antitumor effect of BA was evaluated. Morphology changes of transplan- ted tumor tissues were observed under light microscope after HE staining. Apoptosis index was tested by TUNEL assay;The protein ex- pressions of caspase-3 and CytoC were detected by immunohistoehemical method. Results Tumor volumes of mice treated with BA were smaller than that of control group when mice were sacrificed （ P 〈 0. 01 ）. The tumor inhibitory rate of BA high, medium, and low dosage groups were 56. 2% , 40. 4% and 24. 6% （P 〈 0. O1 ）. The necrosis and apoptosis cells of the transplanted tumors were found under light microscope in the BA treated group by HE staining assay. The apoptosis index of control group, BA low, medium and high dosage groupwas （8.36±2. 78）% ,（20. 98 ±3.01）% ,（28.74 ±4. 77）% and（39.34 ±6. 15）% by TUNEL test（P 〈0. 05）. Immu- nochemical method showed that compared with the control group, expressions of caspase-3 and CytoC in transplanted tumors were upregulated in BA groups. Conclusion BA exerted significant inhibitory effect on the growth of transplanted tumors of human cervical canc- er HeLa cells in nude mice. The mechanism may be associated with upregulating caspase-3 and CytoC protein.