MK-2206联合顺铂对乳腺癌4 T1／DDP移植瘤耐药性的影响

目的：探讨蛋白激酶B（protein kinase B，Akt）抑制剂MK-2206联合顺铂对三阴性乳腺癌4T1顺铂耐药（4T1／cisplatin，4T1／DDP）移植瘤耐药性的影响。方法采用顺铂（cisplatin，DDP）低剂量诱导及体内外交叉致瘤相结合的方法建立三阴性乳腺癌4T1／DDP耐药小鼠移植瘤模型，给予DDP腹腔注射（0．3 g／L，1次／d）单独或联合MK-2206灌胃（12 g／L，1次／周）治疗。给药28 d后处死小鼠，小动物成像检测观察肿瘤生长情况；Western blot法检测肿瘤组织中磷酸化Akt（phosphorate-Akt，p-Akt）和总Akt（total-Akt，t-Akt）蛋白水平变化；免疫组织化学法分析耐药相关蛋白P-糖蛋白（P-glycoprotein，P-gp）、乳腺癌耐药蛋白（breast cancer resistance protein，BCRP）、基质金属蛋白酶7（matrix metalloproteinase 7，MMP7）表达差异。结果建立的三阴性乳腺癌耐药小鼠模型达中等耐药程度。建立非耐药小鼠与耐药小鼠肿瘤组织生长速度未见明显区别（P＞0．05）。分别给予这两种模型小鼠相同剂量（0．3 g／L）的DDP治疗后，耐药小鼠对DDP的敏感性低于非耐药小鼠（P＜0．01）。将MK-2206（12 g／L）与DDP （0．3 g／L）联合应用后小鼠肿瘤较单独应用DDP缩小，且可降低P-gp、BCRP、MMP7蛋白的表达（均P＜0．05），并降低Akt蛋白磷酸化水平（P＜0．01）。结论 MK-2206联合顺铂能够逆转4T1／DDP移植瘤耐药性，且与抑制Akt蛋白磷酸化相关。

Effect of MK-2206 plus cisplatin on the drug resistant 4T1/DDP breast tumor in mice

Objective To investigate the effect of protein kinase B (Akt)inhibitor MK-2206 combined with cispla-tin on the drug resistance of 4T1/cisplatin (DDP)transplantation breast tumor.Methods Drug resistant 4T1/DDP trans-plantation tumor model was established with low-dose DDP induction and in vivo/in vitro tumorigenic approach in mice.The mice were then treated with intraperitoneal injection of DDP alone (0.3 g/L,once per day),or in combination with MK-2206 gavage (1 2 g/L,once per week).The mice were sacrificed 28 days afterwards.Small animal live imaging technology was applied to detect tumor growth.Western blots were used to examine the protein levels of phosphorylated-Akt and total-Akt.Immunohistochemistry was used to examine the expression of P-glycoprotein (P-gp),breast cancer resistance protein (BCRP),and matrix metalloproteinase 7 (MMP7).Results 4T1/DDP transplantation tumor mice model developed me-dium level of drug resistance.The tumor growth rates between non-resistant and resistant mice showed no significant differ-ence (P>0.05).After similar dose of DDP (0.3 g/L)treatment,drug resistant mice showed lower sensitivity than non-resistant mice (P<0.01 ).However,in the drug resistant mice treated with MK-2206(1 2 g/L)and DDP (0.3 g/L),the tumor size were significantly reduced,compared to DDP alone group (P<0.01 ).Moreover,the expression levels of P-gp, BCRP and MMP7 were all significantly reduced (P<0.05)in MK-2206 and DDP treated mice.The phosphorylation level of Akt was also decreased (P<0.01 ).Conclusion MK-2206 in combination with cisplatin can reverse the drug resist-ance of 4T1/DDP transplantation tumor,which may be mediated through the inhibition of Akt phosphorylation.