摘要
核转运蛋白α2(KPNA2)异常表达能增强乳腺癌细胞迁移和侵袭能力,导致肺转移风险,并与乳腺癌患者不良预后相关。本研究进一步分析KPNA2在乳腺癌细胞中的表达情况,并探讨其对乳腺癌细胞生物学行为影响的相关机制。
用免疫组化检测62例乳腺癌患者癌组织与癌旁组织标本中KPNA2的表达。将两种人乳腺癌细胞株(MDA-MB-453、MCF-7)分为阴性对照组(转染空白质粒)、KPNA2敲低组(转染KPNA2 siRNA)、ERK抑制剂组(ERK抑制剂U0126处理)、联合组(转染KPNA2 siRNA联合U0126处理)。各组细胞处理48 h后,分别用qRT-PCR与Western blot检测KPNA2 mRNA与蛋白表达,并分别用MTT法、流式细胞术、Transwell实验、Western blot检测细胞增殖、凋亡、侵袭能力,以及ERK1/2通路与凋亡相关蛋白表达的变化。
免疫组化结果显示,KPNA2蛋白在乳腺癌组织中表达水平高于癌旁组织(2.48±0.39 vs. 1.28±0.22,P<0.05)。qRT-PCR与Western blot结果显示,两种乳腺癌细胞株的阴性对照组和ERK抑制剂组的KPNA2 mRNA及蛋白表达水平均无明显差异(均P>0.05),而KPNA2敲低组和联合组KPNA2 mRNA和蛋白表达下调(均P<0.05)。功能实验结果显示,与各自的阴性对照组比较,ERK抑制剂组、KPNA2敲低组和联合组的细胞增殖率降低、凋亡率升高、细胞侵袭能力减弱,其中联合组各项变化最为明显(均P<0.05)。Western blot结果显示,与各自的阴性对照组比较,ERK抑制剂组、KPNA2敲低组和联合组磷酸化ERK1/2、裂解的胱天蛋白酶3蛋白表达均下调,且联合组两者的下调程度最为明显(均P<0.05)。
关键词
乳腺癌近年来发病率逐渐增高,2022年的统计数据显示乳腺癌发病率居于女性恶性肿瘤首
MDA-MB-453、MCF-7细胞株:购自中国科学院细胞库。MDA-MB-453是TNBC细胞系,TNBC是最具侵袭性亚型,缺乏有效治疗手段且患者预后不
KPNA2和GAPDH引物序列:南京信帆生物技术有限公司。逆转录试剂盒和PCR试剂盒:南京诺唯赞公司。免疫组化试剂:北京中杉金桥公司。阴性对照质粒、KPNA2小干扰RNA(siRNA):上海北诺生物科技有限公司。电化学发光液和RIPA裂解液:上海碧云天公司。KPNA2、ERK1/2、磷酸化ERK1/2(p-ERK1/2)、C-caspase-3抗体:北京博奥森生物技术有限公司。ERK通路抑制剂U0126:上海北诺生物科技有限公司。TS100倒置显微镜:日本Olympus公司。StepOnePlus实时PCR系统:美国ABI公司。BD FACSCalibur流式细胞仪:美国BD Biosciences公司。1640培养基:Gibco公司。Transwell小室:北京科宇深蓝科技有限公司。二氨基联苯胺:艾美捷科技有限公司。
以10%甲醛固定组织,行脱蜡、脱水操作。以柠檬酸行微波修复后以磷酸缓冲液洗涤5 min,重复3次。加入3%的H2O2,洗涤后加入KPNA2反应过夜。滴加二抗于37 ℃下孵育50 min后冲洗,并以二氨基联苯胺显色,行苏木精复染后常规脱水、封片。每张切片选5个视野,观察100个细胞,以阳性细胞占比评分:0分:0~5%;1分:5%~25%;2分:26%~50%;3分:>50%。阳性细胞数在20%以上则为阳性。
于DMEM培养液中加入10%牛胎血清,分别接种MDA-MB-453、MCF-7细胞株进行培养。U0126浓度为10 μmol/L。随机将MDA-MB-453、MCF-7细胞分为阴性对照组(转染空白质粒)、ERK抑制剂组(使用ERK通路抑制剂U012
以TRIzol法提取总RNA,测定其浓度,逆转录获取cDNA,采用qRT-PCR系统行扩增,每个样本设置3个负孔,以GAPDH作为内参。GAPDH上游引物:5'-AGA AGG CTG GGG CTC ATT TG-3',下游引物:5'-AGG GGC GAT GCA GAG TCT TC-3';KPNA2上游引物:5'-GGA AGC ACC ATT ACG AAG G-3',下游引物:5'-TCC CGA AGG TAA CAT AAC TA-3'。于常规反应条件下循环40次,94 ℃反应4 min。重复进行3次,以
取各组MDA-MB-453、MCF-7细胞以RIPA裂解液提取蛋白,经SDS-PAGE电泳转移蛋白样品至醋酸纤维膜,用脱脂奶粉封闭2 h后,分别滴加稀释后的一抗(抗KPNA2、ERK1/2、p-ERK1/2抗体稀释浓度为1∶1 000,抗C-caspase-3抗体稀释浓度为1∶500,抗GAPDH抗体1∶1 000稀释度,设为内参),4 ℃过夜孵育后加入二抗孵育2 h,以电致化学发光显色后,使用软件分析蛋白条带灰度值。
取各组MDA-MB-453、MCF-7细胞接种于96孔板培养,于每孔中加入20 µL浓度为5 mg/mL的MTT液,37 ℃条件下培养4 h。各孔再加入150 µL二甲基亚砜溶液,放于酶标仪上检测其具体的吸光度(OD)值,细胞增殖率(%)=本组OD均值/阴性对照组OD均值×100%
按照试剂盒里面相关的说明书实施。将MDA-MB-453、MCF-7细胞进行接种,置于37 ℃培养箱中,待细胞贴壁后更换培养液为27-P-CAUA。避光孵育24 h后加入不含EDTA的胰蛋白酶反应,获得细胞悬液,再进行离心、洗涤操作。加入结合缓冲液重悬细胞500 μL,混匀后反应10 min。1 h内上机观察,并重复3次,计算Q2和Q3象限细胞的比例。
免疫组化结果显示,KPNA2蛋白在患者乳腺癌组织中的表达明显高于癌旁组织(

图1 免疫组化检测KPNA2蛋白的表达(×200) A:癌旁组织;B:癌组织
Figure 1 Immunohistochemical staining for expression of KPNA2 protein (×200) A: Adjacent tissue; B: Cancer tissue
MDA-MB-453、MCF-7细胞中,阴性对照组和ERK抑制剂组KPNA2 mRNA及蛋白表达之间差异无统计学意义(均P>0.05)。与各自的阴性对照组和ERK抑制剂组比较,KPNA2敲低组和联合组的KPNA2 mRNA及蛋白表达均明显下调(均P<0.05)(

图2 MDA-MB-453、MCF-7细胞中KPNA2的表达检测 A:mRNA表达;B:蛋白表达
Figure 2 Detection of KPNA2 expression in MDA-MB-453 and MCF-7 cells A: mRNA expression; B: Protein expression
与各自阴性对照组比较,MDA-MB-453、MCF-7细胞的ERK抑制剂组、KPNA2敲低组和联合组增殖率下降,凋亡率上升,其中联合组的变化程度最为明显(均P<0.05)(图

图3 各组MDA-MB-453、MCF-7细胞增殖率比较
Figure 3 Comparison of proliferation rates among groups of MDA-MB-453 and MCF-7 cells


图4 流式细胞术检测MDA-MB-453、MCF-7细胞凋亡情况以及各组凋亡率比较
Figure 4 Detection of apoptosis in MDA-MB-453 and MCF-7 cells by flow cytometry and comparison of apoptosis rates among groups
Transwell实验结果显示,与各自阴性对照组比较,ERK抑制剂组、KPNA2敲低组和联合组的侵袭细胞计数减少,而联合组细胞计数结果最低(均P<0.05)(

图5 各组细胞侵袭细胞数比较
Figure 5 Comparison of the number of invading cells in each group
MDA-MB-453、MCF-7细胞各组ERK1/2表达无差异(均P>0.05),但与各自阴性对照组比较,ERK抑制剂组、KPNA2敲低组和联合组的p-ERK1/2和C-caspase-3蛋白表达水平均下调,其中联合组下调程度最为明显(均P<0.05)(

图6 Western blot法检测MDA-MB-453、MCF-7细胞中ERK1/2、p-ERK1/2、C-caspase-3的表达
Figure 6 Detection of ERK1/2, p-ERK1/2, and C-caspase-3 expressions in MDA-MB-453 and MCF-7 cells by Western blot
组别 | MDA-MB-453细胞 | MCF-7细胞 | ||||
---|---|---|---|---|---|---|
p-ERK1/2 | ERK1/2 | C-caspase-3 | p-ERK1/2 | ERK1/2 | C-caspase-3 | |
阴性对照组 | 0.33±0.07 | 0.49±0.09 | 0.28±0.07 | 0.31±0.07 | 0.59±0.09 | 0.24±0.05 |
ERK抑制剂组 |
0.22±0.0 | 0.51±0.07 |
0.18±0.0 |
0.19±0.0 | 0.61±0.11 |
0.15±0.0 |
KPNA2敲低组 |
0.23±0.0 | 0.52±0.09 |
0.16±0.0 |
0.23±0.0 | 0.57±0.10 |
0.14±0.0 |
联合组 |
0.11±0.0 | 0.51±0.08 |
0.09±0.0 |
0.17±0.0 | 0.60±0.08 |
0.08±0.0 |
注: 1)与阴性对照组比较,P<0.05;2)与ERK抑制剂组比较,P<0.05;3)与KPNA2敲低组比较,P<0.05
Note: 1) P<0.05 vs. negative control group; 2) P<0.05 vs. ERK inhibitor group; 3) P<0.05 vs. KPNA2 knockdown group
探究乳腺癌的驱动基因和分子发病机制对于开发靶向治疗药物有重要意义。如磷脂酰肌醇3-激酶(phosphatidylinositide 3-kinases,PI3K)和哺乳动物雷帕霉素靶蛋白(mammalian target of rapamycin,mTOR)通路乳腺癌中异常激活,使用PI3K通路抑制剂阿培利司、卡帕塞替尼和mTOR抑制剂依维莫司能够使雌激素受体阳性的晚期乳腺癌患者获
ERK是Mark家族成员之一,其对细胞的增殖、分化、凋亡等生物学行为均有明显的调节作用,其主要通过激活多种转录因子来实
综上所述,乳腺癌组织中KPNA2表达水平异常偏高,下调KPNA2表达或抑制ERK信号通路能减弱乳腺癌细胞的增殖、侵袭活性,促进细胞凋亡,可作为乳腺癌的新治疗靶点。
作者贡献声明
冉冉负责实验设计、起草论文和修改论文;寇玲娜负责文章审核、协助文章修改;王浩负责数据获取、整理和分析,刘蔡杨、何幸负责数据分析、整理及作图。
利益冲突
所有作者均声明不存在利益冲突。
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