Tumor inhibitory effects of 131I-Trastuzumab on human epidermal growth factor receptor 2 overexpressing breast cancer cells and its possible mechanisms / 中华核医学与分子影像杂志

ABSTRACT

Objective To explore antitumor effect of 131I-Trastuzumab on human epidermal growth factor receptor(HER) 2 overexpressing breast cancer cells and investigate its possible mechanism.Methods The expression levels of HER2 of three different breast cancer cell lines (BT474,MCF-7,HCC1937) were detected with immunofluorescence.Trastuzumab was labeled with 131I using the Iodogen method and 131I-Trastuzumab was isolated with ultrafiltration membrane,then the labeling efficiency,radiochemical purity and immunoreactivity were measured.The effects of 131I,Trastuzumab and 131I-Trastuzumab on viability of BT474 cells were evaluated with cell counting kit-8 (CCK-8) assay.The levels of total Akt and phosphorylated Akt (p-Akt) were detected with Western blot analysis.One-way analysis of variance (ANOVA),ANOVA for factorial design,Bonferroni correction and Pearson correlation analysis were used for data analysis.Results The expression level of HER2 in BT474 cells was much higher than those in HCC1937 and MCF-7 cells.The labeling efficiency,radiochemical purity and immunoreactivity of 131I-Trastuzumab were (89.71± 2.93)％,(91.80±1.43)％ and (58.84±3.35)％ respectively.131I (4.625 GBq/L),Trastuzumab(125.0 rmg/L) and 131I-Trastuzumab(4.625 GBq/L) exhibited a dose-dependent cytotoxicity against BT474 cells (r =-0.964,-0.912,-0.618;all P＜0.05).The cell viability of 131I-Trastuzumab treated gourp (34.73％ ±5.03％) was significantly lower than those of 131I and Trastuzumab treated groups (64.36％± 1.51％ and 58.09％±4.14％;t=10.373 and 8.180,both P＜0.05),and the cell viability of control group was (100.00±4.54)％.131I-Trastuzumab shown a positive multiplicative interaction between 131I and Trastuzumab (F=9.226,P＜0.05;CDI =0.929).Western blot results showed that there was no significant difference of total Akt expression among the control group,131I group,Trastuzumab group and 131I-Trastuzmab group (F=0.208,P＞0.05).P-Akt expression in both Trastuzumab group and 131I-Trastuzumab group were much lower than those of control group and 131I group (t=12.524,15.984,7.347,10.807;all P＜0.05),while there was no significant difference of p-Akt expression between Trastuzumab group and 131I-Trastuzumab group(t =3.460,P＞0.05).Conclusions 131I-Trastuzumab may kill HER2 overexpressing breast cancer cells more effectively than Trastuzumab alone.The underlying mechanism may be attributed to that 131I-Trastuzumab may enhance the radiosensitivity by the inhibitory effect on PI3K/Akt pathway and thus exert synergistic effects with 131I.