RET／PTC1重排和BRAF^V600E突变甲状腺乳头状癌细胞系原位裸鼠模型比较

Comparison of orthotropic models of RET/PTC1 rearrangement and BRAF V600E mutation papillary thyroid cancer cell lines in nude mice

目的比较RET／PTC1重排和BRAF^V600E突变甲状腺乳头状癌细胞系的原位裸鼠模型。方法甲状腺乳头状癌细胞系TPC-1、BHP5-16和BHP2-7经实时定量PCR和DNA测序鉴定RET／PTCI重排和BRAF“加突变细胞株类型。3株细胞分别以2×10^5／只原位接种于balb／c裸鼠甲状腺被膜下，分别在4、12周处死裸鼠，剥离甲状腺肿瘤称重，并测定血清甲状腺激素水平。结果经实时定量PCR鉴定TPC-1和BHP2-7。细胞为RET／PTC1重排，且BHP2-7细胞RET／PTC1表达量远高于TPC-1细胞。DNA测序结果显示BHP5-16细胞为BRAF^V600E突变，TPC-1和BHP2-7细胞非BRAF^V600E突变。3组原位裸鼠模型表现各有不同。TPC-1和BHP5-16组成瘤率为100％，但BHP5-16组肿瘤生长迅速，肿瘤重量远大于TPC-1组。同时二者甲状腺激素水平的变化相同，4周时正常而12周时显著下降（P〈0．05）。然而BHP2-7组的成瘤率仅为6．25％，其甲状腺激素水平与正常对照组相比差异未见统计学意义（P〉0．05）。结论RET／PTCI重排和BRAF^V600E。突变甲状腺乳头状癌细胞系在原位裸鼠模型中表现不同，BRAF^V600E突变具有更明显提高模型成瘤率和促进肿瘤生长的作用。同时值得关注的是中晚期甲状腺肿瘤会导致机体甲状腺功能的破坏。

Objective To observe and compare the different orthotopic models of papillary thyroid cancer （PTC） cell lines of RET/PTCI rearrangement and BRAFV600E mutation in nude mice. Methods Human PTC cell lines TPC-1, BHP5-16 and BHP2z were used. The genotypes of RET/PTCI rearrangement and BRAFV600E mutation were determined by realtime-PCR and DNA sequencing analysis. The cells （2 × 10^5 ） were injected into the thyroid gland of nude mice. The nude mice were executed at 4th, 12th week, and then their thyroid tumors were removed and weighed. The levels of thyroid hormone were detected using chemiluminescent immunoassay. Results Both TPC-1 and BHP2_7 cells were identified as RET/PTC1 rearrangement by real time-PCR, and the expression of RET/PTCI rearrangement in BHP2-7 cell was higher than that of TPC-I cell. BRAFV600E mutation was found in BHP516 cell by DNA sequencing analysis, but was not found in TPC-1 and BHP2-7 cells. There were different characteristics in three orthotnpic nude model groups. Tumorigenic rates of TPC-1 and BHPs ,6 groups were 100%, but the growth of tumor was more rapid in BHP5-16 group than that in TPC-1 group, with more weight tumor. The changes of thyroid hormone levels in BHP5 -16 group and TPC-1 group were the same, which were normal at 4th week and sharply decreased at 12 th week（P〈0.05 ）. However, the tumorigenic rate of BHP2z group was only 6.25%. Compared with normal contrnl group, there was no statistical difference in the levels of thyroid hormone in BHP27 group （ P〉0.05 ）. Conclusions It showed difference in the orthotopic models of PTC cell lines of RET/PTC1 rearrangement and BRAF^V600E mutation in nude mice. BRAF^V600E mutation has obvious impacts on increasing tumorigenic rate and promotion of tumor growth in the orthotopic model. It should not be ignored that advanced thyroid tumor will lead to the destruction of thyroid function.