早期乳腺癌患者循环肿瘤细胞TP53、磷脂酰肌醇-3激酶基因突变分析及其与患者临床病理特征的相关性

摘要

Objective:To investigate the count of circulating tumor cells(CTC)as well as the mutation of TP53 and PI3K gene in patients with early breast cancer, and to analyze the relationship between the gene mutation and clinicopathological features.Methods:A total of 30 patients diagnosed with breast cancer and benign breast masses were collected during January to February 2015.CellSearch method was used to detect CTCs in blood.The mutations of TP53 (p.R248Q,p.R273H,p.R175H)and PI3K(p.E545K,p.H1047R)in patients' blood,CTC,and urine were detected by droplet digital PCR techniques(ddPCR).Meanwhile,the clinical data of all patients were collected including age of onset, tumor size,histological grade,molecular typing,axillary lymph node status,and Ki-67.The relationship between the mutations and clinicopathological features was analyzed.Results:A total of 82(18.9%)were found positive mutations in 435 samples from 29 patients with blood,CTC,and urine samples.The mutation rate of each gene was different,the highest was TP53(p.R175H)with 29 samples(6.7%),the lowest was PI3K(p.E545K)having only 1 sample(0.2%).The mutation rates of five genes were statistically different(χ2 = 50.133,P< 0.001).There were significant differences in the mutation rates among five genes of CTC,blood,and urine(likelihood ratio = 14.204,P= 0.007;χ2 = 25.172,P< 0.001;χ2 =16.681,P=0.002).The highest mutation rate was TP53(p.R175H)in the three types of specimens.There was a correlation between TP53 gene mutation and the clinicopathological features of some patients with breast cancer.The molecular type of breast cancer and the degree of Ki-67 were correlated with the mutation of TP53(p.R248Q)in CTC specimen(Fisher's Exact Test = 10.839,P=0.003;P=0.028).The axillary lymph node metastasis was related to the mutation of TP 53(p.R175H) gene in CTC specimens(P=0.058).Conclusions:The molecular classification of breast cancer and the degree of tumor marker Ki-67 are associated with TP53(p.R248Q)mutation in CTC specimens from patients with early breast cancer.Axillary lymph node metastasis may also be associated with TP53(p.R175H)mutation in CTC specimens.It is suggested that the mutation of TP53 gene in CTC specimens may be a potential indicator for the selection of treatment regimen and prognosis of early breast cancer.%目的:检测早期乳腺癌患者循环肿瘤细胞(circulating tumor cells,CTC)计数及其 TP53、磷脂酰肌醇-3激酶(PI3K)基因突变情况,探讨基因突变结果与患者临床病理特征的相关性.方法:收集30例乳腺癌和良性乳腺肿瘤确诊患者的临床资料及血液、尿液标本,采用CellSearch法检测患者外周血CTC数目;采用微滴式数字PCR(droplet digital PCR,ddPCR)技术检测患者血、CTC和尿标本中 TP53(p.R248Q、p.R273H、p.R175H)和 PI3K(p.E545K、p.H1047R)基因位点突变情况;分析基因突变情况与患者临床病理特征(发病年龄、肿瘤大小、组织学分级、分子分型、腋窝淋巴结转移和Ki-67指数等)间的相关性.结果:最终纳入29例患者,患者血、CTC和尿标本中共获得435个基因检测结果,其中发生基因突变的82个(18.9%).5种基因位点的突变率不同,差异有统计学意义(P<0.001).突变率最高的基因是T P53(p.R175H),有29个突变(6.7%);突变率最低的是PI3K(p.E545K),仅发生1个(0.2%)突变.CTC、血和尿标本间5种基因位点的突变率差异有统计学意义(P=0.007,P<0.001,P=0.002),3类样本中突变率最高的基因都是 TP53(p.R175H).乳腺癌分子分型和Ki-67指数与CTC标本中TP53(p.R248Q)基因突变相关(P=0.003,P=0.028),而腋窝淋巴结转移可能与CTC标本中TP53(p.R175H)基因突变有关(P=0.058).结论:早期乳腺癌患者的肿瘤分子分型和 Ki-67指数与CTC中TP53(p.R248Q)基因突变相关,而腋窝淋巴结转移可能与CTC中T P53(p.R175H)基因突变相关,提示CTC标本中T P53基因突变是早期乳腺癌治疗方案选择及预后判断的潜在指标.