Mishima Chieko, Kagara Naofumi, Matsui Saki, Tanei Tomonori, Naoi Yasuto, Shimoda Masafumi, Shimomura Atsushi, Shimazu Kenzo, Kim Seung Jin, Noguchi Shinzaburo
Department of Breast and Endocrine Surgery, Osaka University Graduate School of Medicine, 2-2-E10 Yamadaoka, Suita-shi, Osaka 565-0871 Japan.
Springerplus. 2015 Oct 22;4:635. doi: 10.1186/s40064-015-1423-7. eCollection 2015.
The aim of the present study was to investigate the promoter methylation status of TRIM9 in breast cancer and to determine the presence of TRIM9-methylated circulating tumor DNA (ctDNA) in plasma. Bisulfite sequencing with a next generation sequencer showed TRIM9 promoter methylation in 92 % (11/12) of breast cancer cell lines (BCCs) and 68 % (13/19) of breast tumor tissues but not in any normal breast tissues (0/19). Methylation ratio of TRIM9 was significantly lower in basal type (9 %, n = 23) than luminal A (69 %, n = 29, P = 0.0003). Quantitative RT-PCR of BCCs disclosed an inverse correlation between TRIM9 mRNA expression and methylation ratio. TRIM9 methylated ctDNA in plasma was detected in 18 % (10/56) of metastatic breast cancer patients but not in any of 60 healthy controls. These results indicate that TRIM9 promoter hypermethylation, which suppresses TRIM9 mRNA expression, occurs in a significant proportion of breast tumors, and that TRIM9-methylated ctDNA thus may serve as a tumor marker for breast cancer.
本研究的目的是调查乳腺癌中TRIM9的启动子甲基化状态，并确定血浆中TRIM9甲基化循环肿瘤DNA（ctDNA）的存在情况。使用下一代测序仪进行的亚硫酸氢盐测序显示，92%（11/12）的乳腺癌细胞系（BCC）和68%（13/19）的乳腺肿瘤组织中存在TRIM9启动子甲基化，而在任何正常乳腺组织中均未检测到（0/19）。TRIM9的甲基化率在基底型（9%，n = 23）中显著低于管腔A型（69%，n = 29，P = 0.0003）。对BCC进行的定量逆转录聚合酶链反应显示，TRIM9 mRNA表达与甲基化率呈负相关。在18%（10/56）的转移性乳腺癌患者血浆中检测到TRIM9甲基化ctDNA，而在60名健康对照者中均未检测到。这些结果表明，抑制TRIM9 mRNA表达的TRIM9启动子高甲基化在相当比例的乳腺肿瘤中发生，因此TRIM9甲基化ctDNA可能作为乳腺癌的肿瘤标志物。
