Mikami Yurie, Fujii Shinsuke, Nagata Kengo, Wada Hiroko, Hasegawa Kana, Abe Misaki, Yoshimoto Reiko U, Kawano Shintaro, Nakamura Seiji, Kiyoshima Tamotsu
Laboratory of Oral Pathology, Division of Maxillofacial Diagnostic and Surgical Sciences, Faculty of Dental Science, Kyushu University, 3-1-1 Maidashi, Higashi-ku, Fukuoka, 812-8582, Japan.
Section of Maxillofacial Oncology, Division of Maxillofacial Diagnostic and Surgical Sciences, Faculty of Dental Science, Kyushu University, 3-1-1 Maidashi, Higashi-ku, Fukuoka, 812-8582, Japan.
J Cancer Res Clin Oncol. 2017 Aug;143(8):1381-1393. doi: 10.1007/s00432-017-2398-2. Epub 2017 Mar 24.
Keratin 17 (KRT17) has been suggested as a potential diagnostic marker of squamous cell carcinoma including oral squamous cell carcinoma (OSCC). The current study was conducted to clarify the function of KRT17 and its expression mechanism in OSCC.
Immunohistochemical analyses were carried out to examine the expression of KRT17, GLI family zinc finger (GLI)-1, GLI-2, or cleaved caspase-3 in OSCCs. The expression of KRT17, GLI-1, or GLI-2 was investigated among OSCC cell lines, and the effects of loss-of-function of KRT17 or GLI, using siRNA or inhibitor, on the cell growth of the OSCC cell line HSC-2 particularly with respect to apoptosis were examined.
Immunohistochemical analyses of tissue specimens obtained from 78 OSCC patients revealed that KRT17 was not observed in non-tumor regions but was strongly expressed at high frequencies in tumor regions. Knockdown of KRT17 increased the number of cleaved caspase-3-positive cells, leading to the reduction of cell number. Loss-of-function of GLI-1 or GLI-2 also increased the cell numbers of apoptotic cells positive for staining of Annexin-V and propidium iodide (PI) and the terminal deoxynucleotidyl transferase dUTP-biotin nick-end labeling (TUNEL) method, and induced DNA fragmentation. This inhibitory effect on cell growth was partially rescued by exogenous KRT17 expression. In the KRT17-positive regions in OSCCs, GLI-1 or GLI-2 was frequently detected, and the number of cells with cleaved caspase-3 positive was decreased.
KRT17 promotes tumor cell growth, at least partially, through its anti-apoptotic effect as a result of the KRT17 overexpression by GLIs in OSCC.
角蛋白17（KRT17）已被认为是包括口腔鳞状细胞癌（OSCC）在内的鳞状细胞癌的潜在诊断标志物。本研究旨在阐明KRT17在OSCC中的功能及其表达机制。
采用免疫组织化学分析检测KRT17、GLI家族锌指蛋白（GLI）-1、GLI-2或裂解的半胱天冬酶-3在OSCC中的表达。研究了OSCC细胞系中KRT17、GLI-1或GLI-2的表达，并使用小干扰RNA（siRNA）或抑制剂敲低KRT17或GLI的功能，检测其对OSCC细胞系HSC-2细胞生长的影响，特别是对细胞凋亡的影响。
对78例OSCC患者的组织标本进行免疫组织化学分析，结果显示，在非肿瘤区域未观察到KRT17，但在肿瘤区域高频率强表达。敲低KRT17可增加裂解的半胱天冬酶-3阳性细胞数量，导致细胞数量减少。GLI-1或GLI-2功能丧失也增加了膜联蛋白-V和碘化丙啶（PI）染色及末端脱氧核苷酸转移酶介导的dUTP缺口末端标记（TUNEL）法阳性的凋亡细胞数量，并诱导DNA片段化。外源性KRT17表达可部分挽救这种对细胞生长的抑制作用。在OSCC的KRT17阳性区域，经常检测到GLI-1或GLI-2，且裂解的半胱天冬酶-3阳性细胞数量减少。
在OSCC中，KRT17通过GLIs使其过表达，至少部分地通过其抗凋亡作用促进肿瘤细胞生长。
