Department of Pathology, Sapporo Medical University School of Medicine, Sapporo, Japan.
Lab Invest. 2011 Dec;91(12):1796-804. doi: 10.1038/labinvest.2011.140. Epub 2011 Sep 19.
Recently, the SOX2 gene has been reported to be amplified in human lung squamous cell carcinomas. However, its roles in human lung adenocarcinomas are still elusive. In this study, we analyzed the functions of SOX2 in cancer stem-like cells (CSCs)/cancer-initiating cells (CICs) derived from human lung adenocarcinoma. Human lung CSCs/CICs were isolated as higher tumorigenic side population (SP) cells using Hoechst 33342 dye from several lung cancer cell lines. Four of nine lung cancer cell lines were positive for SP cells (LHK2, 1-87, A549, Lc817). The ratios of SP cells ranged from 0.4% for Lc817 to 2.8% for LHK2. To analyze the molecular aspects of SP cells, we performed microarray screening and RT-PCR analysis, and isolated SOX2 as one of a SP cell-specific gene. SOX2 was expressed predominantly in LHK2 and 1-87 SP cells, and was also expressed in several other cancer cell lines. The expression of SOX2 protein in primary human lung cancer tissues were also confirmed by immunohistochemical staining, and SOX2 was detected in more than 80% of primary lung cancer tissues. To address SOX2 molecular functions, we established a SOX2-overexpressed LHK2 and A549 cell line (LHK2-SOX2 and A549-SOX2). LHK2-SOX2 cells showed higher rates of SP cells and higher expression of POU5F1 compared with control cells. LHK2-SOX2 and A549-SOX2 cells showed relatively higher tumorigenicity than control cells. On the other hand, SOX2 mRNA knockdown of LHK2 SP cells by gene-specific siRNA completely abrogated tumorigenicity in vivo. These observations indicate that SOX2 has a role in maintenance of stemness and tumorigenicity of human lung adenocarcinoma CSCs/CICs and is a potential target for treatment.
最近，已经有报道称 SOX2 基因在人类肺鳞癌中扩增。然而，其在人类肺腺癌中的作用仍不明确。在这项研究中，我们分析了 SOX2 在源自人类肺腺癌的癌症干细胞样细胞（CSCs）/癌症起始细胞（CICs）中的功能。我们使用 Hoechst 33342 染料从几种肺癌细胞系中分离出更高致瘤性侧群（SP）细胞，从而分离出人类肺 CSCs/CICs。九种肺癌细胞系中有四种为 SP 细胞阳性（LHK2、1-87、A549、Lc817）。SP 细胞的比例范围从 Lc817 的 0.4%到 LHK2 的 2.8%。为了分析 SP 细胞的分子方面，我们进行了微阵列筛选和 RT-PCR 分析，并分离出 SOX2 作为 SP 细胞特异性基因之一。SOX2 在 LHK2 和 1-87 SP 细胞中表达为主，在其他几种癌细胞系中也有表达。免疫组织化学染色也证实了 SOX2 蛋白在原发性人肺癌组织中的表达，并且在超过 80%的原发性肺癌组织中检测到了 SOX2。为了研究 SOX2 的分子功能，我们建立了一个 SOX2 过表达的 LHK2 和 A549 细胞系（LHK2-SOX2 和 A549-SOX2）。与对照细胞相比，LHK2-SOX2 细胞具有更高的 SP 细胞比例和更高的 POU5F1 表达。LHK2-SOX2 和 A549-SOX2 细胞比对照细胞具有相对更高的致瘤性。另一方面，通过基因特异性 siRNA 对 LHK2 SP 细胞进行 SOX2 mRNA 敲低，完全消除了体内的致瘤性。这些观察结果表明，SOX2 在维持人类肺腺癌 CSCs/CICs 的干性和致瘤性方面具有作用，是治疗的潜在靶点。
