State Key Laboratory of Oral Diseases and National Clinical Research Center for Oral Diseases and Department of Oral and Maxillofacial Surgery, Hospital of Stomatology, Sichuan University, No.14, Sec. 3, Renminnan Road, Chengdu, 610041, West China, China.
Department of Head and Neck Surgery, Sichuan Cancer Center, School of Medicine, Sichuan Cancer Hospital and Institute, University of Electronic Science and Technology of China, Chengdu, Sichuan, China.
Cancer Immunol Immunother. 2021 Apr;70(4):1015-1029. doi: 10.1007/s00262-020-02741-2. Epub 2020 Oct 26.
CKLF-like MARVEL transmembrane domain-containing 6 (CMTM6) is a critical regulator of tumor immunology among various cancers. However, the role and underlying molecular mechanism of CMTM6 in oral squamous cell carcinoma (OSCC) progression remains unclear.
The expression of CMTM6, PD-L1 and CD163 in OSCC tissues were detected by immunohistochemistry on tissue microarray. The effect of CMTM6 knockdown on OSCC cells and macrophage polarization were analyzed by CCK-8 assay, apoptotic assay, would-healing assay, transwell assay and qPCR. OSCC cell derived exosomes were obtained by ultracentrifugation and the mechanistic studies were conducted by qPCR and Western Blot. 4-Nitroquinoline N-oxide (4NQO) induced OSCC mice were used for verifying the effect of CMTM6 downregulation on M2 macrophage infiltration and tumor growth.
In OSCC samples, higher CMTM6 expression has been obviously associated with higher pathological stage of OSCC patients, CD163 + macrophages infiltration and PD-L1 expression. CMTM6 knockdown of OSCC cells inhibited proliferative, migrative and invasive abilities of OSCC cells, as well as inhibited M2 macrophage polarization in vitro with downregulating PD-L1 expression. Importantly, exosomes from OSCC cells shuttled CMTM6 to macrophages and promoted M2-like macrophage polarization through activating ERK1/2 signaling. In addition, in 4NQO-induced OSCC mice, CMTM6 level was positively associated with CD163, CD206 and PD-L1 as well as M2-like macrophage infiltration.
OSCC cell-secreted exosomal CMTM6 induces M2-like macrophages polarization to promote malignant progression via ERK1/2 signaling pathway, revealing a novel crosstalk between cancer cells and immune cells in OSCC microenvironment.
CKLF 样 MARVEL 跨膜结构域包含蛋白 6（CMTM6）是各种癌症中肿瘤免疫的关键调节因子。然而，CMTM6 在口腔鳞状细胞癌（OSCC）进展中的作用和潜在分子机制尚不清楚。
通过组织微阵列免疫组织化学检测 OSCC 组织中 CMTM6、PD-L1 和 CD163 的表达。通过 CCK-8 测定、凋亡测定、划痕愈合测定、transwell 测定和 qPCR 分析 CMTM6 敲低对 OSCC 细胞和巨噬细胞极化的影响。通过超速离心获得 OSCC 细胞衍生的外泌体，并通过 qPCR 和 Western Blot 进行机制研究。使用 4-硝基喹啉 N-氧化物（4NQO）诱导 OSCC 小鼠验证 CMTM6 下调对 M2 巨噬细胞浸润和肿瘤生长的影响。
在 OSCC 样本中，CMTM6 表达水平升高与 OSCC 患者的病理分期较高、CD163+巨噬细胞浸润和 PD-L1 表达水平升高明显相关。OSCC 细胞中 CMTM6 的敲低抑制了 OSCC 细胞的增殖、迁移和侵袭能力，并通过下调 PD-L1 表达抑制了体外 M2 巨噬细胞极化。重要的是，OSCC 细胞来源的外泌体将 CMTM6 转运至巨噬细胞，并通过激活 ERK1/2 信号通路促进 M2 样巨噬细胞极化。此外，在 4NQO 诱导的 OSCC 小鼠中，CMTM6 水平与 CD163、CD206 和 PD-L1 以及 M2 样巨噬细胞浸润呈正相关。
OSCC 细胞分泌的外泌体 CMTM6 通过 ERK1/2 信号通路诱导 M2 样巨噬细胞极化，促进恶性进展，揭示了 OSCC 微环境中癌细胞与免疫细胞之间的新串扰。
