口腔鳞癌细胞释放外泌体THBS1活化肿瘤相关巨噬细胞经IL6/STAT3通路提高自身干性的研究

The acquiring of cancer stem cell-like properties is determined by intrinsic gene abnormalities, and/or extrinsic factors from the tumor microenvironment. Till now, no exact abnormalities of potential driver genes have been validated based on –omic studies in oral squamous cell carcinoma (OSCC). The tumor microenvironment might exert key roles in the regulation of cancer stem cells (CSCs ) in OSCC. Tumor-associated macrophages (TAMs) have been termed as the most abundant immune cells in the tumor microenvironment of OSCC. Our previous results have showed that: a. OSCC cells release exosome THBS1 to activate TAMs; b. activated TAMs promote the CSCs properties of OSCC; c. cytokine arrays indicate that activated TAMs secret amounts of IL6; d. activated TAMs promote the phosphate level of STAT3 in OSCC cells. Based on previous studies, we conclude that OSCC-exosome THBS1-TAMs-IL6/STAT3-CSCs feedback loop exerts important roles in the malignant progression of OSCC. Herein, we take the TAMs and CSCs as the objects of the research, and mainly focus on the underlying mechanisms for TAMs activation and its roles in the feedback regulation of CSCs properties of OSCC by using the conditioned culturing system. This study will facilitate certain knowledge to the clinical managements and treatments for the OSCC by targeting TAMs and CSCs.

癌细胞干性的获得取决于内源性基因异常，和/或肿瘤微环境中的外源性因素。大量的组学研究，尚未发现口腔鳞癌（OSCC）存在明确的驱动基因异常，肿瘤微环境无疑是调控其癌症干细胞（CSCs）的关键。肿瘤相关巨噬细胞（TAMs）是口腔鳞癌微环境中丰度最高的免疫细胞。申请人已初步证实：①OSCC释放外泌体携带THBS1活化TAMs；②TAMs经活化后，促进口腔鳞癌干性相关生物学行为；③细胞因子芯片提示，TAMs经活化后大量分泌IL6；④活化的TAMs能提高口腔鳞癌细胞内STAT3的磷酸化水平。结合以往研究，我们推断：OSCC-外泌体THBS1-TAMs-IL6/STAT3-CSCs反馈环路在口腔鳞癌恶性进展中发挥重要作用。本研究以TAMs和CSCs为研究对象，利用条件培养体系，探索TAMs活化及其反馈性调控口腔鳞癌干性的分子机制。这一机制的认识将为基于靶向TAMs及CSCs的口腔鳞癌治疗提供理论参考。

本课题组首次证实口腔鳞癌通过释放外体-THBS1活化类M1型肿瘤相关巨噬细胞（M1-like tumor-associated macrophages, M1-like TAMs）。随后，我们进一步研究M1-like TAMs在口腔鳞癌进展中的作用及作用机制。本研究发现，经口腔鳞癌外泌体活化后的M1-like TAMs能大量释放细胞因子IL6，并活化口腔鳞癌细胞内的JAK/STAT3信号通路，促进口腔鳞癌细胞上皮-间充质转化和癌细胞干性相关生物学行为。此外，本研究亦发现，经M1-like TAMs作用的口腔鳞癌细胞能够经IL6/STAT3/THBS1反馈环路释放更多的外泌体-THBS1， 进一步活化更多的M1-like TAMs。基于以上研究，本课题组首次提出M1-like TAMs可经IL6/STAT3/THBS1正反馈环路，促进口腔鳞癌细胞上皮-间充质转化和癌细胞干性的获取。本研究深入研究口腔鳞癌中M1-like TAMs的生物学作用及作用机制，为其在口腔鳞癌诊治中的进一步转化应用提供了理论基础。