Department of Thoracic Surgery, First Affiliated Hospital of Anhui Medical University, Hefei, China.
Department of Radiotherapy, Luan Hospital of Chinese Medicine affiliated to Anhui University of Chinese Medicine, Luan, China.
Thorac Cancer. 2023 Aug;14(22):2139-2148. doi: 10.1111/1759-7714.14998. Epub 2023 Jun 21.
Elevated lactate results in an acidic tumor microenvironment (TME), which stimulates the progression of esophageal cancer (EC). Tumor-associated macrophages (TAMs) are an essential component of the TME. However, the regulatory mechanisms of lactate secreted by EC on TAMs and the effects of EC advancement are unclear.
Proteins and mRNA expression were determined by western blot and RT-qPCR. Cell metastasis and growth were assessed by scratch assay, transwell and BrdU assays. Lactate in cells was quantified using a lactate kit. A mouse model was constructed for validation in vivo.
First, we determined that lactate upgraded the M2-type polarization marker levels of macrophages. Cell function assays confirmed that lactate-activated M2 macrophages accelerated EC cell migration and proliferation in vitro. However, the lactate inhibitor - oxamate hampered the level of lactate in TE-1 cells. Oxamate abolished the facilitation of macrophage polarization by lactate. In addition, we discovered that phosphorylated AKT and phosphorylated ERK was obviously raised in lactate-stimulated macrophages, and oxamate addition reversed this change, implying that AKT and ERK signaling pathways were involved in macrophage polarization. Response experiments proved that attenuation of AKT/ERK signaling markedly returned the lactate-induced promotion of EC migration and proliferation by macrophages. Finally, mouse tumor models demonstrated that lactate enhanced EC growth by inducing M2 macrophage polarization.
EC-secreted lactate stimulated macrophage M2 polarization via the AKT/ERK pathway thereby boosting the growth of EC.
乳酸水平升高会导致酸性肿瘤微环境（TME），从而刺激食管癌（EC）的进展。肿瘤相关巨噬细胞（TAMs）是 TME 的重要组成部分。然而，EC 分泌的乳酸对 TAMs 的调节机制以及 EC 进展的影响尚不清楚。
通过 Western blot 和 RT-qPCR 测定蛋白质和 mRNA 表达。划痕实验、Transwell 和 BrdU 测定评估细胞迁移和生长。使用乳酸试剂盒定量细胞内的乳酸。构建小鼠模型进行体内验证。
首先，我们确定乳酸上调了巨噬细胞的 M2 型极化标志物水平。细胞功能测定证实，乳酸激活的 M2 巨噬细胞在体外加速了 EC 细胞的迁移和增殖。然而，乳酸抑制剂 - 草氨酸抑制了 TE-1 细胞中的乳酸水平。草氨酸消除了乳酸对巨噬细胞极化的促进作用。此外，我们发现，在乳酸刺激的巨噬细胞中，磷酸化 AKT 和磷酸化 ERK 明显升高，而添加草氨酸则逆转了这种变化，表明 AKT 和 ERK 信号通路参与了巨噬细胞极化。反应实验证明，通过 AKT/ERK 信号通路的衰减明显削弱了巨噬细胞引起的 EC 迁移和增殖的促进作用。最后，小鼠肿瘤模型表明，乳酸通过诱导 M2 巨噬细胞极化来增强 EC 的生长。
EC 分泌的乳酸通过 AKT/ERK 途径刺激巨噬细胞 M2 极化，从而促进 EC 的生长。
