Lysyl-tRNA synthetase–expressing colon spheroids induce M2 macrophage polarization to promote metastasis
Seo Hee Nam, Doyeun Kim, Doohyung Lee, Hye-Mi Lee, Dae-Geun Song, Jae Woo Jung, Ji Eon Kim, Hye-Jin Kim, Nam Hoon Kwon, Eun-Kyeong Jo, Sunghoon Kim, Jung Weon Lee
Seo Hee Nam, Doyeun Kim, Doohyung Lee, Hye-Mi Lee, Dae-Geun Song, Jae Woo Jung, Ji Eon Kim, Hye-Jin Kim, Nam Hoon Kwon, Eun-Kyeong Jo, Sunghoon Kim, Jung Weon Lee
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Research Article Gastroenterology Oncology

Lysyl-tRNA synthetase–expressing colon spheroids induce M2 macrophage polarization to promote metastasis

Abstract

Lysyl-tRNA synthetase (KRS) functions canonically in cytosolic translational processes. However, KRS is highly expressed in colon cancer, and localizes to distinct cellular compartments upon phosphorylations (i.e., the plasma membranes after T52 phosphorylation and the nucleus after S207 phosphorylation), leading to probably alternative noncanonical functions. It is unknown how other subcellular KRSs crosstalk with environmental cues during cancer progression. Here, we demonstrate that the KRS-dependent metastatic behavior of colon cancer spheroids within 3D gels requires communication between cellular molecules and extracellular soluble factors and neighboring cells. Membranous KRS and nuclear KRS were found to participate in invasive cell dissemination of colon cancer spheroids in 3D gels. Cancer spheroids secreted GAS6 via a KRS-dependent mechanism and caused the M2 polarization of macrophages, which activated the neighboring cells via secretion of FGF2/GROα/M-CSF to promote cancer dissemination under environmental remodeling via fibroblast-mediated laminin production. Analyses of tissues from clinical colon cancer patients and Krs–/+ animal models for cancer metastasis supported the roles of KRS, GAS6, and M2 macrophages in KRS-dependent positive feedback between tumors and environmental factors. Altogether, KRS in colon cancer cells remodels the microenvironment to promote metastasis, which can thus be therapeutically targeted at these bidirectional KRS-dependent communications of cancer spheroids with environmental cues.

Authors

Seo Hee Nam, Doyeun Kim, Doohyung Lee, Hye-Mi Lee, Dae-Geun Song, Jae Woo Jung, Ji Eon Kim, Hye-Jin Kim, Nam Hoon Kwon, Eun-Kyeong Jo, Sunghoon Kim, Jung Weon Lee

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Figure 11

A positive relationship between KRS-positive colon cancer cells and an M2 macrophage–remodeled microenvironment promotes KRS-dependent metastasis.

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A positive relationship between KRS-positive colon cancer cells and an M...
(A) Normal human colon fibroblast (CCD-18Co) cells in 3D collagen I gels were analyzed for laminin expression (green) following treatment with CM of THP-1 monocytes or M1 or M2 macrophages. Nuclei were stained with DAPI (blue). (B–D) CCD-18Co fibroblasts were treated with vehicle, M2 macrophage-CM, or M1 macrophage-CM that had been treated with vehicle or CM from HCT116 spheroids (shControl, shKRS#2, or KRS-WT) for 4 days. Immunostaining was done for laminin (green), and nuclei were stained with DAPI (blue) (B). Laminin α1 (LAMA1), laminin β1 (LAMB1), or fibronectin (FN1) mRNA levels (C) or collagen contraction (D) were analyzed. (E) Collagen gel contraction was analyzed for CCD-18Co fibroblasts in normal media, CM from M2 macrophages, or CM from M1 macrophages that had been treated with GAS6 (G), GAS6 + IL-8 (GI), or GAS6 + IL-8 + ANG (GIA) for 4 days. (F) KRS-positive (shCon, shControl) colon cancer spheroids (green) were cocultured with CCD-18Co fibroblasts (red) that were treated with or without M2 macrophage-CM, before imaging of disseminative outgrowth of cancer cells and fibroblasts. The data are presented as the mean ± SD. *P < 0.05, ***P < 0.001 by 1-way ANOVA with Dunnett tests (C–E). The data shown represent 3 independent experiments.