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CCL2/EGF positive feedback loop between cancer cells and macrophages promotes cell migration and invasion in head and neck squamous cell carcinoma.

ABSTRACT: Head and neck squamous cell carcinoma (HNSCC) represents the most frequent malignancy in the head and neck region, and the survival rate has not been improved significantly over the past three decades. It has been reported the infiltrated macrophages contribute to the malignant progression of HNSCC. However, the crosstalk between macrophages and cancer cells remains poorly understood. In the present study, we explored interactions between monocytes/macrophages and HNSCC cells by establishing the direct co-culture system, and found that the crosstalk promoted the migration and invasion of cancer cells by enhancing the invadopodia formation through a CCL2/EGF positive feedback loop. Our results demonstrated HNSCC cells educated monocytes into M2-like macrophages by releasing C-C motif chemokine ligand 2 (CCL2, or MCP-1). And the M2-like macrophages secreted epithelial growth factor (EGF), which increased the motility of HNSCC cells by enhancing the invadopodia formation. These subcellular pseudopodia degraded extracellular matrix (ECM), facilitating tumor local invasion and distant metastasis. Moreover, EGF up-regulated CCL2 expression in HNSCC cells, which recruited monocytes and turned them into M2-like macrophages, thus forming a positive feedback paracrine loop. Finally, we reported that curcumin, a powerful natural drug, suppressed the production of EGF and CCL2 in macrophages and cancer cells, respectively, blocking the feedback loop and suppressing the migration and invasion of HNSCC cells. These results shed light on the possibilities and approaches based on targeting the crosstalk between cancer cells and monocytes/macrophages in HNSCC for potential cancer therapy.

SUBMITTER: Gao L

PROVIDER: S-EPMC5349969 | biostudies-literature |

REPOSITORIES: biostudies-literature

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Project description:Head and neck squamous cell carcinoma (HNSCC) has a proclivity for locoregional invasion. HNSCC mediates invasion in part through invadopodia-based proteolysis of the extracellular matrix (ECM). Activation of Src, Erk1/2, Abl and Arg downstream of epidermal growth factor receptor (EGFR) modulates invadopodia activity through phosphorylation of the actin regulatory protein cortactin. In MDA-MB-231 breast cancer cells, Abl and Arg function downstream of Src to phosphorylate cortactin, promoting invadopodia ECM degradation activity and thus assigning a pro-invasive role for Ableson kinases. We report that Abl kinases have an opposite, negative regulatory role in HNSCC where they suppress invadopodia and tumor invasion. Impairment of Abl expression or Abl kinase activity with imatinib mesylate enhanced HNSCC matrix degradation and 3D collagen invasion, functions that were impaired in MDA-MB-231. HNSCC lines with elevated EGFR and Src activation did not contain increased Abl or Arg kinase activity, suggesting that Src could bypass Abl/Arg to phosphorylate cortactin and promote invadopodia ECM degradation. Src-transformed Abl(-/-)/Arg(-/-) fibroblasts produced ECM degrading invadopodia containing pY421 cortactin, indicating that Abl/Arg are dispensable for invadopodia function in this system. Imatinib-treated HNSCC cells had increased EGFR, Erk1/2 and Src activation, enhancing cortactin pY421 and pS405/418 required for invadopodia function. Imatinib stimulated shedding of the EGFR ligand heparin-binding EGF-like growth factor (HB-EGF) from HNSCC cells, where soluble HB-EGF enhanced invadopodia ECM degradation in HNSCC but not in MDA-MB-231. HNSCC cells treated with inhibitors of the EGFR-invadopodia pathway indicated that EGFR and Src are required for invadopodia function. Collectively, our results indicate that Abl kinases negatively regulate HNSCC invasive processes through suppression of an HB-EGF autocrine loop responsible for activating a EGFR-Src-cortactin cascade, in contrast to the invasion promoting functions of Abl kinases in breast and other cancer types. Our results provide mechanistic support for recent failed HNSCC clinical trials utilizing imatinib.

Project description:BackgroundHead and neck squamous cell carcinoma (HNSCC) is one of the most frequent malignancies worldwide and is characterized by unfavorable prognosis, high lymph node metastasis and early recurrence. However, the molecular events regulating HNSCC tumorigenesis remain poorly understood. Therefore, uncovering the underlying mechanisms is urgently needed to identify novel and promising therapeutic targets for HNSCC. In this study, we aimed to explore the role of pleckstrin-2 (PLEK2) in regulating HNSCC tumorigenesis.MethodsThe expression pattern of PLEK2 and its clinical significance in HNSCC were determined by analyzing publicly assessable datasets and our own independent HNSCC cohort. In vitro and in vivo experiments, including cell proliferation, colony formation, Matrigel invasion, tumor sphere formation, ALDEFLUOR, Western blotting assays and xenograft mouse models, were used to investigate the role of PLEK2 in regulating the malignant behaviors of HNSCC cells. The underlying molecular mechanisms for the tumor-promoting role of PLEK2 were elucidated using co-immunoprecipitation, cycloheximide chase analysis, ubiquitination assays, chromatin immunoprecipitation-quantitative polymerase chain reaction, luciferase reporter assays and rescue experiments.ResultsThe expression levels of PLEK2 mRNA and protein were significantly increased in HNSCC tissues, and PLEK2 overexpression was strongly associated with poor overall survival and therapeutic resistance. Additionally, PLEK2 was important for maintaining the proliferation, invasion, epithelial-mesenchymal transition, cancer stemness and tumorigenesis of HNSCC cells and could alter the cellular metabolism of the cancer cells. Mechanistically, PLEK2 interacted with c-Myc and reduced the association of F-box and WD repeat domain containing 7 (FBXW7) with c-Myc, thereby avoiding ubiquitination and subsequent proteasome-mediated degradation of c-Myc. Moreover, the c-Myc signaling activated by PLEK2 was important for sustaining the aggressive malignant phenotypes and tumorigenesis of HNSCC cells. c-Myc also directly bounded to the PLEK2 promoter and activated its transcription, forming a positive feedback loop.ConclusionsCollectively, these findings uncover a previously unknown molecular basis of PLEK2-enhanced c-Myc signaling in HNSCC, suggesting that PLEK2 may represent a promising therapeutic target for treating HNSCC.

Project description:While treatment failure in cases of head and neck squamous cell carcinoma (HNSCC) frequently takes the form of locoregional recurrences and distant metastasis, our understanding of the mechanisms of metastasis in HNSCC is limited. We initially performed the upstream and key nodes analysis together with whole gene microarray analysis characterized by distant metastatic potential in vivo with HNSCC cell lines and identified JunB, a member of the activator protein-1 (AP-1) family, as a key molecule in the regulation of the pathways related to distant metastasis in HNSCC. We have therefore tested the hypothesis that JunB plays a crucial role in distant metastasis in HNSCC.To study the role of JunB on metastatic potential of HNSCC, small interfering RNA (siRNA)-mediated knockdown and clustered regularly interspaced short palindromic repeats (CRISPR)/CRISPR-associated protein 9 (cas9) system (CRISPR/Cas9)-mediated knockout of JunB in HNSCC cells were established and the abilities of cell invasion and migration in vitro were examined. The efficacy of knockout of JunB was also examined using an experimental lung metastatic mouse model of HNSCC. In addition, to study if the role of JunB in HNSCC cell migration and invasiveness is related to epithelial-to-mesenchymal transition (EMT), cell morphology and expression of mesenchymal or epithelial marker on siRNA mediated JunB knockdown in HNSCC cells were examined with or without TGF-? stimulation.siRNA knockdown and sgRNA knockout of JunB in metastatic HNSCC cells significantly suppressed both cell invasion and migration in vitro. In addition, the knockout of JunB in metastatic HNSCC cells significantly repressed the incidence of lung metastases and prolonged the survival in vivo. However, we did not observe any change in cell morphology with the down-regulation of mesenchymal markers and up-regulation of epithelial markers in response to siRNA-mediated JunB knockdown in HNSCC cells.These results suggested that JunB could play an important role in promoting cell invasion, migration and distant metastasis in HNSCC via pathways other than EMT and that the down-regulation of JunB may become an effective strategy for patients with invasive HNSCC.

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CCL2/EGF positive feedback loop between cancer cells and macrophages promotes cell migration and invasion in head and neck squamous cell carcinoma.

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