The prognosis of head and neck squamous cell carcinoma (HNSCC) patients remains poor. High-throughput sequencing data have laid a solid foundation for identifying genes related to cancer prognosis, but a gene marker is needed to predict clinical outcomes in HNSCC. In our study, we downloaded RNA Seq, single nucleotide polymorphism, copy number variation, and clinical follow-up data from TCGA. The samples were randomly divided into training and test. In the training set, we screened genes and used random forests for feature selection. Gene-related prognostic models were established and validated in a test set and GEO verification set. Six genes (PEX11A, NLRP2, SERPINE1, UPK, CTTN, D2HGDH) were ultimately obtained through random forest feature selection. Cox regression analysis confirmed the 6-gene signature is an independent prognostic factor in HNSCC patients. This signature effectively stratified samples in the training, test, and external verification sets (P < 0.01). The 5-year survival AUC in the training and verification sets was greater than 0.74. Thus, we have constructed a 6-gene signature as a new prognostic marker for predicting survival of HNSCC patients.

BackgroundAlternatively activated macrophages in tumor microenvironment is defined as M2 tumor-associated macrophages (M2 TAMs) that promote cancer progression. However, communicative mechanisms between M2 TAMs and cancer cells in squamous cell carcinoma of head and neck (SCCHN) remain largely unknown.MethodsQuantitative real-time PCR, western blotting, enzyme-linked immunosorbent assay and flow cytometry were applied to quantify mRNA and protein expression of genes related to M2 TAMs, epithelial–mesenchymal transition (EMT) and stemness. Wounding-healing and Transwell invasion assays were performed to detect the invasion and migration. Sphere formation assay was used to detect the stemness of SCCHN cells. RNA-sequencing and following bioinformatics analysis were used to determine the alterations of transcriptome.ResultsTHP-1 monocytes were successfully polarized into M2-like TAMs, which was manifested by increased mRNA and protein expression of CCL18, IL-10 and CD206. Conditioned medium from M2-like TAMs promoted the migration and invasion of SCCHN cells, which was accompanied by the occurrence of EMT and enhanced stemness. Importantly, CCL18 neutralizing antibody partially abrogated these effects that caused by conditional medium from M2-like TAMs. In addition, recombinant human CCL18 (rhCCL18) correspondingly promoted the malignant biological behaviors of SCCHN in vitro. Finally, RNA-sequencing analysis identified 331 up-regulated and 363 down-regulated genes stimulated by rhCCL18, which were statistically enriched in 10 cancer associated signaling pathways.ConclusionThese findings indicate that CCL18 derived from M2-like TAMs promotes metastasis via inducing EMT and cancer stemness in SCCHN in vitro.Electronic supplementary materialThe online version of this article (10.1186/s12935-018-0620-1) contains supplementary material, which is available to authorized users.

Metastasis is one of the primary causes for high mortality in patients with squamous cell carcinoma of the head and neck (SCCHN). Our previous study showed that chemokine (C‐C motif) ligand 18 (CCL18), derived from tumour‐associated macrophages (TAMs), regulates SCCHN metastasis by promoting epithelial‐mesenchymal transition (EMT) and preserving stemness. However, the underlying mechanism needs to be further investigation. Interestingly, metadherin (MTDH) expression was induced when SCCHN cells were stimulated with recombinant CCL18 protein in this study. Suppressing MTDH expression reversed CCL18‐induced migration, invasion and EMT in SCCHN cells. Furthermore, the NF‐κB signalling pathway was involved in the MTDH knock‐down cells with CCL18 stimulation. We performed ELISA to evaluate the CCL18 levels in the serums of 132 treatment‐naive SCCHN patients, 25 patients with precancerous lesion and 32 healthy donors. Our results demonstrated that serum CCL18 levels were significantly higher in SCCHN patients than patients with precancerous lesion and healthy individuals. CCL18 levels were found to be significantly correlated with tumour classification, clinical stage, lymph node metastasis and histological grade in SCCHN patients. Thus, our findings suggest that CCL18 may serve as a potential biomarker for diagnosis of SCCHN and promote SCCHN invasion, migration and EMT by MTDH‐NF‐κB signalling pathway.