IC followed by surgery and/or CCR is a comprehensive treatment modality for locally advanced hypopharyngeal cancer patients. However, some patients do not benefit from this treatment due to resistance to IC. So, it is urgently needed to investigate the mechanism of IC resistance. In our study, we provide evidences for the role of miR-211-3p in promoting HSCC progression and identify that miR-211-3p upregulates CSF2/CCL20/TNF signaling to promote IC insensitivity in HSCC.
In HNSCC, previous studies have reported miRNAs take part in its chemoresistance. High level of plasma exosome miR-196a is correlated with poor overall survival and confer cisplatin resistance by downregulating CDKN1B and ING5 in head and neck cancer . MiR-24-3p promotes cell proliferation and regulates chemosensitivity by targeting CHD5 in HNSCC . In tongue squamous cell carcinoma (TSCC), miR-23a promotes chemoresistance and protects cisplatin-induced apoptosis through inducing Twist expression by a JNK-dependent mechanism . miR-211 is reported to be involved in the development and progression of HNSCC. High expression of miR-211 is associated with poor prognosis in oral carcinoma patients, and significantly promotes tumor cell proliferation, migration, and anchorage-independent colony formation . In oral squamous cell carcinoma (OSCC), miR-211 directly targets TCF12, which leads to FAM213A over-expression and plays oncogenic role . In HNSCC, miR-211 regulates TGFβRII and c-Myc promoting cancer progression . However, studies on the molecular mechanism of miR-211-3p involved in IC resistance are still in a developing stage, a comprehensive exploration is needed urgently.
In our present study, we demonstrated that miR-211-3p was up-regulated in IC insensitive larynx-hypopharyngeal tumor tissues, which was consistent with our previous microarray data . We also found that overexpression of miR-211-3p promoted cell proliferation and migration, and inhibited cell apoptosis. The overexpression of miR-211-3p enhanced the IC insensitivity in HSCC cancer cells.
The transcriptome sequencing data of our results showed CSF2 and CCL20 were downstream genes of miR-211-3p. Colony stimulating factor 2 (CSF2), also known as granulocyte macrophage-colony stimulating factor (GM-CSF), acts as a tumor-stimulating factor which promotes immune-independent tumor progression . In gliomas, CSF2 can trigger and drive the alternative activation of tumour-infiltrating microglia/macrophages and shape the tumor immune microenvironment . High CSF2 expression, which is caused by DNA demethylation, affects the immune response to tumor cells and tumor microenvironment. CSF2 plays hub gene role in chemoresistance and correlates worse prognosis in colorectal Cancer . CSF2 is a novel pro-inflammatory factor in human gastric cancer, which effectively induces PD-L1 expression on neutrophils via activation of JAK-STAT3 pathway . Besides, C-C motif chemokine ligand 20 (CCL20) promotes chemoresistance and regulate tumor immune microenvironment in many cancers. CCL20 can recruit regulatory T cells to promote chemoresistance via FOXO1/CEBPB/NF-κB signaling in colorectal cancer . Chemotherapy-induced CCL20 can activate NF-κB pathway and then increase ABCB1 expression, leading to chemoresistance in triple-negative breast cancer patients. The activated NF-κB pathway can also regulate CCL20 expression to further enhance the effect of CCL20 on chemoresistance by a positive feedback loop . Tumor cell-derived CCL20 can promote hepatocellular carcinoma (HCC) progression by interacting with CCR6 highly expressed CD19+CD5+B cells . In lung adenocarcinoma, RUNX3 can upregulate the expression of CCL3 and CCL20 to attract CD8+ T cells into tumor immune microenvironment .
In accordance with the literature, we found CSF2 and CCL20 were involved in TNF signaling pathway and correlated with poor prognosis in HNSCC. Meanwhile, the TNF signaling pathway, a typical inflammatory pathway, was activated in HSCC cells after overexpression of miR-211-3p. Furthermore, our results also indicated that CSF2 and CCL2 were correlated with immune cell infiltration. These results suggest that miR-211-3p may promote IC insensitivity via CSF2/CCL20/TNF signaling to regulate tumor immune cell infiltration in HSCC. However, further molecular and cellular experiments are required in the future.