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Simple Summary: LncRNAs are involved in HNSCC carcinogenesis, progression, and metastasis. In this study, we identified a novel lncRNA, named MASCC1 (Metastasis-Associated Squamous Cell Carcinoma 1), which was highly expressed in metastatic HNSCC and correlated with poor prognosis. In vitro, MASCC1 knockdown (KD) inhibited HNSCC cell proliferation, migration, invasion, and tumor sphere formation while promoting apoptosis. In vivo, MASCC1 KD suppressed HNSCC tumor formation and lymph node metastasis. Mechanistically, MASCC1 acted as a competing endogenous RNA (ceRNA) to sponge miR-195, regulating Cyclin D1, BCL-2, and YAP1 expression. Moreover, miR-195 overexpression rescued the effects of MASCC1 overexpression on the biological behaviors of HNSCC in vitro and in vivo. Our results show that lncRNA MASCC1 functions as an oncogene and is involved in HNSCC progression and metastasis, providing a potential target for HNSCC treatment. The altered expression of long noncoding RNAs (lncRNAs) is associated with human carcinogenesis. We performed a high-throughput analysis of lncRNA expression in strictly selected pairs of metastatic head and neck squamous cell carcinoma (HNSCC) and non-metastatic HNSCC samples. We identified a novel lncRNA, which was highly expressed in metastatic HNSCC, named Metastasis Associated Squamous Cell Carcinoma 1 (MASCC1), for further study. Using qRT-PCR, we further compared MASCC1 expression in 60 HNSCC samples. The results show that high expression of MASCC1 in patients with HNSCC was related to poor prognosis. In vitro, MASCC1 knockdown (KD) inhibited HNSCC proliferation, migration, invasion, and tumor sphere formation, while promoting apoptosis. In vivo, MASCC1 KD inhibited HNSCC growth and lymph node metastasis. Mechanistically, MASCC1 acted as a competing endogenous RNA (ceRNA) by binding to miR-195, subsequently regulating the expression of Cyclin D1, BCL-2, and YAP1. Moreover, miR-195 overexpression rescued the effects of MASCC1 on the biological behaviors of HNSCC. Taken together, our results suggest that MASCC1 is a novel oncogene that can predict the prognosis of patients with HNSCC and is a potential therapeutic target for HNSCC intervention. [ABSTRACT FROM AUTHOR]

Background: Local resident normal fibroblasts (NFs) are the major source of cancer-associated fibroblasts (CAFs), which are distinguishable from NFs by their tumor-supportive properties. However, the mechanism and the effects underlying the transition of NFs to CAFs in oral squamous cell carcinoma (OSCC) remain unclear. Methods: Five pairs of matching primary NFs and CAFs derived from OSCC patients were sent for RNA sequencing. Epiregulin (EREG) expression was analyzed by IHC in fibroblasts from OSCC patients. The role of EREG in the NF-CAF transition and the consequential effects on OSCC progression were examined by upregulation/downregulation of EREG in NFs/CAFs both in vitro and in vivo. Results: Here, we identified epiregulin (EREG) as the most remarkably upregulated gene in CAFs. High EREG expression in CAFs correlated with higher T stage, deeper invasion and inferior worst pattern of invasion (WPOI) in OSCC patients and predicted shorter overall survival. Overexpression of EREG in NFs activated the CAF phenotype. Mechanistically, the JAK2/STAT3 pathway was enhanced by EREG in parallel with increased IL-6 expression, which could be inhibited by the JAK2 inhibitor AG490. Recombinant IL-6 upregulated the JAK2/STAT3/EREG pathway in a feedback loop. Moreover, EREG-induced CAF activation promoted the epithelial-mesenchymal transition (EMT) necessary for migration and invasion, which was dependent on JAK2/STAT3 signaling and IL-6. In vivo, EREG expression in stroma fibroblasts promoted tumor growth with high stromal α-SMA, phospho-JAK2/STAT3, and IL-6 expression and upregulated EMT in HSC3 cells. Conclusions: EREG is essential for the NF-CAF transformation needed to induce EMT of tumor cells in a JAK2-STAT3- and IL-6-dependent manner in OSCC. [ABSTRACT FROM AUTHOR]