Head and neck squamous cell carcinoma (HNSCC) is a prevalent disease worldwide, and the survival of HNSCC has not improved significantly over the last few decades. MicroRNAs (miRNAs) have an important regulatory role during carcinogenesis. Our study investigated the pathogenic implications of miR-134 in head and neck carcinogenesis. The clinicopathologic implications of miR-134 in HNSCC were investigated using expression assays and the functional role of miR-134 in HNSCC pathogenesis was determined using ectopic expression, knockdown and reporter assay experiments. Xenographic tumorigenesis and orthotopic nodal metastasis were assayed in mouse models. In situ hybridization and immunohistochemistry were used to detect the expression of miR-134 and the WWOX gene in human HNSCC. The results indicated that miR-134 was upregulated in HNSCC tissues relative to control mucosa. High expression of miR-134 was associated with nodal metastasis and mortality of patients. Decreased plasma miR-134 levels after tumor ablation indicated a better prognosis for patients. Multivariate analysis showed that high miR-134 expression in HNSCC was an independent predictor of poor survival. Ectopic miR-134 expression significantly enhanced in vitro oncogenic phenotypes and the orthotopic growth and metastasis of HNSCC cells. miR-134 targeted WW domain-containing oxidoreductase (WWOX) gene and cell invasion enhanced by miR-134 expression was abrogated by ectopic WWOX expression in HNSCC cells. miR-134 expression was reversely associated with the WWOX expression in HNSCC tissues. Evidences from our study substantiated that miR-134 expression contributes to head and neck carcinogenesis by targeting the WWOX.MicroRNAs (miRNAs) are 20-22 nucleotide, small, nonprotein-coding RNA molecules that negatively regulate the expression of target genes via epigenetic regulation.

Oral squamous cell carcinoma (OSCC) is a common malignancy worldwide. This study clarified the oncogenic role of miR-134 in OSCC. Reporter assays, using both wild-type and mutant constructs, confirmed that Programmed Cell Death 7 (PDCD7) gene was a potential target of miR-134. The OSCC cells exogenously expressed miR-134 exhibited reduced PDCD7 expression. As expected, exogenous miRZip-134 expression increased PDCD7 expression in the OSCC cells; additionally, PDCD7 expression suppressed the oncogenicity of the OSCC cells. By contrast, PDCD7 knockout through gene editing increased in vitro oncogenicity and neck nodal metastasis in mice, and reduced E-cadherin (E-cad) expression. PDCD7 transactivated E-cad expression via the GC-box in the promoter. Moreover, miR-134-associated cellular transformation and E-cad downregulation was attenuated by PDCD7. Downregulation of both PDCD7 and E-cad and high levels miR-134 expression was observed in OSCC tumor tissues. Activation of the miR-134-PDCD7-E-cad pathogenesis cascade occurred early during the human and murine oral carcinogenesis process. In conclusion, the oncogenic effect of miR-134 in oral carcinoma is mediated by reducing PDCD7 and E-cad expression.

Together, these results suggest the translational value of BI-D1870 in oral squamous cell carcinoma therapy.