MiR-128 Restrains The Epithelial–Mesenchymal Transition in Tongue Squamous Cell Carcinoma Via Suppressing the Oncogenic Activity of MAP2K7

Abstract

The growing incidence of tongue squamous cell carcinoma (TSCC) across the world ratify the aggressive and malignant behavior of this tumor among the other oral quamous cell carcinomas (OSCC) showing poor prognosis, and excessive recurrence risk followed by local invasion. Past studies already revealed that small non-coding RNA molecules comprising 18-25 nucleotides known as microRNAs (miRNAs) can target mRNAs via forming RNA-induced silencing complex (RISC), thereby obstructing the translation, and reducing the half-life of the target mRNAs. However, in tumors, the deregulated expression of microRNAs (miRNAs) has gained a lot of attention being implicated as tumor suppressor or cancer-promoting factors. This study focuses on the identification of differentially expressed (DE) miRNAs and mRNAs through next-generation sequencing of small RNAs and transcriptomes in TSCC cell line and human oral keratinocytes as a control supplemented with additional expression datasets from databases, resulting into 269 DE miRNAs and 2094 DE genes. The miRNA target prediction followed by pathway enrichment analysis unveiled miR-128-MAP2K7, an unlearned interacting miRNA-target pair in TSCC. From our qRT-PCR study, we observed that miR-128 was poorly expressed, whereas MAP2K7 showed reverse expression in TSCC. Further, our cell viability, wound healing, cell cycle, and apoptosis assays revealed that miR-128 downturn the proliferation and metastasis of the TSCC cells followed by arresting the cells at G0/G1 phase. Upon transient overexpression of miR-128, we noticed upregulation of E-cadherin and suppression of N-cadherin, Vimentin, MMP2, and MMP9 expression indicating the reversal of mesenchymal phenotypes to epithelial phenotypes (EMT). Moreover, miR-128 diminishes the MAP2K7 expression by target regulation as observed from qRT-PCR, and dual-luciferase assay. To conclude, our study reveals that miR-128 negatively regulates MAP2K7 and inhibits EMT, invasion, and migration in TSCC.