Interaction of the tumor suppressor SMAD4 and WNT signaling in progression to oral squamous cell carcinoma

METTL3 promotes oral squamous cell carcinoma by regulating miR-146a-5p/SMAD4 axis

N6-methyladenosine (m6A), one of the most prominent and reversible internal modifications of eukaryotic RNAs, has emerged as a critical regulator of gene expression in various cancers including oral squamous cell carcinoma (OSCC), wherein it shapes the tumor-specific epitranscriptomic gene-regulatory networks. METTL3, the primary m6A RNA methyltransferase, is significantly upregulated in OSCC cells leading to increased global m6A levels. Interestingly, METTL3 positively regulates miRNA biogenesis by modulating the processing of primary miRNAs in a m6A-dependent manner. We identified miR-146a-5p, an oncogenic miRNA as one of the METTL3-regulated miRNAs in OSCC. METTL3-depletion or inhibition of its catalytic activity leads to a reduction of miR-146a-5p and an appreciable accumulation of primary miR-146a in OSCC cells. Functional assays examining the effects of miR-146a-5p inhibition or overexpression confirm its oncogenic role in OSCC pathophysiology. Further, SMAD4, a central transducer in TGF-β signaling, was identified as a miR-146a-5p target. In OSCC cells, SMAD4-depletion exacerbates the oncogenic traits, whereas its overexpression exerts the opposite effect. Additionally, METTL3-depletion dysregulates SMAD4-regulated genes suggesting its potential involvement in SMAD4-dependent TGF-β signaling. Taken together, we report that METTL3, an oncogene regulates the expression of SMAD4, a tumor-suppressor via miR-146a-5p, thus unveiling a novel regulatory axis of METTL3/miR-146a-5p/SMAD4 in OSCC, which can potentially have therapeutic implications.

HKDC1 promotes colorectal cancer progression by regulating RCOR1 expression to activate the Wnt/β-catenin pathway, enhancing proliferation, migration, and epithelial-mesenchymal transition

HKDC1 (hexokinase domain containing 1) is recognized as an oncogene in various cancers, yet its role in colorectal cancer (CRC) remains unclear. This study aims to explore HKDC1 expression in CRC and its effects on tumor growth, migration, glycolysis, and EMT, as well as the underlying molecular mechanisms. Using TIMER2.0 and TCGA databases, we analyzed HKDC1 expression across multiple cancers and evaluated its prognostic value via Kaplan-Meier survival analysis. HKDC1 expression in CRC tissues was validated through western blotting, immunohistochemistry, and qRT-PCR, and its correlation with patient prognosis was assessed. Functional experiments involving HKDC1 knockdown and overexpression were performed to examine their impact on CRC cell proliferation, migration, apoptosis, and the cell cycle. Coimmunoprecipitation, immunofluorescence, and mass spectrometry identified HKDC1's interaction with RCOR1, demonstrating its regulation of the Wnt/β-catenin pathway to promote CRC progression. High HKDC1 expression in CRC tissues correlated with poor patient prognosis. Knockdown of HKDC1 significantly reduced cell proliferation and migration, induced G1 phase arrest, and promoted apoptosis, whereas HKDC1 overexpression had the opposite effects. Additionally, HKDC1 promoted EMT and glycolysis through the Wnt/β-catenin signaling pathway. In vivo, HKDC1 knockdown inhibited tumor growth, while overexpression accelerated tumor progression. This study is the first to demonstrate that HKDC1 enhances CRC proliferation, migration, glycolysis, and EMT by modulating RCOR1 and activating the Wnt/β-catenin pathway. These findings suggest that HKDC1 could serve as a potential therapeutic target and prognostic marker for CRC, offering new insights for personalized treatment strategies.