Bicarbonate transporter SLC4A7 promotes EMT and metastasis of HNSCC by activating the PI3K/AKT/mTOR signaling pathway

MLN4924 Suppresses head and neck squamous cell carcinoma progression by inactivating the mTOR signaling pathway via the NEDD8/CUL4/TSC2 axis

Head and neck squamous cell carcinoma (HNSCC) is an aggressive cancer with a five-year survival rate below 50 %. Standard treatments for HNSCC include surgery, radiotherapy, chemotherapy, and targeted therapies, but they still have significant limitations. Neddylation, a post-translational modification involving the attachment of NEDD8 (neural precursor cells expressed developmentally down-regulated 8) to proteins, is frequently dysregulated in HNSCC, thereby promoting tumor growth. MLN4924, also known as Pevonedistat, is a Neddylation inhibitor that has shown promise in suppressing HNSCC cell proliferation and invasion, establishing it as a potential therapeutic option. However, its precise molecular mechanism remains unclear. This study aims to investigate the mechanism of MLN4924 in HNSCC. This study examined the effects of MLN4924 on HNSCC and its associated molecular pathways. Bioinformatic analysis indicated that NEDD8, a critical component of the Neddylation pathway, is linked to poor prognosis and the mTOR (mammalian target of rapamycin) signaling pathway in HNSCC. MLN4924 significantly suppressed cell migration, invasion, and the epithelial-mesenchymal transition (EMT) pathway, and downregulated NEDD8 expression. Mechanistic studies demonstrated that MLN4924 inhibited the binding of NEDD8 to cullin4 (CUL4) and prevented the Neddylation of tuberous sclerosis complex 2 (TSC2), leading to the inactivation of the mTOR pathway. These findings were confirmed in vivo, where MLN4924 effectively inhibited tumor growth. Overall, MLN4924 disrupted Neddylation pathway and stabilized TSC2, thereby inactivating the mTOR pathway. The study provided a theoretical basis for the clinical potential of MLN4924 in improving treatment outcomes for HNSCC patients, offering a novel strategy for addressing this challenging disease.

SAR1A Induces Cell Growth and Epithelial-Mesenchymal Transition Through the PI3K/AKT/mTOR Pathway in Head and Neck Squamous Cell Carcinoma: An In Vitro and In Vivo Study

OBJECTIVES

Head and neck squamous cell carcinoma (HNSCC) ranks sixth globally, with a 50% five-year survival rate. SAR1A exhibits high expression levels in various tumor types, yet its specific role in HNSCC remains to be clarified.

METHODS

In vitro assays, such as CCK8, EdU, colony formation, wound-healing, transwell, and Western blotting analyses, as well as in vivo assays, such as tumor xenografts and lung metastasis models, were conducted to evaluate the impacts of SAR1A on HNSCC proliferation, migration, and invasion. Transcriptome sequencing and KEGG enrichment pathway analysis revealed evident alterations in the PI3K/AKT/mTOR(PAM) pathways. LY294002 (a PI3K/AKT inhibitor) was used to investigate the role of the PAM pathway in proliferation, migration, and invasion in HNSCC.

RESULTS

Univariate and multivariate Cox regression were conducted to screen SAR1A as a gene prognostic biomarker in HNSCC, and it was validated in the Cancer Genome Atlas (TCGA) database. Functional assays demonstrated that the depletion of SAR1A leads to suppressed proliferation, migration, and invasion of HNSCC cells. This is accompanied by a decrease in the expression of epithelial-mesenchymal transition (EMT)-related markers in HNSCC cell lines. In addition, the diminished capacities of proliferation, migration, and invasion observed in SAR1A knockdown cells were reversed upon the overexpression of SAR1A. Furthermore, RNA-seq and KEGG enrichment analysis demonstrated a significant alteration in the PAM pathway following SAR1A knockdown. LY294002 effectively mitigated the increased proliferation, migration, and invasion induced by SAR1A overexpression.

CONCLUSIONS

SAR1A facilitates HNSCC proliferation and EMT via the PI3K/AKT/mTOR pathway.

Slc4a7 Regulates Retina Development in Zebrafish

Inherited retinal degenerations (IRDs) are a group of genetic disorders characterized by the progressive degeneration of retinal cells, leading to irreversible vision loss. SLC4A7 has emerged as a candidate gene associated with IRDs, yet its mechanisms remain largely unknown. This study aims to investigate the role of slc4a7 in retinal development and its associated molecular pathogenesis in zebrafish. Morpholino oligonucleotide knockdown, CRISPR/Cas9 genome editing, quantitative RT-PCR, eye morphometric measurements, immunofluorescent staining, TUNEL assays, visual motor responses, optokinetic responses, rescue experiments, and bulk RNA sequencing were used to assess the impact of slc4a7 deficiency on retinal development. Our results demonstrated that the knockdown of slc4a7 resulted in a dose-dependent reduction in eye axial length, ocular area, and eye-to-body-length ratio. The fluorescence observations showed a significant decrease in immunofluorescence signals from photoreceptors and in mCherry fluorescence from RPE in slc4a7-silenced morphants. TUNEL staining uncovered the extensive apoptosis of retinal cells induced by slc4a7 knockdown. Visual behaviors were significantly impaired in the slc4a7-deficient larvae. GO and KEGG pathway analyses reveal that differentially expressed genes are predominantly linked to aspects of vision, ion channels, and phototransduction. This study demonstrates that the loss of slc4a7 in larvae led to profound visual impairments, providing additional insights into the genetic mechanisms predisposing individuals to IRDs caused by SLC4A7 deficiency.

The Role of the PI3K/Akt/mTOR Axis in Head and Neck Squamous Cell Carcinoma

Head and neck squamous cell carcinoma (HNSCC) is one of the most common malignancies globally, representing a significant public health problem with a poor prognosis. The development of efficient therapeutic strategies for HNSCC prevention and treatment is urgently needed. The PI3K/AKT/mTOR (PAM) signaling pathway is a highly conserved transduction network in eukaryotic cells that promotes cell survival, growth, and cycle progression. Dysfunction in components of this pathway, such as hyperactivity of PI3K, loss of PTEN function, and gain-of-function mutations in AKT, are well-known drivers of treatment resistance and disease progression in cancer. In this review, we discuss the major mutations and dysregulations in the PAM signaling pathway in HNSCC. We highlight the results of clinical trials involving inhibitors targeting the PAM signaling pathway as a strategy for treating HNSCC. Additionally, we examine the primary mechanisms of resistance to drugs targeting the PAM pathway and potential therapeutic strategies.

KDM5B promotes metastasis and epithelial-mesenchymal transition via Wnt/β-catenin pathway in squamous cell carcinoma of the head and neck

Metastasis determines clinical management decision and restricts the therapeutic efficiency in patients with squamous cell carcinoma of the head and neck (SCCHN). Epigenetic factor KDM5B serves as an oncogene in multiple cancers. However, its role in SCCHN metastasis remains unclear. Our previous study showed that KDM5B is significantly elevated in SCCHN tissue and is positively correlated with metastasis and recurrence. KDM5B overexpression predicted a poor prognosis in both disease-free survival and overall survival, which served as an independent prognostic factor in SCCHN patients. This study further investigates the exact impact of KDM5B in metastasis of SCCHN. We found that KDM5B knockdown significantly inhibits the migration and invasion of SCCHN cells both in vitro and in vivo. On the contrary, forced expression of KDM5B leads to enhanced migration and invasion, accompanied by canonical alterations of epithelial-mesenchymal transition (EMT). Mechanism investigations demonstrated that KDM5B activates Wnt/β-catenin pathway, and inhibition of Wnt/β-catenin pathway via a small molecule inhibitor iCRT-14 partially reverses the enhanced migratory and invasive ability caused by KDM5B in SCCHN cells. Together, our data indicate that KDM5B promotes EMT and metastasis via Wnt/β-catenin pathway in SCCHN, suggesting that KDM5B may be a potential therapeutic target and prognosis biomarker in SCCHN.

Increased V-ATPase activity can lead to chemo-resistance in oral squamous cell carcinoma via autophagy induction: new insights

Oral squamous cell carcinoma (OSCC) is a cancer type with a high rate of recurrence and a poor prognosis. Tumor chemo-resistance remains an issue for OSCC patients despite the availability of multimodal therapy options, which causes an increase in tumor invasiveness. Vacuolar ATPase (V-ATPase), appears to be one of the most significant molecules implicated in MDR in tumors like OSCC. It is primarily responsible for controlling the acidity in the solid tumors' microenvironment, which interferes with the absorption of chemotherapeutic medications. However, the exact cellular and molecular mechanisms V-ATPase plays in OSCC chemo-resistance have not been understood. Uncovering these mechanisms can contribute to combating OSCC chemo-resistance and poor prognosis. Hence, in this review, we suggest that one of these underlying mechanisms is autophagy induced by V-ATPase which can potentially contribute to OSCC chemo-resistance. Finally, specialized autophagy and V-ATPase inhibitors may be beneficial as an approach to reduce drug resistance to anticancer therapies in addition to serving as coadjuvants in antitumor treatments. Also, V-ATPase could be a prognostic factor for OSCC patients. However, in the future, more investigations are required to demonstrate these suggestions and hypotheses.

Co-Expression Network Analysis Unveiled lncRNA-mRNA Links Correlated to Epidermal Growth Factor Receptor-Tyrosine Kinase Inhibitor Resistance and/or Intermediate Epithelial-to-Mesenchymal Transition Phenotypes in a Human Non-Small Cell Lung Cancer Cellular Model System

We investigated mRNA-lncRNA co-expression patterns in a cellular model system of non-small cell lung cancer (NSCLC) sensitive and resistant to the epithelial growth factor receptor (EGFR) tyrosine kinase inhibitors (TKIs) erlotinib/gefitinib. The aim of this study was to unveil insights into the complex mechanisms of NSCLC targeted therapy resistance and epithelial-to-mesenchymal transition (EMT). Genome-wide RNA expression was quantified for weighted gene co-expression network analysis (WGCNA) to correlate the expression levels of mRNAs and lncRNAs. Functional enrichment analysis and identification of lncRNAs were conducted on modules associated with the EGFR-TKI response and/or intermediate EMT phenotypes. We constructed lncRNA-mRNA co-expression networks and identified key modules and their enriched biological functions. Processes enriched in the selected modules included RHO (A, B, C) GTPase and regulatory signaling pathways, apoptosis, inflammatory and interleukin signaling pathways, cell adhesion, cell migration, cell and extracellular matrix organization, metabolism, and lipid metabolism. Interestingly, several lncRNAs, already shown to be dysregulated in cancer, are connected to a small number of mRNAs, and several lncRNAs are interlinked with each other in the co-expression network.

Potential Theranostic Roles of SLC4 Molecules in Human Diseases

The solute carrier family 4 (SLC4) is an important protein responsible for the transport of various ions across the cell membrane and mediating diverse physiological functions, such as the ion transporting function, protein-to-protein interactions, and molecular transduction. The deficiencies in SLC4 molecules may cause multisystem disease involving, particularly, the respiratory system, digestive, urinary, endocrine, hematopoietic, and central nervous systems. Currently, there are no effective strategies to treat these diseases. SLC4 proteins are also found to contribute to tumorigenesis and development, and some of them are regarded as therapeutic targets in quite a few clinical trials. This indicates that SLC4 proteins have potential clinical prospects. In view of their functional characteristics, there is a critical need to review the specific functions of bicarbonate transporters, their related diseases, and the involved pathological mechanisms. We summarize the diseases caused by the mutations in SLC4 family genes and briefly introduce the clinical manifestations of these diseases as well as the current treatment strategies. Additionally, we illustrate their roles in terms of the physiology and pathogenesis that has been currently researched, which might be the future therapeutic and diagnostic targets of diseases and a new direction for drug research and development.