BCAT1 overexpression regulates proliferation and c‑Myc/GLUT1 signaling in head and neck squamous cell carcinoma

BCAT1 promotes cell proliferation, migration, and invasion via the PI3K-Akt signaling pathway in oral squamous cell carcinoma

OBJECTIVES

To analyze the expression, biological function of branched chain amino-acid transaminase 1 (BCAT1) in oral squamous cell carcinoma (OSCC).

MATERIALS AND METHODS

Real-time PCR and immunohistochemistry were used to analyze the expression of BCAT1 protein in OSCC and normal oral tissues. Based on the clinicopathological information of patients, the relationship between the expression of BCAT1 protein and other clinicopathological factors was analyzed. Real-time PCR and western blot assays were used to analyze the expression of BCAT1 gene and protein in normal human oral keratinocytes (HOK) and human OSCC cells, respectively. After BCAT1 overexpression or knockdown, the proliferation, cell cycle, migration, and invasion of human OSCC cells were analyzed by CCK8, flow cytometry, wound healing, and transwell invasion assays, respectively. After adding the BCAT1 inhibitor EGR240 to OSCC cells, the changes in cell proliferation, migration, and invasion ability in OSCC cells were analyzed. Based on the TCGA database, the involved signal pathway in BCAT1-related and BCAT1-binding genes was obtained for Kyoto Encyclopedia of Genes and Genomes (KEGG) analysis, verified by western blot assays. After inhibiting PI3K, the effect of BCAT1 on the expression of the downstream phosphorylated protein of the PI3K-Akt signaling pathway was analyzed by western blot assays. The relationship between the expression of BCAT1 and EMT-related protein of OSCC cells was also analyzed.

RESULTS

The expression of BCAT1 gene and protein were upregulated in OSCC tissue, which positively correlated with the pathological grade of patients with OSCC. Compared with normal oral keratinocytes, BCAT1 gene and protein were upregulated in OSCC cells. BCAT1 overexpression promoted the proliferation, migration, and invasion of OSCC cells. BCAT1 knockdown or inhibition could reduce the proliferation, migration, and invasion abilities of OSCC cells. The results of bioinformatics analysis and Western bolt showed that BCAT1 could regulate the activation of PI3K-Akt signaling pathway, and promote epithelial-mesenchymal transition (EMT) of OSCC cells.

CONCLUSIONS

BCAT1 could promote the proliferation, migration, and invasion of OSCC cells via PI3K-Akt signaling pathway, which is a potential therapeutic target for OSCC.

Glucose Metabolism and Glucose Transporters in Head and Neck Squamous Cell Carcinoma

Head and neck squamous cell carcinoma ranks seventh globally in malignancy prevalence, with persistent high mortality rates despite treatment advancements. Glucose, pivotal in cancer metabolism via the Warburg effect, enters cells via glucose transporters, notably GLUT proteins. Glycolysis, aerobic oxidation, and the pentose phosphate pathway in glucose metabolism significantly impact HNSCC progression. HNSCC exhibits elevated expression of glucose metabolism enzymes and GLUT proteins, correlating with prognosis. Heterogeneity in HNSCC yields varied metabolic profiles, influenced by factors like HPV status and disease stage. This review highlights glucose metabolism's role and potential as therapeutic targets and cancer imaging tracers in HNSCC.

Knockdown of PRMT1 suppresses the malignant biological behavior of osteosarcoma cells and increases cisplatin sensitivity via c-Myc-mediated BCAT1 downregulation

Increasing evidence indicated that protein arginine methyltransferase-1 (PRMT1) is an oncogene in multiple malignant tumors, including osteosarcoma (OS). The aim of this study was to investigate the underlying mechanism of PRMT1 in OS. The effects of PRMT1 or BCAT1, branched-chain amino acid transaminase 1 (BCAT1) on OS cell proliferation, invasion, autophagy, and apoptosis in vitro were examined. Moreover, molecular control of PRMT1 on c-Myc or transactivation of BCAT1 on c-Myc was assessed by chromatin immunoprecipitation and quantitative reverse transcription PCR assays. The effects of PRMT1 in vivo were examined with a xenograft tumor model. The results showed that PRMT1 was potently upregulated in OS tissues and cells. Upregulation of PRMT1 markedly increased OS cell proliferation and invasion in vitro and reduced cell apoptosis, whereas PRMT1 silencing showed the opposite effects. Cisplatin, one of the most effective chemotherapeutic drugs, improved cell survival rate by inducing the expression of PRMT1 to downregulate the cisplatin sensitivity. Meanwhile, the cisplatin-induced upregulation of PRMT1 expression caused dramatically autophagy induction and autophagy-mediated apoptosis by inactivating the mTOR signaling pathway, which could be reversed by 3-methyladenine, an autophagy inhibitor, or PRMT1 silencing. PRMT1 could activate c-Myc transcription and increase c-Myc-mediated expression of BCAT1. Furthermore, BCAT1 overexpression counteracted the effects of PRMT1 knockdown on cell proliferation, invasion, and apoptosis. Of note, deficiency of PRMT1 suppressed tumor growth in vivo. PRMT1 facilitated the proliferation and invasion of OS cells, inhibited cell apoptosis, and decreased chemotherapy sensitivity through c-Myc/BCAT1 axis, which may become potential target in treating OS.

Role and clinical significance of immunogenic cell death biomarkers in chemoresistance and immunoregulation of head and neck squamous cell carcinoma

Head and neck squamous cell carcinoma (HNSCC) is one of the most common malignancies in the whole world, with little improvement in the 5-year survival rate due to the occurrence of chemoresistance. With the increasing interests in tumor immune microenvironment, immunogenic cell death (ICD)-induced chemotherapy has shown promising results in enhancing sensitivity to immune checkpoint inhibitors (ICI) and improving the efficiency of tumor immunotherapy. This review summarizes the role of key ICD biomarkers and their underlying molecular mechanisms in HNSCC chemoresistance. The results showed that ICD initiation could significantly improve the survival and prognosis of patients. ICD and its biomarker could also serve as molecular markers for tumor diagnosis and prognosis. Moreover, key components of DAMPs including CALR, HGMB1, and ATP are involved in the regulation of HNSCC chemo-sensitivity, confirming that the key biomarkers of ICD can also be developed into new targets for regulating HNSCC chemoresistance. This review clearly illustrates the theoretical basis for the hypothesis that ICD biomarkers are therapeutic targets involved in HNSCC progression, chemoresistance, and even immune microenvironment regulation. The compilation and investigation may provide new insights into the molecular therapy of HNSCC.

Prognostic impact of FLT3-ITD mutation on NPM1+ acute myeloid leukaemia patients and related molecular mechanisms

The prognosis of acute myeloid leukaemia (AML) patients carrying NPM1 mutations is significantly worse when accompanied by FLT3-ITD mutations. However, accurate quantitative detection of FLT3-ITD mutations remains challenging. To identify a novel biomarker in NPM1+ FLT3-ITD+ AML patients for more accurate stratification, we analysed the differential gene expression between the NPM1+ FLT3-ITD+ and NPM1+ FLT3-ITD- groups in five public AML datasets and identified a biomarker by taking the intersection of differentially expressed genes. We validated this biomarker in bone marrow samples from NPM1+ AML patients at the Peking University Institute of Haematology and analysed its prognostic significance. BCAT1 expression was higher in the NPM1+ FLT3-ITD+ group than in the NPM1+ FLT3-ITD- group in all seven cohorts. BCAT1 was able to predict the prognosis of NPM1+ FLT3-ITD+ AML patients, and its predictive ability was superior to that of the FLT3-ITD allelic ratio (AR). FLT3-targeted inhibitor quizartinib reduced BCAT1 expression. BCAT1 knockdown using lentiviral vectors led to the downregulation of MYC expression. Thus, we identified BCAT1 as a novel biomarker for NPM1+ FLT3-ITD+ AML patients. The FLT3-ITD/BCAT1/MYC signalling pathway may play a biological role in promoting the occurrence and development of AML in FLT3-ITD+ cell lines.

LncRNA THUMPD3-AS1 promotes invasion and EMT in gastric cancer by regulating the miR-1297/BCAT1 pathway

Long noncoding RNA (lncRNA) plays crucial roles in the development of gastric cancer (GC); however, studies of their mechanisms of action are needed to determine their clinical value. The aim of this study is to explore the effects and mechanisms of THUMPD3-AS1 in GC. Elevated levels of THUMPD3-AS1 were observed in GC and demonstrated a significant positive correlation with poor prognosis. Functionally, THUMPD3-AS1 promoted GC cell proliferation, migration, invasion, and epithelial-mesenchymal transition (EMT) and induced tumor growth in vivo. THUMPD3-AS1 exerts its regulatory function on BCAT1 through competitive binding with miR-1297. Further investigations confirmed that both THUMPD3-AS1 and miR-1297 interact with BCAT1. These findings suggest that THUMPD3-AS1 promotes GC invasion and EMT by regulating the miR-1297/BCAT1 pathway, indicating that THUMPD3-AS1 may serve as a biomarker and therapeutic target for GC.

MYC disrupts transcriptional and metabolic circadian oscillations in cancer and promotes enhanced biosynthesis

The molecular circadian clock, which controls rhythmic 24-hour oscillation of genes, proteins, and metabolites in healthy tissues, is disrupted across many human cancers. Deregulated expression of the MYC oncoprotein has been shown to alter expression of molecular clock genes, leading to a disruption of molecular clock oscillation across cancer types. It remains unclear what benefit cancer cells gain from suppressing clock oscillation, and how this loss of molecular clock oscillation impacts global gene expression and metabolism in cancer. We hypothesized that MYC or its paralog N-MYC (collectively termed MYC herein) suppress oscillation of gene expression and metabolism to upregulate pathways involved in biosynthesis in a static, non-oscillatory fashion. To test this, cells from distinct cancer types with inducible MYC were examined, using time-series RNA-sequencing and metabolomics, to determine the extent to which MYC activation disrupts global oscillation of genes, gene expression pathways, and metabolites. We focused our analyses on genes, pathways, and metabolites that changed in common across multiple cancer cell line models. We report here that MYC disrupted over 85% of oscillating genes, while instead promoting enhanced ribosomal and mitochondrial biogenesis and suppressed cell attachment pathways. Notably, when MYC is activated, biosynthetic programs that were formerly circadian flipped to being upregulated in an oscillation-free manner. Further, activation of MYC ablates the oscillation of nutrient transporter proteins while greatly upregulating transporter expression, cell surface localization, and intracellular amino acid pools. Finally, we report that MYC disrupts metabolite oscillations and the temporal segregation of amino acid metabolism from nucleotide metabolism. Our results demonstrate that MYC disruption of the molecular circadian clock releases metabolic and biosynthetic processes from circadian control, which may provide a distinct advantage to cancer cells.

BCAT1, as a prognostic factor for HCC, can promote the development of liver cancer through activation of the AKT signaling pathway and EMT

More and more studies have shown that Branched chain amino acid transaminase 1 (BCAT1) is involved in the occurrence and development of a variety of tumors. However, the mechanism of its occurrence and development in hepatocellular carcinoma (HCC) remains unclear. Here, we demonstrated the relationship between BCAT1 and AKT signaling pathway, as well as EMT, and the clinical significance of BCAT1 by using BCAT1 expression in 5 cell lines and 113 liver cancer and non-liver cancer tissue samples. The results showed that the expression of AKT was positively correlated with BCAT1 in HCC tissues, and BCAT1 could promote the progression of HCC cells through the AKT signaling pathway. Clinical analysis and Bioinformatics technology analysis revealed that BCAT1 was correlated with poor prognosis, and BCAT1 expression in the HCC tissues was evidently correlated with tumor number, vascular invasion, Edmondson grade and TNM stage (P < 0.05). In vitro studies showed that BCAT1 increased the invasion and migration of in MHCC-97H cells a d Huh7 cells. By inhibiting the expression of the BCAT1 gene, we detected the corresponding changes in the expression levels of Twist, E-cadherin and Vimentin, confirming that BCAT1 may promote the invasion and migration of HCC cells through epithelial-mesenchymal transformation (EMT). Overall, BCAT1 can activate AKT signaling pathway and EMT to promote the development and metastasis of HCC cells. this study may provide new ideas and directions for cancer diagnosis and treatment.

Differential expression pattern, bioinformatics analysis, and validation of circRNA and mRNA in patients with arteriosclerosis

Background

Lower limb arteriosclerosis obliterans (ASO) is the formation of atherosclerotic plaques in lower limb arteries, leading to vascular stenosis and occlusion, and is a major factor leading to lower limb amputation. The ASO seriously endangers the physical and mental health of patients. As living standards improve, the disease tends to occur in younger patients, and the incidence keeps increasing year by year. The circular RNAs (circRNAs) have been found to be tissue-specific, and they play an important role in a variety of diseases, but there are few studies on the pathogenic role and expression of circRNAs in ASOs.

Method

Three diseased arteries from patients with ASO and three healthy arteries from healthy donors were collected for second-generation sequencing, and the pathogenic pathways and possible pathogenic circRNAs related to ASO were screened through bioinformatics analysis. PCR and agarose gel electrophoresis were used to validate the sequencing results. The expression of circRNA-0008706 in human arterial smooth muscle cells (HASMCs) was knocked down using siRNA technology to explore its function.

Result

We identified 480 differentially expressed (DE) circRNAs and 2,997 DEmRNAs. Functional analysis revealed that epithelial-to-mesenchymal transition (EMT), lipid transport, regulation of extracellular matrix disassembly, regulation of cardiac muscle cell proliferation, branched-chain amino acid biosynthetic process, and positive regulation of cell growth and migration were enriched. Based on our previous microRNA array results, we constructed an ASO disease-specific competing endogenous (ceRNA) network. After validation, circRNA-0008706 was selected for functional analysis. Knockdown of circRNA-0008706 significantly suppressed the proliferation and migration phenotype of HASMCs and decreased the BCAT1 expression, which may be due to the specific binding of circRNA-0008706 to microRNA-125b-5p.

Conclusion

This study is the first to compare the circRNA and mRNA expression profiles of ASOs and healthy arterial specimens and to construct a disease-specific ceRNA network for ASOs. This study may provide a new therapeutic target for ASO.

The mechanism of branched-chain amino acid transferases in different diseases: Research progress and future prospects

It is well known that the enzyme catalyzes the first step of branched-chain amino acid (BCAA) catabolism is branched-chain amino transferase (BCAT), which is involved in the synthesis and degradation of leucine, isoleucine and valine. There are two main subtypes of human branched chain amino transferase (hBCAT), including cytoplasmic BCAT (BCAT1) and mitochondrial BCAT (BCAT2). In recent years, the role of BCAT in tumors has attracted the attention of scientists, and there have been continuous research reports that BCAT plays a role in the tumor, Alzheimer's disease, myeloid leukaemia and other diseases. It plays a significant role in the growth and development of diseases, and new discoveries about this gene in some diseases are made every year. BCAT usually promotes cancer proliferation and invasion by activating the phosphatidylinositol 3-kinase/protein kinase B/mammalian target of rapamycin pathway and activating Wnt/β-catenin signal transduction. This article reviews the role and mechanism of BCAT in different diseases, as well as the recent biomedical research progress. This review aims to make a comprehensive summary of the role and mechanism of BCAT in different diseases and to provide new research ideas for the treatment, prognosis and prevention of certain diseases.

Identification of natural compounds tubercidin and lycorine HCl against small-cell lung cancer and BCAT1 as a therapeutic target

Although small-cell lung cancer (SCLC) accounts for a small fraction of lung cancer cases (~15%), the prognosis of patients with SCLC is poor with an average overall survival period of a few months without treatment. Current treatments include standard chemotherapy, which has minimal efficacy and a newly developed immunotherapy that thus far, benefits a limited number of patients. In the current study, we screened a natural product library and identified 5 natural compounds, in particular tubercidin and lycorine HCl, that display prominent anti-SCLC activities in vitro and in vivo. Subsequent RNA-sequencing and functional validation assays revealed the anti-SCLC mechanisms of these new compounds, and further identified new cellular factors such as BCAT1 as a potential therapeutic target with clinical implication in SCLC patients. Taken together, our study provides promising new directions for fighting this aggressive lung cancer.

BCAT1: A risk factor in multiple cancers based on a pan-cancer analysis

Background

Although branched chain amino acid transaminase 1 (BCAT1) has been identified to play an essential role in multiple tumors, no studies on its role in pan‐cancer have been consulted before.

Methods

The study comprehensively analyzes the expression, potential mechanisms, and clinical significance of BCAT1 in pan‐cancer through utilizing 16,847 samples, providing novel clues for the treatment of cancers. A Kruskal–Wallis test and the Wilcoxon rank‐sum and signed‐rank tests were applied to investigate diverse BCAT1 expression between various groups (e.g., cancer tissues versus normal tissues). Spearman’s rank correlation coefficient was used in all correlation analyses in the study. Cox analyses and Kaplan‐Meier curves were utilized to identify the prognosis significance of BCAT1 expression in cancers. The significance of BCAT1 expression in differentiating cancer and non‐cancer tissues was explored via the area under the receiver operating characteristic curves (AUC).

Results

The differential expression of BCAT1 was detected in various cancers (p < 0.05), which is relevant to some DNA methyltransferases expression. BCAT1 expression was associated with mismatch repair gene expression, immune checkpoint inhibitors expression, microsatellite instability, and tumor mutational burden in some cancers, indicating its potential in immunotherapy. BCAT1 expression showed prognosis significance and played a risk role in multiple cancers (hazard ratio > 0, p < 0.05). BCAT1 expression also demonstrated conspicuous ability to distinguish some cancers tissues from their normal tissues (AUC > 0.7), indicating its potential to detect cancers. Further analyses on head and neck squamous cell carcinoma certified upregulated BCAT1 expression at both mRNA and protein levels in this disease based on in‐house tissue microarrays and multicenter datasets.

Conclusions

For the first time, the research comprehensively demonstrates the overexpression of BCAT1 in pan‐cancer, which improves the understanding of the pathogenesis of BCAT1 in pan‐cancer. Upregulated BCAT1 expression represented a poor prognosis for cancers patients, and it serves as a potential marker for cancer immunotherapy.

An overview of branched-chain amino acid aminotransferases: functional differences between mitochondrial and cytosolic isozymes in yeast and human

Branched-chain amino acid aminotransferase (BCAT) catalyzes bidirectional transamination in the cell between branched-chain amino acids (BCAAs; valine, leucine, and isoleucine) and branched-chain α-keto acids (BCKAs; α-ketoisovalerate, α-ketoisocaproate, and α-keto-β-methylvalerate). Eukaryotic cells contain two types of paralogous BCATs: mitochondrial BCAT (BCATm) and cytosolic BCAT (BCATc). Both isozymes have identical enzymatic functions, so they have long been considered to perform similar physiological functions in the cells. However, many studies have gradually revealed the differences in physiological functions and regulatory mechanisms between them. In this article, we present overviews of BCATm and BCATc in both yeast and human. We also introduce BCAT variants found natively or constructed artificially, which could have significant implications for research into the relationship between the primary structures and protein functions of BCATs. KEY POINTS: • BCAT catalyzes bidirectional transamination in the cell between BCAAs and BCKAs. • BCATm and BCATc are different in the metabolic roles and regulatory mechanisms. • BCAT variants offer insight into a relationship between the structure and function.