Cellular Oncology最新文献

Purpose: The human AlkB homolog (ALKBH) dioxygenase superfamily plays a crucial role in gene regulation and is implicated in cancer progression. Under hypoxic conditions, hypoxia-inducible factors (HIFs) dynamically regulate methylation by controlling various dioxygenases, thereby modulating gene expression. However, the role of hypoxia-responsive AlkB dioxygenase remains unclear.

Methods: The molecular events were examined using real-time PCR and Western blot analysis. Tumor cell aggressiveness was evaluated through migration, invasion, MTT, trypan blue exclusion, and colony formation assays. In vivo metastatic models and xenograft experiments were conducted to evaluate tumor progression.

Results: Here, we examined the expression of the ALKBH superfamily under hypoxic conditions and found that ALKBH4 expression was negatively regulated by hypoxia. Knockdown of ALKBH4 enhanced the epithelial-mesenchymal transition (EMT), cell migration, invasion, and growth in vitro. The silencing of ALKBH4 enhanced metastatic ability and tumor growth in vivo. Conversely, overexpression of ALLKBH4 reversed these observations. Furthermore, overexpression of ALKBH4 significantly reversed hypoxia/HIF-1α-induced EMT, cell migration, invasion, tumor metastasis, and tumorigenicity. Notably, high expression of ALKBH4 was associated with better outcomes in head and neck cancer and breast cancer patients. Enrichment analysis also revealed that ALKBH4 was negatively enriched in hypoxia-related pathways. Clinically, a negative correlation between ALKBH4 and HIF-1α protein expression has been observed in tissues from both head and neck cancers and breast cancers.

Conclusion: These findings collectively suggest that ALKBH4 acts as a tumor suppressor and holds therapeutic potential for hypoxic tumors.

Purpose: Pancreatic ductal adenocarcinoma (PDAC) is one of the most lethal cancers and several studies demonstrate that STAT3 has critical roles throughout the course of PDAC pathogenesis.

Methods: TCGA, microarray, and immunohistochemistry data from a PDAC cohort were used for clinical analyses. Panc89 cells with ADAM8 knockout, re-expression of ADAM8 mutants, and Panc1 cells overexpressing ADAM8 were generated. Gene expression analyses of ADAM8, STAT3, long non-coding (lnc) RNA NEAT1, miR-181a-5p and ICAM1 were performed by quantitative PCR. Subcellular fractionation quantified NEAT1 expression in cytoplasm and nucleus of PDAC cell lines. Cell proliferation, scratch, and invasion assays were performed to detect growth rate, migration and invasion capabilities of cells. Gain and loss of function experiments were carried out to investigate the biological effects of lncRNA NEAT1 and miR-181a-5p on PDAC cells and downstream genes. Dual-luciferase reporter gene assay determined interaction and binding sites of miR-181a-5p in lncRNA NEAT1. Pull down assays, RNA binding protein immunoprecipitation (RIP), and ubiquitination assays explored the molecular interaction between lncRNA NEAT1 and STAT3.

Results: High ADAM8 expression causes aberrant STAT3 signaling in PDAC cells and is positively correlated with NEAT1 expression. NEAT1 binding to STAT3 was confirmed and prevents STAT3 degradation in the proteasome as increased degradation of STAT3 was observed in ADAM8 knockout cells and cells treated with bortezomib. Furthermore, miRNA-181a-5p regulates NEAT1 expression by direct binding to the NEAT1 promoter.

Conclusion: ADAM8 regulates intracellular STAT3 levels via miR-181a-5p and NEAT1 in pancreatic cancer.

Purpose: Although most of chronic myeloid leukemia (CML) patients can be effectively treated by the tyrosine kinase inhibitors (TKIs), such as Imatinib, TKI-resistance still occurs in approximately 15-17% of cases. Although many studies indicate that branched chain amino acid (BCAA) metabolism may contribute to the TKI resistance in CML, the detailed mechanisms remains largely unknown.

Method: The cell proliferation, colony formation and in vivo transplantation were used to determined the functions of BCAT1 in leukemogenesis. Quantitative real-time PCR (RT-PCR), western blotting, RNA sequencing, BCAA stimulation in vitro were applied to characterize the underlying molecular mechanism that control the leukemogenic activity of BCAT1-knockdown cells.

Results: In this report, we revealed that branched chain amino acid transaminase 1 (BCAT1) is highly enriched in both mouse and human TKI-resistant CML cells. Leukemia was almost completely abrogated upon BCAT1 knockdown during transplantation in a BCR-ABL^T315I-induced murine TKI-resistant CML model. Moreover, knockdown of BCAT1 led to a dramatic decrease in the proliferation of TKI-resistant human leukemia cell lines. BCAA/BCAT1 signaling enhanced the phosphorylation of CREB, which is required for maintenance of TKI-resistant CML cells. Importantly, blockade of BCAA/BCAT1 signaling efficiently inhibited leukemogenesis both in vivo and in vitro.

Conclusions: These findings demonstrate the role of BCAA/BCAT1 signaling in cancer development and suggest that targeting BCAA/BCAT1 signaling is a potential strategy for interfering with TKI-resistant CML.

Purpose: Glioblastomas (GBMs) are highly treatment-resistant and aggressive brain tumors. 2OHOA, which is currently running a phase IIB/III clinical trial for newly diagnosed GBM patients, was developed in the context of melitherapy. This therapy focuses on the regulation of the membrane's structure and organization with the consequent modulation of certain cell signals to revert the pathological state in several disorders. Notch signaling has been associated with tumorigenesis and cell survival, potentially driving the pathogenesis of GBM. The current study aims to determine whether 2OHOA modulates the Notch pathway as part of its antitumoral mechanism.

Methods: 2OHOA's effect was evaluated on different components of the pathway by Western blot, Q-PCR, and confocal microscopy. Notch receptor processing was analyzed by subcellular fractionation and colocalization studies. Furin activity was evaluated under cleavage of its substrate by fluorescence assays and its binding affinity to 2OHOA was determined by surface plasmon resonance.

Results: We found that 2OHOA inhibits Notch2 and Notch3 signaling by dual mechanism. Notch2 inhibition is unleashed by impairment of its processing through the inactivation of furin activity by physical association. Instead, Notch3 is transcriptionally downregulated leading to a lower activation of the pathway. Moreover, we also found that HES1 overexpression highlighted the relevance of this pathway in the 2OHOA pharmacological efficacy.

Conclusion: These findings report that the inhibition of Notch signaling by 2OHOA plays a role in its anti-tumoral activity, an effect that may be driven through direct inhibition of furin, characterizing a novel target of this bioactive lipid to treat GBM.

Glioblastoma is the commonest and deadliest primary brain tumor. Glioblastoma is characterized by significant intra- and inter-tumoral heterogeneity, resistance to treatment and dismal prognoses despite decades of research in understanding its biological underpinnings. Encompassed within this heterogeneity and therapy resistance are severely dysregulated programmed cell death pathways. Glioblastomas recapitulate many neurodevelopmental and neural injury responses; in addition, glioblastoma cells are composed of multiple different transformed versions of CNS cell types. To obtain a greater understanding of the features underlying cell death regulation in glioblastoma, it is important to understand the control of cell death within the healthy CNS during homeostatic and neurodegenerative conditions. Herein, we review apoptotic control within neural stem cells, astrocytes, oligodendrocytes and neurons and compare them to glioblastoma apoptotic control. Specific focus is paid to the Inhibitor of Apoptosis proteins, which play key roles in neuroinflammation, CNS cell survival and gliomagenesis. This review will help in understanding glioblastoma as a transformed version of a heterogeneous organ composed of multiple varied cell types performing different functions and possessing different means of apoptotic control. Further, this review will help in developing more glioblastoma-specific treatment approaches and will better inform treatments looking at more direct brain delivery of therapeutic agents.

Purpose: Immunotherapy using PD-L1 blockade is effective in only a small group of cancer patients, and resistance is common. This emphasizes the importance of understanding the mechanisms of cancer immune evasion and resistance.

Methods: A genome-scale CRISPR-Cas9 screen identified Bap1 as a regulator of PD-L1 expression. To measure tumor size and survival, tumor cells were subcutaneously injected into both syngeneic WT mice and immunocompromised mice. The phenotypic and transcriptional characteristics of Bap1-deleted tumors were examined using flow cytometry, RNA-seq, and CUT&Tag-seq analysis.

Results: We found that loss of histone deubiquitinase Bap1 in cancer cells activates a cDC1-CD8⁺ T cell-dependent anti-tumor immunity. The absence of Bap1 leads to an increase in genes associated with anti-tumor immune response and a decrease in genes related to immune evasion. As a result, the tumor microenvironment becomes inflamed, with more cDC1 cells and effector CD8⁺ T cells, but fewer neutrophils and regulatory T cells. We also found that the elimination of Bap1-deleted tumors depends on the tumor MHCI molecule and Fas-mediated CD8⁺ T cell cytotoxicity. Our analysis of TCGA data further supports these findings, showing a reverse correlation between BAP1 expression and mRNA signatures of activated DCs and T-cell cytotoxicity in various human cancers.

Conclusion: The histone deubiquitinase Bap1 could be used as a biomarker for tumor stratification and as a potential therapeutic target for cancer immunotherapies.

The complex and continuously evolving features of the tumor microenvironment, varying between tumor histotypes, are characterized by the presence of host cells and tumor cells embedded in a milieu shaped by hypoxia and low pH, resulting from the frequent imbalance between vascularity and tumor cell proliferation. These microenvironmental metabolic stressors play a crucial role in remodeling host cells and tumor cells, contributing to the stimulation of cancer cell heterogeneity, clonal evolution, and multidrug resistance, ultimately leading to progression and metastasis. The extracellular vesicles (EVs), membrane-enclosed structures released into the extracellular milieu by tumor/host cells, are now recognized as critical drivers in the complex intercellular communication between tumor cells and the local cellular components in a hypoxic/acidic microenvironment. Understanding the intricate molecular mechanisms governing the interactions between tumor and host cells within a hypoxic and acidic microenvironment, triggered by the release of EVs, could pave the way for innovative strategies to disrupt the complex interplay of cancer cells with their microenvironment. This approach may contribute to the development of an efficient and safe therapeutic strategy to combat cancer progression. Therefore, we review the major findings on the release of EVs in a hypoxic/acidic tumor microenvironment to appreciate their role in tumor progression toward metastatic disease.

Purpose: This study investigates the role and effectiveness of the epidermal growth factor receptor (EGFR) tyrosine kinase inhibitor (TKI) in oral cancer, focusing on the clinical relevance of EGFR and myeloid cell leukemia-1 (Mcl-1) in head and neck cancers (HNCs). It aims to explore the molecular mechanism of afatinib, a TKI, in treating human oral cancer.

Methods: We conducted an in silico analysis using databases like The Cancer Genome Atlas, Gene Expression Omnibus, and Clinical Proteomic Tumor Analysis Consortium, along with immunohistochemistry staining, to study EGFR and Mcl-1 expression in HNCs. For investigating afatinib's anticancer properties, we performed various in vitro and in vivo analyses, including trypan blue exclusion assay, Western blotting, 4'-6-diamidino-2-phenylindole staining, flow cytometry, quantitative real-time PCR, Mitochondrial membrane potential assay, overexpression vector construction, transient transfection, and a tumor xenograft model.

Results: Higher expression levels of EGFR and Mcl-1 were observed in HNC patient tissues compared to normal tissues, with their co-expression significantly linked to poor prognosis. There was a strong correlation between EGFR and Mcl-1 expressions in oral cancer patients. Afatinib treatment induced apoptosis and suppressed Mcl-1 in oral cancer cell lines without the EGFR T790M mutation. The mechanism of afatinib-induced apoptosis involved the EGFR/mTOR/Mcl-1 axis, as shown by the effects of mTOR activator MHY1485 and inhibitor rapamycin. Afatinib also increased Bim expression, mitochondrial membrane permeabilization, and cytochrome c release. It significantly lowered tumor volume without affecting body, liver, and kidney weights.

Conclusion: Afatinib, targeting the EGFR/mTOR/Mcl-1 axis, shows promise as a therapeutic strategy for oral cancer, especially in patients with high EGFR and Mcl-1 expressions.