Long Noncoding RNA Expression Profiling Reveals Upregulation of Uroplakin 1A and Uroplakin 1A Antisense RNA 1 under Hypoxic Conditions in Lung Cancer Cells

A preventative role of nitrate for hypoxia-induced intestinal injury

BACKGROUND

Studying effective interventions for hypoxia-induced injury is crucial, particularly in high-altitude areas. Symptoms stemming from intestinal injuries have a significant impact on the health of individuals transitioning from plains to plateau regions. This research explores the effects and mechanisms of nitrate supplementation in preventing hypoxia-induced intestinal injury.

METHODS

A hypoxia survival mouse model was established using 7% O2 conditions. The intervention with 4 mM sodium nitrate (NaNO3) in drinking water commenced 7 days prior to hypoxia exposure. Weight monitoring, hematoxylin and eosin (HE) staining, transmission electron microscopy (TEM), and intestinal permeability assays were employed for physiological, histological, and functional analyses. Quantitative PCR (qPCR), Western blot, and immunofluorescence were utilized to analyze the levels of tight junction (TJ) proteins and hypoxia-inducible factor 1α (Hif 1α). RNA sequencing (RNA-seq) identified nitrate's target, and chromatin immunoprecipitation (ChIP) verified the transcriptional impact of Hif 1α on TJ proteins. Villin-cre mice infected with AAV9-FLEX-EGFP-Hif 1α were used for mechanism validation.

RESULTS

The results demonstrated that nitrate supplementation significantly alleviated small intestinal epithelial cell necrosis, intestinal permeability, disruption of TJs, and weight loss under hypoxia. Moreover, the nitrate-triggered enhancement of TJs is mediated by Hif 1α nuclear translocation and its subsequent transcriptional function. The effect of nitrate supplementation on TJs was largely attributed to the stimulation of the EGFR/PI3K/AKT/mTOR/Hif 1α signaling pathways.

CONCLUSION

Nitrate serves as a novel approach in preventing hypoxia-induced intestinal injury, acting through Hif 1α activation to promote the transcription of TJ proteins. Furthermore, our study provides new and compelling evidence for the protective effects of nitrate in hypoxic conditions, especially at high altitudes.

Long non-coding RNA (lncRNA) PVT1 in drug resistance of cancers: Focus on pathological mechanisms

According to estimates, cancer will be the leading cause of death globally in 2022, accounting for 9.6 million deaths. At present, the three main therapeutic modalities utilized to treat cancer are radiation therapy, chemotherapy, and surgery. However, during treatment, tumor cells resistant to chemotherapy may arise. Drug resistance remains a major oppose since it often leads to therapeutic failure. Furthermore, the term "acquired drug resistance" describes the situation where tumor cells already display drug resistance before undergoing chemotherapy. However, little is still known about the basic mechanisms underlying chemotherapy-induced drug resistance. The development of new technologies and bioinformatics has led to the discovery of additional genes associated with drug resistance. Long noncoding RNA plasmacytoma variant translocation 1 (PVT1) has been linked to an increased risk of cancer, according to a growing body of research. Apart from biological functions associated with cell division, development, pluripotency, and cell cycle, lncRNA PVT1 contributes significantly to the regulation of various aspects of genome function, such as transcription, splicing, and epigenetics. The article will address the mechanism by which lncRNA PVT1 influences drug resistance in cancer cells.

Comparative analysis of methods to reduce activation signature gene expression in PBMCs

Preserving the in vivo cell transcriptome is essential for accurate profiling, yet factors during cell isolation including time ex vivo and temperature induce artifactual gene expression, particularly in stress-responsive immune cells. In this study, we investigated two methods to mitigate ex vivo activation signature gene (ASG) expression in peripheral blood mononuclear cells (PBMCs): transcription and translation inhibitors (TTis) and cold temperatures during isolation. Comparative analysis of PBMCs isolated with TTis revealed reduced ASG expression. However, TTi treatment impaired responsiveness to LPS stimulation in subsequent in vitro experiments. In contrast, cold isolation methods also prevented ASG expression; up to a point where the addition of TTis during cold isolation offered minimal additional advantage. These findings highlight the importance of considering the advantages and drawbacks of different isolation methods to ensure accurate interpretation of PBMC transcriptomic profiles.

lncRNA SYTL5-OT4 promotes vessel co-option by inhibiting the autophagic degradation of ASCT2

AIMS

Vessel co-option is responsible for tumor resistance to antiangiogenic therapies (AATs) in patients with colorectal cancer liver metastasis (CRCLM). However, the mechanisms underlying vessel co-option remain largely unknown. Herein, we investigated the roles of a novel lncRNA SYTL5-OT4 and Alanine-Serine-Cysteine Transporter 2 (ASCT2) in vessel co-option-mediated AAT resistance.

METHODS

SYTL5-OT4 was identified by RNA-sequencing and verified by RT-qPCR and RNA fluorescence in situ hybridization assays. The effects of SYTL5-OT4 and ASCT2 on tumor cells were investigated by gain- and loss-of-function experiments, and those of SYTL5-OT4 on ASCT2 expression were analyzed by RNA immunoprecipitation and co-immunoprecipitation assays. The roles of SYTL5-OT4 and ASCT2 in vessel co-option were detected by histological, immunohistochemical, and immunofluorescence analyses.

RESULTS

The expression of SYTL5-OT4 and ASCT2 was higher in patients with AAT-resistant CRCLM. SYTL5-OT4 enhanced the expression of ASCT2 by inhibiting its autophagic degradation. SYTL5-OT4 and ASCT2 promoted vessel co-option by increasing the proliferation and epithelial-mesenchymal transition of tumor cells. Combination therapy of ASCT2 inhibitor and antiangiogenic agents overcame vessel co-option-mediated AAT resistance in CRCLM.

CONCLUSION

This study highlights the crucial roles of lncRNA and glutamine metabolism in vessel co-option and provides a potential therapeutic strategy for patients with AAT-resistant CRCLM.

Uroplakin 1a Knockout Mice Display Marginal Reduction in Fecundity, Decreased Bacterial Clearance Capacity, and Drastic Changes in the Testicular Transcriptome

Uroplakins (UPKs) form physical and chemical barriers in the bladder and other urinary tract tissues. We previously reported the identification and localization of UPKs in the male reproductive tract of rat. In this study, we characterized Upk1a knockout mice and report a marginal reduction in fecundity associated with significant decrease in sperm count. Upk1a mice had lower bacterial clearance capacity when challenged with uropathogenic Escherichia coli for 1 to 5 days. High-throughput analyses of testicular transcriptome indicated that 1128 genes that are expressed in testis of wild-type mice were completely absent in the knockout, while 2330 genes were found to be expressed only in the testis of knockout mice. Furthermore, differential regulation of 148 (67 upregulated and 81 downregulated) was observed. Gene ontology analyses indicated that processes related to integral components of membrane (plasma membrane), G-protein receptor activity and signaling, olfactory receptor activity and perception of smell, organization of extracellular space/region, immune and inflammatory responses to pathogens, spermatid development, meiotic cell cycle, and formation of synaptonemal complex were affected. Results of this study provide evidence on the possible multi-functional role of Upk1a in male reproductive tract and in other tissues as well.

Hypoxia-Regulated lncRNA USP2-AS1 Drives Head and Neck Squamous Cell Carcinoma Progression

The role of hypoxia-regulated long non-coding RNA (lncRNA) in the development of head and neck squamous cell carcinoma (HNSCC) remains to be elucidated. In the current study, we initially screened hypoxia-regulated lncRNA in HNSCC cells by RNA-seq, before focusing on the rarely annotated lncRNA USP2 antisense RNA 1 (USP2-AS1). We determined that USP2-AS1 is a direct target of HIF1α and is remarkably elevated in HNSCC compared with matched normal tissues. Patients with a higher level of USP2-AS1 suffered a poor prognosis. Next, loss- and gain-of-function assays revealed that USP2-AS1 promoted cell proliferation and invasion in vitro and in vivo. Mechanically, RNA pulldown and LC-MS/MS demonstrated that the E3 ligase DDB1- and CUL4-associated factor 13 (DCAF13) is one of the binding partners to USP2-AS1 in HNSCC cells. In addition, we assumed that USP2-AS1 regulates the activity of DCAF13 by targeting its substrate ATR. Moreover, the knockdown of DCAF13 restored the elevated cell proliferation and growth levels achieved by USP2-AS1 overexpression. Altogether, we found that lncRNA USP2-AS1 functions as a HIF1α-regulated oncogenic lncRNA and promotes HNSCC cell proliferation and growth by interacting and modulating the activity of DCAF13.

Cancer-associated fibroblast-induced lncRNA UPK1A-AS1 confers platinum resistance in pancreatic cancer via efficient double-strand break repair

The tumor stroma of pancreatic ductal adenocarcinoma (PDAC) is characterized by an abundant and heterogeneous population of cancer-associated fibroblasts (CAFs), which are critically involved in chemoresistance. However, the underlying mechanism of CAFs in chemoresistance is unclear. Here, we show that CAFR, a CAF subset derived from platinum-resistant PDAC patients, assumes an iCAF phenotype and produces more IL8 than CAFS isolated from platinum-sensitive PDAC patients. CAFR-derived IL8 promotes oxaliplatin chemoresistance in PDAC. Based on long noncoding RNA (lncRNA) profiling in tumor cells incubated with CAF-CM, we found that UPK1A-AS1, whose expression is directly induced by IL8/NF-kappa B signaling, functions as a chemoresistance-promoting lncRNA and is critical for active IL8-induced oxaliplatin resistance. Impressively, blocking the activation of UPK1A-AS1 expression increases the oxaliplatin sensitivity of tumor cells in vivo. Mechanistically, UPK1A-AS1 strengthens the interaction between Ku70 and Ku80 to facilitate nonhomologous end joining (NHEJ), thereby enhancing DNA double-strand break (DSB) repair. Clinically, UPK1A-AS1 expression is positively correlated with IL8 expression, a poor chemotherapeutic response and a shorter progression-free survival (PFS) time in advanced PDAC patients. Collectively, our study reveals a lncRNA-mediated mechanism of CAF-derived paracrine IL8-dependent oxaliplatin resistance and highlights UPK1A-AS1 as a potential therapeutic target.

Hypoxia-induced PVT1 promotes lung cancer chemoresistance to cisplatin by autophagy via PVT1/miR-140-3p/ATG5 axis

Lung cancer is one of the most common and lethal malignant tumors and the cases increased rapidly. Elevated chemoresistance during chemotherapy resistance remains a challenge. Hypoxia is one of the components that lead to chemoresistance. PVT1 participates in various tumor drug resistance and is associated with hypoxia conditions. The present study aimed to analyze the regulatory relationship of hypoxia and PVT1 and the mechanism of PVT1 in the hypoxia-induced chemoresistance process of lung cancer. The expression of PVT1 in lung cancer and adjacent tissues, and cell lines were analyzed using the TCGA database and qPCR. The regulatory relationship between hypoxia and PVT1 was validated and analyzed with qPCR, luciferase reporter system, and CHIP-qPCR. The role of PVT1 in chemoresistance ability induced by hypoxia was analyzed with CCK-8 assay and flow cytometry. The roles of PVT1, hypoxia, and chemoresistance were also analyzed with LC3-GFP transfection, WB, and IHC. Finally, the results were further validated in xenograft models. PVT1 is highly expressed in lung cancer and cell lines, and the expression of PVT1 is regulated by HIF-1α, and the luciferase reporter assay and CHIP-qPCR analysis indicated that HIF-1α could bind to the promoter region of PVT1 and regulate PVT1 expression. PVT1 participated in hypoxia-induced chemoresistance and induced higher viability and lower apoptosis rate by the autophagy signaling pathway via PVT1/miR-140-3p/ATG5 axis. All the findings were validated in the xenograft models. In conclusion, these results suggest that the expression of PVT1 is regulated by HIF-1α and participates in hypoxia-induced chemoresistance.

Tetraspanins as Potential Modulators of Glutamatergic Synaptic Function

Tetraspanins (Tspans) comprise a membrane protein family structurally defined by four transmembrane domains and intracellular N and C termini that is found in almost all cell types and tissues of eukaryotes. Moreover, they are involved in a bewildering multitude of diverse biological processes such as cell adhesion, motility, protein trafficking, signaling, proliferation, and regulation of the immune system. Beside their physiological roles, they are linked to many pathophysiological phenomena, including tumor progression regulation, HIV-1 replication, diabetes, and hepatitis. Tetraspanins are involved in the formation of extensive protein networks, through interactions not only with themselves but also with numerous other specific proteins, including regulatory proteins in the central nervous system (CNS). Interestingly, recent studies showed that Tspan7 impacts dendritic spine formation, glutamatergic synaptic transmission and plasticity, and that Tspan6 is correlated with epilepsy and intellectual disability (formerly known as mental retardation), highlighting the importance of particular tetraspanins and their involvement in critical processes in the CNS. In this review, we summarize the current knowledge of tetraspanin functions in the brain, with a particular focus on their impact on glutamatergic neurotransmission. In addition, we compare available resolved structures of tetraspanin family members to those of auxiliary proteins of glutamate receptors that are known for their modulatory effects.

Biphasic Regulation of Mitogen-Activated Protein Kinase Phosphatase 3 in Hypoxic Colon Cancer Cells

Hypoxia, or low oxygen tension, is a hallmark of the tumor microenvironment. The hypoxia-inducible factor-1α (HIF-1α) subunit plays a critical role in the adaptive cellular response of hypoxic tumor cells to low oxygen tension by activating gene-expression programs that control cancer cell metabolism, angiogenesis, and therapy resistance. Phosphorylation is involved in the stabilization and regulation of HIF-1α transcriptional activity. HIF-1α is activated by several factors, including the mitogen-activated protein kinase (MAPK) superfamily. MAPK phosphatase 3 (MKP-3) is a cytoplasmic dual-specificity phosphatase specific for extracellular signal-regulated kinase 1/2 (Erk1/2). Recent evidence indicates that hypoxia increases the endogenous levels of both MKP-3 mRNA and protein. However, its role in the response of cells to hypoxia is poorly understood. Herein, we demonstrated that small-interfering RNA (siRNA)-mediated knockdown of MKP-3 enhanced HIF-1α (not HIF-2α) levels. Conversely, MKP-3 overexpression suppressed HIF-1α (not HIF-2α) levels, as well as the expression levels of hypoxia-responsive genes (LDHA, CA9, GLUT-1, and VEGF), in hypoxic colon cancer cells. These findings indicated that MKP-3, induced by HIF-1α in hypoxia, negatively regulates HIF-1α protein levels and hypoxia-responsive genes. However, we also found that long-term hypoxia (>12 h) induced proteasomal degradation of MKP-3 in a lactic acid-dependent manner. Taken together, MKP-3 expression is modulated by the hypoxic conditions prevailing in colon cancer, and plays a role in cellular adaptation to tumor hypoxia and tumor progression. Thus, MKP-3 may serve as a potential therapeutic target for colon cancer treatment.

The regulatory role of antisense lncRNAs in cancer

Antisense long non-coding RNAs (antisense lncRNAs), transcribed from the opposite strand of genes with either protein coding or non-coding function, were reported recently to play a crucial role in the process of tumor onset and development. Functionally, antisense lncRNAs either promote or suppress cancer cell proliferation, migration, invasion, and chemoradiosensitivity. Mechanistically, they exert their regulatory functions through epigenetic, transcriptional, post-transcriptional, and translational modulations. Simultaneously, because of nucleotide sequence complementarity, antisense lncRNAs have a special role on its corresponding sense gene. We highlight the functions and molecular mechanisms of antisense lncRNAs in cancer tumorigenesis and progression. We also discuss the potential of antisense lncRNAs to become cancer diagnostic biomarkers and targets for tumor treatment.

Expression of HYOU1 via Reciprocal Crosstalk between NSCLC Cells and HUVECs Control Cancer Progression and Chemoresistance in Tumor Spheroids

Among all cancer types, lung cancer ranks highest worldwide in terms of both incidence and mortality. The crosstalk between lung cancer cells and their tumor microenvironment (TME) has begun to emerge as the "Achilles heel" of the disease and thus constitutes an attractive target for anticancer therapy. We previously revealed that crosstalk between lung cancer cells and endothelial cells (ECs) induces chemoresistance in multicellular tumor spheroids (MCTSs). In this study, we demonstrated that factors secreted in response to crosstalk between ECs and lung cancer cells play pivotal roles in the development of chemoresistance in lung cancer spheroids. We subsequently determined that the expression of hypoxia up-regulated protein 1 (HYOU1) in lung cancer spheroids was increased by factors secreted in response to crosstalk between ECs and lung cancer cells. Direct interaction between lung cancer cells and ECs also caused an elevation in the expression of HYOU1 in MCTSs. Inhibition of HYOU1 expression not only suppressed stemness and malignancy, but also facilitated apoptosis and chemosensitivity in lung cancer MCTSs. Inhibition of HYOU1 expression also significantly increased the expression of interferon signaling components in lung cancer cells. Moreover, the activation of the PI3K/AKT/mTOR pathway was involved in the HYOU1-induced aggression of lung cancer cells. Taken together, our results identify HYOU1, which is induced in response to crosstalk between ECs and lung cancer cells within the TME, as a potential therapeutic target for combating the aggressive behavior of cancer cells.