HIF-1α Promotes the Metastasis of Esophageal Squamous Cell Carcinoma by Targeting SP1

Targeting esophageal carcinoma: molecular mechanisms and clinical studies

Esophageal cancer (EC) is identified as a predominant health threat worldwide, with its highest incidence and mortality rates reported in China. The complex molecular mechanisms underlying EC, coupled with the differential incidence of esophageal squamous cell carcinoma (ESCC) and esophageal adenocarcinoma (EAC) across various regions, highlight the necessity for in-depth research targeting molecular pathogenesis and innovative treatment strategies. Despite recent progress in targeted therapy and immunotherapy, challenges such as drug resistance and the lack of effective biomarkers for patient selection persist, impeding the optimization of therapeutic outcomes. Our review delves into the molecular pathology of EC, emphasizing genetic and epigenetic alterations, aberrant signaling pathways, tumor microenvironment factors, and the mechanisms of metastasis and immune evasion. We further scrutinize the current landscape of targeted therapies, including the roles of EGFR, HER2, and VEGFR, alongside the transformative impact of ICIs. The discussion extends to evaluating combination therapies, spotlighting the synergy between targeted and immune-mediated treatments, and introduces the burgeoning domain of antibody-drug conjugates, bispecific antibodies, and multitarget-directed ligands. This review lies in its holistic synthesis of EC's molecular underpinnings and therapeutic interventions, fused with an outlook on future directions including overcoming resistance mechanisms, biomarker discovery, and the potential of novel drug formulations.

Correlation of microscopic tumor extension with tumor microenvironment in esophageal cancer patients

OBJECTIVE

In the era of image-guided adaptive radiotherapy, definition of the clinical target volume (CTV) is a challenge in various solid tumors, including esophageal cancer (EC). Many tumor microenvironmental factors, e.g., tumor cell proliferation or cancer stem cells, are hypothesized to be involved in microscopic tumor extension (MTE). Therefore, this study assessed the expression of FAK, ILK, CD44, HIF-1α, and Ki67 in EC patients after neoadjuvant radiochemotherapy followed by tumor resection (NRCHT+R) and correlated these markers with the MTE.

METHODS

Formalin-fixed paraffin-embedded tumor resection specimens of ten EC patients were analyzed using multiplex immunofluorescence staining. Since gold fiducial markers had been endoscopically implanted at the proximal and distal tumor borders prior to NRCHT+R, correlation of the markers with the MTE was feasible.

RESULTS

In tumor resection specimens of EC patients, the overall percentages of FAK+, CD44+, HIF-1α+, and Ki67+ cells were higher in tumor nests than in the tumor stroma, with the outcome for Ki67+ cells reaching statistical significance (p < 0.001). Conversely, expression of ILK+ cells was higher in tumor stroma, albeit not statistically significantly. In three patients, MTE beyond the fiducial markers was found, reaching up to 31 mm.

CONCLUSION

Our findings indicate that the overall expression of FAK, HIF-1α, Ki67, and CD44 was higher in tumor nests, whereas that of ILK was higher in tumor stroma. Differences in the TME between patients with residual tumor cells in the original CTV compared to those without were not found. Thus, there is insufficient evidence that the TME influences the required CTV margin on an individual patient basis.

TRIAL REGISTRATION NUMBER AND DATE

BO-EK-148042017 and BO-EK-177042022 on 20.06.2022, DRKS00011886, https://drks.de/search/de/trial/DRKS00011886 .

Long non-coding RNA SRA1 suppresses radiotherapy resistance in esophageal squamous cell carcinoma by modulating glycolytic reprogramming

Esophageal squamous cell carcinoma (ESCC), a highly aggressive subtype of esophageal cancer, is characterized by late-stage diagnosis and limited treatment options. Recent advancements in transcriptome sequencing technologies have illuminated the molecular intricacies of ESCC tumors, revealing metabolic reprogramming as a prominent feature. Specifically, the Warburg effect, marked by enhanced glycolysis, has emerged as a hallmark of cancer, offering potential therapeutic targets. In this study, we comprehensively analyzed bulk RNA-seq data from ESCC patients, uncovering elevated SRA1 expression in ESCC development and a poorer prognosis. Silencing of SRA1 led to a modulation of glycolysis-related products and a shift in PKM2 expression. Our findings shed light on the intricate molecular landscape of ESCC, highlighting SRA1 as a potential therapeutic target to disrupt glycolysis-dependent energy production. This metabolic reprogramming may hold the key to innovative treatment strategies for ESCC, ultimately improving patient outcomes.

Interaction and Collaboration of SP1, HIF-1, and MYC in Regulating the Expression of Cancer-Related Genes to Further Enhance Anticancer Drug Development

Specificity protein 1 (SP1), hypoxia-inducible factor 1 (HIF-1), and MYC are important transcription factors (TFs). SP1, a constitutively expressed housekeeping gene, regulates diverse yet distinct biological activities; MYC is a master regulator of all key cellular activities including cell metabolism and proliferation; and HIF-1, whose protein level is rapidly increased when the local tissue oxygen concentration decreases, functions as a mediator of hypoxic signals. Systems analyses of the regulatory networks in cancer have shown that SP1, HIF-1, and MYC belong to a group of TFs that function as master regulators of cancer. Therefore, the contributions of these TFs are crucial to the development of cancer. SP1, HIF-1, and MYC are often overexpressed in tumors, which indicates the importance of their roles in the development of cancer. Thus, proper manipulation of SP1, HIF-1, and MYC by appropriate agents could have a strong negative impact on cancer development. Under these circumstances, these TFs have naturally become major targets for anticancer drug development. Accordingly, there are currently many SP1 or HIF-1 inhibitors available; however, designing efficient MYC inhibitors has been extremely difficult. Studies have shown that SP1, HIF-1, and MYC modulate the expression of each other and collaborate to regulate the expression of numerous genes. In this review, we provide an overview of the interactions and collaborations of SP1, HIF1A, and MYC in the regulation of various cancer-related genes, and their potential implications in the development of anticancer therapy.

Redox Dysregulation in the Tumor Microenvironment Contributes to Cancer Metastasis

Significance: Redox dysregulation under pathological conditions results in excessive reactive oxygen species (ROS) accumulation, leading to oxidative stress and cellular oxidative damage. ROS function as a double-edged sword to modulate various types of cancer development and survival. Recent Advances: Emerging evidence has underlined that ROS impact the behavior of both cancer cells and tumor-associated stromal cells in the tumor microenvironment (TME), and these cells have developed complex systems to adapt to high ROS environments during cancer progression. Critical Issues: In this review, we integrated current progress regarding the impact of ROS on cancer cells and tumor-associated stromal cells in the TME and summarized how ROS production influences cancer cell behaviors. Then, we summarized the distinct effects of ROS during different stages of tumor metastasis. Finally, we discussed potential therapeutic strategies for modulating ROS for the treatment of cancer metastasis. Future Directions: Targeting the ROS regulation during cancer metastasis will provide important insights into the design of effective single or combinatorial cancer therapeutic strategies. Well-designed preclinical studies and clinical trials are urgently needed to understand the complex regulatory systems of ROS in the TME. Antioxid. Redox Signal. 39, 472-490.

Human umbilical cord mesenchymal stem cell-derived extracellular vesicles carrying miR-655-3p inhibit the development of esophageal cancer by regulating the expression of HIF-1α via a LMO4/HDAC2-dependent mechanism

OBJECTIVE

This study clarified the function of human umbilical cord mesenchymal stem cell (hUCMSC)-derived extracellular vesicle (EV)-enclosed miR-655-3p in esophageal squamous cell carcinoma (ESCC).

METHODS

A Chi-square test and the Kaplan-Meier estimator were used to analyze the prognosis of ESCC in relation to the expression of miR-655-3p. ESCC cells were incubated with PBS or hUCMSC-derived EVs (hUCMSC-EVs) in the conditions of gene modification, after which the malignant behaviors of ESCC cells were assessed and the molecular interactions were determined. The effect of hUCMSC-derived EV-miR-655-3p was also investigated in a nude mouse model of ESCC.

RESULTS

Low expression of miR-655-3p indicated poor prognosis of ESCC. hUCMSC-EVs suppressed the malignant behaviors of ESCC cells and the growth and liver metastasis of transplanted tumors. Inhibition of miR-655-3p in hUCMSCs impaired the therapeutic effect of hUCMSC-EVs. LMO4, targeted by miR-655-3p, activated the transcription of HIF-1α by sequestering HDAC2 from HIF-1α promoter. Knockdown of LMO4 suppressed ESCC cell activities, while overexpression of HIF-1α counteracted the tumor suppressive effect of LMO4 knockdown.

CONCLUSION

miR-655-3p enclosed in hUCMSC-derived EVs inhibits ESCC progression partially by inactivating HIF-1α via the LMO4/HDAC2 axis.

Rhaponticin suppresses the hypoxia-induced factor-1 alpha-mediated aggressive phenotype of tongue squamous cell carcinoma

Background

Emerging evidence suggests that rhaponticin, a stilbene monomeric compound isolated from North China rhubarb, has been shown to exhibit significant biological activity against tumors. However, the anticancer effects and mechanisms of rhaponticin in tongue squamous cell carcinoma (TSCC) remain elusive.

Objective

We investigated the changes of migration and invasion abilities and EMT progression of TSCC cells treated with different concentrations of rhaponticin under hypoxia, as well as the possible mechanisms, in order to initially explore the effects of rhaponticin on the biological characteristics of TSCC cells under hypoxia.

Results

The number of cell migration and invasion was prominently increased, E-cadherin protein was down-regulated, and N-cadherin and HIF-1α protein expression was elevated under hypoxia. Rhaponticin intervention strikingly prevented the increased abilities of migration and invasion and EMT of TSCC cells under hypoxia. This was followed by further validation finding that rhaponticin indeed leads to reduced HIF-1α post-transcriptional activity. Mechanistically, rhaponticin may bind to aryl-hydrocarbon nuclear translocator (ARNT) domain of HIF-1α.

Conclusions

Rhaponticin repressed the invasion and migration abilities and EMT process of TSCC cells under a hypoxic environment in vitro by targeted suppression of HIF-1α.

The Role of Reprogrammed Glucose Metabolism in Cancer

Cancer cells reprogram their metabolism to meet biosynthetic needs and to adapt to various microenvironments. Accelerated glycolysis offers proliferative benefits for malignant cells by generating glycolytic products that move into branched pathways to synthesize proteins, fatty acids, nucleotides, and lipids. Notably, reprogrammed glucose metabolism and its associated events support the hallmark features of cancer such as sustained cell proliferation, hijacked apoptosis, invasion, metastasis, and angiogenesis. Overproduced enzymes involved in the committed steps of glycolysis (hexokinase, phosphofructokinase-1, and pyruvate kinase) are promising pharmacological targets for cancer therapeutics. In this review, we summarize the role of reprogrammed glucose metabolism in cancer cells and how it can be manipulated for anti-cancer strategies.

Identification of Potential Biomarkers Using Integrative Approach: A Case Study of ESCC

This paper presents a consensus-based approach that incorporates three microarray and three RNA-Seq methods for unbiased and integrative identification of differentially expressed genes (DEGs) as potential biomarkers for critical disease(s). The proposed method performs satisfactorily on two microarray datasets (GSE20347 and GSE23400) and one RNA-Seq dataset (GSE130078) for esophageal squamous cell carcinoma (ESCC). Based on the input dataset, our framework employs specific DE methods to detect DEGs independently. A consensus based function that first considers DEGs common to all three methods for further downstream analysis has been introduced. The consensus function employs other parameters to overcome information loss. Differential co-expression (DCE) and preservation analysis of DEGs facilitates the study of behavioral changes in interactions among DEGs under normal and diseased circumstances. Considering hub genes in biologically relevant modules and most GO and pathway enriched DEGs as candidates for potential biomarkers of ESCC, we perform further validation through biological analysis as well as literature evidence. We have identified 25 DEGs that have strong biological relevance to their respective datasets and have previous literature establishing them as potential biomarkers for ESCC. We have further identified 8 additional DEGs as probable potential biomarkers for ESCC, but recommend further in-depth analysis.

Cysteine and glycine rich protein 2 exacerbates vascular fibrosis in pulmonary hypertension through the nuclear translocation of yes-associated protein and transcriptional coactivator with PDZ-binding motif

Pulmonary hypertension (PH) is a serious cardiovascular disease with a poor prognosis and high mortality. The pathogenesis of PH is complex, and the main pathological changes in PH are abnormal hypertrophy and vessel stiffness. Cysteine and glycine rich protein 2 (Csrp2), a member of the LIM-only family plays a key role in the response to vascular injury. However, its roles in vascular fibrosis and PH have not been clarified. Therefore, this study aimed to investigate whether Csrp2 can promote vascular fibrosis and to further explore the possible mechanisms. Csrp2 expression was increased in both the pulmonary vasculature of rats with PH and hypoxic pulmonary vascular smooth muscle cells (PASMCs). Hypoxia activated TGF-β1 and its downstream effector, SP1. Additionally, hypoxia activated the ROCK pathway and inhibited KLF4 expression. Silencing SP1 and overexpressing KLF4 reversed the hypoxia-induced increase in Csrp2 expression. Csrp2 knockdown decreased the expression of extracellular matrix (ECM) proteins and inhibited the nuclear translocation and expression of YAP/TAZ in hypoxic PASMCs. These results indicate that hypoxia induces Csrp2 expression through the TGF-β1/SP1 and ROCK/KLF4 pathways. Elevated Csrp2 promoted the nuclear translocation and expression of YAP/TAZ, leading to vascular fibrosis and the development of PH.

HIF-1α drives the transcription of NOG to inhibit osteogenic differentiation of periodontal ligament stem cells in response to hypoxia

Osteogenic differentiation of periodontal ligament stem cells (PDLSCs) is limited in hypoxia, and HIF-1α is key to the response to hypoxia. However, its mechanisms remain largely unknown. This study discovered an osteogenesis-related gene sensitive to hypoxia in PDLSCs, and investigated the molecular mechanisms between HIF-1α and the gene. NOG, a gene that negatively regulates osteogenesis, was discovered by RNA-seq. Under normoxic conditions, HIF-1α overexpression led to enhanced expression of NOG/Noggin and inhibited the expression of osteogenesis-related genes, while inhibition of HIF-1α reversed this effect. The expression of HIF-1α, NOG/Noggin and the osteogenesis-related genes were detected by qRT-PCR or Western blot. Mechanistically, we verified that HIF-1α binds to the hypoxia response element (-1505 to -1502) in the promotor of NOG to enhance secretion of Noggin by chromatin immunoprecipitation and a dual-luciferase reporter assay. IHC staining findings in an animal model verified that Noggin-associated osteogenic differentiation was inhibited in hypoxia. NOG displayed a concordant relationship with HIF-1α, and secreted more with increasing of HIF-1α. Hypoxia stabilized HIF-1α, which bound to the HRE (-1505 to -1502) of the NOG promotor to enhance NOG transcription resulted in inhibiting osteogenic differentiation of PDLSCs. This study offers a promising therapy for periodontitis.

The hypoxia-inducible factor 1 inhibitor LW6 mediates the HIF-1α/PD-L1 axis and suppresses tumor growth of hepatocellular carcinoma in vitro and in vivo

The low survival rate of hepatocellular carcinoma (HCC) remains a major challenge for clinicians and patients, and its progression may be related to hypoxia-inducible factor (HIF) and PD-L1. LW6 is a drug that inhibits hypoxia by reducing HIF-1α accumulation and gene transcriptional activity. However, its effect and regulatory mechanism in HCC remain to be revealed, especially under hypoxic conditions. The HIF-1α and PD-L1 expression in HCC specimens and paracarcinoma tissues was evaluated by a tissue microarray (TMA). The effects of LW6 were evaluated by cell viability, colony formation, and Transwell assays and xenografted nude mice. Cell cycle and apoptosis of HCC cells were detected by flow cytometry. The effects of LW6 on HIF-1α signaling and its targets PD-L1 and VEGF were evaluated through qRT-PCR, Western blots, Cell transfection, Transwell migration and invasion assays, immunohistochemistry, immunofluorescence and luciferase assays. In this study, we found that LW6 had antiproliferative effects on HCC and promoted HCC cell apoptosis, inhibited their migration and invasion, and affected their cell cycle. LW6 dramatically decreased HIF-1α expression through the VHL-dependent proteasome system pathway, inhibited HIF-1α transcriptional activation, and reduced PD-L1 expression by inhibiting EGFR pathway activation. These results suggest that LW6 can promote apoptosis of HCC cells by inhibiting HIF-1α, inhibit tumor angiogenesis, and downregulate the expression of PD-L1, which is an effective choice for the treatment of HCC. Moreover, inhibiting the hypoxic microenvironment combined with immunotherapy is expected to be a potentially effective strategy.

An N-glycoproteomic site-mapping analysis reveals glycoprotein alterations in esophageal squamous cell carcinoma

Background

Aberrant glycosylation has been recognized as a hallmark of cancer and N-glycosylation is one of the main types of glycosylation in eukaryotes. Although N-glycoproteomics has made contributions to the discovery of biomarkers in a variety of cancers, less is known about the abnormal glycosylation signatures in esophageal squamous cell carcinoma (ESCC).

Methods

In this study, we reported the proteomics and N-glycoproteomic site-mapping analysis of eight pairs of ESCC tissues and adjacent normal tissues. With zic-HILIC enrichment, TMT-based isobaric labeling, LC–MS/MS analysis, differentially expressed N-glycosylation was quantitatively characterized. Lectin affinity enrichment combined with western blot was used to validate the potential biomarkers in ESCC.

Results

A series of differentially expressed glycoproteins (e.g., LAMP2, PLOD2) and enriched signaling pathways (e.g., metabolism-related pathway, ECM-receptor interaction, focal adhesion) were identified. Besides that, seven significantly enriched motifs were found from the identified N-glycosylation sites. Three clusters were identified after conducting the dynamic profiling analysis of glycoprotein change during lymph node metastasis progression. Further validation found that the elevated fucosylation level of ITGB1, CD276 contributed to the occurrence and development of ESCC, which might be the potential biomarkers in ESCC.

Conclusion

In summary, we characterized the N-glycosylation and N-glycoprotein alterations associated with ESCC. The typical changes in glycoprotein expression and glycosylation occupancy identified in our study will not only be used as ESCC biomarkers but also improve the understanding of ESCC biology.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12967-022-03489-2.

Potential Role of Silencing Ribonucleic Acid for Esophageal Cancer Treatment

INTRODUCTION

Esophageal cancer is an aggressive malignancy with high mortality. Optimal treatment of esophageal cancer remains an elusive goal. Ribonucleic acid (RNA) interference is a novel potential targeted approach to treat esophageal cancer. Targeting oncogenes that can alter critical cellular functions with silencing RNA molecules is a promising approach. The silencing of specific oncogenes in esophageal cancer cells in the experimental setting has been shown to decrease the expression of oncogenic proteins. This has resulted in cell apoptosis, reduction in cell proliferation, reduced invasion, migration, epithelial-mesenchymal transition, decrease in tumor angiogenesis and metastasis, and overcoming drug resistance. The Hedgehog (Hh) signaling pathway has been shown to be involved in esophageal adenocarcinoma formation in a reflux animal model. In addition to Hh, we will focus on other targets with clinical potential in the treatment of esophageal cancer.

MATERIALS AND METHODS

We searched for articles published from 2005 to August 2020 that studied the siRNA effects on inhibiting esophageal cancer formation in experimental settings. We used combinations of the following terms for searching: "esophageal cancer," "RNA interference," "small interfering RNA," "siRNA," "silencing RNA," "Smoothened (Smo)," "Gli," "Bcl-2," "Bcl-XL," "Bcl-W,″ "Mcl-1," "Bfl-1," "STAT3,"and "Hypoxia inducible factor (HIF)". A total of 21 relevant articles were found.

RESULTS AND CONCLUSIONS

Several proto-oncogenes/oncogenes including Hh pathway mediators, glioma-associated oncogene homolog 1 (Gli-1), Smoothened (Smo), and antiapoptotic Bcl-2 have potential as targets for silencing RNA in the treatment of esophageal cancer.

IL-23 production in human macrophages is regulated negatively by tumor necrosis factor α-induced protein 3 and positively by specificity protein 1 after stimulation of the toll-like receptor 7/8 signaling pathway

The IL-23/IL-17 axis plays an important role in the development of autoimmune diseases, but the mechanism regulating IL-23 production is mainly unknown. We investigated how TNFAIP3 and Sp1 affect IL-23 production by human macrophages after exposure to resiquimod, a TLR7/8 agonist.

IL-23 production was significantly upregulated by resiquimod but only slightly by LPS (a TLR4 agonist). Interestingly, IL-23 levels were significantly attenuated after sequential stimulation with LPS and resiquimod, but IL-12p40 and IL-18 levels were not. TLR4-related factors induced by LPS may regulate IL-23 expression via TLR7/8 signaling. LPS significantly enhanced TNFAIP3 and IRAK-M levels but reduced Sp1 levels. After exposure to resiquimod, RNA interference of TNFAIP3 upregulated IL-23 significantly more than siRNA transfection of IRAK-M did. In contrast, knockdown of Sp1 by RNA interference significantly attenuated IL-23 production. Transfection with siRNA for TNFAIP3 enhanced IL-23 expression significantly. After stimulation with resiquimod, GW7647—an agonist for PPARα (an inducer of NADHP oxidase)—and siRNA for UCP2 (a negative regulator of mitochondrial ROS generation) enhanced TNFAIP3 and reduced IL-23. siRNA for p22phox and gp91phox slightly increased Sp1 levels. However, after exposure to resiquimod siRNA-mediated knockout of DUOX1/2 significantly enhanced Sp1 and IL-23 levels, and decreased TNFα-dependent COX-2 expression. Concomitantly, TNFAIP3 levels was attenuated by DUOX1/2 siRNA. TNFAIP3 and Sp1 levels are reciprocally regulated through ROS generation.

In conclusion, after stimulation of the TLR7/8 signaling pathway IL-23 production in human macrophages is regulated negatively by TNFAIP3.

Mitochondrial calcium uniporter promotes cell proliferation and migration in esophageal cancer

Increasing evidence has suggested that mitochondrial calcium uniporter (MCU) is involved in various types of cancer. However, its functions remain unclear in esophageal cancer. The aim of the present study was to explore its abnormal expression and clinical implications in esophageal cancer. A total of 110 patients with esophageal cancer were enrolled in the study. Western blotting was performed to examine the protein expression levels of MCU in 8 pairs of esophageal cancer and adjacent normal tissues. Using immunochemistry, a total of 110 esophageal cancer specimens were analyzed to identify the association between MCU expression and clinicopathological features of patients with esophageal cancer. Furthermore, immunofluorescence of MCU was performed. Pearson's correlation analysis was performed between MCU and hypoxia inducible factor (HIF)-1α/VEGF/E-cadherin/Vimentin expression based on western blotting. After KYSE-150 and TE-1 cells were treated with the MCU agonist Spermine and a small interfering RNA against MCU (si-MCU), a series of functional assays were performed, including Cell Counting Kit-8, colony formation and Transwell assays. The results revealed that, compared with in adjacent normal tissues, MCU was highly expressed in esophageal cancer tissues. MCU expression was significantly associated with depth of invasion, lymph node metastasis, TNM stage and distant metastasis. Moreover, MCU was significantly correlated with HIF-1α/VEGF/E-cadherin/Vimentin in esophageal cancer tissues. MCU overexpression promoted VEGF, MMP2, Vimentin and N-cadherin expression, while it inhibited E-cadherin expression in KYSE-150 and TE-1 cells, and opposite results were observed after transfection with si-MCU. Furthermore, MCU overexpression accelerated the proliferation and migration of KYSE-150 and TE-1 cells. Thus, the current findings suggested that high MCU expression may participate in cell proliferation, migration and epithelial-mesenchymal transition in esophageal cancer.

CircASXL1 Knockdown Restrains Hypoxia-Induced DDP Resistance and NSCLC Progression by Sponging miR-206

Background

Non-small cell lung carcinoma (NSCLC) is a primary prevalent type of cancer in people worldwide. Cisplatin (DDP) has been widely used to treat NSCLC; however, its curative effect was restrained under hypoxia. In this study, the effects of hypoxia treatment on DDP resistance and NSCLC progression and underneath mechanism were revealed.

Methods

The expression of circular RNA ASXL1 (circASXL1) and microRNA-206 (miR-206) in NSCLC tissues, cells and hypoxia-mediated NSCLC cells was determined by quantitative real-time polymerase chain reaction (qRT-PCR). The expression of proliferation, metastasis and apoptosis-related proteins, drug resistance-related protein and hypoxia-inducible factor-1alpha (HIF-1α) protein was detected by Western blot. The effects of circASXL1 knockdown on hypoxia-induced DDP resistance and NSCLC progression were revealed by cell counting kit-8 proliferation (CCK-8), cell colony formation, transwell and flow apoptosis assays. RNA immunoprecipitation (RIP) assay was performed to determine whether circASXL1 could form silence-inducing complexes with miRNA. The associated relationship between circASXL1 and miR-206 was predicted by circBank online database, and identified by RNA pull-down and dual-luciferase reporter assays. The effects between circASXL1 knockdown and miR-206 downregulation on tumor growth in vivo were investigated by in vivo tumor formation assay.

Results

CircASXL1 expression was dramatically upregulated, whereas miR-206 was significantly down-regulated in NSCLC tissues, cells and hypoxia-mediated NSCLC cells as compared to control groups. CircASXL1 knockdown reversed hypoxia-mediated promotion effects on DDP resistance, cell proliferation, migration, and invasion, and inhibition impact on cell apoptosis, whereas these effects were restored by miR-206 inhibitor. Additionally, circASXL1 was found to form silence-inducing complexes with miRNA and act as a sponge of miR-206. CircASXL1 silencing downregulated HIF-1α expression by controlling miR-206 expression. Furthermore, circASXL1 silencing repressed tumor growth in vivo by sponging miR-206.

Conclusion

CircASXL1 knockdown inhibited DDP resistance, cell proliferation, migration and invasion, whereas induced cell apoptosis under hypoxia by associating with miR-206 in NSCLC. This study provides a new sight in treating NSCLC with DDP under hypoxia.

Cartilage Endplate Stem Cells Transdifferentiate Into Nucleus Pulposus Cells via Autocrine Exosomes

Stem cells derived from cartilage endplate (CEP) cells (CESCs) repair intervertebral disc (IVD) injury; however, the mechanism remains unclear. Here, we evaluated whether CESCs could transdifferentiate into nucleus pulposus cells (NPCs) via autocrine exosomes and subsequently inhibit IVD degeneration. Exosomes derived from CESCs (CESC-Exos) were extracted and identified by ultra-high-speed centrifugation and transmission electron microscopy. The effects of exosomes on the invasion, migration, and differentiation of CESCs were assessed. The exosome-activating hypoxia-inducible factor (HIF)-1α/Wnt pathway was investigated using lenti-HIF-1α and Wnt agonists/inhibitors in cells and gene ontology and Kyoto Encyclopedia of Genes and Genomes enrichment analysis in normal and degenerated human CEP tissue. The effects of GATA binding protein 4 (GATA4) on transforming growth factor (TGF)-β expression and on the invasion, migration, and transdifferentiation of CESCs were investigated using lenti-GATA4, TGF-β agonists, and inhibitors. Additionally, IVD repair was investigated by injecting CESCs overexpressing GATA4 into rats. The results indicated that CESC-Exos promoted the invasion, migration, and differentiation of CESCs by autocrine exosomes via the HIF-1α/Wnt pathway. Additionally, increased HIF-1α enhanced the activation of Wnt signaling and activated GATA4 expression. GATA4 effectively promoted TGF-β secretion and enhanced the invasion, migration, and transdifferentiation of CESCs into NPCs, resulting in promotion of rat IVD repair. CESCs were also converted into NPCs as endplate degeneration progressed in human samples. Overall, we found that CESC-Exos activated HIF-1α/Wnt signaling via autocrine mechanisms to increase the expression of GATA4 and TGF-β1, thereby promoting the migration of CESCs into the IVD and the transformation of CESCs into NPCs and inhibiting IVDD.

SP1 Expression and the Clinicopathological Features of Tumors: A Meta-Analysis and Bioinformatics Analysis

Objective: Specificity protein 1 (SP1) plays a vital role to promote carcinogenesis in a variety of tumors, and its up-regulated expression is reported to be a hinter of poor prognosis of patients. We conducted this meta-analysis to elucidate the clinical significance and prognostic value of SP1 in malignant tumors. Methods: PubMed and Cochrane Library were searched for studies published between January 1, 2000 and June 1, 2020. The combined odds ratios (ORs) and hazard ratios (HRs) with 95% confidence intervals (95% CIs) were used to investigate the correlation of SP1 with clinical behaviors and prognosis in patients with solid tumors. UALCAN was used to conduct bioinformatics analysis. Results: A total of 24 documents involving 2,739 patients were enrolled in our review. The random-effect model was used to perform this analysis due to the high level of heterogeneity. SP1 low expression was not conducive to lymph node metastasis (OR = 0.42; 95% CI: 0.28-0.64; p < 0.05), progression of TNM stage (OR = 0.34; 95% CI: 0.20-0.57; p < 0.05) and tumor infiltration (OR = 0.33; 95% CI: 0.18-0.60; p < 0.05). Elevated SP1 expression was connected with shorter survival time of patients with hepatocellular carcinoma, pancreatic cancer, gastric cancer and esophageal cancer (HR = 1.95; 95% CI: 1.16-3.28; p < 0.05). According to UALCAN database, breast cancer, ovarian cancer, colon cancer and lung adenocarcinoma display an elevated SP1 expression in comparison with normal tissues. Kaplan-Meier survival plots indicate SP1 mRNA level has negative effects on prognosis of liver hepatocellular carcinoma and brain lower grade glioma. Conclusion: SP1 was associated with lymph node metastasis, TNM stage and depth of invasion, and indicated poor clinical outcome, which brought new insights on the potential candidacy of SP1 in clinical usage.

Esophageal Microenvironment: From Precursor Microenvironment to Premetastatic Niche

Esophageal cancer (EC) is the sixth most deadly cancer, and its incidence is still increasing year by year. Although the researches on the molecular mechanisms of EC have been widely carried out and incremental progress has been made, its overall survival rate is still low. There is cumulative evidence showing that the esophageal microenvironment plays a vital role in the development of EC. In precancerous lesions of the esophagus, high-risk environmental factors can promote the development of precancerous lesions by inducing the production of inflammatory factors and the recruitment of immune cells. In the tumor microenvironment, tumor-promoting cells can inhibit anti-tumor immunity and promote tumor progression through a variety of pathways, such as bone marrow-derived suppressor cells (MDSCs), tumor-associated fibroblasts (CAFs), and regulatory T cells (Tregs). The formation of extracellular hypoxia and acidic microenvironment and the change of extracellular matrix stiffness are also important factors affecting tumor progression and metastasis. Simultaneously, primary tumor-derived cytokines and bone marrow-derived immune cells can also promote the formation of pre-metastasis niche of EC lymph nodes, which are beneficial to EC lymph node metastasis. Further research on the specific mechanism of these processes in the occurrence, development, and metastasis of each EC subtype will support us to grasp the overall pre-cancerous prevention, targeted treatment, and metastatic assessment of EC.

Activation of PGK1 under hypoxic conditions promotes glycolysis and increases stem cell‑like properties and the epithelial‑mesenchymal transition in oral squamous cell carcinoma cells via the AKT signalling pathway

Although it has been previously documented that a hypoxic environment can promote glycolysis and the malignant progression of oral squamous cell carcinoma (OSCC) cells, the specific underlying mechanism remains unclear. Phosphoglycerate kinase 1 (PGK1) has been previously reported to serve an important role in tumor metabolism. The aim of the present study was to investigate the effects of hypoxia and PGK1 on glycolysis, stem cell-like properties and epithelial-mesenchymal transition (EMT) in OSCC cells. Cell Counting Kit-8 assays were performed to examine tumor cell viability under hypoxic conditions. Sphere formation, immunohistochemistry, western blotting, Transwell assays and mouse xenograft studies were performed to assess the biological effects of PGK1. Under hypoxic conditions, phosphoglycerate PGK1 expression was found to be upregulated, which resulted in the potentiation of stem cell-like properties and enhancement of EMT. However, PGK1 knockdown reversed hypoxia-mediated glycolysis, stem cell-like properties, EMT in addition to inhibiting OSCC cell invasion and migration. PGK1 knockdown also inhibited tumour growth, whilst the overexpression of PGK1 was demonstrated to promote tumour growth in mouse xenograft models in vivo. Downstream, activation of the AKT signalling pathway reversed the series of changes induced by PGK1 knockdown. PGK1 expression was found to be upregulated in human OSCC tissues, which was associated with the pathological differentiation of tumours and lymph node metastasis. To conclude, results from the present study demonstrate that hypoxia can increase PGK1 expression, resulting in the promotion of glycolysis, enhancing stem cell-like properties and EMT by activating AKT signalling in OSCC.

SP1-activated long noncoding RNA lncRNA GCMA functions as a competing endogenous RNA to promote tumor metastasis by sponging miR-124 and miR-34a in gastric cancer

Long noncoding RNAs (lncRNAs) were demonstrated to play important roles in gene regulation and cancer progression. However, the functional roles of lncRNAs and the detailed mechanisms underlying gastric cancer (GC) progression remain largely unclear. Here, we identified a novel cancer-related lncRNA, termed lncRNA GCMA (Gastric Cancer metastasis-associated lncRNA), which was upregulated in GC tissues with lymph node metastasis (LNM) compared with tissues without LNM. High expression of GCMA was significantly associated with poor prognosis of patients with GC. Luciferase assays, bioinformatics analyses and chromatin immunoprecipitation (ChIP) assays indicated that SP1 transcription factor directly bound to the GCMA promoter region and activated its transcription. Functionally, upregulation of GCMA dramatically promoted GC cells proliferation, migration and invasion in vitro, whereas knockdown of GCMA elicited the opposite function. Consistently, stable knockdown of GCMA inhibited tumor proliferation, invasion and metastasis in vivo. Mechanistically, by using bioinformatics analyses, RNA binding protein immunoprecipitation (RIP) assays, luciferase assays and western-blot assays, GCMA was demonstrated to function as a competing endogenous RNA (ceRNA) via competitively absorbing miR-124 and miR-34a to upregulate slug and snail, thereby induced epithelial-mesenchymal transition (EMT) and GC cell metastasis in vitro and in vivo. Collectively, these results demonstrate that GCMA functions as an oncogenic lncRNA that may serve as a potential prognostic biomarker for GC and shed new lights on targeted therapy of GC in the future.

Association of Nuclear Receptor Coactivators with Hypoxia-Inducible Factor-1α in the Serum of Patients with Chronic Kidney Disease

Nuclear receptor coactivators (NCOAs), consisting of coactivators and corepressors, dramatically enhance the transcriptional activity of nuclear receptors. Hypoxia-inducible factor-1α (HIF-1α) is a transcription factor that plays a major role under hypoxic conditions. This study was performed with the focus on the association of NCOAs with HIF-1α in the serum of chronic kidney disease (CKD) patients. Sixty patients with stage 5 CKD and 30 healthy controls from The Second Affiliated Hospital of Shantou University Medical College, between March 21, 2019, and October 30, 2019, were recruited in this prospective cohort study. We analyzed the serum levels of NCOAs (NCOA1, NCOA2, and NCOA3), HIF-1α, vascular endothelial growth factor (VEGF), etc. and assessed whether there was any relationship between these parameters and CKD disease. We found that circulating NCOA1 was positively associated with circulating NCOA2, NCOA3, and HIF-1α. A positive correlation was also observed between NCOA2 and NCOA1, NCOA3, HIF-1α, and VEGF. Furthermore, statistically significant correlations between NCOA3 and NCOA1, NCOA2, and HIF-1α were observed. The serum levels of VEGF in the CKD group were higher than those of the healthy control group. Circulating NCOA1 and circulating NCOA2 were negatively associated with procalcitonin. In conclusion, there was an association between circulating NCOA1, NCOA2, NCOA3, and circulating HIF-1α, and circulating VEGF was a risk factor for CKD disease. However, more studies should be performed to confirm this hypothesis.