LINC00240 in the 6p22.1 risk locus promotes gastric cancer progression through USP10-mediated DDX21 stabilization

New mechanism of LncRNA: In addition to act as a ceRNA

Long non-coding RNAs (LncRNAs) are a class of RNA molecules with nucleic acid lengths ranging from 200 bp to 100 kb that cannot code for proteins, which are diverse and widely expressed in both animals and plants. Scholars have found that lncRNAs can regulate human physiological processes at the gene and protein levels, mainly through the regulation of epigenetic, transcriptional and post-transcriptional levels of genes and proteins, as well as in the immune response by regulating the expression of immune cells and inflammatory factors, and thus participate in the occurrence and development of a variety of diseases. From the downstream targets of lncRNAs, we summarize the new research progress of lncRNA mechanisms other than miRNA sponges in recent years, aiming to provide new ideas and directions for the study of lncRNA mechanisms.

Current understanding of the role of DDX21 in orchestrating gene expression in health and diseases

RNA helicases are involved in almost all biological events, and the DDXs family is one of the largest subfamilies of RNA helicases. Recently, studies have reported that RNA helicase DDX21 is involved in several biological events, specifically in orchestrating gene expression. Hence, in this review, we provide a comprehensive overview of the function of DDX21 in health and diseases. In the genome, DDX21 contributes to genome stability by promoting DNA damage repair and resolving R-loops. It also facilitates transcriptional regulation by directly binding to promoter regions, interacting with transcription factors, and enhancing transcription through non-coding RNA. Moreover, DDX21 is involved in various RNA metabolism such as RNA processing, translation, and decay. Interestingly, the activity and function of DDX21 are regulated by post-translational modifications, which affect the localization and degradation of DDX21. Except for its role of RNA helicase, DDX21 also acts as a non-enzymatic function in unwinding RNA, regulating transcriptional modifications and promoting transcription. Next, we discuss the potential application of DDX21 as a clinical predictor for diseases, which may facilitate providing novel pharmacological targets for molecular therapy.

System-wide identification of novel de-ubiquitination targets for USP10 in gastric cancer metastasis through multi-omics screening

OBJECTIVE

Ubiquitin-specific peptidase 10 (USP10), a typical de-ubiquitinase, has been found to play a double-edged role in human cancers. Previously, we reported that the expression of USP10 was negatively correlated with the depth of gastric wall invasion, lymph node metastasis, and prognosis in gastric cancer (GC) patients. However, it remains unclear whether USP10 can regulate the metastasis of GC cells through its de-ubiquitination function.

METHODS

In this study, proteome, ubiquitinome, and transcriptome analyses were conducted to comprehensively identify novel de-ubiquitination targets for USP10 in GC cells. Subsequently, a series of validation experiments, including in vitro cell culture studies, in vivo metastatic tumor models, and clinical sample analyses, were performed to elucidate the regulatory mechanism of USP10 and its de-ubiquitination targets in GC metastasis.

RESULTS

After overexpression of USP10 in GC cells, 146 proteins, 489 ubiquitin sites, and 61 mRNAs exhibited differential expression. By integrating the results of multi-omics, we ultimately screened 9 potential substrates of USP10, including TNFRSF10B, SLC2A3, CD44, CSTF2, RPS27, TPD52, GPS1, RNF185, and MED16. Among them, TNFRSF10B was further verified as a direct de-ubiquitination target for USP10 by Co-IP and protein stabilization assays. The dysregulation of USP10 or TNFRSF10B affected the migration and invasion of GC cells in vitro and in vivo models. Molecular mechanism studies showed that USP10 inhibited the epithelial-mesenchymal transition (EMT) process by increasing the stability of TNFRSF10B protein, thereby regulating the migration and invasion of GC cells. Finally, the retrospective clinical sample studies demonstrated that the downregulation of TNFRSF10B expression was associated with poor survival among 4 of 7 GC cohorts, and the expression of TNFRSF10B protein was significantly negatively correlated with the incidence of distant metastasis, diffuse type, and poorly cohesive carcinoma.

CONCLUSIONS

Our study established a high-throughput strategy for screening de-ubiquitination targets for USP10 and further confirmed that inhibiting the ubiquitination of TNFRSF10B might be a promising therapeutic strategy for GC metastasis.

Modulation of YBX1-mediated PANoptosis inhibition by PPM1B and USP10 confers chemoresistance to oxaliplatin in gastric cancer

Gastric cancer (GC) is a common malignant tumor of the digestive tract, and chemoresistance significantly impacts GC patients' prognosis. PANoptosis has been associated with oxaliplatin-induced cell death. However, the direct regulatory role of YBX1 in cellular chemoresistance through PANoptosis remains unclear. In this study, we investigated the impact of YBX1 on regulating PANoptosis and its influence on the resistance of gastric cancer cells to oxaliplatin. Through overexpression and silencing experiments, we assessed YBX1's effect on proliferation and PANoptosis regulation in gastric cancer cells. Additionally, we identified PPM1B and USP10 as interacting proteins with YBX1 and confirmed their influence on YBX1 molecular function and protein expression levels. Our results demonstrate that YBX1 suppresses PANoptosis, leading to enhanced resistance of gastric cancer cells to oxaliplatin. Furthermore, we found that PPM1B and USP10 play critical roles in regulating YBX1-mediated PANoptosis inhibition. PPM1B directly interacts with YBX1, causing dephosphorylation of YBX1 at serine 314 residue. This dephosphorylation process affects the deubiquitination of YBX1 mediated by USP10, resulting in decreased YBX1 protein expression levels and impacting PANoptosis and oxaliplatin resistance in gastric cancer cells. Additionally, we discovered that the 314th amino acid of YBX1 has a profound impact on its own protein expression abundance, thereby affecting the functionality of YBX1. In conclusion, our study reveals the significance of PPM1B-mediated dephosphorylation of YBX1 and USP10-mediated deubiquitination in regulating PANoptosis and sensitivity to oxaliplatin in gastric cancer cells. These findings offer a potential therapeutic strategy for patients with oxaliplatin-resistant gastric cancer.

Ubiquitin-specific proteases: From biological functions to potential therapeutic applications in gastric cancer

Deubiquitination, a post-translational modification regulated by deubiquitinases, is essential for cancer initiation and progression. Ubiquitin-specific proteases (USPs) are essential elements of the deubiquitinase family, and are overexpressed in gastric cancer (GC). Through the regulation of several signaling pathways, such as Wnt/β-Catenin and nuclear factor-κB signaling, and the promotion of the expression of deubiquitination- and stabilization-associated proteins, USPs promote the proliferation, metastasis, invasion, and epithelial-mesenchymal transition of GC. In addition, the expression of USPs is closely related to clinicopathological features, patient prognosis, and chemotherapy resistance. USPs therefore could be used as prognostic biomarkers. USP targeting small molecule inhibitors have demonstrated strong anticancer activity. However, they have not yet been tested in the clinic. This article provides an overview of the latest fundamental research on USPs in GC, aiming to enhance the understanding of how USPs contribute to GC progression, and identifying possible targets for GC treatment to improve patient survival.

Genome-wide functional integration identified MAZ-controlled RPS14 dysregulation in hepatocellular carcinoma

Chronic infection with Hepatitis B virus (HBV) significantly increases the risk of hepatocellular carcinoma (HCC), particularly in Eastern Asia. However, only a subset of individuals with chronic HBV infection develop HCC, suggesting the role for genetic factors in HCC etiology. Despite genome-wide association studies (GWASs) identifying multiple single nucleotide polymorphisms (SNPs) associated with HBV-related HCC susceptibility, the underlying mechanisms and causal genetic polymorphisms remain largely unclear. To address this, we developed The Updated Integrative Functional Genomics Approach (TUIFGA), an methodology that combines data from transcription factor (TF) cistromics, ATAC-seq, DNAase-seq, and the 1000 Genomes Project to identify cancer susceptibility SNPs within TF-binding sites across human genome. Using TUIFGA, we discovered SNP rs13170300 which located in the TF MAZ binding motif of RPS14. The RPS14 rs13170300 was significantly associated with HCC risk in two case-control sets, with the T allele as the protective allele (Shandong discovery set: TT OR = 0.60, 95% CI = 0.49-0.74, P = 1.0 × 10-6; CT OR = 0.69, 95% CI = 0.55-0.86, P = 0.001; Jiangsu validation set: TT OR = 0.70, 95% CI = 0.56-0.87, P = 0.001; CT OR = 0.65, 95% CI = 0.53-0.82, P = 1.6 × 10-4). SNP rs13170300 affected MAZ binding in the RPS14 promoter, resulting in allele-specific changes in gene expression. RPS14 functions as a novel oncogene in HCC, specifically via activating the AKT signaling. Our findings present important insights into the functional genetics underlying HBV-related HCC development and may contribute to personalized approaches for cancer prevention and novel therapeutics.

A positive feedback between PDIA3P1 and OCT4 promotes the cancer stem cell properties of esophageal squamous cell carcinoma

BACKGROUND

Increasing evidence has indicated that long non-coding RNAs (lncRNAs) have been proven to regulate esophageal cancer progression. The lncRNA protein disulfide isomerase family A member 3 pseudogene 1 (PDIA3P1) has been shown to promote cancer stem cell properties; however, its mechanism of action remains unclear. In this study, we investigated the regulation of esophageal cancer stem cell properties by the interaction of PDIA3P1 with proteins.

METHODS

The GEPIA2 and Gene Expression Omnibus databases were used to analyze gene expression. PDIA3P1 expression in human esophageal squamous cell carcinoma (ESCC) tissues and cell lines was detected by quantitative real-time polymerase chain reaction (qRT-PCR). Loss-of-function experiments were performed to determine the effects of PDIA3P1 on ESCC cell proliferation, migration, and invasion. The sphere formation assay, number of side population cells, and CD271 + /CD44 + cells were detected by flow cytometry to identify the cancer stem cell properties. RNA immunoprecipitation (RIP), RNA pull-down, co-immunoprecipitation (co-IP), dual luciferase reporter, and cleavage under targets and tagmentation (CUT&Tag) assays were performed to elucidate the underlying molecular mechanisms.

RESULTS

PDIA3P1 expression was upregulated in ESCC cell lines and tissues. Functionally, higher PDIA3P1 expression promoted cell proliferation, invasion, and metastasis and inhibited apoptosis in esophageal cancer. Importantly, PDIA3P1 promoted cancer stem cell properties in ESCC. Mechanistically, PDIA3P1 interacted with and stabilized octamer-binding transcription factor 4 (OCT4) by eliminating its ubiquitination by the ubiquitinating enzyme WW domain-containing protein 2 (WWP2). Moreover, as a transcription factor, OCT4 bound to the PDIA3P1 promoter and promoted its transcription.

CONCLUSIONS

Our research revealed a novel mechanism by which a positive feedback loop exists between PDIA3P1 and OCT4. It also demonstrated that the PDIA3P1-WWP2-OCT4 loop is beneficial for promoting the cancer stem cell properties of ESCC. Owing to this regulatory relationship, the PDIA3P1-WWP2-OCT4-positive feedback loop might be used in the diagnosis and prognosis, as well as in the development of novel therapeutics for esophageal cancer.

USP10 promotes the progression of triple-negative breast cancer by enhancing the stability of TCF4 protein

Investigating the role of ubiquitin-specific peptidase 10 (USP10) in triple-negative breast cancer (TNBC). Analyzed USP10 expression levels in tumors using public databases. Detected USP10 mRNA and protein levels in cell lines. Examined USP10 expression in tumor tissues from breast cancer patients. Conducted USP10 knockdown experiments and analyzed changes in cell proliferation and metastasis. Confirmed protein-protein interactions with USP10 through mass spectrometry, Co-IP, and fluorescence experiments. Assessed impact of USP10 on transcription factor 4 (TCF4) ubiquitination and validated TCF4's influence on TNBC cells. We initially identified a pronounced overexpression of USP10 across multiple tumor types, including TNBC. Subsequently, we observed a conspicuous upregulation of USP10 expression levels in breast cancer cell lines compared to normal breast epithelial cells. However, upon subsequent depletion of USP10 within cellular contexts, we noted a substantial attenuation of malignant proliferation and metastatic potential in TNBC cells. In subsequent experimental analyses, we elucidated the physical interaction between USP10 and the transcription factor TCF4, whereby USP10 facilitated the deubiquitination modification of TCF4, consequently promoting its protein stability and contributing to the initiation and progression of TNBC. Collectively, this study demonstrates that USP10 facilitated the deubiquitination modification of TCF4, consequently promoting its protein stability and contributing to the initiation and progression of TNBC.

LINC01226 promotes gastric cancer progression through enhancing cytoplasm-to-nucleus translocation of STIP1 and stabilizing β-catenin protein

Gastric cancer (GC) remains one of the most common malignances and the leading cause of cancer-related mortality worldwide. Although the critical role of several long non-coding RNAs (lncRNAs) transcribed from several GC-risk loci has been established, we still know little about the biological significance of these lncRNAs at most gene loci and how they play in cell signaling. In the present study, we identified a novel oncogenic lncRNA LINC01226 transcribed from the 1p35.2 GC-risk locus. LINC01226 shows markedly higher expression levels in GC specimens compared with those in normal tissues. High expression of LINC01226 is evidently correlated with worse prognosis of GC cases. In line with these, oncogenic LINC01226 promotes proliferation, migration and metastasis of GC cells ex vivo and in vivo. Importantly, LINC01226 binds to STIP1 protein, leads to disassembly of the STIP1-HSP90 complex, elevates interactions between HSP90 and β-catenin, stabilizes β-catenin protein, activates the Wnt/β-catenin signaling and, thereby, promote GC progression. Together, our findings uncovered a novel layer regulating the Wnt signaling in cancers and uncovers a new epigenetic mode of GC tumorigenesis. These discoveries also shed new light on the importance of functional lncRNAs as innovative therapeutic targets through precisely controlling protein-protein interactions in cancers.

The ASH1L-AS1-ASH1L axis controls NME1-mediated activation of the RAS signaling in gastric cancer

Gastric cancer (GC) is one of the most leading cause of malignancies. However, the molecular mechanisms underlying stomach carcinogenesis remain incompletely understood. Dysregulated genetic and epigenetic alternations significantly contribute to GC development. Here, we report that ASH1L and its antisense lncRNA ASH1L-AS1, which are transcribed from the most significant GC-risk signal at 1q22, act as novel oncogenes. The high levels of ASH1L or lncRNA ASH1L-AS1 expression in GC specimens are associated with worse prognosis of patients. In line with this, ASH1L and ASH1L-AS1 are functionally important in promoting GC disease progression. LncRNA ASH1L-AS1 up-regulates ASH1L transcription, increases histone methyltransferase ASH1L expression and elevates genome-wide H3K4me3 modification levels in GC cells. Furthermore, ASH1L-AS1 directly interacts with transcription factor NME1 protein to form the ASH1L-AS1-NME1 ribonucleoprotein, which transcriptionally promotes expression of ASH1L, ASH1L-AS1, KRAS and RAF1, and activates the RAS signaling pathway in GC cells. Taken together, our data demonstrated that the ASH1L-AS1-ASH1L regulatory axis controls histone modification reprogram and activation of the RAS signaling in cancers. Thus, ASH1L-AS1 might be a novel targets of GC therapeutics and diagnosis in the clinic.

Inflammatory cytokine-regulated LNCPTCTS suppresses thyroid cancer progression via enhancing Snail nuclear export

Lymph node metastases are commonly observed in diverse malignancies where they promote cancer progression and poor outcomes, although the molecular basis is incompletely understood. Thyroid cancer is the most prevalent endocrine neoplasm characterized by high frequency of lymph node metastases. Here, we uncover an inflammatory cytokines-controlled epigenetic program during thyroid cancer progression. LNCPTCTS acts as a novel tumor suppressive lncRNA with remarkably decreased expression in thyroid cancer specimens, especially in metastatic lymph nodes. Inflammatory cytokines TNFα or CXCL10, which are released from tumor microenvironment (TME), impair binding capabilities of the transcription factor (TF) EGR1 to the LNCPTCTS promoter and reduce the lncRNA expression in cells. Notably, LNCPTCTS binds to eEF1A2 protein and facilitates the interaction between eEF1A2 and Snail, which promotes Snail nucleus export via the RanGTP-Exp5-aa-tRNA-eEF1A2 complex. Loss of LNCPTCTS in tumors leads to accumulation of Snail in the nucleus, suppressed transcription of E-cadherin and PEBP1, reduced E-cadherin and PEBP1 protein levels, and activated epithelial-mesenchymal transition and MAPK signaling. Our results reveal what we believe to be a novel paradigm between TME and epigenetic reprogram in cancer cells which drives lymph node metastases, therefore illuminating the suitability of LNCPTCTS as a targetable vulnerability in thyroid cancer.

Exosomal long noncoding RNA MLETA1 promotes tumor progression and metastasis by regulating the miR-186-5p/EGFR and miR-497-5p/IGF1R axes in non-small cell lung cancer

BACKGROUND

Lung cancer is the most common and deadliest cancer worldwide, and approximately 90% of all lung cancer deaths are caused by tumor metastasis. Tumor-derived exosomes could potentially promote tumor metastasis through the delivery of metastasis-related molecules. However, the function and underlying mechanism of exosomal long noncoding RNA (lncRNA) in lung cancer metastasis remain largely unclear.

METHODS

Cell exosomes were purified from conditioned media by differential ultracentrifugation and observed using transmission electron microscopy, and the size distributions were determined by nanoparticle tracking analysis. Exosomal lncRNA sequencing (lncRNA-seq) was used to identify long noncoding RNAs. Cell migration and invasion were determined by wound-healing assays, two-chamber transwell invasion assays and cell mobility tracking. Mice orthotopically and subcutaneously xenografted with human cancer cells were used to evaluate tumor metastasis in vivo. Western blot, qRT‒PCR, RNA-seq, and dual-luciferase reporter assays were performed to investigate the potential mechanism. The level of exosomal lncRNA in plasma was examined by qRT‒PCR. MS2-tagged RNA affinity purification (MS2-TRAP) assays were performed to verify lncRNA-bound miRNAs.

RESULTS

Exosomes derived from highly metastatic lung cancer cells promoted the migration and invasion of lung cancer cells with low metastatic potential. Using lncRNA-seq, we found that a novel lncRNA, lnc-MLETA1, was upregulated in highly metastatic cells and their secreted exosomes. Overexpression of lnc-MLETA1 augmented cell migration and invasion of lung cancer. Conversely, knockdown of lnc-MLETA1 attenuated the motility and metastasis of lung cancer cells. Interestingly, exosome-transmitted lnc-MLETA1 promoted cell motility and metastasis of lung cancer. Reciprocally, targeting lnc-MLETA1 with an LNA suppressed exosome-induced lung cancer cell motility. Mechanistically, lnc-MLETA1 regulated the expression of EGFR and IGF1R by sponging miR-186-5p and miR-497-5p to facilitate cell motility. The clinical datasets revealed that lnc-MLETA1 is upregulated in tumor tissues and predicts survival in lung cancer patients. Importantly, the levels of exosomal lnc-MLETA1 in plasma were positively correlated with metastasis in lung cancer patients.

CONCLUSIONS

This study identifies lnc-MLETA1 as a critical exosomal lncRNA that mediates crosstalk in lung cancer cells to promote cancer metastasis and may serve as a prognostic biomarker and potential therapeutic target for lung cancer diagnosis and treatment.