TBL1 is required for the mesenchymal phenotype of transformed breast cancer cells

Targeting the DNA damage response through TBL1X in mantle cell lymphoma

ABSTRACT

Mantle cell lymphoma (MCL) is an incurable B-cell lymphoma characterized by significant genomic instability. Patients with MCL who progress on targeted therapies have a short survival; thus, novel therapeutic strategies are urgently needed. Overexpression of transducin β-like protein 1 X-linked (TBL1X) has been documented in several types of cancer and associated with poor prognosis. TBL1X is a critical regulator of multiple oncogenic networks; however, its function in MCL has not been explored. Our data show that, unlike normal B cells, MCL cells express abundant levels of TBL1X and that genetic knockdown of TBL1X and treatment with tegavivint (Iterion), a first-in-class small molecule targeting TBL1X, promote MCL cell death in vitro and in vivo. Moreover, TBL1X controls the stability of key MCL oncogenic drivers, cyclin D1 and RAD51; and targeting TBL1X results in significant DNA damage, cell cycle arrest, and ultimately cell death. Combining tegavivint with poly(adenosine 5'-diphosphate-ribose) polymerase-1/2 inhibitor talazoparib results in synergistic MCL cell death in vitro, and in vivo this combination significantly prolongs the survival of a patient-derived MCL xenograft. Together, our results define the role of TBL1X in maintaining genomic stability in MCL and establish targeting TBL1X as a novel therapeutic strategy for patients with this incurable disease.

PPM1G-mediated TBL1X mRNA splicing promotes cell migration in hepatocellular carcinoma

The progression of hepatocellular carcinoma (HCC) is coincident with aberrant splicing of numerous tumor-related genes. Identification of the tumor-specific splice variants that facilitate HCC metastasis may provide a more comprehensive insight into the mechanisms of HCC metastasis. Through RNA sequencing and bioinformatic analyses, PPM1G was identified as a biomarker associated with HCC metastasis. Our data mapped a transcriptome-wide landscape of alternative splicing events modulated by PPM1G in HCC. Notably, we characterized the exon six-skipping transcript of TBL1X as an onco-splice variant regulated by PPM1G. Experimental validation revealed the enrichment of TBL1X-S in response to PPM1G overexpression. Moreover, mRNA stability analyses revealed that PPM1G prolonged the half-life of the TBL1X-S transcript. Both PPM1G and TBL1X-S exhibited metastasis-promoting phenotypes, with PPM1G-driven metastasis in HCC being partially dependent on TBL1X-S. Mechanistically, different TBL1X splice variants showed varying affinities for ZEB1, with TBL1X-S significantly enhancing ZEB1 activation and repressing CDH1 transcription, potentially accelerating the epithelial-mesenchymal transition (EMT) process. In conclusion, our study highlights the biological role of PPM1G and TBL1X-S in tumor metastasis. The PPM1G/TBL1X-S signaling axis presents a new view for investigating liver cancer metastasis mechanisms.

EP300 promotes tumor stemness via epigenetic activation of CRISP3 leading to lobaplatin resistance in triple-negative breast cancer

Lobaplatin shows antitumor activity against a wide range of tumors, including triple-negative breast cancer (TNBC), and has been linked to cancer stem cell pool. Here, we investigated the molecular mechanisms behind lobaplatin resistance and stemness in vitro and in vivo. Two chemoresistance-related GEO data sets (GSE70690 and GSE103115) were included to screen out relevant genes. Cysteine-rich secretory protein 3 (CRISP3) was found to be overexpressed in lobaplatin-resistant TNBC and related to poor diagnosis. CRISP3 expression was significantly correlated with tumor stemness markers in lobaplatin-resistant cells. E1A-associated protein p300 (EP300) regulated CRISP3 expression by affecting the H3K27ac modification of the CRISP3 promoter. In addition, knocking down EP300 curbed the malignant biological behavior of lobaplatin-resistant cells, which was antagonized by CRISP3 overexpression. Collectively, our results highlight the EP300/CRISP3 axis as a key driver of lobaplatin resistance in TNBC and suggest that therapeutic targeting of this axis may be an effective strategy for enhancing platinum sensitivity in TNBC.

Comparing the roles of sex chromosome-encoded protein homologs in gene regulation

The X and Y chromosomes play important roles outside of human reproduction; namely, their potential contribution to human sex biases in physiology and disease. While sex biases are often thought to be an effect of hormones and environmental exposures, genes encoded on the sex chromosomes also play a role. Seventeen homologous gene pairs exist on the X and Y chromosomes whose proteins have critical functions in biology, from direct regulation of transcription and translation to intercellular signaling and formation of extracellular structures. In this review, we cover the current understanding of several of these sex chromosome-encoded protein homologs that are involved in transcription and chromatin regulation: SRY/SOX3, ZFX/ZFY, KDM5C/KDM5D, UTX/UTY, and TBL1X/TBL1Y. Their mechanisms of gene regulation are discussed, including any redundancies or divergent roles of the X- and Y-chromosome homologs. Additionally, we discuss associated diseases related to these proteins and any sex biases that exist therein in an effort to drive further research into how these pairs contribute to sexually dimorphic gene regulation in health and disease.

Ferroptosis-related lncRNAs: Distinguishing heterogeneity of the tumour microenvironment and predicting immunotherapy response in bladder cancer

Ferroptosis, a cell death pathway dependent on iron, has been shown in research to play a role in the development, advancement, and outlook of tumours through ferroptosis-related lncRNAs (FRLRs). However, the value of the FRLRs in bladder cancer (BLCA) has not been thoroughly investigated. This research project involved developing a predictive model using ten specific FRLRs (AC099850.4, AL731567.1, AL133415.1, AC021321.1, SPAG5-AS1, HMGA2-AS1, RBMS3-AS3, AC006160.1, AL583785.1, and AL662844.4) through univariate COX and LASSO regression techniques. The validation of this signature as a standalone predictor was confirmed in a group of 65 patients from the urology bladder tumour database at the First Affiliated Hospital of Wenzhou Medical University in Wenzhou, China. Patients were categorized based on their median risk score into either a low-risk group or a high-risk group. Enrichment analysis identified possible molecular mechanisms that could explain the variations in clinical outcomes observed in high-risk and low-risk groups. Moreover, we explored the correlation between FLPS and immunotherapy-related indicators. The ability of FLPS to forecast the effectiveness of immunotherapy was validated by the elevated levels of immune checkpoint genes (PD-L1, CTLA4, and PD-1) in the group at high risk. We also screened the crucial FRLR (HMGA2-AS1) through congruent expression and prognostic conditions and established a ceRNA network, indicating that HMGA2-AS1 may affect epithelial-mesenchymal transition by modulating the Wnt signalling pathway through the ceRNA mechanism. We identified the top five mRNAs (NFIB, NEGR1, JAZF1, JCAD, and ESM1) based on random forest algorithm and analysed the relationship between HMGA2-AS1, the top five mRNAs, and immunotherapy, and their interactions with drug sensitivities. Our results suggest that patients with BLCA have a greater sensitivity to four drugs (dasatinib, pazopanib, erismodegib and olaparib). Our study provides new insights into the TME, key signalling pathways, genome, and potential therapeutic targets of BLCA, with future guidance for immunotherapy and targeted precision drugs.

Research progress of Claudin-low breast cancer

Claudin-low breast cancer (CLBC) is a subgroup of breast cancer discovered at the molecular level in 2007. Claudin is one of the primary proteins that make up tight junctions, and it plays crucial roles in anti-inflammatory and antitumor responses as well as the maintenance of water and electrolyte balance. Decreased expression of claudin results in the disruption of tight junction structures and the activation of downstream signaling pathways, which can lead to tumor formation. The origin of Claudin-low breast cancer is still in dispute. Claudin-low breast cancer is characterized by low expression of Claudin3, 4, 7, E-cadherin, and HER2 and high expression of Vimentin, Snai 1/2, Twist 1/2, Zeb 1/2, and ALDH1, as well as stem cell characteristics. The clinical onset of claudin-low breast cancer is at menopause age, and its histological grade is higher. This subtype of breast cancer is more likely to spread to lymph nodes than other subtypes. Claudin-low breast cancer is frequently accompanied by increased invasiveness and a poor prognosis. According to a clinical retrospective analysis, claudin-low breast cancer can achieve low pathological complete remission. At present, although several therapeutic targets of claudin-low breast cancer have been identified, the effective treatment remains in basic research stages, and no animal studies or clinical trials have been designed. The origin, molecular biological characteristics, pathological characteristics, treatment, and prognosis of CLBC are extensively discussed in this article. This will contribute to a comprehensive understanding of CLBC and serve as the foundation for the individualization of breast cancer treatment.

Long noncoding RNA MIAT regulates TP53 ubiquitination and expedites prostate adenocarcinoma progression by recruiting TBL1X

Despite recent advances in cancer immunotherapy, their efficacy for treating patients with prostate adenocarcinoma (PRAD) is low due to complex immune evasion mechanisms. However, the function of long non-coding RNA (lncRNAs) in immune evasion has not been fully clarified. This study aimed to expound the role of myocardial infarction-associated transcript (MIAT), a lncRNA significantly upregulated in three PRAD-associated datasets, in immune evasion and try to reveal the potential mechanism. MIAT was highly expressed in PRAD tissues and predicted poor prognosis, and suppression of MIAT inhibited the malignant biological behavior of PRAD cells. Moreover, the depletion of MIAT promoted the immune response of CD8+ T cells and hampered the immune evasion of PRAD cells. In addition, MIAT downregulated TP53 protein expression by recruiting transducin beta-like protein 1X (TBL1X) for ubiquitination modification. Silencing of TP53 or overexpression of TBL1X was enough to abate the tumor suppressive effects of MIAT knockdown in vitro and in vivo. Our results provide evidence for a novel regulation mechanism of CD8+ T cells in PRAD and MIAT may serve as a potential therapeutic target in PRAD.

ARID1A downregulation promotes cell proliferation and migration of colon cancer via VIM activation and CDH1 suppression

According to our prior findings, ARID1A expression is decreased in colon cancer, which has a poor prognosis. In this study, we investigated the ARID1A-VIM/CDH1 signalling axis's role in colon cancer proliferation and migration. The differentially expressed genes in cells that might be controlled by ARID1A were discovered by a database screening for ARID1A knockout. qPCR was used to analyse ARID1A and EMT markers expression levels in colon cancer. We utilized siRNA RID1A to explore the influence of ARID1A silencing on EMT in CRC cells. The function of ARID1A in the colon was investigated utilizing the wound healing, transwell and CCK-8 WST- assays. The molecular mechanism by which ARID1A regulates VIM and CDH1 was elucidated using chip-qPCR. Numerous genes involved in EMT were dysregulated in the absence of ARID1A. VIM expression increased in cells lacking ARID1A expression and vice versa. Many COAD samples with high ARID1A mRNA expression had low VIM mRNA expression, despite the relevance. CDH1 gene was positively correlated with ARID1A. Moreover, siRNA-ARID1A-transfected cells accelerated cell migration and invasion and increased cell proliferation rate in vitro. Chip-qPCR analysis showed that ARID1A binds to the promoters of both genes and changes their expression in colon cancer. ARID1A inactivation is associated with VIM activation and CDH1 suppression, which might serve as crucial molecules influencing COAD prognosis, accelerate tumour progression, and shorten patients' survival time, and promote metastases of COAD. Thus, depletion of ARID1A can be therapeutically exploited by targeting downstream effects to improve cancer treatment-related outcomes.

TBL1X: At the crossroads of transcriptional and posttranscriptional regulation

Over the past 2 decades, the adaptor protein transducin β-like 1 (TBL1X) and its homolog TBL1XR1 have been shown to be upregulated in solid tumors and hematologic malignancies, and their overexpression is associated with poor clinical outcomes. Moreover, dysregulation of the TBL1 family of proteins has been implicated as a key component of oncogenic prosurvival signaling, cancer progression, and metastasis. Herein, we discuss how TBL1X and TBL1XR1 are required for the regulation of major transcriptional programs through the silencing mediator for tetanoid and thyroid hormone receptor (SMRT)/nuclear receptor corepressor (NCOR)/ B cell lymphoma 6 (BCL6) complex, Wnt/β catenin, and NF-κB signaling. We outline the utilization of tegavivint (Iterion Therapeutics), a first-in-class small molecule targeting the N-terminus domain of TBL1, as a novel therapeutic strategy in preclinical models of cancer and clinically. Although most published work has focused on the transcriptional role of TBL1X, we recently showed that in diffuse large B-cell lymphoma (DLBCL), the most common lymphoma subtype, genetic knockdown of TBL1X and treatment with tegavivint resulted in decreased expression of critical (onco)-proteins in a posttranscriptional/β-catenin-independent manner by promoting their proteasomal degradation through a Skp1/Cul1/F-box (SCF)/TBL1X supercomplex and potentially through the regulation of protein synthesis. However, given that TBL1X controls multiple oncogenic signaling pathways in cancer, treatment with tegavivint may ultimately result in drug resistance, providing the rationale for combination strategies. Although many questions related to TBL1X function remain to be answered in lymphoma and other diseases, these data provide a growing body of evidence that TBL1X is a promising therapeutic target in oncology.

Two lncRNAs, MACC1-AS1 and UCA1, co-mediate the expression of multiple mRNAs through interaction with individual miRNAs in breast cancer cells

BACKGROUND

Increasing studies have shown that lncRNAs often play roles through interaction with miRNAs to control gene expression by inhibiting translation or facilitating degradation of target mRNAs. Here, we report that two lncRNAs, MACC1-AS1 and UCA1 are coordinately expressed in breast cancer cells and share the ability to interact with multiple miRNAs to mediate the expression of different genes.

METHODS

Targetscan, starBase and miRDB databases were used to predict the relationships of MACC1-AS1/UCA1-miRNA-mRNA network. qRT-PCR, and RNA sequencing were used to study the differential expression of lncRNAs and miRNA-targeted genes in breast cancer cells. RIP, RNA pull-down and luciferase assays were performed to confirm the molecular interactions of MACC1-AS1 or UCA1 with predicted miRNAs. The role of lncRNA-mediated miRNA-mRNA interactions in cell proliferation was examined by MTT assays following loss-of-function and gain-of-function effects.

RESULTS

We identified a lncRNA-miRNA-mRNA regulatory network in breast cancer cells, in which a number of mRNAs can be co-regulated by MACC1-AS1 and UCA1 lncRNAs. Each lncRNA possesses the capacity as a ceRNA to compete with various mRNA-targeting miRNAs. Interaction of MACC1-AS1 or UCA1 with individual miRNAs is able to increase the expression of the same target mRNAs, such as TBL1X and MEF2D, thus affecting cancer-cell growth phenotype.

CONCLUSIONS

Our study suggests that in each cell type, there is a balance of interactions between certain lncRNAs and miRNAs. Disrupting the balance would eventually affect the expression of miRNA-targeted genes and cell proliferation.

TBL1X and Flot2 form a positive feedback loop to promote metastasis in nasopharyngeal carcinoma

Metastasis is the main cause of death in patients with nasopharyngeal carcinoma (NPC). The molecular mechanisms underlying the metastasis of NPC remain to be elucidated. TBL1X has been shown abnormally expressed in diverse cancers. However, the role and mechanism of TBL1X in NPC remain unknown. Here, we showed TBL1X expression was significantly higher in metastatic NPC tissues compared to non-metastatic tissues and significantly correlated with TNM stage and metastasis of NPC patients. In addition, NPC patients with high TBL1X expression had a poor prognosis. TBL1X interacted with TCF4 to trans-activate Flot2 expression. TBL1X promoted NPC cell migration and invasion in vitro and in vivo through Flot2. Moreover, Flot2 increased the expression of TBL1X by upregulating c-myc, which was identified to be a positively regulatory transcription factor of TBL1X. TBL1X could restore the functional changes of NPC cells resulting from Flot2 alteration. TBL1X and Flot2 were positively correlated in NPC. Patients with high expression of both TBL1X and Flot2 possessed poorer overall survival (OS) and disease-free survival (DFS) compared to patients with high expression of any single one of the two proteins. Our findings demonstrate that TBL1X and Flot2 positively regulate each other to promote NPC metastasis, which provides novel potential molecular targets for NPC treatment.