Upregulation of DACT2 suppresses proliferation and enhances apoptosis of glioma cell via inactivation of YAP signaling pathway

Dishevelled-associated antagonist of β-catenin homolog 3 (DACT3) suppresses glioma progression though Notch1 signaling pathway in β-catenin-dependent manner

The disheveled-associated antagonist of β-catenin homolog 3 (DACT3) has been recognized as a tumor suppressor in various cancers. However, the function of DACT3 on glioma malignant progression along with potential molecular mechanisms is poorly clarified. This research aimed to investigate how DACT3 contributes to suppressing the progression of glioma. In our investigation, a pronounced decrease in DACT3 expression was observed in glioma tissues. Through the overexpression of DACT3, we noted a significant suppression in the proliferation, invasion, and migration of glioma cells, while concurrently observing an increase in cell adhesion. Our exploration into the molecular mechanisms revealed that DACT3 executes its tumor-suppressive role by impeding the expression of notch 1 intracellular domain (NICD) and translocating into the nucleus by downregulating the expression of β-catenin. Consequently, this process leads to the suppression of Notch1 signaling. To summarize, our findings reveal the function of DACT3 to inhibit glioma progression via the Notch1 signaling pathway in β-catenin dependent manner. This study stands as the pioneer in examining the role of DACT3 in glioma progression and comprehensively elucidating its molecular mechanisms in glioma development. Therefore, our results suggest that DACT3 holds promise as both a prognostic factor and a potential biomarker for guiding treatment strategies in glioma patients (Graphical Abstract).

Hypocretin-1 suppresses malignant progression of glioblastoma cells through Notch1 signaling pathway

Hypocretin-1 is a multifunctional neuropeptide that has been identified as a potential antitumor agent for its role in inhibiting tumor growth, including in colon cancer, neuroendocrine tumor, and prostate cancer. However, the role and mechanism of hypocretin-1 in the occurrence and development of malignant glioma have not been well studied. Therefore, we investigated the effect of hypocretin-1 on glioblastoma proliferation, apoptosis, migration and invasion and its mechanism. We found that the hypocretin-1 receptor was expressed in both glioma cell lines and glioma tissues. Hypocretin-1 treatment can inhibit glioblastoma cell proliferation, migration and invasion, and induce cell apoptosis. Meanwhile, hypocretin-1 treatment significantly reduces tumor growth rate and tumor weight. In addition, mechanistic studies have found that hypocretin-1 exerts antitumor effects by inhibiting NOTCH signaling pathway. Overexpression of NICD significantly reversed the antitumor effect of hypocretin on glioblastoma. Taken together, these findings suggest that hypocretin-1 inhibits glioblastoma proliferation, migration and invasion and induces apoptosis in vitro and in vivo through NOTCH signaling pathway.

Multiomics integration reveals the effect of Orexin A on glioblastoma

Objectives: This study involved a multi-omics analysis of glioblastoma (GBM) samples to elaborate the potential mechanism of drug treatment. Methods: The GBM cells treated with or without orexin A were acquired from sequencing analysis. Differentially expressed genes/proteins/metabolites (DEGs/ DEPs/ DEMs) were screened. Next, combination analyses were conducted to investigate the common pathways and correlations between the two groups. Lastly, transcriptome-proteome-metabolome association analysis was carried out to determine the common pathways, and the genes in these pathways were analyzed through Kaplan-Meier (K-M) survival analysis in public databases. Cell and animal experiments were performed to investigate the anti-glioma activity of orexin A. Results: A total of 1,527 DEGs, 52 DEPs, and 153 DEMs were found. Moreover, the combination analyses revealed that 6, 4, and 1 common pathways were present in the transcriptome-proteome, proteome-metabolome, and transcriptome-metabolome, respectively. Certain correlations were observed between the two data sets. Finally, 11 common pathways were discovered in association analysis, and 138 common genes were screened out in these common pathways. Six genes showed significant differences in terms of survival in both TCGA and CGGA. In addition, orexin A inhibited the proliferation, migration, and invasion of glioma in vitro and in vivo. Conclusion: Eleven common KEGG pathways with six common genes were found among different omics participations, revealing the underlying mechanisms in different omics and providing theoretical basis and reference for multi-omics research on drug treatment.

The Role of DACT Family Members in Tumorigenesis and Tumor Progression

Disheveled-associated antagonist of β-catenin (DACT), which ubiquitously expressed in human tissue, is critical for regulating cell proliferation and several developmental processes in different cellular contexts. In addition, DACT is essential for some other cellular processes, such as cell apoptosis, migration and differentiation. Given the importance of DACT in these cellular processes, many scientists are gradually interested in studying the role of DACT in tumorigenesis and cancer progression. This review article focuses on the latest research regarding the essential functions and potential DACT mechanisms in the occurrence and progression of tumors. Our study indicates that DACT may act as a tumor biomarker for cancer diagnosis and prognosis, as well as a promising therapeutic target in cancers.

The interplay between noncoding RNA and YAP/TAZ signaling in cancers: molecular functions and mechanisms

The Hippo signaling pathway was found coordinately modulates cell regeneration and organ size. Its dysregulation contributes to uncontrolled cell proliferation and malignant transformation. YAP/TAZ are two critical effectors of the Hippo pathway and have been demonstrated essential for the initiation or growth of most tumors. Noncoding RNAs (ncRNAs), including miRNAs, lncRNAs, and circRNAs, have been shown to play critical roles in the development of many cancers. In the past few decades, a growing number of studies have revealed that ncRNAs can directly or indirectly regulate YAP/TAZ signaling. YAP/TAZ also regulate ncRNAs expression in return. This review summarizes the interactions between YAP/TAZ signaling and noncoding RNAs together with their biological functions on cancer progression. We also try to describe the complex feedback loop existing between these components.

Crosstalk of the Wnt/β-Catenin Signaling Pathway in the Induction of Apoptosis on Cancer Cells

The Wnt/β-catenin signaling pathway plays a major role in cell survival and proliferation, as well as in angiogenesis, migration, invasion, metastasis, and stem cell renewal in various cancer types. However, the modulation (either up- or downregulation) of this pathway can inhibit cell proliferation and apoptosis both through β-catenin-dependent and independent mechanisms, and by crosstalk with other signaling pathways in a wide range of malignant tumors. Existing studies have reported conflicting results, indicating that the Wnt signaling can have both oncogenic and tumor-suppressing roles, depending on the cellular context. This review summarizes the available information on the role of the Wnt/β-catenin pathway and its crosstalk with other signaling pathways in apoptosis induction in cancer cells and presents a modified dual-signal model for the function of β-catenin. Understanding the proapoptotic mechanisms induced by the Wnt/β-catenin pathway could open new therapeutic opportunities.

miR-181a, delivered by hypoxic PTC-secreted exosomes, inhibits DACT2 by downregulating MLL3, leading to YAP-VEGF-mediated angiogenesis

Papillary thyroid cancer (PTC) is the most common type of thyroid cancer, and angiogenesis plays critical roles in its recurrence and metastasis. In this study, we investigated the effects of hypoxia-induced exosomal microRNA-181 (miR-181a) from PTC on tumor growth and angiogenesis. Thyroid-cancer-related differentially expressed miR-181a was identified by microarray-based analysis in the Gene Expression Omnibus (GEO) database. We validated that miR-181a was highly expressed in PTC cells and even more so in cells cultured under hypoxic conditions, which also augmented exosome secretion from PTC cells. Exosomes extracted from PTC cells with manipulated miR-181a and mixed-lineage leukemia 3 (MLL3) were subjected to normoxic or hypoxic conditions. Human umbilical vein endothelial cells (HUVECs) were transfected with miR-181a inhibitor/mimic or small interfering RNA (siRNA)-MLL3 or treated with exosomes from hypoxic PTC cells. Hypoxic exosomal miR-181a delivery promoted proliferation and capillary-like network formation in HUVECs. Mechanistically, miR-181a targeted and inhibited MLL3. Furthermore, miR-181a downregulated DACT2 and upregulated YAP and vascular endothelial growth factor (VEGF). Further, hypoxic exosomal miR-181a induced angiogenesis and tumor growth in vivo, which was reversed by hypoxic exosomal miR-181a inhibitor. In conclusion, exosomal miR-181a from hypoxic PTC cells promotes tumor angiogenesis and growth through MLL3 and DACT2 downregulation, as well as VEGF upregulation.

Exosomal microRNA-503-3p derived from macrophages represses glycolysis and promotes mitochondrial oxidative phosphorylation in breast cancer cells by elevating DACT2

MicroRNAs (miRNAs) are emerging drivers in tumor progression, while the role of miR-503-3p in breast cancer (BC) remains largely unknown. We aimed to explore the impact of macrophage-derived exosomal miR-503-3p in the development of BC by regulating disheveled-associated binding antagonist of beta-catenin 2 (DACT2). miR-503-3p and DACT2 expression in BC tissues and cells was assessed, and the expression of Wnt/β-catenin signaling pathway-related proteins in BC cells was also evaluated. Macrophages were induced and exosomes were extracted. The screened BC cell lines were, respectively, treated with exosomes, miR-503-3p inhibitor/mimic or upregulated/inhibited DACT2, and then the phenotypes, glucose intake, oxygen consumption rate, and adenosine-triphosphate (ATP) level of BC cells were determined. Cell growth in vivo was also observed. MiR-503-3p was elevated, DACT2 was reduced, and Wnt/β-catenin signaling pathway was activated in BC cells. Macrophage-derived exosomes, upregulated miR-503-3p or inhibited DACT2 promoted malignant behaviors of BC cells, glucose intake, and activity of the Wnt/β-catenin signaling pathway, while repressed oxygen consumption rate and ATP level in BC cells. Reversely, reduced miR-503-3p or upregulated DACT2 exerted opposite effects. This study revealed that reduction of macrophage-derived exosomal miR-503-3p repressed glycolysis and promoted mitochondrial oxidative phosphorylation in BC by elevating DACT2 and inactivating Wnt/β-catenin signaling pathway. Our research may provide novel targets for BC treatment.

Multifaceted WNT Signaling at the Crossroads Between Epithelial-Mesenchymal Transition and Autophagy in Glioblastoma

Tumor cells can employ epithelial-mesenchymal transition (EMT) or autophagy in reaction to microenvironmental stress. Importantly, EMT and autophagy negatively regulate each other, are able to interconvert, and both have been shown to contribute to drug-resistance in glioblastoma (GBM). EMT has been considered one of the mechanisms that confer invasive properties to GBM cells. Autophagy, on the other hand, may show dual roles as either a GBM-promoter or GBM-suppressor, depending on microenvironmental cues. The Wingless (WNT) signaling pathway regulates a plethora of developmental and biological processes such as cellular proliferation, adhesion and motility. As such, GBM demonstrates deregulation of WNT signaling in favor of tumor initiation, proliferation and invasion. In EMT, WNT signaling promotes induction and stabilization of different EMT activators. WNT activity also represses autophagy, while nutrient deprivation induces β-catenin degradation via autophagic machinery. Due to the importance of the WNT pathway to GBM, and the role of WNT signaling in EMT and autophagy, in this review we highlight the effects of the WNT signaling in the regulation of both processes in GBM, and discuss how the crosstalk between EMT and autophagy may ultimately affect tumor biology.

Gint4.T-Modified DNA Tetrahedrons Loaded with Doxorubicin Inhibits Glioma Cell Proliferation by Targeting PDGFRβ

Glioma is one of the deadliest intrinsic brain tumours due to its invasive growth. The effect of glioma treatment is poor because of the presence of the blood-brain barrier and blood tumour barrier and insufficient drug targeting. DNA tetrahedrons (TDN) show great potential for drug delivery and may be a novel therapeutic strategy for glioma. In this study, we used TDN to deliver doxorubicin (DOX) for the glioma therapy. Gint4.T, an aptamer that could recognize platelet-derived growth factor receptor β on tumour cell, was used to modify TDN (Apt-TDN) for targeted drug delivery. The TDN were self-assembled by one-step synthesis, which showed small size (10 nm) and negative charge. Fetal bovine serum test showed its stability as a drug delivery vehicle. Apt-TDN could be effectively taken up by U87MG cells. Compared with DOX and DOX@TDN (TDN loaded with DOX), the DOX@Apt-TDN (Gint4.T-modified TDN loaded with DOX) showed more early apoptosis rate, higher cell cycle arrest, and greater cytotoxicity towards U87MG cells. In conclusion, our findings indicated that DOX@Apt-TDN provides a novel therapy with promising clinical application for gliomas patients.

DACT2 modulated by TFAP2A-mediated allelic transcription promotes EGFR-TKIs efficiency in advanced lung adenocarcinoma

Patients with epidermal growth factor receptor (EGFR)-mutant advanced non-small-cell lung cancer (NSCLC) benefits from EGFR-tyrosine kinase inhibitor (TKI) treatment. However, drug resistance to EGFR-TKIs remains a great challenge. Single nucleotide polymorphisms (SNPs) may significantly influence prognosis of EGFR-TKI therapy. Herein, we hypothesized that the functional SNP in DACT2, coding a pivotal inhibitor of the Wnt/β-catenin signaling, may affect gene expression, which in turn, impact prognosis of NSCLC treated with EGFR-TKIs. Genotypes of the DACT2 promoter rs9364433 SNP were determined in two independent cohorts consisted of 319 EGFR-TKI treated stage IIIB/IV NSCLC patients. The allele-specific regulation on DACT2 expression by rs9364433 and impacts of DACT2 on gefitinib sensitivity was evaluated in vitro and in vivo. Cox regression analyses demonstrated that rs9364433 was significantly associated with patient survival in both cohorts (all P < 0.05). Reporter gene assays and Electrophoretic Mobility Shift Assays demonstrated that rs9364433 has an allele-specific effect on gene expression modulated by transcription factor TFAP2A. The G allele associated with diminished TFAP2A binding leads to significantly decreased DACT2 expression in NSCLC cell lines and tissues. Consistently, DACT2 could evidently increase the anti-proliferation effect of gefitinib on NSCLC cells. Our findings elucidated potential clinical implications of DACT2, which may result in better understanding and outcome assessment of EGFR-TKI treatments.

Actin like-6A promotes glioma progression through stabilization of transcriptional regulators YAP/TAZ

Increased Actin-like 6A (ACTL6A) expression has been implicated in the development of diverse cancers and recently associated with the Hippo signaling pathway, which is known to regulate biological properties, including proliferation, tissue regeneration, stem cell biology, as well as tumorigenesis. Here we first show that ACTL6A is upregulated in human gliomas and its expression is associated with glioma patient survival. ACTL6A promotes malignant behaviors of glioma cells in vitro and in orthotopic xenograft model. In co-immunoprecipitation assays, we discover that ACTL6A physically associated with YAP/TAZ and furthermore disrupts the interaction between YAP and β-TrCP E3 ubiquitin ligase, which promotes YAP protein degradation. Moreover, effects of ACTL6A on glioma cells proliferation, migration, and invasion could be mediated by YAP/TAZ. These data indicate that ACTL6A may contribute to cancer progression by stabilizing YAP/TAZ and therefore provide a novel therapeutic target for the treatment of human gliomas.

The new 6q27 tumor suppressor DACT2, frequently silenced by CpG methylation, sensitizes nasopharyngeal cancer cells to paclitaxel and 5-FU toxicity via β-catenin/Cdc25c signaling and G2/M arrest

BACKGROUND

Nasopharyngeal carcinoma (NPC) is prevalent in South China, including Hong Kong and Southeast Asia, constantly associated with Epstein-Barr virus (EBV) infection. Epigenetic etiology attributed to EBV plays a critical role in NPC pathogenesis. Through previous CpG methylome study, we identified Disheveled-associated binding antagonist of beta-catenin 2 (DACT2) as a methylated target in NPC. Although DACT2 was shown to regulate Wnt signaling in some carcinomas, its functions in NPC pathogenesis remain unclear.

METHODS

RT-PCR, qPCR, MSP, and BGS were applied to measure expression levels and promoter methylation of DACT2 in NPC. Transwell, flow cytometric analysis, colony formation, and BrdU-ELISA assay were used to assess different biological functions affected by DACT2. Immunofluorescence, Western blot, and dual-luciferase reporter assay were used to explore the mechanisms of DACT2 functions. Chemosensitivity assay was used to measure the impact of DACT2 on chemotherapy drugs.

RESULTS

We found that DACT2 is readily expressed in multiple normal adult tissues including upper respiratory tissues. However, it is frequently downregulated in NPC and correlated with promoter methylation. DNA methyltransferase inhibitor 5-aza-2'-deoxycytidine restored its expression in NPC cells. DACT2 methylation was further detected in 29/32 (91%) NPC tumors but not in any (0/8) normal nasopharyngeal tissue samples. Ectopic expression of DACT2 in NPC cells suppressed their proliferation, migration, and invasion through downregulating matrix metalloproteinases. DACT2 expression also induced G2/M arrest in NPC cells through directly suppressing β-catenin/Cdc25c signaling, which sensitized NPC cells to paclitaxel and 5-FU, but not cisplatin.

CONCLUSION

Our results demonstrate that DACT2 is frequently inactivated epigenetically by CpG methylation in NPC, while it inhibits NPC cell proliferation and metastasis via suppressing β-catenin/Cdc25c signaling. Our study suggests that DACT2 promoter methylation is a potential epigenetic biomarker for the detection and chemotherapy guidance of NPC.