MT1G induces lipid droplet accumulation through modulation of H3K14 trimethylation accelerating clear cell renal cell carcinoma progression.

BACKGROUND: Lipid droplet formation is a prominent histological feature in clear cell renal cell carcinoma (ccRCC), but the significance and mechanisms underlying lipid droplet accumulation remain unclear. METHODS: Expression and clinical significance of MT1G in ccRCC were analyzed by using TCGA data, GEO data and scRNASeq data. MT1G overexpression or knockdown ccRCC cell lines were constructed and in situ ccRCC model, lung metastasis assay, metabolomics and lipid droplets staining were performed to explore the role of MT1G on lipid droplet accumulation in ccRCC. RESULTS: Initially, we observed low MT1G expression in ccRCC tissues, whereas high MT1G expression correlated with advanced disease stage and poorer prognosis. Elevated MT1G expression promoted ccRCC growth and metastasis both in vitro and in vivo. Mechanistically, MT1G significantly suppressed acylcarnitine levels and downstream tricarboxylic acid (TCA) cycle activity, resulting in increased fatty acid and lipid accumulation without affecting cholesterol metabolism. Notably, MT1G inhibited H3K14 trimethylation (H3K14me3) modification. Under these conditions, MT1G-mediated H3K14me3 was recruited to the CPT1B promoter through direct interaction with specific promoter regions, leading to reduced CPT1B transcription and translation. CONCLUSIONS: Our study unveils a novel mechanism of lipid droplet accumulation in ccRCC, where MT1G inhibits CPT1B expression through modulation of H3K14 trimethylation, consequently enhancing lipid droplet accumulation and promoting ccRCC progression. Graphical abstract figure Schematic diagram illustrating MT1G/H3K14me3/CPT1B-mediated lipid droplet accumulation promoted ccRCC progression via FAO inhibition.

Arachidonic acid released by PIK3CA mutant tumor cells triggers malignant transformation of colonic epithelium by inducing chromatin remodeling.

Key gene mutations are essential for colorectal cancer (CRC) development; however, how the mutated tumor cells impact the surrounding normal cells to promote tumor progression has not been well defined. Here, we report that PIK3CA mutant tumor cells transmit oncogenic signals and result in malignant transformation of intestinal epithelial cells (IECs) via paracrine exosomal arachidonic acid (AA)-induced H3K4 trimethylation. Mechanistically, PIK3CA mutations sustain SGK3-FBW7-mediated stability of the cPLA2 protein, leading to the synthetic increase in AA, which is transported through exosome and accumulated in IECs. Transferred AA directly binds Menin and strengthens the interactions of Menin and MLL1/2 methyltransferase. Finally, the combination of VTP50469, an inhibitor of the Menin-MLL interaction, and alpelisib synergistically represses PDX tumors harboring PIK3CA mutations. Together, these findings unveil the metabolic link between PIK3CA mutant tumor cells and the IECs, highlighting AA as the potential target for the treatment of patients with CRC harboring PIK3CA mutations.

Betulinic acid arrests cell cycle at G2/M phase by up-regulating metallothionein 1G inhibiting proliferation of colon cancer cells.

Betulinic acid (BA) is a pentacyclic triterpene found in many plant species and has a broad-spectrum anti-tumor effect in various cancers, including colon cancer (CRC). However, its anticancer mechanism in CRC is no clear. RNA sequencing and bioinformatics analysis showed BA up-regulated 378 genes and down-regulated 137 genes in HT29 cells, while 2303 up-regulated and 1041 down-regulated genes were found in SW480 cells. KEGG enrichment analysis showed BA significantly stimulated the expression of metallothionein 1 (MT1) family genes in both HT29 and SW480 cells. Metallothionein 1G (MT1G) was the gene with the highest upregulation of MT1 family genes induced by BA dose-dependently. High MT1G expression enhanced the sensitivity of CRC cells to BA, whereas, MT1G knockdown had the opposite effect in vitro and in vivo. GSEA and GSCA showed genes affected by BA treatment were involved in cell cycle and G2/M checkpoint in CRC. Flow cytometry further exhibited BA reduced the percentage of G0/G1 cells and increased the percentage of G2/M cells in a dose-dependent manner, which could be rescued by MT1G knockdown. Moreover, MT1G also counteracted the BA-induced changes in cell cycle-related proteins (CDK2 and CDK4) and p-Rb. In summary, we have revealed a new anti-tumor mechanism that BA altered the cell cycle progression of CRC cells by upregulating MT1G gene, thereby inhibiting the proliferation of CRC cells.

TNF+ regulatory T cells regulate the stemness of gastric cancer cells through the IL13/STAT3 pathway.

Regulatory T cells (Tregs) are an important component of the tumor microenvironment; however, the interaction between Tregs and gastric cancer cells is not completely understood. Recent studies have shown that Tregs participate in cancer cell stemness maintenance. In this study, we performed single-cell RNA sequencing of gastric cancer and adjacent tissues and found that Tregs with high TNF expression were recruited to gastric cancer tissues and were significantly correlated with patient survival. TNF+ Tregs significantly contribute to tumor growth and progression. Our studies have further demonstrated that TNF+ Tregs promote the stemness of gastric cancer cells through the IL13/STAT3 pathway. Therefore, blocking the interaction between TNF+ Tregs and gastric cancer cells may be a new approach in the treatment of gastric cancer.

MARCKS is a New Prognostic Biomarker in Hepatocellular Carcinoma.

Background: Hepatocellular carcinoma (HCC) is one of the most common type of cancers, but there is still a lack of known biomarkers for the effective diagnosis or prognosis of HCC. Myristoylated alanine-rich C-kinase substrate (MARCKS) is a substrate of protein kinase C, which was located in the cell plasma membrane. The purpose of our study was to evaluate the role of MARCKS in HCC. Methods: The role of MARCKS in HCC was explored by bioinformatics and experiment. Results: We demonstrated that MARCKS expression was significantly elevated in HCC datasets of TCGA. MARCKS was up-regulated in tumor sample in HCC. Functional enrichment indicated that MARCKS-related differentially expressed genes (DEGs) were mainly enriched in cell junction tissue, response to growth factors and cell population proliferation. Tumor and ECM-receptor interactions related pathways were enriched by the KEGG. MARCKS expression in HCC patients was higher in females, younger individuals, and those at worse clinical stages. Cox regression analysis showed that MARCKS expression was a risk factor for overall survival and disease-specific survival of patients. Conclusion: MARCKS was up-regulated in HCC, may play a crucial role in HCCs, and has prognostic value for clinical outcomes.

AQP5 complements LGR5 to determine the fates of gastric cancer stem cells through regulating ULK1 ubiquitination.

BACKGROUND: Cancer stem cells (CSCs) are regarded as the "seed cells" for tumorigenesis, metastasis, recurrence and drug resistance. However, specific surface markers of CSCs of different origins have not been documented. METHODS: Single-cell sequencing was used to analyze the highly expressed genes in cancer stem cells of gastric cancer patients, and it was verified that AQP5 was specifically highly expressed in gastric cancer stem cells (GC-CSCs) in vivo and in vitro. The effect of AQP5-promoting LGR5 on the malignant biological function of GC-CSCs was investigated. The mechanism by which AQP5 affects GC-CSCs was explored through transcriptome sequencing, proteomic detection, mass spectrometry, etc. RESULTS: We report the identification and validation of AQP5 as a potentially specific surface marker of GC-CSCs. AQP5 was significantly upregulated in CSCs isolated from gastric cancer patients and in spheroid cells, and AQP5 was coexpressed with the canonical stem marker LGR5. Biologically, AQP5 promoted the sphere formation, proliferation, migration and invasion of GC cells in vitro and enhanced tumorigenesis in vivo. Furthermore, AQP5 coordinated with LGR5 and synergistically promoted the tumorigenesis of GC-CSCs. At the mechanistic level, AQP5 activated autophagy by inducing the LC3I/LC3II transformation in GC-CSCs, which was crucial for the biological functions of AQP5. Finally, we demonstrated that AQP5 recruited the E3 ligase TRIM21 to the key autophagy protein ULK1 and induced the K63-mediated ubiquitination of ULK1. CONCLUSIONS: We elucidate a novel surface marker, AQP5, which is specifically expressed by GC-CSCs. Furthermore, our study creates a link between AQP5 and LGR5 and highlights the necessity of targeting both surface markers simultaneously as a promising approach for the treatment of gastric cancer patients.

Long noncoding RNA LINC00930 promotes PFKFB3-mediated tumor glycolysis and cell proliferation in nasopharyngeal carcinoma.

BACKGROUND: Metabolic reprogramming is a hallmark of cancer. However, the roles of long noncoding RNAs (lncRNAs) in cancer metabolism, especially glucose metabolism remain largely unknown. RESULTS: In this study, we identified and functionally characterized a novel metabolism-related lncRNA, LINC00930, which was upregulated and associated with tumorigenesis, lymphatic invasion, metastasis, and poor prognosis in nasopharyngeal carcinoma (NPC). Functionally, LINC00930 was required for increased glycolysis activity and cell proliferation in multiple NPC models in vitro and in vivo. Mechanistically, LINC00930 served as a scaffold to recruit the RBBP5 and GCN5 complex to the PFKFB3 promoter and increased H3K4 trimethylation and H3K9 acetylation levels in the PFKFB3 promoter region, which epigenetically transactivating PFKFB3, and thus promoting glycolytic flux and cell cycle progression. Clinically, targeting LINC00930 and PFKFB3 in combination with radiotherapy induced tumor regression. CONCLUSIONS: Collectively, LINC00930 is mechanistically, functionally and clinically oncogenic in NPC. Targeting LINC00930 and its pathway may be meaningful for treating patients with NPC.

Signal transduction mechanism of exosomes in diabetic complications (Review).

Exosomes are vesicles with a particle size of 30-120 nm that are secreted by cells through exocytosis. The composition of an exosome includes a lipid bilayer and its internal package of biological molecules, such as proteins, ribonucleotides and deoxyribonucleotides. Diabetes is a chronic and refractory disease. The complications induced by high blood glucose have become a major problem in global public health and the pathogenesis of diabetic complications remains to be fully elucidated. In recent years, it has been gradually recognized that exosomes from different cell sources and their related molecules, particularly exosomal proteins and microRNAs, have an important role in the pathogenesis of diabetic complications, allowing for the exploration of the pathogenesis of diabetic complications from a molecular perspective. The present review summarizes the latest studies on exosomes from different cell sources in the pathogenesis of diabetic complications, which may provide novel targets for the prevention and treatment of diabetic complications.

The Role of RNA Methylation in Regulating Stem Cell Fate and Function-Focus on m6A.

The biological role of RNA methylation in stem cells has attracted increasing attention. Recent studies have demonstrated that RNA methylation plays a crucial role in self-renewal, differentiation, and tumorigenicity of stem cells. In this review, we focus on the biological role of RNA methylation modifications including N6-methyladenosine, 5-methylcytosine, and uridylation in embryonic stem cells, adult stem cells, induced pluripotent stem cells, and cancer stem cells, so as to provide new insights into the potential innovative treatments of cancer or other complex diseases.

Sox9 Is Crucial for Mesenchymal Stem Cells to Enhance Cutaneous Wound Healing.

BACKGROUND AND OBJECTIVES: Human umbilical cord mesenchymal stem cells (HUC-MSCs) are promising candidates for cell-based therapy in regenerative medicine or other diseases due to their superior characteristics, including higher proliferation, faster self-renewal ability, lower immunogenicity, a noninvasive harvest procedure, easy expansion in vitro, and ethical access, compared with stem cells from other sources. METHODS AND RESULTS: In the present study, we knocked down the expression of SOX9 in HUC-MSCs by lentivirus interference and found that knockdown of SOX9 inhibited the proliferation and migration of HUC-MSCs and influenced the expression of cytokines (IL-6 and IL-8), growth factors (GM-CSF and VEGF) and stemness-related genes (OCT4 and SALL4). In addition, the repair effect of skin with burn injury in rats treated with HUC-MSCs transfected with sh-control was better than that rats treated with HUC-MSCs transfected with shSOX9 or PBS, and the accessory structures of the skin, including hair follicles and glands, were greater than those in the other groups. We found that knockdown of the expression of SOX9 obviously inhibited the expression of Ki67, CK14 and CK18. CONCLUSIONS: In conclusion, this study will provide a guide for modifying HUC-MSCs by bioengineering technology in the future.

The Roles of Host Noncoding RNAs in Mycobacterium tuberculosis Infection.

Tuberculosis remains a major health problem. Mycobacterium tuberculosis, the causative agent of tuberculosis, can replicate and persist in host cells. Noncoding RNAs (ncRNAs) widely participate in various biological processes, including Mycobacterium tuberculosis infection, and play critical roles in gene regulation. In this review, we summarize the latest reports on ncRNAs (microRNAs, piRNAs, circRNAs and lncRNAs) that regulate the host response against Mycobacterium tuberculosis infection. In the context of host-Mycobacterium tuberculosis interactions, a broad and in-depth understanding of host ncRNA regulatory mechanisms may lead to potential clinical prospects for tuberculosis diagnosis and the development of new anti-tuberculosis therapies.

IL-17B/IL-17RB signaling cascade contributes to self-renewal and tumorigenesis of cancer stem cells by regulating Beclin-1 ubiquitination.

Cancer stem cells (CSCs) are characterized by robust self-renewal and tumorigenesis and are responsible for metastasis, drug resistance, and angiogenesis. However, the molecular mechanisms for the regulation of CSC homeostasis are incompletely understood. This study demonstrated that the interleukin-17 (IL-17)B/IL-17RB signaling cascade promotes the self-renewal and tumorigenesis of CSCs by inducing Beclin-1 ubiquitination. We found that IL-17RB expression was significantly upregulated in spheroid cells and Lgr5-positive cells from the same tumor tissues of patients with gastric cancer (GC), which was closely correlated with the degree of cancer cell differentiation. Recombinant IL-17B (rIL-17B) promoted the sphere-formation ability of CSCs in vitro and enhanced tumor growth and metastasis in vivo. Interestingly, IL-17B induced autophagosome formation and cleavage-mediated transformation of LC3 in CSCs and 293T cells. Furthermore, inhibition of autophagy activation by ATG7 knockdown reversed rIL-17B-induced self-renewal of GC cells. In addition, we showed that IL-17B also promoted K63-mediated ubiquitination of Beclin-1 by mediating the binding of tumor necrosis factor receptor-associated factor 6 to Beclin-1. Silencing IL-17RB expression abrogated the effects of IL-17B on Beclin-1 ubiquitination and autophagy activation in GC cells. Finally, we showed that IL-17B level in the serum of GC patients was positively correlated with IL-17RB expression in GC tissues, and IL-17B could induce IL-17RB expression in GC cells. Overall, the results elucidate the novel functions of IL-17B for CSCs and suggest that the intervention of the IL-17B/IL-17RB signaling pathway may provide new therapeutic targets for the treatment of cancer.

A New Antitumor Direction: Tumor-Specific Endothelial Cells.

Targeting tumor blood vessels is an important strategy for tumor therapies. At present, antiangiogenic drugs are known to have significant clinical effects, but severe drug resistance and side effects also occur. Therefore, new specific targets for tumor and new treatment methods must be developed. Tumor-specific endothelial cells (TECs) are the main targets of antiangiogenic therapy. This review summarizes the differences between TECs and normal endothelial cells, assesses the heterogeneity of TECs, compares tumorigenesis and development between TECs and normal endothelial cells, and explains the interaction between TECs and the tumor microenvironment. A full and in-depth understanding of TECs may provide new insights for specific antitumor angiogenesis therapies.

Dual Role of MSC-Derived Exosomes in Tumor Development.

Mesenchymal stem cells (MSCs) are a class of adult stem cells derived from the mesoderm. They can self-renew, have multidirectional differentiation potential, and can differentiate into a variety of mesenchymal tissues. MSCs can produce a large number of exosomes, which can mediate information exchange and transmission between cells in the tumor microenvironment under conditions of rest or stress. Recent studies have reported conflicting findings regarding the effect of MSC-derived exosomes on tumors. Some studies have suggested that MSC-derived exosomes can promote tumor growth and metastasis, but others have reported that they can inhibit tumor cell growth. Here, we investigate the two sides of the debate regarding the effect of MSC-derived exosomes on tumors and analyze the reasons for the divergent findings.

YAP promotes self-renewal of gastric cancer cells by inhibiting expression of L-PTGDS and PTGDR2.

INTRODUCTION: Cancer stem cells have been implicated angiogenesis of tumor and invasiveness, drug resistance in tumors. Yes-associated protein 1 (YAP) owns carcinogenic roles in various organs, but the role of YAP in cancer stem cells of gastric cancer (GC) remains unclear. In this study, we explored the function and mechanism of YAP in GC cancer stem cells. MATERIALS AND METHODS, AND RESULTS: First, we confirmed that the expression of YAP mRNA and protein in GC tissues was higher than in adjacent tissues by RT-PCR, western blot and immunohistochemistry. Immunofluorescence staining of the GC tissues revealed that the region of YAP expression coincided with the region of expression of the cancer stem cell marker SALL4 but did not overlap with that of the epithelial marker cytokeratin 14 (CK14). Additional research revealed that spherical cells expressed relatively high levels of YAP protein, and YAP overexpression reinforced self-renewal and expression of stem cell markers in the GC cells. Knockdown the expression of YAP reversed this phenomenon. Second, we examined the expression patterns of lipocalin-type prostaglandin D2 synthase (L-PTGDS) and prostaglandin D2 receptor 2 (PTGDR2) in GC tissues and proved that there was negatively correlation between the expression of L-PTGDS and PTGDR2 and YAP in GC tissues. Finally, we confirmed that YAP inhibited the expression of L-PTGDS and PTGDR2 by gain- and loss-of-function experiments. Moreover, the overexpression of L-PTGDS and PTGDR2 suppressed the proliferation and self-renewal induced by YAP in vitro and reversed the pro-tumor effect of YAP in vivo. CONCLUSION: Our results revealed a novel function of YAP and the mechanism underlying cancer stem cell regulation by YAP.

TRAF6 Promotes Gastric Cancer Cell Self-Renewal, Proliferation, and Migration.

Gastric cancer is the third most common type of tumor associated with death. TRAF6 belongs to the tumor necrosis factor receptor-associated factor family and has been demonstrated to be involved in tumor progression in various cancers. However, the exact effect of TRAF6 on gastric cancer stem cells has not been extensively studied. In this study, abnormal expression of TRAF6 was found in gastric cancer tissues. Overexpression of TRAF6 enhanced proliferation and migration, and TRAF6 knockdown reversed this phenomenon in gastric cancer cells. Moreover, TRAF6 may inhibit differentiation and promote stemness and epithelial-mesenchymal transition (EMT). Transcriptome profiles revealed 701 differentially expressed genes in the wild-type group and the TRAF6 knockout group. Potential molecules associated with cell proliferation and migration were identified, including MAPK, FOXO, and IL-17. In conclusion, TRAF6 is a significant factor promoting proliferation and migration in gastric cancer cells and may provide a new target for the accurate treatment of gastric cancer.

Transcriptome Analysis Reveals Key Genes and Pathways Associated with Metastasis in Breast Cancer.

BACKGROUND: Metastasis is the major cause of death in breast cancer patients. Although the strategies targeting metastasis have promoted survival, the underlying mechanisms still remain unclear. In this study, we used microarray data of primary breast tumor, tumor derived from bone and liver, and skin metastatic tissue, to identify the key genes and pathways that are involved in metastasis in breast cancer. METHODS: We first calculated the differentially expressed genes (DEGs) between three metastatic tissues and primary tumor tissue, and then used it to perform Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway enrichment analysis. Further, we analyzed the correlation of genes enriched in GO terms and KEGG pathways with survival of breast cancer patients. To identify the key genes and pathways associated with metastasis, we overlapped the DEGs and KEGG pathways. In our in vitro experiments, we knocked down the key gene, ERLIN2, and detected the PI3K expression in tumor cells to evaluate their effect on tumor metastasis. RESULTS: We identified six genes (ALOX15, COL4A6, LMB13, MTAP, PLA2G4A, TAT) that correlated with survival. Seven key genes (SNRPN, ARNT2, HDGFRP3, ERO1LB, ERLIN2, YBX2, EBF4) and seven signaling pathways (metabolic pathways, phagosome pathway, PI3K-AKT signaling pathway, focal adhesion, ECM-receptor interaction, pancreatic secretion, human papillomavirus infection) associated with metastasis were also identified. Our in vitro experiments revealed that ERLIN2 was highly expressed in MDA-MB231 cells compared to MCF-7 cells. Moreover, knockdown of ERLIN2 increased apoptosis, while inhibiting the proliferation, invasion, and migration ability of breast cancer cells. The PI3K/AKT signaling pathway was also found to be highly expressed in MDA-MB231 cells. CONCLUSION: Our results reveal the key genes and signaling pathways that contribute to metastasis, and highlight that strategic targeting of ENLIN2 and PI3K/AKT signaling pathways could inhibit metastasis of breast cancer.

Biological Properties and the Role of IL-25 in Disease Pathogenesis.

The interleukin- (IL-) 17 superfamily, a T cell-derived cytokine, consists of 6 ligands (IL-17A-IL-17F) and 5 receptors (IL-17RA-IL-17RE). IL-17A, a prototype member of this family, is involved in the pathogenesis of allergies, autoimmune diseases, allograft transplantations, and malignancies. By contrast, IL-17B is reported to be closely related to certain diseases, particularly tumors such as breast cancer, gastric cancer, and pancreatic cancer. Recently, the biological function of IL-17E (also called IL-25) in disease, particularly airway diseases, has attracted the attention of researchers. However, studies on IL-25 are scant. In this review, we detail the structural characteristics, expression patterns, responder cells, biological properties, and role of IL-25 in disease pathogenesis.

PGD2/PTGDR2 Signaling Restricts the Self-Renewal and Tumorigenesis of Gastric Cancer.

The antitumor effect of prostaglandin D2 (PGD2) on gastric cancer (GC) has been known for decades. However, the mechanism of PGD2's control of GC growth is unclear. Cancer stem cells (CSCs) are implicated in tumor neovascularization, invasiveness, and therapeutic resistance. Herein, we discovered that signaling between PGD2 and its receptor (PTGDR2) has the ability to restrict the self-renewal of GC cells in vitro and suppress tumor growth and metastasis in vivo. To obtain these findings, we first determined that PGD2 synthase (L-PTGDS) and PTGDR2 expression were lower in GC tissues than adjacent tissues and was associated with the patients' prognosis. Moreover, the expression of L-PTGDS and PTGDR2 was negatively correlated with the GC-CSC markers Sall4 and Lgr5 in GC tissues. Second, L-PTGDS and PTGDR2 expression were knocked down in CSC-like cells, resulting in enhanced expression of CSC markers and self-renewal ability. Direct PGD2 stimulation and L-PTGDS overexpression produced the opposite effect. Thirdly, PGD2 inhibited tumor growth and incidence rate in a subcutaneous tumor model and suppressed liver and mesenteric metastasis in a peritoneal metastasis model. Interfering with the expression of PTGDR2 reversed these effects in vivo. Last, a mechanistic study found that PGD2 inhibited STAT3 phosphorylation and nuclear expression. Further experiments revealed that the inhibitory effect of PGD2 on the expression of CSC markers disappeared after mutations were introduced into STAT3 phosphorylation (Thr705) site. In short, this study reveals a novel function of PGD2/PTGDR2 signaling on CSC regulation and provides a new way to control the development of GC. Stem Cells 2018;36:990-1003.