Proteogenomic characterization of small cell lung cancer identifies biological insights and subtype-specific therapeutic strategies.

We performed comprehensive proteogenomic characterization of small cell lung cancer (SCLC) using paired tumors and adjacent lung tissues from 112 treatment-naive patients who underwent surgical resection. Integrated multi-omics analysis illustrated cancer biology downstream of genetic aberrations and highlighted oncogenic roles of FAT1 mutation, RB1 deletion, and chromosome 5q loss. Two prognostic biomarkers, HMGB3 and CASP10, were identified. Overexpression of HMGB3 promoted SCLC cell migration via transcriptional regulation of cell junction-related genes. Immune landscape characterization revealed an association between ZFHX3 mutation and high immune infiltration and underscored a potential immunosuppressive role of elevated DNA damage response activity via inhibition of the cGAS-STING pathway. Multi-omics clustering identified four subtypes with subtype-specific therapeutic vulnerabilities. Cell line and patient-derived xenograft-based drug tests validated the specific therapeutic responses predicted by multi-omics subtyping. This study provides a valuable resource as well as insights to better understand SCLC biology and improve clinical practice.

circRNA TATA-box binding protein associated factor 15 acts as an oncogene to facilitate bladder cancer progression through targeting miR-502-5p/high mobility group box 3.

Circular RNAs (circRNAs) are key in regulating bladder cancer progression. This study explored the effects of circRNA TATA-box binding protein associated factor 15 (circTAF15) on bladder cancer progression. We enrolled 80 bladder cancer patients to examine the relationship between circTAF15 expression and clinical features. The function of circTAF15 on bladder cancer cell viability, proliferation, migration, invasion, and glycolysis was monitored by cell counting kit-8 assay, 5-Ethynyl-2'-deoxyuridine experiment, Transwell experiment, and glycolysis analysis. Dual luciferase reporter gene assay, RNA pull-down assay, and RNA immunoprecipitation assay were used to verify the binding between circTAF15 and miR-502-5p or between miR-502-5p and high mobility group box 3 (HMGB3). circTAF15 effect on in vivo growth of bladder cancer was investigated by xenograft tumor experiment. Quantitative real-time polymerase chain reaction, Western blot, and immunohistochemistry were implemented to investigate the expression levels of genes. circTAF15 was upregulated in bladder cancer patients, associated with unfavorable outcomes. circTAF15 knockdown attenuated bladder cancer cell viability, proliferation, migration, invasion, epithelial-mesenchymal transition, and glycolysis. circTAF15 suppressed miR-502-5p expression, and miR-502-5p inhibited HMGB3 expression. Low miR-502-5p expression was associated with unfavorable outcomes in bladder cancer patients. miR-502-5p silencing and HMGB3 overexpression counteracted the inhibition of circTAF15 knockdown on the malignant phenotype of bladder cancer cells. circTAF15 knockdown attenuated the in vivo growth of bladder cancer cells. circTAF15 enhanced the progression of bladder cancer through upregulating HMGB3 via suppressing miR-502-5p. circTAF15 may be a novel target to treat bladder cancer in the future.

Macrophage-derived exosomal HMGB3 regulates silica-induced pulmonary inflammation by promoting M1 macrophage polarization and recruitment.

BACKGROUND: Chronic inflammation and fibrosis are characteristics of silicosis, and the inflammatory mediators involved in silicosis have not been fully elucidated. Recently, macrophage-derived exosomes have been reported to be inflammatory modulators, but their role in silicosis has not been explored. The purpose of the present study was to investigate the role of macrophage-derived exosomal high mobility group box 3 (HMGB3) in silica-induced pulmonary inflammation. METHODS: The induction of the inflammatory response and the recruitment of monocytes/macrophages were evaluated by immunofluorescence, flow cytometry and transwell assays. The expression of inflammatory cytokines was examined by RT-PCR and ELISA, and the signalling pathways involved were examined by western blot analysis. RESULTS: HMGB3 expression was increased in exosomes derived from silica-exposed macrophages. Exosomal HMGB3 significantly upregulated the expression of inflammatory cytokines, activated the STAT3/MAPK (ERK1/2 and p38)/NF-κB pathways in monocytes/macrophages, and promoted the migration of these cells by CCR2. CONCLUSIONS: Exosomal HMGB3 is a proinflammatory modulator of silica-induced inflammation that promotes the inflammatory response and recruitment of monocytes/macrophages by regulating the activation of the STAT3/MAPK/NF-κB/CCR2 pathways.

Structure and Functions of HMGB3 Protein.

HMGB3 protein belongs to the group of HMGB proteins from the superfamily of nuclear proteins with high electrophoretic mobility. HMGB proteins play an active part in almost all cellular processes associated with DNA-repair, replication, recombination, and transcription-and, additionally, can act as cytokines during infectious processes, inflammatory responses, and injuries. Although the structure and functions of HMGB1 and HMGB2 proteins have been intensively studied for decades, very little attention has been paid to HMGB3 until recently. In this review, we summarize the currently available data on the molecular structure, post-translational modifications, and biological functions of HMGB3, as well as the possible role of the ubiquitin-proteasome system-dependent HMGB3 degradation in tumor development.

SOX9 and HMGB3 co-operatively transactivate NANOG and promote prostate cancer progression.

BACKGROUND: The homeodomain-containing transcription factor NANOG is overexpressed in prostate adenocarcinoma (PCa) and predicts poor prognosis. The SOX family transcription factor SOX9, as well as the transcription co-activator HMGB3 of the HMGB family, are also overexpressed and may play pivotal roles in PCa. However, it is unknown whether SOX9 and HMGB3 interact with each other, or if they regulate NANOG gene transcription. METHODS: We identified potential SOX9 responsive elements in NANOG promoter, and investigated if SOX9 regulated NANOG transcription in co-operation with HMGB3 by experimental analysis of potential SOX9 binding sites in NANOG promoter, reporter gene transcription assays with or without interference or artificial overexpression of SOX9 and/or HMGB3, and protein-binding assays of SOX9-HMGB3 interaction. Clinicopathologic and prognostic significance of SOX9-HMGB3 overexpression in PCa was analyzed. RESULTS: SOX9 activated NANOG gene transcription by preferentially binding to a highly conserved consensus cis-regulatory element (-573 to -568) in NANOG promoter, and promoted the expression of NANOG downstream oncogenic genes. Importantly, HMGB3 functioned as a partner of SOX9 to co-operatively enhance transactivation of NANOG by interacting with SOX9, predominantly via the HMG Box A domain of HMGB3. Overexpression of SOX9 and/or HMGB3 enhanced PCa cell survival and cell migration and were significantly associated with PCa progression. Notably, Cox proportional regression analysis showed that co-overexpression of both SOX9 and HMGB3 was an independent unfavorable prognosticator for both CRPC-free survival (relative risk [RR] = 3.779，95% confidence interval [CI]: 1.159-12.322, p = 0.028) and overall survival (RR = 3.615，95% CI: 1.101-11.876, p = 0.034). CONCLUSIONS: These findings showed a novel SOX9/HMGB3/NANOG regulatory mechanism, deregulation of which played important roles in PCa progression.

HMGB3 promotes the malignant phenotypes and stemness of epithelial ovarian cancer through the MAPK/ERK signaling pathway.

BACKGROUND: Ovarian cancer, particularly epithelial ovarian cancer (EOC), is the leading cause of cancer-related mortality among women. Our previous study revealed that high HMGB3 levels are associated with poor prognosis and lymph node metastasis in patients with high-grade serous ovarian carcinoma; however, the role of HMGB3 in EOC proliferation and metastasis remains unknown. METHODS: MTT, clonogenic, and EdU assays were used to assess cell proliferation. Transwell assays were performed to detect cell migration and invasion. Signaling pathways involved in HMGB3 function were identified by RNA sequencing (RNA-seq). MAPK/ERK signaling pathway protein levels were evaluated by western blot. RESULTS: HMGB3 knockdown inhibited ovarian cancer cell proliferation and metastasis, whereas HMGB3 overexpression facilitated these processes. RNA-seq showed that HMGB3 participates in regulating stem cell pluripotency and the MAPK signaling pathway. We further proved that HMGB3 promotes ovarian cancer stemness, proliferation, and metastasis through activating the MAPK/ERK signaling pathway. In addition, we demonstrated that HMGB3 promotes tumor growth in a xenograft model via MAPK/ERK signaling. CONCLUSIONS: HMGB3 promotes ovarian cancer malignant phenotypes and stemness through the MAPK/ERK signaling pathway. Targeting HMGB3 is a promising strategy for ovarian cancer treatment that may improve the prognosis of women with this disease. Video Abstract.

Tanshinone IIA (TSIIA) represses the progression of non-small cell lung cancer by the circ_0020123/miR-1299/HMGB3 pathway.

Tanshinone IIA (TSIIA), a multi-pharmaceutical compound, has been demonstrated to have anti-tumor properties. This study explores the potential regulatory mechanism of TSIIA on non-small cell lung cancer (NSCLC) progression. The cytotoxicity of TSIIA was evaluated by MTT (3-(4,5-Dimethylthiazol-2-yl)-2,5-Diphenyltetrazolium Bromide) and LDH (lactate dehydrogenase) assays. Expression levels of circ_0020123 (hsa_circ_0020123) and microRNA-1299 (miR-1299) were assessed by quantitative real-time polymerase chain reaction (qRT-PCR). Cell proliferation, migration, invasion, and apoptosis were analyzed by MTT, colony formation, transwell, wound-healing, or flow cytometry assays. The relationship between miR-1299 and circ_0020123 or HMGB3 (high mobility group box 3) was verified by the dual-luciferase reporter and/or RNA immunoprecipitation (RIP) assays. Protein level of HMGB3 was measured by western blotting. The relationship between TSIIA and circ_0020123 was confirmed by xenograft assay. TSIIA reduced xenograft tumor growth in vivo and repressed proliferation, migration, invasion, and facilitated apoptosis of NSCLC cells in vitro. TSIIA reduced circ_0020123 and HMGB3 expression, whereas elevated miR-1299 expression in NSCLC cells. Circ_0020123 knockdown enhanced the repressive influence of TSIIA treatment on the malignancy of NSCLC cells in vitro and in vivo. Circ_0020123 sponged miR-1299 to regulate HMGB3 expression under TSIIA treatment. MiR-1299 inhibitor reversed circ_0020123 knockdown-mediated influence on malignant behaviors of NSCLC cells under TSIIA treatment. HMGB3 elevation offset the suppressive impact of miR-1299 mimic on the malignancy of NSCLC cells under TSIIA treatment. TSIIA curbed NSCLC progression by the circ_0020123/miR-1299/HMGB3 axis, manifesting that the TSIIA/circ_0020123/miR-1299/HMG regulatory network might be a potential treatment strategy for NSCLC.

Circ_LDLR promotes the progression of papillary thyroid carcinoma by regulating miR-1294/HMGB3 axis.

Circular RNAs (circRNAs) have been found to be associated with the development and progression of cancers including papillary thyroid carcinoma (PTC). Circ_LDLR has been reported to be highly expressed in PTC, but its underlying mechanism of action has not been fully elucidated. This study aimed to investigate the role of circ_LDLR in PTC. The expression of circ_LDLR, miR-1294 and high mobility group box (HMGB) 3 was detected by quantitative real-time polymerase chain reaction (qRT-PCR). CCK-8 assay and transwell assays were employed to value cell viability, invasion and migration abilities. Western blot assay was to detect HMGB3 protein expression. Luciferase reporter gene and pull down assay were used to validate the interaction between miR-1294 and HMGB3 or circ_LDLR. Circ_LDLR showed high expression levels in PTC tissues and cells and knockdown of it inhibited the growth, invasion, and migration of PTC cells. In addition, miR-1294 was considered as a downstream target of circ_LDLR, and inhibition of miR-1294 partially reversed the inhibitory effects of circ_LDLR knockdown on PTC cells growth, invasion, and migration. More importantly, HMGB3 was identified as a downstream target of miR-1294. Our findings suggest circ_LDLR may plays a promoting role in PTC by downregulating miR-1294 and upregulating HMGB3 expression. Therefore, circ_LDLR may serve as a valuable prognostic biomarker and therapeutic target for PTC.

Circ-IGF1R Affects the Progression of Colorectal Cancer by Activating the miR-362-5p/HMGB3-Mediated Wnt/ß-Catenin Signal Pathway.

The aim of this study was to investigate the role of circRNA insulin growth factor 1 receptor (circ-IGF1R) in colorectal cancer (CRC). Glycolytic metabolism was analyzed by glucose uptake and lactate production using the corresponding kits. The protein levels were determined using Western blot. The effect of circ-IGF1R on CRC in vivo was explored by xenograft experiment in mice. Circ-IGF1R was up-regulated in CRC tissues and cells. Knockdown of circ-IGF1R inhibited proliferation, migration, invasion and glycolysis but induced apoptosis of CRC cells. Circ-IGF1R interacted with miR-362-5p and miR-362-5p inhibitor attenuated the anti-tumor effects of circ-IGF1R downregulation on CRC cells. HMGB3 acted as a downstream target for miR-362-5p, and circ-IGF1R facilitated the malignant behaviors of CRC cells by regulating HMGB3. Circ-IGF1R activated the Wnt/ß-catenin pathway via targeting miR-362-5p/HMGB3 axis. Tumor growth in vivo was reduced after knockdown of circ-IGF1R. Circ-IGF1R might be a novel biomolecular target for CRC diagnosis and treatment.

Circ_CLIP2 promotes glioma progression through targeting the miR-195-5p/HMGB3 axis.

BACKGROUND: Circular RNA (circRNA) has been demonstrated to play key roles in regulating glioma progression. Understanding the regulatory mechanism of circRNA in glioma is vital to reveal the pathogenesis of glioma and develop novel therapeutic strategies. Therefore, our study focuses on the role and underlying mechanism of Circ_CLIP2 in glioma. METHODS: The expression of Circ_CLIP2, miR-195-5p and HMGB3 in glioma cells and tissues were analyzed using qRT-PCR. Cell proliferation was determined with colony formation and MTT assays. Cell cycle and apoptosis were examined by flow cytometry. Western blot was conducted for analyzing HMGB3, PCNA, Bax, Bcl-2, cleaved-caspase 3, Wnt-1 and ß-catenin. Dual-luciferase reporter assay was measured to investigate the interaction among Circ_CLIP2, miR-195-5p and HMGB3. RESULTS: The expression of Circ_CLIP2 and HMGB3 were increased while miR-195-5p was down-regulated in glioma cells and patients. Silencing of Circ_CLIP2 inhibited cell proliferation, enhanced cell apoptosis and inhibited the Wnt/ß-catenin signaling pathway. Circ_CLIP2 suppressed miR-195-5p expression by directly sponging miR-195-5p. MiR-195-5p inhibited HMGB3 expression via directly targeting HMGB3. Knockdown of miR-195-5p facilitated cell proliferation, inhibited cell apoptosis and activated Wnt/ß-catenin signaling, which were reversed by silencing of HMGB3. CONCLUSION: Knockdown of Circ_CLIP2 suppresses glioma progression by targeting miR-195-5p/HMGB3 thus inhibiting Wnt/ß-catenin signaling. This study may provide potential therapeutic targets against glioma.

High-mobility group box 3 (HMGB3) silencing inhibits non-small cell lung cancer development through regulating Wnt/ß-catenin pathway.

It has been reported that high-mobility group box 3 is overexpressed in various cancers. This study aimed to explore its function in non-small cell lung cancer (NSCLC). A546 and H460 cell lines were used for in vivo experiments, scratch healing tests, transwell migration and invasion experiments. It was first found that HMGB3 was highly expressed in tumor tissues in the patients and associated with NSCLC stage. Silencing of HMGB3 significantly slowed the growth, proliferation and invasion of NSCLC in vitro, and repressed cell growth in vivo. Mechanistic studies suggest that the observed effects were mediated by inhibiting the expression of ß-catenin/MMP7/c-Myc in Wnt pathway. Our study highlights the role of HMGB3 in NSCLC, which may provide a therapeutic target for the treatment of NSCLC.

CircMMP1 promotes the progression of glioma through miR-433/HMGB3 axis in vitro and in vivo.

Circular RNAs (circRNAs) are non-coding RNAs that have shown to regulate the progression of human diseases, including a variety of cancers. We aimed to investigate the function and the underlying working mechanism of circRNA matrix metallopeptidase 1 (circMMP1; hsa_circ_0024108) in glioma progression. Quantitative real-time polymerase chain reaction (qRT-PCR) was performed to examine the expression of circMMP1, microRNA-433-3p (written as "miR-433") and high mobility group box 3 (HMGB3). Nanoparticle tracking analysis (NTA) was used to analyze the relative concentration and size distribution of serum exosomes. Cell proliferation was analyzed via cell counting kit-8 (CCK8) assay and colony formation assay. Transwell migration and invasion assays were used to examine the metastasis ability of glioma cells. Cell apoptosis was assessed by flow cytometry. Dual-luciferase reporter assay and RNA immunoprecipitation (RIP) assay were used to verify the interactions of circMMP1/miR-433 and miR-433/HMGB3 messenger RNA (mRNA). Xenograft mouse model was built to clarify the role of circMMP1 in vivo. The results showed that high serum exosomal circMMP1 level might predict poor prognosis of glioma patients. CircMMP1 promoted the proliferation and motility and impeded the apoptosis of glioma cells. MiR-433 was a direct target of circMMP1, and circMMP1 silencing-mediated influences in glioma cells were partly alleviated by the knockdown of miR-433. MiR-433 directly interacted with HMGB3 mRNA, and HMGB3 overexpression partly counteracted the effects of miR-433 up-regulation in glioma cells. CircMMP1 enhanced HMGB3 level through sponging miR-433 in glioma cells. CircMMP1 silencing suppressed the progression of glioma in vivo. CircMMP1 promoted the progression of glioma through acting as a competitive endogenous RNA (ceRNA) of miR-433 to up-regulate HMGB3. CircMMP1 level in serum exosomes might be a potential marker for the diagnosis of glioma patients. Targeting circMMP1/miR-433/HMGB3 signaling might be a novel insight for glioma treatment.

LncRNA SNHG5 promotes nasopharyngeal carcinoma progression by regulating miR-1179/HMGB3 axis.

BACKGROUND: Long noncoding RNAs (lncRNAs) have been reported to be important regulators in pathogenesis of human cancers, including nasopharyngeal carcinoma (NPC). Here, we mainly aimed to explore the mechanisms of LncRNA-SNHG5/ miR-1179/HMGB3 axis in NPC progression. METHODS: RT-qPCR and Western blot analysis were employed to detect mRNA and protein expressions. CCK-8, Transwell and dual luciferase reporter assays were applied to investigate functions of LncRNA-SNHG5/miR-1179/HMGB3 axis. RESULTS: Upregulation of lncRNA-SNHG5 and downregulation of miR-1179 were identified in NPC, which were associated with adverse clinical outcomes. Functionally, upregulation of lncRNA-SNHG5 and downregulation of miR-1179 accelerated NPC cell proliferation, migration and invasion. Furthermore, lncRNA-SNHG5 acted as a molecular sponge of miR-1179 in NPC. Besides that, upregulation of HMGB3 was found in NPC, and knockdown of HMGB3 restrained NPC progression. Moreover, HMGB3, a target of miR-1179, regulated NPC progression by mediating LncRNA-SNHG5/miR-1179 axis. CONCLUSION: LncRNA SNHG5 serves as a tumor promoter in NPC by sponging miR-1179 and upregulating HMGB3.

Effects of microRNA-513b on cell proliferation, apoptosis, invasion, and migration by targeting HMGB3 through regulation of mTOR signaling pathway in non-small-cell lung cancer.

This study aimed to explore the underlying mechanism of miR-513b and HMGB3 in regulating non-small-cell lung cancer (NSCLC). NSCLC tumor, adjacent tissues, and cell lines were extracted, and the expression of miR-513b and HMGB3 were determined by quantitative real-time polymerase chain reaction (RT-qPCR) and western blot analysis. Then, miR-513b was overexpressed in NSCLC cell, and the proliferation, migration, invasion, and apoptosis of cells were determined by 3-(4,5-dimethyl-2-thiazolyl)-2,5-diphenyl-2H-tetrazolium bromide (MTT), wound healing, transwell, and flow cytometry, respectively. Regulatory relationship between miR-513b and HMGB3 was determined using luciferase activity reporter assay. Lastly, HMGB3 and/or miR-513b were overexpressed in NSCLC cells, and the proliferation, migration, invasion, and apoptosis of cells were determined. Compared with the controls, the expression of miR-513b was significantly downregulated in the NSCLC tissues and cells lines by RT-qPCR ( p < 0.05). However, the expression of HMGB3 was significantly downregulated at both messenger RNA and protein levels ( p < 0.05). Overexpression of miR-513b could significantly inhibit the proliferation, invasion, migration, and promote apoptosis of NSCLC cells ( p < 0.05). HMGB3 was a target of miR-513b, and overexpression of HMGB3 could obviously reverse the effect of miR-513 on the proliferation, invasion, migration, and apoptosis of NSCLC cells ( p < 0.05). The present results could suggest miR-513b was downregulated in NSCLC and could regulate the proliferation, invasion, migration, and apoptosis of NSCLC cells via HMGB3.

HMGB3 promotes the proliferation and metastasis of glioblastoma and is negatively regulated by miR-200b-3p and miR-200c-3p.

High mobility group box 3 (HMGB3) is strongly involved in oncogenesis in a variety of cancers. In the present study, we have explored the role of HMGB3 in glioblastoma multiforme (GBM) tumorigenesis and have identified the microRNAs (miRNAs) miR-200b-3p and miR-200c-3p as negative regulators of HMGB3 expression. We began by determining that endogenous HMGB3 expression levels were significantly elevated in GBM tissues and in 3 GBM cell lines. To study the function of HMGB3 in GBM, we transfected a small-interfering RNA (siRNA) against HMGB3 into GBM cell lines U251 and LN229. MTT and tumour sphere assays demonstrated that HMGB3 knockdown significantly inhibited cell proliferation. Wound healing and transwell assays determined that HMGB3 knockdown substantially suppressed GBM cell migration and invasion. We evaluated the effects of HMGB3 knockdown on MAPK phosphorylation and target gene expression, finding that HMGB3 knockdown significantly reduced MAPK phosphorylation (p-ERK (1/2), p-p38, and p-JNK). We then used the biologic prediction algorithm TargetScan to identify the 3' untranslated region (3'-UTR) of HMGB3 as a target of miR-200b-3p and miR-200c-3p. Luciferase, qRT-PCR, and western blot assays confirmed that miR-200b-3p and miR-200c-3p bind and inhibit HMGB3 expression. Finally, Pearson correlation analyses demonstrated a negative correlation between relative HMGB3 mRNA and miR-200b/c-3p expression levels in GBM tissue samples. Overall, the present study strongly suggests that HMGB3 promotes GBM oncogenesis through the MAPK signalling pathway while miR-200b-3p and miR-200c-3p inhibit its expression.

MiR-27b is epigenetically downregulated in tamoxifen resistant breast cancer cells due to promoter methylation and regulates tamoxifen sensitivity by targeting HMGB3.

MiR-27b downregulation is significantly associated with tamoxifen resistance in breast cancer cells. However, how it is downregulated in tamoxifen resistant (TamR) breast cancer cells and its downstream regulation were not clear. By performing MSP assay and QRT-PCR analysis with the use of 5-AZA-dC, a DNA methyltransferase inhibitor, we observed that TamR MCF-7 cells had significantly higher levels of methylation in the miR-27b promoter region than tamoxifen sensitive MCF-7 (TamS) cells and demethylation restored miR-27b expression. Re-expression of miR-27b sensitized TamR MCF-7 cells to tamoxifen, inhibited invasion and reversed epithelial-mesenchymal transition (EMT)-like properties. By using bioinformatics analysis and following dual luciferase and western blot analysis, this study confirmed a direct regulation of miR-27b on HMGB3 expression by binding to the 3'UTR. In addition, this study also found that silencing of HMGB3 indeed partially phenocopied the effects of miR-27b in reducing tamoxifen resistance and cell invasion and in reversing EMT-like properties. Therefore, we infer that HMGB3 is a functional target of miR-27b in modulation of tamoxifen resistance and EMT.

CircRUNX1 drives the malignant phenotypes of lung adenocarcinoma through mediating the miR-5195-3p/HMGB3 network.

BACKGROUND: Circular RNAs (circRNAs) are key factors in the regulation of cancer progression. However, the role of circRUNX1 in lung adenocarcinoma (LUAD) progression is unclear. METHODS: The expression levels of circRUNX1, microRNA (miR)-5195-3p, and high-mobility group protein B3 (HMGB3) were detected by quantitative real-time PCR. Cell proliferation, migration, invasion and apoptosis were analyzed by EdU staining, colony formation assay, transwell assay and flow cytometry. Protein levels were measured using western blot analysis. The interaction between miR-5195-3p and circRUNX1 or HMGB3 was verified by dual-luciferase reporter assay and RIP assay. Animal experiments were performed to investigate the role of circRUNX1 in LUAD tumorigenesis. RESULTS: We found that circRUNX1 was upregulated in LUAD tumor tissues and cells. CircRUNX1 knockdown suppressed LUAD cell proliferation and metastasis, while promoted apoptosis. In terms of mechanism, we found that circRUNX1 could sponge miR-5195-3p, and miR-5195-3p inhibitor abolished the regulation of circRUNX1 knockdown on LUAD cell proliferation, metastasis and apoptosis. In addition, miR-5195-3p could target HMGB3, and HMGB3 overexpression reversed the inhibition effect of miR-5195-3p on LUAD progression. Moreover, circRUNX1 knockdown reduced LUAD tumorigenesis. CONCLUSION: CircRUNX1 facilitated LUAD proliferation and metastasis by regulating the miR-5195-3p/HMGB3 axis, suggesting that it might be a possible therapeutic target for LUAD.

Two novel homologs of high mobility group box 3 gene in grass carp (Ctenopharyngodon idella): potential roles in innate immune responses.

High mobility group box 3 (HMGB3) protein is a universal sentinel in the activation of innate antiviral immune responses in mammalian cells of limited tissues. However, the underlying immune functions of HMGB3 responding to viruses and viral/bacterial pathogen-associated molecular patterns (PAMPs) are still unknown in teleosts. In the present study, two novel homologs of grass carp (Ctenopharyngodon idella) HMGB3 (designated as CiHMGB3a and CiHMGB3b) were identified and characterized. Quantitative RT-PCR analysis showed that CiHMGB3a and CiHMGB3b were widely expressed in tissues. The mRNA expressions of CiHMGB3a and CiHMGB3b were induced by grass carp reovirus (GCRV) challenges both in tissues and in cells, and CiHMGB3a played a more active role in antiviral immune responses. Viral PAMP stimulation evidenced that CiHMGB3a and CiHMGB3b mediated immune responses in CIK (C. idella kidney) cells. Interestingly, CiHMGB3a had little impact on bacterial PAMPs (LPS and PGN), whereas CiHMGB3b was critical responding to bacterial PAMPs stimulation. In overexpressions of CiHMGB3a and CiHMGB3b cells, the transcriptional levels of CiHMGB3a, CiHMGB3b, CiTRIF, CiIPS-1, CiIFN-I and CiMx1 were remarkably induced. In addition, CiMyD88 had vital impact on antiviral signaling channels in overexpression of CiHMGB3b cells. Furthermore, 96-well plate staining assay, virus titer test and GCRV quantitative analysis collectively indicated CiHMGB3a and CiHMGB3b exhibited substantial antiviral activity. These results suggest that CiHMGB3a and CiHMGB3b exert important functions in antiviral immune responses by TLRs and RLRs signaling pathways. Taken together, current study provides the first evidence that HMGB3 participates in broad antiviral and antibacterial immune responses in teleosts.

The expression of high mobility group protein 3 (HMGB3) in breast cancer with emphasis on its role in lymphovascular invasion.

Lymphovascular invasion (LVI) is a common phenomenon in breast cancer (BC), and it is correlated to poor outcome. However, the biomarkers that influence the development of LVI remain to be defined. Through rigorous bioinformatics analyses, high mobility group protein 3 (HMGB3) was revealed as a driver gene that is associated with the presence of LVI. The purpose of this study was to further investigate the role of HMGB3 in the pathogenesis of LVI in BC. In vitro functional assays were performed to investigate the effect of HMGB3 silencing on cell proliferation, migration, adherence and transmigration of BC cell lines with dermal lymphatic endothelial cells (DLECs) and human vascular endothelial cells (HUVECs). The correlation of HMGB3 expression with clinicopathological parameters was also assessed at the transcriptomic and the proteomic levels using large BC cohorts with well-characterised LVI status. Silencing HMGB3 reduced cell proliferation, migration, adherence and transmigration across endothelial cell lines. At the mRNA and protein levels, high HMGB3 expression was significantly correlated with LVI-positivity, higher tumour grade, lymph nodal stage, hormone receptor negativity, HER2 positivity and poor outcome. Moreover, high HMGB3 expression was an independent predictor of shorter breast cancer-specific survival. HMGB3 plays an oncogenic function and contributes to the development of LVI in BC. Results warrant further investigation as a potential target to inhibit LVI in BC.