High mobility group AT-hook 2 regulates osteoblast differentiation and facial bone development.

The mutation and deletion of high mobility group AT-hook 2 (Hmga2) gene exhibit skeletal malformation, but almost nothing is known about the mechanism. This study examined morphological anomaly of facial bone in Hmga2-/- mice and osteoblast differentiation of pre-osteoblast MC3T3-E1 cells with Hmga2 gene knockout (A2KO). Hmga2-/- mice showed the size reduction of anterior frontal part of facial bones. Hmga2 protein and mRNA were expressed in mesenchymal cells at ossification area of nasal bone. A2KO cells differentiation into osteoblasts after reaching the proliferation plateau was strongly suppressed by alizarin red and alkaline phosphatase staining analyses. Expression of osteoblast-related genes, especially Osterix, was down-regulated in A2KO cells. These results demonstrate a close association of Hmga2 with osteoblast differentiation of mesenchymal cells and bone growth. Although future studies are needed, the present study suggests an involvement of Hmga2 in osteoblast-genesis and bone growth.

High-mobility group AT-hook 2 promotes growth and metastasis and is regulated by miR-204-5p in oesophageal squamous cell carcinoma.

BACKGROUND: To investigate the expression of high-mobility group AT-hook 2 (HMGA2) and miR-204-5p in oesophageal squamous cell carcinoma (ESCC) and their biological roles in ESCC development and progression. METHODS: HMGA2 and miR-204-5p expression levels in ESCC tissues and cell lines were detected by qRT-PCR, Western blotting and immunohistochemical staining. ESCC cell lines were transfected with a small interfering RNA for HMGA2 and miR-204-5p mimic to downregulate and upregulate the expression levels of HMGA2 and miR-204-5p, respectively. The growth, migration and invasion abilities of ESCC cells were assessed by MTT, colony formation, wound-healing and Transwell assays, respectively. A luciferase reporter gene assay was used to determine whether the 3'-untranslated coding regions of HMGA2 could be directly bound by miR-204-5p. RESULTS: HMGA2 expression was markedly upregulated (P < .001), while miR-204-5p expression was markedly downregulated (P = .003) in ESCC tissues compared with adjacent normal tissues. HMGA2 expression was correlated with tumour size, invasion depth, lymph node metastasis and tumour-node-metastasis stage (all P < .05) and was identified as an independent prognostic factor for ESCC patients. The expression levels of HMGA2 and miR-204-5p were negatively correlated (r2  = 0.609, P < .001). HMGA2 knockdown or miR-204-5p overexpression markedly inhibited ESCC cell growth, migration and invasion (P < .05). In addition, restoration of HMGA2 expression partly reversed the inhibitory effects of miR-204-5p overexpression on migration and invasion (P < .05). The luciferase reporter gene assay suggested that HMGA2 is a direct downstream target of miR-204-5p. CONCLUSION: HMGA2 functions as an oncogene in the growth and metastasis of ESCC and is negatively regulated by miR-204-5p.

hsa_circ_0062019 promotes the proliferation, migration, and invasion of prostate cancer cells via the miR-195-5p/HMGA2 axis.

Circular RNA (circRNA) is a new class of non-coding RNA. It was reported that circRNA involves in the metastasis of cancer. The aim of this study is to explore the role and mechanism of circRNA hsa_circ_0062019 in the development of prostate cancer (PCa). Our results showed that hsa_circ_0062019 was highly expressed in PCa cell lines. Cell Counting Kit-8 assay revealed that upregulation of hsa_circ_0062019 boosted PCa cell proliferation, and silencing of hsa_circ_0062019 inhibited cell proliferation. Meanwhile, transwell assay proved that upregulation of hsa_circ_0062019 facilitated PCa cell invasion and migration, while downregulation of hsa_circ_0062019 inhibited these malignant phenotypes. Furthermore, luciferase reporter assay proved the binding of hsa_circ_0062019 with miR-195-5p and the binding between miR-195-5p and high mobility group AT-hook 2 (HMGA2), suggesting that hsa_circ_0062019 promoted the expression of HMGA2 by sponging miR-195-5p. In addition, our results revealed that the hsa_circ_0062019-induced PCa cell malignant phenotypes were notably reversed by the downregulation of HMGA2. Overall, our study demonstrated that hsa_circ_0062019 promoted PCa cell proliferation, migration, and invasion via upregulation of HMGA2 expression by sponging miR-195-5p. Our study proved a novel molecular mechanism of PCa development and provided a potential target for the treatment of PCa.

Systematic molecular and clinical analysis of uterine leiomyomas from fertile-aged women undergoing myomectomy.

STUDY QUESTION: What are the distributions and associated clinical characteristics of mediator complex subunit 12 (MED12), high mobility group AT-hook 2 (HMGA2) and fumarate hydratase (FH) aberrations in uterine leiomyomas from fertile-aged myomectomy patients? SUMMARY ANSWER: These driver mutations account for the majority (83%) of tumours in fertile-aged patients. WHAT IS KNOWN ALREADY: Alterations affecting MED12, HMGA2 and FH account for 80-90% of uterine leiomyomas from middle-aged hysterectomy patients, while the molecular background of tumours from young myomectomy patients has not been systematically studied. STUDY DESIGN, SIZE, DURATION: A retrospective series of 361 archival uterine leiomyoma samples from 234 women aged ≤45 years undergoing myomectomy in 2009-2014 was examined. Associations between the molecular data and detailed clinical information of the patients and tumours were analysed. PARTICIPANTS/MATERIALS, SETTING, METHODS: DNA was extracted from formalin-fixed paraffin-embedded samples and MED12 exons 1 and 2 were sequenced to identify mutations. Level of HMGA2 expression was evaluated by immunohistochemistry. Biallelic FH inactivation was analysed with 2-succinylcysteine staining, which is an indirect method of assessing FH deficiency. All patients' medical histories were reviewed, and clinical information of patients and tumours was combined with molecular data. MAIN RESULTS AND THE ROLE OF CHANCE: The median age at operation was 34 years. The majority (58%) of patients were operated on for a single leiomyoma. Known driver mutations were identified in 83% of tumours (71% MED12; 9% HMGA2; 3% FH). In solitary leiomyomas, the MED12 mutation frequency was only 43%, and 29% were wild-type for all driver alterations. MED12 mutations were associated with multiple tumours, smaller tumour size and subserosal location. LIMITATIONS, REASONS FOR CAUTION: Although comprehensive, the study is retrospective in nature and all samples have been collected for routine diagnostic purposes. The use of paraffin-embedded samples and immunohistochemistry may have led to an underestimation of mutations. Due to the limited sample size and rarity of especially FH-deficient leiomyomas, the data are partly descriptive. WIDER IMPLICATIONS OF THE FINDINGS: The contribution of driver mutations in leiomyomas from young myomectomy patients is comparable to tumours obtained from hysterectomies of mostly middle-aged women. Our results support the earlier findings that MED12 mutations are associated with multiple tumours, smaller tumour size and subserosal location. The study emphasizes the distinct molecular background of solitary leiomyomas, and more research is needed to clarify the underlying causes of the notable proportion of wild-type leiomyomas. STUDY FUNDING/COMPETING INTEREST(S): The study was supported by the Academy of Finland (307773), the Sigrid Jusélius Foundation, the Cancer Foundation Finland and the iCAN Digital Precision Cancer Medicine Flagship. The authors declare no conflicts of interest. TRIAL REGISTRATION NUMBER: N/A.

Long non-coding RNA LINC00460 promotes proliferation and inhibits apoptosis of cervical cancer cells by targeting microRNA-503-5p.

Long non-coding RNAs are associated with the pathogenesis of cancers. Moreover, LINC00460 is involved in the development of multiple cancers. However, the function of LINC00460 in cervical cancer (CC) remains inconclusive. Herein, CC tissues and tumor-adjacent tissues were collected from patients. The effect of LINC00460 silencing in cell proliferation and apoptosis in CC was explored in vitro and in vivo. Additionally, the interaction between LINC00460 and miR-503-5p was analyzed using dual luciferase reporter assay. The expression of genes and proteins was assayed using quantitative real-time PCR, western blotting and immunohistochemistry, cell viability using MTT assay, cell cycle distribution using flow cytometry, cell apoptosis using Annexin V staining, Hoechst staining and TUNEL assay. LINC00460 levels in CC tissues were higher than tumor-adjacent tissues. LINC00460 silencing suppressed proliferation and promoted apoptosis of CC cells as evidenced by decreased cell viability, inhibited proliferation-related protein and cell cycle protein expressions and G1/S transition, increased apoptotic cells and Hoechst-positive cells, and enhanced apoptosis-related protein expressions. LINC00460 could bind to miR-503-5p and LINC00460 silencing enhanced miR-503-5p expression and inhibited its target gene expressions in CC cells. MiR-503-5p inhibition reversed LINC00460 silencing-caused inhibition of cell proliferation and miR-503-5p target gene expressions, and promotion of cell apoptosis. LINC00460 silencing also attenuated tumor growth, promoted miR-503-5p levels and cell apoptosis, and inhibited cell proliferation and miR-503-5p target gene expressions in tumor tissues. Hence, LINC00460 functioned as an oncogene in CC that affected cell proliferation and apoptosis via sponging miR-503-5p. This study provides a novel therapeutic target for CC.

Effects of HMGA2 gene downregulation by siRNA on lung carcinoma cell migration in A549 cell lines.

BACKGROUND: Although there are multiple treatments for lung cancer, the death rate of this cancer remains high because of metastasis in earlier stages. So a novel treatment for overcoming metastasis is urgently needed. Overexpression of high-mobility group AT-hook 2 (HMGA2), a nonhistone chromosomal protein has been observed in metastatic cancers. So, we suggested that HMGA2 upregulation may play a critical role in treating lung cancer. METHODS: The A549 cells were transfected with specific HMGA2 small interfering RNA (siRNA) using transfection reagent. Relative HMGA2 and matrix metallopeptidase 1 (MMP1), C-X-C chemokine receptor type 4 (CXCR4), vimentin, and E-cadherin messenger RNA expression levels were measured by quantitative real-time polymerase chain reaction. To diagnose cytotoxic effect of HMGA2 siRNA and other components of transfection process, 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide assay was applied. The migration capacity after transfection with HMGA2 siRNA was detected by wound-healing assay. RESULTS: HMGA2 siRNA significantly reduced HMGA2 expression in a dose-dependent manner 48 hours after transfection. Expression levels of MMP1, vimentin, and CXCR4 were reduced, but E-cadherin level was not changed meaningfully. HMGA2 knockdown significantly reduced cell survival rate and also led to the inhibition of cell migration. CONCLUSIONS: Our results indicated that RNA interference by downregulation of HMGA2 gene expression and affecting downstream genes led to the inhibition of cell migration and proliferation. Therefore, HMGA2 siRNA might be an alternative treatment option for metastatic lung cancer.

HMGA2 promotes intestinal tumorigenesis by facilitating MDM2-mediated ubiquitination and degradation of p53.

High mobility group A2 (HMGA2) is an architectural transcription factor that promotes human colorectal cancer (CRC) aggressiveness by modulating the transcription of target genes. The degradation of p53 is mediated by murine double minute 2 (MDM2) in a proteasome-dependent manner. Here we report that HMGA2 promotes cell cycle progression and inhibits apoptosis in CRC cells in vitro. We also developed an intestinal epithelial cell-specific Hmga2 knock-in (KI) mouse model. It revealed that the Hmga2 KI promoted chemical carcinogen-induced tumorigenesis in the intestine in vivo. In studying the underlying molecular mechanism, we found that HMGA2 formed a protein complex with p53. The tetramerization domain of p53 (amino acids 294-393) and the three AT-hook domains (amino acids 1-83) of HMGA2 were responsible for their direct interaction. We also found that HMGA2 directly bound to MDM2 and the central acidic and zinc finger domains of MDM2 (amino acids 111-360) were required for interaction with HMGA2. Furthermore, our results indicated that HMGA2 promoted MDM2-mediated p53 ubiquitination and degradation. Interestingly, Hmga2 overexpression in Hmga2 KI mice resulted in an increase in the accumulation of ubiquitinated p53. In addition, in two large CRC cohorts, it was demonstrated that high HMGA2 expression was predictive of an adverse outcome in the p53-negative subgroup of CRC patients. In summary, our data have established for the first time a novel mechanism by which HMGA2 functions with p53 and MDM2 to promote CRC progression. Copyright © 2018 Pathological Society of Great Britain and Ireland. Published by John Wiley & Sons, Ltd.

Circulating cell-free high mobility group AT-hook 2 mRNA as a detection marker in the serum of colorectal cancer patients.

BACKGROUND: Detection of circulating cell-free mRNA serves as noninvasive tools for cancer diagnosis. As an oncofetal protein, HMGA2 (high mobility group AT-hook 2) is upregulated in colorectal cancer (CRC) tissues. However, it is not clear whether the increased levels of circulating cell-free HMGA2 mRNA functions as potential biomarkers for improved diagnosis of CRC. METHODS: To assess its clinical significance in diagnosis and prediction, we evaluated serum levels of circulating HMGA2 mRNA in CRC patients and in healthy controls. In this study, 83 CRC patients and 11 normal controls were enrolled in this study. We used real-time quantitative reverse transcription-PCR to evaluate the plasma mRNA levels of HMGA2 and analyze the correlation between their expression and clinicopathologic characteristics. RESULTS: We found that the levels of HMGA2 mRNA were significantly higher in CRC patients compared with healthy volunteers. The patients with right-sided CRC, colon cancer, positive nerve infiltration, positive vascular invasion, negative microsatellite instability (MSI), and increasing in serum carbohydrate antigen (CA) 199 had higher levels of plasma HMGA2 mRNA. A strong positive correlation between circulating cell-free HMGA2 mRNA and CA199 level in serum was found in our study. Furthermore, statistical analysis revealed that levels of HMGA2 mRNA in plasma and in tumors were strictly correlated. CONCLUSIONS: Collectively, our data suggested that cell-free HMGA2 mRNA in plasma might function as a novel diagnostic marker for CRC.

Angiotensin II type 2 receptor-interacting protein 3a inhibits ovarian carcinoma metastasis via the extracellular HMGA2-mediated ERK/EMT pathway.

Local migration and long-distance metastasis is the main reason for higher mortality of ovarian cancer. Microtubule-associated tumor suppressor 1/angiotensin II type 2 receptor-interacting protein is associated with tumor initiation and progression and exerts anti-tumor effects. High mobility group AT-hook 2 is overexpressed in majority of metastatic carcinomas, which contributes to carcinomas metastasis through Snail-induced epithelial-to-mesenchymal transition signal pathway. The purpose of this study was to investigate the signal pathway of microtubule-associated tumor suppressor 1/angiotensin II type 2 receptor-interacting protein-mediated anti-tumor effects. Our data observed that ovarian carcinoma cells exhibited lower expression of angiotensin II type 2 receptor-interacting protein 3a and higher expression of high mobility group AT-hook 2 compared to normal ovarian cells. Restoration of angiotensin II type 2 receptor-interacting protein 3a expression in ovarian carcinoma cells inhibited high mobility group AT-hook 2 expression and exhibited anti-proliferative effects. In addition, angiotensin II type 2 receptor-interacting protein 3a treatment suppressed the phosphorylation of epithelial-to-mesenchymal transition and extracellular signal-regulated kinase in ovarian carcinoma cells. We also observed that angiotensin II type 2 receptor-interacting protein 3a restoration downregulated expression of Snail, E-Cadherin, N-Cadherin, and Vimentin in ovarian carcinoma cells, whereas angiotensin II type 2 receptor-interacting protein 3a knockdown enhanced the phosphorylation of extracellular signal-regulated kinase and epithelial-to-mesenchymal transition. In vivo assay indicated that angiotensin II type 2 receptor-interacting protein 3a inhibited ovarian tumor growth and elevated survival of tumor-bearing immunodeficient mice. Tumor histological analysis indicated that Snail, E-Cadherin, N-Cadherin, and Vimentin expression levels were downregulated via decreasing high mobility group AT-hook 2 expression. Furthermore, upregulation of angiotensin II type 2 receptor-interacting protein 3a impaired the phenotype of extracellular signal-regulated kinase and epithelial-to-mesenchymal transition in ovarian carcinoma cells and tumor tissues. Taken together, angiotensin II type 2 receptor-interacting protein 3a presents potential in suppressing the proliferation and aggressiveness of ovarian carcinoma cells through the high mobility group AT-hook 2-mediated extracellular signal-regulated kinase/epithelial-to-mesenchymal transition signal pathway.

[Hmga2 knockdown enhances osteogenic differentiation of adipose-derived mesenchymal stem cells and accelerates bone defect healing in mice].

OBJECTIVE: To investigate the role of high-mobility group AT-hook 2 (HMGA2) in osteogenic differentiation of adipose-derived mesenchymal stem cells (ADSCs) and the effect of Hmga2 knockdown for promoting bone defect repair. METHODS: Bioinformatics studies using the GEO database and Rstudio software identified HMGA2 as a key factor in adipogenic-osteogenic differentiation balance of ADSCs. The protein-protein interaction network of HMGA2 in osteogenic differentiation was mapped using String and visualized with Cytoscape to predict the downstream targets of HMGA2. Primary mouse ADSCs (mADSCs) were transfected with Hmga2 siRNA, and the changes in osteogenic differentiation of the cells were evaluated using alkaline phosphatase staining and Alizarin red S staining. The expressions of osteogenic markers Runt-related transcription factor 2 (RUNX2), osteopontin (OPN), and osteocalcein (OCN) in the transfected cells were detected using RT-qPCR and Western blotting. In a mouse model of critical-sized calvarial defects, mADSCs with Hmga2-knockdown were transplanted into the defect, and bone repair was evaluated 6 weeks later using micro-CT scanning and histological staining. RESULTS: GEO database analysis showed that HMGA2 expression was upregulated during adipogenic differentiation of ADSCs. Protein-protein interaction network analysis suggested that the potential HMGA2 targets in osteogenic differentiation of ADSCs included SMAD7, CDH1, CDH2, SNAI1, SMAD9, IGF2BP3, and ALDH1A1. In mADSCs, Hmga2 knockdown significantly upregulated the expressions of RUNX2, OPN, and OCN and increased cellular alkaline phosphatase activity and calcium deposition. In a critical-sized calvarial defect model, transplantation of mADSCs with Hmga2 knockdown significantly promoted new bone formation. CONCLUSION: HMGA2 is a crucial regulator of osteogenic differentiation in ADSCs, and Hmga2 knockdown significantly promotes osteogenic differentiation of ADSCs and accelerates ADSCs-mediated bone defect repair in mice.

[Retracted] MicroRNA­219 is downregulated in non­small cell lung cancer and inhibits cell growth and metastasis by targeting HMGA2.

Following the publication of this paper, it was drawn to the Editor's attention by a concerned reader that certain of the Transwell migration and invasion assay data shown in Figs. 2C and 4C were strikingly similar to data that had already been published in different form in another article written by different authors at a different research institute [Yang S, Zhang Y, Zhao X, Wang J and Shang J: microRNA­361 targets Wilms' tumor 1 to inhibit the growth, migration and invasion of non­small­cell lung cancer cells. Mol Med Rep 14: 5415­5421, 2016].  Owing to the fact that the contentious data in the above article had already been published prior to its submission to Molecular Medicine Reports, the Editor has decided that this paper should be retracted from the Journal. The authors were asked for an explanation to account for these concerns, but the Editorial Office did not receive a reply. The Editor apologizes to the readership for any inconvenience caused. [Molecular Medicine Reports 16: 3557­3564, 2017; DOI: 10.3892/mmr.2017.7000].

High Mobility Group AT-hook 2: A Biomarker Associated with Resistance to Enzalutamide in Prostate Cancer Cells.

Metastatic prostate cancer (mPCa) is a leading cause of mortality, partly due to its resistance to anti-androgens like enzalutamide. Snail can promote this resistance by increasing full-length AR and AR-V7. High Mobility Group AT-hook 2 (HMGA2), a DNA-binding protein upstream of Snail, is crucial in proliferation and epithelial-mesenchymal transition (EMT). This study examines HMGA2's role in enzalutamide resistance. LNCaP and 22Rv1 cells overexpressing wild-type HMGA2, but not truncated HMGA2, showed EMT. Both variants led to a decreased sensitivity to enzalutamide but not alisertib compared to Neo control cells. The overexpression of HMGA2 did not alter AR expression. Enzalutamide-resistant C4-2B cells (C4-2B MDVR) had higher HMGA2 and AR/AR variant expression than enzalutamide-sensitive C4-2B cells but remained sensitive to alisertib. The HMGA2 knockdown in C4-2B MDVR cells increased sensitivity to both enzalutamide and alisertib without changing AR expression. A clinical analysis via cBioPortal revealed HMGA2 alterations in 3% and AR alterations in 59% of patients. The HMGA2 changes were linked to treatments like enzalutamide, abiraterone, or alisertib, with amplifications more prevalent in bone, lymph node, and liver metastases. Conclusively, HMGA2 is a potential biomarker for enzalutamide resistance in mPCa, independent of Snail and AR signaling, and alisertib may be an effective treatment for mPCa that expresses HMGA2.

HDAC3 Impairs Cardiac Function in Chronic Heart Failure Rats via Mediating MicroRNA-26b-3p to Target High Mobility Group AT-Hook 2.

BACKGROUND: Histone deacetylase 3 (HDAC3) has been studied in chronic heart failure (CHF), while the regulatory mechanism of HDAC3 on the development of CHF in regulating microRNA (miR)-26b-3p/high mobility group AT-hook 2 (HMGA2) axis has not been extensively investigated. This study aimed to probe the effects of HDAC3, miR-26b-3p and HMGA2 on CHF. METHODS: CHF rat models were established using aortic coarctation. HDAC3, miR-26b-3p and HMGA2 levels in CHF rats were examined. Thereafter, the CHF rats were injected with relative oligonucleotides and plasmids of HDAC3, miR-26b-3p and HMGA2 to detect the cardiac function, inflammatory reaction, myocardial tissue pathological changes, and cardiomyocyte apoptosis. The binding relationship between miR-26b-3p and HMGA2 and the interaction between HDAC3 and miR-26b-3p were validated. RESULTS: HDAC3 and HMGA2 were elevated, while miR-26b-3p was decreased in CHF rats. The reduced HDAC3 or HMGA2 or enriched miR-26b-3p attenuated cardiac dysfunction, inflammatory reaction, myocardial tissue pathological changes and cardiomyocyte apoptosis in CHF rats, while the reduction of miR-26b-3p exerted the opposite effects. Furthermore, the inhibition of the miR-26b-3p or elevation of HMGA2 reversed the effect of reduced HDAC3 on mitigating CHF progression. Mechanically, miR-26b-3p targeted HMGA2 and HDAC3 bound to miR-26-3p. CONCLUSION: Downregulation of HDAC3 relieves cardiac function in CHF rats via mediating miR-26b-3p/HMGA2 axis. This study provides novel theory references and a distinct direction for the therapy strategies of CHF.

[Retracted] MicroRNA­599 targets high­mobility group AT­hook 2 to inhibit cell proliferation and invasion in clear cell renal carcinoma.

Following the publication of the above paper, it was drawn to the Editors' attention by a concerned reader that cell migration and invasion assay data shown in Fig. 5C were strikingly similar to data appearing in different form in other articles by different authors, which have been retracted. Owing to the fact that the contentious data in the above article were already under consideration for publication, or had already been published, elsewhere when it was submitted to Molecular Medicine Reports, the Editor has decided that this paper should be retracted from the Journal. The authors were asked for an explanation to account for these concerns, but the Editorial Office did not receive any reply. The Editor apologizes to the readership for any inconvenience caused. [Molecular Medicine Reports 17: 7451­7459, 2018; DOI: 10.3892/mmr.2018.8755].

Fusion of the High-mobility Group AT-Hook 2 (HMGA2) and the Gelsolin (GSN) Genes in Lipomas With t(9;12)(q33;q14) Chromosomal Translocation.

BACKGROUND/AIM: Lipomas are benign tumors composed of mature fat cells. They are common soft tissue tumors that often carry chromosome aberrations involving 12q14 resulting in rearrangements, deregulation, and generation of chimeras of the high-mobility group AT-hook 2 gene (HMGA2) which maps in 12q14.3. In the present study, we report the finding of t(9;12)(q33;q14) translocation in lipomas and describe its molecular consequences. MATERIALS AND METHODS: Four lipomas from two male and two female adult patients were selected because their neoplastic cells carried a t(9;12)(q33;q14) as the sole karyotypic aberration. The tumors were investigated using RNA sequencing, reverse transcription polymerase chain reaction (RT-PCR), and Sanger sequencing techniques. RESULTS: RNA sequencing of a t(9;12)(q33;q14)-lipoma detected an in-frame fusion of HMGA2 with the gelsolin gene (GSN) from 9q33. RT-PCR together with Sanger sequencing confirmed the presence of an HMGA2::GSN chimera in the tumor as well as in two other tumors from which RNA was available. The chimera was predicted to code for an HMGA2::GSN protein which would contain the three AT-hook domains of HMGA2 and the entire functional part of GSN. CONCLUSION: t(9;12)(q33;q14) is a recurrent cytogenetic aberration in lipomas and generates an HMGA2::GSN chimera. Similar to what is seen in other rearrangements of HMGA2 in mesenchymal tumors, the translocation physically separates the part of HMGA2 encoding AT-hook domains from the gene's 3'-terminal part which contains elements that normally regulate HMGA2 expression.

Hmga2 deficiency is associated with allometric growth retardation, infertility, and behavioral abnormalities in mice.

The high mobility group AT-hook 2 (HMGA2) protein works as an architectural regulator by binding AT-rich DNA sequences to induce conformational changes affecting transcription. Genomic deletions disrupting HMGA2 coding sequences and flanking noncoding sequences cause dwarfism in mice and rabbits. Here, CRISPR/Cas9 was used in mice to generate an Hmga2 null allele that specifically disrupts only the coding sequence. The loss of one or both alleles of Hmga2 resulted in reduced body size of 20% and 60%, respectively, compared to wild-type littermates as well as an allometric reduction in skull length in Hmga2-/- mice. Both male and female Hmga2-/- mice are infertile, whereas Hmga2+/- mice are fertile. Examination of reproductive tissues of Hmga2-/- males revealed a significantly reduced size of testis, epididymis, and seminal vesicle compared to controls, and 70% of knock-out males showed externalized penis, but no cryptorchidism was observed. Sperm analyses revealed severe oligospermia in mutant males and slightly decreased sperm viability, increased DNA damage but normal sperm chromatin compaction. Testis histology surprisingly revealed a normal seminiferous epithelium, despite the significant reduction in testis size. In addition, Hmga2-/- mice showed a significantly reduced exploratory behavior. In summary, the phenotypic effects in mouse using targeted mutagenesis confirmed that Hmga2 is affecting prenatal and postnatal growth regulation, male reproductive tissue development, and presents the first indication that Hmga2 function is required for normal mouse behavior. No specific effect, despite an allometric reduction, on craniofacial development was noted in contrast to previous reports of an altered craniofacial development in mice and rabbits carrying deletions of both coding and noncoding sequences at the 5' part of Hmga2.

Fusion of the HMGA2 and BNC2 Genes in Uterine Leiomyoma With t(9;12)(p22;q14).

BACKGROUND/AIM: The translocation t(9;12) (p22;q14~15) has been reported in lipomas, pleomorphic adenomas, a myolipoma, two chondroid hamartomas, and two uterine leiomyomas. In lipomas and pleomorphic adenomas, the translocation fuses HMGA2 (12q14) with the NFIB gene from 9p22; in myolipoma, it fuses HMGA2 with C9orf92 from 9p22; and in chondroid hamartomas, fluorescence in situ hybridization (FISH) investigations showed the chromosomal aberration to cause intragenic rearrangement of HMGA2. The translocation's molecular consequence in a uterine leiomyoma is described here. MATERIALS AND METHODS: A typical leiomyoma was investigated using banding cytogenetics, FISH, RNA sequencing, reverse transcription polymerase chain reaction and Sanger sequencing. RESULTS: A single translocation, t(9;12)(p22;q14) leading to an HMGA2::BNC2 chimera, was found in tumor cells. A sequence of the untranslated part of exon 5 of HMGA2 (nucleotide 1035 in the NCBI reference sequence NM_003483.4) had fused with a sequence from the untranslated part of exon 7 of BNC2 from 9p22 (nucleotide 9284 in reference sequence NM_017637.6). CONCLUSION: At the molecular level, the t(9;12)(p22;q14~15) found in several benign tumors appears to be heterogeneous fusing HMGA2 with either BNC2, C9orf92 or NFIB which all three map close to one another within a 3 Mbp region in 9p22. Because the fusion point in HMGA2 in the present tumor lays downstream from the first Let-7 miRNA consensus binding site, we conclude that deletion of the first Let-7 miRNA binding site is not important for the transcriptional upregulation of HMGA2 caused by the genomic rearrangement.

Circular ribonucleic acid nucleoporin 98 knockdown alleviates high glucose-induced proliferation, fibrosis, inflammation and oxidative stress in human glomerular mesangial cells by regulating the microribonucleic acid-151-3p-high mobility group AT-hook 2 axis.

AIMS/INTRODUCTION: This study aimed to investigate the role and mechanism of circular ribonucleic acid nucleoporin 98 (circNUP98) in diabetic nephropathy (DN). MATERIALS AND METHODS: Human glomerular mesangial cells (HMCs) were stimulated with high glucose (HG) to imitate the growth environment of cells under the DN condition. Levels of genes and proteins were tested by quantitative reverse transcription polymerase chain reaction and western blot. Cell proliferation, apoptosis and inflammatory response were analyzed by using cell counting kit-8, flow cytometry and enzyme-linked immunosorbent assay analysis, respectively. Oxidative stress and fibrosis were evaluated by detecting the activity of reactive oxygen species, malondialdehyde, superoxide dismutase, fibronectin and collagen IV. The binding interaction between microribonucleic acid (miR)-151-3p and high mobility group AT-hook 2 (HMGA2) or circNUP98 was confirmed using dual-luciferase reporter, pull-down and ribonucleic acid immunoprecipitation assays. Exosomes were isolated by ultracentrifugation, and qualified by transmission electron microscopy, nanoparticle tracking analysis and western blot. RESULTS: CircNUP98 expression was higher in the serum of DN patients and HG-stimulated HMCs. Functionally, circNUP98 knockdown alleviated HG-induced proliferation, fibrosis, inflammatory response and oxidative stress in HMCs. Mechanistically, circNUP98 directly sponged miR-151-3p, which targeted HMGA2. Rescue experiments showed that miR-151-3p reversed the inhibitory effects of circNUP98 knockdown on HG-induced HMC dysfunction. Furthermore, miR-151-3p re-expression also led to an inhibition of the aforementioned biological behaviors, which was attenuated by HMGA2 upregulation. Besides that, CircNUP98 was found to be packaged into exosomes of DN, and exosomal circNUP98 possessed diagnostic value for DN patients. CONCLUSION: CircNUP98 knockdown alleviates HG-induced proliferation, fibrosis inflammation and oxidative stress in HMCs by regulating the miR-151-3p-HMGA2 axis, which might provide a potential approach for DN therapeutics.

Circ_0000658 knockdown inhibits epithelial-mesenchymal transition in bladder cancer via miR-498-induced HMGA2 downregulation.

BACKGROUND: Epithelial-mesenchymal transition (EMT) has been associated with the angiogenesis and oncogenic phenotypes of multiple malignant tumors including bladder cancer (BCa). Circular RNAs (circRNAs) are recognized as crucial regulators in the EMT. This study aims to illustrate the possible role of circular RNA_0000658 (circ_0000658) in BCa and the underlying molecular mechanism. METHODS: The expression of circ_0000658, microRNA (miR)-498, and high mobility group AT-hook 2 (HMGA2) was assessed in cancer and adjacent normal tissue collected from BCa patients and human BCa cell lines (MGH-U3, T24, 5637 and SW780). BCa cells were transduced with a series of overexpression or shRNA plasmids to clarify the function of circ_0000658 and miR-498 on the oncogenic phenotypes and EMT of BCa cells. Further, we established nude mice xenografted with BCa cells to validate the roles of circ_0000658 on tumor growth in vivo. RESULTS: Circ_0000658 was highly expressed in BCa tissue samples and cell lines, which indicated a poor prognosis of BCa patients. Circ_0000658 competitively bound to miR-498 and thus restricted miR-498 expression. Meanwhile, circ_0000658 weakened the binding of miR-498 to the target gene HMGA2 and upregulated the HMGA2 expression. Circ_0000658 elevation or miR-498 knockdown augmented oncogenic phenotypes and EMT of BCa cells, corresponding to a reduction in the expression of ß-catenin and E-cadherin as well as an increase in the expression of N-cadherin, Slug, Snail, ZEB1 and Twist. Inhibition of HMGA2 reversed the effects of circ_0000658 overexpression on tumor growth in vivo. CONCLUSION: Altogether, our study uncovered the tumor-promoting role of circ_0000658 in BCa via the miR-498/HMGA2 axis.

HMGA2 Immunoexpression is frequent in salivary gland pleomorphic adenoma: immunohistochemical and molecular analyses of PLAG1 and HMGA2 in 25 cases.

The main oncologic events in pleomorphic adenoma (PA) are the translocations of Pleomorphic adenoma gene 1 (PLAG1) on chromosome 8q12 and High-mobility group AT-hook 2 (HMGA2) on chromosome 12q14.3 with various fusion partners. These translocations result in the transcriptional up-regulation of PLAG1 and HMGA2 proteins. We carried out a preliminary evaluation of PLAG1 translocation by fluorescence in-situ hybridization (FISH), immunohistochemistry (IHC) and HMGA2 IHC on twenty-five archived formalin-fixed paraffin-embedded tissues of PAs and its clinicopathologic features. Only eight cases were successfully hybridized and 50% of the interpretable cases were considered positive for PLAG1 translocation. PLAG1 IHC was only positive in 2 (8%) of the 25 cases stained, including one of the positive PLAG1 translocation cases. HMGA2 IHC was positive in 12 (48%) of the 25 cases stained including 2 (50%) of the 4 cases identified with PLAG1 translocation by FISH, 3 (75%) of the 4 cases negative for PLAG1 translocation by FISH and 7 (41%) of the 17 cases with failed hybridization. Overall, 15 (60%) of the 25 PA cases demonstrated PLAG1 and/or HMGA2 alterations confirmed either by FISH or IHC. In conclusion, PLAG1 and HMGA2 alterations were confirmed either by FISH or IHC in this cohort and HMGA2 alteration is a common event in PAs of salivary gland.