High Mobility Group AT-hook 2 Gene Research Articles

A variant of uncertain significance of the HMGA2 gene in a child with Silver-Russell syndrome-like phenotype: a case report.

Silver-Russell syndrome 5 (SRS5) is characterized by asymmetric intrauterine growth restriction (IUGR), poor postnatal growth, macrocephaly at birth, and feeding difficulties. Other possible features include triangular shaped face, prominent forehead, hypertelorism, epicanthus, micrognathia, brachydactyly, clinodactyly of the 5th finger, and syndactyly of the 2nd and 3rd toes. Pathogenic variants of the HMGA2 (high mobility group AT-hook 2) gene, on chromosome 12q14, which regulates the transcription of growth factor IGF2, have recently been associated with this syndrome. Herein, we present a 2.5-year-old boy with growth delay, SRS-like phenotype, and a variant of uncertain significance in the HMGA2 gene, which has not, to the best of our knowledge, been described to date in the medical literature. So far, 28 pathogenic variants ofthe HMGA2 gene in patients with clinical SRS phenotype have recently been reported. Therefore, HMGA2 gene testing should alwaysbe done in SRS patients who are found to be negative for the typical 11p15 (epi)mutations and matUPD7, while the mutations should also be added to growth retardation disorder panels.

Exploration of the Polymorphism Distribution of Bovine HMGA2 Gene in Worldwide Breeds and Its Associations with Ovarian Traits.

The high-mobility group AT-hook 2(HMGA2) gene has been widely studied in the context of cancer and animal growth. However, recently, several studies have uncovered its critical role in cell proliferation. A genome-wide association study (GWAS) further suggests that the HMGA2 gene is a candidate gene in fertility, indicating its connection not only to growth traits but also to reproduction, specifically ovarian traits. Thus, this study aimed to analyze the distribution of the HMGA2 gene in 54 bovine breeds worldwide, identify important short fragment variants (indels), and investigate the relationship between HMGA2 and ovarian development. The dataset included genotypic information from a bovine population of 634 individuals (n = 634). After genotyping and analyzing four selected loci, we found that one out of four loci, rs133750033 (P4-D22-bp), was polymorphic. Our results also reveal that this indel of HMGA2 is significantly associated with certain ovarian traits (p < 0.05). Specifically, it has connection with ovarian length (p = 0.004) and ovarian height (p = 0.026) during diestrus. Additionally, we discovered a higher expression of the HMGA2 gene in Asian cattle breeds. In summary, this study suggests that HMGA2 has the potential to serve as an animal fertility testing marker gene. Moreover, these findings contribute to a more promising outlook for the bovine industry.

MiR-129 Weakens Proliferation of Non-Small Cell Lung Cancer Cells via Targeted Regulation of High-Mobility Group AT-Hook 2

This study investigated the role of micro ribonucleic acid (miR)-129 in non-small cell lung cancer (NSCLC) by examining its effects on cell proliferation and apoptosis, as well as its relationship with the high-mobility group AT-hook 2 (HMGA2) target gene. Human NSCLC tissues were collected, and cancerous cells and normal cells were isolated and cultured. In vitro cultured NSCLC cells were transfected with miR-129 mimics or HMGA2-small interfering RNA (siRNA). The expression levels of miR-129 and HMGA2 were measured using quantitative reverse transcription-polymerase chain reaction (qRT-PCR), while cell proliferation was assessed using the cell counting kit-8 (CCK-8) assay. The targeted regulation between miR-129 and HMGA2 was examined using a luciferase reporter assay system, and protein expression was determined by Western blotting (WB). Flow cytometry was utilized to measure the cell apoptosis rate. NSCLC tissues and cells exhibited significantly decreased miR-129 expression and increased HMGA2 expression compared to normal tissues and cells. Transfection with miR-129 mimics and HMGA2-siRNA effectively reduced HMGA2 gene and protein expression in NSCLC cells, leading to decreased proliferation and increased apoptosis. The luciferase reporter assay confirmed targeted regulation between miR-129 and HMGA2. In summary, miR-129 may suppress NSCLC cell proliferation and induce apoptosis by targeting HMGA2 expression.

Front Cover: Green Tea Epigallocatechin Gallate Inhibits Preadipocyte Growth via the microRNA‐let‐7a/HMGA2 Signaling Pathway

Mol. Nutr. Food Res. 2023, 67, 202200336 DOI: 10.1002/mnfr.202200336 Green tea epigallocatechin-3-gallate (EGCG) inhibits the growth of 3T3-L1 white and D12 beige preadipocytes at least through modulations of microRNA-let-7a and high mobility group AT-hook 2 (HMGA2) expression levels. EGCG increases microRNA-let-7a levels and decreases HMGA2 gene expression. This is reported by Ching-Feng Cheng, Hui-Chen Ku, Yung-Hsi Kao, and co-workers in article number 2200336.

Effects of HMGA2 gene silencing on cell cycle and apoptosis in the metastatic renal carcinoma cell line ACHN.

ObjectiveTo explore the role of high mobility group AT-hook 2 (HMGA2) in the regulation of the cell cycle and apoptosis.MethodsThe renal carcinoma cell line ACHN was transiently transfected with small interfering RNA to knock down the expression of the HMGA2 gene. Cell cycle analysis was undertaken using flow cytometry. The mRNA and protein levels of HMGA2, E2F transcription factor 1 (E2F1), cyclin D1, cyclin dependent kinase 6 (CDK6), B-cell lymphoma-2 (Bcl-2), caspase-3 and caspase-9 were analysed using reverse transcription quantitative real-time polymerase chain reaction and Western blot analysis.ResultsThe mRNA and protein levels of HMGA2 were significantly higher in renal carcinoma cell lines compared with the human renal proximal tubular epithelial cell line HKC. After HMGA2 gene-specific silencing, more cells entered the G0/G1 phase, while fewer cells entered the G2/M phase; and the cells exhibited early and late apoptosis. HMGA2 gene-specific silencing significantly reduced the mRNA and protein levels of E2F1, cyclin D1, CDK6 and Bcl-2; and increased the mRNA and protein levels of caspase-3 and caspase-9.ConclusionThe HMGA2 gene may be involved in the tumorigenesis and development of renal cancer, thus inhibiting HMGA2 gene expression might provide a potential therapeutic target in the future.

High HMGA2 expression without gene rearrangement in meningiomas.

High mobility group AT-hook 2 (HMGA2) is a non-histone transcriptional regulator protein. Aberrant expression of the HMGA2 gene (HMGA2) and structural rearrangement at the chromosomal region 12q14 with HMGA2 involvement have been reported in several mesenchymal tumors. We analyzed truncated and full-length HMGA2 expression in 55 cases of meningioma, the most common brain tumor of mesenchymal origin. Fluorescence in situ hybridization and 3'-rapid amplification of cDNA ends were used to investigate the possibility of gene rearrangements. Moreover, the relationship between HMGA2 expression and clinicopathological features was assessed. Compared with normal brain tissues, 95% of the meningioma tissues exhibited increased HMGA2 expression. In 14 cases, the expression of truncated HMGA2 was more than two-fold higher than that of paired full-length HMGA2. Chromosomal translocation involving the chromosomal region 12q14 was undetectable. No significant correlation was found between the Ki-67 labeling index and HMGA2 expression and between the HMGA2 expression and the clinicopathological features. The majority of the meningioma cases displayed increased HMGA2 expression, which was not attributed to the chromosomal rearrangement at the corresponding region. Similar to that in the other mesenchymal tumors, increased HMGA2 expression was not associated with tumor cell proliferation in meningiomas.

Novel Variants in the HMGA2 Gene Are Associated With Withers Height in Debao Pony

The Debao pony is a well-known dwarf horse breed in China. High-mobility group AT-hook 2 (HMGA2) gene is regarded as one of the important candidate genes regulating body height in horses. The aim of this study was to study the association between mutations in HMGA2 gene and withers height in Debao ponies. The polymorphisms in all exons and partial introns of the HMGA2 gene were screened with sequencing across 180 Debao ponies. And the association between the DNA variants and withers height was analyzed. Seven genetic variants were identified in HMGA2 gene, including six novel variants. Among them, six mutations were located in two closed linked blocks. The three novel variants (In1-1, E5-1, and E5-2) in the 1st intron and the fifth exon and a known mutation (In1-2) had significant association with withers height in Debao ponies. These results suggest that the four variants have the potential to be used as genetic markers for dwarf horse breeding activities.

HMGA2 Gene rs8756 A>C Polymorphism Reduces Neuroblastoma Risk in Chinese Children: A Four-Center Case-Control Study.

BackgroundNeuroblastoma, mainly affecting children, is a lethal malignancy arising from the developing sympathetic nervous system. The genetic etiology of neuroblastoma remains mostly obscure. High mobility group AT-hook 2 (HMGA2), an oncogenic gene, is up-regulated in many tumors. Single nucleotide polymorphisms (SNPs) often modify cancer susceptibility. However, no studies are investigating the association between HMGA2 SNPs and neuroblastoma susceptibility.MethodsWe conducted a four-center case-control study to evaluate the association between three HMGA2 polymorphisms (rs6581658 A>G, rs8756 A>C and rs968697 T>C) and neuroblastoma susceptibility in a Chinese population with 505 cases and 1070 controls. Logistic regression was performed to evaluate the strength of the association.ResultsWe found that the rs8756 AC/CC genotypes were associated with a reduced neuroblastoma risk when compared to rs8756 AA genotype [Adjusted odds ratio (OR)=0.74, 95% confidence interval (CI)=0.56–0.99, P=0.039]. Carriers with 3 protective genotypes have lower neuroblastoma susceptibility than those without or with 0–2 protective genotypes. The stratified analysis revealed that the protective effects of rs8756 AC/CC genotypes were more predominant among children of age > 18 months, males, and subgroups with the tumor in the mediastinum. Furthermore, haplotype analysis uncovered that haplotype ACC significantly reduced neuroblastoma risk.ConclusionOur study indicated HMGA2 rs8756 A>C polymorphism is significantly associated with decreased neuroblastoma risk.

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

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. 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. 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. 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.

Effect of RNA interference of the expression of HMGA2 on the proliferation and invasion ability of ACHN renal cell carcinoma cells.

This aim of the present study was to observe the effect of high mobility group AT-hook 2 (HMGA2) on the proliferation and invasion ability of ACHN renal cell carcinoma (RCC) cells. Human ACHN cells, an RCC cell line, and HKC normal human renal tubular epithelial cells were cultured. HMGA2 small interfering (si)RNA, Mock-siRNA and their negative control group were designed and synthesized. Subsequently, the ACHN cells were transiently transfected using RNA interference technology. Finally, the mRNA and protein expression levels of HMGA2 were detected using reverse transcription-polymerase chain reaction and western blot analyses. The proliferation ability of the ACHN cells was determined using MTT, and ACHN cell invasion ability was detected using the Transwell method. The results showed that the mRNA and protein expression levels of HMGA2 in the ACHN cells were considerably higher, compared with those in the HKC cells (P<0.01). The RCC cells, in which the expression of HMGA2 was specifically silenced, was successfully constructed. The proliferation rate of cells in the HMGA2-siRNA group was significantly lower, compared with that of cells in the Mock-siRNA group and control group at 24, 48, 72 and 96 h post-transfection (P<0.05). The invasion ability of cells in the HMGA2-siRNA group was significantly lower, compared with that of cells in the Mock-siRNA group and control group (P<0.05) 48 h following transfection. Therefore, the HMGA2 gene may function as an oncogene in the occurrence and development of RCC, and provide specific targets for the targeted therapy of RCC. Further detailed investigations of the HMGA2 gene are important for future gene therapy of RCC.

The activity of the HDAC inhibitor HBI-8000 (Chidamide) combined with eribulin on 4T1 spontaneous metastasis development.

e14055 Background: In preclinical studies eribulin has shown significant effects on epithelial-mesenchymal transition (EMT) in human breast cancer cells in vitro and in vivo, inducing a switch from mesenchymal to epithelial states, decreasing migration and invasiveness of human breast cancer cells in vitro, as well as experimental metastases in vivo. HBI-8000 is a novel, orally bioavailable Class I selective HDAC inhibitor (HDACi). In addition to its demonstrated positive effects on antitumor immunity, it also exerts significant effects on EMT pathway components, enhancing CDH1 (e-cadherin) expression and inhibiting TGF-β induced metastasis. Methods: The syngeneic, orthotopic 4T1 model is thought to be a close representation of the clinical situation; similar to human mammary carcinoma, the major cause of morbidity and mortality is development of spontaneous metastases. 4T1-implanted mice treated with combinations of eribulin and HBI-8000 were monitored for primary tumor growth inhibition (TGI), survival, and metastatic lung foci. Tumor samples were analyzed by Q-PCR for expression of genes involved in EMT or in the metastatic process. Results: Eribulin alone had no effect on primary TGI. Eribulin combined with HBI-8000 resulted in significant (P &lt; 0.05) reductions in median tumor volume, tumor volume distribution (TMD) and survival (P &lt; 0.005). Single agent HBI-8000 had a similar effect on TGI, TMD (P &lt; 0.05) and survival (P &lt; 0.005). Whereas single agent HBI-8000 or eribulin failed to significantly reduce metastases, the eribulin-HBI-8000 combination produced significant (P &lt; 0.01) and synergistic inhibition of metastases, decreasing the number of lung foci approximately 10-fold. Gene expression analyzed by Q-PCR revealed correlations between metastasis blockade and increases in E-Cadherin, Occludin and Claudin1. There was a strong correlation with inhibition of HMGA2 (High Mobility Group AT-Hook 2) gene expression. Conclusions: Eribulin combined with HBI-8000 inhibited primary tumor growth and inhibited metastasis development and increased survival. This effect was correlated and consistent with changes in genes relevant to EMT, tumor plasticity and stemness.

RKIP suppresses the proliferation and metastasis of breast cancer cell lines through up-regulation of miR-185 targeting HMGA2

Raf-1 kinase inhibitor protein (RKIP) is a tumor and metastasis suppressor in cancer cells. MicroRNAs (miRNAs) have been suggested to play a vital role in tumor initiation and progression by negatively regulating oncogenes and tumor suppressors. Quite recently, studies have identified some miRNAs operating to promote or suppress tumor invasion or metastasis via regulating metastasis-related genes, providing potential therapeutic targets on anti-metastasis strategy. In this study, we found the expression of RKIP and miR-185 in breast cancer tissues was significantly lower than that of in normal breast tissues. Over-expression of RKIP up-regulated miR-185 expression, inhibited breast cancer cell growth and invasion, and inhibited miR-185 target gene High-mobility group AT-hook 2 (HMGA2). HMGA2 is encoded by HMGA2 gene, which encodes a protein that belongs to the non-histone chromosomal high-mobility group (HMG) protein family. Moreover, RKIP knockdown attenuated the inhibition of breast cancer cell invasion and the expression of HMGA2 by miR-185. Forced HMGA2 overexpression could partly restore the inhibitory effect of miR-185 on breast cancer cell growth and invasion. Our findings newly described RKIP/miR-185 to HMGA2 link and provided a potential mechanism for breast cancer cell growth and invasion. It may illustrate the potential therapeutic utility of signaling pathway signatures.

MiR-1297 promotes apoptosis and inhibits the proliferation and invasion of hepatocellular carcinoma cells by targeting HMGA2.

MicroRNAs (miRNAs) have recently emerged as important regulators of gene expression in various tissues. In particular, miRNAs have been identified as new therapeutic agents and biomarkers in cancer. The aim of the present study was to explore whether miR‑1297 has an anti‑cancer role in hepatocellular carcinoma cell lines and to explore its underlying mechanism. The proliferation, apoptosis and migration of hepatocellular carcinoma cells were evaluated by cell viability assay, TUNEL staining and a wound healing assay, respectively. Western blot analysis and reverse transcription polymerase chain reaction (RT‑PCR) were performed to determine the expression levels of proteins and mRNAs of high‑mobility group AT‑hook 2 (HMGA2) in hepatocellular carcinoma. The luciferase assay was employed to verify the inhibitory activity of miR‑1297 on the 3' untranslated region (3'UTR) of the HMGA2 gene. In the present study, overexpression of miR‑1297 significantly inhibited the proliferation of HepG2 and SMMC7721 cells. Forced expression of miR‑1297 also increased the apoptosis of HepG2 and SMMC7721. Furthermore, the migration of HepG2 and SMMC7721 was also clearly suppressed by miR‑1297 overexpression. All these effects can be abrogated by co‑transfection with miR‑1297 inhibitor‑AMO‑1297. The luciferase assay verified that miR‑1297 overexpression is able to inhibit the activity of luciferase reporter harboring the HMGA2 3'UTR, indicating HMGA2 as the target of miR‑1297. Although the HMGA2 level was not affected by miR‑1297, the HMGA2 protein was significantly inhibited by miR‑1297 overexpression. Collectively, miR‑1297 was revealed to regulate the proliferation, apoptosis and migration of hepatocellular carcinoma cells via acting on HMGA2. The finding provides a new target for the treatment of hepatocellular carcinoma.

Human HMGA2 protein overexpressed in mice induces precursor T-cell lymphoblastic leukemia.

T-cell acute lymphoblastic leukemia (T-ALL) is a neoplasia of thymocytes characterized by the rapid accumulation of the precursors of T lymphocytes. HMGA2 (high-mobility group AT-hook 2) gene expression is extremely low in normal adult tissues, but it is overexpressed in many tumors. To identify the biological function of HMGA2, we generated transgenic mice carrying the human HMGA2 gene under control of the VH promoter/Eμ enhancer. Approximately 90% of Eμ-HMGA2 transgenic mice became visibly sick between 4 and 8 months due to the onset and progression of a T-ALL-like disease. Characteristic features included severe alopecia (30% of mice); enlarged lymph nodes and spleen; and profound immunological abnormalities (altered cytokine levels, hypoimmunoglobulinemia) leading to reduced immune responsiveness. Immunophenotyping showed accumulation of CD5+CD4+, CD5+CD8+ or CD5+CD8+CD4+ T-cell populations in the spleens and bone marrow of sick animals. These findings show that HMGA2-driven leukemia in mice closely resembles spontaneous human T-ALL, indicating that HMGA2 transgenic mice should serve as an important model for investigating basic mechanisms and potential new therapies of relevance to human T-ALL.

5 DISRUPTION OF THE HIGH MOBILITY GROUP AT-HOOK 2 (HMGA2) GENE IN SWINE REDUCES POSTNATAL GROWTH

The high mobility group AT-hook 2 (HMGA2) protein has been shown to be a crucial gene for cell growth, proliferation, and apoptosis; HMGA2 is also a strong biological candidate for growth, because mutations in this gene alter body size in mice and humans. Compared with wild-type controls, adult mice lacking HMGA2 are 60% smaller, and adult heterozygous mutants are 20% smaller. In humans, HMGA2 has been associated with adult and childhood height without any other deleterious effect. Additionally, a microdeletion in the HMGA2 gene in a human patient resulted in short stature, with no dysmorphologies and normal puberty. In order to determine the effect of HMGA2 on fetal and adult growth in pigs, a transgenic pig line deficient in HMGA2 expression was generated by gene targeting in fetal fibroblasts (FF). Using a targeting vector carrying a reporter gene, and homology arms specific to HMGA2, heterozygous mutant cell lines were generated. The cell lines were then used to generate 6 heterozygous females by somatic cell nuclear transfer (SCNT). Bodyweights and lengths from snout to base of tail were measured every 2 weeks for a year for mutant (n = 6) and wild-type farm gilts (n = 6). Data were analysed by one-way ANOVA. As in mice, disruption of one allele of the HMGA2 gene resulted in 25% reduction in weight (P &lt; 0.0001) and 14% reduction in length (P &lt; 0.0001). Early in postnatal growth (2 months), weights of mutants were not different than wild-type. However, mutants were 20 to 35% lighter (P &lt; 0.05) during mid stages (6 months) and 25 to 30% (P &lt; 0.0001) in late stages (3 months). The same insertional mutation generated 8 heterozygous male clones by SCNT. In addition, 7 nontransgenic males from the same FF line were generated as SCNT controls. Bodyweights and lengths were measured every 2 weeks for 30 weeks for HMGA2 heterozygous mutants (n = 8), control SCNT (n = 7) and wild-type farm boars (n = 5). The weight curve of boars showed similar pattern as for mutant gilts. At 30-week postnatal stage, mutants were 17% (P &lt; 0.05) and 16% (P &lt; 0.05) lighter in weight compared with littermate and wild-type animals, respectively. We are presently developing homozygous HMGA2 mutant lines. Currently, 3 of 6 heterozygous gilts have been bred with heterozygous boars, with 1 confirmed pregnancy. The expectation is that the homozygous animals will, like mice, be 60% smaller than the wild-type animals. The approach described here will result not only in a valuable large-animal model of dwarfism, but also in a tool to reduce the size of existing transgenic and nontransgenic swine lines. This, in turn, will increase the receptivity of valuable transgenic lines by the biomedical community. Funding for this work was provided by NIH grant R21-OD010553 to JP.

Upregulation of the high mobility group AT-hook 2 gene in acute aortic dissection is potentially associated with endothelial-mesenchymal transition.

The high mobility group AT-hook 2 (HMGA2) gene is proposed to regulate the genes involved in the epithelial-mesenchymal transition (EMT). One form of EMT is endothelial-mesenchymal transition (EndMT). We analyzed the expression profile of the HMGA2 gene in different human aortic diseases. Aortic specimens were collected from 51 patients, including 19 with acute aortic dissection, 26 with aortic aneurysm, two with Marfan syndrome and four aortic valves. Quantitative real-time polymerase chain reaction was carried out for HMGA2 and immunohistochemical analyses were performed for HMGA2, SNAI1, Vimentin, CD34, MKI-67 and TGFB1. The expression of let-7d microRNA, which is assumed to play a role in the regulation of HMGA2, was also quantified. The level of HMGA2 gene expression was significantly higher in acute aortic dissection compared with all the other samples (193.1 vs. 8.1 fold normalized to calibrator, P<0.001). The immunohistochemical investigation showed that HMGA2, SNAI1, and Vimentin proteins were mainly detected in the endothelial cells of the vasa vasorum. The HMGA2 gene is upregulated in acute aortic dissection. This is the first report describing a link between HMGA2 and acute aortic dissection. The HMGA2, SNAI1 and Vimentin proteins were mainly detected in the endothelium of the vasa vasorum. It seems that HMGA2 overexpression in acute aortic dissection occurs in a let-7d-independent manner and is associated with EndMT of the vasa vasorum.

HMGA2 gene expression analysis performed on cytologic smears to distinguish benign from malignant thyroid nodules

Up to 80% of thyroid nodules with an indeterminate diagnosis on fine-needle aspiration (FNA) (eg, "suspicious for follicular neoplasm") prove to be benign at the time of surgical resection. Ancillary tests in current use are limited in their ability to improve the preoperative detection of malignant follicular thyroid nodules. Studies using paraffin-embedded tissue have indicated that high mobility group AT-hook 2 (HMGA2) overexpression is present in a high percentage of malignant thyroid neoplasms but not in benign thyroid neoplasms. In the current study, the ability of HMGA2 overexpression analysis to preoperatively distinguish benign from malignant thyroid nodules by reverse transcriptase-polymerase chain reaction (RT-PCR) on suspicious cytologic smears was evaluated. Patients who underwent thyroid FNA and subsequent thyroid resection from 2001 through 2007 were identified. A subset of these patients who had a cytologic diagnosis of "suspicious" underwent HMGA2 expression analysis. HMGA2 expression was detected on cells scraped from cytologic smears with 1-step, real-time quantitative RT-PCR. Of the 125 cases identified, RNA extraction and HMGA2 analysis were successful in 115 cases. With an HMGA2 overexpression change of 5.9-fold or greater compared with a thyroid tumor cell line as a positive cutoff, the test was found to have the following overall performance for detecting malignant nodules: sensitivity of 71%, specificity of 97%, positive predictive value of 94%, and negative predictive value of 84%. HMGA2 overexpression was found to have low sensitivity for detecting Hurthle cell carcinoma (33%). HMGA2 mRNA expression analysis can be performed on cytologic smears and demonstrates a high specificity and positive predictive value and relatively high sensitivity and negative predictive value for detecting malignancy in "suspicious" thyroid aspirate specimens.

Derepression of HMGA2 via Removal of ZBRK1/BRCA1/CtIP Complex Enhances Mammary Tumorigenesis

The high mobility group AT-hook 2 (HMGA2), a DNA architectural protein, is highly regulated during development and plays an important role in tumorigenesis. Indeed, HMGA2 was overexpressed in many different kinds of tumors. However, the mechanisms regulating HMGA2 expression remain elusive. Using microarray analysis, we found that HMGA2, along with a dozen of other genes, was co-repressed by ZBRK1, BRCA1, and CtIP. BRCA1 exerts its transcriptional repression activity through interaction with the transcriptional repressor ZBRK1 in the central domain, and with CtIP in the C-terminal BRCT domain. Here, we show that ZBRK1, BRCA1, and CtIP form a repression complex that coordinately regulates HMGA2 expression via a ZBRK1 recognition site in the HMGA2 promoter. Depletion of any of the proteins in this complex via adenoviral RNA interference in MCF10A mammary epithelial cells activates HMGA2 expression, resulting in increased colony formation in soft agar. Similarly, depletion of ZBRK1, or ectopic overexpression of HMGA2, in MCF10A cells induces abnormal acinar size with increased cell number and inhibits normal acinar formation. Consistently, many BRCA1-deficient mouse breast tumors express higher levels of HMGA2 than BRCA1-proficient tumors. These results suggest that activation of HMGA2 gene expression through derepression of the ZBRK1/BRCA1/CtIP complex is a significant step in accelerating breast tumorigenesis.

Upregulation of the high mobility group AT-hook 2 gene in acute aortic dissection

Introduction: The high mobility group AT-hook 2 (HMGA2) gene has recently been shown to be a transcriptional organizer of transforming growth factor (TGF-ß) signaling. It is proposed that HMGA2 acts in a gene-specific manner to regulate factors involved in epithelial-mesenchymal-transition (EMT), known to be expressed abundantly during embryogenesis. We analyzed the expression profile of the HMGA2 gene in different human aortic diseases.