High Mobility Group A1 Expression Research Articles

Expression of Matrix Metalloproteinase-9, Pituitary Tumor Transforming Gene, High Mobility Group A 2, and Ki-67 in Adrenocorticotropic Hormone-Secreting Pituitary Tumors and Their Association with Tumor Recurrence.

Matrix metalloproteinase-9 (MMP-9), pituitary tumor transforming gene (PTTG), and high mobility group A 2 (HMGA2) play important roles in the tumorigenesis of adrenocorticotrophic hormone (ACTH)-secreting pituitary tumors, but their associations with tumor recurrence after transsphenoidal adenomectomy remain unclear. The aim of the study was to investigate the immunohistochemical expression profiles of MMP-9, PTTG, HMGA2, and Ki-67 in recurrent and nonrecurrent ACTH-secreting pituitary tumors and to identify their associations with tumor behavior and recurrence status. A retrospective study was performed including 55 patients with sporadic Cushing's disease with long-term remission after transsphenoidal adenomectomy. Fifty-five ACTH-secreting pituitary tumor specimens and 2 normal pituitary glands were collected. After an intensive follow-up (33-59 months, mean 41.8 months), patients were divided into 2 groups based on their recurrence status: thenonrecurrent group (n= 28) and the recurrent group (n= 27). The expression of MMP-9, PTTG, HMGA2, and Ki-67 in each sample was examined and quantified by immunohistochemistry. The association between MMP-9, PTTG, HMGA2, and Ki-67 expression and clinicopathologic characteristics and tumor recurrence were evaluated. There was a significantly increased expression of MMP-9 in the recurrent group compared with the nonrecurrent group (P= 0.022), and this was strongly associated with the recurrence-free interval (P= 0.007, correlation coefficient.= -0.354). PTTG, HMGA2, and Ki-67 expression were not significantly different between the recurrent group and the nonrecurrent group. No expression of MMP-9, PTTG, HMGA2, or Ki-67 was detected in the 2normal pituitary glands. ACTH-secreting pituitary tumors with greater levels of MMP-9 were associated with a greater recurrence rate and a shorter recurrence-free interval. MMP-9 could be a valuable tool for predicting recurrence of ACTH-secreting pituitary tumors.

HMGA1 Overexpression is Associated With the Malignant Status and Progression of Breast Cancer.

Breast cancer is the most common malignant tumor among women, and the incidence and mortality of breast cancer has rapidly increased in recent years. Studies have indicated that high mobility group A1 (HMGA1), an important member of the HMGA family, plays a role in the pathogenesis and progression of malignant tumors, including breast cancer. This study aims to evaluate the effect of HMGA1 in breast cancer. Interestingly, we found that HMGA1 expression was significantly higher in breast cancer tissues than in adenoma tissues and closely correlated with the clinical stage and histological grade in breast cancer patients. Further study showed that HMGA1 knockdown inhibited the proliferation and migration of breast cancer cells. Thus, the results demonstrated that HMGA1 could act as an independent prognostic indicator in breast cancer. HMGA1 expression was closely correlated with the clinical stage, histological grade, and tumor size in breast cancer patients and breast cancer progression in transgenic MMTV-PyMT mice. Anat Rec, 301:1061-1067, 2018. © 2018 Wiley Periodicals, Inc.

HMGA1 and MMP-11 Are Overexpressed in Human Non-melanoma Skin Cancer.

The High-Mobility Group A1 (HMGA1) protein has been implicated in human malignancies, playing an important role in cancer proliferation, angiogenesis and metastasis. Increased HMGA1 expression has been found in skin mouse tumors, whereas Hmga1-null mice were protected against skin carcinogenesis. Here, we examined the expression of HMGA1 in human skin tumors, squamous cell carcinoma and basal cell carcinoma. Tumor and normal skin tissues from 15 affected patients were surgically excised, and mRNA and protein extraction was performed. mRNA and protein content for both HMGA1 and MMP-11, a proteinase enzyme that plays a role in tumor development and progression, was measured by real-time PCR and western blotting, respectively. Data were analyzed by the SPSS software. HMGA1 mRNA and protein expression patterns were higher in neoplastic skin lesions, compared to normal skin (p<0.001). Similar results were observed for MMP-11. Our data confirm previous observations in mice studies, and suggest that HMGA1 and MMP-11 may play a key role in the proliferation and progression of skin tumors in humans.

Increased high mobility group A 2 expression promotes transition of cervical intraepithelial neoplasm into cervical cancer.

Integration of the high risk human papillomavirus (HR-HPV) genome into host chromatin is an important step in cervical carcinogenesis. We identified HR-HPV integration sites within the human genome through detection of integrated papillomavirus sequences-PCR and assessed the role of high mobility group A 2 (HMGA2) in cervical carcinogenesis in clinical samples and cell lines. HPV integration sites were analyzed in 40 cervical cancer samples, while copy number variation and protein expression were assessed in 19 normal cervixes, 49 cervical intraepithelial neoplasia (CIN), and 52 cervical cancer samples. Overall, 25 HR-HPV integrating loci were detected in 24 cervical samples; HMGA2 was the only recurring integration site. Both HPV copy number and HMGA2 protein expression were higher in cervical cancer than CIN samples. Area under the curve (AUC) values for HMGA2 expression and HPV copy number were 0.910 (95% CI: 0.844–0.976) and 0.848 (95% CI: 0.772–0.923), respectively. Expression of Bcl-2 and Caspase 3 can indicate the cell proliferation and apoptosis. Transfection of HMGA2 siRNA decreased HMGA2 mRNA and protein expression, Bcl-2 expression, inhibited cell proliferation, and increased Caspase 3 expression and apoptosis in SiHa, CaSki and S12 cervical cancer cells. HMGA2 overexpression had the opposite effects. These results suggest that elevated HMGA2 expression is associated with transformation of CIN into cervical cancer and that HMGA2 might be a useful biomarker for assessing the risk of cervical lesion progression.

Investigation of silencing high-mobility group A1 on self-renewal of colon cancer stem cells

Objective To investigate the expression and role of high-mobility group A1 (HMGA1) in maintaining of colon tumour stem cell (CTSC). Methods Real-time reverse transcriptase-polymerase chain reaction (RT-qPCR) and Western blotting were applied to detect the expression of HMGA1 in CTSCs, regular colon cancer cells (HCT116 and HT29) and normal colonic mucosa (NM). Synthetic small interfering RNAs (siRNAs) were used to suppress the intrinsic HMGA1 expression. CTSC self-renewal was assessed by methyl thiazol tetrazolium (MTT) proliferation assay and sphere-forming efficiency. Results HMGA1 mRNA relative expression were 1.00±0.09, 1.56±0.13 and 1.62±0.10 for NM, HCT116 and HT29 respectively with statistical difference (t=5.949, P=0.005; t=8.124, P=0.001); HMGA1 mRNA expression was 2.37±0.15 which was statistical higher than NM group (t=12.330, P=0.001); The cell proliferation ability was significant decreased by inhibiting HMGA1 (3.60±0.14 vs. 2.71±0.30, t=4.649, P=0.010); The number and diameter of HMGA1 silenced CTSC cell clones were 55 710±11 007 (t=5.957, P=0.004) and (0.50±0.04) mm (t=3.499, P=0.025)decreased significantly with statistically significant difference. Conclusion HMGA1 interfering could significantly inhibit cell proliferation and sphere formation, which suggest its critical role involved in self-renewal of CTSCs. Key words: High-mobility group A1; Colon tumour stem cell; RNA interference

Extranuclear Translocation of High-Mobility Group A1 Reduces the Invasion of Extravillous Trophoblasts Involved in the Pathogenesis of Preeclampsia: New Aspect of High-Mobility Group A1

High-mobility group A1 (HMGA1) protein is known to express in trophoblast; however, the role of migration has not been reported to date. In this study, we investigated the role of HMGA1 on the pathogenesis of preeclampsia using immortalized human trophoblast cell (HTR-8/SVneo). We investigated HMGA1 expression in cytotrophoblasts derived from our preeclampsia model mouse, the CD40L mouse, using immunofluorescence. Wound healing and transwell migration assays were also performed using HTR-8/SVneo (extravillous trophoblast) cells transfected with DNA or siRNA of HMGA1. The effect of extranuclear translocation of HMGA1 on the migration of extravillous trophoblastic cells was evaluated using deoxycholic acid (DCA). HMGA1 was expressed exclusively in the nuclei of trophoblasts derived from control mice; cytoplasmic expression was observed only in CD40L mice with preeclampsia. Furthermore, overexpression of HMGA1 in the nuclei of HTR-8/SVneo cells stimulated cell proliferation and migration. Translocation of nuclear HMGA1 to cytoplasm treated with DCA reduced cell migration. Collectively, these findings demonstrate that proper subcellular localization of HMGA1 is important for its function in trophoblast cells, and suggest that aberrant cytoplasmic expression of HMGA1 contributes to the pathogenesis of preeclampsia through impairment of trophoblast migration.

HMGA1 is a novel transcriptional regulator of the FoxO1 gene

PurposeThe forkhead transcription factor (FoxO1) is a master transcriptional regulator of fundamental cellular processes ranging from cell proliferation and differentiation to inflammation and metabolism. However, despite its relevance, the mechanism(s) underlying FoxO1 gene regulation are largely unknown. We have previously shown that the chromatin factor high-mobility group A1 (HMGA1) plays a key role in the transcriptional regulation of glucose-responsive genes, including some that are involved in FoxO1-mediated glucose metabolism. Here we investigated the impact of HMGA1 on FoxO1 gene expression.MethodsFoxO1 protein and gene expression studies were performed by Western blot analysis combined with qRT-PCR of material from human cultured cells and EBV-transformed lymphoblasts, and from primary cultured hepatocytes from wild-type and Hmga1–/– mice. Reporter gene assays and chromatin immunoprecipitation for binding of HMGA1 to the endogenous FoxoO1 locus were performed in cells overexpressing HMGA1 and in cells pretreated with siRNA targeting HMGA1.ResultsHMGA1 increased FoxO1 mRNA and protein expression in vitro, in cultured HepG2 and HEK-293 cells by binding FoxO1 gene promoter, thereby activating FoxO1 gene transcription. Forced expression of HMGA1 in primary cultured hepatocytes from Hmga1–/– mice and in EBV-transformed lymphoblasts from subjects with reduced expression of endogenous HMGA1 increased FoxO1 mRNA and protein levels.ConclusionThese findings may contribute to the understanding of FoxO1 gene regulation and its role in metabolism.

Roles of microRNA let-7b in papillary thyroid carcinoma by regulating HMGA2.

The incidence of thyroid cancer has increased significantly in the last decade, and the most frequent type of this cancer is papillary thyroid carcinoma. MicroRNAs have been demonstrated to be abnormally expressed in tumors and associated with the development of the tumors. Our aim was to analyze the role and molecular mechanisms of tumor suppressor let-7b in the papillary thyroid carcinoma. Expression of let-7b and high-mobility group A2 in papillary thyroid carcinoma tissues and cell lines was assessed using quantitative reverse transcription polymerase chain reaction and western blot analysis. To explore the role of let-7b or high-mobility group A2 in the BCPAP and TPC-1 cells, 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide and Transwell methods were used. Let-7b expression was significantly downregulated while expression of high-mobility group A2 was upregulated dramatically in papillary thyroid carcinoma tissues and cells compared with that in normal thyroid tissues and cells. In addition, overexpression of let-7b or knockdown of high-mobility group A2 inhibited cell migration and invasion compared with that of control. Besides, high-mobility group A2 was negatively regulated by let-7b in BCPAP cells. Moreover, high-mobility group A2 reintroduction reversed the anti-proliferation, anti-migration, and anti-invasion roles of let-7b. Let-7b might function as a tumor suppressor in papillary thyroid carcinoma by suppressing the expression of high-mobility group A2, and therefore might provide a promising therapeutic target for patients with papillary thyroid carcinoma.

Role of high mobility group A1 and body mass index in the prognosis of patients with breast cancer.

The high mobility group A1 (HMGA1) protein is associated with poor prognosis in patients with a wide range of cancers. However, the affect of HMGA1 on the risk of mortality from breast cancer (BC) has not been fully characterized. In the present retrospective multiple center study, the HMGA1 expression level was determined by performing immunohistochemistry on surgical tissue samples of 273 BC specimens from the Second Affiliated Hospital of Zhejiang University (Zhejiang, China) and 310 BCs from the National Engineering Center for Biochip (Shanghai, China). Kaplan-Meier analysis and Cox proportional hazard model were employed to analyze the survivability. HMGA1 expression was significantly associated with tumor histological degree and body mass index (BMI). However, HMGA1 expression showed no prognostic value in patients with BC. Combined evaluation of HMGA1 expression and high BMI (≥24 kg/m2) predicted worse overall survival of BC. Therefore, HMGA1 and BMI were considered to serve synergistic roles in the development and progression of BC, and combined evaluation of HMGA1 expression and high BMI may be an effective marker in predicting poor prognosis of BC patients.

The long noncoding RNA HULC promotes liver cancer by increasing the expression of the HMGA2 oncogene via sequestration of the microRNA-186

The long noncoding RNA highly up-regulated in liver cancer (HULC) is aberrantly elevated in hepatocellular carcinoma (HCC), and this up-regulation is crucial for HCC pathogenesis. However, the underlying mechanism in HULC up-regulation is poorly understood. We hypothesized that HULC might modulate the oncogene high mobility group A2 (HMGA2) to promote hepatocarcinogenesis. Quantitative real-time PCR analysis showed that the expression levels of HULC were positively correlated with those of HMGA2 in clinical HCC tissues. Interestingly, we also observed that HULC could up-regulate HMGA2 in HCC cells. Mechanistically, we found that the microRNA-186 inhibited HMGA2 expression by targeting the 3'-untranslated region (3'-UTR) of HMGA2 mRNA. Strikingly, HULC acted as a competing noncoding RNA to sequester miR-186 and thereby relieved miR-186-mediated HMGA2 repression. Functionally, HMGA2 knockdown decreased the HULC-enhanced growth of HCC cells both in vitro and in vivo We conclude that the long noncoding RNA HULC increases HMGA2 expression by sequestering miR-186 post-transcriptionally and thereby promotes liver cancer growth, providing new insights into the mechanism by which HULC enhances hepatocarcinogenesis.

HMGA2 upregulation mediates Cd-induced migration and invasion in A549 cells and in lung tissues of mice

Cadmium (Cd) is a toxic metal widely found in a number of environmental matrices, and it induces serious adverse effects in various organs and tissues. In this study, the role of high mobility group A2 (HMGA2) in promoting migration and invasion in Cd-treated A549 cells and lung tissues of mice was investigated. Our findings showed that exposure to Cd (2 μM) for 48 h or subcutaneous injection of Cd daily for 6 weeks significantly enhanced the expression of matrix metalloproteinase-9 (MMP-9), matrix metalloproteinase-2 (MMP-2), phosphorylated focal adhesion kinase (p-FAK), and HMGA2 in A549 cells or lung tissues of mice. In A549 cells, HMGA2 knockdown significantly decreased expression of MMP-9, MMP-2 and p-FAK and inhibited the migration and invasion compared to that of only Cd-treated cultures. Overexpression of HMGA2 in HEK-293T cells increased expression of MMP-9, MMP-2 and p-FAK and enhanced the migration and invasion compared with the empty vector transfection group. In conclusion, upregulation of HMGA2 plays an important role in Cd-enhanced migration and invasion. Suppressing HMGA2 expression might have potential values in prevention of Cd-resulted toxicities.

The Fragment HMGA2-sh-3p20 from HMGA2 mRNA 3\u2032UTR Promotes the Growth of Hepatoma Cells by Upregulating HMGA2

High mobility group A2 (HMGA2) plays a crucial role in the development of cancer. However, the mechanism by which HMGA2 promotes the growth of hepatocellular carcinoma (HCC) remains unclear. Here, we explore the hypothesis that HMGA2 may enhance the growth of hepatoma cells through a fragment based on the secondary structure of HMGA2 mRNA 3′-untranslated region (3′UTR). Bioinformatics analysis showed that HMGA2 mRNA displayed a hairpin structure within its 3′UTR, termed HMGA2-sh. Mechanistically, RNA immunoprecipitation assays showed that the microprocessor Drosha or DGCR8 interacted with HMGA2 mRNA in hepatoma cells. Then, Dicer contributes to the generation of the fragment HMGA2-sh-3p20 from the HMGA2-sh. HMGA2-sh-3p20 was screened by PCR analysis. Interestingly, HMGA2-sh-3p20 increased the expression of HMGA2 through antagonizing the tristetraprolin (TTP)-mediated degradation of HMGA2. HMGA2-sh-3p20 inhibited the expression of PTEN by targeting the 3′UTR of PTEN mRNA. In addition, the overexpression of PTEN could downregulate HMGA2 expression. Significantly, we documented the ability of HMGA2-sh-3p20 to promote the growth of hepatoma cells in vitro and in vivo. Thus, we conclude that the fragment HMGA2-sh-3p20 from HMGA2 mRNA 3′UTR promotes the growth of hepatoma cells by upregulating HMGA2. Our finding provides new insights into the mechanism by which HMGA2 enhances hepatocarcinogenesis.

High mobility group A1 enhances tumorigenicity of human cholangiocarcinoma and confers resistance to therapy.

High mobility group A1 (HMGA1) protein has been described to play an important role in numerous types of human carcinoma. By the modulation of several target genes HMGA1 promotes proliferation and epithelial-mesenchymal transition of tumor cells. However, its role in cholangiocarcinoma (CCA) has not been addressed yet. Therefore, we determined HMGA1 mRNA expression in CCA samples in a transcriptome array (n = 104) and a smaller cohort (n = 13) by qRT-PCR. Protein expression was evaluated by immunohistochemistry in a tissue microarray (n = 67). In addition, we analyzed changes in cell proliferation, colony formation, response to gemcitabine treatment, and target gene expression after modulation of HMGA1 expression in CCA cell lines. mRNA levels of HMGA1 were found to be upregulated in 15-62% depending on the cohort analyzed. Immunohistochemistry showed HMGA1 overexpression in 51% of CCA specimens. Integration with clinico-pathological data revealed that high HMGA1 expression was associated with reduced time to recurrence and a positive lymph node status in extrahepatic cholangiocellular carcinoma. In vitro experiments showed that overexpression of HMGA1 in CCA cell lines promoted cell proliferation, whereas its suppression reduced growth rate. HMGA1 further promoted colony formation in an anchorage independent growth and conferred resistance to gemcitabine treatment. Finally, HMGA1 modulated the expression of two genes involved in CCA carcinogenesis, iNOS and ERBB2. In conclusion, our findings indicate that HMGA1 expression is increased in a substantial number of CCA specimens. HMGA1 further promotes CCA tumorigenicity and confers resistance to chemotherapy.

Expression and clinical significance of HMGA2 in renal carcinoma

Objective: To detect the high mobility group A2 (HMGA2) expression in renal carcinoma, and to explore the relationship with clinicopathological features and its significance for prognosis. Methods: 50 renal carcinoma specimens, 50 corresponding adjacent normal kidney tissue samples, and 40 benign renal tumor specimens were used in this study. The expressions of HMGA2 mRNA and protein were detected by RT-PCR, Western blot and immunohistochemical assays, and its relationship with clinicopathological features and prognosis in the renal carcinoma patients was analyzed. Results: The RT-PCR results showed that the relative expression levels of HMGA2 mRNA in the renal carcinoma, benign renal tumor tissues, and adjacent normal renal tissues were 0.84±0.23, 0.19± 0.06 and 0.08±0.04, respectively, and the expression in renal carcinoma tissue was significantly higher than those of the other 2 groups (P<0.01). The Western blot results showed that the relative expression levels of HMGA2 protein in the renal carcinoma, benign renal tumor tissues, and adjacent normal renal tissues were 0.91±0.24, 0.12±0.04 and 0.03±0.01, respectively, and the expression in renal carcinoma tissue was significantly higher than those of the other 2 groups (P<0.01). Immunohistochemical results showed that the expression of HMGA2 protein exhibited brown and tan granular, which mainly distributed in the cell nuclei. Among the 50 cases of renal carcinoma, 34 cases exhibited positive expression, with a positive rate of 68.0%. Among the 40 cases of benign tumor tissues, 3 cases had positive expression, with a positive rate of 7.5%, while among the 50 cases of adjacent normal renal tissues, there was only 1 case exhibiting positive expression of HMGA2 protein, with a positive rate of 2.0%. The protein expression of HMGA2 was significantly higher in the renal carcinoma than in the benign tumors and normal renal tissues (P=0.004). There was no statistically significant difference in the association of HMGA2 protein expressions with age, sex, tumor size and histological type (P>0.05), while significant difference did exist in the association with different statuses of TNM staging and lymph node metastasis (P<0.05). The median time to progression (TTP) in 34 HMGA2 protein-positive patients was (22.36±1.48) months and that of 16 HMGA2 protein-negative patients was (34.55±1.87) months (P<0.05). Conclusions: HMGA2 plays an important role in the tumorigenesis and development of renal carcinoma, and may be used as an important predictor for estimating the prognosis of renal carcinoma. HMGA2 might become a new diagnostic and prognostic marker for renal carcinoma.

Expression of miR‑26a exhibits a negative correlation with HMGA1 and regulates cancer progression by targeting HMGA1 in lung adenocarcinoma cells.

Lung cancer is the most common cause of cancer-associated mortality worldwide, and the number of cases is increasing annually. Several studies have shown that microRNAs (miRNAs) control proliferation, differentiation, and apoptosis in various cell types, and increasing evidence indicates the presence of aberrant miRNA expression profiles and unique miRNA signaling pathways in several types of cancer. The present study aimed to identify miRNAs, which correlated specifically with the progression of lung cancer through the analysis of 57,100 transcripts and 1,341 small RNA expression profiles in 26 lung adenocarcinoma cell lines using next-generation sequencing. The most marked negative correlation was found between the expression of hsa-miR-26a-1 and messenger RNA (mRNA), and a list of mRNAs, which exhibited negative correlation with hsa-miR-26a-1 were investigated. The most marked negative correlation was observed between the expression levels of hsa-miR-26a-1 and high mobility group A1 (HMGA1). Using a lung adenocarcinoma cell line, the present study analyzed the effect of the overexpression of miR-26a on the expression of HMGA1 and found that miR-26a repressed the expression of HMGA1 by reducing the mRNA levels of HMGA1. Furthermore, it was demonstrated that the overexpression of miR-26a in a lung adenocarcinoma cell line repressed cell migration, invasion and growth by targeting HMGA1. Taken together, the present study showed a significant negative correlation between the expression of miR-26a and HMGA1 in 26 lung adenocarcinoma cell lines, and provided evidence that the suppression of miR-26a supports the progression of cancer by stimulating the expression of HMGA1.

Abstract 1704: High mobility group A1 chromatin remodeling protein expands the intestinal stem cell compartment and Paneth cell niche through Wnt/β-catenin signaling and Sox9

Abstract The High Mobility Group A1 (HMGA1) gene is overexpressed in most poorly differentiated cancers and high levels portend adverse clinical outcomes, although the molecular mechanisms through which it functions are poorly understood. HMGA1 encodes the HMGA1a and HMGA1b chromatin remodeling proteins, which modulate gene expression by bending chromatin and orchestrating the assembly of transcription factor complexes to DNA. HMGA1 is highly expressed during embryogenesis, but silenced in adult, differentiated tissues. Postnatally, HMGA1 expression is maintained in adult stem cells, such as intestinal stem cells (ISCs); however, its role in this setting has been unknown. Here, we report that Hmga1 overexpression in ISCs of transgenic mice drives expansion in the ISC compartment leading to hyperproliferation, aberrant crypt formation, and polyposis. Surprisingly, Hmga1 transgenic mice also exhibit marked expansion in terminally differentiated Paneth cells, which comprise an epithelial cell niche for ISCs. To dissect the mechanisms mediating these phenotypes, we generated three-dimensional (3D) intestinal organoids with varied expression of Hmga1. Strikingly, silencing Hmga1 in wildtype crypt cells disrupts their ability to organize into functional 3D organoids with bud formation, while crypt cells expressing ectopic Hmga1 exhibit enhanced organoid formation with increased ISC number, proliferation, and bud development. Because Wnt/β-catenin signaling is central to ISC function, we determined whether Hmga1 modulates this pathway. β-catenin protein is increased in the crypts of the Hmga1 transgenic mice and organoids. Hmga1 amplifies Wnt/β-catenin signaling by inducing both genes that encode Wnt cell surface receptors and target genes downstream of Wnt/β-catenin. Hmga1 also directly up-regulates Sox9, which is required for terminal differentiation to Paneth cells. This is the first example of Hmga1 fostering terminal differentiation to establish a stem cell niche. In human intestinal epithelium, HMGA1 and SOX9 are highly correlated (P = 0.008), and both become up-regulated in carcinogenesis. These results reveal a novel role for Hmga1 in intestinal homeostasis by maintaining both the stem cell pool and epithelial niche compartment and suggest that deregulated Hmga1 perturbs this equilibrium during intestinal carcinogenesis. Citation Format: Lingling Xian, Tait Huso, Amy Belton, David Huso, Linda M. S. Resar. High mobility group A1 chromatin remodeling protein expands the intestinal stem cell compartment and Paneth cell niche through Wnt/β-catenin signaling and Sox9. [abstract]. In: Proceedings of the 107th Annual Meeting of the American Association for Cancer Research; 2016 Apr 16-20; New Orleans, LA. Philadelphia (PA): AACR; Cancer Res 2016;76(14 Suppl):Abstract nr 1704.

The High Mobility Group A1 (HMGA1) Transcriptome in Cancer and Development.

Chromatin structure is the single most important feature that distinguishes a cancer cell from a normal cell histologically. Chromatin remodeling proteins regulate chromatin structure and high mobility group A (HMGA1) proteins are among the most abundant, nonhistone chromatin remodeling proteins found in cancer cells. These proteins include HMGA1a/HMGA1b isoforms, which result from alternatively spliced mRNA. The HMGA1 gene is overexpressed in cancer and high levels portend a poor prognosis in diverse tumors. HMGA1 is also highly expressed during embryogenesis and postnatally in adult stem cells. Overexpression of HMGA1 drives neoplastic transformation in cultured cells, while inhibiting HMGA1 blocks oncogenic and cancer stem cell properties. Hmga1 transgenic mice succumb to aggressive tumors, demonstrating that dysregulated expression of HMGA1 causes cancer in vivo. HMGA1 is also required for reprogramming somatic cells into induced pluripotent stem cells. HMGA1 proteins function as ancillary transcription factors that bend chromatin and recruit other transcription factors to DNA. They induce oncogenic transformation by activating or repressing specific genes involved in this process and an HMGA1 "transcriptome" is emerging. Although prior studies reveal potent oncogenic properties of HMGA1, we are only beginning to understand the molecular mechanisms through which HMGA1 functions. In this review, we summarize the list of putative downstream transcriptional targets regulated by HMGA1. We also briefly discuss studies linking HMGA1 to Alzheimer's disease and type-2 diabetes. Further elucidation of HMGA1 function should lead to novel therapeutic strategies for cancer and possibly for other diseases associated with aberrant HMGA1 expression.

ROS-dependent HMGA2 upregulation mediates Cd-induced proliferation in MRC-5 cells

Cadmium (Cd) is a heavy metal widely found in a number of environmental matrices, and the exposure to Cd is increasing nowadays. In this study, the role of high mobility group A2 (HMGA2) in Cd-induced proliferation was investigated in MRC-5 cells. Exposure to Cd (2μM) for 48h significantly enhanced the growth of MRC-5 cells, increased reactive oxygen species (ROS) production, and induced both mRNA and protein expression of HMGA2. Evidence for Cd-induced reduction of the number of G0/G1 phase cells and an increase in the number of cells in S phase and G2/M phase was sought by flow cytometric analysis. Western blot analysis showed that cyclin D1, cyclin B1, and cyclin E were upregulated in Cd-treated cells. Further study revealed that N-acetyl cysteine (NAC) markedly prevented Cd-induced proliferation of MRC-5 cells, ROS generation, and the increasing protein level of HMGA2. Silencing of HMGA2 gene by siRNA blocked Cd-induced cyclin D1, cyclin B1, and cyclin E expression and reduction of the number of G0/G1 phase cells. Combining, our data showed that Cd-induced ROS formation provoked HMGA2 upregulation, caused cell cycle changes, and led to cell proliferation. This suggests that HMGA2 might be an important biomarker in Cd-induced cell proliferation.

The High Mobility Group A1 (HMGA1) gene is highly overexpressed in human uterine serous carcinomas and carcinosarcomas and drives Matrix Metalloproteinase-2 (MMP-2) in a subset of tumors

ObjectivesAlthough uterine cancer is the fourth most common cause for cancer death in women worldwide, the molecular underpinnings of tumor progression remain poorly understood. The High Mobility Group A1 (HMGA1) gene is overexpressed in aggressive cancers and high levels portend adverse outcomes in diverse tumors. We previously reported that Hmga1a transgenic mice develop uterine tumors with complete penetrance. Because HMGA1 drives tumor progression by inducing Matrix Metalloproteinase (MMP) and other genes involved in invasion, we explored the HMGA1-MMP-2 pathway in uterine cancer. MethodsTo investigate MMP-2 in uterine tumors driven by HMGA1, we used a genetic approach with mouse models. Next, we assessed HMGA1 and MMP-2 expression in primary human uterine tumors, including low-grade carcinomas (endometrial endometrioid) and more aggressive tumors (endometrial serous carcinomas, uterine carcinosarcomas/malignant mesodermal mixed tumors). ResultsHere, we report for the first time that uterine tumor growth is impaired in Hmga1a transgenic mice crossed on to an Mmp-2 deficient background. In human tumors, we discovered that HMGA1 is highest in aggressive carcinosarcomas and serous carcinomas, with lower levels in the more indolent endometrioid carcinomas. Moreover, HMGA1 and MMP-2 were positively correlated, but only in a subset of carcinosarcomas. HMGA1 also occupies the MMP-2 promoter in human carcinosarcoma cells. ConclusionsTogether, our studies define a novel HMGA1-MMP-2 pathway involved in a subset of human carcinosarcomas and tumor progression in murine models. Our work also suggests that targeting HMGA1 could be effective adjuvant therapy for more aggressive uterine cancers and provides compelling data for further preclinical studies.

Triplex forming oligonucleotides targeted to hmga1 selectively inhibit its expression and induce apoptosis in human cervical cancer

High-mobility group A1 (HMGA1) is a non-histone chromosomal protein, which is known as ‘architectural’ transcription factor that facilitates the assembly of ‘enhanceosome.’ Because of its elevated expression in a number of human malignancies, with barely minimal levels in healthy adults, HMGA1 is considered as potential ‘tumor marker.’ Therefore, we looked at the inhibition of hmga1 using anti-gene strategy, as an attractive therapeutic approach. This was achieved by two triplex forming oligonucleotides (TFOs), TFO1 and TFO2 targeted to the promoter of hmga1 at positions, −284–−304 and −2800–−2826, respectively. The stability of two DNA triplexes was characterized using a variety of biophysical and thermodynamics techniques and was confirmed by gel retardation assay using γ-32P [ATP]. The efficacy of TFOs on HMGA1 expression was evaluated in HeLa cells using MTT assay, Flow cytometry, Western blot, and RT-PCR. Results revealed that DNA Triplex1 formed by TFO1 is more stable and stronger than the corresponding Triplex2. Although both TFOs downregulated hmga1 expression at mRNA and protein levels and caused apoptotic cell death in HeLa cell line, TFO1 demonstrated a greater effect at low concentration which corroborates well with the stability data. Thus, TFO-mediated inhibition of hmga1 expression can be a promising strategy for the development of novel anti-cancer therapeutics.