An increased high-mobility group A2 expression level is associated with malignant phenotype in pancreatic exocrine tissue

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.

High glucose promotes atherosclerosis by regulating miRNA let7d-5p level

BACKGROUND

MiRNA let7d-5p has been recently reported to be abnormally expressed in diabetes-associated atherosclerosis (AS). However, it still remains unknown how let7d-5p contributes to the process of atherosclerosis.

METHODS

Twenty fresh tissues and a total of 28 wax block specimens from carotid endarterectomy procedures were obtained from the Luoyang Central Hospital affiliated to Zhengzhou University. The expression of let7d-5p was assessed using quantitative RT-PCR (qRT-PCR). A series of in vitro experiments was used to determine the roles of let7d-5p knockdown and overexpression in vascular smooth muscle cells (VSMCs).

RESULTS

We discovered that the carotid plaques from diabetic patients had lower expression levels of miR let7d-5p. In VSMCs, the expression of miRNA let7d-5p was significantly lower in high glucose conditions compared with low glucose situations. The proliferation and migration of VSMCs were also inhibited by the overexpression of let7d-5p, whereas the opposite was true when let7d-5p was inhibited, according to gain and loss of function studies. Mechanically, let7d-5p might activate the GSK3β/β-catenin signaling pathway via binding to the high mobility group AT-Hook 2 (HMGA2) mRNA in VSMCs. Additionally, GLP-1RA liraglutide may prevent the migration and proliferation of VSMCs by raising let7d-5p levels.

CONCLUSIONS

High glucose stimulated the proliferation and migration of VSMCs by regulating the let7d-5p/HMGA2/GSK3β/β-catenin pathway, and liraglutide may slow atherosclerosis by increasing the levels of miR let7d-5p.

Significance of High-Mobility Group A Protein 2 Expression in Pancreatic Ductal Adenocarcinoma and Ampullary Adenocarcinoma

BACKGROUND/AIMS

Pancreatic and ampullary adenocarcinoma (AAC) are quite resistant to chemotherapy with high metastasis potential. Our study aimed to interpret high-mobility group A protein 2 (HMGA2) expression in benign and precursor pancreatic lesions and pancreatic and ampullary carcinoma and to evaluate its relationship with epithelial-mesenchymal transition (EMT) and clinicopathological parameters.

MATERIALS AND METHODS

In this study, normal-appearing pancreas, chronic pancreatitis (CP), low- (L) and high (H)-grade pancreatic intraepithelial neoplasia (PanIN), pancreatic ductal adenocarcinoma (PDAC), and AAC were evaluated with the immunohistochemical marker of HMGA2. Vimentin and E-cadherin immunohistochemical stains were applied in PDAC and AAC.

RESULTS

The HMGA2 expression was not detected in normal-appearing pancreas, CP, and L-PanIN. A statistically significant expression was observed in PDAC and H-PanIN (P < .001). A statistically significant correlation was found between loss of membranous E-cadherin expression and vimentin positivity and HMGA2 expression (P > .05). The HMGA2 expression was observed to increase the risk of diseaserelated death and decrease overall survival (OS) in AAC and the neoplasia group (P = .002 and P = .016, respectively). There was no significant difference in OS and risk of death in PDAC (P > .05) with respect to HMGA2 positivity.

CONCLUSION

High-mobility group A protein 2 is a helpful immunohistochemical marker in differentiating CP from PDAC. It also plays a role in EMT and may serve as a potential new prognostic agent and therapeutic target in tumors of the periampullary region, especially AAC.

Novel roles for HMGA2 isoforms in regulating oxidative stress and sensitizing to RSL3-Induced ferroptosis in prostate cancer cells

Oxidative stress is increased in several cancers including prostate cancer, and is currently being exploited in cancer therapy to induce ferroptosis, a novel nonapoptotic form of cell death. High mobility group A2 (HMGA2), a non-histone protein up-regulated in several cancers, can be truncated due to chromosomal rearrangement or alternative splicing of HMGA2 gene. The purpose of this study is to investigate the role of wild-type vs. truncated HMGA2 in prostate cancer (PCa). We analyzed the expression of wild-type vs. truncated HMGA2 and showed that prostate cancer patient tissue and some cell lines expressed increasing amounts of both wild-type and truncated HMGA2 with increasing tumor grade, compared to normal epithelial cells. RNA-Seq analysis of LNCaP prostate cancer cells stably overexpressing wild-type HMGA2 (HMGA2-WT), truncated HMGA2 (HMGA2-TR) or empty vector (Neo) control revealed that HMGA2-TR cells exhibited higher oxidative stress compared to HMGA2-WT or Neo control cells, which was also confirmed by analysis of basal reactive oxygen species (ROS) levels using 2', 7'-dichlorofluorescin diacetate (DCFDA) dye, the ratio of reduced glutathione/oxidized glutathione (GSH/GSSG) and NADP/NADPH using metabolomics. This was associated with increased sensitivity to RAS-selective lethal 3 (RSL3)-induced ferroptosis that could be antagonized by ferrostatin-1. Additionally, proteomic and immunoprecipitation analyses showed that cytoplasmic HMGA2 protein interacted with Ras GTPase-activating protein-binding protein 1 (G3BP1), a cytoplasmic stress granule protein that responds to oxidative stress, and that G3BP1 transient knockdown increased sensitivity to ferroptosis even further. Endogenous knockdown of HMGA2 or G3BP1 in PC3 cells reduced proliferation which was reversed by ferrostatin-1. In conclusion, we show a novel role for HMGA2 in oxidative stress, particularly the truncated HMGA2, which may be a therapeutic target for ferroptosis-mediated prostate cancer therapy.

Multi-omics data integration and modeling unravels new mechanisms for pancreatic cancer and improves prognostic prediction

Pancreatic ductal adenocarcinoma (PDAC), has recently been found to be a heterogeneous disease, although the extension of its diversity remains to be fully understood. Here, we harmonize transcriptomic profiles derived from both PDAC epithelial and microenvironment cells to develop a Master Regulators (MR)-Gradient model that allows important inferences on transcriptional networks, epigenomic states, and metabolomics pathways that underlies this disease heterogeneity. This gradient model was generated by applying a blind source separation based on independent components analysis and robust principal component analyses (RPCA), following regulatory network inference. The result of these analyses reveals that PDAC prognosis strongly associates with the tumor epithelial cell phenotype and the immunological component. These studies were complemented by integration of methylome and metabolome datasets generated from patient-derived xenograft (PDX), together experimental measurements of metabolites, immunofluorescence microscopy, and western blot. At the metabolic level, PDAC favorable phenotype showed a positive correlation with enzymes implicated in complex lipid biosynthesis. In contrast, the unfavorable phenotype displayed an augmented OXPHOS independent metabolism centered on the Warburg effect and glutaminolysis. Epigenetically, we find that a global hypermethylation profile associates with the worst prognosis. Lastly, we report that, two antagonistic histone code writers, SUV39H1/SUV39H2 (H3K9Me3) and KAT2B (H3K9Ac) were identified key deregulated pathways in PDAC. Our analysis suggests that the PDAC phenotype, as it relates to prognosis, is determined by a complex interaction of transcriptomic, epigenomic, and metabolic features. Furthermore, we demonstrated that PDAC prognosis could be modulated through epigenetics.

Prognostic significance of high mobility group A2 (HMGA2) in pancreatic ductal adenocarcinoma: malignant functions of cytoplasmic HMGA2 expression

PURPOSE

HMGA2 has frequently been found in benign as well as malignant tumors and a significant association between HMGA2 overexpression and poor survival in different malignancies was described. In pancreatic ductal adenocarcinoma (PDAC), nuclear HMGA2 expression is associated with tumor dedifferentiation and presence of lymph node metastasis. Nevertheless, the impact of HMGA2 occurrence in other cell compartments is unknown.

METHODS

Intracellular distribution of HMGA2 was analyzed in PDAC (n = 106) and peritumoral, non-malignant ducts (n = 28) by immunohistochemistry. Findings were correlated with clinico-pathological data. Additionally, intracellular HMGA2 presence was studied by Western blotting of cytoplasmic and nuclear fractions of cultured cells.

RESULTS

HMGA2 was found in the cytoplasm and in the nucleus of cultured cells. In human tumor tissue, HMGA2 was also frequently found in the cytoplasm and the nucleus of tumor cells, however, nuclear staining was generally stronger. Direct comparison from tumor tissue with corresponding non-neoplastic peritumoral tissue revealed significantly stronger expression in tumors (p = 0.003). Of note, the nuclear staining was significantly stronger in lymph node metastatic cell nuclei compared to primary tumor cell nuclei (p = 0.049). Interestingly, cytoplasmic staining positively correlated with lymph vessel (p = 0.004) and venous invasion (p = 0.046).

CONCLUSION

HMGA2 is a prognostic marker in PDAC. Firstly, we found a positive correlation for cytoplasmic HMGA2 expression with lympho-vascular invasion and, secondly, we found a significantly stronger nuclear expression of HMGA2 in cancer-positive lymph node nuclei compared to primary tumor cell nuclei. So far, the role of cytoplasmic HMGA2 is nearly unknown, however, our data lend support to the hypothesis that cytoplasmic HMGA2 expression is involved in nodal spread.

Small interfering-high mobility group A2 attenuates epithelial-mesenchymal transition in thymic cancer cells via the Wnt/β-catenin pathway

Thymus carcinoma is one of the thymic epithelial neoplasms with high metastasis, which does not have any good treatment at present. High mobility group A2 (HMGA2) is highly expressed in a variety of malignant tumors, such as lung cancer, colon cancer and ovarian cancer and is closely related to tumor invasion and metastasis. The present study aimed to investigate the effect and mechanism of HMGA2 on epithelial-mesenchymal transition (EMT) in thymic cancer cells. IU-TAB-1, A549, HCT-116 and 293T cells were screened by testing the protein expression level of HMGA2 though western blotting and subjected to HMGA2 interference [small interfering (si)-HMGA2]. Cell proliferation was evaluated using the Cell Counting Kit-8 assay. Cell migration and invasion were detected using the Transwell assay. Cell apoptosis was examined using flow cytometry and β-catenin expression was observed by immunofluorescence. The levels of E-cadherin, vimentin, Wnt3a, Wnt5a and β-catenin proteins were determined by western blotting. Among the four cell lines tested, IU-TAB-1 cells demonstrated the highest expression of HMGA2 (P<0.05) and were hence selected for subsequent experiments. Compared with the control group (untransfected cells), si-HMGA2 resulted in significantly decreased proliferation, migration and invasion of IU-TAB-1 cells, whereas apoptosis was increased (P<0.05). The protein expression of vimentin, Wnt3a, Wnt5a and β-catenin was significantly decreased by si-HMGA2 compared with the control group (P<0.05), whereas E-cadherin expression was increased (P<0.05). After treatment with si-HMGA2 in combination with Wnt/β-catenin agonists (SKL2001) or inhibitors (XAV-939), EMT was respectively enhanced or inhibited in IU-TAB-1 cells. Overall, si-HMGA2 may attenuate EMT in thymic cancer cells and the mechanism may be related to the Wnt/β-catenin pathway.

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.

Oncogenic role of HMGA2 in fusion-negative rhabdomyosarcoma cells

Background

Rhabdomyosarcoma (RMS) is the most common pediatric soft tissue sarcoma. There are two subtypes, fusion gene-positive RMS (FP-RMS) and fusion gene-negative RMS (FN-RMS), depending on the presence of a fusion gene, either PAX3-FOXO1 or PAX7-FOXO1. These fusion genes are thought to be oncogenic drivers of FP-RMS. By contrast, the underlying mechanism of FN-RMS has not been thoroughly investigated. It has recently been shown that HMGA2 is specifically positive in pathological tissue from FN-RMS, but the role of HMGA2 in FN-RMS remains to be clarified.

Methods

In this study, we used FN-RMS cell lines to investigate the function of HMGA2. Gene expression, cell growth, cell cycle, myogenic differentiation, tumor formation in vivo, and cell viability under drug treatment were assessed.

Results

We found that HMGA2 was highly expressed in FN-RMS cells compared with FP-RMS cells and that knockdown of HMGA2 in FN-RMS cells inhibited cell growth and induced G1 phase accumulation in the cell cycle and myogenic differentiation. Additionally, we showed using both gain-of-function and loss-of-function assays that HMGA2 was required for tumor formation in vivo. Consistent with these findings, the HMGA2 inhibitor netropsin inhibited the cell growth of FN-RMS.

Conclusions

Our results suggest that HMGA2 has important role in the oncogenicity of FP-RMS and may be a potential therapeutic target in patients with FN-RMS.

Cytoplasmic levels of high mobility group A2 determine survival prognoses in breast cancer patients

BACKGROUND

High mobility group A proteins are involved in chromatin remodeling, thereby influencing multiple fundamental biological processes. HMGA2 has been linked to oncogenic traits among a variety of malignancies.

OBJECTIVE

To determine the prognostic implications of subcellular distribution patterns of HMGA2 in breast cancer.

METHODS

Nuclear and cytoplasmic HMGA2 was evaluated in 342 breast cancer specimens and matched with clinico-pathological parameters.

RESULTS

Overall and cytoplasmic, but not nuclear, levels of HMGA2 correlated with better survival prognoses in our collective (hazard ratio (HR) 0.34, P = 0.001 and HR 0.34, P < 0.001, respectively). The protective effect of cytoplasmic HMGA2 persisted in the Luminal A and triple negative breast cancer subgroups. Evaluating Luminal A and B subgroups jointly, only cytoplasmic, but not overall or nuclear HMGA2 levels were associated with better survival (HR 0.42, 95% confidence interval 0.21, 0.86, P = 0.017), irrespective of tumor size and node status. The addition of HMGA2 overall and cytoplasmic scores strengthened the prognostic selectivity in a model of conventional breast cancer risk factors. No predictive significance with regard to endocrine or chemoendocrine therapies was observed.

CONCLUSION

Unexpectedly, we found a favorable survival probability upon overall levels of HMGA2 in our breast cancer collective, which was predominantly determined by the presence of HMGA2 in the cytoplasm.

Overexpression of HMGA2 in breast cancer promotes cell proliferation, migration, invasion and stemness

Despite improved therapeutic strategies for early-stage breast cancer, the most common cancer type in women, relapse remains common and the underlying mechanisms for this progression remain poorly understood. To gain more insight, we studied the DNA-binding protein HMGA2 in breast cancer development and stemness. We demonstrated that HMGA2 is overexpressed in breast cancer tissues at the mRNA and protein levels (P value <0.0001). HMGA2 knockdown and overexpression in breast cancer cells revealed that HMGA2 promotes cell proliferation and protects against apoptosis via the intrinsic pathway. HMGA2 knockdown also causes cell cycle arrest in G2/M phase. In addition, we found that HMGA2 increases breast cancer cell migration and invasion (P value <0.001) and promotes the acquisition of cancer stem cell features, both in vitro, in colony formation (P value <0.01) and spheroid assays, and in breast cancer tissues. Overexpression of HMGA2 in breast cancer spurs the acquisition of several hallmarks of cancer, including increased cell proliferation, migration, invasion and stemness, and decreased apoptosis. Thus, targeting HMGA2 could represent an effective strategy to block breast cancer progression.

HMGA2 Antisense Long Non-coding RNAs as New Players in the Regulation of HMGA2 Expression and Pancreatic Cancer Promotion

Background: Natural antisense long non-coding RNAs (lncRNAs) are regulatory RNAs transcribed from the opposite strand of either protein coding or non-coding genes, able to modulate their own sense gene expression. Hence, their dysregulation can lead to pathologic processes. Cancer is a complex class of diseases determined by the aberrant expression of a variety of factors, among them, the oncofetal chromatin architectural proteins High Mobility Group A (HMGA) modulate several cancer hallmarks. Thus, we decided to investigate the presence of natural antisense lncRNAs in HMGA1 and HMGA2 loci, and their possible involvement in gene expression regulation. Methods: We used FANTOM5 data resources, FANTOM-CAT genome browser and Zenbu visualization tool, which employ 1,829 human CAGE and RNA-sequencing libraries, to determine expression, ontology enrichment, and dynamic regulation of natural antisense lncRNAs in HMGA1 and HMGA2 loci. We then performed qRT-PCR in different cancer cell lines to validate the existence of HMGA2-AS1 transcripts. We depleted HMGA2-AS1 transcripts with siRNAs and investigated HMGA2 expression by qRT-PCR and western blot analyses. Moreover, we evaluated cell viability and migration by MTS and transwell assays, and EMT markers by qRT-PCR and immunofluorescence. Furthermore, we used bioinformatics approaches to evaluate HMGA2 and HMGA2-AS1 correlation and overall survival in tumor patients. Results: We found the presence of a promoter-associated lncRNA (CATG00000088127.1) in the HMGA1 gene and three antisense genes (RPSAP52, HMGA2-AS1, and RP11-366L20.3) in the HMGA2 gene. We studied the uncharacterized HMGA2-AS1 transcripts, validating their existence in cancer cell lines and observing a positive correlation between HMGA2 and HMGA2-AS1 expression in a cancer-derived patient dataset. We showed that HMGA2-AS1 transcripts positively modulate HMGA2 expression and migration properties of PANC1 cells through HMGA2. In addition, Kaplan-Meier analysis showed that high level of HMGA2-AS1 is a negative prognostic factor in pancreatic cancer patients. Conclusions: Our results describe novel antisense lncRNAs associated with HMGA1 and HMGA2 genes. In particular, we demonstrate that HMGA2-AS1 is involved in the regulation of its own sense gene expression, mediating tumorigenesis. Thus, we highlight a new layer of complexity in the regulation of HMGA2 expression, providing new potential targets for cancer therapy.

HMGA Proteins in Stemness and Differentiation of Embryonic and Adult Stem Cells

HMGA1 and HMGA2 are chromatin architectural proteins that do not have transcriptional activity per se, but are able to modify chromatin structure by interacting with the transcriptional machinery and thus negatively or positively regulate the transcription of several genes. They have been extensively studied in cancer where they are often found to be overexpressed but their functions under physiologic conditions have still not been completely addressed. Hmga1 and Hmga2 are expressed during the early stages of mouse development, whereas they are not detectable in most adult tissues. Hmga overexpression or knockout studies in mouse have pointed to a key function in the development of the embryo and of various tissues. HMGA proteins are expressed in embryonic stem cells and in some adult stem cells and numerous experimental data have indicated that they play a fundamental role in the maintenance of stemness and in the regulation of differentiation. In this review, we discuss available experimental data on HMGA1 and HMGA2 functions in governing embryonic and adult stem cell fate. Moreover, based on the available evidence, we will aim to outline how HMGA expression is regulated in different contexts and how these two proteins contribute to the regulation of gene expression and chromatin architecture in stem cells.

Long Non-Coding RNA EGOT Promotes the Malignant Phenotypes of Hepatocellular Carcinoma Cells and Increases the Expression of HMGA2 via Down-Regulating miR-33a-5p

Background

Chronic hepatitis C virus (HCV) infection is an important risk factor for hepatocellular carcinoma (HCC). EGOT is a long non-coding RNA (lncRNA) induced after HCV infection that increases viral replication by antagonizing the antiviral response. Interestingly, EGOT also acts as a crucial regulator in multiple cancers. However, its role in HCC remains unclear.

Methods

Real-time PCR (RT-PCR) was used to detect the expression of EGOT in HCC samples and cell lines. CCK-8 assay and colony formation assay were performed to evaluate the effect of EGOT on proliferation. Scratch healing assay and transwell assay were used to detect the changes of migration and invasion. Flow cytometry was used to detect the effect of EGOT on apoptosis. Interaction between EGOT and miR-33a-5p was determined by bioinformatics analysis, RT-PCR, and dual-luciferase reporter assay. Western blot was used to confirm that high mobility group protein A2 (HMGA2) could be modulated by EGOT.

Results

Compared with normal liver tissues, the expression level of EGOT in HCC tissues was significantly up-regulated. EGOT markedly regulated viability, migration and invasion of HCC cells. The expression level of EGOT was negatively correlated the expression level of miR-33a-5p. It is also confirmed that EGOT could specifically bind to miR-33a-5p and could reduce its expression, in turn, up-regulate the expression of HMGA2.

Conclusion

Our data imply that EGOT may be a novel therapeutic target for HCC, and highlights the key role of EGOT/miR-33a-5p/HMGA2 in the progression of this deadly disease.

MicroRNA-98 targets HMGA2 to inhibit the development of retinoblastoma through mediating Wnt/β-catenin pathway

BACKGROUND

Recently, the incidence and mortality of retinoblastoma (RB) have gradually increased. Many studies support the pivotal role of microRNAs (miRNAs) in the pathogenesis of RB. Alternation of microRNA-98 (miR-98) expression has been detected in several cancers, excluding RB. This study was designed to assess the regulatory mechanisms of miR-98 in human RB.

METHODS

RT-qPCR and Western blot analysis were used to detect miR-98 and HMGA2 expression. The effects of miR-98 were explored using the CCK-8 and Transwell assays. Dual-luciferase reporter assay was performed to confirm the relationship between miR-98 and HMGA2.

RESULTS

In RB, downregulation of miR-98 was identified. Upregulation of miR-98 inhibited proliferation, invasion and migration of RB cells. Further, HMGA2 was confirmed as a direct target gene of miR-98. And knockdown of HMGA2 suppressed the progression of RB. Moreover, upregulation of HMGA2 reversed the suppressive effects in the development of RB. In addition, miR-98 also showed suppressive effect on EMT and Wnt/β-catenin pathway.

CONCLUSION

MiR-98 targets HMGA2 to act as a tumor suppressor in RB by mediating Wnt/β-catenin pathway.

MicroRNA-9 exerts antitumor effects on hepatocellular carcinoma progression by targeting HMGA2

Accumulating evidence has demonstrated that the aberrant expression of microRNAs (miRs or miRNAs) may contribute to the initiation and progression of various types of human cancer and may also constitute biomarkers for cancer diagnosis and therapy. However, the specific function of miR‐9 in hepatocellular carcinoma (HCC) remains unclear, and the mechanisms that underlie HCC are incompletely understood. Here, we report that miR‐9 expression was significantly decreased in clinical tumor tissue samples, as well as in a cohort of HCC cell lines. In addition, it was demonstrated that overexpression of miR‐9 suppressed the proliferative and migratory capacity of HCC cells and impaired cell cycle progression. Furthermore, high mobility group AT‐hook 2 (HMGA2) was verified as a downstream target gene of miR‐9 using a luciferase reporter assay. Quantitative RT‐PCR and western blotting implicated HMGA2 in the miR‐9‐mediated reduction of HCC cell growth. In vivo, transfection with miR‐9 mimics down‐regulated the expression of HMGA2, thus leading to a dramatic reduction in tumor growth in a mouse xenograft model. These results suggest that miR‐9 may exert critical antitumor effects on HCC by directly targeting HMGA2, and the miR9/HMGA2 signaling pathway may be of use for the diagnosis and prognosis of patients with HCC.

BRCA1 regulates HMGA2 levels in the Swan71 trophoblast cell line

During early placental development, tumor suppressors and oncogenes work synergistically to regulate cell proliferation and differentiation in a restrained manner compared with the uncontrollable growth in cancer. One example of this partnership is the regulation of the oncofetal protein HMGA2 by BRCA1. BRCA1 forms a repressor complex with ZNF350 and CtIP to bind to the promoter of HMGA2, preventing transcription. Chromatin immunoprecipitation determined BRCA1 forms this repressor complex in human trophoblast cells, suggesting a role in the placenta. Furthermore, miR-182 has been shown to target BRCA1 mRNA in ovarian cancer cells, blocking the formation of the BRCA1 repressor complex and allowing increased transcription of HMGA2. miR-182 was one of the first miRNAs described as elevated in the serum and placentas of preeclamptic women. Therefore, we hypothesized that BRCA1 is essential for normal trophoblast cell development. We used CRISPR-Cas9 genome editing and miR-182 overexpression to decrease BRCA1 protein in the Swan71 cell line. HMGA2 was significantly increased in the BRCA1 KO and miR-182 overexpressing cells compared to controls. We also determined that BRCA1 repressor complex binding to HMGA2 was significantly reduced in BRCA1 KO and miR-182 overexpressing cells compared with controls, leading us to conclude that increased HMGA2 was because of decreased binding of the BRCA1 repressor complex. Finally, we found that the caspase activity was significantly higher in BRCA1 KO and miR-182 overexpressing cells suggesting an increased amount of apoptosis. These data suggest that BRCA1 is an important regulator of the oncofetal protein HMGA2 and promotes cell survival in human placental cells.

Role of High-mobility Group Protein A Isoforms and Their Clinicopathologic Significance in Primary Retinoblastoma

BACKGROUND

High-mobility group proteins A (HMGA) are more abundant in rapidly dividing and transformed cells. These are a group of proteins regulating tumorigenesis and tumor invasion. Increased expression of HMGA1 and HMGA2 has been reported in various benign and malignant tumors. The aim of the present study was to analyze expression of HMGA1 and HMGA2 proteins in retinoblastoma.

METHODS

Protein expression of HMGA1 and HMGA2 in 80 formalin-fixed retinoblastoma tissues was performed by immunohistochemistry, and their mRNA expressions were analyzed on 40 fresh primary enucleated retinoblastoma samples by semiquantitative reverse transcription polymerase chain reaction. Results were then correlated with clinicopathologic parameters.

RESULTS

Immunohistochemical analysis of HMGA1 and HMGA2 was seen in 56.25% and 58.75% of retinoblastoma cases, respectively. mRNA expressions of HMGA1 and HMGA2 was found to be 57.55% and 62.5%, respectively. The mRNA results correlated well with immunostaining results. Expression of both HMGA1 and HMGA2 was significantly associated with choroidal invasion and poor tumor differentiation.

CONCLUSIONS

HMGA1 and HMGA2 proteins may contribute to tumorigenesis of Rb. Expression of HMGA1 and HMGA2 predicts poor prognosis and could serve as a therapeutic target in the management of RB. Further experiments are needed to determine the role of these proteins as therapeutic targets in tumorigenesis.

Prognostic value of high mobility group protein A2 (HMGA2) over-expression in cancer progression

The high mobility group A2 (HMGA2; also called HMGI-C) gene is an architectural transcription factor that belonging to the high mobility group AT-hook (HMGA) gene family. HMGA2 is aberrantly regulated in several human tumors. Over-expression of HMGA2 is correlated with a higher risk of metastasis and an unfavorable prognosis in patients with cancer. We performed a meta-analysis to determine the clinic-pathological and prognostic value of HMGA2 overexpression in different human tumors. A comprehensive literature search was performed using PubMed, Embase, Cochrane Library, Scopus, MEDLINE, Google Scholar and ISI Web of Science. Hazard ratios (HRs)/odds ratios (ORs) and their 95% confidence intervals (CIs) were used to assess the strength of the association between HMGA2 expression and overall survival (OS)/progression free survival (PFS)/disease free survival (DFS). A total of 5319 patients with 19 different types of cancer from 35 articles were evaluated. Pooled data analysis indicated that increased HMGA2 expression in cancer patients predicted a poor OS (HR = 1.70; 95% CI = 1.6-1.81; P < 0.001; fixed-effect model). In subgroup analyses, high HMGA2 expression was particularly associated with poor OS in individuals with gastrointestinal (GI) cancer (HR = 1.89, 95% CI: 1.83-1.96; fixed-effect model) and HNSCC cancer (HR-1.78, 95%CI: 1.44-2.21; fixed-effect model). Over-expression of HMGA2 was associated with vascular invasion (OR = 0.16, 95% CI = 0.05-0.49; P = 0.001) and lymphatic invasion (OR = 1.89, 95% CI = 1.06-3.38; P = 0.032). Further studies should be conducted to validate the prognostic value of HMGA2 for patients with GI cancers.

Hmga2 is dispensable for pancreatic cancer development, metastasis, and therapy resistance

Expression of the chromatin-associated protein HMGA2 correlates with progression, metastasis and therapy resistance in pancreatic ductal adenocarcinoma (PDAC). Hmga2 has also been identified as a marker of a transient subpopulation of PDAC cells that has increased metastatic ability. Here, we characterize the requirement for Hmga2 during growth, dissemination, and metastasis of PDAC in vivo using conditional inactivation of Hmga2 in well-established autochthonous mouse models of PDAC. Overall survival, primary tumour burden, presence of disseminated tumour cells in the peritoneal cavity or circulating tumour cells in the blood, and presence and number of metastases were not significantly different between mice with Hmga2-wildtype or Hmga2-deficient tumours. Treatment of mice with Hmga2-wildtype and Hmga2-deficient tumours with gemcitabine did not uncover a significant impact of Hmga2-deficiency on gemcitabine sensitivity. Hmga1 and Hmga2 overlap in their expression in both human and murine PDAC, however knockdown of Hmga1 in Hmga2-deficient cancer cells also did not decrease metastatic ability. Thus, Hmga2 remains a prognostic marker which identifies a metastatic cancer cell state in primary PDAC, however Hmga2 has limited if any direct functional impact on PDAC progression and therapy resistance.

High mobility group A2 (HMGA2) promotes EMT via MAPK pathway in prostate cancer

Studies have shown that High mobility group A2 (HMGA2), a non-histone protein, can promote epithelial-mesenchymal transition (EMT), which plays a critical role in prostate cancer progression and metastasis. Interestingly, full-length or wild-type HMGA2 and truncated (lacking the 3'UTR) HMGA2 isoforms are overexpressed in several cancers. However, there are no studies investigating the expression and differential roles of WT vs truncated HMGA2 isoforms in prostate cancer. Immunohistochemical staining of prostate tissue microarray revealed low membrane expression in normal epithelial prostate cells, and that expression increased with tumor grade as well as a switch from predominantly cytoplasmic HMGA2 in lower tumor grades, to mostly nuclear in high grade and bone metastatic tissue. LNCaP cells stably overexpressing wild-type HMGA2 displayed nuclear localization of HMGA2 and induction of EMT associated with increased Snail, Twist and vimentin expression compared to LNCaP Neo control cells, as shown by immunofluorescence and western blot analyses. This was associated with increased cell migration on collagen shown using boyden chamber assay. Conversely, LNCaP cells overexpressing truncated HMGA2 showed cytoplasmic HMGA2 expression that did not induce EMT yet displayed increased cell proliferation and migration compared to LNCaP Neo. Both wild-type and truncated HMGA2 increased levels of phospho-ERK, and interestingly, treatment with U0126, MAPK inhibitor, antagonized wild-type HMGA2-mediated EMT and cell migration, but did not affect truncated HMGA2-mediated cell proliferation or migration. Therefore, although both wild-type and truncated HMGA2 may promote prostate tumor progression, wild-type HMGA2 acts by inducing EMT via MAPK pathway.

The long non-coding RNA LSINCT5 promotes malignancy in non-small cell lung cancer by stabilizing HMGA2

Long non-coding RNAs (lncRNAs) can actively participate in tumorigenesis in various cancers. However, the involvement of lncRNA long stress induced non-coding transcripts 5 (LSINCT5) in non-small cell lung cancer (NSCLC) remains largely unknown. Here we showed a novel lncRNA signature in NSCLC through lncRNA profiling. Increased LSINCT5 expression positively correlates with malignant clinicopathological features and poor survival. LSINCT5 can promote migration and viability of various NSCLC cells in vitro and also enhance lung cancer progression in vivo. RNA immunoprecipitation followed by mass spectrometry has identified that LSINCT5 interacts with HMGA2. This physical interaction can increase the stability of HMGA2 by inhibiting proteasome-mediated degradation. Therefore, LSINCT5 may possibly contribute to NSCLC tumorigenesis by stabilizing the oncogenic factor of HMGA2. This novel LSINCT5/HMGA2 axis can modulate lung cancer progression and might be a promising target for pharmacological intervention.

MicroRNA-150 suppresses triple-negative breast cancer metastasis through targeting HMGA2

Background

Growing evidence suggests that miR-150 plays an inhibitory role in various types of cancer. However, the function and underlying mechanisms of miR-150 in triple-negative breast cancer (TNBC) remain unknown.

Patients and methods

miR-150 expression was detected by qRT-PCR and ISH in TNBC tumor and adjacent normal breast tissues. miR-150 function was analyzed by wound healing and transwell assay in vitro and mouse lung metastasis model in vivo. mRNA microarray, qRT-PCR, western blotting and luciferase assay were used to identify the target gene of miR-150. HMGA2 over-expression plasmid was co-transfected with miR-150 to study the role of miR-150 through regulating HMGA2.

Results

We found that miR-150 was down-regulated in TNBC tumor tissues compared to corresponding adjacent, normal breast tissues, and was correlated with decreased lymph-node metastasis. Ectopic expression of miR-150 suppressed TNBC cell migration in vitro and metastasis in vivo. Mechanistic study revealed that miR-150 down-regulates HMGA2 by directly targeting its mRNA. Moreover, the suppression of cell migration caused by miR-150 is relieved by over-expression of HMGA2, suggesting that miR-150 inhibits migration of TNBC cells by down-regulating HMGA2.

Conclusion

This work indicates that the miR-150/HMGA2 axis may serve as a treatment marker in TNBC.

HMGA2, but not HMGA1, is overexpressed in human larynx carcinomas

AIMS

Malignant tumours from the upper aerodigestive tract are grouped collectively in the class of head and neck squamous cell carcinoma (HNSCC). The head and neck tumours were responsible for more than 500 000 cancer cases in 2012, accounting for the sixth highest incidence rate and mortality worldwide among all tumour types. Laryngeal squamous cell carcinoma (LSCC) possesses the second highest incidence rate among all HNSCC. Despite significant advances in surgery and radiotherapy during the last few decades, no treatment has been shown to achieve a satisfactory therapeutic outcome and the mortality rate of LSCC is still high, with a 5-year survival rate of 64%. Therefore, further investigations are required to identify the pathogenesis of LSCC.

METHODS AND RESULTS

In order to search for new LSCC biomarkers, we have analysed the expression of the HMGA family members, HMGA1 and HMGA2, by quantitative reverse transcription-polymerase chain reaction (qRT-PCR) and immunohistochemistry. HMGA proteins are usually absent in the healthy adult tissues. In contrast, their constitutive expression is a feature of several neoplasias, being associated with a highly malignant phenotype and reduced survival. Here, we report HMGA2 overexpression in larynx carcinomas. Conversely, HMGA1 does not show any differences in its expression between normal and carcinoma tissues. Interestingly, HMGA2 overexpression appears associated with that of two HMGA1-pseudogenes, HMGA1P6 and HMGA1P7, acting as a sponge for HMGA1- and HMGA2-targeting microRNAs and involved in several human cancers.

CONCLUSIONS

Therefore, HMGA2 overexpression appears to be a strong feature of larynx carcinoma, supporting its detection as a valid tool for the diagnosis of these malignancies.

The neuroendocrine phenotype, genomic profile and therapeutic sensitivity of GEPNET cell lines

Experimental models of neuroendocrine tumour disease are scarce, and no comprehensive characterisation of existing gastroenteropancreatic neuroendocrine tumour (GEPNET) cell lines has been reported. In this study, we aimed to define the molecular characteristics and therapeutic sensitivity of these cell lines. We therefore performed immunophenotyping, copy number profiling, whole-exome sequencing and a large-scale inhibitor screening of seven GEPNET cell lines. Four cell lines, GOT1, P-STS, BON-1 and QGP-1, displayed a neuroendocrine phenotype while three others, KRJ-I, L-STS and H-STS, did not. Instead, these three cell lines were identified as lymphoblastoid. Characterisation of remaining authentic GEPNET cell lines by copy number profiling showed that GOT1, among other chromosomal alterations, harboured losses on chromosome 18 encompassing the SMAD4 gene, while P-STS had a loss on 11q. BON-1 had a homozygous loss of CDKN2A and CDKN2B, and QGP-1 harboured amplifications of MDM2 and HMGA2 Whole-exome sequencing revealed both disease-characteristic mutations (e.g. ATRX mutation in QGP-1) and, for patient tumours, rare genetic events (e.g. TP53 mutation in P-STS, BON-1 and QGP-1). A large-scale inhibitor screening showed that cell lines from pancreatic NETs to a greater extent, when compared to small intestinal NETs, were sensitive to inhibitors of MEK. Similarly, neuroendocrine NET cells originating from the small intestine were considerably more sensitive to a group of HDAC inhibitors. Taken together, our results provide a comprehensive characterisation of GEPNET cell lines, demonstrate their relevance as neuroendocrine tumour models and explore their therapeutic sensitivity to a broad range of inhibitors.

LncRNA HOTAIR influences cell growth, migration, invasion, and apoptosis via the miR-20a-5p/HMGA2 axis in breast cancer

To study the regulatory effect of lncRNA HOTAIR/miR-20a-5p/HMGA2 axis on breast cancer (BC) cell growth, cell mobility, invasiveness, and apoptosis. The microarray data of lncRNAs and mRNAs with differential expression in BC tissues were analyzed in the Cancer Genome Atlas (TCGA) database. LncRNA HOX transcript antisense RNA (lncRNA HOTAIR) expression in BC was assessed by qRT-PCR. Cell viability was confirmed using MTT and colony formation assay. Cell apoptosis was analyzed by TdT-mediated dUTP nick-end labeling (TUNEL) assay. Cell mobility and invasiveness were testified by transwell assay. RNA pull-down and dual luciferase assay were used for analysis of the correlation between lncRNA HOTAIR and miR-20a-5p, as well as relationship of miR-20a-5p with high mobility group AT-hook 2 (HMGA2). Tumor xenograft study was applied to confirm the correlation of lncRNA HOTAIR/miR-20a-5p/HMGA2 axis on BC development in vivo. The expression levels of the lncRNA HOTAIR were upregulated in BC tissues and cells. Knockdown lncRNA HOTAIR inhibited cell propagation and metastasis and facilitated cell apoptosis. MiR-20a-5p was a target of lncRNA HOTAIR and had a negative correlation with lncRNA HOTAIR. MiR-20a-5p overexpression in BC suppressed cell growth, mobility, and invasiveness and facilitated apoptosis. HMGA2 was a target of miR-20a-5p, which significantly induced carcinogenesis of BC. BC cells progression was mediated by lncRNA HOTAIR via affecting miR-20a-5p/HMGA2 in vivo. LncRNA HOTAIR affected cell growth, metastasis, and apoptosis via the miR-20a-5p/HMGA2 axis in breast cancer.

BLIMP1 Induces Transient Metastatic Heterogeneity in Pancreatic Cancer

Pancreatic ductal adenocarcinoma (PDAC) is one of the most metastatic and deadly cancers. Despite the clinical significance of metastatic spread, our understanding of molecular mechanisms that drive PDAC metastatic ability remains limited. By generating a genetically engineered mouse model of human PDAC, we uncover a transient subpopulation of cancer cells with exceptionally high metastatic ability. Global gene expression profiling and functional analyses uncovered the transcription factor BLIMP1 as a driver of PDAC metastasis. The highly metastatic PDAC subpopulation is enriched for hypoxia-induced genes, and hypoxia-mediated induction of BLIMP1 contributes to the regulation of a subset of hypoxia-associated gene expression programs. These findings support a model in which upregulation of BLIMP1 links microenvironmental cues to a metastatic stem cell character.Significance: PDAC is an almost uniformly lethal cancer, largely due to its tendency for metastasis. We define a highly metastatic subpopulation of cancer cells, uncover a key transcriptional regulator of metastatic ability, and define hypoxia as an important factor within the tumor microenvironment that increases metastatic proclivity. Cancer Discov; 7(10); 1184-99. ©2017 AACR.See related commentary by Vakoc and Tuveson, p. 1067This article is highlighted in the In This Issue feature, p. 1047.

Stroma-regulated HMGA2 is an independent prognostic marker in PDAC and AAC

BACKGROUND

The HMGA2 protein has experimentally been linked to EMT and cancer stemness. Recent studies imply that tumour-stroma interactions regulate these features and thereby contribute to tumour aggressiveness.

METHODS

We analysed 253 cases of pancreatic ductal adenocarcinoma (PDAC) and 155 cases of ampullary adenocarcinoma (AAC) for HMGA2 expression by IHC. The data were correlated with stroma abundance and supplemented by experimental studies.

RESULTS

HMGA2 acts as an independent prognostic marker associated with a significantly shorter overall survival in both tumour types. Overall, HMGA2-positivity was more frequent in patients with PDAC than with AAC. The HMGA2 status in tumour cells significantly correlated with the abundance of PDGFRβ-defined stroma cells. In vivo co-injection of Panc-1 cancer cells with pancreatic stellate cells increased tumour growth in a manner associated with increased HMGA2 expression. Furthermore, in vitro treatment of Panc-1 with conditioned media from PDGF-BB-activated stellate cells increased their ability to form tumour spheroids.

CONCLUSIONS

This study identifies HMGA2 expression in tumour cells as an independent prognostic marker in PDAC and AAC. Correlative data analysis gives novel tissue-based evidence for a heterotypic cross-talk with stroma cells as a possible mechanism for HMGA2 induction, which is further supported by experimental models.

Function of high-mobility group A proteins in the DNA damage signaling for the induction of apoptosis

O⁶-Methylguanine produced in DNA can pair with thymine during DNA replication, thus leading to a G-to-A transition mutation. To prevent such outcomes, cells harboring O⁶-methylguanine-containing mispair undergo apoptosis that requires the function of mismatch repair (MMR) protein complex. To identify the genes involved in the induction of apoptosis, we performed gene-trap mutagenesis and isolated a clone of mouse cells exhibiting an increased resistance to the killing effect of an alkylating agent, N-methyl-N-nitrosourea (MNU). The mutant carries an insertion in the Hmga2 gene, which belongs to a gene family encoding the high-mobility group A non-histone chromatin proteins. To elucidate the function of HMGA proteins in the apoptosis pathway, we introduced siRNAs for HMGA1 and/or HMGA2 into human HeLa MR cells defective in O⁶-methylguanine-DNA methyltransferase. HMGA1- and HMGA2-single knockdown cells showed an increased resistance to MNU, and HMGA1/HMGA2-double knockdown cells exhibited further increased tolerance compared to the control. The phosphorylation of ATR and CHK1, the appearance of a sub-G₁ population, and caspase-9 activation were suppressed in the knockdown cells, although the formation of mismatch recognition complex was unaffected. These results suggest that HMGA family proteins function at the step following the damage recognition in the process of apoptosis triggered by O⁶-methylguanine.

Silencing of High Mobility Group Isoform I-C (HMGI-C) Enhances Paclitaxel Chemosensitivity in Breast Adenocarcinoma Cells (MDA-MB-468)

PURPOSE

HMGI-C (High Mobility Group protein Isoform I-C) protein is a member of the high-mobility group AT-hook (HMGA) family of small non-histone chromosomal protein that can modulate transcription of an ample number of genes. Genome-wide studies revealed up regulation of the HMGI-C gene in many human cancers. We suggested that HMGI-C might play a critical role in the progression and migration of various tumors. However, the exact role of HMGI-C in breast adenocarcinoma has not been cleared.

METHODS

The cells were transfected with siRNAs using transfection reagent. Relative HMGI-C mRNA and protein levels were measured by quantitative real-time PCR and Western blotting, respectively. The cytotoxic effects of HMGI-C siRNA, Paclitaxel alone and combination on breast adenocarcinoma cells were determined using MTT assay. The migration after treatment by HMGI-C siRNA, Paclitaxel alone and combination were detected by wound-healing respectively.

RESULTS

HMGI-C siRNA significantly reduced both mRNA and protein expression levels in a 48 hours after transfection and dose dependent manner. We observed that the knockdown of HMGI-C led to the significant reduced cell viability and inhibited cells migration in MDA-MB-468 cells in vitro.

CONCLUSION

These results propose that HMGI-C silencing and Paclitaxel treatment alone can inhibit the proliferation and migration significantly, furthermore, synergic effect of HMGI-C siRNA and Paclitaxel showed higher inhibition compared to mono treatment. Taken together, HMGI-C could be used as a promising therapeutic agent in the treatment of human breast adenocarcinoma. Therefore HMGI-C siRNA may be an effective adjuvant in human breast adenocarcinoma.

Pancreatic cyst fluid concentration of high-mobility group A2 protein acts as a differential biomarker of dysplasia in intraductal papillary mucinous neoplasm

BACKGROUND AND AIMS

No reliable cyst fluid biomarkers exist that allow preoperative identification of patients with intraductal papillary mucinous neoplasms (IPMNs) and high-risk pathology. High-mobility group (HMG) A2 protein has been demonstrated to be a biomarker of dysplasia in IPMNs. It is unknown whether HMGA2 protein is present in the cyst fluid from IPMNs. The aims of this study were to determine whether HMGA2 protein is present in the cyst fluid of IPMNs and demonstrate whether HMGA2 protein concentration correlates with the degree of dysplasia.

METHODS

Patients with surgically resected IPMNs and banked pancreatic cyst fluid were identified. Low-risk IPMNs (low-grade [LGD] or moderate dysplasia [MD]) and high-risk IPMNs (high-grade dysplasia [HGD] or invasive cancer) were identified. Pancreatic cyst fluid concentrations of HMGA2 protein were measured via enzyme-linked immunosorbent assay.

RESULTS

Samples from 31 patients were analyzed. HMGA2 protein was detected in the cyst fluid of 30 of 31 specimens (97%). Median cyst fluid HMGA2 protein concentration (ng/mL) was as follows: LGD, 0.6 (interquartile range [IQR] 0.35-0.6); MD, 1.55 (IQR 0.65-2.7); HGD, 4.2 (IQR 1.7-9.2) (P < .05). The median HMGA2 protein concentration was significantly higher in the HGD group (4.2 ng/mL, IQR 1.7-9.2) compared with the concentration in the low-risk group (1.1 ng/mL, IQR 0.6-2.7, P = .03).

CONCLUSION

HMGA2 protein is present in IPMN cyst fluid. Significantly higher concentrations of cyst fluid HMGA2 protein are found in IPMNs with HGD compared with lesions with LGD or MD. Cyst fluid concentrations of HMGA2 protein may thus serve as a biomarker to differentiate patients with high-risk IPMNs from those with low-risk IPMNs.

HMGI-C suppressing induces P53/caspase9 axis to regulate apoptosis in breast adenocarcinoma cells

PURPOSE

The HMGI-C (high mobility group protein isoform I-C) protein is a member of the high-mobility group AT-hook (HMGA) family of small non-histone chromosomal proteins that can modulate transcription of an ample number of genes. Genome-wide studies reveal upregulation of the HMGI-C gene in many human cancers, which suggests that HMGI-C might play a critical role in the progression of various tumors. However, the exact role of HMGI-C in breast adenocarcinoma has not been made clear.

METHODS

HMGI-C mRNA expression in breast cancer samples and marginal normal tissues was characterized using qRT-PCR. The cytotoxic effects of HMGI-C siRNA on breast adenocarcinoma cells were determined using MTT assay. Relative HMGI-C mRNA and protein levels were measured by quantitative real-time PCR and western blotting, respectively. Apoptosis detection was done using TUNEL and Annexin-V/PI assays, P53, caspase 3, 9, 8 and Bcl2 proteins evaluated by protein gel blot and miR34a, Let-7a genes investigates by QRT-PCR assay. Cell cycle was analyzed by flow cytometry assay using propidium iodide DNA staining.

RESULTS

An overexpression of HMGA2 was revealed with highly statistically significant differences between breast cancer samples and marginal normal tissues (P < 0.0001). HMGI-C siRNA significantly reduced both mRNA and protein expression levels in a 48-hour period after transfection and in a dose-dependent manner. We observed that the knockdown of HMGI-C led to the significant induction of apoptosis via mitochondrial pathway by inducing miR34a and cell cycle arrest in MDA-MB-468 cells in vitro.

CONCLUSIONS

These results propose that HMGI-C might play a critical role in the progression of breast adenocarcinoma. Here we introduced HMGI-C as a potential therapeutic target for trigger apoptosis and cell cycle arrest in human breast adenocarcinoma. Therefore HMGI-C siRNA may be an effective adjuvant in human breast adenocarcinoma.

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 MYCN-HMGA2-CDKN2A pathway in non-small cell lung carcinoma--differences in histological subtypes

Background

Extensive research has increased our understanding of the molecular alterations needed for non-small cell lung cancer (NSCLC) development. Deregulation of a pathway including MYCN, HMGA2 and CDKN2A, with the participation of DICER1, is of importance in several solid tumours, and may also be of significance in the pathogenesis of NSCLC.

Methods

Gene expression of MYCN, HMGA2, CDKN2A and DICER1 were investigated with RT-qPCR in surgically resected NSCLC tumour tissue from 175 patients. Expression of the let-7 microRNA family was performed in 78 adenocarcinomas and 16 matching normal lung tissue samples using microarrays. The protein levels of HMGA2 were determined by immunohistochemistry in 156 tumour samples and the protein expression was correlated with gene expression. Associations between clinical data, including time to recurrence, and expression of mRNA, protein and microRNAs were analysed.

Results

Compared to adenocarcinomas, squamous cell carcinomas had a median 5-fold increase in mRNA expression of HMGA2 (p = 0.003). A positive correlation (r = 0.513, p < 0.010) between HMGA2 mRNA expression and HMGA2 protein expression was seen. At the protein level, 90 % of the squamous cell carcinomas expressed high levels of the HMGA2 protein compared to 47 % of the adenocarcinomas (p < 0.0001). MYCN was positively correlated with HMGA2 (p < 0.010) and DICER1 mRNA expression (p < 0.010), and the expression of the let-7 microRNAs seemed to be correlated with the genes studied. MYCN expression was associated with time to recurrence in multivariate survival analyses (p = 0.020).

Conclusions

A significant difference in HMGA2 mRNA expression between the histological subtypes of NSCLC was seen with a higher expression in the squamous cell carcinomas. This was also found at the protein level, and we found a good correlation between the mRNA and the protein expression of HMGA2. Moreover, the expression of MYCN, HMGA2, and DICER1 seems to be correlated to each other and the expression of the let7-genes impacted by their expression. MYCN gene expression seems to be of importance in time to recurrence in this patient cohort with resected NSCLC.

Electronic supplementary material

The online version of this article (doi:10.1186/s12885-016-2104-9) contains supplementary material, which is available to authorized users.

Tumors of the lacrimal gland

Tumors of the lacrimal gland comprise a wide spectrum, of which the most common demonstrate epithelial and lymphoid differentiation. The diagnosis of lacrimal gland tumors depends primarily on histological evaluation, as do the choice of treatment and prognosis. For some lacrimal gland neoplasms, such as adenoid cystic carcinoma, the outlook is grave. Optimal treatment for several lacrimal gland tumors is also a matter of controversy. However, recent progress has been made in the molecular and genetic understanding of tumorigenesis for such lesions. This article presents an overview of the histopathology of lacrimal gland tumors, together with their epidemiological features, clinical characteristics, and treatment strategies.

Let-7 Sensitizes KRAS Mutant Tumor Cells to Chemotherapy

KRAS is the most commonly mutated oncogene in human cancers and is associated with poor prognosis and drug resistance. Let-7 is a family of tumor suppressor microRNAs that are frequently suppressed in solid tumors, where KRAS mutations are highly prevalent. In this study, we investigated the potential use of let-7 as a chemosensitizer. We found that let-7b repletion selectively sensitized KRAS mutant tumor cells to the cytotoxicity of paclitaxel and gemcitabine. Transfection of let-7b mimic downregulated the expression of mutant but not wild-type KRAS. Combination of let-7b mimic with paclitaxel or gemcitabine diminished MEK/ERK and PI3K/AKT signaling concurrently, triggered the onset of apoptosis, and reverted the epithelial-mesenchymal transition in KRAS mutant tumor cells. In addition, let-7b repletion downregulated the expression of β-tubulin III and ribonucleotide reductase subunit M2, two proteins known to mediate tumor resistance to paclitaxel and gemcitabine, respectively. Let-7 may represent a new class of chemosensitizer for the treatment of KRAS mutant tumors.

High-mobility-group A2 overexpression provokes a poor prognosis of gastric cancer through the epithelial-mesenchymal transition

Tumor metastases are the ultimate target in cancer therapy. In epithelial malignancies, the expression of high-mobility-group A2 (HMGA2) is associated with disease progression and the epithelial-mesenchymal transition (EMT), which is involved in the metastatic process. The present study assessed the clinical and molecular effects of HMGA2 with the malignant tissues of 170 patients with gastric cancer and gastric cancer cells expressing HMGA2. HMGA2 expression was determined using immunohistochemistry and analyzed with respect to the clinicopathological data of patients with this tumor. In the gastric cancer cell line MKN28, in which HMGA2 was knocked down by two different short-hairpin RNAs, Transwell migration and invasion assays were conducted and western blotting was used to detect the altered expression of EMT markers. In patients with gastric cancer, HMGA2 overexpression correlated with tumor progression and was indicative of a significantly worse overall survival. Migration and invasion assays using HMGA2-knocked down MKN28 cells showed a reduction in cell migration and invasion. The upregulation of E-cadherin, an epithelial marker, and the downregulation of N-cadherin, a mesenchymal marker were observed in HMGA2-knocked down cells. In addition, expression of the transcriptional factors Snail and Zeb1 and of the EMT-pathway molecule β-catenin were decreased. HMGA2 overexpression, through its relationship to EMT, thus seems to aggravate invasion and metastasis in gastric cancer. It may therefore serve as a predictive marker in determining the clinical outcome of patients with gastric cancer and offer a promising therapeutic target.

Coexpression of HMGA2 and Oct4 predicts an unfavorable prognosis in human gastric cancer

High mobility group protein A2 (HMGA2) and octamer-binding transcription factor 4 (Oct4) are transcription factors that play major roles in the acquisition of cancer stemness phenotypes and tumorigenicity of malignant neoplasms. The aim of this study was to analyze the association between HMGA2 and Oct4 expression and various clinicopathologic features in gastric cancer patients including invasion, metastasis, and clinical prognosis, in addition to overall survival. Immunohistochemistry was performed to explore the expression of HMGA2 and Oct4 in 158 gastric cancer and surrounding non-tumor tissues. Moreover, HMGA2 and Oct4 mRNA and protein levels were also detected by qRT-PCR and Western blotting, respectively, in 86 clinical tissue specimens and various gastric epithelial cell lines (GES-1, SGC7901, MKN45, and MKN27). Finally, associations between HMGA2 and Oct4 expression and clinicopathological features were analyzed by Pearson correlation coefficient. Survival analysis was performed by univariate and multivariate analyses. Taken together, we found that HMGA2 and Oct4 expression was significantly higher in gastric cancer tissues compared with non-cancerous tissues (P < 0.01), and HMGA2 and Oct4 protein levels were significantly higher in poorly differentiated gastric cancer cell lines (MKN45), moderately differentiated cell lines (SGC7901), and well-differentiated cell lines (MKN28) compared with human immortalized gastric epithelial cell lines (GES-1) (P < 0.01). Elevated HMGA2 and Oct4 levels were significantly associated with poor clinical prognosis (P < 0.05). Further conclusion showed that coexpression of HMGA2 and Oct4 in gastric cancer correlated with tumor invasion, metastasis, and clinical prognosis and predicted an unfavorable clinical outcome. These transcription factors may represent useful biomarkers to identify patients at high risk of postoperative recurrence.

Pancreatic stellate cells and CX3CR1: occurrence in normal pancreas and acute and chronic pancreatitis and effect of their activation by a CX3CR1 agonist

OBJECTIVES

Numerous studies suggest important roles of the chemokine, fractalkine (CX3CL1), in acute/chronic pancreatitis; however, the possible mechanisms of the effects are unclear. Pancreatic stellate cells (PSCs) can play important roles in pancreatitis, secreting inflammatory cytokines/chemokines, as well as proliferation. Therefore, we investigated CX3CL1 receptor (CX3CR1) occurrence in normal pancreas and pancreatitis (acute/chronic) tissues and the effects of CX3CL1 on activated PSCs.

METHODS

CX3CR1 expression/localization in normal pancreas and pancreatitis (acute/chronic) tissues was evaluated with immunohistochemical analysis. CX3CR1 expression and effects of CX3CL1 on activated PSCs were examined with real-time polymerase chain reaction, BrdU (5-bromo-2-deoxyuridine) assays, and Western blotting.

RESULTS

In normal pancreas, acinar cells expressed CX3CR1 within granule-like formations in the cytoplasm, whereas in acute/chronic pancreatitis, acinar, ductal, and activated PSCs expressed CX3CR1 on cell membranes. With activation of normal PSCs, CX3CR1 is increased. CX3CL1 activated multiple signaling cascades in PSCs. CX3CL1 did not induce inflammatory genes expression in activated PSCs, but induced proliferation.

CONCLUSIONS

CX3CR1s are expressed in normal pancreas. Expression is increased in acute/chronic pancreatitis, and the CX3CR1s are activated. CX3CL1 induces proliferation of activated PSCs without increasing release of inflammatory mediators. These results suggest that CX3CR1 activation of PSCs could be important in their effects in pancreatitis, especially to PSC proliferation in pancreatitis where CX3CL1 levels are elevated.

Generation and characterisation of a canine EGFP-HMGA2 prostate cancer in vitro model

The architectural transcription factor HMGA2 is abundantly expressed during embryonic development. In several malignant neoplasias including prostate cancer, high re-expression of HMGA2 is correlated with malignancy and poor prognosis. The let-7 miRNA family is described to regulate HMGA2 negatively. The balance of let-7 and HMGA2 is discussed to play a major role in tumour aetiology. To further analyse the role of HMGA2 in prostate cancer a stable and highly reproducible in vitro model system is precondition. Herein we established a canine CT1258-EGFP-HMGA2 prostate cancer cell line stably overexpressing HMGA2 linked to EGFP and in addition the reference cell line CT1258-EGFP expressing solely EGFP to exclude EGFP-induced effects. Both recombinant cell lines were characterised by fluorescence microscopy, flow cytometry and immunocytochemistry. The proliferative effect of ectopically overexpressed HMGA2 was determined via BrdU assays. Comparative karyotyping of the derived and the initial CT1258 cell lines was performed to analyse chromosome consistency. The impact of the ectopic HMGA2 expression on its regulator let-7a was analysed by quantitative real-time PCR. Fluorescence microscopy and immunocytochemistry detected successful expression of the EGFP-HMGA2 fusion protein exclusively accumulating in the nucleus. Gene expression analyses confirmed HMGA2 overexpression in CT1258-EGFP-HMGA2 in comparison to CT1258-EGFP and native cells. Significantly higher let-7a expression levels were found in CT1258-EGFP-HMGA2 and CT1258-EGFP. The BrdU assays detected an increased proliferation of CT1258-HMGA2-EGFP cells compared to CT1258-EGFP and native CT1258. The cytogenetic analyses of CT1258-EGFP and CT1258-EGFP-HMGA2 resulted in a comparable hyperdiploid karyotype as described for native CT1258 cells. To further investigate the impact of recombinant overexpressed HMGA2 on CT1258 cells, other selected targets described to underlie HMGA2 regulation were screened in addition. The new fluorescent CT1258-EGFP-HMGA2 cell line is a stable tool enabling in vitro and in vivo analyses of the HMGA2-mediated effects on cells and the development and pathogenesis of prostate cancer.

Chaperoning HMGA2 protein protects stalled replication forks in stem and cancer cells

Maintaining genome integrity requires the accurate and complete replication of chromosomal DNA. This is of the utmost importance for embryonic stem cells (ESCs), which differentiate into cells of all lineages, including germ cells. However, endogenous and exogenous factors frequently induce stalling of replication forks in every cell cycle, which can trigger mutations and chromosomal instabilities. We show here that the oncofetal, nonhistone chromatin factor HMGA2 equips cells with a highly effective first-line defense mechanism against endonucleolytic collapse of stalled forks. This fork-stabilizing function most likely employs scaffold formation at branched DNA via multiple DNA-binding domains. Moreover, HMGA2 works independently of other human factors in two heterologous cell systems to prevent DNA strand breaks. This fork chaperone function seemingly evolved to preserve ESC genome integrity. It is hijacked by tumor (stem) cells to also guard their genomes against DNA-damaging agents widely used to treat cancer patients.

Tumours of the lacrimal gland. Epidemiological, clinical and genetic characteristics

Tumours of the lacrimal gland are rare, but the prognosis may be grave. To date, no population-based incidence and distribution data on lacrimal gland tumours exist. In addition, almost nothing is known about the genetic profile of epithelial tumours of the lacrimal gland. We collected specimens and clinical files on all biopsied lacrimal gland lesions in Denmark over a 34-year period and re-evaluated the diagnosis to provide updated population-based incidence rates and epidemiological characteristics. Clinical data regarding symptoms, clinical examinations, treatment and follow-up were collected for patients with adenoid cystic carcinoma (ACC), pleomorphic adenoma (PA), carcinoma ex pleomorphic adenoma (Ca-ex-PA) and mucoepidermoid carcinoma (MEC). Using RT-PCR, FISH, immunohistochemistry, Q-PCR and high-resolution array-based comparative genomic hybridization (arrayCGH) we explored the genetic characteristics including copy number alterations (CNA) in ACC, PA, Ca-ex-PA and MEC. The incidence of biopsied lacrimal gland lesions was 1.3/1,000,000/year, and ~50% were neoplastic lesions. Of these, 55% were malignant tumours with epithelial tumours as the most frequent. The overall incidence was increasing, and this was caused by an increase in biopsied non-neoplastic lesions. We found that 10/14 ACCs either expressed the MYB-NFIB fusion gene and/or had rearrangements of MYB. All ACCs expressed the MYB protein. ACC was characterized by recurrent copy number losses involving 6q, 12q and 17q and gains involving 19q, 8q and 11q. ArrayCGH revealed an apparently normal genomic profile in 11/19 PAs. The remaining 8 PAs had recurrent copy number losses involving 1p, 6q, 8q and 13q and gain involving 9p. PA expressed PLAG1 in all tumours whereas only 2/29 tumours expressed HMGA2. Ca-ex-PA was characterized by recurrent copy number gain involving 22q. PLAG1 was expressed in 3/5 Ca-ex-PA whereas none of these tumours expressed HMGA2. MEC expressed the CRTC1-MAML2, and this fusion was found to be tumour-specific for lacrimal gland MEC. In conclusion, lacrimal gland lesions that require pathological evaluation are rare in the Danish population, and the incidence rate of biopsied benign lesions is increasing. Epithelial tumours of the lacrimal gland are molecularly very similar to their salivary gland counterparts in the expression of the tumour-specific fusion genes and in their genomic imbalances as demonstrated by arrayCGH. MYB-NFIB is a useful biomarker for ACC and MYB, and its downstream target genes may be potential therapeutic targets for these tumours.

HMGA2/TET1/HOXA9 signaling pathway regulates breast cancer growth and metastasis

The ten-eleven translocation (TET) family of methylcytosine dioxygenases initiates demethylation of DNA and is associated with tumorigenesis in many cancers; however, the mechanism is mostly unknown. Here we identify upstream activators and downstream effectors of TET1 in breast cancer using human breast cancer cells and a genetically engineered mouse model. We show that depleting the architectural transcription factor high mobility group AT-hook 2 (HMGA2) induces TET1. TET1 binds and demethylates its own promoter and the promoter of homeobox A (HOXA) genes, enhancing its own expression and stimulating expression of HOXA genes including HOXA7 and HOXA9. Both TET1 and HOXA9 suppress breast tumor growth and metastasis in mouse xenografts. The genes comprising the HMGA2-TET1-HOXA9 pathway are coordinately regulated in breast cancer and together encompass a prognostic signature for patient survival. These results implicate the HMGA2-TET1-HOX signaling pathway in the epigenetic regulation of human breast cancer and highlight the importance of targeting methylation in specific subpopulations as a potential therapeutic strategy.