Elevated HMGA2 expression is associated with cancer aggressiveness and predicts poor outcome in breast cancer

Circular RNAs as a novel molecular mechanism in diagnosis, prognosis, therapeutic target, and inhibiting chemoresistance in breast cancer

Breast cancer (BC) is the most common cancer among women, characterized by significant heterogeneity. Diagnosis of the disease in the early stages and appropriate treatment plays a crucial role for these patients. Despite the available treatments, many patients due to drug resistance do not receive proper treatments. Recently, circular RNAs (circRNAs), a type of non-coding RNAs (ncRNAs), have been discovered to be involved in the progression and resistance to drugs in BC. CircRNAs can promote or inhibit malignant cells by their function. Numerous circRNAs have been discovered to be involved in the proliferation, invasion, and migration of tumor cells, as well as the progression, pathogenesis, tumor metastasis, and drug resistance of BC. Circular RNAs can also serve as a biomarker for diagnosing, predicting prognosis, and targeting therapy. In this review, we present an outline of the variations in circRNAs expression in various BCs, the functional pathways, their impact on the condition, and their uses in clinical applications.

Decoding high mobility group A2 protein expression regulation and implications in human cancers

High Mobility Group A2 (HMGA2) oncofetal proteins are a distinct category of Transcription Factors (TFs) known as "architectural factors" due to their lack of direct transcriptional activity. Instead, they modulate the three-dimensional structure of chromatin by binding to AT-rich regions in the minor grooves of DNA through their AT-hooks. This binding allows HMGA2 to interact with other proteins and different regions of DNA, thereby regulating the expression of numerous genes involved in carcinogenesis. Consequently, multiple mechanisms exist to finely control HMGA2 protein expression at various transcriptional levels, ensuring precise concentration adjustments to maintain cellular homeostasis. During embryonic development, HMGA2 protein is highly expressed but becomes absent in adult tissues. However, recent studies have revealed its re-elevation in various cancer types. Extensive research has demonstrated the involvement of HMGA2 protein in carcinogenesis at multiple levels. It intervenes in crucial processes such as cell cycle regulation, apoptosis, angiogenesis, epithelial-to-mesenchymal transition, cancer cell stemness, and DNA damage repair mechanisms, ultimately promoting cancer cell survival. This comprehensive review provides insights into the HMGA2 protein, spanning from the genetic regulation to functional protein behavior. It highlights the significant mechanisms governing HMGA2 gene expression and elucidates the molecular roles of HMGA2 in the carcinogenesis process.

The emerging role and mechanism of HMGA2 in breast cancer

High mobility group AT-hook 2 (HMGA2) is a member of the non-histone chromosomal high mobility group (HMG) protein family, which participate in embryonic development and other biological processes. HMGA2 overexpression is associated with breast cancer (BC) cell growth, proliferation, metastasis, and drug resistance. Furthermore, HMGA2 expression is positively associated with poor prognosis of patients with BC, and inhibiting HMGA2 signaling can stimulate BC cell progression and metastasis. In this review, we focus on HMGA2 expression changes in BC tissues and multiple BC cell lines. Wnt/β-catenin, STAT3, CNN6, and TRAIL-R2 proteins are upstream mediators of HMGA2 that can induce BC invasion and metastasis. Moreover, microRNAs (miRNAs) can suppress BC cell growth, invasion, and metastasis by inhibiting HMGA2 expression. Furthermore, long noncoding RNAs (LncRNAs) and circular RNAs (CircRNAs) mainly regulate HMGA2 mRNA and protein expression levels by sponging miRNAs, thereby promoting BC development. Additionally, certain small molecule inhibitors can suppress BC drug resistance by reducing HMGA2 expression. Finally, we summarize findings demonstrating that HMGA2 siRNA and HMGA2 siRNA-loaded nanoliposomes can suppress BC progression and metastasis.

HMGA2 promotes cancer metastasis by regulating epithelial-mesenchymal transition

Epithelial-mesenchymal transition (EMT) is a complex physiological process that transforms polarized epithelial cells into moving mesenchymal cells. Dysfunction of EMT promotes the invasion and metastasis of cancer. The architectural transcription factor high mobility group AT-hook 2 (HMGA2) is highly overexpressed in various types of cancer (e.g., colorectal cancer, liver cancer, breast cancer, uterine leiomyomas) and significantly correlated with poor survival rates. Evidence indicated that HMGA2 overexpression markedly decreased the expression of epithelial marker E-cadherin (CDH1) and increased that of vimentin (VIM), Snail, N-cadherin (CDH2), and zinc finger E-box binding homeobox 1 (ZEB1) by targeting the transforming growth factor beta/SMAD (TGFβ/SMAD), mitogen-activated protein kinase (MAPK), and WNT/beta-catenin (WNT/β-catenin) signaling pathways. Furthermore, a new class of non-coding RNAs (miRNAs, circular RNAs, and long non-coding RNAs) plays an essential role in the process of HMGA2-induced metastasis and invasion of cancer by accelerating the EMT process. In this review, we discuss alterations in the expression of HMGA2 in various types of cancer. Furthermore, we highlight the role of HMGA2-induced EMT in promoting tumor growth, migration, and invasion. More importantly, we discuss extensively the mechanism through which HMGA2 regulates the EMT process and invasion in most cancers, including signaling pathways and the interacting RNA signaling axis. Thus, the elucidation of molecular mechanisms that underlie the effects of HMGA2 on cancer invasion and patient survival by mediating EMT may offer new therapeutic methods for preventing cancer progression.

The FGFR inhibitor PD173074 binds to the C-terminus of oncofetal HMGA2 and modulates its DNA-binding and transcriptional activation functions

The architectural chromatin factor high-mobility group AT-hook 2 (HMGA2) is causally involved in several human malignancies and pathologies. HMGA2 is not expressed in most normal adult somatic cells, which renders the protein an attractive drug target. An established cell-based compound library screen identified the fibroblast growth factor receptor (FGFR) inhibitor PD173074 as an antagonist of HMGA2-mediated transcriptional reporter gene activation. We determined that PD173074 binds the C-terminus of HMGA2 and interferes with functional coordination of the three AT-hook DNA-binding domains mediated by the C-terminus. The HMGA2-antagonistic effect of PD173074 on transcriptional activation may therefore result from an induced altered DNA-binding mode of HMGA2. PD173074 as a novel HMGA2-specific antagonist could trigger the development of derivates with enhanced attributes and clinical potential.

Non-coding RNAs and exosomal non-coding RNAs in pituitary adenoma

Pituitary adenoma (PA) is the third most common primary intracranial tumor in terms of overall disease incidence. Although they are benign tumors, they can have a variety of clinical symptoms, but are mostly asymptomatic, which often leads to diagnosis at an advanced stage when surgical intervention is ineffective. Earlier identification of PA could reduce morbidity and allow better clinical management of the affected patients. Non-coding RNAs (ncRNAs) do not generally code for proteins, but can modulate biological processes at the post-transcriptional level through a variety of molecular mechanisms. An increased number of ncRNA expression profiles have been found in PAs. Therefore, understanding the expression patterns of different ncRNAs could be a promising method for developing non-invasive biomarkers. This review summarizes the expression patterns of dysregulated ncRNAs (microRNAs, long non-coding RNAs, and circular RNAs) involved in PA, which could one day serve as innovative biomarkers or therapeutic targets for the treatment of this neoplasia. We also discuss the potential molecular pathways by which the dysregulated ncRNAs could cause PA and affect its progression.

HMGA2 regulation by miRNAs in cancer: affecting cancer hallmarks and therapy response

High mobility group A 2 (HMGA2) is a protein that modulates the structure of chromatin in the nucleus. Importantly, aberrant expression of HMGA2 occurs during carcinogenesis, and this protein is an upstream mediator of cancer hallmarks including evasion of apoptosis, proliferation, invasion, metastasis, and therapy resistance. HMGA2 targets critical signaling pathways such as Wnt/β-catenin and mTOR in cancer cells. Therefore, suppression of HMGA2 function notably decreases cancer progression and improves outcome in patients. As HMGA2 is mainly oncogenic, targeting expression by non-coding RNAs (ncRNAs) is crucial to take into consideration since it affects HMGA2 function. MicroRNAs (miRNAs) belong to ncRNAs and are master regulators of vital cell processes, which affect all aspects of cancer hallmarks. Long ncRNAs (lncRNAs) and circular RNAs (circRNAs), other members of ncRNAs, are upstream mediators of miRNAs. The current review intends to discuss the importance of the miRNA/HMGA2 axis in modulation of various types of cancer, and mentions lncRNAs and circRNAs, which regulate this axis as upstream mediators. Finally, we discuss the effect of miRNAs and HMGA2 interactions on the response of cancer cells to therapy. Regarding the critical role of HMGA2 in regulation of critical signaling pathways in cancer cells, and considering the confirmed interaction between HMGA2 and one of the master regulators of cancer, miRNAs, targeting miRNA/HMGA2 axis in cancer therapy is promising and this could be the subject of future clinical trial experiments.

Has_circ_0048764 promotes breast cancer progression by sponging miR-578 and regulating HMGA2 expression

BACKGROUND

Circular RNAs (circRNAs) function as important regulators in the progression of cancers. The role of circRNA_0048764 (circ_0048764) in the development of breast cancer (BC) remains inconclusive. This work investigates the biological function and molecular mechanism of circ_0048764 in BC.

METHODS

Quantitative real-time PCR (qRT-PCR) was conducted to measure the expression levels of circ_0048764, microRNA-578 (miR-578) and high mobility group AT-hook 2 (HMGA2) mRNA. The viability of BC cells was examined by cell counting kit 8 (CCK-8) assay. Besides, cyclin D1, proliferating cell nuclear antigen (PCNA) and HMGA2 expression levels were detected by western blot. The migrative and invasive capability of BC cells were probed by transwell assay. The relationships between miR-578 and circ_0048764 or HMGA2 3'-UTR were validated by dual-luciferase reporter gene assay.

RESULTS

Circ_0048764 was highly expressed in BC tissues and cells, which was significantly associated with tumor size (≥2 cm), lymph node status (positive), and higher TNM stage of BC patients. Circ_0048764 depletion suppressed the proliferative, migrative, and invasive abilities of BC cells, which was rescued by transfection of miR-578 inhibitors. The binding sites were verified between circ_0048764 and miR-578. HMGA2 was identified to be a target of miR-578 in BC cells, and circ_0048764 positively regulated HMGA2 expression in BC cells via repressing miR-578.

CONCLUSION

Circ_0048764 promotes BC cell growth, migration and invasion via absorbing miR-578 and up-regulating HMGA2.

miR-219-5p attenuates cisplatin resistance of ovarian cancer by inactivating Wnt/β-catenin signaling and autophagy via targeting HMGA2

Our previous study confirmed that miR-219-5p inhibits the progression of ovarian cancer (OC) by targeting high mobility group AT-hook 2 (HMGA2), while the role of miR-219-5p on the chemoresistance of OC is unclear. HMGA2 and miR-219-5p expression in OC tumors and various types of OC cells were determined by reverse transcription-quantitative PCR (RT-qPCR) and western blotting. The miRNA profiles in A2780 and cisplatin-resistant A2780 cells were investigated via bulk miRNA sequencing, and the interactions of miR-219-5p and HMGA2 were determined by luciferase reporter activity assay. Cell function was verified through Cell Counting Kit-8, invasion assay, wound-healing, and TUNEL assays. HMGA2 level is highly expressed in cisplatin-resistant OC cell lines compared to normal OC cells, while the expression trend of miR-219-5p is the opposite. In addition, we found that miR-219-5p is one of the miRNAs that have the most significant reduction in levels in the cisplatin-resistant A2780/DDP cell line compared to A2780 cells. Then, we reveal that miR-219-5p directly targets HMGA2 in cisplatin-resistant OC cells, and upregulation of miR-219-5p significantly reduces the resistance of OC cells to cisplatin both in vitro and in vivo. Finally, our results suggest that Wnt/β-catenin signaling and autophagy pathway is involved in the role of miR-219-5p/HMGA2 on resistance of OC cells to cisplatin via gain-of-function experiments. Collectively, the present study shows that miR-219-5p decreases the resistance of OC cells to cisplatin via Wnt/β-catenin signaling and autophagy by regulating HMGA2, which provides a feasible solution for the resistance of OC to chemotherapy.

The proteasome activator REGγ promotes diabetic endothelial impairment by inhibiting HMGA2-GLUT1 pathway

Diabetic vascular endothelial impairment is one of the main causes of death in patients with diabetes lacking adequately defined mechanisms or effective treatments. REGγ, the 11S proteasome activator known to promote the degradation of cellular proteins in a ubiquitin- and ATP-independent manner, emerges as a new regulator in the cardiovascular system. Here, we found that REGγ was upregulated in streptozocin (STZ)-induced diabetic mouse aortic endothelium in vivo and high glucose (HG)-treated vascular endothelial cells (ECs) in vitro. REGγ deficiency ameliorated endothelial impairment in STZ-induced diabetic mice by protecting against a decline in cellular glucose uptake and associated vascular ECs dysfunction by suppressing high mobility group AT-hook 2 (HMGA2) decay. Mechanically, REGγ interacted with and degraded the transcription factor HMGA2 directly, leading to decreased HMGA2 transcriptional activity, subsequently lowered expression of glucose transporter type 1 (GLUT1), and reduced cellular glucose uptake, vascular endothelial dysfunction, and impaired diabetic endothelium. Ablation of endogenous GLUT1 or HMGA2 or overexpressing exogenous HMGA2 in vascular ECs significantly blocked or reestablished the REGγ-dependent action on cellular glucose uptake and vascular endothelial functions of HG stimulation in vitro. Furthermore, exogenously introducing HMGA2 improved diabetic mice endothelial impairment features caused by REGγ in vivo, thereby substantiating a REGγ-HMGA2-GLUT1 pathway in diabetic endothelial impairment. Our findings indicate that modulating REGγ-proteasome activity may be a potential therapeutic approach for diabetic disorders with endothelial impairment.

HMGA2-Snai2 axis regulates tumorigenicity and stemness of head and neck squamous cell carcinoma

Cancer stem cells (CSCs) are a tumorigenic cell subpopulation, which contributes to treatment resistance, tumor recurrence, and metastasis. This study aimed to investigate the role and underlying molecular targets of high mobility group AT-hook 2 (HMGA2) in the progression and CSCs regulation of head and neck squamous cell carcinoma (HNSCC). HMGA2 mRNA and protein expression levels were examined in HNSCC specimens and cells by qRT-PCR, Western blot, and immunohistochemistry. The roles of HMGA2 were validated via loss-of-function and exogenous overexpression experiments in vitro and in vivo, and CSCs properties were assessed by tumorsphere formation assay. Chromatin immunoprecipitation (ChIP) and luciferase reporter assays provided further insight into the molecular mechanisms by which HMGA2 regulates stemness. HMGA2 was abnormally overexpressed in HNSCC, and it promoted the expression of the CSCs markers including SOX2, CD133, CD44, ALDH1A1, and Bmi1. HMGA2 was correlated with stemness, malignant progression, and reduced survival in HNSCC. Luciferase reporter assay indicated that Snai2 was a direct downstream target gene of HMGA2. Mechanistically, ChIP-qPCR assay showed that HMGA2 was recruited to three binding sites on the Snai2 promoter, directly facilitating the transcription of Snai2 in HNSCC. Snai2 overexpression reversed the inhibitory effect of HMGA2 interference on the proliferation, invasion, and metastasis of HNSCC and CSC marker expression in vitro and in vivo. HMGA2 promoted the malignant progression of HNSCC and acquired CSCs properties through direct regulation of Snai2, thereby suggesting that targeting the HMGA2-Snai2 axis might be a promising therapeutic strategy for HNSCC.

LncRNA SNHG1 promotes renal cell carcinoma progression through regulation of HMGA2 via sponging miR-103a

BACKGROUND

Long noncoding RNAs (LncRNAs) plays a vital role in tumorigenesis and development. The molecular mechanism of SNHG1 in renal cell carcinoma (RCC) has not been illustrated. The aim of this research was to explore the expression and function of LncRNA SNHG1 in RCC.

MATERIAL AND METHODS

The expression of SNHG1 in clinical tissues and RCC cell lines was detected. Luciferase reporter assay was performed to verify the correlation between SNHG1, miR-103a, and HMGA2. CCK-8 assay was performed to examine cell viability. Cell apoptosis was analyzed using flow cytometry. Cell invasion capacity was determined by Transwell assays. The protein level of HMGA2 was analyzed by Western blotting.

RESULTS

The expression of SNHG1 markedly increased in RCC tissues and cell lines. Subsequent studies identified SNHG1 as a miRNA sponge for miR-103a. In addition, SNHG1 knockdown and miR-103a overexpression significantly inhibited progression of RCC. miR-103a also regulated HMGA2 levels.

CONCLUSION

Our findings showed that SNHG1 was upregulated in RCC cells and tissues. SNHG1 promoted the malignant characteristics of RCC cells. Its regulatory effect may be regulation of HMGA2 by sponging miR-103a. Therefore, Our study facilitates the understanding of SNHG1 function in RCC.

Mechanisms of cancer stem cells drug resistance and the pivotal role of HMGA2

Nowadays, the focus of researchers is on perceiving the heterogeneity observed in a tumor. The researchers studied the role of a specific subset of cancer cells with high resistance to traditional treatments, recurrence, and unregulated metastasis. This small population of tumor cells that have stem-cell-like specifications was named Cancer Stem Cells (CSCs). The unique features that distinguish this type of cancer cell are self-renewing, generating clones of the tumor, plasticity, recurrence, and resistance to therapies. There are various mechanisms that contribute to the drug resistance of CSCs, such as CSCs markers, Epithelial mesenchymal transition, hypoxia, other cells, inflammation, and signaling pathways. Recent investigations have revealed the primary role of HMGA2 in the development and invasion of cancer cells. Importantly, HMGA2 also plays a key role in resistance to treatment through their function in the drug resistance mechanisms of CSCs and challenge it. Therefore, a deep understanding of this issue can provide a clearer perspective for researchers in the face of this problem.

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.

HMGA2 rs968697 T > C polymorphism is associated with the risk of colorectal cancer

A genetic polymorphism (rs968697 T > C) in the HMGA2 gene has recently been linked to an increased risk of hepatoblastoma. However, no studies have been conducted to investigate the effect of the polymorphism on the risk of colorectal cancer (CRC). The study aimed to explore whether the rs968697 polymorphism had a significant impact on CRC risk. A total of 500 CRC patients and 500 age and gender matched healthy individuals were genotyped by using the SNaPshot method. Quantitative real-time PCR technology was used to detect the relative expression of the HMGA2 gene in 30 pairs of primary CRC and adjacent non-cancerous tissues. Results: HMGA2 rs968697 polymorphism was significantly associated with CRC risk [CC vs. TT: OR = 0.20, 95%CI = 0.06-0.70, P = 0.01; (CC + CT) vs. TT: OR = 0.71, 95%CI = 0.53-0.96, P = 0.02; CC vs. (CT + TT): OR = 0.21, 95%CI = 0.06-0.73, P = 0.01; C vs. T: OR = 0.67, 95%CI = 0.51-0.89, P < 0.01]. The analysis based on tumor stage indicated that the CRC patients with HMGA2 rs968697 C allele were less likely to have high-stage tumors. Furthermore, the genotype-tissue expression analysis revealed that the rs968697 CC genotype was linked to the low expression of HMGA2 gene. The in silico analysis revealed that the rs968697 polymorphism in the promoter region of the HMGA2 gene could influence transcription factor binding, including ATF6, DBP, CDPCR3, DR3, NRSF, PAX8, PPARA, SZF11, TAXCREB and POLR2A. In conclusion, our findings suggested that the HMGA2 rs968697 polymorphism was linked to CRC risk and could be used as a biomarker to detect CRC risk.

ER-α36 Promotes the Malignant Progression of Cervical Cancer Mediated by Estrogen via HMGA2

Objectives

Estrogen is proven to promote the malignant behaviors of many cancers via its receptors. Estrogen receptor alfa 36 (ER-α36) is a newly identified isoform of estrogen receptor alfa (ER-α), the role of ER-α36 in regulating the effects of estrogen and its potential impact on human cervical cancer is poorly understood.

Methods

Immunohistochemistry staining was used to evaluate the expression of ER-α36, estrogen receptor alfa 66 (ER-α66) and their prognostic values in cervical cancer. The effects of ER-α36 and ER-α66 on the proliferation and metastasis of cervical cancer were measured in vitro. A xenograft tumor assay was used to study the tumorigenesis role of ER-α36 in vivo. Furthermore, the functional gene at the downstream of ER-α36 was obtained via next-generation sequencing, and the biological functions of high mobility group A2 (HMGA2) in cervical cancer cells were investigated in vitro.

Results

ER-α36 was over-expressed in cervical cancer tissues and elevated ER-α36 expression was associated with poor prognosis in cervical cancer patients. High expression of ER-α36 promoted the proliferation, invasion and metastasis of cervical cancer cells mediated by estrogen, while silencing ER-α36 had the opposite effects. Further research showed that HMGA2 was a downstream target of ER-α36 in cervical cancer cells. The oncogenic effect of ER-α36 was attenuated after HMGA2 knockdown.

Conclusions

High expression of ER-α36 was correlated with a poor prognosis in cervical cancer by regulating HMGA2. ER-α36 could be a prognostic biomarker and a target for cervical cancer treatment.

HMGA2 as a Critical Regulator in Cancer Development

The high mobility group protein 2 (HMGA2) regulates gene expression by binding to AT-rich regions of DNA. Akin to other DNA architectural proteins, HMGA2 is highly expressed in embryonic stem cells during embryogenesis, while its expression is more limited at later stages of development and in adulthood. Importantly, HMGA2 is re-expressed in nearly all human malignancies, where it promotes tumorigenesis by multiple mechanisms. HMGA2 increases cancer cell proliferation by promoting cell cycle entry and inhibition of apoptosis. In addition, HMGA2 influences different DNA repair mechanisms and promotes epithelial-to-mesenchymal transition by activating signaling via the MAPK/ERK, TGFβ/Smad, PI3K/AKT/mTOR, NFkB, and STAT3 pathways. Moreover, HMGA2 supports a cancer stem cell phenotype and renders cancer cells resistant to chemotherapeutic agents. In this review, we discuss these oncogenic roles of HMGA2 in different types of cancers and propose that HMGA2 may be used for cancer diagnostic, prognostic, and therapeutic purposes.

MiR-590 Suppresses Proliferation and Induces Apoptosis in Pancreatic Cancer by Targeting High Mobility Group A2

BACKGROUND

Pancreatic ductal adenocarcinoma is a common malignancy with high morbidity. MicroRNAs have been demonstrated to be critical posttranscriptional regulators in tumorigenesis. This study aimed to investigate the effect of microRNA-590 on the proliferation and apoptosis of pancreatic ductal adenocarcinoma.

MATERIAL AND METHODS

The expression of microRNA-590 and high mobility group AT-hook 2 were examined in clinical pancreatic ductal adenocarcinoma tissues. Pancreatic ductal adenocarcinoma cell line Capan-2 was employed and transfected with microRNA-590 mimics or inhibitor. The correlation between microRNA-590 and high mobility group AT-hook 2 was verified by luciferase reporter assay. Cell viability and apoptosis were detected by MTT and flow cytometry assay. The protein level of high mobility group AT-hook 2, AKT, p-AKT, mTOR, and phosphorylated mTOR were analyzed by Western blotting.

RESULTS

MicroRNA-590 was found to be negatively correlated with the expression of high mobility group AT-hook 2 in pancreatic ductal adenocarcinoma tissues. Further studies identified high mobility group AT-hook 2 as a direct target of microRNA-590. Moreover, overexpression of microRNA-590 downregulated expression of high mobility group AT-hook 2, reduced cell viability, and promoted cell apoptosis, while knockdown of miR-590 led to an inverse result. MicroRNA-590 also suppressed the phosphorylation of AKT and mTOR without altering total AKT and mTOR levels.

CONCLUSION

Our study indicated that microRNA-590 negatively regulates the expression of high mobility group AT-hook 2 in clinical specimens and in vitro. MicroRNA-590 can inhibit cell proliferation and induce cell apoptosis in pancreatic ductal adenocarcinoma cells. This regulatory effect of microRNA-590 may be associated with AKT signaling pathway. Therefore, microRNA-590 has the potential to be used as a biomarker for predicting the progression of pancreatic ductal adenocarcinoma.

The pro-migration and anti-apoptosis effects of HMGA2 in HUVECs stimulated by hypoxia

High-mobility group AT-hook2 (HMGA2), serving as an architectural transcription factor, participates in plenty of biological processes. Our study is aimed at illustrating the effect of HMGA2 on hypoxia-induced HUVEC injury and the underlying mechanism. To induce hypoxia-related cell injury, HUVECs were exposed to hypoxic condition for 12-24 h. Molecular expression was determined by Western blot analysis, real-time PCR and immunofluorescence staining. Cell migration was monitored by wound healing assay and Transwell chamber assay. Cell proliferation and apoptosis were measured by MTT assay kits and TUNEL staining. In this study, we discovered that HMGA2 was upregulated in hypoxia-induced HUVECs. Overexpression of HMGA2 promoted cell migration, decreased the apoptosis ratio in response to hypoxia stimulation, while HMGA2 knockdown inhibited cell migration and accelerated apoptosis in HUVECs under hypoxic condition. Mechanistically, we found that HMGA2 induced increased expression of HIF-1α,VEGF, eNOS and AKT. eNOS knockdown significantly reduced HMGA2-mediated pro-migration effects, and AKT knockdown strikingly counteracted HMGA2-mediated anti-apoptotic effect. Hence, our data indicated that HMGA2 promoted cell migration by regulating HIF-1α/VGEF/eNOS signaling and prevented cell apoptosis by activating HIF-1α/VGEF/AKT signaling in HUVECs.

Long Noncoding RNA LINC02163 Accelerates Malignant Tumor Behaviors in Breast Cancer by Regulating the MicroRNA-511-3p/HMGA2 Axis

Long intergenic nonprotein-coding RNA 02163 (LINC02163) has been reported to be upregulated and work as an oncogene in gastric cancer. The aims of the present study were to determine the expression profile and clinical value of LINC02163 in breast cancer. Additionally, the detailed functions of LINC02163 in breast cancer were explored, and relevant molecular events were elucidated. In this study, LINC02163 was upregulated in breast cancer, and its expression level was closely associated with tumor size, lymph node metastasis, and TNM stage. Patients with breast cancer presenting high LINC02163 expression exhibited shorter overall survival than those presenting low LINC02163 expression. Knockdown of LINC02163 resulted in a decrease in breast cancer cell proliferation, migration, and invasion and an increase in cell apoptosis in vitro. In addition, silencing of LINC02163 impeded breast cancer tumor growth in vivo. Mechanistic investigation revealed that LINC02163 served as a competing endogenous RNA for microRNA-511-3p (miR-511-3p) and consequently upregulated the expression of the high-mobility group A2 (HMGA2), a downstream target of miR-511-3p. Intriguingly, miR-511-3p inhibition and HMGA2 restoration counteracted the effects of LINC02163 deficiency on the malignant properties of breast cancer cells. LINC02163 exerts cancer-promoting effects during the initiation and progression of breast cancer via regulation of the miR-511-3p/HMGA2 axis. Our findings add to our understanding of the roles of the LINC02163/miR-511-3p/HMGA2 pathway as a regulator of breast cancer pathogenesis and may be useful in the development of lncRNA-directed cancer diagnosis, prognosis, and therapy.

Emerging roles for HMGA2 in colorectal cancer

HMGA2 (High Mobility Group AT-hook 2) has been reported to promote colorectal cancer (CRC) development by regulating the transcription of target genes. It participates in nearly all aspects of cellular processes, including cell transformation, proliferation, apoptosis, senescence, metastasis, epithelial-to-mesenchymal transition (EMT), DNA repair and stem cell self-renewal. In the past decades, a group of downstream targets and binding partners have been identified in a wide range of cancers. Our findings of HMGA2 as a key factor in the MDM2/p53, IL11/STAT3 and Wnt/β-catenin signaling pathways prompt us to summarize current advances in the functional and molecular basis of HMGA2 in CRC. In this review, we address the roles of HMGA2 in the oncogenic networks of CRC based on recent advances. We review its aberrant expression, explore underlying mechanisms, discuss its pro-tumorigenic effects, and highlight promising small-molecule inhibitors based on targeting HMGA2 here. However, the understanding of HMGA2 in CRC progression is still elusive, thus we also discuss the future perspectives in this review. Collectively, this review provides novel insights into the oncogenic properties of HMGA2, which has potential implications in the diagnosis and treatment of CRC.

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HMGA2 promotes colorectal cancer (CRC) development by regulating the transcriptions of target genes.

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Circulating cell-free HMGA2 mRNA has been identified as a potential screening marker in CRC.

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HMGA2 appears to be a key factor in the networks of MDM2/p53, IL11/STAT3 and Wnt/β-catenin signaling pathways in CRC.

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Many agents and siRNAs serve as potential therapeutic approaches by targeting HMGA2 for the treatment of CRC.

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Deciphering HMGA2-mediated machinery helps to conceive effective therapy strategies and develop novel inhibitors in CRC.

Significance of HMGA2 expression as independent poor prognostic marker in perihilar and distal cholangiocarcinoma resected with curative intent

BACKGROUND

Extrahepatic cholangiocarcinoma requires invasive surgery and is associated with poor prognosis; thus, a prognostic biomarker is highly needed. Extrahepatic cholangiocarcinoma is sub-classified into two types based on their location, namely perihilar and distal. Perihilar cholangiocarcinoma requires lobectomy as curative surgical resection, whereas the distal requires pancreatoduodenectomy. HMGA2 overexpression is reported to correlate with progression, aggressiveness, dissemination and poor prognosis in several types of cancers. Although its association with extrahepatic cholangiocarcinoma has been reported, none of the previous studies assessed its significance in each subtype.

METHODS

We assessed the expression of HMGA2 protein in surgical specimens after curative intent surgery in 80 patients including 41 with perihilar cholangiocarcinoma and 39 with distal cholangiocarcinoma by immunohistochemistry. We then examined its association with clinicopathological findings and patient survival outcomes.

RESULTS

We found that HMGA2 was expressed in 51% (21 of 41) of perihilar cholangiocarcinoma and 41% (16 of 39) of distal cholangiocarcinoma samples. In perihilar cholangiocarcinoma, we found significant correlations between expression and vascular invasion and perineural invasion. In distal cholangiocarcinoma, we found that protein levels correlated with tumor grade. Univariate and multivariate analyses demonstrated that HMGA2 expression was an independent poor prognostic factor for patients with both subtypes of disease.

CONCLUSIONS

Our results revealed that HMGA2 expression as an independent prognostic marker for both perihilar and distal cholangiocarcinoma that were resected with curative intent.

A novel role of Krüppel-like factor 8 as an apoptosis repressor in hepatocellular carcinoma

Background

Krüppel-like factor 8 (KLF8), a cancer-promoting factor that regulates critical gene transcription and cellular cancer-related events, has been implicated in tumor development and progression. However, the functional role of KLF8 in the pathogenesis of hepatocellular carcinoma (HCC) remains largely unknown.

Methods

The gene expression patterns and genome-wide regulatory profiles of HCC cells after KLF8 knockout were analyzed by using RNA sequencing (RNA-seq) and chromatin immunoprecipitation sequencing (ChIP-seq) of histone H3 lysine 27 acetylation (H3K27ac) combined with bioinformatics analysis. Transcription factor-binding motifs that recognized by KLF8 were evaluated by motif analysis. For the predicted target genes, transcriptional changes were examined by ChIP, and loss of function experiments were conducted by siRNA transfection.

Results

KLF8 functioned as a transcription repressor in HCC and mainly regulated apoptotic-related genes directly. A total of 1,816 differentially expressed genes after KLF8 knockout were identified and significantly corresponded to global changes in H3K27ac status. Furthermore, two predicted target genes, high-mobility group AT-hook 2 (HMGA2) and matrix metalloproteinase 7 (MMP7), were identified as important participants in KLF8-mediated anti-apoptotic effect in HCC. Knockout of KLF8 enhanced cell apoptosis process and caused increase in the associated H3K27ac, whereas suppression HMGA2 or MMP7 attenuated these biological effects.

Conclusions

Our work suggests a novel role and mechanism for KLF8 in the regulation of cell apoptosis in HCC and facilitates the discovery of potential therapeutic targets for HCC treatment.

Gene Set Analysis: Challenges, Opportunities, and Future Research

Gene set analysis methods are widely used to provide insight into high-throughput gene expression data. There are many gene set analysis methods available. These methods rely on various assumptions and have different requirements, strengths and weaknesses. In this paper, we classify gene set analysis methods based on their components, describe the underlying requirements and assumptions for each class, and provide directions for future research in developing and evaluating gene set analysis methods.

Alterations in TGF-β signaling leads to high HMGA2 levels potentially through modulation of PJA1/SMAD3 in HCC cells

Recently, we observed that the TGF-β pathway is altered in 39% of HCCs. The alterations are correlated with a raised HMGA2 level. Therefore, we compared genetic alterations of HMGA2 and 43 TGF-β pathway core genes in HCC patients from TCGA database. Genetic alterations of 15 genes, including INHBE, INHBC, GDF11, ACVRL and TGFB2 out of 43 core genes, highly-moderately matched that of HMGA2. Co-occurrences of mutation amplification, gains, deletions and high/low mRNA of HMGA2 with those of the core genes were highly significant in INHBE, INHBC, ACVR1B, ACVRL and GDF11. Mass spectrometry studies revealed that HMGA2 interacted with an E3 ligase, PJA1, and that this interaction is enhanced by TGF-β treatment in the nuclear of HCC cells. Co-localization of nuclear PJA1 and HMGA2 in HCC cells increased upon TGF-β treatment. Raised HMGA2 levels that occur with alterations in the TGF-β signaling pathway may reflect an altered activity of E3 ligases, such as PJA1, and potentially contribute to the tumor-promoting roles of TGF-β signaling. Here, we report that the co-occurrence of genetic alterations in HMGA2 and TGF-β pathway core genes is implicated in HCC progression, and propose that HMGA2 and PJA1 may be potential novel targets in dysfunctional TGF-β signaling in HCC.

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.

MALAT1 knockdown inhibits hypopharyngeal squamous cell carcinoma malignancy by targeting microRNA-194

Metastasis-associated lung adenocarcinoma transcript 1 (MALAT1) is involved in the oncogenesis and progression of various types of cancer. However, the function of MALAT1 in hypopharyngeal squamous cell carcinoma (HSCC) is not completely understood. In the present study, MALAT1 expression levels were determined using reverse transcription-quantitative PCR, and Cell Counting Kit-8, Transwell and flow cytometry assays were performed to investigate the biological functions of HSCC cells. The results indicated that MALAT1 was upregulated in HSCC. MALAT1 knockdown suppressed HSCC cell proliferation, migration and invasion, and promoted apoptosis compared with the control group. Additionally, microRNA (miR)-194 was identified as a target of MALAT1 and was expressed at low levels in HSCC tissues compared with adjacent non-tumor tissues. A miR-194 agomir inhibited malignant cell behaviors, including cell proliferation, migration and invasion, whereas miR-194 antagomir promoted malignant behaviors compared with the corresponding control groups. In addition, the results suggested that MALAT1 knockdown inhibited the malignant behaviors of HSCC cells by binding miR-194. miR-194 inhibition partially reversed the MALAT1 knockdown-induced inhibitory effects on HSCC cells. Furthermore, MALAT1 knockdown combined with miR194 mimics resulted in the lowest tumor volume among all tested groups in vivo. In conclusion, the results of the present study suggested that MALAT1 knockdown suppressed the malignant behavior of HSCC by targeting miR-194; therefore, MALAT1 may serve as a novel therapeutic target for HSCC.

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.

Cullin 3 overexpression inhibits lung cancer metastasis and is associated with survival of lung adenocarcinoma

Cullin 3 (CUL3), a molecular scaffold of Cullin-RING ubiquitin ligase, plays an important role in regulating biological processes through modulating the ubiquitylation and degradation of various protein substrates. Dysfunction of CUL3 is implicated in the development of several human diseases. However, the clinical significance and prognostic value of CUL3 in lung cancer have not been investigated. This study investigated the CUL3-modulating potential of non-small cell lung cancer cell lines, H1299, H358, H2170 and H520, by using immunoblotting, MTT, migration, invasion, colony formation and in vivo tumorigenicity assays. The prognostic significance of CUL3 was measured by public KM plotter database (http://kmplot.com/analysis/index.php?p=service&cancer=breast) and tissue immunohistochemistry analysis. The public online database analysis revealed that elevated mRNA expression of CUL3 was associated with better prognosis for non-small cell lung cancer and lung adenocarcinoma. In vitro experiments showed that ectopic overexpression of CUL3 significantly inhibited lung adenocarcinoma cell proliferation and migration, and the tumor-suppressive effect of CUL3 was dependent on the Nrf2/RhoA axis. In vivo mice model demonstrated that overexpression of CUL3 lead to a significant reduction of lung adenocarcinoma growth and metastasis. Importantly, tissue immunohistochemistry analysis showed that about 47% of non-small cell lung cancer tissues were expressed of CUL3 at high levels. Overexpression of CUL3 predicted favorable overall survival in non-small cell lung cancer patients, especially in lung adenocarcinoma, but not in lung squamous cell carcinoma patients. CUL3 could serve as a prognostic biomarker for lung adenocarcinoma. Loss of CUL3 might be driving tumorigenesis by activating the Nrf2/RhoA pathway.

Downregulation of lncRNA HOTTIP Suppresses the Proliferation, Migration, and Invasion of Oral Tongue Squamous Cell Carcinoma by Regulation of HMGA2-Mediated Wnt/β-Catenin Pathway

Background: Oral tongue squamous cell carcinoma (OTSCC) is a common type of oral tumor. LncRNAs (long noncoding RNAs) and miRNAs (microRNAs) were identified as regulators in many human cancers. This study aims to explore the molecular basis of HOXA transcript at the distal tip (HOTTIP) in regulating OTSCC progression. Materials and Methods: The expression of HOTTIP, miR-124-3p, and high-mobility group AT-hook 2 (HMGA2) was detected by quantitative real-time polymerase chain reaction. Next, the proliferation was evaluated by 3-(4,5-dimethylthiazole-2-y1)-2,5-biphenyl tetrazolium bromide (MTT) assay. The migration and invasion were assessed by transwell assay. Furthermore, dual-luciferase reporter assay was performed to confirm the combination between HOTTIP and miR-124-3p, miR-124-3p, and HMGA2. Protein levels of HMGA2, β-catenin, c-Myc, and E-cadherin were examined by Western blot. The nude mice model was employed to test the tumor growth in vivo. Results: HOTTIP was upregulated in OTSCC tissues and cells, and was highly expressed in positive lymph node metastasis and late-stage OTSCC patients. Silencing HOTTIP impeded proliferation, migration, and invasion of OTSCC cells. Moreover, HOTTIP knockdown inhibited proliferation, migration, and invasion of OTSCC cells by targeting miR-124-3p. Besides, miR-124-3p targeted HMGA2 to block proliferation, migration, and invasion. HMGA2 could rescue the inhibitory effects of HOTTIP interference on proliferation, migration, and invasion. In addition, HMGA2 overexpression reversed the downregulation of β-catenin and c-Myc protein levels and upregulation of E-cadherin level affected by HOTTIP silencing. Finally, HOTTIP silencing repressed tumor growth and resulted in a great rise on miR-124-3p and E-cadherin expression and a distinct fall on HMGA2, β-catenin, and c-Myc protein levels. Conclusions: HOTTIP knockdown restrained proliferation, migration, and invasion of OTSCC cells by miR-124-3p/HMGA2 axis through Wnt/β-catenin pathway.

Gene Expression Signature-Based Approach Identifies Antifungal Drug Ciclopirox As a Novel Inhibitor of HMGA2 in Colorectal Cancer

Human high-mobility group A2 (HMGA2) encodes for a non-histone chromatin protein which influences a variety of biological processes, including the cell cycle process, apoptosis, the DNA damage repair process, and epithelial–mesenchymal transition. The accumulated evidence suggests that high expression of HMGA2 is related to tumor progression, poor prognosis, and a poor response to therapy. Thus, HMGA2 is an important molecular target for many types of malignancies. Our recent studies revealed the positive connections between heat shock protein 90 (Hsp90) and HMGA2 and that the Hsp90 inhibitor has therapeutic potential to inhibit HMGA2-triggered tumorigenesis. However, 43% of patients suffered visual disturbances in a phase I trial of the second-generation Hsp90 inhibitor, NVP-AUY922. To identify a specific inhibitor to target HMGA2, the Gene Expression Omnibus (GEO) database and the Library of Integrated Network-based Cellular Signatures (LINCS) L1000platform were both analyzed. We identified the approved small-molecule antifungal agent ciclopirox (CPX) as a novel potential inhibitor of HMGA2. In addition, CPX induces cytotoxicity of colorectal cancer (CRC) cells by induction of cell cycle arrest and apoptosis in vitro and in vivo through direct interaction with the AT-hook motif (a small DNA-binding protein motif) of HMGA2. In conclusion, this study is the first to report that CPX is a novel potential inhibitor of HMGA2 using a drug-repurposing approach, which can provide a potential therapeutic intervention in CRC patients.

miR-491 inhibits BGC-823 cell migration via targeting HMGA2

PURPOSE

miR-491 functions as a tumor suppressor in several types of cancer. However, its function and mechanism in gastric cancer proliferation and metastasis have not been well defined. The aim of this study was to explore the role and regulatory mechanism of miR-491 in cell proliferation and migration in gastric cancer.

METHODS

Quantitative reverse transcriptase-polymerase chain reaction (qRT-PCR) was used to detect the expression pattern of miR-491 in gastric cancer tissues. miR-491 overexpression vector, miR-491 inhibitor, and siHMGA2 were used; and MTT, wound healing, and transwell assays were employed to examine proliferation and migration for BGC-823 cells. A dual-luciferase reporter gene was used to measure the target relationship between miR-491 and HMGA2.

RESULTS

Most gastric cancer patients exhibit decreased miR-491 expression. miR-491 overexpression inhibited cell proliferation and migration, whereas miR-491 inhibitor treatment produced the opposite effect. Mechanistically, HMGA2 was identified as a direct target of miR-491. Moreover, HMGA2 knockdown inhibited cell proliferation and migration, which was similar to the effect of miR-491 overexpression. HMGA2 was decreased after transfection of the miR-491 vector and increased after transfection of the miR-491 inhibitor.

CONCLUSION

Our results suggest that miR-491 suppressed cell proliferation and cell motility in gastric cancer by targeting HMGA2. Silencing HMGA2 produced a similar effect to miR-491 overexpression on cell proliferation and migration. miR-491/HMGA2 signaling may be a potential therapeutic target for gastric cancer patients with decreased miR-491 expression.

The transcribed pseudogene RPSAP52 enhances the oncofetal HMGA2-IGF2BP2-RAS axis through LIN28B-dependent and independent let-7 inhibition

One largely unknown question in cell biology is the discrimination between inconsequential and functional transcriptional events with relevant regulatory functions. Here, we find that the oncofetal HMGA2 gene is aberrantly reexpressed in many tumor types together with its antisense transcribed pseudogene RPSAP52. RPSAP52 is abundantly present in the cytoplasm, where it interacts with the RNA binding protein IGF2BP2/IMP2, facilitating its binding to mRNA targets, promoting their translation by mediating their recruitment on polysomes and enhancing proliferative and self-renewal pathways. Notably, downregulation of RPSAP52 impairs the balance between the oncogene LIN28B and the tumor suppressor let-7 family of miRNAs, inhibits cellular proliferation and migration in vitro and slows down tumor growth in vivo. In addition, high levels of RPSAP52 in patient samples associate with a worse prognosis in sarcomas. Overall, we reveal the roles of a transcribed pseudogene that may display properties of an oncofetal master regulator in human cancers.

Oncofetal HMGA2 attenuates genotoxic damage induced by topoisomerase II target compounds through the regulation of local DNA topology

Rapidly dividing cells maintain chromatin supercoiling homeostasis via two specialized classes of enzymes, DNA topoisomerase type 1 and 2 (TOP1/2). Several important anticancer drugs perturb this homeostasis by targeting TOP1/2, thereby generating genotoxic DNA damage. Our recent studies indicated that the oncofetal chromatin structuring high‐mobility group AT‐hook 2 (HMGA2) protein plays an important role as a DNA replication fork chaperone in coping with DNA topological ramifications that occur during replication stress, both genomewide and at fragile sites such as subtelomeres. Intriguingly, a recent large‐scale clinical study identified HMGA2 expression as a sole predicting marker for relapse and poor clinical outcomes in 350 acute myeloid leukemia (AML) patients receiving combinatorial treatments that targeted TOP2 and replicative DNA synthesis. Here, we demonstrate that HMGA2 significantly enhanced the DNA supercoil relaxation activity of the drug target TOP2A and that this activator function is mechanistically linked to HMGA2's known ability to constrain DNA supercoils within highly compacted ternary complexes. Furthermore, we show that HMGA2 significantly reduced genotoxic DNA damage in each tested cancer cell model during treatment with the TOP2A poison etoposide or the catalytic TOP2A inhibitor merbarone. Taken together with the recent clinical data obtained with AML patients targeted with TOP2 poisons, our study suggests a novel mechanism of cancer chemoresistance toward combination therapies administering TOP2 poisons or inhibitors. We therefore strongly argue for the future implementation of trials of HMGA2 expression profiling to stratify patients before finalizing clinical treatment regimes.

Oncological role of HMGA2 (Review)

The high mobility group A2 (HMGA2) protein is a non‑histone architectural transcription factor that modulates the transcription of several genes by binding to AT‑rich sequences in the minor groove of B‑form DNA and alters the chromatin structure. As a result, HMGA2 influences a variety of biological processes, including the cell cycle process, DNA damage repair process, apoptosis, senescence, epithelial‑mesenchymal transition and telomere restoration. In addition, the overexpression of HMGA2 is a feature of malignancy, and its elevated expression in human cancer predicts the efficacy of certain chemotherapeutic agents. Accumulating evidence has suggested that the detection of HMGA2 can be used as a routine procedure in clinical tumour analysis.

Amplification of hsa-miR-191/425 locus promotes breast cancer proliferation and metastasis by targeting DICER1

The dysregulation of micro RNAs (miRNAs) is a crucial characteristic of human cancers. Herein, we observed frequent amplification of the MIR191/425 locus in breast cancer, which is correlated with poor survival outcome. We demonstrated that the miR-191/425 cluster binds the 3' untranslated region of the DICER1 transcript and posttranscriptionally represses DICER1 expression, thereby impairing global miRNAs biogenesis. Functionally, the forced expression of miR-191 or miR-425 stimulated the proliferation, survival, migration and invasion of breast cancer cells, whereas the inhibition of miR-191 or miR-425 suppressed these oncogenic behaviors of breast cancer cells, in a manner dependent on miR-191/425-mediated downregulation of DICER1. Furthermore, the miR-191/425 cluster promoted breast tumor growth, invasion and metastasis in vivo. The let-7 family of miRNAs was downregulated upon forced expression of miR-191 or miR-425, with a corresponding increase in the levels of let-7 target, high-mobility group AT-hook 2 (HMGA2). The forced expression of let-7 partially abrogated the miR-191/425-mediated oncogenic effects in breast cancer cells, suggestive of let-7 as a downstream effector of the miR-191/425-DICER1 axis. Collectively, we proposed that the inhibition of global miRNA processing, through miR-191/425-mediated downregulation of DICER1, promotes breast cancer progression.

Ca2+ and CACNA1H mediate targeted suppression of breast cancer brain metastasis by AM RF EMF

BACKGROUND

Brain metastases are a major cause of death in patients with metastatic breast cancer. While surgical resection and radiation therapy are effective treatment modalities, the majority of patients will succumb from disease progression. We have developed a novel therapy for brain metastases that delivers athermal radiofrequency electromagnetic fields that are amplitude-modulated at breast cancer specific frequencies (BCF).

METHODS

27.12 MHz amplitude-modulated BCF were administered to a patient with a breast cancer brain metastasis by placing a spoon-shaped antenna on the anterior part of the tongue for three one-hour treatments every day. In preclinical models, a BCF dose, equivalent to that delivered to the patient's brain, was administered to animals implanted with either brain metastasis patient derived xenografts (PDXs) or brain-tropic cell lines. We also examined the efficacy of combining radiation therapy with BCF treatment. Additionally, the mechanistic underpinnings associated with cancer inhibition was identified using an agnostic approach.

FINDINGS

Animal studies demonstrated a significant decrease in growth and metastases of brain-tropic cell lines. Moreover, BCF treatment of PDXs established from patients with brain metastases showed strong suppression of their growth ability. Importantly, BCF treatment led to significant and durable regression of brain metastasis of a patient with triple negative breast cancer. The tumour inhibitory effect was mediated by Ca²⁺ influx in cancer cells through CACNA1H T-type voltage-gated calcium channels, which, acting as the cellular antenna for BCF, activated CAMKII/p38 MAPK signalling and inhibited cancer stem cells through suppression of β-catenin/HMGA2 signalling. Furthermore, BCF treatment downregulated exosomal miR-1246 level, which in turn decreased angiogenesis in brain environment. Therefore, targeted growth inhibition of breast cancer metastases was achieved through CACNA1H.

INTERPRETATION

We demonstrate that BCF, as a single agent or in combination with radiation, is a novel treatment approach to the treatment of brain metastases. This paradigm shifting modality warrants further clinical trials for this unmet medical need.

Impact of high-mobility-group A2 overexpression on epithelial-mesenchymal transition in pancreatic cancer

Background: Tumor metastasis causes high mortality in patients with malignancies. In carcinomas, overexpression of high-mobility-group A2 (HMGA2) in cancer cells would lead to tumor development and epithelial to mesenchymal transition (EMT), promoting metastasis. This study evaluated HMGA2 overexpression for its effects on pancreatic cancer (PC).

Methods: HMGA2 protein levels were immunohistochemically assessed in human PC tissue specimens and evaluated for associations with patients’ clinicopathological findings. In human PC CAPAN 1 cells after HMGA2 expression was silenced or overexpressed, Transwell migration and invasion assays were performed, and EMT marker levels (E-cadherin, N-cadherin and Vimentin) were determined by immunoblot.

Results: HMGA2 and Vimentin were found in 43% and 45% of PC tissue samples, respectively, while E-cadherin was absent in 60%. HMGA2 expression, loss of E-cadherin and Vimentin expression were significantly associated with clinical stage, tumor differentiation and lymph node metastasis. More importantly, univariate and multivariate analysis demonstrated that HMGA2 expression is an independent prognostic factor for patients with pancreatic cancer. Meanwhile, HMGA2-silenced CAPAN 1 cells showed reduced migration and invasion ability while HMGA2-overexpressed CAPAN 1 cells showed increased migration and invasion ability. Increased E-cadherin (epithelial marker) and reduced N-cadherin and Vimentin (mesenchymal markers) were found in HMGA2-silenced cells, while reduced E-cadherin and increased N-cadherin and Vimentin were found in HMGA2-overexpressed cells. Furthermore, Snail and Zeb1 (transcriptional factors) were reduced in HMGA2-silenced cells and increased in HMGA2-overexpressed cells.

Conclusion: Our findings demonstrate that HMGA2 expression correlates with advanced tumor grades, lymph node metastasis and poor prognosis and may be a novel prognosis/therapeutic marker for PC.

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.

P53-induced miR-1249 inhibits tumor growth, metastasis, and angiogenesis by targeting VEGFA and HMGA2

MicroRNAs (miRNAs) are important class of functional regulators involved in human cancers development, including colorectal cancer (CRC). Exploring aberrantly expressed miRNAs may provide us with new insights into the initiation and development of CRC by functioning as oncogenes or tumor suppressors. The aim of our study is to discover the expression pattern of miR-1249 in CRC and investigate its clinical significance as well as biological role in CRC progression. In our study, we found that miR-1249 was markedly downregulated in CRC tissues and cell lines, and negatively related to pN stage, pM stage, TNM stage, and overall survival (OS). Moreover, we demonstrated that miR-1249 was a direct transcriptional target of P53 and revealed that P53-induced miR-1249 inhibited tumor growth, metastasis and angiogenesis in vitro and vivo. Additionally, we verified that miR-1249 suppressed CRC proliferation and angiogenesis by targeting VEGFA as well as inhibited CRC metastasis by targeting both VEGFA and HMGA2. Further studying showed that miR-1249 suppressed CRC cell proliferation, migration, invasion, and angiogenesis via VEGFA-mediated Akt/mTOR pathway as well as inhibited EMT process of CRC cells by targeting both VEGFA and HMGA2. Our study indicated that P53-induced miR-1249 may suppress CRC growth, metastasis and angiogenesis by targeting VEGFA and HMGA2, as well as regulate Akt/mTOR pathway and EMT process in the initiation and development of CRC. miR-1249 might be a novel the therapeutic candidate target in CRC treatment.

Effects of Notch signalling on the expression of SEMA3C, HMGA2, CXCL14, CXCR7, and CCL20 in breast cancer

Metastasis is the main reason for death in breast cancer. Understanding the molecular players in metastasis is crucial for diagnostic and therapeutic purposes. Notch signalling plays an oncogenic role in breast tumorigenesis and is involved in metastasis. Downstream mediators of Notch signalling in prometastatic processes are not yet fully discovered. Here we aimed to investigate whether Notch signalling regulates the expression of SEMA3C, HMGA2, CXCL14, CXCR7, and CCL20, which are involved in prometastatic processes, in breast cell lines. To this end, expression of the selected genes was analysed following Notch activation by overexpression of the Notch1 intracellular domain in the normal breast epithelial cell line MCF10A, and inhibition by silencing of the Notch transcriptional mediator RBPjκ in the breast cancer cell line MDA MB 231. SEMA3C and HMGA2 mRNA were decreased, while CXCL14 and CXCR7 mRNA were increased significantly in response to Notch activation in MCF10A cells. Notch inhibition in MDA MB 231 cells significantly decreased HMGA2 and CCL20 mRNA. Protein levels were not significantly altered by Notch modulation. In conclusion, we showed that Notch signalling regulates expression of SEMA3C, CXCL14, CCL20, CXCR7, and HMGA2, which are prominent candidate genes that might function downstream of Notch to induce prometastatic processes.

miR-16 regulates proliferation and apoptosis of pituitary adenoma cells by inhibiting HMGA2

Previous studies have revealed that elevated expression of high mobility group A2 (HMGA2) is closely associated with the occurrence of pituitary adenomas (PAs). The expression of microRNA (miR)-16 is deregulated in PA tissues. Bioinformatics analysis has demonstrated that there is a complementary region between seed region of miR-16 and 3'-untranslated region (3'-UTR) of HMGA2 gene. In the present study, it was investigated whether miR-16 may regulate the expression of HMGA2 and whether it is involved in the pathogenesis of PAs. A total of 52 patients with PAs were recruited. Normal brain tissues obtained from 12 patients with traumatic brain injury were used as controls. The association between miR-16 and HMGA2 was validated using dual-luciferase reporter gene assay. HP75 cells were cultured in vitro and divided into the following groups: miR control, miR-16 mimic, small interfering RNA (si)-negative control, si-HMGA2 and miR-16 mimic+si-HMGA2 groups. The expression of miR-16 and HMGA2 in HP75 cells was determined using qRT-PCR and western blot. Cell proliferation was detected using the Cell Counting Kit-8 assay and apoptosis was detected using the TdT-UTP nick end labeling assay. Compared with normal pituitary tissues, the expression of miR-16 in PA tissues was significantly decreased, while the mRNA and protein levels of HMGA2 were significantly increased. miR-16 targeted the 3'-UTR of HMGA2 gene and regulated the expression of HMGA2. Transfection with siRNAs targeting HMGA2 and/or miR-16 mimics inhibited the expression of HMGA2 and the proliferative ability of HP75 cells, whereas it increased apoptosis of HP75 cells. The downregulation of miR-16 and upregulation of HMGA2 were involved in the pathogenesis of PAs. Thus, it is hypothesized that miR-16 inhibited the proliferation and promoted apoptosis of HP75 cells by inhibiting HMGA2 expression.

Involvement of the long noncoding RNA NEAT1 in carcinogenesis

Altered expression levels of the long noncoding RNA (lncRNA) nuclear‐enriched abundant transcript 1 (NEAT1) have been reported in different types of cancer. More than half of the NEAT1 studies in cancer have been published within the last 2 years. In this review, we discuss very recent developments and insights into NEAT1 contribution to carcinogenesis. Summarizing the literature, it becomes obvious that NEAT1 is a lncRNA highly de‐/upregulated in a variety of cancer entities, in which it primarily acts as a competing endogenous RNA (ceRNA) which sponges tumor‐suppressive microRNA (miRNA). The sponged miRNA lose their ability to degrade, silence, or hamper translation of their downstream—mostly oncogenic—target transcripts, ultimately promoting carcinogenesis. This role of NEAT1 function in tumorigenesis suggests it may be a prognostic biomarker as well as potential therapeutic target, pending the completion of further studies into the underlying mechanisms.

MiR-219-5p inhibits growth and metastasis of ovarian cancer cells by targeting HMGA2

Background

Accumulating studies have demonstrated that high-mobility group A2 (HMGA2), an oncofetal protein, plays a role in tumor development and progression. However, the molecular role of HMGA2 in ovarian carcinoma is yet to be established. MicroRNAs (miRNAs), a group of small noncoding RNAs, negatively regulate gene expression and their dysregulation has been implicated in tumorigenesis. The aim of this study was to investigate the potential involvement of a specific miRNA, miR-219-5p, in HMGA2-induced ovarian cancer.

Methods

The ovarian cancer cell line, SKOV3, was employed, and miR-219-5p and HMGA2 overexpression vectors constructed. The CCK-8 kit was used to determine cell proliferation and the Transwell^® assay used to measure cell invasion and migration. RT-PCR and western blot analyses were applied to analyze the expression of miR-219-5p and HMGA2, and the luciferase reporter assay used to examine the interactions between miR-219-5p and HMGA2. Nude mice were employed to characterize in vivo tumor growth regulation.

Results

Expression of miR-219-5p led to suppression of proliferation, invasion and migration of the ovarian cancer cell line, SKOV3, by targeting HMGA2. The inhibitory effects of miR-219-5p were reversed upon overexpression of HMGA2. Data from the luciferase reporter assay showed that miR-219-5p downregulates HMGA2 via direct integration with its 3′-UTR. Consistent with in vitro findings, expression of miR-219-5p led to significant inhibition of tumor growth in vivo.

Conclusion

Our results collectively suggest that miR-219-5p inhibits tumor growth and metastasis by targeting HMGA2.

Roles of Tristetraprolin in Tumorigenesis

Genetic loss or mutations in tumor suppressor genes promote tumorigenesis. The prospective tumor suppressor tristetraprolin (TTP) has been shown to negatively regulate tumorigenesis through destabilizing the messenger RNAs of critical genes implicated in both tumor onset and tumor progression. Regulation of TTP has therefore emerged as an important issue in tumorigenesis. Similar to other tumor suppressors, TTP expression is frequently downregualted in various human cancers, and its low expression is correlated with poor prognosis. Additionally, disruption in the regulation of TTP by various mechanisms results in the inactivation of TTP protein or altered TTP expression. A recent study showing alleviation of Myc-driven lymphomagenesis by the forced expression of TTP has shed light on new therapeutic avenues for cancer prevention and treatment through the restoration of TTP expression. In this review, we summarize key oncogenes subjected to the TTP-mediated mRNA degradation, and discuss how dysregulation of TTP can contribute to tumorigenesis. In addition, the control mechanism underlying TTP expression at the posttranscriptional and posttranslational levels will be discussed.

A Pan-Cancer Analysis Reveals High-Frequency Genetic Alterations in Mediators of Signaling by the TGF-β Superfamily

We present an integromic analysis of gene alterations that modulate transforming growth factor β (TGF-β)-Smad-mediated signaling in 9,125 tumor samples across 33 cancer types in The Cancer Genome Atlas (TCGA). Focusing on genes that encode mediators and regulators of TGF-β signaling, we found at least one genomic alteration (mutation, homozygous deletion, or amplification) in 39% of samples, with highest frequencies in gastrointestinal cancers. We identified mutation hotspots in genes that encode TGF-β ligands (BMP5), receptors (TGFBR2, AVCR2A, and BMPR2), and Smads (SMAD2 and SMAD4). Alterations in the TGF-β superfamily correlated positively with expression of metastasis-associated genes and with decreased survival. Correlation analyses showed the contributions of mutation, amplification, deletion, DNA methylation, and miRNA expression to transcriptional activity of TGF-β signaling in each cancer type. This study provides a broad molecular perspective relevant for future functional and therapeutic studies of the diverse cancer pathways mediated by the TGF-β superfamily.

Overexpression of APC11 predicts worse survival in lung adenocarcinoma

Background

Anaphase-promoting complex subunit 11 (APC11) plays an important role in gathering E2 and catalyzing ubiquitin-chain formation to support ubiquitination of substrates by acting as a catalytic core subunit of anaphase-promoting complex (APC/C). However, whether APC11 is implicated in the tumorigenesis of lung cancer is never known.

Materials and methods

In this study, we used an online survival analysis software to estimate the prognostic value of APC11 mRNA expression level for lung cancer. Cell Counting Kit-8 assay, colony-forming assay, and transwell assay were used to assess the biological functions of APC11 in lung cancer cells. Then, 107 lung cancer patient tissues were collected to examine the expression level of APC11 by immunohistochemistry staining. Kaplan–Meier method and univariate Cox regression analysis were performed to reveal the prognostic value of APC11 protein expression in lung cancer.

Results

Higher mRNA level of APC11 was significantly associated with worse survival for lung adenocarcinoma, but not for lung squamous cell carcinoma. Knockdown of APC11 by siRNA apparently inhibited cell proliferation and colon formation in both H1299 and H358 cells. In addition, silencing of APC11 decreased cell migrative and invasive abilities. Moreover, immunohistochemical analysis showed that APC11 was highly expressed in lung cancer tissues, and multivariate analysis suggested that APC11 overexpression was an independent prognostic factor in lung adenocarcinoma.

Conclusion

We suggest that APC11 could serve as a prognostic biomarker and a novel target in treating lung adenocarcinoma.

CCN6 regulates IGF2BP2 and HMGA2 signaling in metaplastic carcinomas of the breast

PURPOSE

Metaplastic breast carcinomas are an aggressive subtype of triple-negative breast cancer (TNBC) in which part or all of the adenocarcinoma transforms into a non-glandular component (e.g., spindled, squamous, or heterologous). We discovered that mammary-specific Ccn6/Wisp3 knockout mice develop mammary carcinomas with spindle and squamous differentiation that share upregulation of the oncofetal proteins IGF2BP2 (IMP2) and HMGA2 with human metaplastic carcinomas. Here, we investigated the functional relationship between CCN6, IGF2BP2, and HMGA2 proteins in vitro and in vivo, and their expression in human tissue samples.

METHODS

MMTV-cre;Ccn6^fl/fl tumors and spindle TNBC cell lines were treated with recombinant CCN6 protein or vehicle. IGF2BP2 was downregulated using shRNAs in HME cells with stable CCN6 shRNA knockdown, and subjected to invasion and adhesion assays. Thirty-one human metaplastic carcinomas were arrayed in a tissue microarray (TMA) and immunostained for CCN6, IGF2BP2, and HMGA2.

RESULTS

CCN6 regulates IGF2BP2 and HMGA2 protein expression in MMTV-cre;Ccn6^fl/fl tumors, in MDA-MB-231 and - 468, and in HME cells. CCN6 recombinant protein reduced IGF2BP2 and HMGA2 protein expression, and decreased growth of MMTV-cre;Ccn6^fl/fl tumors in vivo. IGF2BP2 shRNA knockdown was sufficient to reverse the invasive abilities conferred by CCN6 knockdown in HME cells. Analyses of the TCGA Breast Cancer Cohort (n = 1238) showed that IGF2BP2 and HMGA2 are significantly upregulated in metaplastic carcinoma compared to other breast cancer subtypes. In clinical samples, low CCN6 is frequent in tumors with high IGF2BP2/HMGA2 with spindle and squamous differentiation.

CONCLUSIONS

These data shed light into the pathogenesis of metaplastic carcinoma and demonstrate a novel CCN6/IGF2BP2/HMGA2 oncogenic pathway with biomarker and therapeutic implications.