HMGA2 induces transcription factor Slug expression to promote epithelial-to-mesenchymal transition and contributes to colon cancer progression

Trichostatin A reverses epithelial-mesenchymal transition and attenuates invasion and migration in MCF-7 breast cancer cells

Breast cancer remains one of the leading causes of mortality in women, and epithelial-mesenchymal transition (EMT) serves an indispensable role in the invasion and migration of breast cancer cells. As a representative of classical histone deacetylase inhibitors (HDACIs), trichostatin A (TSA) has been demonstrated to reverse EMT in certain types of non-tumor cells and tumor cells. In the present study, the invasive and migratory abilities of MCF-7 cells were examined following treatment with TSA. TSA-induced changes in the expression of an epithelial biomarker epithelial cadherin (E-cadherin), a mesenchymal biomarker (vimentin), and a transcription factor [zinc finger protein SNAI2 (SLUG)] were also investigated. Transwell invasion and migration assays, and wound healing assays, revealed that the invasive and migratory abilities of MCF-7 cells were suppressed significantly upon treatment with TSA. Treatment with TSA led to an increased expression level of E-cadherin, and decreased expression of vimentin and, in MCF-7 cells. The overexpression of SLUG decreased the expression level of E-cadherin, but increased vimentin expression, and upon treatment with TSA, these effects were reversed. Additionally, SLUG knockdown also led to upregulation of E-cadherin expression, downregulation of vimentin expression, and suppression of the invasion and migration of MCF-7 cells. Taken together, these results suggest that TSA is able to reverse EMT via suppressing SLUG and attenuate the invasion and migration of MCF-7 cells in vitro, thereby providing a potential avenue for chemotherapeutic intervention in the treatment of breast cancer.

Molecular regulation of Snai2 in development and disease

The transcription factor Snai2, encoded by the SNAI2 gene, is an evolutionarily conserved C2H2 zinc finger protein that orchestrates biological processes critical to tissue development and tumorigenesis. Initially characterized as a prototypical epithelial-to-mesenchymal transition (EMT) transcription factor, Snai2 has been shown more recently to participate in a wider variety of biological processes, including tumor metastasis, stem and/or progenitor cell biology, cellular differentiation, vascular remodeling and DNA damage repair. The main role of Snai2 in controlling such processes involves facilitating the epigenetic regulation of transcriptional programs, and, as such, its dysregulation manifests in developmental defects, disruption of tissue homeostasis, and other disease conditions. Here, we discuss our current understanding of the molecular mechanisms regulating Snai2 expression, abundance and activity. In addition, we outline how these mechanisms contribute to disease phenotypes or how they may impact rational therapeutic targeting of Snai2 dysregulation in human disease.

MiR-26b Suppresses the Development of Stanford Type A Aortic Dissection by Regulating HMGA2 and TGF-β/Smad3 Signaling Pathway

Purpose: Stanford type A aortic dissection (TAAD) is one of the most dangerous cardiovascular diseases. MicroRNAs (miRNAs) have been considered as potential therapeutic targets for TAAD. In this present study, we aimed to investigate the functional role and regulatory mechanism of miR-26b in TAAD development.

Materials and Methods: MiR-26b mRNA expression was detected by real-time polymerase chain reaction (RT-PCR) and protein levels were measured by Western blot. Verifying the direct target of miR-26b was used by dual luciferase assay, RT-PCR, and Western blot. Cell Counting Kit-8 (CCK-8) and TUNEL staining assays were applied for detecting rat aortic vascular smooth muscle cells (VSMCs) viability and apoptosis, respectively.

Results: We found that miR-26b was under-expressed in TAAD patients and closely associated with the poor prognosis of TAAD patients. Re-expression of miR-26b facilitated while knockdown of miR-26b inhibited VSMC proliferation. However, miR-26b showed the opposite effect on cell apoptosis. More importantly, high-mobility group AT-hook 2 (HMGA2) was verified as the direct target of miR-26b. Furthermore, transforming growth factor beta (TGF-β)/Smad3 signaling pathway was involved in the development of TAAD modulated by miR-26b.

Conclusion: miR-26b impeded TAAD development by regulating HMGA2 and TGF-β/Smad3 signaling pathway, which provided a potential biomarker for TAAD treatment.

Kallikrein 6 protease advances colon tumorigenesis via induction of the high mobility group A2 protein

Kallikrein-related peptidase 6 (KLK6) overexpression is commonly observed in primary tumors of colorectal cancer (CRC) patients and has been associated with tumor aggressiveness, metastasis, and poor prognosis. We previously established a unique contribution of KLK6 in colon cancer metastasis via a specific network of microRNAs and mRNAs. Here we evaluated the cellular functions of KLK6 protease in Caco-2 colon adenocarcinoma cell line after introduction of the enzymatically active or inactive form of the enzyme. We found that proteolytically active KLK6 increased Caco-2 cells invasiveness in vitro and decreased the animal survival in the orthotopic colon cancer model. The active KLK6 induced phosphorylation of SMAD 2/3 proteins leading to the altered expression of the epithelial-mesenchymal transition (EMT) markers. KLK6 overexpression also induced the RNA-binding protein LIN28B and high-mobility group AT-hook 2 (HMGA2) transcription factor, two essential regulators of cell invasion and metastasis. In the CRC patients, KLK6 protein levels were elevated in the non-cancerous distant and adjacent tissues, compared to their paired tumor tissues (p < 0.0001 and p = 0.0157, respectively). Patients with mutant K-RAS tumors had significantly higher level of KLK6 protein in the luminal surface of non-cancerous distant tissue, compared to the corresponding tissues of the patients with K-RAS wild type tumors (p ≤ 0.05). Furthermore, KLK6 and HMGA2 immunohistochemistry (IHC) scores in patients' tumors and paired adjacent tissues positively correlated (Spearman correlation P < 0.01 and p = 0.03, respectively). These findings demonstrate the critical function of the KLK6 enzyme in colon cancer progression and its contribution to the signaling network in colon cancer.

N6-methyladenosine modification of circNSUN2 facilitates cytoplasmic export and stabilizes HMGA2 to promote colorectal liver metastasis

Circular RNAs (circRNAs) have been implicated in cancer progression through largely unknown mechanisms. Herein, we identify an N⁶-methyladenosine (m⁶A) modified circRNA, circNSUN2, frequently upregulated in tumor tissues and serum samples from colorectal carcinoma (CRC) patients with liver metastasis (LM) and predicts poorer patient survival. The upregulated expression of circNSUN2 promotes LM in PDX metastasis models in vivo and accelerates cancer cells invasion in vitro. Importantly, N⁶-methyladenosine modification of circNSUN2 increases export to the cytoplasm. By forming a circNSUN2/IGF2BP2/HMGA2 RNA-protein ternary complex in the cytoplasm, circNSUN2 enhances the stability of HMGA2 mRNA to promote CRC metastasis progression. Clinically, the upregulated expressions of circNSUN2 and HMGA2 are more prevalent in LM tissues than in primary CRC tissues. These findings elucidate that N⁶-methyladenosine modification of circNSUN2 modulates cytoplasmic export and stabilizes HMGA2 to promote CRC LM, and suggest that circNSUN2 could represent a critical prognostic marker and/or therapeutic target for the disease.

miR-330 suppresses EMT and induces apoptosis by downregulating HMGA2 in human colorectal cancer

MicroRNAs (miRNAs) are important molecular regulatorsof cellular signaling and behavior. They alter gene expression by targeting messenger RNAs, including those encoding transcriptional regulators, such as HMGA2. While HMGA2 is oncogenic in various tumors, miRNAs may be oncogenic or tumor suppressive. Here, we investigate the expression of HMGA2 and the miRNA miR-330 in a patient with colorectal cancer (CRC) samples and their effects on oncogenic cellular phenotypes. We found that HMGA2 expression is increased and miR-330 expression is decreased in CRCs and each predicts poor long-term patient survival. Stably increased miR-330 expression in human colorectal cancer cells (HCT116) and SW480 CRC cell lines downregulate the oncogenic expression of HMGA2, a predicted miR-330 target. Additionally, this promotes apoptosis and decreases cell migration and viability. Consistently, it also decreases protein-level expression of markers for epithelial-to-mesenchymal-transition (Snail-1, E-cadherin, and Vascular endothelial growth factor receptors) and transforming growth factor β signaling (SMAD3), as well as phospho- Protein kinase B (AKT) and phospho-STAT3 levels. We conclude that miR-330 acts as a tumor suppressor miRNA in CRC by suppressing HMGA2 expression and reducing cell survival, proliferation, and migration. Thus, we identify miR-330 as a promising candidate for miRNA replacement therapy for patients with CRC.

Extracellular-Signal Regulated Kinase: A Central Molecule Driving Epithelial-Mesenchymal Transition in Cancer

Epithelial-mesenchymal transition (EMT) is a reversible cellular process, characterized by changes in gene expression and activation of proteins, favoring the trans-differentiation of the epithelial phenotype to a mesenchymal phenotype. This process increases cell migration and invasion of tumor cells, progression of the cell cycle, and resistance to apoptosis and chemotherapy, all of which support tumor progression. One of the signaling pathways involved in tumor progression is the MAPK pathway. Within this family, the ERK subfamily of proteins is known for its contributions to EMT. The ERK subfamily is divided into typical (ERK 1/2/5), and atypical (ERK 3/4/7/8) members. These kinases are overexpressed and hyperactive in various types of cancer. They regulate diverse cellular processes such as proliferation, migration, metastasis, resistance to chemotherapy, and EMT. In this context, in vitro and in vivo assays, as well as studies in human patients, have shown that ERK favors the expression, function, and subcellular relocalization of various proteins that regulate EMT, thus promoting tumor progression. In this review, we discuss the mechanistic roles of the ERK subfamily members in EMT and tumor progression in diverse biological systems.

HMGA2 Contributes to Distant Metastasis and Poor Prognosis by Promoting Angiogenesis in Oral Squamous Cell Carcinoma

The highly malignant phenotype of oral squamous cell carcinoma (OSCC), including the presence of nodal and distant metastasis, reduces patient survival. High-mobility group A protein 2 (HMGA2) is a non-histone chromatin factor that is involved in advanced malignant phenotypes and poor prognosis in several human cancers. However, its biological role in OSCC remains to be elucidated. The purpose of this study was to determine the clinical significance and role of HMGA2 in the malignant potential of OSCC. We first investigated the expression pattern of HMGA2 and its clinical relevance in 110 OSCC specimens using immunohistochemical staining. In addition, we examined the effects HMGA2 on the regulation of vascular endothelial growth factor (VEGF)-A, VEGF-C, and fibroblast growth factor (FGF)-2, which are related to angiogenesis, in vitro. High expression of HMGA2 was significantly correlated with distant metastasis and poor prognosis. Further, HMGA2 depletion in OSCC cells reduced the expression of angiogenesis genes. In OSCC tissues with high HMGA2 expression, angiogenesis genes were increased and a high proportion of blood vessels was observed. These findings suggest that HMGA2 plays a significant role in the regulation of angiogenesis and might be a potential biomarker to predict distant metastasis and prognosis in OSCC.

Overexpression of HMGA1 Figures as a Potential Prognostic Factor in Endometrioid Endometrial Carcinoma (EEC)

Endometrioid endometrial carcinomas (EEC) are the most common malignant gynecologic tumors. Despite the increase in EEC molecular knowledge, the identification of new biomarkers involved in disease's development and/or progression would represent an improvement in its course. High-mobility group A protein (HMGA) family members are frequently overexpressed in a wide range of malignancies, correlating with a poor prognosis. Thus, the aim of this study was to analyze HMGA1 and HMGA2 expression pattern and their potential role as EEC biomarkers. HMGA1 and HMGA2 expression was initially evaluated in a series of 46 EEC tumors (stages IA to IV), and the findings were then validated in The Cancer Genome Atlas (TCGA) EEC cohort, comprising 381 EEC tumors (stages IA to IV). Our results reveal that HMGA1 and HMGA2 mRNA and protein are overexpressed in ECC, but only HMGA1 expression is associated with increased histological grade and tumor size. Moreover, HMGA1 but not HMGA2 overexpression was identified as a negative prognostic factor to EEC patients. Finally, a positive correlation between expression of HMGA1 pseudogenes-HMGA1-P6 and HMGA1-P7-and HMGA1 itself was detected, suggesting HMGA1 pseudogenes may play a role in HMGA1 expression regulation in EEC. Thus, these results indicate that HMGA1 overexpression possesses a potential role as a prognostic biomarker for EEC.

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.

HIT000218960 promotes gastric cancer cell proliferation and migration through upregulation of HMGA2 expression

The aim of the present study was to elucidate whether the long non-coding RNA (lncRNA) HIT000218960 could accelerate the proliferative and migratory ability of gastric cancer (GC) cells by regulating high-mobility group AT-hook 2 (HMGA2) gene. The reverse transcription-quantitative polymerase chain reaction was used to determine HIT000218960 and HMGA2 expression levels in GC tissues and cells. The HMGA2 protein level was detected by western blotting. A χ² test was used to determine the association between the HIT000218960 expression level and the clinical characteristics of patients with GC. GC cells were transfected with small interfering (si)-negative control, si-HIT000218960 and si-HIT000218960+pcDNA-HMGA2, prior to assessing the cell proliferative and migratory ability using the Cell Counting Kit-8 and Transwell assays, respectively. HIT000218960 and HMGA2 were highly expressed in GC tissues compared with in healthy tissues. In addition, HIT000218960 and HMGA2 were positively correlated in GC tissues. The HIT000218960 expression level was associated with tumor size, Tumor-Node-Metastasis staging and lymph node metastasis in patients with GC. HIT000218960 silencing decreased the proliferative and migratory ability of HGC27 and NCI-N87 cells; however, HMGA2 overexpression partly reversed this inhibitory effect. The results of the present study indicated that HIT000218960 could promote HGC27 and NCI-N87 cell proliferation and migration, which may be mediated by HMGA2.

HMGA2 and Bach-1 cooperate to promote breast cancer cell malignancy

During breast cancer progression, tumor cells acquire multiple malignant features. The transcription factors and cell cycle regulators high mobility group A2 (HMGA2) and BTB and CNC homology 1 (Bach-1) are overexpressed in several cancers, but the mechanistic understanding of how HMGA2 and Bach-1 promote cancer development has been limited. We found that HMGA2 and Bach-1 are overexpressed in breast cancer tissues and their expression correlates positively in tumors but not in normal tissues. Individual HMGA2 or Bach-1 knockdown downregulates expression of both proteins, suggesting a mutual stabilizing effect between the two proteins. Importantly, combined HMGA2 and Bach-1 knockdown additively decrease cell proliferation, migration, epithelial-to-mesenchymal transition, and colony formation, while promoting apoptotic cell death via upregulation of caspase-3 and caspase-9. First the first time, we show that HMGA2 and Bach-1 overexpression in tumors correlate positively and that the proteins cooperatively suppress a broad range of malignant cellular properties, such as proliferation, migration, clonogenicity, and evasion of apoptotic cell death. Thus, our observations suggest that combined targeting of HMGA2 and Bach1 may be an effective therapeutic strategy to treat breast cancer.

MnTE-2-PyP Attenuates TGF-β-Induced Epithelial-Mesenchymal Transition of Colorectal Cancer Cells by Inhibiting the Smad2/3 Signaling Pathway

Background

As a key step in enhancing cancer cell invasion and metastasis, epithelial-mesenchymal transition (EMT) plays an important role in colorectal cancer progression. EMT is triggered by a variety of signaling pathways, among which the transforming growth factor β (TGF-β) signaling pathway has been implicated as a primary inducer. Accumulating evidence demonstrates that MnTE-2-PyP (chemical name: manganese(III) meso-tetrakis-(N-ethylpyridinium-2-yl), a superoxide dismutase (SOD) mimetic, inhibits TGF-β signaling; however, its ability to inhibit TGF-β-induced EMT in colorectal cancer has not yet been explored.

Methods

To verify our hypothesis that MnTE-2-PyP attenuates TGF-β-induced EMT, human colorectal cancer cells were treated with TGF-β in the presence or absence of MnTE-2-PyP. Cells were analyzed by several techniques including western blotting, real-time quantitative PCR, transwell assay, and wound healing assay.

Results

MnTE-2-PyP reverses cell phenotypes induced by TGF-β in colon cancer cells. MnTE-2-PyP treatment significantly reduced the expression of mesenchymal markers but maintained epithelial marker expression. Mechanistically, MnTE-2-PyP suppressed the phosphorylated Smad2/3 protein levels induced by TGF-β in SW480 cells, but MnTE-2-PyP failed to suppress TGF-β-induced Slug and Snail expression in colorectal cells. Furthermore, MnTE-2-PyP effectively suppressed TGF-β-mediated cell migration and invasion and the expression of matrix metalloproteinase 2 (MMP-2) and matrix metalloproteinase 9 (MMP-9) in colorectal cells.

Conclusion

Taken together, we provide an in-depth mechanism by which MnTE-2-PyP inhibits colorectal cancer progression, supporting an important role for MnTE-2-PyP as an effective and innovative antitumor agent to enhance treatment outcomes in colorectal cancer.

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.

Epigenetic suppression of E-cadherin expression by Snail2 during the metastasis of colorectal cancer

Background

The transcription factor Snail2 is a repressor of E-cadherin expression during carcinogenesis; however, the specific mechanisms involved in this process in human colorectal cancer (CRC) remain largely unknown.

Method

We checked the expression of Snail2 in several clinical CRC specimens. Then, we established Snail2-overexpressing and knockdown cell lines to determine the function of Snail2 during EMT and metastasis processes in CRC. In addition, we used luciferase reporter assay to explore how Snail2 inhibits the expression of E-cadherin and induces EMT.

Results

We found that the expression of Snail2 was higher in clinical specimens of colorectal cancer (CRC) compared to non-cancerous tissues. Overexpression of Snail2 induced migration and metastatic properties in CRC cells in vitro and in vivo. Furthermore, overexpression of Snail2 promoted the occurrence of the epithelial–mesenchymal transition (EMT), downregulating the expression of E-cadherin and upregulating that of vimentin. Specifically, Snail2 could interact with HDAC6 and then recruited HDAC6 and PRC2 to the promoter of E-cadherin and thus inhibited the expression of E-cadherin, promoting EMT and inducing invasion and metastasis of CRC.

Conclusion

Our study reveals that Snail2 might epigenetically suppress the expression of E-cadherin during CRC metastasis.

Hepatitis B virus X protein promotes epithelial-mesenchymal transition and metastasis in hepatocellular carcinoma cell line HCCLM3 by targeting HMGA2

Chronic hepatitis B virus (HBV) infection is a major risk factor for hepatocellular carcinoma (HCC), and HBV X protein (HBx) serves an essential role in the development of HCC. However, its mechanism remains to be elucidated. The aim of the present study was to investigate the role and mechanism of the HBx protein in the epithelial-mesenchymal transition (EMT) and metastasis of HCC. The HCCLM3 cell line was transfected with a HBx-expressing vector. The effects of HBx overexpression on proliferation, migration, invasion and EMT capacities of the HCCLM3 cell line were evaluated using MTT, migration and invasion assays, and western blotting, respectively. Furthermore, the impact of High mobility group AT-hook 2 (HMGA2) knockdown on HBx-mediated metastasis was investigated in the HCC cell line HCCLM3. The results demonstrated that HBx significantly upregulated HMGA2 expression, and enhanced the proliferation, EMT, invasion and migration in HCC cells. Furthermore, HMGA2 knockdown almost abolished HBx-induced EMT and metastasis in HCC. The results of the present study suggest that HBx promotes the proliferation, EMT, invasion and migration of HCC cells by targeting HMGA2. HMGB2 may serve as a potential therapeutic target for HBV-associated HCC.

The Molecular Basis and Therapeutic Potential of Let-7 MicroRNAs against Colorectal Cancer

Although a number of studies have revealed the underlying mechanisms which regulate the development of colorectal cancer (CRC), we have not completely overcome this disease yet. Accumulating evidence has shown that the posttranscriptional regulation by the noncoding RNAs such as microRNAs plays an important role in the development or progression of CRC. Among a number of microRNAs, the let-7 microRNA family that was first discovered in C. elegans and conserved from worms to humans has been linked with the development of many types of cancers including CRC. The expression level of let-7 microRNAs is temporally low during the normal developmental processes, while elevated in the differentiated tissues. The let-7 microRNAs regulate the cell proliferation, cell cycle, apoptosis, metabolism, and stemness. In CRC, expressions of let-7 microRNAs have been reported to be reduced, and so let-7 microRNAs are considered to be a tumor suppressor. In this review, we discuss the mechanisms regulating the let-7 microRNA expression and the downstream targets of let-7 in the context of intestinal tumorigenesis. The application of let-7 mimics is also highlighted as a novel therapeutic agent.

miR-541 suppresses proliferation and invasion of squamous cell lung carcinoma cell lines via directly targeting high-mobility group AT-hook 2

An increasing number of studies have demonstrated that micro-ribonucleic acids (miRNAs) are important tumor suppressors during carcinogenesis. However, the function of miRNA-541 (miR-541) in malignancies, especially lung cancer, has not been widely reported. In this study, miR-541 expression was significantly decreased in squamous cell lung carcinoma (SCLC) cancerous tissue and SCLC cell lines. To analyze miR-541 function in SCLC, we overexpressed miR-541 in SCLC cell lines (SK-MES-1 and H226). According to the CCK8, wound scratch, and transwell invasion assay results, miR-541 overexpression significantly inhibited SCLC cell proliferation, migration, and invasion ability. Next, using RT-PCR, Western blotting, immunocytochemistry, and luciferase assays, HMGA2 was identified, for the first time, as a direct regulatory target of miR-541 in SK-MES-1 and H226 cells. Furthermore, upregulating HMGA2 expression significantly alleviated the suppressive effects of miR-541 on SK-MES-1 and H226 cell proliferation, migration, and invasion. In summary, our study revealed that miR-541 inhibited SCLC proliferation and invasion by directly targeting HMGA2.

LIN28B enhanced tumorigenesis in an autochthonous KRASG12V-driven lung carcinoma mouse model

LIN28B is a RNA-binding protein regulating predominantly let-7 microRNAs with essential functions in inflammation, wound healing, embryonic stem cells, and cancer. LIN28B expression is associated with tumor initiation, progression, resistance, and poor outcome in several solid cancers, including lung cancer. However, the functional role of LIN28B, especially in non-small cell lung adenocarcinomas, remains elusive. Here, we investigated the effects of LIN28B expression on lung tumorigenesis using LIN28B transgenic overexpression in an autochthonous KRAS^G12V-driven mouse model. We found that LIN28B overexpression significantly increased the number of CD44+/CD326+ tumor cells, upregulated VEGF-A and miR-21 and promoted tumor angiogenesis and epithelial-to-mesenchymal transition (EMT) accompanied by enhanced AKT phosphorylation and nuclear translocation of c-MYC. Moreover, LIN28B accelerated tumor initiation and enhanced proliferation which led to a shortened overall survival. In addition, we analyzed lung adenocarcinomas of the Cancer Genome Atlas (TCGA) and found LIN28B expression in 24% of KRAS-mutated cases, which underscore the relevance of our model.

Tetrac downregulates β-catenin and HMGA2 to promote the effect of resveratrol in colon cancer

The molecular pathogenesis of colorectal cancer encompasses the activation of several oncogenic signaling pathways that include the Wnt/β-catenin pathway and the overexpression of high mobility group protein A2 (HMGA2). Resveratrol - the polyphenolic phytoalexin - binds to integrin αvβ3 to induce apoptosis in cancer cells via cyclooxygenase 2 (COX-2) nuclear accumulation and p53-dependent apoptosis. Tetraiodothyroacetic acid (tetrac) is a de-aminated derivative of l-thyroxine (T₄), which - in contrast to the parental hormone - impairs cancer cell proliferation. In the current study, we found that tetrac promoted resveratrol-induced anti-proliferation in colon cancer cell lines, in primary cultures of colon cancer cells, and in vivo The mechanisms implicated in this action involved the downregulation of nuclear β-catenin and HMGA2, which are capable of compromising resveratrol-induced COX-2 nuclear translocation. Silencing of either β-catenin or HMGA2 promoted resveratrol-induced anti-proliferation and COX-2 nuclear accumulation which is essential for integrin αvβ3-mediated-resveratrol-induced apoptosis in cancer cells. Concurrently, tetrac enhanced nuclear abundance of chibby family member 1, the nuclear β-catenin antagonist, which may further compromise the nuclear β-catenin-dependent gene expression and proliferation. Taken together, these results suggest that tetrac targets β-catenin and HMGA2 to promote resveratrol-induced-anti-proliferation in colon cancers, highlighting its potential in anti-cancer combination therapy.

miR-186 affects the proliferation, invasion and migration of human gastric cancer by inhibition of Twist1

Recent evidence shows that miRNAs are dysregulated in a variety of cancers including gastric cancer (GC), and emerging as key oncogenes or tumor suppressors. In this study, qRT-PCR was used to analyze the expression of miR-186 in GC tissues and adjacent non-cancerous tissues, and then more in-vitro experiments were used to investigate the role of miR-186 in GC cells. Here, we identified miR-186 was generally down-regulated in GC tissues; however, Twist1 was generally up-regulated in GC tissues. Moreover, miR-186 and Twist1 were associated with larger tumor size and advanced clinical stage of GC. In-vitro experiments demonstrated that ectopic overexpression of miR-186 inhibited GC cell proliferation, invasion and migration; however, inhibited expression of miR-186 enhanced cell proliferation, invasion and migration. Furthermore, the luciferase reporter assay demonstrated Twist1 as a direct target of miR-186. Finally, over-expression of Twist1 abrogated inhibitory impact of miR-186 on cell proliferation, invasion and migration. In conclusion, miR-186 affects the proliferation, invasion and migration of human gastric cancer by inhibition of Twist1, and could be a tumor suppressor in GC development. Thus, miR-186 may be served as a candidate prognostic biomarker and target for new therapies in human gastric cancer.

miR‑539 suppresses proliferation and induces apoptosis in renal cell carcinoma by targeting high mobility group A2

Renal cell carcinoma (RCC) is one of the most common urinary malignancies with a high rate of morbidity. MicroRNAs (miRNAs) have been shown to be critical post-transcriptional regulators in tumorigenesis. The present study aimed to investigate the effect of miRNA (miR)-539 on the proliferation and apoptosis of RCC. The expression of miR-539 and high mobility group AT-hook 2(HMGA2) were examined in clinical RCC specimens. The 786-O RCC cell line was also used and was transfected with miR-539 mimics or inhibitors. The correlation between miR-539 and HMGA2 was confirmed using a luciferase reporter assay. Cell viability and apoptosis were detected using MTT and flow cytometry assays. The protein levels of HMGA2, AKT, phosphorylated (p)-AKT, mammalian target of rapamycin (mTOR) and p-mTOR were analyzed using western blot analysis. The results revealed that miR-539 was negatively correlated with the expression of HMGA2 in clinical RCC specimens. Further experiments identified HMGA2 as a direct target of miR-539. The overexpression of miR-539 downregulated the expression of HMGA2, reduced cell proliferation and promoted cell apoptosis, whereas the knockdown of miR-539 led to the opposite results. miR-539 also suppressed the phosphorylation of AKT and mTOR, without altering the levels of total AKT and mTOR. Taken together, the results of the present study indicated that miR-539 negatively regulated the expression of HMGA2 in clinical specimens and in vitro. miR539 inhibited cell proliferation and induced apoptosis in RCC cells. This regulatory effect of miR-539 may be associated with the AKT signaling pathway. Therefore, miR-539 may be used as a biomarker for predicting the progression of RCC.

Phosphohistone H3 (pHH3) is a prognostic and epithelial to mesenchymal transition marker in diffuse gliomas

The World Health Organization (WHO) grading of gliomas stratifies tumors by histology. However, the aggressiveness of tumors in each grade still shows great heterogeneity. Phosphohistone H3 (pHH3) has been reported as an accurate marker of cells within the mitotic phase of the cell cycle in many kinds of cancers. To evaluate the role of pHH3 in predicting patient outcome and to annotate the functions of pHH3 in WHO grade II-IV gliomas, we analyzed the expression pattern of pHH3 and pHH3 associated genes by IHC and mRNA expression profiling. Phosphohistone H3, mRNA enrichment of histone H3 and associated gene signature all showed prognostic value in adult diffuse gliomas. Gene set enrichment analysis suggested that the expression of pHH3 had positive correlation with both epithelial to mesenchymal transition and immune response. These findings suggest that subgroups of diffuse gliomas defined by pHH3 and pHH3 signatures possess distinctive prognostic and biological characteristics.

HMGA2 facilitates epithelial-mesenchymal transition in renal cell carcinoma by regulating the TGF-β/Smad2 signaling pathway

High-mobility group AT-hook 2 (HMGA2), a member of the high mobility group family, has been reported to correlate with cancer progression. However, there is no report concerning the correlation between HMGA2 and metastasis in renal cell carcinoma. In the present study, we found that HMGA2 was highly expressed in five renal cell carcinoma cell lines compared with that in the normal renal tubular epithelial HK2 cell line. Additionally, HMGA2 facilitated cell migration and invasion of renal cell carcinoma cells, as evidenced by wound healing and Transwell assays. Subsequently, our results revealed that the E-cadherin level was upregulated, while N-cadherin, Twist1 and Twist2 expression were downregulated in HMGA2-depleted ACHN cells. In contrast, overexpression of HMGA2 in 786-O cells enhanced epithelial-mesenchymal transition (EMT). In addition, analysis of the database Cancer Browser further validated the positive correlation between HGMA2 and Twist1 or Twist2 in renal cell carcinoma. Meanwhile, Kaplan-Meier analysis indicated that low HMGA2 expression was closely associated with an increased overall survival in renal cell carcinoma patients. To confirm the underlying mechanism of HMGA2-regulated EMT, our results revealed that silencing of HMGA2 downregulated the mRNA and protein levels of TGF-β and Smad2, while HMGA2 overexpression had the opposite effect. Furthermore, TGF-β overexpression could partially reverse the anti-metastatic effect and mesenchymal-epithelial transition (MET) by HMGA2 loss, while TGF-β deficiency impeded the pro-metastatic phenotype and high expression of EMT markers induced by HMGA2 overexpression. In summary, our results demonstrated that HMGA2 facilitated a metastatic phenotype and the EMT process in renal cell carcinoma cells in vitro through a TGF-β-dependent pathway. In addition, these data strongly suggest that HGMA2 may serve as a potential therapeutic target and prognostic biomarker against renal cell carcinoma in the future.

CR6-interacting factor 1 inhibits invasiveness by suppressing TGF-β-mediated epithelial-mesenchymal transition in hepatocellular carcinoma

CR6-interacting factor 1 (CRIF1) regulates cell cycle progression and the DNA damage response. Here, we show that CRIF1 expression is decreased in hepatocellular carcinoma (HCC) tissues and positively correlates with patients’ survival. In vitro, down-regulation of CRIF1 promotes HCC cell proliferation and invasiveness, while over-expression has the opposite effect. in vivo, CRIF1 knockdown enhances growth of HCC xenografts. Analysis of mRNA microarrays showed that CRIF1 knockdown activates genes involved in TGF-β RI/Smad2/3 signaling, leading to epithelial-mesenchymal transition (EMT) and increased matrix metalloproteinase-3 (MMP3) expression. However, cell invasion and EMT are abrogated in HCC cells treated with SB525334, a specific TGF-β RI inhibitor, which indicates the inhibitory effect of CRIF1 on HCC tumor growth is mediated by TGF-β signaling. These results demonstrate that CRIF1 benefits patient survival by inhibiting HCC cell invasiveness through suppression of TGF-β-mediated EMT and MMP3 expression. This suggests CRIF1 may serve as a novel target for inhibiting HCC metastasis.

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

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

HMGA2 regulates lung cancer proliferation and metastasis

BACKGROUND

This study aimed to explore the effects of HMGA2 on cell proliferation and metastases in lung cancer and its underlying mechanism.

METHODS

HMGA2 expression in lung cancer tissues and its association with overall survival were analyzed based on data from a public database. The roles of HMGA2 were validated via loss-of-function and gain-of-function experiments in vitro. HMGA2 regulation by microRNA-195 (miR-195) was validated by real time-PCR, Western blotting, and luciferase reporter assays.

RESULTS

HMGA2 was upregulated and associated with reduced overall survival in patients with lung adenocarcinoma. HMGA2 knockdown suppressed the proliferation and motility of H1299 cells, while HMGA2 ectopic expression in A549 cells increased cell proliferation and migration. HMGA2 affected cell apoptosis through caspase 3/9 and Bcl-2, and regulated epithelial-to-mesenchymal transition by targeting Twist 1. Moreover, miR-195 was found to directly target the 3' untranslated region of HMGA2 messenger RNA and suppress its expression in lung cancer.

CONCLUSION

This study demonstrated that HMGA2, regulated by miR-195, played important roles in proliferation, metastases, and epithelial-to-mesenchymal transition in lung cancer. HMGA2 might serve as a biomarker and potential therapeutic target for lung cancer treatment.

Human MSCs promotes colorectal cancer epithelial-mesenchymal transition and progression via CCL5/β-catenin/Slug pathway

Mesenchymal stem cells (MSCs) extensively interact with cancer cells and other stroma cells in the tumor microenvironment. However, the role of MSCs in colorectal cancer (CRC) progression and metastasis is controversial. This study was designed to identify the role of inflammation-activated-MSCs in CRC development. Our results show that tumor necrosis factor (TNF)-α-preactivated-hMSCs significantly promote the progression of colon cancer cells by enhancing cell proliferation, epithelial–mesenchymal transition, migration, and invasion. TNF-α-primed-hMSCs secrete high level of CCL5, which interacts with its receptor CCR1 expressed in colon cancer cells. Interestingly, the stimulation of colon cancer cell progression by TNF-α-primed hMSCs is associated with the upregulation ofβ-catenin signaling pathway. Blockingβ-catenin pathway significantly decreases the TNF-α-primed-conditioned medium or CCL5-mediated cancer cell progression by decreasing the enhancement of Slug, suggesting that the CCL5/β-catenin/Slug pathway plays a critical role in hMSC-mediated cancer progression. Furthermore,in vivomodel in nude mice confirms the ability of hMSCs to promote the proliferation and progression of colon cancer cells, and the upregulation of CCl5/β-catenin/Slug pathway. Taken together, the present study has demonstrated a novel pathway involving CCl5/CCR1/β-catenin/Slug, via which hMSCs promotes CRC development.

Specific microRNA-mRNA Regulatory Network of Colon Cancer Invasion Mediated by Tissue Kallikrein-Related Peptidase 6

Metastatic colon cancer is a major cause of deaths among colorectal cancer (CRC) patients. Elevated expression of kallikrein 6 (KLK6), a member of a kallikrein subfamily of peptidase S1 family serine proteases, has been reported in CRC and is associated with low patient survival rates and poor disease prognosis. We knocked down KLK6 expression in HCT116 colon cancer cells to determine the significance of KLK6 expression for metastatic dissemination and to identify the KLK6-associated microRNAs (miRNAs) signaling networks in metastatic colon cancer. KLK6 suppression resulted in decreased cells invasion in vitro with a minimal effect on the cell growth and viability. In vivo, animals with orthotopic colon tumors deficient in KLK6 expression had the statistically significant increase in survival rates (P = .005) and decrease in incidence of distant metastases. We further performed the integrated miRNA and messenger RNA (mRNA) expression profiling to identify functional miRNA-mRNA interactions associated with KLK6-mediated invasiveness of colon cancer.

Through bioinformatics analysis we identified and functionally validated the top two up-regulated miRNAs, miR-182 and miR-203, and one down-regulated miRNA, miRNA-181d, and their seven mRNA effectors. The established miRNA-mRNA interactions modulate cellular proliferation, differentiation and epithelial–mesenchymal transition (EMT) in KLK6-expressing colon cancer cells via the TGF-β signaling pathway and RAS-related GTP-binding proteins. We confirmed the potential tumor suppressive properties of miR-181d and miR-203 in KLK6-expressing HCT116 cells using Matrigel invasion assay. Our data provide experimental evidence that KLK6 controls metastasis formation in colon cancer via specific downstream network of miRNA-mRNA effectors.

SphK1 modulates cell migration and EMT-related marker expression by regulating the expression of p-FAK in colorectal cancer cells

Sphingosine kinase 1 (SphK1) plays an important role in colorectal carcinoma metastasis. However, whether SphK1 modulates epithelial-mesenchymal transition (EMT)-related marker expression and the underlying mechanisms remain unclear. In this study, in order to clarify this issue, we used various colorectal cancer (CRC) cell lines, Caco2, HT29, RKO and HCT116. Each of the cell lines was divided into 3 groups as follows: the control group, SKI-Ⅱ (SphK1 inhibitor) group and PF-562271 [focal adhesion kinase (FAK) inhibitor] group. The migratory ability of the cells was examined by Transwell chamber assay. The mRNA and protein expression levels of SphK1, FAK (p-FAK), Slug, vimentin, N-cadherin and E-cadherin were detected by PCR and western blot analysis, respectively. The results revealed that the suppression of SphK1 reduced the cell migratory ability, and decreased the expression of Slug, vimentin and N-cadherin; however, the expression of E-cadherin was increased. Moreover, the inhibition of SphK1 reduced the expression of p-FAK. The inhibition of FAK (p-FAK) also decreased the cell migratory ability, and decreased the expression of Slug, vimentin and N-cadherin, whereas the expression of E-cadherin was increased. Thus, our data suggest that SphK1 modulates the expression of EMT-related markers and cell migration by regulating the expression of p-FAK in CRC cells. Thus, SphK1 may play a functional role in mediating the EMT process in CRC.

HMGA2-FOXL2 Axis Regulates Metastases and Epithelial-to-Mesenchymal Transition of Chemoresistant Gastric Cancer

Purpose: Chemoresistance is the main cause of treatment failure in cancer and is associated with distant metastases and epithelial-to-mesenchymal transition (EMT). This study was aimed to explore the mechanism of metastases and EMT in chemoresistant gastric cancer.Experimental Design: A key molecular pathway was identified via gene profiling and a bioinformatic analysis in a chemoresistant gastric cancer model. The roles of FOXL2, HMGA2, and ITGA2 were validated via loss-of-function and gain-of-function experiments in vitro and in an orthotopic gastric cancer animal model. The regulation of FOXL2 by HMGA2 was explored via immunoprecipitation and luciferase reporter assays. The expression of these proteins in gastric cancer tissues was examined by IHC.Results: HMGA2 and FOXL2 directly regulated the metastasis and EMT of chemoresistant gastric cancer. The interaction between HMGA2 and pRb facilitated the transactivation of FOXL2 by E2F1, and ITGA2 was the downstream effector of the HMGA2-FOXL2 pathway. HMGA2, FOXL2, and ITGA2 were associated with the TNM classification and staging of gastric cancer and were increased in metastatic lymph nodes and distant metastases. Increased HMGA2, FOXL2, and ITGA2 levels were associated with reduced overall survival periods of patients with gastric cancer.Conclusions: This study demonstrated that the transactivation of FOXL2 driven by interactions between HMGA2 and pRb might exert critical effects on the metastases and EMT of chemoresistant gastric cancer. Blocking the HMGA2-FOXL2-ITGA2 pathway could serve as a new strategy for gastric cancer treatment. Clin Cancer Res; 23(13); 3461-73. ©2017 AACR.

Grhl2 reduces invasion and migration through inhibition of TGFβ-induced EMT in gastric cancer

Metastasis is one of the typical features of malignancy that significantly increases cancer-related mortality. Recent studies have shown that epithelial-mesenchymal transition (EMT) is closely related to the invasion and migration of cancer cells. Grainyhead-like 2 (Grhl2), a transcription factor, has been reported to be associated with several tumor processes including EMT. In the previous study, we have reported that Grhl2 functioned as a tumor suppressor in proliferation and apoptosis of gastric cancer. Here we aim to explore the effects of Grhl2 on invasion and migration of gastric cancer and further clarify its possible underlying mechanisms. As a result, in both SGC7901 and MKN45 cells, Grhl2 overexpression significantly inhibited the ability of invasion and migration. In addition, preliminary experiments showed that Grhl2 reduces the protein expression of matrix metalloproteinase-2, -7 and -9 (MMP-2, MMP-7 and MMP-9). Most importantly, Grhl2 antagonizes transforming growth factor-β (TGFβ)-induced EMT, and inhibition of TGFβ signaling pathways can restore Grhl2 expression. Finally, the results of subcutaneous xenograft model indicated that Grhl2 suppresses the growth of gastric cancer and reverses EMT process in vivo. Meanwhile, the metastatic tumor model further confirmed the inhibition of Grhl2 on metastasis of gastric cancer. Taken together, our findings proved that Grhl2, functioned as a tumor suppressor, reduces the invasion and migration through inhibition of TGFβ-induced EMT in gastric cancer.

MiR-4500 is epigenetically downregulated in colorectal cancer and functions as a novel tumor suppressor by regulating HMGA2

This study aimed to understand the exact function and potential mechanism of miR-4500 in colorectal cancer (CRC). In this study, the expression of miR-4500 was decreased in both CRC cells and tissues, and downregulated miR-4500 indicated advanced tumor stage and poor survival. By bisulfite sequencing analysis, we found that the CpG island in the promoter region of miR-4500 was hypermethylated in CRC cells and tissues compared with normal control cells and non-tumor tissues, respectively. Functionally, gain- and loss-of-function analyses indicated the tumor suppressor role of miR-4500: it suppressed cell proliferation, cell cycle progression, migration, and invasion. Predictive algorithms and experimental analyses identified HMGA2 as a direct target of miR-4500. Reintroducing HMGA2 impaired the inhibitory effects of miR-4500 on cell growth and motility. Clinically, higher HMGA2 protein expression in CRC tissues was associated with advanced tumor stage and poor survival. An inverse correlation was found between miR-4500 levels and HMGA2 protein expression. Taken together, this study provides the first evidence that miR-4500 functions as a novel tumor suppressor in the miR-4500/HMGA2 axis in colorectal carcinogenesis, and restoring miR-4500 expression might represent a promising therapeutic strategy for CRC.

Mechanisms of TGFβ-Induced Epithelial-Mesenchymal Transition

Transitory phenotypic changes such as the epithelial–mesenchymal transition (EMT) help embryonic cells to generate migratory descendants that populate new sites and establish the distinct tissues in the developing embryo. The mesenchymal descendants of diverse epithelia also participate in the wound healing response of adult tissues, and facilitate the progression of cancer. EMT can be induced by several extracellular cues in the microenvironment of a given epithelial tissue. One such cue, transforming growth factor β (TGFβ), prominently induces EMT via a group of specific transcription factors. The potency of TGFβ is partly based on its ability to perform two parallel molecular functions, i.e. to induce the expression of growth factors, cytokines and chemokines, which sequentially and in a complementary manner help to establish and maintain the EMT, and to mediate signaling crosstalk with other developmental signaling pathways, thus promoting changes in cell differentiation. The molecules that are activated by TGFβ signaling or act as cooperating partners of this pathway are impossible to exhaust within a single coherent and contemporary report. Here, we present selected examples to illustrate the key principles of the circuits that control EMT under the influence of TGFβ.

Transcriptional activation of FN1 and IL11 by HMGA2 promotes the malignant behavior of colorectal cancer

Colorectal cancer (CRC) is the second leading cause of cancer deaths worldwide, and metastasis is the principle reason for its poor prognosis. Overexpression of high-mobility gene group A2 (HMGA2) contributes to the aggressiveness of CRC. However, the underlying molecular mechanism of its overexpression is still elusive. In this study, we showed that ectopic expression of HMGA2 significantly enhanced cell migration and invasion in vitro and promoted tumor growth and distant metastasis in vivo In contrast, the silencing of HMGA2 produced the opposite effects in vitro and in vivo Chromatin immunoprecipitation-PCR and luciferase assays revealed that HMGA2 bound directly to the promoters of FN1 and IL11 and significantly induced their transcriptional activities. Moreover, as the direct downstream target of HMGA2, IL11 modulated cell migration and invasion through a pSTAT3-dependent signaling pathway. Furthermore, a strong positive correlation between HMGA2 and IL11 expression was identified in 122 CRC tissues. High IL11 expression was associated with poor differentiation, a large tumor size, lymph node metastasis and low overall survival in CRC patients. Collectively, our data reveal novel insights into the molecular mechanisms underlying HMGA2-mediated CRC metastasis and highlight the possibility of targeting HMGA2 and IL11 for treating CRC patients with metastasis.

RNA-binding protein Lin28 in cancer and immunity

The highly conserved RNA-binding protein, Lin28, is involved in many biological processes, including development, reprogramming, pluripotency, and metabolism. Importantly, Lin28 functions as an oncogene, promoting tumor progression and metastasis in various human cancers. Lin28 can regulate gene expression either by directly binding to mRNAs or by blocking microRNA biogenesis, and the underlying mechanisms include Let-7-dependent and Let-7-independent modes of action. Recent evidence shows that Lin28 also plays a fundamental role in immunity. The roles of Lin28 in disease are complex and require characterization of its physiological functions in cancer and immunological contexts. Here we review emerging information on the role of Lin28 in cancer and immunity and the molecular mechanisms it uses. We discuss our present knowledge of the system and highlight remaining mysteries related to the functions of this small RNA-binding protein. This knowledge may lead to Lin28 becoming a diagnostic marker for cancer or immune-related diseases and a possible therapeutic target.

Heat shock protein 90 is involved in the regulation of HMGA2-driven growth and epithelial-to-mesenchymal transition of colorectal cancer cells

High Mobility Group AT-hook 2 (HMGA2) is a nonhistone chromatin-binding protein which acts as a transcriptional regulating factor involved in gene transcription. In particular, overexpression of HMGA2 has been demonstrated to associate with neoplastic transformation and tumor progression in Colorectal Cancer (CRC). Thus, HMGA2 is a potential therapeutic target in cancer therapy. Heat Shock Protein 90 (Hsp90) is a chaperone protein required for the stability and function for a number of proteins that promote the growth, mobility, and survival of cancer cells. Moreover, it has shown strong positive connections were observed between Hsp90 inhibitors and CRC, which indicated their potential for use in CRC treatment by using combination of data mining and experimental designs. However, little is known about the effect of Hsp90 inhibition on HMGA2 protein expression in CRC. In this study, we tested the hypothesis that Hsp90 may regulate HMGA2 expression and investigated the relationship between Hsp90 and HMGA2 signaling. The use of the second-generation Hsp90 inhibitor, NVP-AUY922, considerably knocked down HMGA2 expression, and the effects of Hsp90 and HMGA2 knockdown were similar. In addition, Hsp90 knockdown abrogates colocalization of Hsp90 and HMGA2 in CRC cells. Moreover, the suppression of HMGA2 protein expression in response to NVP-AUY922 treatment resulted in ubiquitination and subsequent proteasome-dependant degradation of HMGA2. Furthermore, RNAi-mediated silencing of HMGA2 reduced the survival of CRC cells and increased the sensitivity of these cells to chemotherapy. Finally, we found that the NVP-AUY922-dependent mitigation of HMGA2 signaling occurred also through indirect reactivation of the tumor suppressor microRNA (miRNA), let-7a, or the inhibition of ERK-regulated HMGA2 involved in regulating the growth of CRC cells. Collectively, our studies identify the crucial role for the Hsp90-HMGA2 interaction in maintaining CRC cell survival and migration. These findings have significant implications for inhibition HMGA2-dependent tumorigenesis by clinically available Hsp90 inhibitors.

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

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

CXCL12/CXCR4 Axis Upregulates Twist to Induce EMT in Human Glioblastoma

In recent decades, the chemokine receptor CXCR4 and its ligand CXCL12 have been extensively reported to be associated with tumorigenesis. In addition, Twist signaling induces the epithelial-mesenchymal transition (EMT) process in glioblastoma development. In the present study, in vitro assays were used to investigate the role of CXCR4 and Twist in human glioblastoma. We explored the impact of CXCR4 and Twist on human glioblastoma using in vitro protein and gene assays. We found the administration of CXCL12 upregulated the expression of p-ERK, p-AKT, Twist, N-cadherin, and MMP9 in U87 cells, whereas the increase of E-cadherin protein was affected. Subsequently, Twist activity and EMT signaling were directly influenced by PD98059 and LY294002. Most importantly, the genetic silencing of Twist inhibited CXCL12-induced EMT occurrence, including proliferation, migration, and tumor formation of U87 cells. In conclusion, CXCL12/CXCR4 pathway activates ERK and PI3K/AKT signaling to upregulate Twist pathway, leading to the progression of EMT in human glioblastoma. Our study creates a new stage for molecule-targeted therapy of human glioblastoma.

Dysregulated protease activated receptor 1 (PAR1) promotes metastatic phenotype in breast cancer through HMGA2

As the majority of patients with basal-like breast carcinoma present with invasive, metastatic disease that do not respond to available therapies, it is essential to identify new therapeutic targets that impact invasion and metastasis. Protease-activated receptor 1 (PAR1), a G-protein coupled receptor has been shown to act as an oncogene, but underlying mechanisms are not well understood. Here, we show that ectopic expression of functionally active PAR1 in MCF-7 cells induced a hormone-refractory, invasive phenotype representative of advanced basal-like breast carcinoma that readily formed metastatic lesions in lungs of mice. PAR1 was found to globally upregulate mesenchymal markers, including vimentin, a direct target of PAR1, and downregulate the epithelial markers including E-cadherin, as well as estrogen receptor. In contrast, non-signaling PAR1 mutant receptor did not lead to an invasive, hormone refractory phenotype. PAR1 expression increased spheroid formation and the level of stemness markers and self-renewal capacity in human breast cancer cells. We identified HMGA2 (high mobility group A2) as an important regulator of PAR1-mediated invasion. Inhibition of PAR1 signaling suppresses HMGA2-driven invasion in breast cancer cells. HMGA2 gene and protein are highly expressed in metastatic breast cancer cells. Overall, our results show that PAR1/HMGA2 pathway may present a novel therapeutic target.