miR-372 down-regulates the oncogene ATAD2 to influence hepatocellular carcinoma proliferation and metastasis

Plin2 inhibits autophagy via activating AKT/mTOR pathway in non-small cell lung cancer

Perilipin 2 (Plin2) is known to be dysregulated in several human malignancies, which facilitates cancer progression. Recent studies have found that the abnormal expression of Plin2 is associated with poor prognosis of non-small cell lung cancer (NSCLC). However, the specific role of Plin2 and its underlying mechanism remain unclear. This study revealed that Plin2 expression was low in NSCLC tissues, and its relatively higher expression indicated larger tumor size and poorer prognosis. In vitro experiments proved that Plin2 promoted NSCLC cellular proliferation and inhibited autophagy by activating the AKT/mTOR pathway. Meanwhile, treatment with the AKT phosphorylation promoter or inhibitor neutralized the influence of Plin2 depletion or over-expression on proliferation and autophagy, respectively. In vivo study showed that Plin2 stimulated subcutaneous tumorigenesis of NSCLC cells in nude mice. Collectively, this study clarified the carcinogenic role of Plin2 and its molecular mechanism in NSCLC progression, which may facilitate a targeted therapy in the future.

ATAD2 is a driver and a therapeutic target in ovarian cancer that functions by upregulating CENPE

Ovarian cancer is a complex disease associated with multiple genetic and epigenetic alterations. The emergence of treatment resistance in most patients causes ovarian cancer to become incurable, and novel therapies remain necessary. We identified epigenetic regulator ATPase family AAA domain-containing 2 (ATAD2) is overexpressed in ovarian cancer and is associated with increased incidences of metastasis and recurrence. Genetic knockdown of ATAD2 or its pharmacological inhibition via ATAD2 inhibitor BAY-850 suppressed ovarian cancer growth and metastasis in both in vitro and in vivo models. Transcriptome-wide mRNA expression profiling of ovarian cancer cells treated with BAY-850 revealed that ATAD2 inhibition predominantly alters the expression of centromere regulatory genes, particularly centromere protein E (CENPE). In ovarian cancer cells, changes in CENPE expression following ATAD2 inhibition resulted in cell-cycle arrest and apoptosis induction, which led to the suppression of ovarian cancer growth. Pharmacological CENPE inhibition phenotypically recapitulated the cellular changes induced by ATAD2 inhibition, and combined pharmacological inhibition of both ATAD2 and CENPE inhibited ovarian cancer cell growth more potently than inhibition of either alone. Thus, our study identified ATAD2 as regulators of ovarian cancer growth and metastasis that can be targeted either alone or in combination with CENPE inhibitors for effective ovarian cancer therapy.

MicroRNA-372 acts as a double-edged sword in human cancers

MicroRNAs (miRNAs or miRs) are non-coding, single-stranded, endogenous RNAs that regulate various biological processes, most notably the pathophysiology of many human malignancies. It process is accomplished by binding to 3'-UTR mRNAs and controlling gene expression at the post-transcriptional level. As an oncogene, miRNAs can either accelerate cancer progression or slow it down as a tumor suppressor. MicroRNA-372 (miR-372) has been found to have an abnormal expression in numerous human malignancies, implying that the miRNA plays a role in carcinogenesis. It is both increased and downregulated in various cancers, and it serves as both a tumor suppressor and an oncogene. This study examines the functions of miR-372 as well as the LncRNA/CircRNA-miRNA-mRNA signaling pathways in various malignancies and analyses its potential prognostic, diagnostic, and therapeutic implications.

ATPase family AAA domain-containing protein 2 (ATAD2): From an epigenetic modulator to cancer therapeutic target

ATPase family AAA domain-containing protein 2 (ATAD2) has been widely reported to be a new emerging oncogene that is closely associated with epigenetic modifications in human cancers. As a coactivator of transcription factors, ATAD2 can participate in epigenetic modifications and regulate the expression of downstream oncogenes or tumor suppressors, which may be supported by the enhancer of zeste homologue 2. Moreover, the dominant structure (AAA + ATPase and bromine domains) can make ATAD2 a potential therapeutic target in cancer, and some relevant small-molecule inhibitors, such as GSK8814 and AZ13824374, have also been discovered. Thus, in this review, we focus on summarizing the structural features and biological functions of ATAD2 from an epigenetic modulator to a cancer therapeutic target, and further discuss the existing small-molecule inhibitors targeting ATAD2 to improve potential cancer therapy. Together, these inspiring findings would shed new light on ATAD2 as a promising druggable target in cancer and provide a clue on the development of candidate anticancer drugs.

The Role of CTNNA1 in Malignancies: An Updated Review

Catenin alpha 1 (CTNNA1), encoding α-catenin, is involved in several physiological activities, such as adherens junction synthesis and signal transduction. Recent studies have suggested additional functions for CTNNA1 malignancies. This review systematically summarizes the varying functions of CTNNA1 in different tumors and briefly describes the diverse pathways and mechanisms involved in different types of tumors. CTNNA1 is abnormally expressed in leukemia and solid tumor such as cancers of digestive system, genitourinary system and breast, and it's related to the occurrence, development, and prognosis of tumors. In addition, the possible physiological processes involving CTNNA1, such as methylation, miRNA interference, or regulatory axes, similar to those of CDH1, SETD2, and hsa-miR-30d-5p/GJA1 are also summarized here. The precise mechanism of CTNNA1 in most cancers remains uncertain; hence, additional pre-clinical studies of CTNNA1 are warranted for potential early tumor diagnosis, prognosis, and treatment.

miR-302 Suppresses the Proliferation, Migration, and Invasion of Breast Cancer Cells by Downregulating ATAD2

Simple Summary

ATPase family AAA domain-containing protein 2 (ATAD2) overexpression is associated with poor survival and disease recurrence in multiple cancers. The current study aimed to investigate the expression and function of ATAD2 in breast cancer. Our results showed that ATAD2 expression was upregulated in human breast cancer tissues and cell lines, while ATAD2 knockdown inhibited the proliferation, migration, and invasion of breast cancer cells. Moreover, we provide evidence suggesting that miR-302 directly targets ATAD2 and thus modulates cancer cell proliferation, migration, and invasion in vitro. Moreover, ATAD2 overexpression rescued the inhibition of tumor growth caused by miR-302 in xenograft mice. These findings indicate that miR-302 plays a crucial role in inhibiting the malignant phenotypes of breast cancer cells by targeting ATAD2.

Abstract

Breast cancer is the most common malignant tumor in women. The ATPase family AAA domain-containing protein 2 (ATAD2) contains an ATPase domain and a bromodomain, and is abnormally expressed in various human cancers, including breast cancer. However, the molecular mechanisms underlying the regulation of ATAD2 expression in breast cancer remain unclear. This study aimed to investigate the expression and function of ATAD2 in breast cancer. We found that ATAD2 was highly expressed in human breast cancer tissues and cell lines. ATAD2 depletion via RNA interference inhibited the proliferation, migration, and invasive ability of the SKBR3 and T47D breast cancer cell lines. Furthermore, Western blot analysis and luciferase assay results revealed that ATAD2 is a putative target of miR-302. Transfection with miR-302 mimics markedly reduced cell migration and invasion. These inhibitory effects of miR-302 were restored by ATAD2 overexpression. Moreover, miR-302 overexpression in SKBR3 and T47D cells suppressed tumor growth in the xenograft mouse model. However, ATAD2 overexpression rescued the decreased tumor growth seen after miR-302 overexpression. Our findings indicate that miR-302 plays a prominent role in inhibiting the cancer cell behavior associated with tumor progression by targeting ATAD2, and could thus be a valuable target for breast cancer therapy.

Aspirin Exerts Its Antitumor Effect in Esophageal Squamous Cell Carcinoma by Downregulating the Expression of ATAD2 and KIF4A

Objective

To investigate the expression of ATPase family AAA domain-containing protein 2 (ATAD2) and kinesin family member 4A (KIF4A) in esophageal squamous cell carcinoma (ESCC) tissues and their association with clinicopathological features and to explore the role of ATAD2 in regulating KIF4A expression and biological functions in ESCC cells and the effect of aspirin on their expression.

Methods

The mRNA and protein expression of ATAD2 and KIF4A in the tissues of patients with ESCC were measured by RT-qPCR and immunohistochemistry, and the correlation between the expression of mRNA and clinicopathological characteristics was analyzed. Western blot and RT-qPCR were used to detect the interference efficiency and KIF4A expression after si-ATAD2 transfection in EC109 and KYSE30 cells. CCK-8 and Transwell assay were performed to investigate the effects of ATAD2 and aspirin on proliferation, migration, and invasion of ESCC cells. The effect of aspirin on the expression of ATAD2 and KIF4A in ESCC cells was measured by RT-qPCR and Western blot.

Results

The expression of ATAD2 and KIF4A was upregulated in ESCC tissues, and both were correlated with the differentiation grades and lymph node metastasis. Knockdown of ATAD2 in ESCC cells significantly inhibited cell proliferation, migration, and invasion. Compared to the negative control group, the proliferation, migration, and invasion ability of ESCC cells in the aspirin-treated groups were decreased, and the expression of ATAD2 and KIF4A in ESCC cells was decreased after treating with aspirin for 48 h.

Conclusion

The expression levels of ATAD2 and KIF4A are elevated in ESCC. ATAD2 promotes proliferation, migration, and invasion of ESCC cells by regulating KIF4A. Aspirin can inhibit the malignant behavior of ESCC cells by downregulating ATAD2 and KIF4A.

Tumor-Promoting ATAD2 and Its Preclinical Challenges

ATAD2 has received extensive attention in recent years as one prospective oncogene with tumor-promoting features in many malignancies. ATAD2 is a highly conserved bromodomain family protein that exerts its biological functions by mainly AAA ATPase and bromodomain. ATAD2 acts as an epigenetic decoder and transcription factor or co-activator, which is engaged in cellular activities, such as transcriptional regulation, DNA replication, and protein modification. ATAD2 has been reported to be highly expressed in a variety of human malignancies, including gastrointestinal malignancies, reproductive malignancies, urological malignancies, lung cancer, and other types of malignancies. ATAD2 is involved in the activation of multiple oncogenic signaling pathways and is closely associated with tumorigenesis, progression, chemoresistance, and poor prognosis, but the oncogenic mechanisms vary in different cancer types. Moreover, the direct targeting of ATAD2’s bromodomain may be a very challenging task. In this review, we summarized the role of ATAD2 in various types of malignancies and pointed out the pharmacological direction.

MicroRNA-217 modulates pancreatic cancer progression via targeting ATAD2

AIMS

Pancreatic cancer is a fatal disease across the world with 5 years survival rate less than 10%. ATAD2, a valid cancer drug-target, is overexpressed in pancreatic malignancy with high oncogenic potential. However, the mechanism of the upregulated expression of ATAD2 in pancreatic cancer is unknown. Since microRNAs (miRNAs) could potentially control target mRNA expressions, and are involved in cancer as tumor-suppressors, oncomiR or both, we examine the possibility of miRNA-mediated regulation of ATAD2 in pancreatic cancer cells (PCCs).

MAIN METHODS

Our in-silico approach first identifies hsa-miR-217 as a candidate regulator for ATAD2 expression. For further validation, luciferase reporter assay is performed. We overexpress hsa-miRNA-217 and assess cellular viability, migration, apoptosis and cell cycle progression in three different PCCs (BxPC3, PANC1, and MiaPaCa2).

KEY FINDINGS

We find hsa-miRNA-217 has potential binding site at the 3'UTR of ATAD2. Luciferase assay confirms that ATAD2 is a direct target of hsa-miR-217. Overexpression of hsa-miR-217 drastically downregulates ATAD2 expression in PCCs, thus, corroborating binding studies. The elevated expression of hsa-miRNA-217 diminishes cell proliferation and migration as well as induces apoptosis and cell cycle arrest in PCCs. Finally, siRNA mediated ATAD2 knockdown or overexpression of hsa-miRNA-217 in PCCs showed inactivation of the AKT signaling pathway. Therefore, hsa-miR-217 abrogates pancreatic cancer progression through inactivation of the AKT signaling pathway and this might be partly due to miR-217 mediated suppression of ATAD2 expression.

SIGNIFICANCE

The application of hsa-miR-217 mimic could be a promising therapeutic strategy for the treatment of pancreatic cancer patients in near future.

Effect of chronic intermittent hypoxia-induced HIF-1α/ATAD2 expression on lung cancer stemness

Background

Obstructive sleep apnea is associated with increased lung cancer incidence and mortality. Cancer stem cells (CSCs) are characterized by their self-renewing ability, which contributes to metastasis, recurrence, and drug resistance. ATPase family AAA domain-containing protein 2 (ATAD2) induces malignancy in different types of tumors. However, a correlation between ATAD2 expression and CSCs in lung cancer has not yet been reported.

Methods

The relative messenger RNA (mRNA) levels of ATAD2, CD44, CD133, and hypoxia-inducible factor (HIF)-1α were determined using reverse-transcription quantitative polymerase chain reaction. ATAD2 protein levels were determined using Western blotting. Cell counting kit-8, 5-ethynyl-2′-deoxyuridine (EdU), and colony formation assays were performed to analyze the proliferation of lung cancer cells. Transwell migration and invasion assays were performed to evaluate cell migration and invasion, respectively. Tumor sphere formation analysis was used to determine tumor spheroid capacity. The link between ATAD2 and HIF-1α was verified using a dual-luciferase reporter assay. Immunofluorescence staining was performed to assess mitochondrial reactive oxygen species (mtROS) production. Flow cytometry analysis was conducted to determine the CD133 and CD44 positive cell ratio.

Results

We evaluated the relative expression of ATAD2 in four lung cancer cell lines (A549, SPC-A1, H460, and H1299 cells) and found increased mRNA and protein levels of ATAD2 in lung cancer samples. ATAD2 overexpression was a poor prognostic factor for lung cancer patients. Loss of ATAD2 reduced lung cancer cell viability and proliferation. Additionally, ATAD2 knockdown repressed lung cancer cell migration, invasion, stem-cell-like properties, and mtROS production. Chronic intermittent hypoxia (CIH)-induced HIF-1α expression significantly activated ATAD2 during lung cancer progression.

Conclusions

This study found that CIH induced HIF-1α expression, which acts as a transcriptional activator of ATAD2. The present study also suggests a novel mechanism by which the integrity of CIH-triggered HIF-1α/ATAD2 may determine lung cancer aggressiveness via the interplay of mtROS and stemness in lung cancer cells.

Supplementary Information

The online version contains supplementary material available at 10.1186/s11658-022-00345-5.

MiR-372-3p Functions as a Tumor Suppressor in Colon Cancer by Targeting MAP3K2

MicroRNAs (miRNAs) as small non-coding RNA transcripts bind their complementary sequences in the 3′-untranslated region (3′-UTR) of target messenger RNAs (mRNAs) to regulate their expression. It is known that miR-372 belongs to the miR-371–373 gene cluster and has been found to be abnormally expressed in a variety of cancers, but its precise mechanism in cancer remains to be discovered. In this study, miR-372-3p expression was assessed in 153 frozen tissue samples, including primary diagnosed colon cancer and matched normal and adjacent tissues, using real time quantitative polymerase chain reaction (qPCR). An analysis of qPCR data revealed a significant reduction in miR-372-3p expression (by >2-fold) in colon cancer tissues in 51.5% (34/66) of patients. Consistent with this, mimicking the increased miR-372-3p levels in SW480 colon cancer cells significantly suppressed cell growth and proliferation. Although no direct correlation was found between the low level of miR-372-3p and certain tumor-related factors, such as p53, HRE-2, PMS2, MLH1, MSH2, MSH6, HDAC4, p21, and Wee1, in colon cancer tissues, an inverse relationship between miR-372-3p and Ki67 (a marker of proliferation) or miR-372-3p and MAP3K2(MEKK2), which plays a critical role in the MAPK signaling pathways, was confirmed using tissue samples. The target relationship between miR-372-3p and MAP3K2 was verified using luciferase assays in SW480 colon cancer cells. As expected, miR-372-3p mimics significantly suppressed the luciferase activity of pMIR-luc/MAP3K2 3′-UTR in cells, suggesting that miR-372-3p modulates the expression of MAP3K2 by directly targeting its 3′-UTR. Overall, the results obtained herein suggest that miR-372-3p may function as a tumor-suppressor miRNA in colon cancer by targeting MAP3K2.

Evaluation of ATAD2 as a Potential Target in Hepatocellular Carcinoma

PURPOSE

Hepatocellular carcinoma (HCC) is one of the leading causes of cancer-related death worldwide with lack of effective systemic chemotherapy. In this study, we aimed to evaluate the value of ATPase family AAA domain-containing protein 2 (ATAD2) as a biomarker and potential therapeutic target for HCC.

METHODS

The expression of ATAD2 was tested in different HCC patient cohorts by immunohistochemistry and comparative transcriptional analysis. The co-expression of ATAD2 and proliferation markers was compared during liver regeneration and malignancy with different bioinformatics tools. The cellular effects of ATAD2 inactivation in liver malignancy was tested on cell cycle, apoptosis, and colony formation ability as well as tumor formation using RNA interference. The genes affected by ATAD2 inactivation in three different HCC cell lines were identified by global gene expression profiling and bioinformatics tools.

RESULTS

ATAD2 overexpression is closely correlated with HCC tumor stage. There was gradual increase from dysplasia, well-differentiated and poorly-differentiated HCC, respectively. We also observed transient upregulation of ATAD2 expression during rat liver regeneration in parallel to changes in Ki-67 expression. ATAD2 knockdown resulted in apoptosis and decreased cell survival in vitro and decreased tumor formation in some HCC cell lines. However, three other HCC cell lines tested were not affected. Similarly, gene expression response to ATAD2 inactivation in different HCC cell lines was highly heterogeneous.

CONCLUSIONS

ATAD2 is a potential proliferation marker for liver regeneration and HCC. It may also serve as a therapeutic target despite heterogeneous response of malignant cells.

Potential Biomarkers of miR-371-373 Gene Cluster in Tumorigenesis

microRNAs (miRNAs) are small non-coding RNA transcripts (20–24 nucleotides) that bind to their complementary sequences in the 3′-untranslated regions (3′-UTR) of targeted genes to negatively or positively regulate their expression. miRNAs affect the expression of genes in cells, thereby contributing to several important biological processes, including tumorigenesis. Identifying the miRNA cluster as a human embryonic stem cell (hESC)-specific miRNAs initially led to the identification of miR-371, miR-372, miR-373, and miR-373*, which can ultimately be translated into mature miRNAs. Recent evidence suggests that miR-371–373 genes are abnormally expressed in various cancers and act either as oncogenes or tumor suppressors, indicating they may be suitable as molecular biomarkers for cancer diagnosis and prevention. In this article, we summarize recent studies linking miR-371–373 functions to tumorigenesis and speculate on the potential applications of miR-371–373 as biomarkers for cancer diagnosis and treatment.

AQP3-mediated H2 O2 uptake inhibits LUAD autophagy by inactivating PTEN

It is widely accepted that redox reprogramming participates in malignant transformation of lung adenocarcinoma (LUAD). However, the source of excessive reactive oxygen species (ROS) and the downstream signaling regulatory mechanism are complicated and unintelligible. In the current study, we newly identified the aquaporin 3 (AQP3) as a LUAD oncogenic factor with capacity to transport exogenous hydrogen peroxide (H₂ O₂ ) and increase intracellular ROS levels. Subsequently, we demonstrated that AQP3 was necessary for the facilitated diffusion of exogenous H₂ O₂ in LUAD cells and that the AQP3-dependent transport of H₂ O₂ accelerated cell growth and inhibited rapamycin-induced autophagy. Mechanistically, AQP3-mediated H₂ O₂ uptake increased intracellular ROS levels to inactivate PTEN and activate the AKT/mTOR pathway to subsequently inhibit autophagy and promote proliferation in LUAD cells. Finally, we suggested that AQP3 depletion retarded subcutaneous tumorigenesis in vivo and simultaneously decreased ROS levels and promoted autophagy. These findings underscore the importance of AQP3-induced oxidative stress in malignant transformation and suggest a therapeutic target for LUAD.

lncRNA MALAT1 regulated ATAD2 to facilitate retinoblastoma progression via miR-655-3p

Long noncoding RNA (lncRNA) metastasis-associated lung adenocarcinoma transcript 1 (MALAT1) was reported as an oncogene in many tumors including retinoblastoma (RB). This research mainly focused on the functions and mechanism of MALAT1 in RB. MALAT1 was upregulated in RB tissues and cells, and it served as a competing endogenous RNA (ceRNA) and inhibited miRNA-655-3p (miR-655-3p) expression, which eventually regulated the expression of miR-655-3p downstream target ATPase Family AAA Domain Containing 2 (ATAD2). The level of ATAD2 significantly increased, while that of miR-655-3p remarkably decreased in RB tissues and cells. MALAT1 depletion inhibited cell proliferation, metastasis, and epithelial-mesenchymal transition (EMT), but promoted apoptosis in vitro and blocked xenograft tumor growth in vivo. MALAT1 exerted its oncogenic functions in RB by regulating miR-655-3p/ATAD2 axis.

MicroRNA-372-3p Predicts Response of TACE Patients Treated with Doxorubicin and Enhances Chemosensitivity in Hepatocellular Carcinoma

BACKGROUND

Identification of factors to detect and improve chemotherapy.response in cancer is the main concern. microRNA-372-3p (miR-372-3p) has been demonstrated to play a crucial role in cellular proliferation, apoptosis and metastasis of various cancers including Hepatocellular Carcinoma (HCC). However, its contribution towards Doxorubicin (Dox) chemosensitivity in HCC has never been studied.

OBJECTIVE

This study aims to investigate the potential role of miR-372-3p in enhancing Dox effects on HCC cell line (HepG2). Additionally, the correlation between miR-372-3p and HCC patients who received Transarterial Chemoembolization (TACE) with Dox treatment has been analyzed.

METHODS

Different cell processes were elucidated by cell viability, colony formation, apoptosis and wound healing assays after miR-372-3p transfection in HepG2 cells Furthermore, the miR-372-3p level has been estimated in the blood of primary HCC patients treated with TACE/Dox by quantitative real-time PCR assay. Receiver Operating Curve (ROC) analysis for serum miR-372-3p was constructed for its prognostic significance. Finally, the protein level of Mcl-1, the anti-apoptotic player, has been evaluated using western blot.

RESULTS

We found a significantly higher level of miR-372-3p in the blood of the responder group of HCC patients who received TACE with Dox than of non-responders. Ectopic expression of miR-372-3p reduced cell proliferation, migration and significantly induced apoptosis in HepG2 cells which was coupled with a decrease of anti-apoptotic protein Mcl-1.

CONCLUSION

Our study demonstrated that miR-372-3p acts as a tumor suppressor in HCC and can act as a predictor biomarker for drug response. Furthermore, the data referred for the first time its potential role in drug sensitivity that might be a therapeutic target for HCC.

Emerging oncogene ATAD2: Signaling cascades and therapeutic initiatives

ATAD2 is a promising oncoprotein with tumor-promoting functions in many cancers. It is a valid cancer drug-target and a potential cancer-biomarker for multiple malignancies. As a cancer/testis antigen (CTA), ATAD2 could also be a probable candidate for immunotherapy. It is a unique CTA that belongs to both AAA+ ATPase and bromodomain family proteins. Since 2007, several research groups have been reported on the pleiotropic oncogenic functions of ATAD2 in diverse signaling pathways, including Rb/E2F-cMyc pathway, steroid hormone signaling pathway, p53 and p38-MAPK-mediated apoptotic pathway, AKT pathway, hedgehog signaling pathway, HIF1α signaling pathway, and Epithelial to Mesenchymal Transition (EMT) pathway in various cancers. In all these pathways, ATAD2 participates in chromatin dynamics, DNA replication, and gene transcription, demonstrating its role as an epigenetic reader and transcription factor or coactivator to promote tumorigenesis. However, despite the progress, an overall mechanism of ATAD2-mediated oncogenesis in diverse origin is elusive. In this review, we summarize the accumulated evidence to envision the overall ATAD2 signaling networks during carcinogenesis and highlight the area where missing links await further research. Besides, the structure-function aspect of ATAD2 is also discussed. Since the efforts have already been initiated to explore targeted drug molecules and RNA-based therapeutic alternatives against ATAD2, their potency and prospects have been elucidated. Together, we believe this is a well-rounded review on ATAD2, facilitating a new drift in ATAD2 research, essential for its clinical implication as a biomarker and/or cancer drug-target.

MicroRNA-302 represses epithelial-mesenchymal transition and cisplatin resistance by regulating ATAD2 in ovarian carcinoma

Epithelial-mesenchymal transition (EMT) is an important contributor to drug resistance in ovarian cancer. The aims of this study were to explore the potential role of the miR-302 cluster in modulating EMT and cisplatin resistance in ovarian cancer. We used qRT-PCR and western blotting to show that miR-302 expression was lower in chemoresistant than in chemosensitive cells, and miR-302 was upregulated in chemosensitive, but not chemoresistant ovarian cancer cells in response to cisplatin treatment. We identified ATAD2 as a target of miR-302 and showed that ectopic expression of miR-302 increased cisplatin sensitivity and inhibited EMT and the invasiveness of cisplatin-resistant cells in vitro by targeting ATAD2. Knockdown of ATAD2 restored cisplatin sensitivity and reversed EMT/metastasis in cisplatin-resistant cells, as shown by western blotting and invasion/migration assays. The effect of miR-302 overexpression on EMT and invasiveness was mediated by the modulation of β-catenin nuclear expression. Immunofluorescence analysis showed that ATAD2 overexpression reversed the miR-302-induced downregulation of nuclear β-catenin in cisplatin resistant cells. A xenograft tumor model was used to show that miR-302 increases the antitumor effect of cisplatin in vivo. Taken together, these results identify a potential regulatory axis involving miR-302 and ATAD2 with a role in chemoresistance, indicating that activation of miR-302 or inactivation of ATAD2 could serve as a novel approach to reverse cisplatin resistance in ovarian cancer.

The Role of Long Non-Coding RNAs in Thyroid Cancer

Thyroid cancer, the most common endocrine malignancy, has become the most commonly diagnosed malignant solid tumor. Moreover, some cases have poor prognosis, and the survival period is only 3-5 months. Long noncoding RNAs (lncRNAs) are a group of functional RNA molecules more than 200 nucleotides in length that lack the ability to encode protein but participate in all aspects of gene regulation. Functionally, many lncRNAs play essential roles in epigenetic regulation at transcriptional and post-transcriptional levels via various molecular mechanisms. Recent studies have discovered important roles for lncRNAs during the complex process of carcinogenesis in thyroid cancer. In this review, we focus on lncRNAs dysregulated in thyroid cancer and summarize recently reported associations between lncRNAs and thyroid cancer in order to demonstrate the significant value of lncRNAs in diagnosis and treatment.

Long Non-Coding RNA CRNDE Promotes Colorectal Carcinoma Cell Progression and Paclitaxel Resistance by Regulating miR-126-5p/ATAD2 Axis

Background

Long non-coding RNA colorectal neoplasia differentially expressed (lncRNA CRNDE) and microRNA-126-5p (miR-126-5p) were reported to be related to the development of colorectal carcinoma (CRC). However, the detailed mechanism of CRNDE and miR-126-5p is not fully understood. The purpose of this research was to explore their roles and molecular mechanism in CRC.

Methods

Quantitative real-time polymerase chain reaction was performed to detect the transcription levels of genes. Paclitaxel (PTX) was used to analyze cell drug resistance. 3-(4, 5-Dimethylthiazol-2-yl)-2, 5-diphenyltetrazolium bromide assay and flow cytometry analysis were employed to assess cell proliferation and apoptosis, respectively. Furthermore, cell migratory and invasive abilities were measured using transwell assay. The interaction between miR-126-5p and CRNDE or ATPase family AAA domain-containing protein 2 (ATAD2) was predicted by online tool starbase and then confirmed using the dual-luciferase reporter assay. Besides, Western blot assay was carried out to detect the levels of proteins.

Results

CRNDE and ATAD2 expressions were upregulated and miR-126-5p expression was downregulated in CRC tissues and cells. CRNDE depletion repressed PTX resistance and the growth of CRC cells. Interestingly, we found that miR-126-5p was a target gene of CRNDE, and miR-126-5p directly targeted ATAD2. Furthermore, CRNDE affected CRC cell progression via modulation of miR-126-5p/ATAD2 axis in CRC cells.

Conclusion

Our data suggested that CRNDE regulated CRC cell development and PTX resistance by modulating miR-126-5p/ATAD2 axis, providing the theoretical basis for the treatment of CRC patients.

Long Non-Coding HULC and miRNA-372 as Diagnostic Biomarkers in Hepatocellular Carcinoma

Background

We aimed to evaluate the effectiveness of Highly Upregulated in Liver Cancer (HULC) and microRNA-372 (miR-372) as biochemical markers in Hepatocellular carcinoma (HCC) and HCV-infected patients.

Methods

The present study was conducted on 100 Egyptian individuals divided into 3 groups, 40 patients with HCC and HCV infection, 40 patients only HCV-infected, and 20 individuals as normal controls. They were subject to full history taking, full clinical and laboratory examination, and assessment of HULC and miR-372 levels by real-time PCR.

Results

A statistically significant difference was found with p< 0.05 between HCC and each of HCV and control groups as regards HULC level with high mean among HCC followed by HCV patients. Our results also show a statistically significant difference with p< 0.05 between each of HCC and HCV compared to control as regards miR-372 level with low mean among HCC patients.

Conclusion

HULC could be considered as a potential non-invasive marker for detection and early diagnosis of HCC. Also, it may play an important role in the early prophylaxis and control measures to reduce the incidence of HCC. However, miR-372 cannot be considered as a reliable marker as HULC for early detection of HCC especially in HCV patients.

Integrated Bioinformatics Analysis of the Clinical Value and Biological Function of ATAD2 in Hepatocellular Carcinoma

ATPase family AAA domain-containing protein 2 (ATAD2), a chromatin regulator and an oncogenic transcription cofactor, is frequently overexpressed in many cancers, particularly in hepatocellular carcinoma (HCC). By integrating open-access online mRNA datasets and our institutional tissue data on HCC, the clinical role and functions of ATAD2 were analyzed by bioinformatic algorithms. We systematically examined ATAD2 expression in HCC based on a large sample population, integrating data from our institution and the GEO, Oncomine, and TCGA datasets. Aberrant ATAD2 expression related to pathways was identified by bioinformatic algorithms. The effects of ATAD2 downregulation on the cycle cell were also determined. A pooled analysis from 28 datasets indicated that ATAD2 overexpression was found in HCC (SMD = 8.88, 95% CI: 5.96–11.81, P < 0.001) and was correlated with poor survival. Subgroup analysis of Asian patients with a serum alpha-fetoprotein (AFP) concentration < 200 ng/ml in stage I + II showed that the ATAD2-high group had a more unfavorable overall survival (OS) rate than the ATAD2-low group. The receiver operating characteristic curve indicated that the efficiency of ATAD2 for HCC diagnosis was considerable (area under the curve = 0.89, 95% CI: 0.86–0.91). Functional analysis based on bioinformatic algorithms demonstrated that ATAD2 participates in cell division, mitotic nuclear division, DNA replication, repair, and cell cycle processes. ATAD2 knockout in HCC cells downregulated cyclin C and cyclin D1 protein levels and resulted in G1/S phase arrest in vitro. The kinesin family member C1 (KIFC1), shugoshin 1 (SGO1), GINS complex subunit 1 (GINS1), and TPX2 microtubule nucleation factor (TPX2) genes were closely related to ATAD2 upregulation. ATAD2 may interact with TTK protein kinase (TTK) to accelerate HCC carcinogenesis. ATAD2 plays a vital role in HCC carcinogenesis by disturbing the interaction between chromatin proteins and DNA. Targeting ATAD2 represents a promising method for the development of therapeutic treatments for cancer.

ATAD2 expression increases [18F]Fluorodeoxyglucose uptake value in lung adenocarcinoma via AKT-GLUT1/HK2 pathway

[18F]Fluorodeoxyglucose (FDG) PET/CT imaging has been widely used in the diagnosis of malignant tumors. ATPase family AAA domain-containing protein 2 (ATAD2) plays important roles in tumor growth, invasion and metastasis. However, the relationship between [18F]FDG accumulation and ATAD2 expression remains largely unknown. This study aimed to investigate the correlation between ATAD2 expression and [18F]FDG uptake in lung adenocarcinoma (LUAD), and elucidate its underlying molecular mechanisms. The results showed that ATAD2 expression was positively correlated with maximum standardized uptake value (SUV_max), total lesion glycolysis (TLG), glucose transporter type 1 (GLUT1) expression and hexokinase2 (HK2) expression in LUAD tissues. In addition, ATAD2 knockdown significantly inhibited the proliferation, tumorigenicity, migration, [18F]FDG uptake and lactate production of LUAD cells, while, ATAD2 overexpression exhibited the opposite effects. Furthermore, ATAD2 modulated the glycometabolism of LUAD via AKT-GLUT1/HK2 pathway, as assessed using LY294002 (an inhibitor of PI3K/AKT pathway). In summary, to explore the correlation between ATAD2 expression and glycometabolism is expected to bring good news for anti-energy metabolism therapy of cancers.

Knockdown of ATAD2 Inhibits Proliferation and Tumorigenicity Through the Rb-E2F1 Pathway and Serves as a Novel Prognostic Indicator in Gastric Cancer

Introduction

The aim of the present study was to examine the expression of ATAD2 in gastric cancer (GC) specimens and to evaluate its correlation with clinicopathologic features, including survival of GC patients. The potential roles of ATAD2 in the GC cell proliferation, apoptosis, and tumour growth were further explored.

Materials and Methods

Quantitative reverse transcription-polymerase chain reaction (qRT-PCR), Western blotting and immunohistochemistry (IHC) were applied to determine the mRNA and protein expression of ATAD2 in GC and corresponding adjacent non-tumourous specimens. The relationship between ATAD2 expression and clinicopathological features of GC patients was analysed. Kaplan-Meier analysis was performed to assess the prognostic value of ATAD2 expression levels. The proliferation, colony formation, apoptosis and tumorigenesis roles of ATAD2 were measured using in vitro and in vivo experiments.

Results

The expression of ATAD2 mRNA and protein was overexpressed in GC tissues compared with corresponding adjacent non-tumourous tissues. ATAD2 expression was significantly correlated with tumour size, tumour differentiation, and clinical tumour-node-metastasis (TNM) stage. Patients with high ATAD2 expression were likely to experience significantly shorter postoperative overall survival (OS) and disease-free survival (DFS). Multivariate Cox analysis suggested ATAD2 as an independent variable for OS and DFS. Knockdown of ATAD2 significantly suppressed cell proliferation, colony formation in vitro and tumorigenicity in vivo. Cell cycle and apoptotic assays showed that the anti-proliferative effect of pLV-ATAD2 shRNA was mediated by arresting cells in the G1 phase and inducing cell apoptosis. Silencing of ATAD2 reduced the expression of cyclinD1, ppRb, E2F1 and cyclinE and upregulated the expression of cleaved-PARP and cleaved-Caspase 3.

Conclusion

Our study indicated that ATAD2 plays an important role in the process of tumorigenesis and progression in GC, and it could serve as a novel prognostic biomarker and a therapeutic target for the treatment of GC patients.

Downregulation of AAA-domain-containing protein 2 restrains cancer stem cell properties in esophageal squamous cell carcinoma via blockade of the Hedgehog signaling pathway

Esophageal squamous cell carcinoma (ESCC) ranks among the five most common cancers in China and has a five-year survival rate of less than 15%. The transcription factor ATPase-family AAA-domain-containing protein 2 (ATAD2) has potential as a therapeutic target in various tumors, and microarray-based gene expression profiling reveals dysregulation of ATAD2 specifically in ESCC. Here we investigated whether ATAD2 could mediate a regulation of cancer stem cell (CSC) biological functions in ESCC. Immunohistochemical staining, reverse transcription quantitative polymerase chain reaction, and Western blot assays all revealed upregulation of ATAD2 in ESCC tissues and cell lines, which furthermore correlated with progression of ESCC. In loss-of-function experiments, silencing of ATAD2 inhibited activation of the Hedgehog signaling pathway, as indicated by reduced expression of glioma-associated oncogene family zinc finger 1 (Gli1), smoothened frizzled class receptor (SMO), and patched 1 (PTCH1). Investigations with 5-ethynyl-2'-deoxyuridine (EdU), Transwell assay, scratch test, flow cytometry, and colony formation assay showed that silencing of ATAD2 or inhibiting the Hedgehog signaling decreased the proliferation, invasion, and migration abilities along with colony formation, but elevated the apoptosis rate of CSCs. Furthermore, in vivo experiments validated the suppressive effect of siRNA-mediated ATAD2 silencing on tumor growth in nude mice. Thus, downregulation of ATAD2 can seemingly restrain the malignant phenotypes of ESCC cells through inhibition of the Hedgehog signaling pathway.

Prognostic value of ATPase family, AAA+ domain containing 2 expression in human cancers: A systematic review and meta-analysis

BACKGROUND

ATPase family, AAA+ domain containing 2 (ATAD2) is also known as AAA+ nuclear coregulator cancer-associated protein or PRO2000. ATAD2 has been reported as a prognostic factor in different cancer types, but the association between ATAD2 high expression and survival is still unclear. Thereby, this meta-analysis was performed to evaluate the prognostic value of ATAD2 high expression in human cancers.

METHODS

All of the studies included were retrieved from PubMed, EMBASE, and Cochrane Library electronic databases. The clinical outcomes were evaluated by calculating hazard ratio (HR) with their 95% confidence interval (CI).

RESULTS

Thirteen studies including 2689 patients were eligible for this analysis. The pooled results showed that ATAD2 over-expression was significantly associated with shorter overall survival (OS) (HR = 2.32, 95% CI = 1.77-3.02), as well as shorter recurrence-free survival (RFS), disease-free survival (DFS), and disease-specific survival (DSS) (HR = 1.83, 95% CI = 1.51-2.23) among human cancers. Subgroup analyses for OS were implemented in terms of region, tumor type, and sample size and the results were coincident with overall pooled results. Begg funnel plot and Egger test showed the presence of publication bias for OS. Sensitivity analysis indicated that both results were not affected for removing any study.

CONCLUSION

ATAD2 would be likely to act as a prognostic biomarker for the patients of different cancer types and provide a guide on clinical treatment. Prospective clinical studies are needed to support these findings.

Bioinformatics analysis identifies hub genes and pathways in nasopharyngeal carcinoma

The aim of the present study was to identify genes associated with and the underlying mechanisms in nasopharyngeal carcinoma (NPC) using microarray data. GSE12452 and GSE34573 gene expression profiles were obtained from the Gene Expression Omnibus (GEO) database. GEO2R was utilized to obtain differentially expressed genes (DEGs). In addition, the Database for Annotation, Visualization and Integrated Discovery was used to perform pathway enrichment analyses for DEGs using the Gene Ontology (GO) annotation along with the Kyoto Encyclopedia of Genes and Genomes (KEGG). Furthermore, Cytoscape was used to perform module analysis of the protein-protein interaction (PPI) network and pathways of the hub genes were studied. A total of 298 genes were ascertained as DEGs in the two datasets. To functionally categorize these DEGs, we obtained 82 supplemented GO terms along with 7 KEGG pathways. Subsequently, a PPI network consisting of 10 hub genes with high degrees of interaction was constructed. These hub genes included cyclin-dependent kinase (CDK) 1, structural maintenance of chromosomes (SMC) 4, kinetochore-associated (KNTC) 1, kinesin family member (KIF) 23, aurora kinase A (AURKA), ATAD (ATPase family AAA domain containing) 2, NDC80 kinetochore complex component, enhancer of zeste 2 polycomb repressive complex 2 subunit, BUB1 mitotic checkpoint serine/threonine kinase and protein regulator of cytokinesis 1. CDK1, SMC4, KNTC1, KIF23, AURKA and ATAD2 presented with high areas under the curve in receiver operator curves, suggesting that these genes may be diagnostic markers for nasopharyngeal carcinoma. In conclusion, it was proposed that CDK1, SMC4, KNTC1, KIF23, AURKA and ATAD2 may be involved in the tumorigenesis of NPC. Furthermore, they may be utilized as molecular biomarkers in early diagnosis of NPC.

Comprehensive analysis of histone modification-associated genes on differential gene expression and prognosis in gastric cancer

Accumulating evidence suggests that the epigenetic alterations caused by histone modifications have important roles in the genesis of gastric cancer (GC), particularly the well-studied acetylation and methylation modifications. In the present study, a Bioinformatics analysis of the expression of histone modification-associated genes in GC and normal tissues was performed by using datasets from Oncomine, the Gene Expression Omnibus (GEO) and The Cancer Genome Atlas (TCGA). The clinical data of GC patients were downloaded from TCGA to determine the association between histone modification-associated gene expression and clinicopathological parameters or survival of GC. Finally, lysine acetyltransferase 2A (KAT2A), nuclear receptor coactivator 1 (NCOA1), SMYD family member 5 (SMYD5), protein arginine methyltransferase 1 (PRMT1) and PRDF1-RIZ (PR)/Su(var)3-9, enhancer-of-zeste and trithorax (SET) domain 16 (PRDM16) were screened; KAT2A, SMYD5 and PRMT1 were upregulated, while PRDM16 expression was downregulated in GC. Analysis of the GEO and Oncomine datasets revealed that NCOA1 was upregulated, which was contrary to the result obtained with the TCGA stomach adenocarcinoma dataset. Aberrant expression of KAT2A, NCOA1, SMYD5 and PRMT1 was more obvious in gastric intestinal-type adenocarcinoma; low NCOA1 expression was associated with better overall survival of GC patients [hazard ratio (HR)=0.690, 95% CI=0.570-0.840, P<0.001] and was an independent predictor for patients diagnosed with GC (HR=0.639, 95% CI=0.437-0.933, P=0.020). Correlation analysis and protein-protein interaction network analysis indicated a close association between ATAD2 and estrogen receptor 1 (ESR1), PRMT1, NCOA1 and KAT2A. In conclusion, differential expression of KAT2A, NCOA1, SMYD5, PRMT1 and PRDM16 was identified in GC vs. normal tissues, low NCOA1 expression was associated with poor survival of GC and ATAD2 may interact with ESR1 to regulate NCOA1 and PRMT1 in GC.

Aquaporin 3 maintains the stemness of CD133+ hepatocellular carcinoma cells by activating STAT3

An increasing interest in liver cancer stemness arises owing to its aggressive behavior and poor prognosis. CD133, a widely known liver cancer stem cell marker, plays critical roles in the maintenance of liver cancer stemness. Thus, exploring the regulatory mechanism of CD133 expression is significant. In the present study, we proved the carcinogenesis roles of aquaporin 3 (AQP3) in hepatocellular carcinoma (HCC) and demonstrated that AQP3 promotes the stem cell-like properties of hepatoma cells by regulating CD133 expression. In addition, AQP3 promoted the stimulation and nuclear translocation of signal transducer and activator of transcription 3 (STAT3) with a subsequent increase in the level of CD133 promoter-acetylated histone H3. This phenomenon accelerated CD133 transcription. Next, whether AQP3 acted as an oncogenic gene in HCC and maintained the stemness of CD133+ hepatoma cells were elucidated; also, a novel mechanism underlying the AQP3/STAT3/CD133 pathway in HCC was deduced.

Overexpression of microRNA-186 inhibits angiogenesis in retinoblastoma via the Hedgehog signaling pathway by targeting ATAD2

Retinoblastoma (RB) represents an aggressive malignancy in the eye during the period of infancy and childhood. We delineated the ability of microRNA-186 (miR-186) to influence viability, invasion, migration, angiogenesis, and apoptosis of RB via the Hedgehog signaling pathway by targeting AAA domain-containing protein 2 (ATAD2). The microarray-based analysis was adopted to identify differentially expressed genes (DEGs) related to RB. Subsequently, RB cells were treated with miR-186 mimic, miR-186 inhibitor, or si-ATAD2. The expression of miR-186, ATAD2, Hedgehog signaling pathway-related genes were evaluated, and the target relationship between miR-186 and ATAD2 was verified. Finally, cell proliferation, invasion, migration, apoptosis, and angiogenesis were assessed. ATAD2 was identified as a DEG and modulated by miR-186. Moreover, we revealed that ATAD2 was highly expressed, whereas miR-186 was lowly expressed, and the Hedgehog signaling pathway was activated in RB. Then, ATAD2 as a putative target of miR-186 was validated using a luciferase assay. miR-186 mimic or siRNA-ATAD2 in RB cells reduced cell viability, invasion, and migration coordinating with elevated apoptosis via impairing the Hedgehog signaling pathway, where repressed angiogenesis was observed. Overexpression of miR-186 attenuates RB via the inactivation of the Hedgehog signaling pathway by downregulating ATAD2.

Involvement of long non-coding RNA HULC (highly up-regulated in liver cancer) in pathogenesis and implications for therapeutic intervention

INTRODUCTION

HULC (highly upregulated in liver cancer) is a long non-coding RNA (lncRNA) which is, as its name suggests, highly upregulated in hepatocellular carcinoma and in several other cancers. Increased HULC expression levels are strongly associated with clinicopathologic features such as tumor stages and overall survival and is a driver of tumor proliferation, migration, and invasion. Areas covered: This review addresses the discovery of HULC and discusses the consequences of HULC deregulation in cancer, the underlying molecular mechanisms and the potential of HULC as a biomarker and therapeutic target. Expert opinion: HULC is a promising candidate as a therapeutic target in cancer; however, more studies are necessary to further elucidate the underlying molecular mechanism(s), especially in cancer types other than hepatocellular carcinomas. Future studies that focus on an optimized HULC-targeting approach are necessary to clarify the best strategy to target this lncRNA in vivo and in patients.

ATAD2 is associated with malignant characteristics of pancreatic cancer cells

Pancreatic cancer is one of the most aggressive human cancers and is associated with a poor prognosis. To develop a novel strategy for pancreatic cancer treatment, it is essential to elucidate the molecular mechanisms underlying the invasion and proliferation of cancer cells. ATPase family AAA domain containing protein 2 (ATAD2) is a highly conserved protein with an AAA+ domain and a bromodomain. Accumulating studies have demonstrated that ATAD2 is associated with the progression of multiple cancers. The present study demonstrated that ATAD2 depletion suppressed cell invasion and migration. In addition, ATAD2 knockdown suppressed anchorage-independent growth of pancreatic cancer cells. Finally, ATAD2 depletion was demonstrated to sensitize pancreatic cancer cells to gemcitabine. The results of the present study indicate that ATAD2 is involved in the malignant characteristics of pancreatic cancer.

Disulfide bridge formation influences ligand recognition by the ATAD2 bromodomain

The ATPase family, AAA domain-containing protein 2 (ATAD2) has a C-terminal bromodomain, which functions as a chromatin reader domain recognizing acetylated lysine on the histone tails within the nucleosome. ATAD2 is overexpressed in many cancers and its expression is correlated with poor patient outcomes, making it an attractive therapeutic target and potential biomarker. We solved the crystal structure of the ATAD2 bromodomain and found that it contains a disulfide bridge near the base of the acetyllysine binding pocket (Cys1057-Cys1079). Site-directed mutagenesis revealed that removal of a free C-terminal cysteine (C1101) residue greatly improved the solubility of the ATAD2 bromodomain in vitro. Isothermal titration calorimetry experiments in combination with the Ellman's assay demonstrated that formation of an intramolecular disulfide bridge negatively impacts the ligand binding affinities and alters the thermodynamic parameters of the ATAD2 bromodomain interaction with a histone H4K5ac peptide as well as a small molecule bromodomain ligand. Molecular dynamics simulations indicate that the formation of the disulfide bridge in the ATAD2 bromodomain does not alter the structure of the folded state or flexibility of the acetyllysine binding pocket. However, consideration of this unique structural feature should be taken into account when examining ligand-binding affinity, or in the design of new bromodomain inhibitor compounds that interact with this acetyllysine reader module.

Prior Knowledge Driven Joint NMF Algorithm for ceRNA Co-Module Identification

MRNA and lncRNA serve as a type of endogenous RNA in cell, which can competitively bind to the same miRNA through miRNA response elements (MREs), thereby regulating their respective expression levels, playing an important role in post-transcriptional regulation, and regulating the progress of tumors. The proposed competing endogenous RNA (ceRNA) hypothesis provides novel clues for the occurrence and development of tumors, but the integrative analysis methods of diverse RNA data are significantly limited. In order to find out the relationship among miRNA, mRNA and lncRNA, the previous studies only used individual dataset as seeds to search two other related data in the database to construct ceRNA network, but it was difficult to identify the synchronized effects from multiple regulatory levels. Here, we developed the joint matrix factorization method integrating prior knowledge to map the three types of RNA data of lung cancer to the common coordinate system and construct the ceRNA network corresponding to the common module. The results show that more than 90% of the modules are closely related to cancer, including lung cancer. Furthermore, the resulting ceRNA network not only accurately excavates the known correlation of the three types of RNA molecular, but also further discovers the potential biological associations of them. Our work provides support and foundation for future biological validation how competitive relationships of multiple RNAs affects the development of tumors.

Aiming to Miss a Moving Target: Bromo and Extra Terminal Domain (BET) Selectivity in Constrained ATAD2 Inhibitors

ATAD2 is a cancer-associated protein whose bromodomain has been described as among the least druggable of its class. In our recent disclosure of the first chemical probe against this bromodomain, GSK8814 (6), we described the use of a conformationally constrained methoxy piperidine to gain selectivity over the BET bromodomains. Here we describe an orthogonal conformational restriction strategy of the piperidine ring to give potent and selective tropane inhibitors and show structural insights into why this was more challenging than expected. Greater understanding of why different rational approaches succeeded or failed should help in the future design of selectivity in the bromodomain family.

miR372 Promotes Progression of Liver Cancer Cells by Upregulating erbB-2 through Enhancement of YB-1

MicroRNAs are known to be involved in carcinogenesis. Recently, microRNA-372 (miR372) has been proven to play a substantial role in several human cancers, but its functions in liver cancer remain unclear. Herein, our results demonstrate that miR372 accelerates growth of liver cancer cells in vitro and in vivo. Mechanistically, miR372 enhances expression of Y-box-binding protein 1 (YB-1) by targeting for phosphatase and tensin homolog (PTEN) directly and consequently promotes phosphorylation of YB-1 via HULC looping dependent on ERK1/2 and PTEN. In particular, HULC knockdown or PTEN overexpression abrogated this miR372 action. Moreover, miR372 inhibits the degradation of β-catenin dependent on phosphorylation of YB-1 and then enhances the expression and activity of pyruvate kinase M2 isoform (PKM2) by β-catenin-LEF/TCF4 pathway. Furthermore, the loading of LEF/TCF4 on PKM2 promoter region was significantly increased in miR372 overexpressing Hep3B, and thus, glycolytic proton efflux rate (glycoPER) was significantly increased in rLV-miR372 group compared to the rLV group. Moreover, β-catenin knockdown abrogates this function of miR372. Ultimately, miR372 promotes the expression of erbB-2 through PKM2-pH3T11-acetylation on histone H3 lysine 9 (H3K9Ac) pathway. Of significance, both YB-1 knockdown and erbB-2 knockdown abrogate oncogenic action of miR372. Our observations suggest that miR372 promotes liver cancer cell cycle progress by activating cyclin-dependent kinase 2 (CDK2)-cyclin E-P21/Cip1 complex through miR372-YB-1-β-catenin-LEF/TCF4-PKM2-erbB-2 axis. This study elucidates a novel mechanism for miR372 in liver cancer cells and suggests that miR372 can be used as a novel therapeutic target of liver cancer.

Long noncoding RNA PCAT-14 induces proliferation and invasion by hepatocellular carcinoma cells by inducing methylation of miR-372

Long non-coding RNAs (lncRNAs) regulate oncogenesis by inducing methylation of CpG islands to silence target genes. Here we show that the lncRNA PCAT-14 is overexpressed in patients with hepatocellular carcinoma (HCC), and is associated with a poor prognosis after surgery. Our results demonstrate that PCAT-14 promotes proliferation, invasion, and cell cycle arrest in HCC cells. In addition, PCAT-14 inhibits miR-372 expression by inducing methylation of the miR-372 promoter. Simultaneously, miR-372 eliminates the effects of PCAT-14 on proliferation, invasion, and cell cycle in HCC cells. Moreover, PCAT-14 regulates expression of ATAD2 and activation of the Hedgehog pathway via miR-372. These findings indicate that PCAT-14 plays an important role in HCC, and may serve as a novel prognostic factor and therapeutic target.

NEAT1_2 functions as a competing endogenous RNA to regulate ATAD2 expression by sponging microRNA-106b-5p in papillary thyroid cancer

Nuclear paraspeckle assembly transcript 1 (NEAT1), a long non-coding RNA (lncRNA), is a core structural component of paraspeckles and is essential for paraspeckle formation. NEAT1 comprises two different isoforms: NEAT1_1 (3.7 kb) and NEAT1_2 (23 kb). Recently, NEAT1 has been shown to have oncogenic roles and to facilitate tumorigenesis in various human cancers. However, the function of NEAT1 in papillary thyroid cancer (PTC) is not well understood. The relative expression levels of NEAT1_2, ATPase family AAA domain-containing protein 2 (ATAD2), and microRNA-106b-5p (miR-106b-5p) were assessed via quantitative real-time reverse transcription polymerase chain reaction (qRT-PCR). Four PTC cell lines were used to detect the relative expression of NEAT1_2. The effects of NEAT1_2 on PTC cells were studied by RNA interference approaches in vitro. The effects of NEAT1_2 on downstream proteins were detected by western blotting. The underlying mechanism was clarified by a rescue experiment, and three dual-luciferase reporter assays. NEAT1_2 expression was markedly increased in PTC tissues and the PTC cell lines (K1 and TPC1). The relative expression level of NEAT1_2 was positively associated with TNM stage and tumor size. NEAT1_2 knockdown led to a significant inhibition of growth and metastasis, and induced apoptosis in PTC cells. Knockdown of NEAT1_2 significantly inhibited malignant biological behavior by downregulating the oncogene ATAD2. In addition, NEAT1_2 could act as a competing endogenous RNA to regulate the expression of ATAD2 through downregulating miR-106b-5p. Taken together, our results indicated that NEAT1_2 is overexpressed in PTC. NEAT1_2 could function as a competing endogenous RNA to regulate ATAD2 expression by sponging miR-106b-5p in PTC. Targeting NEAT1_2 could be a promising therapeutic strategy for patients with PTC.

miR-372 promotes breast cancer cell proliferation by directly targeting LATS2

MicroRNAs (miRs) have previously been demonstrated to be important in the tumorigenesis and progression of breast cancer. miR-372 was previously revealed to be involved in various types of human cancer, however its function in breast cancer remains largely unknown. The present study demonstrated that miR-372 is frequently overexpressed in breast cancer cell lines and tissues. The downregulation of miR-372 markedly inhibited cell proliferation, arrested the cell cycle in the G1/S phase, and increased the apoptosis of breast cancer cells. Consistently, an in vivo xenograft study also demonstrated the suppressive effects of miR-372 knockdown on tumor growth. Further studies revealed that miR-372 modulated the expression of large tumor suppressor kinase 2 (LATS2) by directly targeting its 3′-untranslated region in breast cancer cells. Furthermore, silencing of LATS2 was able to rescue the effect of the miR-372 inhibitor. Overall, the results suggest that miR-372 functions as an oncogenic miRNA in breast cancer by targeting LATS2.

ATAD2 in cancer: a pharmacologically challenging but tractable target

INTRODUCTION

ATAD2 protein is an emerging oncogene that has strongly been linked to the etiology of multiple advanced human cancers. Therapeutically, despite the fact that genetic suppression/knockdown studies have validated it as a compelling drug target for future therapeutic development, recent druggability assessment data suggest that direct targeting of ATAD2's bromodomain (BRD) may be a very challenging task. ATAD2's BRD has been predicted as a 'difficult to drug' or 'least druggable' target due to the concern that its binding pocket, and the areas around it, seem to be unfeasible for ligand binding. Areas covered: In this review, after shedding light on the multifaceted roles of ATAD2 in normal physiology as well as in cancer-etiology, we discuss technical challenges rendered by ATAD2's BRD active site and the recent drug discovery efforts to find small molecule inhibitors against it. Expert opinion: The identification of a novel low-nanomolar semi-permeable chemical probe against ATAD2's BRD by recent drug discovery campaign has demonstrated it to be a pharmacologically tractable target. Nevertheless, the development of high quality bioavailable inhibitors against ATAD2 is still a pending task. Moreover, ATAD2 may also potentially be utilized as a promising target for future development of RNAi-based therapy to treat cancers.

Decreased expression of hsa‑miR‑372 predicts poor prognosis in patients with gallbladder cancer by affecting chloride intracellular channel 1

It has been reported that hsa‑microRNA (miRNA/miR)‑372 functions as a tumor suppressor or oncogene in various digestive system tumors, however, its roles in gallbladder cancer (GBC) are yet to be established. The present study aimed to determine the expression and clinical relevance of hsa‑miR‑372 in GBC. The expression of hsa‑miR‑372 in 80 pairs of human GBC tissues and adjacent normal gallbladder tissues was measured by reverse transcription‑quantitative polymerase chain reaction. Subsequently, the associations between hsa‑miR‑372 expression levels and the clinicopathological characteristics of patients with GBC were determined using χ2 test. Furthermore, Kaplan‑Meier method and Cox regression analysis were performed to evaluate the association between hsa‑miR‑372 expression and the prognosis of patients with GBC. Furthermore, a dual‑luciferase reporter assay and western blot analysis were performed to predict and verify the target gene of hsa‑miR‑372. The results demonstrated that markedly lower hsa‑miR‑372 expression was observed in GBC tissues, which was associated with poor prognosis in patients with GBC. Downregulated expression of hsa‑miR‑372 was negatively associated with tumor histological grade, tumor‑node‑metastasis stage, lymph node metastasis and distant metastasis, however, no association was observed between reduced hsa‑miR‑372 expression and patient gender, age, tumor size and gallbladder stones. Multivariate Cox regression analysis revealed that hsa‑miR‑372 expression, histological grade and lymph node metastasis were independent prognostic factors for overall survival in patients with GBC. Chloride intracellular channel 1 (CLIC1) was previously reported to be an effective biomarker for predicting the prognosis of GBC. Notably, the results of the present study indicated that CLIC1 may be a direct target gene of hsa‑miR‑372. In conclusion, the current study provides the first statistically convincing evidence that downregulation of hsa‑miR‑372 may occur in GBC tissues, which may be associated with aggressive and progressive tumor behavior by affecting CLIC1 expression.

KIF26B, a novel oncogene, promotes proliferation and metastasis by activating the VEGF pathway in gastric cancer

Tumor metastasis is the main reason of cancer-related death for gastric cancer (GC) patients and gene expression microarray data indicate that kinesin family member 26B (KIF26B) is one of the most upregulated genes in metastatic GC samples. Specifically, KIF26B expression was upregulated in a stepwise manner from non-tumorous gastric mucosa, primary GC tissues without metastasis, via primary GC tissues with metastasis, to secondary lymph node metastatic (LNM) foci. Increased expression of KIF26B was correlated with tumor size, positive LNM or distant metastases and poor prognosis. KIF26B, negatively regulated by miR-372, promoted GC cell proliferation and metastasis in vitro and in vivo. Mechanistic investigations confirmed that the main target of KIF26B was the vascular endothelial growth factor (VEGF) signaling pathway, particularly by inhibition or overexpression of VEGFA, PXN, FAK, PIK3CA, BCL2 and CREB1. Thus, KIF26B, a novel oncogene regulated by miR-372, promotes proliferation and metastasis through the VEGF pathway in GC.

MiR-520b as a novel molecular target for suppressing stemness phenotype of head-neck cancer by inhibiting CD44

Cancer stem cells preferentially acquire the specific characteristics of stress tolerance and high mobility, allowing them to progress to a therapy-refractive state. To identify a critical molecule to regulate cancer stemness is indispensable to erratically cure cancer. In this study, we identified miR-520b as a novel molecular target to suppress head-neck cancer (HNC) with stemness phenotype. MiR-520b inhibited cellular migration and invasion via the mechanism of epithelial-mesenchymal transition. It also sensitized cells to therapeutic drug and irradiation. Significantly, miR-520b suppressed spheroid cell formation, as well as reduced expressions of multiple stemness regulators (Nestin, Twist, Nanog, Oct4). The CD44 molecule was identified as a direct target of miR-520b, as shown by the reverse correlative expressions, the response to miR-520 modulation, the luciferase reporter assay, and the functional rescue analyses. These cellular results were confirmed by a tumor xenograft mice study. Administration of miR-520b dramatically restrained tumorigenesis and liver colonization. Conversely, miR-520b silencing led to an acceleration of tumor growth. Taken together, our study demonstrated that miR-520b inhibits the malignancy of HNC through regulation of cancer stemness conversion by targeting CD44. MiR-520b may serve as an emerging therapeutic target that may be further developed for the intervention of refractory HNC.

HIF-1α promoted vasculogenic mimicry formation in hepatocellular carcinoma through LOXL2 up-regulation in hypoxic tumor microenvironment

Background

The incidence and mortality rates of hepatocellular carcinoma (HCC) have steadily increased in recent years. A hypoxic microenvironment is one of the most important characteristics of solid tumors which has been shown to promote tumor metastasis, epithelial-mesenchymal transition and angiogenesis. Epithelial-mesenchymal transition and vasculogenic mimicry have been regarded as crucial contributing factors to cancer progression. HIF-1α functions as a master transcriptional regulator in the adaptive response to hypoxia. Lysyl oxidases like 2 (LOXL2) is a member of the lysyl oxidase family, which main function is to catalyze the covalent cross-linkages of collagen and elastin in the extracellular matrix. Recent work has demonstrated that HIF-1α promotes the expression of LOXL2, which is believed to amplify tumor aggressiveness. LOXL2 has shown to promote metastasis and is correlated with poor prognosis in hepatocellular carcinoma. The purpose of our study is to explore the role of HIF-1α in progression and metastasis of hepatocellular carcinoma by promoting the expression of LOXL2 as well as the potential regulatory mechanism.

Methods

HIF-1α, LOXL2 expression and CD31/periodic acid-Schiff double staining in HCC patient samples were examined by immunohistochemical staining. shRNA plasmids against HIF-1α was used to determine whether LOXL2 been increased by HIF-1α. We monitored a series of rescue assays to demonstrate our hypothesis that LOXL2 is required and sufficient for HIF-1α induced EMT and VM formation, which mediates cellular transformation and takes effect in cellular invasion. Then we performed GeneChip® Human Transcriptome Array (HTA) 2.0 in HepG2 cells, HepG2 cells overexpressed LOXL2 and HepG2 cells treated with CoCl₂.

Results

In clinical HCC tissues, it confirmed a positive relationship between HIF-1α and LOXL2 protein. Importantly, HIF-1α and LOXL2 high expression and the presence of vasculogenic mimicry were correlated to poor prognosis. HIF-1α was found to induce EMT, HCC cell migration, invasion and VM formation by regulating LOXL2. The results of microarray assays were analyzed.

Conclusion

HIF-1α plays an important role in the development of HCC by promoting HCC metastasis, EMT and VM through up-regulating LOXL2. This study highlights the potential therapeutic value of targeting LOXL2 for suppression of HCC metastasis and progression.

Electronic supplementary material

The online version of this article (doi:10.1186/s13046-017-0533-1) contains supplementary material, which is available to authorized users.

MiR-372-3p promotes cell growth and metastasis by targeting FGF9 in lung squamous cell carcinoma

The aim of this study was to study the role of miR‐372‐3p in lung squamous cell carcinoma (LSCC) cell proliferation and invasion by suppressing FGF9. RT‐PCR was used to determine miR‐372‐3p and FGF9 mRNA expression in tissues and cells. Western blot was used to determine FGF9 expression in tissues and NCI‐H520 cell line. Dual luciferase reporter gene assay was conducted to confirm that FGF9 can be directly targeted by miR‐372‐3p. MTT, colony formation assays were conducted to investigate the effects of ectopic miR‐372‐3p and FGF9 expression on NCI‐H520 cell growth. Flow cytometry was used to analyze the influence of miR‐372‐3p and FGF9 expression on cell cycle distribution and apoptosis. Transwell assay was also conducted to see the effects of miR‐372‐3p and FGF9 expression on NCI‐H520 cell invasiveness. MiR‐372‐3p was found significantly overexpressed in both LSCC tissues and cell lines, whereas FGF9 mRNA was found underexpressed in LSCC tissues. MiR‐372‐3p directly bound to wild‐type FGF9 mRNA 3′UTR, therefore led to the reduction in FGF9 expression. The upregulation of FGF9 or the downregulation of miR‐372‐3p substantially retarded LSCC cell growth, mitosis, and invasion. MiR‐372‐3p enhanced LSCC cell proliferation and invasion through inhibiting FGF9.

BCIP: a gene-centered platform for identifying potential regulatory genes in breast cancer

Breast cancer is a disease with high heterogeneity. Many issues on tumorigenesis and progression are still elusive. It is critical to identify genes that play important roles in the progression of tumors, especially for tumors with poor prognosis such as basal-like breast cancer and tumors in very young women. To facilitate the identification of potential regulatory or driver genes, we present the Breast Cancer Integrative Platform (BCIP, http://omics.bmi.ac.cn/bcancer/). BCIP maintains multi-omics data selected with strict quality control and processed with uniform normalization methods, including gene expression profiles from 9,005 tumor and 376 normal tissue samples, copy number variation information from 3,035 tumor samples, microRNA-target interactions, co-expressed genes, KEGG pathways, and mammary tissue-specific gene functional networks. This platform provides a user-friendly interface integrating comprehensive and flexible analysis tools on differential gene expression, copy number variation, and survival analysis. The prominent characteristic of BCIP is that users can perform analysis by customizing subgroups with single or combined clinical features, including subtypes, histological grades, pathologic stages, metastasis status, lymph node status, ER/PR/HER2 status, TP53 mutation status, menopause status, age, tumor size, therapy responses, and prognosis. BCIP will help to identify regulatory or driver genes and candidate biomarkers for further research in breast cancer.

MicroRNA-372 inhibits endometrial carcinoma development by targeting the expression of the Ras homolog gene family member C (RhoC)

Here we explore the role of microRNA-372 (miR-372) in tumorigenesis and development of endometrial adenocarcinoma (EC) and analyze the underlying mechanism. We found that miR-372 expression is much lower in EC than normal endometrial specimens. Cell function experiments demonstrated that miR-372 overexpression suppressed cell proliferation, migration, and invasion, and led to a G1 phase arrest and promoted the apoptosis of endometrial carcinoma cells in vitro. The nude mouse xenograft assay demonstrated that miR-372 overexpression suppressed tumor growth. RT-PCR and Western blot assays detected the expression of known targets of miR-372 in other malignant tumors and found Cyclin A1 and Cyclin-dependent Kinase 2 (CDK2) was downregulated by miR-372. Bioinformatic predictions and dual-luciferase reporter assays found that RhoC was a possible target of miR-372. RT-PCR and Western blot assays demonstrated that miR-372 transfection reduced the expression of RhoC, matrix metalloproteinase 2 (MMP2) and MMP9, while it increased the expression of cleaved poly (ADP ribose) polymerase (PARP) and bcl-2-associated X protein (Bax). The cell function experiments that transfected siRNA with RhoC showed the same trend as those which were transfected with miR-372. Taken together, our results demonstrated for the first time that miR-372 suppresses tumorigenesis and the development of EC; RhoC is a new and potentially important therapeutic target.

Suppression of ATAD2 inhibits hepatocellular carcinoma progression through activation of p53- and p38-mediated apoptotic signaling

The ATPase family, AAA domain containing 2 (ATAD2) is highly expressed in multiple cancers. We aim to understand the clinical and biological significance of ATAD2 over-expression in hepatocellular carcinoma (HCC), as a means to validate it as a therapeutic target in HCC. We demonstrated that ATAD2 was over-expressed in HCC patients, where high ATAD2 levels were significantly correlated with aggressive phenotypes such as high AFP levels, advanced tumor stages, and vascular invasion. Using RNA interference, suppression of ATAD2 in HCC cell lines decreased cell viability, migration, and invasion, and induced apoptosis in vitro. Furthermore, we identified p53 and p38 as key proteins that mediate apoptosis induced by ATAD2 suppression. In HCC cells, we demonstrated that ATAD2 directly interacted with MKK3/6, which prevented p38 activation and therefore inhibited p38-mediated apoptosis. In vivo, suppression of ATAD2 impaired the growth of HepG2 and Hep3B subcutaneous xenografts, accompanied by enhanced apoptosis and p-p53 and p-p38 levels. Our results validate that ATAD2 is an important negative regulator of apoptosis, and that neutralizing its activity has promising anti-tumor effects in HCC cells.

An ANCCA/PRO2000-miR-520a-E2F2 regulatory loop as a driving force for the development of hepatocellular carcinoma

Hepatocellular carcinoma (HCC) is one of the most common malignancies in Asia especially in China. We previously identified that ANCCA/PRO2000 as an important proliferation-associated protein predicted poor prognosis of patients with HCC. However, the molecular mechanisms of ANCCA/PRO2000 leading to hepatocarcinogenesis and progression are still obscure. In the present study, we found that ANCCA/PRO2000 overexpression in HCC specimens correlated with aggressive tumor behavior and poor survival. Furthermore, ANCCA/PRO2000 exerts strong oncogenic function in HCC and promotes cell proliferation by regulating E2F2 expression, a critical cell cycle regulator. Notably, miR-520a is an intermediate regulator between ANCCA/PRO2000 and E2F2. Mechanistically, ANCCA/PRO2000 not only interacts with E2F2 but also negatively regulates miR-520a that inhibits E2F2 to cooperatively promote in vitro and in vivo growth of HCC cells. Moreover, we demonstrated that ANCCA/PRO2000 enhances the migratory capacity of HCC cells partially by suppressing ERO1L and G3BP2 expression. Additional research identified that miR-372, as a prognostic factor for HCC, could directly target ANCCA/PRO2000. Our results suggest the ANCCA/PRO2000-miR-520a-E2F2 regulatory loop as a driving force for HCC development and ANCCA/PRO2000 as a potential therapeutic target for HCC.

Clinical and Prognostic Significance of ANCCA in Squamous Cell Lung Carcinoma Patients

BACKGROUND AND AIMS

AAA+ nuclear coregulatory cancer associated (ANCCA) has been demonstrated as playing important roles in diverse biological processes including tumorigenesis. However, the clinical and prognostic significance of ANCCA in squamous cell lung carcinoma (SCLC) patients is still unknown. The aim of this study is to identify the role of ANCCA in SCLC patients.

METHODS

ANCCA mRNA and protein expressions were detected in SCLC tissues and cell lines by real-time PCR and Western blot. We examined the ANCCA protein expression in 152 SCLC samples by immunohistochemistry and analyzed the association between the expression of ANCCA protein and clinicopathological characteristics of SCLC patients.

RESULTS

ANCCA mRNA and protein expression are increased in SCLC tissues and cell lines. Moreover, ANCCA protein overexpression was associated with differentiated degree, clinical stage, lymph node metastasis, and distant metastasis. In uni- and multivariate analyses, ANCCA protein overexpression was an independent poor prognostic factor for SCLC patients.

CONCLUSIONS

ANCCA act as a potential biomarker for therapeutic strategy and prognostic prediction for SCLC.