MicroRNA-33a mediates the regulation of high mobility group AT-hook 2 gene (HMGA2) by thyroid transcription factor 1 (TTF-1/NKX2-1)

Circ_0004676 exacerbates triple-negative breast cancer progression through regulation of the miR-377-3p/E2F6/PNO1 axis

BACKGROUND

The significant roles of circular RNAs (circRNAs) in different cancers and diseases have been reported. We now focused on the possible role of a newly recognized circRNA, circ_0004674 in triple-negative breast cancer (TNBC), and the related downstream mechanism.

METHODS

The expression of circ_0004674 in TNBC tissues and cells was determined followed by analysis of the correlation between circ_0004674 and TNBC patients' prognosis. The interaction between circ_0004674, miR-377-3p, E2F6, and PNO1 was then identified using bioinformatics analysis combined with FISH, RIP, RNA pull-down, RT-qPCR, and Western blot analysis. Using gain-of-function and loss-of-function methods, we analyzed the effect of circ_0004674, miR-377-3p, E2F6, and PNO1 on TNBC in vivo and in vitro.

RESULTS

Increased circ_0004674 and E2F6 but decreased miR-377-3p were observed in TNBC tissues and MDA-MB-231 TNBC cells, all of which findings were associated with poor prognosis in patients with TNBC. Silencing of circ_0004676 remarkably suppressed the proliferation, cell cycle progression, and migration of TNBC cells in vitro, as well as inhibiting tumorigenesis and metastasis in vivo. Additionally, circ_0004676 served as a sponge of miR-377-3p which bound to the transcription factor E2F6. In the presence of overexpression of circ_0004676, E2F6 expression and its target PNO1 expression were elevated, while miR-377-3p expression was decreased. Interestingly, overexpression of E2F6 could reverse the inhibitory effect on tumor growth caused by downregulation of circ_0004676.

CONCLUSION

Our study highlighted the carcinogenic effect of circ_0004676 on TNBC through regulation of the miR-377-3p/E2F6/PNO1 axis. 1. Circ_0004674 is highly expressed in TNBC tissues and cells. 2. Circ_0004674 upregulates the expression of E2F6 by sponging miR-377-3p. 3. E2F6 upregulates PNO1 by binding to the PNO1 promoter. 4. Circ_0004674 favors TNBC progression by regulating the miR-377-3p/E2F6/PNO1 axis. 5. This study provides a new target for the treatment of TNBC.

Single-cell RNA-seq uncovered hemocyte functional subtypes and their differentiational characteristics and connectivity with morphological subpopulations in Litopenaeus vannamei

Hemocytes play central roles in shrimp immune system, whereas whose subclasses have not yet been completely defined. At present, the morphological classification of hemocytes is inadequate to classify the complete hemocyte repertoire and elucidate the functions and differentiation and maturation processes. Based on single-cell RNA sequencing (scRNA-seq) of hemocytes in healthy Litopenaeus vannamei, combined with RNA-FISH and flow cytometric sorting, we identified three hemocyte clusters including TGase+ cells, CTL+ cells and Crustin+ cells, and further determined their functional properties, potential differentiation trajectory and correspondence with morphological subpopulations. The TGase+ cells were mainly responsible for the coagulation, exhibiting distinguishable characteristics of hyalinocyte, and appeared to be developmentally arrested at an early stage of hemocyte differentiation. The CTL+ cells and Crustin+ cells arrested at terminal stages of differentiation mainly participated in recognizing foreign pathogens and initiating immune defense responses, owning distinctive features of granule-containing hemocytes. Furthermore, we have revealed the functional sub-clusters of three hemocyte clusters and their potential differentiation pathways according to the expression of genes involved in cell cycle, cell differentiation and immune response, and the successive differentiation and maturation of hyalinocytes to granule-containing hemocytes have also mapped. The results revealed the diversity of shrimp hemocytes and provide new theoretical rationale for hemocyte classification, which also facilitate systematic research on crustacean immunity.

Induction of microRNA hsa-let-7d-5p, and repression of HMGA2, contribute protection against lipid accumulation in macrophage 'foam' cells

Accumulation of excess cholesterol and cholesteryl ester in macrophage 'foam' cells within the arterial intima characterises early 'fatty streak' atherosclerotic lesions, and is accompanied by epigenetic changes, including altered expression of microRNA sequences which determine of gene and protein expression. This study established that exposure to lipoproteins, including acetylated LDL, induced macrophage expression of microRNA hsa-let-7d-5p, a sequence previously linked with tumour suppression, and repressed expression of one of its target genes, high mobility group AT hook 2 (HMGA2). A let-7d-5p mimic repressed expression of HMGA2 (18%; p < 0.05) while a marked increase (2.9-fold; p < 0.05) in expression of HMGA2 was noted in the presence of let-7d-5p inhibitor. Under these conditions, let-7d-5p mimic significantly (p < 0.05) decreased total (10%), free (8%) and cholesteryl ester (21%) mass, while the inhibitor significantly (p < 0.05) increased total (29%) and free cholesterol (29%) mass, compared with the relevant controls. Let-7d-5p inhibition significantly (p < 0.05) increased endogenous biosynthesis of cholesterol (38%) and cholesteryl ester (39%) pools in macrophage 'foam' cells, without altering the cholesterol efflux pathway, or esterification of exogenous radiolabelled oleate. Let-7d-5p inhibition in sterol-loaded cells increased the level of HMGA2 protein (32%; p < 0.05), while SiRNA knockdown of this protein (29%; p < 0.05) resulted in a (21%, p < 0.05) reduction in free cholesterol mass. Thus, induction of let-7d-5p, and repression of its target HMGA2, in macrophages is a protective response to the challenge of increased cholesterol influx into these cells; dysregulation of this response may contribute to atherosclerosis and other disorders such as cancer.

MicroRNA-216b targets HK2 to potentiate autophagy and apoptosis of breast cancer cells via the mTOR signaling pathway

Patients suffering from breast cancer (BC) still have a poor response to treatments, even though early detection and improved therapy have contributed to a reduced mortality. Recent studies have been inspired on the association between microRNAs (miRs) and therapies of BC. The current study set out to investigate the role of miR-216b in BC, and further analyze the underlining mechanism. Firstly, hexokinase 2 (HK2) and miR-216b were characterized in BC tissues and cells by RT-qPCR and Western blot assay. In addition, the interaction between HK2 and miR-216b was analyzed using dual luciferase reporter assay. BC cells were further transfected with a series of miR-126b mimic or inhibitor, or siRNA targeting HK2, so as to analyze the regulatory mechanism of miR-216b, HK2 and mammalian target of rapamycin (mTOR) signaling pathway, and to further explore their regulation in BC cellular behaviors. The results demonstrated that HK2 was highly expressed and miR-216b was poorly expressed in BC cells and tissues. HK2 was also verified as a target of miR-216b with online databases and dual luciferase reporter assay. Functionally, miR-216b was found to be closely associated with BC progression via inactivating mTOR signaling pathway by targeting HK2. Moreover, cell viability, migration and invasion were reduced as a result of miR-216b upregulation or HK2 silencing, while autophagy, cell cycle arrest and apoptosis were induced. Taken together, our findings indicated that miR-216 down-regulates HK2 to inactivate the mTOR signaling pathway, thus inhibiting the progression of BC. Hence, this study highlighted a novel target for BC treatment.

Connecting Cholesterol Efflux Factors to Lung Cancer Biology and Therapeutics

Cholesterol is a foundational molecule of biology. There is a long-standing interest in understanding how cholesterol metabolism is intertwined with cancer biology. In this review, we focus on the known connections between lung cancer and molecules mediating cholesterol efflux. A major take-home lesson is that the roles of many cholesterol efflux factors remain underexplored. It is our hope that this article would motivate others to investigate how cholesterol efflux factors contribute to lung cancer biology.

HMGA2 as a Critical Regulator in Cancer Development

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

TENET 2.0: Identification of key transcriptional regulators and enhancers in lung adenocarcinoma

Lung cancer is the leading cause of cancer-related death and lung adenocarcinoma is its most common subtype. Although genetic alterations have been identified as drivers in subsets of lung adenocarcinoma, they do not fully explain tumor development. Epigenetic alterations have been implicated in the pathogenesis of tumors. To identify epigenetic alterations driving lung adenocarcinoma, we used an improved version of the Tracing Enhancer Networks using Epigenetic Traits method (TENET 2.0) in primary normal lung and lung adenocarcinoma cells. We found over 32,000 enhancers that appear differentially activated between normal lung and lung adenocarcinoma. Among the identified transcriptional regulators inactivated in lung adenocarcinoma vs. normal lung, NKX2-1 was linked to a large number of silenced enhancers. Among the activated transcriptional regulators identified, CENPA, FOXM1, and MYBL2 were linked to numerous cancer-specific enhancers. High expression of CENPA, FOXM1, and MYBL2 is particularly observed in a subgroup of lung adenocarcinomas and is associated with poor patient survival. Notably, CENPA, FOXM1, and MYBL2 are also key regulators of cancer-specific enhancers in breast adenocarcinoma of the basal subtype, but they are associated with distinct sets of activated enhancers. We identified individual lung adenocarcinoma enhancers linked to CENPA, FOXM1, or MYBL2 that were associated with poor patient survival. Knockdown experiments of FOXM1 and MYBL2 suggest that these factors regulate genes involved in controlling cell cycle progression and cell division. For example, we found that expression of TK1, a potential target gene of a MYBL2-linked enhancer, is associated with poor patient survival. Identification and characterization of key transcriptional regulators and associated enhancers in lung adenocarcinoma provides important insights into the deregulation of lung adenocarcinoma epigenomes, highlighting novel potential targets for clinical intervention.

Paired Box 9 (PAX9), the RNA polymerase II transcription factor, regulates human ribosome biogenesis and craniofacial development

Dysregulation of ribosome production can lead to a number of developmental disorders called ribosomopathies. Despite the ubiquitous requirement for these cellular machines used in protein synthesis, ribosomopathies manifest in a tissue-specific manner, with many affecting the development of the face. Here we reveal yet another connection between craniofacial development and making ribosomes through the protein Paired Box 9 (PAX9). PAX9 functions as an RNA Polymerase II transcription factor to regulate the expression of proteins required for craniofacial and tooth development in humans. We now expand this function of PAX9 by demonstrating that PAX9 acts outside of the cell nucleolus to regulate the levels of proteins critical for building the small subunit of the ribosome. This function of PAX9 is conserved to the organism Xenopus tropicalis, an established model for human ribosomopathies. Depletion of pax9 leads to craniofacial defects due to abnormalities in neural crest development, a result consistent with that found for depletion of other ribosome biogenesis factors. This work highlights an unexpected layer of how the making of ribosomes is regulated in human cells and during embryonic development.

Role of microRNA-33a in malignant cells

Cancer causes most of the mortality and morbidity worldwide, with a significant increase in incidence during recent years. MicroRNAs (miRNAs/miRs) are non-coding small RNAs capable of regulating gene expression. They regulate crucial cellular processes, including proliferation, differentiation, metastasis and apoptosis. Therefore, abnormal miRNA expression is associated with multiple diseases, including cancer. There are two types of cancer-associated miRNAs, oncogenic and tumor suppressor miRNAs, depending on their roles and expression patterns in cancer. Accordingly, miRNAs are considered to be targets for cancer prevention and treatment. miR-33a controls cellular cholesterol uptake and synthesis, which are both closely associated with carcinogenesis. The present review thoroughly describes the roles of miR-33a in more than a dozen types of cancer and the underlying mechanisms. Accordingly, the present review may serve as a guide for researchers studying the involvement of miR-33a in diverse cancer settings.

HMGA Proteins in Hematological Malignancies

The high mobility group AT-Hook (HMGA) proteins are a family of nonhistone chromatin remodeling proteins known as "architectural transcriptional factors". By binding the minor groove of AT-rich DNA sequences, they interact with the transcription apparatus, altering the chromatin modeling and regulating gene expression by either enhancing or suppressing the binding of the more usual transcriptional activators and repressors, although they do not themselves have any transcriptional activity. Their involvement in both benign and malignant neoplasias is well-known and supported by a large volume of studies. In this review, we focus on the role of the HMGA proteins in hematological malignancies, exploring the mechanisms through which they enhance neoplastic transformation and how this knowledge could be exploited to devise tailored therapeutic strategies.

High Mobility Group A (HMGA): Chromatin Nodes Controlled by a Knotty miRNA Network

High mobility group A (HMGA) proteins are oncofoetal chromatin architectural factors that are widely involved in regulating gene expression. These proteins are unique, because they are highly expressed in embryonic and cancer cells, where they play a relevant role in cell proliferation, stemness, and the acquisition of aggressive tumour traits, i.e., motility, invasiveness, and metastatic properties. The HMGA protein expression levels and activities are controlled by a connected set of events at the transcriptional, post-transcriptional, and post-translational levels. In fact, microRNA (miRNA)-mediated RNA stability is the most-studied mechanism of HMGA protein expression modulation. In this review, we contribute to a comprehensive overview of HMGA-targeting miRNAs; we provide detailed information regarding HMGA gene structural organization and a comprehensive evaluation and description of HMGA-targeting miRNAs, while focusing on those that are widely involved in HMGA regulation; and, we aim to offer insights into HMGA-miRNA mutual cross-talk from a functional and cancer-related perspective, highlighting possible clinical implications.

MiR-33a Controls hMSCS Osteoblast Commitment Modulating the Yap/Taz Expression Through EGFR Signaling Regulation

Mesenchymal stromal cells (hMSCs) display a pleiotropic function in bone regeneration. The signaling involved in osteoblast commitment is still not completely understood, and that determines the failure of current therapies being used. In our recent studies, we identified two miRNAs as regulators of hMSCs osteoblast differentiation driving hypoxia signaling and cytoskeletal reorganization. Other signalings involved in this process are epithelial to mesenchymal transition (EMT) and epidermal growth factor receptor (EGFR) signalings through the regulation of Yes-associated protein (YAP)/PDZ-binding motif (TAZ) expression. In the current study, we investigated the role of miR-33a family as a (i) modulator of YAP/TAZ expression and (ii) a regulator of EGFR signaling during osteoblast commitments. Starting from the observation on hMSCs and primary osteoblast cell lines (Nh-Ost) in which EMT genes and miR-33a displayed a specific expression, we performed a gain and loss of function study with miR-33a-5p and 3p on hMSCs cells and Nh-Ost. After 24 h of transfections, we evaluated the modulation of EMT and osteoblast genes expression by qRT-PCR, Western blot, and Osteoimage assays. Through bioinformatic analysis, we identified YAP as the putative target of miR-33a-3p. Its role was investigated by gain and loss of function studies with miR-33a-3p on hMSCs; qRT-PCR and Western blot analyses were also carried out. Finally, the possible role of EGFR signaling in YAP/TAZ modulation by miR-33a-3p expression was evaluated. Human MSCs were treated with EGF-2 and EGFR inhibitor for different time points, and qRT-PCR and Western blot analyses were performed. The above-mentioned methods revealed a balance between miR-33a-5p and miR-33a-3p expression during hMSCs osteoblast differentiation. The human MSCs phenotype was maintained by miR-33a-5p, while the maintenance of the osteoblast phenotype in the Nh-Ost cell model was permitted by miR-33a-3p expression, which regulated YAP/TAZ through the modulation of EGFR signaling. The inhibition of EGFR blocked the effects of miR-33a-3p on YAP/TAZ modulation, favoring the maintenance of hMSCs in a committed phenotype. A new possible personalized therapeutic approach to bone regeneration was discussed, which might be mediated by customizing delivery of miR-33a in simultaneously targeting EGFR and YAP signaling with combined use of drugs.

Downregulation of long noncoding RNA CRNDE suppresses drug resistance of liver cancer cells by increasing microRNA-33a expression and decreasing HMGA2 expression

At present, some researches have revealed the participation of long noncoding RNAs (lncRNAs) in liver cancer, but few of them have mentioned the role of CRNDE in drug resistance of liver cancer. Hence, this study is conducted to understand the role of CRNDE on liver cancer by regulating microRNA-33a (miR-33a) and high mobility group protein A2 (HMGA2) in liver cancer. First, drug-resistance model (HepG2 and BEL-7402) of human liver cancer cells was established. Then, CRNDE expression in drug-resistant cell lines (HepG2/adriamycin [ADM], BEL-7402/ADM) and parental cell lines (HepG2, BEL-7402) was detected. Furthermore, HepG2/ADM and BEL-7402/ADM cell lines with poor CRNDE expression or miR-33a overexpression was constructed. Next, drug-resistance index was calculated, and cell proliferation, apoptosis, migration, and invasion were detected, respectively. Then, the growth of tumor was observed in nude mice. Finally, the binding relationship between CRNDE and miR-33a and the targeting relationship between miR-33a and HMGA2 were verified. LncRNA CRNDE expressed highly in drug-resistant cells of liver cancer. Downregulated CRNDE and upregulated miR-33a-inhibited cells drug-resistance and promoted their apoptosis in liver cancer drug-resistant cells. CRNDE adsorbing and inhibiting miR-33a to promote HMGA2 in liver cancer drug-resistant cells by acting as a ceRNA. Silencing CRNDE or up-regulating miR-33a inhibited tumor growth of liver cancer in vivo. Our study provides evidence that downregulated CRNDE could upregulate miR-33a and inhibit HMGA2 expression, thus significantly promotes apoptosis of liver cancer cells and inhibiting its proliferation, migration, invasion and drug resistance.

Inhibition of microRNA-103 attenuates inflammation and endoplasmic reticulum stress in atherosclerosis through disrupting the PTEN-mediated MAPK signaling

Atherosclerosis (AS), a chronic disorder of large arteries, is the underlying pathological process of heart disease and stroke. Former researchers have found that microRNAs (miRs) are involved in the several key processes of AS. Apolipoprotein E knockout (ApoE^-/- ) mice fed a high-fat-diet (HFD) to establish AS model. The expression of miR-103 was characterized in the mice model. The effects of miR-103 on inflammation and endoplasmic reticulum stress (ERS) were analyzed when the expression of miR-103 was inhibited in ApoE ^-/- mice fed an HFD and human aortic endothelial cells (HAECs) exposed to oxidized low-density lipoprotein (ox-LDL). The relationship between miR-103 and phosphatase and tensin homolog (PTEN) was identified by luciferase activity detection and real-time quantitative polymerase chain reaction (RT-qPCR). Gain- and loss-function approaches were further applied for investigating the regulatory effects of miR-103 and PTEN on ERS. Role of MAPK signaling was then analyzed using PD98059 to block this pathway. miR-103 was highly expressed in the ApoEApoE ^-/- mice fed an HFD. Downregulation of miR-103 suppressed inflammation and ERS in endothelial cells isolated from ApoE ^-/- mice fed a HFD and ox-LDL-exposed HAECs. In addition, miR-103 can target PTEN and downregulate its expression. Overexpression of PTEN reversed the miR-103-induced activation of MAPK signaling. Moreover, PTEN upregulation or MAPK signaling inhibition ease miR-103-induced inflammation and ERS in vivo and in vitro. Thus, miR-103 depletion restrains the progression of AS through blocking PTEN-mediated MAPK signaling.

Long noncoding RNA LINC00473 drives the progression of pancreatic cancer via upregulating programmed death-ligand 1 by sponging microRNA-195-5p

Pancreatic cancer (PC) is a great health burden to patients owing to its poor overall survival rate. Long noncoding RNAs (lncRNAs) interact with microRNAs (miRs) to participate in tumorigenesis. Therefore, we aim to uncover the role and related mechanism of LINC00473 in PC through the modulation of miR-195-5p and programmed death-ligand 1 (PD-L1). Increased LINC00473 and PD-L1 but declined miR-195-5p were determined in PC tissues and cell lines, and it was found that LINC00473 mainly situated in the cytoplasm. Also, miR-195-5p was verified to bind with both LINC00473 and PD-L1. Next, with the aim to examine the ability of LINC00473, miR-195-5p, and PD-L1 on the PC progression, the expression of LINC00473, miR-195-5p and PD-L1 were altered with mimics, inhibitors, overexpression vectors or siRNAs in PC cells and cocultured CD8⁺ T cells. It was demonstrated that LINC00473 sponged miR-195-5p to upregulate PD-L1 expression. More important, the obtained results revealed that LINC00473 silencing or miR-195-5p upregulation elevated the expression of Bcl-2 associated X protein (Bax), interferon (IFN)-γ, and interleukin (IL)-4 but reduced the expression of B-cell lymphoma-2 (Bcl-2), matrix metalloproteinase (MMP)-2, MMP-9, and IL-10, thus inducing the enhancement of the apoptosis as along with the inhibition of proliferation, invasion, and migration of the PC cells. LINC00473 silencing or miR-195-5p elevation activated the CD8⁺ T cells. Taken together, LINC00473 silencing blocked the PC progression through enhancing miR-195-5p-targeted downregulation of PD-L1. This finding offers new therapeutic options for treating this devastating disease.

Mechanistic Study of TTF-1 Modulation of Cellular Sensitivity to Cisplatin

The lung lineage master regulator gene, Thyroid Transcription Factor-1 (TTF-1, also known as NKX2-1), is used as a marker by pathologists to identify lung adenocarcinomas since TTF-1 is expressed in 60 ~ 70% of lung ADs. Much research has been conducted to investigate roles of TTF-1 in lung cancer biology. But, how it modulates cellular chemosensitivity remains poorly characterized. Our study shows that TTF-1 sensitizes the KRAS-mutated A549 and NCI-H460 lung cancer cells to cisplatin, a common chemotherapy used to treat lung cancer. This chemosensitization activity does not appear to be mediated by a TTF-1-imposed alteration on nucleotide excision repair. Mechanistically, TTF-1 induced a reduction in p-AKT (S473), which in turn activated glycogen synthase kinase 3 (GSK3) and reduced β-catenin. Intriguingly, in the EGFR-mutated NCI-H1975 and HCC827 cells, TTF-1 desensitized these cells to cisplatin; concomitantly, TTF-1 conferred an increase in p-AKT. Finally, the conditioned media of TTF-1-transefected cells sensitized TTF-1- cells to cisplatin, implicating that the TTF-1-driven chemosensitization activity may be dually pronged in both intracellular and extracellular compartments. In short, this study highlights the enigmatic activities of TTF-1 in lung cancer, and calls for future research to optimally manage chemotherapy of patients with TTF-1+ lung ADs.

The effects of tracheal occlusion on Wnt signaling in a rabbit model of congenital diaphragmatic hernia

PURPOSE

Tracheal occlusion (TO) reverses pulmonary hypoplasia (PH) in congenital diaphragmatic hernia (CDH), but its mechanism of action remains poorly understood. Wnt signaling plays a critical role in lung development, but few studies exist. The purpose of our study was to a) confirm that our CDH rabbit model produced PH which was reversed by TO and b) determine the effects of CDH +/- TO on Wnt signaling.

METHODS

CDH was created in fetal rabbits at 23 days, TO at 28 days, and lung collection at 31 days. Lung body weight ratio (LBWR) and mean terminal bronchiole density (MTBD) were determined. mRNA and miRNA expression was determined in the left lower lobe using RT-qPCR.

RESULTS

Fifteen CDH, 15 CDH + TO, 6 sham CDH, and 15 controls survived and were included in the study. LBWR was low in CDH, while CDH + TO was similar to controls (p = 0.003). MTBD was higher in CDH fetuses and restored to control levels in CDH + TO (p < 0.001). Reference genes TOP1, SDHA, and ACTB were consistently expressed within and between treatment groups. miR-33 and MKI67 were increased, and Lgl1 was decreased in CDH + TO.

CONCLUSION

TO reversed pulmonary hypoplasia and stimulated early Wnt signaling in CDH fetal rabbits.

TYPE OF STUDY

Basic science, prospective.

LEVEL OF EVIDENCE

II.

MicroRNA-135a participates in the development of astrocytes derived from bacterial meningitis by downregulating HIF-1α

Accumulating evidence has highlighted the potential of microRNAs (miRs) as biomarkers in various human diseases. However, the roles of miRs in bacterial meningitis (BM), a severe infectious condition, still remain unclear. Thus, the present study aimed to investigate the effects of miR-135a on proliferation and apoptosis of astrocytes in BM. Neonatal rats were injected with Streptococcus pneumoniae to establish the BM model. The expression of miR-135a and hypoxia-inducible factor 1α (HIF-1α) in the BM rat models were characterized, followed by determination of their interaction. Using gain- and loss-of-function approaches, the effects of miR-135a on proliferation, apoptosis, and expression of glial fibrillary acidic protein (GFAP), in addition to apoptosis-related factors in astrocytes were examined accordingly. The regulatory effect of HIF-1α was also determined along with the overexpression or knockdown of HIF-1α. The results obtained indicated that miR-135a was poorly expressed, whereas HIF-1α was highly expressed in the BM rat models. In addition, restored expression levels of miR-135a were determined to promote proliferation while inhibiting the apoptosis of astrocytes, along with downregulated Bax and Bad, as well as upregulated Bcl-2, Bcl-XL, and GFAP. As a target gene of miR-135a, HIF-1α expression was determined to be diminished by miR-135a. The upregulation of HIF-1α reversed the miR-135a-induced proliferation of astrocytes. Taken together, the key findings of the current study present evidence suggesting that miR-135a can downregulate HIF-1α and play a contributory role in the development of astrocytes derived from BM, providing a novel theoretical perspective for BM treatment approaches.

RASSF1C regulates miR-33a and EMT marker gene expression in lung cancer cells

RASSF1C functions as an oncogene in lung cancer cells by stimulating proliferation and migration, and reducing apoptosis. Further, RASSF1C up-regulates important protein-coding and non-coding genes involved in lung cancer cell growth, including the stem cell self-renewal gene, piwil1, and small noncoding PIWI-interacting RNAs (piRNAs). In this article, we report the identification of microRNAs (miRNAs) that are modulated in lung cancer cells over-expressing RASSF1C. A lung cancer-specific miRNA PCR array screen was performed to identify RASSF1C target miRNA-coding genes using RNA isolated from the lung cancer cell line H1299 stably over-expressing RASSF1C and corresponding control. Several modulated miRNA genes were identified that are important in cancer cell proliferation and survival. Among the miRNAs down-regulated by RASSF1C is miRNA-33a-5p (miRNA-33a), which functions as a tumor suppressor in lung cancer cells. We validated that over-expression of RASSF1C down-regulates miR-33a expression and RASSF1C knockdown up-regulates miR-33a expression. We found that RASSF1C over-expression also increases β-catenin, vimentin, and snail protein levels in cells over-expressing miR-33a. In addition, we found that RASSF1C up-regulates the expression of ABCA1 mRNA which is a known target of miR-33a. Our findings suggest that RASSF1C may promote lung epithelial mesenchymal transition (EMT), resulting in the development of a lung cancer stem cell phenotype, progression, and metastasis, in part, through modulation of miR-33a expression. Our findings reveal a new mechanistic insight into how RASSF1C functions as an oncogene.

MicroRNA 33 Regulates the Population of Peripheral Inflammatory Ly6Chigh Monocytes through Dual Pathways

MicroRNA 33 (miR-33) targets ATP-binding cassette transporter A1 (ABCA1), and its deficiency increases serum high-density lipoprotein (HDL)-cholesterol (HDL-C) and ameliorates atherosclerosis. Although we previously reported that miR-33 deficiency increased peripheral Ly6C^high monocytes on an ApoE-deficient background, the effect of miR-33 on the monocyte population has not been fully elucidated, especially in a wild-type (WT) background. We found that Ly6C^high monocytes in miR-33^−/− mice were decreased in peripheral blood and increased in bone marrow (BM). Expansion of myeloid progenitors and decreased apoptosis in Lin⁻ Sca1⁺ c-Kit⁺ (LSK) cells were observed in miR-33^−/− mice. A BM transplantation study and competitive repopulation assay revealed that hematopoietic miR-33 deficiency caused myeloid expansion and increased peripheral Ly6C^high monocytes and that nonhematopoietic miR-33 deficiency caused reduced peripheral Ly6C^high monocytes. Expression of high-mobility group AT-hook 2 (HMGA2) targeted by miR-33 increased in miR-33-deficient LSK cells, and its knockdown abolished the reduction of apoptosis. Transduction of human apolipoprotein A1 and ABCA1 in WT mouse liver increased HDL-C and reduced peripheral Ly6C^high monocytes. These data indicate that miR-33 deficiency affects distribution of inflammatory monocytes through dual pathways. One pathway involves the enhancement of Hmga2 expression in hematopoietic stem cells to increase Ly6C^high monocytes, and the other involves the elevation of HDL-C to decrease peripheral Ly6C^high monocytes.

Immunohistochemical Biomarkers in Thyroid Pathology

The application of immunohistochemistry to the diagnosis of thyroid lesions has increased as new biomarkers have emerged. In this review, we discuss the biomarkers that are critical for accurate diagnosis, prognosis, and management. Immunohistochemical markers are used to confirm that an unusual tumor in the thyroid is indeed of thyroid origin, either of follicular epithelial or C-cell differentiation; the various mimics include nonthyroidal lesions such as parathyroid tumors, paragangliomas, thymic neoplasms, and metastatic malignancies. Tumors of thyroid follicular epithelial cells can be further subclassified using a number of immunohistochemical biomarkers that can distinguish follicular-derived from C-cell lesions and others that support malignancy in borderline cases. The use of mutation-specific antibodies can distinguish papillary carcinomas harboring a BRAF^V600E mutation from RAS-like neoplasms. Immunostains have been developed to further identify molecular alterations underlying tumor development, including some rearrangements. Altered expression of several biomarkers that are known to be epigenetically modified in thyroid cancer can be used to assist in predicting more aggressive behavior such as a propensity to develop locoregional lymphatic spread. Immunohistochemistry can assist in identifying lymphatic and vascular invasion. Biomarkers can be applied to determine dedifferentiation and to further classify poorly differentiated and anaplastic carcinomas. The rare tumors associated with genetic predisposition to endocrine neoplasia can also be identified using some immunohistochemical stains. The application of these ancillary tools allows more accurate diagnosis and better understanding of pathogenesis while improving prediction and prognosis for patients with thyroid neoplasms.

Thyroid transcription factor 1 enhances cellular statin sensitivity via perturbing cholesterol metabolism

We have discovered an unexpected connection between a critical lung development and cancer gene termed thyroid transcription factor 1 (TTF-1 also known as NKX2-1) and cholesterol metabolism. Our published work implicates that TTF-1 positively regulates miR-33a which is known to repress ATP-binding cassette transporter 1 (ABCA1) and thus its cholesterol efflux activity. We set out to demonstrate that a higher TTF-1 expression would presumably inhibit cholesterol efflux and consequently raise intracellular cholesterol level. Surprisingly, raising TTF-1 expression actually lowers intracellular cholesterol level, which, we believe, is attributed to a direct transactivation of ABCA1 by TTF-1. Subsequently, we show that lung cancer cells primed with a TTF-1-driven decrease of cholesterol were more vulnerable to simvastatin, a frequently prescribed cholesterol biosynthesis inhibitor. In view of the fact that pathologists routinely interrogate human lung cancers for TTF-1 immunopositivity to guide diagnosis and the prevalent use of statins, TTF-1 should be further investigated as a putative biomarker of lung cancer vulnerability to statins.

miR-302a-5p/367-3p-HMGA2 axis regulates malignant processes during endometrial cancer development

BACKGROUND

Metastasis is one of the main reasons for treatment failure in endometrial cancer. Notably, high mobility group AT-hook 2 (HMGA2) has been recognized as a driving factor of tumour metastasis. microRNAs (miRNAs) are powerful posttranscriptional regulators of HMGA2.

METHODS

The binding sites of miR-302a-5p and miR-367-3p on HMGA2 mRNA were identified using bioinformatics prediction software and were validated via luciferase assay. The expression levels of miR-302a-5p and miR-367-3p were detected using quantitative real-time PCR and in situ hybridization. Western blotting and immunohistochemistry were used to detect the levels of HMGA2 and epithelial-mesenchymal transition pathway-related proteins. Co-immunoprecipitation was used to detect protein interactions. The roles of miR-302a-5p and miR-367-3p in the regulation of HMGA2 during the progression of endometrial cancer were investigated using both in vitro and in vivo assays.

RESULTS

In the present study, high HMGA2 expression was correlated with poor clinical outcomes in endometrial cancer. The binding sites of miRNAs on HMGA2 mRNA were identified using bioinformatics prediction software and were validated via luciferase assay. In the endometrial cancer cell lines Ishikawa and HEC-1A, the overexpression of miR-302a-5p/367-3p significantly inhibited the expression of HMGA2 mRNA. In endometrial cancer tissues, we showed that miR-302a-5p and miR-367-3p were significantly downregulated and thus inversely correlated with HMGA2. The miR-302a-5p and miR-367-3p expression levels were closely correlated with FIGO stage and lymph node metastasis. High expression of miR-302a-5p/367-3p was correlated with high survival rates in endometrial cancer. In addition, miR-302a-5p/367-3p suppressed the malignant behaviour of endometrial carcinoma cells via the inhibition of HMGA2 expression.

CONCLUSION

Our findings indicate that miR-302a-5p/367-3p-mediated expression of HMGA2 regulates the malignant behaviour of endometrial carcinoma cells, which suggests that the miR-302a-5p/367-3p-HMGA2 axis may be a predictive biomarker of endometrial cancer metastasis and patient survival and a potential therapeutic target in metastatic endometrial cancer.

MicroRNA-33a downregulation is associated with tumorigenesis and poor prognosis in patients with hepatocellular carcinoma

In order to examine the prognostic significance of miR-33a in patients with hepatocellular carcinoma (HCC), total RNA was extracted from 149 HCC biopsies, 36 of which were paired with para-carcinoma tissues, and miR-33a expression was measured by reverse transcription-quantitative polymerase chain reaction. The results demonstrated that miR-33a expression was decreased in HCC biopsies compared with normal liver tissue samples. It was also demonstrated that miR-33a expression was significantly associated with tumor foci number. Furthermore, overall and progression-free survival time was decreased in patients expressing low miR-33a with multiple tumor foci. Taken together, the low expression of miR-33a may be a potential risk factor for HCC.

NKX2-1 expression as a prognostic marker in early-stage non-small-cell lung cancer

BACKGROUND

NKX2-1, a key molecule in lung development, is highly expressed in non-small cell lung cancer (NSCLC), particularly in lung adenocarcinoma (ADK), where it is a diagnostic marker. Studies of the prognostic role of NKX2-1 in NSCLC have reported contradictory findings. Two microRNAs (miRNAs) have been associated with NKX2-1: miR-365, which targets NKX2-1; and miR-33a, which is downstream of NKX2-1. We have examined the effect of NKX2-1, miR-365 and miR-33a on survival in a cohort of early-stage NSCLC patients and in sub-groups of patients classified according to the mutational status of TP53, KRAS, and EGFR.

METHODS

mRNA and miRNA expression was determined using TaqMan assays in 110 early-stage NSCLC patients. TP53, KRAS, and EGFR mutations were assessed by Sanger sequencing.

RESULTS

NKX2-1 expression was upregulated in never-smokers (P = 0.017), ADK (P < 0.0001) and patients with wild-type TP53 (P = 0.001). A negative correlation between NKX2-1 and miR-365 expression was found (ρ = -0.287; P = 0.003) but there was no correlation between NKX2-1 and miR-33a expression. Overall survival (OS) was longer in patients with high expression of NKX2-1 than in those with low expression (80.8 vs 61.2 months (P = 0.035), while a trend towards longer OS was observed in patients with low miR-365 levels (P = 0.07). The impact of NKX2-1 on OS and DFS was higher in patients with neither TP53 nor KRAS mutations. Higher expression of NKX2-1 was related to higher OS (77.6 vs 54 months; P = 0.017) and DFS (74.6 vs 57.7 months; P = 0.006) compared to low expression. The association between NKX2-1 and OS and DFS was strengthened when the analysis was limited to patients with stage I disease (P = 0.005 and P=0.003 respectively).

CONCLUSIONS

NKX2-1 expression impacts prognosis in early-stage NSCLC patients, particularly in those with neither TP53 nor KRAS mutations.

Overexpression of miR-194 Reverses HMGA2-driven Signatures in Colorectal Cancer

Colorectal cancer (CRC) is one of the leading causes of cancer death worldwide with increasing incidence and mortality in developed countries. Oncogenes and microRNAs regulate key signaling pathways in CRC and are known to be deregulated. Oncogenic transcriptional regulator high-mobility group AT-hook 2 (HMGA2) participates in the transformation of several cancers including CRC and exhibits strong correlation with poor prognosis and distal metastasis. Evidence of HMGA2 and its co-regulated miRs contributing to tumor progression remains to be clarified.

METHODS

We performed gene-set enrichment analysis on the expression profiles of 70 CRC patients and revealed HMGA2 correlated genes that are targeted by several miRs including miR-194. To eliminate the oncogenic effects in HMGA2-driven CRC, we re-expressed miR-194 and found that miR-194 functions as a tumor suppressor by reducing cell proliferation and tumor growth in vitro and in vivo.

RESULTS

As a direct upstream inhibitory regulator of miR-194, overexpression of HMGA2 reduced miR-194 expression and biological activity, whereas re-expressing miR-194 in cells with high levels of HMGA2 impaired the effects of HMGA2, compromising cell survival, the epithelial-mesenchymal transition process, and drug resistance.

CONCLUSION

Our findings demonstrate that novel molecular correlations can be discovered by revisiting transcriptome profiles. We uncover that miR-194 is as important as HMGA2, and both coordinately regulate the oncogenesis of CRC with inverted behaviors, revealing alternative molecular therapeutics for CRC patients with high HMGA2 expression.

Roles of Thyroid Transcription Factor 1 in Lung Cancer Biology

Thyroid transcription factor 1 (TTF-1 or NKX2-1) is a transcription factor of fundamental importance in driving lung maturation and morphogenesis. In the last decade, scientists began to appreciate the functional roles of TTF-1 in lung tumorigenesis. This movement was triggered by the discoveries of genetic alterations of TTF-1 in the form of gene amplification in lung cancer. Many downstream target genes of TTF-1 relevant to the lung cancer biology of TTF-1 have been documented. One of the most surprising findings was that TTF-1 may exhibit either pro- or antitumorigenic activities, an outcome with the complexity exceeding the original anticipation purely based on the fact that TTF-1 undergoes gene amplification in lung cancer. In the coming decade, we believe, we will witness additional surprises as the research exploring the cancer roles of TTF-1 progresses.

Thyroid transcription factor-1-regulated microRNA-532-5p targets KRAS and MKL2 oncogenes and induces apoptosis in lung adenocarcinoma cells

Thyroid transcription factor‐1 (TTF‐1), also known as NKX2‐1, plays a role as a lineage‐survival oncogene in lung adenocarcinoma that possesses double‐edged sword characteristics. Although evidence from previous studies has steadily accumulated regarding the roles of TTF‐1 in transcriptional regulation of protein‐coding genes, little is known about its regulatory relationship with microRNAs. Here, we utilized an integrative approach designed to extract maximal information from expression profiles of both patient tumors in vivo and TTF‐1‐inducible cell lines in vitro, which identified microRNA (miR)‐532‐5p as a novel transcriptional target of TTF‐1. We found that miR‐532‐5p is directly regulated by TTF‐1 through its binding to a genomic region located 8 kb upstream of miR‐532‐5p, which appears to impose transcriptional regulation independent of that of CLCN5, a protein‐coding gene harboring miR‐532‐5p in its intron 3. Furthermore, our results identified KRAS and MKL2 as novel direct targets of miR‐532‐5p. Introduction of miR‐532‐5p mimics markedly induced apoptosis in KRAS‐mutant as well as KRAS wild‐type lung adenocarcinoma cell lines. Interestingly, miR‐532‐5p showed effects on MEK‐ERK pathway signaling, specifically in cell lines sensitive to siKRAS treatment, whereas those miR‐532‐5p‐mediated effects were clearly rendered as phenocopies by repressing expression or inhibiting the function of MKL2 regardless of KRAS mutation status. In summary, our findings show that miR‐532‐5p is a novel transcriptional target of TTF‐1 that plays a tumor suppressive role by targeting KRAS and MKL2 in lung adenocarcinoma.

Curcumin inhibits cancer progression through regulating expression of microRNAs

Curcumin, a major yellow pigment and spice in turmeric and curry, is a powerful anti-cancer agent. The anti-tumor activities of curcumin include inhibition of tumor proliferation, angiogenesis, invasion and metastasis, induction of tumor apoptosis, increase of chemotherapy sensitivity, and regulation of cell cycle and cancer stem cell, indicating that curcumin maybe a strong therapeutic potential through modulating various cancer progression. It has been reported that microRNAs as small noncoding RNA molecules are related to cancer progression, which can be regulated by curcumin. Dysregulated microRNAs play vital roles in tumor biology via regulating expressions of target genes and then influencing multiple cancer-related signaling pathways. In this review, we focused on the inhibition effect of curcumin on various cancer progression by regulating expression of multiple microRNAs. Curcumin-induced dysregulation of microRNAs may activate or inactivate a set of signaling pathways, such as Akt, Bcl-2, PTEN, p53, Notch, and Erbb signaling pathways. A better understanding of the relation between curcumin and microRNAs may provide a potential therapeutic target for various cancers.

Long noncoding RNA HIT000218960 promotes papillary thyroid cancer oncogenesis and tumor progression by upregulating the expression of high mobility group AT-hook 2 (HMGA2) gene

Accumulating evidence suggests that long noncoding RNAs (lncRNAs) play an important role in oncogenesis and tumor progression. However, our knowledge of lncRNAs in thyroid cancer is still limited. To explore the crucial lncRNAs involved in oncogenesis of papillary thyroid cancer (PTC), we acquired data of differentially expressed lncRNAs between PTC tissues and paired adjacent noncancerous thyroid tissues through lncRNA microarray. In the microarray data, we observed that a newly identified lncRNA, HIT000218960, was significantly upregulated in PTC tissues and associated with a well-known oncogene, high mobility group AT-hook 2 (HMGA2) gene. Both in normal thyroid tissues and PTC tissues, the expression of HIT000218960 was significantly positively correlated with that of HMGA2 mRNA. Knockdown of HIT000218960 in PTC cells resulted in downregulation of HMGA2. In addition, functional assays indicated that inhibition of HIT000218960 in PTC cells suppressed cell proliferation, colony formation, migration and invasion in vitro. Increased HIT000218960 expression in PTC tissues was obviously correlated with lymph node metastasis and multifocality, as well as TNM stage. Those findings suggest that HIT000218960 might acts as a tumor promoter through regulating the expression of HMGA2.

MiR-33a suppresses proliferation of NSCLC cells via targeting METTL3 mRNA

Methyltransferase like 3 (METTL3) was incipiently known as a methyltransferase which was responsible for N⁶-methyladenosine (m⁶A) methylation. METTL3 can promote the expression of several crucial oncoproteins and its high expression enhanced proliferation, survival, and invasion of human lung cancer cells. However, how METTL3 was regulated is seldom understood in non-small-cell lung carcinoma (NSCLC). In the present study, miR-33a was suspicious to target to the 3'-untranslated region (3'UTR) of METTL3 mRNA via in silico prediction. Besides, the expressions of METTL3 were higher in NSCLC tissues than those in adjacent tissues, and METTL3 expressions were positively related to the expressions of miR-33a in NSCLC tissues which confirmed by quantitative real-time polymerase chain reaction (qRT-PCR). MiR-33a can directly target to the 3'UTR of METTL3 mRNA which examined by luciferase reporter gene assay. Moreover, we found that miR-33a can reduce the expression of METTL3 at both mRNA and protein levels using reverse transcription-polymerase chain reaction (RT-PCR) and Western blot analysis. Functionally, miR-33a can reduce the proliferation of A549 and NCI-H460 cells. Conversely, inhibition of miR-33a by anti-miR-33a can rescue that using 4,5-dimethyl-2-thiazolyl)-2,5-diphenyl-2-H-tetrazolium bromide (MTT) and 5-ethynyl-2-deoxyuridine (EdU) assay. Similarly, miR-33a can reduce cellular anchorage-independent growth of A549 cells. Additionally, the negative influences of miR-33a on the downstream genes of METTL3 were examined by Western blot analysis. Thus, we concluded that miR-33a can attenuate NSCLC cells proliferation via targeting to the 3'UTR of METTL3 mRNA. Our findings provide new insights into the mechanism of METTL3 regulation by micro RNA, and supports METTL3 as a therapeutic target in NSCLC.

Cordycepin (3'-deoxyadenosine) suppressed HMGA2, Twist1 and ZEB1-dependent melanoma invasion and metastasis by targeting miR-33b

Malignant melanoma, the most deadly form of skin cancer, has a high propensity for metastatic spread and is notoriously chemotherapy-resistant. Cordycepin, the active component of Cordyceps spp., has been identified to have anti-metastatic effect on tumor progression and thus possesses pharmacological and therapeutic potentials. However, the mechanisms of anti-metastatic effects of cordycepin at cellular levels remain elusive. We analyzed the effect of cordycepin on human melanoma miRNA expression profiles by miRNAarray and found that miR-33b was upregulated in highly-metastatic melanoma cell lines following cordycepin exposure. Cordycepin-mediated miR-33b expression was dependent on LXR-RXR heterodimer activation. miR-33b directly binds to HMGA2, Twist1 and ZEB1 3'-UTR to suppress their expression. The negative correlations between miR-33b levels and HMGA2, Twist1 or ZEB1 expression were detected in 72 patient melanoma tissue samples. By targeting HMGA2 and Twist1, miR-33b attenuated melanoma migration and invasiveness upon cordycepin exposure. miR-33b knockdown or ZEB1 overexpression reverted cordycepin-mediated mesenchymal-epithelial transition (MET), triggering the expression of N-cadherin. In spontaneous metastasis models, cordycepin suppressed tumor metastasis without altering primary tumor growth. We showed for the first time that targeting miRNA by cordycepin indicates a new mechanism of cordycepin-induced suppression of tumor metastasis and miR-33b/HMGA2/Twist1/ZEB1 axis plays critical roles in regulating melanoma dissemination.

The transcriptional modulator HMGA2 promotes stemness and tumorigenicity in glioblastoma

Glioblastoma (GBM) contains a population of stem-like cells that promote tumor invasion and resistance to therapy. Identifying and targeting stem cell factors in GBM may lead to the development of more effective therapies. High Mobility Group AT-hook 2 (HMGA2) is a transcriptional modulator that mediates motility and self-renewal in normal and cancer stem cells. We identified increased expression of HMGA2 in the majority of primary human GBM tumors and cell lines compared to normal brain. Additionally, HMGA2 expression was increased in CD133+ GBM neurosphere cells compared to CD133- cells. Targeting HMGA2 with lentiviral short hairpin RNA (shRNA) led to decreased GBM stemness, invasion, and tumorigenicity. Ectopic expression of HMGA2 in GBM cell lines promoted stemness, invasion, and tumorigenicity. Our data suggests that targeting HMGA2 in GBM may be therapeutically beneficial.

miR-33-5p, a novel mechano-sensitive microRNA promotes osteoblast differentiation by targeting Hmga2

MicroRNAs (miRNAs) interfere with the translation of specific target mRNAs and are thought to thereby regulate many cellular processes. However, the role of miRNAs in osteoblast mechanotransduction remains to be defined. In this study, we investigated the ability of a miRNA to respond to different mechanical environments and regulate mechano-induced osteoblast differentiation. First, we demonstrated that miR-33-5p expressed by osteoblasts is sensitive to multiple mechanical environments, microgravity and fluid shear stress. We then confirmed the ability of miR-33-5p to promote osteoblast differentiation. Microgravity or fluid shear stress influences osteoblast differentiation partially via miR-33-5p. Through bioinformatics analysis and a luciferase assay, we subsequently confirmed that Hmga2 is a target gene of miR-33-5p that negatively regulates osteoblast differentiation. Moreover, miR-33-5p regulates osteoblast differentiation partially via Hmga2. In summary, our findings demonstrate that miR-33-5p is a novel mechano-sensitive miRNA that can promote osteoblast differentiation and participate in the regulation of differentiation induced by changes in the mechanical environment, suggesting this miRNA as a potential target for the treatment of pathological bone loss.

miR-33a is downregulated in melanoma cells and modulates cell proliferation by targeting PCTAIRE1

MicroRNA-33a (miR-33a) was previously identified as a lipid regulator that controls the cellular balance between cholesterol and fatty acid metabolism. However, its role in tumor progression is largely unknown. The present study identified that miR-33a acts as a tumor suppressor in melanoma cells. The present study revealed that miR-33a was downregulated in melanoma cells compared with melanocytes. Overexpression of miR-33a suppressed the colony formation of human melanoma SK-MEL-1 and WM-115 cells. Furthermore, a bromodeoxyuridine incorporation assay and anaphase analysis revealed that miR-33a inhibits melanoma cell proliferation. miR-33a overexpression inhibited p27 phosphorylation and upregulated p27 expression. Additionally, the present study demonstrated that PCTAIRE1 was a direct target of miR-33a; miR-33a overexpression suppressed the luciferase activity of a reporter construct containing a 3′-untranslated region of PCTAIRE1 and downregulated PCTAIRE1 in melanoma cells. An overexpression of PCTAIRE1 reversed the miR-33a-induced p27 accumulation and tumor suppressive effects. In summary, the present findings offer novel mechanistic insights into miR-33a and its downstream target in melanoma cells.

miR-33a functions as a tumor suppressor in melanoma by targeting HIF-1α

BACKGROUND

Our previous findings showed that miR-33 expressed abnormally in clinical specimens of melanoma, but the exact molecular mechanism has not been elucidated.

OBJECT

To determine miR-33's roles in melanoma and confirm whether HIF-1α is a direct target gene of miR-33a.

METHODS

First miR-33a/b expression levels were detected in HM, WM35, WM451, A375 and SK-MEL-1. Then lentiviral vectors were constructed to intervene miR-33a expression in melanoma cells. Cell proliferation, invasion and metastasis were detected. A375 cells mice model was performed to test the tumorigenesis of melanoma in vivo. Finally the dual reporter gene assay was carried out to confirm whether HIF-1α is a direct target gene of miR-33a.

RESULTS

MiR-33a/b exhibited a lower expression in WM35, WM451, A375 and SK-MEL-1 of the metastatic skin melanoma cell lines than that in HM. Then inhibition of miR-33a expression in WM35 and WM451 cell lines could promote cell proliferation, invasion and metastasis. Conversely, increased expression of miR-33a in A375 cells could inhibit cellproliferation, invasion and metastasis. In vivo tests also confirmed that overexpression of miR-33a in A375 cells significantly inhibited melanoma tumorigenesis. Finally, we confirmed that HIF-1α is a direct target gene of miR-33a.

CONCLUSION

The newly identified miR-33a/HIF-1α axis might provide a new strategy for the treatment of melanoma.

Thyroid Transcription Factor 1 Reprograms Angiogenic Activities of Secretome

Through both gain- and loss-of-TTF-1 expression strategies, we show that TTF-1 positively regulates vascular endothelial growth factor (VEGF) and that the VEGF promoter element contains multiple TTF-1-responsive sequences. The major signaling receptor for VEGF, i.e VEGFR2, also appears to be under a direct and positive regulation of TTF-1. The TTF-1-dependent upregulation of VEGF was moderately sensitive to rapamycin, implicating a partial involvement of mammalian target of rapamycin (mTOR). However, hypoxia did not further increase the secreted VEGF level of the TTF-1⁺ lung cancer cells. The TTF-1-induced VEGF upregulation occurs in both compartments (exosomes and exosome-depleted media (EDM)) of the conditioned media. Surprisingly, the EDM of TTF-1⁺ lung cancer cells (designated EDM-TTF-1⁺) displayed an anti-angiogenic activity in the endothelial cell tube formation assay. Mechanistic studies suggest that the increased granulocyte-macrophage colony-stimulating factor (GM-CSF) level in the EDM-TTF-1⁺ conferred the antiangiogenic activities. In human lung cancer, the expression of TTF-1 and GM-CSF exhibits a statistically significant and positive correlation. In summary, this study provides evidence that TTF-1 may reprogram lung cancer secreted proteome into an antiangiogenic state, offering a novel basis to account for the long-standing observation of favorable prognosis associated with TTF-1⁺ lung adenocarcinomas.

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

Background

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

Methods

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

Results

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

Conclusions

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

Electronic supplementary material

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

SREBP-1c/MicroRNA 33b Genomic Loci Control Adipocyte Differentiation

White adipose tissue (WAT) is essential for maintaining metabolic function, especially during obesity. The intronic microRNAs miR-33a and miR-33b, located within the genes encoding sterol regulatory element-binding protein 2 (SREBP-2) and SREBP-1, respectively, are transcribed in concert with their host genes and function alongside them to regulate cholesterol, fatty acid, and glucose metabolism. SREBP-1 is highly expressed in mature WAT and plays a critical role in promoting in vitro adipocyte differentiation. It is unknown whether miR-33b is induced during or involved in adipogenesis. This is in part due to loss of miR-33b in rodents, precluding in vivo assessment of the impact of miR-33b using standard mouse models. This work demonstrates that miR-33b is highly induced upon differentiation of human preadipocytes, along with SREBP-1. We further report that miR-33b is an important regulator of adipogenesis, as inhibition of miR-33b enhanced lipid droplet accumulation. Conversely, overexpression of miR-33b impaired preadipocyte proliferation and reduced lipid droplet formation and the induction of peroxisome proliferator-activated receptor γ (PPARγ) target genes during differentiation. These effects may be mediated by targeting of HMGA2, cyclin-dependent kinase 6 (CDK6), and other predicted miR-33b targets. Together, these findings demonstrate a novel role of miR-33b in the regulation of adipocyte differentiation, with important implications for the development of obesity and metabolic disease.

Molecular mechanisms of microRNAs in regulating epithelial-mesenchymal transitions in human cancers

The epithelial-mesenchymal transition (EMT) provides a strong driving force in the progression of various human cancers and the development of chemoresistance. Recently, numbers of studies have demonstrated that microRNAs (miRNAs), by post-transcriptionally silencing EMT-related molecules, can promote or inhibit the EMT process and play pivotal roles in effectively manipulating the occurrence, development, invasion, and metastasis of cancers. MiRNAs can also control the EMT or be controlled by genetic modification and mutual regulation, especially negative feedback. Therefore, miRNAs can be viewed as either oncogenes or tumor suppressor genes to facilitate or retard the EMT, resulting in far-reaching impact on tumor metastasis and effective diagnosis, treatment, and prognosis.

Downregulation of microRNA‑33a promotes cyclin‑dependent kinase 6, cyclin D1 and PIM1 expression and gastric cancer cell proliferation

Although microRNA‑33 (miR‑33) family members are known to be involved in the regulation and balancing of cholesterol metabolism, fatty acid oxidation and insulin signaling, their functions in carcinogenesis are controversial and the underlying mechanisms have remained elusive. Gastric cancer is the fourth most common malignancy in the world; however, the dysregulation and function of miR‑33 family members in gastric cancer have not been extensively studied. The present study reported that a miR‑33 family member, miR‑33a, was significantly downregulated in gastric cancer tissues and gastric cancer cell lines. Of note, the expression of miR‑33a was inversely correlated with pathological differentiation and metastasis as well as gastric cancer biomarker CA199. A cell‑counting kit‑8 assay showed that transfection of the SGC‑7901 gastric cell line with miR‑33a‑overexpression plasmid inhibited the capability of the cells to proliferate. Furthermore, overexpression of miR‑33a led to cell cycle arrest of SGC‑7901 cells in G1 phase. In addition, a luciferase reporter assay showed that miR‑33a directly targeted cyclin‑dependent kinase 6 (CDK6), cyclin D1 (CCND1) and serine/threonine kinase PIM‑1. In gastric cancer specimens, the reduced expression of miR‑33a was associated with increased expression of CDK‑6, CCND1 and PIM1. However, only PIM1 expression was significantly increased in cancer tissues compared with that in their adjacent tissues. The present study revealed that miR‑33a was downregulated in gastric cancer tissues and cell lines, while forced overexpression of miR‑33a decreased CDK‑6, CCND1 and PIM1 expression to inhibit gastric cancer cell proliferation by causing G1 phase arrest. miR‑33a overexpression may therefore resemble an efficient strategy for gastric cancer therapy.

MircoRNA-33a inhibits epithelial-to-mesenchymal transition and metastasis and could be a prognostic marker in non-small cell lung cancer

Understanding the molecular mechanism by which epithelial mesenchymal transition (EMT)-mediated cancer metastasis and how microRNA (miRNA) regulates lung cancer progression via Twist1-activated EMT may provide potential therapeutic targets for cancer therapy. Here we found that miR-33a, an intronic miRNA located within the sterol regulatory element-binding protein 2 (SREBP-2) gene, is expressed at low levels in metastatic non-small cell lung cancer (NSCLC) cells and is inversely correlated with Twist1 expression. Conversely, miR-33a knockdown induces EMT and miR-33a overexpression blocks EMT by regulating of Twist1 expression in NSCLC cells. Bioinformatical prediction and luciferase reporter assay confirm that Twist1 is a direct target of miR-33a. Additionally, Twist1 knockdown blocks EMT-related metastasis and forced expression of miR-33a inhibits lung cancer metastasis in a xenograft animal model. Clinically, miR-33a is found to be at low levels in NSCLC patients and down-regulation of miR-33a predicts a poor prognosis. These findings suggest that miR-33a targets Twist1 and inhibits invasion and metastasis in NSCLC. Thus, miR-33a might be a potential prognostic marker and of therapeutic relevance for NSCLC metastasis intervention.

High mobility group a proteins as tumor markers

Almost 30 years ago, overexpression of HMGA proteins was associated with malignant phenotype of rat thyroid cells transformed with murine retroviruses. Thereafter, several studies have analyzed HMGA expression in a wide range of human neoplasias. Here, we summarize all these results that, in the large majority of the cases, confirm the association of HMGA overexpression with high malignant phenotype as outlined by chemoresistance, spreading of metastases, and a global poor survival. Even though HMGA proteins’ overexpression indicates a poor prognosis in almost all malignancies, their detection may be particularly useful in determining the prognosis of breast, lung, and colon carcinomas, suggesting for the treatment a more aggressive therapy. In particular, the expression of HMGA2 in lung carcinomas is frequently associated with the presence of metastases. Moreover, recent data revealed that often the cause for the high HMGA proteins levels detected in human malignancies is a deregulated expression of non-coding RNA. Therefore, the HMGA proteins represent tumor markers whose detection can be a valid tool for the diagnosis and prognosis of neoplastic diseases.

Associations of deregulation of mir-365 and its target mRNA TTF-1 and survival in patients with NSCLC

microRNA (mir)-365 exerts tumor suppressor function by targeting thyroid transcription factor-1 (TTF-1) in lung cancer cells. The purpose of the present study was to assess mir-365 and its target mRNA TTF-1 in lung cancer and their correlations with patients' survival. Quantitative real-time PCR was used to examine the expression levels of mir-365 and TTF-1 in tumor tissue and its adjacent noncancerous tissue of 126 patients with non-small cell lung cancer (NSCLC). Our results showed that mir-365 was significantly decreased in tumor tissue than that in normal tissue (P=0.006), however, TTF-1 was significantly increased in tumor tissue than in normal tissue (P<0.001). Besides, significant correlations between decreased mir-365 and advanced tumor-node-metastasis (TNM) stage (P=0.001) and regional lymph node involvement (P=0.037) was observed. The similar result was also found between increased TTF-1 and TNM stage (P=0.003). Furthermore, mir-365 downregulation or TTF-1 upregulation were associated with poor outcome of patients than mir-365 upregulation or TTF-1 downregulation (for mir-365: P<0.001; for TTF-1: P=0.002). Of note, combination of decreased mir-365 and increased TTF-1 had worst overall survival (P<0.001). In conclusion, aberrant expression of mir-365/TTF-1 may be involved in the tumor development in patients with NSCLC. Moreover, mir-365 and TTF-1 could jointly predict the prognosis of patients and their combination may serve as a biomarker to predict risk of poor survival in NSCLC patients. Mir-365/TTF-1 might serve as a potential therapeutic target for clinical treatment of NSCLC.

MicroRNA-33b, upregulated by EF24, a curcumin analog, suppresses the epithelial-to-mesenchymal transition (EMT) and migratory potential of melanoma cells by targeting HMGA2

Diphenyl difluoroketone (EF24), a curcumin analog, exhibits potent anti-tumor activities by arresting cell cycle and inducing apoptosis. However, the efficacy and modes of action of EF24 on melanoma metastasis remain elusive. In this study, we found that at non-cytotoxic concentrations, EF24 suppressed cell motility and epithelial-to-mesenchymal Transition (EMT) of melanoma cell lines, Lu1205 and A375. EF24 also suppressed HMGA2 expression at mRNA and protein levels. miR-33b directly bound to HMGA2 3' untranslated region (3'-UTR) to suppress its expression as measured by dual-luciferase assay. EF24 increased expression of E-cadherin and decreased STAT3 phosphorylation and expression of the mesenchymal markers, vimentin and N-cadherin. miR-33b inhibition or HMGA2 overexpression reverted EF24-mediated suppression of EMT phenotypes. In addition, EF24 modulated the HMGA2-dependent actin stress fiber formation, focal adhesion assembly and FAK, Src and RhoA activation by targeting miR-33b. Thus, the results suggest that EF24 suppresses melanoma metastasis via upregulating miR-33b and concomitantly reducing HMGA2 expression. The observed activities of EF24 support its further evaluation as an anti-metastatic agent in melanoma therapy.

MicroRNAs in human lung cancer

Lung cancer, which can be divided into two major clinical-pathological categories, small cell lung cancer and non-small cell lung cancer, is the leading cause of cancer-related death worldwide. MicroRNAs (miRNAs), small non-coding RNAs approximately 22 nucleotides in length, have been reported to be upregulated or downregulated in disease states and specific cell types. Recently, miRNAs have gained recognition as major regulators of human gene expression. MiRNAs can control highly complex signal transduction pathways and other biological pathways by targeting and controlling gene expression, accounting for their important role in lung cancer. Findings from recent studies on the roles of miRNAs in lung cancer are summarized in this review. Understanding miRNA functions in lung cancer will bring molecular-level insight leading to better prognosis, diagnosis, and therapeutic approaches.

MicroRNAs: regulators of cancer metastasis and epithelial-mesenchymal transition (EMT)

Tumor metastasis is the main cause of death in patients with solid tumors. The epithelial-mesenchymal transition (EMT) process, in which epithelial cells are converted into mesenchymal cells, is frequently activated during cancer invasion and metastasis. MicroRNAs (miRNAs) are small, non-coding RNAs that provide widespread expressional control by repressing mRNA translation and inducing mRNA degradation. The fundamental roles of miRNAs in tumor growth and metastasis have been increasingly well recognized. A growing number of miRNAs are reported to regulate tumor invasion/metastasis through EMT-related and/or non-EMT- related mechanisms. In this review, we discuss the functional role and molecular mechanism of miRNAs in regulating cancer metastasis and EMT.