miR-409-3p/-5p promotes tumorigenesis, epithelial-to-mesenchymal transition, and bone metastasis of human prostate cancer

MicroRNA-409-3p inhibits osteosarcoma cell migration and invasion by targeting catenin-δ1

Osteosarcoma is the most common primary bone cancer which is associated with early metastatic potential and poor prognosis. However, the molecular mechanisms underlying osteosarcoma progression are not well characterized. Here, we investigated the role of miR-409-3p in osteosarcoma metastasis. Osteosarcoma tissue showed decreased expression of miR-409-3p compared to adjacent non-tumorous tissue. The expression level of miR-409-3p was negatively correlated with osteosarcoma metastasis. Overexpression of miR-409-3p in osteosarcoma cells (U2OS) inhibited cell migration and invasion. Bioinformatics analysis showed that catenin-δ1 (CTNND1, p120-catenin) is a direct target of miR-409-3p. Overexpression of miR-409-3p repressed the expression of catenin-δ1 in U2OS cells at both mRNA and protein levels. Meanwhile, miR-409-3p repressed the activity of luciferase reporter containing the 3'-untranslated region (3'UTR) of CTNND1 gene. Furthermore, expression of catenin-δ1 rescued the inhibitory effect of miR-409-3p on cell migration and invasion. Altogether, these results indicated that miR-409-3p targets catenin-δ1 to repress osteosarcoma metastasis.

MiRNA Transcriptome Profiling of Spheroid-Enriched Cells with Cancer Stem Cell Properties in Human Breast MCF-7 Cell Line

Breast cancer is the second leading cause of cancer-related mortality worldwide as most patients often suffer cancer relapse. The reason is often attributed to the presence of cancer stem cells (CSCs). Recent studies revealed that dysregulation of microRNA (miRNA) are closely linked to breast cancer recurrence and metastasis. However, no specific study has comprehensively characterised the CSC characteristic and miRNA transcriptome in spheroid-enriched breast cells. This study described the generation of spheroid MCF-7 cell in serum-free condition and the comprehensive characterisation for their CSC properties. Subsequently, miRNA expression differences between the spheroid-enriched CSC cells and their parental cells were evaluated using next generation sequencing (NGS). Our results showed that the MCF-7 spheroid cells were enriched with CSCs properties, indicated by the ability to self-renew, increased expression of CSCs markers, and increased resistance to chemotherapeutic drugs. Additionally, spheroid-enriched CSCs possessed greater cell proliferation, migration, invasion, and wound healing ability. A total of 134 significantly (p<0.05) differentially expressed miRNAs were identified between spheroids and parental cells using miRNA-NGS. MiRNA-NGS analysis revealed 25 up-regulated and 109 down-regulated miRNAs which includes some miRNAs previously reported in the regulation of breast CSCs. A number of miRNAs (miR-4492, miR-4532, miR-381, miR-4508, miR-4448, miR-1296, and miR-365a) which have not been previously reported in breast cancer were found to show potential association with breast cancer chemoresistance and self-renewal capability. The gene ontology (GO) analysis showed that the predicted genes were enriched in the regulation of metabolic processes, gene expression, DNA binding, and hormone receptor binding. The corresponding pathway analyses inferred from the GO results were closely related to the function of signalling pathway, self-renewability, chemoresistance, tumorigenesis, cytoskeletal proteins, and metastasis in breast cancer. Based on these results, we proposed that certain miRNAs identified in this study could be used as new potential biomarkers for breast cancer stem cell diagnosis and targeted therapy.

Epigenetic regulation of steroid inactivating UDP-glucuronosyltransferases by microRNAs in prostate cancer

Androgens play a central role in prostate cancer progression. Systemic and local androgen bioavailability is controlled by UDP-glucuronosyltransferases conjugating enzymes (UGT), namely UGT2B15, UGT2B17 and UGT2B28. Reporter vector assays in HEK293 cells initially validated in silico-predicted regulatory potential of candidate miRNAs to target UGT transcripts, including miR-376c, miR-409 and miR-494 for UGT2B17, miR-331-5p and miR-376c for UGT2B15 while none were efficient for UGT2B28. miR-376c was shown as the most effective to downregulate UGT2B15 and UGT2B17 through interactions with a site conserved in both UGTs. Ectopic miR-376c expression in prostate cancer cells significantly reduced UGT2B15 and UGT2B17 expression (>32%; P<0.005) with a consequent decrease in dihydrotestosterone glucuronidation (-37%; P<0.001). Consistent with reduced androgen inactivation, ectopic expression of miR-376c changed expression of androgen responsive genes and enhanced cell proliferation with no effect on androgen receptor levels. Sustaining a role of miR-376c in the regulation of androgen-inactivating UGTs, its expression was significantly downregulated in prostatic tumors and further reduced in metastases (P<0.0001), whereas the opposite was observed for UGT2B15/17 (P=0.031). In high-grade tumors (Gleason ≥8), UGT2B15/17 and miR-376c were inversely correlated (r=-0.557; P=0.048) with also a significant relationship in metastases (r=-0.747; P=0.003). In line with a modification in androgen bioavailability, PSA mRNA levels were also negatively correlated to those of UGT2B15/17 (r=-0.573; P=0.01) but positively linked to levels of miR-376c (r=0.577; P=0.039). This study reveals that the androgen-inactivating UGT2B15 and UGT2B17 genes are direct targets of miR-376c and thus may influence steroid metabolism during prostate cancer progression.

Curcumin mediates reversion of HGF-induced epithelial-mesenchymal transition via inhibition of c-Met expression in DU145 cells

The hepatocyte growth factor (HGF)/c-Met signaling pathway results in cancer cell scattering and invasion, and has been reported to participate in several types of cancer, including prostate and colorectal cancer. The downstream phosphorylation cascade of HGF, particularly the mitogen-activated protein kinase and phosphoinositide 3-kinase/AKT signaling pathway, regulates epithelial-mesenchymal transition (EMT). However, the mechanism by which these signaling pathways govern EMT, and whether certain kinases are able to respond to specific EMT effectors, remains to be elucidated. In the present study, an increase in the levels of vimentin, rather than co-regulation of certain EMT marker proteins, was observed in response to HGF-induced EMT in DU145 prostate cancer cells. In addition, it was observed that curcumin abrogated HGF-induced DU145 cell scattering and invasion. Furthermore, curcumin was able to effectively inhibit the HGF-induced increase in the levels of vimentin by downregulating the expression of phosphorylated c-Met, extracellular signal-regulated kinase and Snail. In conclusion, the results of the present study demonstrated that curcumin was able to reverse HGF-induced EMT, possibly by inhibiting c-Met expression in DU145 prostate cancer cells.

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.

miR-409-3p suppresses breast cancer cell growth and invasion by targeting Akt1

Altered levels and functions of microRNAs (miRNAs) are correlated with carcinogenesis. While miR-409-3p has been shown to play important roles in several cancer types, its function in the context of breast cancer (BC) remains unknown. In this study, miR-409-3p was significantly downregulated in BC tissues and cell lines, compared with the corresponding control counterparts. Overexpression of miR-409-3p inhibited BC cell proliferation, migration and invasion in vitro and suppressed tumor growth in vivo. Notably, miR-409-3p induced downregulation of Akt1 protein through binding to its 3' untranslated region (UTR). Conversely, restoring Akt1 expression rescued the suppressive effects of miR-409-3p. Our data collectively indicate that miR-409-3p functions as a tumor suppressor in BC through downregulating Akt1, supporting the targeting of the novel miR-409-3p/Akt1 axis as a potentially effective therapeutic approach for BC.

miR-22 and miR-29a Are Members of the Androgen Receptor Cistrome Modulating LAMC1 and Mcl-1 in Prostate Cancer

The normal prostate as well as early stages and advanced prostate cancer (PCa) require a functional androgen receptor (AR) for growth and survival. The recent discovery of microRNAs (miRNAs) as novel effector molecules of AR disclosed the existence of an intricate network between AR, miRNAs and downstream target genes. In this study DUCaP cells, characterized by high content of wild-type AR and robust AR transcriptional activity, were chosen as the main experimental model. By integrative analysis of chromatin immunoprecipitation-sequencing (ChIP-seq) and microarray expression profiling data, miRNAs putatively bound and significantly regulated by AR were identified. A direct AR regulation of miR-22, miR-29a, and miR-17-92 cluster along with their host genes was confirmed. Interestingly, endogenous levels of miR-22 and miR-29a were found to be reduced in PCa cells expressing AR. In primary tumor samples, miR-22 and miR-29a were less abundant in the cancerous tissue compared with the benign counterpart. This specific expression pattern was associated with a differential DNA methylation of the genomic AR binding sites. The identification of laminin gamma 1 (LAMC1) and myeloid cell leukemia 1 (MCL1) as direct targets of miR-22 and miR-29a, respectively, suggested a tumor-suppressive role of these miRNAs. Indeed, transfection of miRNA mimics in PCa cells induced apoptosis and diminished cell migration and viability. Collectively, these data provide additional information regarding the complex regulatory machinery that guides miRNAs activity in PCa, highlighting an important contribution of miRNAs in the AR signaling.

MicroRNA-409-3p suppresses colorectal cancer invasion and metastasis partly by targeting GAB1 expression

Colorectal cancer (CRC) is one of the most common cancers worldwide and its metastasis accounts for the majority of deaths. However, the molecular mechanisms underlying CRC progression are not well characterized. In this study, we identified miR-409-3p as a tumor suppressor of CRC. MiR-409-3p expression was significantly downregulated in CRC tissue compared to adjacent non-tumor tissue, and reduced miR-409-3p expression was correlated with CRC metastasis. In vitro and in vivo studies revealed that miR-409-3p negatively regulated CRC metastatic capacities, including suppressing cancer cell migration, invasion and metastasis. To explore the mechanism of action of miR-409-3p, we adopted a pathway and pathophysiological event-based target screening and validation approach, and found nine known metastasis-related genes as potential targets. The 3'-UTR binding assays between the candidates and miR-409-3p suggested that only GAB1, NR4A2 and LMO4 were directly regulated by the miRNA. However, endogenous expression analysis revealed that only GAB1 was modulated by miR-409-3p in CRC cells at both the mRNA and protein levels. Furthermore, we provided evidence to conclude that GAB1 was partially responsible for miR-409-3p-mediated metastasis. Taken together, our data demonstrate that miR-409-3p is a metastatic suppressor, and post-transcriptional inhibition of the oncoprotein GAB1 is one of the mechanisms of action of this miRNA. Our finding suggests miR-409-3p might be a novel target for CRC metastasis treatment.

MicroRNAs targeting prostate cancer stem cells

Prostate cancer is a frequently diagnosed cancer in males with high mortality in the world. As a heterogeneous tissue, the tumor mass contains a subpopulation that is called as cancer stem cells and displays stem-like properties such as self-renewal, epithelial-mesenchymal transition, metastasis, and drug resistance. Cancer stem cells have been identified in variant tumors and shown to be regulated by various molecules including microRNAs. MicroRNAs are a class of small non-coding RNAs, which can influence tumorigenesis via different mechanisms. In this review, we focus on the functions of microRNAs on regulating the stemness of prostate cancer stem cells with different mechanisms and propose the potential roles of microRNAs in prostate cancer therapy.

Oridonin alters the expression profiles of microRNAs in BxPC-3 human pancreatic cancer cells

Background

Oridonin, an ingredient used in traditional Chinese medicine, has been demonstrated to play an important role in antitumour effects, but the mechanism underlying its antitumour properties is still not clear.

Methods

To verify the anti-cancer effects of oridonin via a miRNA-dependent mechanism, comprehensive miRNA expression profiling of oridonin-treated BxPC-3 human pancreatic cancer cells was performed using a miRNA microarray assay based on Sanger miR-Base Release 20, followed by a validation using real-time PCR. MicroRNA target prediction and Gene Ontology and KEGG pathway analysis were performed to investigate possible pathways involved.

Results

The results showed that 105 miRNAs were significantly differentially expressed (signal reading >500, p ≤ 0.01, |Log2-value| ≥1) in oridonin-treated BxPC-3 human pancreatic cancer cells.

Conclusions

Our data indicates that oridonin inhibits BxPC-3 cells probably through regulating the expression of miRNAs. Interruption of miRNA profiling may provide new therapeutic methods for the clinical treatment of pancreatic cancer.

Rsu1 contributes to cell adhesion and spreading in MCF10A cells via effects on P38 map kinase signaling

The ILK, PINCH, Parvin (IPP) complex regulates adhesion and migration via binding of ILK to β1 integrin and α−parvin thus linking focal adhesions to actin cytoskeleton. ILK also binds the adaptor protein PINCH which connects signaling proteins including Rsu1 to the complex. A recent study of Rsu1 and PINCH1 in non-transformed MCF10A human mammary epithelial cells revealed that the siRNA-mediated depletion of either Rsu1 or PINCH1 decreased the number of focal adhesions (FAs) and altered the distribution and localization of FA proteins. This correlated with reduced adhesion, failure to spread or migrate in response to EGF and a loss of actin stress fibers and caveolae. The depletion of Rsu1 caused significant reduction in PINCH1 implying that Rsu1 may function in part by regulating levels of PINCH1. However, Rsu1, but not PINCH1, was required for EGF-induced activation of p38 Map kinase and ATF2 phosphorylation, suggesting a Rsu1 function independent from the IPP complex. Reconstitution of Rsu1-depleted cells with a Rsu1 mutant (N92D) that does not bind to PINCH1 failed to restore FAs or migration but did promote IPP-independent spreading and constitutive as well as EGF-induced p38 activation. In this commentary we discuss p38 activity in adhesion and how Rsu1 expression may be linked to Map kinase kinase (MKK) activation and detachment-induced stress kinase signaling.

miR-154* and miR-379 in the DLK1-DIO3 microRNA mega-cluster regulate epithelial to mesenchymal transition and bone metastasis of prostate cancer

PURPOSE

MicroRNAs in the delta-like 1 homolog-deiodinase, iodothyronine 3 (DLK1-DIO3) cluster have been shown to be critical for embryonic development and epithelial to mesenchymal transition (EMT). DLK1-DIO3 cluster miRNAs are elevated in the serum of patients with metastatic cancer. However, the biologic functions of these miRNAs in the EMT and metastasis of cancer cells are poorly understood. We previously demonstrated the oncogenic and metastatic role of miR-409-3p/5p, a member of this cluster, in prostate cancer. In this study, we defined the role of miR-154* and miR-379, two key members of this cluster, in prostate cancer progression and bone metastasis in both cell line models and clinical specimens.

EXPERIMENTAL DESIGN

Genetic manipulation of miR-154* and miR-379 was performed to determine their role in tumor growth, EMT, and bone metastasis in mouse models. We determined the expression of miR-154* in prostate cancer clinical samples and bone metastasis samples using in situ hybridization and quantum dot labeling.

RESULTS

Elevated expression of miR-154* and miR-379 was observed in bone metastatic prostate cancer cell lines and tissues, and miR-379 expression correlated with progression-free survival of patients with prostate cancer. Intracardiac inoculation (to mimic systemic dissemination) of miR-154* inhibitor-treated bone metastatic ARCaPM prostate cancer cells in mice led to decreased bone metastasis and increased survival.

CONCLUSION

miR-154* and miR-379 play important roles in prostate cancer biology by facilitating tumor growth, EMT, and bone metastasis. This finding has particular translational importance because miRNAs in the DLK1-DIO3 cluster can be attractive biomarkers and possible therapeutic targets to treat bone metastatic prostate cancer.