Rewiring of an epithelial differentiation factor, miR-203, to inhibit human squamous cell carcinoma metastasis

NUAK: never underestimate a kinase

NUAK1 and NUAK2 belong to a family of kinases related to the catalytic α-subunits of the AMP-activated protein kinase (AMPK) complexes. Despite canonical activation by the tumour suppressor kinase LKB1, both NUAKs exhibit a spectrum of activities that favour tumour development and progression. Here, we review similarities in structure and function of the NUAKs, their regulation at gene, transcript and protein level, and discuss their phosphorylation of specific downstream targets in the context of the signal transduction pathways and biological activities regulated by each or both NUAKs.

Exosomal microRNA as a key regulator of PI3K/AKT pathways in human tumors

MicroRNAs (miRNAs) are conserved non-protein-coding RNAs that are naturally present in organisms and can control gene expression by suppressing the translation of mRNA or causing the degradation of mRNA. MicroRNAs are highly concentrated in the PI3K/AKT pathway, and abnormal activation of the PI3K/AKT pathway plays a role in cancer progression. The AKT/PI3K pathway is critical for cellular functions and can be stimulated by cytokines and in normal situations. It is involved in regulating various intracellular signal transduction, including development, differentiation, transcriptional regulation, protein, and synthesis. There is a growing body of evidence indicating that miRNAs, which are abundant in exosomes released by different cells, can control cellular biological activities via modulating the PI3K/AKT pathway, hence influencing cancer progression and drug resistance. This article provides an overview of the latest research progress regarding the function and medical use of the PI3K/AKT pathway and exosomal miRNA/AKT/PI3K axis in the behaviors of cancer cells.

NUAK1 activates STAT5/GLI1/SOX2 signaling to enhance cancer cell expansion and drives chemoresistance in gastric cancer

The gene encoding the NUAK family kinase 1 (NUAK1) is frequently amplified and its expression is upregulated, activating oncogenic signaling in various cancers. However, little is known about its role in gastric cancer (GC). We investigate the mechanistic links among NUAK1, Hedgehog signaling, and tumorigenesis in GC. NUAK1 overexpression is validated in local and public GC cohorts. Patient-derived xenograft and transgenic mouse models demonstrate that NUAK1 depletion or inhibition dramatically ameliorates gastric tumorigenesis. NUAK1 upregulates GLI1 expression by activating STAT5-mediated transcription and stabilizing GLI1 protein. NUAK1 depletion or inhibition impairs cancer cell expansion, tumor formation, and chemotherapy resistance in in vitro and in vivo models. Clinicopathological analysis confirms that upregulated NUAK1 expression correlates with poor prognosis and chemotherapy resistance in human GC. Our findings demonstrate that the signaling axis NUAK1/STAT5/GLI1 promotes cancer cell expansion and tumorigenesis and indicate that NUAK1 is an attractive therapeutic target and prognostic factor in GC.

E7-mediated repression of miR-203 promotes LASP1-dependent proliferation in HPV-positive cervical cancer

Human papillomaviruses (HPV) are a major cause of malignancy, contributing to ~5% of all human cancers worldwide, including most cervical cancer cases and a growing number of anogenital and oral cancers. The major HPV viral oncogenes, E6 and E7, manipulate many host cellular pathways that promote cell proliferation and survival, predisposing infected cells to malignant transformation. Despite the availability of highly effective vaccines, there are still no specific anti-viral therapies targeting HPV or treatments for HPV-associated cancers. As such, a better understanding of viral-host interactions may allow the identification of novel therapeutic targets. Here, we demonstrate that the actin-binding protein LASP1 is upregulated in cervical cancer and significantly correlates with a poorer overall survival. In HPV positive cervical cancer, LASP1 depletion significantly inhibited the oncogenic phenotype in vitro, whilst having minimal effects in HPV negative cervical cancer cells. Furthermore, we demonstrate that the LASP1 SH3 domain is essential for LASP1-mediated oncogenicity in these cells. Mechanistically, we show that HPV E7 regulates LASP1 at the post-transcriptional level by repressing the expression of miR-203, which negatively regulates LASP1 mRNA levels by binding to its 3'UTR. Finally, we demonstrate that LASP1 expression is required for the growth of HPV positive cervical cancer cells in an in vivo tumourigenicity model. Together, these data demonstrate that HPV induces LASP1 expression to promote proliferation and survival in cervical cancer, thus identifying a potential therapeutic target in these cancers.

E7-mediated repression of miR-203 promotes LASP1-dependent proliferation in HPV-positive cervical cancer

Human papillomaviruses (HPV) are a major cause of malignancy, contributing to ∼5% of all human cancers worldwide, including most cervical cancer cases and a growing number of ano-genital and oral cancers. The major HPV viral oncogenes, E6 and E7, manipulate many host cellular pathways that promote cell proliferation and survival, predisposing infected cells to malignant transformation. Despite the availability of highly effective vaccines, there are still no specific anti-viral therapies targeting HPV or treatments for HPV-associated cancers. As such, a better understanding of viral-host interactions may allow the identification of novel therapeutic targets. Here, we demonstrate that the actin-binding protein LASP1 is upregulated in cervical cancer and significantly correlates with a poorer overall survival. In HPV positive cervical cancer, LASP1 depletion significantly inhibited proliferation in vitro , whilst having minimal effects in HPV negative cervical cancer cells. Furthermore, we show that the LASP1 SH3 domain is essential for LASP1-mediated proliferation in these cells. Mechanistically, we show that HPV E7 regulates LASP1 at the post-transcriptional level by repressing the expression of miR-203, which negatively regulated LASP1 mRNA levels by binding to its 3'UTR. Finally, we demonstrated that LASP1 expression is required for the growth of HPV positive cervical cancer cells in an in vivo tumourigenicity model. Together, these data demonstrate that HPV induces LASP1 expression to promote proliferation and survival role in cervical cancer, thus identifying a potential therapeutic target in these cancers.

miRNAs as potential game-changers in bone diseases: Future medicinal and clinical uses

MicroRNAs (miRNAs), short, highly conserved non-coding RNA, influence gene expression by sequential mechanisms such as mRNA breakdown or translational repression. Many biological processes depend on these regulating substances, thus changes in their expression have an impact on the maintenance of cellular homeostasis and result in the emergence of a variety of diseases. Relevant studies have shown in recent years that miRNAs are involved in many stages of bone development and growth. Additionally, abnormal production of miRNA in bone tissues has been closely associated with the development of numerous bone disorders, such as osteonecrosis, bone cancer, and bone metastases. Many pathological processes, including bone loss, metastasis, the proliferation of osteosarcoma cells, and differentiation of osteoblasts and osteoclasts, are under the control of miRNAs. By bringing together the most up-to-date information on the clinical relevance of miRNAs in such diseases, this study hopes to further the study of the biological features of miRNAs in bone disorders and explore their potential as a therapeutic target.

miR-218-5p in endometrial microenvironment prevents the migration of ectopic endometrial stromal cells by inhibiting LASP1

BACKGROUND

Our previous two-dimensional electrophoresis experiment showed that the expression of LASP1 in patients with endometriosis was significantly higher than that of control endometrium. However, the molecular mechanism by which LASP1 is regulated in endometriosis/adenomyosis is unknown.

METHODS

Herein, qPCR was performed to analyze the expression levels of LASP1 and miR-218-5p between endometriosis (Ems) cells and control cells. Fluorescence in situ hybridization was carried out to measure the expression level of miR-218-5p in ectopic endometrium versus normal endometrium. After miR-218-5p mimic or inhibitor were transfected, the transwell experiment was carried out to see the effect of miR-218-5p on the migration of endometrial stromal cells (ESCs). EdU was used to measure cell proliferation rate. Dual-luciferase reporter assay was used to verify the binding of hsa-miR-218-5p to the 3'UTR of LASP1. Western blot and immunofluorescence analysis were carried out to identify the protein expression pattern of LASP1 and EMT markers in endometrial tissue.

RESULTS

The miR-218-5p is mainly secreted from blood vessels and expressed in the muscle layer around the endometrium, which inhibits the expression level of LASP1 by binding the 3'UTR region of LASP1 in normal ESCs. Overexpression of miR-218-5p impedes the epithelial-to-mesenchymal transition (EMT) and prevents the migration of ESCs and the expression of Vimentin in Ems.

CONCLUSIONS

Our findings revealed that miR-218-5p in endometrial microenvironment prevents the migration of ectopic endometrial stromal cells by inhibiting LASP1.

miRNA-guided reprogramming of glucose and glutamine metabolism and its impact on cell adhesion/migration during solid tumor progression

MicroRNAs (miRNAs) are small, non-coding RNAs about 22 nucleotides in length that regulate the expression of target genes post-transcriptionally, and are highly involved in cancer progression. They are able to impact a variety of cell processes such as proliferation, apoptosis and differentiation and can consequently control tumor initiation, tumor progression and metastasis formation. miRNAs can regulate, at the same time, metabolic gene expression which, in turn, influences relevant traits of malignancy such as cell adhesion, migration and invasion. Since the interaction between metabolism and adhesion or cell movement has not, to date, been well understood, in this review, we will specifically focus on miRNA alterations that can interfere with some metabolic processes leading to the modulation of cancer cell movement. In addition, we will analyze the signaling pathways connecting metabolism and adhesion/migration, alterations that often affect cancer cell dissemination and metastasis formation.

Molecular Mechanisms of Cutaneous Squamous Cell Carcinoma

Non-melanoma skin cancers are cutaneous malignancies representing the most common form of cancer in the United States. They are comprised predominantly of basal cell carcinomas and squamous cell carcinomas (cSCC). The incidence of cSCC is increasing, resulting in substantial morbidity and ever higher treatment costs; currently in excess of one billion dollars, per annum. Here, we review research defining the molecular basis and development of cSCC that aims to provide new insights into pathogenesis and drive the development of novel, cost and morbidity saving therapies.

Dietary palmitic acid promotes a prometastatic memory via Schwann cells

Fatty acid uptake and altered metabolism constitute hallmarks of metastasis^1,2, yet evidence of the underlying biology, as well as whether all dietary fatty acids are prometastatic, is lacking. Here we show that dietary palmitic acid (PA), but not oleic acid or linoleic acid, promotes metastasis in oral carcinomas and melanoma in mice. Tumours from mice that were fed a short-term palm-oil-rich diet (PA), or tumour cells that were briefly exposed to PA in vitro, remained highly metastatic even after being serially transplanted (without further exposure to high levels of PA). This PA-induced prometastatic memory requires the fatty acid transporter CD36 and is associated with the stable deposition of histone H3 lysine 4 trimethylation by the methyltransferase Set1A (as part of the COMPASS complex (Set1A/COMPASS)). Bulk, single-cell and positional RNA-sequencing analyses indicate that genes with this prometastatic memory predominantly relate to a neural signature that stimulates intratumoural Schwann cells and innervation, two parameters that are strongly correlated with metastasis but are aetiologically poorly understood^3,4. Mechanistically, tumour-associated Schwann cells secrete a specialized proregenerative extracellular matrix, the ablation of which inhibits metastasis initiation. Both the PA-induced memory of this proneural signature and its long-term boost in metastasis require the transcription factor EGR2 and the glial-cell-stimulating peptide galanin. In summary, we provide evidence that a dietary metabolite induces stable transcriptional and chromatin changes that lead to a long-term stimulation of metastasis, and that this is related to a proregenerative state of tumour-activated Schwann cells.

Diagnostic and Prognostic Value of MicroRNAs in Metastasis and Recurrence of Head and Neck Squamous Cell Carcinoma: A Systematic Review and Meta-Analysis

MicroRNAs have been proven to make remarkable differences in the clinical behaviors of head and neck squamous cell carcinoma (HNSCC). This study aims to systematically analyze whether differential expression levels of microRNAs are related to recurrence or metastasis in patients with HNSCC. A comprehensive search of the PubMed, EMBASE, and CENTRAL was conducted up to July 24^th, 2021. Data were collected and combined from studies reporting recurrence-free survival (RFS) of HNSCC patients with high microRNA expression compared to those with low expression. Besides, studies providing necessary data for evaluating the diagnostic value of microRNAs for detecting recurrence and metastasis based on their expression levels were also included and combined. The pooled hazard ratio (HR) value for the outcomes of RFS in 1,093 HNSCC samples from 10 studies was 2.51 (95%CI: 2.13–2.96). A sensitivity of 0.79 (95% CI: 0.72–0.85) and specificity of 0.77 (95%CI: 0.68–0.83) were observed in three studies, of which 93 patients with recurrence and 82 nonrecurrence controls were included, and the area under the curve (AUC) was 0.85 (95% CI: 0.81–0.88). Additionally, high diagnostic accuracy of microRNAs in detecting lymph node metastasis (LNM) was also reported. In conclusion, two panels of microRNAs showed the potential to predict recurrence or diagnose recurrence in HNSCC patients, respectively, which could facilitate prognosis prediction and diagnosis of clinical behaviors in HNSCC patients.

Nanoliposomal Delivery of MicroRNA-203 Suppresses Migration of Triple-Negative Breast Cancer through Distinct Target Suppression

Triple-negative breast cancers affect thousands of women in the United States and disproportionately drive mortality from breast cancer. MicroRNAs are small, non-coding RNAs that negatively regulate gene expression post-transcriptionally by inhibiting target mRNA translation or by promoting mRNA degradation. We have identified that miRNA-203, silenced by epithelial-mesenchymal transition (EMT), is a tumor suppressor and can promote differentiation of breast cancer stem cells. In this study, we tested the ability of liposomal delivery of miR-203 to reverse aspects of breast cancer pathogenesis using breast cancer and EMT cell lines. We show that translationally relevant methods for increasing miR-203 abundance within a target tissue affects cellular properties associated with cancer progression. While stable miR-203 expression suppresses LASP1 and survivin, nanoliposomal delivery suppresses BMI1, indicating that suppression of distinct mRNA target profiles can lead to loss of cancer cell migration.

MiR-130a Acts as a Tumor Suppressor MicroRNA in Cutaneous Squamous Cell Carcinoma and Regulates the Activity of the BMP/SMAD Pathway by Suppressing ACVR1

Cutaneous squamous cell carcinoma (cSCC) is a malignant neoplasm of the skin resulting from the accumulation of somatic mutations due to solar radiation. cSCC is one of the fastest increasing malignancies, and it represents a particular problem among immunosuppressed individuals. MicroRNAs are short noncoding RNAs that regulate the expression of protein-coding genes at the post-transcriptional level. In this study, we identify miR-130a to be downregulated in cSCC compared to healthy skin and precancerous lesions (actinic keratosis). Moreoever, we show that its expression is regulated at the transcriptional level by HRAS and MAPK signaling pathway. We demonstrate that overexpession of miR-130a suppresses long-term capacity of growth, cell motility and invasion ability of human cSCC cell lines. We report that miR-130a suppresses the growth of cSCC xenografts in mice. Mechanistically, miR-130a directly targets ACVR1 (ALK2), and changes in miR-130a levels result in the decreased activity of the BMP/SMAD pathway through ACVR1. These data reveal a link between activated MAPK signaling and decreased expression of miR-130a, which acts as a tumor-suppressor microRNA in cSCC and contribute to a better understanding of the molecular processes during malignant transformation of epidermal keratinocytes.

Signals from the Metastatic Niche Regulate Early and Advanced Ovarian Cancer Metastasis through miR-4454 Downregulation

Treatment of ovarian cancer is limited by extensive metastasis and yet it remains poorly understood. We have studied the critical step of metastatic colonization in the context of the productive interactions with the metastatic microenvironment with a goal of identifying key regulators. By combining miRNA expression analysis using an organotypic 3D culture model of early ovarian cancer metastasis with that of matched primary and metastatic tumors from 42 patients with ovarian cancer, we identified miR-4454 as a key regulator of both early colonization and advanced metastasis in patients with ovarian cancer. miR-4454 was downregulated in the metastasizing ovarian cancer cells through paracrine signals from microenvironmental fibroblasts, which promoted migration, invasion, proliferation, and clonogenic growth in ovarian cancer cells as well as their ability to penetrate through the outer layers of the omentum. Stable overexpression of miR-4454 decreased metastasis in ovarian cancer xenografts. Its mechanism of action was through the upregulation of its targets, secreted protein acidic and cysteine rich (SPARC) and BCL2 associated athanogene 5 (BAG5), which activated focal adhesion kinase (FAK) signaling, promoted mutant p53 gain of function by its stabilization, and inhibited apoptosis. Because microenvironment-induced downregulation of miR-4454 is essential for early and advanced metastasis, targeting it could be a promising therapeutic approach. IMPLICATIONS: This study identifies a miRNA, miR-4454, which is downregulated by signals from the microenvironment and promotes early and advanced ovarian cancer metastasis through its effects on FAK activation, mutant p53 stabilization, and apoptosis inhibition.

miR-622 is a novel potential biomarker of breast carcinoma and impairs motility of breast cancer cells through targeting NUAK1 kinase

BACKGROUND

Aberrant expression of microRNAs (miR) has been proposed as non-invasive biomarkers for breast cancers. The aim of this study was to analyse the miR-622 level in the plasma and in tissues of breast cancer patients and to explore the role of miR-622 and its target, the NUAK1 kinase, in this context.

METHODS

miR-622 expression was analysed in plasma and in tissues samples of breast cancer patients by q-RT-PCR. Bioinformatics programs, luciferase assay, public dataset analysis and functional experiments were used to uncover the role of miR-622 and its target in breast cancer cells.

RESULTS

miR-622 is downregulated in plasma and in tissues of breast cancer patients respect to healthy controls and its downregulation is significantly associated with advanced grade and high Ki67 level. Modulation of miR-622 affects the motility phenotype of breast cancer cells. NUAK1 kinase is a functional target of miR-622, it is associated with poor clinical outcomes of breast cancer patients and is inversely correlated with miR-622 level.

CONCLUSIONS

miR-622/NUAK1 axis is deregulated in breast cancer patients and affects the motility phenotype of breast cancer cells. Importantly, miR-622 and NUAK1 hold promises as biomarkers and as targets for breast cancers.

Implication of the p53-Related miR-34c, -125b, and -203 in the Osteoblastic Differentiation and the Malignant Transformation of Bone Sarcomas

The formation of the skeleton occurs throughout the lives of vertebrates and is achieved through the balanced activities of two kinds of specialized bone cells: the bone-forming osteoblasts and the bone-resorbing osteoclasts. Impairment in the remodeling processes dramatically hampers the proper healing of fractures and can also result in malignant bone diseases such as osteosarcoma. MicroRNAs (miRNAs) are a class of small non-coding single-strand RNAs implicated in the control of various cellular activities such as proliferation, differentiation, and apoptosis. Their post-transcriptional regulatory role confers on them inhibitory functions toward specific target mRNAs. As miRNAs are involved in the differentiation program of precursor cells, it is now well established that this class of molecules also influences bone formation by affecting osteoblastic differentiation and the fate of osteoblasts. In response to various cell signals, the tumor-suppressor protein p53 activates a huge range of genes, whose miRNAs promote genomic-integrity maintenance, cell-cycle arrest, cell senescence, and apoptosis. Here, we review the role of three p53-related miRNAs, miR-34c, -125b, and -203, in the bone-remodeling context and, in particular, in osteoblastic differentiation. The second aim of this study is to deal with the potential implication of these miRNAs in osteosarcoma development and progression.

MicroRNAs and Metastasis

Metastasis, the development of secondary malignant growths at a distance from the primary site of a cancer, is associated with almost 90% of all cancer deaths, and half of all cancer patients present with some form of metastasis at the time of diagnosis. Consequently, there is a clear clinical need for a better understanding of metastasis. The role of miRNAs in the metastatic process is beginning to be explored. However, much is still to be understood. In this review, we present the accumulating evidence for the importance of miRNAs in metastasis as key regulators of this hallmark of cancer.

Epigenetic inactivation of miR-203 as a key step in neural crest epithelial-to-mesenchymal transition

miR-203 is a tumor-suppressor microRNA with known functions in cancer metastasis. Here, we explore its normal developmental role in the context of neural crest development. During the epithelial-to-mesenchymal transition of neural crest cells to emigrate from the neural tube, miR-203 displays a reciprocal expression pattern with key regulators of neural crest delamination, Phf12 and Snail2, and interacts with their 3'UTRs. We show that ectopic maintenance of miR-203 inhibits neural crest migration in chick, whereas its functional inhibition using a 'sponge' vector or morpholinos promotes premature neural crest delamination. Bisulfite sequencing further shows that epigenetic repression of miR-203 is mediated by the de novo DNA methyltransferase DNMT3B, the recruitment of which to regulatory regions on the miR-203 locus is directed by SNAIL2 in a negative-feedback loop. These findings reveal an important role for miR-203 in an epigenetic-microRNA regulatory network that influences the timing of neural crest delamination.

NUAK1 knockdown suppresses prostate cancer cell epithelial-mesenchymal transition, migration, and invasion through microRNA-30b-5p

OBJECTIVE

Prostate cancer is one of the most diagnosed malignancies in men worldwide. Novel (nua) kinase family 1 (NUAK1) is a member of adenosine monophosphate (AMP)-related kinase which participates in varying cancers progression. However, the role of NUAK1 in prostate tumorigenesis has not been fully characterized. The aim of this study was to elucidate the potential biological role of NUAK1 in prostate cancer.

METHODS

Quantitative real-time PCR (qRT-PCR) was performed to determine the expression levels of NUAK1 and microRNA-30b-5p (miRNA-30b-5p) in prostate cancer cell lines and samples. Western blot was conducted to explore the related protein levels of epithelial-mesenchymal transition (EMT) and NUAK1 expression in prostate cancer cells. Trans-well test was used to assay prostate cancer cell migration and invasion. Luciferase assays were employed to probe the interaction between NUAK1 and miR-30b-5p.

RESULTS

NUAK1 abundance was enhanced in prostate cancer tissues and cell lines. The knockdown of NUAK1 may inhibit prostate cancer cells EMT, migration and invasion. Luciferase assays suggested NUAK1 was a target gene of miR-30b-5p. Furthermore, miR-30b-5p suppressed EMT, migration, and invasion in prostate cancer cells and introduction of NUAK1 abated the inhibitory effect.

CONCLUSIONS

Both of NUAK1 and miR-30b-5p were required for prostate cancer progression. NUAK1 interference limited prostate cancer cell EMT, migration and invasion by miRNA-30b-5p modulating, providing a promising therapeutic approach for prostate cancer.

New Frontiers for the Cytoskeletal Protein LASP1

In the recent two decades, LIM and SH3 protein 1 (LASP1) has been developed from a simple actin-binding structural protein to a tumor biomarker and subsequently to a complex, nuclear transcriptional regulator. Starting with a brief historical perspective, this review will mainly compare and contrast LASP1 and LASP2 from the angle of the newest data and importantly, examine their role in transcriptional regulation. We will summarize the current knowledge through pictorial models and tables including the roles of different microRNAs in the differential regulation of LASP1 levels and patient outcome rather than specify in detail all tumor entities. Finally, the novel functional roles of LASP1 in secretion of vesicles, expression of matrix metalloproteinases and transcriptional regulation as well as the activation of survival and proliferation pathways in different cancer types are described.

Elucidating the microRNA-203 specific biological processes in glioblastoma cells from comprehensive RNA-sequencing transcriptome profiling

Glioblastoma (GBM) is the most common primary malignant intracranial adult brain tumor. Allelic deletion on chromosome 14q plays an essential role in GBM pathogenesis, and this chromosome 14q site was thought to harbor multiple tumor suppressor genes associated with GBM, a region that also encodes microRNA-203 (miR-203). This study was conducted to identify whole transcriptome profile changes associated with miR-203 expression by high-throughput RNA sequencing. Enrichment analyses for gene ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway analysis revealed that miR-203 expression had a strong, negative effect on a number of fundamental and interconnected biological processes involved in cell growth and proliferation. The biological processes mostly influenced were p53 signaling pathway, FoxO signaling pathway, DNA replication, cell cycle, MAPK signaling pathway, and apoptosis. In total, 847 upregulated and 345 downregulated differentially expressed genes were identified in control versus miR-203 expressing glioma cells. After GO enrichment, the downregulated differentially expressed genes such as BCL2, SPARC were found to be mainly enriched in cell cycle regulation and apoptosis processes, whereas the upregulated differentially expressed genes such as CCND1, E2F1 were involved in the DNA replication and cell cycle regulation. We also performed miR-203 target analysis and found BCL2, AKT, SPARC, ROBO1, c-JUN, PDGFA, and CREB were predicted target of miR-203 and miR-203 expression suppressed the protein and mRNA levels of these target genes by western blotting and qRT-PCR analysis. Moreover, co-transfection experiments using a luciferase-based reporter assay demonstrated that miR-203 directly regulated BCL-2 expression and BCL-2 overexpression suppressed miR-203 mediated glioma cell apoptosis. These results indicate that overexpression of miR-203 coordinately regulates several oncogenic pathways in GBM.

Epithelial-mesenchymal transition and microRNAs: Challenges and future perspectives in oral cancer

BACKGROUND

Head and neck cancer is the sixth most common cancer worldwide, with oral squamous cell carcinoma (OSCC) being the most representative type. OSCC is a public health problem with high morbidity and poor survival rate. Epithelial-mesenchymal transition is emerging as a hallmark in OSCC.

METHODS

In this study, we described the role of microRNAs in epithelial-mesenchymal transition regulation in OSCC based on a PubMed search using articles published in English between January 1, 2010, and January 31, 2018.

RESULTS

MicroRNA's regulatory networks seem to be a hallmark of epithelial-mesenchymal transition in OSCC pathophysiology becoming a growing challenge to design new studies and strategies from biology to clinical applications.

CONCLUSION

Therefore, we propose that targeting therapies to epithelial-mesenchymal transition-type cells, namely, coordinating microRNAs and/or hydrophobic drugs, such as conventional therapy, could be a promising strategy to improve the outcomes of patients with OSCC.

Clinicopathological significance of miR-26, miR-107, miR-125b, and miR-203 in head and neck carcinomas

OBJECTIVES

MicroRNAs play a role in the development and progression of head and neck squamous cell carcinomas (HNSCC). Our aim was to study the expression of miR-26, miR-107, miR-125b, and miR-203 in primary HNSCC with and without lymph node metastasis and their clinicopathological significance.

MATERIALS AND METHODS

The expression of microRNAs in primary HNSCC with lymph node metastasis (n = 16) and their matched lymph node, as well as primary tumors without metastasis (n = 16), were determined by quantitative RT-PCR and analyzed with clinicopathological features and survival.

RESULTS

The expression levels of miR-26 (p < .05) and miR-125b (p < .01) were higher in metastatic primary HNSCC, while levels of miR-203 (p < .01) were lower. The expression of the microRNAs was associated with clinicopathological features, including miR-26 high expression and N stage (p = .04), poor differentiation (p = .005) and recurrence (p = .007), miR-125b high expression and N stage (p = .0005) and death (p = .02), and low levels of miR-203 and N stage (p = .04). The high expression of miR-26 was associated with shortened disease-free survival, and high miR-125b expression was an independent risk factor for poor disease-specific survival.

CONCLUSIONS

These findings suggest that miR-26 and miR-125b may be associated with the progression and metastasis of HNSCC and that miR-203 is associated with a more favorable prognosis.

Colorectal Tumors Require NUAK1 for Protection from Oxidative Stress

Exploiting oxidative stress has recently emerged as a plausible strategy for treatment of human cancer, and antioxidant defenses are implicated in resistance to chemotherapy and radiotherapy. Targeted suppression of antioxidant defenses could thus broadly improve therapeutic outcomes. Here, we identify the AMPK-related kinase NUAK1 as a key component of the antioxidant stress response pathway and reveal a specific requirement for this role of NUAK1 in colorectal cancer. We show that NUAK1 is activated by oxidative stress and that this activation is required to facilitate nuclear import of the antioxidant master regulator NRF2: Activation of NUAK1 coordinates PP1β inhibition with AKT activation in order to suppress GSK3β-dependent inhibition of NRF2 nuclear import. Deletion of NUAK1 suppresses formation of colorectal tumors, whereas acute depletion of NUAK1 induces regression of preexisting autochthonous tumors. Importantly, elevated expression of NUAK1 in human colorectal cancer is associated with more aggressive disease and reduced overall survival.Significance: This work identifies NUAK1 as a key facilitator of the adaptive antioxidant response that is associated with aggressive disease and worse outcome in human colorectal cancer. Our data suggest that transient NUAK1 inhibition may provide a safe and effective means for treatment of human colorectal cancer via disruption of intrinsic antioxidant defenses. Cancer Discov; 8(5); 632-47. ©2018 AACR.This article is highlighted in the In This Issue feature, p. 517.

Upregulation of the long non-coding RNA PVT1 promotes esophageal squamous cell carcinoma progression by acting as a molecular sponge of miR-203 and LASP1

Long non-coding RNAs are a group of non-coding RNAs longer than 200 nucleotides and possess diverse functions and exhibit exquisite cell-specific and developmental dynamic expression patterns. The role of the long non-coding RNA PVT1 in esophageal squamous cell carcinoma remains unsolved. Here, we showed that PVT1 expression is significantly up-regulated in ESCC tumor samples compared with their normal counterparts. Knockdown of PVT1 suppressed tumor growth in vitro and in vivo. Further studies revealed that silence of PVT1 lead to up-regulation of miR-203, and vice versa. Moreover, LASP1 was found to be downregulated after knockdown of PVT1 and overexpression of LASP1 attenuated the tumor-suppressive roles of PVT1 knockdown. Our results suggest that PVT1 promote ESCC progression via functioning as a molecular sponge for miR-203 and LASP1 and provide the first evidence of dysregulated PVT1/miR-203/LASP1 axis in ESCC.

Calcium signalling links MYC to NUAK1

NUAK1 is a member of the AMPK-related family of kinases. Recent evidence suggests that NUAK1 is an important regulator of cell adhesion and migration, cellular and organismal metabolism, and regulation of TAU stability. As such, NUAK1 may play key roles in multiple diseases ranging from neurodegeneration to diabetes and metastatic cancer. Previous work revealed a crucial role for NUAK1 in supporting viability of tumour cells specifically when MYC is overexpressed. This role is surprising, given that NUAK1 is activated by the tumour suppressor LKB1. Here we show that, in tumour cells lacking LKB1, NUAK1 activity is maintained by an alternative pathway involving calcium-dependent activation of PKCα. Calcium/PKCα-dependent activation of NUAK1 supports engagement of the AMPK-TORC1 metabolic checkpoint, thereby protecting tumour cells from MYC-driven cell death, and indeed, MYC selects for this pathway in part via transcriptional regulation of PKCα and ITPR. Our data point to a novel role for calcium in supporting tumour cell viability and clarify the synthetic lethal interaction between NUAK1 and MYC.

hsa-miR-29c-3p regulates biological function of colorectal cancer by targeting SPARC

Colorectal cancer (CRC) is the most common type of behavioral cancers, miRNAs play a critical role in cancer development and progression. In the present study, we downloaded the original data from Gene Expression Omnibus (GEO) and conduct data analysis. has-mir-29c-3p mimic, inhibitor, negative control or si-SPARC (secreted protein acidic, rich in cysteine) were transfected into HCT116 cells, respectively. Quantitative real time PCR (qRT-PCR) was used to measure has-mir-29c-3p and SPARC mRNA expressions, western blot was used to detect ACAA1 (acetyl-CoA acyltransferase 1), ACOX1 (acyl-CoA oxidase 1), COL1A1(collagen, type I, alpha-1), COL1A2 (collagen, type I, alpha-2), COL4A1 (collagen, type IV, alpha-1), COL5A2 (collagen, type V, alpha-2), COL12A1 (collagen, type XII, alpha-1), CPT2 (carnitine palmitoyltransferase 2), ETHE1 (persulfide dioxygenase), HMGCS2 (3-hydroxy-3-methylglutaryl-CoA synthase 2), SPARC, SQRDL (sulfide quinone oxidoreductase), and TST (thiosulfate sulfurtransferase) protein expression. CCK-8 and wound healing assay were employed to verify cell proliferation and migration. The luciferase reporter assay data made sure the target correlation of has-mir-29c-3p and SPARC. Firstly, we found that the expression of has-mir-29c-3p was lower in CRC tissues than in their paired corresponding non-cancerous tissues and there was significant inversed correlation between has-mir-29c-3p and SPARC. Overexpression of has-mir-29c-3p reduced cell proliferation and migration. SPARC was identified as a direct target of has-mir-29c-3p, whose silencing reduced cell proliferation and migration. These data showed that has-mir-29c-3p regulates CRC cell functions through regulating SPARC expression. Taken together, has-mir-29c-3p may function as an oncogenic miRNA targeting SPARC, targeted modulation of has-mir-29c-3p expression may became a potential strategy for the treatment.

MiR-203a-3p suppresses cell proliferation and metastasis through inhibiting LASP1 in nasopharyngeal carcinoma

BACKGROUND

miR-203a-3p was reported as a tumor suppressor and disregulated in many malignancies including nasopharyngeal carcinoma (NPC). However, its function in tumor growth and metastasis in NPC has rarely been reported.

METHODS

The expression level of miR-203a-3p in human NPC tissues and cell lines was detected via real-time PCR (RT-PCR). Cell proliferation, migration and invasion were assessed in vitro by MTT, colony formation and transwell assay, respectively. The function of miR-203a-3p in vivo was detected through NPC xenograft tumor growth and lung metastatic mice model. Dual-luciferase reporter assay was used to identify the direct target of miR-203a-3p.

RESULTS

The expression of miR-203a-3p was decreased in NPC tissues and cell lines in comparison with normal nasopharyngeal tissues and cell line. Ectopic expression of miR-203a-3p inhibited while inhibiting miR-203a-3p expression increased NPC cell proliferation, migration and invasion in vitro. MR-203a-3p overexpression suppressed xenograft tumor growth and lung metastasis in vivo. LASP1 was identified as a direct target of miR-203a-3p, which was confirmed by real-time PCR and western blotting assay. Ectopic expression of LASP1 partially reversed miR-203a-3p-mediated inhibition on proliferation, migration and invasion in NPC cells.

CONCLUSION

Collectively, miR-203a-3p suppresses tumor growth and metastasis through targeting LASP1 in NPC. The newly identified miR-203a-3p/LASP1 pathway provides further insights into the initiation and progression of NPC, which may represent a novel therapeutic target for NPC.

Epigenetic silencing of miR-203 in Kazakh patients with esophageal squamous cell carcinoma by MassARRAY spectrometry

Dysregulation of miR-203 by promoter methylation is associated with the development of various cancers. We aimed to explore the underlying link between promoter methylation and miR-203 expression in Kazakh esophageal squamous cell carcinoma (ESCC). MassARRAY® System spectrometry was used to quantitatively analyze the DNA methylation of 32 CpG sites within miR-203 in 99 Kazakh ESCC and 46 normal esophageal tissues (NETs) with similar population characteristics. We conducted real-time PCR to detect miR-203 expression levels and evaluated their association with methylation. Eleven CpG units within miR-203 promoter were frequently hypermethylated in ESCC compared with NETs (P < 0.05). The hypermethylation of several CpG units positively correlated with age, lower esophagus, constrictive type of ESCC, and moderately differentiated ESCC. Given the involvement of human papillomavirus (HPV) in etiology of ESCC was confirmed from our previous reports, herein we found that CpG units within miR-203 in HPV16-positive ESCC are more heavily methylated. Furthermore, miR-203 expression showed a nearly 4.5-fold decrease in ESCC than NETs (0.206 ± 0.336 vs. 0.908 ± 1.424, P < 0.001) and was significantly associated with lymph node metastasis (P = 0.012). The expression of miR-203 with 11 completely hypermethylated CpG units was approximately 6.5-fold lower than that with at least 1 unmethylated CpG unit (P < 0.001) and especially the CpG_15.16 and CpG_31.32 with higher methylation levels in ESCC tissues exhibited lower expression levels of miR-203, which indicated a reverse association between miR-203 methylation and expression. Hypermethylated miR-203 is a potential biomarker and targeted delivery of miR-203 could therefore serve as a preventive or therapeutic strategy for Kazakh ESCC.

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

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

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

microRNA-203 suppresses invasion and epithelial-mesenchymal transition induction via targeting NUAK1 in head and neck cancer

Head and neck squamous cell carcinoma (HNSCC) has a high capacity for invasion. To identify microRNAs (miRNAs) that regulate HNSCC invasion, we compared miRNA expression profiles between a parent HNSCC cell line and a highly invasive clone. The miR-200 family and miR-203 were downregulated in the clone. Here we focused on the role of miR-203 in invasion and epithelial-mesenchymal transition (EMT) induction in HNSCC. miR-203 was downregulated during EMT induction. Moreover, ectopic overexpression of miR-203 suppressed the invasion and induced mesenchymal-epithelial transition (MET) in HNSCC cells. Interestingly, we identified NUAK family SNF1-like kinase 1 (NUAK1) as a novel target gene of miR-203 by cyclopedic analysis using anti-Ago2 antibody. Increased expression of NUAK1 was observed during EMT induction, and ectopic expression of miR-203 delayed EMT induction by suppressing NUAK1 expression. Moreover, NUAK1 overexpression promoted the invasion of HNSCC cells. Importantly, NUAK1 expression was well correlated with poor differentiation, invasiveness, and lymph node metastasis in HNSCC cases. Overall, miR-203 has a tumor-suppressing role in invasion and EMT induction by targeting NUAK1 in HNSCC, suggesting miR-203 as a potential new diagnostic and therapeutic target for the treatment of HNSCC.

Targeting metastasis-initiating cells through the fatty acid receptor CD36

The fact that the identity of the cells that initiate metastasis in most human cancers is unknown hampers the development of antimetastatic therapies. Here we describe a subpopulation of CD44^bright cells in human oral carcinomas that do not overexpress mesenchymal genes, are slow-cycling, express high levels of the fatty acid receptor CD36 and lipid metabolism genes, and are unique in their ability to initiate metastasis. Palmitic acid or a high-fat diet specifically boosts the metastatic potential of CD36⁺ metastasis-initiating cells in a CD36-dependent manner. The use of neutralizing antibodies to block CD36 causes almost complete inhibition of metastasis in immunodeficient or immunocompetent orthotopic mouse models of human oral cancer, with no side effects. Clinically, the presence of CD36⁺ metastasis-initiating cells correlates with a poor prognosis for numerous types of carcinomas, and inhibition of CD36 also impairs metastasis, at least in human melanoma- and breast cancer-derived tumours. Together, our results indicate that metastasis-initiating cells particularly rely on dietary lipids to promote metastasis.

miR-203 inhibits the traumatic heterotopic ossification by targeting Runx2

Emerging evidence has indicated that dysregulated microRNAs (miRNAs) have an important role in bone formation. However, the pathophysiological role of miRNAs in traumatic heterotopic ossification (HO) remains to be elucidated. Using gene expression profile analyses and subsequent confirmation with real-time PCR assays, we identified the decreased expression of miRNA-203 (miR-203) and increased expression of Runx2 as responses to the development of traumatic HO. We found that miR-203 expression was markedly higher in primary and recurrent HO tissues than in normal bones. The upregulation of miR-203 significantly decreased the level of Runx2 expression, whereas miR-203 downregulation increased Runx2 expression. Mutation of the putative miR-203-binding sites in Runx2 mRNA abolished miR-203-mediated repression of Runx2 3'-untranslated region luciferase reporter activity, indicating that Runx2 is an important target of miR-203 in osteoblasts. We also found that miR-203 is negatively correlated with osteoblast differentiation. Furthermore, in vitro osteoblast activity and matrix mineralization were promoted by antagomir-203 and decreased by agomir-203. We showed that miR-203 suppresses osteoblast activity by inhibiting the β-catenin and extracellular signal-regulated kinase pathways. Moreover, using a tenotomy mouse HO model, we found an inhibitory role of miR-203 in regulating HO in vivo; pretreatment with antagomiR-203 increased the development of HO. These data suggest that miR-203 has a crucial role in suppressing HO by directly targeting Runx2 and that the therapeutic overexpression of miR-203 may be a potential strategy for treating traumatic HO.

MicroRNA-203 Inversely Correlates with Differentiation Grade, Targets c-MYC, and Functions as a Tumor Suppressor in cSCC

Cutaneous squamous cell carcinoma (cSCC) is the second most common cancer and a leading cause of cancer mortality among solid organ transplant recipients. MicroRNAs (miR) are short RNAs that regulate gene expression and cellular functions. Here, we show a negative correlation between miR-203 expression and the differentiation grade of cSCC. Functionally, miR-203 suppressed cell proliferation, cell motility, and the angiogenesis-inducing capacity of cSCC cells in vitro and reduced xenograft tumor volume and angiogenesis in vivo. Transcriptomic analysis of cSCC cells with ectopic overexpression of miR-203 showed dramatic changes in gene networks related to cell cycle and proliferation. Transcription factor enrichment analysis identified c-MYC as a hub of miR-203-induced transcriptomic changes in squamous cell carcinoma. We identified c-MYC as a direct target of miR-203. Overexpression of c-MYC in rescue experiments reversed miR-203-induced growth arrest in cSCC, which highlights the importance of c-MYC within the miR-203-regulated gene network. Together, miR-203 acts as a tumor suppressor in cSCC, and its low expression can be a marker for poorly differentiated tumors. Restoration of miR-203 expression may provide a therapeutic benefit, particularly in poorly differentiated cSCC.

MicroRNA screening identifies a link between NOVA1 expression and a low level of IKAP in familial dysautonomia

Familial dysautonomia (FD) is a rare neurodegenerative disease caused by a mutation in intron 20 of the IKBKAP gene (c.2204+6T>C), leading to tissue-specific skipping of exon 20 and a decrease in the synthesis of the encoded protein IKAP (also known as ELP1). Small non-coding RNAs known as microRNAs (miRNAs) are important post-transcriptional regulators of gene expression and play an essential role in the nervous system development and function. To better understand the neuronal specificity of IKAP loss, we examined expression of miRNAs in human olfactory ecto-mesenchymal stem cells (hOE-MSCs) from five control individuals and five FD patients. We profiled the expression of 373 miRNAs using microfluidics and reverse transcription coupled to quantitative PCR (RT-qPCR) on two biological replicate series of hOE-MSC cultures from healthy controls and FD patients. This led to the total identification of 26 dysregulated miRNAs in FD, validating the existence of a miRNA signature in FD. We then selected the nine most discriminant miRNAs for further analysis. The signaling pathways affected by these dysregulated miRNAs were largely within the nervous system. In addition, many targets of these dysregulated miRNAs had been previously demonstrated to be affected in FD models. Moreover, we found that four of our nine candidate miRNAs target the neuron-specific splicing factor NOVA1. We demonstrated that overexpression of miR-203a-3p leads to a decrease of NOVA1, counter-balanced by an increase of IKAP, supporting a potential interaction between NOVA1 and IKAP. Taken together, these results reinforce the choice of miRNAs as potential therapeutic targets and suggest that NOVA1 could be a regulator of FD pathophysiology.

Summary: A miRNA screening conducted in olfactory stem cells from patients links the neuron-specific splicing factor NOVA1 to neurodegeneration in familial dysautonomia.

Mesenchymal to Epithelial Transition Induced by Reprogramming Factors Attenuates the Malignancy of Cancer Cells

Epithelial to mesenchymal transition (EMT) is a biological process of metastatic cancer. However, an effective anticancer therapy that directly targets the EMT program has not yet been discovered. Recent studies have indicated that mesenchymal to epithelial transition (MET), the reverse phenomenon of EMT, is observed in fibroblasts during the generation of induced pluripotent stem cells. In the present study, we investigated the effects of reprogramming factors (RFs) on squamous cell carcinoma (SCC) cells. RFs-introduced cancer cells (RICs) demonstrated the enhanced epithelial characteristics in morphology with altered expression of mRNA and microRNAs. The motility and invasive activities of RICs in vitro were significantly reduced. Furthermore, xenografts of RICs exhibited no lymph node metastasis, whereas metastasis was detected in parental SCC-inoculated mice. Thus, we concluded that RICs regained epithelial properties through MET and showed reduced cancer malignancy in vitro and in vivo. Therefore, the understanding of the MET process in cancer cells by introduction of RFs may lead to the designing of a novel anticancer strategy.

Loss of miR-203 regulates cell shape and matrix adhesion through ROBO1/Rac/FAK in response to stiffness

Breast tumor progression is accompanied by changes in the surrounding extracellular matrix (ECM) that increase stiffness of the microenvironment. Mammary epithelial cells engage regulatory pathways that permit dynamic responses to mechanical cues from the ECM. Here, we identify a SLIT2/ROBO1 signaling circuit as a key regulatory mechanism by which cells sense and respond to ECM stiffness to preserve tensional homeostasis. We observed that Robo1 ablation in the developing mammary gland compromised actin stress fiber assembly and inhibited cell contractility to perturb tissue morphogenesis, whereas SLIT2 treatment stimulated Rac and increased focal adhesion kinase activity to enhance cell tension by maintaining cell shape and matrix adhesion. Further investigation revealed that a stiff ECM increased Robo1 levels by down-regulating miR-203. Consistently, patients whose tumor expressed a low miR-203/high Robo1 expression pattern exhibited a better overall survival prognosis. These studies show that cells subjected to stiffened environments up-regulate Robo1 as a protective mechanism that maintains cell shape and facilitates ECM adherence.

Strand-specific in vivo screen of cancer-associated miRNAs unveils a role for miR-21(∗) in SCC progression

MicroRNAs play diverse roles in both normal and malignant stem cells. Focusing on miRs and/or miR(∗)s abundant in squamous cell carcinoma (SCC) stem cells, we engineer an efficient, strand-specific expression library, and apply functional genomics screening in mice to identify which of 169 cancer-associated miRs are key drivers in malignant progression. Not previously linked functionally to cancer, miR-21(∗) was the second top hit, surfacing in >12% of tumours. miR-21(∗) also correlates with poor prognosis in human SCCs and enhances tumour progression in xenografts. On deleting the miR-21 gene and rescuing each strand separately, we document the dual, but independent, oncogenicity of miR-21 and miR-21(∗). A cohort of predicted miR-21(∗) targets inversely correlate with miR-21(∗) in SCCs. Of particular interest is Phactr4, which we show is a miR-21(∗) target in SCCs, acting through the Rb/E2F cell cycle axis. Through in vivo physiological miR screens, our findings add an interesting twist to an increasingly important oncomiR locus.

Diagnostic and prognostic values of tissue hsa-miR-30c and hsa-miR-203 in prostate carcinoma

Prostate cancer (PCa) has become a prevalent malignant disease in males globally. Accumulating data suggested that hsa-microRNAs (miRNAs) could be potential biomarkers for tumor diagnosis due to their important roles in the cell cycle. This study investigated the diagnostic and prognostic values of hsa-miR-203 and hsa-miR-30c in PCa tissues. There were 44 pathologically confirmed PCa patients who were enrolled in this study. Tissue samples were collected from both tumor tissues and adjacent normal tissues. RNA was extracted and the expression levels of hsa-miR-203 and hsa-miR-30c in tumor and normal tissues were compared. The receiver operating characteristic (ROC) curves were plotted to evaluate the reliability of hsa-miR-203 and hsa-miR-30c in detecting PCa. All subjects in this study were followed up by 36 months, and the Kaplan-Meier method was conducted to investigate the survival status of PCa patients. The average relative expressions of hsa-miR-203 and hsa-miR-30c in tumor tissues were significantly different from those in adjacent normal tissues (P < 0.001), and the predictive power of the two hsa-miRNAs for PCa prognosis was reliable. Besides that, the average survival times of low-hsa-miR-30c and high-hsa-miR-203 groups were significantly lower than those of the corresponding groups with the log-rank P of 0.015 and 0.023, respectively. In summary, our study suggested that both hsa-miR-203 and hsa-miR-30c are potential biomarkers for detection and prognosis of PCa.

Evidence of cancer-promoting roles for AMPK and related kinases

The discovery that the 5'AMP-activated protein kinase (AMPK) serves to link the tumour suppressors LKB1 and the tuberous sclerosis complex and functions to slow macromolecular synthesis through attenuation of the mechanistic target of rapamycin complex 1 revealed a role for AMPK in tumour suppression. On the other hand, the well-recognized role of AMPK in maintaining ATP homeostasis, through suppression of anabolism and promotion of catabolism, as well as the role of AMPK in neutralizing reactive oxygen species, via maintenance of NADPH-dependent reductive capacity, point to tumour-protective roles in the context of metabolic stress, which is a key feature of many solid tumours. A growing number of studies thus suggest a duality of functions for AMPK that are either pro- or anti-cancer, depending upon context. Importantly, AMPK is composed of three subunits, and multiple isoforms exist for all three, allowing for different permutations to assemble and the potential for specific AMPK complexes to regulate distinct cellular processes. Moreover, certain subunits of the AMPK complex are frequently overexpressed in a spectrum of human cancer types, suggesting an outright oncogenic function for specific AMPK complexes. Adding complexity to this picture, the catalytic AMPK alpha subunits belong to a family of 14 kinases that can all be activated by LKB1 and studies are beginning to reveal a similar duality of roles in cancer for other members of the AMPK-related kinase family.

miR-381 suppresses C/EBPα-dependent Cx43 expression in breast cancer cells

miR-381 suppressed CX43 expression by directly targeting the 3′-UTR of C/EBPα, a novel transcription factor of Cx43 in human breast cancer cells. The miR-381–Cx43 axis might be a useful diagnostic and therapeutic target of metastatic breast cancer.

Cx43 (connexin43) is an enhancer of the metastasis of breast cancer cells. Our previous study identified miR-381 as an indirect suppressor of Cx43 gene expression, with the precise mechanism being not understood. In the present study, using a reporter gene assay, we found that miR-381 suppressed Cx43 gene expression via the promoter region −500/−250. With site-directed gene mutation, we demonstrated that miR-381 could directly bind with the sequences CACUUGUAU in the 3′-UTR so as to inhibit C/EBPα (CCAAT/enhancer-binding protein α) expression. C/EBPα was further identified as a novel transcription factor by binding to a canonic element (AATTGTC) locating at −459/−453 in the promoter region of the Cx43 gene. Functionally, we demonstrated that miR-381 suppressed C/EBPα- and Cx43-dependent migration and invasion of breast cancer cells. Finally, we revealed that decreased levels of miR-381 as well as increased expression of C/EBPα and Cx43 in the metastatic breast cancer cells and tissues. Therefore we are the first to identify that miR-381 suppresses C/EBPα-dependent Cx43 expression in breast cancer cells. The miR-381–C/EBPα–Cx43 axis might be a useful diagnostic and therapeutic target of metastatic breast cancer.

Identification of miR-200a as a novel suppressor of connexin 43 in breast cancer cells

We demonstrated that miRNA (miR)-200a inhibited connexin 43 (Cx43) expression by directly targeting at the 3’-UTR of Cx43 gene in human breast cancer cells. The miR-200a/Cx43 axis might be a useful diagnostic and therapeutic target of metastatic breast cancer.

Both miRNAs (miRs) and connexin 43 (Cx43) were important regulators of the metastasis of breast cancer, whereas the miRs regulating Cx43 expression in breast cancer cells were still obscure. In the present study, we scanned and found miR-1, miR-206, miR-200a, miR-381, miR-23a/b and miR-186 were functional suppressors of human Cx43 mRNA and protein expression. Specially, we demonstrated that only miR-200a could directly target the 3′-untranslated region (3′-UTR) of human Cx43 gene. Functionally, overexpression of Cx43 in MCF cells potentiated the migration activity, whereas additional miR-200a treatment notably prevented this effect. Finally, we demonstrated that decreased levels of miR-200a and elevated expression of Cx43 in the metastatic breast cancer tissues compared with the primary ones. Thus, we are the first to identify miR-200a as a novel and direct suppressor of human Cx43, indicating that miR200a/Cx43 axis might be a useful diagnostic and therapeutic target of metastatic breast cancer.

An update on the LIM and SH3 domain protein 1 (LASP1): a versatile structural, signaling, and biomarker protein

The gene encoding the LIM and SH3 domain protein (LASP1) was cloned two decades ago from a cDNA library of breast cancer metastases. As the first protein of a class comprising one N-terminal LIM and one C-terminal SH3 domain, LASP1 founded a new LIM-protein subfamily of the nebulin group. Since its discovery LASP1 proved to be an extremely versatile protein because of its exceptional structure allowing interaction with various binding partners, its ubiquitous expression in normal tissues, albeit with distinct expression patterns, and its ability to transmit signals from the cytoplasm into the nucleus. As a result, LASP1 plays key roles in cell structure, physiological processes, and cell signaling. Furthermore, LASP1 overexpression contributes to cancer aggressiveness hinting to a potential value of LASP1 as a cancer biomarker.

In this review we summarize published data on structure, regulation, function, and expression pattern of LASP1, with a focus on its role in human cancer and as a biomarker protein. In addition, we provide a comprehensive transcriptome analysis of published microarrays (n=2,780) that illustrates the expression profile of LASP1 in normal tissues and its overexpression in a broad range of human cancer entities.

MicroRNA-203 represses selection and expansion of oncogenic Hras transformed tumor initiating cells

In many mouse models of skin cancer, only a few tumors typically form even though many cells competent for tumorigenesis receive the same oncogenic stimuli. These observations suggest an active selection process for tumor-initiating cells. Here, we use quantitative mRNA- and miR-Seq to determine the impact of Hras^G12V on the transcriptome of keratinocytes. We discover that microRNA-203 is downregulated by Hras^G12V. Using a knockout mouse model, we demonstrate that loss of microRNA-203 promotes selection and expansion of tumor-initiating cells. Conversely, restoration of microRNA-203 using an inducible model potently inhibits proliferation of these cells. We comprehensively identify microRNA-203 targets required for Hras-initiated tumorigenesis. These targets include critical regulators of the Ras pathway and essential genes required for cell division. This study establishes a role for the loss of microRNA-203 in promoting selection and expansion of Hras mutated cells and identifies a mechanism through which microRNA-203 antagonizes Hras-mediated tumorigenesis.

DOI:http://dx.doi.org/10.7554/eLife.07004.001

DNA mutations occur and accumulate during an individual's lifetime. Often these changes are harmless. But some mutations—called driver mutations—can trigger the formation of tumors. This is often because these mutations allow the cells to grow faster than normal cells. Mutations in genes in the Ras gene family are among the most common driver mutations found in human cancers. These common mutations lead to the uncontrolled activation of genes that are normally tightly controlled, which in turn allows the cells to divide more and live for longer: these are two key features of cancer cells.

So, how are Ras genes and the genes that they control regulated to prevent such dangerous over activation? One mechanism rests on binding sites in their messenger RNA sequence that are recognized by smaller RNA molecules called microRNAs. RNA molecules are created when genes are transcribed. Some RNAs, called messenger RNAs, are then decoded to create proteins. Many other RNAs, including microRNAs, do not code for proteins, but instead bind to many messenger RNA targets, and repress their ability to be decoded into proteins. Three genes, called Hras, Kras, and Nras, are regulated in this way by numerous microRNAs, which together act to dampen the normal activities of these genes.

Riemondy et al. investigate how a cancer-promoting mutation in the Hras gene affects the activities of microRNAs in mouse skin cells in culture. By measuring RNA levels, the experiments reveal that skin cells carrying this mutation produce significantly lower levels of what is normally the most highly produced microRNA in the skin. This microRNA, called microRNA-203, acts to limit the proliferation of skin cells when these cells are dividing rapidly. When the gene encoding microRNA-203 was deleted in mice, the skin cells proliferated more. These mice also developed more skin tumors than normal mice when they were exposed to cancer-causing chemicals. When the gene for microRNA-203 was added into skin cells carrying the Hras mutation and then activated, the cells both divided less and, as a results, grew less. This indicates that microRNA-203 could prevent cancerous cells from expanding in number, a key event in the initiation of tumors.

Riemondy et al. also used a variety of approaches to identify the molecules targeted by microRNA-203 in the skin, and reveal that it targets multiple signaling pathways, including components of the Ras pathway, to suppress cell proliferation. Together, these findings highlight microRNA-203 as a potential source of new treatments to prevent or slow tumor growth in humans.

DOI:http://dx.doi.org/10.7554/eLife.07004.002

Patent highlights February–March 2015

A snapshot of noteworthy recent developments in the patent literature of relevance to pharmaceutical and medical research and development.