The proto-oncogene KRAS is targeted by miR-200c

Non-coding RNAs and exosomal non-coding RNAs in lung cancer: insights into their functions

Lung cancer is the second most common form of cancer worldwide Research points to the pivotal role of non-coding RNAs (ncRNAs) in controlling and managing the pathology by controlling essential pathways. ncRNAs have all been identified as being either up- or downregulated among individuals suffering from lung cancer thus hinting that they may play a role in either promoting or suppressing the spread of the disease. Several ncRNAs could be effective non-invasive biomarkers to diagnose or even serve as effective treatment options for those with lung cancer, and several molecules have emerged as potential targets of interest. Given that ncRNAs are contained in exosomes and are implicated in the development and progression of the malady. Herein, we have summarized the role of ncRNAs in lung cancer. Moreover, we highlight the role of exosomal ncRNAs in lung cancer.

Oncogenic K-Ras suppresses global miRNA function

K-Ras frequently acquires gain-of-function mutations (K-RasG12D being the most common) that trigger significant transcriptomic and proteomic changes to drive tumorigenesis. Nevertheless, oncogenic K-Ras-induced dysregulation of post-transcriptional regulators such as microRNAs (miRNAs) during oncogenesis is poorly understood. Here, we report that K-RasG12D promotes global suppression of miRNA activity, resulting in the upregulation of hundreds of targets. We constructed a comprehensive profile of physiological miRNA targets in mouse colonic epithelium and tumors expressing K-RasG12D using Halo-enhanced Argonaute pull-down. Combining this with parallel datasets of chromatin accessibility, transcriptome, and proteome, we uncovered that K-RasG12D suppressed the expression of Csnk1a1 and Csnk2a1, subsequently decreasing Ago2 phosphorylation at Ser825/829/832/835. Hypo-phosphorylated Ago2 increased binding to mRNAs while reducing its activity to repress miRNA targets. Our findings connect a potent regulatory mechanism of global miRNA activity to K-Ras in a pathophysiological context and provide a mechanistic link between oncogenic K-Ras and the post-transcriptional upregulation of miRNA targets.

Combating Drug Resistance by Exploiting miRNA-200c-Controlled Phase II Detoxification

Acquired drug resistance constitutes a serious obstacle to the successful therapy of cancer. In the process of therapy resistance, microRNAs can play important roles. In order to combat resistance formation and to improve the efficacy of chemotherapeutics, the mechanisms of the multifaceted hsa-miR-200c on drug resistance were elucidated. Upon knockout of hsa-miR-200c in breast carcinoma cells, a proteomic approach identified altered expression of glutathione S-transferases (GSTs) when cells were treated with the chemotherapeutic drug doxorubicin. In different hsa-miR-200c expression systems, such as knockout, inducible sponge and inducible overexpression, the differential expression of all members of the GST family was evaluated. Expression of hsa-miR-200c in cancer cells led to the repression of a multitude of these GSTs and as consequence, enhanced drug-induced tumor cell death which was evaluated for two chemotherapeutic drugs. Additionally, the influence of hsa-miR-200c on the glutathione pathway, which is part of the phase II detoxification mechanism, was investigated. Finally, the long-term effects of hsa-miR-200c on drug efficacy were studied in vitro and in vivo. Upon doxycycline induction of hsa-miR-200c, MDA-MB 231 xenograft mouse models revealed a strongly reduced tumor growth and an enhanced treatment response to doxorubicin. A combined treatment of these tumors with hsa-miR-200c and doxorubicin resulted in complete regression of the tumor in 60% of the animals. These results identify hsa-miR-200c as an important player regulating the cellular phase II detoxification, thus sensitizing cancer cells not expressing this microRNA to chemotherapeutics and reversing drug resistance through suppression of GSTs.

Discovery of genes positively modulating treatment effect using potential outcome framework and Bayesian update

BACKGROUND

The recent explosion of cancer genomics provides extensive information about mutations and gene expression changes in cancer. However, most of the identified gene mutations are not clinically utilized. It remains uncertain whether the presence of a certain genetic alteration will affect treatment response. Conventional statistics have limitations for causal inferences and are hard to gain sufficient power in genomic datasets. Here, we developed and evaluated a C-search algorithm for searching the causal genes that maximize the effect of the treatment.

METHODS

The algorithm was developed based on the potential outcome framework and Bayesian posterior update. The precision of the algorithm was validated using a simulation dataset. The algorithm was implemented to a cBioPortal dataset. The genes discovered by the algorithm were externally validated within CancerSCAN screening data from Samsung Medical Center.

RESULTS

Simulation data analysis showed that the C-search algorithm was able to identify nine causal genes out of ten. The C-search algorithm shows the discovery rate rapidly increasing until the 1500 data instances. Meanwhile, the log-rank test shows a slower increase in performance. The C-search algorithm was able to suggest nine causal genes from the cBioPortal Metabric dataset. Treating the patients with the causal genes is associated with better survival outcome in both the cBioPortal dataset and the CancerSCAN dataset which is used for external validation.

CONCLUSIONS

Our C-search algorithm demonstrated better performance to identify causal effects of the genes than multiple log-rank test analysis especially within a limited number of data. The result suggests that the C-search can discover the causal genes from various genetic datasets, where the number of samples is limited compared to the number of variables.

Efficacy of Sirna-Loaded Nanoparticles in the Treatment of k-ras Mutant Lung Cancer in vitro

AIM

To design and develop K-RAS silencing small interfering RNA (siRNA)-loaded poly (D, L-lactic-co-glycolic acid) nanoparticles and evaluate their efficacy in the treatment of K-RAS mutant lung cancer.

METHODS

The nanoparticles prepared by the double emulsion solvent evaporation method were characterized by TEM, FTIR and XPS analyzes and evaluated in vitro by XTT, PCR, ELISA, and Western-Blot. Metabolomic analyzes were performed to evaluate the changes in metabolic profiles of the cells after nanoparticles treatment.

RESULTS

The nanoparticles were obtained with a particle size less than 250 nm, a polydispersity index around 0.1, a surface charge of (-12) - (+14) mV, and 80% of the siRNA encapsulation. The nanoparticles didn't affect cell viability of the cells after 72 hours. In cancer cells, KRAS expression was decreased by up to 50%, protein levels were decreased by more than 90%.

CONCLUSION

The formulated siRNA delivery nanoparticles can be promising treatment in lung cancer.

MicroRNA-200c Attenuates the Tumor-Infiltrating Capacity of Macrophages

Simple Summary

The tumor microenvironment determines the prognosis and outcome for cancer patients. Herein, tumor-associated macrophages are not only highly abundant, but also play a crucial role in shaping a tumor-supporting microenvironment. Both their recruitment to the tumor as well as their functional polarization toward a pro-tumorigenic phenotype are mediated by tumor-derived factors including microRNAs. However, the impact of most microRNAs on the tumor cell-macrophage crosstalk remains to be elucidated. Thus, we reached out to investigate the role of hsa-miR-200c-3p (miR-200c) in tumor cell–macrophage interactions, as it was shown to be differentially expressed during cancer progression and metastasis. miR-200c was highly expressed in MCF7 breast tumor cells compared to macrophages. Furthermore, we identified a CD36-dependent uptake of miR-200c, derived from apoptotic tumor cells, into macrophages. In macrophages, elevated miR-200c levels reduced the expression of numerous migration-associated mRNAs, consequently reducing the capacity of macrophages to infiltrate into tumor spheroids. Finally, a distinct signature of miR-200c-repressed, predicted targets was identified, which strongly correlated with tumor infiltration. Targeting the miR-200c transfer from dying tumor cells to macrophages might therefore provide the opportunity to specifically modulate tumor-associated macrophage recruitment.

Abstract

Macrophages constitute a major part of the tumor-infiltrating immune cells. Within the tumor microenvironment, they acquire an alternatively activated, tumor-supporting phenotype. Factors released by tumor cells are crucial for the recruitment of tumor-associated macrophages. In the present project, we aimed to understand the role of hsa-miR-200c-3p (miR-200c) in the interplay between tumor cells and macrophages. To this end, we employed a coculture system of MCF7 breast tumor cells and primary human macrophages and observed the transfer of miR-200c from apoptotic tumor cells to macrophages, which required intact CD36 receptor in macrophages. We further comprehensively determined miR-200c targets in macrophages by mRNA-sequencing and identified numerous migration-associated mRNAs to be downregulated by miR-200c. Consequently, miR-200c attenuated macrophage infiltration into 3-dimensional tumor spheroids. miR-200c-mediated reduction in infiltration further correlated with a miR-200c migration signature comprised of the four miR-200c-repressed, predicted targets PPM1F, RAB11FIB2, RDX, and MSN.

Interplay between K-RAS and miRNAs

K-RAS is frequently mutated in cancers, and its overactivation can lead to oncogene-induced senescence (OIS), a barrier to cellular transformation. Feedback onto K-RAS limits its signaling to avoid senescence while achieving the appropriate level of activation that promotes proliferation and survival. Such regulation could be mediated by miRNAs, as aberrant RAS signaling and miRNA activity coexist in several cancers, with miRNAs acting both up- and downstream of K-RAS. Several miRNAs both regulate and are regulated by K-RAS, suggesting a noncoding RNA-based feedback mechanism. Functional interactions between K-RAS and the miRNA machinery have also begun to unfold. This review comprehensively surveys the state of knowledge connecting K-RAS to miRNA function and proposes a model for the regulation of K-RAS signaling by noncoding RNAs.

Modulation of Cellular MicroRNA by HIV-1 in Burkitt Lymphoma Cells-A Pathway to Promoting Oncogenesis

Viruses and viral components have been shown to manipulate the expression of host microRNAs (miRNAs) to their advantage, and in some cases to play essential roles in cancer pathogenesis. Burkitt lymphoma (BL), a highly aggressive B-cell derived cancer, is significantly over-represented among people infected with HIV. This study adds to accumulating evidence demonstrating that the virus plays a direct role in promoting oncogenesis. A custom miRNA PCR was used to identify 32 miRNAs that were differently expressed in Burkitt lymphoma cells exposed to HIV-1, with a majority of these being associated with oncogenic processes. Of those, hsa-miR-200c-3p, a miRNA that plays a crucial role in cancer cell migration, was found to be significantly downregulated in both the array and in single-tube validation assays. Using an in vitro transwell system we found that this downregulation correlated with significantly enhanced migration of BL cells exposed to HIV-1. Furthermore, the expression of the ZEB1 and ZEB2 transcription factors, which are promotors of tumour invasion and metastasis, and which are direct targets of hsa-miR-200c-3p, were found to be enhanced in these cells. This study therefore identifies novel miRNAs as role players in the development of HIV-associated BL, with one of these miRNAs, hsa-miR-200c-3p, being a candidate for further clinical studies as a potential biomarker for prognosis in patients with Burkitt lymphoma, who are HIV positive.

The impact of microRNAs on myeloid-derived suppressor cells in cancer

Inflammation promotes cancer development. To a large extent, this can be attributed to the recruitment of myeloid-derived suppressor cells (MDSCs) to tumors. These cells are known for establishing an immunosuppressive tumor microenvironment by suppressing T cell activities. However, MDSCs also promote metastasis and angiogenesis. Critically, as small non-coding RNAs that regulate gene expression, microRNAs (miRNAs) control MDSC activities. In this review, we discuss how miRNA networks regulate key MDSC signaling pathways, how they shape MDSC development, differentiation and activation, and how this impacts tumor development. By targeting the expression of miRNAs in MDSCs, we can alter their main signaling pathways. In turn, this can compromise their ability to promote multiple hallmarks of cancer. Therefore, this may represent a new powerful strategy for cancer immunotherapy.

MiRNA-200C expression in Fanconi anemia pathway functionally deficient lung cancers

The Fanconi Anemia (FA) pathway is essential for human cells to maintain genomic integrity following DNA damage. This pathway is involved in repairing damaged DNA through homologous recombination. Cancers with a defective FA pathway are expected to be more sensitive to cross-link based therapy or PARP inhibitors. To evaluate downstream effectors of the FA pathway, we studied the expression of 734 different micro RNAs (miRNA) using NanoString nCounter miRNA array in two FA defective lung cancer cells and matched control cells, along with two lung tumors and matched non-tumor tissue samples that were deficient in the FA pathway. Selected miRNA expression was validated with real-time PCR analysis. Among 734 different miRNAs, a cluster of microRNAs were found to be up-regulated including an important cancer related micro RNA, miR-200C. MiRNA-200C has been reported as a negative regulator of epithelial-mesenchymal transition (EMT) and inhibits cell migration and invasion by promoting the upregulation of E-cadherin through targeting ZEB1 and ZEB2 transcription factors. miRNA-200C was increased in the FA defective lung cancers as compared to controls. AmpliSeq analysis showed significant reduction in ZEB1 and ZEB2 mRNA expression. Our findings indicate the miRNA-200C potentially play a very important role in FA pathway downstream regulation.

miR-34a and miR-200c Have an Additive Tumor-Suppressive Effect on Breast Cancer Cells and Patient Prognosis

Breast cancer is the most common women's malignancy in the world and, for subgroups of patients, treatment outcomes remain poor. Thus, more effective therapeutic strategies are urgently needed. MicroRNAs (miRNAs) have emerged as promising therapeutic tools and targets, as they play significant roles in regulating key cellular processes by suppressing gene expression. However, additive opportunities involving miRNAs have been underexplored. For example, both miR-34a and miR-200c individually suppress the development of different types of cancer, but the cellular effects of their combined actions remain unknown. Here, we show that miR-34a and miR-200c levels are reduced in breast tumors compared to adjacent normal tissues and that this additively predicts poor patient survival. In addition, in cell lines, miR-34a and miR-200c additively induce apoptosis and cell cycle arrest, while also inhibiting proliferation, invasion, migration, stemness and epithelial-to-mesenchymal transition (EMT). Mechanistically, both miRNA-34a and miR-200c directly target HIF1-α and subsequently downregulate VEGFR, MMP9 and CXCR4, although combined miRNA-34a and miR-200c delivery suppresses mouse xenograft tumor development as effectively as individual delivery. We establish a model, supported by in vitro and clinical data, which collectively suggest that the co-delivery of miR-34a and miR-200c represents a promising novel therapeutic strategy for breast cancer patients.

Integrative p53, micro-RNA and Cathepsin Protease Co-Regulatory Expression Networks in Cancer

Simple Summary

This article describes an emerging area of significant interest in cancer and cell death and the relationships shared by these through the transcriptional regulation of cathepsin protease genes by micro-RNAs that are connected to p53 activation. While it has been demonstrated that the p53 protein can directly regulate some cathepsin genes and the expression of their upstream regulatory micro-RNAs, very little is known about what input the p53 isoform proteins may have in regulating this relationship. Herein, we draw attention to this important regulatory aspect in the context of describing mechanisms that are being established for the micro-RNA regulation of cathepsin protease genes and their collective use in diagnostic or prognostic assays.

Abstract

As the direct regulatory role of p53 and some of its isoform proteins are becoming established in modulating gene expression in cancer research, another aspect of this mode of gene regulation that has captured significant interest over the years is the mechanistic interplay between p53 and micro-RNA transcriptional regulation. The input of this into modulating gene expression for some of the cathepsin family members has been viewed as carrying noticeable importance based on their biological effects during normal cellular homeostasis and cancer progression. While this area is still in its infancy in relation to general cathepsin gene regulation, we review the current p53-regulated micro-RNAs that are generating significant interest through their regulation of cathepsin proteases, thereby strengthening the link between activated p53 forms and cathepsin gene regulation. Additionally, we extend our understanding of this developing relationship to how such micro-RNAs are being utilized as diagnostic or prognostic tools and highlight their future uses in conjunction with cathepsin gene expression as potential biomarkers within a clinical setting.

Nucleic Acid-Based Approaches for Tumor Therapy

Within the last decade, the introduction of checkpoint inhibitors proposed to boost the patients' anti-tumor immune response has proven the efficacy of immunotherapeutic approaches for tumor therapy. Furthermore, especially in the context of the development of biocompatible, cell type targeting nano-carriers, nucleic acid-based drugs aimed to initiate and to enhance anti-tumor responses have come of age. This review intends to provide a comprehensive overview of the current state of the therapeutic use of nucleic acids for cancer treatment on various levels, comprising (i) mRNA and DNA-based vaccines to be expressed by antigen presenting cells evoking sustained anti-tumor T cell responses, (ii) molecular adjuvants, (iii) strategies to inhibit/reprogram tumor-induced regulatory immune cells e.g., by RNA interference (RNAi), (iv) genetically tailored T cells and natural killer cells to directly recognize tumor antigens, and (v) killing of tumor cells, and reprograming of constituents of the tumor microenvironment by gene transfer and RNAi. Aside from further improvements of individual nucleic acid-based drugs, the major perspective for successful cancer therapy will be combination treatments employing conventional regimens as well as immunotherapeutics like checkpoint inhibitors and nucleic acid-based drugs, each acting on several levels to adequately counter-act tumor immune evasion.

KRAS-associated microRNAs in colorectal cancer

Colorectal cancer (CRC) is one of the leading causes of cancerrelated death worldwide. Despite progress in treatment of cancers, CRC with KRAS mutations are resistant towards anti-EGFR treatment. MicroRNAs have been discovered in an exponential manner within the last few years and have been known to exert either an onco-miRNA or tumor suppressive effect. Here, the various roles of microRNAs involved in the initiation and progression of KRAS-regulated CRC are summarized. A thorough understanding of the roles and functions of the plethora of microRNAs associated with KRAS in CRC will grant insights into the provision of other potential therapeutic targets as well as treatment. MicroRNAs may also serve as potential molecular classifier or early detection biomarkers for future treatment and diagnosis of CRC.

Particle-Size-Dependent Delivery of Antitumoral miRNA Using Targeted Mesoporous Silica Nanoparticles

Multifunctional core-shell mesoporous silica nanoparticles (MSN) were tailored in size ranging from 60 to 160 nm as delivery agents for antitumoral microRNA (miRNA). The positively charged particle core with a pore diameter of about 5 nm and a stellate pore morphology allowed for an internal, protective adsorption of the fragile miRNA cargo. A negatively charged particle surface enabled the association of a deliberately designed block copolymer with the MSN shell by charge-matching, simultaneously acting as a capping as well as endosomal release agent. Furthermore, the copolymer was functionalized with the peptide ligand GE11 targeting the epidermal growth factor receptor, EGFR. These multifunctional nanoparticles showed an enhanced uptake into EGFR-overexpressing T24 bladder cancer cells through receptor-mediated cellular internalization. A luciferase gene knock-down of up to 65% and additional antitumoral effects such as a decreased cell migration as well as changes in cell cycle were observed. We demonstrate that nanoparticles with a diameter of 160 nm show the fastest cellular internalization after a very short incubation time of 45 min and produce the highest level of gene knock-down.

MiR-200b Inhibits Tumor Growth and Chemoresistance via Targeting p70S6K1 in Lung Cancer

Downregulation of microRNA-200b (miR-200b) has been identified in a range of cancers, yet the specific mechanisms whereby it influences lung cancer growth require further exploration. We determined that lung cancer patient tumor samples exhibit decreased miR-200b expression, and we further found this miRNA to inhibit tumor growth via interfering with ERK1/2 and AKT signaling, targeting p70S6K1 to suppress HIF-1α expression. This miRNA further rendered H1299 cells more sensitive to cisplatin while impairing their proliferative and invasive potential through its ability to target and inhibit the activity of p70S6K1. These results were further confirmed in a murine xenograft model in which miR-200b also inhibited the growth of tumor and suppressed p70S6K1, p-AKT, p-ERK1/2, and HIF-1α expression. These findings clearly demonstrate a role for miR-200b in suppressing lung cancer development, making it a potentially relevant target for future diagnostic and therapeutic interventions.

Exosomal miR-200c suppresses chemoresistance of docetaxel in tongue squamous cell carcinoma by suppressing TUBB3 and PPP2R1B

BACKGROUND

Chemoresistance is the main challenge for treating tongue squamous cell carcinoma (TSCC). MiR-200c is an important regulator of chemoresistance. Exosomes are a promising molecule-delivery system for cancer treatment. Thus, this study aimed to investigate the role of miR-200c in chemoresistance of TSCC and whether exosomes could effectively deliver miR-200c to chemo-resistant cells and regulate cellular activities.

RESULTS

The results showed that the downregulation of miR-200c increased resistance to DTX, migration, and invasion and decreased apoptosis, which was reversed by the overexpression of miR-200c. The NTECs-derived exosomes transported miR-200c to HSC-3DR, increasing the sensitivity to DTX in vitro and in vivo. Also, epithelial-to-mesenchymal transition (EMT) and DNA damage responses were involved in DTX resistance. Furthermore, miR-200c regulated DTX resistance by targeting TUBB3 and PPP2R1B.

CONCLUSION

Exosome-mediated miR-200c delivery may be an effective and promising strategy to treat chemoresistance in TSCC.

METHODS

Docetaxel (DTX) resistant HSC-3 cells (HSC-3DR) were transfected with miR-200c lentivirus and cocultured with exosomes derived from normal tongue epithelial cells (NTECs) that were overexpressed with miR-200c. The roles of miR-200c and exosomal miR-200c in vitro and in vivo were determined by RNA-Seq, qRT-PCR, western blots, transmission electron microscopy, and flow cytometry, fluorescence, CCK8, Transwell, and wound healing assays.

Effects of MIR143 on rat sarcoma signaling networks in solid tumors: A brief overview

Rat sarcoma (RAS) is a well-known oncogene that plays important roles in cancer proliferation, cell survival and cell invasion. RAS exists as three major isoforms, Kirsten rat sarcoma (KRAS), Harvey rat sarcoma (HRAS) and neuroblastoma rat sarcoma (NRAS). Mutations of these genes account for approximately 30% of all cancers. Among them, KRAS mutations are the most common, responsible for 85%, followed by NRAS (12%) and HRAS (3%). Although the development of RAS inhibitors has been explored for over the past decade, so far, no effective inhibitor has been found. MicroRNA (miRNA) are a class of small non-coding RNA that control the gene expression of pleural target genes at the post-transcriptional level. MiRNA play critical roles in the physiological and pathological processes at work in cancers, such as cell proliferation, cell death, cell invasion and metastasis. MicroRNA-143 (MIR143) is known to function as a tumor suppressor in a variety of cancers. One of its known mechanisms is suppression of RAS expression and its effector signaling pathways, such as PI3K/AKT and MAPK/ERK. Within the last five years, we developed a potent chemically modified MIR143-3p that enabled us to elucidate the details of the KRAS signaling networks at play in colon and other cancer cells. In this review, we will discuss the role of MIR143-3p in those RAS signaling networks that are related to various biological processes of cancer cells. In addition, we will discuss the possibility of the use of MIR143 as a therapeutic drug for targeting RAS signaling networks.

NO1, a New Sigma 2 Receptor/TMEM97 Fluorescent Ligand, Downregulates SOCE and Promotes Apoptosis in the Triple Negative Breast Cancer Cell Lines

(1) Background: The structure of the Sigma 2 receptor/TMEM97 (σ2RTMEM97) has recently been reported. (2, 3) Methods and results: We used genetic and biochemical approaches to identify the molecular mechanism downstream of σ2R/TMEM97. The novel σ2R/TMEM97 fluorescent ligand, NO1, reduced the proliferation and survival of the triple negative breast cancer cell lines (TNBC: MDA-MB-231 and MDA-MB-468 cell lines), due to NO1-induced apoptosis. Greater bioaccumulation and faster uptake of NO1 in MDA-MB-231 cells compared to MCF10A or MCF7 cell lines were also shown. Accordingly, elevated σ2R/TMEM97 expression was confirmed by Western blotting. In contrast to NO1, other σ2R/TMEM97 ligands, such as SM21 and PB28, enhanced MDA-MB-231 cell proliferation and migration. Store-operated calcium entry (SOCE) is crucial for different cancer hallmarks. Here, we show that NO1, but not other σ2R/TMEM97 ligands, reduced SOCE in MDA-MB-231 cells. Similarly, TMEM97 silencing in MDA-MB-231 cells also impaired SOCE. NO1 administration downregulated STIM1-Orai1 interaction, probably by impairing the positive regulatory effect of σ2R/TMEM97 on STIM1, as we were unable to detect interaction with Orai1. (4) Conclusion: σ2R/TMEM97 is a key protein for the survival of triple negative breast cancer cells by promoting SOCE; therefore, NO1 may become a good pharmacological tool to avoid their proliferation.

Inducible microRNA-200c decreases motility of breast cancer cells and reduces filamin A

Cancer progression and metastases are frequently related to changes of cell motility. Amongst others, the microRNA-200c (miR-200c) was shown to maintain the epithelial state of cells and to hamper migration. Here, we describe two miR-200c inducible breast cancer cell lines, derived from miR-200c knock-out MCF7 cells as well as from the miR-200c-negative MDA-MB-231 cells and report on the emerging phenotypic effects after miR-200s induction. The induction of miR-200c expression seems to effect a rapid reduction of cell motility, as determined by 1D microlane migration assays. Sustained expression of miR200c leads to a changed morphology and reveals a novel mechanism by which miR-200c interferes with cytoskeletal components. We find that filamin A expression is attenuated by miRNA-200c induced downregulation of the transcription factors c-Jun and MRTF/SRF. This potentially novel pathway that is independent of the prominent ZEB axis could lead to a broader understanding of the role that miR200c plays in cancer metastasis.

MicroRNAs in breast cancer: Roles, functions, and mechanism of actions

Breast cancer is one of the most lethal malignancies in women in the world. Various factors are involved in the development and promotion of the malignancy; most of them involve changes in the expression of certain genes, such as microRNAs (miRNAs). MiRNAs can regulate signaling pathways negatively or positively, thereby affecting tumorigenesis and various aspects of cancer progression, particularly breast cancer. Besides, accumulating data demonstrated that miRNAs are a novel tool for prognosis and diagnosis of breast cancer patients. Herein, we will review the roles of these RNA molecules in several important signaling pathways, such as transforming growth factor, Wnt, Notch, nuclear factor-κ B, phosphoinositide-3-kinase/Akt, and extracellular-signal-regulated kinase/mitogen activated protein kinase signaling pathways in breast cancer.

The microRNA-200 family acts as an oncogene in colorectal cancer by inhibiting the tumor suppressor RASSF2

This study aimed to determine whether manipulation of the microRNA-200 (miR-200) family could influence colon adenocarcinoma cell behavior. The miR-200 family has a significant role in tumor suppression and functions as an oncogene. In vitro studies on gain and loss of function with small interfering RNA demonstrated that the miR-200 family could regulate RASSF2 expression. Knockdown of the miR-200 family in the HT-29 colon cancer cell line increased KRAS expression but decreased signaling in the MAPK/ERK signaling pathway through reduced ERK phosphorylation. Increased expression of the miR-200 family in the CCD-841 colon epithelium cell line increased KRAS expression and led to increased signaling in the MAPK/ERK signaling pathway but increased ERK phosphorylation. Functionally, knockdown of the miR-200 family led to decreased cell proliferation in the HT-29 cells; therefore, increased miR-200 family expression could increase cell proliferation in the CCD-841 cell line. The present study included a large paired miR array dataset (n=632), in which the miR-200 family was significantly found to be increased in colon cancer when compared with normal adjacent colon epithelium. In a miR-seq dataset (n=199), the study found that miR-200 family expression was increased in localized colon cancer compared with metastatic disease. Decreased expression was associated with poorer overall survival. The miR-200 family directly targeted RASSF2 and was inversely correlated with RASSF2 expression (n=199, all P<0.001). Despite the well-defined role of the miR-200 family in tumor suppression, the present findings demonstrated a novel function of the miR-200 family in tumor proliferation.

Micromanaging aerobic respiration and glycolysis in cancer cells

BACKGROUND

Cancer cells possess a common metabolic phenotype, rewiring their metabolic pathways from mitochondrial oxidative phosphorylation to aerobic glycolysis and anabolic circuits, to support the energetic and biosynthetic requirements of continuous proliferation and migration. While, over the past decade, molecular and cellular studies have clearly highlighted the association of oncogenes and tumor suppressors with cancer-associated glycolysis, more recent attention has focused on the role of microRNAs (miRNAs) in mediating this metabolic shift. Accumulating studies have connected aberrant expression of miRNAs with direct and indirect regulation of aerobic glycolysis and associated pathways.

SCOPE OF REVIEW

This review discusses the underlying mechanisms of metabolic reprogramming in cancer cells and provides arguments that the earlier paradigm of cancer glycolysis needs to be updated to a broader concept, which involves interconnecting biological pathways that include miRNA-mediated regulation of metabolism. For these reasons and in light of recent knowledge, we illustrate the relationships between metabolic pathways in cancer cells. We further summarize our current understanding of the interplay between miRNAs and these metabolic pathways. This review aims to highlight important metabolism-associated molecular components in the hunt for selective preventive and therapeutic treatments.

MAJOR CONCLUSIONS

Metabolism in cancer cells is influenced by driver mutations but is also regulated by posttranscriptional gene silencing. Understanding the nuanced regulation of gene expression in these cells and distinguishing rapid cellular responses from chronic adaptive mechanisms provides a basis for rational drug design and novel therapeutic strategies.

The Roles of MicroRNA in Lung Cancer

Lung cancer is the most devastating malignancy in the world. Beyond genetic research, epigenomic studies—especially investigations of microRNAs—have grown rapidly in quantity and quality in the past decade. This has enriched our understanding about basic cancer biology and lit up the opportunities for potential therapeutic development. In this review, we summarize the involvement of microRNAs in lung cancer carcinogenesis and behavior, by illustrating the relationship to each cancer hallmark capability, and in addition, we briefly describe the clinical applications of microRNAs in lung cancer diagnosis and prognosis. Finally, we discuss the potential therapeutic use of microRNAs in lung cancer.

The Modulatory Role of MicroRNA-873 in the Progression of KRAS-Driven Cancers

KRAS is one of the most frequently mutated proto-oncogenes in pancreatic ductal adenocarcinoma (PDAC) and aberrantly activated in triple-negative breast cancer (TNBC). A profound role of microRNAs (miRNAs) in the pathogenesis of human cancer is being uncovered, including in cancer therapy. Using in silico prediction algorithms, we identified miR-873 as a potential regulator of KRAS, and we investigated its role in PDAC and TNBC. We found that reduced miR-873 expression is associated with shorter patient survival in both cancers. miR-873 expression is significantly repressed in PDAC and TNBC cell lines and inversely correlated with KRAS levels. We demonstrate that miR-873 directly bound to the 3′ UTR of KRAS mRNA and suppressed its expression. Notably, restoring miR-873 expression induced apoptosis; recapitulated the effects of KRAS inhibition on cell proliferation, colony formation, and invasion; and suppressed the activity of ERK and PI3K/AKT, while overexpression of KRAS rescued the effects mediated by miR-873. Moreover, in vivo delivery of miR-873 nanoparticles inhibited KRAS expression and tumor growth in PDAC and TNBC tumor models. In conclusion, we provide the first evidence that miR-873 acts as a tumor suppressor by targeting KRAS and that miR-873-based gene therapy may be a therapeutic strategy in PDAC and TNBC.

A Conditional Dependency on MELK for the Proliferation of Triple-Negative Breast Cancer Cells

The role of maternal and embryonic leucine zipper kinase (MELK) in cancer cell proliferation has been contentious, with recent studies arriving at disparate conclusions. We investigated the in vitro dependency of cancer cells on MELK under a range of assay conditions. Abrogation of MELK expression has little effect under common culture conditions, in which cells are seeded at high densities and reach confluence in 3–5 days. However, MELK dependency becomes clearly apparent in clonogenic growth assays using either RNAi or CRISPR technologies to modulate MELK expression. This dependency is in sharp contrast to that of essential genes, such as those encoding classic mitotic kinases, but is similar to that of other oncogenes including MYC and KRAS. Our study provides an example demonstrating some of the challenges encountered in cancer target validation, and reveals how subtle, but important, technical variations can ultimately lead to divergent outcomes and conclusions.

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Inhibiting MELK expression compromises clonogenic growth of cancer cells

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MELK depletion minimally affects non-clonogenic cell growth

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MELK depletion by RNAi or CRISPR has similar effects on cell growth

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Cancer cell dependency on MELK is similar to that on classic oncogenes

MiRNA-27a sensitizes breast cancer cells to treatment with Selective Estrogen Receptor Modulators

BACKGROUND

MicroRNA-27a (miR-27a) is a small non-coding RNA, shown to play a role in multiple cancers, including the regulation of ERα expression in breast cancer. Most ERα positive tumors are treated with Selective Estrogen Receptor Modulators (SERMs) and thus the role of miR-27a expression in response to SERM treatment is of interest.

METHODS

Tamoxifen resistant cells were generated by molecular evolution with six cycles of tamoxifen treatment. MCF7 and T47D luminal A breast cancer cell lines were either treated with miR-27a mimics, or ER-signaling was modulated ectopically. The changes were analyzed with RT-qPCR, western blotting and transcriptional activity ERE-reporter assays. Moreover, the response to SERM treatments (tamoxifen, endoxifen and toremifen) was investigated by cell viability and apoptosis measurements. An in silico analysis of survival data from the METABRIC study was performed in order to assess the prognostic value of miR-27a for response to SERM treatment.

RESULTS

Tamoxifen-resistant cells showed decreased expression of ERα and miR-27a. The overexpression of miR-27a increased the levels of ERα, while modulation of ERα decreased miR-27a expression. High miR-27a expression increased the sensitivity of MCF7 and T47D cells to SERM treatments and re-sensitized the cells to tamoxifen. Patient survival of luminal A breast cancer patients that underwent endocrine therapies was better in groups with high miR-27a expression.

CONCLUSION

MiR-27a sensitizes luminal A breast cancer cells to SERM treatments based on a positive feedback loop with ERα. An increased overall-survival of ER-positive breast cancer patients that underwent endocrine treatments and displayed high miR-27a levels was found.

The effect of combined treatment with sodium phenylbutyrate and cisplatin, erlotinib, or gefitinib on resistant NSCLC cells

Background

Chemotherapy resistance is the main cause of the marginal clinical benefit of platinum-based chemotherapy and tyrosine kinase inhibitors in advanced non-small-cell lung cancer (NSCLC). Thus, the identification of new therapeutic agents that can enhance the sensitivity of these drugs is of clinical importance. Histone deacetylase inhibitors (HDACIs) are emerging as new promising agents with strong antiproliferative effects against different types of cancers. This study investigates the synergistic potential of sodium phenylbutyrate (NaPB) added on top of standard chemotherapy used against NSCLC.

Objective

The objective of this study was to evaluate the ability of NaPB to overcome the resistance of NSCLC cell lines to cisplatin, gefitinib, and erlotinib.

Methods

MTT cell proliferation assay was used to measure the anticancer effects of cisplatin, erlotinib, or gefitinib alone or combined with various concentrations of NaPB against A549, Calu1, and H1650 NSCLC cell lines. Synergism was estimated by measuring synergy value (R), which is equal to the ratio of IC₅₀ of each primary drug alone divided by combination IC₅₀s. Student’s t-test analysis was used to evaluate the potential differences between IC₅₀ values. ANOVA followed by Tukey’s post hoc was used to evaluate the potential differences among monotherapy and combination treatment groups. Analyses were performed using R 3.3.2 software. P-value <0.05 was considered to be statistically significant.

Results

NaPB was shown to inhibit the growth of A549, Calu1, and H1650 cell lines in a dose-dependent manner (IC₅₀ 10, 8.53, and 4.53 mM, respectively). Furthermore, the addition of NaPB along with cisplatin, erlotinib, or gefitinib to A549, Calu1, and H1650 cell lines resulted in a synergistic antiproliferative effect against the three NSCLC cell lines (R>1.6, P-value <0.05), thus suggesting that NaPB can potentiate the effect of cisplatin, erlotinib, and gefitinib on A549, Calu1, and H1650 cell lines.

Conclusion

Current results suggest a potential role of NaPB as a sensitizing agent in NSCLC.

Phosphodiesterase 7B/microRNA-200c relationship regulates triple-negative breast cancer cell growth

Members of microRNA-200 (miRNA-200) family play a regulatory role in epithelial to mesenchymal transition (EMT) by suppressing Zeb1 and Zeb2 expression. Consistent with its role in suppressing EMT, Hsa-miR-200c-3p (miR-200c), a member of miR-200 family is poorly expressed in mesenchymal-like triple negative breast cancer (TNBC) cells and ectopic miR-200c expression suppresses cell migration. In this manuscript, we demonstrated that miR-200c potently inhibited TNBC cell growth and tumor development in a mechanism distinct from its ability to downregulate Zeb1 and Zeb2 expression because silencing them only marginally affected TNBC cell growth. We identified phosphodiesterase 7B (PDE7B) as a bona fide miR-200c target. Importantly, miR-200c-led inhibition in cell growth and tumor development was prevented by forcing PDE7B transgene expression while knockdown of PDE7B effectively inhibited cell growth. These results suggest that miR-200c inhibits cell growth by targeting PDE7B mRNA. To elucidate mechanism underlying miR-200c/PDE7B regulation of TNBC cell growth, we showed that cAMP concentration was lower in TNBC cells compared to estrogen receptor-positive (ER+) cells and that both miR-200c and PDE7B siRNAs were able to increase cAMP concentration in TNBC cells. High level of cellular cAMP has been shown to induce cell cycle arrest and apoptosis in TNBC cells. Our observation that ectopic expression of miR-200c triggered apoptosis indicates that it does so by elevating level of cellular cAMP. Analysis of breast tumor gene expression datasets revealed an inverse association between miR-200c and PDE7B expression. Especially, both low miR-200c and high PDE7B expression were correlated with poor survival of breast cancer patients. Our study supports a critical role of miR-200c/PDE7B relationship in TNBC tumorigenesis.

A proteomic analysis of an in vitro knock-out of miR-200c

Loss of miR-200c is correlated to advanced cancer-subtypes due to increased EMT and decreased treatment efficacy by chemotherapeutics. As miRNAs regulate a multitude of targets, the analysis of differentially expressed proteins upon a genomic knock-out (KO) is of interest. In this study, we generated a TALENs KO of miR-200c in MCF7 breast cancer cells, excluded its compensation by family-members and evaluated the impact on the proteome by analyzing three individual KO-clones. We identified 26 key proteins and a variety of enrichments in metabolic and cytoskeletal pathways. In six of these targets (AGR2, FLNA/B, ALDH7A1, SCIN, GSTM3) the differential expression was additionally detected at mRNA level. Together, these alterations in protein abundance accounted for the observed biological phenotypes, i.e. increased migration and chemoresistance and altered metabolism, found in the miR-200c-KO clones. These findings provide novel insights into miR-200c and pave the way for further studies.

Expression of miR-200c and its clinicopathological significance in patients with colorectal cancer

MicroRNA-200c (miR-200c) is known to play a pivotal role in the regulation of epithelial-to-mesenchymal and mesenchymal-to-epithelial transition processes. However, the biological function of miR-200c in human carcinogenesis remains controversial. We examined the association of miR-200c expression with various clinicopathological factors, including KRAS mutation status and survival, in patients with colorectal cancer (CRC). The expression level of miR-200c was evaluated in 109 paired CRC and normal tissue samples using quantitative reverse transcription polymerase chain reaction. The KRAS mutation status of the CRC samples was determined using the PNAClamp™ KRAS Mutation Detection kit. Compared with the normal tissue group, miR-200c expression was significantly upregulated in the CRCs (P < .001). The expression of miR-200c was increased in CRCs with higher grade (P = .009), advanced stage (P = .042), and lymphovascular invasion (P = .003). Thirty-one CRCs (28.4%) had KRAS mutations in codon 12 or 13. CRCs with KRAS mutations had significantly higher miR-200c expression than CRCs with wild-type KRAS (P = .003). In survival analysis, high miR-200c expression was correlated with worse overall survival (P = .017) and recurrence-free survival (P = .048). Our results indicate that miR-200c is involved in tumor progression and aggressiveness in CRCs, and this oncogenic role of miR-200c may be triggered by activation of the KRAS signaling pathway.

Epigenetics and MicroRNAs in Cancer

The ability to reprogram the transcriptional circuitry by remodeling the three-dimensional structure of the genome is exploited by cancer cells to promote tumorigenesis. This reprogramming occurs because of hereditable chromatin chemical modifications and the consequent formation of RNA-protein-DNA complexes that represent the principal actors of the epigenetic phenomena. In this regard, the deregulation of a transcribed non-coding RNA may be both cause and consequence of a cancer-related epigenetic alteration. This review summarizes recent findings that implicate microRNAs in the aberrant epigenetic regulation of cancer cells.

RAS-MAPK pathway epigenetic activation in cancer: miRNAs in action

The highly conserved RAS-mitogen activated protein kinase (MAPK) signaling pathway is involved in a wide range of cellular processes including differentiation, proliferation, and survival. Somatic mutations in genes encoding RAS-MAPK components frequently occur in many tumors, making the RAS-MAPK a critical pathway in human cancer. Since the pioneering study reporting that let-7 miRNA acted as tumor suppressor by repressing the RAS oncogene, growing evidence has suggested the importance of miRNAs targeting the RAS-MAPK in oncogenesis. MiRNAs alterations in human cancers may act as a rheostat of the oncogenic RAS signal that is often amplified as cancers progress. However, specific mechanisms leading to miRNAs deregulation and their functional consequences in cancer are far from being fully elucidated. In this review, we provide an experimental-validated map of RAS-MAPK oncomiRs and tumor suppressor miRNAs from transmembrane receptor to downstream ERK proteins. MiRNAs could be further considered as potential genetic biomarkers for diagnosis, prognosis, or therapeutic purpose.

New Insight into microRNA Functions in Cancer: Oncogene-microRNA-Tumor Suppressor Gene Network

Tumorigenesis is a multi-step and complex process with multi-factors involved. Deregulated oncogenes and tumor suppressor genes (TSGs) induced by genetic and epigenetic factors are considered as the driving force in the development and progression of cancer. Besides, microRNAs (miRNAs) act vital roles in tumorigenesis through regulating some oncogenes and TSGs. Interestingly, miRNAs are also regulated by oncogenes and TSGs. Considering the entangled regulation, here we propose a new insight into these regulation relationships in cancer: oncogene–miRNA–TSG network, which further emphasizes roles of miRNA, as well as highlights the network regulation among oncogene, miRNA, and TSG during tumorigenesis. The oncogene–miRNA–TSG network demonstrates that oncogenes and TSGs not only show functional synergy, but also there are regulatory relationships among oncogenes and TSGs during tumorigenesis, which could be mediated by miRNAs. In view of the oncogene–miRNA–TSG network involved in many oncogenes, miRNAs, and TSGs, as well as occurring in various tumor types, the anomaly of this network may be a common event in cancers and participates in tumorigenesis. This hypothesis broadens horizons of molecular mechanisms underlying tumorigenesis, and may provide a new promising venue for the prediction, diagnosis, and even therapy of cancer.

Monitoring integrity and localization of modified single-stranded RNA oligonucleotides using ultrasensitive fluorescence methods

Short single-stranded oligonucleotides represent a class of promising therapeutics with diverse application areas. Antisense oligonucleotides, for example, can interfere with various processes involved in mRNA processing through complementary base pairing. Also RNA interference can be regulated by antagomirs, single-stranded siRNA and single-stranded microRNA mimics. The increased susceptibility to nucleolytic degradation of unpaired RNAs can be counteracted by chemical modification of the sugar phosphate backbone. In order to understand the dynamics of such single-stranded RNAs, we investigated their fate after exposure to cellular environment by several fluorescence spectroscopy techniques. First, we elucidated the degradation of four differently modified, dual-dye labeled short RNA oligonucleotides in HeLa cell extracts by fluorescence correlation spectroscopy, fluorescence cross-correlation spectroscopy and Förster resonance energy transfer. We observed that the integrity of the oligonucleotide sequence correlates with the extent of chemical modifications. Furthermore, the data showed that nucleolytic degradation can only be distinguished from unspecific effects like aggregation, association with cellular proteins, or intramolecular dynamics when considering multiple measurement and analysis approaches. We also investigated the localization and integrity of the four modified oligonucleotides in cultured HeLa cells using fluorescence lifetime imaging microscopy. No intracellular accumulation could be observed for unmodified oligonucleotides, while completely stabilized oligonucleotides showed strong accumulation within HeLa cells with no changes in fluorescence lifetime over 24 h. The integrity and accumulation of partly modified oligonucleotides was in accordance with their extent of modification. In highly fluorescent cells, the oligonucleotides were transported to the nucleus. The lifetime of the RNA in the cells could be explained by a balance between release of the oligonucleotides from endosomes, degradation by RNases and subsequent depletion from the cells.

EGF receptor targeted lipo-oligocation polyplexes for antitumoral siRNA and miRNA delivery

Antitumoral siRNA and miRNA delivery was demonstrated by epidermal growth factor receptor (EGFR) targeted oligoaminoamide polyplexes. For this purpose, the T-shaped lipo-oligomer 454 was used to complex RNA into a core polyplex, which was subsequently functionalized with the targeting peptide ligand GE11 via a polyethylene glycol (PEG) linker. To this end, free cysteines on the surface of 454 polyplex were coupled with a maleimide-PEG-GE11 reagent (Mal-GE11). Resulting particles with sizes of 120-150 nm showed receptor-mediated uptake into EGFR-positive T24 bladder cancer cells, MDA-MB 231 breast cancer cells and Huh7 liver cancer cells. Furthermore, these formulations led to ligand-dependent gene silencing. RNA interference (RNAi) triggered antitumoral effects were observed for two different therapeutic RNAs, a miRNA-200c mimic or EG5 siRNA. Using polyplexes modified with a ratio of 0.8 molar equivalents of Mal-GE11, treatment of T24 or MDA-MB 231 cancer cells with miR-200c led to the expected decreased proliferation and migration, changes in cell cycle and enhanced sensitivity towards doxorubicin. Delivery of EG5 siRNA into Huh7 cells resulted in antitumoral activity with G2/M arrest, triggered by loss of mitotic spindle separation and formation of mono-astral spindles. These findings demonstrate the potential of GE11 ligand-containing RNAi polyplexes for cancer treatment.

Potential relevance of microRNAs in inter-species epigenetic communication, and implications for disease pathogenesis

MicroRNAs are short non-protein coding RNA molecules involved in the epigenetic regulation of gene expression. Recently, extracellular microRNAs have been described in body fluids that might enable epigenetic communication between distant tissues. Being highly conserved molecules, exogenous xeno-microRNAs from different species could affect gene expression in the host even in a cross-kingdom fashion. Several data underline the relevance of microRNA-mediated communication between virus and host, and there are some experimental data showing that plant- or animal-derived dietary microRNAs might have gene expression modulating activity in humans. Milk-derived microRNAs might be involved in the "epigenetic priming" of the baby. Exogenous microRNAs might be hypothesized to be implicated in disease pathogenesis, e.g. in tumors. Major questions remain to be addressed including the amount of xeno-microRNAs needed for biological action or routes for microRNA delivery. In this brief review, experimental data and hypotheses on the potential pathogenic inter-species relevance of microRNA are presented.

Roles of TP53 in determining therapeutic sensitivity, growth, cellular senescence, invasion and metastasis

TP53 is a critical tumor suppressor gene that regulates cell cycle progression, apoptosis, cellular senescence and many other properties critical for control of normal cellular growth and death. Due to the pleiotropic effects that TP53 has on gene expression and cellular physiology, mutations at this tumor suppressor gene result in diverse physiological effects. T53 mutations are frequently detected in numerous cancers. The expression of TP53 can be induced by various agents used to treat cancer patients such as chemotherapeutic drugs and ionizing radiation. Radiation will induce Ataxia telangiectasia mutated (ATM) and other kinases that results in the phosphorylation and activation of TP53. TP53 is also negatively regulated by other mechanisms, such as ubiquitination by ligases such as MDM2. While TP53 has been documented to control the expression of many "classical" genes (e.g., p21^Cip-1, PUMA, Bax) by transcriptional mechanisms for quite some time, more recently TP53 has been shown to regulate microRNA (miR) gene expression. Different miRs can promote oncogenesis (oncomiR) whereas others act to inhibit tumor progression (tumor suppressor miRs). Targeted therapies to stabilize TP53 have been developed by various approaches, MDM2/MDM4 inhibitors have been developed to stabilize TP53 in TP53-wild type (WT) tumors. In addition, small molecules have been isolated that will reactivate certain mutant TP53s. Both of these types of inhibitors are in clinical trials. Understanding the actions of TP53 may yield novel approaches to suppress cancer, aging and other health problems.

miR-200c inhibits breast cancer proliferation by targeting KRAS

The microRNA, miR-200c, is involved in the tumorigenesis and progression of a variety of cancers. The purpose of this study was to investigate the expression, mechanism and prognostic roles of miR-200c in breast cancer. We found that miR-200c was downregulated in both breast cancer tissue and cell lines using quantitative real-time PCR (qRT-PCR). In situ hybridization (ISH) and microarrays showed that low miR-200c expression was associated with poor patient overall survival (OS) and disease free survival (DFS). We used luciferase reporter plasmids to find that miR-200c inhibited the AKT and ERK pathways by directly targeting KRAS. Repression of KRAS by miR-200c suppressed the proliferation and survival of breast cancer cells in vitro and in vivo. miR-200c also had an anti-tumor effect by negatively regulating KRAS in a xenograft mouse model. Our findings provide clues regarding the role of miR-200c as a tumor suppressor in breast cancer through the inhibition of KRAS translation both in vitro and in vivo. miR-200c could be a potential therapeutic target in breast cancer.

Ehrlichia chaffeensis TRP32 is a Nucleomodulin that Directly Regulates Expression of Host Genes Governing Differentiation and Proliferation

Ehrlichia chaffeensis is an obligately intracellular bacterium that reprograms the mononuclear phagocyte through diverse effector-host interactions to modulate numerous host cell processes, including transcription. In a previous study, we reported that E. chaffeensis TRP32, a type 1 secreted effector, interacts with multiple host nucleus-associated proteins and also auto-activates reporter gene expression in yeast. In this study, we demonstrate that TRP32 is a nucleomodulin that binds host DNA and alters host gene transcription. TRP32 enters the host cell nucleus via a noncanonical translocation mechanism that involves phosphorylation of Y179 located in a C-terminal tri-tyrosine motif. Both genistein and mutation of Y179 inhibited TRP32 nuclear entry. An electromobility shift assay (EMSA) demonstrated TRP32 host DNA binding via its tandem repeat domain. TRP32 DNA binding and motif preference were further confirmed by supershift assays, as well as competition and mutant probe analyses. Using ChIP-Seq, we determined that TRP32 binds a G-rich motif primarily within ±500 bp of the gene transcription start site. An ontology analysis identified genes involved in processes such as immune cell differentiation, chromatin remodeling, and RNA transcription and processing, as primary TRP32 targets. TRP32 bound genes (n=1223) were distributed on all chromosomes and included several global regulators of proliferation and inflammation such as FOS and JUN, AKT3 and NRAS, and non-coding RNA genes, miRNA 21 and miRNA 142. TRP32 target genes were differentially regulated during infection, the majority of which were repressed, and direct repression/activation of these genes by TRP32 was confirmed in vitro with a cellular luciferase reporter assay.

Electroneutral composite polymersomes self-assembled by amphiphilic polyphosphazenes for effective miR-200c in vivo delivery to inhibit drug resistant lung cancer

MiR-200c has been confirmed to display remarkable effects on proliferation inhibition and apoptosis induction of certain cancer cells, but the main challenge for its successful translation into the clinic remains its effective delivery to the action site in vivo. In this study, a novel composite polyphosphazene vesicle system composed of amphiphilic [NP(PEG)0.3(EAB)1.7]n (PEEP) and weakly cationic [NP(PEG)0.5(DPA)1.5]n (PEDP) was prepared via a very simple dialysis method. The loading of miR-200c was accomplished with high efficiency by taking advantage of the combination effect of physical encapsulation and electrostatic interaction between vectors and miR-200c. The resultant miR-200c-loaded PEEP-PEDP polymersome (Nano-ED-200c) displayed suitable particle size, electric neutrality, excellent Ribonuclease stability and hemocompatibility. We also evaluated its subsequent miR-200c function in paclitaxel resistance human lung cancer (A549/T) cells in culture and tumor xenografts in nude mice. The results showed that Nano-ED-200c could achieve a higher miR-200c level and the enhanced antitumor efficacy with 68% tumor inhibition ratio at a very low dose of 1.0 mg/kg than PEEP nanoparticle, PEDP nanoparticle, even than Lipo2000. All these evidences indicated that this miR-200c delivery via polyphosphazene vesicles could act as a potential new therapeutic option for paclitaxel resistant human lung cancer.

Milk miRNAs: simple nutrients or systemic functional regulators?

Milk is rich in miRNAs that appear to play important roles in the postnatal development of all mammals. Currently, two competing hypotheses exist: the functional hypothesis, which proposes that milk miRNAs are transferred to the offspring and exert physiological regulatory functions, and the nutritional hypothesis, which suggests that these molecules do not reach the systemic circulation of the milk recipient, but merely provide nutrition without conferring active regulatory signals to the offspring. The functional hypothesis is based on indirect evidence and requires further investigation. The nutritional hypothesis is primarily based on three mouse models, which are inherently problematic: 1) miRNA-375 KO mice, 2) miRNA-200c/141 KO mice, and 3) transgenic mice presenting high levels of miRNA-30b in milk. This article presents circumstantial evidence that these mouse models may all be inappropriate to study the physiological traffic of milk miRNAs to the newborn mammal, and calls for new studies using more relevant mouse models or human milk to address the fate and role of milk miRNAs in the offspring and the adult consumer of cow's milk.

miR-200c: a versatile watchdog in cancer progression, EMT, and drug resistance

MicroRNAs (miRNAs) are 20-22-nucleotide small endogenous non-coding RNAs which regulate gene expression at post-transcriptional level. In the last two decades, identification of almost 2600 miRNAs in human and their potential to be modulated opened a new avenue to target almost all hallmarks of cancer. miRNAs have been classified as tumor suppressors or oncogenes depending on the phenotype they induce, the targets they modulate, and the tissue where they function. miR-200c, an illustrious tumor suppressor, is one of the highly studied miRNAs in terms of development, stemness, proliferation, epithelial-mesenchymal transition (EMT), therapy resistance, and metastasis. In this review, we first focus on the regulation of miR-200c expression and its role in regulating EMT in a ZEB1/E-cadherin axis-dependent and ZEB1/E-cadherin axis-independent manner. We then describe the role of miR-200c in therapy resistance in terms of multidrug resistance, chemoresistance, targeted therapy resistance, and radiotherapy resistance in various cancer types. We highlight the importance of miR-200c at the intersection of EMT and chemoresistance. Furthermore, we show how miR-200c coordinates several important signaling cascades such as TGF-β signaling, PI3K/Akt signaling, Notch signaling, VEGF signaling, and NF-κB signaling. Finally, we discuss miR-200c as a potential prognostic/diagnostic biomarker in several diseases, but mainly focusing on cancer and its potential application in future therapeutics.

Knockdown of lncRNA-ATB suppresses autocrine secretion of TGF-β2 by targeting ZNF217 via miR-200c in keloid fibroblasts

Abnormally high activation of transforming growth factor-β (TGF-β) signaling has been demonstrated to be involved in the initiation and progression of keloids. However, the functional role of long non-coding RNA (lncRNA)-activated by TGF-β (lncRNA-ATB) in keloids has not been documented. Here we investigated the role of lncRNA-ATB in the autocrine secretion of TGF-β in keloid fibroblasts (KFs) and explored the underlying molecular mechanism. Using immunohistochemistry and quantitative RT-PCR analysis, we showed that lncRNA-ATB and ZNF217, a transcriptional activator of TGF-β, were overexpressed and miR-200c, which targets ZNF217, was under-expressed in keloid tissue and keloid fibroblasts. Through gain- and loss-of-function studies, we demonstrated that knockdown of lncRNA-ATB decreased autocrine secretion of TGF-β2 and ZNF217 expression but upregulated expression of miR-200c in KFs. Stable downregulation of ZNF217 expression decreased the autocrine secretion of TGF-β2. miR-200c was endogenously associated with lncRNA-ATB, and inhibition of miR-200c overcame the decrease in ZNF217 expression in KFs. Taken together, these findings indicate that lncRNA-ATB governs the autocrine secretion of TGF-β2 in KFs, at least in part, by downregulating the expression level of ZNF217 via miR-200c, suggesting a signaling axis consisting of lncRNA-ATB/miR-200c/ZNF217/TGF-β2. These findings may provide potential biomarkers and targets for novel diagnostic and therapeutic approaches for keloids.

Mutations in PIK3CA sensitize breast cancer cells to physiologic levels of aspirin

A review of the literature finds that women diagnosed with breast cancer, who were on an aspirin regimen, experienced a decreased risk of distant metastases and death. Several recent studies have reported an improvement in overall survival in colorectal cancer patients who harbored mutations in the oncogene PIK3CA and received a daily aspirin regimen. Breast cancer patients on a daily aspirin regimen experienced decreased risk of distant metastases and death. PIK3CA is the most frequently mutated oncogene in breast cancer, occurring in up to 45 % of all breast cancers. In order to determine if mutations in PIK3CA sensitized breast cancers to aspirin treatment, we employed the use of isogenic cellular clones of the non-tumorigenic, breast epithelial cell line MCF-10A that harbored mutations in either PIK3CA or KRAS or both. We report that mutations in both PIK3CA and KRAS are required for the greatest aspirin sensitivity in breast cancer, and that the GSK3β protein was hyperphosphorylated in aspirin-treated double knockin cells, but not in other clones/treatments. A more modest effect was observed with single mutant PIK3CA, but not KRAS alone. These observations were further confirmed in a panel of breast cancer cell lines. Our findings provide the first evidence that mutations in PIK3CA sensitize breast cancer cells to aspirin.

microRNA-449a functions as a tumor suppressor in neuroblastoma through inducing cell differentiation and cell cycle arrest

microRNA-449a (miR-449a) has been identified to function as a tumor suppressor in several types of cancers. However, the role of miR-449a in neuroblastoma has not been intensively investigated. We recently found that the overexpression of miR-449a significantly induces neuroblastoma cell differentiation, suggesting its potential tumor suppressor function in neuroblastoma. In this study, we further investigated the mechanisms underlying the tumor suppressive function of miR-449a in neuroblastoma. We observed that miR-449a inhibits neuroblastoma cell survival and growth through 2 mechanisms--inducing cell differentiation and cell cycle arrest. Our comprehensive investigations on the dissection of the target genes of miR-449a revealed that 3 novel targets- MFAP4, PKP4 and TSEN15 -play important roles in mediating its differentiation-inducing function. In addition, we further found that its function in inducing cell cycle arrest involves down-regulating its direct targets CDK6 and LEF1. To determine the clinical significance of the miR-449a-mediated tumor suppressive mechanism, we examined the correlation between the expression of these 5 target genes in neuroblastoma tumor specimens and the survival of neuroblastoma patients. Remarkably, we noted that high tumor expression levels of all the 3 miR-449a target genes involved in regulating cell differentiation, but not the target genes involved in regulating cell cycle, are significantly correlated with poor survival of neuroblastoma patients. These results suggest the critical role of the differentiation-inducing function of miR-449a in determining neuroblastoma progression. Overall, our study provides the first comprehensive characterization of the tumor-suppressive function of miR-449a in neuroblastoma, and reveals the potential clinical significance of the miR-449a-mediated tumor suppressive pathway in neuroblastoma prognosis.

By downregulating Ku80, hsa-miR-526b suppresses non-small cell lung cancer

Ku80 is involved in DNA double-strand breaks (DSBs) repair. Ku80 is overexpressed in lung cancer tissues, yet, molecular mechanisms have not been examined. We identified that miRNA, hsa-miR-526b, is bound to the 3′-UTR of Ku80 mRNA, thus decreasing Ku80 expression in NSCLC cells. Hsa-miR-526b was downregulated in NSCLC tissues compared with corresponding non-tumorous tissues, and its expression was inversely correlated with Ku80 upregulation. Overexpression of Ku80 and downregulation of hsa-miR-526b were associated with poor clinical outcomes of NSCLC patients. Hsa-miR-526b suppressed NSCLC cell proliferation, clonogenicity, and induced cell cycle arrest and apoptosis. Hsa-miR-526b inhibited xenografts and orthotopic lung tumor growth. Further, Ku80 knockdown in NSCLC cells suppressed tumor properties in vitro and in vivo similar to hsa-miR-526b overexpression. In agreement, Ku80 restoration partially reversed cell cycle arrest and apoptosis induced by hsa-miR-526b in NSCLC cells in vitro and in vivo. In addition, hsa-miR-526b overexpression or Ku80 knockdown increased p53 and p21^CIP1/WAF1 expression. These findings reveal that hsa-miR-526b is a potential target in cancer therapy.

Hsa-miR-1 suppresses breast cancer development by down-regulating K-ras and long non-coding RNA MALAT1

MicroRNAs exert their functions by mainly regulating coding genes or long non-coding RNA expression. In the present study, we reported that hsa-miR-1 was down-regulated in breast cancer tissues. Restoration of miR-1 in breast cancer cells inhibited proliferation, motility and increased apoptosis in vitro. MiR-1 functioned as a tumor suppressor by targeting K-RAS and MALAT1. In addition, the effects of up-regulation of miR-1 were similar to that of silencing K-RAS and MALAT1 in breast cancer cells. In vivo study indicated that restoration of miR-1 inhibited tumor growth and metastasis. Patients with low miR-1 expression had poorer overall survival time than those with high miR-1 expression. Our findings emphasized the potential role of miR-1 as tumor suppressive miRNA in breast cancer.

Roles of EGFR and KRAS and their downstream signaling pathways in pancreatic cancer and pancreatic cancer stem cells

Pancreatic cancer is currently the fourth most common cancer, is increasing in incidence and soon will be the second leading cause of cancer death in the USA. This is a deadly malignancy with an incidence that approximates the mortality with 44,000 new cases and 36,000 deaths each year. Surgery, although only modestly successful, is the only curative option. However, due the locally aggressive nature and early metastasis, surgery can be performed on less than 20% of patients. Cytotoxic chemotherapy is palliative, has significant toxicity and improves survival very little. Thus new treatment paradigms are needed desperately. Due to the extremely high frequency of KRAS gene mutations (>90%) detected in pancreatic cancer patients, the roles of the epidermal growth factor receptor (EGFR), Ras/Raf/MEK/ERK and PI3K/PTEN/Akt/mTORC1/GSK-3 pathways have been investigated in pancreatic cancer for many years. Constitutively active Ras can activate both of these pathways and there is cross talk between Ras and EGFR which is believed to be important in driving metastasis. Mutant KRAS may also drive the expression of GSK-3 through Raf/MEK/ERK-mediated effects on GSK-3 transcription. GSK-3 can then regulate the expression of NF-kappaB which is important in modulating pancreatic cancer chemoresistance. While the receptors and many downstream signaling molecules have been identified and characterized, there is still much to learn about these pathways and how their deregulation can lead to cancer. Multiple inhibitors to EGFR, PI3K, mTOR, GSK-3, Raf, MEK and hedgehog (HH) have been developed and are being evaluated in various cancers. Current research often focuses on the role of these pathways in cancer stem cells (CSC), with the goal to identify sites where therapeutic resistance may develop. Relatively novel fields of investigation such as microRNAs and drugs used for other diseases e.g., diabetes, (metformin) and malaria (chloroquine) have provided new information about therapeutic resistance and CSCs. This review will focus on recent advances in the field and how they affect pancreatic cancer research and treatment.

Identification of a ternary protein-complex as a therapeutic target for K-Ras-dependent colon cancer

A cancer phenotype is driven by several proteins and targeting a cluster of functionally interdependent molecules should be more effective for therapeutic intervention. This is specifically important for Ras-dependent cancer, as mutated (MT) Ras is non-druggable and targeting its interaction with effectors may be essential for therapeutic intervention. Here, we report that a protein-complex activated by the Ras effector p38γ MAPK is a novel therapeutic target for K-Ras-dependent colon cancer. Unbiased proteomic screening and immune-precipitation analyses identified p38γ interaction with heat shock protein 90 (Hsp90) and K-Ras in K-Ras MT, but not wild-type (WT), colon cancer cells, indicating a role of this complex in Ras-dependent growth. Further experiments showed that this complex requires p38γ and Hsp90 activity to maintain MT, but not WT, K-Ras protein expression. Additional studies demonstrated that this complex is activated by p38γ-induced Hsp90 phosphorylation at S595, which is important for MT K-Ras stability and for K-Ras dependent growth. Of most important, pharmacologically inhibition of Hsp90 or p38γ activity disrupts the complex, decreases K-Ras expression, and selectively inhibits the growth of K-Ras MT colon cancer in vitro and in vivo. These results demonstrated that the p38γ-activated ternary complex is a novel therapeutic target for K-Ras-dependent colon cancer.