Role of miR-24 in Multiple Endocrine Neoplasia Type 1: A Potential Target for Molecular Therapy.

Multiple endocrine neoplasia type 1 (MEN1) is a rare autosomal dominant inherited multiple cancer syndrome of neuroendocrine tissues. Tumors are caused by an inherited germinal heterozygote inactivating mutation of the MEN1 tumor suppressor gene, followed by a somatic loss of heterozygosity (LOH) of the MEN1 gene in target neuroendocrine cells, mainly at parathyroids, pancreas islets, and anterior pituitary. Over 1500 different germline and somatic mutations of the MEN1 gene have been identified, but the syndrome is completely missing a direct genotype-phenotype correlation, thus supporting the hypothesis that exogenous and endogenous factors, other than MEN1 specific mutation, are involved in MEN1 tumorigenesis and definition of individual clinical phenotype. Epigenetic factors, such as microRNAs (miRNAs), are strongly suspected to have a role in MEN1 tumor initiation and development. Recently, a direct autoregulatory network between miR-24, MEN1 mRNA, and menin was demonstrated in parathyroids and endocrine pancreas, showing a miR-24-induced silencing of menin expression that could have a key role in initiation of tumors in MEN1-target neuroendocrine cells. Here, we review the current knowledge on the post-transcriptional regulation of MEN1 and menin expression by miR-24, and its possible direct role in MEN1 syndrome, describing the possibility and the potential approaches to target and silence this miRNA, to permit the correct expression of the wild type menin, and thereby prevent the development of cancers in the target tissues.

The Role of microRNA Let-7d in Female Malignancies and Diseases of the Female Reproductive Tract.

microRNAs are small noncoding RNAs that regulate gene expression at the posttranscriptional level. Let-7d is a microRNA of the conserved let-7 family that is dysregulated in female malignancies including breast cancer, ovarian cancer, endometrial cancer, and cervical cancer. Moreover, a dysregulation is observed in endometriosis and pregnancy-associated diseases such as preeclampsia and fetal growth restriction. Let-7d expression is regulated by cytokines and steroids, involving transcriptional regulation by OCT4, MYC and p53, as well as posttranscriptional regulation via LIN28 and ADAR. By downregulating a wide range of relevant mRNA targets, let-7d affects cellular processes that drive disease progression such as cell proliferation, apoptosis (resistance), angiogenesis and immune cell function. In an oncological context, let-7d has a tumor-suppressive function, although some of its functions are context-dependent. Notably, its expression is associated with improved therapeutic responses to chemotherapy in breast and ovarian cancer. Studies in mouse models have furthermore revealed important roles in uterine development and function, with implications for obstetric diseases. Apart from a possible utility as a diagnostic blood-based biomarker, pharmacological modulation of let-7d emerges as a promising therapeutic concept in a variety of female disease conditions.

Stable duplex-linked antisense targeting miR-148a inhibits breast cancer cell proliferation.

MicroRNAs (miRNAs) regulate cancer cell proliferation by binding directly to the untranslated regions of messenger RNA (mRNA). MicroRNA-148a (miR-148a) is expressed at low levels in breast cancer (BC). However, little attention has been paid to the sequestration of miR-148a. Here, we performed a knockdown of miR-148a using anti-miRNA oligonucleotides (AMOs) and investigated the effect on BC cell proliferation. BC cell proliferation was significantly suppressed by AMO flanked by interstrand cross-linked duplexes (CL-AMO), whereas single-stranded and commercially available AMOs had no effect. The suppression was caused by sequestering specifically miR-148a. Indeed, miR-148b, another member of the miR-148 family, was not affected. Importantly, the downregulation of miR-148a induced a greater and longer-lasting inhibition of BC cell proliferation than the targeting of oncogenic microRNA-21 (miR-21) did. We identified thioredoxin-interacting protein (TXNIP), a tumor suppressor gene, as a target of miR-148a and showed that CL-AMO provoked an increase in TXNIP mRNA expression. This study provide evidence that lowly expressed miRNAs such as miR-148a have an oncogenic function and might be a promising target for cancer treatment.

Pharmacological Inhibition of miR-130 Family Suppresses Bladder Tumor Growth by Targeting Various Oncogenic Pathways via PTPN1.

Previously, we have revealed that the miR-130 family (miR-130b, miR-301a, and miR-301b) functions as an oncomiR in bladder cancer. The pharmacological inhibition of the miR-130 family molecules by the seed-targeting strategy with an 8-mer tiny locked nucleic acid (LNA) inhibits the growth, migration, and invasion of bladder cancer cells by repressing stress fiber formation. Here, we searched for a functionally advanced target sequence with LNA for the miR-130 family with low cytotoxicity and found LNA #9 (A(L)^i^i^A(L)^T(L)^T(L)^G(L)^5(L)^A(L)^5(L)^T(L)^G) as a candidate LNA. LNA #9 inhibited cell growth in vitro and in an in vivo orthotopic bladder cancer model. Proteome-wide tyrosine phosphorylation analysis suggested that the miR-130 family upregulates a wide range of receptor tyrosine kinases (RTKs) signaling via the expression of phosphorylated Src (pSrcTyr416). SILAC-based proteome analysis and a luciferase assay identified protein tyrosine phosphatase non-receptor type 1 (PTPN1), which is implicated as a negative regulator of multiple signaling pathways downstream of RTKs as a target gene of the miR-130 family. The miR-130-targeted LNA increased and decreased PTPN1 and pSrcTyr416 expressions, respectively. PTPN1 knockdown led to increased tumor properties (cell growth, invasion, and migration) and increased pSrcTyr416 expression in bladder cancer cells, suggesting that the miR-130 family upregulates multiple RTK signaling by targeting PTPN1 and subsequent Src activation in bladder cancer. Thus, our newly designed miR-130 family targeting LNA could be a promising nucleic acid therapeutic agent for bladder cancer.

A synthetic small molecule stalls pre-mRNA splicing by promoting an early-stage U2AF2-RNA complex.

Dysregulated pre-mRNA splicing is an emerging Achilles heel of cancers and myelodysplasias. To expand the currently limited portfolio of small-molecule drug leads, we screened for chemical modulators of the U2AF complex, which nucleates spliceosome assembly and is mutated in myelodysplasias. A hit compound specifically enhances RNA binding by a U2AF2 subunit. Remarkably, the compound inhibits splicing of representative substrates and stalls spliceosome assembly at the stage of U2AF function. Computational docking, together with structure-guided mutagenesis, indicates that the compound bridges the tandem U2AF2 RNA recognition motifs via hydrophobic and electrostatic moieties. Cells expressing a cancer-associated U2AF1 mutant are preferentially killed by treatment with the compound. Altogether, our results highlight the potential of trapping early spliceosome assembly as an effective pharmacological means to manipulate pre-mRNA splicing. By extension, we suggest that stabilizing assembly intermediates may offer a useful approach for small-molecule inhibition of macromolecular machines.

A novel circular RNA hsa_circRNA_103809/miR-377-3p/GOT1 pathway regulates cisplatin-resistance in non-small cell lung cancer (NSCLC).

BACKGROUND: Cisplatin is the first-line chemotherapeutic drug for non-small cell lung cancer (NSCLC), and emerging evidences suggests that targeting circular RNAs (circRNAs) is an effective strategy to increase cisplatin-sensitivity in NSCLC, but the detailed mechanisms are still not fully delineated. METHODS: Cell proliferation, viability and apoptosis were examined by using the cell counting kit-8 (CCK-8) assay, trypan blue staining assay and Annexin V-FITC/PI double staining assay, respectively. The expression levels of cancer associated genes were measured by using the Real-Time qPCR and Western Blot analysis at transcriptional and translated levels. Dual-luciferase reporter gene system assay was conducted to validated the targeting sites among hsa_circRNA_103809, miR-377-3p and 3' untranslated region (3'UTR) of GOT1 mRNA. The expression status, including expression levels and localization, were determined by immunohistochemistry (IHC) assay in mice tumor tissues. RESULTS: Here we identified a novel hsa_circRNA_103809/miR-377-3p/GOT1 signaling cascade which contributes to cisplatin-resistance in NSCLC in vitro and in vivo. Mechanistically, parental cisplatin-sensitive NSCLC (CS-NSCLC) cells were subjected to continuous low-dose cisplatin treatment to generate cisplatin-resistant NSCLC (CR-NSCLC) cells, and we found that hsa_circRNA_103809 and GOT1 were upregulated, while miR-377-3p was downregulated in CR-NSCLC cells but not in CS-NSCLC cells. In addition, hsa_circRNA_103809 sponged miR-337-3p to upregulate GOT1 in CS-NSCLC cells, and knock-down of hsa_circRNA_103809 enhanced the inhibiting effects of cisplatin on cell proliferation and viability, and induced cell apoptosis in CR-NSCLC cells, which were reversed by downregulating miR-377-3p and overexpressing GOT1. Consistently, overexpression of hsa_circRNA_103809 increased cisplatin-resistance in CS-NSCLC cells by regulating the miR-377-3p/GOT1 axis. Finally, silencing of hsa_circRNA_103809 aggravated the inhibiting effects of cisplatin treatment on NSCLC cell growth in vivo. CONCLUSIONS: Analysis of data suggested that targeting the hsa_circRNA_103809/miR-377-3p/GOT1 pathway increased susceptibility of CR-NSCLC cells to cisplatin, and this study provided novel targets to improve the therapeutic efficacy of cisplatin for NSCLC treatment in clinic.

Targeting TdT gene expression in Molt-4 cells by PNA-octaarginine conjugates.

Peptide nucleic acid (PNA) is an amide based structural nucleic acid mimic with potential applications in gene therapeutic drug discovery. In the present study, we evaluated and compared the effects on gene expression, cell viability and apoptosis of two antisense PNA-d-octaarginine conjugates, targeting sequences at the AUG translation start site or the 5'-UTR of the TdT (terminal deoxynucleotidyl transferase) gene, as well as a sense oligomer corresponding to the 5'-UTR-antisense, in Molt-4 cells. The protein level of TdT was determined by flow cytometry, and qPCR was used for mRNA expression analysis. Mismatch PNAs were used as control to address the sequence/target spcifity of the biological effects. The results showed that treatment with the AUG- and to slightly lesser extent with the 5'-UTR-antisense PNAs reduced the TdT mRNA as wel as the protein level, whereas only very low effect was observed for the 5'-UTR-sense PNA. A parallel effect was observed on reduced cell survival and increased rate of apoptosis. Our findings suggest that antisense PNAs can inhibit expression of the TdT gene and induce apoptosis in Molt-4 cells.

The inhibition of microRNA-326 by SP1/HDAC1 contributes to proliferation and metastasis of osteosarcoma through promoting SMO expression.

Osteosarcoma (OS) is a malignant bone cancer lacking of effective treatment target when the metastasis occurred. This study investigated the implication of MicroRNA-326 in OS proliferation and metastasis to provide the clue for the treatment of metastatic OS. This study knocked down SP1 in MG63 and 143B cells and then performed Microarray assay to find the expression of miRNAs that were influenced by SP1. MTT, EdU, wound-healing and cell invasion assays were performed to evaluated cell proliferation and invasion. OS metastasis to lung was detected in a nude mice model. ChIP assay and DAPA were applied to determine the regulatory effect of SP1 and histone deacetylase 1 (HDAC) complex on miR-326 expression. Human OS tissues showed lowly expressed miR-326 but highly expressed Sp1 and HDAC. Sp1 recruited HDAC1 to miR-326 gene promoter, which caused the histone deacetylation and subsequent transcriptional inhibition of miR-326 gene. miR-326 deficiency induced the stimulation of SMO/Hedgehog pathway and promoted the proliferation and invasion of 143B and MG63 cells as well as the growth and metastasis in nude mice. SP1/HDAC1 caused the transcriptional inhibition of miR-326 gene by promoting histone deacetylation; miR-326 deficiency conversely stimulated SMO/Hedgehog pathway that was responsible for the proliferation and metastasis of OS.

Long noncoding RNA PENG upregulates PDZK1 expression by sponging miR-15b to suppress clear cell renal cell carcinoma cell proliferation.

PDZK1 downregulation was reported to independently predict poor prognosis of clear cell renal cell carcinoma (ccRCC) patients and induce ccRCC development and progression. However, the underlying mechanism of PDZK1 downregulation remains unknown. Competing endogenous RNA (ceRNA) networks are emerging as new players in gene regulation and are associated with cancer development. ceRNAs regulate other RNA transcripts by competing for shared miRNAs. To investigate the role and mechanism of ceRNAs in PDZK1 downregulation and the development of ccRCC, we searched databases for miRNAs and lncRNAs that regulate PDZK1 expression in ccRCC tissues and assessed their effects in ccRCC. We found that miR-15b was expressed at higher levels in ccRCC tissues, and its upregulation was clinically associated with lower PDZK1 level, larger tumor size and shorter survival time of ccRCC patients. Conversely, a novel lncRNA (lncPENG) was expressed at a lower level in ccRCC tissues, and its downregulation was associated with the same effects as upregulation of miR-15b. Downregulation of miR-15b and upregulation of lncPENG resulted in a significant increase in PDZK1 level and inhibition of proliferation in vitro and in vivo. Mechanistically, lncPENG directly bound to miR-15b and effectively functioned as a sponge for miR-15b to modulate the expression of PDZK1. Thus, lncPENG may function as a ceRNA to attenuate miR-15b-dependent PDZK1 downregulation and inhibit cell proliferation, suggesting that it may be clinically valuable as a therapeutic target and a prognostic biomarker of ccRCC.

Development and Clinical Trials of Nucleic Acid Medicines for Pancreatic Cancer Treatment.

Approximately 30% of pancreatic cancer patients harbor targetable mutations. However, there has been no therapy targeting these molecules clinically. Nucleic acid medicines show high specificity and can target RNAs. Nucleic acid medicine is expected to be the next-generation treatment next to small molecules and antibodies. There are several kinds of nucleic acid drugs, including antisense oligonucleotides, small interfering RNAs, microRNAs, aptamers, decoys, and CpG oligodeoxynucleotides. In this review, we provide an update on current research of nucleic acid-based therapies. Despite the challenging obstacles, we hope that nucleic acid drugs will have a significant impact on the treatment of pancreatic cancer. The combination of genetic diagnosis using next generation sequencing and targeted therapy may provide effective precision medicine for pancreatic cancer patients.

In Vivo Inhibition of MicroRNA to Decrease Tumor Growth in Mice.

MicroRNAs (miRNAs) are important regulators of gene expression through their ability to destabilize mRNA and inhibit translation of target mRNAs. An ever-increasing number of studies have identified miRNAs as potential biomarkers for cancer diagnosis and prognosis, and also as therapeutic targets, adding an extra dimension to cancer evaluation and treatment. In the context of thyroid cancer, tumorigenesis results not only from mutations in important genes, but also from the overexpression of many miRNAs. Accordingly, the role of miRNAs in the control of thyroid gene expression is evolving as an important mechanism in cancer. Herein, we present a protocol to examine the effects of miRNA-inhibitor delivery as a therapeutic modality in thyroid cancer using human tumor xenograft and orthotopic mouse models. After engineering stable thyroid tumoral cells expressing GFP and luciferase, cells are injected into nude mice to develop tumors, which can be followed by bioluminescence. The in vivo inhibition of a miRNA can reduce tumor growth and upregulate miRNA gene targets. This method can be used to assess the importance of a determined miRNA in vivo, in addition to identifying new therapeutic targets.

miR-367 as a therapeutic target in stem-like cells from embryonal central nervous system tumors.

Aberrant expression of the pluripotency factor OCT4A in embryonal tumors of the central nervous system (CNS) is a key factor that contributes to tumor aggressiveness and correlates with poor patient survival. OCT4A overexpression has been shown to up-regulate miR-367, a microRNA (miRNA) that regulates pluripotency in embryonic stem cells and stem-like aggressive traits in cancer cells. Here, we show that (a) miR-367 is carried in microvesicles derived from embryonal CNS tumor cells expressing OCT4A; and (b) inhibition of miR-367 in these cells attenuates their aggressive traits. miR-367 silencing in OCT4A-overexpressing tumor cells significantly reduced their proliferative and invasive behavior, clonogenic activity, and tumorsphere generation capability. In vivo, targeting of miR-367 through direct injections of a specific inhibitor into the cerebrospinal fluid of Balb/C nude mice bearing OCT4A-overexpressing tumor xenografts inhibited tumor development and improved overall survival. miR-367 was also shown to target SUZ12, one of the core components of the polycomb repressive complex 2 known to be involved in epigenetic silencing of pluripotency-related genes, including POU5F1, which encodes OCT4A. Our findings reveal possible clinical applications of a cancer stemness pathway, highlighting miR-367 as a putative liquid biopsy biomarker that could be further explored to improve early diagnosis and prognosis prediction, and potentially serve as a therapeutic target in aggressive embryonal CNS tumors.

Systems biology-based investigation of cooperating microRNAs as monotherapy or adjuvant therapy in cancer.

MicroRNAs (miRNAs) are short, noncoding RNAs that regulate gene expression by suppressing mRNA translation and reducing mRNA stability. A miRNA can potentially bind many mRNAs, thereby affecting the expression of oncogenes and tumor suppressor genes as well as the activity of whole pathways. The promise of miRNA therapeutics in cancer is to harness this evolutionarily conserved mechanism for the coordinated regulation of gene expression, and thus restoring a normal cell phenotype. However, the promiscuous binding of miRNAs can provoke unwanted off-target effects, which are usually caused by high-dose single-miRNA treatments. Thus, it is desirable to develop miRNA therapeutics with increased specificity and efficacy. To achieve that, we propose the concept of miRNA cooperativity in order to exert synergistic repression on target genes, thus lowering the required total amount of miRNAs. We first review miRNA therapies in clinical application. Next, we summarize the knowledge on the molecular mechanism and biological function of miRNA cooperativity and discuss its application in cancer therapies. We then propose and discuss a systems biology approach to investigate miRNA cooperativity for the clinical setting. Altogether, we point out the potential of miRNA cooperativity to reduce off-target effects and to complement conventional, targeted, or immune-based therapies for cancer.

DUXAP10 inhibition attenuates the proliferation and metastasis of hepatocellular carcinoma cells by regulation of the Wnt/ß-catenin and PI3K/Akt signaling pathways.

The long non-coding RNA DUXAP10 has been involved in the development, progression, and metastasis in several human cancers, but its biological function and underlying mechanism in hepatocellular carcinoma (HCC) still undetermined. The present study was proposed to explore the effect of DUXAP10 on the growth and metastasis of HCC cells and the potential mechanisms involved. The results showed that DUXAP10 is dramatically elevated in HCC tumor tissues and cell lines. Knockdown of DUXAP10 by DUXAP10 si-RNA significantly inhibited the cell viability, proliferation and induce the apoptosis of HCC cell line. Meanwhile, inhibition of DUXAP10 attenuates the cell migration, invasion, and epithelial-mesenchymal transition (EMT) process. No significant change of JNK MAPK pathway was detected in DUXAP10 siRNA transfected HCC cell lines. The ß-catenin and pAkt levels were decreased in the Hep G2+DUXAP10 siRNA and SMMC7721+DUXAP10 siRNA groups, while the activation of Wnt/ß-catenin or PI3K/Akt suppressed the inhibition of DUXAP10 siRNA on cell proliferation and migration. Collectively, DUXAP10 plays a critical role in regulating HCC development, potentially by regulating EMT and cell proliferation through the PI3K/Akt and Wnt/ß-catenin signaling. Inhibition of DUXAP10 in HCC HepG2 cells could attenuate the EMT and cell proliferation and invasion. Therefore, DUXAP10 might be a promising therapy target to inhibit the growth of HCC.

Detection and Analysis of RNAs Expression Profile for Methylated Candidate Tumor Suppressor Genes in Nasopharyngeal Carcinoma.

BACKGROUND: DNA methylation, which acts as an expression regulator for multiple Tumor Suppressor Genes (TSGs), is believed to play an important role in Nasopharyngeal Carcinoma (NPC) development. METHODS: We compared the effects of 5-aza-2-deoxycytidine (decitabine, DAC) on gene expression using RNA sequencing in NPC cells. RESULTS: We analyzed Differentially Expressed Genes (DEGs) in NPC cells using DAC demethylation treatment and found that 2182 genes were significantly upregulated (≥ 2-fold change), suggesting that they may play a key role in cell growth, proliferation, development, and death. For data analysis, we used the Gene Ontology database and pathway enrichment analysis of the DEGs to discover differential patterns of DNA methylation associated with changes in gene expression. Furthermore, we evaluated 74 methylated candidate TSGs from the DEGs in NPC cells and summarized these genes in several important signaling pathways frequently disrupted by promoter methylation in NPC tumorigenesis. CONCLUSION: Our study analyzes the DEGs and identifies a set of genes whose promoter methylation in NPC cells is reversed by DAC. These genes are potential substrates of DNMT inhibitors and may serve as tumor suppressors in NPC cells.

FGF18, a prominent player in FGF signaling, promotes gastric tumorigenesis through autocrine manner and is negatively regulated by miR-590-5p.

Fibroblast growth factors (FGFs) and their receptors are significant components during fundamental cellular processes. FGF18 plays a distinctive role in modulating the activity of both tumor cells and tumor microenvironment. This study aims to comprehensively investigate the expression and functional role of FGF18 in gastric cancer (GC) and elucidate its regulatory mechanisms. The upregulation of FGF18 was detected in seven out of eleven (63.6%) GC cell lines. In primary GC samples, FGF18 was overexpressed in genomically stable and chromosomal instability subtypes of GC and its overexpression was associated with poor survival. Knocking down FGF18 inhibited tumor formation abilities, induced G1 phase cell cycle arrest and enhanced anti-cancer drug sensitivity. Expression microarray profiling revealed that silencing of FGF18 activated ATM pathway but quenched TGF-ß pathway. The key factors that altered in the related signaling were validated by western blot and immunofluorescence. Meanwhile, treating GC cells with human recombinant FGF18 or FGF18-conditioned medium accelerated tumor growth through activation of ERK-MAPK signaling. FGF18 was further confirmed to be a direct target of tumor suppressor, miR-590-5p. Their expressions showed a negative correlation in primary GC samples and more importantly, re-overexpression of FGF18 partly abolished the tumor-suppressive effect of miR-590-5p. Our study not only identified that FGF18 serves as a novel prognostic marker and a therapeutic target in GC but also enriched the knowledge of FGF-FGFR signaling during gastric tumorigenesis.

Antisense Oligonucleotide-Conjugated Nanostructure-Targeting lncRNA MALAT1 Inhibits Cancer Metastasis.

Metastasis-associated lung adenocarcinoma transcript 1 (MALAT1), a long noncoding RNA (lncRNA) located in the cell nucleus, is a critical regulator of tumor cell migration. Antisense oligonucleotides (ASOs), which can downregulate the expression level of specific RNAs, have been used in clinical for disease treatment. Herein, we constructed MALAT1-specific ASO and nucleus-targeting TAT peptide cofunctionalized Au nanoparticles, namely, ASO-Au-TAT NPs, which stabilized the fragile ASOs, enhanced nuclear internalization, and exhibited good biocompatibility. After treatment with the ASO-Au-TAT NPs, A549 lung cancer cells showed a greatly reduced MALAT1 expression level and decreased migration ability  in vitro. Moreover, the ASO-Au-TAT NPs significantly reduced metastatic tumor nodule formation in vivo. Our results demonstrate that the ASO-Au-TAT nanostructures (NSs) have great potential for treatment of cancer metastasis.

Long non-coding RNA Linc00662 promotes cell invasion and contributes to cancer stem cell-like phenotypes in lung cancer cells.

Long non-coding RNAs (lncRNAs) is essential in regulation of cancer cell and cancer stem cells (CSCs) behaviour. Linc00662 is a newly identified human lung cancer related lncRNA. In this study, we aimed to explore the function of Linc00662 in human lung cancer. The expression level of Linc00662 was analysed by quantitative real-time PCR. Cell metastasis and invasive ability were detected by transwell and scratch wound healing assays. The stemness of CSCs was shown by tumorsphere formation assay and flow cytometry. The interaction between Linc00662 and Lin28 was confirmed by RNA immunoprecipitation and RNA pulldown assay. Overexpression of Linc00662 promoted the poor prognosis of lung cancer. Cell invasion, metastasis and CSCs stemness in H1299 and A549 could be influenced by Linc00662. Linc00662 had direct interaction with Lin28, and the Linc00662 function was dependent on Lin28. We demonstrate that overexpression of Linc00662 enhances lung cancer cell metastasis and CSC stemness by interacting with Lin28 in human lung cancer, which could be utilized as a potential diagnostic and therapeutic target for lung cancer patients.

Cobomarsen, an oligonucleotide inhibitor of miR-155, co-ordinately regulates multiple survival pathways to reduce cellular proliferation and survival in cutaneous T-cell lymphoma.

miR-155, a microRNA associated with poor prognosis in lymphoma and leukaemia, has been implicated in the progression of mycosis fungoides (MF), the most common form of cutaneous T-cell lymphoma (CTCL). In this study, we developed and tested cobomarsen (MRG-106), a locked nucleic acid-modified oligonucleotide inhibitor of miR-155. In MF and human lymphotropic virus type 1 (HTLV-1+) CTCL cell lines in vitro, inhibition of miR-155 with cobomarsen de-repressed direct miR-155 targets, decreased expression of multiple gene pathways associated with cell survival, reduced survival signalling, decreased cell proliferation and activated apoptosis. We identified a set of genes that are significantly regulated by cobomarsen, including direct and downstream targets of miR-155. Using clinical biopsies from MF patients, we demonstrated that expression of these pharmacodynamic biomarkers is dysregulated in MF and associated with miR-155 expression level and MF lesion severity. Further, we demonstrated that miR-155 simultaneously regulates multiple parallel survival pathways (including JAK/STAT, MAPK/ERK and PI3K/AKT) previously associated with the pathogenesis of MF, and that these survival pathways are inhibited by cobomarsen in vitro. A first-in-human phase 1 clinical trial of cobomarsen in patients with CTCL is currently underway, in which the panel of proposed biomarkers will be leveraged to assess pharmacodynamic response to cobomarsen therapy.

Therapeutic vulnerability of multiple myeloma to MIR17PTi, a first-in-class inhibitor of pri-miR-17-92.

The microRNA (miRNA) cluster miR-17-92 is oncogenic and represents a valuable therapeutic target in c-MYC (MYC)-driven malignancies. Here, we developed novel LNA gapmeR antisense oligonucleotides (ASOs) to induce ribonuclease H-mediated degradation of MIR17HG primary transcripts and consequently prevent biogenesis of miR-17-92 miRNAs (miR-17-92s). The leading LNA ASO, MIR17PTi, impaired proliferation of several cancer cell lines (n = 48) established from both solid and hematologic tumors by on-target antisense activity, more effectively as compared with miR-17-92 inhibitors. By focusing on multiple myeloma (MM), we found that MIR17PTi triggers apoptosis via impairment of homeostatic MYC/miR-17-92 feed-forward loops (FFLs) in patient-derived MM cells and induces MYC-dependent synthetic lethality. We show that alteration of a BIM-centered FFL is instrumental for MIR17PTi to induce cytotoxicity in MM cells. MIR17PTi exerts strong in vivo antitumor activity in nonobese diabetic severe combined immunodeficient mice bearing clinically relevant models of MM, with advantageous safety and pharmacokinetic profiles in nonhuman primates. Altogether, MIR17PTi is a novel pharmacological tool to be tested in early-phase clinical trials against MM and other MYC-driven malignancies.