Retraction Note: miR-34a blocks osteoporosis and bone metastasis by inhibiting osteoclastogenesis and Tgif2.

A Retraction to this paper has been published and can be accessed via a link at the top of the paper.

Author Correction: miR-34a blocks osteoporosis and bone metastasis by inhibiting osteoclastogenesis and Tgif2.

Change history: In this Letter, the citation to 'Fig. 4e, f' in the main text should be 'Fig. 3e, f'. This has not been corrected online.

Allele-Specific Reprogramming of Cancer Metabolism by the Long Non-coding RNA CCAT2.

Altered energy metabolism is a cancer hallmark as malignant cells tailor their metabolic pathways to meet their energy requirements. Glucose and glutamine are the major nutrients that fuel cellular metabolism, and the pathways utilizing these nutrients are often altered in cancer. Here, we show that the long ncRNA CCAT2, located at the 8q24 amplicon on cancer risk-associated rs6983267 SNP, regulates cancer metabolism in vitro and in vivo in an allele-specific manner by binding the Cleavage Factor I (CFIm) complex with distinct affinities for the two subunits (CFIm25 and CFIm68). The CCAT2 interaction with the CFIm complex fine-tunes the alternative splicing of Glutaminase (GLS) by selecting the poly(A) site in intron 14 of the precursor mRNA. These findings uncover a complex, allele-specific regulatory mechanism of cancer metabolism orchestrated by the two alleles of a long ncRNA.

EphA2- and HDAC-Targeted Combination Therapy in Endometrial Cancer.

Endometrial cancer is the most frequent malignant tumor of the female reproductive tract but lacks effective therapy. EphA2, a receptor tyrosine kinase, is overexpressed by various cancers including endometrial cancer and is associated with poor clinical outcomes. In preclinical models, EphA2-targeted drugs had modest efficacy. To discover potential synergistic partners for EphA2-targeted drugs, we performed a high-throughput drug screen and identified panobinostat, a histone deacetylase inhibitor, as a candidate. We hypothesized that combination therapy with an EphA2 inhibitor and panobinostat leads to synergistic cell death. Indeed, we found that the combination enhanced DNA damage, increased apoptosis, and decreased clonogenic survival in Ishikawa and Hec1A endometrial cancer cells and significantly reduced tumor burden in mouse models of endometrial carcinoma. Upon RNA sequencing, the combination was associated with downregulation of cell survival pathways, including senescence, cyclins, and cell cycle regulators. The Axl-PI3K-Akt-mTOR pathway was also decreased by combination therapy. Together, our results highlight EphA2 and histone deacetylase as promising therapeutic targets for endometrial cancer.

Broad-acting therapeutic effects of miR-29b-chitosan on hypertension and diabetic complications.

MicroRNA miR-29 promotes endothelial function in human arterioles in part by targeting LYPLA1 and increasing nitric oxide production. In addition, miR-29 is a master inhibitor of extracellular matrix gene expression, which may attenuate fibrosis but could also weaken tissue structure. The goal of this study was to test whether miR-29 could be developed as an effective, broad-acting, and safe therapeutic. Substantial accumulation of miR-29b and effective knockdown of Lypla1 in several mouse tissues were achieved using a chitosan-packaged, chemically modified miR-29b mimic (miR-29b-CH-NP) injected systemically at 200 µg/kg body weight. miR-29b-CH-NP, injected once every 3 days, significantly attenuated angiotensin II-induced hypertension. In db/db mice, miR-29b-CH-NP treatment for 12 weeks decreased cardiac and renal fibrosis and urinary albuminuria. In uninephrectomized db/db mice, miR-29b-CH-NP treatment for 20 weeks significantly improved myocardial performance index and attenuated proteinuria. miR-29b-CH-NP did not worsen abdominal aortic aneurysm in ApoE knockout mice treated with angiotensin II. miR-29b-CH-NP caused aortic root fibrotic cap thinning in ApoE knockout mice fed a high-cholesterol and high-fat diet but did not worsen the necrotic zone or mortality. In conclusion, systemic delivery of low-dose miR-29b-CH-NP is an effective therapeutic for several forms of cardiovascular and renal disease in mice.

Combination of EphA2- and Wee1-Targeted Therapies in Endometrial Cancer.

EphA2 tyrosine kinase is upregulated in many cancers and correlated with poor survival of patients, including those with endometrial cancer. EphA2-targeted drugs have shown modest clinical benefit. To improve the therapeutic response to such drugs, we performed a high-throughput chemical screen to discover novel synergistic partners for EphA2-targeted therapeutics. Our screen identified the Wee1 kinase inhibitor, MK1775, as a synergistic partner to EphA2, and this finding was confirmed using both in vitro and in vivo experiments. We hypothesized that Wee1 inhibition would sensitize cells to EphA2-targeted therapy. Combination treatment decreased cell viability, induced apoptosis, and reduced clonogenic potential in endometrial cancer cell lines. In vivo Hec1A and Ishikawa-Luc orthotopic mouse models of endometrial cancer showed greater anti-tumor responses to combination treatment than to either monotherapy. RNASeq analysis highlighted reduced cell proliferation and defective DNA damage response pathways as potential mediators of the combination's effects. In conclusion, our preclinical findings indicate that Wee1 inhibition can enhance the response to EphA2-targeted therapeutics in endometrial cancer; this strategy thus warrants further development.

Redirecting host preexisting influenza A virus immunity for cancer immunotherapy.

We tested the concept that host preexisting influenza A virus immunity can be redirected to inhibit tumor growth and metastasis through systemic administration of influenza A virus-related peptides to targeted tumors. Mice infected with influenza A virus strain A/Puerto Rico/8/34 (PR8) were used as a model of a host with preexisting viral immunity. The extent to which preexisting influenza A immunity in PR8-immunized mice can be redirected to inhibit tumor growth and metastasis was first examined by ectopic expression of influenza A nucleoprotein (NP) and hemagglutinin (HA) in syngeneic mammary tumor cells via lentiviral transduction. Then, the feasibility of implementing this strategy using a systemic therapy approach was assessed by systemic delivery of major histocompatibility complex class I (MHC-I)-compatible peptides to targeted mammary tumors overexpressing human epidermal growth factor receptor-2 (HER2) in mice using a novel HER2-targeting single-lipid nanoparticle (SLNP). Our results show that preexisting influenza A immunity in PR8-immunized mice could be quickly redirected to syngeneic tumors expressing influenza A NP and HA, leading to strong inhibition of tumor growth and metastasis and improvement of survival compared to the findings in antigen-naïve control mice. MHC-I-compatible peptides could be delivered to targeted mammary tumors in mice using the HER2-targeting SLNP for antigen presentation, which subsequently redirected preexisting influenza A immunity to the tumors to exert antitumor activities. In conclusion, preexisting influenza A immunity can be repurposed for cancer immunotherapy through systemic delivery of influenza A-related peptides to targeted tumors. Further development of the strategy for clinical translation is warranted.

Conversion of RNA Aptamer into Modified DNA Aptamers Provides for Prolonged Stability and Enhanced Antitumor Activity.

Aptamers, synthetic single-strand oligonucleotides that are similar in function to antibodies, are promising as therapeutics because of their minimal side effects. However, the stability and bioavailability of the aptamers pose a challenge. We developed aptamers converted from RNA aptamer to modified DNA aptamers that target phospho-AXL with improved stability and bioavailability. On the basis of the comparative analysis of a library of 17 converted modified DNA aptamers, we selected aptamer candidates, GLB-G25 and GLB-A04, that exhibited the highest bioavailability, stability, and robust antitumor effect in in vitro experiments. Backbone modifications such as thiophosphate or dithiophosphate and a covalent modification of the 5'-end of the aptamer with polyethylene glycol optimized the pharmacokinetic properties, improved the stability of the aptamers in vivo by reducing nuclease hydrolysis and renal clearance, and achieved high and sustained inhibition of AXL at a very low dose. Treatment with these modified aptamers in ovarian cancer orthotopic mouse models significantly reduced tumor growth and the number of metastases. This effective silencing of the phospho-AXL target thus demonstrated that aptamer specificity and bioavailability can be improved by the chemical modification of existing aptamers for phospho-AXL. These results lay the foundation for the translation of these aptamer candidates and companion biomarkers to the clinic.

Clinical significance of homologous recombination deficiency score testing in endometrial Cancer.

BACKGROUND: Homologous recombination deficiency (HRD) score is related to chemotherapy response in some cancers, but its role in endometrial cancer in not known. We determined frequency and clinical significance of alterations in the HR pathway in endometrial cancer. METHODS: 253 endometrioid endometrial adenocarcinoma (EEA) samples from two independent cohorts (discovery and replication) were tested for HRD score using the Myriad HRD assay, microsatellite instability (MSI) and tumor mutation burden (TMB) using a next generation sequencing assay. HRD scores were also generated on endometrial cancer cell lines and in vivo response to olaparib was assessed. RESULTS: ROC curves were employed to determine optimal cutoffs of HRD in relation to survival impact in endometrial cancer and a cutoff of HRD ≥ 4 was suggested for DFS using the discovery cohort. Patients from two independent cohorts with HRD score ≥ 4 trended toward worse survival as compared to those with HRD score < 4. Both cohorts were further separated into four groups according to molecular subtypes (TMB positive; MSI positive; HRD positive; all others). When grouped by molecular subtype, there was a significant difference between groups using an HRD ≥4 cutoff in the initial (p = 0.0024) and replication (p = 0.042) cohorts. The Hec1a model (HRD score = 19) was highly sensitive to olaparib in in vitro and in vivo experiments. CONCLUSIONS: High HRD score was associated with worse DFS in our patient cohort. These findings suggest that HRD score may have clinical utility in patients with advanced or recurrent endometrial cancer.

TP53 loss creates therapeutic vulnerability in colorectal cancer.

TP53, a well-known tumour suppressor gene that encodes p53, is frequently inactivated by mutation or deletion in most human tumours. A tremendous effort has been made to restore p53 activity in cancer therapies. However, no effective p53-based therapy has been successfully translated into clinical cancer treatment owing to the complexity of p53 signalling. Here we demonstrate that genomic deletion of TP53 frequently encompasses essential neighbouring genes, rendering cancer cells with hemizygous TP53 deletion vulnerable to further suppression of such genes. POLR2A is identified as such a gene that is almost always co-deleted with TP53 in human cancers. It encodes the largest and catalytic subunit of the RNA polymerase II complex, which is specifically inhibited by α-amanitin. Our analysis of The Cancer Genome Atlas (TCGA) and Cancer Cell Line Encyclopedia (CCLE) databases reveals that POLR2A expression levels are tightly correlated with its gene copy numbers in human colorectal cancer. Suppression of POLR2A with α-amanitin or small interfering RNAs selectively inhibits the proliferation, survival and tumorigenic potential of colorectal cancer cells with hemizygous TP53 loss in a p53-independent manner. Previous clinical applications of α-amanitin have been limited owing to its liver toxicity. However, we found that α-amanitin-based antibody-drug conjugates are highly effective therapeutic agents with reduced toxicity. Here we show that low doses of α-amanitin-conjugated anti-epithelial cell adhesion molecule (EpCAM) antibody lead to complete tumour regression in mouse models of human colorectal cancer with hemizygous deletion of POLR2A. We anticipate that inhibiting POLR2A will be a new therapeutic approach for human cancers containing such common genomic alterations.

PRKAR1B-AS2 Long Noncoding RNA Promotes Tumorigenesis, Survival, and Chemoresistance via the PI3K/AKT/mTOR Pathway.

Many long noncoding RNAs have been implicated in tumorigenesis and chemoresistance; however, the underlying mechanisms are not well understood. We investigated the role of PRKAR1B-AS2 long noncoding RNA in ovarian cancer (OC) and chemoresistance and identified potential downstream molecular circuitry underlying its action. Analysis of The Cancer Genome Atlas OC dataset, in vitro experiments, proteomic analysis, and a xenograft OC mouse model were implemented. Our findings indicated that overexpression of PRKAR1B-AS2 is negatively correlated with overall survival in OC patients. Furthermore, PRKAR1B-AS2 knockdown-attenuated proliferation, migration, and invasion of OC cells and ameliorated cisplatin and alpelisib resistance in vitro. In proteomic analysis, silencing PRKAR1B-AS2 markedly inhibited protein expression of PI3K-110α and abrogated the phosphorylation of PDK1, AKT, and mTOR, with no significant effect on PTEN. The RNA immunoprecipitation detected a physical interaction between PRKAR1B-AS2 and PI3K-110α. Moreover, PRKAR1B-AS2 knockdown by systemic administration of 1,2-dioleoyl-sn-glycero-3-phosphatidylcholine nanoparticles loaded with PRKAR1B-AS2-specific small interfering RNA enhanced cisplatin sensitivity in a xenograft OC mouse model. In conclusion, PRKAR1B-AS2 promotes tumor growth and confers chemoresistance by modulating the PI3K/AKT/mTOR pathway. Thus, targeting PRKAR1B-AS2 may represent a novel therapeutic approach for the treatment of OC patients.

Therapeutic potential of FLANC, a novel primate-specific long non-coding RNA in colorectal cancer.

OBJECTIVE: To investigate the function of a novel primate-specific long non-coding RNA (lncRNA), named FLANC, based on its genomic location (co-localised with a pyknon motif), and to characterise its potential as a biomarker and therapeutic target. DESIGN: FLANC expression was analysed in 349 tumours from four cohorts and correlated to clinical data. In a series of multiple in vitro and in vivo models and molecular analyses, we characterised the fundamental biological roles of this lncRNA. We further explored the therapeutic potential of targeting FLANC in a mouse model of colorectal cancer (CRC) metastases. RESULTS: FLANC, a primate-specific lncRNA feebly expressed in normal colon cells, was significantly upregulated in cancer cells compared with normal colon samples in two independent cohorts. High levels of FLANC were associated with poor survival in two additional independent CRC patient cohorts. Both in vitro and in vivo experiments demonstrated that the modulation of FLANC expression influenced cellular growth, apoptosis, migration, angiogenesis and metastases formation ability of CRC cells. In vivo pharmacological targeting of FLANC by administration of 1,2-dioleoyl-sn-glycero-3-phosphatidylcholine nanoparticles loaded with a specific small interfering RNA, induced significant decrease in metastases, without evident tissue toxicity or pro-inflammatory effects. Mechanistically, FLANC upregulated and prolonged the half-life of phosphorylated STAT3, inducing the overexpression of VEGFA, a key regulator of angiogenesis. CONCLUSIONS: Based on our findings, we discovered, FLANC as a novel primate-specific lncRNA that is highly upregulated in CRC cells and regulates metastases formation. Targeting primate-specific transcripts such as FLANC may represent a novel and low toxic therapeutic strategy for the treatment of patients.

Long non-coding RNAs in ovarian cancer: expression profile and functional spectrum.

Long non-coding RNAs (lncRNAs), initially recognized as byproducts of the transcription process, have been proven to play crucial modulatory roles in preserving overall homoeostasis of cells and tissues. Furthermore, aberrant levels of these transcripts have been shown to contribute many diseases, including cancer. Among these, many aspects of ovarian cancer biology have been found to be regulated by lncRNAs, including cancer initiation, progression and dissemination. In this review, we summarize recent studies to highlight the various roles of lncRNAs in ovary in normal and pathological conditions, immune system, diagnosis, prognosis, and therapy. We address lncRNAs that have been extensively studied in ovarian cancer and their contribution to cellular dynamics.

miR-34a blocks osteoporosis and bone metastasis by inhibiting osteoclastogenesis and Tgif2.

Bone-resorbing osteoclasts significantly contribute to osteoporosis and bone metastases of cancer. MicroRNAs play important roles in physiology and disease, and present tremendous therapeutic potential. Nonetheless, how microRNAs regulate skeletal biology is underexplored. Here we identify miR-34a as a novel and critical suppressor of osteoclastogenesis, bone resorption and the bone metastatic niche. miR-34a is downregulated during osteoclast differentiation. Osteoclastic miR-34a-overexpressing transgenic mice exhibit lower bone resorption and higher bone mass. Conversely, miR-34a knockout and heterozygous mice exhibit elevated bone resorption and reduced bone mass. Consequently, ovariectomy-induced osteoporosis, as well as bone metastasis of breast and skin cancers, are diminished in osteoclastic miR-34a transgenic mice, and can be effectively attenuated by miR-34a nanoparticle treatment. Mechanistically, we identify transforming growth factor-ß-induced factor 2 (Tgif2) as an essential direct miR-34a target that is pro-osteoclastogenic. Tgif2 deletion reduces bone resorption and abolishes miR-34a regulation. Together, using mouse genetic, pharmacological and disease models, we reveal miR-34a as a key osteoclast suppressor and a potential therapeutic strategy to confer skeletal protection and ameliorate bone metastasis of cancers.

Blockade of CDK7 Reverses Endocrine Therapy Resistance in Breast Cancer.

Cyclin-dependent kinase (CDK)-7 inhibitors are emerging as promising drugs for the treatment of different types of cancer that show chemotherapy resistance. Evaluation of the effects of CDK7 inhibitor, THZ1, alone and combined with tamoxifen is of paramount importance. Thus, in the current work, we assessed the effects of THZ1 and/or tamoxifen in two estrogen receptor-positive (ER+) breast cancer cell lines (MCF7) and its tamoxifen resistant counterpart (LCC2) in vitro and in xenograft mouse models of breast cancer. Furthermore, we evaluated the expression of CDK7 in clinical samples from breast cancer patients. Cell viability, apoptosis, and genes involved in cell cycle regulation and tamoxifen resistance were determined. Tumor volume and weight, proliferation marker (Ki67), angiogenic marker (CD31), and apoptotic markers were assayed. Bioinformatic data indicated CDK7 expression was associated with negative prognosis, enhanced pro-oncogenic pathways, and decreased response to tamoxifen. Treatment with THZ1 enhanced tamoxifen-induced cytotoxicity, while it inhibited genes involved in tumor progression in MCF-7 and LCC2 cells. In vivo, THZ1 boosted the effect of tamoxifen on tumor weight and tumor volume, reduced Ki67 and CD31 expression, and increased apoptotic cell death. Our findings identify CDK7 as a possible therapeutic target for breast cancer whether it is sensitive or resistant to tamoxifen therapy.

RNA interference-based therapy and its delivery systems.

RNA interference (RNAi) is considered a highly specific approach for gene silencing and holds tremendous potential for treatment of various pathologic conditions such as cardiovascular diseases, viral infections, and cancer. Although gene silencing approaches such as RNAi are widely used in preclinical models, the clinical application of RNAi is challenging primarily because of the difficulty in achieving successful systemic delivery. Effective delivery systems are essential to enable the full therapeutic potential of RNAi. An ideal nanocarrier not only addresses the challenges of delivering naked siRNA/miRNA, including its chemically unstable features, extracellular and intracellular barriers, and innate immune stimulation, but also offers "smart" targeted delivery. Over the past decade, great efforts have been undertaken to develop RNAi delivery systems that overcome these obstacles. This review presents an update on current progress in the therapeutic application of RNAi with a focus on cancer therapy and strategies for optimizing delivery systems, such as lipid-based nanoparticles.

Activating p53 family member TAp63: A novel therapeutic strategy for targeting p53-altered tumors.

BACKGROUND: Over 96% of high-grade ovarian carcinomas and 50% of all cancers are characterized by alterations in the p53 gene. Therapeutic strategies to restore and/or reactivate the p53 pathway have been challenging. By contrast, p63, which shares many of the downstream targets and functions of p53, is rarely mutated in cancer. METHODS: A novel strategy is presented for circumventing alterations in p53 by inducing the tumor-suppressor isoform TAp63 (transactivation domain of tumor protein p63) through its direct downstream target, microRNA-130b (miR-130b), which is epigenetically silenced and/or downregulated in chemoresistant ovarian cancer. RESULTS: Treatment with miR-130b resulted in: 1) decreased migration/invasion in HEYA8 cells (p53 wild-type) and disruption of multicellular spheroids in OVCAR8 cells (p53-mutant) in vitro, 2) sensitization of HEYA8 and OVCAR8 cells to cisplatin (CDDP) in vitro and in vivo, and 3) transcriptional activation of TAp63 and the B-cell lymphoma (Bcl)-inhibitor B-cell lymphoma 2-like protein 11 (BIM). Overexpression of TAp63 was sufficient to decrease cell viability, suggesting that it is a critical downstream effector of miR-130b. In vivo, combined miR-130b plus CDDP exhibited greater therapeutic efficacy than miR-130b or CDDP alone. Mice that carried OVCAR8 xenograft tumors and were injected with miR-130b in 1,2-dioleoyl-sn-glycero-3-phosphatidylcholine (DOPC) liposomes had a significant decrease in tumor burden at rates similar to those observed in CDDP-treated mice, and 20% of DOPC-miR-130b plus CDDP-treated mice were living tumor free. Systemic injections of scL-miR-130b plus CDDP in a clinically tested, tumor-targeted nanocomplex (scL) improved survival in 60% and complete remissions in 40% of mice that carried HEYA8 xenografts. CONCLUSIONS: The miR-130b/TAp63 axis is proposed as a new druggable pathway that has the potential to uncover broad-spectrum therapeutic options for the majority of p53-altered cancers.

Thymoquinone inhibits cell proliferation, migration, and invasion by regulating the elongation factor 2 kinase (eEF-2K) signaling axis in triple-negative breast cancer.

BACKGROUND/PURPOSE: Triple-negative breast cancer (TNBC) is the most aggressive and chemoresistant subtype of breast cancer. Therefore, new molecular targets and treatments need to be developed to improve poor patient prognosis and survival. We have previously shown that eukaryotic elongation factor 2 kinase (eEF-2K) is highly expressed in TNBC cells, is associated with poor patient survival and prognosis, and promotes cell proliferation, migration, and invasion. In vivo targeting of eEF-2K significantly reduces the tumor growth of orthotopic TNBC xenograft mouse models, suggesting that eEF-2K may serve as a potential novel therapeutic target. METHODS/RESULTS: In the current study, we identified thymoquinone (TQ), an active ingredient of Nigella sativa, as a potential safe and effective eEF-2K inhibitor in TNBC. We demonstrated for the first time that TQ inhibits the protein and mRNA expression of eEF-2K, as well as the clinically relevant downstream targets, including Src/FAK and Akt, and induces the tumor suppressor miR-603, in response to NF-kB inhibition. This effect was associated with a significant decrease in the proliferation, colony formation, migration, and invasion of TNBC cells. Furthermore, systemic in vivo injection of TQ (20 and 100 mg/kg) significantly reduced the growth of MDA-MB-231 tumors and inhibited the eEF-2K expression in an orthotopic tumor model in mice. CONCLUSION: Our study provides first evidence that TQ treatment inhibits cell proliferation, migration/invasion, and tumor growth, in part through the inhibition of eEF-2K signaling in TNBC. Thus, our findings suggest that systemic TQ treatment may be used as a targeted therapeutic strategy for the inhibition of eEF-2K in TNBC tumor growth and progression.