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.

MicroRNAome genome: a treasure for cancer diagnosis and therapy.

The interplay between abnormalities in genes coding for proteins and noncoding microRNAs (miRNAs) has been among the most exciting yet unexpected discoveries in oncology over the last decade. The complexity of this network has redefined cancer research as miRNAs, produced from what was once considered "genomic trash," have shown to be crucial for cancer initiation, progression, and dissemination. Naturally occurring miRNAs are very short transcripts that never produce a protein or amino acid chain, but act by regulating protein expression during cellular processes such as growth, development, and differentiation at the transcriptional, posttranscriptional, and/or translational level. In this review article, miRNAs are presented as ubiquitous players involved in all cancer hallmarks. The authors also describe the most used methods to detect their expression, which have revealed the identity of hundreds of miRNAs dysregulated in cancer cells or tumor microenvironment cells. Furthermore, the role of miRNAs as hormones and as reliable cancer biomarkers and predictors of treatment response is discussed. Along with this, the authors explore current strategies in designing miRNA-targeting therapeutics, as well as the associated challenges that research envisions to overcome. Finally, a new wave in molecular oncology translational research is introduced: the study of long noncoding RNAs.

Design of a miRNA sponge for the miR-17 miRNA family as a therapeutic strategy against vulvar carcinoma.

Dysregulation of microRNAs has been studied thoroughly, and has been observed in a variety of tumors including vulvar carcinomas, a rare type of gynecological tumor with increasing incidence. However, very few therapeutic alternatives have reached the clinical setting, and there is an urgent unmet need to develop novel strategies for patients with this tumor type. Thus, a microRNA (miRNA) sponge for the miR-17 miRNA family was designed, synthesized and validated in vitro in order to explore a new therapeutic strategy based on inhibiting this oncogenic miRNA family in vulvar cancer. Members of the miR-17 family were evaluated for expression in a vulvar tumor cell line (SW954) and 20 HPV negative formalin-fixed paraffin-embedded (FFPE) samples by quantitative real-time PCR (qRT-PCR). Six in tandem, bulged sequences that were complementary to these miRNAs were designed, synthesized, cloned, and transfected into SW954 cells. A luciferase reporter assay with a psiCheck2 vector was used to test the specificity of the sponge sequences for miR-17 family miRNA binding. Taqman qRT-PCR was used to test how the sponges affected miRNA expression. In FFPE samples, higher expression of miR-20a and miR-106a correlated with deeper tumor invasion (P = 0.0187 and P = 0.0404, respectively). The luciferase reporter assay validated the specificity of the sponge for miR-17 family members. Using qRT-PCR, we confirmed this specificity with decreased expression in 5 (out of six) miRNAs of the miR-17 family in SW954 cells. Although our results are preliminary, these results demonstrate that these miRNA sponges are potent inhibitors of the miR-17 family of miRNAs in SW954. Therefore, this miRNA-specific sponge may be developed into a novel therapeutic treatment for patients with vulvar cancer.

Regulation of hnRNPA1 by microRNAs controls the miR-18a-K-RAS axis in chemotherapy-resistant ovarian cancer.

The regulation of microRNA (miRNA) biogenesis, function and degradation involves a range of mechanisms, including interactions with RNA-binding proteins. The potential contribution of regulatory miRNAs to the expression of these RNA interactor proteins that could control other miRNAs expression is still unclear. Here we demonstrate a regulatory circuit involving oncogenic and tumor-suppressor miRNAs and an RNA-binding protein in a chemotherapy-resistant ovarian cancer model. We identified and characterized miR-15a-5p and miR-25-3p as negative regulators of hnRNPA1 expression, which is required for the processing of miR-18a-3p, an inhibitor of the K-RAS oncogene. The inhibition of miR-25-3p and miR-15a-5p decreased the proliferation, motility, invasiveness and angiogenic potential and increased apoptosis when combined with docetaxel. Alteration of this regulatory circuit causes poor overall survival outcome in ovarian cancer patients. These results highlight miR-15a-5p and miR-25-3p as key regulators of miR-18a-3p expression and its downstream target K-RAS, through direct modulation of hnRNPA1 expression. Our results demonstrate the therapeutic potential of inhibiting miR-25-3p and miR-15a-5p and the use of miR-18a-3p/KRAS ratio as a prominent outcome prognostic factor.

MiR-223-5p works as an oncomiR in vulvar carcinoma by TP63 suppression.

MiR-223-5p has been previously mentioned to be associated with tumor metastasis in HPV negative vulvar carcinomas, such as in several other tumor types. In the present study, we hypothesized that this microRNA would be important in vulvar cancer carcinogenesis and progression. To investigate this, we artificially mimicked miR-223-5p expression in a cell line derived from lymph node metastasis of vulvar carcinoma (SW962) and performed in vitro assays. As results, lower cell proliferation (p < 0.01) and migration (p < 0.001) were observed when miR-223-5p was overexpressed. In contrast, increased invasive potential of these cells was verified (p < 0.004). In silico search indicated that miR-223-5p targets TP63, member of the TP53 family of proteins, largely described with importance in vulvar cancer. We experimentally demonstrated that this microRNA is capable to decrease levels of p63 at both mRNA and protein levels (p < 0.001, and p < 0.0001; respectively). Also, a significant inverse correlation was observed between miR-223-5p and p63 expressions in tumors from patients (p = 0.0365). Furthermore, low p63 protein expression was correlated with deeper tumor invasion (p = 0.0491) and lower patient overall survival (p = 0.0494). Our study points out miR-223-5p overexpression as a putative pathological mechanism of tumor invasion and a promising therapeutic target and highlights the importance of both miR-223-5p and p63 as prognostic factors in vulvar cancer. Also, it is plausible that the evaluation of p63 expression in vulvar cancer at the biopsy level may bring important contribution on prognostic establishment and in elaborating better surgical approaches for vulvar cancer patients.

Small molecule compounds targeting miRNAs for cancer therapy.

One of the most fascinating discoveries in molecular oncology has been that cancer represents a disease in which genetic alterations in protein-coding, but also in non-coding genes complement each other. MicroRNAs (miRNAs) are a type of non-coding RNA (ncRNA) transcripts that can regulate gene expression primarily by disrupting messenger RNA (mRNA) translation and/or stability, or alternatively by modulating the transcription of target mRNAs. For the last decade, miRNAs have shown to be pivotal characters of every single one of the cancer hallmarks. Profiling studies have proven the significance of identifying over-expressed miRNAs (oncomiRs) causative of the activation of oncogenic pathways that lead to malignancy. Due to their crucial role in cancer, it has become a challenge to develop efficient miRNA-inhibiting strategies such as antagomiRs, locked nucleic acids or antisense oligonucleotides. However, to this date, the accessible delivery agents and their pharmacokinetic/pharmacodynamic properties are not ideal. Thus there is an urgent, unmet need to develop miRNA-based inhibitory therapeutics. Herein we present a novel therapeutic strategy that is only at the tip of the iceberg: the use of small molecule inhibitors to target specific miRNAs (SMIRs). Furthermore we describe several high-throughput techniques to screen for SMIRs both in vitro and in silico. Finally we take you through the journey that has led to discovering the handful of SMIRs that have been validated to this date.

Phytochemicals modulate carcinogenic signaling pathways in breast and hormone-related cancers.

Over the years, nutrition and environmental factors have been demonstrated to influence human health, specifically cancer. Owing to the fact that cancer is a leading cause of death worldwide, efforts are being made to elucidate molecular mechanisms that trigger or delay carcinogenesis. Phytochemicals, in particular, have been shown to modulate oncogenic processes through their antioxidant and anti-inflammatory activities and their ability to mimic the chemical structure and activity of hormones. These compounds can act not only by influencing oncogenic proteins, but also by modulating noncoding RNAs such as microRNAs and long noncoding RNAs. Although we are only beginning to understand the complete effects of many natural compounds, such as phytochemicals, researchers are motivated to combine these agents with traditional, chemo-based, or hormone-based therapies to fight against cancer. Since ongoing studies continue to prove effective, herein we exalt the importance of improving dietary choices as a chemo-preventive strategy.

Rac1/Pak1/p38/MMP-2 Axis Regulates Angiogenesis in Ovarian Cancer.

PURPOSE: Zoledronic acid is being increasingly recognized for its antitumor properties, but the underlying functions are not well understood. In this study, we hypothesized that zoledronic acid inhibits ovarian cancer angiogenesis preventing Rac1 activation. EXPERIMENTAL DESIGN: The biologic effects of zoledronic acid were examined using a series of in vitro [cell invasion, cytokine production, Rac1 activation, reverse-phase protein array, and in vivo (orthotopic mouse models)] experiments. RESULTS: There was significant inhibition of ovarian cancer (HeyA8-MDR and OVCAR-5) cell invasion as well as reduced production of proangiogenic cytokines in response to zoledronic acid treatment. Furthermore, zoledronic acid inactivated Rac1 and decreased the levels of Pak1/p38/matrix metalloproteinase-2 in ovarian cancer cells. In vivo, zoledronic acid reduced tumor growth, angiogenesis, and cell proliferation and inactivated Rac1 in both HeyA8-MDR and OVCAR-5 models. These in vivo antitumor effects were enhanced in both models when zoledronic acid was combined with nab-paclitaxel. CONCLUSIONS: Zoledronic acid has robust antitumor and antiangiogenic activity and merits further clinical development as ovarian cancer treatment.

The ZNF304-integrin axis protects against anoikis in cancer.

Ovarian cancer (OC) is a highly metastatic disease, but no effective strategies to target this process are currently available. Here, an integrative computational analysis of the Cancer Genome Atlas OC data set and experimental validation identifies a zinc finger transcription factor ZNF304 associated with OC metastasis. High tumoral ZNF304 expression is associated with poor overall survival in OC patients. Through reverse phase protein array analysis, we demonstrate that ZNF304 promotes multiple proto-oncogenic pathways important for cell survival, migration and invasion. ZNF304 transcriptionally regulates ß1 integrin, which subsequently regulates Src/focal adhesion kinase and paxillin and prevents anoikis. In vivo delivery of ZNF304 siRNA by a dual assembly nanoparticle leads to sustained gene silencing for 14 days, increased anoikis and reduced tumour growth in orthotopic mouse models of OC. Taken together, ZNF304 is a transcriptional regulator of ß1 integrin, promotes cancer cell survival and protects against anoikis in OC.

MicroRNA and Epigenetics: Diagnostic and Therapeutic Opportunities.

MicroRNAs (miRNAs) are a large family of post-transcriptional regulators of gene expression that control cellular and developmental processes by targeting messenger RNAs (mRNA). These small non-coding RNAs (ncRNAs) are aberrantly expressed in cancer, and are known to contribute to tumorigenesis and disease progression. Therapeutic strategies based on modulating miRNAs activity are emerging due to the ability of these ncRNAs to influence cellular behavior. MiRNA levels predict disease prognosis and overall patient survival, and reconstituting their basal levels has been proven to inhibit tumor growth and metastasis. Different delivery mechanisms have been tested in vivo, however many challenges need to be overcome before their utilization in the clinic. Moreover, it has been found that circulating miRNAs in body fluids have the potential to reshape cancer diagnosis and prognosis by functioning as biomarkers and indicators of progression and metastasis. These miRNAs as biofluids-based biomarkers provide an alternative strategy for early diagnosis and treatment of cancer patients.