Here, we present a unifying hypothesis about how messenger RNAs, transcribed pseudogenes, and long noncoding RNAs “talk” to each other using microRNA response elements (MREs) as letters of a new ...language. We propose that this “competing endogenous RNA” (ceRNA) activity forms a large-scale regulatory network across the transcriptome, greatly expanding the functional genetic information in the human genome and playing important roles in pathological conditions, such as cancer.
Recent reports have described an intricate interplay among diverse RNA species, including protein-coding messenger RNAs and non-coding RNAs such as long non-coding RNAs, pseudogenes and circular ...RNAs. These RNA transcripts act as competing endogenous RNAs (ceRNAs) or natural microRNA sponges - they communicate with and co-regulate each other by competing for binding to shared microRNAs, a family of small non-coding RNAs that are important post-transcriptional regulators of gene expression. Understanding this novel RNA crosstalk will lead to significant insight into gene regulatory networks and have implications in human development and disease.
The activity of RNA is controlled by different types of post-transcriptional modifications, such as the addition of methyl groups and other chemical and structural changes, that have been recently ...described in human cells by high-throughput sequencing. Herein, we will discuss how the so-called epitranscriptome is disrupted in cancer and what the contribution of its writers, readers, and erasers to the process of cellular transformation is, particularly focusing on the epigenetic modifications of ncRNAs.
Chemical modifications of RNA play a central role in the control of messenger and ncRNA activity and, thus, are tightly regulated in cells. In this review, we provide insight into how these marks are altered in cancer cells and how this knowledge can be translated to the clinical setting.
The cancer transcriptome is characterized by aberrant expression of both protein-coding and noncoding transcripts. Similar to mRNAs, a significant portion of the noncoding transcriptome, including ...long noncoding RNAs and pseudogenes, harbors microRNA (miRNA)-response elements (MRE). The recent discovery of competitive endogenous RNAs (ceRNA), natural decoys that compete for a common pool of miRNAs, provides a framework to systematically functionalize MRE-harboring noncoding RNAs and integrate them with the protein-coding RNA dimension in complex ceRNA networks. Functional interactions in ceRNA networks aid in coordinating a number of biologic processes and, when perturbed, contribute to disease pathogenesis. In this review, we discuss recent discoveries that implicate natural miRNA decoys in the development of cancer.
Cross-talk between ceRNAs through shared miRNAs represents a novel layer of gene regulation that plays important roles in the physiology and development of diseases such as cancer. As cross-talk can be predicted on the basis of the overlap of miRNA-binding sites, we are now one step closer to a complete functionalization of the human transcriptome, especially the noncoding space.
The PTEN⁻PI3K Axis in Cancer Papa, Antonella; Pandolfi, Pier Paolo
Biomolecules (Basel, Switzerland),
04/2019, Letnik:
9, Številka:
4
Journal Article
Recenzirano
Odprti dostop
The PI3K-AKT-mTOR signal transduction pathway regulates a variety of biological processes including cell growth, cell cycle progression and proliferation, cellular metabolism, and cytoskeleton ...reorganization. Fine-tuning of the phosphatidylinositol 3-kinase (PI3K) pathway signaling output is essential for the maintenance of tissue homeostasis and uncontrolled activation of this cascade leads to a number of human pathologies including cancer. Inactivation of the tumor suppressor phosphatase and tensin homologue deleted on Chromosome 10 (PTEN) and/or activating mutations in the proto-typical lipid kinase PI3K have emerged as some of the most frequent events associated with human cancer and as a result the PI3K pathway has become a highly sought-after target for cancer therapies. In this review we summarize the essential role of the PTEN-PI3K axis in controlling cellular behaviors by modulating activation of key proto-oncogenic molecular nodes and functional targets. Further, we highlight important functional redundancies and peculiarities of these two critical enzymes that over the last few decades have become a central part of the cancer research field and have instructed hundreds of pre-clinical and clinical trials to better cancer treatments.
Recent clinical trials have demonstrated that the immense majority of acute promyelocytic leukemia (APL) patients can be definitively cured by the combination of two targeted therapies: retinoic acid ...(RA) and arsenic. Mouse models have provided unexpected insights into the mechanisms involved. Restoration of PML nuclear bodies upon RA- and/or arsenic-initiated PML/RARA degradation is essential, while RA-triggered transcriptional activation is dispensable for APL eradication. Mutations of the arsenic-binding site of PML/RARA, but also PML, have been detected in therapy-resistant patients, demonstrating the key role of PML in APL cure. PML nuclear bodies are druggable and could be harnessed in other conditions.
Recent clinical trials have demonstrated that the immense majority of acute promyelocytic leukemia (APL) patients can be definitively cured by the combination of two targeted therapies: retinoic acid (RA) and arsenic. Mouse models have provided unexpected insights into the mechanisms involved. Restoration of PML nuclear bodies upon RA- and/or arsenic-initiated PML/RARA degradation is essential, while RA-triggered transcriptional activation is dispensable for APL eradication. Mutations of the arsenic-binding site of PML/RARA, but also PML, have been detected in therapy-resistant patients, demonstrating the key role of PML in APL cure. PML nuclear bodies are druggable and could be harnessed in other conditions.
Warburg suggested that the alterations in metabolism that he observed in cancer cells were due to the malfunction of mitochondria. In the past decade, we have revisited this idea and reached a better ...understanding of the 'metabolic switch' in cancer cells, including the intimate and causal relationship between cancer genes and metabolic alterations, and their potential to be targeted for cancer treatment. However, the vast majority of the research into cancer metabolism has been limited to a handful of metabolic pathways, while other pathways have remained in the dark. This Progress article brings to light the important contribution of fatty acid oxidation to cancer cell function.
Here, we demonstrate that protein-coding RNA transcripts can crosstalk by competing for common microRNAs, with microRNA response elements as the foundation of this interaction. We have termed such ...RNA transcripts as competing endogenous RNAs (ceRNAs). We tested this hypothesis in the context of PTEN, a key tumor suppressor whose abundance determines critical outcomes in tumorigenesis. By a combined computational and experimental approach, we identified and validated endogenous protein-coding transcripts that regulate PTEN, antagonize PI3K/AKT signaling, and possess growth- and tumor-suppressive properties. Notably, we also show that these genes display concordant expression patterns with PTEN and copy number loss in cancers. Our study presents a road map for the prediction and validation of ceRNA activity and networks and thus imparts a trans-regulatory function to protein-coding mRNAs.
Display omitted
► A microRNA target prediction algorithm predicts candidate PTEN ceRNAs ► Expression of PTEN ceRNAs significantly correlates with PTEN expression in vivo ► PTEN ceRNAs modulate PTEN and P-Akt levels in a microRNA-dependent manner ► PTEN ceRNAs display tumor-suppressive properties and are lost in human cancer
A large network of messenger RNAs regulates tumor-suppressive properties of PTEN by controlling the availability of microRNAs targeting PTEN.
Chromosomal translocations encode oncogenic fusion proteins that have been proven to be causally involved in tumorigenesis. Our understanding of whether such genomic alterations also affect ...non-coding RNAs is limited, and their impact on circular RNAs (circRNAs) has not been explored. Here, we show that well-established cancer-associated chromosomal translocations give rise to fusion circRNAs (f-circRNA) that are produced from transcribed exons of distinct genes affected by the translocations. F-circRNAs contribute to cellular transformation, promote cell viability and resistance upon therapy, and have tumor-promoting properties in in vivo models. Our work expands the current knowledge regarding molecular mechanisms involved in cancer onset and progression, with potential diagnostic and therapeutic implications.
Display omitted
•F-circRNAs are generated from cancer-associated chromosomal translocations•F-circRNAs promote transformation and cell survival upon treatment•F-circRNAs confer resistance to treatment in tumor cells
Chromosomal translocations associated with cancer give rise to fusion circRNAs which contribute to cellular transformation, affect cell viability, and have tumor-promoting properties in in vivo models.
The ERG gene is fused to TMPRSS2 in approximately 50% of prostate cancers (PrCa), resulting in its overexpression. However, whether this is the sole mechanism underlying ERG elevation in PrCa is ...currently unclear. Here we report that ERG ubiquitination and degradation are governed by the Cullin 3-based ubiquitin ligase SPOP and that deficiency in this pathway leads to aberrant elevation of the ERG oncoprotein. Specifically, we find that truncated ERG (ΔERG), encoded by the ERG fusion gene, is stabilized by evading SPOP-mediated destruction, whereas prostate cancer-associated SPOP mutants are also deficient in promoting ERG ubiquitination. Furthermore, we show that the SPOP/ERG interaction is modulated by CKI-mediated phosphorylation. Importantly, we demonstrate that DNA damage drugs, topoisomerase inhibitors, can trigger CKI activation to restore the SPOP/ΔERG interaction and its consequent degradation. Therefore, SPOP functions as a tumor suppressor to negatively regulate the stability of the ERG oncoprotein in prostate cancer.
Display omitted
•The E3 ubiquitin ligase SPOP promotes ERG degradation in a CKI-dependent manner•Prostate cancer-associated SPOP mutants fail to promote ERG destruction•ERG fusion proteins evade SPOP-mediated degradation and could be restored by CKI•Etoposide-induced ERG fusion protein degradation depends on SPOP and CKI
Gan et al. report that the Cullin 3SPOP E3 ubiquitin ligase plays a critical tumor-suppressive role in prostate cancer by negatively controlling ERG stability. Therefore, either SPOP mutation or ERG fusion can lead to elevated ERG protein levels by evading the SPOP-mediated degradation pathway to promote prostate cancer progression.
PDF
