Iron is an essential nutrient that plays a complex role in cancer biology. Iron metabolism must be tightly controlled within cells. Whilst fundamental to many cellular processes and required for cell survival, excess labile iron is toxic to cells. Increased iron metabolism is associated with malignant transformation, cancer progression, drug resistance and immune evasion. Depleting intracellular iron stores, either with the use of iron chelating agents or mimicking endogenous regulation mechanisms, such as microRNAs, present attractive therapeutic opportunities, some of which are currently under clinical investigation. Alternatively, iron overload can result in a form of regulated cell death, ferroptosis, which can be activated in cancer cells presenting an alternative anti-cancer strategy. This review focuses on alterations in iron metabolism that enable cancer cells to meet metabolic demands required during different stages of tumorigenesis in relation to metastasis and immune response. The strength of current evidence is considered, gaps in knowledge are highlighted and controversies relating to the role of iron and therapeutic targeting potential are discussed. The key question we address within this review is whether iron modulation represents a useful approach for treating metastatic disease and whether it could be employed in combination with existing targeted drugs and immune-based therapies to enhance their efficacy.

No abstract

Sorafenib remains the only approved drug for treating patients with advanced hepatocellular carcinoma (HCC). However, the therapeutic effect of sorafenib is transient, and patients invariably develop sorafenib resistance (SR). Recently, TYRO3, a member of the TYRO3-AXL-MER family of receptor tyrosine kinases, was identified as being aberrantly expressed in a significant proportion of HCC; however, its role in SR is unknown. In this study, we generated two functionally distinct sorafenib-resistant human Huh-7 HCC cell lines in order to identify new mechanisms to abrogate acquired SR as well as new potential therapeutic targets in HCC. Initially, we investigated the effects of a microRNA (miR), miR-7-5p (miR-7), in both in vitro and in vivo preclinical models of human HCC and identified miR-7 as a potent tumor suppressor of human HCC. We identified TYRO3 as a new functional target of miR-7, which regulates proliferation, migration, and invasion of Huh-7 cells through the phosphoinositide 3-kinase/protein kinase B pathway and is markedly elevated with acquisition of SR. Furthermore, miR-7 effectively silenced TYRO3 expression in both sorafenib-sensitive and sorafenib-resistant Huh-7 cells, inhibiting TYRO3/growth arrest specific 6-mediated cancer cell migration and invasion. Conclusion: We identified a mechanism for acquiring SR in HCC that is through the aberrant expression of the TYRO3/phosphoinositide 3-kinase/protein kinase B signal transduction pathway, and that can be overcome by miR-7 overexpression. Taken together, these data suggest a potential role for miR-7 as an RNA-based therapeutic to treat refractory and drug-resistant HCC. (HEPATOLOGY 2018;67:216-231) L iver cancer ranks sixth among all malignancies in the world and is the second leading cause of cancer-related mortality. (1) The rising incidence of hepatocellular carcinoma (HCC), the most common primary malignant neoplasm of the liver, has been linked to hepatitis B or C infection and increasing worldwide obesity associated with fatty liver disease. (2) In 2017, it is estimated that 40,710 patients will be diagnosed with HCC in the United States, and more than 70% of them will eventually die from this

microRNA-7-5p (miR-7-5p) is a tumor suppressor in multiple cancer types and inhibits growth and invasion by suppressing expression and activity of the epidermal growth factor receptor (EGFR) signaling pathway. While melanoma is not typically EGFR-driven, expression of miR-7-5p is reduced in metastatic tumors compared to primary melanoma. Here, we investigated the biological and clinical significance of miR-7-5p in melanoma. We found that augmenting miR-7-5p expression in vitro markedly reduced tumor cell viability, colony formation and induced cell cycle arrest. Furthermore, ectopic expression of miR-7-5p reduced migration and invasion of melanoma cells in vitro and reduced metastasis in vivo. We used cDNA microarray analysis to identify a subset of putative miR-7-5p target genes associated with melanoma and metastasis. Of these, we confirmed nuclear factor kappa B (NF-κB) subunit RelA, as a novel direct target of miR-7-5p in melanoma cells, such that miR-7-5p suppresses NF-κB activity to decrease expression of canonical NF-κB target genes, including IL-1β, IL-6 and IL-8. Importantly, the effects of miR-7-5p on melanoma cell growth, cell cycle, migration and invasion were recapitulated by RelA knockdown. Finally, analysis of gene array datasets from multiple melanoma patient cohorts revealed an association between elevated RelA expression and poor survival, further emphasizing the clinical significance of RelA and its downstream signaling effectors. Taken together, our data show that miR-7-5p is a potent inhibitor of melanoma growth and metastasis, in part through its inactivation of RelA/NF-κB signaling. Furthermore, miR-7-5p replacement therapy could have a role in the treatment of this disease.

No abstract

BackgroundmicroRNAs (miRNAs) are short non-coding RNAs that fine-tune gene expression. The aberrant expression of miRNAs is associated with many diseases and they have both therapeutic and biomarker potential. However, our understanding of their usefulness is dependent on the tools we have to study them. Previous studies have identified the need to optimise and standardise RNA extraction methods in order to avoid biased results. Herein, we extracted RNA from murine lung, liver and brain tissues using five commercially available total RNA extraction methods. These included either: phenol: chloroform extraction followed by alcohol precipitation (TRIzol), phenol:chloroform followed by solid-phase extraction (column-based; miRVana and miRNeasy) and solid-phase separation with/without affinity resin (Norgen total and Isolate II). We then evaluated each extraction method for the quality and quantity of RNA recovered, and the expression of miRNAs and target genes.ResultsWe identified differences between each of the RNA extraction methods in the quantity and quality of RNA samples, and in the analysis of miRNA and target gene expression. For the purposes of consistency in quantity, quality and high recovery of miRNAs from tissues, we identified that Phenol:chloroform phase separation combined with silica column-based solid extraction method was preferable (miRVana microRNA isolation). We also identified a method that is not appropriate for miRNA analysis from tissue samples (Bioline Isolate II). For target gene expression any of the kits could be used to analyse mRNA, but if interested in analysing mRNA and miRNA from the same RNA samples some methods should be avoided.ConclusionsDifferent methods used to isolate miRNAs will yield different results and therefore a robust RNA isolation method is required for reproducibility. Researchers should optimise these methods for their specific application and keep in mind that “total RNA” extraction methods do not isolate all types of RNA equally.Electronic supplementary materialThe online version of this article (10.1186/s12896-018-0421-6) contains supplementary material, which is available to authorized users.

No abstract

microRNAs (miRNAs) are a family of short, non-coding RNA molecules that drive a complex network of post-transcriptional gene regulation by enhancing target mRNA decay and/or inhibiting protein synthesis from mRNA transcripts. They regulate genes involved in key aspects of normal cell growth, development and the maintenance of body homeostasis and have been closely linked to the development and progression of human disease, in particular cancer. Over recent years there has been much interest regarding their potential as biomarkers and as therapeutic agents or targets. microRNA-7 (miR-7) is a 23 nucleotide (nt) miRNA known primarily to act as a tumour suppressor. miR-7 directly inhibits a number of oncogenic targets and impedes various aspects of cancer progression in vitro and in vivo, however, some studies have also implicated miR-7 in oncogenic roles. This review summarises the role of miR-7 in cancer, its potential in miRNA-based replacement therapy and its capacity as both a diagnostic and prognostic biomarker.