MicroRNAs (miRNAs) are small non-coding RNAs that can modulate mRNA expression. Insights into the roles of miRNAs in development and disease have led to the development of new therapeutic approaches that are based on miRNA mimics or agents that inhibit their functions (antimiRs), and the first such approaches have entered the clinic. This Review discusses the role of different miRNAs in cancer and other diseases, and provides an overview of current miRNA therapeutics in the clinic. In just over two decades since the discovery of the first microRNA (miRNA), the field of miRNA biology has expanded considerably. Insights into the roles of miRNAs in development and disease, particularly in cancer, have made miRNAs attractive tools and targets for novel therapeutic approaches. Functional studies have confirmed that miRNA dysregulation is causal in many cases of cancer, with miRNAs acting as tumour suppressors or oncogenes (oncomiRs), and miRNA mimics and molecules targeted at miRNAs (antimiRs) have shown promise in preclinical development. Several miRNA-targeted therapeutics have reached clinical development, including a mimic of the tumour suppressor miRNA miR-34, which reached phase I clinical trials for treating cancer, and antimiRs targeted at miR-122, which reached phase II trials for treating hepatitis. In this article, we describe recent advances in our understanding of miRNAs in cancer and in other diseases and provide an overview of current miRNA therapeutics in the clinic. We also discuss the challenge of identifying the most efficacious therapeutic candidates and provide a perspective on achieving safe and targeted delivery of miRNA therapeutics.

MicroRNA therapeutics: towards a new era for the management of cancer and other diseases

Cancer is associated with fibroblasts at all stages of disease progression. This Review discusses the pleiotropic actions of cancer-associated fibroblasts (CAFs) on tumour cells and postulates that they are likely to be a heterogeneous and plastic population of cells in the tumour microenvironment. Among all cells, fibroblasts could be considered the cockroaches of the human body. They survive severe stress that is usually lethal to all other cells, and they are the only normal cell type that can be live-cultured from post-mortem and decaying tissue. Their resilient adaptation may reside in their intrinsic survival programmes and cellular plasticity. Cancer is associated with fibroblasts at all stages of disease progression, including metastasis, and they are a considerable component of the general host response to tissue damage caused by cancer cells. Cancer-associated fibroblasts (CAFs) become synthetic machines that produce many different tumour components. CAFs have a role in creating extracellular matrix (ECM) structure and metabolic and immune reprogramming of the tumour microenvironment with an impact on adaptive resistance to chemotherapy. The pleiotropic actions of CAFs on tumour cells are probably reflective of them being a heterogeneous and plastic population with context-dependent influence on cancer.

The biology and function of fibroblasts in cancer

Awareness that the metabolic phenotype of cells within tumours is heterogeneous - and distinct from that of their normal counterparts - is growing. In general, tumour cells metabolize glucose, lactate, pyruvate, hydroxybutyrate, acetate, glutamine, and fatty acids at much higher rates than their nontumour equivalents; however, the metabolic ecology of tumours is complex because they contain multiple metabolic compartments, which are linked by the transfer of these catabolites. This metabolic variability and flexibility enables tumour cells to generate ATP as an energy source, while maintaining the reduction-oxidation (redox) balance and committing resources to biosynthesis - processes that are essential for cell survival, growth, and proliferation. Importantly, experimental evidence indicates that metabolic coupling between cell populations with different, complementary metabolic profiles can induce cancer progression. Thus, targeting the metabolic differences between tumour and normal cells holds promise as a novel anticancer strategy. In this Review, we discuss how cancer cells reprogramme their metabolism and that of other cells within the tumour microenvironment in order to survive and propagate, thus driving disease progression; in particular, we highlight potential metabolic vulnerabilities that might be targeted therapeutically.

Cancer metabolism: a therapeutic perspective

Cancer progression often benefits from the selective conditions present in the tumour microenvironment, such as the presence of cancer-associated fibroblasts (CAFs), deregulated ECM deposition, expanded vascularisation and repression of the immune response. Generation of a hypoxic environment and activation of its main effector, hypoxia-inducible factor-1 (HIF-1), are common features of advanced cancers. In addition to the impact on tumour cell biology, the influence that hypoxia exerts on the surrounding cells represents a critical step in the tumorigenic process. Hypoxia indeed enables a number of events in the tumour microenvironment that lead to the expansion of aggressive clones from heterogeneous tumour cells and promote a lethal phenotype. In this article, we review the most relevant findings describing the influence of hypoxia and the contribution of HIF activation on the major components of the tumour microenvironment, and we summarise their role in cancer development and progression.

/pdf/the-hypoxic-tumour-microenvironment-4843dw6kw7.pdf

The hypoxic tumour microenvironment.

Functional genomics reveal that the serine synthesis pathway is essential in breast cancer

https://www.cell.com/cell-reports/pdf/S2211-1247(15)00133-3.pdf

Metabolic reprogramming of cancer-associated fibroblasts by IDH3α downregulation.

How TGF-β1-mediated signaling pathways are finely tuned to orchestrate the generation of carcinoma-associated fibroblasts (CAFs) is poorly understood Here, we demonstrate that miR-21 and the signaling of its target Smad 7 determine TGF-β1-induced CAF formation In primary cultured fibroblasts, mature miR-21 increases after TGF-β1 treatment, whereas the Smad 7 protein level decreases MiR-21 binds to the 3′ UTR of Smad7 mRNA and inhibits its translation, rather than causing its degradation Most importantly, Smad 7 is bound to Smad 2 and 3, which are thought to competitively bind to TGFBR1 and prevents their activation upon TGF-β1 stimulation The depletion of miR-21 or the overexpression of Smad 7 blocks TGF-β1-induced CAF formation, whereas the overexpression of miR-21 or the depletion of Smad 7 promotes CAF formation, even without TGF-β1 stimulation Collectively, these findings clearly demonstrate that miR-21 and Smad7 are critical regulators of TGF-β1 signaling during the induction of CAF formation

/pdf/mir-21-smad-7-signaling-determines-tgf-b1-induced-caf-1db9amqzfj.pdf

MiR-21/Smad 7 signaling determines TGF-β1-induced CAF formation

Cancer-associated Fibroblasts Promote Irradiated Cancer Cell Recovery Through Autophagy.

Cysteine is an essential amino acid for infants, aged people as well as patients with metabolic disorders. Although the thiol group of cysteine side chain is active in oxidative reactions, the role of cysteine in cancer remains largely unknown. Here, we report that the expression level of the solute carrier family 3, member 1 (SLC3A1), the cysteine carrier, tightly correlated with clinical stages and patients' survival. Elevated SLC3A1 expression accelerated the cysteine uptake and the accumulation of reductive glutathione (GSH), leading to reduced reactive oxygen species (ROS). ROS increased the stability and activity of PP2Ac, resulting in decreased AKT activity. Hence, SLC3A1 activated the AKT signaling through inhibiting PP2A phosphatase activity. Consistently, overexpression of SLC3A1 enhanced tumorigenesis of breast cancer cells, whereas blocking SLC3A1 either with specific siRNA or SLC3A1 specific inhibitor sulfasalazine suppressed tumor growth and also abolished dietary NAC-promoted tumor growth. Collectively, our data demonstrate that SLC3A1 promotes cysteine uptake and determines cellular response to antioxidant N-acetylcysteine, suggesting SLC3A1 is a potential therapeutic target for breast cancer.

/pdf/cysteine-transporter-slc3a1-promotes-breast-cancer-xjlnooggzl.pdf

Cysteine transporter SLC3A1 promotes breast cancer tumorigenesis.

// Xiaodan Hou 1, 3 , Jieying Zhang 1 , Yongbin Wang 1 , Wujun Xiong 2 and Jun Mi 1 1 Department of Biochemistry and Molecular Cell Biology, Shanghai Key Laboratory of Tumor Microenvironment and Inflammation, Shanghai Jiao Tong University School of Medicine, Shanghai, China 2 Shanghai East Hospital, Affiliated to Tongji University, Shanghai, China 3 Center of Systems Medicine, Chinese Academy of Medical Sciences, Suzhou Institute of Systems Medicine, Suzhou, China Correspondence to: Jun Mi, email: jmei@sjtu.edu.cn Wujun Xiong, email: xiongwujun@126.com Keywords: IDH1, TGFBR, TGF-β signalling, Cav1, alpha-ketoglutarate Received: July 28, 2017      Accepted: August 23, 2017      Published: September 13, 2017 ABSTRACT TGF-β signalling plays an important role in fibroblasts activation and tumour progression. Here, we report that the TGFBR-IDH1-Cav1 axis promotes TGF- β signalling in fibroblasts. Our data demonstrated that IDH1 was downregulated by TGF-β signalling in fibroblasts, and downregulation of IDH1 increased cellular concentration of α-ketoglutarate (α-KG) by accelerating glutamine metabolization. Interestingly, α-KG suppressed Cav1 expression through reducing the trimethylation of histone H3K4. Furthermore, Cav1 downregulation inhibited TGFBR protein degradation. In turn, the activated TGFBR promoted TGF-β signalling. These findings demonstrated that metabolic enzyme IDH1 regulates TGF-β signalling by feedback mechanism through α-KG and TGFBR-IDH1-Cav1 axis is important for TGF-β signalling.

https://www.oncotarget.com/index.php?journal=oncotarget&page=article&op=download&path%5B%5D=20861&path%5B%5D=66449

Yongbin Wang

Papers

Metabolic reprogramming of cancer-associated fibroblasts by IDH3α downregulation.

MiR-21/Smad 7 signaling determines TGF-β1-induced CAF formation

Cancer-associated Fibroblasts Promote Irradiated Cancer Cell Recovery Through Autophagy.

Cysteine transporter SLC3A1 promotes breast cancer tumorigenesis.

TGFBR-IDH1-Cav1 axis promotes TGF-β signalling in cancer-associated fibroblast