Let-7a mimic attenuates CCL18 induced breast cancer cell metastasis through Lin 28 pathway

RNA-binding proteins in breast cancer: Biological implications and therapeutic opportunities

RNA-binding proteins (RBPs) refer to a class of proteins that participate in alternative splicing, RNA stability, polyadenylation, localization and translation of RNAs, thus regulating gene expression in post-transcriptional manner. Dysregulation of RNA-RBP interaction contributes to various diseases, including cancer. In breast cancer, disorders in RBP expression and function influence the biological characteristics of tumor cells. Targeting RBPs has fostered the development of innovative therapies for breast cancer. However, the RBP-related mechanisms in breast cancer are not completely clear. In this review, we summarize the regulatory mechanisms of RBPs and their signaling crosstalk in breast cancer. Specifically, we emphasize the potential of certain RBPs as prognostic factors due to their effects on proliferation, invasion, apoptosis, and therapy resistance of breast cancer cells. Most importantly, we present a comprehensive overview of the latest RBP-related therapeutic strategies and novel therapeutic targets that have proven to be useful in the treatment of breast cancer.

Therapeutic Approaches Targeting Proteins in Tumor-Associated Macrophages and Their Applications in Cancers

Tumor-associated macrophages (TAMs) promote tumor proliferation, invasion, angiogenesis, stemness, therapeutic resistance, and immune tolerance in a protein-dependent manner. Therefore, the traditional target paradigms are often insufficient to exterminate tumor cells. These pro-tumoral functions are mediated by the subsets of macrophages that exhibit canonical protein markers, while simultaneously having unique transcriptional features, which makes the proteins expressed on TAMs promising targets during anti-tumor therapy. Herein, TAM-associated protein-dependent target strategies were developed with the aim of either reducing the numbers of TAMs or inhibiting the pro-tumoral functions of TAMs. Furthermore, the recent advances in TAMs associated with tumor metabolism and immunity were extensively exploited to repolarize these TAMs to become anti-tumor elements and reverse the immunosuppressive tumor microenvironment. In this review, we systematically summarize these current studies to fully illustrate the TAM-associated protein targets and their inhibitors, and we highlight the potential clinical applications of targeting the crosstalk among TAMs, tumor cells, and immune cells in anti-tumor therapy.

Research progress on RNA‑binding proteins in breast cancer (Review)

Breast cancer is the most common malignancy among women, and the abnormal regulation of gene expression serves an important role in its occurrence and development. However, the molecular mechanisms underlying gene expression are highly complex and heterogeneous, and RNA-binding proteins (RBPs) are among the key regulatory factors. RBPs bind targets in an environment-dependent or environment-independent manner to influence mRNA stability and the translation of genes involved in the formation, progression, metastasis and treatment of breast cancer. Due to the growing interest in these regulators, the present review summarizes the most influential studies concerning RBPs associated with breast cancer to elucidate the role of RBPs in breast cancer and to assess how they interact with other key pathways to provide new molecular targets for the diagnosis and treatment of breast cancer.

Non-Coding RNAs in the Crosstalk between Breast Cancer Cells and Tumor-Associated Macrophages

Non-coding RNAs (ncRNAs) play a pivotal role in regulating the tumor microenvironment (TME) by controlling gene expression at multiple levels. In tumors, ncRNAs can mediate the crosstalk between cancer cells and other cells in the TME, such as immune cells, stromal cells, and endothelial cells, influencing tumor development and progression. Tumor-associated macrophages (TAMs) are among the most abundant inflammatory cells infiltrating solid cancers that promote tumorigenesis, and their infiltration correlates with a poor prognosis in many tumors. Cancer cells produce different ncRNAs that orchestrate TAM recruitment and polarization toward a tumor-promoting phenotype. Tumor-reprogrammed macrophages shape the TME by promoting angiogenesis and tissue remodeling, and suppressing the anti-tumor activity of adaptive immune cells. TAMs can also produce ncRNA molecules that boost cancer cell proliferation and direct their phenotype and metabolic changes facilitating cancer progression and metastasis. This review will focus on the crosstalk between cancer cells and TAMs mediated by microRNAs and long non-coding RNAs during breast cancer (BC) initiation and progression.

Photocaged amplified FRET nanoflares: spatiotemporal controllable of mRNA-powered nanomachines for precise and sensitive microRNA imaging in live cells

There is considerable interest in creating a precise and sensitive strategy for in situ visualizing and profiling intracellular miRNA. Present here is a novel photocaged amplified FRET nanoflare (PAFN), which spatiotemporal controls of mRNA-powered nanomachine for precise and sensitive miRNA imaging in live cells. The PAFN could be activated remotely by light, be triggered by specific low-abundance miRNA and fueled by high-abundance mRNA. It offers high spatiotemporal control over the initial activity of nanomachine at desirable time and site, and a ‘one-to-more’ ratiometric signal amplification model. The PAFN, an unprecedented design, is quiescent during the delivery process. However, upon reaching the interest tumor site, it can be selectively activated by light, and then be triggered by specific miRNA, avoiding undesirable early activation and reducing nonspecific signals, allowing precise and sensitive detection of specific miRNA in live cells. This strategy may open new avenues for creating spatiotemporally controllable and endogenous molecule-powered nanomachine, facilitating application at biological and medical imaging.

The Hypoxic Microenvironment of Breast Cancer Cells Promotes Resistance in Radiation Therapy

The American Cancer Society has estimated an expected 279,100 new breast cancer cases, and an expected 42,690 breast cancer deaths in the U.S. for the year 2020. This includes an estimated 276,480 women who are expected to be diagnosed. Radiation therapy, also called ionizing radiation therapy, is one of the most frequently used methods in the treatment of breast cancer. While radiation therapy is used in the treatment of more than 50% of all cancer cases, tumor resistance to ionizing radiation presents a major challenge for effective cancer treatment. Most tumor cells are in a hypoxic microenvironment that promotes resistance to radiation therapy. In addition to radiation resistance, the hypoxic microenvironment also promotes cancer proliferation and metastasis. In this review, we will discuss the hypoxic microenvironment of breast cancer tumors, related signaling pathways, breast cancer stem-like cells, and the resistance to radiation therapy. Recent developments in our understanding of tumor hypoxia and hypoxic pathways may assist us in developing new strategies to increase cancer control in radiation therapy.

Remote postconditioning ameliorates stroke damage by preventing let-7a and miR-143 up-regulation

Remote limb ischemic postconditioning (RLIP) is a well-established neuroprotective strategy able to protect the brain from a previous harmful ischemic insult through a sub-lethal occlusion of the femoral artery. Neural and humoral mechanisms have been proposed as mediators required to transmit the peripheral signal from limb to brain. Moreover, different studies suggest that protection observed at brain level is associated to a general genetic reprogramming involving also microRNAs (miRNAs) intervention.

Methods: Brain ischemia was induced in male rats by transient occlusion of the middle cerebral artery (tMCAO), whereas RLIP was achieved by one cycle of temporary occlusion of the ipsilateral femoral artery after tMCAO. The expression profile of 810 miRNAs was evaluated in ischemic brain samples from rats subjected either to tMCAO or to RLIP. Among all analyzed miRNAs, there were four whose expression were upregulated after stroke and returned to basal level after RLIP, thus suggesting a possible involvement in RLIP-induced neuroprotection. These selected miRNAs were intracerebroventricularly infused in rats subjected to remote ischemic postconditioning, and their effect was evaluated in terms of brain damage, neurological deficit scores and expression of putative targets.

Results: Twenty-one miRNAs, whose expression was significantly affected by tMCAO and by tMCAO plus RLIP, were selected based on microarray microfluidic profiling. Our data showed that: (1) stroke induced an up-regulation of let-7a and miR-143 (2) these two miRNAs were involved in the protective effects induced by RLIP and (3) HIF1-α contributes to their protective effect. Indeed, their expression was reduced after RLIP and the exogenous intracerebroventricularly infusion of let-7a and miR-143 mimics prevented neuroprotection and HIF1-α overexpression induced by RLIP.

Conclusions: Prevention of cerebral let-7a and miR-143 overexpression induced by brain ischemia emerges as new potential strategy in stroke intervention.

CCL18 in the Progression of Cancer

A neoplastic tumor consists of cancer cells that interact with each other and non-cancerous cells that support the development of the cancer. One such cell are tumor-associated macrophages (TAMs). These cells secrete many chemokines into the tumor microenvironment, including especially a large amount of CCL18. This chemokine is a marker of the M2 macrophage subset; this is the reason why an increase in the production of CCL18 is associated with the immunosuppressive nature of the tumor microenvironment and an important element of cancer immune evasion. Consequently, elevated levels of CCL18 in the serum and the tumor are connected with a worse prognosis for the patient. This paper shows the importance of CCL18 in neoplastic processes. It includes a description of the signal transduction from PITPNM3 in CCL18-dependent migration, invasion, and epithelial-to-mesenchymal transition (EMT) cancer cells. The importance of CCL18 in angiogenesis has also been described. The paper also describes the effect of CCL18 on the recruitment to the cancer niche and the functioning of cells such as TAMs, regulatory T cells (T_reg), cancer-associated fibroblasts (CAFs) and tumor-associated dendritic cells (TADCs). The last part of the paper describes the possibility of using CCL18 as a therapeutic target during anti-cancer therapy.

Let-7 as biomarker, prognostic indicator, and therapy for precision medicine in cancer

Abnormal regulation and expression of microRNAs (miRNAs) has been documented in various diseases including cancer. The miRNA let-7 (MIRLET7) family controls developmental timing and differentiation. Let-7 loss contributes to carcinogenesis via an increase in its target oncogenes and stemness factors. Let-7 targets include genes regulating the cell cycle, cell signaling, and maintenance of differentiation. It is categorized as a tumor suppressor because it reduces cancer aggressiveness, chemoresistance, and radioresistance. However, in rare situations let-7 acts as an oncogene, increasing cancer migration, invasion, chemoresistance, and expression of genes associated with progression and metastasis. Here, we review let-7 function as tumor suppressor and oncogene, considering let-7 as a potential diagnostic and prognostic marker, and a therapeutic target for cancer treatment. We explain the complex regulation and function of different let-7 family members, pointing to abnormal processes involved in carcinogenesis. Let-7 is a promising option to complement conventional cancer therapy, but requires a tumor specific delivery method to avoid toxicity. While let-7 therapy is not yet established, we make the case that assessing its tumor presence is crucial when choosing therapy. Clinical data demonstrate that let-7 can be used as a biomarker for rational precision medicine decisions, resulting in improved patient survival.

A genetic variant rs13293512 in the promoter of let-7 is associated with an increased risk of breast cancer in Chinese women

Growing evidence has demonstrated that single-nucleotide polymorphisms (SNPs) in the promoter of miRNA may influence individuals’ susceptibility to human diseases. We examined two SNPs rs10877887 and rs13293512 in the promoters of let-7 family to determine if the two SNPs were related to the occurrence of breast cancer (BC). Genotyping of the two SNPs was performed by PCR and restriction fragment length polymorphism analysis or TaqMan assay in 301 BC patients and 310 age matched controls. We found a higher frequency of rs13293512 CC genotype and rs13293512 C allele amongst BC patients (CC vs TT: adjusted odds ratio (OR) = 1.78; 95% CI: 1.14–2.80; P=0.012; C vs T: adjusted OR = 1.33; 95% CI: 1.06–1.67; P=0.013). Stratification analysis showed that rs13293512 CC genotype was associated with an increased risk of BC in patients with negative estrogen receptor (adjusted OR = 2.39; 95% CI: 1.32–4.30; P=0.004), patients with negative progesterone receptor (adjusted OR = 1.92; 95% CI: 1.11–3.33; P=0.02), patients with T1-2 stage cancer (adjusted OR = 1.77; 95% CI: 1.07–2.93; P=0.03), and patients with N1-3 stage cancer (adjusted OR = 1.89; 95% CI: 1.13–3.17; P=0.015). These findings suggest that rs13293512 in the promoter of let-7a-1/let-7f-1/let-7d cluster may be a possible biomarker for the development of BC in Chinese women.

Lin28 promotes dental pulp cell proliferation via upregulation of cyclin-dependent proteins and interaction with let-7a/IGF2BP2 pathways

Caries, pulpitis, and trauma are the main causes of dental pulp damage. The regeneration capacity of dental pulp declines with age. Lin28 is a conserved RNA-binding protein in higher eukaryotes that regulates several important cellular functions associated with development, glucose metabolism, differentiation, and pluripotency. Conditional reactivation of Lin28 gene in adult mice markedly accelerates the wound-healing process in injured digits. However, little is known about its functions and molecular mechanism in human dental pulp. The aim of this study was to investigate the effects and mechanism of overexpression of Lin28 gene on the proliferation of human dental pulp cells (HDPCs). For this purpose, a number of molecular and biochemical analytical techniques, including the ethynyl-2'-deoxyuridine (EdU) incorporation assay, RNA-protein immunoprecipitation (RIP) analysis, and luciferase assays, were used for detailed characterization. In addition, factors regulating HDPCs activation were explored through gain-of-function and loss-of-function analyses. The results demonstrate that Lin28 promotes cell proliferation and the S-G2/M transition of HDPCs and directly binds to a group of cell cycle regulatory mRNAs in HDPCs. Through bioinformatics analysis and luciferase assays, we confirmed that let-7a targets IGF2BP2. Silencing of IGF2BP2 showed similar cellular and molecular effects as let-7a. Similarly, restoration of IGF2BP2 counteracted the effects of let-7a expression. In conclusion, Lin28 promotes cell proliferation by regulation of both mRNA translation (let-7-independent) and miRNA biogenesis (let-7-dependent). Lin28 can promote the expression of pro-proliferative genes by directly enhancing their translation to maintain a tight control over HDPC proliferation.

Therapeutic microRNAs in human cancer

MicroRNAs (miRNAs) are RNA molecules at about 22 nucleotide in length that are non-coding, which regulate gene expression in the post-transcriptional level by performing degradation or blocks translation of the target mRNA. It is known that they play roles in mechanisms such as metabolic regulation, embryogenesis, organogenesis, differentiation and growth control by providing post-transcriptional regulation of gene expression. With these properties, miRNAs play important roles in the regulation of biological processes such as proliferation, differentiation, apoptosis, drug resistance mechanisms in eukaryotic cells. In addition, there are miRNAs that can be used for cancer therapy. Tumor cells and tumor microenvironment have different miRNA expression profiles. Some miRNAs are known to play a role in the onset and progression of the tumor. miRNAs with oncogenic or tumor suppressive activity specific to different cancer types are still being investigated. This review summarizes the role of miRNAs in tumorigenesis, therapeutic strategies in human cancer and current studies.

Oncogenic mechanisms of Lin28 in breast cancer: new functions and therapeutic opportunities

The RNA binding protein Lin28 is best known for the critical role in cell development, recent researches also have implied its oncogenic function in various human cancers, including breast cancer. Specifically, aberrant Lin28 participates in multiple pathological processes, such as proliferation, metastasis, radiotherapy and chemotherapy resistance, metabolism, immunity and inflammation as well as stemness. In this review, we summarize the let-7-dependent and let-7-independent mechanism regulated by Lin28, focusing on its relation with tumor hallmarks in breast cancer, and subsequently discuss our present knowledge of Lin28 to develop a molecular-based therapeutic strategy against breast cancer.

The suppressing role of miR-622 in renal cell carcinoma progression by down-regulation of CCL18/MAPK signal pathway

BACKGROUND

MicroRNAs have emerged as critical modulators of carcinogenesis and tumor progression including renal cell carcinoma (RCC). MiR-622 plays as a tumor inhibitor in some types of cancer, however, its role in kidney cancer is unknown. The purpose of the present work is to investigate the functional behaviors and regulatory mechanism of miR-622 in RCC.

RESULTS

We examined the expression of miR-622 in RCC and adjacent normal tissues and then explored the roles of miR-622. The results of this analysis indicated that miR-622 activity was significantly downregulated in RCC tissues compared with the corresponding normal tissues, so did in RCC cell lines. MiR-622 was associated with RCC aggressiveness. MiR-622 in RCC cells decreased CCL18 expression and suppressed CCL18 activated MAPK signal pathway. Using Western blot and luciferase reporter assays, it was verified that CCL18 was a direct target of miR-622. A specific and inverse correlation between miR-622 and CCL18 expression was found in human RCC samples.

CONCLUSIONS

The results demonstrated that miR-622 acted as a tumor-promoting miRNA by targeting CCL18 in RCC.

CCL18 - Beyond chemotaxis

The chemokine CCL18 is constitutively expressed in human lung and serum, and is further elevated during pathologic conditions such as allergy, fibrosis and cancer, suggesting that it may participate in both homeostatic and inflammatory processes. Under steady state conditions, CCL18 has chemotactic activity, albeit modest, toward naïve T cells and as such, may be involved in the initiation of the adaptive response. Its chemotactic effect on inflammatory cells is ambiguous as it attracts both regulatory and inflammatory immune cells. CCL18 can also modulate tissue inflammation by inhibiting cell recruitment through binding to glycosaminoglycans with high affinity, thereby displacing other chemokines bound to the endothelial surface. CCL18 induces regulatory phenotype and function of immune cells through direct activation and plays a major role in fibrotic processes, particularly in the lung. Finally, CCL18 is involved in cancer cell activation and migration and also participates in immune tolerance toward cancer. Its high constitutive expression levels and its further up-regulation in many diseases, together with its moderate chemoattractant properties support the fact that this chemokine has activities beyond cell recruitment.

Arsenic trioxide inhibits cell growth and motility via up-regulation of let-7a in breast cancer cells

Arsenic trioxide (ATO) has been reported to exert its anti-cancer activities in human cancers. However, the molecular mechanism of ATO-triggered anti-tumor activity has not been fully elucidated. Recently, multiple studies demonstrated that ATO could regulate miRNAs in human cancers. Therefore, in this study, we investigated whether ATO regulated let-7a in breast cancer cells. We found that ATO upregulated let-7a level in breast cancer cells. We also found that up-regulation of let-7a inhibited cell growth and induced apoptosis and retarded cell migration and invasion. We also observed that up-regulation of let-7a enhanced cell growth inhibition and invasion suppression induced by ATO treatment. Our findings suggest that ATO suppressed cell growth, stimulated apoptosis, and retarded cell invasion partly via upregulation of let-7a in breast cancer cells. Our study provides a new anti-tumor mechanism of ATO treatment in breast cancer.

Free-Energy-Driven Lock/Open Assembly-Based Optical DNA Sensor for Cancer-Related microRNA Detection with a Shortened Time-to-Result

Quantification of cancer biomarker microRNAs (miRs) by exquisitely designed biosensors with a short time-to-result is of great clinical significance. With immobilized capture probes (CPs) and fluorescent-labeled signal probes (SPs), surface-involved sandwich-type (SST) biosensors serve as powerful tools for rapid, highly sensitive, and selective detection of miR in complex matrices as opposed to the conventional techniques. One key challenge for such SST biosensors is the existence of false-negative signals when the amount of miRs exceeds SPs in solution phase for a surface with a limited number of CP. To meet this challenge, a dynamic lock/open DNA assembly was designed to rationally program the pathway for miR/SP hybrids. Based on secondary structure analysis and free-energy assessment, a "locker" strand that partially hybridizes with target miR by two separated short arms was designed to stabilize target miR, preventing possible false-negative signals. The strategy was demonstrated on a fiber-based fluorescent DNA-sensing platform. CP/miR/SP sandwiches formed on the fiber surface would generate fluorescent signals for quantitative analysis. The developed SST biosensor was able to detect miR Hsa let-7a with a detection limit of 24 pM. The applicability of this free-energy-driven lock/open assembly-based optical DNA sensor was further confirmed with spiked human urine and serum samples.

Curcumin Inhibits LIN-28A through the Activation of miRNA-98 in the Lung Cancer Cell Line A549

Metastasis is common in lung cancer and is associated with poor clinical outcomes and increased mortality. Curcumin is a natural anti-cancer agent that inhibits the metastasis of various cancers by modulating the expression of micro (mi) RNAs such as miR-98, which acts as a tumor suppressor. This study investigated the effect of curcumin on miR-98 expression and in vitro cell line growth and invasiveness in lung cancer. Curcumin treatment enhanced the expression of miR-98 and reduced that of the miR-98 target gene LIN28A as well as matrix metalloproteinase (MMP) 2 and MMP9 in vitro and in vivo. MiR-98 overexpression suppressed lung cancer cell migration and invasion by inhibiting LIN28A-induced MMP2 and MMP9 expression. Meanwhile, LIN28A level was downregulated by overexpression of miR-98 mimic. Induction of miR-98 by curcumin treatment suppressed MMP2 and MMP9 by targeting LIN28A. These findings provide insight into the mechanisms by which curcumin suppresses lung cancer cell line growth in vitro and in vivo and invasiveness in vitro.

Tumor-Associated Macrophages Promote Malignant Progression of Breast Phyllodes Tumors by Inducing Myofibroblast Differentiation

Myofibroblast differentiation plays an important role in the malignant progression of phyllodes tumor, a fast-growing neoplasm derived from periductal stromal cells of the breast. Macrophages are frequently found in close proximity with myofibroblasts, but it is uncertain whether they are involved in the myofibroblast differentiation during phyllodes tumor progression. Here we show that increased density of tumor-associated macrophage (TAM) correlates with malignant progression of phyllodes tumor. We found that TAMs stimulated myofibroblast differentiation and promoted the proliferation and invasion of phyllodes tumor cells. Furthermore, we found that levels of the chemokine CCL18 in TAM was an independent prognostic factor of phyllodes tumor. Mechanistic investigations showed that CCL18 promoted expression of α-smooth muscle actin, a hallmark of myofibroblast, along with the proliferation and invasion of phyllodes tumor cells, and that CCL18-driven myofibroblast differentiation was mediated by an NF-κB/miR-21/PTEN/AKT signaling axis. In murine xenograft models of human phyllodes tumor, CCL18 accelerated tumor growth, induced myofibroblast differentiation, and promoted metastasis. Taken together, our findings indicated that TAM drives myofibroblast differentiation and malignant progression of phyllodes tumor through a CCL18-driven signaling cascade amenable to antibody disruption. Cancer Res; 77(13); 3605-18. ©2017 AACR.