MicroRNA-34 family in breast cancer: from research to therapeutic potential

High Expression of miR-34a Associated with Less Aggressive Cancer Biology but Not with Survival in Breast Cancer

Most breast cancer (BC) patients succumb to metastatic disease. MiR-34a is a well-known tumor suppressive microRNA which exerts its anti-cancer functions by playing a role in p53, apoptosis induction, and epithelial-mesenchymal transition (EMT) suppression. Molecular Taxonomy of Breast Cancer International Consortium (METABRIC) and The Cancer Genome Atlas (TCGA) cohorts were used to test our hypothesis that miR-34a high BCs translate to less aggressive cancer biology and better survival in large cohorts. There was no association between miR-34a expression levels and clinicopathological features of BC patients except for HER2 positivity. MiR-34a high expressing tumors were associated with lower Nottingham pathological grades and lower MKI67 expression. In agreement, high miR-34a tumors demonstrated lower GSVA scores of cell cycle and cell proliferation-related gene sets. High miR-34a tumors enriched the p53 pathway and apoptosis gene sets. Unexpectedly, high miR-34a tumors also associated with elevated EMT pathway score and ZEB1 and two expressions. MiR-34a expression did not associate with any distant metastasis. Further, high miR-34a tumors did not associate with better survival compared with miR-34a low tumors. In conclusion, the clinical relevance of miR-34a high expressing tumors was associated with suppressed cell proliferation, enhanced p53 pathway and apoptosis, but enhanced EMT and these findings did not reflect better survival outcomes in large BC patient cohorts.

Delivery of dual miRNA through CD44-targeted mesoporous silica nanoparticles for enhanced and effective triple-negative breast cancer therapy

The development of new therapeutic strategies to target triple-negative breast cancer (TNBC) is in much demand to overcome the roadblocks associated with the existing treatment procedures. In this regard, therapies targeting the CD44 receptor have drawn attention for more than a decade. MicroRNAs (miRNAs) modulate post-transcriptional gene regulation and thus, the correction of specific miRNA alterations using miRNA mimics or antagomiRs is an emerging strategy to normalize the genetic regulation in the tumor microenvironment. It has been acknowledged that miR-34a is downregulated and miR-10b is upregulated in TNBC, which promotes tumorigenesis and metastatic dissemination. However, there are a few barriers related to miRNA delivery. Herein, we have introduced tailored mesoporous silica nanoparticles (MSNs) for the co-delivery of miR-34a-mimic and antisense-miR-10b. MSN was functionalized with a cationic basic side chain and then loaded with the dual combination to overexpress miR-34a and downregulate miR-10b simultaneously. Finally, the loaded MSNs were coated with an hyaluronic acid-appended PEG-PLGA polymer for specific targeting. The cellular uptake, release profile, and subsequent effect in TNBC cells were evaluated. In vitro and in vivo studies demonstrated high specificity in TNBC tumor targeting, leading to efficient tumor growth inhibition as well as the retardation of metastasis, which affirmed the clinical application potential of the system.

A Systemic Review on the Regulatory Roles of miR-34a in Gastrointestinal Cancer

MicroRNAs (miRNAs) are a class of endogenous non-coding single-stranded small-molecule RNAs that regulate gene expression by repressing target messenger RNA (mRNA) translation or degrading mRNA. miR-34a is one of the most important miRNAs participating in various physiological and pathological processes. miR-34a is abnormally expressed in a variety of tumors. The roles of miR-34a in gastrointestinal cancer (GIC) draw lots of attention. Numerous studies have demonstrated that dysregulated miR-34a is closely related to the proliferation, differentiation, migration, and invasion of tumor cells, as well as the diagnosis, prognosis, treatment, and chemo-resistance of tumors. Thus, we systematically reviewed the abnormal expression and regulatory roles of miR-34a in GICs including esophageal cancer (EC), gastric cancer (GC), colorectal cancer (CRC), hepatocellular carcinoma (HCC), pancreatic cancer (PC), and gallbladder cancer (GBC). It may provide a profile of versatile roles of miR-34a in GICs.

The role of miR-34 in cancer drug resistance

Resistance to conventional chemotherapy remains a major cause of cancer relapse and cancer-related deaths. Therefore, there is an urgent need to overcome resistance barriers. To improve cancer treatment approaches, it is critical to elucidate the basic mechanisms underlying drug resistance. Increasingly, the mechanisms involving micro-RNAs (miRNAs) are studied because miRNAs are also considered practical therapeutic options due to high degrees of specificity, efficacy, and accuracy, as well as their ability to target multiple genes at the same time. Years of research have firmly established miR-34 as a key tumor suppressor miRNA whose target genes are involved in drug resistance mechanisms. Indeed, numerous articles show that low levels of circulating miR-34 or tumor-specific miR-34 expression are associated with poor response to chemotherapy. In addition, elevation of inherently low miR-34 levels in resistant cancer cells effectively restores sensitivity to chemotherapeutic agents. Here, we review this literature, also highlighting some contradictory observations. In addition, we discuss the potential utility of miR-34 expression as a predictive biomarker for chemotherapeutic drug response. Although caution needs to be exercised, miR-34 is emerging as a biomarker that could improve cancer precision medicine.

TP53/miR-34a-associated signaling targets SERPINE1 expression in human pancreatic cancer

Pancreatic ductal adenocarcinoma (PDAC) is a disease of aging. The TP53 gene product regulates cell growth, aging, and cancer. To determine the important targets of TP53 in PDAC, we examined the expression of 440 proteins on a reverse phase protein array (RPPA) in PDAC-derived MIA-PaCa-2 cells which either had WT-TP53 or lacked WT-TP53. MIA-PaCa-2 cells have a TP53 mutation as well as mutant KRAS and represent a good in vitro model to study PDAC. RPPA analysis demonstrated expression of tumor promoting proteins in cells that lacked WT-TP53; and this feature could be reversed significantly when the cells were transfected with vector encoding WT-TP53 or treated with berberine or a modified berberine (BBR). Expression of miR-34a-associated signaling was elevated in cells expressing WT-TP53 compared to cells expressing mTP53. Results from in vivo studies using human PDAC specimens confirmed the in vitro results as the expression of miR-34a and associated signaling was significantly decreased in PDAC specimens compared to non-cancerous tissues. This study determined SERPINE1 as a miR-34a target with relevance to the biology of PDAC. Thus, we have identified a key target (SERPINE1) of the TP53/miR-34a axis that may serve as a potential biomarker for early detection of pancreatic cancer.

MicroRNAs as novel targets of sulforaphane in cancer therapy: The beginning of a new tale?

Effective management and treatment of cancer depend on developing novel antitumor drugs with the capability of targeting various molecular pathways. Identification and subsequent targeting of these pathways are of importance in cancer therapy. MicroRNAs (miRNAs) are small noncoding RNA molecules responsible for post-transcriptional regulation of genes. Notably, miRNAs participate in a number of biological processes such as proliferation, apoptosis, differentiation, and cell cycle regulation. So, any impairment in the expression and function of miRNAs is associated with development of disorders, particularly cancer. Naturally occurring nutraceutical compounds have attracted much attention due to their great antitumor activity. Among them, sulforaphane isolated from Brassica oleracea (broccoli) is of interest due to its therapeutic and biological activities such as antidiabetic, antioxidant, anti-inflammatory, hepatoprotection, and cardiprotection. Sulforaphane has demonstrated great antitumor activity and is able to significantly inhibit proliferation, viability, migration, malignancy, and epithelial-to-mesenchymal transition of cancer cells. These antitumor effects have widely been investigated, and it appears that there is a need for a precise review to demonstrate the molecular pathway that sulforaphane follows to exert its antitumor activity. At the present review, we focus on the modulatory impact of sulforaphane on miRNAs and exhibit that how various miRNAs in different cancers are regulated by sulforaphane.

Inflammation and DNA Methylation-Dependent Down-Regulation of miR-34b-5p Mediates c-MYC Expression and CRL4DCAF4 E3 Ligase Activity in Colitis-Associated Cancer

miRNAs, a well-known group of noncoding RNAs, contribute to the pathogenesis of multiple diseases, including colitis-associated cancer (CAC). Our recent findings indicate that proinflammatory cytokines up-regulate c-MYC level, which subsequently activates cullin 4A and 4B (CUL4A/4B) and CRL4^DCAF4 E3 ligases and promotes ubiquitination of suppression of tumorigenicity 7 in CAC. Herein, we identified and proved that miR-34b-5p can directly target c-MYC. In vitro oncogenic phenotype analyses and in vivo tumor formation assay indicated that miR-34b-5p overexpression could markedly decrease cell proliferation, colony formation, cell invasion, and tumor volumes. Overexpression of c-MYC in vitro could reverse the oncogenic phenotypes caused by miR-34b-5p up-regulation. In addition, the down-regulation of miR-34b-5p in CAC was dependent on the coregulation of the inflammatory microenvironment and DNA methylation. Collectively, our findings demonstrate that intracellular inflammation and DNA hypermethylation suppress miR-34b-5p expression, which limits its inhibitory effect on c-MYC and initiates the downstream events, including the induction of CRL4^DCAF4 E3 ligase activity. The activated CRL4^DCAF4 E3 ligase ubiquitinates suppression of tumorigenicity 7 and results in its degradation, eventually leading to the CAC tumorigenesis.

Triple negative breast cancer: A thorough review of biomarkers

Triple-negative breast cancer (TNBC) is defined as a type of breast cancer with lack of expression of estrogen receptor (ER), progesterone receptor (PR) and HER2 protein. The tumorigenesis is not likely to be driven by hormonal or HER2 pathway. In comparison to other types of breast cancer, TNBC stands out for its aggressive behavior, more prone to early recurrence. Historically, TNBC has been considered a disease with poor response to molecular target therapy, requiring better validation of biomarkers. Recent issues related to tumor heterogeneity have been widely discussed suggesting the subdivision of TNBC into different molecular subtypes. Through a complete research on the main published trials databases and platforms of ongoing clinical studies, the current manuscript was carried out in order to present a critical view of the role of immunohistochemical and molecular biomarkers for the prognosis and response prediction of TNBC to traditional therapy and new molecular target agents.

The Many Faces of Gene Regulation in Cancer: A Computational Oncogenomics Outlook

Cancer is a complex disease at many different levels. The molecular phenomenology of cancer is also quite rich. The mutational and genomic origins of cancer and their downstream effects on processes such as the reprogramming of the gene regulatory control and the molecular pathways depending on such control have been recognized as central to the characterization of the disease. More important though is the understanding of their causes, prognosis, and therapeutics. There is a multitude of factors associated with anomalous control of gene expression in cancer. Many of these factors are now amenable to be studied comprehensively by means of experiments based on diverse omic technologies. However, characterizing each dimension of the phenomenon individually has proven to fall short in presenting a clear picture of expression regulation as a whole. In this review article, we discuss some of the more relevant factors affecting gene expression control both, under normal conditions and in tumor settings. We describe the different omic approaches that we can use as well as the computational genomic analysis needed to track down these factors. Then we present theoretical and computational frameworks developed to integrate the amount of diverse information provided by such single-omic analyses. We contextualize this within a systems biology-based multi-omic regulation setting, aimed at better understanding the complex interplay of gene expression deregulation in cancer.

MicroRNA‑124 negatively regulates chloride intracellular channel 1 to suppress the migration and invasion of liver cancer cells

The dysregulation of microRNAs (miRNAs) is associated with the development and progression of a variety of cancers, including liver cancer. Aberrant expression of miRNA (miR)-124 has been demonstrated in liver cancer, but its functional mechanism in liver cancer is still largely unknown. Metastasis of liver cancer is one of the most common causes of mortality. The present study showed that miR-124 inhibited the proliferation, migration and invasion of liver cancer cells. Furthermore, chloride intracellular channel 1 (CLIC1) was identified as a novel target of miR-124 in liver cancer cells. Overexpression of miR-124 reduced CLIC1 expression at both the protein and mRNA levels in liver cancer cells. Downregulation of CLIC1 decreased the migration and invasion of liver cancer cells without affecting cell proliferation. Taken together, these results showed that CLIC1 is a critical target for miR-124-mediated inhibitory effects on cell migration and invasion. Thus, miR-124 or suppression of CLIC1 may have diagnostic value and therapeutic potential for the treatment of human liver cancer.

MicroRNAs in Bone Metastasis

PURPOSE OF REVIEW

This review provides an update on the recent literature describing the role of microRNAs (miRNAs) in cancer formation and bone metastasis. We confined our focus on osteosarcoma, breast cancer, prostate cancer, and epithelial-mesenchymal transition.

RECENT FINDINGS

In all areas covered, major discoveries on the role of miRNAs in tumorigenesis and metastasis have been made. Novel signaling networks were identified with miRNAs having a central function. Potential improvements in the diagnosis of malignant diseases and the long-term follow-up might become possible by the use of miRNAs. Furthermore, miRNAs also have disease-modifying properties and might emerge as a new class of therapeutic molecules. MiRNAs are novel and important regulators of multiple cellular and molecular events. Due to their functions, miRNAs might become useful to improve the diagnosis, follow-up and treatment of cancer, and metastases. Thus, miRNAs are molecules of great interest in translational medicine.

MiR-128-3p suppresses breast cancer cellular progression via targeting LIMK1

Breast cancer is the most common malignancy in women all over the world. MiRNAs are a type of small noncoding RNA that can regulate various cellular processes via binding different target genes in cancer cells. In this study, we found that miR-128-3p could suppress cellular proliferation and motility abilities of breast cancer. In addition, we found that overexpression of miR-128-3p arrested breast cancer cells in G0/G1 phase by affecting expression of CDK4/CDK6/Cyclin D1 and CDK2/Cyclin E1. Furthermore, we confirmed that LIM domain kinase 1 (LIMK1) is a direct target gene of miR-128-3p and that overexpression of miR-128-3p could suppress the expression levels of LIMK1 and Cofilin 1, which is downstream of LIMK1. TCGA clinical database showed that miR-128-3p was highly expressed in breast cancer patients and that high expression of miR-128-3p indicates a better prognosis of breast cancer. Our findings demonstrated that miR-128-3p could regulate cellular progression of breast cancer via regulating the LIMK1/CFL1 signaling pathway, and this new avenue could broaden existing versions of molecular mechanisms in breast cancer and perhaps represent potential novel direction of breast cancer treatment in the future.

Roles of MicroRNA-34a in Epithelial to Mesenchymal Transition, Competing Endogenous RNA Sponging and Its Therapeutic Potential

MicroRNA-34a (miR-34a), a tumor suppressor, has been reported to be dysregulated in various human cancers. MiR-34a is involves in certain epithelial-mesenchymal transition (EMT)-associated signal pathways to repress tumorigenesis, cancer progression, and metastasis. Due to the particularity of miR-34 family in tumor-associated EMT, the significance of miR-34a is being increasingly recognized. Competing endogenous RNA (ceRNA) is a novel concept involving mRNA, circular RNA, pseudogene transcript, and long noncoding RNA regulating each other’s expressions using microRNA response elements to compete for the binding of microRNAs. Studies showed that miR-34a is efficient for cancer therapy. Here, we provide an overview of the function of miR-34a in tumor-associated EMT. ceRNA hypothesis plays an important role in miR-34a regulation in EMT, cancer progression, and metastasis. Its potential roles and challenges as a microRNA therapeutic candidate are discussed. As the negative effect on cancer progression, miR-34a should play crucial roles in clinical diagnosis and cancer therapy.

MicroRNA-34 family: a potential tumor suppressor and therapeutic candidate in cancer

MicroRNA-34 (miR-34) has been reported to be dysregulated in various human cancers and regarded as a tumor suppressive microRNA because of its synergistic effect with the well-known tumor suppressor p53. Along with the application of MRX34, the first tumor-targeted microRNA drug which based on miR-34a mimics, on phase I clinical trial (NCT01829971), the significance of miR-34 is increasingly recognized. miR-34 plays a crucial role on repressing tumor progression by involving in epithelial-mesenchymal transition (EMT) via EMT- transcription factors, p53 and some important signal pathways. Not only that, numerous preclinical researches revealed the giant potential of miR-34a on cancer therapy through diversiform nano-scaled delivery systems. Here, we provide an overview about the function of miR-34 in various cancers and the mechanism of miR-34 in tumor-associated EMT. Furthermore, its potential role as a microRNA therapeutic candidate is also discussed. Notwithstanding some obstacles existed, the extensive application prospect of miR-34 on oncotherapy cannot be neglected.