Fine-tuning miR-21 expression and inhibition of EMT in breast cancer cells using aromatic-neomycin derivatives

MicroRNAs (miRs) are a class of endogenously expressed non-coding RNAs that negatively regulate gene expression within cells and participate in maintaining cellular homeostasis. By targeting 3' UTRs of target genes, individual miRs can control a wide array of gene expressions. Previous research has shed light upon the fact that aberrantly expressed miRs within cells can pertain to diseased conditions, such as cancer. Malignancies caused due to miRs are because of the high expression of onco-miRs or feeble expression of tumor-suppressing miRs. Studies have also shown miRs to engage in epithelial to mesenchymal transition (EMT), which allows cancer cells to become more invasive and metastasize. miR-21 is an onco-miR highly expressed in breast cancer cells and targets protein PTEN, which abrogates EMT. Therefore, we discuss an approach where in-house-developed peptidic amino sugar molecules have been used to target pre-miR-21 to inhibit miR-21 biogenesis, and hence antagonize its tumor-causing effect and inhibit EMT. Our study shows that small-molecule-based fine-tuning of miR expression can cause genotypic as well as phenotypic changes and also reinstates the potential and importance of nucleic acid therapeutics.

miR-4721, Induced by EBV-miR-BART22, Targets GSK3β to Enhance the Tumorigenic Capacity of NPC through the WNT/β-catenin Pathway

Nasopharyngeal carcinoma (NPC) is prevalent in East and Southeast Asia. In a previous study, Epstein-Barr virus (EBV)-miR-BART22 induces tumor metastasis and stemness and is significantly involved in NPC progression. In the present study, we observed that miR-4721 is induced by EBV-miR-BART22 through phosphatidylinositol 3-kinase (PI3K)/AKT/c-JUN/Sp1 signaling to promote its transcription. In a subsequent study, we observed that miR-4721 serves as a potential oncogenic factor promoting NPC cell cycle progression and cell proliferation in vitro and in vivo. Mechanism analysis indicated that miR-4721 directly targetes GSK3β and reduces its expression, which therefore elevates β-catenin intra-nuclear aggregation and activates its downstream cell cycle factors, including CCND1 and c-MYC. In clinical samples, miR-4721 and GSK3β are respectively observed to be upregulated and downregulated in NPC progression. Elevated expression of miR-4721 is positively associated with clinical progression and poor prognosis. Our study first demonstrated that miR-4721 as an oncogene is induced by EBV-miR-BART22 via modulating PI3K/AKT/c-JUN/Sp1 signaling to target GSK3β, which thus activates the WNT/β-catenin-stimulated cell cycle signal and enhances the tumorigenic capacity in NPC. miR-4721 may be a potential biomarker or therapeutic target in NPC treatment in the future.

MicroRNAs in prostate cancer: From function to biomarker discovery

MicroRNAs (miRNAs) are a small functional non-coding RNAs that post-transcriptionally regulate gene expression through mRNA degradation or translational repression. miRNAs are key regulatory components of various cellular networks. Current evidence support that multiple mammalian genome-encoded miRNAs impact the cellular biology, including proliferation, apoptosis, differentiation, and tumorigenesis, by targeting specific subsets of mRNAs. This minireview is focused on the current themes underlying the interactions between miRNAs and their mRNA targets and pathways in prostate tumorigenesis and progression, and their potential clinical utility as biomarkers for prostate cancer. Impact statement The primary goal of this article was to review recent literature on miRNA biogenesis and further elaborate on the identity of newly discovered miRNAs and their potential functional significance in the complex biological network associated with prostate tumorigenesis and disease progression and as biomarkers for prostate cancer.

The "Macro" World of microRNAs in Hepatocellular Carcinoma

Hepatotropic viruses such as hepatitis B virus (HBV) and hepatitis C virus (HCV) are the major etiological agents associated with development of hepatocellular carcinoma (HCC). Progression of HCC is a multistep process that requires sequential or parallel deregulation of oncogenic and tumor suppressive pathways leading to chromosomal instability and neoplastic phenotype. In the recent years, microRNAs (miRNAs) have carved their own niche alongside oncogenes and tumor suppressors, owing to their innate ability to receive and relay multiple signals. Not surprisingly, miRNAs are fast emerging as central player in myriads of malignancies including HCC. miRNAs are reported to participate in initiation and progression of HCC, and have also been clinically correlated with risk assessment, disease grade, aggressiveness, and prognosis. Despite extensive data available on the role of miRNAs in HCC, there is a pressing need to integrate and evaluate these datasets to find its correlation, if any, with causal agents in order to devise novel interventional modalities. Through this review, we attempt to bridge the gap by consolidating the current knowledge and concepts in the field of HCC-related miRNAs with special emphasis on HBV and HCV. Further, we assess the potential of common as well as unique signatures that may be useful in developing novel biomarkers and therapeutics.