MiR-339 depresses cell proliferation via directly targeting S-phase kinase-associated protein 2 mRNA in lung cancer

SKping cell cycle regulation: role of ubiquitin ligase SKP2 in hematological malignancies

SKP2 (S-phase kinase-associated protein 2) is a member of the F-box family of substrate-recognition subunits in the SCF ubiquitin-protein ligase complexes. It is associated with ubiquitin-mediated degradation in the mammalian cell cycle components and other target proteins involved in cell cycle progression, signal transduction, and transcription. Being an oncogene in solid tumors and hematological malignancies, it is frequently associated with drug resistance and poor disease outcomes. In the current review, we discussed the novel role of SKP2 in different hematological malignancies. Further, we performed a limited in-silico analysis to establish the involvement of SKP2 in a few publicly available cancer datasets. Interestingly, our study identified Skp2 expression to be altered in a cancer-specific manner. While it was found to be overexpressed in several cancer types, few cancer showed a down-regulation in SKP2. Our review provides evidence for developing novel SKP2 inhibitors in hematological malignancies. We also investigated the effect of SKP2 status on survival and disease progression. In addition, the role of miRNA and its associated families in regulating Skp2 expression was explored. Subsequently, we predicted common miRNAs against Skp2 genes by using miRNA-predication tools. Finally, we discussed current approaches and future prospective approaches to target the Skp2 gene by using different drugs and miRNA-based therapeutics applications in translational research.

CIZ1 aggravates gastric cancer progression via mediating FBXL19-AS1 and miR-339-3p

Gastric cancer (GC) remains a prevalent malignancy with high morbidity and mortality. CDKN1A interacting zinc finger protein 1 (CIZ1) has been demonstrated to have oncogenic functions in the development of cancers. We detected CIZ1 expression via quantitative real-time PCR (RT-qPCR). The protein level of CIZ1 was measured through Western blot. We noticed that CIZ1 expression was markedly enhanced in GC cells. Furthermore, functional experiments including colony formation assay, EdU staining assay, transwell assay, TUNEL staining assay and flow cytometry analysis uncovered that CIZ1 silencing attenuated cell malignant phenotypes in GC. Through bioinformatics tools and mechanism assays, we explored the up-stream mechanism of CIZ1 and determined that CIZ1 was modulated by FBXL19 antisense RNA 1 (FBXL19-AS1) and microRNA-339-3p (miR-339-3p). Additionally, miR-339-3p exerted a negative role on GC development in vitro, and FBXL19-AS1 depletion also had the inhibitory impacts on the progression of GC in vitro. Eventually, the finding that CIZ1 overexpression reversed the effects of FBXL19-AS1 silencing on GC development was validated by rescue assays. In a word, CIZ1 functioned as a tumor promoter in GC, indicating that CIZ1 might be a promising target for GC treatment.

Reactivation of tumour suppressor in breast cancer by enhancer switching through NamiRNA network

Dysfunction of Tumour Suppressor Genes (TSGs) is a common feature in carcinogenesis. Epigenetic abnormalities including DNA hypermethylation or aberrant histone modifications in promoter regions have been described for interpreting TSG inactivation. However, in many instances, how TSGs are silenced in tumours are largely unknown. Given that miRNA with low expression in tumours is another recognized signature, we hypothesize that low expression of miRNA may reduce the activity of TSG related enhancers and further lead to inactivation of TSG during cancer development. Here, we reported that low expression of miRNA in cancer as a recognized signature leads to loss of function of TSGs in breast cancer. In 157 paired breast cancer and adjacent normal samples, tumour suppressor gene GPER1 and miR-339 are both downregulated in Luminal A/B and Triple Negative Breast Cancer subtypes. Mechanistic investigations revealed that miR-339 upregulates GPER1 expression in breast cancer cells by switching on the GPER1 enhancer, which can be blocked by enhancer deletion through the CRISPR/Cas9 system. Collectively, our findings reveal novel mechanistic insights into TSG dysfunction in cancer development, and provide evidence that reactivation of TSG by enhancer switching may be a promising alternative strategy for clinical breast cancer treatment.

Emerging Roles of SKP2 in Cancer Drug Resistance

More than half of all cancer patients receive chemotherapy, however, some of them easily acquire drug resistance. Resistance to chemotherapy has become a massive obstacle to achieve high rates of pathological complete response during cancer therapy. S-phase kinase-associated protein 2 (Skp2), as an E3 ligase, was found to be highly correlated with drug resistance and poor prognosis. In this review, we summarize the mechanisms that Skp2 confers to drug resistance, including the Akt-Skp2 feedback loop, Skp2-p27 pathway, cell cycle and mitosis regulation, EMT (epithelial-mesenchymal transition) property, enhanced DNA damage response and repair, etc. We also addressed novel molecules that either inhibit Skp2 expression or target Skp2-centered interactions, which might have vast potential for application in clinics and benefit cancer patients in the future.

Skp2 in the ubiquitin-proteasome system: A comprehensive review

The ubiquitin-proteasome system (UPS) is a complex process that regulates protein stability and activity by the sequential actions of E1, E2 and E3 enzymes to influence diverse aspects of eukaryotic cells. However, due to the diversity of proteins in cells, substrate selection is a highly critical part of the process. As a key player in UPS, E3 ubiquitin ligases recruit substrates for ubiquitination specifically. Among them, RING E3 ubiquitin ligases which are the most abundant E3 ubiquitin ligases contribute to diverse cellular processes. The multisubunit cullin-RING ligases (CRLs) are the largest family of RING E3 ubiquitin ligases with tremendous plasticity in substrate specificity and regulate a vast array of cellular functions. The F-box protein Skp2 is a component of CRL1 (the prototype of CRLs) which is expressed in many tissues and participates in multiple cellular functions such as cell proliferation, metabolism, and tumorigenesis by contributing to the ubiquitination and subsequent degradation of several specific tumor suppressors. Most importantly, Skp2 plays a pivotal role in a plethora of cancer-associated signaling pathways. It enhances cell growth, accelerates cell cycle progression, promotes migration and invasion, and inhibits cell apoptosis among others. Hence, targeting Skp2 may represent a novel and attractive strategy for the treatment of different human cancers overexpressing this oncogene. In this review article, we summarized the known roles of Skp2 both in health and disease states in relation to the UPS.

miRNAs and lncRNAs in Echinococcus and Echinococcosis

Echinococcosis are considered to be potentially lethal zoonotic diseases that cause serious damage to hosts. The metacestode of Echinococcus multilocularis and E. granulosus can result in causing the alveolar and cystic echinococcoses, respectively. Recent studies have shown that non-coding RNAs are widely expressed in Echinococcus spp. and hosts. In this review, the two main types of non-coding RNAs—long non-coding RNAs (lncRNAs) and microRNAs (miRNAs)—and the wide-scale involvement of these molecules in these parasites and their hosts were discussed. The expression pattern of miRNAs in Echinococcus spp. is species- and developmental stage-specific. Furthermore, common miRNAs were detected in three Echinococcus spp. and their intermediate hosts. Here, we primarily focus on recent insights from transcriptome studies, the expression patterns of miRNAs and lncRNAs, and miRNA-related databases and techniques that are used to investigate miRNAs in Echinococcus and echinococcosis. This review provides new avenues for screening therapeutic and diagnostic markers.

miRNA-339-5p Plays an Important Role in Invasion and Migration of Pancreatic Cancer Cells

BACKGROUND This study aimed to investigate the role of miRNA-339-5p in pancreatic cancer cell invasion and migration. MATERIAL AND METHODS The differences between exosomal miRNAs of PANC02 and PANC02-H7 were studied by microarray analysis. We measured miRNA-339-5p expression in different groups; differences in cell invasion and migration were evaluated using the Transwell and wound healing assays and expression of relative proteins (E-cadherin, vimentin and ZNF689) was measured by WB assay. The correlation between miRNA-339-5p and ZNF689 expression was evaluated by luciferase reporter gene assay. RESULTS Compared with PANC02 exosome, microarray analysis indicated that miRNA-339-5p mRNA expression was significantly suppressed (P<0.001) in the PANC02-H7 exosome. Supplementation with miR-339-5p mimics led to a significant decrease in the invasion cell number and wound healing rate (P<0.001), with significantly enhanced E-cadherin expression and suppressed vimentin expression (P<0.001). However, transfection of a miR-339-5p inhibitor led to a significant increase in the invasion cell number and wound healing rate (P<0.001), with significantly suppressed E-cadherin expression and increased vimentin expression (P<0.001). Luciferase reporter gene assay demonstrated ZNF689 gene to be the target of miR-339-5p in the PANC02-H7 cell. With miR-339-5p and ZNF689 transfection, the invasion cell number and wound healing rate were significantly increased compared with those in the miR-339-5p group (P<0.001), with significantly increased expression of ZNF689 and vimentin and suppressed E-cadherin expression (P<0.001). CONCLUSIONS miR-339-5p suppresses the invasion and migration of pancreatic cancer cells via direct regulation of ZNF689 in vitro.

MicroRNA-339 inhibits human hepatocellular carcinoma proliferation and invasion via targeting ZNF689

Background

Hepatocellular carcinoma (HCC) is the second leading cause of cancer mortality worldwide, however, the prognosis for HCC remains unsatisfactory. This study aimed to explore the role of miR-339-5p in HCC.

Methods

We first used quantitative real-time PCR to examine the level of miR-339-5p in HCC tissues. Then we further adopted Western blotting assay, CCK8, cell invasion assays, apoptosis detection assay, and luciferase assay to analyze how it mediate the development of HCC.

Results

We found that miR-339 is significantly decreased in primary HCC tissues. Overexpression of miR-339 in HCC cells remarkably suppressed proliferation and invasion and induced apoptosis. However, silencing miR-339 in HCC cells promoted proliferation and invasion, and reduced apoptosis. Moreover, we demonstrated that ZNF689 is a target of miR-339 and there is a negative correlation between miR-339 and ZNF689 expression in the HCC tissues. Overexpression of ZNF689 in miR-339-overexpressing HCC cells partially antagonized the inhibitory effects of miR-339.

Conclusion

Our study revealed that miR-339 inhibits HCC growth through targeting oncoprotein ZNF689 and restoration of miR-339 might be feasible therapeutic strategy for HCC treatment.

MicroRNA‑339‑5p inhibits cell proliferation of acute myeloid leukaemia by directly targeting SOX4

In recent decades, microRNAs (miRNAs) have been considered novel gene regulators. Dysregulated miRNAs serve crucial roles in the formation and progression of acute myeloid leukaemia (AML). Therefore, the roles of differentially expressed miRNAs in AML require extensive investigation to obtain insight into the treatment of patients with AML. The present study demonstrated significant miR‑339‑5p downregulation in AML samples and cell lines. miR‑339‑5p overexpression attenuated AML cell proliferation by inducing cell cycle arrest and promoting cell apoptosis. Additionally, sex‑determining region Y‑related high‑mobility group box 4 (SOX4) was identified as a direct target gene of miR‑339‑5p in AML. Furthermore, SOX4 expression was significantly upregulated in AML samples; this upregulation was inversely correlated with the expression levels of miR‑339‑5p. Additionally, a series of rescue experiments demonstrated that SOX4 resumption reversed the effects of miR‑339‑5p overexpression on cell proliferation, cycle status and apoptosis of AML. In conclusion, miR‑339‑5p may serve its antiproliferative role in AML by directly targeting SOX4, which suggests that miR‑339‑5p may be considered an effective novel therapeutic target for treating patients with such an aggressive haematological malignancy.