MicroRNA-485-5p reduces O-GlcNAcylation of Bmi-1 and inhibits colorectal cancer proliferation

Opportunities for Therapeutic Modulation of O-GlcNAc

O-Linked β-N-acetylglucosamine (O-GlcNAc) is an essential, dynamic monosaccharide post-translational modification (PTM) found on serine and threonine residues of thousands of nucleocytoplasmic proteins. The installation and removal of O-GlcNAc is controlled by a single pair of enzymes, O-GlcNAc transferase (OGT) and O-GlcNAcase (OGA), respectively. Since its discovery four decades ago, O-GlcNAc has been found on diverse classes of proteins, playing important functional roles in many cellular processes. Dysregulation of O-GlcNAc homeostasis has been implicated in the pathogenesis of disease, including neurodegeneration, X-linked intellectual disability (XLID), cancer, diabetes, and immunological disorders. These foundational studies of O-GlcNAc in disease biology have motivated efforts to target O-GlcNAc therapeutically, with multiple clinical candidates under evaluation. In this review, we describe the characterization and biochemistry of OGT and OGA, cellular O-GlcNAc regulation, development of OGT and OGA inhibitors, O-GlcNAc in pathophysiology, clinical progress of O-GlcNAc modulators, and emerging opportunities for targeting O-GlcNAc. This comprehensive resource should motivate further study into O-GlcNAc function and inspire strategies for therapeutic modulation of O-GlcNAc.

O-GlcNAcylation in cancer development and immunotherapy

O-linked β-D-N-acetylglucosamine (O-GlcNAc), as a posttranslational modification (PTM), is a reversible reaction that attaches β-N-GlcNAc to Ser/Thr residues on specific proteins by O-GlcNAc transferase (OGT). O-GlcNAcase (OGA) removes the O-GlcNAc from O-GlcNAcylated proteins. O-GlcNAcylation regulates numerous cellular processes, including signal transduction, the cell cycle, metabolism, and energy homeostasis. Dysregulation of O-GlcNAcylation contributes to the development of various diseases, including cancers. Accumulating evidence has revealed that higher expression levels of OGT and hyper-O-GlcNAcylation are detected in many cancer types and governs glucose metabolism, proliferation, metastasis, invasion, angiogenesis, migration and drug resistance. In this review, we describe the biological functions and molecular mechanisms of OGT- or O-GlcNAcylation-mediated tumorigenesis. Moreover, we discuss the potential role of O-GlcNAcylation in tumor immunotherapy. Furthermore, we highlight that compounds can target O-GlcNAcylation by regulating OGT to suppress oncogenesis. Taken together, targeting protein O-GlcNAcylation might be a promising strategy for the treatment of human malignancies.

The Crucial Roles of Bmi-1 in Cancer: Implications in Pathogenesis, Metastasis, Drug Resistance, and Targeted Therapies

B-cell-specific Moloney murine leukemia virus integration region 1 (Bmi-1, also known as RNF51 or PCGF4) is one of the important members of the PcG gene family, and is involved in regulating cell proliferation, differentiation and senescence, and maintaining the self-renewal of stem cells. Many studies in recent years have emphasized the role of Bmi-1 in the occurrence and development of tumors. In fact, Bmi-1 has multiple functions in cancer biology and is closely related to many classical molecules, including Akt, c-MYC, Pten, etc. This review summarizes the regulatory mechanisms of Bmi-1 in multiple pathways, and the interaction of Bmi-1 with noncoding RNAs. In particular, we focus on the pathological processes of Bmi-1 in cancer, and explore the clinical relevance of Bmi-1 in cancer biomarkers and prognosis, as well as its implications for chemoresistance and radioresistance. In conclusion, we summarize the role of Bmi-1 in tumor progression, reveal the pathophysiological process and molecular mechanism of Bmi-1 in tumors, and provide useful information for tumor diagnosis, treatment, and prognosis.

LncRNA CASC21 induces HGH1 to mediate colorectal cancer cell proliferation, migration, EMT and stemness

Colorectal cancer (CRC) is one of the leading causes of cancer-related deaths worldwide. Long non-coding RNAs (lncRNAs) have been increasingly reported to serve vital parts in malignancies including CRC. Although cancer susceptibility 21 (CASC21) has been uncovered to play a part in CRC, its mechanism still needs further explanation. Thus, our study aimed to further explore the influence and mechanism of CASC21 in CRC progression. Quantitative real-time RT-PCR and western blot were performed to detect gene expression; a series of functional assays were performed to investigate the effect of CASC21 on CRC cells; in vivo tumour growth was evaluated via the nude mice xenograft model. The results revealed that CASC21 facilitated CRC cell proliferation, migration, epithelial-mesenchymal transition (EMT) and stemness. In addition, CASC21 was co-expressed with and bound to transcription factor POU5F1B (POU class 5 homeobox 1B). CASC21 recruited POU5F1B to HGH1 promoter to activate the transcription of HGH1 homolog. Also, CASC21 served as a competitive endogenous RNA (ceRNA) to up-regulate HGH1 via endogenously sponging miR-485-5p. Moreover, HGH1 overexpression counteracted the suppression of CASC21 deficiency on CRC tumour growth. In summary, our study indicated that CASC21 enhanced the expression of HGH1 to promote the malignancy of CRC by recruiting POU5F1B and sponging miR-485-5p, suggesting a key role of CASC21 in CRC progression.

RHPN1‑AS1 promotes ovarian carcinogenesis by sponging miR‑485‑5p and releasing TPX2 mRNA

Long non-coding RNAs (lncRNAs) play a crucial role in cancer development. However, researchers have yet to identify the underlying association between lncRNAs and ovarian cancer (OC). The aim of the present study was to examine the effect of lncRNA RHPN1-AS1 (RHPN1-AS1) on OC cells and tissues. Reverse transcriptase-quantitative PCR (RT-qPCR) was utilized to quantify RHPN1-AS1, miR-485-5p, and TPX2 mRNA expression in samples with OC. Luciferase-reporter assay, RNA immunoprecipitation (RIP) assay, and RNA pull-down assay were then employed to validate the target relationship among RHPN1-AS1, miR-485-5p and TPX2. Cell Counting Kit-8, BrdU, wound-healing, cell-adhesion, and flow cytometry assays were also employed to assess cell viability, proliferation, migration, adhesion and apoptosis, respectively, in SKOV3 and OVCAR3 cell lines. Findings revealed that RHPN1-AS1 demonstrated a higher expression level in OC cell lines and tissues. In addition, RHPN1-AS1 enhanced the adhesion, proliferation and migration of OC cell lines but decreased apoptosis of OC cells. It was also observed that the relationship between RHPN1-AS1 and miR-485-5p was negative and that RHPN1-AS1 could sponge miR-485-5p to regulate the proliferation, apoptosis, adhesion, and migration abilities of OC cells. Moreover, TPX2 was targeted by miR-485-5p and was significantly overexpressed in OC cell lines and tissues. Experimental investigations also revealed that TPX2 promoted the proliferation, adhesion, and migration of OC cells but suppressed the apoptosis of SKOV3 and OVCAR3 cells. In summary, RHPN1-AS1 played a tumor promotive role by sponging miR-485-5p to increase TPX2 expression in OC tumorigenesis.

MicroRNA‑485‑5p suppresses the progression of esophageal squamous cell carcinoma by targeting flotillin‑1 and inhibits the epithelial‑mesenchymal transition

As esophageal squamous cell carcinoma (ESCC) is one of the most frequently diagnosed cancers in Asia, it is crucial to uncover its underlying molecular mechanisms that support its development and progression. Several articles have reported that microRNA (miR)-485-5p inhibits the malignant phenotype in a number of cancer types, such as lung, gastric and breast cancer, but to the best of our knowledge, its function in ESCC has not been studied in depth until the present study. It is of great significance to probe the regulatory action and underlying mechanism of miR-485-5p in ESCC. In brief, this study identified that miR-485-5p expression in ESCC tissues was significantly lower than that in normal tissues. The decrease in miR-485-5p expression was associated with a larger tumour size and poor histology and stage. The expression of miR-485-5p was relatively high in Eca 109 and TE-1 cells, but relatively low in KYSE 30. The overexpression of miR-485-5p inhibited cell proliferation, migration and invasion in vitro, whereas miR-485-5p knockdown did the opposite. Flotillin-1 (FLOT-1) can facilitate the malignant phenotype in various cancer types. The present study found that in ESCC tissue, the protein expression of FLOT-1 was negatively correlated with miR-485-5p expression. Further experiments showed that miR-485-5p directly targeted the 3′-untranslated region of FLOT-1. The overexpression of miR-485-5p significantly suppressed the mRNA and protein expression levels of FLOT-1, whereas knockdown had the reverse effects. Furthermore, overexpression of miR-485-5p restrained epithelial-mesenchymal metastasis (EMT)-related factors at both the mRNA and protein levels. At the same time, it also inhibited the growth of ESCC and restrained the EMT in vivo. In summary, miR-485-5p was found to be an inhibitor of ESCC and may have potential as a novel target candidate for ESCC treatment.

Epigenetic Regulation of Glycosylation in Cancer and Other Diseases

In the last few decades, the newly emerging field of epigenetic regulation of glycosylation acquired more importance because it is unraveling physiological and pathological mechanisms related to glycan functions. Glycosylation is a complex process in which proteins and lipids are modified by the attachment of monosaccharides. The main actors in this kind of modification are the glycoenzymes, which are translated from glycosylation-related genes (or glycogenes). The expression of glycogenes is regulated by transcription factors and epigenetic mechanisms (mainly DNA methylation, histone acetylation and noncoding RNAs). This review focuses only on these last ones, in relation to cancer and other diseases, such as inflammatory bowel disease and IgA1 nephropathy. In fact, it is clear that a deeper knowledge in the fine-tuning of glycogenes is essential for acquiring new insights in the glycan field, especially if this could be useful for finding novel and personalized therapeutics.

Temozolomide modulates the expression of miRNAs in colorectal cancer

Cancer is the second leading cause of death globally, where nearly 1 in 6 deaths is due to cancer, with 70% of all deaths from cancer occur in low- and middle-income countries. The overall lifetime risk of developing colorectal cancer is 1 in 22 in men and 1 in 24 in women. In this work, we aimed to evaluate the role of temozolomide (TMZ) in controlling colon cancer cells (CRC) via regulating the miRnome. For this purpose, CRC cells (CaCo-2) were treated with 50 µM of TMZ for 48 h. Cell count using trypan test and cytotoxicity using 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl tetrazolium bromide (MTT) were carried out, and the obtained results indicated a significant decrease in cell count (p = 0.029), and in the cell viability (p = 0.0019). Cell cycle analysis was performed using flow cytometer, and results showed that TMZ arrested CRC cells at G2/M phase. A total of 84 miRNAs were profiled using real time PCR, and the results indicated that TMZ treatment upregulated 15 of 84 miRNAs panel profiled and downregulated the rest. The TMZ-upregulated/downregulated miRNAs were predicted to interact with many epigenetic-related proteins i.e., DNMTs, EZH2, and SUV31H1. This study shed some light on the role of TMZ in regulating the miRnome of CRC and hence in different types of cancers.

Sweet Control: MicroRNA Regulation of the Glycome

Glycosylation is a sophisticated informational system that controls specific biological functions at the cellular and organismal level. Dysregulation of glycosylation may underlie some of the most complex and common diseases of the modern era. In the past 5 years, microRNAs have come to the forefront as a critical regulator of the glycome. Herein, we review the current literature on miRNA regulation of glycosylation and how this work may point to a new way to identify the biological importance of glycosylation enzymes.

MiR-485-5p as a potential biomarker and tumor suppressor in human colorectal cancer

Aim: To investigate the role of miR-485-5p in colorectal cancer (CRC). Methodology: The level of miR-485-5p in serum and cell lines were measured by quantitative real-time polymerase chain reaction, and analyzed the diagnostic and prognostic value. Additionally, the biological effect of miR-485-5p on CRC cells was also explored in vitro. Results: The receiver operating characteristic (ROC) curves analysis revealed that miR-485-5p was a diagnostic candidate. Kaplan-Meier analyses demonstrated that patients with low serum miR-485-5p had shorter overall survival. In addition, the result of cox regression model indicated that miR-485-5p was not an independent risk factor for progression. Functional study revealed that overexpression of miR-485-5p could inhibit CRC cell proliferation, invasion and facilitates cell apoptosis. Conclusion: Our study revealed that miR-485-5p was a tumor suppressor and it could serve as a potential prognostic biomarker in CRC.

Long non-coding RNA LINC00707 acts as a competing endogenous RNA to enhance cell proliferation in colorectal cancer

Long non-coding RNAs (lncRNAs) have been indicated to serve critical roles in cancer development and progression. Long intergenic non-protein coding RNA 70 (LINC00707) was recently reported to be an oncogene involved in the tumorigenesis of several types of human cancer. However, the clinical role, biological functions and molecular mechanism of LINC00707 in colorectal cancer (CRC) remain unclear. The aim of the present study was to investigate the biological effects and mechanism of LINC00707 in CRC. Reverse transcription-quantitative PCR was used to detect the expression levels of LINC00707 in 65 CRC tissue samples and CRC cell lines (HCT116, HT29 and SW480). Cell Counting Kit-8 and colony formation assays were performed to investigate the effects of LINC00707 on CRC cell proliferation. A dual-luciferase reporter assay was conducted to investigate the mechanisms of LINC00707 in CRC. The upregulation of LINC00707 expression was significantly associated with tumor size, stage and poor survival in patients with CRC. LINC00707 also acted as an independent prognostic factor for CRC. Functional analyses revealed that the knockdown of LINC00707 could inhibit CRC cell proliferation. Furthermore, bioinformatics analysis demonstrated that microRNA (miR)-485-5p could directly bind to LINC00707, which was confirmed by a dual-luciferase reporter assay. In conclusion, the upregulation of LINC00707 is associated with a shorter survival time in patients with CRC. Knockdown of LINC00707 may inhibit the proliferation of CRC cells by binding with miR-485-5p.

A novel lncRNA-miRNA-mRNA network analysis identified the hub lncRNA RP11-159F24.1 in the pathogenesis of papillary thyroid cancer

Papillary thyroid cancer (PTC) is one of the most common cancers worldwide, and its carcinogenesis is influenced by a complex network of gene interactions. In this study, the microarray expression profile was re-annotated into a lncRNA-mRNA biphasic profile. LncRNA-mRNA interactions were confirmed by established miRNA-RNA data and hypergeometric test. Then, a PTC-related lncRNA-miRNA-mRNA network (PTCRN) was constructed by integrating differentially expressed genes with the RNA-RNA networks. The new network consisted of 21 lncRNAs, 241 mRNAs and 803 edges. To prioritize PTC-related genes, we performed topological analysis and random walk with restart (PWR) algorithm analysis of PTCRN. Both analyses identified lncRNA RP11-159F24.1 as a hub node in the network, which could interact with 47 mRNAs by sponging miR-485. In functional enrichment analysis, these interacting mRNAs were associated with the pathways in cancer. In validation, RP11-159F24.1 (up-regulated; P = 0.0013) showed an opposite expression pattern with its target miR-485 (down-regulated; P = 0.0013) in PTC, indicating that the RP11-159F24.1/miR-485/mRNAs axis might play an important role in the development of PTC. In conclusion, this study has constructed a PTC-related lncRNA-miRNA-mRNA network and identified the hub lncRNA RP11-159F24.1 in the tumorigenesis, which provided novel insights to explore the underlying mechanism of PTC.