miR-218 contributes to drug resistance in multiple myeloma via targeting LRRC28

Epigenetic Alterations as Vital Aspects of Bortezomib Molecular Action

Bortezomib (BTZ) is widely implemented in the treatment of multiple myeloma (MM). Its main mechanism of action is very well established. BTZ selectively and reversibly inhibits the 26S proteasome. More precisely, it interacts with the chymotryptic site of the 20S proteasome and therefore inhibits the degradation of proteins. This results in the intracellular accumulation of misfolded or otherwise defective proteins leading to growth inhibition and apoptosis. As well as interfering with the ubiquitin-proteasome complex, BTZ elicits various epigenetic alterations which contribute to its cytotoxic effects as well as to the development of BTZ resistance. In this review, we summarized the epigenetic alterations elicited by BTZ. We focused on modifications contributing to the mechanism of action, those mediating drug-resistance development, and epigenetic changes promoting the occurrence of peripheral neuropathy. In addition, there are therapeutic strategies which are specifically designed to target epigenetic changes. Herein, we also reviewed epigenetic agents which might enhance BTZ-related cytotoxicity or restore the sensitivity to BTZ of resistant clones. Finally, we highlighted putative future perspectives regarding the role of targeting epigenetic changes in patients exposed to BTZ.

Biological and therapeutic viewpoints towards role of miR-218 in human cancers: Revisiting molecular interactions and future clinical translations

Understanding the exact pathogenesis of cancer is difficult due to heterogenous nature of tumor cells and multiple factors that cause its initiation and development. Treatment of cancer is mainly based on surgical resection, chemotherapy, radiotherapy and their combination, while gene therapy has been emerged as a new kind of therapy for cancer. Post-transcriptional regulation of genes has been of interest in recent years and among various types of epigenetic factors that can modulate gene expression, short non-coding RNAs known as microRNAs (miRNAs) have obtained much attention. The stability of mRNA decreases by miRNAs to repress gene expression. miRNAs can regulate tumor malignancy and biological behavior of cancer cells and understanding their function in tumorigenesis can pave the way towards developing new therapeutics in future. One of the new emerging miRNAs in cancer therapy is miR-218 that increasing evidence highlights its anti-cancer activity, while a few studies demonstrate its oncogenic function. The miR-218 transfection is promising in reducing progression of tumor cells. miR-218 shows interactions with molecular mechanisms including apoptosis, autophagy, glycolysis and EMT, and the interaction is different. miR-218 induces apoptosis, while it suppresses glycolysis, cytoprotective autophagy and EMT. Low expression of miR-218 can result in development of chemoresistance and radio-resistance in tumor cells and direct targeting of miR-218 as a key player is promising in cancer therapy. LncRNAs and circRNAs are nonprotein coding transcripts that can regulate miR-218 expression in human cancers. Moreover, low expression level of miR-218 can be observed in human cancers such as brain, gastrointestinal and urological cancers that mediate poor prognosis and low survival rate.

Non-coding RNAs and exosomal ncRNAs in multiple myeloma: An emphasis on molecular pathways

One of the most common hematological malignancies is multiple myeloma (MM) that its mortality and morbidity have increased. The incidence rate of MM is suggested to be higher in Europe and various kinds of therapeutic strategies including stem cell transplantation. However, MM treatment is still challenging and gene therapy has been shown to be promising. The non-coding RNAs (ncRNAs) including miRNAs, lncRNAs and circRNAs are considered as key players in initiation, development and progression of MM. In the present review, the role of ncRNAs in MM progression and drug resistance is highlighted to provide new insights for future experiments for their targeting and treatment of MM. The miRNAs affect proliferation and invasion of MM cells, and targeting tumor-promoting miRNAs can induce apoptosis and cell cycle arrest, and reduces proliferation of MM cells. Furthermore, miRNA regulation is of importance for modulating metastasis and chemotherapy response of tumor cells. The lncRNAs exert the same function and determine proliferation, migration and therapy response of MM cells. Notably, lncRNAs mainly target miRNAs in regulating MM progression. The circRNAs also target different molecular pathways in regulating MM malignancy that miRNAs are the most well-known ones. Furthermore, clinical application of ncRNAs in MM is discussed.

CircATIC Contributes to Multiple Myeloma Progression via miR-324-5p-Dependent Regulation of HGF

Circular RNA (circRNA) 5-aminoimidazole-4-carboxamide ribonucleotide formyltransferase/IMP cyclohydrolase (circATIC; hsa_circ_0058058) was observed to be upregulated in multiple myeloma (MM) by former article. However, the function and exact mechanism of circATIC in MM development remain barely known. CircRNA-microRNA (miRNA)-messenger RNA (mRNA) axis was established through using bioinformatic databases (starbase, Circinteractome, and microT-CDS). Dual-luciferase reporter assay, RNA immunoprecipitation assay, and RNA-pull down assay were utilized to verify the target relationship between microRNA-324-5p (miR-324-5p) and circATIC or hepatocyte growth factor (HGF). CircATIC expression was upregulated in MM patients and cell lines. CircATIC interference notably hampered cell proliferation, migration, invasion, and glycolysis and induced cell apoptosis of MM cells. MiR-324-5p was a target of circATIC. CircATIC silencing-mediated effects in MM cells were largely overturned by the knockdown of miR-324-5p. HGF was a target of miR-324-5p, and circATIC upregulated the expression of HGF partly through sponging miR-324-5p in MM cells. MiR-324-5p suppressed the malignant behaviors of MM cells, which were largely counteracted by the overexpression of HGF in MM cells. CircATIC accelerated the proliferation, migration, invasion, and glycolysis and suppressed the apoptosis of MM cells through mediating miR-324-5p/HGF signaling.

MicroRNA-125a/b-5p promotes malignant behavior in multiple myeloma cells and xenograft tumor growth by targeting DIS3

Multiple myeloma (MM) is a hematological malignancy with a high prevalence and is characterized by the clonal expansion of malignant plasma cells. As a new tumor suppressor, defective in sister chromatid joining (DIS3) was reported to be a gene closely related to MM. This study elucidated the biological functions and underlying mechanisms of DIS3 in MM. DIS3 mRNA and protein levels were detected using RT-qPCR and western blotting, respectively. Methyl thiazolyl tetrazolium assays, flow cytometry analyses, Transwell assays, and wound healing assays were performed to detect the proliferation, apoptosis, invasion, and migration of MM cells. The binding relationship between miR-125a/b-5p and DIS3 was verified using luciferase reporter assays and RNA pulldown assays. Xenograft tumor models were established in nude mice to investigate the effects of miR-125a/b-5p and DIS3 on tumor growth in vivo. DIS3 levels were downregulated in MM cells, and DIS3 upregulation inhibited the malignant behaviors of MM cells. Mechanistically, miR-125a/b-5p directly targeted the 3' untranslated region of DIS3. The expression of miR-125a/b-5p was upregulated in MM cells, miR-125a/b-5p knockdown inhibited the malignant behaviors of MM cells, and the inhibitory effect was reversed by DIS3 downregulation. The results of in vivo experiments indicated that miR-125a/b-5p promoted tumor growth by downregulating DIS3. Overall, miR-125a/b-5p promotes MM cellular processes and xenograft tumor growth by targeting DIS3.

Significance of a tumor microenvironment-mediated P65-miR-30a-5p-BCL2L11 amplification loop in multiple myeloma

Despite significant progress in the treatment of myeloma, multiple myeloma (MM) remains an incurable hematological malignancy due to cell adhesion-mediated drug resistance (CAM-DR) phenotype. However, data on the molecular mechanisms underlying the CAM-DR remains scanty. Here, we identified a miRNA-mRNA regulatory network in myeloma cells that are directly adherent to bone marrow stromal cells (BMSCs). Our data showed that the BMSCs up-regulated miR-30a-5p and down-regulated BCL2L11 at both mRNA and protein level in the myeloma cells. Besides, luciferase reporter genes demonstrated direct interaction between miR-30a-5p and BCL2L11 gene. Moreover, the BMSCs activated NF-ΚB signaling pathway in myeloma cells and the NF-κB P65 was shown to directly bind the miR-30a-5p promoter region. Moreover, suppression of the miR-30a-5p or upregulation of the BCL2L11 promoted apoptosis of the myeloma cells independent of the BMSCs, thus suggesting clinical significance of miR-30a-5p inhibitor and PLBCL2L11 plasmid in CAM-DR. Together, our data demonstrated the role of P65-miR-30a-5p-BCL2L11 loop in CAM-DR myeloma cells. These findings give new insights into the role of tumor microenvironment in the treatment of patients with myeloma.

Advances in the Biological Functions and Mechanisms of miRNAs in the Development of Osteosarcoma

Osteosarcoma is one of the most common primary malignant bone tumors, mainly occurring in children and adolescents, and is characterized by high morbidity and poor prognosis. MicroRNAs, a class of noncoding RNAs consisting of 19 to 25 nucleotides, are involved in cell proliferation, invasion, metastasis, and apoptosis to regulate the development and progression of osteosarcoma. Studies have found that microRNAs are closely related to the diagnosis, treatment, and prognosis of osteosarcoma patients and have an important role in improving drug resistance in osteosarcoma. This paper reviews the role of microRNAs in the pathogenesis of osteosarcoma and their clinical value, aiming to provide a new research direction for diagnosing and treating osteosarcoma and achieving a better prognosis.

One Omics Approach Does Not Rule Them All: The Metabolome and the Epigenome Join Forces in Haematological Malignancies

Aberrant DNA methylation, dysregulation of chromatin-modifying enzymes, and microRNAs (miRNAs) play a crucial role in haematological malignancies. These epimutations, with an impact on chromatin accessibility and transcriptional output, are often associated with genomic instability and the emergence of drug resistance, disease progression, and poor survival. In order to exert their functions, epigenetic enzymes utilize cellular metabolites as co-factors and are highly dependent on their availability. By affecting the expression of metabolic enzymes, epigenetic modifiers may aid the generation of metabolite signatures that could be utilized as targets and biomarkers in cancer. This interdependency remains often neglected and poorly represented in studies, despite well-established methods to study the cellular metabolome. This review critically summarizes the current knowledge in the field to provide an integral picture of the interplay between epigenomic alterations and the cellular metabolome in haematological malignancies. Our recent findings defining a distinct metabolic signature upon response to enhancer of zeste homolog 2 (EZH2) inhibition in multiple myeloma (MM) highlight how a shift of preferred metabolic pathways may potentiate novel treatments. The suggested link between the epigenome and the metabolome in haematopoietic tumours holds promise for the use of metabolic signatures as possible biomarkers of response to treatment.

CircRERE confers the resistance of multiple myeloma to bortezomib depending on the regulation of CD47 by exerting the sponge effect on miR-152-3p

Background

Inevitable resistance to chemotherapeutic drugs has become a major obstacle for the clinical treatment of multiple myeloma (MM). Circular RNAs (circRNAs) can regulate the chemoresistance in different tumors. Our study was to explore the regulation of circRNA arginine-glutamic acid dipeptide repeats (circRERE) in bortezomib (BTZ) resistance of MM.

Methods

CircRERE, microRNA-152-3p (miR-152-3p) and cluster of differentiation 47 (CD47) levels were assayed through the quantitative real-time polymerase chain reaction (qRT-PCR). Cell sensitivity to BTZ was analyzed using Cell Counting Kit-8 (CCK-8) assay. Cell proliferation and apoptosis were determined via colony formation assay and flow cytometry, respectively. The detection of all proteins was conducted by western blot. The target binding was analyzed via the dual-luciferase reporter assay and RIP assay.

Results

We found the upregulation of circRERE in BTZ-resistant MM samples and cells. BTZ resistance was inhibited after circRERE expression was downregulated in MM cells. CircRERE was identified to act as a miR-152-3p sponge. The effect of circRERE on the BTZ resistance was associated with the sponge function for miR-152-3p. CD47 was a target for miR-152-3p and circRERE could sponge miR-152-3p to generate the expression regulation of CD47. MiR-152-3p facilitated the susceptibility of MM cells to BTZ by targeting CD47.

Conclusion

These results suggested that circRERE could suppress the BTZ resistance in MM cells by mediating the miR-152-3p/CD47 axis.