miR-520g and miR-520h overcome bortezomib resistance in multiple myeloma via suppressing APE1

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.

Circ_0091537 promotes gefitinib chemoresistance in non-small cell lung cancer by mediating the miR-520h/YAP1 network

Chemoresistance is the leading cause of poor outcomes of non-small cell lung cancer (NSCLC). Circular RNA (circRNA) plays a vital role in NSCLC resistance progression. Our study aimed to uncover the role of circRNA PDZ domain containing 8 (circ_0091537) in NSCLC with gefitinib resistance. The expression of circ_0091537, microRNA-520h (miR-520h), and Yes-associated protein 1 (YAP1) mRNA were detected using quantitative real-time PCR. Cell viability and cell proliferation were assessed by MTT assay and colony formation assay. Colony formation ability was detected by colony formation assay. Cell cycle distribution and cell apoptosis were determined by flow cytometry assay. Cell migration and cell invasion were detected by transwell assay. The potential relationship between miR-520h and circ_0091537 or YAP1 was verified by dual-luciferase reporter assay. Tumor formation assay in nude mice was performed to test the role of circ_0091537 in vivo . Circ_0091537 and YAP1 were upregulated, while miR-520h was downregulated in gefitinib-resistant NSCLC cells. Circ_0091537 knockdown inhibited gefitinib resistance in NSCLC cells and then inhibited NSCLC cell growth, migration, and invasion. MiR-520h was a target of circ_0091537, and miR-520h inhibition reversed the effects of circ_0091537 knockdown. Moreover, YAP1 was a target of miR-520h, and circ_0091537 competitively combined with miR-520h to enrich YAP1 expression. MiR-520h restoration impaired gefitinib resistance and suppressed NSCLC cell proliferation, migration, and invasion by repressing YAP1. Circ_0091537 overexpression weakened gefitinib sensitivity in vivo to promote tumor growth. Circ_0091537 strengthens gefitinib chemoresistance to promote NSCLC progression by mediating the miR-520h/YAP1 network, suggesting that circ_0091537 may be a key indicator in resistance to treatment of NSCLC.

Circular RNA circ_SKA3 enhances gastric cancer development by targeting miR-520h

PURPOSE

To explore the mechanisms of action of circ_SKA3 in gastric cancer (GC), which are still not fully understood.

METHODS

Subcellular localization assay was used to analyze the localization of circ_SKA3, and Actinomycin D assay was applied to confirm the stability of circ_SKA3. The levels of circ_SKA3, microRNA (miR)-520h, and cell division cycle 42 (CDC42) mRNA were gauged by quantitative real-time polymerase chain reaction (qRT-PCR). The protein levels of CDC42 and proliferating cell nuclear antigen (PCNA) were assessed by western blot. Cell proliferation, colony formation, cell cycle distribution, apoptosis, migration, and invasion were detected by 3-[4,5-dimethylthiazol-2-yl]-2, 5-diphenyltetrazolium bromide (MTT), 5-Ethynyl-2'-Deoxyuridine (EdU) incorporation, colony formation, flow cytometry, and transwell assays, respectively. Directed relationship between miR-520h and circ_SKA3 or CDC42 was verified by a dual-luciferase reporter assay. Mouse xenograft experiments were used to elucidate the impact of circ_SKA3 in vivo.

RESULTS

Overexpression of circ_SKA3 was validated in GC tissues and cells. The down-regulation of circ_SKA3 suppressed proliferation, cell cycle progression, colony formation, migration, invasion, and promoted cell apoptosis in vitro, as well as weakening tumor growth in vivo. Circ_SKA3 directly bound to miR-520h, and circ_SKA3 regulated CDC42 expression through miR-520h. Circ_SKA3 exerted regulatory effects on GC cell behaviors by inhibiting miR-520h. Furthermore, CDC42 was a functional target of miR-520h in regulating GC cell behaviors.

CONCLUSION

Our findings established a strong molecular mechanism, the miR-520h/CDC42 axis, at least in part, for the oncogenic role of circ_SKA3 in GC.

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.

Circulating miR-448 acts as a potential diagnostic biomarker for multiple myeloma

OBJECTIVE

The current diagnostic methods for multiple myeloma (MM) include bone marrow aspiration and biopsy, which are not only complicated but also invasive, causing great pain to patients. Micro ribonucleotides (miRNA) exist stably in circulating plasma and could be easily detected, making them promising specific diagnostic markers for MM.

METHODS

The expression of plasma miR-448 in MM patients was detected by real-time quantitative PCR analysis. Spearman correlation was used to analyze correlations between miR-448 expression and various clinic pathological characteristics of MM patients. The ROC and the AUC (95% confidence interval) were exploited to evaluate the potential of miR-448 acting as a diagnostic marker for MM patients.

RESULTS AND DISCUSSION

In this study, we found that the expression level of miR-448 in patients with MM was significantly higher than that in normal people and showed statistically differential expression in different stages of MM. Besides, we observed that the abundance of miR-448 in the plasma of newly diagnosed MM patients was positively correlated with the proportion of plasma cells (PC) in the bone marrow and the concentration of serum M protein (MP), respectively. In addition, ROC analysis demonstrated the sensitivity and specificity of the diagnostic value of miR-448 for MM are 92.90% and 87.50%, respectively.

CONCLUSION

Taken together, these results indicated that miR-448 may serve as a potential molecular diagnostic marker for MM.

APE1 shRNA-loaded cancer stem cell-derived extracellular vesicles reverse Erlotinib resistance in non-small cell lung cancer via the IL-6/STAT3 signalling

OBJECTIVE

Apurinic endonuclease 1 (APE1) has been suggested as an oncogene of lung tumours and our bioinformatics analysis identified the association between Erlotinib resistance and interleukin-6 (IL-6). Thus, we performed this work to delineate the mechanistic actions of APE1/IL-6 signalling in Erlotinib resistance of non-small cell lung cancer (NSCLC).

METHODS

We selected human NSCLC cell lines HCC827 and PC9 to establish Erlotinib-resistant HCC827R and PC9R cells. Cancer stem cells (CSCs) were isolated from Erlotinib-sensitive HCC827P and PC9P cells (PCSCs) and from HCC827R and PC9R cells (RCSCs). Further, extracellular vesicles (EVs) were separated from PCSCs (PCSC-EVs) and RCSCs (RCSC-EVs) and co-cultured with RCSCs with or without short hairpin RNA (shRNA)-targeting APE1 (APE1 shRNA) transduction. In addition, functional assays were conducted to determine the effect of APE1 shRNA on malignant phenotypes of cancer cells in vitro and in vivo and the activation of IL-6/STAT3 signalling.

RESULTS

It was found that NSCLC cells could internalize both RCSC-EVs and PCSC-EVs. RCSC-EVs augmented the resistance of NSCLC cells to Erlotinib. The overexpression of APE1 occurred in NSCLC tissues, and IL-6 was enriched in serum samples of patients with NSCLC. APE1 shRNA was demonstrated to restrict the Erlotinib resistance of NSCLC cells by inactivating the IL-6/STAT3 signalling. Additionally, shAPE1-loaded RCSC-EVs suppressed the Erlotinib resistance of NSCLC via the IL-6/STAT3 axis both in vitro and in vivo, as reflected by impeded malignant phenotypes and xenograft tumour formation.

CONCLUSIONS

Collectively, these data indicate that APE1 confers Erlotinib resistance by activating the IL-6/STAT3 signalling, suggesting targeting APE1 as a possible therapeutic target in Erlotinib-resistant NSCLC.

Pharmacological inhibition of Ref-1 enhances the therapeutic sensitivity of papillary thyroid carcinoma to vemurafenib

The use of the BRAF inhibitor vemurafenib exhibits drug resistance in the treatment of thyroid cancer (TC), and finding more effective multitarget combination therapies may be an important solution. In the present study, we found strong correlations between Ref-1 high expression and BRAF mutation, lymph node metastasis, and TNM stage. The oxidative stress environment induced by structural activation of BRAF upregulates the expression of Ref-1, which caused intrinsic resistance of PTC to vemurafenib. Combination inhibition of the Ref-1 redox function and BRAF could enhance the antitumor effects of vemurafenib, which was achieved by blocking the action of Ref-1 on BRAF proteins. Furthermore, combination treatment could cause an overload of autophagic flux via excessive AMPK protein activation, causing cell senescence and cell death in vitro. And combined administration of Ref-1 and vemurafenib in vivo suppressed PTC cell growth and metastasis in a cell-based lung metastatic tumor model and xenogeneic subcutaneous tumor model. Collectively, our study provides evidence that Ref-1 upregulation via constitutive activation of BRAF in PTC contributes to intrinsic resistance to vemurafenib. Combined treatment with a Ref-1 redox inhibitor and a BRAF inhibitor could make PTC more sensitive to vemurafenib and enhance the antitumor effects of vemurafenib by further inhibiting the MAPK pathway and activating the excessive autophagy and related senescence process.

MicroRNA Alterations Induced in Human Skin by Diesel Fumes, Ozone, and UV Radiation

Epigenetic alterations are a driving force of the carcinogenesis process. MicroRNAs play a role in silencing mutated oncogenes, thus defending the cell against the adverse consequences of genotoxic damages induced by environmental pollutants. These processes have been well investigated in lungs; however, although skin is directly exposed to a great variety of environmental pollutants, more research is needed to better understand the effect on cutaneous tissue. Therefore, we investigated microRNA alteration in human skin biopsies exposed to diesel fumes, ozone, and UV light for over 24 h of exposure. UV and ozone-induced microRNA alteration right after exposure, while the peak of their deregulations induced by diesel fumes was reached only at the end of the 24 h. Diesel fumes mainly altered microRNAs involved in the carcinogenesis process, ozone in apoptosis, and UV in DNA repair. Accordingly, each tested pollutant induced a specific pattern of microRNA alteration in skin related to the intrinsic mechanisms activated by the specific pollutant. These alterations, over a short time basis, reflect adaptive events aimed at defending the tissue against damages. Conversely, whenever environmental exposure lasts for a long time, the irreversible alteration of the microRNA machinery results in epigenetic damage contributing to the pathogenesis of inflammation, dysplasia, and cancer induced by environmental pollutants.

Bortezomib Inhibits Multiple Myeloma Cells by Transactivating ATF3 to Trigger miR-135a-5p- Dependent Apoptosis

Multiple myeloma (MM) is a malignant cancer with an increasing in incidence that can be alleviated through bortezomib (BTZ) treatment. Activating transcription factor 3 (ATF3) plays a major role in cancer development. Moreover, microRNAs (miRNAs) regulate carcinogenic pathways, apoptosis, and programmed necrotic cell death. However, the detailed mechanism by which ATF3 modulates BTZ drug sensitivity/resistance remains elusive. In the current study, expression of ATF3 was significantly increased under BTZ treatment in a dose-dependent manner in MM cell lines. In addition, ATF3 could regulate cell apoptosis under BTZ treatment. The effect of ATF3 was negatively regulated by its binding miRNA, miR-135a-5p. When either ATF3 was silenced or miR-135a-5p mimics were added to MM cells, they partially lost sensitivity to BTZ treatment. This was accompanied by low levels of Noxa, CHOP, and DR5, and a decrease in mitochondrial membrane potential. These results revealed the combinatorial regulatory patterns of ATF3 and miR-135a-5p in the regulatory protein interactome, which indicated a clinical significance of the miR-135a-5p-ATF3 protein interaction network in BTZ therapy. This study provides potential evidence for further investigation into BTZ resistance.

Over-expression of long non-coding RNA insulin-like growth factor 2-antisense suppressed hepatocellular carcinoma cell proliferation and metastasis by regulating the microRNA-520h/cyclin-dependent kinase inhibitor 1A signaling pathway

Primary liver cancer is the sixth most common cancer and the third leading cause of malignancy-related death worldwide in 2020, with 75–85% of hepatocellular carcinoma (HCC). Evidences have verified that long noncoding RNAs (lncRNAs) play key roles in HCC onset and development. However, the function and mechanism of lncRNA insulin-like growth factor 2-antisense (IGF2-AS) in HCC remain unclear. Herein, IGF2-AS expression profile in HCC patients was first investigated based on The Cancer Genome Atlas (TCGA) database and local HCC patients, followed by prognostic value evaluation using Kaplan–Meier method; then, the bioinformatics analysis, dual-luciferase reporter assay, Spearman correlation assay, function gain, and loss with rescue experiments were applied to investigate the biological function and the involved molecular mechanisms of IGF2-AS in HCC oncogenesis and development. Our results showed that IGF2-AS expression was significantly down-regulated in HCC cells and tissues; lower IGF2-AS expression was significantly associated with poor prognosis of HCC patients; IGF2-AS over-expression inhibited the viability, colony formation, invasion, and migration, while promoted apoptosis in vitro, and inhibited HCC xenograft growth in vivo; IGF2-AS sponged microRNA-520h (miR-520h) to up-regulate IGF2-AS expression, and miR-520h over-expression or cyclin-dependent kinase inhibitor 1A (CDKN1A) silencing reversed IGF2-AS reduced aggressive behaviors of HCC cells. In conclusion, IGF2-AS is a tumor-suppressor in HCC, and lower IGF2-AS expression is associated with poor prognosis of HCC patients; IGF2-AS inhibits HCC oncogenesis and development by IGF2-AS/miR-520h/CDKN1A pathway. Therefore, IGF2-AS may serve as a new biomarker for HCC management.

Knockdown of LINC00657 inhibits the viability, migration and invasion of pancreatic cancer cells by regulating the miR-520h/CKS1B axis

Long non-coding RNA LINC00657 has a critical role in multiple cancers. The aim of the present study was to investigate the regulatory effect of LINC00657 in pancreatic cancer (PC) and reveal its molecular mechanism of function. The expression levels of LINC00657 and microRNA (miR)-520h were detected by reverse transcription-quantitative PCR in PC tissues and cell lines. MTT, wound healing and Transwell assays were used to detect cell viability, migration and invasion, respectively. Dual-luciferase reporter assay was utilized to examine the relationship between LINC00657 and miR-520h and that between miR-520h and cyclin-dependent kinases regulatory subunit 1 (CKS1B). Western blotting was performed to detect CKS1B expression. The expression levels of LINC00657 and CKS1B were enhanced and miR-520h expression level was reduced in PC tissues and cell lines compared with adjacent normal tissues or HPDE6 cells. LINC00657 knockdown decreased the viability, migration and invasion of PC cells. Additionally, LINC00657 targeted miR-520h and negatively modulated miR-520h expression. Furthermore, miR-520h overexpression inhibited the viability, migration and invasion of PC cells. In addition, miR-520h targeted CKS1B and reversely regulated CKS1B expression. miR-520h inhibition and CKS1B overexpression alleviated the inhibition effect of LINC00657 knockdown on the viability, migration and invasion of PACA-2 PC cells. In conclusion, the results of the present study demonstrated that LINC00657 knockdown repressed the viability, migration and invasion of PC cells via targeting the miR-520h/CKS1B axis, which may offer a future target for PC therapy.

Two Antibody-Guided Lactic-co-Glycolic Acid-Polyethylenimine (LGA-PEI) Nanoparticle Delivery Systems for Therapeutic Nucleic Acids

We previously reported a new polymer, lactic-co-glycolic acid-polyethylenimine (LGA-PEI), as an improved nanoparticle (NP) delivery for therapeutic nucleic acids (TNAs). Here, we further developed two antibody (Ab)-conjugated LGA-PEI NP technologies for active-targeting delivery of TNAs. LGA-PEI was covalently conjugated with a single-chain variable fragment antibody (scFv) against mesothelin (MSLN), a biomarker for pancreatic cancer (PC), or a special Ab fragment crystallizable region-binding peptide (FcBP), which binds to any full Ab (IgG). TNAs used in the current study included tumor suppressor microRNA mimics (miR-198 and miR-520h) and non-coding RNA X-inactive specific transcript (XIST) fragments; green fluorescence protein gene (GFP plasmid DNA) was also used as an example of plasmid DNA. MSLN scFv-LGA-PEI NPs with TNAs significantly improved their binding and internalization in PC cells with high expression of MSLN in vitro and in vivo. Anti-epidermal growth factor receptor (EGFR) monoclonal Ab (Cetuximab) binding to FcBP-LGA-PEI showed active-targeting delivery of TNAs to EGFR-expressing PC cells.

Circ_0000317/microRNA-520g/HOXD10 axis affects the biological characteristics of colorectal cancer

Circular RNAs (circRNAs) are a class of noncoding RNAs that are widely expressed in cancer tissues and play a pro- or anticancer role in modulating cancer progression. This work is aimed to probe the biological role of circ_0000317 in colorectal cancer (CRC) and its underlying mechanism. Circ_0000317 was selected from the circRNA microarray datasets (GSE121895). Quantitative real-time polymerase chain reaction was utilized to examine circ_0000317, microRNA (miR)-520g, and homeobox D10 (HOXD10) mRNA expression in CRC. Cell Counting Kit-8 and Transwell experiments were conducted to examine the effects of circ_0000317 on proliferation, migration, and invasion of CRC cells. Bioinformatic analysis and dual-luciferase reporter gene experiments were implemented to predict and validate the targeting relationship between circ_0000317 and miR-520g, miR-520g, and HOXD10. Western blot was employed to examine HOXD10 expression at protein level in CRC cells. Circ_0000317 and HOXD10 mRNA expression were unveiled to be down-modulated and miR-520g expression was up-modulated in CRC. Functionally, circ_0000317 overexpression repressed CRC cell proliferation, migration, and invasion. Mechanistically, miR-520g was a direct target of circ_0000317 and miR-520g specifically modulated HOXD10 expression. Furthermore, miR-520g mimics partially counteracted the suppressing effect of circ_0000317 on malignant phenotype of CRC cells. Circ_0000317 represses CRC progression by targeting miR-520g and modulating HOXD10 expression. Hence, circ_0000317 may be a promising diagnostic biomarker and a therapeutic target for CRC.

tRNA-derived fragments as novel potential biomarkers for relapsed/refractory multiple myeloma

Background

tRNA-derived fragments have been reported to be key regulatory factors in human tumors. However, their roles in the progression of multiple myeloma remain unknown.

Results

This study employed RNA-sequencing to explore the expression profiles of tRFs/tiRNAs in new diagnosed MM and relapsed/refractory MM samples. The expression of selected tRFs/tiRNAs were further validated in clinical specimens and myeloma cell lines by qPCR. Bioinformatic analysis was performed to predict their roles in multiple myeloma progression.We identified 10 upregulated tRFs/tiRNAs and 16 downregulated tRFs/tiRNAs. GO enrichment and KEGG pathway analysis were performed to analyse the functions of 1 significantly up-regulated and 1 significantly down-regulated tRNA-derived fragments. tRFs/tiRNAs may be involved in MM progression and drug-resistance.

Conclusion

tRFs/tiRNAs were dysregulated and could be potential biomarkers for relapsed/refractory MM.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12859-021-04167-8.

Genomic Instability in Multiple Myeloma: A "Non-Coding RNA" Perspective

Simple Summary

Genomic instability (GI) plays an important role in the pathobiology of multiple myeloma (MM) by promoting the acquisition of several tumor hallmarks. Molecular determinants of GI in MM are continuously emerging and will be herein discussed, with specific regard to non-coding RNAs. Targeting non-coding RNA molecules known to be involved in GI indeed provides novel routes to dampen such oncogenic mechanisms in MM.

Abstract

Multiple myeloma (MM) is a complex hematological malignancy characterized by abnormal proliferation of malignant plasma cells (PCs) within a permissive bone marrow microenvironment. The pathogenesis of MM is unequivocally linked to the acquisition of genomic instability (GI), which indicates the tendency of tumor cells to accumulate a wide repertoire of genetic alterations. Such alterations can even be detected at the premalignant stages of monoclonal gammopathy of undetermined significance (MGUS) and smoldering multiple myeloma (SMM) and, overall, contribute to the acquisition of the malignant traits underlying disease progression. The molecular basis of GI remains unclear, with replication stress and deregulation of DNA damage repair pathways representing the most documented mechanisms. The discovery that non-coding RNA molecules are deeply dysregulated in MM and can target pivotal components of GI pathways has introduced a further layer of complexity to the GI scenario in this disease. In this review, we will summarize available information on the molecular determinants of GI in MM, focusing on the role of non-coding RNAs as novel means to tackle GI for therapeutic intervention.

Expression Profiles of tRNA-Derived Fragments and Their Potential Roles in Multiple Myeloma

Background

Multiple myeloma is an incurable hematologic malignancy. The discovery of mechanisms may help to find new therapeutic targets and prolong survival. tRNA-related fragments (tRF) and tRNA halves (tiRNA) are small RNA derived from tRNAs and implicated in a wide variety of pathological processes, including cancer initiation and progression. However, there are almost no research reporting the role of these tRNA derived fragments in myeloma as far as we know.

Methods

In this study, we proposed the expression profiles of tRFs/tiRNAs in myeloma through RNA-sequencing in new diagnosed myeloma and healthy donors. The expression of selected tRFs/tiRNAs was further validated in clinical specimens by qPCR. Bioinformatic analysis was performed to predict their potential roles in multiple myeloma.

Results

A total of 33 upregulated tRFs/tiRNAs and 22 downregulated tRFs/tiRNAs were identified. GO enrichment and KEGG pathway analysis were performed to analyze the functions of one significantly up-regulated and one significantly down-regulated tRNA-derived fragments. tRFs/tiRNAs may be involved in MM initiation and progression.

Conclusion

We concluded that tRFs/tiRNAs were dysregulated and could be potential biomarkers for multiple myeloma.

miRNAs mediated drug resistance in hematological malignancies

Despite improvements in the therapeutic approaches for hematological malignancies in the last decades, refractory disease still occurs, and cancer drug resistance still remains a major hurdle in the clinical management of these cancer patients. The investigation of this problem has been extensive and different mechanism and molecules have been associated with drug resistance. MicroRNAs (miRNAs) have been described as having an important action in the emergence of cancer, including hematological tumors, and as being major players in their progression, aggressiveness and response to treatments. Moreover, miRNAs have been strongly associated with cancer drug resistance and with the modulation of the sensitivity of cancer cells to a wide array of anticancer drugs. Furthermore, this role has also been reported for miRNAs packaged into extracellular vesicles (EVs-miRNAs), which in turn have been described as essential for the horizontal transfer of drug resistance to sensitive cells. Several studies have been suggesting the use of miRNAs as biomarkers for drug response and clinical outcome prediction, as well as promising therapeutic tools in hematological diseases. Indeed, the combination of miRNA-based therapeutic tools with conventional drugs contributes to overcome drug resistance. This review addresses the role of miRNAs in the pathogenesis of hematological malignances, namely multiple myeloma, leukemias and lymphomas, highlighting their important action (either in their cell-free circulating form or within circulating EVs) in drug resistance and their potential clinical applications.

Potential Role of microRNAs in inducing Drug Resistance in Patients with Multiple Myeloma

The prognosis for newly diagnosed subjects with multiple myeloma (MM) has significantly progressed in recent years. However, most MM patients relapse and after several salvage therapies, the onset of multidrug resistance provokes the occurrence of a refractory disease. A continuous and bidirectional exchange of information takes place between the cells of the microenvironment and neoplastic cells to solicit the demands of cancer cells. Among the molecules serving as messengers, there are microRNAs (miRNA), a family of small noncoding RNAs that regulate gene expression. Numerous miRNAs are associated with drug resistance, also in MM, and the modulation of their expression or activity might be explored to reverse it. In this review we report the most recent studies concerning the relationship between miRNAs and chemoresistance to the most frequently used drugs, such as proteasome inhibitors, steroids, alkylating agents and immunomodulators. The experimental use of antagomirs or miRNA mimics have successfully been proven to counteract chemoresistance and display synergistic effects with antimyeloma drugs which could represent a fundamental moment to overcome resistance in MM treatment.

Diallyl thiosulfinate enhanced the anti-cancer activity of dexamethasone in the side population cells of multiple myeloma by promoting miR-127-3p and deactivating the PI3K/AKT signaling pathway

Background

Side population (SP) cells, which have similar features to those of cancer stem cells, show resistance to dexamethasone (Dex) treatment. Thus, new drugs that can be used in combination with Dex to reduce the population of SP cells in multiple myeloma (MM) are required. Diallyl thiosulfinate (DATS, allicin), a natural organosulfur compound derived from garlic, has been shown to inhibit the proliferation of SP cells in MM cell lines. Therefore, we investigated the effect of a combination of DATS and Dex (DAT + Dex) on MM SP cells.

Methods

SP cells were sorted from MM RPMI-8226 and NCI-H929 cell lines using Hoechst 33342-labeled fluorescence-activated cell sorting. The growth of SP cells was evaluated using the cell counting kit-8 assay. Cell cycle and apoptosis assays were conducted using a BD Calibur flow cytometer. miRNA expression was measured using quantitative reverse transcription-polymerase chain reaction. Phosphoinositide 3-kinase (PI3K), phosphorylated AKT (p-AKT), AKT, p-mechanistic target of rapamycin (mTOR), and mTOR levels were measured using western blot analysis.

Results

Our results showed that the combination of DATS+Dex inhibited sphere formation, colony formation, and proliferation of MM SP cells by inducing apoptosis and cell cycle arrest in the G1/S phase. In addition, the combination of DATS+Dex promoted miR-127-3p expression and inhibited PI3K, p-AKT, and p-mTOR expression in SP cells. Knockdown of miR-127-3p expression weakened the effect of DATS+Dex on cell proliferation, colony formation, apoptosis, and cell cycle of MM SP cells. Additionally, knockdown of miR-127-3p activated the PI3K/AKT/mTOR signaling pathway in MM SP cells cotreated with DATS+Dex.

Conclusion

We demonstrated that cotreatment with DATS+Dex reduced cell proliferation, promoted apoptosis, and caused cell cycle arrest of MM SP cells by promoting miR-127-3p expression and deactivating the PI3K/AKT/mTOR signaling pathway.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12885-021-07833-5.

MicroRNA-1252-5p Associated with Extracellular Vesicles Enhances Bortezomib Sensitivity in Multiple Myeloma Cells by Targeting Heparanase

INTRODUCTION

Multiple myeloma (MM) remains an incurable disease, and patient survival requires a better understanding of this malignancy's molecular aspects. Heparanase (HPSE) is highly expressed in aggressive MM cells and related to tumor growth, metastasis, and bortezomib (BTZ) resistance. Thus, targeting HPSE seems to be a promising approach for MM treatment, and because microRNAs (miRNAs) have emerged as potential regulators of HPSE expression, the use of extracellular vesicles (EVs) can allow the efficient delivery of therapeutic miRNAs.

METHODS

We used prediction algorithms to identify potential miRNAs that regulate negatively HPSE expression. RT-qPCR was performed to assess miRNAs and HPSE expression in MM lines (U266 and RPMI-8226). Synthetic miRNA mimics were electroporated in MM cells to understand the miRNA contribution in HPSE expression, glycosaminoglycans (GAGs) profile, cell proliferation, and cell death induced by BTZ. EVs derived from HEK293T cells were engineered with miRNAs to evaluate their therapeutic potential combined with BTZ.

RESULTS

It revealed a direct association between BTZ sensitivity, HPSE, and miR-1252-5p expressions. Moreover, overexpression of miR-1252-5p significantly reduced HPSE expression and HPSE enzymatic activity in MM cells. The higher level of miR-1252-5p was correlated with a reduction of cell viability and higher sensitivity to BTZ. Further, EVs carrying miR-1252-5p increased MM cells' sensitivity to BTZ treatment.

CONCLUSION

These results showed that miR-1252-5p could negatively regulate HPSE in MM, indicating the use of EVs carrying miR-1252-5p as a potential novel BTZ sensitization approach in MM cells.

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

Multiple myeloma (MM) is a malignant neoplasm featured by obvious drug resistance and poor prognosis. MicroRNAs (miRNAs) are a class of small noncoding RNAs with crucial roles in many biological processes including cancer initiation and progression. The current study aims to investigate the pathogenic role and molecular mechanism of miRNAs in MM drug resistance. In the present study, The expression profile of miRNAs in MM samples was analyzed by microarray and real-time polymerase chain reaction. Protein expressions were detected by Western blot analysis. Cell apoptosis was detected by the Annexin V staining assay. The interaction between miRNA and the targeting mRNA was assessed using Dual luciferase reporter assay. Herein, we show that expression profile of miRNAs is deregulated in MM. miR-218, one of the most aberrational miRNAs in MM, is significantly decreased in MM cells compared to peripheral blood mononuclear cell (PBMC). Genetic manipulation reveals miR-218 control the response of MM cells to anticancer drug bortezomib (BTZ). Overexpression of miR-218 causes a significant aberrant genes expression including leucine rich repeat containing 28 (LRRC28). Mechanistic study shows that miR-218 control the drug response through mediating the expression of LRRC28 in MM cells. Overexpression of LRRC28 significantly reserves miR-218-mediated cell response to BTZ. Taken together, miR-218 is decreased in MM that contributes to BTZ resistance via targeting LRRC28, which might be used as a novel therapeutic target for multiple myeloma.

LINC01436 Promotes the Progression of Gastric Cancer via Regulating miR-513a-5p/APE1 Axis

Background

Gastric cancer (GC) is one of the deadliest cancer worldwide. Multiple long non-coding RNAs (lncRNAs) are recently identified as crucial oncogenic factors or tumor suppressors in GC. In this study, we aimed to probe into the effect of LINC01436 on GC progression.

Methods

LINC01436 and miR-513a-5p expressions in GC tissue samples were measured using quantitative real-time polymerase chain reaction (qRT-PCR). Western blot was used to detect the expression of apurinic/apyrimidinic endodeoxyribonuclease 1 (APE1) expression. Human GC cell lines AGS and BGC-823 were employed to investigate the function and mechanism of LINC01436 in GC. Cell counting kit-8 (CCK-8) assay was used to assess the effect of LINC01436 on proliferation. Flow cytometry was utilized to explore the effect of LINC01436 on apoptosis, and Transwell assay was conducted to detect the effect of LINC01436 on the migration and invasion. Colony formation assay was performed to evaluate the effect of LINC01436 on radioresistance of GC cells. Furthermore, luciferase reporter assay and RNA immunoprecipitation assay were conducted to confirm the binding relationship between miR-513a-5p and LINC01436. Additionally, Western blot was used to study the regulatory function of LINC01436 and miR-513a-5p on APE1.

Results

LINC01436 expression of GC clinical samples was remarkably increased and LINC01436 was correlated with unfavorable pathological indexes. LINC01436 high expression was associated with shorter overall survival time. Its overexpression observably promoted the proliferation, metastasis and radioresistance of GC cells, and its knockdown suppressed the malignant phenotypes of GC cells. LINC01436 overexpression markedly reduced the miR-513a-5p expression via sponging it and enhanced the APE1 expression. MiR-513a-5p overexpression or APE1 knockdown reversed the effects of LINC01436 on GC cells.

Conclusion

LINC01436 is a molecular sponge of tumor suppressor miR-513a-5p, which indirectly enhances the APE1 expression and functions as the oncogenic lncRNA in GC.

MicroRNA-mediated autophagy regulation in cancer therapy: The role in chemoresistance/chemosensitivity

Chemoresistance has doubled the effort needed to reach an effective treatment for cancer. Now, scientists should consider molecular pathways and mechanisms involved in chemoresistance to overcome cancer. Autophagy is a "self-digestion" mechanism in which potentially toxic and aged organelles and macromolecules are degraded. Increasing evidence has shown that autophagy possesses dual role in cancer cells (onco-suppressor or oncogene). So, it is vital to identify its role in cancer progression and malignancy. MicroRNAs (miRs) are epigenetic factors capable of modulation of autophagy in cancer cells. In the current review, we emphasize on the relationship between miRs and autophagy in cancer chemotherapy. Besides, we discuss upstream mediators of miR/autophagy axis in cancer chemotherapy including long non-coding RNAs, circular RNAs, Nrf2 c-Myc, and HIF-1α. At the final section, we provide a discussion about how anti-tumor compounds affect miR/autophagy axis in ensuring chemosensitivity. These topics are described in this review to show how autophagy inhibition/induction can lead to chemosensitivity/chemoresistance, and miRs are considered as key players in these discussions.

Role of microRNAs in Diagnosis, Prognosis and Management of Multiple Myeloma

Multiple myeloma (MM) is a cancerous bone disease characterized by malignant transformation of plasma cells in the bone marrow. MM is considered to be the second most common blood malignancy, with 20,000 new cases reported every year in the USA. Extensive research is currently enduring to validate diagnostic and therapeutic means to manage MM. microRNAs (miRNAs) were shown to be dysregulated in MM cases and to have a potential role in either progression or suppression of MM. Therefore, researchers investigated miRNAs levels in MM plasma cells and created tools to test their impact on tumor growth. In the present review, we discuss the most recently discovered miRNAs and their regulation in MM. Furthermore, we emphasized utilizing miRNAs as potential targets in the diagnosis, prognosis and treatment of MM, which can be useful for future clinical management.

Let-7b regulates the adriamycin resistance of chronic myelogenous leukemia by targeting AURKB in K562/ADM cells

Chronic myeloid leukemia (CML) is a malignant hematological disease, and drug resistance is often related to poor prognosis. MicroRNAs (miRNA) play a pivotal role in transcriptional regulation, cell development, and chemotherapy resistance. Here, we describe the effect of let-7b on resistant leukemia cells and examine the relevance of let-7b as a biomarker for adriamycin resistance. Results showed that let-7b was downregulated in K562/ADM (KA) cells, and the downregulation of let-7b in K562 and KA cells increased ADM resistance. The inhibition of let-7b subsequently induced the upregulation of AURKB. Finally, results proved that the Pi3k/Akt/Erk pathway was related to AURKB-activated resistance. Our research indicated that the underexpression of let-7b and overexpression of AURKB contributed to the resistance of CML, and its function is partly regulated by the Pi3k/Akt/Erk pathway. Thus, our further understand of its inhibitory effect may promise a new therapeutic strategy to overcome chemotherapeutic resistance in CML.

miR-520h Stimulates Drug Resistance to Paclitaxel by Targeting the OTUD3-PTEN Axis in Breast Cancer

MicroRNAs (miRNAs) have been identified as negative posttranscriptional regulators of target genes and are involved directly in the pathological processes of tumors, including drug resistance. However, the exact function of miR-520h in breast cancer remains poorly understood. The aim of this study was to investigate the molecular mechanisms of miR-520h in paclitaxel resistance in the MCF-7 breast cancer cell line. Ectopic expression of miR-520h could promote the proliferation of breast cancer cells and inhibit paclitaxel-induced cell apoptosis. Inhibiting the expression of miR-520h could enhance the sensitivity to paclitaxel in paclitaxel-resistant MCF-7/Taxol cells. Furthermore, luciferase reporter assays showed that OTUD3 was a direct target of miR-520h. OTUD3 plays a necessary role in the paclitaxel resistance effect of miR-520h, and cotreatment with a miR-520h inhibitor and OTUD3 overexpression significantly enhanced MCF-7 cell sensitivity to paclitaxel. Moreover, miR-520h substantially inhibited the protein expression of PTEN via OTUD3 and subsequently affected downstream p-AKT pathway activity. In a clinical study, we also found that high miR-520h expression was associated with more aggressive pathological characteristic and poor prognosis. Therefore, our findings showed that miR-520h targeted the OTUD3-PTEN axis to drive paclitaxel resistance, and this miR might be an important potential target for breast cancer treatment.

The YY1/miR-548t-5p/CXCL11 signaling axis regulates cell proliferation and metastasis in human pancreatic cancer

Pancreatic cancer (PC) is a malignant tumor with a poor prognosis and high mortality. However, the biological role of miR-548t-5p in PC has not been reported. In this study, we found that miR-548t-5p expression was significantly decreased in PC tissues compared with adjacent tissues, and that low miR-548t-5p expression was associated with malignant PC behavior. In addition, high miR-548t-5p expression inhibited the proliferation, migration, and invasion of PC cell lines. Regarding the molecular mechanism, the luciferase reporter gene, chromatin immunoprecipitation (ChIP), and functional recovery assays revealed that YY1 binds to the miR-548t-5p promoter and positively regulates the expression and function of miR-548t-5p. miR-548t-5p also directly regulates CXCL11 to inhibit its expression. A high level of CXCL11 was associated with worse Tumor Node Metastasis (TNM) staging in patients with PC, enhancing proliferation and metastasis in PC cells. Our study shows that the YY1/miR-548t-5p/CXCL11 axis plays an important role in PC and provides a new potential candidate for the treatment of PC.

LncRNA TDRG1 promotes the proliferation, migration, and invasion of cervical cancer cells by sponging miR-214-5p to target SOX4

The pathogenesis of cervical cancer (CC) at molecular level has attracted much research attention. The current study aimed to explore the effects of LncRNA TDRG1 on cellular process in CC cells and its molecular mechanism. Expressions of TDRG1 and miR-214-5p in CC and normal tissues and CC cells were measured by quantitative real-time polymerase chain reaction (qRT-PCR). The effects of TDRG1, miR-214-5p, and SOX4 on cell proliferation, migration, invasion, and EMT process of CC cells were detected by Cell Counting Kit-8 (CCK-8), colony formation, wound-healing, Transwell, and Western blot assays, respectively. StarBase and Targetscan7.2 were used to predict the target genes of TDRG1 and miR-214-5p, and the predictions were verified by dual-luciferase reporter assay. The expression of SOX4 in CC and normal tissues, and CC cells transfected with siTDRG1 or miR-214-5p inhibitor was determined by qRT-PCR. The results showed that expression of TDRG1 was up-regulated, while that of miR-214-5p was down-regulated in CC. The target genes of TDRG1 and miR-214-5p were verified to be miR-214-5p and SOX4, respectively. Knocking down TDRG1 expression could inhibit cell proliferation, colony, migration, and invasion abilities, and EMT process, whereas the inhibition of miR-214-5p expression partially reversed such results. Moreover, high SOX4 expression was observed in CC tissues, and down-regulating TDRG1 expression reduced the SOX4 expression while down-regulating miR-214-5p expression alleviated such an inhibition. In conclusion, TDRG1 acts as cancer promoter in CC through promoting cell proliferation, migration, invasion, and EMT process to modulate SOX4 expression through adsorbing miR-214-5p.

Scutellarin circumvents chemoresistance, promotes apoptosis, and represses tumor growth by HDAC/miR-34a-mediated down-modulation of Akt/mTOR and NF-κB-orchestrated signaling pathways in multiple myeloma

Multiple myeloma (MM) is a neoplastic dyscrasia of monoclonal immunoglobulin-secreting plasma cells culminating in multi-organ dysfunction. In this study, we sought to investigate whether scutellarin (STN), a flavonoid, could reduce MM progression, mitigate chemoresistance of MM cells to bortezomib (BTB), and cause MM cell apoptosis in a xenograft mouse model of MM. Epigenetic signalling plays a main role in the modulation of various pathways involved in multiple myeloma progression. At the outset, mechanistic analyses of the MM pathways indicated that key epigenetic molecules including HDAC1/3 and miR-34a were up-modulated and down-modulated respectively, in the MM mice. Besides, the downstream signalling analysis of miR-34a depicted that the c-Met/AKT/mTOR pathway was activated in the MM mice. We also investigated the expression of NF-κB, one of the major chemoresistance inducers in cancer treatment, in the MM mice. As anticipated, the tumor-bearing mice expressed more NF-κB along with elevated anti-apoptotic Bcl-xL protein, as well as reduced pro-apoptotic Bim protein. On the other hand, STN+BTB co-treatment effectively combated the MM tumor progression, and STN circumvented the MM tumor resistance to BTB and provoked apoptotic cell death in MM. Based on our study data, we deduce that STN, in combination with BTB, appears to be a reliable tumoricidal strategy.

MicroRNA-Based Combinatorial Cancer Therapy: Effects of MicroRNAs on the Efficacy of Anti-Cancer Therapies

The susceptibility of cancer cells to different types of treatments can be restricted by intrinsic and acquired therapeutic resistance, leading to the failure of cancer regression and remission. To overcome this problem, a combination therapy has been proposed as a fundamental strategy to improve therapeutic responses; however, resistance is still unavoidable. MicroRNA (miRNAs) are associated with cancer therapeutic resistance. The modulation of dysregulated miRNA levels through miRNA-based therapy comprising a replacement or inhibition approach has been proposed to sensitize cancer cells to other anti-cancer therapies. The combination of miRNA-based therapy with other anti-cancer therapies (miRNA-based combinatorial cancer therapy) is attractive, due to the ability of miRNAs to target multiple genes associated with the signaling pathways controlling therapeutic resistance. In this article, we present an overview of recent findings on the role of therapeutic resistance-related miRNAs in different types of cancer. We review the feasibility of utilizing dysregulated miRNAs in cancer cells and extracellular vesicles as potential candidates for miRNA-based combinatorial cancer therapy. We also discuss innate properties of miRNAs that need to be considered for more effective combinatorial cancer therapy.

The Role and Function of microRNA in the Pathogenesis of Multiple Myeloma

Recently, attention has been drawn to the role of non-coding regions of the genome in cancer pathogenesis. MicroRNAs (miRNAs) are small non-coding RNAs with 19–25 bases of length that control gene expression by destroying messenger RNA or inhibiting its translation. In multiple myeloma (MM), the expression of several miRNAs, such as miR-15a and miR-16, is markedly decreased and their target genes upregulated, suggesting their role as tumor-suppressing miRNAs. In contrast, miRNAs such as miR-21 and miR-221 are highly expressed and function as oncogenes (oncomiRs). In addition, several miRNAs, such as those belonging to the miR-34 family, are transcriptional targets of p53 and mediate its tumor-suppressive functions. Many miRNAs are associated with drug resistance, and the modulation of their expression or activity might be explored to reverse it. Moreover, miRNA expression patterns in either MM cells or serum exosomes have been shown to be good prognostic markers. miRNA regulation mechanisms have not been fully elucidated. Many miRNAs are epigenetically controlled by DNA methylation and histone modification, and others regulate the expression of epigenetic modifiers, indicating that miRNA and other epigenetic effectors are part of a network. In this review, we outlined the roles of miRNAs in MM and their potential to predict MM prognosis and develop novel therapies.