Long Non-Coding RNAs in Multiple Myeloma

Identification and evaluation of a six-lncRNA prognostic signature for multiple myeloma

PURPOSE

Multiple myeloma (MM) is the second most common hematologic malignancy, and there is no cure for this disease. This study aimed to explore the prognostic value of long noncoding RNAs (lncRNAs) in MM and to reveal related immune and chemotherapy resistance mechanisms.

METHODS

In this study, lncRNA profiles from the Multiple Myeloma Research Foundation (MMRF) and Gene Expression Omnibus (GEO) databases were analyzed to identify lncRNAs linked to MM patient survival. A risk assessment model stratified patients into high- and low-risk groups, and survival was evaluated. Additionally, a triple-ceRNA (lncRNA-miRNA-mRNA) network was constructed, and functional analysis was performed. The research also involved immune function analysis and chemotherapy drug sensitivity assessment using oncoPredict and the GDSC dataset.

RESULTS

We identified 422 lncRNAs significantly associated with overall survival in MM patients and ultimately focused on the 6 with the highest prognostic value. These lncRNAs were used to develop a risk score formula that stratified patients into high- and low-risk groups. Kaplan-Meier analysis revealed shorter survival in high-risk patients. We integrated this lncRNA signature with clinical parameters to construct a nomogram for predicting MM prognosis. Additionally, a triple-ceRNA network was constructed to reveal potential miRNA targets, coding genes related to these lncRNAs and significantly enriched pathways. Immune checkpoint gene expression and immune cell composition were also analyzed in relation to the lncRNA risk score. Finally, using the oncoPredict tool, we observed that high-risk patients exhibited decreased sensitivity to key MM chemotherapeutics, suggesting that lncRNA profiles are linked to chemotherapy resistance.

Highlights on the Effects of Non-Coding RNAs in the Osteonecrosis of the Jaw

Osteonecrosis of the jaw is the progressive loss and destruction of bone affecting the maxilla or mandible in patients treated with antiresorptive and antiangiogenic agents without receiving prior radiation therapy. The pathogenesis involves the inflammatory pathway of receptor activator of nuclear factor NF-kB ligand and the macrophage colony-stimulating factor, essential for osteoclast precursors survival and proliferation and acting through its receptor c-Fms. Evidence has shown the role of non-coding RNAs in the pathogenesis of osteonecrosis of the jaw and this finding might be useful in diagnosis since these small RNAs could be considered as biomarkers of apoptotic activity in bone. Interestingly, it has been proved that miR-29 and miR-31-5p, acting on specific targets such as CALCR and RhoA, promote programmed-cell death and consequently the necrosis of bone tissue. Specific long non-coding RNAs, instead, have been detected both at reduced levels in patients with multiple myeloma and osteonecrosis, and associated with suppression of osteoblast differentiation, with consequences in the progression of mandible lesions. Among non-coding genic material, circular RNAs have the capability to modify the expression of specific mRNAs responsible for the inhibition of bisphosphonates activity on osteoclastogenesis.

Multiple myeloma, a quintessential malignant disease of aging: a geroscience perspective on pathogenesis and treatment

Multiple myeloma (MM) is an incurable plasma cell malignancy, which is predominantly a disease of older adults (the median age at diagnosis is 70 years). The slow progression from asymptomatic stages and the late-onset of MM suggest fundamental differences compared to many other hematopoietic system-related malignancies. The concept discussed in this review is that age-related changes at the level of terminally differentiated plasma cells act as the main risk factors for the development of MM. Epigenetic and genetic changes that characterize both MM development and normal aging are highlighted. The relationships between cellular aging processes, genetic mosaicism in plasma cells, and risk for MM and the stochastic processes contributing to clonal selection and expansion of mutated plasma cells are investigated. In line with the DNA damage accumulation theory of aging, in this review, the evolution of monoclonal gammopathy to symptomatic MM is considered. Therapeutic consequences of age-dependent comorbidities that lead to frailty and have fundamental influence on treatment outcome are described. The importance of considering geriatric states when planning the life-long treatment course of an elderly MM patient in order to achieve maximal therapeutic benefit is emphasized.

Expression levels of NONO, a nuclear protein primarily involved in paraspeckles function, are associated with several deregulated molecular pathways and poor clinical outcome in multiple myeloma

PURPOSE

The NONO protein belongs to the multifunctional family of proteins that can bind DNA, RNA and proteins. It is located in the nucleus of most mammalian cells and can affect almost every step of gene regulation. Dysregulation of NONO has been found in many types of cancer; however, data regarding its expression and relevance in Multiple Myeloma (MM) are virtually absent.

METHODS

We took advantage of a large cohort of MM patients enrolled in the Multiple Myeloma Research Foundation CoMMpass study to elucidate better the clinical and biological relevance of NONO expression in the context of the MM genomic landscape and transcriptome.

RESULTS

NONO is overexpressed in pathological samples compared to normal controls. In addition, higher NONO expression levels are significant independent prognostic markers of worse clinical outcome in MM. Our results indicate that NONO deregulation may play a pathogenetic role in MM by affecting cell cycle, DNA repair mechanisms, and influencing translation by regulating ribosome biogenesis and assembly. Furthermore, our data suggest NONO involvement in the metabolic reprogramming of glucose metabolism from respiration to aerobic glycolysis, a phenomenon known as the 'Warburg Effect' that supports rapid cancer cell growth, survival, and invasion.

CONCLUSION

These findings strongly support the need of future investigations for the understanding of the mechanisms of deregulation and the biological role and activity of NONO in MM.

Dissecting the Biological Relevance and Clinical Impact of lncRNA MIAT in Multiple Myeloma

Simple Summary

The interest in the biological role and clinical impact of long non-coding RNAs (lncRNAs) in multiple myeloma (MM) is continuously expanding. Many studies, mainly involving solid tumors, have strongly suggested the MIAT oncogenic role; more recently, it has been suggested that MIAT may have a role in inducing Bortezomib resistance in MM. However, data concerning MIAT deregulation in MM are virtually absent. In this context, we investigated the expression pattern and the clinical relevance of the lncRNA MIAT in MM, taking advantage of the publicly available CoMMpass database. Our findings prompt further studies to elucidate better the significance of MIAT in MM.

Abstract

The biological impact of long non-coding RNAs (lncRNAs) in multiple myeloma (MM) is becoming an essential aspect of the investigation, which may contribute to understanding the disease’s complex pathobiology, providing novel potential therapeutic targets. Herein, we investigated the expression pattern and the clinical relevance of the lncRNA MIAT in MM, taking advantage of the publicly available CoMMpass database. MIAT expression in MM is highly heterogeneous and significantly associated with specific molecular lesions frequently occurring in MM. Transcriptome analyses of MM PCs from patients included in the CoMMpass database indicated a potential involvement of MIAT in different signaling pathways and ribosome biogenesis and assembly. These findings suggest that MIAT deregulation may play a pathogenetic role in MM by affecting both proliferation pathways and, indirectly, the translational process. Although MIAT expression levels seem not to be significantly associated with clinical outcome in multivariate analyses, high MIAT expression levels are associated with bortezomib resistance, this suggesting that MIAT targeting could overcome drug resistance in MM. These findings strongly prompt for further studies investigating the significance of MIAT in MM.

lncRNA ST3GAL6‑AS1 promotes invasion by inhibiting hnRNPA2B1‑mediated ST3GAL6 expression in multiple myeloma

Multiple myeloma (MM) is an incurable disease caused by the infiltration of malignant plasma B cells into bone marrow, whose pathogenesis remains largely unknown. Long non‑coding RNAs (lncRNAs) have emerged as important factors in pathogenesis. Our previous study validated that lncRNA ST3 β‑galactoside α‑2,3‑sialyltransferase 6 antisense RNA 1 (ST3GAL6‑AS1) was upregulated markedly in MM. Therefore, the aim of the study was to investigate the molecular mechanisms of ST3GAL6‑AS1 in MM cells. ST3GAL6‑AS1 expression levels in MM cells was detected using reverse transcription‑quantitative PCR. ST3GAL6‑AS1 antisense oligonucleotides and small interfering RNAs were transfected into MM cells to downregulate expression. In vitro assays were performed to investigate the functional role of ST3GAL6‑AS1 in MM cells. RNA pull‑down, RNA immunoprecipitation and comprehensive identification of RNA‑binding proteins using mass spectrometry assays were used to determine the mechanism of ST3GAL6‑AS1‑mediated regulation of underlying targets. It was reported that knockdown of ST3GAL6‑AS1 suppressed the adhesion, migration and invasion ability of MM cells in vitro. Expression of ST3GAL6 was significantly reduced when ST3GAL6‑AS1 was knock downed in MM cells. Moreover, mechanistic investigation showed that ST3GAL6‑AS1 could suppress ST3GAL6 mRNA degradation via interacting with heterogeneous nuclear ribonucleoprotein A2B1 (hnRNPA2B1). The present results suggested that upregulated lncRNA ST3GAL6‑AS1 promotes adhesion and invasion of MM cells by binding with hnRNPA2B1 to regulate ST3GAL6 expression.

Epigenetic silencing of long non-coding RNA BM742401 in multiple myeloma: impact on prognosis and myeloma dissemination

Background

Long non-coding RNA (lncRNA) BM742401 is a tumor suppressor in gastric cancer and chronic lymphocytic leukemia. As the promoter and coding region of BM742401 are fully embedded in a CpG island, we hypothesized that BM742401 is a tumor suppressor lncRNA epigenetically silenced by promoter DNA methylation in multiple myeloma.

Methods

Methylation-specific PCR and quantitative bisulfite pyrosequencing were performed to detect the methylation of BM742401 in normal plasma cells, myeloma cell lines and primary myeloma samples. The expression of BM742401 was measured by qRT-PCR. The function of BM742401 in multiple myeloma cells was analyzed by lentivirus transduction followed by migration assay.

Results

BM742401 methylation was detected in 10 (66.7%) myeloma cell lines but not normal plasma cells, and inversely correlated with expression of BM742401. In primary samples, BM742401 methylation was detected in 3 (12.5%) monoclonal gammopathy of undetermined significance, 9 (15.8%) myeloma at diagnosis and 8 (17.0%) myeloma at relapse/progression. Moreover, BM742401 methylation at diagnosis was associated with inferior overall survival (median OS: 25 vs. 39 months; P = 0.0496). In myeloma cell line JJN-3, stable overexpression of BM742401 by lentivirus transduction resulted in reduced cell migration (P = 0.0001) but not impacting cell death or proliferation.

Conclusions

This is the first report of tumor-specific methylation-mediated silencing of BM742401 in myeloma, which is likely an early event in myelomagenesis with adverse impact on overall survival. Moreover, BM742401 is a tumor suppressor lncRNA by inhibiting myeloma cell migration, hence implicated in myeloma plasma cell homing, metastasis and disease progression.

The functional epigenetic landscape of aberrant gene expression in molecular subgroups of newly diagnosed multiple myeloma

Background

Multiple Myeloma (MM) is a hematological malignancy with genomic heterogeneity and poor survival outcome. Apart from the central role of genetic lesions, epigenetic anomalies have been identified as drivers in the development of the disease.

Methods

Alterations in the DNA methylome were mapped in 52 newly diagnosed MM (NDMM) patients of six molecular subgroups and matched with loci-specific chromatin marks to define their impact on gene expression. Differential DNA methylation analysis was performed using DMAP with a ≥10% increase (hypermethylation) or decrease (hypomethylation) in NDMM subgroups, compared to control samples, considered significant for all the subsequent analyses with p<0.05 after adjusting for a false discovery rate.

Results

We identified differentially methylated regions (DMRs) within the etiological cytogenetic subgroups of myeloma, compared to control plasma cells. Using gene expression data we identified genes that are dysregulated and correlate with DNA methylation levels, indicating a role for DNA methylation in their transcriptional control. We demonstrated that 70% of DMRs in the MM epigenome were hypomethylated and overlapped with repressive H3K27me3. In contrast, differentially expressed genes containing hypermethylated DMRs within the gene body or hypomethylated DMRs at the promoters overlapped with H3K4me1, H3K4me3, or H3K36me3 marks. Additionally, enrichment of BRD4 or MED1 at the H3K27ac enriched DMRs functioned as super-enhancers (SE), controlling the overexpression of genes or gene-cassettes.

Conclusions

Therefore, this study presents the underlying epigenetic regulatory networks of gene expression dysregulation in NDMM patients and identifies potential targets for future therapies.

Long non-coding RNA TUG1 knockdown hinders the tumorigenesis of multiple myeloma by regulating the microRNA-34a-5p/NOTCH1 signaling pathway

Multiple myeloma (MM) is a serious health issue in hematological malignancies. Long non-coding RNA taurine-upregulated gene 1 (TUG1) has been reported to be highly expressed in the plasma of MM patients. However, the functions of TUG1 in MM tumorigenesis along with related molecular basis are still undefined. In this study, increased TUG1 and decreased microRNA-34a-5p (miR-34a-5p) levels in MM tissues and cells were measured by the real-time quantitative polymerase reaction assay. The expression of relative proteins was determined by the Western blot assay. TUG1 knockdown suppressed cell viability, induced cell cycle arrest and cell apoptosis in MM cells, as shown by Cell Counting Kit-8 and flow cytometry assays. Bioinformatics analysis, luciferase reporter assay, and RNA pull-down assay indicated that miR-34a-5p was a target of TUG1 and directly bound to notch receptor 1 (NOTCH1), and TUG1 regulated the NOTCH1 expression by targeting miR-34a-5p. The functions of miR-34a-5p were abrogated by TUG1 upregulation. Moreover, TUG1 loss impeded MM xenograft tumor growth in vivo by upregulating miR-34a-5p and downregulating NOTCH1. Furthermore, TUG1 depletion inhibited the expression of Hes-1, Survivin, and Bcl-2 protein in MM cells and xenograft tumors. TUG1 knockdown inhibited MM tumorigenesis by regulating the miR-34a-5p/NOTCH1 signaling pathway in vitro and in vivo, deepening our understanding of the TUG1 function in MM.

Expression Pattern and Biological Significance of the lncRNA ST3GAL6-AS1 in Multiple Myeloma

The biological impact of long non-coding RNAs (lncRNAs) in multiple myeloma (MM) is becoming an important aspect of investigation, which may contribute to the understanding of the complex pathobiology of the disease whilst also providing novel potential therapeutic targets. Herein, we investigated the expression pattern and the biological significance of the lncRNA ST3 beta-galactoside alpha-2,3 sialyltransferase 6 antisense RNA 1 (ST3GAL6-AS1) in MM. We documented a high ST3GAL6-AS1 expression level in MM compared to normal plasma cells (PCs) or other hematological malignancies. Transcriptome analyses of MM PCs from patients included in the CoMMpass database indicated a potential involvement of ST3GAL6-AS1 in MAPK signaling and ubiquitin-mediated proteolysis pathways. ST3GAL6-AS1 silencing by LNA-gapmeR antisense oligonucleotides inhibits cell proliferation and triggers apoptosis in MM cell line. Notably, ST3GAL6-AS1 silencing in vitro displayed the down-regulation of the MAPK pathway and protein ubiquitination. These data suggest that ST3GAL6-AS1 deregulation may play a pathogenetic role in MM by affecting both proliferation pathways and circuits fundamental for PC survival. However, ST3GAL6-AS1 expression levels seem not to be significantly associated with clinical outcome and its targeting appears to exert antagonistic effects with proteasome inhibitors used in MM. These findings strongly urge the need for further studies investigating the relevance of ST3GAL6-AS1 in MM.

FAM46C controls antibody production by the polyadenylation of immunoglobulin mRNAs and inhibits cell migration in multiple myeloma

FAM46C, frequently mutated in multiple myeloma (MM), has recently been shown to encode a non‐canonical poly(A) polymerase (ncPAP). However, its target mRNAs and its role in MM pathogenesis remain mostly unknown. Using CRISPR‐Cas9 technology and gene expression analysis, we found that the inactivation of FAM46C in MM down‐regulates immunoglobulins (Igs) and several mRNAs encoding ER‐resident proteins, including some involved in unfolded protein response and others that affect glycosylation. Interestingly, we show that FAM46C expression is induced during plasma cell (PC) differentiation and that Ig mRNAs encoding heavy and light chains are substrates of the ncPAP, as revealed by poly(A) tail‐length determination assays. The absence of the ncPAP results in Ig mRNA poly(A) tail‐shortening, leading to a reduction in mRNA and protein abundance. On the other hand, loss of FAM46C up‐regulates metastasis‐associated lncRNA MALAT1 and results in a sharp increase in the migration ability. This phenotype depends mainly on the activation of PI3K/Rac1 signalling, which might have significant therapeutic implications. In conclusion, our results identify Ig mRNAs as targets of FAM46C, reveal an important function of this protein during PC maturation to increase antibody production and suggest that its role as a tumour suppressor might be related to the inhibition of myeloma cell migration.

Impact of Natural Dietary Agents on Multiple Myeloma Prevention and Treatment: Molecular Insights and Potential for Clinical Translation

Chemoprevention is based on the use of non-toxic, pharmacologically active agents to prevent tumor progression. In this regard, natural dietary agents have been described by the most recent literature as promising tools for controlling onset and progression of malignancies. Extensive research has been so far performed to shed light on the effects of natural products on tumor growth and survival, disclosing the most relevant signal transduction pathways targeted by such compounds. Overall, anti-inflammatory, anti-oxidant and cytotoxic effects of dietary agents on tumor cells are supported either by results from epidemiological or animal studies and even by clinical trials. Multiple myeloma is a hematologic malignancy characterized by abnormal proliferation of bone marrow plasma cells and subsequent hypercalcemia, renal dysfunction, anemia, or bone disease, which remains incurable despite novel emerging therapeutic strategies. Notably, increasing evidence supports the capability of dietary natural compounds to antagonize multiple myeloma growth in preclinical models of the disease, underscoring their potential as candidate anti-cancer agents. In this review, we aim at summarizing findings on the anti-tumor activity of dietary natural products, focusing on their molecular mechanisms, which include inhibition of oncogenic signal transduction pathways and/or epigenetic modulating effects, along with their potential clinical applications against multiple myeloma and its related bone disease.

Deregulated Expression of Long Non-coding RNA HOX Transcript Antisense RNA (HOTAIR) in Egyptian Patients with Multiple Myeloma

Increasing evidence of involvement of non-coding RNAs, especially long non-coding RNAs (lncRNAs), in the molecular biology of various malignancies have been recently reported. Their utilization as markers for diagnosis, prognosis and evaluation of treatment response was widely investigated. As the impact of lncRNA HOTAIR on multiple myeloma (MM) was not properly highlighted, we aimed to explore the expression levels of HOTAIR in three groups of MM patients and to analyze its relationship to different patients' characteristics. Plasma samples were withdrawn from 24 newly diagnosed MM patients, 23 post-therapy patients in complete response (CR) or very good partial response (VGPR) and 15 patients who had either progressive disease (PD) or relapse. The expression of lncRNA HOTAIR in MM patients and 20 healthy controls was analyzed by quantitative reverse transcription polymerase chain reactions. HOTAIR was significantly upregulated in newly diagnosed and PD/relapse categories in comparison with controls and MM patients who had achieved CR or VGPR (P < 0.001). Furthermore; HOTAIR expression levels correlated with the percentage of malignant plasma cells in bone marrow (P = 0.006) and disease stage (ISS stage) (P = 0.031). HOTAIR may be employed as  prognostic molecular marker and novel therapeutic tool for newly diagnosed MM patients.

Increased lncRNA HOTAIR expression promotes the chemoresistance of multiple myeloma to dexamethasone by regulating cell viability and apoptosis by mediating the JAK2/STAT3 signaling pathway

Multiple studies have shown that HOX antisense intergenic RNA (HOTAIR), an oncogenic long non‑coding RNA (lncRNA), is dysregulated in leukemia and is involved in tumor progression. The aim of the present study was to determine whether HOTAIR could serve as a novel biomarker for the diagnosis of multiple myeloma (MM), and to investigate its role in regards to MM cell viability and chemoresistance to dexamethasone (DEX). The results revealed that the expression of HOTAIR was significantly upregulated in serum, bone marrow and primary CD138+ cells from MM patients compared with those from normal controls as determined by qPCR. HOTAIR expression was obviously increased in MM cell lines compared to that in normal plasma cells. ROC curve analysis showed that the serum level of HOTAIR exhibited a higher diagnostic value for MM. Furthermore, loss‑of‑functional assays indicated that HOTAIR inhibition suppressed MM cell viability by arresting the cell cycle at the G0/G1 phase as determined by cell viability assay and flow cytometry. An in‑depth study revealed that knockdown of HOTAIR led to decreased chemoresistance of DEX in MM cells by regulating the JAK2/STAT3 signaling pathway. Taken together, our findings suggest that upregulation of serum HOTAIR may prove to be a novel biomarker for the diagnosis of MM. HOTAIR promoted MM cell viability and increased chemoresistance of MM to DEX via the JAK2/STAT3 signaling pathway, indicating HOTAIR may also serve as a potential therapeutic target for MM.

Long non-coding RNA NEAT1 targeting impairs the DNA repair machinery and triggers anti-tumor activity in multiple myeloma

The biological role and therapeutic potential of long non-coding RNAs (lncRNAs) in multiple myeloma (MM) are still open questions. Herein, we investigated the functional significance of the oncogenic lncRNA nuclear paraspeckle assembly transcript 1 (NEAT1) in MM. Our study demonstrates that NEAT1 expression level is higher in MM than in the majority of hematological malignancies. NEAT1 silencing by novel LNA-gapmeR antisense oligonucleotide inhibits MM cell proliferation and triggers apoptosis in vitro and in vivo murine MM model as well. By transcriptome analyses, we found that NEAT1 targeting downregulates genes involved in DNA repair processes including the Homologous Recombination pathway, which in turn results in massive DNA damage. These findings may explain the synergistic impact on apoptosis observed in MM cell lines co-treated with inhibitors of both NEAT1 and PARP. The translational significance of NEAT1 targeting is further underlined by its synergistic effects with the most common drugs administered for MM treatment, including bortezomib, carfilzomib, and melphalan. Overall, NEAT1 silencing is associated with a chemo-sensitizing effect of both conventional and novel therapies, and its targeting could therefore represent a promising strategy for novel anti-MM therapeutic options.

Noncoding RNAs in Extracellular Fluids as Cancer Biomarkers: The New Frontier of Liquid Biopsies

The last two decades of cancer research have been devoted in two directions: (1) understanding the mechanism of carcinogenesis for an effective treatment, and (2) improving cancer prevention and screening for early detection of the disease. This last aspect has been developed, especially for certain types of cancers, thanks also to the introduction of new concepts such as liquid biopsies and precision medicine. In this context, there is a growing interest in the application of alternative and noninvasive methodologies to search for cancer biomarkers. The new frontiers of the research lead to a search for RNA molecules circulating in body fluids. Searching for biomarkers in extracellular body fluids represents a better option for patients because they are easier to access, less painful, and potentially more economical. Moreover, the possibility for these types of samples to be taken repeatedly, allows a better monitoring of the disease progression or treatment efficacy for a better intervention and dynamic treatment of the patient, which is the fundamental basis of personalized medicine. RNA molecules, freely circulating in body fluids or packed in microvesicles, have all the characteristics of the ideal biomarkers owing to their high stability under storage and handling conditions and being able to be sampled several times for monitoring. Moreover, as demonstrated for many cancers, their plasma/serum levels mirror those in the primary tumor. There are a large variety of RNA species noncoding for proteins that could be used as cancer biomarkers in liquid biopsies. Among them, the most studied are microRNAs, but recently the attention of the researcher has been also directed towards Piwi-interacting RNAs, circular RNAs, and other small noncoding RNAs. Another class of RNA species, the long noncoding RNAs, is larger than microRNAs and represents a very versatile and promising group of molecules which, apart from their use as biomarkers, have also a possible therapeutic role. In this review, we will give an overview of the most common noncoding RNA species detectable in extracellular fluids and will provide an update concerning the situation of the research on these molecules as cancer biomarkers.

MicroRNA-765 is pregulated in multiple myeloma and serves an oncogenic role by directly targeting SOX6

Increasing evidence has revealed that microRNAs (miRNAs) are closely associated with multiple myeloma (MM) pathogenesis and progression. Therefore, an in-depth understanding of the biological functions of miRNAs in MM may be helpful for the identification of promising therapeutic techniques for patients with MM. miRNA-765 (miR-765) has been reported to be dysregulated in many types of human cancer. However, the expression pattern, specific roles and underlying mechanisms of miR-765 in MM remain largely unknown. In the present study, plasma miR-765 significantly increased in patients with MM and cell lines. The downregulation of miR-765 in MM cells attenuated proliferation and promoted apoptosis. Bioinformatics analysis predicted that SRY-Box 6 (SOX6) was a putative target of miR-765. This was experimentally verified using a luciferase reporter assay, reverse transcription-quantitative PCR and western blot analysis. Furthermore, plasma SOX6 was downregulated in patients with MM and the downregulation of SOX6 was inversely correlated with that of miR-765 expression. Furthermore, SOX6 knockdown markedly abrogated the effects of miR-765 underexpression on cell proliferation and apoptosis in MM. The current study demonstrated that miR-765 serves an oncogenic role in MM progression by directly targeting SOX6, suggesting that miR-765 may be a potential therapeutic target for MM prevention and treatment.

Decreased expression of long noncoding RNA XLOC_013703 promotes cell growth via NF-κB pathway in multiple myeloma

Long noncoding RNAs (lncRNAs) are dysregulated in cancer and involved in oncogenic or tumor inhibitory processes. The aim of the study was to investigate the expression pattern of lncRNA XLOC_013703 in multiple myeloma (MM) and to evaluate its biological role and potential significance. We found that XLOC_013703 was significantly decreased in CD138 positive plasma cells and serum of MM patients compared to normal controls, and the decreased XLOC_013703 expression was correlated with β2-MG, serum-free light chain (s-FLC) and revised international staging system. RNA-fluorescence in situ hybridization results revealed that XLOC_013703 was distributed both in the nucleus and in the cytoplasm of MM cells including H929, RPMI8226, and U266. Overexpression of XLOC_013703 inhibited the proliferation of U266 cells and blocked the cell cycle in G1 stage, thus contributing to MM cell apoptosis. By contrast, knockdown of XLOC_013703 promoted the growth of H929 cells. Western blot analysis confirmed that the expression of p-IκBα and nuclear P65 was substantially increased in shRNA transfection groups compared to control groups, whereas overexpression of XLOC_013703 reduced these expressions. In conclusion, we confirmed that the decreased expression of a novel lncRNA, XLOC_013703, in MM. XLOC_013703 was involved in MM cell survival and proliferation via nuclear factor-κB pathway which represents a potential therapeutic target for MM. © 2019 IUBMB Life, 71(9):1240-1251, 2019.