Multiple myeloma (MM) is characterized by the impaired osteogenic differentiation of mesenchymal stromal cells (MSCs). However, the underlying molecular mechanisms are still poorly understood. Long noncoding RNAs (lncRNAs) are emerging as important regulatory molecules in tumor-suppressor and oncogenic pathways. Here we showed that MSCs from MM expressed less lncRNA MEG3 relative to those from normal donors during osteogenic differentiation. To evaluate the effect of MEG3 on osteogenesis, bone marrow MSCs with enhanced or reduced MEG3 were prepared. We observed that MEG3 knockdown significantly reduced the expression of key osteogenic markers, including Runt-related transcription factor 2, osterix, and osteocalcin, while overexpression of MEG3 enhanced their expression. Additionally, MEG3 knockdown decreased BMP4 transcription. Here we showed that MEG3 was critical for SOX2 transcriptional repression of the BMP4. MEG3, which is located near the BMP4 gene, could dissociate the transcription factor SOX2 from the BMP4 promoter. A stable complex containing the MEG3, SOX2, and the SOX2 consensus site of BMP4 suggested that MEG3 activated transcriptional activity by directly influencing SOX2 activity. By using assays such as luciferase, chromatin immunoprecipitation, and RNA immunoprecipitation, we showed that MEG3 had a critical function in a mechanism of promoter-specific transcriptional activation. These results suggested that MEG3 played an essential role in osteogenic differentiation in bone marrow MSCs, partly by activating BMP4 transcription. Our data provided novel evidence for the biological and clinical significance of lncRNA MEG3 expression as a potential biomarker for identifying patients with MM and as a potential therapeutic target in MM. Stem Cells 2015;33:1985–1997

Extranodal natural killer/T‐cell lymphoma, nasal‐type (ENKTL) is a distinct subtype of non‐Hodgkin lymphoma and most of the patients presented localized disease. Combined modality therapy (CMT), namely chemotherapy combined with radiotherapy, has been recommended for patients with early‐stage ENKTL. However, the optimal CMT has not been fully clarified. This study reports the efficacy and toxicity of sequential P‐GEMOX (pegaspargase, gemcitabine and oxaliplatin) and radiotherapy in a large Chinese cohort comprising of 202 patients diagnosed with early‐stage ENKTL from six medical centers. The observed best overall response rate was 96.0% and 168 (83.2%) patients achieved complete remission. With a median follow‐up of 44.1 months, the 3‐year progression‐free survival (PFS) and overall survival (OS) were 74.6% and 85.2%, respectively. Multivariate analysis suggested that extensive primary tumor (PFS, hazard ratio [HR] 3.660, 95% CI 1.820–7.359, p < 0.001; OS, HR 3.825, 95% CI 1.442–10.148, p = 0.007) and Eastern Cooperative Oncology Group performance status ≥ 2 (PFS, 3.042, 95% CI 1.468–6.306, p = 0.003; OS, HR 3.983, 95% CI 1.678–9.457, p = 0.02) were independent prognostic factors for survival outcomes. Among the established prognostic models for ENKTL, the nomogram‐revised risk index model had optimal prognostic risk stratification ability (PFS, p < 0.001; OS, p < 0.001) and relatively balanced population distribution. The adverse events of this CMT were well‐tolerated and manageable. In conclusion, sequential P‐GEMOX and radiotherapy showed favorable efficacy with acceptable toxicity, and could be an effective treatment option for early‐stage ENKTL patients.

High-dose methotrexate (HD-MTX) serves as the cornerstone of central nervous system lymphoma (CNSL) treatment, but its efficacy is limited due to low blood–brain barrier (BBB) penetration and adverse effects. This study is focused on an exosome-based drug delivery approach aimed at enhancing BBB permeability, thereby reducing the required dosage of methotrexate (MTX) while ensuring specific targeting of CNSL. Human adipose-derived mesenchymal stem cells (hAMSCs) were modified with a lentiviral vector encoding anti-CD19, incorporated into exosomes characterized by colloidal gold immunoelectron microscopy and Nano flow cytometry. MTX loaded into anti-CD19-Exos via co-incubation, assessed for loading and encapsulation efficiencies using HPLC. In vitro BBB model constructed using hCMEC/D3 and astrocytes to investigate BBB permeability. In vivo efficacy of anti-CD19-Exo-MTX evaluated in intracranial CNSL models using MRI. Biodistribution tracked with DiR-labeled exosomes, drug concentration in CSF measured by HPLC. LC-MS/MS identified and characterized exosomal proteins analyzed using GO Analysis. Neuroprotective effects of exosomal proteins assessed with TUNEL and Nissl staining on hippocampal neurons in CNSL models. Liver and kidney pathology, blood biochemical markers, and complete blood count evaluated exosomal protein effects on organ protection and MTX-induced myelosuppression. We generated anti-CD19-Exo derived from hAMSCs. These adapted exosomes effectively encapsulated MTX, enhancing drug accessibility within lymphoma cells and sustained intracellular accumulation over an extended period. Notably, anti-CD19-Exo-MTX interacted with cerebrovascular endothelial cells and astrocytes of the BBB, leading to endocytosis and facilitating the transportation of MTX across the barrier. Anti-CD19-Exo-MTX outperformed free MTX in vitro, exhibiting a more potent lymphoma-suppressive effect (P < 0.05). In intracranial orthotopic CNSL models, anti-CD19-Exo-MTX exhibited a significantly reduced disease burden compared to both the MTX and Exo-MTX groups, along with prolonged overall survival (P < 0.05). CSF drug concentration analysis demonstrated enhanced stability and longer-lasting drug levels for anti-CD19-Exo-MTX. Anti-CD19-Exo-MTX exhibited precise CNSL targeting with no organ toxicity. Notably, our study highlighted the functional potential of reversal effect of hAMSCs-exosomes on MTX-induced neurotoxicity, hepatic and renal impairment, and myelosuppression. We present anti-CD19-Exo-MTX as a promising exosome-based drug delivery platform that enhances BBB permeability and offers specific targeting for effective CNSL treatment with reduced adverse effects.