Integrative analysis of the prognostic value and immune microenvironment of mitophagy-related signature for multiple myeloma.

BACKGROUND: Multiple myeloma (MM) is a fatal malignant tumor in hematology. Mitophagy plays vital roles in the pathogenesis and drug sensitivity of MM. METHODS: We acquired transcriptomic expression data and clinical index of MM patients from NCI public database, and 36 genes involved in mitophagy from the gene set enrichment analysis (GSEA) database. Least absolute shrinkage and selection operator (LASSO) Cox regression analysis was conducted to construct a risk score prognostic model. Kaplan-Meier survival analysis and receiver operation characteristic curves (ROC) were conducted to identify the efficiency of prognosis and diagnosis. ESTIMATE algorithm and immune-related single-sample gene set enrichment analysis (ssGSEA) was performed to uncover the level of immune infiltration. QRT-PCR was performed to verify gene expression in clinical samples of MM patients. The sensitivity to chemotherapy drugs was evaluated upon the database of the genomics of drug sensitivity in cancer (GDSC). RESULTS: Fifty mitophagy-related genes were differently expressed in two independent cohorts. Ten out of these genes were identified to be related to MM overall survival (OS) rate. A prognostic risk signature model was built upon on these genes: VDAC1, PINK1, VPS13C, ATG13, and HUWE1, which predicted the survival of MM accurately and stably both in training and validation cohorts. MM patients suffered more adverse prognosis showed more higher risk core. In addition, the risk score was considered as an independent prognostic element for OS of MM patients by multivariate cox regression analysis. Functional pathway enrichment analysis of differentially expressed genes (DEGs) based on risk score showed terms of cell cycle, immune response, mTOR pathway, and MYC targets were obviously enriched. Furthermore, MM patients with higher risk score were observed lower immune scores and lower immune infiltration levels. The results of qRT-PCR verified VDAC1, PINK1, and HUWE1 were dysregulated in new diagnosed MM patients. Finally, further analysis indicated MM patients showed more susceptive to bortezomib, lenalidomide and rapamycin in high-risk group. CONCLUSION: Our research provided a neoteric prognostic model of MM based on mitophagy genes. The immune infiltration level based on risk score paved a better understanding of the participation of mitophagy in MM.

PRMT1 methylation of WTAP promotes multiple myeloma tumorigenesis by activating oxidative phosphorylation via m6A modification of NDUFS6.

Epigenetic modifications play important roles during the pathogenesis of multiple myeloma (MM). Herein, we found that protein arginine methyltransferase 1 (PRMT1) was highly expressed in MM patients, which was positively correlated with MM stages. High PRMT1 expression was correlated with adverse prognosis in MM patients. We further showed that silencing PRMT1 inhibited MM proliferation and tumorigenesis in vitro and in vivo. Mechanistically, we revealed that the knockdown of PRMT1 reduced the oxidative phosphorylation (OXPHOS) of MM cells through NDUFS6 downregulation. Meanwhile, we identified that WTAP, a key component of the m6A methyltransferase complex, was methylated by PRMT1, and NDUFS6 was identified as a bona fide m6A target of WTAP. Finally, we found that the combination of PRMT1 inhibitor and bortezomib synergistically inhibited MM progression. Collectively, our results demonstrate that PRMT1 plays a crucial role during MM tumorigenesis and suggeste that PRMT1 could be a potential therapeutic target in MM.

N6-methyladenosine reader YTHDF2 promotes multiple myeloma cell proliferation through EGR1/p21cip1/waf1/CDK2-Cyclin E1 axis-mediated cell cycle transition.

Multiple myeloma (MM) is the second most common hematological malignancy. N6-methyladenosine (m6A) is the most abundant RNA modification. YTH domain-containing family protein 2 (YTHDF2) recognizes m6A-cotaining RNAs and accelerates degradation to regulate cancer progression. However, the role of YTHDF2 in MM remains unclear. We investigated the expression levels and prognostic role of YTHDF2 in MM, and studied the effect of YTHDF2 on MM proliferation and cell cycle. The results showed that YTHDF2 was highly expressed in MM and was an independent prognostic factor for MM survival. Silencing YTHDF2 suppressed cell proliferation and caused the G1/S phase cell cycle arrest. RNA immunoprecipitation (RIP) and m6A-RIP (MeRIP) revealed that YTHDF2 accelerated EGR1 mRNA degradation in an m6A-dependent manner. Moreover, overexpression of YTHDF2 promoted MM growth via the m6A-dependent degradation of EGR1 both in vitro and in vivo. Furthermore, EGR1 suppressed cell proliferation and retarded cell cycle by activating p21cip1/waf1 transcription and inhibiting CDK2-cyclinE1. EGR1 knockdown could reverse the inhibited proliferation and cell cycle arrest upon YTHDF2 knockdown. In conclusion, the high expression of YTHDF2 promoted MM cell proliferation via EGR1/p21cip1/waf1/CDK2-cyclin E1 axis-mediated cell cycle transition, highlighting the potential of YTHDF2 as an effective prognostic biomarker and a promising therapeutic target for MM.

Serum soluble BCMA can be used to monitor relapse of multiple myeloma patients after chimeric antigen receptor T-cell immunotherapy.

PURPOSE: Chimeric antigen receptor T-cell (CAR-T) therapy has been proven very effective in treating hematologic malignancies. Ciltacabtagene autoleucel (cilta-cel), a second-generation CAR-T cell with double B cell maturation antigen (BCMA) targeting binding domains, showed an 88% overall response rate (ORR) in patients with relapsed/refractory multiple myeloma (MM), which were carried out in our institute. This study aimed to assess the prognostic potential of soluble BCMA (sBCMA) in serum as a biomarker in MM after CAR-T therapy. PATIENTS AND METHODS: Serum samples (n = 44) from MM patients were collected before and after CAR-T therapy. The level of sBCMA was analyzed by enzyme-linked immunosorbent assay (ELISA). Additionally, three patients' long-term longitudinal analysis were performed. RESULTS: Serum sBCMA level was correlated with the percentage of malignant plasma cells in bone marrow (r = 0.613). After CAR-T infusion, the sBCMA level in serum of MM patients decreased markedly (median: 508,513 pg/mL before CAR-T infusion, 89,198 pg/mL in the first month, 8448 pg/mL in the second months, and 6010 pg/mL in the third month after CAR-T infusion). In patients who obtained objective response (≥ PR), re-elevated sBCMA indicated the possibility of disease recurrence. At a cutoff 69,326.27 pg/mL, sBCMA shows high sensitivity (87.5%) and specificity (88.5%) for identifying relapse of MM after CAR-T therapy. CONCLUSION: Our results suggested that serum sBCMA level changes in response to the clinical status of MM patients after anti-BCMA CAR-T therapy. Furthermore, sBCMA may be a auxiliary biomarker for disease monitoring in MM patients after CAR-T therapy.

Novel insights into roles of N6-methyladenosine reader YTHDF2 in cancer progression.

N6-methyladenosine (m6A) is the most abundant RNA modification. M6A RNA methylation is reversible: m6A is installed by "writers", removed by "erasers", and recognized by "readers". Readers are executors to regulate RNA metabolism by recognizing specific m6A sites, including RNA splicing, export, translation and decay. YTHDF2 is the first identified m6A reader protein. YTHDF2 interacts with m6A-containing transcripts to accelerate the degradation process and regulate various biological processes, such as viral infection, stem cell development and cancer progression. Although there are some reviews about m6A modification in physiological and pathological processes, few reviews focus on roles of YTHDF2 in cancers to date. Therefore, in this review, we attempted to systematically summarize m6A reader protein YTHDF2: its structure, mechanisms in regulating RNA metabolism, roles in cancer progression and potential application for cancer treatment, which might inspire new ideas for m6A research in cancers and provide novel insights into cancer treatment.

Using Circ-ANAPC7 as a Novel Type of Biomarker in the Monitoring of Acute Myeloid Leukemia.

INTRODUCTION: Circular RNAs (circRNAs) are a novel class of RNAs which occupy gene expression at the transcriptional or post-transcriptional level, involve in many physiological processes, and participate in many diseases, especially in cancer. Our previous study showed 1 altered circRNA named circ-anaphase promoting complex subunit 7 (ANAPC7) that was upregulated in acute myeloid leukemia (AML). To further clear the expression and clinical significance of circ-ANAPC7, we enlarged the sample size and illuminated the diagnostic and monitoring value of circ-ANAPC7 in AML. METHODS: Real-time quantitative reverse transcription-polymerase chain reaction (RT-qPCR) was supposed to confirm the expression of circ-ANAPC7 of AML patients. We assessed the correlation of circ-ANAPC7 and clinical variables using the Spearman correlation test. The receiver operating characteristic (ROC) curve was carried out to evaluate the diagnostic value. RESULTS: Circ-ANAPC7 was first found to be upregulated in AML, and its expression was correlated to white blood cell counts in peripheral blood and blast percentage in bone marrow. ROC curve analysis revealed that circ-ANAPC7 has a significant value of auxiliary AML diagnosis (area under the curve = 0.915, p < 0.001). Furthermore, the expression level of circ-ANAPC7 was changed accompanied with disease condition transformation. CONCLUSION: Circ-ANAPC7 was upregulated in newly diagnosed and relapsed AML. It may serve as potential biomarkers for AML patient's diagnosis and monitoring.

lncRNA ST3GAL6­AS1 promotes invasion by inhibiting hnRNPA2B1­mediated 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 non­coding RNAs (lncRNAs) have emerged as important factors in pathogenesis. Our previous study validated that lncRNA ST3 ß­galactoside α­2,3­sialyltransferase 6 antisense RNA 1 (ST3GAL6­AS1) was upregulated markedly in MM. Therefore, the aim of the study was to investigate the molecular mechanisms of ST3GAL6­AS1 in MM cells. ST3GAL6­AS1 expression levels in MM cells was detected using reverse transcription­quantitative PCR. ST3GAL6­AS1 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 ST3GAL6­AS1 in MM cells. RNA pull­down, RNA immunoprecipitation and comprehensive identification of RNA­binding proteins using mass spectrometry assays were used to determine the mechanism of ST3GAL6­AS1­mediated regulation of underlying targets. It was reported that knockdown of ST3GAL6­AS1 suppressed the adhesion, migration and invasion ability of MM cells in vitro. Expression of ST3GAL6 was significantly reduced when ST3GAL6­AS1 was knock downed in MM cells. Moreover, mechanistic investigation showed that ST3GAL6­AS1 could suppress ST3GAL6 mRNA degradation via interacting with heterogeneous nuclear ribonucleoprotein A2B1 (hnRNPA2B1). The present results suggested that upregulated lncRNA ST3GAL6­AS1 promotes adhesion and invasion of MM cells by binding with hnRNPA2B1 to regulate ST3GAL6 expression.

IGF-1 promotes multiple myeloma progression through PI3K/Akt-mediated epithelial-mesenchymal transition.

AIMS: To investigate the role and mechanism of insulin-like growth factor 1(IGF-1)-mediated EMT on multiple myeloma (MM) growth and metastasis. MATERIALS AND METHODS: The expression data from GEO datasets were utilized to explore the expression levels of IGF-1 and epithelial-mesenchymal transition (EMT) markers in MM. Western blotting and flow cytometry analysis were performed to detect the protein levels of EMT markers as well as key components of the PI3K/Akt pathway. Cell proliferation ability was assessed using colony formation assay and EdU incorporation assays. Transwell migration and invasion assays were performed to assess cell metastasis properties. Vimentin was knocked down by using electro-transfection with small interfering RNA (siRNA) to detect the effect of IGF-1-mediated EMT on MM cell growth and metastasis. KEY FINDINGS: First of all, the analysis of GEO database revealed that IGF-1 was excessively expressed and closely correlated with the expression of the EMT markers in MM patients. Furthermore, we demonstrated that IGF-1 enhanced the acquisition of mesenchymal features in a time-dependent manner. Additionally, in vitro studies revealed that IGF-1-mediated mesenchymal phenotype promoted MM migration, invasion and colony formation. Finally, the mechanism study showed PI3K/Akt signaling pathway was involved in the IGF-1-induced EMT in MM cells. SIGNIFICANCE: IGF-1-induced mesenchymal phenotype contributed to MM progression via the PI3K/Akt pathway regulation.

Focusing on long non-coding RNA dysregulation in newly diagnosed multiple myeloma.

AIMS: Multiple myeloma (MM) is an incurable hematological cancer with a higher rate of relapse. Alterations in the function of long non-coding RNAs (lncRNAs) promote the progression and metastasis of cancer. We carry out this study to explore the expression profile of differently expressed lncRNAs in newly diagnosed MM. MAIN METHODS: The Bone marrows we analyzed were obtained from five MM and five IDA patients (serving as controls). Arraystar Human LncRNA Array V4.0 was used to profile expression of lncRNAs and mRNAs. Gene ontology (GO) and pathway analysis were utilized to understand the biological roles of differently expressed genes, while Database for Annotation, Visualization and Integrated Discovery (DAVID) was used for constructing the lncRNA-mRNA co-expression network. Quantitative polymerase chain reaction (qRT-PCR) was performed to confirm the expressions of dysregulated lncRNAs. KEY FINDINGS: Bioinformatic analysis of the lncRNA expression identified >3000 dysregulated lncRNAs (difference ≥ 2-fold) in MM samples. GO and pathway analysis revealed that ECM-receptor and cell cycle pathway-related genes were significantly associated with MM. Four dysregulated lncRNAs were confirmed by qRT-PCR. Among them, the expression of ST3GAL6-AS1, LAMA5-AS1and RP11-175D17.3wereassociated with stage and risk status of MM. On the basis of GEO public database analysis, LAMA5-AS1 was related with an overall survival rate of MM patients. SIGNIFICANCE: These results reveal the feasible functions of lncRNAs in pathogenesis of MM. Further studies are required to explore whether these lncRNAs could serve as candidate therapeutic targets and new molecular biomarkers for MM.