miR-34a promotes the immunosuppressive function of multiple myeloma-associated macrophages by dampening the TLR-9 signaling.

BACKGROUND: Promising outcomes have been observed in multiple myeloma (MM) with the use of immunotherapies, specifically chimeric antigen receptor T (CAR-T) cell therapy. However, a portion of MM patients do not respond to CAR-T therapy, and the reasons for this lack of response remain unclear. The objective of this study was to investigate the impact of miR-34a on the immunosuppressive polarization of macrophages obtained from MM patients. METHODS: The levels of miR-34a and TLR9 (Toll-like receptor 9) were examined in macrophages obtained from both healthy individuals and patients with MM. ELISA was employed to investigate the cytokine profiles of the macrophage samples. Co-culture experiments were conducted to evaluate the immunomodulatory impact of MM-associated macrophages on CAR-T cells. RESULTS: There was an observed suppressed activation of macrophages and CD4+ T lymphocytes in the blood samples of MM patients. Overexpression of miR-34a in MM-associated macrophages dampened the TLR9 expression and impaired the inflammatory polarization. In both the co-culture system and an animal model, MM-associated macrophages suppressed the activity and tumoricidal effect of CAR-T cells in a miR-34a-dependent manner. CONCLUSION: The findings imply that targeting the macrophage miR-34a/TLR9 axis could potentially alleviate the immunosuppression associated with CAR-T therapy in MM patients.

Treg-derived TGF-ß1 dampens cGAS-STING signaling to downregulate the expression of class I MHC complex in multiple myeloma.

Multiple myeloma (MM) progression involves diminished tumor antigen presentation and an immunosuppressive microenvironment, characterized by diminished expression of major histocompatibility complexes (MHC) class I molecule and elevated programmed death ligand 1 (PDL1) in MM cells, along with an enriched population of regulatory T cells (Tregs). To investigate Treg's influence on MM cells, we established a co-culture system using Tregs from MM patients and the MM cell lines (MM.1S and SK-MM-1) in vitro and assessed the effects of intervening in the relevant pathways connecting Tregs and MM cells in vivo. In vitro, Tregs induced transforming growth factor beta-1 (TGF-ß1) production, downregulated MHC I members, and increased PDL1 expression in MM cells. Treg-derived TGF-ß1 suppressed the cGAS-STING pathway, contributing to the loss of MHC I molecule expression and PDL1 upregulation. Correspondingly, neutralizing TGF-ß1 or activating the cGAS-STING pathway restored MHC I and PDL1 expression, effectively countering the pro-tumorigenic effect of Tregs on MM cells in vivo. These data elucidated how Tregs influence tumor antigen presentation and immunosuppressive signal in MM cells, potentially providing therapeutic strategies, such as neutralizing TGF-ß1 or activating the cGAS-STING pathway, to address the immune escape and immunosuppressive dynamics in MM.

Dysregulation of LINC00470 and METTL3 promotes chemoresistance and suppresses autophagy of chronic myelocytic leukaemia cells.

Cytoplasmic lncRNAs have been found to directly interact with target mRNAs and regulate their stability. In this study, we aimed to study the molecular mechanism underlying the function of m6 A as a central regulator in chemoresistance and CML proliferation. In this study, we established three mice groups (control group, ADR-R group and ADR-R + shLINC00470 group). We detected PTEN mRNA expression in the presence of LINC00470 in the mice models, as well as in the KCL22 and K562 cells. LINC00470 was significantly enriched for PTEN mRNA to exhibit a negative regulatory relationship between LINC00470 and PTEN mRNA. However, the alteration of LINC00470 had no effect on the luciferase activity of PTEN promoter, while the half-life of PTEN mRNA was affected. It was further validated that LINC00470 down-regulated PTEN expression by positively regulating the m6A modification of PTEN mRNA via RNA methyltransferase METTL3. Moreover, the relative expression of LC3II, Beclin-1, ATG7 and ATG5 was all decreased in cells treated with LINC00470, and down-regulated PTEN expression was observed in chemo-resistant cells, while the expression of PTEN was rescued by the transfection of shMETTL3 into chemo-resistant cells. Moreover, the knockdown of METTL3 also restored the normal level of PTEN m6 A modification and LINC00470 expression in chemo-resistant cells. In conclusion, our results demonstrated the molecular mechanism underlying the effect of LINC00470 on CML by reducing the PTEN stability via RNA methyltransferase METTL3, thus leading to the inhibition of cell autophagy while promoting chemoresistance in CML.

Effect of co­culture with amniotic epithelial cells on the biological characteristics of amniotic mesenchymal stem cells.

The aim of the present study was to investigate the effect of co­culture with amniotic epithelial cells (AECs) on the biological characteristics of amniotic mesenchymal stem cells (AMSCs), to compare the expression of C­X­C motif chemokine receptor 4 (CXCR4) in co­cultured AMSCs and to investigate the roles of the stromal cell­derived factor­1 (SDF­1)/CXCR4 axis in the homing and migration of AMSCs. AMSCs were isolated from human amniotic membranes, purified and then differentiated into osteoblasts and adipocytes in vitro, which was verified by von Kossa Staining and Oil Red O staining. Cell viability was measured by Cell Counting kit­8 and trypan blue assays at 24, 48 and 72 h, the expression of CXCR4 was analyzed by immunofluorescence­based flow cytometry and reverse transcription­quantitative polymerase chain reaction, and the migration ability of AMSCs in vitro was observed by a migration assay. The results demonstrated that cell viability (at 48 and 72 h) and survival (at 24, 48 and 72 h) in the co­culture and serum groups were higher compared with the serum­free group. Furthermore, CXCR4 mRNA and protein expression, and migration along the SDF­1 gradient, in the co­culture and serum­free groups were higher compared with the serum group. Overall, the results indicated that AMSCs co­cultured with AECs exhibited enhanced proliferation activity and survival rate. In conclusion, the present study demonstrated that co­culture of AMSCs with AECs upregulated CXCR4 on the surface of AMSCs and enhanced the migration ability of AMSCs in vitro. This result may improve the directional migration and homing ability of AMSCs, as well as provide a theoretical basis for the application of AMSCs in clinical practice as a novel strategy to increase the success of hematopoietic stem cell transplantation.

Effect of co-culture with amniotic epithelial cells on biological characteristics of amniotic mesenchymal stem cells / 中国肿瘤生物治疗杂志

@# Objective: The aim of this study was to investigate the effect of co-culture with AEC (amniotic epithelial cell) on the biological characteristics of AMSC (amniotic mesenchymal stem cell), and to investigate the roles of SDF-1/CXCR4 axis in the homing and migration of AMSC. Methods: AMSC andAEC were isolated from human amnion, and then cultured, amplified and identified, respectively. TheAMSC were divided into three groups:AEC co-cultured group, serum-free cultured group and serum cultured group.After culture for 24 h, 48 h, and 72 h, the proliferation viability ofAMSC was measured by CCK-8 assay and trypan blue staining; the expression of CXCR4 mRNAwas analyzed by flow cytometry and Real-time RT-PCR, and the migration ability ofAMSC in vitro was observed by migration assay. Results: Cell viability (48 h and 72 h) and survival rate in the co-culture and serum groups were higher than those in the serum-free group (all P<0.05). The mRNA and protein expressions of CXCR4 in AMSC of the co-culture and serum-free groups were significantly higher than those of the serum group (P<0.05). The migration ability of AMSC in the co-culture and serumfree groups, which increase with the SDF-1 (stromal cell derived factor-1) concentration gradient, were higher than that in the serum group (P<0.05). Conclusion: AMSC co-cultured with AEC still have the basic biological characteristics of MSC, and showed good growth activity. Co-culture withAEC can up-regulate CXCR4 onAMSC surfaces and enhance the migration ability ofAMSC in vitro.