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RAS mutations are among the most prevalent oncogenic drivers in cancers. RAS proteins propagate signals only when associated with cellular membranes as a consequence of lipid modifications that impact their trafficking. Here, we discovered that RAB27B, a RAB family small GTPase, controlled NRAS palmitoylation and trafficking to the plasma membrane, a localization required for activation. Our proteomic studies revealed RAB27B upregulation in CBL- or JAK2-mutated myeloid malignancies, and its expression correlated with poor prognosis in acute myeloid leukemias (AMLs). RAB27B depletion inhibited the growth of CBL-deficient or WRAS-mutant cell lines. Strikingly, Rab27b deficiency in mice abrogated mutant but not WT NRAS-mediated progenitor cell growth, ERK signaling, and NRAS palmitoylation. Further, Rab27b deficiency significantly reduced myelomonocytic leukemia development in vivo. Mechanistically, RAB27B interacted with ZDHHC9, a palmitoyl acyltransferase that modifies NRAS. By regulating palmitoylation, RAB27B controlled c-RAF/MEK/ERK signaling and affected leukemia development. Importantly, RAB27B depletion in primary human AMLs inhibited oncogenic NRAS signaling and leukemic growth. We further revealed a significant correlation between RAB27B expression and sensitivity to MEK inhibitors in AMLs. Thus, our studies presented a link between RAB proteins and fundamental aspects of RAS posttranslational modification and trafficking, highlighting future therapeutic strategies for RAS-driven cancers., Introduction CBL family proteins, including C-CBL (also called CBL), CBL-B, and CBL-C, are RING domain-containing E3 ubiquitin ligases, among which CBL and CBL-B are widely expressed in hematopoietic cells. CBL [...]

Background and Purpose: Tooth eruption is a complicated process regulated by the dental follicles (DF). Our recent study discovered that tooth eruption was inhibited upon injection of bleomycin into DF. However, the mechanisms were unknown.Experimental Approach: Human dental follicle cells (hDFCs) were treated by bleomycin or exogenous TGF-β1 or transfected by plasmids loading SMAD7 or shRNA targeting SMAD7, followed by osteogenesis induction assay and signalling analysis. Human fresh DF tissues and Wistar rats were used to further confirm bleomycin function.Key Results: Bleomycin decreased expression of RUNX2 and osteogenic genes in hDFCs, reducing osteogenic capacity. TGF-β1 expression was up-regulated in bleomycin-treated hDFCs. The effects of exogenous TGF-β1 were similar to those of bleomycin in hDFCs. Additionally, compared to SMAD2/3, SMAD7 expression increased more in bleomycin- or TGF-β1-treated hDFCs. Overexpression of SMAD7 likewise significantly decreased RUNX2 expression and osteogenic capacity of hDFCs. Knockdown of SMAD7 markedly attenuated the inhibitory effects of bleomycin and TGF-β1 on osteogenic capacity and RUNX2 expression of hDFCs. Most importantly, changes in TGF-β1, SMAD7, and RUNX2 expressions were similar in the DF of rats and humans treated with bleomycin.Conclusion and Implications: SMAD7 was a negative regulator of osteogenic differentiation in DFCs through suppressing RUNX2 expression. Bleomycin or TGF-β1 inhibited osteogenic differentiation of DFCs via a TGF-β1/SMAD7/RUNX2 pathway. Our findings might be beneficial for enhancing the osteogenic activity of DFCs or inhibiting the eruption of undesirable teeth. [ABSTRACT FROM AUTHOR]

Cell-derived microparticles (MPs) have been recently recognized as critical intercellular information conveyors. However, further understanding of their biological behavior and potential application has been hampered by the limitations of current labeling techniques. Herein, a universal donor-cell-assisted membrane biotinylation strategy was proposed for labeling MPs by skillfully utilizing the natural membrane phospholipid exchange of their donor cells. This innovative strategy conveniently led to specific, efficient, reproducible, and biocompatible quantum dot (QD) labeling of MPs, thereby reliably conferring valuable traceability on MPs. By further loading with small interference RNA, QD-labeled MPs that had inherent cell-targeting and biomolecule-conveying ability were successfully employed for combined bioimaging and tumor-targeted therapy. This study provides the first reliable and biofriendly strategy for transforming biogenic MPs into functionalized nanovectors. [ABSTRACT FROM AUTHOR]

Background and Purpose Bleomycin ( BLM), one of the most common sclerosants, is often used to treat venous malformations ( VMs). The present study was designed to investigate whether endothelial mesenchymal transition ( EndoMT) contributes to the therapeutic effects of BLM. Experimental Approach Endothelial and mesenchymal markers of HUVECs were measured by immunofluorescence, real-time quantitative PCR and Western blot analysis. Cell migration and tube formation assays were performed to evaluate endothelial cell function. Slug small-interfering RNA and specific inhibitors [Z-VAD-FMK for pan caspases, rapamycin for mammalian target of rapamycin (m TOR)] were used to investigate the mechanism. Key Results Long term (48 h or longer) treatment with BLM (0.1 mU·mL−1) induced EndoMT in HUVECs, as manifested by a reduction in the expression of vascular endothelial-cadherin and an up-regulation in the expression of α-smooth muscle actin and fibroblast specific protein-1, as well as activation of the transcription factor Slug. The size and protein content of the transformed cells were increased. BLM also enhanced the migration of HUVECs but diminished their tube formation. By employing rapamycin, we demonstrated that activation of the m TOR pathway is involved in BLM-induced EndoMT in HUVECs. Conclusions and Implications Our results show that a Slug-dependent EndoMT process is involved in BLM-induced therapeutic effects on endothelial cells and, more importantly, indicate the potential role of this process in the sclerotherapy of VMs. [ABSTRACT FROM AUTHOR]

A dual‐modally traceable nanoplatform for tumor theranostics is developed by Gang Chen and co‐workers in article number 1703482. Circulating cell‐derived microparticles isolated from the peripheral blood of oral cancer patients are transformed into a tumor‐targeted and traceable nanoplatform encapsulating antitumor siRNA and NIR‐fluorescent magnetic quantum dots (QDs). This strategy opens new avenues for the development of real natural nanoplatforms for personalized cancer theranostics. [ABSTRACT FROM AUTHOR]

Background: Venous malformations (VMs), predominantly arising from activating mutations of tyrosine kinase receptor TIE2 within endothelial cells (ECs), are characterized by dilated and tortuous vessels with a paucity of perivascular cells. The mechanisms of interaction between mutant ECs and perivascular cells remain largely elusive., Objectives: To investigate the characteristics of extracellular vesicles (EVs) from VM ECs, especially their carried miRNAs and their roles in the crosstalk between ECs and perivascular cells in VM pathogenesis., Methods: MiRNA profiles of human umbilical vein endothelial cells overexpressing TIE2L914F (L914F cells) and TIE2WT (WT cells) along with their EVs were analyzed using RNA sequencing. In vitro studies using umbilical cord stem cells (UCSCs) were performed for the functional assays of VM EVs and their enriched microRNA-4432 (miR-4432). MiRNA-pulldown and RNA interference techniques were employed to identify the sorting regulator of miR-4432 into VM EVs., Results: We observed an upregulation of RNA secretion in L914F EVs compared to WT EVs. MiRNA sequencing revealed a distinguished profile of L914F EVs compared to L914F cells, WT cells, and WT EVs, identifying miR-4432 as preferentially encapsulated within EVs from L914F cells. Functional assays demonstrated that VM EVs and EV-carried miR-4432 inhibited the differentiation, adhesion, and proliferation of UCSCs. Furthermore, RPL36 was identified as an RNA binding protein and sorting regulator of miR-4432 during the EV secretion process in L914F cells., Conclusions: This study, for the first time, identifies the interaction between VM ECs and perivascular cells via EVs, and offers valuable data on the miRNA profiles of VM ECs and normal ECs, along with their EVs. Our findings suggest that the RPL36-mediated selective loading of miR-4432 into EVs may contribute to the aberrant perivascular cell coverage in VMs, providing novel insights into VM pathogenesis and potential treatment strategies., (© The Author(s) 2024. Published by Oxford University Press on behalf of British Association of Dermatologists. All rights reserved. For commercial re-use, please contact reprints@oup.com for reprints and translation rights for reprints. All other permissions can be obtained through our RightsLink service via the Permissions link on the article page on our site—for further information please contact journals.permissions@oup.com.)

Objective: To explore the potential therapies for infantile haemangiomas by targeting survivin, a member of the inhibitor of apoptosis protein family, using its specific small molecule inhibitor YM155., Methods: The expression of survivin in human haemangioma tissue was explored using immunohistochemistry and immunohistofluorescence. Cell cycle analysis and EdU assays were used to measure cell proliferation. Heochst33342 and Annexin V/PI double staining were performed to measure cell apoptosis. The capacity for self-renewal and multilineage differentiation potential of haemangioma stem cells (HemSCs) were measured by clone formation assays and multiple differentiation assays. Murine haemangioma models were established to explore the therapeutic efficacy of YM155 in vivo., Results: Strong staining of survivin in stromal cells was observed in the proliferative haemangioma tissue. In vitro studies demonstrated that YM155 induced cell cycle arrest and proliferation suppression of HemSCs, and also caused cell apoptosis at a higher concentration. YM155 impaired the self-renewal capacities and damaged multiple differentiation potentials of HemSCs. Importantly, YM155 suppressed blood vessel formation and cell proliferation, and induced cell apoptosis in murine haemangioma models., Conclusion: The present study demonstrated that targeting survivin using its specific suppressant, YM155, prevented the progression of infantile haemangioma by suppressing cell proliferation, inducing cell apoptosis and disrupting the differentiation potential of HemSCs. These results indicate a novel and promising therapeutic approach for the treatment of infantile haemangioma.