The activated B-cell-like (ABC) subtype of diffuse large B-cell lymphoma (DLBCL) relies on chronic active B-cell receptor (BCR) signaling. BCR pathway inhibitors induce remissions in a subset of ABC DLBCL patients. BCR microclusters on the surface of ABC cells resemble those generated following antigen engagement of normal B cells. We speculated that binding of lymphoma BCRs to self-antigens initiates and maintains chronic active BCR signaling in ABC DLBCL. To assess whether antigenic engagement of the BCR is required for the ongoing survival of ABC cells, we developed isogenic ABC cells that differed solely with respect to the IgH V region of their BCRs. In competitive assays with wild-type cells, substitution of a heterologous V region impaired the survival of three ABC lines. The viability of one V H 4-34 + ABC line and the ability of its BCR to bind to its own cell surface depended on V region residues that mediate the intrinsic autoreactivity of V H 4-34 to self-glycoproteins. The BCR of another ABC line reacted with self-antigens in apoptotic debris, and the survival of a third ABC line was sustained by reactivity of its BCR to an idiotypic epitope in its own V region. Hence, a diverse set of self-antigens is responsible for maintaining the malignant survival of ABC DLBCL cells. IgH V regions used by the BCRs of ABC DLBCL biopsy samples varied in their ability to sustain survival of these ABC lines, suggesting a screening procedure to identify patients who might benefit from BCR pathway inhibition.lymphoma | cancer biology | B-cell receptor
Transient overexpression of defined combinations of master regulator genes can effectively induce cellular reprogramming: the acquisition of an alternative predicted phenotype from a differentiated cell lineage. This can be of particular importance in cardiac regenerative medicine wherein the heart lacks the capacity to heal itself, but simultaneously contains a large pool of fibroblasts. In this study we determined the cardio-inducing capacity of ten transcription factors to actuate cellular reprogramming of mouse embryonic fibroblasts into cardiomyocyte-like cells. Overexpression of transcription factors MYOCD and SRF alone or in conjunction with Mesp1 and SMARCD3 enhanced the basal but necessary cardio-inducing effect of the previously reported GATA4, TBX5, and MEF2C. In particular, combinations of five or seven transcription factors enhanced the activation of cardiac reporter vectors, and induced an upregulation of cardiac-specific genes. Global gene expression analysis also demonstrated a significantly greater cardio-inducing effect when the transcription factors MYOCD and SRF were used. Detection of cross-striated cells was highly dependent on the cell culture conditions and was enhanced by the addition of valproic acid and JAK inhibitor. Although we detected Ca2+ transient oscillations in the reprogrammed cells, we did not detect significant changes in resting membrane potential or spontaneously contracting cells. This study further elucidates the cardio-inducing effect of the transcriptional networks involved in cardiac cellular reprogramming, contributing to the ongoing rational design of a robust protocol required for cardiac regenerative therapies.
The proliferation of pulmonary artery smooth muscle cells (PASMCs) contributes to the development of pulmonary vascular remodeling, ultimately leading to pulmonary hypertension. In this study, the effects and molecular mechanisms of salidroside on the platelet‑derived growth factor (PDGF)‑BB‑induced proliferation of primary cultured rat PASMCs were investigated. The presented data demonstrated that salidroside significantly inhibited the proliferation and DNA synthesis of PASMCs induced by PDGF‑BB in a dose‑ and time‑dependent manner, without cell cytotoxicity. In accordance with these findings, salidroside blocked progression through G0/G1 to S phase of the cell cycle. The salidroside‑induced inhibition of the cell cycle was associated with the inhibition of cyclin D1, cyclin E, cyclin‑dependent kinase 2 (CDK2) and CDK4 mRNA expression, as well as an increase in the mRNA expression of p27 in PDGF‑BB‑stimulated PASMCs. Further experiments showed that the beneficial effect of salidroside on blocking the proliferation of PASMCs was associated with the suppression of the AKT/glycogen synthase kinase 3 β (GSK3β) signaling pathway, but did not involve the extracellular signal‑regulated kinase 1/2, p38 and c‑Jun‑N‑terminal kinase signaling pathways. These results indicate that salidroside suppresses PDGF‑BB‑induced PASMC proliferation through the AKT/GSK3β signaling pathway and suggests that it may be a feasible therapy for pulmonary vascular remodeling diseases.
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