Successful hematopoiesis requires long-term retention of the quiescent state of hematopoietic stem cells (HSCs). The transcriptional regulation of stem cell quiescence, especially by factors with specific functions in HSCs, is only beginning to be understood. Here we demonstrate that Nurr1, a nuclear receptor transcription factor, has such a regulatory role. Enforced expression of Nurr1 drives early hematopoietic progenitors into quiescence. When stem cells overexpressing Nurr1 are transplanted into lethally irradiated mice, they home to the bone marrow but do not contribute to regeneration of the blood system. Furthermore, the loss of only one allele of Nurr1 is sufficient to induce HSCs to enter the cell cycle and proliferate. Molecular analysis revealed an association between Nurr1 overexpression and upregulation of the cell cycle inhibitor p18, INK4C, suggesting a mechanism by which Nurr1 could regulate HSC quiescence. Our findings provide critical insight into the transcriptional control mechanisms that determine whether HSCs remain dormant or enter the cell cycle and begin to proliferate.
The overall efficacy of chimeric antigen receptor modified T cells (CARTs) remain limited in solid tumors despite intensive studies that aim at targeting multiple antigens, enhancing migration, reducing tonic signaling, and improving tumor microenvironment. On the other hand, how the affinity and engaging kinetics of antigen-binding domain (ABD) affects the CART’s efficacy has not been carefully investigated. In this article, we first analyzed 38 published solid tumor CART trials and correlated the response rate to their ABD affinity. Not surprisingly, majority (25 trials) of the CARTs utilized high-affinity ABDs, but generated merely 5.7% response rate. In contrast, 35% of the patients treated with the CARTs built from moderate-affinity ABDs had clinical responses. Thus, CARTs with moderate-affinity ABDs not only have less off-target toxicity, but also are more effective. We then reviewed the effects of ABD affinity on the biology and function of CARTs, providing further evidence that moderate-affinity ABDs may be better in CART development. In the end, we propose that a fast-on/fast-off (high Kon and Koff) kinetics of CART-target engagement in solid tumor allow CARTs to generate sufficient signaling to kill tumor cells without being driven to exhaustion. We believe that studying the ABD affinity and the kinetics of CART-tumor interaction may hold a key to designing effective CARTs for solid tumors.
Small-molecule inhibitors targeted MAPK have been wildly used for some cancer therapeutics as a biologically viable model, but no one has been used for cervical caner. ERK1/2, one of MAPK kinases, is expressed high in cervical cancer tissue. The aim of the present study was to evaluate the effects of ERK1/2 inhibitor U0126 on proliferation and apoptosis of cervical cancer cells and appraise the correlated mechanism of the effects. In this study, the cell proliferation of Hela and C33A cervical cancer cells was tested by Cell Counting Kit-8 (CCK8) assay and cell counting after treated with ERK1/2 inhibitor U0126. The cell cycle and apoptosis were evaluated by flow cytometry (FCM). The protein levels of ERK1/2 and c-Fos and c-Jun were detected by Western blot. The results indicated that after down-regulating ERK1/2 proteins with the inhibitor U0126, Hela and C33A cells proliferation was inhibited, cell apoptosis was promoted, the proportions of G0/G1 stage in cell cycle increased, and G2/M stages decreased. After down-regulating ERK1/2 proteins of Hela and C33A cells, the expression levels of p-c-Fos protein decreased, while p-c-Jun protein increased. The results of this study indicated that ERK1/2 may promote the development of cervical cancer cells, suggesting ERK1/2 inhibitor may be used as an effective target for cervical cancer therapies working for. It might inhibit cervical cancer cells growth via regulating the transcription factors expression of c-Fos and c-Jun.
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