骨髓增生性肿瘤 (MPN) 的特点是由于 JAK2V617F 等突变的获得而导致血细胞产生增加。 TGF-β 在 MPN 患者中分泌增加，已知可负调节造血干细胞 (HSC) 增殖。使用同基因 JAK2V617F 或 JAK2 野生型 UT-7 细胞系，我们观察到 JAK2V617F 细胞抵抗 TGF-β 抗增殖活性。尽管 TGF-β 受体和 SMAD2/3 表达在两种细胞类型中相似，但与 JAK2 WT 细胞相比，UT-7 JAK2V617F 细胞中 TGF-β 诱导的 SMAD2/3 磷酸化降低。我们在竞争性测定中证实，JAK2V617F 突变细胞对 TGF-β 的抗增殖作用具有抵抗力，因为我们观察到暴露于 TGF-β 时 JAK2V617F 细胞的阳性选择。使用细胞系、来自 MPN 患者的 CD34 阳性细胞和来自 JAK2V617F 敲入小鼠的骨髓细胞，我们确定了 SHP-1 磷酸酶的下调，这是 TGF-β 调节 HSC 静止所必需的。 SHP-1 cDNA（但不是磷酸酶失活的 cDNA）的转导恢复了 JAK2V617F 突变细胞中 TGF-β 的抗增殖作用。最后，SC-1（一种已知的 SHP-1 激动剂）在 TGF-β 存在的情况下拮抗 JAK2V617F 突变细胞的选择。总之，我们发现 MPN 患者细胞中 SHP-1 存在 JAK2 依赖性下调，这与细胞对 TGF-β 抗增殖作用的抵抗有关。这可能参与 MPN 中癌细胞的克隆选择。© 2024 作者。细胞与分子医学基金会和约翰·威利出版的《细胞与分子医学杂志》

Myeloproliferative neoplasms (MPNs) are characterized by an increased production of blood cells due to the acquisition of mutations such as JAK2V617F. TGF-β, whose secretion is increased in MPN patients, is known to negatively regulate haematopoietic stem cell (HSC) proliferation. Using an isogenic JAK2V617F or JAK2 wild-type UT-7 cell line we observed that JAK2V617F cells resist to TGF-β antiproliferative activity. Although TGF-β receptors and SMAD2/3 expressions are similar in both cell types, TGF-β-induced phosphorylation of SMAD2/3 is reduced in UT-7 JAK2V617F cells compared with JAK2 WT cells. We confirmed that JAK2V617F mutated cells are resistant to the antiproliferative effect of TGF-β in a competitive assay as we observed a positive selection of JAK2V617F cells when exposed to TGF-β. Using cell lines, CD34-positive cells from MPN patients and bone marrow cells from JAK2V617F knock-in mice we identified a down regulation of the SHP-1 phosphatase, which is required for the regulation of HSC quiescence by TGF-β. The transduction of SHP-1 cDNA (but not a phosphatase inactive cDNA) restores the antiproliferative effect of TGF-β in JAK2V617F mutated cells. Finally, SC-1, a known agonist of SHP-1, antagonized the selection of JAK2V617F mutated cells in the presence of TGF-β. In conclusion, we show a JAK2-dependent down regulation of SHP-1 in MPN patients' cells which is related to their resistance to the antiproliferative effect of TGF-β. This may participate in the clonal selection of cancer cells in MPNs.© 2024 The Author(s). Journal of Cellular and Molecular Medicine published by Foundation for Cellular and Molecular Medicine and John Wiley & Sons Ltd.