Zhiqiang Li

Remodeling of adipocyte morphology and function plays a critical role in prostate cancer development. We previously reported that leukemia cells secrete growth differentiation factor 15 (GDF15)，which remodels the residual bone marrow (BM) adipocytes into small adipocytes and is associated with a poor prognosis in acute myeloid leukemia (AML) patients. However, little is known about how GDF15 drives BM adipocyte remodeling. In this study, we examined the role of the transient receptor potential vanilloid (TRPV) channels in the remodeling of BM adipocytes exposed to GDF15. We found that TRPV4 negatively regulated GDF15-induced remodeling of BM adipocytes. Furthermore, transforming growth factor-β type II receptor (TGFβRII) was identified as the main receptor for GDF15 on BM adipocytes. PI3K inhibitor treatment reduced GDF15-induced pAKT, identifying PI3K/AKT as the downstream stress response pathway. Subsequently, GDF15 reduced the expression of the transcription factor Forkhead box C1 (FOXC1) in BM adipocytes subjected to RNA-seq screening and Western blot analyse. Moreover, it was also confirmed that FOXC1 combined with the TRPV4 promoter by the Chip-qPCR experiments, which suggests that FOXC1 mediates GDF15 regulation of TRPV4. In addition, an AML mouse model exhibited smaller BM adipocytes, whereas the TRPV4 activator 4α-phorbol 12,13-didecanoate (4αPDD) partly rescued this process and increased survival. In conclusion, TRPV4 plays a critical role in BM adipocyte remodeling induced by leukemia cells, suggesting that targeting TRPV4 may constitute a novel strategy for AML therapy.

To establish the model of antibody-induced immune hemolytic disease in SD rats so as to provide an experimental platform for the exploration of its pathogenesis, course of disease and evaluation of drug efficacy. The red blood cells(RBC) of SD rats were isolated and intraperitoneally injected into BALB/c mice to induce production of the antiserum to SD rat RBC. Twenty SD rats were randomly divided into 2 groups. The rats in the model group were injected with 0.1 ml antiserum via tail vein; the rats in the control group were injected with 0.1 ml saline via tail vein.The symptoms of rats, hemolysis-related indexes and histopathological changes of the main organs were observed in both groups after injection. After the injection of antiserum, the SD rats in the model group displayed nasal flaring, laziness, decrease of ingestion and water intake, skin and mucosal jaundice, and gross hemoglobinuria. At the 4th day after the injection, the body weight of SD rats in the model group was significantly lower than that in the control group (P＜0.01), and the coefficiens of liver and spleen increased significantly (P＜0.01); The levels of WBC, MCV, MCH, DBIL, DBIL/TBIL and FHb all increased statistically significantly, and RBC, Hb, HCT, MCHC and Plt levels decreased significantly in comparison with the control group (P＜0.01). In the SD rats of model group, the hemolytic pathological changes were observed in liver, spleen, kidney, lung and small intestine, and erythroid proliferation was observed in bone marrow smears. The immune hemolytic disease model of SD rats can be successfully established by injecting the serum aginst SD rat red blood cells into the tail vein of SD rats, showing the high success rate, good reproducibility and low cost.

The adipocyte remodeling, including of the morphological change, might indicate special pathological function. Our previous study found that the morphological remodeling of larger marrow adipocytes into small marrow adipocytes correlates with a poor prognosis for acute myeloid leukemia (AML) patients. However, the mechanisms contributed to the marrow adipocyte remodeling are still poorly understood. GDF15 expression was analyzed by RT-qPCR and western blotting assays in the leukemic cells. The enhancing and antibody neutralization tests in vitro were employed to evaluate the effect of GDF15 on the morphology of mature adipocytes. CCK8 test was used to detect the proliferation of leukemic cells after co-cultivation with small marrow adipocytes. Flow cytometry was used to analysis the proportion of cell cycle of leukemic cells. Immunofluorescence staining and linear analysis were applied to verify the GDF15 expression and the relationship between GDF15 and small marrow adipocytes in AML patients. In this study, we found that leukemic cell lines not only expressed significantly higher growth differentiation factor 15 (GDF15) than the other three cytokines associated with adipocyte differentiation in RNA level but also secreted GDF15 factor. Furthermore, the in vitro experiments demonstrated that GDF15 was involved in the conversion of small marrow adipocytes from larger marrow adipocytes. Correspondingly, the leukemic cells proliferated more rapidly through regulating the cell cycle when co-cultured with GDF15-induced small marrow adipocytes. The immunofluorescence staining on the bone marrow sections of AML patients further exhibited that GDF15 was partly produced by leukemic cells. The positive correlation between the concentration of GDF15 in the marrow aspirates and the number and the volume of small marrow adipocytes might suggest the contribution of GDF15 in AML patients (r = 0.72, r = 0.67). GDF15 secreted by leukemic cells was involved in the morphological remodeling of marrow adipocytes, which can in turn promote leukemic cell growth, indicating that GDF15 may be a promising treatment target for AML patients.

Background/Aims: Chemotherapy is still the main strategy used to prevent the relapse of acute myeloid leukaemia (AML). As the most abundant stromal component in bone marrow (BM), marrow adipocytes have been previously shown to promote leukaemogenesis. The present study was designed to further validate whether marrow adipocytes exert synergistic effects on strengthening chemotherapeutic efficacy and evaluate the underlying mechanism. Methods: A retrospective study of BM biopsies from 80 patients with AML in remission and 71 control subjects was applied to quantitatively analyse the marrow adipocyte volume. Toxicity tests were used to assess the effect of chemotherapy drugs on BM cells. The possible mechanisms by which chemotherapy regulated the reduced marrow adipocyte content were investigated using antibody neutralization experiments, with an emphasis on growth differentiation factor 15 (GDF15). Results: In our study, the marrow adipocyte content was obviously reduced in the AML- complete remission (CR) group compared with the control group (PConclusion: Chemotherapy indirectly inhibited adipogenesis by promoting GDF15 secretion from BM MNCs, subsequently strengthening the efficacy of consolidation chemotherapy in patients with AML during CR.