ABSTRACT
Proper control of B cell growth and metabolism is crucial for B-cell-mediated immunity, but the underlying molecular mechanisms remain incompletely understood. In this study, Sin1, a key component of mTOR complex 2 (mTORC2), specifically regulates B cell growth and metabolism. Genetic ablation of Sin1 in B cells reduces the cell size at either the transitional stage or upon antigen stimulation and severely impairs metabolism. Sin1 deficiency also severely impairs B-cell proliferation, antibody responses, and anti-viral immunity. At the molecular level, Sin1 controls the expression and stability of the c-Myc protein and maintains the activity of mTORC1 through the Akt-dependent inactivation of GSK3 and TSC1/2, respectively. Therefore, our study reveals a novel and specific role for Sin1 in coordinating the activation of mTORC2 and mTORC1 to control B cell growth and metabolism.
Subject(s)
B-Lymphocytes/cytology , B-Lymphocytes/metabolism , Carrier Proteins/physiology , Mechanistic Target of Rapamycin Complex 1/metabolism , Mechanistic Target of Rapamycin Complex 2/metabolism , Proto-Oncogene Proteins c-myc/metabolism , Animals , B-Lymphocytes/immunology , Cell Proliferation , Cells, Cultured , Mechanistic Target of Rapamycin Complex 1/genetics , Mechanistic Target of Rapamycin Complex 2/genetics , Mice , Mice, Inbred C57BL , Mice, Knockout , Phosphorylation , Proto-Oncogene Proteins c-myc/genetics , Signal TransductionABSTRACT
Tumor-associated macrophages (TAMs) can influence ovarian cancer growth, migration, and metastasis, but the detailed mechanisms underlying ovarian cancer metastasis remain unclear. Here, we have shown a strong correlation between TAM-associated spheroids and the clinical pathology of ovarian cancer. Further, we have determined that TAMs promote spheroid formation and tumor growth at early stages of transcoelomic metastasis in an established mouse model for epithelial ovarian cancer. M2 macrophage-like TAMs were localized in the center of spheroids and secreted EGF, which upregulated αMß2 integrin on TAMs and ICAM-1 on tumor cells to promote association between tumor cells and TAM. Moreover, EGF secreted by TAMs activated EGFR on tumor cells, which in turn upregulated VEGF/VEGFR signaling in surrounding tumor cells to support tumor cell proliferation and migration. Pharmacological blockade of EGFR or antibody neutralization of ICAM-1 in TAMs blunted spheroid formation and ovarian cancer progression in mouse models. These findings suggest that EGF secreted from TAMs plays a critical role in promoting early transcoelomic metastasis of ovarian cancer. As transcoelomic metastasis is also associated with many other cancers, such as pancreatic and colon cancers, our findings uncover a mechanism for TAM-mediated spheroid formation and provide a potential target for the treatment of ovarian cancer and other transcoelomic metastatic cancers.
Subject(s)
Macrophages/metabolism , Ovarian Neoplasms/metabolism , Spheroids, Cellular/metabolism , Animals , ErbB Receptors/metabolism , Female , Heterografts , Humans , Intercellular Adhesion Molecule-1/metabolism , Macrophage-1 Antigen/metabolism , Macrophages/pathology , Mice , Mice, Nude , Neoplasm Metastasis , Neoplasm Proteins/metabolism , Neoplasm Transplantation , Ovarian Neoplasms/pathology , Spheroids, Cellular/pathology , Vascular Endothelial Growth Factor A/metabolism , Vascular Endothelial Growth Factor Receptor-1/metabolismABSTRACT
OBJECTIVES: Vasoactive intestinal peptide (VIP) is a molecule shared by the neuroendocrine immune network and is considered to be a potential candidate for treatment of inflammatory and autoimmune diseases. Although some recent studies demonstrate that VIP has a protective role in animal RA models, its variant in different disease grade of OA remains uncertain. DESIGN AND METHODS: Fifty patients with primary knee OA and ten controls with severe trauma were enrolled. Synovial fluid and articular cartilage samples were collected from specimens of total knee arthroplasty (TKA) or knee above amputation. VIP levels in these samples were assessed by ELISA and immunohistochemistry. Kellgren-Lawrence criteria and Mankin score were taken to determine the disease severity. RESULTS: Compared to the controls, OA patients have lower VIP concentration in synovial fluid (659.70±112.79, 95%CI 579.01-740.38 vs 470.83±156.40, 95%CI 426.38-515.28 pg/mL, P<0.001) and articular cartilage (0.26±0.02, 95%CI 0.24-0.28 vs 0.20±0.04, 95%CI 0.18-0.21, P<0.001). Subsequent analysis show that the VIP expression in synovial fluid is markedly correlated with its OD in articular cartilage (Pearson's r=0.580, P<0.001). Furthermore, the synovial fluid and articular cartilage levels of VIP both demonstrated to be negatively correlated with severity of disease (Spearman's ρ=0.838, P<0.001; Spearman's ρ=0.814, P<0.001). CONCLUSIONS: VIP in synovial fluid and articular cartilage is negatively associated with progressive joint damage in OA and is a potential indictor of disease severity.
