Attenuation of MET-mediated migration and invasion in hepatocellular carcinoma cells by SOCS1

AIM To investigate the role of suppressor of cytokine signaling 1(SOCS1)in regulating MET-mediated invasive potential of hepatocellular carcinoma(HCC)cells.METHODSStable derivatives of mouse(Hepa1-6)and human(hep3B,Hep G2)HCC cell lines expressing SOCS1or control vector were evaluated for their ability to migrate towards hepatocyte growth factor(HGF)in the transwell migration assay,invade extracellular matrix in response to HGF stimulation in a 3-D invasion assay by confocal microscopy,and to undergo anchorageindependent proliferation in semisolid agar.Following intravenous and intrasplenic inoculation into NOD.scid.gamma mice,the ability of Hepa cells to form othotopic tumors was evaluated.Following HGF stimulation of Hepa and Hep3B cells,expression of proteins implicated in epithelial-to-mesenchymal transition was evaluated by western blot and qR T-PCR.RESULTS SOCS1 expression in mouse and human HCC cells inhibited HGF-induced migration through matrigel.In the 3-D invasion assay,HGF stimulation induced invasion of HCC cells across type-Ⅰcollagen matrix,and SOCS1expression significantly reduced the depth of invasion.SOCS1 expression also reduced the number and size of colonies formed by anchorage-independent growth in semisolid agar.Following intravenous inoculation,control Hepa cell formed large tumor nodules that obliterated the liver whereas the SOCS1-expressing Hepa cells formed significantly smaller nodules.Tumors formed by SOCS1-expressing cells showed reduced phosphorylation of STAT3 and ERK that was accompanied by reduced levels of MET protein expression.HGF stimulated Hepa cells expressing SOCS1 showed increased expression of E-cadherin and decreased expression of EGR1,SNAI1and ZEB1.Comparable results were obtained with Hep3B cells.SOCS1 expressing HCC cells also showed reduced levels of EGR1 and SNAI1 transcripts.CONCLUSION Our findings indicate that loss of SOCS1-dependent control over epithelial-to-mesenchymal transition may contribute to MET-mediated migration,invasion and metastatic growth of HCC.

Trans-presentation of interleukin-15 by interleukin-15 receptor alpha is dispensable for the pathogenesis of autoimmune type 1 diabetes

Interleukin-15(IL-15)is a pro-inflammatory cytokine that is required for the survival and activation of memory CD8^(+)T cells,natural killer(NK)cells,innate lymphoid cells,macrophages and dendritic cells.IL-15 is implicated in the pathogenesis of various autoimmune diseases such as rheumatoid arthritis,inflammatory bowel disease,psoriasis and autoimmune type 1 diabetes(T1D).IL-15 receptor(IL-15R)consists of a specificαchain,theβchain that is shared with IL-2R and the commonγchain.IL-15 is unique in the manner in which it binds and signals through its receptor subunits.IL-15 that is complexed with IL-15Rαbinds to theβγreceptor complex present on the responding cell to mediate its biological effects through a process referred to as trans-presentation.The trans-presented IL-15 is essential to mediate the biological effects on T lymphocytes and NK cells.Here we show that IL-15,but not IL-15Rα,is required for the development of spontaneous and virus-induced T1D,viral clearance and for antigen cross-presentation to CD8^(+)T lymphocytes.Our findings provide insight into the complexities of IL-15 signalling in the initiation and maintenance of CD8^(+)T cell-mediated immune responses.

I L- 15 trans-presentation regulates homeostasis of CD4^＋ T lymphocytes

Interleukin-15 （IL-15） is essential for the survival of memory CD8^＋ and CD4^＋ T cell subsets, and natural killer and natural killer T cells. Here, we describe a hitherto unreported role of IL-15 in regulating homoeostasis of naive CD4^＋ T cells. Adoptive transfer of splenocytes from non-obese diabetic （NOD） mice results in increased homeostatic expansion of T cells in lymphopenic NOD.scid.II15^-/- mice when compared to NOD.scid recipients. The increased accumulation of CD4^＋ T cells is also observed in NOD.II15^-/- mice, indicating that IL-15-dependent regulation also occurs in the absence of lymphopenia. NOD.scid mice lacking the I L- 15Ra chain, but not those lacking the common gamma chain, also show increased accumulation of CD4^＋ T cells. These findings indicate that the IL-15-mediated regulation occurs directly on CD4^＋ T cells and requires trans-presentation of IL-15. CD4^＋ T cells expanding in the absence of IL-15 signaling do not acquire the characteristics of classical regulatory T cells. Rather, CD4^＋ T cells expanding in the absence of IL-15 show impaired antigen-induced activation and IFN-7 production. Based on these findings, we propose that the IL-15-dependent regulation of the naive CD4^＋ T-cell compartment may represent an additional layer of control to thwart potentially autoreactive cells that escape central tolerance, while permitting the expansion of memory T cells.