title: Functional significance of B7-H1 expressed by human uveal melanoma cells.
abstract: B7-H1, a recently described B7 family member, has been reported to negatively regulate T-cell function in most cancer cells. In this study, we sought to investigate B7-H1 expression in four uveal melanoma (UM) cells (OCM1, SP6.5, OM431 and VUP) to determine the functional significance of B7-H1 expression in T-cell immune response. Using flow cytometry (FCM), we demonstrated that SP6.5 cells had high B7-H1 protein expression, while the other three UM cell lines had none. However, all four UM cell lines expressed B7-H1 mRNA, as confirmed by reverse transcription-polymerase chain reaction. In co-culture experiments using B7-H1-expressing UM cells with T-cells, FCM to determine CD69 expression in T-cells revealed that SP6.5 cell-related B7-H1 inhibited T-cell activation. This effect was eliminated by B7-H1-targeted RNA interference. An Annexin V/PI double staining assay further showed that B7-H1 expressed by SP6.5 cells did not increase the apoptosis of T-cells, though it was found in a variety of other solid tumors. In conclusion, all the UM cell lines constitutively expressed B7-H1 mRNA, while B7-H1 protein was expressed at different levels. UM-related B7-H1 expression negatively regulated T-cell immune response through the inhibition of T-cell activation, and not through the promotion of T-cell apoptosis. This provides new insight into anti-tumor immunity against B7-H1-expressing UM cells.
authors: Department of Ophthalmology, Ninth People's Hospital, Shanghai Jiaotong University School of Medicine, Shanghai 200011, PR China.
authors: Renbing
authors: R
authors: Jia
authors: Zhijun
authors: Z
authors: Jiao
authors: Xiaofang
authors: X
authors: Xu
authors: Jing
authors: J
authors: Wang
authors: Yixiong
authors: Y
authors: Zhou
authors: Xin
authors: X
authors: Song
authors: Shengfang
authors: S
authors: Ge
authors: Xianqun
authors: X
authors: Fan
mesh_terms: D015703:Antigens, CD / Q000235:genetics / Q000276:immunology*; D017209:Apoptosis; D060890:B7-H1 Antigen; D045744:Cell Line, Tumor; D015972:Gene Expression Regulation, Neoplastic; D006801:Humans; D008213:Lymphocyte Activation; D008545:Melanoma / Q000235:genetics / Q000276:immunology; D013601:T-Lymphocytes / Q000166:cytology / Q000276:immunology*; D014604:Uveal Neoplasms / Q000235:genetics / Q000276:immunology; D000098943:Uveal Melanoma
chemical_list: D015703:Antigens, CD; D060890:B7-H1 Antigen; C423236:CD274 protein, human