Isoforms of human B7-H3 co-signalling molecule for T cell activation as potential immunoregulatory agents: Wyeth Corporation: WO2004093894

Roles of B7-H3 in Cervical Cancer and Its Prognostic Value

B7-H3, which has been reported to be a co-regulatory ligand of the B7 family, can suppress T cell-mediated immunity and has also been reported to be expressed in many malignancies. In this study, we found that B7-H3 was primarily expressed in the cytoplasm of cervical cancer cells and was associated with deep stromal invasion (P=0.0013). The disease-free survival data showed that cervical cancer patients whose tumours were positive for B7-H3 expression had higher mortality rates compared with patients whose tumours lacked B7-H3 expression (P=0.0317), representing an advantage over P16 (P=0.3486). In contrast, the level of serum B7-H3 was low in cases of cervical intraepithelial neoplasia and cervical cancer. The silencing of B7-H3 in the SiHa, CaSki and H8 cell lines inhibited cell proliferation and enhanced apoptosis, while the over-expression of B7-H3 in HeLa cells showed inverse changes. These changes were partially due to the regulation of cell cycle- and apoptosis-related proteins, such as E2F, P21, P16, PARP-1, Caspase-8, Bax, Bcl-2 and Bcl-xl. The results of in vivo experiments revealed that the knockdown of B7-H3 in tumour cells suppressed SiHa cell growth in nude mice. Overall, B7-H3 is involved in the development and progression of cervical intraepithelial neoplasia and cervical cancer through its effects on the cell cycle and apoptosis, which are mediated via the E7/Rb pathway. B7-H3 also has the potential to be a useful prognostic marker for patients with cervical cancer.

New B7 Family Checkpoints in Human Cancers

T cells are the main effector cells in immune response against tumors. The activation of T cells is regulated by the innate immune system through positive and negative costimulatory molecules. Targeting immune checkpoint regulators such as programmed cell death 1 (PD-1)/PD-1 ligand 1 (PD-L1) and CTL antigen 4 (CTLA-4) has achieved notable benefit in a variety of cancers, which leads to multiple clinical trials with antibodies targeting the other related B7/CD28 family members. Recently, five new B7 family ligands, B7-H3, B7-H4, B7-H5, B7-H6, and B7-H7, were identified. Here we review recent understanding of new B7 family checkpoint molecules as they have come to the front of cancer research with the concept that tumor cells exploit them to escape immune surveillance. The aim of this article is to address the structure and expression of the new B7 family molecules as well as their roles in controlling and suppressing immune responses of T cells as well as NK cells. We also discuss clinical significance and contribution of these checkpoint expressions in human cancers. Mol Cancer Ther; 16(7); 1203-11. ©2017 AACR.