Investigation of Biological Function of Costimulatory b7 Family Members in Endometrial Cancer

Background Endometrial cancer (EC) is a gynecological malignancy classified into two clinicopathological types, endometroid type I and non-endometroid type II. Type I is characterized by slow growth and a good prognosis, while type II is very aggressive and with a poor survival. Recently, in immune-oncology there is a growing interest towards the costimulatory B7 family members as possible promising targets for immunotherapy. These proteins are cell-surface protein ligands, binding to receptors on lymphocytes to regulate immune responses, but previous evidence have demonstrated that inhibitory B7 molecules are frequently up-regulated in different tumors, which may contribute to immune evasion, invasiveness and chemoresistance. Up to now, very few information were provide about B7 members in EC. Objective Our objective was to characterize the expression profile of B7 members in EC. Methods B7 members were evaluated by RT-PCR and Western Blot analysis, in five different human EC cell lines and compared to normal endometrial samples. Results EC cell lines express several B7 members, such as, PD-L1, PD-L2, ICOS-L and B7-H3 with a significant difference compared with normal tissues. Specifically, PD-L2 is significantly over-expressed by an EC Type-II cell line, suggesting its correlation with tumour aggressiveness. Conclusions The role of inhibitory B7 molecules is not completely understood in cancer. Since no information are actually present in regard to B7 members and their roles in EC, we firstly evidenced that some B7 members were expressed in EC cell lines and their expression levels were different compared with normal tissues. These preliminary results are the basis for the development of a project focused in a better understanding of the B7 molecular role in EC.