Colorectal carcinoma (CRC) is one of the most common malignancies in the world. PD-1/PD-L1 inhibitors have benefited cancer patients with multiple tumor types. However, their efficacy for CRC is low and this treatment in melanoma patients results in adaptive resistance through upregulation of VISTA, another checkpoint inhibitory pathway. Thus, there is an urgent need to explore additional co-inhibitory molecular pathways such as VISTA for CRC treatment. In this study, C10orf54 (encoding VISTA) expression was analyzed by RNA-seq data from 367 CRC patients in human cancer datasets. Moreover, 28 clinical CRC specimens were used to assess VISTA protein expression. Human cancer datasets showed that CRC tumors expressed higher levels of C10orf54 than CD274 (encoding PD-L1). Moreover, C10orf54 mRNA expression was significantly correlated with genes responsible for tumor immune evasion. VISTA protein expression was high in tumors compared with para-tumors and normal tissues, which is similar to PD-L1 expression. However, in contrast to PD-L1, VISTA was mainly expressed by tumor-infiltrating lymphocytes. This study is the first investigation of VISTA expression in human resected CRC tumors, and the results justify the need for future studies on the role of VISTA in anti-CRC immunity in clinical samples.
Keywords: Immune checkpoint; Immunotherapy; PD-L1; Tumor immunity; VISTA.