Exploring the prognostic value of SCARF1 in non-small cell lung cancers

Scavenger receptor class F member 1 (SCARF1) has previously been shown to be highly expressed within the human liver, hold prognostic value in hepatocellular carcinoma and mediate the specific recruitment of leukocytes to liver sinusoidal endothelial cells; however, to date, the liver remains the only major organ in which SCARF1 has been explored in any detail. Here, we utilised publically-available RNA-sequencing data from The Cancer Genome Atlas (TGCA) to identify the lungs as a site of significant SCARF1 expression and attribute the majority of its expression to endothelial cell populations. Next, we show that SCARF1 expression is significantly reduced in two histologically distinct types of non-small cell lung carcinoma cancers (NSCLCs), lung adenocarcinoma (LUAD) and lung squamous cell carcinoma (LUSC), compared to non-tumoural tissues. Interestingly, loss of SCARF1 expression was associated with aggressive tumour biology in LUAD tissues, but not in LUSC. Furthermore, increased SCARF1 expression was highly prognostic of better overall survival in LUAD tumour tissues, but this was again in contrast to LUSC tumours, in which SCARF1 held no prognostic value. Finally, we showed that SCARF1 is widely expressed in tumour endothelial cells of non-small cell lung cancers and that its total expression in LUAD tumour tissues correlated with immune score and CD4+ T cell infiltration. This study represents the first detailed exploration of SCARF1 expression in normal and diseased human lung tissues and further highlights the prognostic value and therapeutic potential of SCARF1 in immunologically active cancers.