We have recently shown that cancer cells of various origins take up
extracellular citrate through the plasma membrane citrate carrier (pmCiC),
a specific plasma membrane citrate transporter. Extracellular citrate is
required to support cancer cell metabolism, in particular fatty acid
synthesis, mitochondrial activity, protein synthesis and histone acetylation.
In addition, cancer cells tend to acquire a metastatic phenotype in the
presence of extracellular citrate. Our recent study also showed that
cancer-associated stromal cells synthesise and release citrate and that this
process is controlled by cancer cells. In the present study, we evaluated the
expression of pmCiC, fibroblast activation protein-α (FAP) and the
angiogenesis marker cluster of differentiation 31 (CD31) in human cancer
tissues of different origins. In the cohort studied, we found no correlation
between disease stage and the expression of FAP or CD31. However, we
have identified a clear correlation between pmCiC expression in cancer
cells and cancer-associated stroma with tumour stage. It can be
concluded that pmCiC is increased in cancer cells and in cancersupporting
cells in the tumour microenvironment at the later stages of
cancer development, particularly at the metastatic sites. Therefore, pmCiC
expression has the potential to serve as a prognostic marker, although further
studies are needed.