Previous studies investigating
cancer cells cultured at acidic pH have shown that the expression level of ~700 genes were more than two-fold higher than those of the cells cultured in alkaline medium at pH 7.5. The aim of the present study was to confirm whether these
acidosis-induced genes are expressed in human
cancer tissues. Therefore, 7 genes were selected from our previous study, which encoded
interleukin 32 (IL-32), lysosomal H+ transporting
ATPase, V0 subunit d2 (ATP6V0D2),
tumor necrosis factor receptor superfamily, member 9 (TNFRSF9),
amphiregulin,
schwannoma-derived growth factor (AREG), v-erb-b2 erythroblastic
leukemia viral oncogene homolog 3 (ErbB3), PRR5-ARHGAP8 (LOC553158) and
dimethylglycine dehydrogenase (DMGDH), and their expression was examined in human clinical specimens from patients with
cancer. In addition, the expression of the gene encoding
manganese superoxide dismutase (MnSOD) was examined. The specimens from patients with colon, stomach and
renal cancer showed increased MnSOD, IL-32, and TNFRSF9 transcripts compared to those from non-tumorous regions of the same patients. Notably, an elevated expression of ATP6V0D2 was found in the specimens from patients with
stomach cancer, whereas the expression was decreased in those from patients with colon and
renal cancer. The expression of LOC553158 was upregulated in colon and
stomach cancer specimens. These results indicate that the investigation of gene expression under acidic conditions is useful for the development of novel
cancer markers and/or chemotherapeutic targets.