Colorectal cancer is one of the leading causes of
cancer death worldwide. To identify candidates for
biomarkers and therapeutic targets, we investigated the
proteome of
colorectal cancer tissues. Using 2D-DIGE in combination with our original large format electrophoresis apparatus, we compared surgically resected normal and
tumor tissues from 53 patients with
colorectal cancer. We focused on
proteins with an alkaline pI using IPG
gels for the alkaline range. We observed 1687
protein spots, and found 100 spots with statistical (p<0.01) and significant (>2-fold) differences between the normal and the
tumor tissue groups. Among these 100
protein spots, five showed a different intensity between
tumor tissues from the stage-II and the stage-III patients. MS experiments revealed that these 100
protein spots corresponded to 58 unique
proteins. These included six
proteins which had not been previously reported to be associated with
colorectal cancer. Among these
proteins, five were not reported in any type of
malignancy. IEF/western blotting confirmed the differences in
protein expression between the normal and the
tumor tissues. These results may provide an insight for
biomarker development and drug target discovery in
colorectal cancer.