Upregulated SLC1A5 promotes cell growth and survival in colorectal cancer.

Glutamine metabolism is essential for tumorigenesis of colorectal cancer, cancer cells remodel their glutamine metabolic pathways to fuel rapid proliferation. SLC1A5 is an important transporter of glutamine various cancer cells. In this study, we investigated SLC1A5 protein expression in colorectal cancer and evaluated its clinical significance and functional importance. Immunohistochemical analysis was performed on tissue microarrays containing 90 pairs of cancer and adjacent normal tissues from colorectal cancer patients, we found that SLC1A5 expression increased significantly in colorectal cancer compared with normal mucosa tissues (P < 0.001). We further validated SLC1A5 overexpression in 12 pairs of fresh cancer and adjacent normal mucosa tissues from colorectal cancer patients by Western blot (P < 0.05). SLC1A5 expression levels were strongly associated with T stage of tumor (P < 0.05), and the tubular adenocarcinoma subtype (P < 0.001). Moreover, downregulation of SLC1A5 by synthetic siRNA could suppress proliferation and induce apoptosis in colorectal cancer cell lines HT29 and HCT116. In conclusion, our results provide for the first time the differential expression in human colorectal cancer and normal tissues, and a functional link between SLC1A5 expression and growth and survival of colorectal cancer, making it an attractive target in colorectal cancer treatment.