KLF7 Promotes Hepatocellular Carcinoma Progression Through Regulating SLC1A5-Mediated Tryptophan Metabolism.

Krüppel-like factor 7 is a transcriptional activator and acts as an oncogene in human cancers, including hepatocellular carcinoma (HCC). Tryptophan metabolism is important for HCC cell proliferation, metastasis, and invasion. It is unclear whether KLF7 could regulate Trp metabolism in HCC. In this study, we found that Trp metabolism was suppressed in HCC cells with KLF7 knockdown. The mRNA and protein levels of SLC1A5, SLC7A5, and TPH1, as well as the content of Trp and serotonin, were reduced after KLF7 knockdown, and were potentiated following KLF7 overexpression. Increasing the content of serotonin could restore the malignancy of tumour cells in vitro and tumour growth in vivo. Conversely, decreasing the content of serotonin suppressed HCC cell proliferation. The binding activity of KLF7 was on the promoter of SLC1A5, and KLF7 positively regulated the expression of SLC1A5. KLF7 contributed to the proliferation and migration of HCC cells by up-regulation of SLC1A5. Collectively, KLF7 promotes the progression of HCC through regulating Trp metabolism. The newly identified axis of KLF7/ SLC1A5 in HCC could represent a potential target for HCC therapy.