CAFs-derived SPI1 in tumor fibroblasts promotes malignant behaviors of liver cancer cells and immune escape by regulating HRAS and PD-L1 transcription.

BACKGROUND: As the fifth most common cancer worldwide, hepatocellular carcinoma (HCC) is a highly malignant disease with a formidable prognosis. Within the tumor microenvironment, cancer-associated fibroblasts (CAFs) play a paramount role in tumorigenesis and progression by providing a supportive environment for cancer cells. This research aims to elucidate the regulatory mechanisms of CAFs and salmonella pathogenicity island 1 (SPI1) in HCC progression. METHODS: Protein and mRNA expression levels were determined by western blot and reverse-transcription quantitative polymerase chain reaction (RT-qPCR), respectively. The ability of glycolysis was detected using the glucose consumption and lactate production test kit. Cell proliferation was examined using colony formation assay. Cell migration and invasion were assessed via wound healing and transwell assays, respectively. The cell apoptosis was examined by flow cytometry and terminal deoxynucleotidyl transferase dUTP Nick-End Labeling (TUNEL). RESULTS: The CAFs and para-cancer fibroblasts (PAFs) were successfully separated. CAFs under hypoxic stress (H/CAFs) promoted glucose consumption and lactate production in HCC cells (Huh7 and Hep3B). CAFs conditioned medium (CAFs-CM) facilitated HCC cell proliferation, migration, invasion, glucose consumption, and lactate production. CAFs-CM facilitated programmed cell death 1 ligand 1 (PD-L1) and CD8(+)T apoptosis and hindered proliferation of CD8(+)T. SPI1 was identified as the common target of the differentially expressed genes (DEGs) in CAFs (GSE192912) and transcription factors (TF). The mRNA and protein expression of SPI1 was increased in CAFs. SPI1 knockdown suppressed PD-L1 expression levels, glucose consumption, lactate production, proliferation, invasion, and immune escape in CAFs-CM-cultured HCC cells. CONCLUSIONS: SPI1 derived from CAFs facilitates the malignant behaviors of HCC cells by up-regulating v-Ha-ras Harvey rat sarcoma viral oncogene homolog (HRAS) expression. This study enriches our understanding of HCC at the molecular level and may pave the way for the development of a novel strategy for the treatment of HCC.