CD5L is upregulated in hepatocellular carcinoma and promotes liver cancer cell proliferation and antiapoptotic responses by binding to HSPA5 (GRP78)

CD5-like (CD5L) is a soluble scavenger cysteine-rich protein that modulates inflammatory responses. We studied the involvement of CD5L in liver cancer. Immunohistochemistry (IHC) of CD5L in 60 hepatocellular carcinomas and 34 adjacent nontumor livers, showed that CD5L staining was higher in tumor than in nontumor tissue (Mann-Whitney test; P = 0.0039). High CD5L correlated with elevated proliferation (Ki67, linear regression; P < 0.0001) and lower patient event-free survival (log-rank; P = 0.0185). Accordingly, CD5L expression was detected in the liver cancer cell lines Huh7, HepG2, and SNU-398. In vitro technologies using these cell lines, including small interfering RNA (siRNA) and cDNA transfection, showed that CD5L promoted colony formation and cell proliferation and protected against cisplatin-induced apoptosis. To find a molecular explanation for these roles, novel CD5L-interacting protein ligands in liver cancer cells were identified by immunoprecipitation followed by mass spectrometry. Among these...