Identification of cDNAs for Sox-4, an HMG-Box protein, and a novel human homolog of yeast splicing factor SSF-1 differentially regulated during apoptosis induced by prostaglandin A2/Δ12-PGJ2 in Hep3B cells

We have examined specific genes whose expression is altered during apoptosis induced by prostaglandin (PG)A(2) and Delta(12)-PGJ(2) in human hepatocellular carcinoma Hep3B cells. Using mRNA differential display, we have identified two genes: one is specifically upregulated and encodes for human Sox-4 (Sry-HMG box gene) and the other is significantly down-regulated and is the human homolog of yeast Ssf-1, a novel splicing factor. Northern blot analysis-confirmed their differential expressions. Interestingly, Sox-4 was highly expressed in subcutaneous tumors grown in nude mice as a xenograft from Hep3B cells. These results suggest that the expression of Sox-4 may be related to the apoptosis pathway leading to cell death as well as to tumorigenesis, and that Ssf-1 gene may serve as a negative regulator of PGA(2)/Delta(12)-PGJ(2)-mediated Hep3B cell apoptosis. (C) 1999 Academic Press.