prostaglandin-a2 and Liver-Neoplasms

Prostaglandin (PG) A2 has been reported to inhibit the growth of hepatocellular carcinoma cells via activation of apoptosis, although the molecular mechanisms involved have not been clarified, yet. To investigate the mechanism of the PGA2-induced apoptosis, we analyzed the activation of caspases during the apoptosis of hepatoma cell lines.. Induction of apoptosis by PGA2 in hepatoma cell lines, Hep 3B and Hep G2, was assessed by DAPI staining of nuclei and agarose gel electrophoresis of genomic DNA. The involvement of caspases was analyzed by immunoblot analysis of poly ADP-ribose polymerase (PARP) and by checking the effect of caspase inhibitors on PGA2-induced apoptosis.. PGA2 inhibited the growth of Hep 3B and Hep G2 cells, accompanying nuclear condensation and fragmentation, and genomic DNA laddering, which are the hallmarks of apoptosis. The PARP was not cleaved during the apoptosis of Hep 3B and Hep G2 cells and caspase inhibitors such as z-VAD-Fmk and z-DEVD-Fmk exerted no effect on the PGA2-induced apoptosis.. These results suggest that PGA2 induces apoptosis in Hep 3B and Hep G2 cells via caspase-independent pathway.

Topics: Apoptosis; Carcinoma, Hepatocellular; Caspase 3; Caspase Inhibitors; Caspases; Cell Line, Tumor; Cell Proliferation; Enzyme Activation; Humans; Liver Neoplasms; Prostaglandins A; Tumor Cells, Cultured

We reported earlier that expression of Sox-4 was found to be elevated during prostaglandin (PG) A(2) and delta(12)-PGJ(2) induced apoptosis in human hepatocarcinoma Hep3B cells. In this study, the role of Sox-4 was examined using human Hep3B and HepG2 cell lines. Sox-4 induction by several apoptotic inducer such as A23187 (Ca(2+) ionophore) and etoposide (topoisomerase II inhibitor) and Sox-4 transfection into the cells were able to induce apoptosis as observed by the cellular DNA fragmentation. Antisense oligonucleotide of Sox-4 inhibited the induction of Sox-4 expression and blocked the formation of DNA fragmentation by PGA(2) and delta(12)-PGJ(2) in Hep3B and HepG2 cells. Sox-4-induced apoptosis was accompanied with caspase-1 activation indicating that caspase cascade was involved in this apoptotic pathway. These results indicate that Sox-4 is involved in Hep3B and HepG2 cells apoptosis as an important apoptotic mediator.

Topics: Apoptosis; Blotting, Western; Calcimycin; Caspase 1; Caspase Inhibitors; Etoposide; Gene Expression Regulation, Neoplastic; High Mobility Group Proteins; Humans; Liver Neoplasms; Oligopeptides; Prostaglandin D2; Prostaglandins A; SOXC Transcription Factors; Trans-Activators; Transfection; Tumor Cells, Cultured

Prostaglandin (PG) A2 (PGA2) and Delta12-PGJ2 have potent antiproliferative activity on various tumor cell growths in vitro. In this study, we investigated the mechanism of PGA2/Delta12-PGJ2-mediated apoptosis, including intracellular apoptosis-related genes in human hepatocarcinoma Hep3B cells. Hep3B cells treated with PGA2/Delta12-PGJ2 showed that a time-dependent DNA fragmentation characterized by marked apoptosis and the elevation of c-myc mRNA expression. In proportion to the increased c-myc gene transcription, heat shock protein 70 (hsp70) mRNA was induced from 1 to 24 h after PGA2/Delta12-PGJ2 treatment. The transfection of c-myc antisense oligomers in Hep3B cells significantly delayed the induction of HSP70 expression and blocked formation of DNA fragmentation by PGA2/Delta12-PGJ2. Moreover, overexpressed HSP70 showed an increased resistance to apoptosis by PGA2/Delta12-PGJ2 treatment. These results demonstrated that the decreased survival in response to PGA2/Delta12-PGJ2 was causally related to the amount of c-myc and the induction of c-myc regulated the elevation of HSP70 which have been known to correlate with a resistance to apoptosis.

Topics: Antineoplastic Agents; Apoptosis; Carcinoma; Cell Division; Gene Expression Regulation; HSP70 Heat-Shock Proteins; Humans; Liver Neoplasms; Oligodeoxyribonucleotides; Prostaglandin D2; Prostaglandins; Prostaglandins A; Proto-Oncogene Proteins c-myc; Transcription, Genetic