dehydroxymethylepoxyquinomicin and Peritoneal-Neoplasms

The transcription factor nuclear factor-κB (NF-κB) plays a crucial role in pancreatic cancer (PC) progression. NF-κB is also involved in resistance to anoikis, a special type of apoptosis induced when cells are detached from the extracellular matrix or other cells. Anoikis resistance is related to the metastatic abilities of tumor cells; however, little is known about anoikis induction as it relates to inhibition of PC metastasis by NF-κB inhibitors. Here we used a specific NF-κB inhibitor, (-)-dehydroxymethylepoxyquinomicin (DHMEQ), to investigate anoikis induction and peritoneal metastasis suppression following NF-κB inhibition. We transduced Gluc, a secretory form of luciferase, into a PC cell line, AsPC-1 (AsPC-1-Gluc), for our in vivo experiments. (-)-DHMEQ induced anoikis in AsPC-1-Gluc cells as measured by cell survival assays and flow cytometry. The DNA-binding activity of p65 was enhanced immediately after cell detachment from culture dishes in ELISA assays. Some antiapoptotic proteins such as cellular inhibitor of apoptotic protein-1 were consequently upregulated on Western blots. (-)-DHMEQ prevented this increase in p65 activity and the subsequent expressions of antiapoptotic molecules. In a murine xenograft model, anoikis-resistant PC cell lines tended to metastasize to the peritoneum more than anoikis-sensitive cells, suggesting a correlation between anoikis sensitivity and peritoneal metastasis. (-)-DHMEQ successfully inhibited peritoneal metastasis of AsPC-1-Gluc cells. We monitored metastasis inhibition by ex vivo chemiluminescent detection of Gluc secreted from tumor cells into murine plasma and by in vivo imaging. Our results suggest that (-)-DHMEQ inhibited peritoneal dissemination by preventing anoikis resistance of PC cells.

Topics: Animals; Anoikis; Apoptosis Regulatory Proteins; Benzamides; Cell Line, Tumor; Cyclohexanones; Disease Models, Animal; Gene Expression; Genes, Reporter; Humans; Mice; Molecular Imaging; NF-kappa B; Pancreatic Neoplasms; Peritoneal Neoplasms; Protein Binding; Transcription Factor RelA; Tumor Burden; Xenograft Model Antitumor Assays

Currently, patients with peritoneal dissemination of gastric cancer must accept a poor prognosis because there is no standard effective therapy. To inhibit peritoneal dissemination it is important to inhibit interactions between extracellular matrices (ECM) and cell surface integrins, which are important for cancer cell adhesion. Although nuclear factor-kappa B (NF-κB) is involved in various processes in cancer progression, its involvement in the expression of integrins has not been elucidated. We used a novel NF-κB inhibitor, dehydroxymethylepoxyquinomicin (DHMEQ), to study whether NF-κB blocks cancer cell adhesion via integrins in a gastric cancer dissemination model in mice and found that DHMEQ is a potent suppressor of cancer cell dissemination. Dehydroxymethylepoxyquinomicin suppressed the NF-κB activity of human gastric cancer cells NUGC-4 and 44As3Luc and blocked the adhesion of cancer cells to ECM when compared with the control. Dehydroxymethylepoxyquinomicin also inhibited expression of integrin (α2, α3, β1) in in vitro studies. In the in vivo model, we injected 44As3Luc cells pretreated with DHMEQ into the peritoneal cavity of mice and performed peritoneal lavage after the injection of cancer cells. Viable cancer cells in the peritoneal cavities were evaluated sequentially by in vivo imaging. In mice injected with DHMEQ-pretreated cells and lavaged, live cancer cells in the peritoneum were significantly reduced compared with the control, and these mice survived longer. These results indicate that DHMEQ could inhibit cancer cell adhesion to the peritoneum possibly by suppressing integrin expression. Nuclear factor-kappa B inhibition may be a new therapeutic option for suppressing postoperative cancer dissemination.

Topics: Animals; Antineoplastic Agents; Benzamides; Cell Adhesion; Cell Line, Tumor; Cell Separation; Cyclohexanones; Flow Cytometry; Humans; Male; Mice; Mice, Nude; Neoplasm Invasiveness; NF-kappa B; Peritoneal Neoplasms; Stomach Neoplasms; Xenograft Model Antitumor Assays