Abstract 3840: Evaluation of the synergetic effect of a combination of dehydroxymethylepoxyquinomicin and gemcitabine on liver metastasis of pancreatic cancer

Abstract

Abstract Activation of the nuclear transcription factor-kappaB (NF-κB) has been implicated in the progression and metastasis of pancreatic cancer. This study was designed to evaluate the effects of a novel NF-κB inhibitor, dehydroxymethylepoxyquinomicin (DHMEQ) in inhibition of liver metastasis of pancreatic cancer in a clinical liver metastasis-mimicking mouse model in which cancer cells were intra-portal injected under small laparotomy. Moreover, the synergistic effect of combination therapy with DHMEQ and gemcitabine (GEM) was investigated. Cytotoxicity of DHMEQ and GEM was evaluated by cell growth inhibition assay. Both DHMEQ and GEM monotherapies inhibited cell growth of the human pancreas cell line AsPC-1. However, there was no synergistic effect in the combination therapy. For the in vivo study, male BALB/c nude mice were xenografted with intra-portal vein injection of AsPC-1. Mice were divided into four groups: 1) control (without any treatment), 2) GEM-treated group, 3) DHMEQ-treated group, and 4) combined treatment group (GEM+DHMEQ). Mice were fed for four weeks, and the number of liver metastases, induction of apoptosis in metastasis focuses and angiogenesis were investigated after sacrifice. The number of liver metastasis was decreased significantly in GEM group, DHMEQ group and GEM+DHMEQ group compared with control group. Significant inductions of apoptosis were revealed in GEM group and DHMEQ group compared with control group, in which apoptosis bodies in metastasis sections were counted by using the TUNEL method. Moreover, combination therapy of DHMEQ+GEM resulted in the strongest inductions of apoptosis. Tumor vessels were identified by immunohistochemical staining of tumor metastasis sections with an antibody against CD31. There was a large reduction in the number of CD31-positive vessels in the tumor of DHMEQ or/and GEM-treated mice as compared with control group. However, there was an inconsistency in the results of cell growth inhibition assay (in vitro) and mice metastasis model (in vivo). Thus we evaluated effect of combination therapy in the invasive potential of tumor cells by using chemoinvasion assay. The invasion ability was significantly inhibited in the GEM group, DHMEQ group and GEM+DHMEQ group. Furthermore, real-time PCR was performed to evaluate expression of mRNA of MMP-9. The expression levels of MMP-9 were inhibited in respective groups in the same order. In conclusion, the anti-tumor effects of combination therapy were significant, as evidenced by angiogenesis inhibition, apoptosis induction and invasiveness inhibition rather than cell growth inhibition. Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 103rd Annual Meeting of the American Association for Cancer Research; 2012 Mar 31-Apr 4; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2012;72(8 Suppl):Abstract nr 3840. doi:1538-7445.AM2012-3840