Effect Of PARG On The Angiogenesis And Metastasis Of Colon Cancer Cell Allografted Tumors By Akt/NF-κB Pathway

Objective: To investigate the effect of poly-(ADP-ribose)glycohydrolase (PARG) gene deficiency on angiogenesis and livermetastasis of CT26murine colon carcinoma cell allografted tumors and itspossible mechanisms.Methods:1. Mouse allograft tumor models were established byintrasplenic injection of CT26murine colon carcinoma cells that weretransfected with lentivirus which carried PARG-shRNA vector. CT26cells that were untransfected and CT26cells that were transfected withlentivirus which carried empty vector served as control group.2. The intra-tumor microvascular density (iMVD) was detected byImmunohistochemistry (IHC)(SABC). All groups were compared witheach other to confirm differences of iMVD in intrasplenic allograft tumor，metastases in liver and survival time of tumor-bearing mice.3. PARG, poly(ADP-ribose)polymerase-1(PARP-1), protein kinaseB(PKB, Akt), P-Akt473, nuclear factor-kappaB p65(NF-κB p65), vascularendothelial growth factor-A (VEGF-A), basic fibroblast growth factor(bFGF)，P-selectin, intercellular adhesion molecular-1(ICAM-1), and vascuolar cell adhesion molecule-1(VCAM-1) of intrasplenic allografttumor were detected by western blotting.Results:1.Compared to the control groups，iMVD of intrasplenicallograft tumor and metastases of liver were obviously lower in PARGsilenced group (P<0.05), and survival time of tumor-bearing mice wasmore prolonged in PARG silenced group (P<0.05).2. Compared to the control groups, expressions of PARG, PARP-1,NF-κB p65, VEGF-A, bFGF, P-selectin, ICAM-1and VCAM-1ofintrasplenic allograft tumor were obviously lower in PARG silenced group(P<0.05). The expression of P-Akt473was obviously higher in PARGsilenced group (P<0.05). There was no difference for total Akt in variousgroups (P＞0.05).Conclusion: These studies demonstrate that the PARG gene silencedin CT26murine colon carcinoma cells can inhibit in vivo angiogenesisand metastasis of colon carcinoma cells，and that this may be attributed tothe reduction of iMVD and expressions of VEGF-A, b-FGF, P-selectin,ICAM-1and VCAM-1by enhancing Akt phosphorylation and furtherattenuating activation of NF-κB after PARG silenced.