Decreasing P-selectin and ICAM-1 via activating Akt: a possible mechanism by which PARG inhibits adhesion of mouse colorectal carcinoma CT26 cells to platelets

Poly (ADP-ribose) glycohydrolase (PARG), which was discovered during studies on DNA damage study and in inflammation research, is an attractive target protein in current cancer research. The enzymatic hydrolysis of poly (ADP-ribose) (PAR) has not been clarified in the regulation of cancer. The purpose of this study was to understand the relationship between PARG and the adhesion of colorectal carcinoma CT26 cells to platelets. PARG was silenced by short hairpin RNA (shRNA) transfection in CT26 cells. A fluorescence method was used to identify adhesion of CT26 cells to platelets and the expression of poly (ADP-ribose) polymerase (PARP)-1, p-Akt, nuclear factor kappa-B (NF-κB), P-selectin and intercellular adhesion molecule-1 (ICAM-1) was analyzed by western blot in various treated groups and control groups. The results were as follows: (a) PARG silencing led to inhibition of adhesion of CT26 cells to platelets, whereas an inhibitor of p-Akt boosted adhesion of PARG-short hairpin RNA interference (shRNAi) CT26 cells to platelets; (b) a PARP-1 inhibitor depressed the expression of P-selectin and ICAM-1 in CT26 cells; (c) PARG silencing increased phosphorylation of Akt and decreased expression of PARP-1, NF-κB, ICAM-1 and P-selectin in CT26 cells; and (d) a p-Akt inhibitor intensified expression of NF-κB, ICAM-1 and P-selectin in PARG-shRNAi CT26 cells accordingly. These results showed the effectiveness of knockout of PARG in inhibiting adhesion of CT26 cells to platelets and its connection with the phosphatidylinositol 3 kinase/Akt pathway.