eIF3f reduces tumor growth by directly interrupting clusterin with anti-apoptotic property in cancer cells.

// Ji-Yeon Lee 1 , Hyun-Ji Kim 1 , Seung Bae Rho 2 and Seung-Hoon Lee 1 1 Department of Life Science, YongIn University, Samga-dong Chuingu, Yonginsi, Korea 2 Research Institute, National Cancer Center, Ilsandong-gu, Goyang-si Gyeonggi-do, Korea Correspondence to: Seung-Hoon Lee, email: // Keywords : clusterin, eukaryotic translation initiation factor 3, subunit f, cancer, apoptosis Received : July 28, 2015 Accepted : February 05, 2016 Published : March 15, 2016 Abstract Clusterin is a secretory heterodimeric glycoprotein and the overexpression of secretory clusterin (sCLU) promotes cancer cell proliferation and reduces chemosensitivity. Therefore, sCLU might be an effective target for anticancer therapy. In the current study, we identified eIF3f as a novel CLU-interacting protein and demonstrated its novel function as a CLU inhibitor. The overexpression of eIF3f retarded cancer cell growth significantly and induced apoptosis. In addition, eIF3f interacted with the α-chain (1–227) of sCLU. This interaction blocked modification of psCLU, thereby decreasing the expression and secretion of α/β CLU. Consequently, the overexpression of eIF3f suppressed Akt and ERK signaling and subsequently depleted CLU expression. In addition, eIF3F stabilized p53, which increased the expression of p21 and Bax. Interestingly, the expression of Bax was increased without the activation of p53. eIF3f injected into a xenograft model of human cervical cancer in nude mice markedly inhibited tumor growth. The identification of this novel function of eIF3f as a sCLU inhibitor might open novel avenues for developing improved strategies for CLU-targeted anti-cancer therapies.