Caffeic acid phenethyl ester (CAPE), a honeybee
propolis-derived bioactive ingredient, has not been extensively elucidated regarding its effect on
prostate cancer and associated mechanisms. The mucosa-associated lymphoid tissue 1 gene (MALT1) modulates NF-κB signal transduction in
lymphoma and non-
lymphoma cells. We investigated the functions and regulatory mechanisms of CAPE in relation to MALT1 in prostate
carcinoma cells. In p53- and
androgen receptor (AR)-positive prostate
carcinoma cells, CAPE downregulated AR and MALT1 expression but enhanced that of p53, thus decreasing
androgen-induced activation of MALT1 and
prostate-specific antigen expressions. p53 downregulated the expression of MALT in prostate
carcinoma cells through the putative consensus and nonconsensus p53 response elements. CAPE downregulated MALT1 expression and thus inhibited NF-κB activity in p53- and AR-negative prostate
carcinoma PC-3 cells, eventually reducing cell proliferation, invasion, and
tumor growth in vitro and in vivo. CAPE induced the ERK/JNK/p38/AMPKα1/2 signaling pathways; however, pretreatment with the corresponding inhibitors of MAPK or AMPK1/2 did not inhibit the CAPE effect on MALT1 blocking in PC-3 cells. Our findings verify that CAPE is an effective
antitumor agent for human
androgen-dependent and -independent prostate
carcinoma cells in vitro and in vivo through the inhibition of MALT1 expression via the AR/p53/NF-κB signaling pathways.