BACKGROUNDProstate specific membrane antigen (PSMA) can facilitate the growth, migration, and invasion of the LNCaP prostate cancer cell lines, but the underlying molecular mechanisms have not yet been clearly defined. Here, we investigated whether PSMA serves as a novel regulator of the phosphatidylinositol 3-kinase (PI3K)/Akt signaling by employing PSMA knockdown model and PI3K pharmacological inhibitor (LY294002) in LNCaP prostate cancer cells.

METHODSPSMA knockdown had been stably established by transfecting with lentivirus-mediated siRNA in our previous study. Then, LNCaP cells were divided into interference, non-interference, and blank groups. We first testified the efficacy of PSMA knockdown in our LNCaP cell line. Then, we compared the expression of PSMA and total/activated Akt by Western blotting in the above three groups with or without LY294002 treatment. Furthermore, immunocytochemistry was performed to confirm the changes of activated Akt (p-Akt, Ser473) in groups. Besides, cell proliferation, migration, and cell cycle were measured by CCK-8 assay, Transwell analysis, and Flow cytometry respectively.

RESULTSAfter PSMA knockdown, the level of p-Akt (Ser473) but not of total-Akt (Akt1/2) was significantly decreased when compared with the non-interference and blank groups. However, LY294002 administration significantly reduced the expression of p-Akt (Ser473) in all the three groups. The results of immunocytochemistry further confirmed that PSMA knockdown or LY294002 treatment was associated with p-Akt (Ser473) down-regulation. Decrease of cell proliferation, migration, and survival were also observed upon PSMA knockdown and LY294002 treatment.

CONCLUSIONSTaken together, our results reveal that PI3K/Akt signaling pathway inhibition may serve as a novel molecular mechanism in LNCaP prostate cancer cells of PSMA knockdown and suggest that Akt (Ser473) may play a critical role as a downstream signaling target effector of PSMA in this cellular model.