Androgen upregulates the palmitoylation of eIF3L in human prostate LNCaP cells

Background: Prostate cancer is the second leading cause of cancer-related deaths in Western countries. Most patients diagnosed with advanced prostate cancer can be treated with the main treatment: androgen deprivation therapy (ADT). The androgen receptor (AR) signaling axis plays a pivotal role in the progression of prostate cancer. However, most patients can ultimately progress to the castration-resistant prostate cancer (CRPC) stage within 2 years. At this stage, drugs targeting the AR signaling axis, including enzalutamide and abiraterone acetate, cannot prevent the progression of prostate cancer, thus predicting a poor prognosis. The molecular mechanism lies in the aberrant AR reactivation, which exhibits an adaptive response to ADT, such as the presence of AR splice variants. Thus, CRPC treatment remains a challenge. Purpose: In addition to the AR axis, a mechanism leading to this progression should be determined. The present study mainly compared palmitoylated proteins between androgen-treated LNCaP cells and non-treated LNCaP cells by palmitoylome profiling, to illustrate the changes at proteomic levels. Materials and methods: To screen the androgen-induced palmitoylated proteins, we conducted proteomic experiments using clickable palmitate probe (Alk-C16) between three individual pairs of androgen-treated and non-treated LNCaP cells. Results: We identified 4351 unique peptides corresponding to 835 proteins, among them a number of these identified proteins were palmitoylated proteins, particularly eIF3L. Androgen treatment significantly increased the palmitoylation level of eIF3L, an individual subunit of eIF3. As an initiation factor, eIF3L plays a pivotal role in the translation of mRNAs encoding growth-promoting proteins by enhancing translation rates, thus controlling cell proliferation. Conclusion: In this study, we demonstrated that the regulation of eIF3L palmitoylation may provide new directions for the therapy of prostate cancer. Moreover, the increased level of androgen-induced eIF3L may be used as a biomarker for the diagnosis of early-stage prostate cancer.