Proximity-dependent mapping of the Androgen Receptor identifies Kruppel-Like Factor 4 as a functional partner

Prostate cancer (PCa) is the most frequently diagnosed cancer in men and the third cause of cancer mortality. PCa initiation and growth is driven by the androgen receptor (AR). The AR is activated by androgens such as testosterone and controls prostatic cell proliferation and survival. Here, we report an AR signalling network generated using BioID proximity labeling proteomics in androgen-dependent LAPC4 cells. We identified 31 AR associated proteins in non-stimulated cells. Strikingly, the AR signalling network increased to 182 and 200 proteins, upon 24h or 72h of androgenic stimulation, respectively, for a total of 267 total non-redundant AR-associated candidates. Among the latter group, we identified 213 proteins that were not previously reported in databases. Many of these new AR-associated proteins are involved in DNA metabolism, RNA processing and RNA polymerase II transcription. Moreover, we identified 44 transcription factors, including the Krüppel-like factor 4 (KLF4), which were found interacting in androgen-stimulated cells. Interestingly, KLF4 repressed the well-characterized AR-dependent transcription of the KLK3 (PSA) gene; AR and KLF4 also colocalized genome-wide. Taken together, our data report an expanded high-confidence proximity network for AR, which will be instrumental to further dissect the molecular mechanisms underlying androgen signalling in PCa cells. Genome-wide binding of KLF4 and AR transcription factors in control and DHT-stimulated LAPC4 cells