Effect of PACT knockout on LNCaP protate cancer cells

PACT, encoded by the PRKRA gene, is a double-stranded RNA binding protein which has two main mechanisms of action; functioning as an activator of both protein kinase RNA (PKR) and retinoic acid-inducible gene 1 (RIG-1) to facilitate innate antiviral defense mechanisms in mammals; and PACT is also an integral member of the cytoplasmic RNA-induced silencing complex (RISC) which enables the processing of pre-microRNAs into mature microRNAs (miRNAs). We previously described an alternate role for PACT as a nuclear receptor (NR) co-activator, which when recruited to hormone-regulated promoters can modulate the expression of NR-regulated genes. Here we employed a loss of function approach to investigate the role of PACT in prostate cancer (PCa). Depletion of PACT in human PCa cell lines resulted in a significant reduction in cell proliferation. RNA-sequencing analysis of LNCaP PCa cells ± PACT revealed that in the absence of PACT, various biological processes involved in proliferation were depleted, including cell cycle progression and division. Overall design: To investigate the gene expression changes upon the depletion of PACT in prostate cancer cells, we used CRISPR/Cas9 to knockout PACT in LNCaP cells, followed by comparative gene expression profiling analysis using the wild-type LNCaP cells as the control.