Lipin-1 inhibition alters the transcriptome and lipidome of castration-resistant prostate cancer cells
The lipin family consists of three members (lipin-1, lipin-2 and lipin-3) that are phosphatidate phosphatases. Lipins facilitate lipid synthesis and remodeling through the conversion of phosphatidic acid to diacylglycerol. Lipin-1 and lipin-2 are also transcriptional co-regulators of peroxisome proliferator-activated receptors (PPARs). Our previous studies showed differential lipin-1 expression in numerous prostate cancer cell lines, and the lipin-1 expression was higher in cells representing advanced prostate cancer. However, the role of lipin-1 in prostate cancer cell growth is not fully understood. This study addressed the role of lipin-1 in prostate cancer cell function by performing RNA sequencing and qualitative LC-MS/MS analysis in PC-3 cells in which the gene for lipin-1 (LPIN1) was genetically inhibited. Transcriptomic and lipidomic analyses of LPIN1 knockdown PC-3 cells demonstrated alterations in the expression of numerous genes and the peak intensities of several lipids. The genes and lipids aligned with pathways that mediate focal adhesion, glycerophospholipid metabolism (GM), and PPAR signaling. Additionally, treatment of PC-3 cells with curcumin, a suggested inhibitor of lipin, decreased lipin-1 and lipin-3 expression, with no effect on lipin-2 expression. Bioinformatic analysis of prostate cancer patients demonstrated a correlation between LPIN3 mRNA expression and higher Gleason scores (8-10). These data show the novel findings that lipin-1 mediates the lipidome of castration-resistant prostate cancer cells and identified several pathways that it regulates, beyond GM and PPAR. Additionally, these data suggest that curcumin may be used to treat advanced prostate cancer that overexpresses lipin-3. Overall design: To investigate the role of lipin-1 in the progression of prostate cancer, we established PC-3 cell lines in which each target LPIN1 gene sequence has been knocked down by shRNA lentiviral particles. We then performed gene expression profiling analysis using data obtained from RNA-seq of five different passages of the PC-3 cell line transfected with either a blank/control sequence (shRNA control) or part of the sequence for the LPIN1 gene (Targets A and B) to knockdown the gene.