Effects of PGRMC1 phosphorylation status on MIA PaCa-2 cells

Progesterone Receptor Membrane Component 1 (PGRMC1) is expressed in many cancer cells, where it is associated with detrimental patient outcomes. Multiple different functions and cellular locations have been attributed to PGRMC1 in a variety of contexts, however the mechanisms underlying PGRMC1 biology remain obscure. The protein contains several phosphorylated residues including tyrosines which were acquired early in animal evolution and could be involved with animal cell differentiation mechanisms. Here we demonstrate that mutagenic manipulation of PGRMC1phosphorylation status in MIA PaCa-2 (MP) pancreatic cells exerts broad pleiotropic effects, influencing cell plasticity and tumorigenicity, as assayed by cell biological and proteomics measurements. Relative to MP cells over-expressing hemagglutinin (HA)-tagged wild-type PGRMC1- HA (WT), cells expressing a PGRMC1-HA-S57A/S181A double mutant (DM) exhibited reduced levels of proteins involved in energy metabolism and mitochondrial function. This was associated with Rho-kinase inhibitor (ROCKI)-sensitive changes including altered cell shape, motility, increased PI3K/Akt and JNK activity, and fragmented mitochondrial morphology. An S57A/Y180F/S181A triple mutant (TM) reduced PI3K/Akt and JNK activation, indicating involvement of Y180. Both TM cells and Y180F single mutant cells exhibited attenuated mouse xenograft tumor growth. Tyrosine 180 phosphorylation status of PGRMC1 exerts dramatic influence over cancer cell biology.