Poster Presentation 26th Annual Lorne Proteomics Symposium 2021

Discovery of organelle membrane remodelling associated with CAV1/CAVIN1 in prostate cancer using integrative Protein and Lipid Organelle Profiling (iPLOP) (#65)

Harley Robinson 1 2 , Michelle Hill 2 3
  1. Faculty of Medicine, The University of Queensland, Brisbane, QLD, Australia
  2. Precision and Systems Biomedicine, QIMR Berghofer Medical Research Institute , Brisbane, QLD, Australia
  3. UQ Diamantina Institute , Brisbane, QLD, Australia

Introduction:

Mammalian cells are compartmentalised into membrane bound organelles, where dysregulated membrane composition leads to loss of organelle homeostasis and may underlie chronic diseases. The cholesterol-binding protein caveolin-1 (CAV1) normally forms specialised caveolae structures at the plasma membrane with the co-factor protein cavin-1 (CAVIN1). However, CAV1 is expressed in advanced prostate cancer without CAVIN1, exemplified by PC3 cells. Ectopic expression of CAVIN1 in PC3 cells lead to caveola formation at the plasma membrane and attenuated prostate cancer progression in vivo (1). In addition to plasma membrane structure changes, PC3-CAVIN1 cells showed redistribution of cholesterol to intracellular compartments (2), therefore, we hypothesize that membrane remodelling modulated by CAVIN1 regulates oncogenic organelle function in prostate cancer. 

Methods:

To enable comprehensive evaluation of organelle composition and proteo-lipid interactions, we developed an integrative Protein and Lipid Organelle Profiling (iPLOP) workflow which incorporates density gradient organelle fractionation with lipidomic (Dynamic MRM) and proteomic (DDA MS/MS) profiling. Here, we used iPLOP to discover organelle lipidomic changes associated with PC3-CAVIN1 cells compared to PC3-CONT cells, and then conducted validation using cell-based assays.

Results:

iPLOP workflow yielded two major findings which may underpin the reduced aggressiveness in PC3-CAVIN1 cells: reduced long unsaturated lipids in the mitochondria and endoplasmic reticulum (ER), and elevated lipid droplets. Lipid droplets, mitochondrial and ER membrane composition and function have been associated with cancer hallmarks (3). These results were functionally validated using cell and spectrometry-based assays. Combined with further functional assessment revealed possible links between the membrane remodelling and oncogenic phenotypes.  

Conclusions:

iPLOP allowed discovery of CAVIN1-induced organelle remodelling in prostate cancer. This unbiased organelle profiling method can facilitate discovery in other cell systems and disease models associated with membrane remodelling.  

  1. 1. Moon et al. 2014 Oncogene 33:3561-70.
  2. 2. Inder et al. 2012 Mol Cell Proteomics. 11:M111.012245
  3. 3. Molendijk et al. 2020 Molecular Omics. 17:6-18.