Proteomic atlas of human peritoneal tissue.

Peritoneal carcinomatosis occurs when the parietal and visceral peritoneum are involved with multifocal metastatic tumors, most commonly arising from abdominopelvic organ sites. The prevailing model of peritoneal carcinomatosis sees the peritoneal lining as the ‘soil’ onto which metastatic cancer cells attach and grow. Molecular methods to assess the functional status of this microenvironment have not been well developed. To address this gap, we analyzed the protein composition of peritoneal tissue using liquid chromatography-tandem mass spectrometry on both fresh frozen and formalin-fixed, paraffin-embedded benign tissue (FFPE) samples, employing an ultra-high-resolution timsTOF mass spectrometer. The protein yield in peritoneal tissue was lower than that observed from similar studies of other visceral organ tissues. Extracellular matrix (ECM) proteins were present in high abundance and may be contributory to cancer cell attachment and invasion in peritoneal carcinomatosis. We further quantified key signal transduction and metabolic proteins known to contribute to cancer progression, along with defined tumor suppressors and oncoproteins. Our findings represent a baseline catalog of the proteomic composition of the peritoneal lining, as a comparison dataset for future studies focused on alterations in pathologic states such as peritoneal carcinomatosis.