Abstract
Background: The diagnosis and treatment of colorectal cancer has been a research priority and challenge, especially metastatic colorectal cancer. Here we screened for the expression differences of plasma exosomal proteome among patients with metastatic colorectal cancer (mCRC), patients with colorectal cancer (CRC), and healthy controls (HC) in order to enhance the understanding of metastatic disease and provide insights for the diagnosis and treatment of colorectal cancer.
Methods: Plasma samples from 5 patients with mCRC, 5 patients with CRC, and 5 healthy subjects were collected and processed to isolate exosomes by ultracentrifugation. Then, the protein concentration was determined with the BCA kit. Liquid chromatography-mass spectrometry was utilized to identify and analyze the proteins within the plasma exosomes.
Results: We isolated exosomes from plasma samples.A total of 994 quantifiable proteins were detected, including 287 differentially expressed proteins were identified by quantitative proteomics analyses. Among them, 965, 963 and 968 proteins were identified in mCRC patients, CRC patients and HC, respectively. The study identified 83 proteins with differential expression in the plasma exosomes of mCRC patients. The top ten up-regulated proteins in the mCRC group and CRC group included ITGA4, GNAI1, SFTPA2, UGGT, GRN, LBP, SMIM1, BMP1, HMGN5, and MFAP4, while the top ten down-regulated proteins were PSMB8, LCK, RAB35, PSMB4, CD81, CD63, GLIPR2, RAP1B, RAB30, and CES1. Western Blot Analysis validation data confirmed that ITGA4 and GNAI1 were unequivocally enriched in plasma-derived exosomes from mCRC patients.
Conclusions: The differentially expressed proteins in the metastatic colorectal cancer group and colorectal cancer group may play a crucial role in colorectal cancer metastasis. These differential proteins offering potential new candidate molecules for further research on the pathogenesis of mCRC and the identification of therapeutic targets. This study sheds light on the potential significance of plasma exosome proteomics in understanding and treating metastatic colorectal cancer.