Dystrophin Promotes Colorectal Carcinoma Metastasis and Exosome Secretion via Protein‐Protein Interaction with Rab GTPase 3C

Abstract

RAB GTPases is involved in membrane trafficking (vesicle formation) and cell motility. Recently, exocytotic RABs has been noted that the exocytosis by RABs is correlated with drug resistance and immune response in tumorigenesis. However, the molecular mechanisms of exocytotic RABs in colorectal tumorigenicity remain unknown. RAB GTPase 3C (RAB3C) has been identified as the key component for exosome formation and exocytosis. In clinical colorectal carcinoma patient cohort, high RAB3C expression maintained its independent prognostic significance for both overall survival and disease‐free survival. We further established RAB3C‐based proteomics datasets and mass spectrometry analyses and found dystrophin (DMD) is upregulated in RAB3C ectopically overexpressed colon cancer cell lines. High DMD expression levels were found correlated with poor survival in colorectal cancer patient cohorts. Moreover, Dystrophin‐complex components including dystrobrevin (DTNA) and syntrophin (SNTA1/SNTB1) also showed the same prognosis trends in colorectal cancer patients. We further found that DMD is a rare mutant event in colorectal clinical cohort by next generation sequencing analysis. Our results showed that DMD could be stabilized by RAB3C through protein‐protein interaction. Besides, our results revealed RAB3C co‐localized with dystrophin complex by immunohistochemistry staining analysis. Merged DMD with RAB3C serves as a significant independent prognostic factor in colorectal cancer and is associated with several clinical parameters. In addition, dystrophin complex decreased cell membrane integrity and altered calcium channel activity for exocytosis. In summary, our results identified DMD is a new functional binding protein for RAB3C that affected colorectal carcinogenesis. These findings suggest a new therapeutic strategy for targeting cancer‐specific protein‐protein interactions in the treatment patients with colorectal cancer.This abstract is from the Experimental Biology 2019 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.