TRIP6 disrupts tight junctions to promote metastasis and drug resistance and is a therapeutic target in colorectal cancer.

ABSTRACT

Metastasis is the primary cause of death in colorectal cancer (CRC). Thyroid hormone receptor interacting protein 6 (TRIP6) is an adaptor protein that regulates cell motility. Here, we aim to elucidate the role of TRIP6 in driving CRC tumorigenesis and metastasis and evaluate its potential as a therapeutic target. TRIP6 mRNA is up-regulated in CRC compared to adjacent normal tissues in three independent cohorts (all P < 0.0001), especially in liver metastases (P < 0.001). High TRIP6 expression predicts poor prognosis of CRC patients in our cohort (P = 0.01) and TCGA cohort (P = 0.02). Colon-specific TRIP6 overexpression (Trip6KIVillin-Cre) in mice accelerated azoxymethane (AOM)-induced CRC (P < 0.05) and submucosal invasion (P < 0.0001). In contrast, TRIP6 knockout (Trip6+/- mice) slowed tumorigenesis (P < 0.05). Consistently, TRIP6 overexpression in CRC cells promoted epithelial-mesenchymal transition (EMT), cell migration/invasion in vitro, and metastases in vivo (all P < 0.05), whereas knockdown of TRIP6 exerted opposite phenotypes. Mechanistically, TRIP6 interacted PDZ domain-containing proteins such as PARD3 to impair tight junctions, evidenced by decreased tight junction markers and gut permeability dysfunction, inhibit PTEN, and activate oncogenic Akt signaling. TRIP6-induced pro-metastatic phenotypes and Akt activation depends on PARD3. Targeting TRIP6 by VNP-encapsulated TRIP6-siRNA synergized with Oxaliplatin and 5-Fluorouracil to suppress CRC liver metastases. In conclusion, TRIP6 promotes CRC metastasis by directly interacting with PARD3 to disrupt tight junctions and activating Akt signaling. Targeting of TRIP6 in combination with chemotherapy is a promising strategy for the treatment of metastatic CRC.