Abstract
Autophagy may play a critical role in colon cancer stem cells (CCSCs)-related cancer development. Here, we investigate whether accumulation of infection/injury-induced CCSCs due to impaired autophagy influences colon cancer development and progression. When Apc++ mice were infected with Citrobacter rodentium (CR; 109CFUs), we discovered presence of autophagosomes with increases in Beclin-1, LC3B and p62 staining during crypt hyperplasia. Apc1638N/+ mice when infected with CR or subjected to CR+AOM treatment, exhibited increased colon tumorigenesis with elevated levels of Ki-67, β-catenin, EZH2 and CCSC marker Dclk1, respectively. AOM/DSS treatment of Apc1638N/+ mice phenocopied CR+AOM treatment as colonic tumors exhibited pronounced changes in Ki-67, EZH2 and Dclk1 accompanied by infiltration of F4/80+ macrophages, CD3+ lymphocytes and CD3/β-catenin co-localization. Intestinal and colonic tumors also stained positive for migrating CSC markers CD110 and CDCP1 wherein, colonic tumors additionally exhibited stromal positivity. In tumors from CR-infected, CR+AOM or AOM/DSS-treated Apc1638N/+ mice and surgically-resected colon tumor/metastatic liver samples, significant accumulation of p62 and it's co-localization with LC3B and Dclk1 was evident. ApcMin/+ mice when infected with CR and BLT1-/-;ApcMin/+ mice, exhibited similar co-localization of p62 with LC3B and Dclk1 within the tumors. Studies in HCT116 and SW480 cells further confirmed p62/Dclk1 co-localization and Chloroquin/LPS-induced increases in Dclk1 promoter activity. Thus, co-localization of p62 with Dclk1 may hamper Dclk1's elimination to impact colon cancer development and progression.