Co-localization of autophagy-related protein p62 with cancer stem cell marker dclk1 may hamper dclk1's elimination during colon cancer development and progression.

Badal Chandra Roy,Joseph Valentino,Shrikant Anant,Venkatakrishna Jala,John Ashcraft,Satish Ramalingam,Shahid Umar,Ishfaq Ahmed,Bodduluri Haribabu,Prabhu Ramamoorthy,Venkatesh Sampath

doi:10.18632/oncotarget.26684

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.

Highlights

Autophagy is a cellular mechanism for the degradation and recycling of cellular components via the lysosomal pathway and is important for the survival and homeostasis [1]
Previous studies have demonstrated that autophagy in intestinal epithelial cells plays an important role in host defense against Citrobacter rodentium (CR) infection and the regulation of CR-induced infectious colitis [4]
We examined the components of the autophagic machinery and a probable link between autophagy and cancer stemness based on the hypothesis that infection and/or injury-related alterations in autophagy may hamper Cancer stem cells (CSCs) elimination which may lead to colon cancer development and/or progression

Summary

Introduction

Autophagy is a cellular mechanism for the degradation and recycling of cellular components via the lysosomal pathway and is important for the survival and homeostasis [1]. It is well established that autophagy is used as a defense mechanism to combat infection of host cells by intracellular pathogens [2, 3]. Several of these pathogens have developed mechanisms to bypass the autophagic response to promote their survival and proliferation and simultaneously affect the host inflammatory responses. Previous studies have demonstrated that autophagy in intestinal epithelial cells plays an important role in host defense against Citrobacter rodentium (CR) infection and the regulation of CR-induced infectious colitis [4]. A systematic role for infection or chemical stressors (e.g., AOM or DSS) or a combination thereof, on either autophagy induction or autophagy-related impairment that leads to pro-survival mechanisms culminating in tumorigenesis, has not been thoroughly investigated

Methods

Results

Conclusion