Basic Study
Copyright ©The Author(s) 2017. Published by Baishideng Publishing Group Inc. All rights reserved.
World J Gastroenterol. May 21, 2017; 23(19): 3440-3448
Published online May 21, 2017. doi: 10.3748/wjg.v23.i19.3440
Role of AXL in invasion and drug resistance of colon and breast cancer cells and its association with p53 alterations
Wael M Abdel-Rahman, Noura A Al-khayyal, Vidhya A Nair, S R Aravind, Maha Saber-Ayad
Wael M Abdel-Rahman, Department of Medical Laboratory Sciences, College of Health Sciences and Sharjah Institute for Medical Research, University of Sharjah, Sharjah 27272, United Arab Emirates
Noura A Al-khayyal, College of Medicine and Sharjah Institute for Medical Research, University of Sharjah, Sharjah 27272, United Arab Emirates
Vidhya A Nair, S R Aravind, Environment and Cancer Research Group, Sharjah Institute for Medical Research, University of Sharjah, Sharjah 27272, United Arab Emirates
Maha Saber-Ayad, Department of Basic Medical Sciences, College of Medicine, and Sharjah Institute for medical Research, University of Sharjah, Sharjah, Cairo University, Cairo 11523, Egypt
Author contributions: Abdel-Rahman WM supported the study, designed and performed experiments, provided study material, analyzed and interpreted the data and wrote the manuscript; Al-khayyal NA developed the ideas, performed experiments and contributed to data analysis and write up; Nair VA and Aravind SR performed experiments. Saber-Ayad M contributed to some lab work, provided critical insights and contributed to data analysis and write up; all authors revised/endorsed the final draft.
Supported by Terry Fox Foundation for Cancer Research.
Institutional review board statement: No patients or patient derived samples were involved in this study.
Conflict-of-interest statement: The authors have no conflicts of interest to declare.
Data sharing statement: All relevant data were presented in the manuscript. Further information is available from the corresponding author.
Open-Access: This article is an open-access article which was selected by an in-house editor and fully peer-reviewed by external reviewers. It is distributed in accordance with the Creative Commons Attribution Non Commercial (CC BY-NC 4.0) license, which permits others to distribute, remix, adapt, build upon this work non-commercially, and license their derivative works on different terms, provided the original work is properly cited and the use is non-commercial. See: http://creativecommons.org/licenses/by-nc/4.0/
Correspondence to: Wael M Abdel-Rahman, MD, PhD, Associate Professor, College of Health Sciences and Sharjah Institute for Medical Research, University of Sharjah, University City Road, Sharjah 27272, United Arab Emirates. whassan@sharjah.ac.ae
Telephone: +97-165-057556 Fax: +97-165-057515
Received: December 27, 2016
Peer-review started: December 28, 2016
First decision: February 10, 2017
Revised: March 11, 2017
Accepted: April 21, 2017
Article in press: April 21, 2017
Published online: May 21, 2017
Abstract
AIM

To characterize AXL receptor tyrosine kinase (AXL) expression in relationship to tumor protein P53 (TP53 gene, p53 protein) and its role in tumor invasion and response to therapy.

METHODS

We used 14 cell lines, including 3 isogenic pairs carrying mutant/knockout p53, to gain insight into the relationship between AXL and TP53. These included HCT116, HCT116.p53 mutant, RKO, and RKO.p53-/- lines (all from colon cancers) as well as breast cancer cell lines MCF7 and 1001 (MCF7-p53 mutant clone). HeLa cell line was used as a positive control for epithelial to mesenchymal transition (EMT). AXL expression was determined by Western blotting using rabbit monoclonal antibody clone C89E7. AXL siRNA silencing was performed and followed by collagen invasion assay. Cell viability analysis using the sulforhodamine B assay and the invasion assay were performed after exposure to chemotherapeutic agents (doxorubicin for breast cancer cells; 5FU or irinotecan for colon cancer cells).

RESULTS

We showed that the introduction of p53 mutations or knockout increased expression levels of AXL in isogenic cells compared to the matching p53 wild-type parental cells. Overall, we found a trend for correlation between the potential EMT candidate AXL, p53 alterations, and EMT markers in colorectal and breast cancers. The expression of AXL in RKO cells, a rare colon cancer cell line with inactive Wnt signaling, suggests that the AXL oncogene might provide an alternative genetic pathway for colorectal carcinogenesis in the absence of Wnt signaling activation and TP53 mutation. AXL silencing in the TP53 mutant isogenic cell lines 1001, HCT116.p53 mutant and RKO.P53-/- was > 95% efficient and the silenced cells were less invasive compared to the parental TP53 wild-type cells. AXL silencing showed a subtle trend to restore colon cancer cell sensitivity to 5FU or irinotecan. Importantly, AXL expressing cells developed more invasive potential after exposure to chemotherapy compared to the AXL-silenced cells.

CONCLUSION

AXL is influenced by p53 status and could cause the emergence of aggressive clones after exposure to chemotherapy. These findings could have applications in cancer management.

Keywords: AXL, Breast cancer, Chemotherapy, Colon cancer, Invasion

Core tip: AXL receptor tyrosine kinase (AXL) is emerging as an attractive molecular target in cancer therapy. We showed that it is regulated by TP53 in colon and breast cancer cells, and it contributes to epithelial to mesenchymal transition and response to therapy in these tumors. We also showed that it could be linked to other carcinogenic pathways, such as the Wnt/β-catenin signaling pathway in colorectal cancer. These interactions should be considered carefully when designing AXL based therapy, because AXL could trigger the emergence of aggressive clones after inappropriate therapy.