Integrin-EGFR interaction regulates anoikis resistance in colon cancer cells
Anoikis resistance is an essential property of cancer cells that allow the extra-cellular matrix-detached cells to survive in a suspended state in body fluid in order to metastasize and invade to distant organs. It is known that integrins play an important role in anoikis resistance, but detailed mechanisms are not well understood. Here we report that highly metastatic colon cancer cells showed a higher degree of anoikis resistance than the normal intestinal epithelial cells. These anoikis-resistant cancer cells express high-levels of integrin-α2, β1, and activated EGFR in the anchorage-independent state than the anchorage-dependent state. In contrast, normal intestinal epithelial cells failed to elevate these proteins. Interestingly, a higher co-association of EGFR with integrin-α2β1/-α5β1 was observed on the surface of anoikis-resistant cells. Thus, in the absence of extra-cellular matrix, integrins in association with EGFR activates downstream effectors ERK and AKT and suppress Caspase-3 activation to induce anoikis resistance as was confirmed from the gene-ablation and pharmacological inhibitor studies. Interestingly, these anoikis-resistant cancer cells express high-level of cancer stem cell signatures (CD24, CD44, CD133, EpCAM) and pluripotent stem cell markers (OCT-4, SOX-2, Nanog) as well as drug-resistant pumps (ABCG2, MDR1, MRP1). Altogether, our findings unravel the interplay between integrin-α2β1/-α5β1 and EGFR in anoikis resistance and suggest that the resistant cells are cancer initiating or cancer stem cells, which may serve as a promising target to combat metastasis of cancer.
KeywordsIntegrin EGFR Anoikis resistance Poly-HEMA HCT116
We acknowledge Dr. Susanta Roychoudhury for providing the HCT116 cell line. Authors are thankful to Mr. R. Dutta, Mr. A. Poddar, Mrs. S. Das, and Mr. S. Chakrabarty, for their technical help. Our work was supported by the grants from the Department of Science & Technology and University Grants Commission, Govt. of India.
DG formulated the project, designed and executed most of the experiments, analyzed related results and wrote the manuscript; TS performed the immunostaining experiments and analyzed the results; SB assisted in cell-culture maintenance; SC analyzed experimental results; SD performed cell viability assays and Western blot experiments; PK analyzed experimental results; AA helped conceptually and gave critical suggestions; TD designed the experiments and edited the manuscript; GS conceptualized the project, designed the experiments, edited the manuscript.
Compliance with ethical standards
Conflict of interest
The authors declare that they have no conflict of interest.
Research involving human participants and animals
This article does not contain any studies with human participants or animals performed by any of the authors.
- 23.Fuji H, Honoki K, Tsujiuchi T, Kido A, Yoshitani K, Takakura Y (2009) Sphere-forming stem-like cell populations with drug resistance in human sarcoma cell lines. Int J Oncol 34(5):1381–1386Google Scholar
- 24.Lin Y, Chen G (2008) Embryoid body formation from human pluripotent stem cells in chemically defined E8 media. StemBook [Internet]. Cambridge (MA): Harvard Stem Cell Institute; 2008-Jun 1Google Scholar
- 35.Beauséjour M, Thibodeau S, Demers MJ, Bouchard V, Gauthier R, Beaulieu JF, Vachon PH (2013) Suppression of anoikis in human intestinal epithelial cells: differentiation state-selective roles of α2β1, α3β1, α5β1, and α6β4 integrins. BMC Cell Biol 14:53. https://doi.org/10.1186/1471-2121-14-53 CrossRefPubMedPubMedCentralGoogle Scholar
- 40.Demers MJ, Thibodeau S, Noël D, Fujita N, Tsuruo T, Gauthier R, Arguin M, Vachon PH (2009) Intestinal epithelial cancer cell anoikis resistance: EGFR-mediated sustained activation of Src overrides Fak-dependent signaling to MEK/Erk and/or PI3-K/Akt-1. J Cell Biochem 107(4):639–654. https://doi.org/10.1002/jcb.22131 CrossRefPubMedGoogle Scholar