Chapter 5
Partial EMT/MET: An Army of One
Sofiane Hamidi, Hiroki Nagai, and Guojun Sheng
Abstract
As our understanding of Epithelial Mesenchymal Transition (EMT) increases, the original binary concept
of E versus M no longer fits with experimental evidence. Re-definition of the EMT paradigm as spectral
transitions between a full epithelium and a full mesenchyme suggests the existence of a virtual infinity of
intermediate cellular states. The new challenge is to develop technical tools needed to contextualize each of
these states and identify biologically significant cellular mechanisms that could be targeted in combatting
EMT-related diseases.
Key words Epithelial-to-mesenchymal transition, Partial EMT/MET, Morphogenesis, Cancer
EMTs (epithelial mesenchymal transitions) and its reverse METs
(mesenchymal epithelial transitions) are normal morphogenetic
processes in animal development and tissue homeostasis
[1]. EMT/METs are also known to play important roles in abnormal morphogenetic processes such as cancer and fibrosis [2, 3]. The
field of EMT/MET research has been growing exponentially in the
last decade, with over 5000 publications in 2018 alone and with
more papers published in the last 5 years (2015–2019) than in all
the previous 35 years combined (Fig. 1). No research field, however, could sustain exponential growth forever. It is therefore timely
to examine what has made the EMT/MET concept attractive to a
diverse group of researchers and where this field is heading in the
next decade.
Functional compartmentalization in multicellular organisms is
achieved through cell lineage specialization and epithelial barrier
establishment. EMT/METs are involved in the development of all
mesendoderm-derived and some ectoderm-derived cell lineages
that form epithelial barriers in a vertebrate body [1]. Failure in
maintaining their epithelial organization characterizes over 90% of
all human cancers (2014 World Cancer Report). For example, the
top eight human cancer types, together causing 2/3 of all cancer
Kyra Campbell and Eric Theveneau (eds.), The Epithelial-to Mesenchymal Transition: Methods and Protocols,
Methods in Molecular Biology, vol. 2179, https://doi.org/10.1007/978-1-0716-0779-4_5,
© Springer Science+Business Media, LLC, part of Springer Nature 2021
29
Partial EMT/MET: An Army of One
Sofiane Hamidi, Hiroki Nagai, and Guojun Sheng
Abstract
As our understanding of Epithelial Mesenchymal Transition (EMT) increases, the original binary concept
of E versus M no longer fits with experimental evidence. Re-definition of the EMT paradigm as spectral
transitions between a full epithelium and a full mesenchyme suggests the existence of a virtual infinity of
intermediate cellular states. The new challenge is to develop technical tools needed to contextualize each of
these states and identify biologically significant cellular mechanisms that could be targeted in combatting
EMT-related diseases.
Key words Epithelial-to-mesenchymal transition, Partial EMT/MET, Morphogenesis, Cancer
EMTs (epithelial mesenchymal transitions) and its reverse METs
(mesenchymal epithelial transitions) are normal morphogenetic
processes in animal development and tissue homeostasis
[1]. EMT/METs are also known to play important roles in abnormal morphogenetic processes such as cancer and fibrosis [2, 3]. The
field of EMT/MET research has been growing exponentially in the
last decade, with over 5000 publications in 2018 alone and with
more papers published in the last 5 years (2015–2019) than in all
the previous 35 years combined (Fig. 1). No research field, however, could sustain exponential growth forever. It is therefore timely
to examine what has made the EMT/MET concept attractive to a
diverse group of researchers and where this field is heading in the
next decade.
Functional compartmentalization in multicellular organisms is
achieved through cell lineage specialization and epithelial barrier
establishment. EMT/METs are involved in the development of all
mesendoderm-derived and some ectoderm-derived cell lineages
that form epithelial barriers in a vertebrate body [1]. Failure in
maintaining their epithelial organization characterizes over 90% of
all human cancers (2014 World Cancer Report). For example, the
top eight human cancer types, together causing 2/3 of all cancer
Kyra Campbell and Eric Theveneau (eds.), The Epithelial-to Mesenchymal Transition: Methods and Protocols,
Methods in Molecular Biology, vol. 2179, https://doi.org/10.1007/978-1-0716-0779-4_5,
© Springer Science+Business Media, LLC, part of Springer Nature 2021
29