Table 1.

Summary of pEMT markers

E/M Markers used to characterize pEMT phenotypea	Proposed pEMT Markers	Cancer	Cell Lines	Microenvironmental Factor	Tumor Model (in vitro/in vivo)	Significance	Ref.
Tumor-intrinsic factors
ECAD, ZO1/SNAI1, VIM, β-catenin	S100A6	Breast cancer	MCF-7	Acidic microenvironment (pH 6.5 $\sim$ 2 months)	In vitro	Acidic-adaptation-induced pEMT phenotype with MCF-7 cells expressing high VIM and loss of β-catenin, ZO-1, SNAI1 while maintaining expression of ECAD. S100A6 proteins induced pEMT phenotype in acid-adapted MCF-7 cells.	Sadeghi et al., 2020
ECAD/VIM	-	Breast cancer	MCF-7, T47D, MDA-MB-231, MDA-MB-468	Hypoxia (5% O2)	In vitro	pEMT cells had increased migration potential	Chen et al., 2018a
ECAD/VIM	-	Breast cancer	T47D	Hypoxia (Tumor—intrinsic)	In vitro	pEMT cells localized to leading edge of migratory tumors linking role of pEMT to collective migration	Singh et al., 2018a
ECAD/VIM	VEGF	Esophageal squamous cell carcinoma	KYSE140, KYSE180, KYSE510, KYSE520	Hypoxia (1% O2)	In vitro	pEMT cells along with elevated VEGF generated invasive TME	Li et al., 2014
ECAD/VIM	-	Pancreatic cancer	BxPc-3, Panc-1	Hypoxia (0.1% O2$\sim$ 2 to 96 h)	In vitro	pEMT cells had increased migration potential	Lundgren et al., 2009
ECAD/ZEB1	NRF2	Non-small-cell lung carcinoma, Bladder cancer	H1975 RT4	Tumor intrinsic metabolism	In vitro	NRF2 activated and stabilized pEMT phenotype	Bocci et al., 2019
Extracellular matrix (ECM)-related factors
ECAD/VIM	-	Pancreatic cancer	BxPc-3	Collagen and fibronectin matrix	In vitro	pEMT cells migrated with amoeboid mode or filopodium-like protrusions by ECM remodeling (collagen degradation and re-orientation of fibronectin matrix)	Kim et al., 2020
ECAD/ FN1, MMP1	L1CAM	Colorectal cancer	Caco-2	L1CAM, α-2, α-5, and β-1 integrins, FN1	In vitro	Loss of NEO1 induced pEMT through ECM remodeling i.e. upregulation of L1CAM, α-2, α-5, β-1 integrins, and FN1	Chaturvedi et al., 2019
ECAD/ VIM	Cathepsin B	Salivary adenoid cystic carcinoma	SACC-83	Cathepsin B	In vitro	Leader cells expressed pEMT markers and cathepsin B, which facilitated ECM remodeling and tumor invasion	Wu et al., 2019
ECAD/VIM, ZEB2	COL2A1, FN1	Hepatocellular carcinoma	Huh7	FN1, COL2A1	In vitro	pEMT cells in exosomal secretion expressed COL2A1 and FN1	Karaosmanoglu et al., 2018
ECAD/NCAD, ZEB2	-	Breast cancer	EpH4	Alginate matrix	In vitro	pEMT cells showed front-back polarity and aggressive phenotype	Bidarra et al., 2016
ECAD/SNAI1, SNAI2	Laminin 5	Hepatocellular carcinoma	Hep3B	Laminin 5	In vitro	Laminin 5 induced pEMT phenotype	Giannelli et al., 2005
Stromal-cell-related factors
•Cancer-associated fibroblasts
ECAD/ZEB1	-	Breast cancer	MCF-7, NOG mice	Stromal fibroblasts	In vitro/in vivo	CAFs secreted SDF1 drive collective migration of pEMT cells	Matsumura et al., 2019
ECAD/VIM	-	Pancreatic cancer	BxPc-3, Panc-1	CAFs	In vitro	CAFs stabilized pEMT state and increased migration and invasion	Shan et al., 2017
100 pEMT gene signature	-	Head and neck cancer	SCC9	CAFs	In vitro and patient samples	Paracrine interactions of CAFs and tumor cells promoted pEMT phenotype vai TGFB/TGFBI axis	Puram et al., 2017
ECAD/ VIM	CD44	NSCLC adenocarcinoma	HCC827, H3255, A549	Stromal fibroblasts	In vitro	Fibroblasts in TME drive pEMT phenotype	Karacosta et al., 2019
•Adipocyte tissue derived stromal cells
ECAD/CLDN7	-	Breast cancer	MDA-MB-231, Hs578t	Adipocyte	In vitro	Mature adipocytes induced pEMT phenotype	Pallegar et al., 2019
ECAD/VIM	-	Breast cancer	MCF-10A	Leptin (adipocyte-secreted hormone)	In vitro	Leptin induced pEMT at leading edge and induced collective migration	Villanueva-Duque et al., 2017
•Tumor associated macrophages (TAMs)
ECAD/VIM, SNAI2	-	Breast cancer	MCF-7, T47D	M1 TAMs	In vitro	M1 TAMs secretome derived pEMT phenotype, increased migration and invasion	Bednarczyk et al., 2018

Cadherin 2 (NCAD), claudin 7 (CLDN7), collagen type II alpha 1 (COL2A1), E-cadherin (ECAD), extracellular matrix (ECM), fibronectin 1 (FN1), L1 cell adhesion molecule (L1CAM), matrix metalloproteinase-1 (MMP1), partial EMT (pEMT), neogenin 1 (NEO1), NOD/Shi-scid IL2 $\gamma$ null (NOG), non-small-cell lung carcinoma (NSCLC), snail family transcription repressor 1 (SNAI1), snail transcription repressor 2 (SNAI2), vascular endothelial growth factor (VEGF), transforming growth factor beta (TGFB), transforming growth factor beta induced (TGFBI), tumor microenvironment (TME), vimentin (VIM), zinc finfer E-box-binding homeobox 1 (ZEB1), zinc finger E-box-binding homeobox 2 (ZEB2), zonula occludens 1 (ZO1).

^aFew studies used multiple epithelial and mesenchymal markers to characterize pEMT phenotype, which are being listed using “/” between epithelial and mesenchymal markers.