Proteoglycans and their functions in esophageal squamous cell carcinoma

Table 1 Classification of proteoglycans with clinicopathological and/or functional significance in esophageal squamous cell carcinoma[14]

Location	Classification	Gene symbol	Eponym	Predominant GAG	Studied in ESCC	Ref.
Intracellular	Secretory granules	SRGN	Serglycin	Heparin/CS	Serglycin	Zhu et al[57]
Cell-surface	Transmembrane	SDC	Syndecan 1-4	HS/CS	Syndecan-1, -2	Mikami et al[58], Szumilo et al[60] and Huang et al[61]
		CSPG4	NG2	CS/DS
		TGFBR3	Betaglycan	HS/CS
		PTPRZ1	Phosphacan	CS/DS
	GPI-anchored	GPC	Glypican 1-6	HS	Glypican-1, -3	Hara et al[62], Li et al[63], Harada et al[64] and Song[65]
Pericellular	Basement membrane zone	HSPG2	Perlecan	HS/CS
		AGRN	Agrin	HS
		COL18A1	Collagen XVIII	HS	Endostatin	Zheng et al[71], Zhong et al[72] and Chen et al[73]
		COL15A1	Collagen XV	CS/HS
Extracellular	Hyalectans	ACAN	Aggrecan	CS/KS
		VCAN	Versican	CS/DS
		NCAN	Neurocan	CS/DS
		BCAN	Brevican	CS/DS
	SLRPs, Canonical Class I	DCN	Decorin	CS/DS	Decorin	Wu et al[83], Ji et al[84] and Augoff et al[85]
		BGN	Biglycan	CS/DS	Biglycan	Zhu et al[97]
		ASPN	Asporin
		ECM2	ECM2
		ECMX	ECMX
	SLRPs, Canonical Class II	FMOD	Fibromodulin	KS
		LUM	Lumican	KS	Lumican	Kashyap et al[102,103]
		PRELP	PRELP
		KERA	Keratocan	KS
		OMD	Osteoadherin	KS
	SLRPs, Canonical Class III	EPYC	Epiphycan	CS/DS
		OPTC	Opticin
		OGN	Osteoglycin
	SLRPs, Non-Canonical Class IV	CHAD	Chondroadherin
		NYX	Nyctalopin
		TSKU	Tsukushi
	SLRPs, Non-Canonical Class V	PODN	Podocan
		PODNL1	Podocan-Like 1
	SPOCK	SPOCK	Testican 1-3	HS	Testican-1	Song et al[108]

CS: Chondroitin sulfate; DS: Dermatan sulfate; ESCC: Esophageal squamous cell carcinoma; GAG: Glycosaminoglycan; GPI: Glycosylphosphatidylinositol; HS: Heparan sulfate; KS: Keratan sulfate; NG2: Nerve/glial antigen 2; SLRP: Small leucine-rich proteoglycan.