Retinoic acid receptor beta promoter methylation and risk of cervical cancer

Table 1 The summary of the articles that investigated the methylation of RARβ gene in tumor tissue from women diagnosed with squamous intraepithelial lesion and cervical cancer

Ref.	Year of publication	Nationality of participants	Sample size	Source of samples	Lab technique	RARβ methylation results
Virmani et al[57]	2001	American	Normal/LSIL = 37	Normal/LSIL/HSIL from liquid-based cytology specimen	MSP	RARβ methylation positive in
			HSIL = 17	ICC from biopsy tissue		Normal/LSIL = 11% HSIL = 29%
			ICC = 19			ICC = 26%
Narayan et al[56]	2003	Colombians	Normal = 8	Normal = cells from cervical swab LSIL/HSIL = formalin-fixed and paraffin-embedded	MSP	RARβ methylation positive in
		German	LSIL = 9	cervical tissues		Normal = 0% SCC/AC = 29.3%
		American	HSIL = 30	SCC/AC = tumor biopsies	Immuno-histochemistry of RARβ protein	Immunohistochemistry
			SCC = 77			LSIL; 11% showed low expression
			AC = 5			HSIL; 60% showed complete lack of expression
Gustafson et al[37]	2004	American	Normal = 11	Liquid-based cytology specimen	Nested MSP	RARβ methylation positive in
			LSIL = 17			Normal = 0% LSIL = 0%
			HSIL = 11			HSIL = 9.1%
Feng et al[58]	2005	Senegalese	Normal/ASCUS = 142	Exfoliated cervical cells and tissue biopsy	MSP	RARβ methylation positive in
			CIN I = 39			Normal/ASCUS = 3.2%
			CIN II = 23			CIN I = 0%
			CIN III = 23			CIN II = 0%
			ICC = 92			CIN III = 15.8% ICC = 38.2%
Wisman et al[59]	2006	Dutch	Normal = 19	Cervical scraping	QMSP	The percentage of RARβ methylation level above control ratio were detected in Normal = 0% SCC = 15% AC = 25%
			SCC = 20
			AC = 8
Choi et al[60]	2007	Korean	Normal = 37	Normal cells were from hysterectomy due to myoma	MSP	RARβ methylation positive in
			SCC = 37	Cancer cells were from tissue after surgery	Immuno-histochemistry of RARβ protein	Normal = 0% SCC = 41%
						Immunostaining normal = strong staining
						SCC = 43% absent staining
Zhang et al[52]	2007	Japanese and Chinese	Normal = 6	Cervical tissue by biopsy or surgery	Real-time PCR for RARβ mRNA	RARβ expression level among normal cells: All were highly expressed
			ICC = 17			RARb2 expression level among cancer cells:
					Semi-nested MSP	13/17: Completely repressed
						2/17: Highly repressed
						2/17: Moderately down-regulated
						Among 13 samples with completely repressed mRNA expression
						9 promoter methylated, 4 unmethylated
Flatley et al[2]	2009	English	Normal = 58	Exfoliated cervical cells and cervical biopsy	Nested MSP	RARβ methylation positive in
			CIN I = 68			Normal = 6.5%
			CIN II = 56			CIN I = 42.6%
			CIN III = 76			CIN II = 6.3%
			ICC = 50			CIN III = 0% ICC = 15.9%
Kim et al[54]	2010	Korean	Normal = 41	Liquid based cytology specimen	Multiplex nested MSP	RARβ methylation positive in
			LSIL = 32			Normal = 4.9% LSIL = 15.6%
			HSIL = 67 SCC = 69			HSIL = 46.3% SCC = 53.6%
Kim et al[61]	2010	Korean	Normal = 28	Liquid based cytology specimen	Multiplex QMSP	RARβ methylation level
			LSIL = 26			Normal = 1.59+3.51% LSIL = 3.67+9.09%
			HSIL = 45 SCC = 63			HSIL = 21.93+20.10% SCC = 19.06+19.39%
Yang et al[62]	2010	Dutch	Normal = 20	Biopsy tissue	QMSP	RARβ methylation positive (from tissue) in
			LSIL = 20			Normal = 85% LSIL = 65%
			HSIL = 20	Cervical scraping only available in subset of samples		HSIL = 75% SCC = 85% AC = 85%
			SCC = 40			RARβ methylation positive (from scraping) in
			AC = 20			Normal = 44% LSIL = 37.5%
						HSIL = 55.6% SCC = 83.8% AC = 100%
						The median methylation level increased significantly with the severity of lesion (P < 0.05)
Pathak et al[63]	2012	Indian	Normal = 35	Normal cells from hysterectomy SIL from excision ICC from tissue biopsy	MSP	RARβ methylation positive in
			SIL = 27			Normal = 11.4% SIL = 55.5% ICC = 57.8%
			ICC = 38
Milutin Gašperov et al[64]	2015	Croatian	Normal = 40	Cervical scraping	MSP	RARβ methylation positive in
			CIN I = 40			Normal = 62.5%
			CIN II = 40			CIN I = 35%
			CIN III = 42			CIN II = 61.5%
			SCC = 8 AC = 3			CIN III = 61.9% SCC/AC = 90%
Sun et al[51]	2015	Chinese	Normal = 48	Liquid based cytology specimen	Methylation specific high resolution melting analysis (Quantitative)	RARβ methylation positive in
			CIN I = 54			Normal = 31.3% CIN I = 35.2%
			CIN II = 47			CIN II and III = 28.2% SCC = 33.3%
			CIN III = 56			RARβ methylation level: none = 68.8%
			SCC = 45			0-5% methylation = 26.4% 5-25% = 4.8%

CIN: Cervical intraepithelial neoplasia; SIL: Squamous intraepithelial lesion; LSIL: Low-grade squamous intraepithelial lesion; HSIL: High-grade squamous intraepithelial lesion; SCC: Squamous cell carcinoma of the cervix; AC: Adenocarcinoma of cervix; ICC: Invasive cervical cancer; MSP: Methylation-Specific Polymerase Chain Reaction; QMSP: Quantitative methylation-specific polymerase chain reaction; ASCUS: Atypical squamous cells of undetermined.