Risk factors for neoplastic progression in Barrett’s esophagus

Table 1 Published evidence from selected studies investigating genetic and epigenetic changes implicated in the metaplasia-dysplasia-carcinoma sequence of Barrett’s esophagus

Factor	Summary of major findings/conclusions	Ref.
Growth self-sufficiency
Cyclin D1	↑ nuclear cyclin D1 immunostaining in 46% BE specimens: -?cyclin D1 overexpression early event in MDC sequence	Arber et al[9]
	↑ nuclear cyclin D1 immunostaining in 64% EAC specimens	Arber et al[13]
	Cyclin D1 expression correlates with degree of dysplasia in BE	Coppola et al[14]
	Cyclin D1 expression 43% BE mucosa (vs 0% normal mucosa)	Umansky et al[15]
	Polyphenon E inhibits growth of BE and EAC cells via downregulation of cyclin D1 expression	Song et al[16]
Cyclin E	↑ cyclin E expression in neoplastic cells in BE	Coppola et al[14]
	Cyclin E expression 37% BE mucosa (vs 0% normal mucosa)	Umansky et al[15]
p27Kip-1	83% EAC specimens displayed low p27 protein levels (despite high p27 mRNA): -p27 inactivated in most BE-associated EAC (post-transcriptional modification)→loss of cell cycle inhibition	Singh et al[17]
	Experimentally-induced BE and EAC development in mouse model significantly enhanced by p27 gene knockout	Ellis et al[18]
EGF (and EGF-R)	↑ EGF in cytoplasm of BE epithelial cells (vs gastric mucosa)	Jankowski et al[19]
	EGF-R expression area in inflamed mucosa (43.1%) significantly > normal mucosa (29.5%); all BE showed positive EGF-R staining	Jankowski et al[20]
	EGF/EGF-R expression significantly ↑ in BE and EAC mucosa (vs normal mucosa) by flow cytometry (P < 0.01)	Jankowski et al[21]
	EGF-R expression positive in 64% of BE-associated EAC; ↑ staining associated with poorer survival (P = 0.004)	Yacoub et al[22]
	EGF A61G G/G genotype associated with >double EAC risk in BE pts (vs A/A or A/G) (OR 2.2)	Lanuti et al[23]
TGF-α	↑ TGF-α expression in cells from BE and EAC mucosa (vs normal gastric mucosa) by flow cytometry (P < 0.01)	Jankowski et al[21]
	TGF-α expression positive in 100% of BE-associated EAC	Yacoub et al[22]
HGF (and HGF-R)	HGF expression significantly ↑ in BE specimens (vs normal esophageal mucosa)	Konturek et al[24]
	Intense HGF-R immunostaining in 100% EAC and dysplastic BE specimens (vs minimal staining in non-dysplastic BE or normal mucosa); HGF-R mRNA and protein levels ↑ in EAC cell lines	Herrera et al[25]
Erb family tyrosine kinases	Membranous c-erbB2 overexpressed in 26% EAC (vs 0% BE with dysplasia): -?later event in MDC sequence	Hardwick et al[26]
	c-erbB-2 gene amplification in 14% EAC vs 11% HG-dysplasia vs 0% metaplasia/LG-dysplasia specimens	Geddert et al[27]
FGF	Immunostaining intensity for FGF sequentially ↑ from metaplasia/LG-dysplasia (negligible)→HG-dysplasia (weak/moderate)→EAC (moderate/strong)	Soslow et al[28]
	FGF-1 mRNA and protein expression sequentially ↑ in HG-dysplasia/EAC (vs metaplasia/LG-dysplasia/controls)	Soslow et al[29]
Src family tyrosine kinases	Src-specific activity 3-4-fold ↑ in BE and 6-fold ↑ in EAC (vs controls): -?Src activation early event in MDC sequence	Kumble et al[30]
	Strong Src expression in 85% EAC vs 93% BE HG-dysplasia vs 72% BE LG-dysplasia vs 27% BE specimens	Iravani et al[31]
Insensitivity to anti-growth signals
p16	9p21 (p16) LOH observed in 89% EAC specimens (vs 0% non-dysplastic BE); homozygous p16 deletion in only 25%	González et al[32]
	p16 promoter hypermethylation (inactivation) in 75% BE with HG-dysplasia vs 56% LG-dysplasia (vs 3% non-dysplastic BE)	Klump et al[8]
APC	5q (APC) LOH seen in 80% EAC specimens (and surrounding mucosa)	Barrett et al[33]
	APC gene LOH observed in 60% EAC specimens (vs 0% non-dysplastic BE)	González et al[32]
	APC promoter hypermethylation in 92% EAC vs 40% BE (vs 0% normal esophageal tissues)	Kawakami et al[34]
Avoidance of apoptosis
p53	Positive p53 immunostaining in 87% EAC vs 55% BE with HG-dysplasia vs 9% LG-dysplasia vs 0% non-dysplastic BE	Younes et al[35]
	17p (p53) LOH found in 91% BE pts who developed aneuploid cell populations: -17p allelic losses precede aneuploidy	Blount et al[36]
	p53 overexpression in 64% EAC vs 31% dysplastic BE vs 0% non-dysplastic BE; trend of ↑ p53 expression with ↑tumour grade: -?p53 mutation early event in malignant progression	Symmans et al[37]
	p53 immunoreactivity only in EAC/BE with HG-dysplasia (not in BE with LG-/no dysplasia); mutated p53 in 69%: -?late event in MDC sequence (during transition to HG-dysplasia)	Rice et al[38]
	p53 protein expression in 85% EAC specimens vs 60% BE with HG-dysplasia vs 7% LG-dysplasia (P < 0.001)	Rioux-Leclercq et al[39]
	p53 mutations identified in 75% EAC specimens; p53 overexpression in 58% EAC vs 60% BE with HG-dysplasia vs 12% LG-dysplasia vs 0% non-dysplastic BE	Chung et al[40]
Fas (CD95)	↓ surface expression of Fas observed in EAC specimens; impaired translocation of Fas to membrane wild-type Fas protein retained in cytoplasm in EAC cell line: -?potential mechanism by which EAC cells evade Fas-mediated apoptosis	Hughes et al[41]
	↓ surface expression of Fas and resistance to Fas-mediated apoptosis observed in EAC cell lines	Mahidhara et al[42]
Bcl-xl/Bax/Bcl-2	Bcl-xl positive in all dysplasia and EAC cells, but negative in 47% non-dysplastic BE: -?switch to anti-apoptotic phenotype in transformation from metaplasia to EAC	van der Woude et al[43]
	Bcl-2 expression in 84% LG-dysplasia vs 0% HG-dysplasia or EAC	Rioux-Leclercq et al[39]
	Cytoplasmic Bcl-xl immunostaining in 59% EAC vs 71% BE/HG-dysplasia vs 60% LG-dysplasia vs 27% non-dysplastic	Iravani et al[31]
COX-2	↑ COX-2 mRNA levels in 80% BE and 100% EAC specimens (vs normal gastric controls) (P < 0.001); COX-2 immunostaining strongly positive in 100% BE samples (> gastric controls)	Wilson et al[44]
	COX-2 immunopositivity in 91% non-dysplastic BE vs 94% dysplastic vs 97% EAC	Lagorce et al[45]
	Natural/synthetic COX-2 inhibitors suppressed proliferation, induced apoptosis and blocked cell cycle in EAC cell lines	Cheong et al[46]
	Cox-2 mRNA strongly upregulated in experimentally-induced BE epithelium in rat model (vs absent in control animals); COX-2 overexpression observed in human BE patients with dysplasia	Majka et al[47]
Limitless replicative potential
Telomerase	Telomerase RNA positive in 100% EAC/BE with HG-dysplasia vs 90% LG-dysplasia vs 70% non-dysplastic BE: marked ↑ telomerase RNA accompanies transition along MDC sequence	Morales et al[48]
	human telomerase reverse transcriptase (catalytic subunit of telomerase) expression ↑ at all stages of BE vs normal controls, and in EAC (P = 0.003) and dysplastic BE (P = 0.056) vs non-dysplastic BE	Lord et al[49]
	Telomerase activity (by telomeric repeat amplification protocol assay) ↑ in EAC samples vs adjacent mucosa (P = 0.0002) and in EAC vs BE (P = 0.001); no difference BE vs adjacent mucosa	Barclay et al[50]
	Telomerase inhibition (by small interference RNAs) induced senescence in 40% and apoptosis in 86% in BE cell lines	Shammas et al[51]
Sustained angiogenesis
VEGF (and VEGF-R)	VEGF expression correlated with higher vascularisation in BE and EAC specimens	Couvelard et al[52]
	VEGF-A expressed in BE epithelium; VEGFR-2 strongly expressed in immature endothelial cells feeding BE epithelium; ↑ VEGF-C expression in BE (vs absent in normal epithelium); ↑ VEGFR-3 in EAC: ?aberrant neovasculature early in MDC sequence	Auvinen et al[53]
	VEGF expressed in 64% EAC specimens; significantly correlated with angiolymphatic invasion/survival	Saad et al[54]
	VEGF expression significantly ↑ in EAC (> dysplastic BE > BE > normal epithelium)	Griffiths et al[55]
Invasive/metastatic potential
CAMs	↓ expression in EAC specimens of E-cadherin (in 74%), α-catenin (60%) and β-catenin (72%)	Krishnadath et al[56]
	Abnormal expression of β-catenin (P = 0.022), α-catenin (P < 0.01) and E-cadherin (P = 0.049) significantly associated with higher degrees of BE-related dysplasia	Washington et al[57]
	↓ expression of E-cadherin with progression along MDC sequence (P < 0.01); in contrast P-cadherin absent from BE (± dysplasia) but expressed in 67% EAC specimens	Bailey et al[58]
	Slug (E-cadherin repressor) immunostaining and mRNA levels overexpressed in EAC vs BE metaplasia specimens: -?Slug upregulation represents mechanism of E-cadherin silencing	Jethwa et al[59]
Cathepsins	Detected amplicon at chromosome 8p22-23 resulting in cathepsin B overexpression (observed in 73% EAC samples)	Hughes et al[60]
	↑ cathepsin C expression in EAC (vs BE vs normal) in rat model	Cheng et al[61]
CD44	Stepwise ↑ cathepsin D mRNA levels in GERD→BE→EAC tissue	Breton et al[62]
	CD44-H and -V6 variant frequently expressed in BE; differing expression patterns along spectrum normal→dysplastic BE→EAC: -?CD44H and V6 involved in carcinogenesis of BE mucosa	Lagorce-Pages et al[63]
	↓ CD44 expression in EAC/HG-dysplasia (vs BE/LG-dysplasia)	Darlavoix et al[64]

BE: Barrett’s esophagus; MDC: Metaplasia-dysplasia-carcinoma; EAC: Esophageal adenocarcinoma; EGF: Epidermal growth factor; EGF-R: EGF receptor; pts: Patients; OR: Odds ratio; TGF: Transforming growth factor; HGF: Hepatocyte growth factor; HGF-R: HGF receptor; mRNA: Messenger RNA; FGF: Fibroblast growth factor; HG: High grade; LG: Low grade; LOH: Loss of heterozygosity; APC: Adenomatous polyposis coli; COX-2: Cyclooxygenase-2; VEGF: Vascular endothelial growth factor; VEGF-R: VEGF receptor; CAM: Cell adhesion molecule; GERD: Gastro-esophageal reflux disease.

Table 2 Clinical and demographic risk factors for neoplastic progression of Barrett’s esophagus

Innate factors	Gastrointestinal factors	Other modifiable factors
Age	Bile and acid reflux	Obesity
Gender	Anti-reflux surgery	Diet
Ethnicity	Proton pump inhibition	Alcohol
	Pharmacological lower esophageal sphincter relaxation	Smoking
	Salivary nitrates	Socioeconomic status
	Barrett’s segment length	Pharmacological COX-2 inhibition

COX-2: Cyclooxygenase-2.

Table 3 Selected published evidence linking adipokines (and ghrelin) with Barrett’s esophagus and progression to esophageal adenocarcinoma

Adipokine	Evidence in BE and EAC
	Relevant study findings	Ref.
Adiponectin (↓ in obesity)	↓ adiponectin receptors in Barrett’s mucosa compared with normal mucosa from controls	Konturek et al[110]
	↑ Bax (pro-apoptotic), ↓ Bcl-2 (anti-apoptotic) and ↑ apoptosis of EAC cell lines on incubation with adiponectin	Konturek et al[110]
	Plasma adiponectin levels inversely associated with BE risk in 50 matched cases (OR 4.7 for each 10 μg/mL ↓ in level) (independent of BMI)	Rubenstein et al[111]
	No difference in adiponectin levels between 51 BE patients and 67 controls	Kendall et al[112]
Leptin (↑ in obesity)	Leptin receptors expressed in esophagus	Francois et al[113]
	↑ proliferation and ↓ apoptosis (via various signalling pathways) in EAC cell lines	Ogunwobi et al[114]
	Leptin levels strongly associated with ↑ risk of BE in males (no association in females)	Kendall et al[112]
	Gastric (fundic) leptin levels positively associated with BE (no association with serum leptin)	Francois et al[113]
Ghrelin (↓ in obesity)	↑ gastric emptying (so may ↓ gastric reflux)	Dornonville et al[115]
	↓ TNF-α-induced COX-2 and interleukin-1-β expression in BE cell line	Konturek et al[110]
	Ghrelin expression negligible in archived EAC cell specimens (vs rich expression in normal mucosa)	Mottershead et al[116]
	↑ serum ghrelin associated with ↓ EAC risk (in overweight subjects)	de Martel et al[117]

BE: Barrett’s esophagus; EAC: Esophageal adenocarcinoma; OR: Odds ratio; BMI: Body mass index; COX-2: Cyclooxygenase-2; TNF: Tumor necrosis factor.