Establishment and characterization of HKESC-1, a new cancer cell line from human esophageal squamous cell carcinoma

The establishment of an esophageal cancer cell line can facilitate the search for molecular mechanisms involved in esophageal carcinogenesis. A new human cancer cell line, HKESC-1, was established from a primary moderately-differentiated squamous cell carcinoma of the esophagus from a 47-year-old Hong Kong Chinese man. The pathological characteristics (morphology, immunohistochemical, and electron microscopic studies), the tumorigenecity in nude mice, the cytogenetic features, the DNA ploidy, and telomerase activity of the cell line were investigated. The HKESC-1 cells have been maintained continuously in vitro for more than 16 months and passaged over 96 times. HKESC-1 cells grow as a monolayer, with a doubling time of 46 hours. The HKESC-1 cells are of a squamous epithelial origin, as shown by their immunopositivity with the anti-cytokeratin antibodies and ultrastructural demonstration of tonofilaments and desmosomes. The HKESC-1 cells possess characteristics of malignancy because they are highly tumorigenic in nude mice and have strong telomerase activity. The HKESC-1 cells had an aneuploid DNA content, as demonstrated by flow cytometric analysis. Cytogenetic analysis revealed hyperdiploidy of greater than 50 in 80% of analyzable metaphases. Chromosome gains and losses were common, and loss of the Y chromosome was a consistent numerical aberration. Additionally, many structural chromosomal abnormalities were encountered, with frequent breakpoints at 1p32, 7p22, 7q34, and 20q13. This newly established cell line serves as a useful model for studying the molecular pathogenesis, and testing new therapeutic reagents for esophageal squamous cell carcinoma.     

Establishment and characterization of a new xenograft-derived human esophageal squamous cell carcinoma cell line HKESC-4 of Chinese origin

A new human esophageal cancer cell line, HKESC-4, was established from a nude-mouse xenograft of a moderately differentiated esophageal squamous cell carcinoma (ESCC) developed from a 65-year-old Hong Kong Chinese man. The cellular characteristics (morphological, electron microscopic, and immunohistochemical studies), tumorigenicity in athymic nude mice, cytogenetic features, and DNA ploidy of the cell line were investigated. The cell line was maintained in vitro for 17 months and passaged 80 times. HKESC-4 grew as a monolayer, with a doubling time of 63 hours. The epithelial nature of HKESC-4 included the presence of cytokeratin intermediate filaments, as shown by antibodies (AE1/AF3, CAM5.2, and MAK 6), and the presence of the tonofilaments, as seen under electron microscopy. HKESC-4 was tumorigenic in nude mice and had DNA aneuploidy. The cytogenetic abnormalities of HKESC-4 included -1, -2, -3, -4, -5, -6, -7, -8, -9, -10, -11, -12, -15, -16, -17, -18, -19, +20, -21, -22, +del(11)(p11), +i(11)(q10), and +21 marker chromosomes. Comparative genomic hybridization analysis demonstrated chromosomal gains at 1p36.13, 3q23 approximately q28, 5p15.33 approximately p15.1, 6p25.1 approximately p22.3, 7p21.3 approximately p11.2, 7q11.21 approximately q21.13, 8q23.3 approximately q23.3, 11p11.2, 11q12.1 approximately q13.2, 14q21.3 approximately q32.2, 17p13.3, 18p11.32 approximately p11.31, and 20p13 approximately p12.2 and chromosomal losses at 1q12, 2p25.1 approximately p24.3, 13p13 approximately p11.2, 21p, 22p13 approximately p11.2, and Y. The newly established cell line HKESC-4 promises to be a useful tool in future studies of molecular pathogenesis and therapeutics in ESCC.     

Establishment and characterization of a new xenograft-derived human esophageal squamous cell carcinoma cell line SLMT-1 of Chinese origin

A new human esophageal cancer cell line, named SLMT-1, was established from a nude-mouse xenograft of a well-differentiated esophageal squamous cell carcinoma (ESCC) of the lower esophagus from a male Hong Kong Chinese patient. SLMT-1, passaged over 34 times and with a doubling time of 31 hours, has the microscopic features of epithelial cells with adherent growth as a monolayer. The general biologic properties of SLMT-1 cells were characterized by (1) a positive test of tumorigenicity obtained by injecting cells subcutaneously into athymic nude mice and observing their development into well-differentiated squamous cell carcinoma; (2) immunohistochemical staining using antibodies (AE1/AE3, CAM5.2 and MAK 6) which show the presence of cytokeratin intermediate filaments; and (3) electron microscopy demonstrating the morphologic features of epithelial cells with the presence of desmosomes. The cytogenetic abnormalities found in both the primary culture and SLMT-1 included der(1;14)(q10;q10), add(1)(p1?), +1, +2, del(3)(q11), +6, +7, i(8)(q10), +8, +10, +11, -13, -15, +16, +17, -18, -19, -Y and marker chromosomes. Additional changes observed in the 34th passage included gains as well as losses of both numerical and structural abnormalities. Comparative genomic hybridization (CGH) indicated copy number gains on chromosomal regions 3q32-qter, 5p, 8p12-p11.2, 11q13-q22 and 13q22-qter, and loss of the Y. The gains of 8p12-p11.2 in SLMT-1 cells are novel to ESCC. Based on its distinct and common characteristics, the SLMT-1 cell line serves as a useful tool for studying the molecular and genetic basis of the pathogenesis of ESCC.     

Expression of HLA-G is associated with prognosis in esophageal squamous cell carcinoma

The detection of HLA-G expression might serve as a clinical marker in the diagnosis or prediction of clinical outcomes for certain types of carcinoma. The aim of this study was to determine whether the detection of HLA-G has any important clinical applications for patients with esophageal squamous cell carcinoma (ESCC) by using immunohistochemical methods. We observed that the HLA-G protein was expressed in 90.9% (110/121) of the primary sites of ESCC but not in the normal esophageal tissues. The expression of HLA-G in the tumors was significantly correlated with histologic grade, depth of invasion, nodal status, host immune response, and clinical stage of disease. Patients with positive HLA-G expression had a significantly worse prognosis. In multivariate analysis, HLA-G was an independent prognostic factor. Our results indicate that expression of HLA-G is a characteristic feature of ESCC and suggest that immunostaining by anti-HLA-G antibodies may be a potentially useful prognostic indicator.     

Oncogenic properties of a novel gene JK-1 located in chromosome 5p and its overexpression in human esophageal squamous cell carcinoma

Esophageal squamous cell carcinoma (ESCC) shows high frequency and mortality in Asian regions, including China. Previous analysis of genomic DNA of ESCC using comparative genomic hybridization indicated that amplification of the chromosome 5p regions is a common event in ESCC cell lines and patient cases of Hong Kong Chinese origin, and the results suggested that the genes located in the chromosome 5p regions may play crucial roles in the molecular pathogenesis of ESCC. Our previous studies on ESCC confirmed the tumorigenic and overexpression properties of a novel gene JS-1 located in chromosome 5p15.2 upstream to delta-catenin. In the present study, another novel gene JK-1 which is located at 5p15.1 downstream to delta-catenin was characterized for its roles in the pathogenesis of ESCC. Thirteen ESCC cell lines and 30 surgical specimens of esophageal tumors were studied for the overexpression of JK-1 using multiplex RT-PCR analysis. The transforming capacity of overexpression of JK-1 was also investigated by transfecting NIH 3T3 and HEK 293 cells with the expression vector cloned with JK-1, followed by the soft agar and foci formation assays. JK-1 was overexpressed in 9/13 (69%) of the ESCC cell lines and 9/30 (30%) of the ESCC patient cases. Both NIH 3T3 and HEK 293 cells acquired the properties of anchorage-dependent and -independent growth when JK-1 was overexpressed. Most significantly, subcutaneous sarcomas were formed in all (3/3) the athymic nude mice after NIH 3T3 cells overexpressing JK-1 were injected subcutaneously. Our results thus indicated that JK-1 is commonly overexpressed in ESCC and has a prominent capacity to transform normal cells. Our overall results thus provide the first evidence that the overexpression of JK-1 and its transforming capacity in normal cells may play a critical role in the molecular pathogenesis of ESCC.     

Genetic variation in transforming growth factor-beta1 gene associated with increased risk of esophageal squamous cell carcinoma

The genetic alterations leading to esophageal squamous cell carcinoma (ESCC) are gradually being discovered. A wide variety of genes have been associated with ESCC development as well as tumor progression. Transforming growth factor-beta1 (TGF-beta1) is a multifunctional cytokine; it promotes tumor growth and metastasis in later stages of of cancer development. Variations in the DNA sequence in the TGF-beta1 gene may lead to altered TGF-beta1 production and/or activity, and so this can modulate an individual's susceptibility to ESCC. To test this hypothesis, we investigated the association of the TGF-beta1 gene -509 C/T and 869 T/C (Leu10Pro) polymorphisms and their haplotypes with the risk of ESCC. 247 patients with ESCC and 260 age- and sex-matched controls were studied using a polymerase chain reaction-restriction fragment length polymorphism. There were significant differences in the genotype and allele distribution of 869 T/C polymorphism of the TGF-beta1 gene among cases and controls. The 869 TC and CC genotypes were associated with a significantly increased risk of ESCC as compared with the 869 TT genotypes [odds ratio (OR) = 1.882, 95% confidence interval (CI) 1.212-2.923, P = 0.005 and OR = 2.099, 95% CI 1.288-3.421, P = 0.003, respectively]. Consistent with the results of the genotyping analyses, the -509 T/869 C haplotype was associated with a significantly increased risk of ESCC as compared with the -509 C/869 T haplotype (OR = 1.463; 95% CI 1.120-1.912; P = 0.005). This study shows for the first time that TGF-beta1 gene 869 T/C polymorphism may contribute to a genetic risk factor for ESCC in a Chinese population.     

High endothelial venules associated with better prognosis in esophageal squamous cell carcinoma

BackgroundHigh endothelial venules (HEVs) are specialized microvessels for recruiting naïve T cells and B cells from the circulation into secondary lymphoid organs. Its involvement in esophageal squamous cell carcinoma (ESCC) is still unknown. This study mainly investigated the possible presence of HEVs in ESCC and explore its relationship with prognosis.MethodFormalin fixed paraffin embedded (FFPE) tissue samples of 52 ESCC patients were stained with immunohistochemically (IHC) to assess the association of HEVs with histological and clinical factors by immunohistochemistry. Furthermore, multiplexed immunofluorescence was performed to explore the microenvironment around HEVs.ResultHEVs was widely present in ESCC and was significantly associated with better overall survival (OS). In addition, multiplexed immunofluorescence imaging demonstrated that HEVs is mainly present in the tertiary lymphoid structures (TLS) of the tumor and is surrounded by a large number of lymphocyte cells.ConclusionHEVs represent a better prognostic factor in ESCC.     

PTK7在食管鳞状细胞癌中的表达及临床意义

目的研究酪氨酸蛋白激酶-7（PTK7）在食管鳞状细胞癌、癌旁组织中的表达及其与食管鳞状细胞癌的发展、侵袭、淋巴结转移的关系,分析其在食管鳞癌中的诊断价值及预后变化。方法收集食管鳞状细胞癌标本80例及癌旁组织63例,采用免疫组织化学链霉菌抗生物素蛋白一过氧化物酶连结（SP）法检测PTK7蛋白的表达,结合临床相关因素进行x2检验及Kaplan—meier等统计学分析。结果80例患者食管鳞状细胞癌组织中有45例PTK7蛋白表达阳性（X2=50．17,P〈0．01）,食管癌旁非典型增生及正常鳞状上皮中PTK7蛋白表达均阴性。PTK7表达与食管鳞癌的年龄、性别、分化程度、浸润深度、淋巴结转移、浸润长度、临床分期等比较差异无统计学意义（P〉0．05）;与5年生存率比较差异亦无统计学意义（X2=0．2,P〉0．1）;当肿瘤组织PTK7蛋白表达综合免疫组化评分≥5分时,5年生存率有下降趋势（X2=3．35,P=0．06）。结论PTK7表达与食管鳞癌有关,当PTK7综合免疫评分≥5分时,5年生存率有下降趋势。利用检测PTK7的表达,有助于综合判断食管鳞癌的相关性和临床预后。     

Mutations in the human homologue of the Drosophila patched gene in esophageal squamous cell carcinoma

The human homologue (PTCH) of the Drosophila segment polarity gene patchedhas recently been identified as a tumor-suppressor gene for nevoid basal cell carcinoma syndrome and for sporadic basal cell carcinomas of the skin. We analyzed 30 esophageal squamous cell carcinomas (ESCC) for intrageneic mutations of the PTCH gene by polymerase chain reaction–single-strand conformation polymorphism analysis followed by DNA sequencing. We identified two somatic PTCH mutations (7%) in 30 ESCC. These were a nonsense mutation (CAG to TAG at codon 361) in exon 8 and a missense mutation (CAG to CTG, Gln to Leu at codon 816) in exon 14. These tumors exhibited loss of heterozygosity at the polymorphic site of the PTCH gene. These results indicate that inactivation of the PTCH gene via a two-hit mechanism occurs in a subset of ESCC. Genes Chromosomes Cancer 21:276–279, 1998. © 1998 Wiley-Liss, Inc.     

Ubiquitous p63 expression in human esophageal squamous cell carcinoma

p63, a recently identified member of the p53 gene family, plays an important role in human tissue functions. We examined the pattern of p63 expression in human esophageal squamous cell carcinomas including early-stage cancers, and its clinicopathological significance. Immunoreactivity for p63 was detected in 96.9% (63/65) esophageal squamous cell carcinomas. Diffuse p63 expression was seen in 75.4% (49/65). p63 was detected not only in the in situ carcinomatous components or intramucosal carcinomas, but also in the invasive carcinomatous parts of the p63-positive cases. There were no significant correlations between p63 expression and clinicopathological features, such as depth of tumor invasion, tumor differentiation, lymph node metastasis and venous/lymphatic invasion. We also analyzed the relationship between p63 and p53 expression in esophageal squamous cell carcinomas. These results suggest that the p63 gene, as well as the p53 gene, play a major role in the carcinogenesis of human esophageal squamous cells and in the growth of the carcinoma.     

子宫颈、食管鳞状细胞癌人乳头状瘤病毒感染的比较研究

目的 探讨同一地区人乳头瘤病毒在宫颈鳞状细胞癌的感染特征及与食管鳞状细胞癌的关系.方法 采用PCR技术和快速导流杂交基因芯片技术分别对来自河南同一地区的75例宫颈鳞癌患者和78例食管鳞癌患者进行HPV 分型检测.结果 来自同一地区的宫颈、食管鳞癌组织中,HPV16型阳性检出率均最高,分别为83%(58/70)和82%(49/60),其余阳性类型宫颈鳞癌中依次为HPV58、18、31、6、52、33、11,分别占14%(10/70),9%(6/70),7%(5/70),6%(4/70),6%(4/70),4%(3/70),4%(3/70);食管鳞癌中依次为HPV18、58、31、6、11,分别占15%(9/60),8%(5/60),7%(4/60),5%(3/60),5%(3/60).对HPV16阳性的宫颈、食管鳞癌标本DNA进行HPV16致癌基因E6/E7扩增进行验证,阳性率为100%.结论 同一地区居民宫颈(食管)鳞癌HPV感染亚型相似,提示HPV可能是这两种肿瘤的共同致病因素,HPV16可能在宫颈和食管癌变过程中起重要作用,也为其生物防治提供了重要理论依据.     

Cloning and characterization of a novel intronless lactate dehydrogenase gene in human testis

Using cDNA microarray hybridization from a human testicular cDNA library, one gene named lactate dehydrogenase A-like gene (LDHL, also known as LDHL6B) was cloned. LDHL exhibited 3.8-fold difference at expression level between adult and fetal human testes. The full cDNA length of LDHL is 1680 bp and had a 1145 bp open reading frame, which encoded a 41.9 kDa protein of 381 amino acids. Sequence analysis showed that LDHL harbors all the domains (one lactate/malate dehydrogenase, NAD binding domain and one lactate/malate dehydrogenase, alpha/beta C-terminal domain) in lactate dehydrogenase gene family. Blasting human genome database localized LDHL to human chromosome 15q22.2 and it was an intronless gene. Results of multiple-tissue PCR and real-time PCR showed that LDHL expressed mainly in testis and its mRNA abundance was testis development-related. In summary, LDHL is believed to be involved in testis development and spermatogenesis.     

Genome-wide association study identifies novel alleles associated with risk of cutaneous basal cell carcinoma and squamous cell carcinoma

We conducted a genome-wide association study on cutaneous basal cell carcinoma (BCC) among 2045 cases and 6013 controls of European ancestry, with follow-up replication in 1426 cases and 4845 controls. A non-synonymous SNP in the MC1R gene (rs1805007 encoding Arg151Cys substitution), a previously well-documented pigmentation gene, showed the strongest association with BCC risk in the discovery set (rs1805007[T]: OR (95% CI) for combined discovery set and replication set [1.55 (1.45-1.66); P= 4.3 × 10(-17)]. We identified that an SNP rs12210050 at 6p25 near the EXOC2 gene was associated with an increased risk of BCC [rs12210050[T]: combined OR (95% CI), 1.24 (1.17-1.31); P= 9.9 × 10(-10)]. In the locus on 13q32 near the UBAC2 gene encoding ubiquitin-associated domain-containing protein 2, we also identified a variant conferring susceptibility to BCC [rs7335046 [G]; combined OR (95% CI), 1.26 (1.18-1.34); P= 2.9 × 10(-8)]. We further evaluated the associations of these two novel SNPs (rs12210050 and rs7335046) with squamous cell carcinoma (SCC) risk as well as melanoma risk. We found that both variants, rs12210050[T] [OR (95% CI), 1.35 (1.16-1.57); P= 7.6 × 10(-5)] and rs7335046 [G] [OR (95% CI), 1.21 (1.02-1.44); P= 0.03], were associated with an increased risk of SCC. These two variants were not associated with melanoma risk. We conclude that 6p25 and 13q32 are novel loci conferring susceptibility to non-melanoma skin cancer.     

Expression of Akt and Mdm2 in human esophageal squamous cell carcinoma

The Akt-Mdm2 pathway plays an important role in carcinogenesis in a variety of malignant tumors. However, the Akt-Mdm2 pathway in esophageal squamous cell carcinoma (ESCC) has not been fully studied. We investigated the proteins and mRNA expression of Akt and Mdm2 to elucidate the roles of these proteins in ESCC. We also examined the effect of Akt knockdown on Mdm2 expression in ESCC cells. ESCC tissue samples were obtained from 23 individuals who underwent surgical resection with no preoperative treatment. Akt1-3 and Mdm2 gene and protein expression were analyzed. The effect of siRNA-mediated Akt knockdown on Mdm2 expression was also studied, using ESCC cell lines. Akt1 and Mdm2 immunoreactivity was detected in 77.8 and 66.7% of tumor specimen from ESCC patients, respectively. Akt1 and Mdm2 mRNA expressions were correlated and significantly elevated in tumor tissue (p < 0.0001 and p < 0.05, respectively). The siRNA-targeted reduction of each Akt isoform reduced Mdm2 protein expression. The overexpression of Akt1 and Mdm2 may be related to esophageal carcinogenesis. Furthermore, Akt expression regulates Mdm2 expression, which may in turn regulate the function of wild-type p53. These results may provide the basis for future preventative or clinical therapies for esophageal cancer.     

Human leukocyte antigen G is associated with esophageal squamous cell carcinoma progression and poor prognosis

Human leukocyte antigen G (HLA-G) is a non-classical HLA class I molecule thought to play a key role in maternal-fetal tolerance and cancer immune evasion. This study aimed to investigate the HLA-G expression in lesion sections and plasma sHLA-G levels of primary esophageal squamous cell carcinoma (ESCC) patients and its clinical significance in diagnosis and prognosis of ESCC. 60 ESCC patients and 28 healthy controls were recruited, and the positive expression of HLA-G in ESCC lesions and adjacent normal tissues were 70% (42/60) and 8.6% (5/60) (P < 0.05), respectively, while no expression was found in normal controls. HLA-G1 and HLA-G5 were determined to be dominating isoforms measured by RT-PCR. There was a significant difference in plasma sHLA-G levels between patients with ESCC (15.04 U/ml, range 4.33–250.00 U/ml) and healthy controls (6.81 U/ml, range 0–29.27 U/ml) (P < 0.01). The plasma IL-10 level was higher in ESCC patients than the controls (23.86 pg/ml vs. 12.81 pg/ml, P < 0.01). HLA-G expression in lesion tissues was correlated with cancer cell differentiation (P = 0.033), lymph node metastasis (P = 0.035) of ESCC. However, no obvious correlations were demonstrated between the plasma sHLA-G levels and the clinicopathological parameters. There was a significant correlation between sHLA-G and IL-10 expression (r = 0.353, P = 0.006) in patients with Esophageal squamous cell carcinoma. HLA-G positive expression showed poorer prognosis of ESCC. HLA-G positive expression might serve as a potential marker in the diagnosis or prediction of ESCC.     

食管鳞状细胞癌中p16基因甲基化及其表达

目的：探讨食管鳞状细胞癌p16／INK4基因启动子区高甲基化和p16、cyclinD1蛋白表达的意义。方法：用甲基化特异性PCR（MSP）法检测p16／INK4基因启动子区的高甲基化，用免疫组织化学方法检测p16、cyclind1蛋白的表达。结果：30例食管鳞状细胞癌中7例p16免疫组织化学阳性，15例cyclinD1阳性，组织学和统计学分析显示p16与cyclinD1的表达呈负相关。4例检出p16／INK4基因启动子区高甲基化，但与p16失表达无统计学意义。结论：（1）在食管鳞状细胞癌可检出p16／INK4基因启动子区的高甲基化，而甲基化不是引起p16失表达的主要原因。（2）p16与cyclinD1的表达呈负相关，提示细胞周期调控因子之间可能存在相互影响表达的反馈机制。     

FEZ1基因在食管癌变过程中的作用

目的探讨FEZ1基因在食管鳞状细胞癌(esophageal squamous cell carcinoma,ESCC)组织中的表达及其与患者预后的关系。方法采用Western blot和免疫组化法分析FEZ1基因在ESCC中的表达情况,应用SPSS 13.0软件分析其与临床病理资料及预后的关系。结果 FEZ1蛋白阳性表达在食管癌中的表达与浸润深度、肿瘤大小相关(P<0.05);而与肿瘤组织分化程度、淋巴结转移无关(P>0.05)。正常食管组织中FEZ1的蛋白表达(4.3±0.39)明显高于食管癌组织中(1.6±0.25),且差异有显著性(P<0.05)。FEZ1的高表达提示患者的5年生存率高。结论 FEZ1基因在食管癌的发生、发展过程中起着重要的作用;FEZ1基因在食管癌中可能是候选的抑癌基因。     

Elevated expression of MDR1 associated with Line-1 hypomethylation in esophageal squamous cell carcinoma

Background: The aim is to discuss the relationship of Line-1 methylation and the MDR1 expression in esophageal squamous cell carcinoma (ESCC). Methods: We analyzed the methylation level of Line-1 by quantitative real-time MSP, and the expression of MDR1 by real-time RT-PCR in 310 ESCC and corresponding non-tumor tissues. Results: We found that the methylation index (MI) of Line-1 decreased from 0.90 in non-tumor tissues toward 0.78 in ESCC. The cumulative survival was significantly shorter in ESCC patients with MI ≤ 0.78 (34 months) than that in patients with MI > 0.78 (43 months). There was a statistical difference between MI ≤ 0.78 and MI > 0.78 cases with these clinicopathologic parameters (age, AJCC stage, differentiation; P = 0.010, P < 0.0001, P = 0.015, respectively). These results implied that Line-1 hypomethylation could be more in ESCC patients with older, advanced tumor and poor differentiation group. Meanwhile, ESCC with demethylation of Line-1 were shown elevated MDR1 expression in tumor (Mean_-∆∆Ct = 0.21), but ESCC with hypermethylation of Line-1 were considered to be decreased MDR1 expression in tumor (Mean_-∆∆Ct = -0.86). Conclusions: Line-1 hypomethylation could be as a biomarker of poor prognosis in ESCC patients. MDR1 gene could be activated via epigenetic mechanisms with demethylation of Line-1 in ESCC, and enhance tumor progression.     

Expression and clinical significance of B cell translocation gene 2 in esophageal squamous cell carcinoma

Esophageal squamous cell carcinoma (ESCC) is widely known as a highly fatal cancer, and thus it is important to identify tumor-specific and radiosensitivity-specific markers in ESCC. B cell translocation gene 2 (BTG2) has been considered a novel tumor suppressor gene or radiotherapy sensitivity-associated gene. However, the relationship between BTG2 and ESCC development and radiotherapy sensitivity is uncertain. The present study aims to explore the expression and clinical significance of B cell translocation gene 2 (BTG2) in ESCC by analyzing the RNAseq data from the TCGA and immunohistochemical staining of ESCC samples. We found that the level of BTG2 mRNA was significantly decreased in ESCC patients, and further decreased significantly in radiotherapy resistant patients compared to sensitive patients. The positive expression rate of BTG2 protein was 56.0% (103/184) in 184 ESCC tissue samples and 84.0% (42/50) in normal esophageal mucosal samples, respectively. The positive ratios of BTG2 expression in radiotherapy-sensitive group and radiotherapy resistant group were 57.9% (22/38) and 23.5% (4/17), respectively. Furthermore, the analysis indicates that the expression level of BTG2 significantly correlated with lymph node metastasis and clinical staging in ESCC patients. A multivariate analysis with Cox regression model showed that BTG2 level was an independent risk factor affecting the prognosis of ESCC patients. Above all, the downregulation of BTG2 may be used as a molecular marker to identify and predict ESCC progression and radiosensitivity.