Northwestern China: a place to learn more on oesophageal cancer. Part one: behavioural and environmental risk factors

Oesophageal squamous cell carcinoma (OSCC) remains a public health problem in many countries, especially in emerging and developing countries. Epidemiology of OSCC is characterized by marked differences in prevalence between countries/regions/ethnical groups. The highest incidence in the world is reached by populations living in specific areas of northwestern Xinjiang, China where age-adjusted mortality may reach 150 of 100 000. In fact, there are also marked differences among the various geographical areas and the various ethnic groups within the region, which suggests specific risk factors. Behavioural factors include those factors which are common to all 'high-risk populations', such as tobacco smoking and alcohol drinking. However, the very unusual sex ratio (1.2 : 1.0) and young age range of OSCC occurrence suggests the involvement of additional early risk factors shared by males and females, and which are different from those studied in other 'high-risk' areas of the world, including China, such as LinXian area. These include drinking very hot and salted tea, boiled with milk; a diet rich in meat, especially salted, dry and/or smoked meat, and dairy products; and a diet poor in fresh fruit and vegetables. The combination of hot drinks (such as milk, tea and soups) and high-degree spirit drinks, and hard food (bread, meat and cheese), together with poor oral hygiene and tooth loss, is likely to add mechanical injury of the oesophagus to other factors linked to climate characteristics of the area (drought) and dietary habits, which promote a sodium and nitrosamine-rich diet. Association of early and severe hypertension in the same populations at high risk of OSCC might likely raise more attention. Human papilloma virus (HPV) infection, and especially HPV 16/18 E6/E7, with gene mutations and association with p53 overexpression, may contribute to the extremely high incidence of OSCC observed in Xinjiang, and could be accessible to prevention. Infection may especially be a crucial additional factor in the Uygur population in which not only HPV infection but also infection with other oncogenic viruses, such as HHV8, are highly prevalent. Genetic polymorphism might interact with viruses and/or viral products to promote carcinogenesis. These observations in northwestern China suggest that usually neglected factors, such as sodium excess and viral infection, could be taken into more account when studying OSCC risk factors in other parts of the world, especially Europe.

Role of microRNA let-7 and effect to HMGA2 in esophageal squamous cell carcinoma

To investigated the role of microRNA (miRNA) let-7 and its regulation on high mobility group A2 (HMGA2) protein expression in esophageal squamous cell carcinoma (ESCC). Let-7 expressions were detected in esophageal cancer cell line Eca109, and 45 paired of fresh ESCC and normal adjacent tissues (NAT) by real-time quantitative PCR (qRT-PCR). To evaluate the role of let-7 and HMGA2, cell proliferations were analyzed with synthetic let-7 mimics- or its inhibitor-transfected cells. Moreover, expressions of HMGA2 were performed by western blotting and further confirmed by 150 paired of formalin-fixed, paraffin-embeded (FFPE) ESCC and NAT by immunohistochemistry (IHC). In Eca109, when transfected with let-7 mimics, accumulation of let-7 was obviously suppressed cell proliferation with approximately 14%. Conversely, when Eca109 transfected with let-7 inhibitor, expression of let-7 was declined, which promoted cell proliferation with approximately 16%. Both of them had no effect on the level of HMGA2 mRNA. The transcription of let-7 inversely correlated with HMGA2 protein. Compared with the NAT, expression of let-7 was significantly lower in ESCC tissues (P < 0.05), and there was a significant correlation between low expression of let-7 and lymph node metastasis in ESCC (P < 0.05). Moreover, the protein expression of HMGA2 was significantly higher in ESCC compared with NAT (P < 0.05). However, mRNA expression of HMGA2 had no obvious significance between them. The present results demonstrated that let-7 and HMGA2 involved in ESCC carcinogenesis. Let-7 could inhibit cell proliferation and lower expressed in ESCC, and there was a correlation between let-7 lower expression and lymph node metastasis in ESCC patients. As well as, HMGA2 protein expression was significantly higher in ESCC than that in NAT, and HMGA2 may negatively regulated by let-7 at the post- transcriptional level in ESCC.

Role of microRNA-21 and effect on PTEN in Kazakh's esophageal squamous cell carcinoma

The aim of this study was investigate the role of microRNA-21 (miR-21) and its regulation on phosphatase and tensin homolog deleted from chromosome-10 (PTEN) in Kazakh's esophageal squamous cell carcinoma (ESCC). MiR-21 expressions were investigated in esophageal cancer cell line Eca109, and 18 pairs of Kazakh's ESCC and adjacent normal tissues by real-time quantitative PCR (qRT-PCR). To evaluate the role of miR-21 and PTEN, cell proliferations were analyzed with miR-21 mimics or their inhibitor-transfected cells. Moreover, the expressions of PTEN were performed by Western blotting. In Eca109, when transfected with miR-21 mimics, accumulation of miR-21 was obviously increased and expression of PTEN protein was decreased to be approximately 40%, which resulted in the promotion of cell proliferation. However, when transfected with miR-21 inhibitor, expression of miR-21 was declined and PTEN protein was overexpressed to be approximately 79%, which resulted in the suppression of cell proliferation. Both of them had no effect on the level of PTEN mRNA. Compared with adjacent normal tissues, miR-21 expression was significantly higher in tumor (P < 0.05). Specifically, patients with cancer cell invasion deep into esophageal serosa showed significantly higher expression of miR-21. Protein expression of PTEN was significantly lower in tumor compared with normal tissues (P < 0.05); however, mRNA expression of PTEN had no obvious significance between them. Furthermore, there was a significantly inverse correlation between miR-21 expression and PTEN protein levels (p < 0.05). The author concluded that MiR-21 was overexpressed in vitro and ESCC, and promoted the cell proliferation, might target PTEN at post-transcriptional level, and regulated the cancer invasion in Kazakh's ESCC.

Shikonin Inhibits Tumor Growth of ESCC by suppressing PKM2 mediated Aerobic Glycolysis and STAT3 Phosphorylation

Background: Shikonin, a small molecule inhibitor of pyruvate kinase 2 (PKM2), has been demonstrated to play the antitumor effect in various cancers. However, the specific effects and related regulatory mechanism of Shikonin in esophageal squamous cell carcinoma (ESCC) have not been clearly declared. Materials and methods: Cell viability was valued through 3-(4,5-Dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay. Glucose consumption, lactate production, glycolytic intermediates and pyruvate kinase enzymatic activity were measured using corresponding assay kits. Patient-derived xenograft (PDX) models were constructed to observe the anti-ESCC effect of Shikonin in vivo. PKM2, p-PKM2, signal transducer and activator of transcription 3 (STAT3), p-STAT3, glucose transporter 1 (GLUT1) and hexokinase 2 (HK2) in ESCC tissues were assessed by western blot. The expression of PKM2, p-PKM2, p-STAT3, GLUT1 and HK2 was assessed by immunohistochemistry (IHC) in ESCC tissue based on PDXs. Results: Shikonin effectively inhibited cell proliferation in dose-dependent and time-dependent manner compared with the control group. The detection of glycolysis showed that Shikonin suppressed the glucose consumption, lactate production, glycolytic intermediates and pyruvate kinase enzymatic activity. Furthermore, Shikonin not only inhibited the growth of ESCC, but also decreased the expression of p-PKM2 and p-STAT3 in vivo. Finally, Shikonin suppressed the expression of GLUT1 and HK2 proteins which are related to glycolysis. Conclusion: Shikonin has a significant antitumor effect in the ESCC by suppressing PKM2 mediated aerobic glycolysis and regulating PKM2/STAT3 signal pathway.

MicroRNA-21 promotes the proliferation and inhibits apoptosis in Eca109 via activating ERK1/2/MAPK pathway

The aim of this study was to investigate how miR-21 promotes proliferation and inhibits apoptosis in esophageal squamous cell carcinoma (ESCC). MTT, wound healing assay and cell cycle showed that proliferation and migration of ESCC cell line Eca109 cells were increased in miR-21 mimics group, and decreased in anti-miR-21 Oligonucleotide (AMO) group after transfection into Eca109 cells with miR-21 mimics, AMO and scramble sequence, respectively. Cell apoptosis assay indicated that cell apoptosis can be obviously inhibited by overexpression of miR-21 and promoted by downregulation of miR-21. Meanwhile, western-blot results showed that p-ERK1/2 expression was elevated in miR-21 mimics group, whereas decreased in AMO group. Furthermore, the ERK1/2, a key component of MAPK signaling pathway, was knocked down, and overexpressed successfully using shRNA-ERK1/2 and overexpressing plasmids containing full length cDNA of ERK1/2, respectively. It was observed that shRNA-ERK1/2 can significantly decreased the level of miR-21 expression, while overexpression of ERK1/2 can up-regulate expression of miR-21. As further confirmation, Eca109 cells were treated with gradient concentration of U0126, a kind of MEK inhibitor, and expression of miR-21 was subsequently examined. It was found that U0126 can significantly decreased endogenous expression of miR-21. In parallel, U0126 decreased cell proliferation, migration and increased the apoptosis in Eca109 cells, with the expression of miR-21 being reduced significantly in U0126 group as compared with control groups. Our findings indicated that miR-21 promoted the proliferation, migration and inhibited apoptosis of Eca109 cells through activating ERK1/2/MAPK pathway, and that targeting miR-21 could be a promising therapeutic strategy in ESCC.

HMGA2 is down-regulated by microRNA let-7 and associated with epithelial-mesenchymal transition in oesophageal squamous cell carcinomas of Kazakhs

AIMS

To investigate the expression of let-7 and its regulation of high-mobility group A2 protein (HMGA2), and to verify the relationship between let-7, HMGA2 and the process of epithelial-mesenchymal transition (EMT), in oesophageal squamous cell carcinomas (OSCC) of Kazakh patients.

METHODS AND RESULTS

Expression of let-7 was significantly lower in Eca109 cells than in normal oesophageal squamous epithelium (P = 2.4 × 10(-7) ). Increased accumulation of let-7 after transfection of Eca109 cells with synthetic let-7 inhibited cell proliferation. Let-7 could repress expression of HMGA2 after co-transfection with let-7 and HMGA2 (P = 0.002). Moreover, let-7 expression was observed less frequently (P = 2.0 × 10(-8) ), and HMGA2 expression more frequently (P = 1.0 × 10(-10) ), in OSCC than in normal adjacent tissues; and let-7 expression was observed less frequently in OSCC from Kazakh patients than in those from Han and Uygur patients (P = 0.041). There was a reverse correlation between expression of let-7 and HMGA2 (P = 0.018). Expression of Snail was statistically higher in Kazakhs' OSCC (P = 0.029), and was correlated with depth of invasion (P = 0.021) and HMGA2 expression (P = 0.026).

CONCLUSIONS

Expression of let-7 can suppress cell proliferation by acting directly on regulation of HMGA2 in OSCC. High expression of Snail and its correlation with HMGA2 expression and tumour invasion suggest that HMGA2 may be involved in EMT in the OSCC of Kazakh patients.

Proteomic identification of differentially-expressed proteins in esophageal cancer in three ethnic groups in Xinjiang

The Objective is to identify candidate biomarkers for Squamous cell carcinoma (ESCC) in three ethnics in Xinjiang as well as reveal molecular mechanism. Proteins from 15 pairs of ESCC and matching adjacent normal esophageal tissues (five pairs in each ethnic of Kazakh, Uygur and Han) were separated by 2-DE and differentially proteins were identified by matrix-assisted laser desorption/ionization time-of-flight MS. After identified by Mascot database, some of interesting proteins were confirmed in the other 175 pairs of ESCC by immuno histochemistry. Comparison of patterns revealed 20 proteins significantly changed, of which 12 protein with concordantly increased, such as ACTB protein, COMT protein, Syntaxin binding protein Pyruvate Kinase (PKM2), Cathepsin D, Chromosome 1 open reading frame 8, Heat shock protein 27, Cdc42, Proteosome, LLDBP, Immunoglobulin, TNF receptor associated factor 7; and eight protein spots with concordantly decreased intensity in ESCC, such as Adenylate kinase 1, General transcription factor II H, Smooth muscle protein, Trangelin, Early endosome antigen 1, Annexin A2, Fibrin beta, Tropomyosin. There were a significant difference in protein overexpression of PKM2 (74.9%) and Cathepsin D (85.1%) in ESCC compared to adjacent tissues (P < 0.05) by immunohistochemistry. Further, overexpression of Cathepsin D was obvious difference in Hazakh ESCC (94.7%) than that in Uygur (78.6%) (P < 0.05). Interestingly, the overexpression of Cathepsin D was reversely associated with ESCC differentiation (P < 0.05). Twenty proteins differentially-expressed between ESCC and normal tissues were identified. Cathepsin D and PKM2 were for the first time observed to be dysregulated in Kazakh's ESCC. Moreover, Cathepsin D may play a complicated role both in carcinogenesis and cell-differentiation of ESCC.

MCP2 activates NF-κB signaling pathway promoting the migration and invasion of ESCC cells

MCP2, aliased CCL8, has been suggested to be implicated in the metastasis of cancer cells; however, no direct evidence has been established in esophageal squamous cell carcinoma (ESCC). In our present study, to investigate the role MCP2 played in the metastasis of ESCC cells; in vitro cell co-culture system was established. Wound-healing and Transwell assays were used to evaluate the migratory and invasive variation of ESCC cells before and after treatment with recombinant human MCP2. It was shown that MCP2 was able to activate the NF-κB signaling pathway inducing the epithelial-mesenchymal transition (EMT) and promoting the migration and invasion of ESCC cells in vitro. Our study provides an alternative working mechanism for M2 macrophage mediated the metastasis in tumor microenvironment in ESCC.

IL-1β from M2 macrophages promotes migration and invasion of ESCC cells enhancing epithelial-mesenchymal transition and activating NF-κB signaling pathway

Despite the phenotype has been established that M2 macrophages promotes the metastasis of ESCC, question still remains as to how the M2 macrophages facilitated metastasis of ESCC cells. To begin with, immunohistochemistry was performed to detect the expression of CD163, one typical surface marker of M2 macrophages in 90 paired ESCC and its normal controls after meta-analyzing the relevant studies regarding M2 macrophages in ESCC, confirming that infiltration of M2 macrophages was significantly linked with lymph node metastasis, T classification, and inferior overall survival of ESCC. To explore the mechanism behind, protein factors secreted by M2 macrophages were identified using antibody microarray. Six different significantly differential protein factors were screened out, including IL-1β, TIMP1, IL-1α, MDC, TGF-β1, and TGF-β2. Among which, IL-1β was picked up as cytokine as interest based on previous reports and its absolute fold. Functional analysis of IL-1β showed that IL-1β was able to promote migration and invasion of ESCC cells, enhancing epithelial-mesenchymal transition, and activating NF-κB pathway. Our study supports the promoting role of M2 macrophages in metastasis of ESCC cells, enriching the profile of protein factors released from M2 macrophages.

Long non-coding RNA LINC00858 exerts a tumor-promoting role in colon cancer via HNF4α and WNK2 regulation

BACKGROUND

Long non-coding RNAs (lncRNAs) are known to be frequently dysregulated in many types of human cancer. As yet, however, their roles in colon carcinogenesis have not been fully elucidated. In the current study, we assessed whether lncRNA LINC00858 may be involved in the progression of colon cancer and, in addition, investigated its downstream targets.

METHODS

LINC00858 expression in patient-derived colon cancer tissues and in colon cancer cell lines was determined using RT-qPCR. Also, relationships between LINC00858 expression and various clinicopathological characteristics were analyzed. The subcellular localization of LINC00858 was determined using fluorescence in situ hybridization. Interactions between LINC00858 and its downstream targets were first predicted by bioinformatic analysis and, subsequently, confirmed by RNA pull-down, RNA immunoprecipitation, chromatin immunoprecipitation and dual luciferase reporter assays. After in vitro upregulation of LINC00858 and/or silencing of WNK2 and hepatocyte nuclear factor 4α (HNF4α), the biological behavior of colon cancer cells was assessed using 5-ethynyl-2'-deoxyuridine (EdU) incorporation, Transwell invasion and tube formation assays. In vivo cancer growth was evaluated in nude mice.

RESULTS

We found that LINC00858 was highly expressed in primary colon cancer tissues and colon cancer cell lines, and was mainly located in the nucleus. High LINC00858 expression was found to correlate with a poor differentiation, advanced TNM stages and lymph node metastasis. Exogenous overexpression of LINC00858 promoted cell proliferation, invasion and migration of colon cancer cells, and facilitated angiogenesis and tumor growth. In addition, we found that LINC00858 can bind to and upregulate the nuclear transcription factor HNF4α, leading to WNK2 expression downregulation. This, in turn, resulted in the promotion of colon cancer cell growth.

CONCLUSIONS

From our data we conclude that LINC00858 acts as a tumor-promoting lncRNA in colon cancer by upregulating HNF4α and downregulating WNK2. Our results may provide novel targets for the treatment for colon cancer.

PKM2-regulated STAT3 promotes esophageal squamous cell carcinoma progression via TGF-β1-induced EMT

Recent studies have demonstrated pleiotropic roles of pyruvate kinase isoenzyme type M2 (PKM2) in tumor progression. However, the precise mechanisms underlying the effects of PKM2 on esophageal squamous cell carcinoma (ESCC) metastasis and transforming growth factor β1 (TGF-β1)-induced epithelial-mesenchymal transition (EMT) remain to be established. In this study, we observed upregulation of PKM2 in ESCC tissues that was markedly associated with lymph node metastasis and poor prognosis. High PKM2 expression in tumor tissues frequently coincided with the high pSTAT3Tyr705 expression and low E-cadherin expression. Furthermore, altered PKM2 expression was significantly associated with proliferation, migration, and invasion of ESCC cells, in addition to expression patterns of EMT markers (Snail, E-cadherin, and vimentin) and pSTAT3Tyr705 /STAT3 ratio. Overexpression of STAT3 significantly attenuated the effects of PKM2 knockdown on cell proliferation and motility as well as expression of pSTAT3 Tyr705 and EMT markers. Consistently, stable short hairpin RNA (shRNA)-mediated silencing of PKM2 reversed the effects of TGF-β1 treatment, specifically, upregulation of PKM2, phosphorylation of STAT3 at Tyr705, and increased EMT, migration, and invasion. We propose that PKM2 regulates cell proliferation, migration, and invasion via phosphorylation of STAT3 through TGF-β1-induced EMT. Our findings collectively provide mechanistic insights into the tumor-promoting role of PKM2, supporting its prognostic value and the therapeutic utility of PKM2 inhibitors as potential antitumor agents in ESCC.

Down-regulated miR-26a promotes proliferation, migration, and invasion via negative regulation of MTDH in esophageal squamous cell carcinoma

Numerous studies have reported that the role played by miR-26a in cancer is controversial, but whether miR-26a regulates metadherin (MTDH) expression in esophageal squamous cell carcinoma (ESCC) is unclear. We performed this study to investigate the clinical relevance of miR-26a expression in ESCC. miR-26a was detected by using the in situ hybridization method. To functionally analyze the role of miR-26a in ESCC cell lines in vitro, KYSE-450 and Eca109 cells were employed, whose endogenous miR-26a was artificially down- or up-regulated, respectively, by using lentiviral-based transfection. There was significant association between miR-26a expression and clinical stage (P = 0.049), lymph node metastasis (P = 0.023), tumor volume (P = 0.003), and poor overall prognosis (P = 0.026). miR-26a was able to suppress proliferation and migration of ESCC cells in vitro Moreover, we have confirmed that miR-26a can negatively regulate MTDH in ESCC cells by using luciferase reporter assay. In addition, to investigate the role miR-26a plays in cell proliferation, we nude mice were xenografted with ESCC cells whose miR-26a was stably down- and up-regulated. Together, our results show that miR-26a is capable of suppressing the proliferation and migration of ESCC cells via negative regulation of MTDH. Moreover, miR-26a expression was clinically relevant in cancer progression and poor prognosis, which supports the idea that miR-26a acts as a tumor suppressor in ESCC.-Yang, C., Zheng, S., Liu, T., Liu, Q., Dai, F., Zhou, J., Chen, Y., Sheyhidin, I., Lu, X. Down-regulated miR-26a promotes proliferation, migration, and invasion via negative regulation of MTDH in esophageal squamous cell carcinoma.

DNA polymorphism and risk of esophageal squamous cell carcinoma in a population of North Xinjiang, China

AIM

To investigate the role of metabolic enzyme and DNA repair genes in susceptibility of esophageal squamous cell carcinoma (ESCC).

METHODS

A case-control study was designed with 454 samples from 128 ESCC patients and 326 gender, age and ethnicity-matched control subjects. Genotypes of 69 single nucleotide polymorphisms (SNPs) of metabolic enzyme (aldehyde dehydrogenase-2, ALDH2; alcohol dehydrogenase-1 B, ADHB1; Cytochrome P450 2A6, CYP2A6) and DNA repair capacity genes (excision repair cross complementing group 1, ERCC1; O(6)-methylguanine DNA methyltransferase, MGMT; xeroderma pigmentosum group A, XPA; xeroderma pigmentosum group A, XPD) were determined by the Sequenom MassARRAY system, and results were analyzed using unconditional logistic regression adjusted for age, gender.

RESULTS

There was no association between the variation in the ERCC1, XPA, ADHB1 genes and ESCC risk. Increased risk of ESCC was suggested in ALDH2 for frequency of presence C allele of SNP [Rs886205: 1.626 (1.158-2.284)], XPD for C allele [Rs50872: 1.482 (1.058-2.074)], and MGMT for A allele [Rs11016897: 1.666 (1.245-2.228)]. Five variants of MGMT were associated with a protective effect on ESCC carcinogenesis, including C allele [Rs7069143: 0.698 (0.518-0.939)], C allele [Rs3793909: 0.653 (0.429-0.995)], A allele [Rs12771882: 0.719 (0.524-0.986)], C allele [Rs551491: 0.707 (0.529-0.945)], and A allele [Rs7071825: 0.618 (0.506-0.910)]. At the genotype level, increased risk of ESCC carcinogenesis was found in homozygous carriers of the ALDH2 Rs886205 [CC vs TT, odds ratios (OR): 3.116, 95% CI: 1.179-8.234], MGMT Rs11016879 (AA vs GG, OR: 3.112, 95% CI: 1.565-6.181), Rs12771882 (AA vs GG, OR: 2.442, 95% CI: 1.204-4.595), and heterozygotes carriers of the ALDH2 Rs886205 (CT vs TT, OR: 3.930, 95% CI: 1.470-10.504), MGMT Rs11016879 (AG vs GG, OR: 3.933, 95% CI: 2.216-6.982) and Rs7075748 (CT vs CC, OR: 1.949, 95% CI: 1.134-3.350), respectively. Three variants were associated with a protective effect on ESCC carcinogenesis, carriers of the MGMT Rs11016878 (AG vs AA, OR: 0.388, 95% CI: 0.180-0.836), Rs7069143(CT vs CC, OR: 0.478, 95% CI: 0.303-0.754) and Rs7071825 (GG vs AA, OR: 0.493, 95% CI: 0.266-0.915). Increased risk of ESCC metastasis was indicated in MGMT for frequency of presence C allele [Rs7068306: 2.204 (1.244-3.906)], A allele [Rs10734088: 1.968 (1.111-3.484)] and C allele [Rs4751115: 2.178 (1.251-3.791)]. Two variants in frequency of presence C allele of CYP2A6 [Rs8192720: 0.290 (0.099-0.855)] and A allele of MGMT [Rs2053139: 0.511 (0.289-0.903)] were associated with a protective effect on ESCC progression. Increased risk of ESCC metastasis was found in heterozygote carriers of the MGMT Rs7068306 (CG vs CC, OR: 4.706, 95% CI: 1.872-11.833).

CONCLUSION

Polymorphic variation in ALDH2, XPD and MGMT genes may be of importance for ESCC susceptibility. Polymorphic variation in CYP2A6 and MGMT are associated with ESCC metastasis.

CXCL6 fuels the growth and metastases of esophageal squamous cell carcinoma cells both in vitro and in vivo through upregulation of PD-L1 via activation of STAT3 pathway

CXCL6, contraction of C-X-C motif chemokine ligand 6, whose biological roles have been rarely described in esophageal squamous cell carcinoma (ESCC). To understand the clinicopathological and biological roles played by CXCL6 in the growth and metastasis of ESCC, immunohistochemistry was used to detect the expression of CXCL6 in ESCC tissues, totaling 105 cases; and the correlation was statistically analyzed between CXCL6 expression and clinicopathological parameters. The role mediated in migration and invasion was evaluated using wound-healing and Transwell assays. MTT and flow cytometry were used to assay the proliferative variation. In vivo, tail vein injection model was established in nude mice xenografted with human ESCC cell lines whose CXCL6 were artificially manipulated. It was found that relative to normal control, CXCL6 was profoundly higher in ESCC; upregulated CXCL6 only significantly correlated with differentiation degree. In vitro, CXCL6 was found to promote the proliferation, migration, and invasion of ESCC cells; which was fully corroborated by nude mice experiment that CXCL6 can promote the growth and metastases of ESCC cells in vivo. Mechanistically, CXCL6 was discovered to be capable of promoting epithelial-mesenchymal transition and upregulating PD-L1 expression through activation of the STAT3 pathway. Collectively, all the data we showed here demonstrate that CXCL6 can enhance the growth and metastases of ESCC cells both in vivo and in vitro.

Clinicopathological pattern and Annexin A2 and Cdc42 status in patients presenting with differentiation and lymphnode metastasis of esophageal squamous cell carcinomas

Annexin A2 and Cdc42 were identified by 2-dimensional electrophoresis (2-DE) and MALDI-TOF-MS between esophageal squamous cell carcinomas (ESCC) and corresponding normal esophagus mucosa in our previous study. To assess clinico-pathological pattern and Annexin A2 and Cdc42 status with respect to cell differentiation and lymphnode metastasis in patients with ESCC. The expression of Annexin A2 and Cdc42 in 22 pairs of fresh ESCC and matched tissues were detected by qRT-PCR and western blot, respectively. And it was further confirmed by immunohistochemistry with 175 pairs of formalin-fixed, paraffin-embedded ESCC. Results showed that Annexin A2 expression was significantly down-regulated, and Cdc42 was up-regulated in ESCC compared to matched control on both mRNA and protein level (P < 0.05), which was in accordance with our previous results on proteomics data. Additionally, Annexin A2 and Cdc42 expression was significantly correlated with lymphoid node metastasis (P < 0.05) and pathological differentiation (P < 0.05). Taken together, we proposed that the aberrant expression of Annexin A2 and Cdc42 played a role in carcinogenesis, differentiation and metastasis of ESCC, which implied its potential target for clinical biomarkers in differentiation and lymph node metastasis.

Posttranslational modification of pyruvate kinase type M2 (PKM2): novel regulation of its biological roles to be further discovered

PKM2, pyruvate kinase type M2, has been shown to play a key role in aerobic glycolysis and to regulate the malignant behaviors of cancer cells. Recently, PKM2 has been revealed to hold dual metabolic and nonmetabolic roles. Working as both a pyruvate kinase with catalytic activity and a protein kinase that phosphorylates its substrates, PKM2 stands at the crossroads of glycolysis and tumor growth. Recently, it was revealed that the catalytic activity of PKM2 can be regulated by its posttranslational modification (PTM). Several PTM types, including phosphorylation, methylation, acetylation, oxidation, hydroxylation, succinylation, and glycylation, have been gradually identified on different amino acid residues of the PKM2 coding sequence. In this review, we highlight the recent advancements in understanding PKM2 PTMs and the regulatory roles conferred by PTMs during anaerobic glycolysis in tumors.

MiR-106b promotes migration and invasion through enhancing EMT via downregulation of Smad 7 in Kazakh's esophageal squamous cell carcinoma

Accumulated evidence suggests that miR-106b played a key role in the promotion of the metastases of cancer; however, little is known about miR-106b in esophageal squamous cell carcinoma (ESCC). To investigate expression level of miR-106b in ESCC tissues, quantitative real-time polymerase chain reaction (qRT-PCR) was used to detect miR-106b expression in 35 Kazakh's ESCC and paired normal adjacent tissues (NATs). To evaluate the role mediated by miR-106b in the proliferation, migration, and invasion, MTT, wound healing, and transwell assays were employed, respectively. Luciferase reporter assay was used to identify the downstream target through miR-106b. To understand the regulation between miR-106b and Smad 7, qRT-PCR and western blot were performed. The present study showed that miR-106b was pronouncedly upregulated in ESCC relative to paired NAT and that upregulated miR-106b was significantly associated with lymph node metastases. MiR-106b was found to be able to promote proliferation, migration, and invasion of ESCC cells in vitro. Smad 7 was confirmed as a downstream target of miR-106b in our experimental setting. Smad 7 was remarkably downregulated in ESCC compared with paired NAT. In addition, upregulation of miR-106b can promote epithelial mesenchymal transition (EMT) in ESCC cell in vitro. Our results indicated that miR-106b can promote migration and invasion of ESCC cells through enhancing EMT process via downregulation of Smad 7, suggesting that miR-106b can be a potential molecular phenotype in ESCC metastases.

LncRNA SLCO4A1-AS1 modulates colon cancer stem cell properties by binding to miR-150-3p and positively regulating SLCO4A1

Long non-coding RNAs (lncRNAs) play important roles in a range of different human cancers. However, the role of lncRNA solute carrier organic anion transporter family member 4A1-AS1 (SLCO4A1-AS1) in colon cancer remains enigmatic. Hence, we aimed to explore the specific role of SLCO4A1-AS1 in colon cancer stem cells. Colon cancer-related differentially expressed lncRNA and mRNA were screened using microarray-based analysis, and the expression of SLCO4A1-AS1 and SLCO4A1 in colon cancer tissues was determined using reverse transcription quantitative polymerase chain reaction and western blot analysis. The interaction among SLCO4A1-AS1, microRNA-150-3p (miR-150-3p) and SLCO4A1 was verified using dual-luciferase reporter assay, RNA immunoprecipitation and RNA pull-down. Moreover, SLCO4A1-AS1, miR-150-3p and/or SLCO4A1 were overexpressed or depleted in colon cancer cells to detect their effects on migration, invasion, sphere formation, apoptosis and tumorigenesis abilities of colon cancer stem CD133+CD44+ cells using both in vitro and in vivo assays. SLCO4A1-AS1 and SLCO4A1 were screened as the differentially expressed lncRNA and mRNA in colon cancer tissues. SLCO4A1-AS1 was confirmed to competitively bind to miR-150-3p to elevate SLCO4A1 expression. Moreover, knockdown of SLCO4A1-AS1 decreased SLCO4A1 expression, thus inhibiting cell migration, invasion, sphere formation, and tumorigenesis abilities and enhancing the apoptosis of CD133+CD44+ cells. Collectively, these findings provide evidence demonstrating that depleting SLCO4A1-AS1 competitively binds to miR-150-3p, which downregulates SLCO4A1 expression, thus hindering colon cancer progression.

CALM1 promotes progression and dampens chemosensitivity to EGFR inhibitor in esophageal squamous cell carcinoma

BACKGROUND

Calmodulin1 (CALM1) has been identified as one of the overexpression genes in a variety of cancers and EGFR inhibitor have been widely used in clinical treatment but it is unknown whether CALM1 and epidermal growth factor receptor (EGFR) have a synergistic effect in esophageal squamous cell carcinoma (ESCC). The aim of the present study was to explore the synergistic effects of knock-out CALM1 combined with EGFR inhibitor (Afatinib) and to elucidate the role of CALM1 in sensitizing the resistance to Afatinib in ESCC.

METHOD

Immunohistochemistry (IHC) and qRT-PCR were used to examine the expression of CALM1 and EGFR in ESCC tissues. Kaplan-Meier survival analysis was used to analyze the clinical and prognostic significance of CALM1 and EGFR expression in ESCC. Furthermore, to evaluate the biological function of CALM1 in ESCC, the latest gene editing technique CRISPR/Cas9(Clustered regularly interspaced short palindromic repeats)was applied to knockout CALM1 in ESCC cell lines KYSE150, Eca109 and TE-1. MTT, flow cytometry, Transwell migration, scratch wound-healing and colony formation assays were performed to assay the combined effect of knock-out CALM1 and EGFR inhibitor on ESCC cell proliferation and migration. In addition, nude mice xenograft model was used to observe the synergistic inhibition of knock-out CALM1 and Afatinib.

RESULTS

Both CALM1 and EGFR were found to be significantly over-expressed in ESCC compared with paired normal control. Over-expressed CALM1 and EGFR were significantly associated with clinical stage, T classification and poor overall prognosis, respectively. In vitro, the combined effect of knock-out CALM1 mediated by the lentivirus and EGFR inhibitor was shown to be capable of inhibiting the proliferation, inducing cell cycle arrest at G1/S stage and increasing apoptosis of KYSE-150 and Eca109 cells; invasion and migration were also suppressed. In vivo, the results of tumor weight and total fluorescence were markedly reduced compared with the sgCtrl-infected group and sgCAML1 group.

CONCLUSION

Our data demonstrated that knock-out of CALM1 could sensitize ESCC cells to EGFR inhibitor, and it may exert oncogenic role via promotion of EMT. Taken together, CALM1 may be a tempting target to overcome Afatinib resistance.

M2 isoform of pyruvate kinase (PKM2) is upregulated in Kazakh's ESCC and promotes proliferation and migration of ESCC cells

The objectives of the present study are to explore role of pyruvate kinase isoenzyme type M2 (PKM2) in progression of Kazakh's esophageal squamous cell carcinoma (ESCC) in Xinjiang, China, and to clarify mechanism of PKM2 in malignant phenotype. PKM2 expression was examined using immunohistochemistry (IHC) in 101 matched pairs of ESCC and normal adjacent tissues (NATs) and using enzyme-linked immunosorbent assay (ELISA) in 35 serum samples of Kazakh's ESCC and 8 serum samples of healthy subjects. To investigate mechanism, small interfering RNA (siRNA)-PKM2 was transfected into ESCC cells. Cell migration and invasion were evaluated by wound healing and Transwell assays. Apoptosis and cell cycle were analyzed by flow cytometry (FCM). PKM2 expression was significantly higher in ESCC tissues (77.2 %, 78/101) compared with matched NAT (P = 0.003) and also higher in serum samples of Kazakh's ESCC patients (78.84 ng/mL) compared with healthy subjects (13.55 ng/mL) (P = 0.001). Patients with overexpression of PKM2 had a poor prognosis (P = 0.032). After knockdown of PKM2, cell proliferation, migration, and invasion were significantly reduced (P = 0.001), apoptosis increased (P = 0.001), and cell cycle was arrested at G1 phase. PKM2 overexpression was significantly correlated with the worse outcome of Kazakh's ESCC. Furthermore, PKM2 was involved in progression of ESCC by promoting proliferation and suppressing apoptosis, accelerating invasion, and influencing cell cycle. PKM2 could be a potential biomarker for molecular classification of ESCC.

Northwestern China: a place to learn more on oesophageal cancer. Part two: gene alterations and polymorphisms

In the first part of this review, some behavioural and environmental risk factors playing important roles in the development of Kazakh's oesophageal squamous cell carcinoma (OSCC) were presented. Although all individuals have been exposed to the same environment and share the same behaviour, some of them will not develop OSCC. Thus, gene susceptibility and/or gene polymorphism are unavoidably involved. The molecular events underlying the initiation and progression of OSCC remain, however, poorly understood. In the second part of our review of OSCC in northwestern China, especially in the high-risk Kazakh population, some recent progress in the study of the molecular biology underlying oesophageal carcinogenesis, including chromosome deletions and loss of heterozygocity, polymorphisms of genes involved in xenobiotic metabolizing and DNA repair, and genetic alterations of transcriptional factors and apoptosis genes are presented. Results obtained in this high-risk population are compared with those obtained in other areas that are also known to be at high risk for OSCC, and whenever possible, with those studies performed in European, American or Australian low-risk areas. Recent advances in the investigation of the proteomics and microRNA biomarkers potentially useful for an earlier diagnosis and/or prognosis of OSCC are also discussed.

New potential biomarkers in the diagnosis of esophageal squamous cell carcinoma

OBJECTIVE

To analyse the alterations of serum proteins in cases of esophageal squamous cell carcinoma (ESCC) in order to screen and validate serum marker patterns for the diagnosis of ESCC in the high-risk populations of Xinjiang, China.

METHODS

The serum proteomic patterns of 188 cases, including 139 patients with ESCC (54 Uygur, 45 Kazakh and 40 Han subjects) and 49 sex- and age-matched healthy controls, were detected using the SELDI-TOF-MS (surface-enhanced laser desorption/ionization-time of flight-mass spectrometry) technology with the CM10 ProteinChip. Differences in protein peaks between patients with ESCC and controls were analysed using the Biomarker Pattern Software, and a primary diagnosis model of ESCC was developed and validated with SVM (support vector machines). This model was further evaluated by a large-scale blind test.

RESULTS

Two hundred and eighty-three protein peaks were detected within the molecular range of 0-20 kDa, among which, 140 peaks were significantly different between ESCC cases and controls (p < 0.05). A diagnostic pattern consisting of six protein peaks (m/z 5667, 5709, 5876, 5979, 6043 and 6102) was established with a sensitivity of 97.12% and a specificity of 83.87%. The large-scale blind test generated a sensitivity of 91.43% and a specificity of 88.89%.

CONCLUSIONS

The differential protein peaks analysed by SELDI-TOF-MS may contain promising serum biomarkers for screening ESCC. The diagnostic model which combined only six protein peaks had a satisfactory discriminatory power. The model should be further evaluated in other populations of ESCC patients and tested against controls. The nature and function of the discriminating proteins have yet to be elucidated.

MicroRNA-21 promotes cell growth and migration by targeting programmed cell death 4 gene in Kazakh's esophageal squamous cell carcinoma

Esophageal cancer (EC) is the eighth most common cancer worldwide and the sixth most common cause of cancer death. There are two main types of EC--squamous cell carcinoma (ESCC) and adenocarcinoma (EAC). Although some advances in the exploration of its possible etiological mechanism were made recently including behaviors and environmental risk factors as well as gene alterations, the molecular mechanism underlying ESCC carcinogenesis and progression remains poorly understood. It has been reported that miR-21 was upregulated in most malignant cancers, the proposed mechanism of which was through suppressing expression of programmed cell death 4 (PDCD4). In present study, it is firstly reported that miR-21 was upregulated in Kazakh's ESCC and that miR-21 played a negative role in regulating PDCD4 using in situ hybridization (ISH) and luciferase reporter approach. Morever, in model of ESCC xenografted nude mice, miR-21 maybe used as an effective target in the treatment. The present results demonstrated that miR-21 may be a potential therapeutic target in management of ESCC.

Plasma‑derived exosomal pyruvate kinase isoenzyme type M2 accelerates the proliferation and motility of oesophageal squamous cell carcinoma cells

Exosomal pyruvate kinase isoenzyme type M2 (PKM2) has been found to play a key role in the progression of human hepatocarcinoma. However, exosomal PKM2 (especially plasma‑derived exosomal PKM2), in patients with oesophageal squamous cell carcinoma (ESCC) has not been well defined. In the present study, plasma‑derived exosomes were isolated from healthy controls and patients with ESCC, and identified by transmission electronic microscopy, western blotting, nano‑flow cytometry, nanoparticle tracking and phagocytosis analysis; exosomal PKM2 was detected by western blotting and ELISA. In addition, changes in cellular proliferation and motility in recipient cells (Eca109) were assessed using Cell Counting Kit‑8, colony formation, wound‑healing and Transwell assays. The PKM2 content was higher in exosomes from patients with ESCC than in those from healthy donors. Furthermore, exosomes from patients with ESCC enhanced the proliferation and motility of ESCC cells in vitro. Notably, PKM2 was found to be transferred by exosomes, and was able to act by activating STAT3. To verify the association between PKM2 and STAT3, immunohistochemistry was employed to analyse the protein levels of PKM2 and pSTAT3Tyr705. These data revealed that PKM2 and pSTAT3Tyr705 were upregulated and associated with overall survival in patients with ESCC. Therefore, the present study highlights that exosomes from patients with ESCC enhance the migration and invasiveness of ESCC cells by transferring PKM2.

SUMOylation of HSP27 regulates PKM2 to promote esophageal squamous cell carcinoma progression

A previous proteomic screening of differentially expressed biomarkers between Kazakh patients with esophageal squamous cell carcinoma (ESCC) and normal adjacent tissues demonstrated that heat shock protein 27 (HSP27) and pyruvate kinase isoenzyme M2 (PKM2) were both highly expressed in ESCC samples compared with normal controls. However, the regulatory association between HSP27 and PKM2 in ESCC remains elusive. In the present study, immunohistochemistry and immunoblotting were adopted to examine the expression of HSP27, PKM2 and other relevant biomarkers involved in epithelial‑to‑mesenchymal transition in clinical tissue samples. The interactions between proteins were detected by co‑immunoprecipitation (Co‑IP) assay and further confirmed by immunofluorescence assay. The growth and motility of ESCC cells were examined by MTT, Transwell and wound healing assays. Overexpression of HSP27 was found to be significantly associated with T‑cell classification, lymph node metastasis and poor prognosis in ESCC. In addition, HSP27 expression was significantly correlated with PKM2 expression in ESCC specimens. Functionally, knockdown of HSP27 inhibited the growth and motility of ESCC cells. Moreover, HSP27 was found to directly interact with small ubiquitin‑related modified protein 2/3 (SUMO2/3) in ESCC cell lines, as evidenced by Co‑IP and laser confocal imaging. In addition, downregulation of HSP27 was shown to decrease PKM2 and E‑cadherin expression. Knockdown of SUMO2/3 was observed to reduce the expression of HSP27, PKM2 and EMT‑related biomarkers. The results of the present study indicated that the SUMOylation of HSP27 enhances the proliferation, invasion and migration of ESCC cells via PKM2.