P4HA1 expression and function in esophageal squamous cell carcinoma.

This study aimed to explore the effect of P4HA1 (prolyl 4-hydroxylase subunit α1) and its ratio on the prognosis of esophageal squamous cell carcinoma. The expression data of P4HA1 in esophageal cancer in The Cancer Genome Atlas and Genotype-Tissue Expression were collected using the public database gene expression profiling interactive analysis. The expression levels of P4HA1 were examined by immunohistochemistry. The relationship between P4HA1 expression and clinicopathological parameters was analyzed the χ2 test. Survival analysis was performed to investigate the effect of P4HA1 and its ratio on prognosis. Compared with normal esophageal mucosal epithelium, there was higher P4HA1 gene mRNA in esophageal cancer tissue. Regarding the expression level, no significant difference was observed in patients with stage I-IV esophageal cancer. Immunohistochemistry showed that P4HA1 was highly expressed in esophageal squamous cell carcinoma (68.7%), while it was negatively expressed in paracancerous tissues. There was a significant difference in expression between cancer and adjacent tissues. The expression of P4HA1 associated with the degree of tumor differentiation, site, lymph node metastasis, and tumor node metastasis stage. The prognostic factors that affected the OS (overall survival) of esophageal cancer patients were the degree of differentiation, lymph node metastasis, and P4HA1 expression. Multivariate analysis of the OS results of patients showed that lymph node metastases and P4HA1 expression were independent prognostic factors that affected the OS of esophageal cancer patients. The prognostic factors affecting the PFS (progression-free survival) of esophageal cancer patients in the univariate survival analysis were as follows: degree of differentiation, lymph node metastasis, and P4HA1 expression. In addition, multivariate analysis of the PFS results of patients showed that lymph node metastasis and P4HA1 expression were independent prognostic factors that affected the PFS of esophageal cancer patients. P4HA1 may be a novel potential biomarker for the early diagnosis, prognosis, and targeted therapy of esophageal cancer.

Clinical features of superficial esophagus squamous cell carcinoma according to alcohol-degrading enzyme ADH1B and ALDH2 genotypes.

BACKGROUND: Inactivated alcohol dehydrogenase (ADH) and aldehyde dehydrogenase (ALDH) are related to esophageal carcinogenesis. We aimed to clarify the clinical features associated with the alcohol-degrading enzyme genotypes, ADH1B and ALDH2. We also investigated the risk factors for metachronous esophageal squamous cell carcinoma (ESCC) and head and neck SCC (HNSCC). METHODS: We conducted a single-center, retrospective study including patients with ESCC treated by endoscopic resection. Patients were recruited between October 2020 and September 2021. Buccal mucosal swabs were obtained from them to analyze the genetic polymorphisms affecting ADH (ADH1B) and ALDH (ALDH2) activity. Patients were categorized into three groups: both inactivated = double-inactivated group; inactivated ADH1B or ALDH2 = single-inactivated group; and both activated = activated group. RESULTS: Among the 297 enrolled patients, patients in the double-inactivated group were significantly younger (P < 0.001) and 60% of them were ≤ 50 years old. This group also had more ESCCs located in the upper esophagus (P < 0.001) and more simultaneous multiple ESCCs (P = 0.044). More than half of the patients had multiple Lugol-voiding lesions (LVLs) (P < 0.001) and heavy alcohol consumers (P = 0.012). Metachronous ESCC and HNSCC were more common in the double-inactivated group (P < 0.001, P = 0.001). Multivariate analysis identified located in the upper esophagus, multiple LVLs and history of HNSCC as risk factors for metachronous ESCC. CONCLUSIONS: Activation patterns of alcohol-metabolizing enzymes were related to age at ESCC onset, lesion location, and metachronous ESCC and HNSCC. Different approaches to the prophylaxis and treatment of esophageal cancer should be considered, depending on the enzyme activity pattern.

Immuno-oncological role of 20S proteasome alpha-subunit 3 in aggravating the progression of esophageal squamous cell carcinoma.

PSMA3, a member of the proteasome subunit, has been shown to play a major player in protein degradation. Reportedly, PSMA3 functions as a negative regulator in various cancers including colon, pancreatic and gastric cancers. However, the contributions of PSMA3 to the progression of esophageal squamous cell carcinoma (ESCC) and the underlying mechanism remain unclear. Therefore, in this study, we investigated whether PSMA3 is involved in ESCC progression and the potential underlying mechanism. The results revealed that PSMA3 was highly expressed in the ESCC tumor tissues and functioned as a negative indicator according to the data from The Cancer Genome Atlas (TCGA)/Gene Expression Omnibus (GEO) datasets and clinical patients' samples. Pathway enrichment analysis showed that PSMA3 was closely correlated with ESCC cancer stemness and the inflammatory response; however, this correlation was absent after knockdown of PSMA3 in vitro. We further demonstrated that PSMA3 suppressed CD8+ T-cells infiltration depending on the C-C motif chemokine ligand 3 (CCL3)/C-C motif chemokine receptor 5 (CCR5) axis. Collectively, these results demonstrate the role of PSMA3 in ESCC cancer stemness and the negative regulation of CD8 T-cells infiltration mediated by PSMA3. The results of this study may provide a potential target for the immuno-oncology effect of PSMA3 in ESCC therapy.

Lysine-Specific Histone Demethylase 1 Promotes Oncogenesis of the Esophageal Squamous Cell Carcinoma by Upregulating DUSP4.

Esophageal squamous cell carcinoma (ESCC) is a predominant subtype of esophageal cancer (EC) and has a poor prognosis due to its aggressive nature. Accordingly, it is necessary to find novel prognostic biomarkers and therapeutic targets for ESCC. Lysine-specific histone demethylase 1 (LSD1) plays a core role in the regulation of ESCC oncogenesis. However, the detailed mechanism of LSD1-regulated ESCC growth has not been elucidated. This study aims to explore molecular mechanism underlying the LSD1-regulated ESCC's oncogenesis. After LSD1 silencing, we detected differentially expressed genes (DEGs) in human ESCC cell line, TE-1, by transcriptome sequencing. Subsequently, we investigated expression pattern of the selected molecules in the ESCC tissues and cell lines by qRT-PCR and Western blotting. Furthermore, we explored the roles of selected molecules in ESCC using gene silencing and overexpression assays. Transcriptome sequencing showed that the expression of dual specificity phosphatase 4 (DUSP4) in TE-1 was significantly attenuated after the LSD1 silencing. In addition, the DUSP4 mRNA expression level was significantly higher in the ESCC tissues, especially in those derived from patients with invasion or metastasis. Moreover, the DUSP4 expression was positively associated with the LSD1 expression in the ESCC tissues. DUSP4 overexpression promoted proliferation, invasion, and migration of the ESCC cells, while DUSP4 silencing had an opposite effect. DUSP4 overexpression also enhanced tumorigenicity of the ESCC cells in vivo, while DUSP4 silencing inhibited tumor growth. Importantly, inhibition of cell proliferation, invasion, and migration by the LSD1 inhibitor (ZY0511) was reversed by DUSP4 overexpression. Conclusively, we found that LSD1 promotes ESCC's oncogenesis by upregulating DUSP4, the potential therapeutic and diagnostic target in ESCC.

ALKBH5 Is Lowly Expressed in Esophageal Squamous Cell Carcinoma and Inhibits the Malignant Proliferation and Invasion of Tumor Cells.

BACKGROUND: Modification of N6-methyladenosine (m6A) and RNA m6A regulatory factors is required in cancer advancement. The contribution of m6A and its alteration in esophageal squamous cell carcinoma (ESCC) is still unclear. RESULTS: ALKBH5 was lowly expressed in ESCC tissues, which the total m6A level was increased in ESCC tissue than the presentation in normal healthy tissue. The pcDNA3.1-ALKBH5 recombinant plasmid was transfected into KYSE-150 and Eca-109 cells. The overexpression of ALKBH5 is responsible for a significant reduction of the total m6A levels in Eca-109 and KYSE150 cells, inhibiting the proliferation capability, migration, and cell invasion. CONCLUSIONS: ALKBH5 as a demethylase was lowly expressed in cancer progression of ESCC and acts as a crucial component in ESCC progression.

Pyk2 level is a novel prognostic marker for patients with esophageal squamous cell carcinoma after radical surgery.

Esophageal squamous cell carcinoma (ESCC) is one of the most common malignant tumors in East Asia. Surgical resection is currently the typical treatment. However, due to the highly invasive and metastatic characteristic of the disease, the mortality rate is still high. A search for potential prognostic biomarkers and therapeutic targets is very necessary. Here, we studied the expression of proline-rich tyrosine kinase 2 (Pyk2), a non-receptor tyrosine protein kinase, in ESCC and its influence on prognosis. A total of 112 cases of ESCC and paired adjacent normal tissues (NT) were organized in tissue microarray (TMA) from the Nantong First People's Hospital. Our analysis of TMA revealed that Pyk2 levels were higher in ESCC than in paired adjacent NT by immunohistochemistry (p<0.001). Western blot and real-time quantitative PCR analysis (p=0.0359) also reached similar conclusions. To further explore the significance of Pyk2 in ESCC, another set of tissue microarrays was collected from the Affiliated Hospital of Nantong University, which includes 241 consecutive patients undergoing radical surgery for ESCC, to perform IHC scores. We demonstrated that the expression level of Pyk2 was positively correlated with N stage (node negative versus node positive, p=0.02) and clinical stage (I + II versus III + IV, p=0.042). Univariate and multivariate analyses suggested that high Pyk2 expression was an independent prognostic factor for overall survival with ESCC. Cell function studies found that Pyk2 promoted tumor proliferation and migration and reduced apoptosis. Pyk2 knockdown enhanced the sensitivity to cisplatin in ESCC cells. Western blot analysis confirmed that Pyk2 may promote tumor progression by activating the Akt signaling pathway.

RECQL4 regulates DNA damage response and redox homeostasis in esophageal cancer.

Objective: RECQL4 (a member of the RECQ helicase family) upregulation has been reported to be associated with tumor progression in several malignancies. However, whether RECQL4 sustains esophageal squamous cell carcinoma (ESCC) has not been elucidated. In this study, we determined the functional role for RECQL4 in ESCC progression. Methods: RECQL4 expression in clinical samples of ESCC was examined by immunohistochemistry. Cell proliferation, cellular senescence, the epithelial-mesenchymal transition (EMT), DNA damage, and reactive oxygen species in ESCC cell lines with RECQL4 depletion or overexpression were analyzed. The levels of proteins involved in the DNA damage response (DDR), cell cycle progression, survival, and the EMT were determined by Western blot analyses. Results: RECQL4 was highly expressed in tumor tissues when compared to adjacent non-tumor tissues in ESCC (P < 0.001) and positively correlated with poor differentiation (P = 0.011), enhanced invasion (P = 0.033), and metastasis (P = 0.048). RECQL4 was positively associated with proliferation and migration in ESCC cells. Depletion of RECQL4 also inhibited growth of tumor xenografts in vivo. RECQL4 depletion induced G0/G1 phase arrest and cellular senescence. Importantly, the levels of DNA damage and reactive oxygen species were increased when RECQL4 was depleted. DDR, as measured by the activation of ATM, ATR, CHK1, and CHK2, was impaired. RECQL4 was also shown to promote the activation of AKT, ERK, and NF-kB in ESCC cells. Conclusions: The results indicated that RECQL4 was highly expressed in ESCC and played critical roles in the regulation of DDR, redox homeostasis, and cell survival.

CYP2C9 inhibits the invasion and migration of esophageal squamous cell carcinoma via downregulation of HDAC.

Cytochrome P450 2C9 (CYP2C9) is involved in the metabolism of cancer drugs and exogenous carcinogens. In our study, CYP2C9 was downregulated in multiple cohorts of human esophageal squamous cell carcinoma (ESCC). Until now, its role and epigenetic regulation of CYP2C9 repression in ESCC remain poorly understood. CYP2C9 repression in collected ESCC patient tumor tissues was demonstrated by RT-qPCR and Western blot. The histone acetylation level was carried out by the treatment of histone deacetylase inhibitor TSA and RNA interference. Epigenetic analysis revealed that the increased expression of CYP2C9 in KYSE-150 and TE1 cells was characterized by inhibition of HDAC8 and HDAC1, respectively. TSA decreased the levels of HDAC occupancy around CYP2C9 promoter region greatly. Overexpression of CYP2C9 reduced the invasion and migration of ESCC cells.

Impact of Deoxycholic Acid on Oesophageal Adenocarcinoma Invasion: Effect on Matrix Metalloproteinases.

Bile acids (BAs) have been implicated in the development of oesophagitis, Barrett's oesophagus and oesophageal adenocarcinoma (OAC). However, whether BAs promote cancer invasiveness has not been elucidated. We evaluated the role of BAs, in particular deoxycholic acid (DCA), in OAC invasion. Migration and invasiveness in untreated and BA-treated oesophageal SKGT-4 cancer cells were evaluated. Activity and expression of different matrix metalloproteinases (MMPs) were determined by zymography, ELISA, PCR and Western blot. Finally, human OAC tissues were stained for MMP-10 by immunohistochemistry. It was found that SKGT-4 cells incubated with low concentrations of DCA had a significant increase in invasion. In addition, MMP-10 mRNA and protein expression were also increased in the presence of DCA. MMP-10 was found to be highly expressed both in-vitro and in-vivo in neoplastic OAC cells relative to non-neoplastic squamous epithelial cells. Our results show that DCA promotes OAC invasion and MMP-10 overexpression. This study will advance our understanding of the pathophysiological mechanisms involved in human OAC and shows promise for the development of new therapeutic strategies.

Elevated DHODH expression promotes cell proliferation via stabilizing ß-catenin in esophageal squamous cell carcinoma.

As a key enzyme in de novo pyrimidine biosynthesis, the expression level of dihydroorotate dehydrogenase (DHODH) has been reported to be elevated in various types of malignant tumors and its tumor-promoting effect was considered to relate to its pyrimidine synthesis function. Here, we revealed one intriguing potential mechanism that DHODH modulated ß-catenin signaling in esophageal squamous cell carcinoma (ESCC). We demonstrated that DHODH directly bound to the NH2 terminal of ß-catenin, thereby, interrupting the interaction of GSK3ß with ß-catenin and leading to the abrogation of ß-catenin degradation and accumulation of ß-catenin in the nucleus, which in turn, resulted in the activation of ß-catenin downstream genes, including CCND1, E2F3, Nanog, and OCT4. We further demonstrated that the regulation of ß-catenin by DHODH was independent of DHODH catalyzing activity. Univariate and multivariate analyses suggested that DHODH expression might be an independent prognostic factor for ESCC patients. Collectively, our study highlights the pivotal role of DHODH mediated ß-catenin signaling and indicates that DHODH may act as a multi-functional switcher from catalyzing pyrimidine metabolism to regulating tumor-related signaling pathways in ESCC.

Matrix metalloproteinase-14 (MMP-14) downregulation inhibits esophageal squamous cell carcinoma cell migration, invasion, and proliferation.

BACKGROUND: Matrix metalloproteinase-14 (MMP-14) is known to be a key regulator of oncogenesis and tumor progression. The present study was designed to assess the relationship between the downregulation of MMP-14 and the in vitro proliferative, migratory, and invasive activity of esophageal squamous cell carcinoma (ESCC) cells. METHODS: MMP-14 expression in human ESCC and paracancerous normal esophageal tissue samples was evaluated via immunohistochemistry, and correlations between MMP-14 staining and patient clinicopathological features were examined. In addition, siRNA was used to knockdown MMP-14 in ESCC cells, and the proliferation and invasive activity of these cells were then evaluated via MTT and Transwell assays, respectively. Flow cytometry was additionally used to assess cell cycle progression, while Western blotting was employed to measure protein levels within these cells. RESULTS: ESCC samples were found to exhibit MMP-14 overexpression relative to paracancerous tissue samples, and this overexpression was positively correlated with tumor T classification (T1-2 vs. T3; P < 0.05), N classification (negative vs. positive; P < 0.001), degree of differentiation (G1 vs. G3, P < 0.05; G2 vs. G3, P < 0.05) and clinical stage (I-IIA vs. IIB-III; P < 0.05). When MMP-14 was knocked down in ESCC cells, this induced cell cycle arrest, impairing their proliferative and invasive activity. CONCLUSIONS: MMP-14 is a key regulator of the proliferation and invasion of ESCC cells, making it a viable therapeutic target for the treatment of this cancer.

Omipalisib Inhibits Esophageal Squamous Cell Carcinoma Growth Through Inactivation of Phosphoinositide 3-Kinase (PI3K)/AKT/Mammalian Target of Rapamycin (mTOR) and ERK Signaling.

BACKGROUND Esophageal squamous cell carcinoma (ESCC) is a life-threatening digestive tract malignancy with no known curative treatment. This study aimed to investigate the antineoplastic effects of omipalisib and its underlying molecular mechanisms in ESCC using a high throughput screen. MATERIAL AND METHODS MTT assay and clone formation were used to determine cell viability and proliferation. Flow cytometry was conducted to detect cell cycle distribution and apoptosis. Global gene expression and mRNA expression levels were determined by RNA sequencing and real-time PCR, respectively. Protein expression was evaluated in the 4 ESCC cell lines by Western blot analysis. Finally, a xenograft nude mouse model was used to evaluate the effect of omipalisib on tumor growth in vivo. RESULTS In the pilot screening of a 1404-compound library, we demonstrated that omipalisib markedly inhibited cell proliferation in a panel of ESCC cell lines. Mechanistically, omipalisib induced G0/G1 cell cycle arrest and apoptosis. RNA-seq, KEGG, and GSEA analyses revealed that the PI3K/AKT/mTOR pathway is the prominent target of omipalisib in ESCC cells. Treatment with omipalisib decreased expression of p-AKT, p-4EBP1, p-p70S6K, p-S6, and p-ERK, therefore disrupting the activation of PI3K/AKT/mTOR and ERK signaling. In the nude mouse xenograft model, omipalisib significantly suppressed the tumor growth in ESCC tumor-bearing mice without obvious adverse effects. CONCLUSIONS Omipalisib inhibited the proliferation and growth of ESCC by disrupting PI3K/AKT/mTOR and ERK signaling. The present study supports the rationale for using omipalisib as a therapeutic approach in ESCC patients. Further clinical studies are needed.

Membranous NOX5-derived ROS oxidizes and activates local Src to promote malignancy of tumor cells.

Reactive oxygen species (ROS) localized at the precise subcellular compartments are essential for regulating the activity of signaling proteins. Furthermore, ROS are master regulators of tumor malignant progression that respond to a diverse set of environmental stress, especially hypoxia. NADPH oxidases (NOXs) appear to be activated within discrete subcellular compartments to facilitate local ROS production. However, the subcellular function of NOXs in hypoxic tumor is still unclear. In this study, we demonstrated that NOX5 was greatly upregulated in clinical esophageal squamous cell carcinoma (ESCC) tumors, ESCC cell lines or primary ESCC cells, and elevated NOX5 was correlated to malignancy of ESCC tumors and poor prognosis. NOX5 induced the malignant progression of ESCC by activating Src, especially under hypoxic condition. Mechanistically, we showed that hypoxia promoted the interaction between NOX5 and Pyk2 on cell membrane via facilitating Ca2+-mediated Pyk2 Tyr402 site phosphorylation. Subsequently, Pyk2 acted as a scaffold for c-Abl phosphorylating the catalytic domain of NOX5 Tyr476/478 sites, which in turn upregulated hydrogen peroxide (H2O2) inside the Pyk2/NOX5 complex to oxidize and activate local Src. These findings provide insights into the biological significance of NOX5 in the development of ESCC.

TWIST1 upregulates matrix metalloproteinase (MMP) genes family in esophageal squamous carcinoma cells.

Twist-related protein 1 (TWIST1), a highly conserved basic helix-loop-helix transcription factor, stimulates epithelial-mesenchymal transition (EMT) and plays a crucial role in the regulation of the extracellular matrix (ECM) and cell-cell adhesion. Our aim in this study was to evaluate the functional correlation between TWIST1 and MMP genes in human ESCC cell lines, KYSE-30 and YM-1. To generate recombinant retroviral particles, the Pruf-IRES-GFP-hTWIST1 was co-transfected into HEK293T along with pGP and pMD2. G as well as Pruf-IRES-GFP control plasmid. Stably transduced high-expressing GFP-hTWIST1 and GFP-control KYSE-30 cells were generated. The produced retroviral particles were transduced into the KYSE-30 and YM-1 ESCC cells. Ectopic expression of TWIST1 mRNA and expression of the MMP genes (MMP-2, MMP-3, MMP-7, MMP-9, and MMP-10) were examined by relative comparative real-time PCR. In silico analysis of the MMP markers and their promoter elements was explored. Moreover, the scratch wound assay was used to evaluate the migration of TWIST1-induced cells. TWIST1 level was up-regulated by nearly 5-fold and 7.4-fold in GFP-hTWIST1 KYSE-30 and YM-1 cells compared to GFP control cells, respectively. Interestingly, this enforced expression of TWIST1 subsequently caused significant overexpression of transcripts for selected MMP genes in GFP-hTWIST1 in comparison with GFP control cells in both ESCC cell lines. Also, the scratch assay indicated that TWIST1 expression effectively increased the migration of GFP-TWIST1 KYSE-30 cells against GFP KYSE-30 control cells in vitro. The present findings illuminate that TWIST1 may contribute broadly to ESCC development in concert with up-regulation of MMPs expression and further suggest the potential advantage of exerting TWIST1/MMPs signaling axis as a framework from which to expand our understanding about the mechanisms of ESCC tumorigenesis.

Lysyl oxidase-like 2 promotes esophageal squamous cell carcinoma cell migration independent of catalytic activity.

Lysyl oxidase-like 2 (LOXL2) is a member of the lysyl oxidase (LOX) family that contributes to tumor cell metastasis. Our previous data identified two splice variants of LOXL2 (i.e., LOXL2 Δ72 and Δ13) in esophageal squamous cell carcinoma (ESCC) cells that increased cell invasiveness and migration but had lower LOX activities than wild-type LOXL2 (LOXL2 WT). We generated a series of LOXL2 deletion mutants with different deleted biochemical domains and examined the relationship between the cell migration abilities and catalytic activities, as well as subcellular locations, of these deletion mutants compared with LOXL2 WT in ESCC cells to explore the mechanism of LOXL2-driven ESCC cell migration. Our results indicated that the deletion mutants of LOXL2 had impaired deamination enzymatic activity; LOXL2 ΔSRCR4, which lacks the fourth scavenger receptor cysteine-rich (SRCR) domain, had lower enzymatic activity; and LOXL2 Y689F had no catalytic activity compared with LOXL2 WT. However these two mutants stimulated greater cellular migration than LOXL2 WT. Furthermore, the degree of cell migration promoted by LOXL2 ΔLO (in which the LOX-like domain was deleted) was higher than that of LOXL2 WT, and LOXL2 ΔSRCR3, which does not have the third SRCR domain, had lower LOX activity and cellular migration ability than LOXL2 WT. These results suggested that LOXL2 promotes ESCC cell migration independent of catalytic activity.

LncRNA MIR31HG functions as a ceRNA to regulate c-Met function by sponging miR-34a in esophageal squamous cell carcinoma.

Accumulating evidence has demonstrated that long non-coding RNAs (lncRNAs) function as essential regulators in the development and progression of multiple tumors. However, the molecular mechanisms of MIR31HG in regulating ESCC progression remain unknown. Here, we confirmed that MIR31HG facilitated ESCC cells proliferation in vivo. Besides, MIR31HG knockdown increases the percentage of cells at the G1 phase, along with reduced arrest in S phase and MIR31HG overexpression exhibits the opposite effects. Overexpressed MIR31HG decreases the percentage of apoptotic ESCC cells. Interestingly, MIR31HG can function as a competing endogenous RNA by sponging miR-34a. The rescue experiments demonstrated that MIR31HG function is partially reversed by inhibiting miR-34a. In addition, we found c-Met is a target gene of miR-34a and is indirectly regulated by MIR31HG. Taken together, our findings revealed that MIR31HG promotes ESCC progression by regulating miR-34a/ c-Met axis and may provide a new prospective for exploration and understanding of the biological effects of esophageal squamous cell carcinoma.

Functional characterization of a low-frequency V1937I variant in FASN associated with susceptibility to esophageal squamous cell carcinoma.

Metabolic reprogramming has been regarded as one of the core hallmarks of cancer and increased de novo fatty acid synthesis has been documented in multiple tumors including esophageal squamous cell carcinoma (ESCC). Our previous exome-wide analyses found a Val1937Ile variant (rs17848945) in the 34th exon of fatty acid synthase (FASN) that showed a strong association with the risk of ESCC. In this study, we performed a series of functional assays to investigate the biological functions underlying this variant in the development of ESCC. We demonstrated that FASN was upregulated in ESCC and both knockdown and knockout of FASN significantly inhibited ESCC cell proliferation, suggesting a tumor promoter role for this gene in ESCC. Furthermore, the results showed that overexpression of FASN[I] in the ESCC cells substantially enhanced cell proliferation, compared with overexpression of FASN[V], or the control vector. Intriguingly, we found that the FASN[I] variant can enhance the enzyme activity of FASN, and, thus, increase the amount of the FASN end-product, palmitate in the ESCC cells. We also observed elevated palmitate levels in the plasma of the FASN[I] genotype carriers among a total of 632 healthy Chinese adults. In conclusion, our results suggested that the FASN V1937I variant influenced ESCC cell proliferation and susceptibility by altering the catabolic activity of FASN on palmitate. These findings may highlight an important role of palmitate metabolism in the development of ESCC and may contribute to the personalized medicine of this disease.

Ribosomal S6 protein kinase 4 promotes radioresistance in esophageal squamous cell carcinoma.

Esophageal squamous cell carcinoma (ESCC) is one of the most aggressive cancers and is highly resistant to current treatments. ESCC harbors a subpopulation of cells exhibiting cancer stem-like cell (CSC) properties that contribute to therapeutic resistance including radioresistance, but the molecular mechanisms in ESCC CSCs are currently unknown. Here, we report that ribosomal S6 protein kinase 4 (RSK4) plays a pivotal role in promoting CSC properties and radioresistance in ESCC. RSK4 was highly expressed in ESCC CSCs and associated with radioresistance and poor survival in patients with ESCC. RSK4 was found to be a direct downstream transcriptional target of ΔNp63α, the main p63 isoform, which is frequently amplified in ESCC. RSK4 activated the ß-catenin signaling pathway through direct phosphorylation of GSK-3ß at Ser9. Pharmacologic inhibition of RSK4 effectively reduced CSC properties and improved radiosensitivity in both nude mouse and patient-derived xenograft models. Collectively, our results strongly suggest that the ΔNp63α/RSK4/GSK-3ß axis plays a key role in driving CSC properties and radioresistance in ESCC, indicating that RSK4 is a promising therapeutic target for ESCC treatment.

Upregulation of Fucosyltransferase 3, 8 and protein O-Fucosyltransferase 1, 2 genes in esophageal cancer stem-like cells (CSLCs).

Recently, studies have shown that Fucosylation plays an important role in the invasion and metastatic process of CSLCs. Understanding the expression pattern of fucosyltransferase (FUT) genes may help to suggest better-targeted therapy strategies for esophageal squamous cell carcinoma (ESCC). The study aimed to address the expression pattern of FUT gene variants in esophageal CSLCs and parental adherent cells. Sphere formation method was used to enrich CSLCs. Expression of FUT genes was examined in tumor sphere and parental adherent cells using the RT-PCR method and then relative expression of detected variants was performed by the Real-Time PCR method in both groups. The detected FUTs, also, were assessed in fresh ESCC tumors and the matched healthy controls. Analysis of The cell surface carbohydrate Lewis x (LeX, CD15) was performed by flow cytometry. Molecular analysis showed that the expression of FUT 3, 8 and POFUT1, 2 genes in tumorsphere were significantly higher than parental adherent cells. Analysis of fresh ESCC tumor tissues and the matched healthy controls showed that FUT8 and POFUT1, 2 genes in contrast to FUT 3 have higher expression in tumor tissues than controls. Flow cytometric analyses revealed that tumorsphere and their parent cells do not differ significantly in Lewis x surface marker. The present study showed that FUT 3, 8 and POFUT1, 2 genes upregulated in esophageal CSLCs in comparison to adherent cells. Understanding the expression pattern of FUT gene variants may help to suggest better-targeted therapy strategies for ESCC.