14-3-3σ confers cisplatin resistance in esophageal squamous cell carcinoma cells via regulating DNA repair molecules. Tumour Biol. 2016;37:2127-2136. [PMID: 26346170 DOI: 10.1007/s13277-015-4018-6]

14-3-3σ downregulation sensitizes pancreatic cancer to carbon ions by suppressing the homologous recombination repair pathway

This study explored the role of 14-3-3σ in carbon ion-irradiated pancreatic adenocarcinoma (PAAD) cells and xenografts and clarified the underlying mechanism. The clinical significance of 14-3-3σ in patients with PAAD was explored using publicly available databases. 14-3-3σ was silenced or overexpressed and combined with carbon ions to measure cell proliferation, cell cycle, and DNA damage repair. Immunoblotting and immunofluorescence (IF) assays were used to determine the underlying mechanisms of 14-3-3σ toward carbon ion radioresistance. We used the BALB/c mice to evaluate the biological behavior of 14-3-3σ in combination with carbon ions. Bioinformatic analysis revealed that PAAD expressed higher 14-3-3σ than normal pancreatic tissues; its overexpression was related to invasive clinicopathological features and a worse prognosis. Knockdown or overexpression of 14-3-3σ demonstrated that 14-3-3σ promoted the survival of PAAD cells after carbon ion irradiation. And 14-3-3σ was upregulated in PAAD cells during DNA damage (carbon ion irradiation, DNA damaging agent) and promotes cell recovery. We found that 14-3-3σ resulted in carbon ion radioresistance by promoting RPA2 and RAD51 accumulation in the nucleus in PAAD cells, thereby increasing homologous recombination repair (HRR) efficiency. Blocking the HR pathway consistently reduced 14-3-3σ overexpression-induced carbon ion radioresistance in PAAD cells. The enhanced radiosensitivity of 14-3-3σ depletion on carbon ion irradiation was also demonstrated in vivo. Altogether, 14-3-3σ functions in tumor progression and can be a potential target for developing biomarkers and treatment strategies for PAAD along with incorporating carbon ion irradiation.

TAPI-1 Exhibits Anti-tumor Efficacy in Human Esophageal Squamous Cell Carcinoma Cells via Suppression of NF-κB Signaling Pathway

BACKGROUND

TNF-α processing inhibitor-1 (TAPI-1) is a known metalloproteinase inhibitor with potential anti-inflammatory effects. However, its anti-cancer effects on esophageal squamous cell carcinoma (ESCC) have not been uncovered.

AIM

In the present study, the effects of TAPI-1 on ESCC cell viability, migration, invasion, and cisplatin resistance and the underlying molecular mechanisms were investigated in TE-1 and Eca109 cells.

METHODS

To this end, TE-1 and Eca109 cells were exposed to TAPI-1 for indicated time intervals. Cell viability was assessed using cell counting kit-8 assay and apoptosis was evaluated using flow cytometry assay. Migration and invasion were assessed using Transwell assays. Gene expressions were analyzed using quantitative reverse transcription polymerase chain reaction. The activation of NF-κB signaling pathway was elucidated via Western blot and chromatin immunoprecipitation assay.

RESULTS

We observed that higher doses (10, 20 μM) of TAPI-1 inhibited ESCC cell viability, while a lower dose (5 μM) of TAPI-1 inhibited ESCC cell migration and invasion and enhanced the chemosensitivity of ESCC cells to cisplatin. Moreover, TAPI-1 suppressed the activation of NF-κB signaling and the target genes expression in the stage of transcription initiation. Furthermore, blocking NF-κB signaling in advance could abolish all the effects of TAPI-1 on ESCC cells.

CONCLUSION

Overall, these results indicated that TAPI-1 impairs ESCC cell viability, migration, and invasion and facilitates cisplatin-induced apoptosis via suppression of NF-κB signaling pathway. TAPI-1 may serve as a potential adjuvant agent with cisplatin for ESCC therapy.

Using a machine learning approach to identify key prognostic molecules for esophageal squamous cell carcinoma

Background

A plethora of prognostic biomarkers for esophageal squamous cell carcinoma (ESCC) that have hitherto been reported are challenged with low reproducibility due to high molecular heterogeneity of ESCC. The purpose of this study was to identify the optimal biomarkers for ESCC using machine learning algorithms.

Methods

Biomarkers related to clinical survival, recurrence or therapeutic response of patients with ESCC were determined through literature database searching. Forty-eight biomarkers linked to recurrence or prognosis of ESCC were used to construct a molecular interaction network based on NetBox and then to identify the functional modules. Publicably available mRNA transcriptome data of ESCC downloaded from Gene Expression Omnibus (GEO) and The Cancer Genome Atlas (TCGA) datasets included GSE53625 and TCGA-ESCC. Five machine learning algorithms, including logical regression (LR), support vector machine (SVM), artificial neural network (ANN), random forest (RF) and XGBoost, were used to develop classifiers for prognostic classification for feature selection. The area under ROC curve (AUC) was used to evaluate the performance of the prognostic classifiers. The importances of identified molecules were ranked by their occurrence frequencies in the prognostic classifiers. Kaplan-Meier survival analysis and log-rank test were performed to determine the statistical significance of overall survival.

Results

A total of 48 clinically proven molecules associated with ESCC progression were used to construct a molecular interaction network with 3 functional modules comprising 17 component molecules. The 131,071 prognostic classifiers using these 17 molecules were built for each machine learning algorithm. Using the occurrence frequencies in the prognostic classifiers with AUCs greater than the mean value of all 131,071 AUCs to rank importances of these 17 molecules, stratifin encoded by SFN was identified as the optimal prognostic biomarker for ESCC, whose performance was further validated in another 2 independent cohorts.

Conclusion

The occurrence frequencies across various feature selection approaches reflect the degree of clinical importance and stratifin is an optimal prognostic biomarker for ESCC.

MiR-200c-3p Modulates Cisplatin Resistance in Biliary Tract Cancer by ZEB1-Independent Mechanisms

Simple Summary

Biliary tract cancer is a rare malignancy with poor overall survival. The majority of patients are faced with advanced disease stage. Cisplatin-based treatment schedules represent the mainstay of first-line therapeutic strategy, yet only a small portion of patients develop a treatment response. One of the main reasons is acquired drug resistance. Previous studies correlated certain microRNAs (miRNAs), including miR-200c-3p, with drug resistance in various cancer types. However, limited knowledge exists about miR-200c-3p expression and cisplatin resistance in biliary tract cancer. Thus, the main aim of this study was to investigate the influence of miR-200c-3p on the cisplatin resistance in this cancer entity. We demonstrated that miR-200c-3p contributes to cisplatin resistance independently of its known influence on ZEB1 expression.

Abstract

Biliary tract cancer is a major global health issue in cancer-related mortality. Therapeutic options are limited, and cisplatin-based treatment schedules represent the mainstay of first-line therapeutic strategies. Although the gain of survival by the addition of cisplatin to gemcitabine is moderate, acquired cisplatin resistance frequently leads to treatment failures with mechanisms that are still poorly understood. Epithelial–mesenchymal transition (EMT) is a dynamic process that changes the shape, function, and gene expression pattern of biliary tract cancer cells. In this study, we explored the influence of the EMT-regulating miR-200c-3p on cisplatin sensitivity in biliary tract cancer cells. Using gain of function experiments, we demonstrated that miR-200c-3p regulates epithelial cell markers through the downregulation of the transcription factor ZEB1. MiR-200c-3p upregulation led to a decreased sensitivity against cisplatin, as observed in transient overexpression models as well as in cell lines stably overexpressing miR-200c-3p. The underlying mechanism seems to be independent of miR-200c-3p’s influence on ZEB1 expression, as ZEB1 knockdown resulted in the opposite effect on cisplatin resistance, which was abolished when ZEB1 knockdown and miR-200c-3p overexpression occurred in parallel. Using a gene panel of 40 genes that were previously associated with cisplatin resistance, two (Dual Specificity Phosphatase 16 (DUSP16) and Stratifin (SFN)) were identified as significantly (>2 fold, p-value < 0.05) up-regulated in miR-200c-3p overexpressing cells. In conclusion, miR-200c-3p might be an important contributor to cisplatin resistance in biliary tract cancer, independently of its interaction with ZEB1.

Dihydroartemisinin Sensitizes Esophageal Squamous Cell Carcinoma to Cisplatin by Inhibiting Sonic Hedgehog Signaling

Platinum-based regimens have been routinely used in the clinical treatment of patients with esophageal squamous cell carcinoma (ESCC). However, administration of these drugs is frequently accompanied by drug resistance. Revealing the underlying mechanisms of the drug resistance and developing agents that enhance the sensitivity to platinum may provide new therapeutic strategies for the patients. In the present study, we found that the poor outcome of ESCC patients receiving platinum-based regimens was associated with co-expression of Shh and Sox2. The sensitivity of ESCC cell lines to cisplatin was related to their activity of Shh signaling. Manipulating of Shh expression markedly changed the sensitivity of ESCC cells to platinum. Continuous treatment with cisplatin resulted in the activation of Shh signaling and enhanced cancer stem cell-like phenotypes in ESCC cells. Dihydroartemisinin (DHA), a classic antimalarial drug, was identified as a novel inhibitor of Shh pathway. Treatment with DHA attenuated the cisplatin-induced activation of the Shh pathway in ESCC cells and synergized the inhibitory effect of cisplatin on proliferation, sphere and colony formation of ALDH-positive ESCC cells in vitro and growth of ESCC cell-derived xenograft tumors in vivo. Taken together, these results demonstrate that the Shh pathway is an important player in cisplatin-resistant ESCC and DHA acts as a promising therapeutic agent to sensitize ESCC to cisplatin treatment.

14-3-3 σ: A potential biomolecule for cancer therapy

As more studies have focused on the function of 14-3-3 proteins, their role in tumor progression has gradually improved. In the 14-3-3 protein family, 14-3-3σ is the protein that is most associated with tumor occurrence and development. In some malignancies, 14-3-3σ acts as a tumor suppressor via p53 and tumor suppressor genes. In most tumors, 14-3-3σ overexpression increases resistance to chemotherapy and radiotherapy and mediates the G2-M checkpoint after DNA damage. Although 14-3-3σ overexpression has been closely associated with poorer prognosis in pancreatic, gastric and colorectal cancer, its role in gallbladder and nasopharyngeal cancer remains less clear. As such, the function of 14-3-3σ in specific cancer types needs to be further clarified. It has been hypothesized that a role may be related to its molecular chaperone function combined with various protein ligands. In this review, we examine the role of 14-3-3σ in tumor development and drug resistance. We discuss the potential of targeting 14-3-3σ regulators in cancer therapy and treatment.

Advances of proteomics technologies for multidrug-resistant mechanisms

Multidrug resistance (MDR) is a vital issue in cancer treatment. Drug resistance can be developed through a variety of mechanisms, including increased drug efflux, activation of detoxifying systems and DNA repair mechanisms, and escape of drug-induced apoptosis. Identifying the exact mechanism related in a particular case is a difficult task. Proteomics is the large-scale study of proteins, particularly their expression, structures and functions. In recent years, comparative proteomic methods have been performed to analyze MDR mechanisms in drug-selected model cancer cell lines. In this paper, we review the recent developments and progresses by comparative proteomic approaches to identify potential MDR mechanisms in drug-selected model cancer cell lines, which may help understand and design chemical sensitizers.

Molecular carcinogenesis in equine penile cancer: A potential animal model for human penile cancer

OBJECTIVES

To evaluate the expression of COX-2, E-cadherin, vimentin, 14-3-3σ, and Phosphatase and tensin homolog (PTEN) tumor-related proteins in equine penile papillomas (ePP) and squamous cell carcinomas (ePSCC), the occurrence of epithelial-mesenchymal transition (EMT) at the invasion front (IF) and compare our findings with current knowledge on human penile squamous cell carcinoma (hPSCC).

MATERIAL AND METHODS

We analyzed, by immunohistochemistry in 45 equine penile proliferative epithelial lesions, the expression of COX-2, E-cadherin, vimentin, 14-3-3σ, and PTEN using monoclonal antibodies. Tumors were histopathologically classified as well-differentiated or poorly differentiated using the IF grading scheme. Semiquantitative analysis was performed to determine down or up-regulation of the proteins and association with histopathological characteristics were statistically investigated using Mann-Whitney U test and/or Spearman's tests.

RESULTS

COX-2 was neo-expressed in 86.6% of the cases and expression progressively increased from ePP to ePSCC (P = 0.0003) and from well to poorly differentiated (P = 0.033). High COX-2 expression was associated with a high mitotic index (MI) (P = 0.026). In contrast to normal epidermis, ePSCC had very low E-cadherin expression in 64% of the cases (P = 0.0005). Vimentin was neo-expressed in 65% of poorly differentiated ePSCC at the IF indicating EMT. Cytoplasmic 14-3-3σ protein expression was reduced in 42% of the ePSCC and additionally, nuclear expression of 14-3-3σ in neoplastic keratinocytes and in the cytoplasm of stromal fibroblasts at the IF was features only found in ePSCC. PTEN protein showed a tendency to be decreased or lost in ePSCC.

CONCLUSIONS

Our study provides evidence of molecular abnormalities in ePSCC similar to those reported for human PSCC. The occurrence of EMT at the IF is a common event in ePSCC. Naturally occurring ePSCC could serve as a valuable preclinical animal model to explore upcoming therapeutic options for hPSCC.

iTRAQ-based quantitative proteomic analysis of differentially expressed proteins in chemoresistant nasopharyngeal carcinoma

Nasopharyngeal carcinoma (NPC) is a highly prevalent disease in Southeast Asia. The disease is typically diagnosed in the later stages, and chemotherapy resistance often causes treatment failure. To investigate the underlying mechanisms of drug resistance, we searched for chemoresistant-associated proteins in NPC and drug-resistant NPC cell lines using isobaric tags for relative and absolute quantitation combined with nano liquid chromatography-tandem mass spectrometry. The chemoresistant NPC cell lines CNE1DDP and CNE2DDP were resistant to 1 mg/L cisplatin, had resistant indexes of 4.58 and 2.63, respectively, and clearly grew more slowly than the NPC cell lines CNE1 and CNE2. Using three technical replicates, we identified 690 nonredundant proteins, 56 of which were differentially expressed in both groups of cell lines (CNE1 vs. CNE1DDP and CNE2 vs. CNE2DDP). Gene Ontology, KEGG pathway, and miRNA analyses and protein-protein interactions of differentially expressed proteins showed that proteins TRIM29, HSPB1, CLIC1, ANXA1, and STMN1, among others, may play a role in the mechanisms of chemoresistance in clinical therapy. The chemotherapy-resistant proteomic profiles obtained may allow the identification of novel biomarkers for early detection of chemoresistance in NPC and other cancers.

Preclinical Study of Novel Curcumin Analogue SSC-5 Using Orthotopic Tumor Xenograft Model for Esophageal Squamous Cell Carcinoma

Purpose

Tumor xenograft model is an indispensable animal cancer model. In esophageal squamous cell carcinoma (ESCC) research, orthotopic tumor xenograft model establishes tumor xenograft in the animal esophagus, which allows the study of tumorigenesis in its native microenvironment.

Materials and Methods

In this study,we described two simple and reproducible methods to develop tumor xenograft at the cervical or the abdominal esophagus in nude mice by direct injection of ESCC cells in the esophageal wall.

Results

In comparing these two methods, the cervical one presented with more clinically relevant features, i.e., esophageal stricture, body weight loss and poor survival. In addition, the derived tumor xenografts accompanied a rapid growth rate and a high tendency to invade into the surrounding structures. This model was subsequently used to study the anti-tumor effect of curcumin, which is known for its potential therapeutic effects in various diseases including cancers, and its analogue SSC-5. SSC-5 was selected among the eight newly synthesized curcumin analogues based on its superior anti-tumor effect demonstrated in an MTT cell proliferation assay and its effects on apoptosis induction and cell cycle arrest in cultured ESCC cells. Treatment of orthotopic tumor-bearing mice with SSC-5 resulted in an inhibition in tumor growth and invasion.

Conclusion

Taken together, we have established a clinically relevant orthotopic tumor xenograft model that can serve as a preclinical tool for screening new anti-tumor compounds, e.g., SSC-5, in ESCC.

The dual role and therapeutic potential of high-mobility group box 1 in cancer

High-mobility group box 1 (HMGB1) is an abundant protein in most eukaryocytes. It can bind to several receptors such as advanced glycation end products (RAGE) and Toll-like receptors (TLRs), in direct or indirect way. The biological effects of HMGB1 depend on its expression and subcellular location. Inside the nucleus, HMGB1 is engaged in many DNA events such as DNA repair, transcription, telomere maintenance, and genome stability. While outside the nucleus, it possesses more complicated functions, including regulating cell proliferation, autophagy, inflammation and immunity. During tumor development, HMGB1 has been characterized as both a pro- and anti-tumoral protein by either promoting or suppressing tumor growth, proliferation, angiogenesis, invasion and metastasis. However, the current knowledge concerning the positive and negative effects of HMGB1 on tumor development is not explicit. Here, we evaluate the role of HMGB1 in tumor development and attempt to reconcile the dual effects of HMGB1 in carcinogenesis. Furthermore, we would like to present current strategies targeting against HMGB1, its receptor or release, which have shown potentially therapeutic value in cancer intervention.

ECRG2 enhances the anti-cancer effects of cisplatin in cisplatin-resistant esophageal cancer cells via upregulation of p53 and downregulation of PCNA

AIM

To explore the anti-tumor effects of esophageal cancer-related gene 2 (ECRG2) in combination with cisplatin (DDP) in DDP-resistant esophageal cancer cells (EC9706/DDP).

METHODS

A drug-resistant cell model was established, with EC9706/DDP cells being treated with ECRG2 and/or DDP. Cell viability was examined by MTT assay. The rate of cell apoptosis was determined by flow cytometry. The mRNA expression levels of proliferating cell nuclear antigen (PCNA), metallothionein (MT), and p53 were determined by RT-PCR and PCNA, while MT and p53 protein expression levels were determined by western blotting.

RESULTS

The anti-proliferative effect of ECRG2 in combination with DDP was superior when compared to ECRG2 or DDP alone. The inhibition rate for the combination reached its peak (51.33%) at 96 h. The early apoptotic rates of the control, ECRG2 alone, DDP alone, and ECRG2 plus DDP groups were 5.71% ± 0.27%, 12.68% ± 0.61%, 14.15% ± 0.87%, and 27.96% ± 0.36%, respectively. Although all treatment groups were significantly different from the control group (P < 0.05), the combination treatment of ECRG2 plus DDP performed significantly better when compared to either ECRG2 or DDP alone (P < 0.05). The combination of ECRG2 and DDP significantly upregulated p53 mRNA and protein levels and downregulated PCNA mRNA and protein levels compared to ECRG2 or DDP alone (P < 0.05). However, no changes were seen in the expression of MT mRNA or protein.

CONCLUSION

ECRG2 in combination with DDP can inhibit viability and induce apoptosis in esophageal cancer DDP-resistant cells, possibly via upregulation of p53 expression and downregulation of PCNA expression. These findings suggest that the combination of ECRG2 and DDP may be a promising strategy for the clinical treatment of esophageal cancers that are resistant to DDP.