Five-year survival rate of esophageal squamous cell carcinoma (ESCC) patients treated with radiotherapy is <20%. Our study aimed to investigate whether cancer-associated fibroblasts (CAFs), one major component of tumor microenvironment, were involved in tumor radioresistance in ESCC. By use of human chemokine/cytokine array, human chemokine CXCL1 was found to be highly expressed in CAFs compared with that in matched normal fibroblasts. Inhibition of CXCL1 expression in CAFs significantly reversed CAF-conferred radioresistance in vitro and in vivo. CAF-secreted CXCL1 inhibited the expression of reactive oxygen species (ROS)-scavenging enzyme superoxide dismutase 1, leading to increased ROS accumulation following radiation, by which DNA damage repair was enhanced and the radioresistance was mediated. CAF-secreted CXCL1 mediated the radioresistance also by activation of Mek/Erk pathway. The cross talk of CAFs and ESCC cells induced CXCL1 expression in an autocrine/paracrine signaling loop, which further enhanced tumor radioresistance. Together, our study highlighted CAF-secreted CXCL1 as an attractive target to reverse tumor radioresistance and can be used as an independent prognostic factor of ESCC patients treated with chemoradiotherapy.

Background Evaluating clinical outcome prior to concurrent chemoradiotherapy remains challenging for oesophageal squamous cell carcinoma (OSCC) as traditional prognostic markers are assessed at the completion of treatment. Herein, we investigated the potential of using sub-region radiomics as a novel tumour biomarker in predicting overall survival of OSCC patients treated by concurrent chemoradiotherapy. Methods Independent patient cohorts from two hospitals were included for training ( n = 87) and validation ( n = 46). Radiomics features were extracted from sub-regions clustered from patients' tumour regions using K-means method. The LASSO regression for ‘Cox’ method was used for feature selection. The survival prediction model was constructed based on the sub-region radiomics features using the Cox proportional hazards model. The clinical and biological significance of radiomics features were assessed by correlation analysis of clinical characteristics and copy number alterations(CNAs) in the validation dataset. Findings The overall survival prediction model combining with seven sub-regional radiomics features was constructed. The C-indexes of the proposed model were 0.729 (0.656–0.801, 95% CI) and 0.705 (0.628–0.782, 95%CI) in the training and validation cohorts, respectively. The 3-year survival receiver operating characteristic (ROC) curve showed an area under the ROC curve of 0.811 (0.670–0.952, 95%CI) in training and 0.805 (0.638–0.973, 95%CI) in validation. The correlation analysis showed a significant correlation between radiomics features and CNAs. Interpretation The proposed sub-regional radiomics model could predict the overall survival risk for patients with OSCC treated by definitive concurrent chemoradiotherapy. Fund This work was supported by the Zhejiang Provincial Foundation for Natural Sciences, National Natural Science Foundation of China.

Radiotherapy is a primary treatment modality for esophageal squamous cell carcinoma (ESCC). However, most of patients benefited little from radiotherapy due to refractory radioresistance. We found that WISP1, a downstream target gene of Wnt/β-catenin pathway, was re-expressed in 67.3 % of ESCC patients as an oncofetal gene. Expression of WISP1 predicted prognosis of ESCC patients treated with radiotherapy. Overall survival in WISP1-positive patients was significantly poorer than in WISP1-negative patients. Serum concentration of WISP1 after radiotherapy reversely correlated with relapse-free survival. Gain and loss of function studies confirmed that WISP1 mediated radioresistance both in esophageal squamous cancer cells and in xenograft tumor models. Further studies revealed that WISP1 contributed to radioresistance primarily by repressing irradiation-induced DNA damage and activating PI3K kinase. LncRNA BOKAS was up-regulated following radiation and promoted WISP1 expression and resultant radioresistance. Furthermore, WISP1 facilitated its own expression in response to radiation, creating a positive feedback loop and increased radioresistance. Our study revealed WISP1 as a potential target to overcome radioresistance in ESCC.

Previous studies on the mechanisms underlying ESCC (esophageal squamous cell carcinoma) chemoresistance only focused on tumor cells while tumor microenvironment has been completely ignored. Our study aimed to clarify the effect of CAFs (cancer-associated fibroblasts), one major component of tumor microenvironment, on the chemoresistance of ESCC. By primary culture, two pairs of CAFs and matched NFs (normal fibroblasts) were isolated from tumor tissues of ESCC patients and matched normal esophageal epithelial tissues, respectively. The association of CAFs and chemoresistance was assessed in esophageal carcinoma cells, in xenograft tumor models and in clinical specimens of ESCC patients. We found CAFs conferred ESCC cells significant resistance to several common chemotherapeutic drugs including cisplatin, taxol, irinotecan (CPT-11), 5-fluorouracil (5-Fu), carboplatin, docetaxel, pharmorubicin, and vincristine. Mechanism studies revealed that blockage of CAFs-secreted TGFβ1 signaling by its receptor TGFβR1 inhibitor LY2157299 significantly reversed the chemoresistance in vitro and in vivo. Furthermore, the crosstalk of CAFs and ESCC cells enhanced the expression and activation of FOXO1, a member of the forkhead transcription factors in the O-box sub-family, inducing TGFβ1 expression in an autocrine/paracrine signaling loop. In 130 ESCC patients, the expression of TGFβ1 in CAFs was significantly associated with overall survival of patients treated with chemoradiotherapy. Together, our study highlighted TGFβ1 expressed in CAFs as an attractive target to reverse tumor chemoresistance, and can be used as an independent prognostic factor of ESCC patients treated with chemoradiotherapy. © 2016 Wiley Periodicals, Inc.

The efficacy of radiotherapy, one major treatment modality for esophageal squamous cell carcinoma (ESCC) is severely attenuated by radioresistance. Epithelial-to-mesenchymal transition (EMT) is a cellular process that determines therapy response and tumor progression. However, whether EMT is induced by ionizing radiation and involved in tumor radioresistance has been less studied in ESCC. Using multiple fractionated irradiation, the radioresistant esophageal squamous cancer cell line KYSE-150R had been established from its parental cell line KYSE-150. We found KYSE-150R displayed a significant EMT phenotype with an elongated spindle shape and down-regulated epithelial marker E-cadherin and up-regulated mesenchymal marker N-cadherin in comparison with KYSE-150. Furthermore, KYSE-150R also possessed some stemness-like properties characterized by density-dependent growth promotion and strong capability for sphere formation and tumorigenesis in NOD-SCID mice. Mechanical studies have revealed that WISP1, a secreted matricellular protein, is highly expressed in KYSE-150R and mediates EMT-associated radioresistance both in ESCC cells and in xenograft tumor models. Moreover, WISP1 has been demonstrated to be closely associated with the EMT phenotype observed in ESCC patients and to be an independent prognosis factor of ESCC patients treated with radiotherapy. Our study highlighted WISP1 as an attractive target to reverse EMT-associated radioresistance in ESCC and can be used as an independent prognostic factor of patients treated with radiotherapy.