Silencing Snail Reverses Epithelial-Mesenchymal Transition and Increases Radiosensitivity in Hypopharyngeal Carcinoma

Purpose

Radioresistance in response to radiotherapy leads to cancer recurrence and poor survival in hypopharyngeal carcinoma patients. Previous studies indicate that ionizing radiation (IR) can induce epithelial–mesenchymal transition (EMT) that promotes the radioresistance, migration and invasiveness of tumors. The aim of this study was to explore the role of Snail in EMT and acquired radioresistance in hypopharyngeal carcinoma.

Methods

Radioresistance human hypopharyngeal carcinoma cells (FaduRR) were previously established from the Fadu cell line. Radiosensitivity was measured by colony forming assay. Western blot and Quantitative real-time PCR were used to detect the expression of EMT phenotypes and AKT/GSK-3β/Snail signaling pathway related proteins in Fadu+4Gy and FaduRR cells. Transwell and wound-healing assays were used to measure cell migration and invasiveness. EMT-related proteins and Snail expression were assessed in 80 hypopharyngeal carcinoma patient samples from radiosensitive and radioresistance groups using immunohistochemistry. Snail was silenced to evaluate its effects on EMT, radioresistance, migration, and invasiveness of FaduRR cells.

Results

The molecular characteristics of EMT were observed following radiation treatment, with migration, invasiveness and radioresistance enhanced in Fadu+4Gy and FaduRR cells. Moreover, we demonstrated that IR-induced EMT by activating the AKT/GSK-3β/Snail signaling pathway and that Snail silencing reversed EMT and attenuated radioresistance in FaduRR cells. Significant differences in EMT-related proteins and Snail expression were observed between radiosensitive and resistant group.

Conclusion

We demonstrate that IR can trigger EMT and enhance the migration, invasiveness, and radioresistance of FaduRR cells through the AKT/GSK-3β/Snail axis. Snail silencing could attenuate these effects and represents a novel therapeutic target for EMT-induced radioresistance in hypopharyngeal carcinoma.

E-cadherin and Snail Immunoexpression in Colorectal Adenocarcinomas

Epithelial-mesenchymal transition (EMT) is a fundamental process which governs invasiveness. E-cadherin plays a major role in development, organogenesis and tissue formation, but also in tumor progression. Snail is a transcription factor described as a direct repressor of E-cadherin during development and in carcinogenesis. In this study we analyzed E-cadherin and Snail immunoexpression in 47 cases of colorectal adenocarcinoma (CRC) in comparison with some histopathological prognostic factors. The majority of cases were G2 tumors in stages II and III, with vascular and perineural invasion. All cases showed positive cytoplasmic signal for E-cadherin and Snail. E-cadherin reactions were intense with the highest composite score (CS) values in CRC G1. CS values of E-cadherin decreased with the advancement in tumor stage and the association with vascular and perineural invasion was statistically significant. Snail immunoreaction was intense with the highest values of CS in CRC G3, being more evident with the increase of tumor staging, aspect which was statistically significant. CS and Snail association demonstrated a statistically significant aspect related to vascular invasion. We found a negative linear correlation of E-cadherin and Snail expression. The obtained results indicate the implication of Snail and E-cadherin in EMT of CRC, aspect which is useful in the evaluation and stratification of patients with CRC for the targeted specific therapy.

Emodin Inhibits Colon Cancer Cell Invasion and Migration by Suppressing Epithelial-Mesenchymal Transition via the Wnt/β-Catenin Pathway

Colon cancer (CC) is the third most common cancer worldwide. Emodin is an anthraquinone-active substance that has the ability to affect tumor progression. Our study aims to explore the effects and the relevant mechanism of emodin on the invasion and migration of CC in vitro and in vivo. In our study, we found that emodin inhibited the invasion and migration abilities of RKO cells and decreased the expression of matrix metalloproteinase-7 (MMP-7), MMP-9, and vascular endothelial growth factor (VEGF) in a dose-dependent manner. Further research suggested that emodin inhibited EMT by increasing the mRNA level of E-cadherin and decreasing the expression of N-cadherin, Snail, and β-catenin. Emodin also significantly inhibited the activation of the Wnt/β-catenin signaling pathway by downregulating the expression of related downstream target genes, including TCF4, cyclin D1, and c-Myc. A Wnt/β-catenin signaling pathway agonist abolished the effect of emodin on EMT and cell mobility, suggesting that emodin exerted its regulating role through the Wnt/β-catenin pathway. The CC xenograft model was established to study the antitumor efficiency of emodin in vivo. The in vivo study further demonstrated that emodin (40 mg/kg) suppressed tumor growth by inhibiting EMT via the Wnt/β-catenin signaling pathway in vivo. Taken together, we suggest that emodin inhibits the invasion and migration of CC cells in vitro and in vivo by blocking EMT, which is related with the inhibition of the Wnt/β-catenin signaling pathway.

Isolation and identification of chemotherapy-enriched sphere-forming cells from a patient with gastric cancer

Gastric cancer (GC) is the third and fifth cause of cancer-associated mortality for men and women throughout the world, respectively. Despite the use of surgery and chemotherapy for GC therapy, there are no efficient therapeutic protocols for it to date. Cancer stem cells (CSCs) due to their pivotal role in tumor initiation, growth, progression, invasion, distant metastasis, recurrence and resistance to anticancer drugs are very appealing targets for cancer therapies. Here, we isolated and identified CSCs from a chemotherapy-treated patient. Small subpopulation of dissociated cells after tissue digestion formed spheroid colonies in serum-free media under the non-adherent condition. These spheroid colonies differentiated into epithelial like cells in serum-containing medium. Few sphere-forming cells carried CD44 and CD54 markers overexpressed DLL4 that is responsible for tumor growth and angiogenesis. Subcutaneous injections of sphere-forming cells in different passages conferred tumorigenicity in nude mice. Sphere-forming cells upregulated CD44 polymorphisms CD44v3, -v6, and -v8 -10, stemness factors OCT4, SOX2, SALL4 and Cripto-1, self-renewal molecules IHh, Wnt, β-catenin and BMI1, and epithelial mesenchymal transition (EMT) markers Twist1 and Snail1 in vitro and in vivo. Moreover, these cells similar to sphere-forming cells isolated from a chemotherapy-free patient expressed Oct-4 and β-catenin proteins. However, the Twist1 protein was only expressed by sphere-forming cells derived from the chemotherapy-treated patient. Thus, these cells have all the characteristics of stationary and migratory CSCs, including tumorigenicity, self-renewal, pluripotency, invasion and metastasis. Taken together, targeting chemotherapy-enriched CSCs as chemo-resistance cells observed in GC patients can provide more effective therapeutic strategies compared to untreated patients.

Fibronectin 1 promotes migration and invasion of papillary thyroid cancer and predicts papillary thyroid cancer lymph node metastasis

Lymph node metastasis (LNM) is common in papillary thyroid cancer (PTC), and is an indicator of recurrence. The detailed molecular mechanism of LNM in PTC has not been well described. This study aimed to investigate the role of fibronectin 1 in PTC LNM and its clinical relevance. The expression of fibronectin 1 was confirmed in PTC tissues and cell lines. A correlation analysis was conducted and a receiver-operating characteristic curve obtained. The effect of fibronectin 1 on the proliferation of PTC cell lines was performed using a colony-formation assay and Cell Counting Kit 8. Cell-cycle analysis was performed with a flow-cytometry assay. Migration and invasion ability were evaluated by transwell and wound-healing assays. Fibronectin 1 was overexpressed in metastasized PTC. Overexpressed fibronectin 1 was positively correlated with PTC LNM. Receiver-operating characteristic analysis showed that the diagnostic accuracy of fibronectin 1 was 81.1%, with sensitivity of 80% and specificity of 82%. Overexpression of fibronectin 1 promoted proliferation, migration, and invasion in PTC. Fibronectin 1 plays a critical role in PTC metastasis by modulating the proliferation, migration, and invasion ability of PTC cells, and it is a valuable diagnostic biomarker for predicting PTC LNM.