RESUMO
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.
Assuntos
Neoplasias Esofágicas/enzimologia , Carcinoma de Células Escamosas do Esôfago/enzimologia , Regulação Enzimológica da Expressão Gênica , Regulação Neoplásica da Expressão Gênica , Proteínas de Neoplasias/biossíntese , Tolerância a Radiação , Proteínas Quinases S6 Ribossômicas 90-kDa/biossíntese , Transdução de Sinais , Animais , Neoplasias Esofágicas/genética , Neoplasias Esofágicas/patologia , Neoplasias Esofágicas/terapia , Carcinoma de Células Escamosas do Esôfago/genética , Carcinoma de Células Escamosas do Esôfago/patologia , Carcinoma de Células Escamosas do Esôfago/terapia , Células HEK293 , Humanos , Camundongos , Proteínas de Neoplasias/genética , Proteínas Quinases S6 Ribossômicas 90-kDa/genética , Fatores de Transcrição/genética , Fatores de Transcrição/metabolismo , Proteínas Supressoras de Tumor/genética , Proteínas Supressoras de Tumor/metabolismo , Ensaios Antitumorais Modelo de XenoenxertoRESUMO
Ectopic lymphoid follicle infiltration is a key event in Hashimoto thyroiditis (HT). Positive regulatory domain zinc finger protein 1 (PRDM1), which is induced by antigen stimulation, can regulate all lymphocyte lineages. Several groups independently demonstrated that human parvovirus B19 (PVB19) is closely associated with HT. Hence, we determined whether PRDM1 is expressed in HT thyroid tissue and whether there is any correlation between PRDM1 expression and PVB19 in the pathogenesis of HT. We detected PRDM1 expression in HT (n = 86), normal thyroid tissue (n = 30), and nontoxic nodular goiter (n = 20) samples using immunohistochemistry. We also detected PVB19 protein in HT samples in a double-blind manner and analyzed the correlation between the 2 proteins using immunofluorescence confocal detection and coimmunoprecipitation. Furthermore, we detected changes of the expression levels of PRDM1 and PVB19 in transfected primary thyroid follicular epithelial cells using real-time quantitative polymerase chain reaction. We found that PRDM1 protein is significantly highly expressed in the injured follicular epithelial cells in HT (83/86 cases) than in normal thyroid cells (0/30 cases) or in nontoxic nodular goiter cells (0/20 cases) (P < .001). In HT, the PRDM1 expression pattern was the same as that of PVB19, whereas PRDM1 and PVB19 were coexistent in the involved epithelial cells. Statistical analysis showed a significant correlation between PRDM1 and PVB19 (P < .001). In addition, primary thyroid epithelial cells also showed PRDM1 up-regulation after PVB19 NS1 transfection. Our findings suggest a previously unrecognized role of PRDM1 and PVB19 in the pathogenesis of HT.