Targeted intervention of eIF4A1 inhibits EMT and metastasis of pancreatic cancer cells via c-MYC/miR-9 signaling

Background Owing to the lack of effective treatment options, early metastasis remains the major cause of pancreatic ductal adenocarcinoma (PDAC) recurrence and mortality. However, the molecular mechanism of early metastasis is largely unknown. We characterized the function of eukaryotic translation initiation factors (eIFs) in epithelial-mesenchymal-transition (EMT) and metastasis in pancreatic cancer cells to investigate whether eIFs and downstream c-MYC affect EMT and metastasis by joint interference. Methods We used The Cancer Genome Atlas (TCGA) and Genome Tissue Expression (GTEx) databases to analyze eIF4A1 expression in PDAC tissues and further validated the findings with a microarray containing 53 PDAC samples. Expression regulation and pharmacological inhibition of eIF4A1 and c-MYC were performed to determine their role in migration, invasion, and metastasis in pancreatic cancer cells in vitro and in vivo. Results Elevated eIF4A1 expression was positively correlated with lymph node infiltration, tumor size, and indicated a poor prognosis. eIF4A1 decreased E-cadherin expression through the c-MYC/miR-9 axis. Loss of eIF4A1 and c-MYC decreased the EMT and metastasis capabilities of pancreatic cancer cells, whereas upregulation of eIF4A1 attenuated the inhibition of EMT and metastasis induced by c-MYC downregulation. Treatment with the eIF4A1 inhibitor rocaglamide (RocA) or the c-MYC inhibitor Mycro3 either alone or in combination significantly decreased the expression level of EMT markers in pancreatic cancer cells in vitro. However, the efficiency and safety of RocA alone were not inferior to those of the combination treatment in vivo. Conclusion Overexpression of eIF4A1 downregulated E-cadherin expression through the c-MYC/miR-9 axis, which promoted EMT and metastasis of pancreatic cancer cells. Despite the potential feedback loop between eIF4A1 and c-MYC, RocA monotherapy is a promising treatment inhibiting eIF4A1-induced PDAC metastasis.

TMPRSS4 promotes cancer stem–like properties in prostate cancer cells through upregulation of SOX2 by SLUG and TWIST1

Background Transmembrane serine protease 4 (TMPRSS4) is a cell surface–anchored serine protease. Elevated expression of TMPRSS4 correlates with poor prognosis in colorectal cancer, gastric cancer, prostate cancer, non–small cell lung cancer, and other cancers. Previously, we demonstrated that TMPRSS4 promotes invasion and proliferation of prostate cancer cells. Here, we investigated whether TMPRSS4 confers cancer stem–like properties to prostate cancer cells and characterized the underlying mechanisms. Methods Acquisition of cancer stem–like properties by TMPRSS4 was examined by monitoring anchorage-independent growth, tumorsphere formation, aldehyde dehydrogenase (ALDH) activation, and resistance to anoikis and drugs in vitro and in an early metastasis model in vivo. The underlying molecular mechanisms were evaluated, focusing on stemness-related factors regulated by epithelial–mesenchymal transition (EMT)-inducing transcription factors. Clinical expression and significance of TMPRSS4 and stemness-associated factors were explored by analyzing datasets from The Cancer Genome Atlas (TCGA). Results TMPRSS4 promoted anchorage-independent growth, ALDH activation, tumorsphere formation, and therapeutic resistance of prostate cancer cells. In addition, TMPRSS4 promoted resistance to anoikis, thereby increasing survival of circulating tumor cells and promoting early metastasis. These features were accompanied by upregulation of stemness-related factors such as SOX2, BMI1, and CD133. SLUG and TWIST1, master EMT-inducing transcription factors, made essential contributions to TMPRSS4-mediated cancer stem cell (CSC) features through upregulation of SOX2. SLUG stabilized SOX2 via preventing proteasomal degradation through its interaction with SOX2, while TWIST1 upregulated transcription of SOX2 by interacting with the proximal E-box element in the SOX2 promoter. Clinical data showed that TMPRSS4 expression correlated with the levels of SOX2, PROM1, SNAI2, and TWIST1. Expression of SOX2 was positively correlated with that of TWIST1, but not with other EMT-inducing transcription factors, in various cancer cell lines. Conclusions Together, these findings suggest that TMPRSS4 promotes CSC features in prostate cancer through upregulation of the SLUG- and TWIST1-induced stem cell factor SOX2 beyond EMT. Thus, TMPRSS4/SLUG–TWIST1/SOX2 axis may represent a novel mechanism involved in the control of tumor progression.

Targeted Intervention of eIF4A1 Promotes EMT and Metastasis of Pancreatic Cancer Cells through c-MYC/miR-9 Signaling

Background: Due to the lack of effective interference options, early metastasis remains a major cause of pancreatic ductal adenocarcinoma (PDAC) recurrence and mortality. However, the molecular mechanism of early metastasis is largely unknown. We characterize the function of eukaryotic translation initiation factors (eIFs) in Pancreatic cancer cell epithelial mesenchymal-transition (EMT) and metastasis, to investigate whether it is effective to inhibit EMT and metastasis by joint interference of eIFs and downstream c-MYC. Methods: We used the data of The Cancer Genome Atlas (TCGA) and Genome Tissue Expression (GTEx) to analyze the expression level of eIF4A1 in PDAC tissues, and further validated in a microarray containing 53 PDAC samples. Expression regulation and pharmacological inhibition of eIF4A1/c-MYC was performed to determine their role in migration, invasion, and metastasis in pancreatic cancer cells in vitro and in vivo.Results: Elevated expression of eIF4A1 was positively correlated with lymph node infiltration, tumor size, and indicated a poor prognosis. eIF4A1 decreased E-cadherin expression through c-MYC/miR-9 axis. Ablation of eIF4A1 and c-MYC decreased the EMT and metastasis capabilities of pancreatic cancer cells. Upregulation of eIF4A1 could attenuate the inhibition of EMT and metastasis induced by c-MYC downregulation. Single-use of eIF4A1 inhibitor Rocaglamide (RocA) or c-MYC inhibitor Mycro3 and joint intervention all significantly the EMT level of pancreatic cancer cells in vitro. However, the efficiency and safety of RocA single-use were not inferior to joint use in vivo. Conclusion: The results demonstrated that overexpression of eIF4A1 downregulated E-cadherin through c-MYC/miR-9 axis, which promoted EMT and metastasis of pancreatic cancer cells. Despite the potential loop between eIF4A1 and c-MYC existing, RocA single strategy was a promising therapy for the inhibition of eIF4A1 induced PDAC metastasis.

Rapid metastasis of stage IA primary pulmonary high-grade mucoepidermoid carcinoma with a cystic airspace: a case report and reflection

Primary pulmonary high-grade mucoepidermoid carcinoma (MEC) with a cystic airspace is uncommon, and early metastasis is extremely rare. In such cases, however, it is clinically important for clinicians to consider whether the tumor has spread to the lymph nodes through the cystic airspace. A 77-year-old man presented to our hospital with cough and hemoptysis. Chest computed tomography showed a 25-mm-diameter mass with a cystic airspace located in the upper lobe of the left lung. The possibility of malignancy was considered. Without a definitive preoperative diagnosis, left upper lobectomy and mediastinal lymphadenectomy were performed. Histopathological examination revealed the typical histological characteristics of high-grade MEC (stage IA) and no lymph node metastasis. However, lymph node metastasis was found 6 months after surgical resection, and radiochemotherapy was performed. The patient developed widespread metastatic disease 4 months following completion of radiochemotherapy and died 2 months later. Primary pulmonary MEC with a cystic airspace is a rare malignant disease with uncommon imaging findings. Complete surgical resection is the main treatment method for high-grade MEC. In this case, we hypothesize that early metastasis was caused by seeding of tumor cells through the cystic airspace.