5396

PRRX1

Thyroid carcinoma is the most common endocrine malignancy, and papillary thyroid carcinoma represents the most common thyroid cancer. Papillary thyroid carcinomas that invade locally or metastasize are associated with a poor prognosis. We found that, during epithelial-mesenchymal transition (EMT) induced by transforming growth factor-beta1 (TGF-beta1), papillary thyroid carcinoma cells acquired increased cancer stem cell-like features and the transcription factor paired-related homeobox protein 1 (PRRX1; alias PRX-1), a newly identified EMT inducer, was markedly up-regulated. miR-146b-5p was also transiently up-regulated during EMT, and in siRNA experiments miR-146b-5p had an inhibitory role on cell proliferation and invasion during TGF-beta1-induced EMT. We conclude that papillary thyroid carcinoma tumor cells exhibit increased cancer stem cell-like features during TGF-beta1-induced EMT, that miR-146b-5p has a role in cell proliferation and invasion, and that PRRX1 plays an important role in papillary thyroid carcinoma EMT and disease progression.CI - Copyright (c) 2014 American Society for Investigative Pathology. Published by Elsevier Inc. All rights reserved.

Carcinoma cells hijack the epithelial-mesenchymal transition (EMT) for tumor dissemination. Paired-related homeobox 1 (PRRX1) has been identified as a new EMT inducer. However, the function of PRRX1 in gastric cancer has not been elucidated. In this study, we observed that PRRX1 expression levels were upregulated and positively correlated with metastasis and EMT markers in human gastric cancer specimens. PRRX1 overexpression had distinct effects on the cell morphology, proliferation, migration and invasion of BGC823 and SGC7901 gastric cancer cells both in vitro and in xenografts. PRRX1 overexpression resulted in the regulation of the EMT molecular markers N-cadherin, E-cadherin and vimentin as well as the levels of intranuclear beta-catenin and the Wnt/beta-catenin target c-Myc. Furthermore, the inhibition of the Wnt/beta-catenin pathway by XAV939 offset the effects of PRRX1 overexpression. These findings demonstrate that PRRX1 promotes EMT in gastric cancer cells through the activation of Wnt/beta-catenin signaling and that PRRX1 upregulation is closely correlated with gastric cancer metastasis.

The two major isoforms of the paired-related homeodomain transcription factor 1 (Prrx1), Prrx1a and Prrx1b, are involved in pancreatic development, pancreatitis, and carcinogenesis, although the biological role that these isoforms serve in the systemic dissemination of pancreatic ductal adenocarcinoma (PDAC) has not been investigated. An epithelial-mesenchymal transition (EMT) is believed to be important for primary tumor progression and dissemination, whereas a mesenchymal-epithelial transition (MET) appears crucial for metastatic colonization. Here, we describe novel roles for both isoforms in the metastatic cascade using complementary in vitro and in vivo models. Prrx1b promotes invasion, tumor dedifferentiation, and EMT. In contrast, Prrx1a stimulates metastatic outgrowth in the liver, tumor differentiation, and MET. We further demonstrate that the switch from Prrx1b to Prrx1a governs EMT plasticity in both mouse models of PDAC and human PDAC. Last, we identify hepatocyte growth factor ( HGF) as a novel transcriptional target of Prrx1b. Targeted therapy of HGF in combination with gemcitabine in a preclinical model of PDAC reduces primary tumor volume and eliminates metastatic disease. Overall, we provide new insights into the isoform-specific roles of Prrx1a and Prrx1b in primary PDAC formation, dissemination, and metastatic colonization, allowing for novel therapeutic strategies targeting EMT plasticity.CI - (c) 2016 Takano et al.; Published by Cold Spring Harbor Laboratory Press.

Triple-negative breast cancer (TNBC) is a highly aggressive breast cancer subtype that lacks effective targeted therapies. The epithelial-to-mesenchymal transition (EMT) is a key contributor in the metastatic process. In this study, we found that miR-655 was down-regulated in TNBC, and its expression levels were associated with molecular-based classification and lymph node metastasis in breast cancer. These findings led us to hypothesize that miR-655 overexpression may inhibit EMT and its associated traits of TNBC. Ectopic expression of miR-655 not only induced the up-regulation of cytokeratin and decreased vimentin expression but also suppressed migration and invasion of mesenchymal-like cancer cells accompanied by a morphological shift towards the epithelial phenotype. In addition, we found that miR-655 was negatively correlated with Prrx1 in cell lines and clinical samples. Overexpression of miR-655 significantly suppressed Prrx1, as demonstrated by Prrx1 3'-untranslated region luciferase report assay. Our study demonstrated that miR-655 inhibits the acquisition of the EMT phenotype in TNBC by down-regulating Prrx1, thereby inhibiting cell migration and invasion during cancer progression.CI - (c) 2016 The Authors. Journal of Cellular and Molecular Medicine published by John Wiley & Sons Ltd and Foundation for Cellular and Molecular Medicine.

Triple-negative breast cancer (TNBC) is a highly aggressive tumour subtype associated with poor prognosis. The mechanisms involved in TNBC progression remains largely unknown. To date, there are no effective therapeutic targets for this tumour subtype. Paired-related homeobox 1b (Prrx1b), one of major isoforms of Prrx1, has been identified as a new epithelial-mesenchymal transition (EMT) inducer. However, the function of Prrx1b in TNBC has not been elucidated. In this study, we found that Prrx1b was significantly up-regulated in TNBC and associated with tumour size and vascular invasion of breast cancer. Silencing of Prrx1b suppressed the proliferation, migration and invasion of basal-like cancer cells. Moreover, silencing of Prrx1b prevented Wnt/beta-catenin signaling pathway and induced the mesenchymal-epithelial transition (MET). Taken together, our data indicated that Prrx1b may be an important regulator of EMT in TNBC cells and a new therapeutic target for interventions against TNBC invasion and metastasis.CI - (c) 2016 The Authors. Journal of Cellular and Molecular Medicine published by John Wiley & Sons Ltd and Foundation for Cellular and Molecular Medicine.

BACKGROUND: Accumulating evidence supports the hypothesis that cancer stem cells (CSCs) are essential for cancer initiation, metastasis and drug resistance. However, the functional association of gastric CSC markers with stemness and epithelial-mesenchymal transition (EMT) signature genes is unclear. METHODS: qPCR was performed to measure the expression profiles of stemness and EMT signature genes and their association with putative CSC markers in gastric cancer tissues, cancer cell lines and sphere cells. Western blot analysis was used to confirm the results of the transcript analysis. Cell proliferation, cell migration, drug resistance and sphere cell growth assays were conducted to measure the expansion and invasion abilities of the cells. tumor xenograft experiments were performed in NOD/SCID mice to test cell stemness in vivo. Flow cytometry and immunofluorescence staining were used to analyze cell subpopulations. RESULTS: The expression of LGR5 was strikingly up-regulated in sphere cells but not in cancer tissues or parental adherent cells. The up-regulation of LGR5 was also positively associated with stemness regulators (NANOG, OCT4, SOX2, and AICDA) and EMT inducers (PRRX1, TWIST1, and BMI1). In addition, sphere cells exhibited up-regulated vimentin and down-regulated E-cadherin expression. Using gene-specific primers, we found that the NANOG expression primarily originates from the retrogene NANOGP8. Western blot analysis showed that the expression of both LGR5 and NANOG is significantly higher in sphere cells. LGR5 over-expression significantly enhanced sphere cell growth, cell proliferation, cell migration and drug resistance in MGC803 cells. tumor xenografts in nude mice showed that sphere cells are at least 10 times more efficient at tumor initiation than adherent cells. Flow cytometry analysis showed that ~20% of sphere cells are LGR5+/CD54+, but only ~3% of adherent cells are Lgr5+/CD54+. Immunofluorescence staining supports the above results. CONCLUSION: The LGR5-expressing fraction of CD54+ cells represents gastric cancer CSCs, in which LGR5 is closely associated with stemness and EMT core genes, and NANOG expression is mainly contributed by the retrogene NANOGP8. Sphere cells are the best starting materials for the characterization of CSCs.

BACKGROUND: Dormancy is one characteristic of cancer cells to make patients remain asymptomatic before metastasis and relapse, which is closely related to the survival rate of cancer patients, including head and neck squamous cell carcinoma (HNSCC). PRRX1 has previously been implicated in the invasion and metastasis of the epithelial-mesenchymal transition (EMT) process in different types of human carcinoma. However, whether PRRX1 can regulate cancer dormancy and its reactivation, leading to the migration and invasion of HNSCC cells, remains elusive. The aim of this study was to determine the role of PRRX1 in cellular phenotype plasticity and cancer dormancy of HNSCC cells and its association with miRNAs in HNSCC. METHODS: The expression of PRRX1 was detected by immunohistochemical staining in primary HNSCC samples and the metastatic lymph nodes. Meanwhile, the role of PRRX1 and its relationship with miR-642b-3p and EMT in cellular phenotype plasticity and cancer dormancy of HNSCC were investigated in vitro and in vivo. RESULTS: PRRX1 was significantly higher at the invasive front of HNSCC samples compared with the metastatic lymph nodes, and such switch process was accompanied by the cellular phenotype plasticity and cell dormancy activation. In HNSCC cell lines, PRRX1 positively promoted the expression of known EMT inducers and cooperated with activated TGF-beta1 to contribute to EMT and migration and invasion of HNSCC cells. Then, we found that overexpression of miR-642b-3p, one of the most significantly downregulated miRNAs in PRRX1-overexpressed cells, significantly reduced the migration and invasion, and increased cell proliferation and apoptosis. And miR-642b-3p restoration reversed PRRX1-induced cell dormancy and EMT of HNSCC cells through TGF-beta2 and p38. Finally, we demonstrated that overexpressed PRRX1 was closely correlated with miR-642b-3p downregulation and the upregulation of TGF-beta2 and p38 in a xenograft model of HNSCC. CONCLUSIONS: Our findings showed that PRRX1 may be one of the main driving forces for the cellular phenotype plasticity and tumor dormancy of HNSCC. Therefore, we can raise the possibility that EMT may help to keep cancer cell in dormant state and mesenchymal-epithelial transition may resurge dormancy in HNSCC.CI - Copyright (c) 2018 The Authors. Published by Elsevier Inc. All rights reserved.