Project description:Paired related homeobox 1 (PRRX1) is a marker of limb bud mesenchymal cells, and deficiency of p53 or Rb in Prrx1-positive cells induces osteosarcoma in several mouse models. However, the regulatory roles of PRRX1 in human osteosarcoma have not been defined. In this study, we performed PRRX1 immunostaining on 35 human osteosarcoma specimens to assess the correlation between PRRX1 level and overall survival. In patients with osteosarcoma, the expression level of PRRX1 positively correlated with poor prognosis or the ratio of lung metastasis. Additionally, we found PRRX1 expression on in 143B cells, a human osteosarcoma line with a high metastatic capacity. Downregulation of PRRX1 not only suppressed proliferation and invasion but also increased the sensitivity to cisplatin and doxorubicin. When 143B cells were subcutaneously transplanted into nude mice, PRRX1 knockdown decreased tumor sizes and rates of lung metastasis. Interestingly, forskolin, a chemical compound identified by Connectivity Map analysis using RNA expression signatures during PRRX1 knockdown, decreased tumor proliferation and cell migration to the same degree as PRRX1 knockdown. These results demonstrate that PRRX1 promotes tumor malignancy in human osteosarcoma.
Project description:Malignant nerve sheath tumors (MPNST) are rare types of malignant soft tissue sarcomas and characterized by high resistance for current chemotherapeutic strategies, including topoisomerase 2a (TOP2A) inhibitor, etoposide. Although the poor therapeutic or severe side effects of etoposide in MPNST patients are demonstrated, novel molecular targets that promote tumor malignancy have not been identified. Previously, we reported that paired related-homeobox 1 (PRRX1) serves as a malignant factor in human osteosarcoma. Here, we found that expression level of PRRX1 in tumor tissues, especially sarcomas, are higher than in normal tissues using database analysis. PRRX1 was expressed in various human sarcoma tissues, and its level increased during malignant progression from schwannoma or neurofibroma to MPNST. High expression of PRRX1 was also associated with poor prognosis of human MPNST patients, and PRRX1 knockdown suppressed proliferation, invasion and tumorigenic potential of human MPNST cell line, HS-PSS. Immunoprecipitation and mass spectrometry analysis revealed that PRRX1 interacts with TOP2A, and human MPNST patients with high expression of TOP2A showed poor prognosis. Interestingly, database analysis revealed that expression level of TOP2A in tumor tissues were positively correlated with PRRX1. TOP2A knockdown in HS-PSS suppressed proliferation, and inhibited the migration induced by PRRX1A overexpression. Overexpression of PRRX1 and TOP2A cooperatively increased migration and expression of tumor-malignancy associated gene sets, including EMT, mTORC1, KRAS and SRC signaling pathways. Inhibition of PRRX1-TOP2A interaction would be a novel tumor-selective therapeutic strategy that has less severe side effects than current chemotherapies.
Project description:Primary human adipose stromal cells (hASCs) from rs4684847 CC risk allele carriers were cultured and induced to differentiate into adipocytes, and simultaneously transfected for 72h with non-targeting siRNA or siRNA targeting PRRX1 (n=10) or both PRRX1 and PPARG (subset of the subjects, n=4).
Project description:Pulmonary metastasis is the main cause of medical failure and death of osteosarcoma patients. Our recent study identified IRX1 as a potential metastasis-driving gene in osteosarcoma. Studies showed that IRX1 can promote the migration, invasion and anoikis resistance of osteosarcoma cells. We generated 143B stable IRX1 knockdown and control cell lines, and found that IRX1 knockdown can inhibit the pulmonary metastasis of 143B cells in orthotopic mouse osteosarcoma model. Expression microarrays are performed in143B-shCtrl and 143B-shIRX1 cells to study the mechanism of IRX1 on promoting metastasis of osteosarcoma
Project description:Metastasis is a major obstacle to better prognosis in patients with hepatocellular carcinoma (HCC). Mesenchymal-epithelial transition (MET) is the driving force for metastatic colonization in which E-cadherin reexpression is a critical procedure. It has been reported that the loss of paired-related homeobox transcription factor 1 (PRRX1) is required for cancer cell metastasis in vivo. However, the role of PRRX1 in MET and how its downregulation triggers E-cadherin reexpression are unknown. In this study, we performed a systematic, mechanistic study regarding the role of PRRX1 in MET of HCC. We observed PRRX1 downregulation in HCC tissues which correlated with early metastasis and short overall survival time. Overexpression of PRRX1 induced EMT, but did not promote metastasis formation, while knockdown of PRRX1 promoted metastasis and colonization of circulating HCC cells as shown in in situ liver tumor model and colonization model. PRRX1 protein levels reversely correlated with E-cadherin levels in HCC cell lines. PRRX1 knockdown promoted E-cadherin reexpression and cell proliferation, inhibited cell invasion and migration. The microarray results showed that PRRX1 deficiency regulated extracellular matrix (ECM) interaction, focal adhesion, TGF-β signaling and cancer pathways. PRRX1 knockdown upregulated PITX2 (paired like homeodomain 2) and inhibited CTNNB1 (catenin beta 1) and SLUG. Silencing of PITX2 reversed CTNNB1 and SLUG inhibition and E-cadherin reexpression. PITX2 upregulation increased miR-200a and miR-200b/429, which further inhibited the transcription of CTNNB1 and SLUG, respectively, thus abrogating the inhibitory effect on E-cadherin. In conclusion, our data showed that the downregulation of PRRX1 induced E-cadherin reexpression through PITX2/miR-200a/CTNNB1 and PITX2/miR-200b/429/SLUG pathway, making PRRX1 a novel prognostic factor for HCC.
Project description:Pulmonary metastasis is the main cause of medical failure and death of osteosarcoma patients. Our recent study identified IRX1 as a potential metastasis-driving gene in osteosarcoma. Studies showed that IRX1 can promote the migration, invasion and anoikis resistance of osteosarcoma cells. We generated 143B stable IRX1 knockdown and control cell lines, and found that IRX1 knockdown can inhibit the pulmonary metastasis of 143B cells in orthotopic mouse osteosarcoma model.
Project description:To investigate downstream targets of PRRX1, we used MDA-MB-231 (MDA231) breast cancer cells which express low level of PRRX1 to generate a stable cell line where human PRRX1 was ectopically overexpressed (MDA231-PRRX1), and performed comparative microarray analyses. Interestingly, we found many miRNAs that were upregulated in MDA231-PRRX1 cells.
Project description:PRRX1 is expressed in mesenchymal-type neuroblastoma cells. Over-expression of PRRX1 in adrenergic-type cell line was used to study reprogramming towards a mesenchymal lineage.