Project description:Pancreatic cancer is an aggressive malignancy, often diagnosed at metastatic stages. Several studies have implicated systemic factors, such as extracellular vesicle release and myeloid cell expansion, in the establishment of pre-metastatic niches in cancer. The Rab27a GTPase is overexpressed in advanced cancers, can regulate vesicle trafficking, and has been previously linked to non-cell autonomous control of tumor growth and metastasis, however, the role of Rab27a itself in the metastatic propensity of pancreatic cancer is not well understood. Here, we have established a model to study how Rab27a directs formation of the pre-metastatic niche. Loss of Rab27a in pancreatic cancer cells did not decrease tumor growth in vivo, but resulted in altered systemic myeloid cell expansion, both in the primary tumors and at the distant organ sites. In metastasis assays, loss of Rab27a expression in tumor cells injected into circulation compromised efficient outgrowth of metastatic lesions. However, Rab27a knockdown cells had an unexpected advantage at initial steps of metastatic seeding, suggesting that Rab27a may alter cell-autonomous invasive properties of the tumor cells. Gene expression analysis of gene expression revealed that downregulation of Rab27a increased expression of genes involved in epithelial-to-mesenchymal transition pathways, consistent with our findings that primary tumors arising from Rab27a knockdown cells were more invasive. Overall, these data reveal that Rab27a can play divergent roles in regulating pro-metastatic propensity of pancreatic cancer cells: by generating pro-metastatic environment at the distant organ sites, and by suppressing invasive properties of the cancer cells.
Project description:RATIONALE: Diagnostic imaging procedures, such as fludeoxyglucose F 18 PET, may be effective in detecting cancer or recurrence of cancer, or premalignant polyps.
PURPOSE: This clinical trial is studying fludeoxyglucose F 18-PET imaging to see how well it works in determining protein and gene expression signatures in patients with premalignant polyps or colon cancer.
Project description:This work was designed to profile major proteins of extracellular vesicles (EVs) from mouse tanycytes with target gene knockdown (KD) versus control. The assay was based on using in vitro culture models of mouse hypothalamic tanycytes (predominantly alpha-tanycytes) which were engineered through lentivirus-mediated KD of a target gene, including CRISPR/Cas9-based Rab27a KD or Rictor KD or shRNA-based KD of pre-pro-insulin (ppIns). Scramble gRNA-based control was used as the control group for both Rab27a KD and Rictor KD, and scramble shRNA-based control was used as the control group for ppIns KD. EVs were released from these tanycytes in culture, purified and subjected to proteomics. EV samples of KD groups included Rab27a KD EVs (251015-1, 251015-2, 251015-5), ppIns KD EVs (251015-12, 251015-13, 251015-15), and Rictor KD EVs (251015-3, 251015-6, 251015-14). EV samples of control groups included scramble gRNA control EVs (251015-4, 251015-10, 251015-11) and scramble shRNA control EVs (251015-7, 251015-8, 251015-9). Proteomic profiling suggested that the overall protein composition of tanycyte-derived EVs was not substantially changed by either of these KD approaches.