Project description:Dermal invasion is a hallmark of malignant melanoma. The molecular alterations driving the progression of primary melanoma to metastatic disease have been studied extensively, whereas the early progression of non-invasive primary melanoma to an invasive state is not well understood. To elucidate the mechanisms underlying the transition from radial to vertical growth, the first step in melanoma invasion, we developed a zebrafish melanoma model in which constitutive activation of ribosomal protein S6 kinase 1 (RSK1) drives tumor invasion. Transcriptomic analysis of RSK1-activated tumors identified metabolic changes, including upregulation of genes associated with oxidative phosphorylation. Vertical growth phase human melanoma cells show higher oxygen consumption and preferential utilization of glutamine compared to radial growth phase melanoma cells. Peroxisome proliferator-activated receptor gamma coactivator-1α (PGC1a has been proposed as a master regulator of tumor oxidative phosphorylation. In human primary melanoma specimens we show that PGC1a protein expression is positively associated with increased tumor thickness and expression of the proliferative marker Ki-67 and the reactive oxygen species (ROS) scavenger SCARA3. PGC1a depletion modulates cellular processes associated with primary melanoma growth and invasion, including oxidative stress. Our results support a role for PGC1a in mediating glutamine-driven OXPHOS to facilitate the invasive growth of primary melanoma.
Project description:Background: Melanoma brain metastases (MBM) continues to be a significant clinical problem with limited treatment options. Highly invasive melanoma cells migrate along the vasculature and perivascular cells may contribute to residual disease and recurrence. PTEN loss and hyperactivation of AKT occur in MBM; however, a role for PTEN/AKT in perivascular invasion has not been described. Methods: We used in vivo intracranial injections of murine melanoma and bulk RNA sequencing of melanoma cells co-cultured with brain endothelial cells (brECs) to investigate brain colonization and perivascular invasion. Results: We found that PTEN-null melanoma cells were highly efficient at colonizing the perivascular niche relative to PTEN-expressing counterparts. PTEN re-expression (PTEN-RE) in melanoma significantly reduced brain colonization and migration along the vasculature. We hypothesized this phenotype was mediated through vascular-induced TGFβ secretion, which drives AKT phosphorylation. Disabling TGFβ signaling in melanoma cells reduced colonization and perivascular invasion; however, introduction of constitutively-active myristolated-AKT (myrAKT) restored overall tumor size but not perivascular invasion. Conclusions: PTEN loss facilitates perivascular brain colonization and invasion of melanoma. TGFβ-AKT signaling partially contributes to this phenotype, but further studies are needed to determine the complementary mechanisms that enable melanoma cells to both survive and spread along the brain vasculature.
Project description:High-grade glioma is highly aggressive and malignant, resistant to combined therapies and easy to relapse. A better understanding of circRNA biological function in high-grade glioma might contribute to the therapeutic efficacy. Here, a circRNA merely up-regulated in high-grade glioma, circGLIS3 (hsa_circ_0002874, originating from exon 2 of GLIS3), was validated by microarray and qRT-PCR. Functional experiments uncovered that up-regulation of circGLIS3 promoted glioma cell migration and invasion, and showed aggressive characteristics in tumor-bearing mice. Fluorescence in situ hybridization, RNA pull-down, RNA immunoprecipitation and immunohistochemical staining showed that circGLIS3 could promoted Ezrin T567 phosphorylation. Further investigation showed that circGLIS3 could be excreted by glioma through exosomes and induced endothelial cells angiogenesis. This study indicates that circGLIS3 is up-regulated in high-grade glioma and contributes to the invasion and angiogenesis of glioma via promoting Ezrin T567 phosphorylation.
Project description:High-grade glioma is highly aggressive and malignant, resistant to combined therapies and easy to relapse. A better understanding of circRNA biological function in high-grade glioma might contribute to the therapeutic efficacy. Here, a circRNA merely up-regulated in high-grade glioma, circGLIS3 (hsa_circ_0002874, originating from exon 2 of GLIS3), was validated by microarray and qRT-PCR. Functional experiments uncovered that up-regulation of circGLIS3 promoted glioma cell migration and invasion, and showed aggressive characteristics in tumor-bearing mice. Fluorescence in situ hybridization, RNA pull-down, RNA immunoprecipitation and immunohistochemical staining showed that circGLIS3 could promoted Ezrin T567 phosphorylation. Further investigation showed that circGLIS3 could be excreted by glioma through exosomes and induced endothelial cells angiogenesis. This study indicates that circGLIS3 is up-regulated in high-grade glioma and contributes to the invasion and angiogenesis of glioma via promoting Ezrin T567 phosphorylation.
Project description:Targeting components of the mitogen-activated protein kinase (MAPK) pathway prolongs survival of patients with advanced BRAFV600E melanomas but such an approach is not curative because of the rapid acquisition of numerous resistance mechanisms. Here we analyze melanoma cells that evade MAPK inhibitors by undergoing a senescence-like, slow-growth, phenotype, which leads to acquired resistance. The initial therapeutic response is characterized by an integrated stress response program, including stimulation of autophagic flux, activation of the endoplasmic reticulum machinery, and an enhanced ability of detoxifying reactive oxygen species. Reversibly senescent cells also exhibit an increase in mitochondrial genome copy number and a strong metabolic shift towards oxidative phosphorylation (OxPhos). Inducing mitochondrial dysfunction by co-targeting the MAPK pathway and mitochondrial Hsp90-directed protein folding with specific inhibitors prevented entry of cells into a reversibly senescent state, suppressed mitochondrial energy metabolism and augmented therapy response.
Project description:Cancer is a disease of aging, and incidence and mortality from all cancers increase logarithmically after the age of 45. Older patients have a much poorer prognosis for melanomas of equal stage, compared to younger individuals. The role of the tumor microenvironment in modulating cancer behavior is widely recognized. We hypothesized that age-related changes in the tumor microenvironment could affect the progression of melanoma. We demonstrate that the aging microenvironment increases the invasion of melanoma cells. Using skin fibroblasts isolated from healthy donors, we have built artificial skin and demonstrate that melanoma cells invade more rapidly when exposed to aged fibroblasts. In a mouse model of melanoma (YUMM1.7, BrafV600E/Cdkn2a-/-/Pten-/-), congeneic to C57/BL6 mice, melanomas invade faster in aged mice. Gene expression analyses suggest that melanoma cells are undergoing DNA damage when exposed to an aged microenvironment, and we confirm this in cellular assays. Proteomics analysis of aging fibroblasts suggest that fibroblasts secrete molecules (laminin b2, Wnt inhibitors) associated with increased resistance to targeted therapy. Indeed, melanoma cells injected into aged mice respond less well to PLX4720 than those injected into young mice. This suggests that exciting new drugs targeting the BRAF pathway may be less effective in aging patients.
Project description:To define the role of MAGE-A1 in melanoma growth and metastasis, we performed RNA-seq analysis on MAGE-A1 overexpression (OE) and knockdown (KD) models in A375 human melanoma cell line. Our results revealed that overexpression of MAGE-A1 dramatically promoted proliferation, migration, and invasion of human melanoma cells in vitro and down-regulated of MAGE-A1 inhibited tumor cell proliferation and invasion. Furthermore, MAGE-A1 exerts its tumor promoting activity via activating including ERK-MAPK signaling pathway by RNA-seq analysis. mRNA profiles of MAGE-A1 over expression (OE), knockdown (KD), pcDNA-vector control, and pRNAT-scramble control in A375 cell line were generated using Ion torrent