Expression data from Control and Six1 expressing MCF7 derived xenograft tumors
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ABSTRACT: Although an important association between lymph node metastasis and poor prognosis in breast cancer was observed decades ago, an active role for the lymphatic system in metastatic dissemination has only recently been examined. We demonstrate that the Six1 homeoprotein promotes peri- and intra-tumoral lymphangiogenesis, lymphatic invasion, and distant metastasis of breast cancer cells. We identify the pro-lymphangiogenic factor, VEGF-C, as required for this process, and demonstrate transcriptional induction as the mechanism of regulation of VEGF-C expression by Six1. Using a different, but complementary animal model, we show that while required, VEGF-C is not sufficient for the pro-metastatic effects of Six1. Verifying the clinical significance of this pro-metastatic Six1-VEGF-C axis, we demonstrate co-expression of Six1 and VEGF-C in human breast cancer.
Project description:Although an important association between lymph node metastasis and poor prognosis in breast cancer was observed decades ago, an active role for the lymphatic system in metastatic dissemination has only recently been examined. We demonstrate that the Six1 homeoprotein promotes peri- and intra-tumoral lymphangiogenesis, lymphatic invasion, and distant metastasis of breast cancer cells. We identify the pro-lymphangiogenic factor, VEGF-C, as required for this process, and demonstrate transcriptional induction as the mechanism of regulation of VEGF-C expression by Six1. Using a different, but complementary animal model, we show that while required, VEGF-C is not sufficient for the pro-metastatic effects of Six1. Verifying the clinical significance of this pro-metastatic Six1-VEGF-C axis, we demonstrate co-expression of Six1 and VEGF-C in human breast cancer. Two Control and two Six1 expressing MCF7 clones were orthotopically injected into NOD/Scid mice forming a total of 3 Control and 3 Six1 tumors that were allowed to grow to 2 cm^3 . The tumors were dissected and total RNA was isolated from each tumor and hybridized to Affymetrix arrays
Project description:<p>Breast cancer metastasis occurs via blood and lymphatic vessels. Breast cancer cells 'educate' lymphatic endothelial cells (LECs) to support tumor vascularization and growth. However, despite known metabolic alterations in breast cancer, it remains unclear how lymphatic endothelial cell metabolism is altered in the tumor microenvironment and its effect in lymphangiogenic signaling in LECs. We analyzed metabolites inside LECs in co-culture with MCF-7, MDA-MB-231, and SK-BR-3 breast cancer cell lines using 1H nuclear magnetic resonance (NMR) metabolomics, Seahorse, and the spatial distribution of metabolic co-enzymes using optical redox ratio imaging to describe breast cancer-LEC metabolic crosstalk. LECs co-cultured with breast cancer cells exhibited cell-line dependent altered metabolic profiles, including significant changes in lactate concentration in breast cancer co-culture. Cell metabolic phenotype analysis using Seahorse showed LECs in co-culture exhibited reduced mitochondrial respiration, increased reliance on glycolysis and reduced metabolic flexibility. Optical redox ratio measurements revealed reduced NAD(P)H levels in LECs potentially due to increased NAD(P)H utilization to maintain redox homeostasis. 13C-labeled glucose experiments did not reveal lactate shuttling into LECs from breast cancer cells, yet showed other 13C signals in LECs suggesting internalized metabolites and metabolic exchange between the two cell types. We also determined that breast cancer co-culture stimulated lymphangiogenic signaling in LECs, yet activation was not stimulated by lactate alone. Increased lymphangiogenic signaling suggests paracrine signaling between LECs and breast cancer cells which could have a pro-metastatic role.</p>
Project description:Inappropriate activation of developmental pathways is a well-recognized tumor-promoting mechanism. Here we show that overexpression of the homeoprotein Six1, normally a developmentally restricted transcriptional regulator, increases Transforming Growth Factor-beta (TGF-beta) signaling in mammary carcinoma cells and induces an epithelial to mesenchymal transition (EMT) that is in part dependent on its ability to increase TGF-beta signaling. TGF-beta signaling and EMT have been implicated in metastatic dissemination of carcinoma. Using spontaneous and experimental metastasis mouse models, we demonstrate that Six1 overexpression promotes breast cancer metastasis. In addition, we show that, like its induction of EMT, Six1-induced experimental metastasis is dependent on its ability to activate TGF-beta signaling. Importantly, in human breast cancers Six1 significantly correlates with nuclear Smad3, and thus increased TGF-beta signaling. Further, breast cancer patients whose tumors overexpress Six1 have a shortened time to relapse and metastasis, and an overall decrease in survival. Finally, we show that the effects of Six1 on tumor progression likely extend beyond breast cancer, since its overexpression correlates with adverse outcomes in numerous other cancers, including brain, cervical, prostate, colon, kidney, and liver, amongst others. Our findings argue that Six1, acting through TGF-beta signaling and EMT, is a powerful and global promoter of cancer metastasis.
Project description:Within the tumor microenvironment, lymphatic endothelial cells (LEC) contribute to the remodeling and the formation of lymphatic vessels involved in the transport of metastatic and immune cells. Displaying an increasingly recognized plasticity and heterogeneity, tumor-associated LEC are expected to exert additional functions in the primary tumor environment. Using RNA sequencing data, we analyzed the transcriptomic changes induced in LEC in response to two different stimuli from the tumor microenvironment, i.e. vascular endothelial growth factor C (VEGF-C) and the tumor secretome of malignant cells. This analysis revealed that these two stimuli exert contrasting effects leading to distinct transcriptomic switches: a stimulation of pro-inflammatory factors (“secretory transcriptome”) induced by the tumor secretome versus an upregulation of cell cycle-associated pathways (“lymphangiogenic transcriptome”) induced by VEGF-C. These data help to better understand the phenotypic reprogramming of LEC caused by their interaction with tumor cells and pro-lymphangiogenic factors, opening the door for further investigations to decipher the diversity of LEC subpopulations and their diverse roles in lymphangiogenic conditions and the tumor microenvironment.
Project description:Secreted extracellular vesicles are known to influence the tumor microenvironment and promote metastasis. In this work, we have analyzed the involvement of extracellular vesicles in establishing the lymph node pre-metastatic niche by melanoma cells. We found that small extracellular vesicles (sEVs) derived from highly metastatic melanoma cell lines spread broadly through the lymphatic system and are taken up by lymphatic endothelial cells reinforcing lymph node metastasis. Melanoma-derived sEVs induce lymphangiogenesis, a hallmark of pre-metastatic niche formation, in vitro and in lymphoreporter mice in vivo. Analysis of involved factors demonstrated that the neural growth factor receptor (NGFR) is secreted in melanoma-derived small extracellular vesicles and shuttled to lymphatic endothelial cells inducing lymphangiogenesis and tumor cell adhesion through the activation of ERK and NF-B pathways and ICAM1 expression. Importantly, ablation or inhibition of NGFR in sEVs reversed the lymphangiogenic phenotype, decreased melanoma lymph node metastasis and extended mice survival. Importantly, analysis of NGFR expression in lymph node metastases and matched primary tumors shows that levels of MITF+NGFR+ lymph node metastatic cells are correlated with disease outcome. Our data support that NGFR is secreted in sEVs favoring lymph node pre-metastatic niche formation and lymph node metastasis in melanoma.
Project description:Secreted extracellular vesicles are known to influence the tumor microenvironment and promote metastasis. In this work, we have analyzed the involvement of extracellular vesicles in the establishment of lymph node pre-metastatic niches by melanoma cells. We found that small extracellular vesicles (sEVs) derived from highly metastatic melanoma cell lines spread broadly through the lymphatic system and were taken up by lymphatic endothelial cells, reinforcing lymph node metastasis. Melanoma-derived sEVs induce lymphangiogenesis, a hallmark of pre-metastatic niche formation, in vitro and in lymphoreporter mice in vivo. We found that neural growth factor receptor (NGFR) is secreted in melanoma-derived small extracellular vesicles and shuttled to lymphatic endothelial cells, inducing lymphangiogenesis and tumor cell adhesion through the activation of ERK and NF-B pathways and ICAM1 expression. Importantly, ablation or inhibition of NGFR in sEVs reversed the lymphangiogenic phenotype, decreased melanoma lymph node metastasis and extended the survival. Importantly, analysis of NGFR expression in lymph node metastases and matched primary tumors shows that levels of MITF+NGFR+ lymph node metastatic cells are correlated with disease outcome. Our data support the idea that NGFR secreted in sEVs favors lymph node pre-metastatic niche formation and lymph node metastasis in melanoma
Project description:Invasion of lymphatic vessels is a key step in the metastasis of primary tumour cells to draining lymph nodes. Recent evidence indicates that such metastasis can be facilitated by tumour lymphangiogenesis, although it remains unclear whether this is a consequence of increased lymphatic vessel numbers or alteration in the properties of the vessels themselves. Here we have addressed this important question by comparing the RNA profile of normal dermal lymphatic endothelial cells (LEC) with those isolated from tumours of murine T-241/VEGF-C metastatic fibrosarcoma. Our findings reveal significant changes in the expression of some 792 genes in tumour lymphatics (â?¥ 2 fold up/downregulation, p â?¤ 0.05), involving particularly transcripts associated with junctional adhesion, immunomodulation, extracellular matrix and vessel growth/patterning, several of which we have confirmed by RT-PCR and/or immunohistochemistry. Interestingly, this altered phenotype could not be attributed solely to VEGF-C induced lymphoproliferation, as no similar change in gene expression was reported when human LEC were cultured with VEGF-C in vitro. Moreover, we show that a key protein upregulated in the mouse model, namely the tight junction protein Endothelial Cell Specific Adhesion Molecule (ESAM), is similarly upregulated in tumour lymphatic vessels from 2/2 patients with head and neck squamous cell carcinoma and 4/4 patients with aggressive bladder carcinoma. These findings demonstrate a previously unrecognized influence of tumour environment on lymphatic gene expression and identify candidate tumour specific vessel markers that may prove valuable for either prognosis or therapy. Experiment Overall Design: Here we have investigated the invasion of lymphatic vessels as a key step in the metastasis of primary tumour cells to draining lymph nodes by comparing the gene expression profile of normal dermal lymphatic endothelial cells (LEC) with those isolated from tumours of murine T241/VEGF-C/GFP metastatic fibrosarcoma. Three biological replicates were analyzed from each group.
Project description:TP53 is mutated in 50% of all cancers, and is often functionally compromised in cancers where it is not mutated. We demonstrate that the pro-tumorigenic/metastatic Six1 homeoprotein decreases p53 levels through a mechanism that does not involve the negative regulator of p53, MDM2. Instead, Six1 regulates p53 via a dual mechanism involving upregulation of microRNA-27a and downregulation of the ribosomal protein L26 (RPL26), a positive regulator of p53 translation. Mutation analysis confirms that RPL26, whose expression inversely correlates with Six1 expression in numerous tumor types, inhibits miR-27a binding to the p53 3’UTR and prevents microRNA-mediated translational inhibition of p53. Thus, through simultaneous downregulation of RPL26 and upregulation of miR-27a, Six1 efficiently lowers p53 levels despite regulation of p53 at the level of the proteasome. Consequently, Six1 overexpression, which is observed in numerous tumor types, leads to dramatic resistance to nutlins, as well as other therapies targeting the p53-MDM2 interaction.
Project description:TP53 is mutated in 50% of all cancers, and is often functionally compromised in cancers where it is not mutated. We demonstrate that the pro-tumorigenic/metastatic Six1 homeoprotein decreases p53 levels through a mechanism that does not involve the negative regulator of p53, MDM2. Instead, Six1 regulates p53 via a dual mechanism involving upregulation of microRNA-27a and downregulation of the ribosomal protein L26 (RPL26), a positive regulator of p53 translation. Mutation analysis confirms that RPL26, whose expression inversely correlates with Six1 expression in numerous tumor types, inhibits miR-27a binding to the p53 3’UTR and prevents microRNA-mediated translational inhibition of p53. Thus, through simultaneous downregulation of RPL26 and upregulation of miR-27a, Six1 efficiently lowers p53 levels despite regulation of p53 at the level of the proteasome. Consequently, Six1 overexpression, which is observed in numerous tumor types, leads to dramatic resistance to nutlins, as well as other therapies targeting the p53-MDM2 interaction.
Project description:In primary melanoma, the amount of VEGF-C expression and lymphangiogenesis predict the probability of metastasis to sentinel nodes, but conditions boosting VEGF-C expression in melanoma are poorly characterized. By comparative mRNA expression analysis of a set of 22 human melanoma cell lines, we found a striking negative correlation between VEGF-C and MITF expression, which was confirmed by data mining in GEO databases of human melanoma Affymetrix arrays. Moreover, in human patients, high VEGF-C, and low MITF levels in primary melanoma significantly correlated with the chance of metastasis. Pathway analysis disclosed the respective JNK- and p38/MAPK activities as being responsible for the inverse regulation of VEGF-C and MITF. Predominant JNK signaling results in a VEGF-Clow/MITFhigh phenotype, these melanoma cells are highly proliferative, show low mobility and are poorly lymphangiogenic. Predominant p38 signaling results in a VEGF-Chigh/MITFlow phenotype, corresponding to a slowly cycling, highly mobile, lymphangiogenic and metastatic melanoma.