Platelet clusters might be also found not only within blood vessels, but also within the tumor stroma, indicating leaking vessels. Since vascular and stromal platelet clusters correlated, the migration of platelets out of the vessels seems to be induced by vascular clusters. The lymphangiogenic factors secreted within the stroma by extravasated platelets might induce growth of lymphatic endothelium, thus supporting the formation of newly formed lymphatic vessels. A shown in our cell culture experiments, this stimulation of proliferation of LECs by platelets seems to be induced in a timeand dose dependent manner mainly by VEGF-C and PDGF-BB, which are secreted by platelets. Blocking IQ1 experiments indicate a predominant role of VEGF-C in this process. As reported in a variety of studies, the increase in lymphatic vessels correlates with the probability to develop LVI and subsequent lymph node metastases. [29?4] The fact that platelets promote extravasation of tumor cells is well known [17], but based on our data it seems very probable that platelets in the tumor stroma also promote invasion of tumor cells into the lymphovascular system. In summary, we show for the first time in large series of human cancer patients and also in vitro that peripheral blood platelets play an important role in esophageal cancer lymphangiogenesis and LVI, thus influencing prognosis of patients. So the disruption of signaling pathways between platelets, tumor cells and lymphatic endothelium might be of benefit for patients.Author ContributionsConceived and designed the experiments: SFS CB PB. Performed the experiments: LA CB TP. Analyzed the data: SFS LA AS TP CB PB. Contributed reagents/materials/analysis tools: SFS AS TP. Wrote the paper: SFS LA AS TP CB PB.
Multiple myeloma (MM) is an incurable malignancy of antibody-secreting plasma B-cells, whose etiology remains poorly understood. Pleuromutilin mutations in Ras genes, encoding key proteins regulating cell growth, differentiation and survival, occur commonly in MM with a prevalence of 20?9 [1?]. Indeed, using a targeted sequencing approach to screen highly expressed tyrosine kinase and cytokine signaling genes in primary human patient myeloma, we previously identified mutations at codon 12 and 61 in N- and KRAS as being the only recurrent variation in our sample set [4]. Recent genome sequencing efforts also found Ras mutations to be the most common single nucleotide variant (SNV) in MM [4], suggesting that Ras activation is an important event in MM pathogenesis. The somatic SNVs found most frequently in MM are gain-of-function mutations in Ras oncogenes (Kras and Nras), causing constitutive activation of the Ras protein [5]. Despite the genomic evidence for Ras pathogenesis, the functional role of Ras activation in MM has not previously been tested. This issue is not trivial as the induction of neoplasia by Ras activation is highly dependent on cellular context [6]. Understanding the effects of Ras activation in mature B-cells will allow us to better define the downstream pathways critical for development of MM. Moreoever, pharmaceutical approaches to target cancers with mutant Ras are underway [7?0], and a pre-clinical modelfaithfully replicating Ras-driven myeloma would be critical in evaluating the therapeutic potential of these agents in myeloma. Post-germinal center (GC) B-cells are strongly implicated as the cell of origin in MM by demonstration of stable immunoglobulin (Ig) switch clonotypes over the course of dis.Platelet clusters might be also found not only within blood vessels, but also within the tumor stroma, indicating leaking vessels. Since vascular and stromal platelet clusters correlated, the migration of platelets out of the vessels seems to be induced by vascular clusters. The lymphangiogenic factors secreted within the stroma by extravasated platelets might induce growth of lymphatic endothelium, thus supporting the formation of newly formed lymphatic vessels. A shown in our cell culture experiments, this stimulation of proliferation of LECs by platelets seems to be induced in a timeand dose dependent manner mainly by VEGF-C and PDGF-BB, which are secreted by platelets. Blocking experiments indicate a predominant role of VEGF-C in this process. As reported in a variety of studies, the increase in lymphatic vessels correlates with the probability to develop LVI and subsequent lymph node metastases. [29?4] The fact that platelets promote extravasation of tumor cells is well known [17], but based on our data it seems very probable that platelets in the tumor stroma also promote invasion of tumor cells into the lymphovascular system. In summary, we show for the first time in large series of human cancer patients and also in vitro that peripheral blood platelets play an important role in esophageal cancer lymphangiogenesis and LVI, thus influencing prognosis of patients. So the disruption of signaling pathways between platelets, tumor cells and lymphatic endothelium might be of benefit for patients.Author ContributionsConceived and designed the experiments: SFS CB PB. Performed the experiments: LA CB TP. Analyzed the data: SFS LA AS TP CB PB. Contributed reagents/materials/analysis tools: SFS AS TP. Wrote the paper: SFS LA AS TP CB PB.
Multiple myeloma (MM) is an incurable malignancy of antibody-secreting plasma B-cells, whose etiology remains poorly understood. Mutations in Ras genes, encoding key proteins regulating cell growth, differentiation and survival, occur commonly in MM with a prevalence of 20?9 [1?]. Indeed, using a targeted sequencing approach to screen highly expressed tyrosine kinase and cytokine signaling genes in primary human patient myeloma, we previously identified mutations at codon 12 and 61 in N- and KRAS as being the only recurrent variation in our sample set [4]. Recent genome sequencing efforts also found Ras mutations to be the most common single nucleotide variant (SNV) in MM [4], suggesting that Ras activation is an important event in MM pathogenesis. The somatic SNVs found most frequently in MM are gain-of-function mutations in Ras oncogenes (Kras and Nras), causing constitutive activation of the Ras protein [5]. Despite the genomic evidence for Ras pathogenesis, the functional role of Ras activation in MM has not previously been tested. This issue is not trivial as the induction of neoplasia by Ras activation is highly dependent on cellular context [6]. Understanding the effects of Ras activation in mature B-cells will allow us to better define the downstream pathways critical for development of MM. Moreoever, pharmaceutical approaches to target cancers with mutant Ras are underway [7?0], and a pre-clinical modelfaithfully replicating Ras-driven myeloma would be critical in evaluating the therapeutic potential of these agents in myeloma. Post-germinal center (GC) B-cells are strongly implicated as the cell of origin in MM by demonstration of stable immunoglobulin (Ig) switch clonotypes over the course of dis.
