Receptor Tyrosine Kinases Activate Canonical WNT/β-Catenin Signaling via MAP Kinase/LRP6 Pathway and Direct β-Catenin Phosphorylation

Receptor tyrosine kinase signaling cooperates with WNT/β-catenin signaling in regulating many biological processes, but the mechanisms of their interaction remain poorly defined. We describe a potent activation of WNT/β-catenin by FGFR2, FGFR3, EGFR and TRKA kinases, which is independent of the PI3K/AKT pathway. Instead, this phenotype depends on ERK MAP kinase-mediated phosphorylation of WNT co-receptor LRP6 at Ser1490 and Thr1572 during its Golgi network-based maturation process. This phosphorylation dramatically increases the cellular response to WNT. Moreover, FGFR2, FGFR3, EGFR and TRKA directly phosphorylate β-catenin at Tyr142, which is known to increase cytoplasmic β-catenin concentration via release of β-catenin from membranous cadherin complexes. We conclude that signaling via ERK/LRP6 pathway and direct β-catenin phosphorylation at Tyr142 represent two mechanisms used by various receptor tyrosine kinase systems to activate canonical WNT signaling

Intercellular Mitochondrial Transfer in the Tumor Microenvironment

Cell-to-cell communication is a fundamental process in every multicellular organism. In addition to membrane-bound and released factors, the sharing of cytosolic components represents a new, poorly explored signaling route. An extraordinary example of this communication channel is the direct transport of mitochondria between cells. In this review, we discuss how intercellular mitochondrial transfer can be used by cancer cells to sustain their high metabolic requirements and promote drug resistance and describe relevant molecular players in the context of current and future cancer therapy

Intercellular Mitochondrial Transfer in the Tumor Microenvironment

Cell-to-cell communication is a fundamental process in every multicellular organism. In addition to membrane-bound and released factors, the sharing of cytosolic components represents a new, poorly explored signaling route. An extraordinary example of this communication channel is the direct transport of mitochondria between cells. In this review, we discuss how intercellular mitochondrial transfer can be used by cancer cells to sustain their high metabolic requirements and promote drug resistance and describe relevant molecular players in the context of current and future cancer therapy

More than 2% of circulating tumor plasma cells defines plasma cell leukemia-like multiple myeloma

[Purpose]: Primary plasma cell leukemia (PCL) is the most aggressive monoclonal gammopathy. It was formerly characterized by $20$ 5%. We hypothesized that primary PCL is not a separate clinical entity, but rather that it represents ultra-high-risk multiple myeloma (MM) characterized by elevated CTC levels. [Methods]: We assessed the levels of CTCs by multiparameter flow cytometry in 395 patients with newly diagnosed transplant-ineligible MM to establish a cutoff for CTCs that identifies the patients with ultra-high-risk PCL-like MM. We tested the cutoff on 185 transplant-eligible patients with MM and further validated on an independent cohort of 280 transplant-ineligible patients treated in the GEM-CLARIDEX trial. The largest published real-world cohort of patients with primary PCL was used for comparison of survival. Finally, we challenged the current 5% threshold for primary PCL diagnosis. [Results]: Newly diagnosed transplant-ineligible patients with MM with 2%-20% CTCs had significantly shorter progression-free survival (3.1 v 15.6 months; P , .001) and overall survival (14.6 v 33.6 months; P 5 .023) than patients with , 2%. The 2% cutoff proved to be applicable also in transplant-eligible patients with MM and was successfully validated on an independent cohort of patients from the GEM-CLARIDEX trial. Most importantly, patients with 2%-20% CTCs had comparable dismal outcomes with primary PCL. Moreover, after revealing a low mean difference between flow cytometric and morphologic evaluation of CTCs, we showed that patients with 2%-5% CTCs have similar outcomes as those with 5%-20% CTCs. [Conclusions]: Our study uncovers that $ 2% CTCs is a biomarker of hidden primary PCL and supports the assessment of CTCs by flow cytometry during the diagnostic workup of MM.Supported by the European Regional Development Fund—New Directions of Biomedical Research in the Ostrava Region (No. CZ.02.1.01/0.0/0.0/18_069/0010060), by the National Institute for Cancer Research (Program EXCELES, ID Project No. LX22NPO5102)—Funded by the European Union—Next Generation EU and by the Ministry of Health of the Czech Republic (AZV—NU21-03-00076), Institutional Support by MH CZ—DRO—FNOs/2019, MH CZ—DRO—FNOs/2020, Student's grant system SGS12/PrF/2022, SGS10/LF/2022 University of Ostrava and by the Ministry of Education, Youth and Sports of the Czech Republic through the e-INFRA CZ (ID:90140). The work was also supported by Centro de Investigación Biomédica en Red—Área de Oncología—del Instituto de Salud Carlos III (CIBERONC; CB16/12/00369); Instituto de Salud Carlos III/Subdirección General de Investigación Sanitaria (FIS No. PI20/00048, PI21/01816); the Cancer Research UK (C355/A26819), FCAECC and AIRC under the Accelerator Award Program (EDITOR); the European Research Council (ERC) 2015 Starting Grant (MYELOMANEXT/680200)

Receptor Tyrosine Kinases Activate Canonical WNT/?-Catenin Signaling via MAP Kinase/LRP6 Pathway and Direct Beta-Catenin Phosphorylation

Receptor tyrosine kinase signaling cooperates with WNT/β-catenin signaling in regulating many biological processes, but the mechanisms of their interaction remain poorly defined. We describe a potent activation of WNT/β-catenin by FGFR2, FGFR3, EGFR and TRKA kinases, which is independent of the PI3K/AKT pathway. Instead, this phenotype depends on ERK MAP kinase-mediated phosphorylation of WNT co-receptor LRP6 at Ser1490 and Thr1572 during its Golgi network-based maturation process. This phosphorylation dramatically increases the cellular response to WNT. Moreover, FGFR2, FGFR3, EGFR and TRKA directly phosphorylate β-catenin at Tyr142, which is known to increase cytoplasmic β-catenin concentration via release of β-catenin from membranous cadherin complexes. We conclude that signaling via ERK/LRP6 pathway and direct β-catenin phosphorylation at Tyr142 represent two mechanisms used by various receptor tyrosine kinase systems to activate canonical WNT signaling

Receptor Tyrosine Kinases Activate Canonical WNT/?-Catenin Signaling via MAP Kinase/LRP6 Pathway and Direct Beta-Catenin Phosphorylation

Receptor tyrosine kinase signaling cooperates with WNT/β-catenin signaling in regulating many biological processes, but the mechanisms of their interaction remain poorly defined. We describe a potent activation of WNT/β-catenin by FGFR2, FGFR3, EGFR and TRKA kinases, which is independent of the PI3K/AKT pathway. Instead, this phenotype depends on ERK MAP kinase-mediated phosphorylation of WNT co-receptor LRP6 at Ser1490 and Thr1572 during its Golgi network-based maturation process. This phosphorylation dramatically increases the cellular response to WNT. Moreover, FGFR2, FGFR3, EGFR and TRKA directly phosphorylate β-catenin at Tyr142, which is known to increase cytoplasmic β-catenin concentration via release of β-catenin from membranous cadherin complexes. We conclude that signaling via ERK/LRP6 pathway and direct β-catenin phosphorylation at Tyr142 represent two mechanisms used by various receptor tyrosine kinase systems to activate canonical WNT signaling

More than 2% of circulating tumor plasma cells defines plasma cell leukemia-like multiple myeloma

PURPOSEPrimary plasma cell leukemia (PCL) is the most aggressive monoclonal gammopathy. It was formerly characterized by >= 20% circulating plasma cells (CTCs) until 2021, when this threshold was decreased to >= 5%. We hypothesized that primary PCL is not a separate clinical entity, but rather that it represents ultra-high-risk multiple myeloma (MM) characterized by elevated CTC levels.METHODSWe assessed the levels of CTCs by multiparameter flow cytometry in 395 patients with newly diagnosed transplant-ineligible MM to establish a cutoff for CTCs that identifies the patients with ultra-high-risk PCL-like MM. We tested the cutoff on 185 transplant-eligible patients with MM and further validated on an independent cohort of 280 transplant-ineligible patients treated in the GEM-CLARIDEX trial. The largest published real-world cohort of patients with primary PCL was used for comparison of survival. Finally, we challenged the current 5% threshold for primary PCL diagnosis.RESULTSNewly diagnosed transplant-ineligible patients with MM with 2%-20% CTCs had significantly shorter progression-free survival (3.1 v 15.6 months; P = 2% CTCs is a biomarker of hidden primary PCL and supports the assessment of CTCs by flow cytometry during the diagnostic workup of MM

Disease-associated FGFR3 and FGFR2 mutants signal via ERK/LRP6 pathway.

<p>(A) RCS cells were transfected with wt FGFR3 or activating FGFR3 mutants (N540K, G380R, R248C, Y373C, K650M, K650E), and analyzed for the indicated molecules by WB 48 hours later. The levels of ERK phosphorylation vary among the tested mutants, reflecting the different strength of FGFR3 activation by each particular mutation <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0035826#pone.0035826-Krejci2" target="_blank">[24]</a>. K508M - kinase inactive FGFR3 mutant. GFP and empty vectors serve as transfection controls. (B) LRP6 phosphorylation at Thr1572 caused by highly activating FGFR3 mutants R248C and K650E. (C) Cells were transfected with the indicated FGFR3 vectors together with Topflash reporter vectors, treated with WNT3a and analyzed for luciferase activity. Data represent an average from three transfections (each measured twice), with the indicated standard deviations. A logarithmic scale of the <i>y</i>-axis is necessary to express the massive Topflash activation in WNT3a-treated cells expressing activating FGFR3 mutants (* <i>p</i><0.001; Student’s <i>t</i>-test; compared to wt FGFR3). Results are representative of four experiments. (D) Cells were transfected with wt FGFR2 or activating FGFR2 mutants (S252W, P253R, C342R, C342Y, Y375C), and analyzed for the indicated molecules by WB. Note the significant ERK and LRP6 phosphorylation caused by C342R, C342Y and Y375C mutants, which correlates with increased basal (E; upper graph) and WNT3a-induced (E; lower graph) β-catenin activity, evidenced by Topflash experiment. Results are representative for three experiments (* <i>p</i><0.001; Student’s <i>t</i>-test; compared to wt FGFR2).</p

EGFR and TRKA activate WNT/β-catenin signaling via ERK/LRP6 pathway.

<p>(A, E) RCS cells were transfected with empty plasmid or plasmid encoding V5-tagged EGFR or TRKA, treated with EGF or NGF (50 ng/ml) for 1 hour, and analyzed for indicated molecules by WB. (B, F) Cells were transfected as indicated, grown for 24 hours, treated with EGF, NGF and WNT3a, and analyzed for luciferase activity. Data represent an average from three transfections (each measured twice). Statistically significant differences are indicated (* <i>p</i><0.0001, # <i>p</i><0.05; Student’s <i>t</i>-test). Note the potent upregulation of basal or WNT3a-mediated Topflash activity in EGF or NGF-treated cells expressing the corresponding receptor. (C, G) Cells were transfected with EGFR (C) or TRKA (G) together with Topflash reporter vectors, treated with U0126 (20 µM) one hour prior to EGF, NGF and WNT3a treatment, and analyzed for luciferase activity. Data represent an average from three or four transfections (each measured twice). Statistically significant differences are indicated (* <i>p</i><0.0001, # <i>p</i><0.005; Student’s <i>t</i>-test, compared to cells without U0126 for each treatment). (D, H) Cells were transfected as indicated, treated with EGF, NGF and WNT3a for 48 hours, and analyzed for luciferase activity. Data represent an average from four transfections (each measured twice), with the indicated standard deviations. Statistically significant differences are indicated (* <i>p</i><0.0001, # <i>p</i><0.001; Student’s <i>t</i>-test).</p