STAT3 GAIN-OF-FUNCTION MUTATIONS CAUSE AUTOIMMUNE LYMPHOPROLIFERATIVE SYNDROME LIKE DISEASE BY DYSREGULATING EXPRESSION OF FAS AND BCL2 PROTEINS AND CAN BE THERAPEUTICALLY TARGETED BY BH3 MIMETICS
(Abstract release date: 05/19/16)
EHA Library. Fischer U. 06/12/16; 135323; S829
Dr. Ute Fischer
Contributions
Contributions
Abstract
Abstract: S829
Type: Oral Presentation
Presentation during EHA21: On Sunday, June 12, 2016 from 08:15 - 08:30
Location: Room H5
Background
Autoimmune Lymphoproliferative Syndrome (ALPS) like disease is typically characterized by lymphadenopathy, hepatosplenomegaly, autoimmune cytopenias and an elevated number of double negative T cells (DNT cells, CD3+, TCRα/β+, CD4-, CD8-). 70% of patients suffering from classical ALPS harbor germline or somatic mutations in genes involved in the apoptotic FAS death receptor signaling pathway (FAS, FASLG or CASP10). For about 30% of ALPS or ALPS-like patients the genetic cause is unknown.
Aims
The objective of this study was to identify novel gene candidates underlying ALPS like disease of unknown genetic cause and to test potential targeted therapeutic approaches.
Methods
30 patients with clinical ALPS like symptoms, but without classical mutations were analyzed by whole-exome sequencing. Candidate genes were identified using an in-house developed bioinformatic analysis pipeline for gene prioritization. Candidate mutations were validated by Sanger sequencing. Their impact on Fas signaling and apoptosis was studied and potential therapeutic approaches tested.
Results
We identified two patients with de novo germline mutations (p.R278H, p.M394T) of the Signal Transducer And Activator Of Transcription 3 (STAT3). Elevated levels of phosphorylated STAT3 (pSTAT3-Tyr705) indicated constitutive activation of STAT3.Patient 1 presented with Coombs positive hemolytic anemia, thrombocytopenia, generalized progressive, non-infectious, non-malignant lymphadenopathy and splenomegaly at the age of nine. Immunophenotyping revealed increased numbers of DNT cells (20% in peripheral blood) and over time the patient developed panhypogammaglobulinemia. Patient 2 presented with early-onset insulin dependent diabetes mellitus and non-infectious, non-malignant lymphadenopathy, splenomegaly, thrombocytopenia, neutropenia and mild anemia. DNT cells and immunoglobulin levels were normal.We could demonstrate that constitutive activation of STAT3 led to decreased FAS expression on primary patient T cells and to reduced FAS ligand induced apoptosis similar to the effect of FAS mutations in classical ALPS. Therapeutic targeting of STAT3 is challenging and so far none of the developed STAT3 inhibitors has been approved for clinical use. To determine alternative targets we analyzed STAT3 signaling in primary and transformed lymphocytes of the patients. STAT3 gain-of-function mutations led to increased expression of STAT3 target genes, including SOCS3 and key anti-apoptotic factors of the BCL2 family of proteins (BCL-2, BCL-XL), whereas expression of pro-apoptotic factors (BAX, BAK) was decreased. Consistently, patient cells were resistant to cell death induced by stimuli (e.g. IL-21, staurosporine) mediating cell death via the BCL2 protein family. Treatment with a STAT3-specific inhibitor (S3I-201) normalized the expression of these factors and rescued the apoptotic response. Cells harboring STAT3 mutations were significantly more sensitive than normal cells to death induced by the BH3 mimetic inhibitor ABT-737 that targets BCL2, BCL-XL and BCL-W providing proof-of-concept evidence and indicating a novel therapeutic option.
Conclusion
We report here on dominant STAT3 gain-of-function mutations that caused clinical phenotypes similar to ALPS like disease. We demonstrated that constitutive active STAT3 caused decreased FAS expression and a skewed balance of pro- and antiapoptotic BCL-2 factors resulting in apoptosis evasion that may be therapeutically targeted by BH3 mimetics.
Session topic: Non-malignant hematopoietic disorders
Keyword(s): Autoimmune disease, BCL2, Fas, Lymphoproliferative disorder
Type: Oral Presentation
Presentation during EHA21: On Sunday, June 12, 2016 from 08:15 - 08:30
Location: Room H5
Background
Autoimmune Lymphoproliferative Syndrome (ALPS) like disease is typically characterized by lymphadenopathy, hepatosplenomegaly, autoimmune cytopenias and an elevated number of double negative T cells (DNT cells, CD3+, TCRα/β+, CD4-, CD8-). 70% of patients suffering from classical ALPS harbor germline or somatic mutations in genes involved in the apoptotic FAS death receptor signaling pathway (FAS, FASLG or CASP10). For about 30% of ALPS or ALPS-like patients the genetic cause is unknown.
Aims
The objective of this study was to identify novel gene candidates underlying ALPS like disease of unknown genetic cause and to test potential targeted therapeutic approaches.
Methods
30 patients with clinical ALPS like symptoms, but without classical mutations were analyzed by whole-exome sequencing. Candidate genes were identified using an in-house developed bioinformatic analysis pipeline for gene prioritization. Candidate mutations were validated by Sanger sequencing. Their impact on Fas signaling and apoptosis was studied and potential therapeutic approaches tested.
Results
We identified two patients with de novo germline mutations (p.R278H, p.M394T) of the Signal Transducer And Activator Of Transcription 3 (STAT3). Elevated levels of phosphorylated STAT3 (pSTAT3-Tyr705) indicated constitutive activation of STAT3.Patient 1 presented with Coombs positive hemolytic anemia, thrombocytopenia, generalized progressive, non-infectious, non-malignant lymphadenopathy and splenomegaly at the age of nine. Immunophenotyping revealed increased numbers of DNT cells (20% in peripheral blood) and over time the patient developed panhypogammaglobulinemia. Patient 2 presented with early-onset insulin dependent diabetes mellitus and non-infectious, non-malignant lymphadenopathy, splenomegaly, thrombocytopenia, neutropenia and mild anemia. DNT cells and immunoglobulin levels were normal.We could demonstrate that constitutive activation of STAT3 led to decreased FAS expression on primary patient T cells and to reduced FAS ligand induced apoptosis similar to the effect of FAS mutations in classical ALPS. Therapeutic targeting of STAT3 is challenging and so far none of the developed STAT3 inhibitors has been approved for clinical use. To determine alternative targets we analyzed STAT3 signaling in primary and transformed lymphocytes of the patients. STAT3 gain-of-function mutations led to increased expression of STAT3 target genes, including SOCS3 and key anti-apoptotic factors of the BCL2 family of proteins (BCL-2, BCL-XL), whereas expression of pro-apoptotic factors (BAX, BAK) was decreased. Consistently, patient cells were resistant to cell death induced by stimuli (e.g. IL-21, staurosporine) mediating cell death via the BCL2 protein family. Treatment with a STAT3-specific inhibitor (S3I-201) normalized the expression of these factors and rescued the apoptotic response. Cells harboring STAT3 mutations were significantly more sensitive than normal cells to death induced by the BH3 mimetic inhibitor ABT-737 that targets BCL2, BCL-XL and BCL-W providing proof-of-concept evidence and indicating a novel therapeutic option.
Conclusion
We report here on dominant STAT3 gain-of-function mutations that caused clinical phenotypes similar to ALPS like disease. We demonstrated that constitutive active STAT3 caused decreased FAS expression and a skewed balance of pro- and antiapoptotic BCL-2 factors resulting in apoptosis evasion that may be therapeutically targeted by BH3 mimetics.
Session topic: Non-malignant hematopoietic disorders
Keyword(s): Autoimmune disease, BCL2, Fas, Lymphoproliferative disorder
Abstract: S829
Type: Oral Presentation
Presentation during EHA21: On Sunday, June 12, 2016 from 08:15 - 08:30
Location: Room H5
Background
Autoimmune Lymphoproliferative Syndrome (ALPS) like disease is typically characterized by lymphadenopathy, hepatosplenomegaly, autoimmune cytopenias and an elevated number of double negative T cells (DNT cells, CD3+, TCRα/β+, CD4-, CD8-). 70% of patients suffering from classical ALPS harbor germline or somatic mutations in genes involved in the apoptotic FAS death receptor signaling pathway (FAS, FASLG or CASP10). For about 30% of ALPS or ALPS-like patients the genetic cause is unknown.
Aims
The objective of this study was to identify novel gene candidates underlying ALPS like disease of unknown genetic cause and to test potential targeted therapeutic approaches.
Methods
30 patients with clinical ALPS like symptoms, but without classical mutations were analyzed by whole-exome sequencing. Candidate genes were identified using an in-house developed bioinformatic analysis pipeline for gene prioritization. Candidate mutations were validated by Sanger sequencing. Their impact on Fas signaling and apoptosis was studied and potential therapeutic approaches tested.
Results
We identified two patients with de novo germline mutations (p.R278H, p.M394T) of the Signal Transducer And Activator Of Transcription 3 (STAT3). Elevated levels of phosphorylated STAT3 (pSTAT3-Tyr705) indicated constitutive activation of STAT3.Patient 1 presented with Coombs positive hemolytic anemia, thrombocytopenia, generalized progressive, non-infectious, non-malignant lymphadenopathy and splenomegaly at the age of nine. Immunophenotyping revealed increased numbers of DNT cells (20% in peripheral blood) and over time the patient developed panhypogammaglobulinemia. Patient 2 presented with early-onset insulin dependent diabetes mellitus and non-infectious, non-malignant lymphadenopathy, splenomegaly, thrombocytopenia, neutropenia and mild anemia. DNT cells and immunoglobulin levels were normal.We could demonstrate that constitutive activation of STAT3 led to decreased FAS expression on primary patient T cells and to reduced FAS ligand induced apoptosis similar to the effect of FAS mutations in classical ALPS. Therapeutic targeting of STAT3 is challenging and so far none of the developed STAT3 inhibitors has been approved for clinical use. To determine alternative targets we analyzed STAT3 signaling in primary and transformed lymphocytes of the patients. STAT3 gain-of-function mutations led to increased expression of STAT3 target genes, including SOCS3 and key anti-apoptotic factors of the BCL2 family of proteins (BCL-2, BCL-XL), whereas expression of pro-apoptotic factors (BAX, BAK) was decreased. Consistently, patient cells were resistant to cell death induced by stimuli (e.g. IL-21, staurosporine) mediating cell death via the BCL2 protein family. Treatment with a STAT3-specific inhibitor (S3I-201) normalized the expression of these factors and rescued the apoptotic response. Cells harboring STAT3 mutations were significantly more sensitive than normal cells to death induced by the BH3 mimetic inhibitor ABT-737 that targets BCL2, BCL-XL and BCL-W providing proof-of-concept evidence and indicating a novel therapeutic option.
Conclusion
We report here on dominant STAT3 gain-of-function mutations that caused clinical phenotypes similar to ALPS like disease. We demonstrated that constitutive active STAT3 caused decreased FAS expression and a skewed balance of pro- and antiapoptotic BCL-2 factors resulting in apoptosis evasion that may be therapeutically targeted by BH3 mimetics.
Session topic: Non-malignant hematopoietic disorders
Keyword(s): Autoimmune disease, BCL2, Fas, Lymphoproliferative disorder
Type: Oral Presentation
Presentation during EHA21: On Sunday, June 12, 2016 from 08:15 - 08:30
Location: Room H5
Background
Autoimmune Lymphoproliferative Syndrome (ALPS) like disease is typically characterized by lymphadenopathy, hepatosplenomegaly, autoimmune cytopenias and an elevated number of double negative T cells (DNT cells, CD3+, TCRα/β+, CD4-, CD8-). 70% of patients suffering from classical ALPS harbor germline or somatic mutations in genes involved in the apoptotic FAS death receptor signaling pathway (FAS, FASLG or CASP10). For about 30% of ALPS or ALPS-like patients the genetic cause is unknown.
Aims
The objective of this study was to identify novel gene candidates underlying ALPS like disease of unknown genetic cause and to test potential targeted therapeutic approaches.
Methods
30 patients with clinical ALPS like symptoms, but without classical mutations were analyzed by whole-exome sequencing. Candidate genes were identified using an in-house developed bioinformatic analysis pipeline for gene prioritization. Candidate mutations were validated by Sanger sequencing. Their impact on Fas signaling and apoptosis was studied and potential therapeutic approaches tested.
Results
We identified two patients with de novo germline mutations (p.R278H, p.M394T) of the Signal Transducer And Activator Of Transcription 3 (STAT3). Elevated levels of phosphorylated STAT3 (pSTAT3-Tyr705) indicated constitutive activation of STAT3.Patient 1 presented with Coombs positive hemolytic anemia, thrombocytopenia, generalized progressive, non-infectious, non-malignant lymphadenopathy and splenomegaly at the age of nine. Immunophenotyping revealed increased numbers of DNT cells (20% in peripheral blood) and over time the patient developed panhypogammaglobulinemia. Patient 2 presented with early-onset insulin dependent diabetes mellitus and non-infectious, non-malignant lymphadenopathy, splenomegaly, thrombocytopenia, neutropenia and mild anemia. DNT cells and immunoglobulin levels were normal.We could demonstrate that constitutive activation of STAT3 led to decreased FAS expression on primary patient T cells and to reduced FAS ligand induced apoptosis similar to the effect of FAS mutations in classical ALPS. Therapeutic targeting of STAT3 is challenging and so far none of the developed STAT3 inhibitors has been approved for clinical use. To determine alternative targets we analyzed STAT3 signaling in primary and transformed lymphocytes of the patients. STAT3 gain-of-function mutations led to increased expression of STAT3 target genes, including SOCS3 and key anti-apoptotic factors of the BCL2 family of proteins (BCL-2, BCL-XL), whereas expression of pro-apoptotic factors (BAX, BAK) was decreased. Consistently, patient cells were resistant to cell death induced by stimuli (e.g. IL-21, staurosporine) mediating cell death via the BCL2 protein family. Treatment with a STAT3-specific inhibitor (S3I-201) normalized the expression of these factors and rescued the apoptotic response. Cells harboring STAT3 mutations were significantly more sensitive than normal cells to death induced by the BH3 mimetic inhibitor ABT-737 that targets BCL2, BCL-XL and BCL-W providing proof-of-concept evidence and indicating a novel therapeutic option.
Conclusion
We report here on dominant STAT3 gain-of-function mutations that caused clinical phenotypes similar to ALPS like disease. We demonstrated that constitutive active STAT3 caused decreased FAS expression and a skewed balance of pro- and antiapoptotic BCL-2 factors resulting in apoptosis evasion that may be therapeutically targeted by BH3 mimetics.
Session topic: Non-malignant hematopoietic disorders
Keyword(s): Autoimmune disease, BCL2, Fas, Lymphoproliferative disorder
{{ help_message }}
{{filter}}