Kim De Keersmaecker | KU Leuven (original) (raw)
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Papers by Kim De Keersmaecker
Blood, 2017
T-cell acute lymphoblastic leukemia (T-ALL) is an aggressive malignancy caused by the accumulatio... more T-cell acute lymphoblastic leukemia (T-ALL) is an aggressive malignancy caused by the accumulation of genomic lesions that affect the development of T-cells. Since many years, it has been established that deregulated expression of transcription factors, impairment of the CDKN2A/2B cell cycle regulators and hyperactive NOTCH1 signaling play prominent roles in the pathogenesis of this leukemia. In the past decade, systematic screening of T-ALL genomes by high resolution copy number arrays and next- generation sequencing technologies has revealed that T-cell progenitors accumulate additional mutations affecting JAK/STAT signaling, protein translation and epigenetic control, providing novel attractive targets for therapy. In this review, we provide an update on our knowledge on T-ALL pathogenesis, on the opportunities for the introduction of targeted therapy and on the challenges that are still ahead.
Ash Annual Meeting Abstracts, Nov 16, 2006
Haematologica, 2005
Over the past 20 years, a large number of genes involved in the pathogenesis of T-cell acute lymp... more Over the past 20 years, a large number of genes involved in the pathogenesis of T-cell acute lymphoblastic leukemia (T-ALL) has been identified by molecular characterization of recurrent chromosomal aberrations and more subtle genetic defects. When reviewing the current list of oncogenes and tumor suppressor genes, it becomes clear that these can be grouped into four classes of mutations, which are involved in: (i) cell cycle deregulation; (ii) impaired differentiation; (iii) proliferation and survival advantage and (iv) unlimited self-renewal capacity. Based on recent studies of T-ALL, we can speculate that at least these four different mutations are required for the development of T-ALL. In this review we summarize our current insights into the molecular pathogenesis of T-ALL, and we discuss how these molecular findings provide new directions for future research and novel therapeutic strategies in T-ALL.
Blood, 2015
Ribosomopathies are largely congenital diseases linked to defects in ribosomal proteins or biogen... more Ribosomopathies are largely congenital diseases linked to defects in ribosomal proteins or biogenesis factors. Some of these disorders are characterized by hypoproliferative phenotypes such as bone marrow failure and anemia early in life, followed by elevated cancer risks later in life. This transition from hypo-to hyperproliferation presents an intriguing paradox in the field of hematology known as "Dameshek's riddle." Recent cancer sequencing studies also revealed somatically acquired mutations and deletions in ribosomal proteins in T-cell acute lymphoblastic leukemia and solid tumors, further extending the list of ribosomopathies and strengthening the association between ribosomal defects and oncogenesis. In this perspective, we summarize and comment on recent findings in the field of ribosomopathies. We explain how ribosomopathies may provide clues to help explain Dameshek's paradox and highlight some of the open questions and challenges in the field. (Blood. 2015;125(9): 1377-1382
Proceedings of the National Academy of Sciences, 2014
Leukemia, 2008
The NUP214-ABL1 fusion kinase has recently been identified in 6% of patients with T-cell acute ly... more The NUP214-ABL1 fusion kinase has recently been identified in 6% of patients with T-cell acute lymphoblastic leukemia. In contrast to the more common oncogenic ABL1 fusion BCR-ABL1, NUP214-ABL1 localizes to the nuclear pore complexes and has attenuated transforming properties in hematopoietic cells and in mouse bone marrow transplant models. We have performed a thorough biochemical comparative analysis of NUP214-ABL1 and BCR-ABL1 and show that, despite their common tyrosine kinase domain, the two fusion proteins differ in many critical catalytic properties. NUP214-ABL1 has lower in vitro tyrosine kinase activity, which is in agreement with the absence of phosphorylation on its activation loop. NUP214-ABL1 was more sensitive to imatinib (Glivec) than BCR-ABL1 in vitro and in cells, indicating a different activation state and conformation of the two ABL1 fusion kinases. Using a peptide array, we identified differences in the spectrum and efficiency of substrate peptide phosphorylation and a differential involvement of Src kinases in downstream signaling. These results clearly indicate that different fusion partners of the same kinase can determine not only localization, but also critical functional properties of the enzyme such as inhibitor sensitivity and substrate preference, with subsequent differences in downstream signaling effectors and likely consequences in disease pathogenesis.
Blood, 2005
The BCR-ABL1 fusion kinase is frequently associated with chronic myeloid leukemia and B-cell acut... more The BCR-ABL1 fusion kinase is frequently associated with chronic myeloid leukemia and B-cell acute lymphoblastic leukemia but is rare in T-cell acute lymphoblastic leukemia (T-ALL). We recently identified NUP214-ABL1 as a variant ABL1 fusion gene in 6% of T-ALL patients. Here we describe the identification of another ABL1 fusion, EML1-ABL1, in a T-ALL patient with a cryptic t(9;14)(q34;q32) associated with deletion of CDKN2A (p16) and expression of TLX1 (HOX11). Echinoderm microtubule-associated protein-like 1-Abelson 1 (EML1-ABL1) is a constitutively phosphorylated tyrosine kinase that transforms Ba/F3 cells to growth factor-independent growth through activation of survival and proliferation pathways, including extracellular signal-related kinase 1/2 (Erk1/2), signal transducers and activators of transcription 5 (Stat5), and Lyn kinase. Deletion of the coiled-coil domain of EML1 abrogated the transforming proper-ties of the fusion kinase. EML1-ABL1 and breakpoint cluster region (BCR)-ABL1 were equally sensitive to the tyrosine kinase inhibitor imatinib. These data further demonstrate the involvement of ABL1 fusions in the pathogenesis of T-ALL and identify EML1-ABL1 as a novel therapeutic target of imatinib. (Blood. 2005;105:4849-4852)
Haematologica, Jan 20, 2017
Proceedings of the National Academy of Sciences of the United States of America, Jan 21, 2017
The Notch1 gene is a major oncogenic driver and therapeutic target in T-cell acute lymphoblastic ... more The Notch1 gene is a major oncogenic driver and therapeutic target in T-cell acute lymphoblastic leukemia (T-ALL). However, inhibition of NOTCH signaling with γ-secretase inhibitors (GSIs) has shown limited antileukemic activity in clinical trials. Here we performed an expression-based virtual screening to identify highly active antileukemic drugs that synergize with NOTCH1 inhibition in T-ALL. Among these, withaferin A demonstrated the strongest cytotoxic and GSI-synergistic antileukemic effects in vitro and in vivo. Mechanistically, network perturbation analyses showed eIF2A-phosphorylation-mediated inhibition of protein translation as a critical mediator of the antileukemic effects of withaferin A and its interaction with NOTCH1 inhibition. Overall, these results support a role for anti-NOTCH1 therapies and protein translation inhibitor combinations in the treatment of T-ALL.
Oncotarget, 2015
For many years, defects in the ribosome have been associated to cancer. Recently, somatic mutatio... more For many years, defects in the ribosome have been associated to cancer. Recently, somatic mutations and deletions affecting ribosomal protein genes were identified in a few leukemias and solid tumor types. However, systematic analysis of all 81 known ribosomal protein genes across cancer types is lacking. We screened mutation and copy number data of respectively 4926 and 7322 samples from 16 cancer types and identified six altered genes (RPL5, RPL11, RPL23A, RPS5, RPS20 and RPSA). RPL5 was located at a significant peak of heterozygous deletion or mutated in 11% of glioblastoma, 28% of melanoma and 34% of breast cancer samples. Moreover, patients with low RPL5 expression displayed worse overall survival in glioblastoma and in one breast cancer cohort. RPL5 knockdown in breast cancer cell lines enhanced G2/M cell cycle progression and accelerated tumor progression in a xenograft mouse model. Interestingly, our data suggest that the tumor suppressor role of RPL5 is not only mediated by its known function as TP53 or c-MYC regulator. In conclusion, RPL5 heterozygous inactivation occurs at high incidence (11-34%) in multiple tumor types, currently representing the most common somatic ribosomal protein defect in cancer, and we demonstrate a tumor suppressor role for RPL5 in breast cancer.
Activating NOTCH1 mutations are common in T-cell acute lymphoblastic leukemia. Inhibition of NOTC... more Activating NOTCH1 mutations are common in T-cell acute lymphoblastic leukemia. Inhibition of NOTCH1 signaling with γ-secretase inhibitors causes cell cycle block, but only after treatment for several days. We further documented the effects of γ-secretase inhibitor treatment on T-cell acute lymphoblastic leukemia cell lines and tested whether combining γ-secretase inhibitors with other anti-cancer drugs offers a therapeutic advantage.
British Journal of Haematology, 2016
Diamond-Blackfan anaemia (DBA) is an inherited disease characterized by pure erythroid aplasia th... more Diamond-Blackfan anaemia (DBA) is an inherited disease characterized by pure erythroid aplasia that has been tagged as a 'ribosomopathy'. We report a multi-centre study focused on the analysis of rRNA processing of 53 Italian DBA patients using capillary electrophoresis analysis of rRNA maturation of the 40S and 60S ribosomal subunits. The ratio of 28S/18S rRNA was higher in patients with mutated ribosomal proteins (RPs) of the small ribosomal subunit. In contrast, patients with mutated RPs of the large ribosomal subunit (RPLs) had a lower 28S/18S ratio. The assay reported here would be amenable for development as a diagnostic tool.
Molecular Pathology Library, 2010
Page 1. Introduction Precursor T-cell lymphoblastic leukemias and lymphomas represent 15% of chil... more Page 1. Introduction Precursor T-cell lymphoblastic leukemias and lymphomas represent 15% of childhood acute lymphoblastic leukemias (ALLs) and one third of pediatric non-Hodgkin lympho-mas, respectively. T-cell ALLs ...
Blood, 2017
T-cell acute lymphoblastic leukemia (T-ALL) is an aggressive malignancy caused by the accumulatio... more T-cell acute lymphoblastic leukemia (T-ALL) is an aggressive malignancy caused by the accumulation of genomic lesions that affect the development of T-cells. Since many years, it has been established that deregulated expression of transcription factors, impairment of the CDKN2A/2B cell cycle regulators and hyperactive NOTCH1 signaling play prominent roles in the pathogenesis of this leukemia. In the past decade, systematic screening of T-ALL genomes by high resolution copy number arrays and next- generation sequencing technologies has revealed that T-cell progenitors accumulate additional mutations affecting JAK/STAT signaling, protein translation and epigenetic control, providing novel attractive targets for therapy. In this review, we provide an update on our knowledge on T-ALL pathogenesis, on the opportunities for the introduction of targeted therapy and on the challenges that are still ahead.
Ash Annual Meeting Abstracts, Nov 16, 2006
Haematologica, 2005
Over the past 20 years, a large number of genes involved in the pathogenesis of T-cell acute lymp... more Over the past 20 years, a large number of genes involved in the pathogenesis of T-cell acute lymphoblastic leukemia (T-ALL) has been identified by molecular characterization of recurrent chromosomal aberrations and more subtle genetic defects. When reviewing the current list of oncogenes and tumor suppressor genes, it becomes clear that these can be grouped into four classes of mutations, which are involved in: (i) cell cycle deregulation; (ii) impaired differentiation; (iii) proliferation and survival advantage and (iv) unlimited self-renewal capacity. Based on recent studies of T-ALL, we can speculate that at least these four different mutations are required for the development of T-ALL. In this review we summarize our current insights into the molecular pathogenesis of T-ALL, and we discuss how these molecular findings provide new directions for future research and novel therapeutic strategies in T-ALL.
Blood, 2015
Ribosomopathies are largely congenital diseases linked to defects in ribosomal proteins or biogen... more Ribosomopathies are largely congenital diseases linked to defects in ribosomal proteins or biogenesis factors. Some of these disorders are characterized by hypoproliferative phenotypes such as bone marrow failure and anemia early in life, followed by elevated cancer risks later in life. This transition from hypo-to hyperproliferation presents an intriguing paradox in the field of hematology known as "Dameshek's riddle." Recent cancer sequencing studies also revealed somatically acquired mutations and deletions in ribosomal proteins in T-cell acute lymphoblastic leukemia and solid tumors, further extending the list of ribosomopathies and strengthening the association between ribosomal defects and oncogenesis. In this perspective, we summarize and comment on recent findings in the field of ribosomopathies. We explain how ribosomopathies may provide clues to help explain Dameshek's paradox and highlight some of the open questions and challenges in the field. (Blood. 2015;125(9): 1377-1382
Proceedings of the National Academy of Sciences, 2014
Leukemia, 2008
The NUP214-ABL1 fusion kinase has recently been identified in 6% of patients with T-cell acute ly... more The NUP214-ABL1 fusion kinase has recently been identified in 6% of patients with T-cell acute lymphoblastic leukemia. In contrast to the more common oncogenic ABL1 fusion BCR-ABL1, NUP214-ABL1 localizes to the nuclear pore complexes and has attenuated transforming properties in hematopoietic cells and in mouse bone marrow transplant models. We have performed a thorough biochemical comparative analysis of NUP214-ABL1 and BCR-ABL1 and show that, despite their common tyrosine kinase domain, the two fusion proteins differ in many critical catalytic properties. NUP214-ABL1 has lower in vitro tyrosine kinase activity, which is in agreement with the absence of phosphorylation on its activation loop. NUP214-ABL1 was more sensitive to imatinib (Glivec) than BCR-ABL1 in vitro and in cells, indicating a different activation state and conformation of the two ABL1 fusion kinases. Using a peptide array, we identified differences in the spectrum and efficiency of substrate peptide phosphorylation and a differential involvement of Src kinases in downstream signaling. These results clearly indicate that different fusion partners of the same kinase can determine not only localization, but also critical functional properties of the enzyme such as inhibitor sensitivity and substrate preference, with subsequent differences in downstream signaling effectors and likely consequences in disease pathogenesis.
Blood, 2005
The BCR-ABL1 fusion kinase is frequently associated with chronic myeloid leukemia and B-cell acut... more The BCR-ABL1 fusion kinase is frequently associated with chronic myeloid leukemia and B-cell acute lymphoblastic leukemia but is rare in T-cell acute lymphoblastic leukemia (T-ALL). We recently identified NUP214-ABL1 as a variant ABL1 fusion gene in 6% of T-ALL patients. Here we describe the identification of another ABL1 fusion, EML1-ABL1, in a T-ALL patient with a cryptic t(9;14)(q34;q32) associated with deletion of CDKN2A (p16) and expression of TLX1 (HOX11). Echinoderm microtubule-associated protein-like 1-Abelson 1 (EML1-ABL1) is a constitutively phosphorylated tyrosine kinase that transforms Ba/F3 cells to growth factor-independent growth through activation of survival and proliferation pathways, including extracellular signal-related kinase 1/2 (Erk1/2), signal transducers and activators of transcription 5 (Stat5), and Lyn kinase. Deletion of the coiled-coil domain of EML1 abrogated the transforming proper-ties of the fusion kinase. EML1-ABL1 and breakpoint cluster region (BCR)-ABL1 were equally sensitive to the tyrosine kinase inhibitor imatinib. These data further demonstrate the involvement of ABL1 fusions in the pathogenesis of T-ALL and identify EML1-ABL1 as a novel therapeutic target of imatinib. (Blood. 2005;105:4849-4852)
Haematologica, Jan 20, 2017
Proceedings of the National Academy of Sciences of the United States of America, Jan 21, 2017
The Notch1 gene is a major oncogenic driver and therapeutic target in T-cell acute lymphoblastic ... more The Notch1 gene is a major oncogenic driver and therapeutic target in T-cell acute lymphoblastic leukemia (T-ALL). However, inhibition of NOTCH signaling with γ-secretase inhibitors (GSIs) has shown limited antileukemic activity in clinical trials. Here we performed an expression-based virtual screening to identify highly active antileukemic drugs that synergize with NOTCH1 inhibition in T-ALL. Among these, withaferin A demonstrated the strongest cytotoxic and GSI-synergistic antileukemic effects in vitro and in vivo. Mechanistically, network perturbation analyses showed eIF2A-phosphorylation-mediated inhibition of protein translation as a critical mediator of the antileukemic effects of withaferin A and its interaction with NOTCH1 inhibition. Overall, these results support a role for anti-NOTCH1 therapies and protein translation inhibitor combinations in the treatment of T-ALL.
Oncotarget, 2015
For many years, defects in the ribosome have been associated to cancer. Recently, somatic mutatio... more For many years, defects in the ribosome have been associated to cancer. Recently, somatic mutations and deletions affecting ribosomal protein genes were identified in a few leukemias and solid tumor types. However, systematic analysis of all 81 known ribosomal protein genes across cancer types is lacking. We screened mutation and copy number data of respectively 4926 and 7322 samples from 16 cancer types and identified six altered genes (RPL5, RPL11, RPL23A, RPS5, RPS20 and RPSA). RPL5 was located at a significant peak of heterozygous deletion or mutated in 11% of glioblastoma, 28% of melanoma and 34% of breast cancer samples. Moreover, patients with low RPL5 expression displayed worse overall survival in glioblastoma and in one breast cancer cohort. RPL5 knockdown in breast cancer cell lines enhanced G2/M cell cycle progression and accelerated tumor progression in a xenograft mouse model. Interestingly, our data suggest that the tumor suppressor role of RPL5 is not only mediated by its known function as TP53 or c-MYC regulator. In conclusion, RPL5 heterozygous inactivation occurs at high incidence (11-34%) in multiple tumor types, currently representing the most common somatic ribosomal protein defect in cancer, and we demonstrate a tumor suppressor role for RPL5 in breast cancer.
Activating NOTCH1 mutations are common in T-cell acute lymphoblastic leukemia. Inhibition of NOTC... more Activating NOTCH1 mutations are common in T-cell acute lymphoblastic leukemia. Inhibition of NOTCH1 signaling with γ-secretase inhibitors causes cell cycle block, but only after treatment for several days. We further documented the effects of γ-secretase inhibitor treatment on T-cell acute lymphoblastic leukemia cell lines and tested whether combining γ-secretase inhibitors with other anti-cancer drugs offers a therapeutic advantage.
British Journal of Haematology, 2016
Diamond-Blackfan anaemia (DBA) is an inherited disease characterized by pure erythroid aplasia th... more Diamond-Blackfan anaemia (DBA) is an inherited disease characterized by pure erythroid aplasia that has been tagged as a 'ribosomopathy'. We report a multi-centre study focused on the analysis of rRNA processing of 53 Italian DBA patients using capillary electrophoresis analysis of rRNA maturation of the 40S and 60S ribosomal subunits. The ratio of 28S/18S rRNA was higher in patients with mutated ribosomal proteins (RPs) of the small ribosomal subunit. In contrast, patients with mutated RPs of the large ribosomal subunit (RPLs) had a lower 28S/18S ratio. The assay reported here would be amenable for development as a diagnostic tool.
Molecular Pathology Library, 2010
Page 1. Introduction Precursor T-cell lymphoblastic leukemias and lymphomas represent 15% of chil... more Page 1. Introduction Precursor T-cell lymphoblastic leukemias and lymphomas represent 15% of childhood acute lymphoblastic leukemias (ALLs) and one third of pediatric non-Hodgkin lympho-mas, respectively. T-cell ALLs ...