Kyogo Suzuki1, Yusuke Okuno1, Nozomu Kawashima1, Hideki Muramatsu1, Tatsuya Okuno1, Xinan Wang1, Shinsuke Kataoka1, Yuko Sekiya1, Motoharu Hamada1, Norihiro Murakami1, Daiei Kojima1, Kotaro Narita1, Atsushi Narita1, Hirotoshi Sakaguchi1, Kimiyoshi Sakaguchi1, Nao Yoshida1, Nobuhiro Nishio1, Asahito Hama1, Yoshiyuki Takahashi1, Kazuko Kudo1, Koji Kato1, Seiji Kojima2. 1. Kyogo Suzuki, Yusuke Okuno, Nozomu Kawashima, Hideki Muramatsu, Tatsuya Okuno, Xinan Wang, Shinsuke Kataoka, Yuko Sekiya, Motoharu Hamada, Norihiro Murakami, Daiei Kojima, Atsushi Narita, Nobuhiro Nishio, Asahito Hama, Yoshiyuki Takahashi, and Seiji Kojima, Nagoya University Graduate School of Medicine; Yusuke Okuno and Nobuhiro Nishio, Nagoya University Hospital; Kotaro Narita, Hirotoshi Sakaguchi, Nao Yoshida, and Koji Kato, Children's Medical Center, Japanese Red Cross Nagoya First Hospital, Nagoya; Kimiyoshi Sakaguchi, Hamamatsu University School of Medicine, Hamamatsu; and Kazuko Kudo, Fujita Health University School of Medicine, Toyoake, Japan. 2. Kyogo Suzuki, Yusuke Okuno, Nozomu Kawashima, Hideki Muramatsu, Tatsuya Okuno, Xinan Wang, Shinsuke Kataoka, Yuko Sekiya, Motoharu Hamada, Norihiro Murakami, Daiei Kojima, Atsushi Narita, Nobuhiro Nishio, Asahito Hama, Yoshiyuki Takahashi, and Seiji Kojima, Nagoya University Graduate School of Medicine; Yusuke Okuno and Nobuhiro Nishio, Nagoya University Hospital; Kotaro Narita, Hirotoshi Sakaguchi, Nao Yoshida, and Koji Kato, Children's Medical Center, Japanese Red Cross Nagoya First Hospital, Nagoya; Kimiyoshi Sakaguchi, Hamamatsu University School of Medicine, Hamamatsu; and Kazuko Kudo, Fujita Health University School of Medicine, Toyoake, Japan. kojimas@med.nagoya-u.ac.jp.
Abstract
PURPOSE: Acute lymphoblastic leukemia (ALL) makes up a significant proportion of all pediatric cancers, and relapsed ALL is a leading cause of cancer-associated deaths in children. Identification of risk factors and druggable molecular targets in ALL can lead to a better stratification of treatments and subsequent improvement in prognosis. PATIENTS AND METHODS: We enrolled 59 children with relapsed or primary refractory ALL who were treated in our institutions. We primarily performed RNA sequencing (RNA-seq) using patients' leukemic cells to comprehensively detect gene fusions and analyze gene expression profiles. On the basis of results obtained by RNA-seq, we performed genetic validation, functional analysis, and in vitro drug sensitivity testing using patients' samples and an exogenous expression model. RESULTS: We identified a total of 26 gene fusions in 22 patients by RNA-seq. Among these, 19 were nonrandom gene fusions already described in ALL, and four of the remaining seven involved identical combination of MEF2D and BCL9. All MEF2D-BCL9-positive patients had B-cell precursor immunophenotype and were characterized as being older in age, being resistant to chemotherapy, having very early relapse, and having leukemic blasts that mimic morphologically mature B-cell leukemia with markedly high expression of HDAC9. Exogenous expression of MEF2D-BCL9 in a B-cell precursor ALL cell line promoted cell growth, increased HDAC9 expression, and induced resistance to dexamethasone. Using a primary culture of leukemic blasts from a patient, we identified several molecular targeted drugs that conferred inhibitory effects in vitro. CONCLUSION: A novel MEF2D-BCL9 fusion we identified characterizes a novel subset of pediatric ALL, predicts poor prognosis, and may be a candidate for novel molecular targeting.
PURPOSE:Acute lymphoblastic leukemia (ALL) makes up a significant proportion of all pediatric cancers, and relapsed ALL is a leading cause of cancer-associated deaths in children. Identification of risk factors and druggable molecular targets in ALL can lead to a better stratification of treatments and subsequent improvement in prognosis. PATIENTS AND METHODS: We enrolled 59 children with relapsed or primary refractory ALL who were treated in our institutions. We primarily performed RNA sequencing (RNA-seq) using patients' leukemic cells to comprehensively detect gene fusions and analyze gene expression profiles. On the basis of results obtained by RNA-seq, we performed genetic validation, functional analysis, and in vitro drug sensitivity testing using patients' samples and an exogenous expression model. RESULTS: We identified a total of 26 gene fusions in 22 patients by RNA-seq. Among these, 19 were nonrandom gene fusions already described in ALL, and four of the remaining seven involved identical combination of MEF2D and BCL9. All MEF2D-BCL9-positive patients had B-cell precursor immunophenotype and were characterized as being older in age, being resistant to chemotherapy, having very early relapse, and having leukemic blasts that mimic morphologically mature B-cell leukemia with markedly high expression of HDAC9. Exogenous expression of MEF2D-BCL9 in a B-cell precursor ALL cell line promoted cell growth, increased HDAC9 expression, and induced resistance to dexamethasone. Using a primary culture of leukemic blasts from a patient, we identified several molecular targeted drugs that conferred inhibitory effects in vitro. CONCLUSION: A novel MEF2D-BCL9 fusion we identified characterizes a novel subset of pediatric ALL, predicts poor prognosis, and may be a candidate for novel molecular targeting.
Authors: Zhaohui Gu; Michelle L Churchman; Kathryn G Roberts; Ian Moore; Xin Zhou; Joy Nakitandwe; Kohei Hagiwara; Stephane Pelletier; Sebastien Gingras; Hartmut Berns; Debbie Payne-Turner; Ashley Hill; Ilaria Iacobucci; Lei Shi; Stanley Pounds; Cheng Cheng; Deqing Pei; Chunxu Qu; Scott Newman; Meenakshi Devidas; Yunfeng Dai; Shalini C Reshmi; Julie Gastier-Foster; Elizabeth A Raetz; Michael J Borowitz; Brent L Wood; William L Carroll; Patrick A Zweidler-McKay; Karen R Rabin; Leonard A Mattano; Kelly W Maloney; Alessandro Rambaldi; Orietta Spinelli; Jerald P Radich; Mark D Minden; Jacob M Rowe; Selina Luger; Mark R Litzow; Martin S Tallman; Janis Racevskis; Yanming Zhang; Ravi Bhatia; Jessica Kohlschmidt; Krzysztof Mrózek; Clara D Bloomfield; Wendy Stock; Steven Kornblau; Hagop M Kantarjian; Marina Konopleva; Williams E Evans; Sima Jeha; Ching-Hon Pui; Jun Yang; Elisabeth Paietta; James R Downing; Mary V Relling; Jinghui Zhang; Mignon L Loh; Stephen P Hunger; Charles G Mullighan Journal: Nat Genet Date: 2019-01-14 Impact factor: 38.330