The Wnt signaling pathway regulates Nalm-16 b-cell precursor acute lymphoblastic leukemic cell line survival and etoposide resistance.
B-cell precursor acute lymphoblastic leukemia (BCP-ALL) is the most common malignancy in children. The Wnt signaling pathway has been found to be extensively involved in cancer onset and progression but its role in BCP-ALL remains controversial. We evaluate the role of the Wnt pathway in maintenance of BCP-ALL cells and resistance to chemotherapy. Gene expression profile revealed that BCP-ALL cells are potentially sensitive to modulation of Wnt pathway. Nalm-16 and Nalm-6 cell lines displayed low levels of canonical activation, as reflected by the virtually complete absence of total beta-catenin in Nalm-6 and the beta-catenin cell membrane distribution in Nalm-16 cell line. Canonical activation with Wnt3a induced nuclear beta-catenin translocation and led to BCP-ALL cell death. Lithium chloride (LiCl) also induced a cytotoxic effect on leukemic cells. In contrast, both Wnt5a and Dkk-1 increased Nalm-16 cell survival. Also, Wnt3a enhanced the in vitro sensitivity of Nalm-16 to etoposide (VP-16) while treatment with canonical antagonists protected leukemic cells from chemotherapy-induced cell death. Overall, our results suggest that canonical activation of the Wnt pathway may exerts a tumor suppressive effect, thus its inhibition may support BCP-ALL cell survival.
Hospital Universitário Clementino Fraga Filho and Departamento de Histologia e Embriologia, Instituto de Ciências Biomédicas, Universidade Federal do Rio de Janeiro, Rio de Janeiro, Brazil. leandrothiago@terra.com.br
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Thiago
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Costa
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Lopes
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Otazu
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Nowill
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Mendes
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Portilho
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Abreu
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Mermelstein
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Orfao
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Borojevic
D000972:Antineoplastic Agents, Phytogenic / Q000494:pharmacology*; D016923:Cell Death / Q000187:drug effects; D045744:Cell Line, Tumor; D002470:Cell Survival / Q000187:drug effects; D019008:Drug Resistance, Neoplasm / Q000187:drug effects; D005047:Etoposide / Q000494:pharmacology*; D015972:Gene Expression Regulation, Neoplastic; D006801:Humans; D015452:Precursor B-Cell Lymphoblastic Leukemia-Lymphoma / Q000188:drug therapy* / Q000503:physiopathology; D021381:Protein Transport; D015398:Signal Transduction; D051153:Wnt Proteins / Q000378:metabolism*; D051176:beta Catenin / Q000378:metabolism
D000972:Antineoplastic Agents, Phytogenic; D051153:Wnt Proteins; D051176:beta Catenin; D005047:Etoposide