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HSP70/HSF1 axis, regulated via a PI3K/AKT pathway, is a druggable target in chronic lymphocytic leukemia
Author(s) -
Frezzato Federica,
Raggi Flavia,
Martini Veronica,
Severin Filippo,
Trimarco Valentina,
Visentin Andrea,
Scomazzon Edoardo,
Accordi Benedetta,
Bresolin Silvia,
Piazza Francesco,
Facco Monica,
Basso Giuseppe,
Semenzato Gianpietro,
Trentin Livio
Publication year - 2019
Publication title -
international journal of cancer
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.475
H-Index - 234
eISSN - 1097-0215
pISSN - 0020-7136
DOI - 10.1002/ijc.32383
Subject(s) - hsf1 , hsp70 , protein kinase b , chronic lymphocytic leukemia , pi3k/akt/mtor pathway , cancer research , biology , leukemia , heat shock protein , signal transduction , microbiology and biotechnology , chemistry , immunology , biochemistry , gene
Considering the role played by the heat shock protein of 70 kDa (HSP70) in cancer, we characterized this protein and its major regulator, the heat shock factor 1 (HSF1), in chronic lymphocytic leukemia (CLL). We found both HSP70 and HSF1 overexpressed in CLL patients, correlated to poor prognosis and abnormally localized in the nucleus of leukemic B cells. The two proteins were strictly correlated each other and their levels decreased consensually in those patients responding to in vivo therapeutic regimens. HSP70 and HSF1 inhibition was proved to be effective in inducing a dose‐dependent in vitro apoptosis of CLL B cells. Considering that HSF1 is finely regulated by kinases belonging to pathways triggered by rat sarcoma (RAS), we benefited from a previous proteomic study performed in CLL patients aiming to assess the activation/expression of key signaling proteins. We found that patients showing high levels of HSP70 also expressed high Akt‐Ser473, thus activating HSF1. Inhibition of PI3K, which activates AKT, reduced the expression of HSF1 and HSP70. By contrast, HSP70‐low patients displayed high activation of MEK1/2 and ERK1/2, known to negatively regulate HSF1. These data demonstrate that the HSP70 expression is regulated by the modulation of HSF1 activity through the activation of RAS‐regulated pathways and suggest the HSP70/HSF1 interplay as an interesting target for antileukemic therapies. Finally, inhibition of PI3K, that activates AKT, reduced the expression of HSF1 and HSP70.