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Acquired mutations in BCL2 family proteins conferring resistance to the BH3 mimetic ABT-199 in lymphoma.

Blood (2014-05-03)
Vicente Fresquet, Melissa Rieger, Carlo Carolis, Maria J García-Barchino, Jose A Martinez-Climent
ABSTRACT

Acquired resistance to targeted drugs is emerging as an obstacle to successful cancer treatment. Recently, a BCL2-selective BH3 mimetic termed ABT-199 showed promising therapeutic results in BCL2-dependent tumors. Based on its high affinity for BCL2, we studied potential mechanisms conferring resistance upon ABT-199 therapy, aiming to anticipate its occurrence in the clinic. Two models of resistant lymphomas were established by continuous ABT-199 exposure. In resistant Bcl2-expressing mouse lymphoma cells, 2 missense mutations within the Bcl2 BH3 domain were identified. Both F101C and F101L mutations impeded ABT-199 binding to the BH3 domain, therefore suppressing mitochondrial apoptosis. In resistant human lymphoma cells, a missense mutation in the C-terminal transmembrane domain of proapoptotic BAX (G179E) was found, which abrogated BAX anchoring to mitochondria and blocked ABT-199-induced apoptosis both in vitro and in vivo. Importantly, G179E BAX mutation also induced partial cross-resistance to other antineoplastic drugs. Our study reveals the acquisition of mutations in BCL2 family proteins as a novel mechanism of apoptosis resistance in cancer. These results anticipate the potential development of such mutations in patients treated with ABT-199, providing a basis to preventing their occurrence and to designing drugs able to circumvent the acquired resistance.

MATERIALS
Product Number
Brand
Product Description

Sigma-Aldrich
cis-Diammineplatinum(II) dichloride, crystalline
Cisplatin, European Pharmacopoeia (EP) Reference Standard
Sigma-Aldrich
cis-Diamineplatinum(II) dichloride, ≥99.9% trace metals basis
Sigma-Aldrich
Temsirolimus, ≥98% (HPLC)
Sigma-Aldrich
trans-Platinum(II)diammine dichloride
Cisplatin impurity A, European Pharmacopoeia (EP) Reference Standard
USP
Transplatin, United States Pharmacopeia (USP) Reference Standard