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Quantitation of resistance to cytosine arabinoside by myeloid leukemic cells expressing bcl‐2
Author(s) -
Guedez Liliana,
Suresh Alaparthy,
Tung Frank,
Zucali James
Publication year - 1996
Publication title -
european journal of haematology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.904
H-Index - 84
eISSN - 1600-0609
pISSN - 0902-4441
DOI - 10.1111/j.1600-0609.1996.tb01353.x
Subject(s) - clonogenic assay , apoptosis , cytarabine , myeloid leukemia , flow cytometry , biology , myeloid , microbiology and biotechnology , dna fragmentation , cancer research , cell culture , transfection , immunology , programmed cell death , biochemistry , genetics
The presence of bcl‐2 in myeloid leukemias has been associated with a decrease in therapy‐induced apoptosis, reduced patient survival and in vitro autonomous growth of leukemic cells. The present study focuses on the quantitation of resistance to increasing doses of 1‐β‐d‐arabinofuranosylcytosine (Ara‐C) by using hematological tumors expressing different levels of bcl‐2. Scanning densitometry of Western blots demonstrated that the myeloid U‐937 cells express low levels of bcl‐2 (RD=0.008), whereas the follicular lymphoma RL‐7 expressed very high levels (RD=3.084). Colony formation was also examined following incubation with Ara‐C and RL‐7 cells demonstrated a higher clonogenic survival (LD 50 =0.5 μm) when compared with U‐937 cells (LD 50 =0.005 μ m ). Similarly, the level of bcl‐2 expression in each cell line was also related to apoptosis with U‐937 cells demonstrating increased DNA fragmentation when compared with RL‐7 cells. To further evaluate the effect of upregulated bcl‐2 on Ara‐C treatment, U‐937 cells were transfected with a retroviral vector carrying the murine bcl‐2 or vector alone. Upregulation of bcl‐2 by myeloid leukemic cells increased the resistance by 3 logs to Ara‐C when comparing LD 50 values from clonogenic assays, and decreased apoptosis by at least 3 logs when measuring dUTP positive cells by flow cytometry.