Effect of Methotrexate on Cell Growth of Human Monocyte-like
Cell Line U937 and Its Induction of Apoptosis
Ye Hui,
Gu Longjun, Chen Hongxin, Chen Jing, Ye Yuchen, Xue Huiliang
Shanghai Children’s Medical
Center, Shanghai Second Medical University,
Shanghai, China
Objective:
To
explore the novel approach of treatment in the patients with acute
monocytic leukemia (AML-M5),
Methods: The U937 cell line,
which has the monocytic characters, was used. Cell growth inhibition was
measured by XTT assay after 24 and 48 hours in the continuous presence of
various concentrations ranging from 1nmol/L to 100 mmol/L. To understand the
mechanism of MTX cytotoxicity, a variety of assay, including trypan blue
exclusion, flow cytometry, light microscopy (Wright’s staining) and DNA
fragment electrophoresis, were performed.
Results: After 24 hours
treatment, IC50 value for U937 cell was 0.04mmol/L. After 48 hours
treatment, the IC50 was 0.037 mmol/L and IC90 was 0.39mmol/L. There were no
significant apoptotic changes after shorter exposure of MTX (4 and 6
hours). After 8 hours at various concentrations of MTX treatment ranging
from 5 nmol/L to 10 mmol/L, the percentage of
the cells in the pre-G1 (apoptotic) was 3.2% at 0.1 mmol/L and it reached a
peak of 18.2% at 5.0 mmol/L. The DNA synthesis
in S-phase was inhibited from 41.2% (0.01 mmol/L) to 19.1% (10 mmol/L). DNA ladder band,
a feature of apoptosis, was observed.
Conclusion:
The
arrest of cell growth and the apoptotic properties induced by MTX have lead
to its evaluation as a potentially therapeutic agent in the treatment of
AML-M5.