[Effect of hexamethylene bisacetamine on proliferation and apoptosis of human leukemia cells in vitro and relevant mechanisms].
OBJECTIVE
To investigate the in vitro effect of hexamethylene bisacetamine (HMBA) on the proliferation, cell cycle regulation, and apoptosis of human leukemia cells and to study the relevant mechanisms.


METHODS
K562 and U937 human leukemia cells were cultured and then suspensions thereof without HMBA or with HMBA of different concentrations (1, 2, and 4 mmol/L) were made. The optical absorbance value at 595 nm of these suspensions were tested every 24 hours. The suspensions were mixed with 4% trypan blue dye solution. Live and dead cells were observed with microscope and the live cell rate was calculated. Double staining of cellular cyclin A protein/DNA was used to detect the expression levels of cyclin A protein in cytoplasm. Fluorescein isothiocyanate (FITC)-labeled annexin V/Propidiumiodide) was used to detect the apototic cells fluorescence-activated cell sorter. Gel electrophoresis was conducted to detect DNA contents.


RESULTS
After exposure to HMBA for 6 days, the optical absorbance values at 595nm of K562 leukemia cells of the control group and groups with 1, 2, and 4mmol/L HMBA were 1.03, 0.81, 0.58, and 0.36 respectively. After treatment of HMBA, the percentages of cyclin A positive K562 leukemia cells in control group and groups with 1, 2, and 4 mmol/L HMBA were 34.4% +/- 5.2%, 16.1% +/- 2.5%, 9.9% +/- 1.7%, and 7.6% +/- 2.0% respectively (P < 0.01). No drug-related apoptosis was found in both cell lines.


CONCLUSIONS
HMBA inhibits cell proliferation and reduces S-phase-fraction in both cell lines dose-dependently through down-regulating the expression of cyclin A. Apoptosis is not a consequence of the proceeding mitosis arrest and is induced p53-dependently by HMBA. In both leukemia cell lines (U937 and K562) lacking wt-p53, a nonapoptotic death pathway may exist during HMBA induction.
Department of Hematology, Huashan Hospital, Medical Center of Fudan University, Shanghai 200040, China.
Hui
H
Yu
Huazhong
H
Lu
Bin
B
Zheng
Huahua
H
Fan
Yi
Y
Xie
D000081:Acetamides / Q000494:pharmacology*; D000970:Antineoplastic Agents / Q000494:pharmacology*; D017209:Apoptosis; D002455:Cell Division / Q000187:drug effects; D019925:Cyclin A / Q000096:biosynthesis; D004273:DNA, Neoplasm / Q000032:analysis; D004305:Dose-Response Relationship, Drug; D004587:Electrophoresis, Agar Gel / Q000379:methods; D006801:Humans; D020014:K562 Cells; D007938:Leukemia; D016196:S Phase; D014407:Tumor Cells, Cultured; D020298:U937 Cells
D000081:Acetamides; D000970:Antineoplastic Agents; D019925:Cyclin A; D004273:DNA, Neoplasm; C014026:hexamethylene bisacetamide