[Activation of adenylate cyclase influences the sensitivity of acute promyelocytic leukemia cell lines to ATRA].
OBJECTIVE
To explore the molecular mechanism of APL cell resistance to ATRA.


METHODS
The ATRA sensitive and resistant APL cell lines, NB4 and NB4-R1, were used as in vitro models. The effects of specific inhibitors and activators of adenylate cyclase (AC) and phosphodiesterase (PDE) on ATRA-induced differentiation was evaluated by cell morphology, cell surface antigen expression and nitroblue-tetrazolium (NBT) reduction assays.


RESULTS
SQ22536, a specific antagonist of AC, could dramatically block ATRA-induced NB4 cell differentiation. When ATRA + SQ22536 group compared with ATRA group, the positivity of CD11b decreased from (95.9 +/- 2.5)% to (60.3 +/- 7.1)%, while the A(540) in NBT reduction assay decreased from 0.585 +/- 0.092 to 0.170 +/- 0.028 (P < 0.05). Forskolin, an agonist of AC, could overcome the resistance of NB4-R1 cells to ATRA. When ATRA + forskolin group compared with ATRA group, the positivity of CD11b increased from (34.3 +/- 5.3)% to (94.6 +/- 2.4)%, while the A(540) in NBT reduction assay increased from 0.110 +/- 0.028 to 0.395 +/- 0.049 (P < 0.05). In contrast, the specific antagonist and agonist of PDE, 3-isobutyl-1-methylxanthine (IBMX) and calmodulin, exerted little impact on ATRA treatment.


CONCLUSIONS
The defaults in the initiation of AC activation may contribute to the resistance to ATRA in some APL cells.
Dou
Ai-xia
AX
Shanghai Institute of Hematology, Ruijin Hospital, Shanghai Second Medical University, Shanghai 200025, China.
Jia
Pei-min
PM
Zhu
Qi
Q
Zhao
Qian
Q
Wang
Zhen-yi
ZY
Tong
Jian-hua
JH
D000225:Adenine / Q000031:analogs & derivatives / Q000494:pharmacology; D000067956:Adenylyl Cyclase Inhibitors; D000262:Adenylyl Cyclases / Q000378:metabolism*; D000970:Antineoplastic Agents / Q000494:pharmacology; D039481:CD11b Antigen / Q000378:metabolism*; D002454:Cell Differentiation / Q000187:drug effects*; D045744:Cell Line, Tumor; D019008:Drug Resistance, Neoplasm / Q000187:drug effects; D004789:Enzyme Activation / Q000187:drug effects; D004791:Enzyme Inhibitors / Q000494:pharmacology; D006801:Humans; D015473:Leukemia, Promyelocytic, Acute / Q000378:metabolism / Q000473:pathology; D010727:Phosphoric Diester Hydrolases / Q000378:metabolism; D014212:Tretinoin / Q000494:pharmacology*
D000067956:Adenylyl Cyclase Inhibitors; D000970:Antineoplastic Agents; D039481:CD11b Antigen; D004791:Enzyme Inhibitors; C017759:9-(tetrahydro-2-furyl)-adenine; D014212:Tretinoin; D010727:Phosphoric Diester Hydrolases; D000262:Adenylyl Cyclases; D000225:Adenine