Naphthalimides induce G(2) arrest through the ATM-activated Chk2-executed pathway in HCT116 cells.
Naphthalimides, particularly amonafide and 2-(2-dimethylamino)-6-thia-2-aza-benzo[def]chrysene-1,3-diones (R16), have been identified to possess anticancer activities and to induce G(2)-M arrest through inhibiting topoisomerase II accompanied by Chk1 degradation. The current study was designed to precisely dissect the signaling pathway(s) responsible for the naphthalimide-induced cell cycle arrest in human colon carcinoma HCT116 cells. Using phosphorylated histone H3 and mitotic protein monoclonal 2 as mitosis markers, we first specified the G(2) arrest elicited by the R16 and amonafide. Then, R16 and amonafide were revealed to induce phosphorylation of the DNA damage sensor ataxia telangiectasia-mutated (ATM) responding to DNA double-strand breaks (DSBs). Inhibition of ATM by both the pharmacological inhibitor caffeine and the specific small interference RNA (siRNA) rescued the G(2) arrest elicited by R16, indicating its ATM-dependent characteristic. Furthermore, depletion of Chk2, but not Chk1 with their corresponding siRNA, statistically significantly reversed the R16- and amonafide-triggered G(2) arrest. Moreover, the naphthalimides phosphorylated Chk2 in an ATM-dependent manner but induced Chk1 degradation. These data indicate that R16 and amonafide preferentially used Chk2 as evidenced by the differential ATM-executed phosphorylation of Chk1 and Chk2. Thus, a clear signaling pathway can be established, in which ATM relays the DNA DSBs signaling triggered by the naphthalimides to the checkpoint kinases, predominantly to Chk2,which finally elicits G(2) arrest. The mechanistic elucidation not only favors the development of the naphthalimides as anticancer agents but also provides an alternative strategy of Chk2 inhibition to potentiate the anticancer activities of these agents.
Zhu
Hong
H
Division of Anti-tumor Pharmacology, State Key Laboratory of Drug Research, Shanghai Institute of Materia Medica, Chinese Academy of Sciences, Shanghai 201203, PR China.
Miao
Ze-Hong
ZH
Huang
Min
M
Feng
Jian-Ming
JM
Zhang
Zhi-Xiang
ZX
Lu
Jin-Jian
JJ
Cai
Yu-Jun
YJ
Tong
Lin-Jiang
LJ
Xu
Yu-Fang
YF
Qian
Xu-Hong
XH
Ding
Jian
J
D000225:Adenine; D000970:Antineoplastic Agents / Q000494:pharmacology*; D064007:Ataxia Telangiectasia Mutated Proteins; D015153:Blotting, Western; D018797:Cell Cycle Proteins / Q000378:metabolism*; D064447:Checkpoint Kinase 2; D053903:DNA Breaks, Double-Stranded; D004268:DNA-Binding Proteins / Q000378:metabolism*; D005434:Flow Cytometry; D005455:Fluorescent Antibody Technique; D016195:G2 Phase / Q000187:drug effects*; D045325:HCT116 Cells; D006801:Humans; D053644:Naphthalimides / Q000494:pharmacology*; D063065:Organophosphonates; D017346:Protein Serine-Threonine Kinases / Q000378:metabolism*; D034741:RNA, Small Interfering; D015398:Signal Transduction / Q000502:physiology; D013876:Thiophenes / Q000494:pharmacology*; D014162:Transfection; D025521:Tumor Suppressor Proteins / Q000378:metabolism*
C524136:2-(2-dimethylamino)-6-thia-2-azabenzo(def)chrysene-1,3-dione; D000970:Antineoplastic Agents; D018797:Cell Cycle Proteins; D004268:DNA-Binding Proteins; D053644:Naphthalimides; D063065:Organophosphonates; D034741:RNA, Small Interfering; D013876:Thiophenes; D025521:Tumor Suppressor Proteins; C037020:amonafide; D064447:Checkpoint Kinase 2; C576324:ATM protein, human; D064007:Ataxia Telangiectasia Mutated Proteins; C578634:CHEK2 protein, human; D017346:Protein Serine-Threonine Kinases; D000225:Adenine