Naphthalimides Induce G2 Arrest Through the ATM-Activated Chk2-Executed Pathway in HCT116 Cells

Abstract

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.

A series of naphthalimide derivatives as intra and extracellular pH sensors

“…On the other hand, some amino-containing naphthalimide derivatives have been demonstrated to be efficient drugs [54, 55]. Therefore, associating the simple structures and the highly Stokes shifted fluorescence properties of these reported naphtalimide derivatives in acidic cellular compartments, they are expected to be used for understanding cellular and biological mechanisms as well as antitumor drug mechanisms of delivery and efficacy.…”

Potentiation of Bleomycin in Jurkat Cells by Fungal Pycnidione

“…37) Several topoisomerase inhibitors have been reported; NSC 320846 and F11782, inhibitors of topoisomerases I and II, induced cell death 33,38) and H2A.X phosphorylation, 33) and R16, which was an inhibitor of topoisomerase II 39) and an inducer of genotoxic damage similar to bleomycin, 40) reduced Chk1 levels. 41) As demonstrated, pycnidione also induced cell death (Fig.…”

Characterization of the conversion between CD133+and CD133-cells in colon cancer SW620 cell line

“…Cells (4 × 10 5 /well) were seeded into six-well plates overnight, then harvested and washed with PBS, fixed with 70% ethanol at 4°C and incubated with 40 μg/mL RNase A for 15 min at 37°C. The samples were stained with 10 μg/mL propidium iodide in the dark for 30 min and analyzed at least 10,000 events using a FACSCalibur flow cytometer 29 (Becton Dickinson). display differential gene expression profiles, tumorigenesis and drug sensitivity.…”