P53 and p38 MAPK pathways are involved in MONCPT-induced cell cycle G2/M arrest in human non-small cell lung cancer A549.
OBJECTIVE
In previous research, we found that 10-methoxy-9-nitrocamptothecin (MONCPT) possessed potent anti-tumor activity in A549 cells in vitro and in vivo. In this paper, our purpose is to investigate the mechanism of MONCPT-induced cell cycle arrest in A549 cells.


METHODS
Cell cycle distribution was measured using flow cytometry (FCM). Protein expression and RNA expression were analyzed by western blotting and real-time PCR, respectively. SiRNA technology was introduced to silence the expression of p53 and p38.


RESULTS
FCM showed that MONCPT induced cell cycle G2/M arrest in time- and dose-dependent manner. The levels of feedback loop proteins PLK-1, Cdc25C, and cyclinB1 were obviously increased from 12 to 24 h, and then reduced from 36 to 48 h by MONCPT (100.0 nM). Moreover, down-regulation of p-AKT in A549 cells was seen after treated with 100.0 nM MONCPT for 12-48 h. Over-expression of p53 and p21 in A549 cells treated with MONCPT was observed in time-dependent manner. When wild type p53 expression was specifically inhibited by RNA-interference, A549 cells treated with MONCPT delayed the onset of G2/M arrest; meanwhile p-ERK and Cdc2 were up-regulated while p21 and CDK7 were down-regulated in A549 cells treated with MONCPT and p53 SiRNA transfection in contrast to cells treated with 100.0 nM MONCPT alone. In addition, our results exhibited that MONCPT obviously down-regulated p-ERK, JNK, p-JNK, and p-p38. Treatment with p38 mitogen-activated protein kinase (MAPK) SiRNA obviously inhibited p38 MAPK and delayed the G2/M arrest induced by 50.0 nM MONCPT after 48 h.


CONCLUSIONS
Cell cycle regulators, AKT, p53, and MAPK, as therapeutic targets for MONCPT to induce cell cycle G2/M arrest in the context of anticancer therapy.
Zhang
Chong
C
Institute of Pharmacology and Toxicology, College of Pharmaceutical Sciences, Zhejiang University, #388 Yuhangtang Road, Hangzhou, Zhejiang, 310058, China.
Zhu
Hong
H
Yang
Xiaochun
X
Lou
Jianshu
J
Zhu
Difeng
D
Lu
Wei
W
He
Qiaojun
Q
Yang
Bo
B
D000970:Antineoplastic Agents / Q000494:pharmacology / Q000627:therapeutic use; D002166:Camptothecin / Q000031:analogs & derivatives* / Q000494:pharmacology / Q000627:therapeutic use; D002289:Carcinoma, Non-Small-Cell Lung / Q000188:drug therapy / Q000378:metabolism / Q000473:pathology*; D002453:Cell Cycle / Q000187:drug effects*; D002455:Cell Division / Q000187:drug effects; D045744:Cell Line, Tumor; D049109:Cell Proliferation / Q000187:drug effects; D016195:G2 Phase / Q000187:drug effects; D006801:Humans; D008175:Lung Neoplasms / Q000188:drug therapy / Q000378:metabolism / Q000473:pathology*; D008954:Models, Biological; D051058:Oncogene Protein v-akt / Q000378:metabolism / Q000502:physiology; D034741:RNA, Small Interfering / Q000494:pharmacology; D015398:Signal Transduction / Q000187:drug effects / Q000502:physiology; D016159:Tumor Suppressor Protein p53 / Q000037:antagonists & inhibitors / Q000378:metabolism / Q000502:physiology*; D048051:p38 Mitogen-Activated Protein Kinases / Q000037:antagonists & inhibitors / Q000378:metabolism / Q000502:physiology*
C513484:10-methoxy-9-nitrocamptothecin; D000970:Antineoplastic Agents; D034741:RNA, Small Interfering; D016159:Tumor Suppressor Protein p53; D051058:Oncogene Protein v-akt; D048051:p38 Mitogen-Activated Protein Kinases; D002166:Camptothecin