7-Chloro-6-piperidin-1-yl-quinoline-5,8-dione (PT-262), a novel synthetic compound induces lung carcinoma cell death associated with inhibiting ERK and CDC2 phosphorylation via a p53-independent pathway.
BACKGROUND
The derivatives of 5,8-quinolinedione have been shown to exert anticancer activities. A new synthetic compound 7-chloro-6-piperidin-1-yl-quinoline-5,8-dione (designed as PT-262) derived from 6,7-dichloroquinoline-5,8-dione on its anticancer activity was investigated in this study.


METHODS
PT-262 was synthesized as the following: triethylamine (0.56 ml, 5.1 mmol) was added dropwise to a solution of 6,7-dichloroquinoline-5,8-dione (1.00 g, 4.4 mmol) and piperidine (0.50 ml, 5.1 mmol) in 150 ml of benzene with stirring at room temperature for 5 min, and the solvent was removed using rotary evaporator to give a dark brown solid. PT-262 was purified by flash chromatography using 50% ethyl acetate/hexanes to elute that displayed as brown solids. To examine the induction of apoptosis following PT-262 treatment, the lung cancer cells were subjected to apoptotic cell observation, caspase activation, and mitochondrial functional assays. The protein levels of phosphorylated ERK and CDC2 after treatment with PT-262 were analyzed by Western blot.


RESULTS
Treatment with 1-20 microM PT-262 for 24 h induced cytotoxicity via a concentration-dependent manner in human lung cancer cells. PT-262 induced the loss of mitochondrial membrane potential and elevated the caspase-3 activation and apoptosis. Interestingly, the phosphorylation of ERK was inhibited by PT-262. The IC50 value of ERK phosphorylation inhibition was approximate around 5 microM. Treatment with a specific MEK1/2 (the upstream of ERK) inhibitor, PD98059, increased the PT-262-induced cytotoxicity in lung cancer cells. Moreover, PT-262 did not alter the protein expression of tumor suppressor p53. PT-262 elicited the cytotoxicity and accumulated the G2/M fractions in both the p53-wild type and p53-null lung cancer cells. The mitosis-regulated protein levels of cyclin B1 and phospho-CDC2 at Thr14, Tyr15, and Thr161 were repressed by PT-262 in these cells.


CONCLUSIONS
PT-262 suppresses the phosphorylation of ERK and CDC2 associated with proliferation inhibition via a p53-independent pathway in human lung cancer cells.
Hsu
Tzu-Sheng
TS
Institute of Pharmacology and Toxicology, Tzu Chi University, 701, Section 3, Chung-Yang Road, Hualien 970, Taiwan.
Chen
Chinpiao
C
Lee
Pei-Ting
PT
Chiu
Shu-Jun
SJ
Liu
Huei-Fang
HF
Tsai
Chih-Chien
CC
Chao
Jui-I
JI
D000970:Antineoplastic Agents / Q000737:chemistry / Q000494:pharmacology*; D017209:Apoptosis / Q000187:drug effects; D016203:CDC2 Protein Kinase / Q000037:antagonists & inhibitors*; D002277:Carcinoma / Q000188:drug therapy* / Q000473:pathology; D002452:Cell Count; D002453:Cell Cycle / Q000187:drug effects; D016923:Cell Death / Q000187:drug effects; D002455:Cell Division / Q000187:drug effects; D045744:Cell Line, Tumor; D049109:Cell Proliferation / Q000187:drug effects; D002470:Cell Survival / Q000187:drug effects; D048049:Extracellular Signal-Regulated MAP Kinases / Q000037:antagonists & inhibitors*; D006801:Humans; D008175:Lung Neoplasms / Q000188:drug therapy* / Q000473:pathology; D008564:Membrane Potentials / Q000187:drug effects; D051336:Mitochondrial Membranes / Q000187:drug effects; D020928:Mitogen-Activated Protein Kinases / Q000037:antagonists & inhibitors; D010766:Phosphorylation; D015363:Quinolones / Q000737:chemistry / Q000494:pharmacology*; D011809:Quinones / Q000737:chemistry / Q000494:pharmacology*; D015398:Signal Transduction / Q000187:drug effects; D016159:Tumor Suppressor Protein p53 / Q000502:physiology*
C533600:7-chloro-6-piperidin-1-ylquinoline-5,8-dione; D000970:Antineoplastic Agents; D015363:Quinolones; D011809:Quinones; D016159:Tumor Suppressor Protein p53; D016203:CDC2 Protein Kinase; D048049:Extracellular Signal-Regulated MAP Kinases; D020928:Mitogen-Activated Protein Kinases