Salinomycin enhances cisplatin-induced cytotoxicity in human lung cancer cells via down-regulation of AKT-dependent thymidylate synthase expression

Jen-Chung Ko; Hao-Yu Zheng; Wen-Ching Chen; Yi-Shuan Peng; Chia-Hung Wu; Chia-Li Wei; Jyh-Cheng Chen; Yun-Wei Lin

doi:10.1016/j.bcp.2016.09.022

Salinomycin enhances cisplatin-induced cytotoxicity in human lung cancer cells via down-regulation of AKT-dependent thymidylate synthase expression

Biochem Pharmacol. 2016 Dec 15:122:90-98. doi: 10.1016/j.bcp.2016.09.022. Epub 2016 Sep 22.

Authors

Jen-Chung Ko¹, Hao-Yu Zheng², Wen-Ching Chen², Yi-Shuan Peng², Chia-Hung Wu², Chia-Li Wei², Jyh-Cheng Chen³, Yun-Wei Lin⁴

Affiliations

¹ Department of Internal Medicine, National Taiwan University Hospital, Hsin-Chu Branch, Taiwan; Institute of Technology Law, National Chiao Tung University, Hsinchu, Taiwan.
² Department of Biochemical Science and Technology, National Chiayi University, Chiayi, Taiwan.
³ Department of Food Science, National Chiayi University, Chiayi, Taiwan.
⁴ Department of Biochemical Science and Technology, National Chiayi University, Chiayi, Taiwan. Electronic address: linyw@mail.ncyu.edu.tw.

PMID: 27666600
DOI: 10.1016/j.bcp.2016.09.022

Abstract

Salinomycin, a polyether antibiotic, acts as a highly selective potassium ionophore and has anticancer activity on various cancer cell lines. Cisplatin has been proved as chemotherapy drug for advanced human non-small cell lung cancer (NSCLC). Thymidylate synthase (TS) is a key enzyme in the pyrimidine salvage pathway, and increased expression of TS is thought to be associated with resistance to cisplatin. In this study, we showed that salinomycin (0.5-2μg/mL) treatment down-regulating of TS expression in an AKT inactivation manner in two NSCLC cell lines, human lung adenocarcinoma A549 and squamous cell carcinoma H1703 cells. Knockdown of TS using small interfering RNA (siRNA) or inhibiting AKT activity with PI3K inhibitor LY294002 enhanced the cytotoxicity and cell growth inhibition of salinomycin. A combination of cisplatin and salinomycin resulted in synergistic enhancement of cytotoxicity and cell growth inhibition in NSCLC cells, accompanied with reduced activation of phospho-AKT, and TS expression. Overexpression of a constitutive active AKT (AKT-CA) expression vector reversed the salinomycin and cisplatin-induced synergistic cytotoxicity. In contrast, pretreatment with LY294002 further decreased the cell viability in salinomycin and cisplatin cotreated cells. Our findings suggested that the down-regulation of AKT-mediated TS expression by salinomycin enhanced the cisplatin-induced cytotoxicity in NSCLC cells. These results may provide a rationale to combine salinomycin with cisplatin for lung cancer treatment.

Keywords: AKT; ALLN (PubChem CID: 4332); Actinomycin D (PubChem CID: 2019); Cisplatin; Cisplatin (PubChem CID: 441203); Crystal violet (PubChem CID: 11057); Cycloheximide (PubChem CID: 6197); LY294002 (PubChem CID: 3973); MG132 (PubChem CID: 462382); Non-small cell lung cancer; Penicillin (PubChem CID: 5904); Salinomycin; Salinomycin (PubChem CID: 3085092); Sodium bicarbonate (PubChem CID: 516892); Streptomycin (PubChem CID: 19649); Thymidylate synthase; Trypan blue (PubChem CID: 9562061); Wortmannin (PubChem CID: 101764112); l-Glutamine (PubChem CID: 5961).

MeSH terms

Anti-Bacterial Agents / pharmacology
Antineoplastic Agents / pharmacology
Carcinoma, Non-Small-Cell Lung / drug therapy*
Cell Line, Tumor
Cisplatin / pharmacology*
Down-Regulation
Drug Therapy, Combination
Humans
Proto-Oncogene Proteins c-akt / genetics
Proto-Oncogene Proteins c-akt / metabolism*
Pyrans / pharmacology*
RNA, Messenger / genetics
RNA, Messenger / metabolism
Thymidylate Synthase / genetics
Thymidylate Synthase / metabolism*

Substances

Anti-Bacterial Agents
Antineoplastic Agents
Pyrans
RNA, Messenger
salinomycin
Thymidylate Synthase
Proto-Oncogene Proteins c-akt
Cisplatin