title: Lidamycin up-regulates the expression of thymidine phosphorylase and enhances the effects of capecitabine on the growth and pulmonary metastases of murine breast carcinoma.
abstract: OBJECTIVE
  Capecitabine (CAP), a prodrug, needs to be converted to 5-fluorouracil by several key enzymes, including thymidine phosphorylase (TP). To improve the therapeutic index, potentiation of antitumor activity of CAP is required. In this study, we explored whether lidamycin (LDM), an enediyne anticancer antibiotic, can induce synergistic antitumor effects in combination with CAP in murine breast cancer in vitro and in vivo.
  
  
  METHODS
  Using MTT, cell migration and invasion, siRNA knockdown, and Western blot assays, the in vitro synergistic effects of LDM plus CAP on 4T1(LUC) cells were evaluated, and the mechanism of this synergy was explored. For in vivo model of orthotopic implantation model of 4T1(LUC) cells, optical molecular imaging system was utilized to evaluate the growth of primary tumor and metastasis. To further understand the mechanism of action of the LDM/CAP combination, immunohistochemistry analysis was carried out to detect thymidine phosphorylase induction and ERK signaling.
  
  
  RESULTS
  As determined by MTT and transwell assay, LDM enhanced the inhibitory effects of CAP on cancer cell proliferation, migration, and invasion. Western blot showed that this synergistic effect was attributed to the up-regulated expression of TP induced by LDM. Knocking down TP impaired the synergistic anti-proliferative effect of LDM and CAP. Furthermore, our data suggested that LDM-induced up-regulation of TP both in vitro and in vivo is associated with ERK activation, because the inhibition of ERK activity by ERK inhibitor U0126 abrogated LDM-induced TP up-regulation. In animal models, LDM plus CAP potently inhibited primary tumor growth as well as lung metastasis compared with control or single-agent-treated group.
  
  
  CONCLUSIONS
  LDM can potentiate the antitumor effects of CAP on breast cancer line. The synergistic effects suggest that the combination of LDM and CAP is an innovative antitumor strategy for breast cancer therapy.
authors: Department of Oncology, Institute of Medicinal Biotechnology, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing, 100050, China.
authors: Sheng-hua
authors: SH
authors: Zhang
authors: Hao
authors: H
authors: Zhang
authors: Hong-wei
authors: HW
authors: He
authors: Liang
authors: L
authors: Li
authors: Xing-qi
authors: XQ
authors: Li
authors: Yi-ping
authors: YP
authors: Zhang
authors: Rong-guang
authors: RG
authors: Shao
mesh_terms: D000617:Aminoglycosides / Q000008:administration & dosage; D000818:Animals; D000971:Antineoplastic Combined Chemotherapy Protocols / Q000494:pharmacology*; D015153:Blotting, Western; D000069287:Capecitabine; D045744:Cell Line, Tumor; D003841:Deoxycytidine / Q000008:administration & dosage / Q000031:analogs & derivatives; D004357:Drug Synergism; D053281:Enediynes / Q000008:administration & dosage; D004790:Enzyme Induction / Q000187:drug effects; D005260:Female; D005472:Fluorouracil / Q000008:administration & dosage / Q000031:analogs & derivatives; D015972:Gene Expression Regulation, Neoplastic / Q000187:drug effects; D055785:Gene Knockdown Techniques; D008175:Lung Neoplasms / Q000517:prevention & control* / Q000556:secondary; D020935:MAP Kinase Signaling System / Q000187:drug effects; D008325:Mammary Neoplasms, Experimental / Q000188:drug therapy* / Q000473:pathology; D051379:Mice; D008807:Mice, Inbred BALB C; D008819:Mice, Nude; D013939:Thymidine Phosphorylase / Q000096:biosynthesis / Q000235:genetics*; D015854:Up-Regulation / Q000187:drug effects*
chemical_list: D000617:Aminoglycosides; D053281:Enediynes; D003841:Deoxycytidine; C058024:C 1027; D000069287:Capecitabine; D013939:Thymidine Phosphorylase; D005472:Fluorouracil