title: Leptin promotes breast cancer cell migration and invasion via IL-18 expression and secretion.
abstract: In recent years, crosstalk between tumor microenvironment and cancer cells have received increasing attention. Accumulating research data suggests that leptin, a key adipokine secreted from adipocytes, plays important roles in breast cancer development. In our study, the effects of leptin on polarization of tumor-associated macrophages (TAMs) and promotion of the invasiveness of tumor cells were investigated. THP1 cells were used to differentiate M2 polarization macrophages. After stimulated by leptin, we established a co-culture system of tumor cells and macrophages to evaluate the function of leptin-induced macrophages in the migration and invasion of breast cancer cells. The gene and protein expressions were analyzed and the underlying mechanisms were evaluated. Moreover, pathological human specimens, and xenografts in nude mice, were detected to strengthen the in vitro results. Leptin elevated the expression of an array of cytokines in TAMs, IL-18 was the most increased, with an activation of the NF-κB/NF-κB1 signalling pathway. Additionally, after treated with leptin, TAMs significantly promoted the migration and invasion of breast cancer cells. However, these effects of leptin were abolished by the co-incubation of Bay11‑7082, a pharmacological NF-κB inhibitor. Leptin also directly stimulated IL-18 expression in breast cancer cells, which, differently, was via the PI3K/AKT-ATF-2 signaling pathway. In vivo studies showed that malignant breast carcinoma exhibited strong higher expression of Leptin, IL-8, and TAMs markers. Xenograft tumor-bearing mouse models showed that leptin significantly increased tumor volume, enhanced lung metastases, and increased expression of IL-8 and TAM markers, which were abolished by depletion of macrophages by clophosome-clodronate liposomes (CCL). Leptin could induce IL-18 expression both in TAMs and breast cancer cells. Leptin-induced IL-18 expression was regulated via NF-κB/NF-κB1 signaling in TAMs, while via PI3K-AKT/ATF-2 signaling in breast cancer cells, which, eventually, lead to invasion and metastasis of breast cancer cells.
authors.affiliation: Key Laboratory of Diagnostic Medicine Designated by the Ministry of Education, Chongqing Medical University, Chongqing 400016, P.R. China.
authors.forename: Kuangfa
authors.initials: K
authors.lastname: Li
authors.affiliation: Key Laboratory of Diagnostic Medicine Designated by the Ministry of Education, Chongqing Medical University, Chongqing 400016, P.R. China.
authors.forename: Lan
authors.initials: L
authors.lastname: Wei
authors.affiliation: Key Laboratory of Diagnostic Medicine Designated by the Ministry of Education, Chongqing Medical University, Chongqing 400016, P.R. China.
authors.forename: Yunxiu
authors.initials: Y
authors.lastname: Huang
authors.affiliation: Key Laboratory of Diagnostic Medicine Designated by the Ministry of Education, Chongqing Medical University, Chongqing 400016, P.R. China.
authors.forename: Yang
authors.initials: Y
authors.lastname: Wu
authors.affiliation: Key Laboratory of Diagnostic Medicine Designated by the Ministry of Education, Chongqing Medical University, Chongqing 400016, P.R. China.
authors.forename: Min
authors.initials: M
authors.lastname: Su
authors.affiliation: Key Laboratory of Diagnostic Medicine Designated by the Ministry of Education, Chongqing Medical University, Chongqing 400016, P.R. China.
authors.forename: Xueli
authors.initials: X
authors.lastname: Pang
authors.affiliation: Key Laboratory of Diagnostic Medicine Designated by the Ministry of Education, Chongqing Medical University, Chongqing 400016, P.R. China.
authors.forename: Nian
authors.initials: N
authors.lastname: Wang
authors.affiliation: Key Laboratory of Diagnostic Medicine Designated by the Ministry of Education, Chongqing Medical University, Chongqing 400016, P.R. China.
authors.forename: Feihu
authors.initials: F
authors.lastname: Ji
authors.affiliation: Key Laboratory of Diagnostic Medicine Designated by the Ministry of Education, Chongqing Medical University, Chongqing 400016, P.R. China.
authors.forename: Changli
authors.initials: C
authors.lastname: Zhong
authors.affiliation: Key Laboratory of Diagnostic Medicine Designated by the Ministry of Education, Chongqing Medical University, Chongqing 400016, P.R. China.
authors.forename: Tingmei
authors.initials: T
authors.lastname: Chen
mesh_terms: D000818:Animals; D001943:Breast Neoplasms / Q000235:genetics / Q000378:metabolism / Q000473:pathology*; D045744:Cell Line, Tumor; D002465:Cell Movement / Q000187:drug effects*; D002478:Cells, Cultured; D018920:Coculture Techniques; D005260:Female; D006801:Humans; D020382:Interleukin-18 / Q000235:genetics* / Q000378:metabolism; D020738:Leptin / Q000378:metabolism*; D061986:MCF-7 Cells; D008264:Macrophages / Q000166:cytology / Q000187:drug effects* / Q000473:pathology; D051379:Mice; D009361:Neoplasm Invasiveness; D009368:Neoplasm Transplantation; D015398:Signal Transduction / Q000187:drug effects; D059016:Tumor Microenvironment
chemical_list: C000589760:IL18 protein, human; D020382:Interleukin-18; D020738:Leptin