title: Bladder cancer cells re-educate TAMs through lactate shuttling in the microfluidic cancer microenvironment.
abstract: BACKGROUND
  In the present study, we aimed to investigate the influence of lactate shuttling on the functional polarization and spatial distribution of transitional cell carcinoma of the bladder (TCCB) cells and macrophages.
  
  
  METHODS
  We designed a microfluidic coculture chip for real-time integrative assays. The effect of lactate shuttling on the re-education of macrophages by TCCB cells was explored by measuring the levels of NO using a total NO assay kit and by evaluating the protein expression of iNOS, p-NFkB-p65, Arg-1 and HIF-1α via cell immunofluorescence and western blotting. Additionally, we examined TCCB cell viability using acridine orange/ethidium bromide (AO/EB) and MitoTracker staining. Moreover, the concentration distributions of lactate and large signaling proteins in the culture chambers were measured using 4',6-diamidino-2-phenylindole (DAPI) and fluorescein isothiocyanate-dextran (FITC-dextran). Furthermore, the recruitment of macrophages and the influence of macrophages on BC metastasis were observed via light microscopy.
  
  
  RESULTS
  We confirmed that TCCB cells reprogrammed macrophages into an M2 phenotype. Moreover, lactate inhibited M1 polarization and induced M2 polarization of macrophages, but blockade of cancer cell-macrophage lactate flux significantly inhibited the re-education of macrophages by TCCB cells. In addition, lactate diffused faster and deeper than large signaling proteins in the microfluidic tumor microenvironment. Furthermore, lactate alone induced the migration of macrophages, and M1, but not M2, macrophages reduced the motility of TCCB cells.
  
  
  CONCLUSIONS
  TCCB cells reprogrammed macrophages into an M2 phenotype in a manner that depended on cancer cell-TAM lactate flux. Furthermore, the lactate shuttle may be a determinant of the density of TAMs in tumor tissue.
authors.affiliation: Department of Surgery, Affiliated Hospital of Qingdao University, Qingdao, China.
authors.forename: Yang
authors.initials: Y
authors.lastname: Zhao
authors.affiliation: Department of Anatomy, School of Basic Medical Sciences, Lanzhou University, Lanzhou, China.
authors.forename: Degui
authors.initials: D
authors.lastname: Wang
authors.affiliation: Department of Geratology, The 401st Hospital of PLA, Qingdao, China.
authors.forename: Ting
authors.initials: T
authors.lastname: Xu
authors.affiliation: Department of Surgery, Affiliated Hospital of Qingdao University, Qingdao, China.
authors.forename: Pengfei
authors.initials: P
authors.lastname: Liu
authors.affiliation: Department of Urology, Affiliated Hospital of Qingdao University, Key Laboratory of Urinary System Diseases, Qingdao, China.
authors.forename: Yanwei
authors.initials: Y
authors.lastname: Cao
authors.affiliation: Department of Urology, Affiliated Hospital of Qingdao University, Key Laboratory of Urinary System Diseases, Qingdao, China.
authors.forename: Yonghua
authors.initials: Y
authors.lastname: Wang
authors.affiliation: Department of Urology, Affiliated Hospital of Qingdao University, Key Laboratory of Urinary System Diseases, Qingdao, China.
authors.forename: Xuecheng
authors.initials: X
authors.lastname: Yang
authors.affiliation: Department of Urology, Affiliated Hospital of Qingdao University, Key Laboratory of Urinary System Diseases, Qingdao, China.
authors.forename: Xiaodong
authors.initials: X
authors.lastname: Xu
authors.affiliation: Department of Urology, Affiliated Hospital of Qingdao University, Key Laboratory of Urinary System Diseases, Qingdao, China.
authors.forename: Xinsheng
authors.initials: X
authors.lastname: Wang
authors.affiliation: Department of Urology, Affiliated Hospital of Qingdao University, Key Laboratory of Urinary System Diseases, Qingdao, China.
authors.forename: Haitao
authors.initials: H
authors.lastname: Niu
mesh_terms: D000818:Animals; D002295:Carcinoma, Transitional Cell / Q000378:metabolism* / Q000473:pathology*; D016764:Cell Polarity / Q000502:physiology; D018920:Coculture Techniques; D006801:Humans; D056656:Lab-On-A-Chip Devices; D019344:Lactic Acid / Q000378:metabolism*; D008264:Macrophages / Q000378:metabolism* / Q000473:pathology*; D051379:Mice; D044085:Microfluidics; D000067996:RAW 264.7 Cells; D059016:Tumor Microenvironment; D001749:Urinary Bladder Neoplasms / Q000378:metabolism* / Q000473:pathology*
chemical_list: D019344:Lactic Acid
keywords: bladder cancer; lactate; microfluidic chips; re-education; tumor-associated macrophage