title: Wnt modulates MCL1 to control cell survival in triple negative breast cancer.
abstract: BACKGROUND
  Triple negative breast cancer (TNBC) has higher rates of recurrence and distant metastasis, and poorer outcome as compared to non-TNBC. Aberrant activation of WNT signaling has been detected in TNBC, which might be important for triggering oncogenic conversion of breast epithelial cell. Therefore, we directed our focus on identifying the WNT ligand and its underlying mechanism in TNBC cells.
  
  
  METHODS
  We performed large-scale analysis of public microarray data to screen the WNT ligands and the clinical significance of the responsible ligand in TNBC. WNT5B was identified and its overexpression in TNBC was confirmed by immunohistochemistry staining, Western blot and ELISA. ShRNA was used to knockdown WNT5B expression (shWNT5B). Cellular functional alteration with shWNT5B treatment was determined by using wound healing assay, mammosphere assay; while cell cycle and apoptosis were examined by flowcytometry. Mitochondrial morphology was photographed by electron microscope. Biological change of mitochondria was detected by RT-PCR and oxygen consumption assay. Activation of WNT pathway and its downstream targets were evaluated by liciferase assay, immunohistochemistry staining and immunoblot analysis. Statistical methods used in the experiments besides microarray analysis was two-tailed t-test.
  
  
  RESULTS
  WNT5B was elevated both in the tumor and the patients' serum. Suppression of WNT5B remarkably impaired cell growth, migration and mammosphere formation. Additionally, G0/G1 cell cycle arrest and caspase-independent apoptosis was observed. Study of the possible mechanism indicated that these effects occurred through suppression of mitochondrial biogenesis, as evidenced by reduced mitochondrial DNA (MtDNA) and compromised oxidative phosphorylation (OXPHOS). In Vivo and in vitro data uncovered that WNT5B modulated mitochondrial physiology was mediated by MCL1, which was regulated by WNT/β-catenin responsive gene, Myc. Clinic data analysis revealed that both WNT5B and MCL1 are associated with enhanced metastasis and decreased disease-free survival.
  
  
  CONCLUSIONS
  All our findings suggested that WNT5B/MCL1 cascade is critical for TNBC and understanding its regulatory apparatus provided valuable insight into the pathogenesis of the tumor development and the guidance for targeting therapeutics.
authors.forename: Lixin
authors.initials: L
authors.lastname: Yang
authors.forename: Aldwin Apollo
authors.initials: AA
authors.lastname: Perez
authors.forename: Sayuri
authors.initials: S
authors.lastname: Fujie
authors.forename: Charles
authors.initials: C
authors.lastname: Warden
authors.forename: Jie
authors.initials: J
authors.lastname: Li
authors.forename: Yafan
authors.initials: Y
authors.lastname: Wang
authors.forename: Bryan
authors.initials: B
authors.lastname: Yung
authors.forename: Yun-Ru
authors.initials: YR
authors.lastname: Chen
authors.forename: Xiyong
authors.initials: X
authors.lastname: Liu
authors.forename: Hang
authors.initials: H
authors.lastname: Zhang
authors.forename: Shu
authors.initials: S
authors.lastname: Zheng
authors.forename: Zheng
authors.initials: Z
authors.lastname: Liu
authors.forename: David
authors.initials: D
authors.lastname: Ann
authors.affiliation: Department of Molecular Pharmacology, Beckman Research Institute, City of Hope National Medical Center, Beckman Building, Room 4117, 1500 East Duarte Road, Duarte, CA 91010, USA. yyen@coh.org.
authors.forename: Yun
authors.initials: Y
authors.lastname: Yen
mesh_terms: D045744:Cell Line, Tumor; D002470:Cell Survival / Q000502:physiology; D015331:Cohort Studies; D005260:Female; D006801:Humans; D064549:Myeloid Cell Leukemia Sequence 1 Protein / Q000096:biosynthesis* / Q000502:physiology; D015996:Survival Rate / Q000639:trends; D064726:Triple Negative Breast Neoplasms / Q000175:diagnosis / Q000378:metabolism* / Q000401:mortality*; D051153:Wnt Proteins / Q000502:physiology*
chemical_list: C579095:MCL1 protein, human; D064549:Myeloid Cell Leukemia Sequence 1 Protein; C435831:WNT5B protein, human; D051153:Wnt Proteins