title: Targeting CD44-STAT3 signaling by Gemini vitamin D analog leads to inhibition of invasion in basal-like breast cancer.
abstract: BACKGROUND
  CD44, a transmembrane glycoprotein, is a major receptor for extracellular proteins involved in invasion and metastasis of human cancers. We have previously demonstrated that the novel Gemini vitamin D analog BXL0124 [1α,25-dihydroxy-20R-21(3-hydroxy-3-deuteromethyl-4,4,4-trideuterobutyl)-23-yne-26,27-hexafluro-cholecalciferol] repressed CD44 expression in MCF10DCIS.com basal-like human breast cancer cells and inhibited MCF10DCIS xenograft tumor growth. In the present study, we investigated potential factors downstream of CD44 and the biological role of CD44 repression by BXL0124 in MCF10DCIS cells.
  
  
  RESULTS
  The treatment with Gemini vitamin D BXL0124 decreased CD44 protein level, suppressed STAT3 signaling, and inhibited invasion and proliferation of MCF10DCIS cells. The interaction between CD44 and STAT3 was determined by co-immunoprecipitation. CD44 forms a complex with STAT3 and Janus kinase 2 (JAK2) to activate STAT3 signaling, which was inhibited by BXL0124 in MCF10DCIS cells. The role of CD44 in STAT3 signaling and invasion of MCF10DCIS cells was further determined by the knockdown of CD44 using small hairpin RNA in vitro and in vivo. MCF10DCIS cell invasion was markedly decreased by the knockdown of CD44 in vitro. The knockdown of CD44 also significantly decreased mRNA expression levels of invasion markers, matrix metalloproteinases (MMPs) and urokinase plasminogen activator (uPA), in MCF10DCIS cells. In MCF10DCIS xenograft tumors, CD44 knockdown decreased tumor size and weight as well as invasion markers.
  
  
  CONCLUSIONS
  The present study identifies STAT3 as an important signaling molecule interacting with CD44 and demonstrates the essential role of CD44-STAT3 signaling in breast cancer invasion. It also suggests that repression of CD44-STAT3 signaling is a key molecular mechanism in the inhibition of breast cancer invasion by the Gemini vitamin D analog BXL0124.
authors: Department of Chemical Biology, Ernest Mario School of Pharmacy, Rutgers, The State University of New Jersey, Piscataway, New Jersey, United States of America.
authors: Jae Young
authors: JY
authors: So
authors: Amanda K
authors: AK
authors: Smolarek
authors: David M
authors: DM
authors: Salerno
authors: Hubert
authors: H
authors: Maehr
authors: Milan
authors: M
authors: Uskokovic
authors: Fang
authors: F
authors: Liu
authors: Nanjoo
authors: N
authors: Suh
mesh_terms: D000818:Animals; D001943:Breast Neoplasms / Q000378:metabolism / Q000473:pathology; D002117:Calcitriol / Q000031:analogs & derivatives / Q000494:pharmacology; D045744:Cell Line, Tumor; D005260:Female; D015972:Gene Expression Regulation, Neoplastic / Q000187:drug effects*; D006801:Humans; D018960:Hyaluronan Receptors / Q000235:genetics / Q000378:metabolism*; D051379:Mice; D009361:Neoplasm Invasiveness; D009362:Neoplasm Metastasis / Q000188:drug therapy; D050796:STAT3 Transcription Factor / Q000235:genetics / Q000378:metabolism*; D015398:Signal Transduction; D014183:Transplantation, Heterologous; D014807:Vitamin D / Q000031:analogs & derivatives / Q000494:pharmacology
chemical_list: C552206:1,25-dihydroxy-21-(3-hydroxy-3-methyl-4,4,4-tributyl)-23-yne-26,27-hexafluorocholecalciferol; C497483:CD44 protein, human; D018960:Hyaluronan Receptors; D050796:STAT3 Transcription Factor; C494086:STAT3 protein, human; D014807:Vitamin D; D002117:Calcitriol