title: Sulforaphane counteracts aggressiveness of pancreatic cancer driven by dysregulated Cx43-mediated gap junctional intercellular communication.
abstract: The extreme aggressiveness of pancreatic ductal adenocarcinoma (PDA) has been associated with blocked gap junctional intercellular communication (GJIC) and the presence of cancer stem cells (CSCs). We examined whether disturbed GJIC is responsible for a CSC phenotype in established and primary cancer cells and patient tissue of PDA using interdisciplinary methods based in physiology, cell and molecular biology, histology and epigenetics. Flux of fluorescent dyes and gemcitabine through gap junctions (GJs) was intact in less aggressive cells but not in highly malignant cells with morphological dysfunctional GJs. Among several connexins, only Cx43 was expressed on the cell surface of less aggressive and GJIC-competent cells, whereas Cx43 surface expression was absent in highly malignant, E-cadherin-negative and GJIC-incompetent cells. The levels of total Cx43 protein and Cx43 phosphorylated at Ser368 and Ser279/282 were high in normal tissue but low to absent in malignant tissue. si-RNA-mediated inhibition of Cx43 expression in GJIC-competent cells prevented GJIC and induced colony formation and the expression of stem cell-related factors. The bioactive substance sulforaphane enhanced Cx43 and E-cadherin levels, inhibited the CSC markers c-Met and CD133, improved the functional morphology of GJs and enhanced GJIC. Sulforaphane altered the phosphorylation of several kinases and their substrates and inhibition of GSK3, JNK and PKC prevented sulforaphane-induced CX43 expression. The sulforaphane-mediated expression of Cx43 was not correlated with enhanced Cx43 RNA expression, acetylated histone binding and Cx43 promoter de-methylation, suggesting that posttranslational phosphorylation is the dominant regulatory mechanism. Together, the absence of Cx43 prevents GJIC and enhances aggressiveness, whereas sulforaphane counteracts this process, and our findings highlight dietary co-treatment as a viable treatment option for PDA.
authors.affiliation: General, Visceral and Transplantation Surgery, University of Heidelberg, Heidelberg, Germany.
authors.forename: Tobias
authors.initials: T
authors.lastname: Forster
authors.forename: Vanessa
authors.initials: V
authors.lastname: Rausch
authors.forename: Yiyao
authors.initials: Y
authors.lastname: Zhang
authors.forename: Orkhan
authors.initials: O
authors.lastname: Isayev
authors.forename: Katharina
authors.initials: K
authors.lastname: Heilmann
authors.forename: Frank
authors.initials: F
authors.lastname: Schoensiegel
authors.forename: Li
authors.initials: L
authors.lastname: Liu
authors.forename: Michelle
authors.initials: M
authors.lastname: Nessling
authors.forename: Karsten
authors.initials: K
authors.lastname: Richter
authors.forename: Sabrina
authors.initials: S
authors.lastname: Labsch
authors.forename: Clifford C
authors.initials: CC
authors.lastname: Nwaeburu
authors.forename: Juergen
authors.initials: J
authors.lastname: Mattern
authors.forename: Jury
authors.initials: J
authors.lastname: Gladkich
authors.forename: Nathalia
authors.initials: N
authors.lastname: Giese
authors.forename: Jens
authors.initials: J
authors.lastname: Werner
authors.forename: Peter
authors.initials: P
authors.lastname: Schemmer
authors.forename: Wolfgang
authors.initials: W
authors.lastname: Gross
authors.forename: Martha M
authors.initials: MM
authors.lastname: Gebhard
authors.forename: Clarissa
authors.initials: C
authors.lastname: Gerhauser
authors.forename: Michael
authors.initials: M
authors.lastname: Schaefer
authors.forename: Ingrid
authors.initials: I
authors.lastname: Herr
mesh_terms: D000230:Adenocarcinoma / Q000188:drug therapy* / Q000378:metabolism / Q000473:pathology; D016588:Anticarcinogenic Agents / Q000494:pharmacology; D017209:Apoptosis / Q000187:drug effects; D015153:Blotting, Western; D021441:Carcinoma, Pancreatic Ductal / Q000188:drug therapy* / Q000378:metabolism / Q000473:pathology; D016022:Case-Control Studies; D002450:Cell Communication / Q000187:drug effects*; D049109:Cell Proliferation / Q000187:drug effects; D018031:Connexin 43 / Q000037:antagonists & inhibitors / Q000235:genetics / Q000378:metabolism*; D003841:Deoxycytidine / Q000031:analogs & derivatives / Q000494:pharmacology; D019008:Drug Resistance, Neoplasm / Q000187:drug effects; D017629:Gap Junctions / Q000187:drug effects* / Q000378:metabolism / Q000473:pathology; D006801:Humans; D007124:Immunoenzyme Techniques; D017879:Isothiocyanates / Q000494:pharmacology*; D008854:Microscopy, Electron; D010179:Pancreas / Q000378:metabolism; D010190:Pancreatic Neoplasms / Q000188:drug therapy* / Q000378:metabolism / Q000473:pathology; D010766:Phosphorylation / Q000187:drug effects; D034741:RNA, Small Interfering / Q000235:genetics; D018874:Spheroids, Cellular / Q000187:drug effects / Q000378:metabolism / Q000473:pathology; D013454:Sulfoxides; D014407:Tumor Cells, Cultured; D000093542:Gemcitabine
chemical_list: D016588:Anticarcinogenic Agents; D018031:Connexin 43; D017879:Isothiocyanates; D034741:RNA, Small Interfering; D013454:Sulfoxides; D003841:Deoxycytidine; C016766:sulforaphane; D000093542:Gemcitabine
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