title: Inhibition of STAT signalling in bladder cancer by diindolylmethane: relevance to cell adhesion, migration and proliferation.
abstract: Effective treatments to prevent recurrence or progression of non-muscle-invasive bladder cancer, or to inhibit metastasis of muscle-invasive forms of the disease, would deliver significant patient benefit. Here the involvement of STAT signalling and the chemopreventive potential of diindolylmethane (DIM) in human bladder cancer were investigated. Muscle-invasive bladder cancer tissues were characterised by nuclear expression of phosphorylated STAT1, 3 and 5. In E-cadherin positive tumour cell lines (RT112, RT4, HT1376), STAT5 was constitutively phosphorylated, while E-cadherin negative lines (J82, T24, UMUC3) contained phosphoSTAT3. Knockdown of STAT3 induced G₀/G₁ arrest and inhibited adhesion in J82 cells. Knockdown of STAT1inhibited migration in J82 and RT112 lines. No significant increase in apoptosis was observed. In response to the Janus kinase inhibitor, AG490, RT112 and J82 cells initially underwent G₀/G₁ arrest, with RT112 cells subsequently exhibiting S phase arrest. Phosphorylation of STAT1(Tyr701), STAT3(Tyr705) and (Ser727) and STAT5(Tyr694) was inhibited by DIM, as was adhesion of J82 cells to collagen, an effect that was enhanced when STAT1 or 3 was reduced by siRNA. However, over-expression of STAT3C partially rescued the DIM inhibitory effect on collagen-mediated adhesion. Migration of both lines was inhibited by DIM, while transfection of constitutively active STAT3C enhanced migration of RT112 cells. DIM induced cell cycle arrest and apoptosis in three cell lines with different degrees of radioresistance. Taken together, these results suggest that inhibition of STAT signalling and/or treatment with DIM may decrease invasiveness of bladder cancer. DIM can induce apoptosis in cell lines which are radioresistant, so in combination with radiotherapy may be useful in overcoming such resistance.
authors.affiliation: Department of Cancer Studies and Molecular Medicine, Biocentre, University of Leicester, UK.
authors.forename: Yiyang
authors.initials: Y
authors.lastname: Sun
authors.forename: Mai-Kim
authors.initials: MK
authors.lastname: Cheng
authors.forename: Thomas R L
authors.initials: TR
authors.lastname: Griffiths
authors.forename: J Kilian
authors.initials: JK
authors.lastname: Mellon
authors.forename: Bao
authors.initials: B
authors.lastname: Kai
authors.forename: Marina
authors.initials: M
authors.lastname: Kriajevska
authors.forename: Margaret M
authors.initials: MM
authors.lastname: Manson
mesh_terms: D000970:Antineoplastic Agents / Q000494:pharmacology*; D017209:Apoptosis / Q000187:drug effects; D002448:Cell Adhesion / Q000187:drug effects; D002453:Cell Cycle / Q000187:drug effects; D002467:Cell Nucleus / Q000187:drug effects / Q000378:metabolism; D020868:Gene Silencing; D006801:Humans; D007211:Indoles / Q000494:pharmacology*; D053612:Janus Kinases / Q000037:antagonists & inhibitors; D058990:Molecular Targeted Therapy; D019042:Muscle Neoplasms / Q000378:metabolism / Q000473:pathology / Q000556:secondary; D009361:Neoplasm Invasiveness / Q000517:prevention & control; D009363:Neoplasm Proteins / Q000037:antagonists & inhibitors* / Q000235:genetics / Q000378:metabolism; D010766:Phosphorylation / Q000187:drug effects; D020033:Protein Isoforms / Q000037:antagonists & inhibitors / Q000235:genetics / Q000378:metabolism; D047428:Protein Kinase Inhibitors / Q000494:pharmacology; D011499:Protein Processing, Post-Translational / Q000187:drug effects; D034741:RNA, Small Interfering; D050791:STAT Transcription Factors / Q000037:antagonists & inhibitors* / Q000235:genetics / Q000378:metabolism; D015398:Signal Transduction / Q000187:drug effects*; D001743:Urinary Bladder / Q000378:metabolism / Q000473:pathology; D001749:Urinary Bladder Neoplasms / Q000188:drug therapy* / Q000378:metabolism / Q000473:pathology
chemical_list: D000970:Antineoplastic Agents; D007211:Indoles; D009363:Neoplasm Proteins; D020033:Protein Isoforms; D047428:Protein Kinase Inhibitors; D034741:RNA, Small Interfering; D050791:STAT Transcription Factors; D053612:Janus Kinases; C016392:3,3'-diindolylmethane