title: Targeting COX-2/PGE(2) pathway in HIPK2 knockdown cancer cells: impact on dendritic cell maturation.
abstract: BACKGROUND
  Homeodomain-interacting protein kinase 2 (HIPK2) is a multifunctional protein that exploits its kinase activity to modulate key molecular pathways in cancer to restrain tumor growth and induce response to therapies. For instance, HIPK2 knockdown induces upregulation of oncogenic hypoxia-inducible factor-1 (HIF-1) activity leading to a constitutive hypoxic and angiogenic phenotype with increased tumor growth in vivo. HIPK2 inhibition, therefore, releases pathways leading to production of pro-inflammatory molecules such as vascular endothelial growth factor (VEGF) or prostaglandin E2 (PGE(2)). Tumor-produced inflammatory mediators other than promote tumour growth and vascular development may permit evasion of anti-tumour immune responses. Thus, dendritic cells (DCs) dysfunction induced by tumor-produced molecules, may allow tumor cells to escape immunosurveillance. Here we evaluated the molecular mechanism of PGE(2) production after HIPK2 depletion and how to modulate it.
  
  
  RESULTS
  We show that HIPK2 knockdown in colon cancer cells resulted in cyclooxygenase-2 (COX-2) upregulation and COX-2-derived PGE(2) generation. At molecular level, COX-2 upregulation depended on HIF-1 activity. We previously reported that zinc treatment inhibits HIF-1 activity. Here, zinc supplementation to HIPK2 depleted cells inhibited HIF-1-induced COX-2 expression and PGE(2)/VEGF production. At translational level, while conditioned media of both siRNA control and HIPK2 depleted cells inhibited DCs maturation, conditioned media of only zinc-treated HIPK2 depleted cells efficiently restored DCs maturation, seen as the expression of co-stimulatory molecules CD80 and CD86, cytokine IL-10 release, and STAT3 phosphorylation.
  
  
  CONCLUSIONS
  THESE FINDINGS SHOW THAT: 1) HIPK2 knockdown induced COX-2 upregulation, mostly depending on HIF-1 activity; 2) zinc treatment downregulated HIF-1-induced COX-2 and inhibited PGE(2)/VEGF production; and 3) zinc treatment of HIPK2 depleted cells restored DCs maturation.
authors.affiliation: Department of Experimental Oncology, Molecular Oncogenesis Laboratory, Regina Elena National Cancer Institute, Rome, Italy.
authors.forename: Alessia
authors.initials: A
authors.lastname: Garufi
authors.forename: Giuseppa
authors.initials: G
authors.lastname: Pistritto
authors.forename: Claudia
authors.initials: C
authors.lastname: Ceci
authors.forename: Livia
authors.initials: L
authors.lastname: Di Renzo
authors.forename: Roberta
authors.initials: R
authors.lastname: Santarelli
authors.forename: Alberto
authors.initials: A
authors.lastname: Faggioni
authors.forename: Mara
authors.initials: M
authors.lastname: Cirone
authors.forename: Gabriella
authors.initials: G
authors.lastname: D'Orazi
mesh_terms: D002352:Carrier Proteins / Q000235:genetics* / Q000378:metabolism; D002454:Cell Differentiation; D045744:Cell Line, Tumor; D051546:Cyclooxygenase 2 / Q000235:genetics / Q000378:metabolism*; D003713:Dendritic Cells / Q000502:physiology*; D015232:Dinoprostone / Q000235:genetics / Q000378:metabolism*; D015536:Down-Regulation / Q000187:drug effects; D015870:Gene Expression; D015972:Gene Expression Regulation, Neoplastic; D055785:Gene Knockdown Techniques; D006801:Humans; D051795:Hypoxia-Inducible Factor 1, alpha Subunit / Q000378:metabolism / Q000502:physiology; D017346:Protein Serine-Threonine Kinases / Q000235:genetics* / Q000378:metabolism; D034741:RNA, Small Interfering / Q000235:genetics; D015398:Signal Transduction / Q000187:drug effects; D019139:Tumor Escape; D042461:Vascular Endothelial Growth Factor A / Q000235:genetics / Q000378:metabolism; D015032:Zinc / Q000494:pharmacology
chemical_list: D002352:Carrier Proteins; C497442:HIF1A protein, human; D051795:Hypoxia-Inducible Factor 1, alpha Subunit; D034741:RNA, Small Interfering; C467484:VEGFA protein, human; D042461:Vascular Endothelial Growth Factor A; D051546:Cyclooxygenase 2; C496540:PTGS2 protein, human; C115114:HIPK2 protein, human; D017346:Protein Serine-Threonine Kinases; D015032:Zinc; D015232:Dinoprostone