ABSTRACT
Tumor metastasis and lack of NKG2D ligand (NKG2DL) expression are associated with poor prognosis in patients with colon cancer. Here, we found that spironolactone (SPIR), an FDA-approved diuretic drug with a long-term safety profile, can up-regulate NKG2DL expression in multiple colon cancer cell lines by activating the ATM-Chk2-mediated checkpoint pathway, which in turn enhances tumor elimination by natural killer cells. SPIR can also up-regulate the expression of metastasis-suppressor genes TIMP2 and TIMP3, thereby reducing tumor cell invasiveness. Although SPIR is an aldosterone antagonist, its antitumor effects are independent of the mineralocorticoid receptor pathway. By screening the human nuclear hormone receptor siRNA library, we identified retinoid X receptor γ (RXRγ) instead as being indispensable for the antitumor functions of SPIR. Collectively, our results strongly support the use of SPIR or other RXRγ agonists with minimal side effects for colon cancer prevention and therapy.
Subject(s)
Colorectal Neoplasms/drug therapy , Colorectal Neoplasms/metabolism , NK Cell Lectin-Like Receptor Subfamily K/metabolism , Retinoid X Receptor gamma/agonists , Spironolactone/pharmacology , Animals , Cell Line, Tumor , Colorectal Neoplasms/secondary , Cytotoxicity, Immunologic/drug effects , GPI-Linked Proteins/genetics , GPI-Linked Proteins/metabolism , Histocompatibility Antigens Class I/genetics , Histocompatibility Antigens Class I/metabolism , Humans , Intercellular Signaling Peptides and Proteins/genetics , Intercellular Signaling Peptides and Proteins/metabolism , Intracellular Signaling Peptides and Proteins/genetics , Intracellular Signaling Peptides and Proteins/metabolism , Killer Cells, Natural/drug effects , Killer Cells, Natural/immunology , Ligands , Mice , Mice, Inbred C57BL , Mice, Mutant Strains , RNA, Messenger/genetics , RNA, Messenger/metabolism , RNA, Neoplasm/genetics , RNA, Neoplasm/metabolism , Receptors, Mineralocorticoid/metabolism , Retinoid X Receptor gamma/antagonists & inhibitors , Retinoid X Receptor gamma/genetics , Signal Transduction , Tissue Inhibitor of Metalloproteinase-2/genetics , Tissue Inhibitor of Metalloproteinase-3/genetics , Up-Regulation/drug effects , Xenograft Model Antitumor AssaysABSTRACT
Nuclear retinoid X receptors (RXRs) and peroxisome proliferator-activated receptors (PPARs are potential candidates as drug target for cancer prevention and treatment. We investigated if the rexinoid 6-OH-11-O-hydroxyphenantrene (IIF) potentiates the antitumoral properties of PPARgamma ligands as ciglitazone and pioglitazone, on two colon cancer cell lines: HCA-7 and HCT-116. Drugs inhibited cell growth and induced apoptosis synergistically. The combination resulted in a decrease of cyclooxigenase-2, metalloproteinases-2 and -9 expression level and activity while PPARgamma, RXRgamma and tissue inhibitors of metalloproteinase-1 and -2 expression were increased. Finally, IIF potentiated PPAR transcriptional activity by enhancement of peroxisome proliferator response elements transactivation.
Subject(s)
Antineoplastic Combined Chemotherapy Protocols/pharmacology , Cell Movement/drug effects , Cell Proliferation/drug effects , Colonic Neoplasms/pathology , PPAR gamma/agonists , Retinoid X Receptor gamma/agonists , Apoptosis/drug effects , Cell Survival/drug effects , Colonic Neoplasms/genetics , Colonic Neoplasms/metabolism , Cyclooxygenase 2/metabolism , Dose-Response Relationship, Drug , Drug Synergism , HCT116 Cells , Humans , Ligands , Matrix Metalloproteinase 2/metabolism , Matrix Metalloproteinase 9/metabolism , Neoplasm Invasiveness , PPAR gamma/genetics , PPAR gamma/metabolism , Pioglitazone , Response Elements/drug effects , Retinoid X Receptor gamma/metabolism , Thiazolidinediones/pharmacology , Tissue Inhibitor of Metalloproteinase-1/metabolism , Tissue Inhibitor of Metalloproteinase-2/metabolism , Transcriptional Activation/drug effects , Tretinoin/analogs & derivatives , Tretinoin/pharmacologyABSTRACT
Three-dimensional pharmacophore models were generated for retinoid X receptor (RXR(gamma)) agonists using quantitative approach (CATALYST HypoRefine). One optimal pharmacophore model for selective RXR(gamma) agonists was determined through careful validation processes. The best quantitative model (Hypo-1) had five features and five excluded volumes: three hydrophobic aliphatic groups (HAL1, HAL2, and HAL3), one hydrophobic aromatic ring (HAR), and one hydrogen bond acceptor (HBA). The model was validated using a wide range of test molecules. It could predict agonist activity and identify highly potent molecules. The present results are valuable to discover and develop specific RXR(gamma) agonists with desired biological activities.
Subject(s)
Drug Design , Models, Molecular , Neuropharmacology/methods , Retinoid X Receptor gamma/agonists , Computer Simulation , Drug Evaluation, Preclinical/methods , Molecular Structure , Predictive Value of Tests , SoftwareABSTRACT
Retinoid X receptor agonists (RXR agonists, rexinoids) are interesting candidates for the treatment of cancers such as tamoxifen-resistant breast cancer and taxol-resistant lung cancer. However, well-known RXR agonists possess a strong lipophilic character. In addition, although RXR has three subtypes, no subtype-selective RXR agonists are known. Thus we aimed to produce less-lipophilic and subtype-selective RXR agonists. By designing sulfonamide-type RXR agonists, 4-[N-methanesulfonyl-N-(5,5,8,8-tetramethyl-5,6,7,8-tetrahydro-2-naphthyl)amino]benzoic acid (8 a) was found to prefer RXRalpha over RXRbeta and RXRgamma, although the potency is less than the potencies of well-known RXR pan-agonists. Moreover, our results suggest that the reduction of lipophilicity at the hydrophobic interaction region of RXR agonists enables production of RXR subtype preference. Our finding will be useful for the creation of more potent and less-lipophilic subtype-selective RXR agonists aimed at the reduction of undesirable side effects.
Subject(s)
Anti-Obesity Agents/pharmacology , Antineoplastic Agents/pharmacology , Cell Differentiation/drug effects , Retinoid X Receptors/agonists , Sulfonamides/pharmacology , Animals , Anti-Obesity Agents/chemical synthesis , Antineoplastic Agents/chemical synthesis , COS Cells , Cell Differentiation/physiology , Chlorocebus aethiops , Drug Synergism , Hydrophobic and Hydrophilic Interactions , Models, Chemical , Nitroblue Tetrazolium/metabolism , Oxidation-Reduction , Retinoid X Receptor alpha/agonists , Retinoid X Receptor beta/agonists , Retinoid X Receptor gamma/agonists , Sulfonamides/chemical synthesisABSTRACT
Benzofused heterocyclic analogs of the RXR selective modulator 1 (LG101506) were synthesized, and tested for their ability to bind RXRalpha and activate RXR homo and heterodimers. Potency and efficacy were observed to be dependent upon the choice of heterocycle as well as the sidechain employed.
