Target Identification and Mode of Action Studies

Drug target identification and mode of action studies for molecules discovered through phenotypic screens usually represent a bottleneck in drug discovery. The limited abundance of compound available for characterization studies is an additional fundamental concern in natural products drug discovery, particularly if the structural complexity precludes chemical synthesis in a timely manner. Genomic and proteomic profiling techniques which require only minute amounts of natural products are being applied in our lab to gain insight into how the compounds act globally on the molecular and cellular level. We systematically transfer genome-wide studies used in yeast to infer targets of bioactive compounds into more relevant mammalian systems in order to interrogate more complex pathways. These approaches led to us to identify a novel mode of action for the apratoxin family of anticancer agents, inhibiting cotranslational translocation.Modes of Action Studies Luesch

Luesch, H. Mol. BioSyst. 2006, 2, 609–620 (Reproduced by permission of The Royal Society of Chemistry).

We use classical biochemical approaches to study affected molecular pathways and to validate hypotheses derived from global strategies.  We employ affinity chromatography for direct target identification upon labeling of natural products using synthetic organic chemistry.  Cocrystallization of inhibitor–target complexes followed by X-ray crystallography or molecular docking are other techniques applied in our lab to establish binding modes to target proteins.  We also subject natural products to orthogonal biochemical and cell-based profiling platforms, mainly targeting proteases and GPCRs.

Luesch MOA Slide 2020

Sample Publications:

  1. Bousquet, M. S.; Ratnayake, R.; Pope, J. L.; Chen, Q.-Y.; Zhu, F; Chen, S.; Carney, T. J.; Gharaibeh, R. Z.; Jobin, C.; Paul, V. J.; Luesch, H. “Seaweed Natural Products Modify the Host Inflammatory Response via Nrf2 Signaling and Alter Colon Microbiota Composition and Gene Expression” Free Rad. Biol. Med. 2020, 146, 306–323.
  2. Al-Awadhi, F. H.; Bowen, G.; Rezaei, M. A.; Kwan, J. C.; Li, C.; Ye, T.; Paul, V. J.; Luesch, H. “Discovery, Synthesis, Pharmacological Profiling and Biological Characterization of Brintonamides A-E, Novel Dual Protease and GPCR Modulators from a Marine Cyanobacterium” J. Med. Chem. 2018, 61, 6364–6378.
  3. Matthews, J. H.; Liang, X.; Paul, V. J.; Luesch, H. “A Complementary Chemical and Genomic Screening Approach for Druggable Targets in the Nrf2 Pathway and Small Molecule Inhibitors to Overcome Cancer Cell Drug Resistance” ACS Chem. Biol. 2018, 13, 1189–1199.  
  4. Al-Awadhi, F. A.; Paul, V. J.; Luesch, H. “Structural Diversity and Anticancer Activity of Marine-Derived Elastase Inhibitors: Key Features and Mechanisms Mediating the Antimetastatic Effects in Invasive Breast Cancer” ChemBioChem 2018, 19, 815–825.
  5. Al-Awadhi, F. H.; Law, B. K.; Paul, V. J.; Luesch, H. “Grassystatins D–F, Potent Aspartic Protease Inhibitors from Marine Cyanobacteria as Potential Antimetastatic Agents Targeting Invasive Breast Cancer” J. Nat. Prod. 2017, 80, 2969–2986.
  6. Bousquet, M. S.; Ma, J. J.; Ratnayake, R.; Havre, P. A.; Yao, J.; Dang, N. H.; Paul, V. J.; Carney, T. J.; Dang, L. H.; Luesch, H. “Multidimensional Screening Platform for Simultaneously Targeting Oncogenic KRAS and Hypoxia-Inducible Factors Pathways in Colorectal Cancer” ACS Chem. Biol. 2016, 11, 1322–1331.
  7. Montaser, R.; Paul, V. J.; Luesch, H. “Modular Strategies for Structure and Function Employed by Marine Cyanobacteria: Characterization and Synthesis of Pitinoic Acids” Org. Lett. 2013, 15, 4050‒4053.
  8. Salvador, L. A.; Taori, K.; Biggs, J. S.; Jakoncic, J.; Ostrov, D. A.; Paul, V. J.; Luesch, H. “Potent Elastase Inhibitors from Cyanobacteria: Structural Basis and Mechanisms Mediating Cytoprotective and Anti-Inflammatory Effects in Bronchial Epithelial Cells” J. Med. Chem. 2013, 56, 1276‒1290.
  9. Kwan, J. C.; Meickle, T.; Ladwa, D.; Teplitski, M.; Paul, V.; Luesch, H. “Lyngbyoic Acid, a ‘Tagged’ Fatty Acid from a Marine Cyanobacterium, Disrupts Quorum Sensing in Pseudomonas aeruginosaMol. BioSyst. 2011, 7, 1205‒1216.
  10. Liu, Y.; Salvador, L. A.; Byeon, S.; Ying, Y.; Kwan, J. C.; Law, B. K.; Hong, J.; Luesch, H. “Anticolon Cancer Activity of Largazole, a Marine-Derived Tunable Histone Deacetylase Inhibitor” J. Pharmacol. Exp. Ther. 2010, 335, 351–361.
  11. Liu, Y.; Law, B. K.; Luesch, H. “Apratoxin A Reversibly Inhibits the Secretory Pathway by Preventing Cotranslational Translocation” Mol. Pharmacol. 2009, 76, 91–104.
  12. Ying, Y.; Taori, K.; Kim, H.; Hong, J.; Luesch, H. “Total Synthesis and Molecular Target of Largazole, a Histone Deacetylase Inhibitor” J. Am. Chem. Soc. 2008, 130, 8455–8459.
  13. Liu, Y.; Kern, J. T.; Walker, J. R.; Johnson, J. A.; Schultz, P. G.; Luesch, H. “A Genomic Screen for Activators of the Antioxidant Response Element” Proc. Natl. Acad. Sci. USA 2007, 104, 5205–5210.
  14. Luesch, H.; Chanda, S. K.; Raya, R. M.; DeJesus, P. D.; Orth, A. P.; Walker, J. R.; Izpisúa Belmonte, J. C.; Schultz, P. G. “A Functional Genomics Approach to the Mode of Action of Apratoxin A” Nature Chem. Biol. 2006, 2, 158–167.
  15. Luesch, H.; Wu, T. Y. H.; Ren, P.; Gray, N. S.; Schultz, P. G.; Supek, F. “A Genome-Wide Overexpression Screen in Yeast for Small-Molecule Target Identification” Chem. Biol. 2005, 12, 55–63.

Related Reviews:

  1. Liang, X.; Luo, D.; Luesch, H. “Advances in Exploring the Therapeutic Potential of Marine Natural Products” Pharmacol. Res. 2019, 147, 104373.
  2. Al-Awadhi, F. H.; Salvador, L. A.; Luesch, H. Chapter 7: Screening Strategies for Drug Discovery and Target Identification. In Marine Biomedicine: From Beach to Bedside. Baker, B.J., Ed. CRC Press, Boca Raton, Florida, 2016, pp. 135–165.
  3. Salvador-Reyes, L. A.; Luesch, H. “Biological Targets and Mechanisms of Action of Natural Products from Marine Cyanobacteria” Nat. Prod. Rep. 2015, 32, 478–503.
  4. Salvador, L. A.; Luesch, H. “Discovery and Mechanism of Natural Products as Modulators of Histone Acetylation” Curr. Drug. Targets 2012, 13, 1029‒1047.
  5. Kwan, J. C.; Luesch, H. “Weapons in Disguise – Activating Mechanisms and Protecting Group Chemistry in Nature” Chem. Eur. J. 2010, 16, 13020–13029.
  6. Luesch, H. “Towards High-Throughput Characterization of Small Molecule Mechanisms of Action” Mol. BioSyst. 2006, 2, 609–620.

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