Advances in cell biology: contribution to drug modern design
PhD
1. EVALUATION OF A NEW CHEMOTYPE OF
TUBULIN MODULATORS OF THE VINCA DOMAIN
GONZALO SÁEZ CALVO
OCTOBER 23rd, 2015
2. Introduction. General information
Cancer (Hippocrates, V BC): Group of diseases, mostly non-
hereditary, that allow cells to escape homeostatic control
Main features: Induction of angiogenesis (metastasis), invasion of
healthy tissues, evasion of immune system and insensitivity to
anti-growth signals
14.1 millions new cases. 8.2 millions deaths related (~15% total)
9% of total budget on research in Spain is invested on the study of
cancer
3. Introduction. Treatments
Surgery
As a treatments or as a
diagnostic tool
Radiotherapy
Ionizing radiation
Chemotherapy
Hormones
Breast or prostate
cancer
Immune
system
First response
against
carcinogens
Bone marrow
transplant
Leukemia
Genes
Interaction with
cancer-related
genes
4. Introduction. Chemotherapy
Replication of the
genetic material
Alkylating agents
Platinum derivatives
Topoisomerases inhibitors
Intercalating agents
Machinery of cell
division
Agents against kinases
Modulators of cytoskeleton
(kinesins, microtubules)
5. Introduction. Resistances
Mutations in p53 allow cell to keep replicating
p53-mediated pathway
Etoposide changes topoisomerase localization
Modifications on specific proteins
Proteins that form conjugates, immune system
activation, DNA repair proteins, ABC proteins (P-gP)
Enhanced expression of proteins
6. Introduction. Resistances
Aller et al., 2009
MDR phenotype
Leukemia, stomach, breast,
ovary or pancreas cancer
Lipophilicity and hydrogen bonds
donors are major determinants
7. Introduction. Microtubules
Dr. Eva Nogales
Long, relatively stiff and highly
dynamic hollow tubes. 24nm of
diameter. 13 parallel proto-
filaments of tubulin
Structure of cilia and flagella,
intracellular transport,
machinery of chromosome
segregation
Grow out from centrosomes to
cell periphery (polarity)
α-monomer
β-monomer
11. Introduction. Microtubule dynamics
Dynamic instability
Transitions between
growth and fast shrinkage
phases
Treadmilling
Constant length
Net flux from minus end to
plus end
Allows microtubule
movement
14. Goals
Biological, biochemical and structural characterization of the
cytotoxic activity of a molecule with a new chemical structure type
Evaluation and quantification of the activity of the studied molecule and six structural
derivatives
Determination of the biological target
Characterization of the binding site, the bounded ligands conformation and their
molecular mechanisms of action
Measurement of the biochemical parameters of the binding (stoichiometry, binding
constants and kinetic constants)
Study of the relations between structure and activity
Comparison between effects induced by action of the studied ligands, and those
induced by action of model drugs
15. Conclusions
CSCD compounds are antimitotic drugs whose effects are not
affected by P-gP overexpression
All of them bind to tubulin in the vinca domain with a micromolar
affinity
Tubulin oligomerizes in helical structures in the presence of
studied compounds
Two π-π stacks between compound and β-tubulin contribute in a
critical way to ligand binding
Those compounds with major structural differences are the ones whose
stoichiometries are slightly over the 1:1 ratio
16. Conclusions
Binding of vinblastine favors the formation of a curved tubulin
structure that prevents its bonding with other tubulin dimers, but binding
of compound 1 favors the formation of a straightened
structure that may facilitates certain level of tubulin association
There is an inverse relation between size and polarity of the
inward-facing group and the observed affinity
