QUIROGA RODRIGO
Congresos y reuniones científicas
Título:
DRUG DISCOVERY OF TLS INHIBITORS TO SELECTIVELY TARGET CANCER CELLS WITH HOMOLOGOUS RECOMBINATION REPAIR DEFICIENCIES
Autor/es:
GARCÍA, ALEJANDRA I.; VILLAFAÑEZ, FLORENCIA; QUIROGA, RODRIGO; BOCCO, JOSÉ L.; VILLARREAL, MARCOS; SORIA, GASTÓN
Lugar:
Salta
Reunión:
Workshop; PABMB-SAIB 2019; 2019
Resumen:
Translesion DNA Synthesis (TLS) and homologous recombination (HR) cooperate during S-phase to ensure replication forks integrity and cell
survival. Consequently, TLS inhibition emerges as a promising strategy for the therapeutic intervention of HR-deficient tumors by synthetic
lethality (SL) induction. Given the current lack of selective TLS pharmacological inhibitors to evaluate this hypothesis, we developed different
approaches to identify small molecules able to impair PCNA mono-ubiquitination, a key post-translational modification required for the efficient
activation of TLS. Initially, we developed a miniaturized WB assay using complementary antibodies that simultaneously detect ubi-PCNA and
total PCNA. Using this assay, we screened a library of 627 kinase inhibitors. We found that targeting the pro-survival kinase AKT leads to a strong
impairment of PCNA ubiquitination. Remarkably, such inhibition triggered the induction of SL in BRCA-deficient cells submitted to replication
stress. The follow-up strategy was to focus on the identification of PCNA ubiquitination inhibitors with more selective mechanisms of action. To
tackle this challenge, we designed a virtual screening approach to identify direct blockers of PCNA-ubiquitination through molecular modeling
from a 10K collection of structurally diverse small molecules. We found several putative compounds that block PCNA-ubiquitination in silico,
which after experimental validation led to the identification of a small group of strong PCNA ubiquitination inhibitors. Collectively, this work
shows for the first time that TLS inhibition can be achieved by the pharmacological impairment of PCNA ubiquitination and provides the proofof-concept of TLS inhibition as a therapeutic strategy to selectively kill HR-deficient cells.
survival. Consequently, TLS inhibition emerges as a promising strategy for the therapeutic intervention of HR-deficient tumors by synthetic
lethality (SL) induction. Given the current lack of selective TLS pharmacological inhibitors to evaluate this hypothesis, we developed different
approaches to identify small molecules able to impair PCNA mono-ubiquitination, a key post-translational modification required for the efficient
activation of TLS. Initially, we developed a miniaturized WB assay using complementary antibodies that simultaneously detect ubi-PCNA and
total PCNA. Using this assay, we screened a library of 627 kinase inhibitors. We found that targeting the pro-survival kinase AKT leads to a strong
impairment of PCNA ubiquitination. Remarkably, such inhibition triggered the induction of SL in BRCA-deficient cells submitted to replication
stress. The follow-up strategy was to focus on the identification of PCNA ubiquitination inhibitors with more selective mechanisms of action. To
tackle this challenge, we designed a virtual screening approach to identify direct blockers of PCNA-ubiquitination through molecular modeling
from a 10K collection of structurally diverse small molecules. We found several putative compounds that block PCNA-ubiquitination in silico,
which after experimental validation led to the identification of a small group of strong PCNA ubiquitination inhibitors. Collectively, this work
shows for the first time that TLS inhibition can be achieved by the pharmacological impairment of PCNA ubiquitination and provides the proofof-concept of TLS inhibition as a therapeutic strategy to selectively kill HR-deficient cells.
