ABSTRACT
Background
Thymidylate synthase (TS) catalyses the only de novo pathway to produce thymidylate for DNA replication and repair and is an important target for cancer chemotherapy. Preexisting or acquired drug resistance in colorectal cancer (CRC) cells limits clinical efficacy of TS-targeting drugs. Cells selected for higher TS protein activity have lower sensitivity to TS-targeting chemotherapeutic agents (5-FU and raltitrexed) and show crossresistance to other chemotherapeutics (e.g., oxalilplatinum ). To prevent/delay treatment-induced resistance, novel therapeutic strategies are required.
Hypothesis
1. Computational design and consequent E7 structural modification allow newly synthesized Ddis with improved molecular properties and better in vivo pharmacokinetics and anticancer activity.
2. By targeting hTS and favouring its proteasomal degradation, the Ddis halt DNA synthesis, cause DNA damage and trigger apoptosis, with resulting cancer cell growth inhibition.
3. Combinations of the Ddis with DNA damage targeting agents can counter drug resistance.
Aims
1. to disclose the structural and mechanistic features of the Ddis:TS interaction.
2. to improve their potency and molecular properties, for a more favorable in vivo pharmacokinetics.
2. to clarify the link between the TS dimer disruption and its proteasomal degradation on one hand and DNA damage response on the other.
3. to show the capability of Ddis to halt drug-resistance development when given in combination with DNA damage-targeting drugs.
4.to achieve information on the efficacy of the newly synthesized Ddis in in vivo CRC models.
Expected Results
1. identification of at least 2 Ddis with suitable profiles to be progress towards advanced in vivo pre-clinical studies.
2. identification of two new Ddis active against a validated target such as TS and, by definitely reducing its cellular levels, able to halt drug resistance development.
Impact On Cancer
•disclosure of a new class of Ddis that, by dissociating the enzyme dimer, reduce its intracellular levels and lead to apoptosis by inducing a DNA damage response;
•proposal of synergistically-acting combinations of Ddis with drugs targeting the DNA damage, thus increasing their efficacy and reducing their doses.
•proving that these combinations can halt CRC drug resistance.
•providing new leads against CRC with promising biological properties to be developed further in a future
project to counteract therapeutical drug resistance.
In perspective, this body of work should lead to savings in therapy costs, decrease of side effects and improvement of the patient's life quality, with faster recovery and return to active life and the corresponding general economic advantages.