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Published on: May 20, 2015
CYP1-bioactivated 2,4-diaryl-substituted pyridine analogues with remarkable activity in a breast cancer in vitro
Ketan Ruparelia1, Dyan N Ankrett1, Kenneth J M Beresford1
1Leicester School of Pharmacy, De Montfort University, Leicester, United Kingdom.
Abstract:
A series of 2,4-diaylpyridine analogues 8(1-9) was synthesised and evaluated for antiproliferative activity against a panel of human tumour and non-tumour breast cell lines that was characterised for CYP1 A1, A2 and B1 isoforms expression. Diarylpyridine 8 (6) was the most potent analogue with high cytotoxicity towards MDA-MB-468 cells (IC50 = 0.08 μM) and no toxicity towards MCF-10 A cells (IC50 = 100 μM). In vitro enzyme inhibition studies revealed that CYP1 isozymes were responsible for the metabolism and consequent bioactivation of 8 (6). CYP1-catalysed metabolism experiments using 8 (6) revealed the formation of four main metabolites (M1-4) that were characterised by LC-MS analysis. It was found that the primary metabolisation route for 8 (6) consisted in the dealkylation of its 3,4-methylenedioxy A-ring functionality to generate the toxic catechol metabolite M2. The latter was synthesised (9), co-eluted with samples spiked with original CYP1-generated metabolites and evaluated for antiproliferative activity. Our studies confirmed that 9 was the CYP1-generated metabolite (M2) exhibiting cytotoxic activities at low micromolar level against all cell lines in the panel regardless of their expression of CYP1 enzymes. In summary, we demonstrated the pro-drug mode of action of the tumour-selective 8 (6), which upon CYP1-mediated conversion to toxic metabolites, was capable of exerting antiproliferative activity in breast cancer cells.
Insights
A novel diarylpyridine analogue, 8(6), shows potent anticancer activity against breast cancer cells by acting as a prodrug. Upon activation by CYP1 enzymes, it converts to a toxic metabolite, selectively killing tumor cells without harming normal cells.
Area of Science:
- Medicinal Chemistry
- Pharmacology
- Cancer Biology
Background:
- Development of novel anticancer agents targeting breast cancer is crucial.
- Understanding drug metabolism and activation pathways, particularly involving Cytochrome P450 (CYP) enzymes, is key for drug efficacy and selectivity.
- Selective toxicity towards tumor cells over normal cells is a desirable characteristic for chemotherapeutic agents.
Purpose of the Study:
- To synthesize and evaluate a series of 2,4-diarylpyridine analogues for antiproliferative activity against breast cancer cell lines.
- To investigate the role of CYP1 isozymes in the metabolism and bioactivation of potent diarylpyridine analogues.
- To identify and characterize the metabolites responsible for the observed cytotoxic effects.
Main Methods:
- Synthesis of 2,4-diarylpyridine analogues.
- Antiproliferative assays against human tumor and non-tumor breast cell lines.
- In vitro enzyme inhibition studies with CYP1 isozymes (CYP1A1, CYP1A2, CYP1B1).
- LC-MS analysis for metabolite identification.
- Synthesis and antiproliferative evaluation of a key metabolite.
Main Results:
- Diarylpyridine analogue 8(6) exhibited potent cytotoxicity against MDA-MB-468 breast cancer cells (IC50 = 0.08 μM) with minimal toxicity to MCF-10A normal cells (IC50 = 100 μM).
- CYP1 isozymes were identified as responsible for the metabolism and bioactivation of 8(6).
- The primary metabolic pathway involved dealkylation of the methylenedioxy A-ring to form a catechol metabolite (M2), which was synthesized and confirmed as the active cytotoxic agent against all tested cell lines.
Conclusions:
- The tumor-selective diarylpyridine analogue 8(6) functions as a prodrug, exerting its antiproliferative effect through CYP1-mediated bioactivation.
- The generated catechol metabolite (M2) is responsible for the potent, broad-spectrum cytotoxicity observed.
- This study highlights a promising strategy for developing targeted breast cancer therapies via enzyme-activated prodrugs.
