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Using cyclooxygenase-2 inhibitors as molecular platforms to develop a new class of apoptosis-inducing agents
Jiuxiang Zhu1, Xueqin Song, Ho-Pi Lin
1Division of Medicinal Chemistry and Pharmacognosy, College of Pharmacy, The Ohio State University, 500 W. 12th Avenue, Columbus, OH 43210-1291, USA.
Background:
The cyclooxygenase-2 (COX-2) inhibitor celecoxib is thought to act as a chemopreventive agent by sensitizing cancer cells to apoptotic signals. Other COX-2 inhibitors, such as rofecoxib, are two orders of magnitude less potent than celecoxib at inducing apoptosis. The molecular structures of celecoxib and rofecoxib were used as starting points to examine the structural features that contribute to this discrepancy.
Methods:
We used a systematic chemical approach to modify the structures of celecoxib and rofecoxib to produce a series of compounds that were tested for their effects on the viability of human prostate cancer PC-3 cells and their ability to induce apoptosis in these cells. Cell viability was measured by the trypan blue dye exclusion assay, and apoptosis was measured by an enzyme-linked immunosorbent assay that quantifies DNA cleavage and by western blot detection of poly(ADP-ribose) polymerase (PARP) cleavage. Western blotting was used to monitor the effects of the compounds on phosphorylation of the serine/threonine kinase Akt and extracellular signal-regulated kinase 2 (ERK2), two components of celecoxib-induced apoptosis signaling. Monte Carlo simulations were used to molecularly model the surface electrostatic potential and electron density of selected compounds. All statistical tests were two-sided.
Results:
The structural requirements for the induction of apoptosis in PC-3 cells were different from those for COX-2 inhibition. Structure-function analysis indicated that the induction of apoptosis by compounds derived from COX-2 inhibitors required a bulky terminal phenyl ring, a heterocyclic system with negative electrostatic potential, and a benzenesulfonamide or benzenecarboxamide moiety. These derivatives mediated apoptosis by facilitating the dephosphorylation of Akt and ERK2, irrespective of their COX-2 inhibitory activities.
Conclusion:
A new class of compounds that induce apoptosis by targeting Akt and ERK2 signaling pathways in human prostate cancer cells can be synthesized by modifying existing COX-2 inhibitors.
Insights
Modifying cyclooxygenase-2 (COX-2) inhibitors like celecoxib can create new compounds that induce apoptosis in prostate cancer cells by targeting Akt and ERK2 signaling. These compounds offer a novel approach to cancer chemoprevention.
Area of Science:
- Medicinal Chemistry
- Molecular Biology
- Cancer Research
Background:
- Cyclooxygenase-2 (COX-2) inhibitors, such as celecoxib, are investigated for chemopreventive properties by inducing apoptosis in cancer cells.
- Celecoxib is significantly more potent in inducing apoptosis than other COX-2 inhibitors like rofecoxib, suggesting structural differences are key.
- This study aimed to identify the specific structural features responsible for the differential apoptotic activity of COX-2 inhibitors.
Purpose of the Study:
- To systematically modify celecoxib and rofecoxib structures to understand their role in inducing apoptosis in human prostate cancer cells.
- To identify the structural requirements for apoptosis induction independent of COX-2 inhibition.
- To explore the mechanism by which these modified compounds induce apoptosis, focusing on signaling pathways.
Main Methods:
- Synthesized a series of modified COX-2 inhibitor compounds.
- Assessed cell viability using the trypan blue dye exclusion assay.
- Quantified apoptosis via ELISA for DNA cleavage and Western blotting for PARP cleavage.
- Monitored Akt and ERK2 phosphorylation using Western blotting.
- Employed Monte Carlo simulations for molecular modeling of electrostatic potential and electron density.
Main Results:
- Structural requirements for apoptosis induction differed from those for COX-2 inhibition.
- Key structural features for apoptosis included a bulky terminal phenyl ring, a negatively charged heterocyclic system, and a benzenesulfonamide or benzenecarboxamide group.
- Apoptosis was mediated by dephosphorylating Akt and ERK2, independent of COX-2 inhibitory activity.
Conclusions:
- A novel class of apoptosis-inducing compounds targeting Akt and ERK2 signaling pathways in prostate cancer can be developed by modifying existing COX-2 inhibitors.
- These findings provide a basis for designing new chemopreventive agents for prostate cancer.