Using cyclooxygenase-2 inhibitors as molecular platforms to develop a new class of apoptosis-inducing agents.
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.


CONCLUSIONS
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.
Zhu
Jiuxiang
J
Division of Medicinal Chemistry and Pharmacognosy, College of Pharmacy, The Ohio State University, 500 W. 12th Avenue, Columbus, OH 43210-1291, USA.
Song
Xueqin
X
Lin
Ho-Pi
HP
Young
Donn C
DC
Yan
Shunqi
S
Marquez
Victor E
VE
Chen
Ching-Shih
CS
D000894:Anti-Inflammatory Agents, Non-Steroidal / Q000138:chemical synthesis* / Q000494:pharmacology; D016588:Anticarcinogenic Agents / Q000138:chemical synthesis* / Q000494:pharmacology; D017209:Apoptosis / Q000187:drug effects*; D015153:Blotting, Western; D000068579:Celecoxib; D051546:Cyclooxygenase 2; D004791:Enzyme Inhibitors / Q000138:chemical synthesis* / Q000494:pharmacology; D004797:Enzyme-Linked Immunosorbent Assay; D006801:Humans; D007527:Isoenzymes / Q000037:antagonists & inhibitors*; D007783:Lactones / Q000138:chemical synthesis; D008297:Male; D008565:Membrane Proteins; D019950:Mitogen-Activated Protein Kinase 1 / Q000187:drug effects* / Q000378:metabolism; D008958:Models, Molecular; D011451:Prostaglandin-Endoperoxide Synthases; D011471:Prostatic Neoplasms / Q000188:drug therapy* / Q000201:enzymology / Q000378:metabolism*; D017346:Protein Serine-Threonine Kinases; D011518:Proto-Oncogene Proteins / Q000187:drug effects* / Q000378:metabolism; D051057:Proto-Oncogene Proteins c-akt; D011720:Pyrazoles; D015398:Signal Transduction / Q000187:drug effects; D013329:Structure-Activity Relationship; D013449:Sulfonamides / Q000138:chemical synthesis; D013450:Sulfones; D014407:Tumor Cells, Cultured
D000894:Anti-Inflammatory Agents, Non-Steroidal; D016588:Anticarcinogenic Agents; D004791:Enzyme Inhibitors; D007527:Isoenzymes; D007783:Lactones; D008565:Membrane Proteins; D011518:Proto-Oncogene Proteins; D011720:Pyrazoles; D013449:Sulfonamides; D013450:Sulfones; C116926:rofecoxib; D051546:Cyclooxygenase 2; C496540:PTGS2 protein, human; D011451:Prostaglandin-Endoperoxide Synthases; C494918:AKT1 protein, human; D017346:Protein Serine-Threonine Kinases; D051057:Proto-Oncogene Proteins c-akt; D019950:Mitogen-Activated Protein Kinase 1; D000068579:Celecoxib