cyclin-d1 and rofecoxib

Although it is often assumed that the antitumor effects of nonsteroidal anti-inflammatory drugs (NSAIDs) are due to inhibition of cyclooxgenase (COX) activity, specifically COX-2, there is accumulating evidence that COX-2 independent mechanisms can also play an important role. Studies with sulindac sulfone (Aptosyn) and related derivatives have revealed a novel pathway of tumor growth inhibition and apoptosis mediated by activation of the guanosine 3',5' monophosphate (cGMP)-dependent enzyme protein kinase G (PKG). The present study indicates that concentrations of the NSAIDs celecoxib, indomethacin, and meclofenamic acid that inhibit growth of SW480 human colon cancer cells inhibit subcellular cGMP-phosphodiesterase (PDE) enzymatic activity and in intact cells induce a two- to threefold increase in intracellular levels of cGMP. This is associated with phosphorylation of the protein VASP, a marker of PKG activation, activation of JNK1 and a decrease in cellular levels of cyclin D1; effects seen with other agents that cause activation of PKG in these cells. On the other hand even a high concentration of the COX-2 specific inhibitor rofecoxib (500 microM) did not inhibit growth of SW480 cells. Nor did rofecoxib inhibit cGMP-PDE activity or cause other changes related to PKG activation in these cells. Since activation of the PKG pathways by celecoxib, indomethacin, and meclofenamic acid in this cell culture system required high concentrations of these compounds, it remains to be determined whether activation of this pathway contributes to the in vivo antitumor effects of specific NSAIDs.

Topics: Apoptosis; Celecoxib; Cell Adhesion Molecules; Cell Proliferation; Colonic Neoplasms; Cyclic GMP; Cyclic GMP-Dependent Protein Kinases; Cyclic Nucleotide Phosphodiesterases, Type 2; Cyclin D1; Cyclooxygenase Inhibitors; Enzyme Activation; Humans; Indomethacin; Lactones; Meclofenamic Acid; Microfilament Proteins; Mitogen-Activated Protein Kinase 8; Phosphoproteins; Phosphorylation; Pyrazoles; Sulfonamides; Sulfones; Tumor Cells, Cultured

A large number of epidemiological studies have shown that regular use of aspirinor other nonsteroidal anti-inflammatory drugs (NSAIDs) results in a 40-50% reduced risk of colorectal cancer (CRC). Furthermore, NSAIDs cause the regression of preexisting adenomas in patients with familial adenomatous polyposis and significantly inhibit tumor growth in animal models of CRC. To establish a CRC liver metastasis model, we implanted mouse colon tumor MC-26 cells into the splenic subcapsule of BALB/c mice, after which mice were given either standard chow or chow containing the cyclooxygenase (COX)-2-specific inhibitor rofecoxib, alone or in combination with the standard antineoplastic agents, 5-fluoruracil or irinotecan. After 14 days, mice that were given rofecoxib or irinotecan, but not 5-fluoruracil, had significantly smaller primary tumors and fewer metastases. Rofecoxib, at clinical anti-inflammatory plasma concentrations, enhanced the effects of both antineoplastic agents when used in combination. Biochemical analyses of the primary splenic tumor in rofecoxib-treated mice showed no alteration in COX-1 expression, but significant decreases in the expression of the tumor-promoting proteins COX-2, cyclin D1, cytosolic beta-catenin, matrix metalloproteinases-2 and -9, and vascular endothelial cell- derived growth factor. Rofecoxib also decreased growth-enhancing prostaglandin E(2) and tumor-suppressive interleukin-10, whereas antineoplastic interleukin-12 was increased. Two separate survival studies were performed. When mice were fed chow containing 0.01% rofecoxib beginning on day 0 after tumor cell implantation, which achieved clinical anti-inflammatory plasma concentrations, survival time was significantly longer compared with mice given control chow. After 30 days, mortality in the control group was 90%, whereas only one mouse (5%) treated with rofecoxib had died after 30 days. In the second survival study, all of the mice were initially fed with regular chow after tumor cell implantation. On day 7, mice were randomly divided into three dietary groups: control chow, low-dose (0.01%) rofecoxib chow, and high-dose (0.025%) rofecoxib chow. After 28 days, mortality was 100%, 20%, and 10% in control, low-, and high-dose rofecoxib fed groups, respectively. These studies demonstrate that rofecoxib decreases the growth and metastatic potential of CRC in mice through multiple mechanisms. These studies in mice also provide important information that supports the benef

Topics: Animals; Anti-Inflammatory Agents, Non-Steroidal; Antineoplastic Combined Chemotherapy Protocols; beta Catenin; Camptothecin; Cell Division; Colorectal Neoplasms; Cyclin D1; Cyclooxygenase 1; Cyclooxygenase 2; Cyclooxygenase 2 Inhibitors; Cyclooxygenase Inhibitors; Cytoskeletal Proteins; Dinoprostone; Drug Synergism; Endothelial Growth Factors; Fluorouracil; Intercellular Signaling Peptides and Proteins; Interleukin-10; Interleukin-12; Irinotecan; Isoenzymes; Lactones; Liver Neoplasms, Experimental; Lymphokines; Male; Matrix Metalloproteinase 2; Matrix Metalloproteinase 9; Membrane Proteins; Mice; Mice, Inbred BALB C; Neoplasm Transplantation; Prostaglandin-Endoperoxide Synthases; Sulfones; Trans-Activators; Tumor Cells, Cultured; Vascular Endothelial Growth Factor A; Vascular Endothelial Growth Factors