Non-steroidal anti-inflammatory drugs (NSAIDs) inhibit vascular smooth muscle cell proliferation via differential effects on the cell cycle

Abstract

Abnormal vascular smooth muscle cell (VSMC) proliferation plays an important role in the pathogenesis of both atherosclerosis and restenosis. Recent studies suggest that high-dose salicylates, in addition to inhibiting cyclooxygenase activity, exert an antiproliferative effect on VSMC growth both in-vitro and in-vivo. However, whether all non-steroidal anti-inflammatory drugs (NSAIDs) exert similar antiproliferative effects on VSMCs, and do so via a common mechanism of action, remains to be shown. In this study, we demonstrate that the NSAIDs aspirin, sodium salicylate, diclofenac, ibuprofen, indometacin and sulindac induce a dose-dependent inhibition of proliferation in rat A10 VSMCs in the absence of significant cytotoxicity. Flow cytometric analyses showed that exposure of A10 cells to diclofenac, indometacin, ibuprofen and sulindac, in the presence of the mitotic inhibitor, nocodazole, led to a significant G0/G1 arrest. In contrast, the salicylates failed to induce a significant G1 arrest since flow cytometry profiles were not significantly different from control cells. Cyclin A levels were elevated, and hyperphosphorylated p107 was present at significant levels, in salicylate-treated A10 cells, consistent with a post-G1/S block, whereas cyclin A levels were low, and hypophosphorylated p107 was the dominant form, in cells treated with other NSAIDs consistent with a G1 arrest. The ubiquitously expressed cyclin-dependent kinase (CDK) inhibitors, p21 and p27, were increased in all NSAID-treated cells. Our results suggest that diclofenac, indometacin, ibuprofen and sulindac inhibit VSMC proliferation by arresting the cell cycle in the G1 phase, whereas the growth inhibitory effect of salicylates probably affects the late S and/or G2/M phases. Irrespective of mechanism, our results suggest that NSAIDs might be of benefit in the treatment of certain vasculoproliferative disorders.

Nonsteroidal Anti-inflammatory Drugs Inhibit Vascular Smooth Muscle Cell Proliferation by Enabling the Ca2+-dependent Inactivation of Calcium Release-activated Calcium/Orai Channels Normally Prevented by Mitochondria

“…As stated above, NSAIDs inhibit VSMC proliferation and DNA synthesis in vivo and in vitro without cellular toxicity and independently of cyclooxygenase (4,6,7). Consistently, our results show that NSAIDs diminish A10 cell proliferation at roughly the same concentrations that inhibit SOCE.…”

“…A series of NSAIDs, including aspirin, ibuprofen, indomethacin, and sulindac, induce a dose-dependent inhibition of proliferation in A10 cells (6,7), a VSMC cell line derived from embryonic rat aorta. The effects of NSAIDs occur in the absence of cytotoxicity and are independent of cyclooxygenase (7).…”

Targeting the cell cycle machinery for the treatment of cardiovascular disease

“…The activity of the cyclin±CDK complexes, and consequently cell cycle progression, is regulated negatively by the cyclin-dependent kinase inhibitors (CDKIs) Pines et al 1997;Brooks et al 1998). The CDKIs are regulated by degradation which occurs in a cyclin±CDK complex-dependent manner.…”

“…For example, doxazosin is an ¬-adrenergic receptor antagonist that inhibits VSMC proliferation by reducing phosphorylation of the retinoblastoma protein and blocking the G1±S transition in-vitro (Kintscher et al 2000). Another class of drugs that has been found to have an unexpected effect on the cell cycle are the non-steroidal anti-inflammatory drugs (NSAIDs) (Marra et al 2000;Brooks et al 2003). It has been observed that high doses of salicylates cause cell cycle arrest in VSMCs post-S-phase whereas non-salicylate NSAIDs, such as ibuprofen, sulindac and indometacin, inhibit VSMC proliferation at the G1±S border (Brooks et al 2003).…”

“…Another class of drugs that has been found to have an unexpected effect on the cell cycle are the non-steroidal anti-inflammatory drugs (NSAIDs) (Marra et al 2000;Brooks et al 2003). It has been observed that high doses of salicylates cause cell cycle arrest in VSMCs post-S-phase whereas non-salicylate NSAIDs, such as ibuprofen, sulindac and indometacin, inhibit VSMC proliferation at the G1±S border (Brooks et al 2003). The doses that cause these effects, although within the normal pharmacological range, are quite high for long-term use.…”