PTD-p65-P1 Peptide

Ras farnesyltransferase inhibitor (FTI) exhibit antiproliferative and antiangiogenic effects through a mechanism that is poorly understood. Because of the known role of Ras in the activation of transcription factor NF-kappaB and because NF-kappaB-regulated genes can control cell survival and angiogenesis, we postulated that FTI mediates its effects in part by modulating NF-kappaB activation. Therefore, in the present study we investigated the effect of FTI, SCH 66336, on NF-kappaB and NF-kappaB-regulated gene expression activated by a variety of inflammatory and carcinogenic agents. We demonstrate by DNA-binding assay that NF-kappaB activation induced by tumor necrosis factor (TNF), phorbol 12-myristate 13-acetate, cigarette smoke, okadaic acid, and H(2)O(2) was completely suppressed by SCH 66336; the suppression was not cell type-specific. This FTI suppressed the activation of IkappaBalpha kinase (IKK), thus abrogating the phosphorylation and degradation of IkappaBalpha. Additionally, TNF-activated Ras and SCH 66336 inhibited the activation. Also, overexpression of Ras (V12) enhanced TNF-induced NF-kappaB activation, and adenoviral dominant-negative Ras (N17) suppressed the activation, thus suggesting the critical role of Ras in TNF signaling. SCH 66336 also inhibited the NF-kappaB-dependent reporter gene expression activated by TNF, TNFR1, TRADD, TRAF2, NIK, and IKK but not that activated by the p65 subunit of NF-kappaB. The TNF-induced NF-kappaB-regulated gene products cyclin D1, COX-2, MMP-9, survivin, IAP1, IAP2, XIAP, Bcl-2, Bfl-1/A1, TRAF1, and FLIP were all down-regulated by SCH 66336, which potentiated apoptosis induced by TNF and doxorubicin. Overall, our results indicate that SCH 66336 inhibited activation of NF-kappaB and NF-kappaB-regulated gene expressions induced by carcinogens and inflammatory stimuli, which may provide a molecular basis for the ability of SCH 66336 to suppress proliferation and angiogenesis.

The process of tumorigenesis requires cellular transformation, hyperproliferation, invasion, angiogenesis, and metastasis. Several genes that mediate these processes are regulated by the transcription factor nuclear factor-kappaB (NF-kappaB). The latter is activated by various carcinogens, inflammatory agents, and tumor promoters. Thus, agents that can suppress NF-kappaB activation have the potential to suppress carcinogenesis. Ursolic acid, a pentacyclic triterpene acid, has been shown to suppress the expression of several genes associated with tumorigenesis, but whether ursolic acid mediates its effects through suppression of NF-kappaB is not understood. In the study described in the present report, we found that ursolic acid suppressed NF-kappaB activation induced by various carcinogens including tumor necrosis factor (TNF), phorbol ester, okadaic acid, H(2)O(2), and cigarette smoke. These effects were not cell type specific. Ursolic acid inhibited DNA binding of NF-kappaB consisting of p50 and p65. Ursolic acid inhibited IkappaBalpha degradation, IkappaBalpha phosphorylation, IkappaBalpha kinase activation, p65 phosphorylation, p65 nuclear translocation, and NF-kappaB-dependent reporter gene expression. Ursolic acid also inhibited NF-kappaB-dependent reporter gene expression activated by TNF receptor, TNF receptor-associated death domain, TNF receptor-associated factor, NF-kappaB-inducing kinase, IkappaBalpha kinase, and p65. The inhibition of NF-kappaB activation correlated with suppression of NF-kappaB-dependent cyclin D1, cyclooxygenase 2, and matrix metalloproteinase 9 expression. Thus, overall, our results indicate that ursolic acid inhibits IkappaBalpha kinase and p65 phosphorylation, leading to the suppression of NF-kappaB activation induced by various carcinogens. These actions of ursolic acid may mediate its antitumorigenic and chemosensitizing effects.

Betulinic acid (BA), a pentacyclic triterpene isolated from the bark of the white birch tree, has been reported to be a selective inducer of apoptosis in tumor cells. It also exhibits anti-inflammatory and immunomodulatory properties. How BA mediates these effects is not known. Because of the critical role of the transcription factor NF-kappaB in growth modulatory, inflammatory, and immune responses, we postulated that BA modulates the activity of this factor. In this study we investigated the effect of BA on NF-kappaB and NF-kappaB-regulated gene expression activated by a variety of inflammatory and carcinogenic agents. BA suppressed NF-kappaB activation induced by TNF, PMA, cigarette smoke, okadaic acid, IL-1, and H(2)O(2). The suppression of NF-kappaB activation was not cell-type specific. BA suppressed the activation of IkappaBalpha kinase, thus abrogating the phosphorylation and degradation of IkappaBalpha. We found that BA inhibited NF-kappaB activated by TNFR 1, TNFR-associated death domain, TNFR-associated factor 2, NF-kappaB-inducing kinase, and IkappaBalpha kinase. Treatment of cells with this triterpinoid also suppressed NF-kappaB-dependent reporter gene expression and the production of NF-kappaB-regulated gene products such as cyclooxygenase-2 and matrix metaloproteinase-9 induced by inflammatory stimuli. Furthermore, BA enhanced TNF-induced apoptosis. Overall, our results indicated that BA inhibits activation of NF-kappaB and NF-kappaB-regulated gene expression induced by carcinogens and inflammatory stimuli. This may provide a molecular basis for the ability of BA to mediate apoptosis, suppress inflammation, and modulate the immune response.