Rhamnetin Prevents Bradykinin-Induced Expression of Matrix Metalloproteinase-9 in Rat Brain Astrocytes by Suppressing Protein Kinase-Dependent AP-1 Activation.

Bradykinin (BK) has been recognized as a stimulant for matrix metalloproteinase (MMP)-9 expression, contributing to neuroinflammation. Modulating the BK/MMP-9 pathway offers potential in the treatment of neuroinflammatory disorders. Rhamnetin (RNT), a flavonoid compound known for its antioxidant and anti-inflammatory effects, has shown promise. However, the specific mechanisms through which RNT inhibits BK-induced MMP-9 expression remain unclear. Therefore, this study aims to delve into the intricate mechanisms underlying this process. Here, we initially demonstrated that RNT effectively attenuated BK-induced MMP-9 expression and its associated cell migration in rat brain astrocyte-1 (RBA-1) cells. Further investigation revealed that BK-driven MMP-9 protein, mRNA, and promoter activity linked to cell migration relied on c-Src, Pyk2, EGFR, PDGFR, PI3K/Akt, JNK1/2, and c-Jun. This was validated by the inhibition of these effects through specific inhibitors, a finding substantiated by the introduction of siRNAs targeting these signaling molecules. Notably, the phosphorylated levels of these signaling components induced by BK were significantly reduced by their respective inhibitors and RNT, underscoring the inhibitory role of RNT in this process. These findings indicate that, in RBA-1 cells, RNT diminishes the heightened induction of MMP-9 triggered by BK through the inhibition of c-Src/Pyk2/PDGFR and EGFR/PI3K/Akt/JNK1/2-dependent AP-1 activation. This suggests that RNT holds promise as a potential therapeutic approach for addressing neuroinflammation in the brain.

6-Regioisomeric 5,8-quinolinediones as potent CDC25 inhibitors against colorectal cancers.

Precise and accurate control of cell cycle progression is required to maintain cell identity and proliferation. Failing to keep it will lead to genome instability and tumorigenesis. Cell Division Cycle 25 (CDC25) phosphatases are the key to regulating the activity of the master cell cycle controller, cyclin-dependent kinases (CDKs). Dysregulation of CDC25 has been shown to associate with several human malignancies. Here, we reported a series of derivatives of the CDC25 inhibitor, NSC663284, bearing quinones as core scaffolds and morpholin alkylamino side chains. Among these derivatives, the cytotoxic activity of the 6-isomer of 5,8-quinolinedione derivatives (6b, 16b, 17b, and 18b) displayed higher potency against colorectal cancer (CRC) cells. Compound 6b possessed the most antiproliferative activity, with IC50 values of 0.59 µM (DLD1) and 0.44 µM (HCT116). The treatment of compound 6b resulted in a remarkable effect on cell cycle progression, blocking S-phase progression in DLD1 cells straight away while slowing S-phase progression and accumulated cells in the G2/M phase in HCT116 cells. Furthermore, we showed that compound 6b inhibited CDK1 dephosphorylation and H4K20 methylation in cells. The treatment with compound 6b induced DNA damage and triggered apoptosis. Our study identifies compound 6b as a potent CDC25 inhibitor that induces genome instability and kills cancer cells through an apoptotic pathway, deserving further investigation to fulfill its candidacy as an anti-CRC agent.

Anti-Inflammatory Effects of Rhamnetin on Bradykinin-Induced Matrix Metalloproteinase-9 Expression and Cell Migration in Rat Brain Astrocytes.

Bradykinin (BK) has been shown to induce matrix metalloproteinase (MMP)-9 expression and participate in neuroinflammation. The BK/MMP-9 axis can be a target for managing neuroinflammation. Our previous reports have indicated that reactive oxygen species (ROS)-mediated nuclear factor-kappaB (NF-κB) activity is involved in BK-induced MMP-9 expression in rat brain astrocytes (RBA-1). Rhamnetin (RNT), a flavonoid compound, possesses antioxidant and anti-inflammatory effects. Thus, we proposed RNT could attenuate BK-induced response in RBA-1. This study aims to approach mechanisms underlying RNT regulating BK-stimulated MMP-9 expression, especially ROS and NF-κB. We used pharmacological inhibitors and siRNAs to dissect molecular mechanisms. Western blotting and gelatin zymography were used to evaluate protein and MMP-9 expression. Real-time PCR was used for gene expression. Wound healing assay was applied for cell migration. 2',7'-dichlorodihydrofluorescein diacetate (H2DCF-DA) and nicotinamide adenine dinucleotide phosphate (NADPH) oxidase (NOX) were used for ROS generation and NOX activity, respectively. Promoter luciferase assay and chromatin immunoprecipitation (ChIP) assay were applied to detect gene transcription. Our results showed that RNT inhibits BK-induced MMP-9 protein and mRNA expression, promoter activity, and cell migration in RBA-1 cells. Besides, the levels of phospho-PKCδ, NOX activity, ROS, phospho-ERK1/2, phospho-p65, and NF-κB p65 binding to MMP-9 promoter were attenuated by RNT. In summary, RNT attenuates BK-enhanced MMP-9 upregulation through inhibiting PKCδ/NOX/ROS/ERK1/2-dependent NF-κB activity in RBA-1.

Design, synthesis and biological evaluation of bisindole derivatives as anticancer agents against Tousled-like kinases.

This study presents the design, synthesis, and characterization of bisindole molecules as anti-cancer agents against Tousled-like kinases (TLKs). We show that compound 2 composed of an indirubin-3'-oxime group linked with a (N-methylpiperidin-2-yl)ethyl moiety possessed inhibitory activity toward both TLK1 and TLK2 in vitro and diminished the phosphorylation level of the downstream substrate anti-silencing function 1 (ASF1) in replicating cells. The treatment of compound 2 impaired DNA replication, slowed S-phase progression, and triggered DNA damage response in replicating cells. Structure optimization further discovered six derivatives exhibiting potent TLK inhibitory activity and revealed the importance of the tertiary amine-containing moiety of the side chain. Moreover, the derivatives 6, 17, 19, and 20 strongly suppressed the growth of triple-negative breast cancer MDA-MB-231 cells, non-small cell lung cancer A549 cells, and colorectal cancer HCT-116 cells, while normal lung fibroblast MRC5 and IMR90 cells showed a lower response to these compounds. Taken together, this study identifies tertiary amine-linked indirubin-3'-oximes as potent anticancer agents that inhibit TLK activity.