Cirsiliol

28541047

Growth inhibition of the pathogen Staphylococcus aureus with currently available antibiotics is problematic in part due to bacterial biofilm protection. Although recently characterized natural products, including 3′,4′,5-trihydroxy-6,7-dimethoxy-flavone [1], 3′,4′,5,6,7-pentahydroxy-flavone [2], and 5-hydroxy-4′,7-dimethoxy-flavone [3], exhibit both antibiotic and biofilm inhibitory activities, the mode of action of such hydroxylated flavonoids with respect to S. aureus inhibition is yet to be characterized. Enzymatic digestion and high-resolution MS analysis of differentially expressed proteins from S. aureus with and without exposure to antibiotic flavonoids (1-3) allowed for the characterization of global protein alterations induced by metabolite treatment. A total of 56, 92, and 110 proteins were differentially expressed with bacterial exposure to 1, 2, or 3, respectively. The connectivity of the identified proteins was characterized using a search tool for the retrieval of interacting genes/proteins (STRING) with multitargeted S. aureus inhibition of energy metabolism and biosynthesis by the assayed flavonoids. Identifying the mode of action of natural products as antibacterial agents is expected to provide insight into the potential use of flavonoids alone or in combination with known therapeutic agents to effectively control S. aureus infection.

LC−MS/MS proteomics; Staphylococcus aureus; antibacterial flavonoids; multitargeted bacterial inhibition

Multitargeted Flavonoid Inhibition of the Pathogenic Bacterium Staphylococcus aureus: A Proteomic Characterization.

Elmasri WA1, Zhu R1, Peng W1, Al-Hariri M2, Kobeissy F2, Tran P, Hamood AN, Hegazy MF3, Pare PW1, Mechref Y1.

2017 Jul 7;

23902763

Radioresistance is a major cause of decreasing the efficiency of radiotherapy for non-small cell lung cancer (NSCLC). To understand the radioresistance mechanisms in NSCLC, we focused on the radiation-induced Notch-1 signaling pathway involved in critical cell fate decisions by modulating cell proliferation. In this study, we investigated the use of Notch-1-regulating flavonoid compounds as novel therapeutic drugs to regulate radiosensitivity in NSCLC cells, NCI-H1299 and NCI-H460, with different levels of radioresistance. Rhamnetin and cirsiliol were selected as candidate Notch-1-regulating radiosensitizers based on the results of assay screening for activity and pharmacological properties. Treatment with rhamnetin or cirsiliol reduced the proliferation of NSCLC cells through the suppression of radiation-induced Notch-1 expression. Indeed, rhamnetin and cirsiliol increased the expression of tumor-suppressive microRNA, miR-34a, in a p53-dependent manner, leading to inhibition of Notch-1 expression. Consequently, reduced Notch-1 expression promoted apoptosis through significant down-regulation of the nuclear factor-κB pathway, resulting in a radiosensitizing effect on NSCLC cells. Irradiation-induced epithelial-mesenchymal transition was also notably attenuated in the presence of rhamnetin and cirsiliol. Moreover, an in vivo xenograft mouse model confirmed the radiosensitizing and epithelial-mesenchymal transition inhibition effects of rhamnetin and cirsiliol we observed in vitro. In these mice, tumor volume was significantly reduced by combinational treatment with irradiation and rhamnetin or cirsiliol compared with irradiation alone. Taken together, our findings provided evidence that rhamnetin and cirsiliol can act as promising radiosensitizers that enhance the radiotherapeutic efficacy by inhibiting radiation-induced Notch-1 signaling associated with radioresistance possibly via miR-34a-mediated pathways.

Cancer Therapy; Cirsiliol; EMT; Lung Cancer; Natural Products; Notch-1; Radiation Biology; Radiosensitization; Rhamnetin; miR-34a

Rhamnetin and cirsiliol induce radiosensitization and inhibition of epithelial-mesenchymal transition (EMT) by miR-34a-mediated suppression of Notch-1 expression in non-small cell lung cancer cell lines.

Kang J1, Kim E, Kim W, Seong KM, Youn H, Kim JW, Kim J, Youn B.

2013 Sep 20;