A Novel Competitive Binding Screening Assay Reveals Sennoside B as a Potent Natural Product Inhibitor of TNF-α

Sennoside B inhibits malignant phenotypes of triple-negative breast cancer cells and represses ERK/AKT/STAT5 signaling

Triple-negative breast cancer (TNBC) is the most lethal subtype of breast cancer. Treatment alternatives for TNBC are very limited and new therapeutic drugs are needed. Sennoside B (SB) is a dianthrone glycoside that has shown antitumor activity in osteosarcoma. However, the role of SB in TNBC remains unclear. This study aims to investigate the role and potential mechanism of SB in TNBC. MTT, colony formation, scratch, and Transwell assays were conducted to examine the malignant behaviors of TNBC cells under different doses of SB treatment. RT-qPCR and western blotting were utilized to detect mRNA or protein levels of molecules. The results revealed that SB treatment dose-dependently restrained TNBC cell proliferation, migration, invasiveness as well as epithelial-mesenchymal transition. Mechanistically, SB suppressed extracellular signal-regulated kinase (ERK), Ak strain transforming protein (AKT), and signal transducer and activator of transcription 5 (STAT5) phosphorylation in TNBC cells. In conclusion, SB treatment impairs the cell aggressiveness of TNBC and blocks ERK/AKT/STAT5 signaling in TNBC cells.

Recent Advances in the Discovery of Novel Drugs on Natural Molecules

Natural products (NPs) are always a promising source of novel drugs for tackling unsolved diseases [...].

Naturally occurring small molecules with dual effect upon inflammatory signaling pathways and endoplasmic reticulum stress response

The endoplasmic reticulum (ER) is determinant to maintain cellular proteostasis. Upon unresolved ER stress, this organelle activates the unfolded protein response (UPR). Sustained UPR activates is known to occur in inflammatory processes, deeming the ER a potential molecular target for the treatment of inflammation. This work characterizes the inflammatory/UPR-related molecular machinery modulated by an in-house library of natural products, aiming to pave the way for the development of new selective drugs that act upon the ER to counter inflammation-related chronic diseases. Starting from a library of 134 compounds of natural occurrence, mostly occurring in medicinal plants, nontoxic molecules were screened for their inhibitory capacity against LPS-induced nuclear factor kappa B (NF-κB) activation in a luciferase-based reporter gene assay. Since several natural products inhibited NF-κB expression in THP-1 macrophages, their effect on reactive oxygen species (ROS) production and inflammasome activation was assessed, as well as their transcriptional outcome regarding ER stress. The bioactivities of several natural products are described herein for the first time. We report the anti-inflammatory potential of guaiazulene and describe 5-deoxykaempferol as a novel inhibitor of inflammasome activation. Furthermore, we describe the dual potential of 5-deoxykaempferol, berberine, guaiazulene, luteolin-4'-O-glucoside, myricetin, quercetagetin and sennoside B to modulate inflammatory signaling ER stress. Our results show that natural products are promising molecules for the discovery and pharmaceutical development of chemical entities able to modulate the inflammatory response, as well as proteostasis and the UPR.

Small-molecule modulators of tumor necrosis factor signaling

Tumor necrosis factor (TNF) is a pleiotropic cytokine with a major role in immune system homeostasis and is involved in many inflammatory and autoimmune diseases, such as rheumatoid arthritis (RA), psoriasis, Alzheimer's disease (AD), and multiple sclerosis (MS). Thus, TNF and its receptors, TNFR1 and TNFR2, are relevant pharmacological targets. Biologics have been developed to block TNF-dependent signaling cascades, but they display serious side effects, and their pharmacological effectiveness decreases over time because of their immunogenicity. In this review, we present recent discoveries in small molecules targeting TNF and its receptors and discuss alternative strategies for modulating TNF signaling. Teaser: This review presents several recent and innovative strategies for the modulation of tumor necrosis factor function, with a focus on small molecules.