ASR490, a Small Molecule, Overrides Aberrant Expression of Notch1 in Colorectal Cancer

Withaferin A: A Dietary Supplement with Promising Potential as an Anti-Tumor Therapeutic for Cancer Treatment - Pharmacology and Mechanisms

Cancer, as the leading cause of death worldwide, poses a serious threat to human health, making the development of effective tumor treatments a significant challenge. Natural products continue to serve as crucial resources for drug discovery. Among them, Withaferin A (WA), the most active phytocompound extracted from the renowned dietary supplement Withania somnifera (L.) Dunal, exhibits remarkable anti-tumor efficacy. In this manuscript, we aim to comprehensively summarize the pharmacological characteristics of WA as a potential anti-tumor drug candidate, with the objective of contributing to its further development and the discovery of prospective drugs. Through an extensive review of literature from PubMed, Science Direct, and Web of Science, we have gathered substantial evidence showcasing WA's significant anti-tumor effects against a wide range of cancers in both in vitro and in vivo studies. Mechanistically, WA exerts its anti-tumor influence by inducing cell cycle arrest, apoptosis, autophagy, and ferroptosis. Additionally, it inhibits cell proliferation, cancer stem cells, tumor metastasis, and also suppresses epithelial-mesenchymal transition (EMT) and angiogenesis. Several studies have identified direct target proteins of WA, such as vimentin, Hsp90, annexin II and mFAM72A, while BCR-ABL, Mortalin (mtHsp70), Nrf2, and c-MYB are potential targets of WA. Notwithstanding its remarkable anti-tumor efficacy, there are some limitations associated with WA, including potential toxicity and poor oral bioavailability, which need to be addressed when considering it as an anti-tumor candidate agent. Nevertheless, I given its promising anti-tumor attributes, WA remains an encouraging candidate for future drug development. Unveiling the exact target and comprehensive mechanism of WA's action represents a crucial research direction to pursue in the future.

Molecular interplay between NOX1 and autophagy in cadmium-induced prostate carcinogenesis

Chronic exposure to cadmium (Cd), a class I carcinogen, leads to malignant transformation of normal prostate epithelial cells (RWPE-1). The constant generation of Cd-induced ROS and resulting ER stress induces cellular responses that are needed for cell survival, and autophagy has an important role in this process. However, the mechanisms that regulate Cd-induced ROS and how these differ in terms of acute and chronic cadmium exposure remain unexplained. Here, we show that acute or chronic Cd exposure facilitates NOX1 assembly by activating its cytosolic regulators p47phox and p67phox in RWPE-1 cells. Upregulation of NOX1 complex proteins and generation of ROS activates unfolded protein response (UPR) via phosphorylation of protein kinase RNA-like endoplasmic reticulum kinase (PERK), eukaryotic initiation factor 2 alpha (eIF2α), and selective translation of activating transcription factor 4 (ATF4). Chronic Cd exposure constantly activates NOX1 complex and generates consistent ROS and ER stress that led to defective autophagy, wherein ATG5 expression is downregulated in contrast to acute Cd exposure. As a result, selective/defective autophagy creates depletion of autophagosome-lysosome fusion that gives a survival advantage to transforming cells, which is not available to RWPE-1 cells acutely exposed to Cd. Knockdown of key molecules in a lockstep manner directly affects the most downstream autophagy pathways in transforming cells. Overall, this study demonstrates that assembly of NOX1 complex proteins is indispensable for Cd-induced persistent ROS and controls ER stress-induced defective autophagy in mice and humans.

A small molecule inhibitor of Notch1 modulates stemness and suppresses breast cancer cell growth

Although breast cancer stem cells (BCSCs) are well characterized, molecularly targeting and eradicating this sub-population remains a challenge in the clinic. Recent studies have explored several signaling pathways that govern stem cell activation: We and others established that the Notch1 signaling plays a significant role in the proliferation, survival, and differentiation of BCSCs. Earlier, we reported that a newly developed small molecule, ASR490, binds to the negative regulatory region (NRR: The activation switch of the Notch receptor) of Notch1. In vitro results demonstrated that ASR490 significantly inhibited BCSCs (ALDH+ and CD44+/CD24-) and breast cancer (BC) growth at nM concentrations, and subsequently inhibited the colony- and mammosphere-forming abilities of BCSCs and BCs. ASR490 downregulated the expressions of Notch1 intracellular domain (NICD: The active form of Notch1) and its downstream effectors Hey1 and HES1. Inhibition of Notch1-NICD facilitated autophagy-mediated growth inhibition by triggering the fusion of autophagosome and autolysosome in BCSCs. ASR490 was found to be non-toxic to healthy cells as compared to existing Notch1 inhibitors. Moreover, oral administration of ASR490 abrogated BCSC and BC tumor growth in the in vivo xenograft models. Together our results indicate that ASR490 is a potential therapeutic agent that inhibits BC tumor growth by targeting and abolishing Notch1 signaling in BCSCs and BC cells.

Recent Advances in the Chemistry and Therapeutic Evaluation of Naturally Occurring and Synthetic Withanolides

Natural products are a major source of biologically active compounds that make promising lead molecules for developing efficacious drug-like molecules. Natural withanolides are found in many flora and fauna, including plants, algae, and corals, that traditionally have shown multiple health benefits and are known for their anti-cancer, anti-inflammatory, anti-bacterial, anti-leishmaniasis, and many other medicinal properties. Structures of these withanolides possess a few reactive sites that can be exploited to design and synthesize more potent and safe analogs. In this review, we discuss the literature evidence related to the medicinal implications, particularly anticancer properties of natural withanolides and their synthetic analogs, and provide perspectives on the translational potential of these promising compounds.