Rex, D. A. B. | bioRxiv Science

bioRxiv2026

Phosphoproteomic profiling reveals signaling pathways modulated by Annona muricata leaf extract in oral adenosquamous carcinoma cells

Phosphorylation driven dysregulation of intracellular signaling networks is a central feature of cancer initiation, progression, and therapeutic resistance. Although Annona muricata leaf extracts have demonstrated anticancer activity across multiple experimental models, the underlying molecular mechanisms particularly at the level of phosphorylation dependent signaling remain poorly understood. In this study, we employed a tandem mass tag TMT-based quantitative phosphoproteomic approach to systematically characterize signaling alterations induced by methanolic Annona muricataleaf extract (AME) in oral squamous cell carcinoma (OSCC) CAL-27 cells. Functional assays revealed that AME significantly inhibited cell proliferation, migration, and clonogenic survival. Global phosphoproteomic profiling identified 6,362 phosphopeptides corresponding to 1,964 unique phosphorylation sites across nearly 7,000 phosphoproteins. AME treatment induced widespread, time-dependent hypophosphorylation, indicating a coordinated suppression of oncogenic signaling networks. Pathway and network analyses revealed marked inhibition of signaling pathways associated with key oncogenic kinases, including cyclin-dependent kinases (CDKs), mitogen-activated protein kinases (MAPKs), and signaling modules linked to EGFR and mTOR pathways. Kinase-substrate enrichment and kinome mapping further demonstrated reduced inferred activity of CDK and MAPK driven signaling, accompanied by suppression of cell cycle progression, mitosis, and checkpoint regulation. Collectively, these findings demonstrate that AME induces systems-level remodeling of phosphorylation dependent signaling networks, enforcing a growth-restrictive cellular state in OSCC cells. This study highlights quantitative phosphoproteomics as a powerful strategy for dissecting natural product mediated regulation of oncogenic signaling and provides mechanistic insight into the anticancer potential of Annona muricata.

cancer biology↗

bioRxiv2023

Identification of merozoite secreted repertoire and immuno-pharmacological inhibition of a novel host-parasite interaction to block malarial infection

BackgroundDuring the intra-erythrocytic proliferation of Plasmodium falciparum, the host erythrocyte invasion is regarded as a complex and tightly regulated process comprising multiple receptor-ligand interactions, and numerous secretory molecules. Proteins secreted sequentially from apical organelles of merozoites serve as adhesins that play a crucial role in RBC invasion and can serve as vaccine and therapeutic targets. MethodsPurified merozoites were triggered to discharge apical organelle contents by exposure to ionic conditions mimicking that of blood plasma. The secreted proteins were subjected to tandem mass spectrometry, and a well-characterized invasion ligand, RhopH3, was identified. A novel RhopH3 receptor, 14-3-3{square} was unearthed using a Bacterial two-hybrid approach. This interaction was confirmed using multiple biophysical and biochemical approaches. We were successful in disrupting this interaction using a de novo peptide binder of 14-3-3{square}, and we subsequently assessed its effect on merozoite invasion. ResultsA total of 66 proteins were identified in the secretory fraction with apical organellar or merozoite membrane localization. The well-known adhesin, RhopH3 was also identified and its interaction with the host phosphopeptide-binding protein, 14-3-3{square} was established. We also discovered a de novo peptide with the potency to disrupt this crucial interaction, thereby blocking merozoite invasion. ConclusionWe, for the first time, report the secretory repertoire of plasmodium merozoite. Our study shows the importance of the erythrocyte protein, 14-3-3{square} during the invasion process and paves the way for developing anti-malarial peptides or small molecules that inhibit the host-pathogen interaction, hence abrogating the invasion process.

microbiology↗