Searching for natural products with antitumor and immune-enhancing activities is an important aspect of cancer research. Sargassum pallidum is an edible brown alga that has been used in Chinese traditional medicine for the treatment of tumors. However, the purification and application of its active components are still insufficient. In the present study, the polysaccharides from S. pallidum (SPPs) with antitumor and immune-enhancing activities were isolated and purified, and five polysaccharide fractions (SPP-0.3, SPP-0.5, SPP-0.7, SPP-1, and SPP-2) were obtained. The ratio of total saccharides, monosaccharide composition, and sulfated contents was determined, and their structures were analyzed by Fourier transform infrared spectroscopy. Moreover, bioactivity analysis showed that all five fractions had significant antitumor activity against three types of cancer cells (A549, HepG2, and B16), and can induce cancer cell apoptosis. In addition, the results indicated that SPPs can enhance the proliferation of immune cells and improve the expression levels of serum cytokines (IL-6, IL-1β, iNOS, and TNF-α). SPP-0.7 was identified as the most active fraction and selected for further purification, and its physicochemical properties and antitumor mechanism were further analyzed. Transcriptome sequencing result showed that SPP-0.7 can significantly induce the cell apoptosis, cytokine secretion, and cellular stress response process, and inhibit the normal physiological processes of cancer cells. Overall, SPPs and SPP-0.7 may be suitable for use as potential candidate agents for cancer therapy.

Searching for natural products with anti-tumor activity is an important aspect of cancer research. Seaweed polysaccharides from brown seaweed have shown promising anti-tumor activity; however, their structure, composition, and biological activity vary considerably, depending on many factors. In this study, 16 polysaccharide fractions were extracted and purified from three large brown seaweed species (Sargassum horneri, Scytosiphon lomentaria, and Undaria pinnatifida). The chemical composition analysis revealed that the polysaccharide fractions have varying molecular weights ranging from 8.889 to 729.67 kDa, and sulfate contents ranging from 0.50% to 10.77%. Additionally, they exhibit different monosaccharide compositions and secondary structures. Subsequently, their anti-tumor activity was compared against five tumor cell lines (A549, B16, HeLa, HepG_2, and SH-SY5Y). The results showed that different fractions exhibited distinct anti-tumor properties against tumor cells. Flow cytometry and cytoplasmic fluorescence staining (Hoechst/AO staining) further confirmed that these effective fractions significantly induce tumor cell apoptosis without cytotoxicity. qRT-RCR results demonstrated that the polysaccharide fractions up-regulated the expression of Caspase-3, Caspase-8, Caspase-9, and Bax while down-regulating the expression of Bcl-2 and CDK-2. This study comprehensively compared the anti-tumor activity of polysaccharide fractions from large brown seaweed, providing valuable insights into the potent combinations of brown seaweed polysaccharides as anti-tumor agents.

The insulin receptor (IR) plays a crucial role in the growth and metabolism of animals. However, there are still many questions regarding the IR in crustaceans, particularly their role in shrimp growth and glucose metabolism. In this study, we identified a novel insulin-like receptor gene in Litopenaeus vannamei and cloned its full length of 6439 bp. This gene exhibited a highly conserved sequence and structural characteristics. Phylogenetic analysis confirmed it as an unreported RTK2-type IR, namely, LvRTK2. Expression pattern analysis showed that LvRTK2 is primarily expressed in female reproductive and digestive organs. Through a series of in vivo and in vitro experiments, including glucose treatment, exogenous insulin treatment, and starvation treatment, LvRTK2 was confirmed to be involved in the endogenous glucose metabolic pathway of shrimp under different glucose variations. Moreover, long-term and short-term interference experiments with LvRTK2 revealed that the interference significantly reduced the shrimp growth rate and serum glucose clearance rate. Further studies indicated that LvRTK2 may regulate shrimp growth by modulating the downstream PI3K/AKT signaling pathway and a series of glucose metabolism events, such as glycolysis, gluconeogenesis, glycogen synthesis, and glycogenolysis. This report on the characteristics and functions of LvRTK2 confirms the important role of RTK2-type IRs in regulating shrimp growth and glucose metabolism.

Insulin-like peptide (ILP) signaling is a critical endocrine axis governing growth, metabolism, and reproduction in crustaceans. In decapods, the ILP family has diversified into four subtypes through gene duplication, yet the functional coordination among these ligands to buffer endocrine perturbations remains poorly understood. Building on our previous identification of insulin-type ILP ( LvIns ) as a key regulator of growth and glucose metabolism in Litopenaeus vannamei , we investigated the long-term physiological consequences of sustained LvIns suppression. Surprisingly, prolonged knockdown did not result in progressive growth deterioration or elevated mortality. Instead, shrimp exhibited a notable recovery of growth and metabolic performance, revealing a dynamic adaptive response to chronic endocrine perturbation. Notably, this recovery coincided with robust up-regulation of the gonadulin-type ILP LvGon , another ILP family member. In vivo glucose challenge and exogenous insulin assays, together with in vitro primary hepatopancreas cell experiments, demonstrated that LvGon is rapidly induced by hyperglycemia and suppressed by insulin, placing it within a glucose–insulin regulatory loop. LvGon also exhibited broad tissue distribution similar to LvIns , sharing conserved insulin-like structural features and predicted insulin receptor–binding potential. Transcriptomic analysis further revealed coordinated metabolic reprogramming, including up-regulation of glycolysis, fatty acid oxidation/ketogenesis, and the tricarboxylic acid cycle, as well as activation of growth-associated Wnt and MAPK/ERK pathways. Collectively, these findings support a multilevel compensatory framework, in which ligand-level substitution ( LvGon up-regulation), metabolic remodeling, and growth signaling activation converge to restore growth homeostasis under sustained disruption of insulin-like signaling, providing mechanistic insight into endocrine redundancy and network plasticity in crustaceans.

The lack of robust continuous cell lines remains a major bottleneck limiting cell-level mechanistic dissection of endocrine and metabolic regulation in crustaceans. In this context, experimentally tractable primary cell systems provide a practical and physiologically relevant strategy for interrogating regulatory processes under controlled conditions. Here, we established and functionally validated a primary hepatopancreatic cell platform from the Pacific white shrimp Litopenaeus vannamei for investigating glucose metabolism and endocrine-metabolic regulation. Morphological characterization and systematic optimization of key culture parameters showed that the isolated cell population retained representative features of major hepatopancreatic cell types and could be maintained under short-term culture conditions suitable for functional analyses. Using this system, we showed that primary hepatopancreatic cells rapidly sensed exogenous glucose and initiated a coordinated metabolic response characterized by enhanced glucose transport and glycolysis-related transcription, together with suppression of gluconeogenesis-related genes. Exogenous insulin further amplified intracellular glucose accumulation and reinforced this glucose-utilizing transcriptional program, indicating that the platform preserves hormone-responsive metabolic properties in vitro . Conversely, starvation-mimicking conditions induced a distinct adaptive response, marked by reduced intracellular glucose availability, repression of glycolysis-related genes, and activation of gluconeogenesis-related transcription. Linsitinib treatment substantially blunted glucose responsiveness and shifted the transcriptional profile toward impaired glucose utilization. To extend the applicability of the platform beyond acute in vitro stimulation, in vivo endocrine perturbations were coupled with subsequent in vitro glucose-loading assays. Primary cells derived from insulin-degrading enzyme (IDE)-suppressed shrimp displayed enhanced glucose accumulation, whereas prolonged insulin exposure produced a delayed glucose-response profile, indicating an altered temporal response to glucose loading. In addition, optimized cytochemical staining enabled visualization of glycogen and lipid storage differences under distinct nutritional states, providing complementary phenotypic readouts of cellular energy status. Collectively, this study establishes a controllable and expandable primary hepatopancreatic cell platform for dissecting nutrient sensing, glucose metabolic homeostasis, and endocrine-metabolic regulation in L. vannamei . This system provides a valuable cellular tool for crustacean endocrinology and metabolism research and offers a useful framework for future functional studies in economically important crustacean species.