Background Doxorubicin (DOX) resistance remains a major obstacle to favorable outcomes in osteosarcoma. The role of RASGRP2 in osteosarcoma chemoresistance is poorly understood. Methods We analyzed RASGRP2 expression and prognostic value across pan-cancer datasets (TCGA, TARGET) and osteosarcoma cohorts (TARGET-OS, GSE21257, GSE126209). CCK-8, colony formation, wound healing, Transwell, and Western blot assays were employed to evaluate how RASGRP2 knockdown affects osteosarcoma cell proliferation, migration, invasion, and DOX sensitivity. We further established a tibial orthotopic xenograft model to assess the in vivo efficacy of combining RASGRP2 silencing with DOX. Immunohistochemistry was conducted on 53 clinical osteosarcoma samples to validate protein-level associations. Results RASGRP2 was upregulated in multiple malignancies and osteosarcoma, correlating with advanced Huvos grade, metastasis, poor chemotherapy response, and unfavorable survival. Bioinformatic analyses revealed Notch and Wnt signaling enrichment in high-RASGRP2 tumors. DOX induced RASGRP2 upregulation in a dose- and time-dependent fashion. RASGRP2 knockdown suppressed proliferation, migration, and invasion, and enhanced DOX sensitivity in both cellular and animal models. Mechanistically, RASGRP2 promoted DOX resistance via the Notch1-NICD-Hes1 axis, as evidenced by knockdown and VPA-based rescue experiments and further confirmed by functional rescue with the specific Notch ligand Jagged-1. In the orthotopic model, RASGRP2 silencing reduced tumor burden, enhanced DOX efficacy, and reduced CD206-positive cell infiltration. In clinical samples, elevated RASGRP2 protein correlated with higher metastatic incidence (p = 0.003), reduced overall and progression-free survival (p < 0.0001 for both), and unfavorable chemotherapy response. Conclusion RASGRP2 is associated with DOX resistance and osteosarcoma progression through the Notch1-NICD-Hes1 signaling axis and represents a potential prognostic biomarker. Targeting RASGRP2 may offer a strategy to overcome chemoresistance in osteosarcoma.
Recent studies have shown that G protein-coupled P2Y6 receptor (P2Y6R) can play a promoting or inhibitory role in some tumors, but the functional effect of P2Y6R on the migration and invasion of colorectal cancer (CRC) is still poorly understood. Therefore, this study comprehensively investigated whether the P2Y6R plays a promoting or inhibiting role in the migration and invasion of CRC. Public databases were used to investigate the intrinsic association between P2Y6R and CRC tissue. Functional experiments was used to investigate the effects of P2Y6R activation or inhibition on CRC migration, invasion, cytoskeleton and glycogen accumulation. The results showed that high expression of P2Y6R was negatively correlated with overall survival and prognosis of CRC patients. The P2Y6R agonist (UDP) opened the function of the pore on the cell membrane and increased the influx of calcium ions, while antagonistic to its activation could produce a significant inhibitory effect. UDP promoted the migration and invasion capabilities of CRC cells, enhanced the fibrin stress capabilities of the cytoskeleton, and promoted the glycogen accumulation capabilities of cells. However, the P2Y6R antagonist MRS2578 or MRS4853 significantly inhibited these changes induced by UDP. Moreover, the P2Y6R had a clear correlation with AKT/mTOR in patients with CRC tissues. UDP increased the protein expression levels of p-AKT and p-mTOR in CRC cells, while P2Y6R antagonists decreased the protein expression levels of p-AKT and p-mTOR by inhibiting P2Y6R activity. In addition, based on P2Y6R activation, the application of AKT/mTOR pathway inhibitor BGT226 inhibited UDP-induced migration, invasion, cytoskeleton and glycogen accumulation of CRC cells. Combined intervention of P2Y6R antagonists and BGT226 produced additive inhibitory pharmacological effects. These data reveal that high expression of P2Y6R contributes to poor overall survival outcomes in patients with CRC. Activation of P2Y6R promotes the migration, invasion and glycogen accumulation of CRC cells, and the mechanism may be related to the AKT/mTOR pathway. This also reveals that the P2Y6R can be used as another important target for the prevention and treatment of CRC.
Cephalomannine (CPM), a naturally occurring taxane isolated from Taxus wallichiana, exhibits broad antitumor activity against multiple solid malignancies. However, the molecular targets responsible for this anticancer activity remain poorly defined. Here, we used an integrated chemical–genomic and functional framework to elucidate the molecular basis of CPM action in triple-negative breast cancer (TNBC). High-throughput perturbational transcriptomic profiling, computational target prediction, structural molecular modeling, and biophysical validation have converged to identify vascular endothelial growth factor receptor 1 (VEGFR1) as a key molecular determinants of CPM. Functional analysis showed that CPM potently suppressed TNBC cell proliferation and migration at nanomolar concentrations and significantly inhibited tumor growth and metastatic dissemination in orthotopic xenograft models. Mechanistically, CPM selectively attenuated VEGFR1-dependent Src/β-catenin signaling and epithelial–mesenchymal transition (EMT) programs without altering the total receptor abundance, consistent with a non-canonical, phosphorylation-dependent mode of action. Collectively, these findings establish a previously unrecognized mechanism by which CPM exerts its antitumor and anti-metastatic effects in TNBC, expand the current understanding of taxane pharmacology, and provide a rational foundation for the development of VEGFR1-targeted CPM-based therapeutic strategies for aggressive treatment-refractory breast cancers.
