Chemoresistance remains a major challenge in the treatment of triple-negative breast cancer (TNBC). However, the mechanisms underlying chemoresistance remain poorly understood. In this study, we identified that higher levels of Rhomboid-Like 2 (RHBDL2) expression were associated with chemoresistance and poor prognosis in patients with TNBC. Notably, the knockdown of RHBDL2 suppressed cancer stemness and chemoresistance by inhibiting CD44+/CD24− breast cancer stem cells (BCSCs) in TNBC cells. RNA sequencing analysis revealed that the EGFR/PI3K/AKT/mTOR/c-MYC signaling pathway was involved in this process. Mechanistically, we observed that RHBDL2 activated the EGFR/PI3K/AKT/mTOR/c-MYC signaling pathway by binding to EGFR. Knockdown of RHBDL2 inhibited the expression of EGFR on the TNBC cell membrane, thereby deactivating the downstream signaling pathway, and ultimately inhibiting TNBC progression and chemoresistance. Remarkably, our in vivo experiments demonstrated that knockdown of RHBDL2 effectively inhibited tumor growth in xenograft tumor models. Collectively, our study uncovers the roles and mechanisms of RHBDL2 in TNBC chemoresistance and proposes targeting RHBDL2 as an innovative therapeutic strategy to overcome chemoresistance in TNBC.
Oxaliplatin-based neoadjuvant chemotherapy (NACT) is increasingly used in locally advanced colorectal cancer (CRC); however, early acquired resistance substantially limits its efficacy. We revealed an enrichment of therapy-induced senescence (TIS)-like phenotypes in short-term oxaliplatin-exposed CRC. Consistently, a similar upregulation of senescence markers was observed in oxaliplatin-resistant CRC cells. Senolytic treatment attenuated senescence features and restored oxaliplatin sensitivity in vitro and in vivo. Integrative analysis of RNA-sequencing data from resistant tumours and ABT263-treated resistant tumours identified adenosine A1 receptor (ADORA1) as a key mediator of senescence and oxaliplatin resistance. ADORA1 is highly expressed in CRC tumours and is further induced by oxaliplatin, with elevated ADORA1 levels enriched in chemoresistant patients and associated with poor outcomes following chemotherapy. Mechanistically, ADORA1 directly interacts with and stabilises fatty acid synthase (FASN) by suppressing its ubiquitin-mediated degradation, thereby promoting palmitic acid (PA) synthesis, lipid droplet accumulation and p53/p21-driven senescence. Conversely, ADORA1 knockdown attenuates these phenotypes and restores oxaliplatin sensitivity. Together, these findings identify the ADORA1–FASN–PA metabolic reprogramming as a central mechanistic link between TIS and oxaliplatin resistance in CRC, highlighting this pathway as a promising therapeutic target for overcoming early acquired resistance. Early resistance to oxaliplatin-based neoadjuvant chemotherapy (NACT) remains a major obstacle to improving outcomes for patients with locally advanced colorectal cancer (CRC). We found that even brief exposure to oxaliplatin drives therapy-induced senescence (TIS) in CRC tumours. Eliminating these senescent cells reduced oxaliplatin resistance in both resistant CRC cells and xenograft models. By integrating transcriptomic and lipidomic analyses with molecular and functional studies, we identified adenosine A1 receptor (ADORA1) as a key regulator of TIS and oxaliplatin resistance. Mechanistically, ADORA1 stabilises fatty acid synthase (FASN), driving palmitic acid (PA) metabolic reprogramming and sustaining cellular senescence. Reducing ADORA1 expression promoted FASN degradation, alleviated cellular senescence and enhanced the therapeutic efficacy of oxaliplatin. Together, these findings reveal a previously unrecognised mechanism underlying early oxaliplatin resistance and identify the ADORA1–FASN–PA pathway as a promising therapeutic target for improving the efficacy of oxaliplatin-based NACT.
Prostate cancer is a spatially heterogeneous disease in which signaling transitions driving progression remain poorly defined, because bulk molecular analyses obscure compartment-specific pathway alterations. To resolve spatial signaling organization within human tumors, we performed intra-patient, lesion-matched profiling of MRI-targeted biopsies from the same prostate, focusing on Protein Kinase A (PKA). Immunofluorescence across healthy, Grade Group 1, and Grade Group 4 tissues revealed progressive redistribution of PKA subunits: RIβ expression declined with basal layer disruption, whereas PKAC was redistributed to proliferating tumor cells, establishing a grade-dependent imbalance between regulatory and catalytic components. This redistribution was associated with increased phosphorylation of PKA substrates, linking subunit distribution to pathway activation. Quantitative image analysis and biochemical validation of matched suspicious and non-suspicious biopsy cores from 40 patients confirmed coordinated changes in subunit expression and elevated pathway activity. Analysis of independent proteomics datasets comprising over 400 cases further supported dysregulation of catalytic-to-regulatory PKA balance and revealed enrichment of PKA phosphorylation motifs among recurrence-associated proteins. Together, these findings define a spatial transition in PKA regulatory control and support a model in which spatial redistribution of signaling components contributes to pathway activation in heterogeneous tumors.
Chemotherapy remains the backbone of neoadjuvant treatment for triple-negative breast cancer (TNBC), and response to chemotherapy strongly correlates with patient prognosis. However, predicting chemoresistance remains a major clinical challenge. To address this obstacle, we performed serial fine needle aspirations followed by RNA-sequencing on patient-derived xenograft (PDX) models of TNBC that were either chemoresponsive or chemoresistant. We found that these two classes of PDX models exhibited distinct transcriptional trajectories that diverged within one week of chemotherapy initiation, preceding measurable changes in tumor volume. At early time points, chemoresponsive tumors showed activation of apoptotic and cytokine-related pathways, while these changes were absent in chemoresistant models. Notably, cytokine upregulation in chemoresponsive tumors coincided with infiltration of myeloid-derived immune cells into the tumor bed within seven days of chemotherapy, indicating active microenvironment remodeling, even in mice lacking a fully intact immune system. Analysis of paired biopsies from patients with TNBC collected before treatment and within four days of the first chemotherapy dose revealed a consistent pattern: chemoresponsive tumors upregulated inflammatory pathways, whereas chemoresistant tumors showed diminished activation of these pathways. These results underscore the potential clinical value of early on-treatment tumor sampling to detect chemoresistance and guide therapeutic intervention.
Hyperactivation of the mechanistic target of rapamycin (mTOR) complexes, mTORC1 and mTORC2, is common in pancreatic ductal adenocarcinoma (PDAC). However, clinical use of mTOR inhibitors has shown limited efficacy due to rapid adaptive resistance. Using inducible genetically engineered mouse models and matched organoids, we delineated distinct complex-specific adaptations. Loss of mTORC1 delayed tumor progression but induced compensatory PI3K/Akt signalling hyperactivation, while concurrently suppressing inflammatory cancer-associated fibroblasts and desmoplasia through Il-1ra. In contrast, mTORC2 loss impaired de novo sphingolipid synthesis, shifted lipid composition toward saturation, increased the saturated-to-monounsaturated fatty acid ratio, enriched plasma membrane lipid rafts, and amplified interferon-γ signaling. This lipid reprogramming generated a synthetic-lethal dependency on stearoyl-CoA desaturase 1 (Scd1). Pharmacological co-inhibition of mTORC1/2 and Scd1 prevented adaptive PI3K/Akt signalling rebound, remodelled the tumor stroma, enhanced interferon-γ responses, and synergized with anti-PD-1 therapy. These findings establish dual targeting of mTOR signaling and Scd1 as a rational therapeutic strategy for PDAC.
