Serine/arginine-rich splicing factor 3 (SRSF3) regulates mRNA alternative splicing of more than 90% of protein-coding genes, providing an essential source for biological versatility. This study finds that SRSF3 expression is associated with drug resistance and poor prognosis in pancreatic cancer. We also find that SRSF3 regulates ANRIL splicing and m6A modification of ANRIL in pancreatic cancer cells. More importantly, we demonstrate that m6A methylation on lncRNA ANRIL is essential for the splicing. Moreover, our results show that SRSF3 promotes gemcitabine resistance by regulating ANRIL's splicing and ANRIL-208 (one of the ANRIL spliceosomes) can enhance DNA homologous recombination repair (HR) capacity by forming a complex with Ring1b and EZH2. In conclusion, this study establishes a link between SRSF3, m6A modification, lncRNA splicing, and DNA HR in pancreatic cancer and demonstrates that abnormal alternative splicing and m6A modification are closely related to chemotherapy resistance in pancreatic cancer.

Pancreatic ductal adenocarcinoma (PDAC) is a devastating cancer with dismal prognosis due to distant metastasis, even in the early stage. Using RNA sequencing and multiplex immunofluorescence, here we find elevated expression of mixed lineage kinase domain-like pseudo-kinase (MLKL) and enhanced necroptosis pathway in PDAC from early liver metastasis T-stage (T1M1) patients comparing with non-metastatic (T1M0) patients. Mechanistically, MLKL-driven necroptosis recruits macrophages, enhances the tumor CD47 ‘don’t eat me’ signal, and induces macrophage extracellular traps (MET) formation for CXCL8 activation. CXCL8 further initiates epithelial–mesenchymal transition (EMT) and upregulates ICAM-1 expression to promote endothelial adhesion. METs also degrades extracellular matrix, that eventually supports PDAC liver metastasis. Meanwhile, targeting necroptosis and CD47 reduces liver metastasis in vivo. Our study thus reveals that necroptosis facilitates PDAC metastasis by evading immune surveillance, and also suggest that CD47 blockade, combined with MLKL inhibitor GW806742X, may be a promising neoadjuvant immunotherapy for overcoming the T1M1 dilemma and reviving the opportunity for radical surgery.

Current therapeutic strategies for pancreatic ductal adenocarcinoma (PDAC) have limited efficacy in increasing patient survival rates, largely due to ferroptosis resistance and immunosuppression. The aim of this study is to identify molecular mechanisms associated with ferroptosis resistance and immunosuppression in PDAC tumour cells. Circular RNA sequencing (circRNA-seq) was performed on clinical samples to identify potential circRNAs that mediate ferroptosis resistance. C11-BODIPY staining, FerroOrange staining, the glutathione ratio, malondialdehyde quantification, and transmission electron microscopy were employed to assess ferroptosis. RNA pulldown, mass spectrometry, RNA immunoprecipitation, and coimmunoprecipitation assays were conducted to investigate the molecular mechanisms involved. A HuNSG mouse xenograft tumour model was utilized to validate therapeutic agents. A circRNA derived from TRIP12 (cTRIP12) was identified in PDAC samples resistant to ferroptosis. cTRIP12 knockdown increased the sensitivity of PDAC cells to ferroptosis and immunotherapy. Subsequent mechanistic studies revealed that cTRIP12 specifically binds to the O-linked N-acetylglucosamine transferase (OGT) protein and increases intracellular O-GlcNAcylation levels, leading to increased protein levels of ferritin heavy chain (FTH) and PD-L1 in tumour cells. Notably, high cTRIP12 expression suppressed ferroptosis sensitivity and increased immune resistance in PDAC cells by functioning as a protein scaffold through its interaction with OGT and protein kinase R-like endoplasmic reticulum kinase (PERK). cTRIP12 inhibition induced ferroptosis in PDAC cells by reducing FTH and PD-L1 expression and synergistically increased the immunotherapy efficacy. In vivo animal experiments confirmed that the triple therapy consisting of GSK2656157, erastin, and anti-CTLA-4 effectively suppressed the progression of PDAC in tumours with high cTRIP12 expression. We elucidated the molecular mechanisms underlying the simultaneous occurrence of ferroptosis resistance and immune suppression in PDAC patients. Our study provides a novel therapeutic strategy that could promote ferroptosis in tumour cells and increase immunotherapy efficacy.

Intrahepatic cholangiocarcinoma (ICC) is characterized by its dense fibrotic microenvironment and highly malignant nature, which are associated with chemotherapy resistance and very poor prognosis. Although circRNAs have emerged as important regulators in cancer biology, their role in ICC remains largely unclear. Herein, a circular RNA, cPKM is identified, which is upregulated in ICC and associated with poor prognosis. Silencing cPKM in ICC cells reduces TGFB1 release and stromal fibrosis, inhibits STMN1 expression, and suppresses ICC growth and metastasis, moreover, it also leads to overcoming paclitaxel resistance. This is regulated by the interactions of cPKM with miR‐199a‐5p or IGF2BP2 and by the ability of cPKM to stabilize STMN1/TGFB1 mRNA. Based on these findings, a Trojan horse nanotherapy strategy with co‐loading of siRNA against cPKM (si‐cPKM) and paclitaxel (PTX) is developed. The siRNA/PTX co‐loaded nanosystem (Trojan horse) efficiently penetrates tumor tissues, releases si‐cPKM and paclitaxel (soldiers), promotes paclitaxel sensitization, and suppresses ICC proliferation and metastasis in vivo. Furthermore, it alleviates the fibrosis of ICC tumor stroma and reopens collapsed tumor vessels (opening the gates), thus enhancing the efficacy of the standard chemotherapy regimen (main force). This novel nanotherapy provides a promising new strategy for ICC treatment.

Patients with concurrent intrahepatic cholangiocarcinoma (ICC) and hepatolithiasis generally have poor prognoses. Hepatolithiasis is once considered the primary cause of ICC, although recent insights indicate that bacteria in the occurrence of hepatolithiasis can promote the progression of ICC. By constructing in vitro and in vivo ICC models and patient‐derived organoids (PDOs), it is shown that Escherichia coli induces the production of a novel RNA, circGLIS3 (cGLIS3), which promotes tumor growth. cGLIS3 binds to hnRNPA1 and G3BP1, resulting in the assembly of stress granules (SGs) and suppression of hnRNPA1 and G3BP1 ubiquitination. Consequently, the IKKα mRNA is blocked in SGs, decreasing the production of IKKα and activating the NF‐κB pathway, which finally results in chemoresistance and produces metastatic phenotypes of ICC. This study shows that a combination of Icaritin (ICA) and gemcitabine plus cisplatin (GP) chemotherapy can be a promising treatment strategy for ICC.

Cuproptosis, a newly identified form of cell death, is closely linked to copper homeostasis and protein lipoylation. Using a multi-omics approach, we firstly reveal that SERPINB3 confers cuproptosis resistance in pancreatic cancer and functions as a theranostic biomarker. Mechanistically, SERPINB3 inhibits FDX1 transcription by activating the MAPK signaling pathway, thereby conferring cuproptosis resistance. We further demonstrated that SERPINB3 directly interacts with MEK1, impeding its chaperone-mediated autophagic degradation, which ultimately leads to sustained activation of the MAPK signaling pathway. Additionally, we found that SERPINB3 promotes pancreatic cancer immune evasion by upregulating PD-L1 expression on tumor cells. This phenomenon motivated the development of a triple-combination strategy consisting of MAPK inhibition, cuproptosis induction, and αPD-1 therapy for pancreatic cancer patients with high SERPINB3 expression. To this end, we further developed a metal-organic framework (MOF) loaded with both copper ions and MEK inhibitor, which significantly triggers tumor-specific cuproptosis and enhances antitumor immunity. In summary, SERPINB3 serves as a predictive biomarker to inform therapeutic strategies targeting cuproptosis, thereby establishing a novel paradigm for cancer immunotherapy that integrates metal biology, targeted therapy, and immune modulation.