Zhi Li

Nasopharyngeal carcinoma (NPC) is a type of cancer that is prevalent in southern China. In the development of NPC, the oncogenic protein LMP1, which is encoded by EBV, plays a very important role. The Wnt pathway is abnormally activated in many types of malignant tumors. The interaction between AXIN and DVL2 is pivotal for the breakdown of the β‐catenin destruction complex and Wnt/β‐catenin pathway activation. However, the molecular mechanisms underlying this process in NPC are not well understood. In this study, we identified the transmembrane protein LMP1 as an interacting partner of DVL2, which positively regulates the Wnt/β‐catenin pathway by inhibiting the AXIN‐DVL2 interaction. LMP1 overexpression enhanced NPC cell growth, metastasis, and stemness, whereas LMP1 knockdown suppressed these abilities. Our findings reveal new oncogenic roles for LMP1 in NPC progression.

Background: Inflammatory breast cancer (IBC), of which HER2 + is the predominant subtype, is extremely aggressive and difficult to treat. Previous studies have suggested that targeting the tumour microenvironment (TME) may provide new directions for IBC diagnosis and treatment. Methods: In this study, we used single-cell transcriptome technology (scRNA-seq) to investigate the molecular features of the TME of HER2 + IBC patients and performed a comprehensive and detailed comparison of the cellular components and molecular phenotypes of the TME between IBC patients and noninflammatory breast cancer (nIBC) patients to elucidate the cell types that are specifically enriched in the TME of IBC patients, as well as the molecular features that are responsible for the preferential remodelling of the cellular functional state in the TME. Results: A total of 15,832 cells, including epithelial cells, endothelial cells, stromal cells, T cells, B cells, antibody secreting cells (ASCs) and myeloid cells, were obtained from tumour tissues from 3 HER2 + IBC patients for scRNA analysis. By comparing the TME with that of HER2 + nIBC patients in a public database, we found that the TME of HER2 + IBC patients had a greater level of lymphocyte infiltration than that of nIBC patients did, and an especially significant enrichment of ASCs (mainly plasmablasts or plasma cells). In the TME of HER2 + IBC patients, tumour-infiltrating T cells exhibited a dual molecular phenotype of high activation and high exhaustion, with tumour-infiltrating B cells preferring the extrafollicular developmental pathway, and tumour-infiltrating myeloid and mesenchymal cells exhibiting a greater immunosuppressive status. By performing a cellular interaction analysis, we revealed that PTN molecules were significantly overexpressed in HER2 + IBC tumour cells and that the cellular interactions mediated by these molecules were strongly correlated with the functional polarisation of the cellular components in the TME. We observed that HER2 + IBC tumour cells have an active interferon response and epithelial mesenchymal transition (EMT) signalling, and that their malignant process is strongly correlated with the inflammatory response. Moreover, we found that HER2 + IBC tumour-infiltrating B cells promoted necroptosis of endothelial cells through high expression of TNF, thus promoting inflammatory responses. Conclusion: We found a strong correlation between high expression of PTN molecules in HER2 + IBC tumour cells and their highly invasive characteristics and highly immunosuppressive TME. These results suggest that HER2 + IBC tumour cells can promote an inflammatory response by upregulating the expression of TNF molecules in B cells via PTN molecules and that the enhanced inflammatory response in turn promotes tumour progression, a malignant cycle that shapes a more immunosuppressive TME. Therefore, diagnostic and therapeutic strategies targeting the PTN-TNF molecular axis may have considerable potential for development in HER2 + IBC patients.

Tumor cells display profound changes in the metabolism of branched-chain amino acids (BCAA). However, how these changes are regulated to facilitate tumorigenesis is not yet completely understood. Here, we identified pancreatic progenitor cell differentiation and proliferation factor (PPDPF) as a BCAA-responsive protein through extensive screening using stable isotope labeling with amino acids in cell culture (SILAC). PPDPF is upregulated in cholangiocarcinoma to enhance the malignant phenotype of cholangiocarcinoma cells by activating the mTORC1 signaling pathway. Metabolic flux analysis and mechanistic studies revealed that PPDPF prevented the interaction between MCCA and MCCB, thus inhibiting leucine catabolism and activating mTORC1 signaling. Moreover, upon amino acid starvation, ariadne RBR E3 ubiquitin protein ligase 2 (ARIH2) and OTU deubiquitinase 4 (OTUD4) cooperatively regulated the stability of the PPDPF protein by modulating its ubiquitination. Additionally, monocytes/macrophage-derived IL-10 increased the BCAA content in cholangiocarcinoma cells and stabilized the PPDPF protein, even under amino acid starvation conditions. Knockout of PPDPF or restriction of leucine intake significantly inhibits the progression of cholangiocarcinoma in a mouse model. Collectively, we discovered a novel role for PPDPF in promoting the progression of cholangiocarcinoma by activating mTORC1 signaling through the inhibition of leucine catabolism. The present study suggests that targeting PPDPF or decreasing dietary leucine intake may provide a new strategy to improve the treatment efficacy of cholangiocarcinoma.

Temozolomide (TMZ) represents a standard-of-care chemotherapeutic agent in glioblastoma (GBM). However, the development of drug resistance constitutes a significant hurdle in the treatment of malignant glioma. Although specific innovative approaches, such as immunotherapy, have shown favorable clinical outcomes, the inherent invasiveness of most gliomas continues to make them challenging to treat. Consequently, there is an urgent need to identify effective therapeutic targets for gliomas to overcome chemoresistance and facilitate drug development. This investigation used mass spectrometry to examine the proteomic profiles of six pairs of GBM patients who underwent standard-of-care treatment and surgery for both primary and recurrent tumors. A total of 648 proteins exhibiting significant differential expression were identified. Gene Set Enrichment Analysis (GSEA) unveiled notable alterations in pathways related to METABOLISM_OF_LIPIDS and BIOLOGICAL_OXIDATIONS between the primary and recurrent groups. Validation through glioma tissue arrays and the Xiangya cohort confirmed substantial upregulation of inositol 1,4,5-triphosphate (IP3) kinase B (ITPKB) in the recurrence group, correlating with poor survival in glioma patients. In TMZ-resistant cells, the depletion of ITPKB led to an increase in reactive oxygen species (ROS) related to NADPH oxidase (NOX) activity and restored cell sensitivity to TMZ. Mechanistically, the decreased phosphorylation of the E3 ligase Trim25 at the S100 position in recurrent GBM samples accounted for the weakened ITPKB ubiquitination. This, in turn, elevated ITPKB stability and impaired ROS production. Furthermore, ITPKB depletion or the ITPKB inhibitor GNF362 effectively overcome TMZ chemoresistance in a glioma xenograft mouse model. These findings reveal a novel mechanism underlying TMZ resistance and propose ITPKB as a promising therapeutic target for TMZ-resistant GBM.

Inflammation plays an important role in the initiation and progression of colorectal cancer (CRC) and leads to β-catenin accumulation in colitis-related CRC. However, the mechanism remains largely unknown. Here, pancreatic progenitor cell differentiation and proliferation factor (PPDPF) is found to be upregulated in CRC and significantly correlated with tumor-node-metastasis (TNM) stages and survival time. Knockout of PPDPF in the intestinal epithelium shortens crypts, decreases the number of stem cells, and inhibits the growth of organoids and the occurrence of azoxymethane (AOM)/dextran sodium sulfate (DSS)-induced CRC. Mechanistically, PPDPF is found to interact with Casein kinase 1α (CK1α), thereby disrupting its binding to Axin, disassociating the β-catenin destruction complex, decreasing the phosphorylation of β-catenin, and activating the Wnt/β-catenin pathway. Furthermore, interleukin 6 (IL6)/Janus kinase 2 (JAK2)-mediated inflammatory signals lead to phosphorylation of PPDPF at Tyr16 and Tyr17, stabilizing the protein. In summary, this study demonstrates that PPDPF is a key molecule in CRC carcinogenesis and progression that connects inflammatory signals to the Wnt/β-catenin signaling pathway, providing a potential novel therapeutic target.

Pancreatic ductal adenocarcinoma (PDAC) is a highly heterogeneous malignancy. Single-cell sequencing (scRNA-seq) technology enables quantitative gene expression measurements that underlie the phenotypic diversity of cells within a tumor. By integrating PDAC scRNA-seq and bulk sequencing data, we aim to extract relevant biological insights into the ductal cell features that lead to different prognoses. Firstly, differentially expressed genes (DEGs) of ductal cells between normal and tumor tissues were identified through scRNA-seq data analysis. The effect of DEGs on PDAC survival was then assessed in the bulk sequencing data. Based on these DEGs (LY6D, EPS8, DDIT4, TNFSF10, RBP4, NPY1R, MYADM, SLC12A2, SPCS3, NBPF15) affecting PDAC survival, a risk score model was developed to classify patients into high-risk and low-risk groups. The results showed that the overall survival was significantly longer in the low-risk group (p < 0.05). The model also revealed reliable predictive power in different subgroups of patients. The high-risk group had a higher tumor mutational burden (TMB) (p < 0.05), with significantly higher mutation frequencies in KRAS and ADAMTS12 (p < 0.05). Meanwhile, the high-risk group had a higher tumor stemness score (p < 0.05). However, there was no significant difference in the immune cell infiltration scores between the two groups. Lastly, drug candidates targeting risk model genes were identified, and seven compounds might act against PDAC through different mechanisms. In conclusion, we have developed a validated survival assessment model, which acted as an independent risk factor for PDAC.

Pancreatic cancer is a highly malignant tumour of the digestive tract which is difficult to diagnose and treat. Approximately 90% of cases arise from ductal adenocarcinoma of the glandular epithelium. The morbidity and mortality of the disease have increased significantly in recent years. Its 5‐year survival rate is <1% and has one of the worst prognoses amongst malignant tumours. Pancreatic cancer has a low rate of early‐stage diagnosis, high surgical mortality and low cure rate. Selenium compounds produced by selenoamino acid metabolism may promote a large amount of oxidative stress and subsequent unfolded reactions and endoplasmic reticulum stress by consuming the NADPH in cells, and eventually lead to apoptosis, necrosis or necrotic cell death. In this study, we first identified DIAPH3 as a highly expressed protein in the tissues of patients with pancreatic cancer, and confirmed that DIAPH3 promoted the proliferation, anchorage‐independent growth and invasion of pancreatic cancer cells using overexpression and interference experiments. Secondly, bioinformatics data mining showed that the potential proteins interacted with DIAPH3 were involved in selenoamino acid metabolism regulation. Selenium may be incorporated into selenoprotein synthesis such as TrxR1 and GPX4, which direct reduction of hydroperoxides or resist ferroptosis, respectively. Our following validation confirmed that DIAPH3 promoted selenium content and interacted with the selenoprotein RPL6, a ribosome protein subunit involved in selenoamino acid metabolism. In addition, we verified that DIAPH3 could down‐regulate cellular ROS level via up‐regulating TrxR1 expression. Finally, nude mice xenograft model experimental results demonstrate DIAPH3 knock down could decrease tumour growth and TrxR1 expression and ROS levels in vivo. Collectively, our observations indicate DIAPH3 could promote pancreatic cancer progression by activating selenoprotein TrxR1‐mediated antioxidant effects.