Objective: To characterize alpha‐fetoprotein (AFP)‐producing gastric cancer (AFPGC) at the single‐cell level and to identify regulatory factors for AFP expression and malignancy.Methods: ScRNA‐seq was performed on two tumors collected from patients with AFPGC. InferCNV and sub‐clustering were applied to identify typical AFPGC cells, followed by AddModuleScore, pathway enrichment, Pseudo‐time, and Scenic analyses. Data from a gastric cancer (GC) cohort were collected for conjoint analysis. The analytical results were verified by cell experiments and immunohistochemistry.Results: AFPGC cells are similar to hepatocytes in transcriptome and transcriptional regulation, with kinetic malignancy‐related pathways, compared to the common malignant epithelium. In addition, compared to common GC cells, malignancy‐related pathways, such as epithelial‐mesenchymal transition (EMT) and angiogenesis, were upregulated in AFPGC. Mechanistically, Dickkopf‐1 (DKK1) was found to be associated with AFP expression and malignant phenotype upon combining our scRNA‐seq data with a public database, which was further verified by a series of in vitro experiments and immunohistochemistry.Conclusion: We demonstrated the single‐cell characteristics of AFPGC and that DKK1 facilitates AFP expression and malignancy.

Background: Basal-like breast cancer (BLBC) is the most aggressive subtype of breast cancer because of its aggressive biological characteristics and no effective targeted agents. However, the mechanism underlying its aggressive behavior remain poorly understood. β1,3-N-acetylglucosaminyltransferase V (B3GNT5) overexpression occurs specifically in BLBC. Here, we studied the possible molecular mechanisms of B3GBT5 promoting the aggressiveness of BLBC. Methods: The potential effects of B3GNT5 on breast cancer cells were tested by colony formation, mammosphere formation, cell proliferation assay, flow cytometry and Western blotting. The glycosylation patterns of B3GNT5 and associated functions were determined by Western blotting, quantitative real-time PCR and flow cytometry. The effect of B3GNT5 expression on BLBC was assessed by in vitro and in vivo tumorigenesis model. Results: In this study, we showed that B3GNT5 copy number amplification and hypomethylation of B3GNT5 promoter contributed to the overexpression of B3GNT5 in BLBC. Knockout of B3GNT5 strongly reduced surface expression of SSEA-1 and impeded cancer stem cell (CSC)-like properties of BLBC cells. Our results also showed that B3GNT5 protein was heavily N-glycosylated, which is critical for its protein stabilization. Clinically, elevated expression of B3GNT5 was correlated with high grade, large tumor size and poor survival, indicating poor prognosis of breast cancer patients. Conclusions: Our work uncovers the critical association of B3GNT5 overexpression and glycosylation with enhanced CSCs properties in BLBC. These findings suggest that B3GNT5 has the potential to become a prognostic marker and therapeutic target for BLBC.

Alpha-fetoprotein (AFP)-producing adenocarcinoma from the gastrointestinal tract (APA-GI) is a rare type of highly malignant tumor with a poor prognosis. It may originate from any site along the GI tract with similar clinicopathological characteristics. As limited research had ever described the characteristics of APA-GI, the present article intends to systemically investigate the clinicopathological characteristics of APA-GI from a single center's retrospective study to deepen the understanding of the disease. A total of 177 patients pathologically diagnosed with APA-GI between 2010 and 2017 at the Second Affiliated Hospital of Zhejiang University, School of Medicine, were included. Also, clinical data of 419 gastric cancers and 609 colorectal cancers from The Cancer Genome Atlas database were also extracted. Clinical information of patients from Second Affiliated Hospital of Zhejiang University, School of Medicine, was collected, and a median follow-up of 14.5 months was performed to investigate clinical characteristics of APA-GI. For the pathological characteristics of APA-GI, hematoxylin–eosin sections were reviewed, and immunohistochemistry of AFP was performed. The results showed that the primary tumor could develop through the whole GI tract, including the esophagus (0.6%), stomach (83.1%), duodenum (1.1%), ileum (0.6%), appendix (0.6%), colon (5.1%), and rectum (7.9%). Hepatoid adenocarcinoma is the main pathological feature of APA-GI. AFP expression level in tumor tissue was not strictly associated with serum AFP or hepatoid differentiation. The prognosis of APA-GI was worse than that of common adenocarcinoma of the GI tract and liver metastasis, and high AFP levels suggest poor prognosis in patients with APA-GI. Therefore, the present study was the first research to systemically explore the clinicopathological characteristics of APA-GI. APA-GI occurs through the whole GI tract with a significantly worse prognosis than common adenocarcinoma of GI. APA-GI should be regarded as one kind of disease for its similar clinicopathological characteristics within patients.

Background: Basal-like breast cancer (BLBC) is associated with a poor clinical outcome; however, the mechanism of BLBC aggressiveness is still unclear. It has been shown that a linker histone functions as either a positive or negative regulator of gene expression in tumors. Here, we aimed to investigate the possible involvement and mechanism of HIST1H1B in BLBC progression. Experimental design: We analyzed multiple gene expression datasets to determine the relevance of HIST1H1B expression with BLBC. We employed quantitative real-time PCR, transwell assay, colony formation assay, and mammosphere assay to dissect the molecular events associated with the expression of HIST1H1B in human breast cancer. We studied the association of HIST1H1B with CSF2 by ChIP assay. Using tumorigenesis assays, we determine the effect of HIST1H1B expression on tumorigenicity of BLBC cells. Results: Here, we show that the linker histone HIST1H1B is dramatically elevated in BLBC due to HIST1H1B copy number amplification and promoter hypomethylation. HIST1H1B upregulates colony-stimulating factor 2 (CSF2) expression by binding the CSF2 promoter. HIST1H1B expression promotes, whereas knockdown of HIST1H1B expression suppresses tumorigenicity. In breast cancer patients, HIST1H1B expression is positively correlated with large tumor size, high grade, metastasis and poor survival. Conclusion: HIST1H1B contributes to basal-like breast cancer progression by modulating CSF2 expression, indicating a potential prognostic marker and therapeutic target for this disease.