PURPOSE: Aspartate β-hydroxylase (ASPH) contributes to carcinogenesis by promoting tumor cell proliferation, migration, and invasion. The enzymatic activity of ASPH can be inhibited by small molecule inhibitors that have been shown to have anti-metastatic activity in rodent models. ASPH has also been shown to inhibit the activation of natural killer (NK) cells. Therefore, this study aimed to investigate the effect of ASPH inhibition on the induction of anti-tumor immunity and to analyze the immune cells involved. METHODS: In the mouse TC-1/A9 model characterized by reversible downregulation of major histocompatibility class I (MHC-I) molecules, ASPH inhibition was combined with stimulation of innate and/or adaptive immunity, and the anti-tumor response was analyzed by evaluation of tumor growth, in vivo depletion of immune cell subpopulations, and ELISPOT assay. Characteristics of immune cells in the spleen and tumor were determined by flow cytometry and single-cell RNA sequencing (scRNA-seq). RESULTS: ASPH inhibition did not reduce tumor growth or promote the anti-tumor effect of innate immunity stimulation with the synthetic oligonucleotide ODN1826, but it significantly enhanced tumor growth reduction induced by DNA vaccination. In vivo immune cell depletion suggested that CD8+ T cells played a critical role in this immunity stimulated by combined treatment with ASPH inhibition and DNA vaccination. ASPH inhibition also significantly enhanced the specific response of CD8+ T cells induced by DNA vaccination in splenocytes, as detected by ELISPOT assay, and reduced the number of regulatory T cells in tumors. scRNA-seq confirmed the improved activation of CD8+ T cells in tumor-infiltrating cells after combined therapy with DNA vaccination and ASPH inhibition. It also showed activation of NK cells, macrophages, and dendritic cells in tumors. CONCLUSION: ASPH inhibition stimulated T-cell-mediated adaptive immunity induced by DNA vaccination. Different types of lymphoid and myeloid cells were likely involved in the activated immune response that was efficient against tumors with MHC-I downregulation, which are often resistant to T-cell-based therapies. Due to different types of activated immune cells, ASPH inhibition could improve immunotherapy for tumors with various MHC-I expression levels.

• Keywords
• ASPH, adaptive immunity, cancer immunotherapy, scRNA-seq, tumor microenvironment,
• Publication type
• Journal Article MeSH

BACKGROUND: A proportion of head and neck carcinomas (HNSCCs) are induced by high-risk human papillomaviruses (HPVs) and are associated with better patient outcomes compared to patients with HNSCCs related to tobacco and alcohol abuse. In the microenvironment of solid tumors, including HNSCCs, oxygen levels are often reduced, and a hypoxic state is induced. This can lead to a poor treatment response and a worse patient prognosis. One of the hypoxia-responsive genes is aspartate-β-hydroxylase (ASPH), whose activity promotes the growth, invasiveness, and metastasis of many types of solid tumors. METHODS: In our study, HNSCC samples were analyzed for the expression of ASPH and selected endogenous hypoxia markers by real-time PCR and/or multiplex fluorescence immunohistochemistry. RESULTS: Except for the EPAS1 gene, which had higher mRNA expression in the HPV-negative group of HNSCC (p < 0.05), we found no other differences in the expression of the tested genes that were related to HPV status. On the contrary, a statistically significantly higher number of cells producing ASPH (p < 0.0001), HIF1A (p < 0.0001), GLUT1 (p < 0.0001), and MMP13 (p < 0.05) proteins were detected in the HPV-positive tumor group than in the HPV-negative sample group. All the evaluated markers, except for MMP9/13, were more abundant in the tumor parenchyma than in the tumor stroma. The Cox proportional hazard models showed that increased numbers of cells with GLUT1 and HIF1A protein expression were positive prognostic markers for overall and disease-specific survival in patients independent of HPV tumor status. CONCLUSION: The study examined HNSCC samples and found that elevated ASPH and hypoxia marker proteins, typically associated with poor prognosis, may actually indicate active HPV infection, the strongest prognostic factor in HNSCC patients. In cases where HPV status is uncertain, increased expression of HIF1A and GLUT1 can serve as positive prognostic factors.

• Keywords
• Aspartate-β-hydroxylase, Head and neck cancer, Human papillomavirus, Hypoxia, Prognosis,
• Publication type
• Journal Article MeSH

Background: Cancer development involves alterations in key cellular pathways, with aspartate β-hydroxylase (ASPH) emerging as an important player in tumorigenesis. ASPH is upregulated in various cancer types, where it promotes cancer progression mainly by regulating the Notch1 and SRC pathways. Methods: This study explored the responses of various human cervical, pharyngeal, and breast tumor cell lines to second- and third-generation ASPH inhibitors (MO-I-1151 and MO-I-1182) using proliferation, migration, and invasion assays; western blotting; and cell cycle analysis. Results: ASPH inhibition significantly reduced cell proliferation, migration, and invasion and disrupted both the canonical and noncanonical Notch1 pathways. The noncanonical pathway was particularly mediated by AKT signaling. Cell cycle analysis revealed a marked reduction in cyclin D1 expression, further confirming the inhibitory effect of ASPH inhibitors on cell proliferation. Additional analysis revealed G0/G1 arrest and restricted progression into S phase, highlighting the regulatory impact of ASPH inhibitors on the cell cycle. Furthermore, ASPH inhibition induced distinctive alterations in nuclear morphology. The high heterogeneity in the responses of individual tumor cell lines to ASPH inhibitors, both quantitatively and qualitatively, underscores the complex network of mechanisms that are regulated by ASPH and influence the efficacy of ASPH inhibition. The effects of ASPH inhibitors on Notch1 pathway activity, cyclin D1 expression, and nuclear morphology contribute to the understanding of the multifaceted effects of these inhibitors on cancer cell behavior. Conclusion: This study not only suggests that ASPH inhibitors are effective against tumor cell progression, in part through the induction of cell cycle arrest, but also highlights the diverse and heterogeneous effects of these inhibitors on the behavior of tumor cells of different origins.

• Keywords
• AKT signaling, ASPH inhibitors, Notch pathway, cell cycle, heterogeneity, tumorigenesis,
• Publication type
• Journal Article MeSH

Background: Overexpression of aspartate β-hydroxylase (ASPH) in human tumors contributes to their progression by stimulating cell proliferation, migration, and invasion. Several signaling pathways affected by ASPH have been identified, but the high number of potential targets of ASPH hydroxylation suggests that additional mechanisms may be involved. This study was performed to reveal new targets of ASPH signaling. Methods: The effect of ASPH on the oncogenicity of three mouse tumor cell lines was tested using proliferation assays, transwell assays, and spheroid invasion assays after inhibition of ASPH with the small molecule inhibitor MO-I-1151. ASPH was also deactivated with the CRISPR/Cas9 system. A transcriptomic analysis was then performed with bulk RNA sequencing and differential gene expression was evaluated. Expression data were verified by quantitative PCR and immunoblotting. Results: Inhibition or abrogation of ASPH reduced proliferation of the cell lines and their migration and invasiveness. Among the genes with differential expression in more than one cell line, two members of the lymphocyte antigen 6 (Ly6) family, Ly6a and Ly6c1, were found. Their downregulation was confirmed at the protein level by immunoblotting, which also showed their reduction after ASPH inhibition in other mouse cell lines. Reduced production of the Ly6D and Ly6K proteins was shown after ASPH inhibition in human tumor cell lines. Conclusions: Since increased expression of Ly6 genes is associated with the development and progression of both mouse and human tumors, these results suggest a novel mechanism of ASPH oncogenicity and support the utility of ASPH as a target for cancer therapy.

• Keywords
• ASPH inhibitor, Ly6 family, RNA sequencing, Tumorigenesis,
• Publication type
• Journal Article MeSH