Jun-Li Luo

The FXYD family (FXYD domain-containing ion transport regulators) proteins consist of short, single-pass transmembrane proteins that primarily regulate the Na⁺/K⁺-ATPase (NKA) pump, a key player in maintaining cellular ion homeostasis. Ranging from 60 to 160 amino acids in length, FXYD proteins display tissue-specific expression patterns and influence not only NKA activity but also the function of other ion channels, including potassium, sodium, and chloride channels. These proteins interact with NKA in diverse ways, modulating its activity to meet the specific needs of different tissues. In addition to their physiological roles, FXYD proteins are implicated in the development and progression of various diseases, such as cancer, cardiovascular disorders, renal diseases, and neurological conditions. This review offers an overview of the structures, biological functions, and molecular mechanisms through which FXYD proteins regulate ion transport. Furthermore, we explore their emerging roles in disease pathogenesis and discuss potential therapeutic strategies for targeting FXYD proteins in disease management.

Adeno-associated virus (AAV) unequivocally emerges as one of the most powerful and promising delivery vectors for gene therapy targeting hereditary hearing loss. Following AAV transduction in the inner ear, varying degrees of natural immune responses are triggered, primarily characterized by macrophage activation and the secretion of pro-inflammatory factors. Additionally, the production of neutralizing antibodies may affect the efficacy of gene therapy. To evaluate immune dynamics, we injected AAV1 and AAV-ie (capsids with distinct transfection efficiencies) into murine cochleae and analyzed temporal transcriptomic profiles. Our results demonstrate that both capsids induce immune activity but with critical temporal and intensity differences that AAV1 elicits significantly later and milder immune reactions compared to AAV-ie. These findings establish that dynamic cochlear gene expression profiles directly inform the selection of immunologically optimized AAV vectors to minimize adverse responses in future hereditary hearing loss gene therapies.

Background: The urea cycle and pyrimidine synthesis occur mainly in the liver and undergo opposite changes during hepatocarcinogenesis. Argininosuccinate synthase 1 (ASS1) and carbamoyl-phosphate synthetase 2, aspartate transcarbamylase, and dihydroorotase (CAD) are key enzymes in the urea cycle and pyrimidine synthesis, respectively, and compete for the common substrate, aspartate. Moreover, ASS1 is lowly expressed in certain cancers, while CAD is highly expressed. However, the role of ASS1 and CAD in liver cancer still remains unclear. Methods: ASS1 and CAD expression in liver cancer were detected by tissue microarrays. Overexpression of ASS1 and CAD was achieved via lentivirus methods. All in vitro experiments were conducted in cells. The interactions of ASS1 and CAD were detected by co-immunoprecipitation (Co-IP) and GST-pull down. The in vivo study was conducted in a BALB/c nude mouse model. Intracellular metabolites were detected by LC–MS/MS. Results: ASS1 was lowly expressed in liver cancer, while CAD was highly expressed. In patients with recurrent liver cancer, ASS1 and CAD were significantly negatively correlated. Moreover, liver cancer patients with low ASS1 expression and high CAD expression had a poor prognosis. ASS1 and CAD interacted directly and promoted CAD ubiquitination through STUB1. In addition, Overexpression of CAD attenuated the tumor-suppressive effect of ASS1 in liver cancer cells. Pyrimidine supplementation enhanced the growth of liver cancer cells with ASS1 overexpression. Conclusions: ASS1 deficiency causes an imbalance in the urea cycle and pyrimidine synthesis in liver cancer. ASS1 directly controls the ubiquitination of CAD via STUB1, rather than just competing with aspartate, thereby suppressing liver cancer. Thus, ASS1 has potential as a druggable target in liver cancer.

Glioma, marked by a low mutational burden, low immunogenicity, high heterogeneity, and the challenges posed by the blood–brain barrier, continues to be a major hurdle in neuro‐oncology. Current research underscores the necessity for more effective medications and treatment strategies. In this study, we explored the role of Apolipoprotein E (ApoE) in glioma using both bioinformatics and experimental methods. The construction of our bioinformatics risk model identified ApoE as a protective factor linked to longer survival in glioma patients. Subsequently, we created an in situ tumorigenic mouse model and a subcutaneous tumorigenic mouse model with ApoE gene knockout to evaluate the functional impacts of ApoE deficiency in glioma. Our results demonstrated that ApoE deficiency accelerates the growth of glioma and encourages the invasive behaviour of tumour cells into normal brain tissue. Additionally, we detected a reduction in the immune surveillance of glioma in the context of ApoE deficiency. Furthermore, flow cytometry analysis indicated that the lack of ApoE led to a decrease in positive immune cells and an increase in immunosuppressive cells within the tumour microenvironment. Our findings suggest that ApoE plays a crucial role in modulating glioma progression and immune surveillance, highlighting its potential as a therapeutic target.

Background: Colorectal cancer (CRC) is a prevalent global malignancy with particularly challenging treatment outcomes in advanced stages. Oxaliplatin (OXA) is a frontline chemotherapeutic agent for CRC. However, 15% to 50% of stage III patients experience recurrence due to drug resistance. Elucidating the molecular mechanisms underlying OXA resistance is, therefore, crucial for improving CRC prognosis. The role of DIRAS1, a RAS superfamily member with reported tumor-suppressive functions in various cancers, remains poorly defined in CRC. Methods: The effects of DIRAS1 on CRC cell proliferation and migration were evaluated using MTT, wound healing, and colony formation assays. Stable cell lines with knockdown or overexpression of DIRAS1 and PHB1 were established via plasmid and lentiviral systems. Drug sensitivity to OXA was assessed through cytotoxicity assays and IC₅₀ determination. Clinical relevance was validated through immunohistochemical analysis of CRC tissue samples. Transcriptomic sequencing was performed to explore downstream regulatory mechanisms. Results: DIRAS1 expression was positively correlated with OXA resistance and was significantly upregulated following prolonged chemotherapy exposure. Silencing DIRAS1 reduced the IC₅₀ of OXA in vitro and increased tumor sensitivity to OXA in vivo. Transcriptome analysis identified PHB1 as a downstream effector of DIRAS1. Functional studies revealed that PHB1 contributes to chemoresistance by maintaining mitochondrial stability. Conclusions: This study identifies DIRAS1 as a key contributor to OXA resistance in CRC by modulating PHB1 expression and mitochondrial function. Targeting the DIRAS1–PHB1 axis may offer a novel therapeutic strategy to overcome chemoresistance in CRC.

Prostate cancer is among the most frequently diagnosed and deadly cancers among men in the Western world. It is typically classified as an immune “cold” tumor due to its sparse immune cell presence and limited immunogenic response. Recent research has revealed the significant role of immune cells, especially CD8⁺ T cells, in both prostate cancer progression and treatment efficacy. This review integrates recent findings to provide a comprehensive overview of the current understanding of CD8⁺ T cell dynamics in prostate cancer and discusses emerging strategies to improve treatment outcomes. The ongoing exploration of new molecular targets and the development of innovative immunotherapeutic approaches hold promise for more effective management of prostate cancer, particularly in the context of advanced and resistant forms of the disease.

The cathepsin family comprises lysosomal proteases that play essential roles in various physiological processes, including protein degradation, antigen presentation, apoptosis, and tissue remodeling. Dysregulation of cathepsin activity has been linked to a variety of pathological conditions, such as cancer, autoimmune diseases, and neurodegenerative disorders. Understanding the functions of cathepsins is crucial for gaining insights into their roles in both health and disease, as well as for developing targeted therapeutic approaches. Emerging research underscores the significant involvement of cathepsins in immune cells, particularly T cells, macrophages, dendritic cells, and neutrophils, as well as their contribution to immune-related diseases. In this review, we systematically examine the impact of cathepsins on the immune system and their mechanistic roles in cancer, infectious diseases, autoimmune and neurodegenerative disorders, with the goal of identifying novel therapeutic strategies for these conditions.

Endocrine therapy that blocks estrogen signaling is the most effective treatment for patients with estrogen receptor positive (ER⁺) breast cancer. However, the efficacy of agents such as tamoxifen (Tam) is often compromised by the development of resistance. Here we report that cytokines-activated nuclear IKKα confers Tam resistance to ER⁺ breast cancer by inducing the expression of FAT10, and that the expression of FAT10 and nuclear IKKα in primary ER⁺ human breast cancer was correlated with lymphotoxin β (LTB) expression and significantly associated with relapse and metastasis in patients treated with adjuvant mono-Tam. IKKα activation or enforced FAT10 expression promotes Tam-resistance while loss of IKKα or FAT10 augments Tam sensitivity. The induction of FAT10 by IKKα is mediated by the transcription factor Pax5, and coordinated via an IKKα-p53-miR-23a circuit in which activation of IKKα attenuates p53-directed repression of FAT10. Thus, our findings establish IKKα-to-FAT10 pathway as a new therapeutic target for the treatment of Tam-resistant ER⁺ breast cancer.