Over-Expression of GUSB Leads to Primary Resistance of Anti-PD1 Therapy in Hepatocellular Carcinoma

Analysis of genomic ancestry and characterization of a new variant in MPS type VII

BACKGROUND

Mucopolysaccharidosis (MPS) type VII is a storage disorder of autosomal recessive origin that is caused by a deficiency in a lysosomal enzyme that results in the accumulation of glycosaminoglycans and causes secondary metabolic pathway problems. It has systemic symptoms that mainly include progressive skeletal dysplasia, cardiovascular manifestations, hepatosplenomegaly, coarse facies, and many other manifestations, and cognitive decline is observed in most cases. A significant proportion of patients may present with foetal hydrops. Allelic variations in specific ethnic groups explain the higher incidence in some groups due to founder effects and/or endogamy. In Brazil, the most common variant is p.Leu176Phe. This study aimed to investigate GUSB gene expression in a patient with MPS VII with a new mutation (p.Leu292Pro). Additionally, this study investigated the ancestry of 5 patients with MPS VII from Brazil to understand the Amerindian, African, and European contributions.

RESULTS

The analysis revealed varying proportions of ancestry markers in the sample of patients with MPS VII. The European contribution was more prominent and significantly different (p = 0.0031) from the African contribution. Relative expression analysis by the 2-ΔCT method revealed greater expression of the GUSB gene in the patient with MPS VII than in the control group (CG). However, some samples from the CG group presented higher expression than did the samples from the patient with the new mutation. Relative to the comparison among threshold cycles, 2/20 samples presented significantly different CT values for the patient with MPS VII when the numbers of amplification cycles were compared. The parents of the patient also presented different values (p < 0.05) for the amplification cycles. The in silico prediction of the new variant indicated that it affects function by modifying a highly conserved region.

CONCLUSIONS

The p.Leu176Phe mutation may have originated in Europe, as suggested in this study. There is a discrepancy between the mRNA levels of GUSB and the amount of beta-glucuronidase synthesized. The expression of the GUSB gene variant from the patient with MPS VII was within the range of the control group's distribution in this study. The p.Leu292Pro mutation is pathogenic, but its impact on the MPS VII phenotype still needs to be fully elucidated.

A novel allosteric driver mutation of β-glucuronidase promotes head and neck squamous cell carcinoma progression through STT3B-mediated PD-L1 N-glycosylation

Head and neck squamous cell carcinoma (HNSCC) develops and advances because of the accumulation of somatic mutations located in orthosteric and allosteric areas. However, the biological effects of allosteric driver mutations during tumorigenesis are mostly unknown. Here, we mapped somatic mutations generated from 10 tumor-normal matched HNSCC samples into allosteric sites to prioritize the mutated allosteric proteins via whole-exome sequencing and AlloDriver, identifying the specific mutation H351Q in β-glucuronidase (GUSB), a lysosomal enzyme, as a novel allosteric driver mutation, which considerably encouraged HNSCC progression both in vitro and in vivo. Mechanistically, the allosteric mutation of H351Q remarkably attenuated protein trafficking from the endoplasmic reticulum (ER) to lysosomes, leading to ER retention, in which GUSB-H351Q facilitated the aberrant N-glycosylation of PD-L1 through increasing protein stability and mRNA transcripts of the STT3 oligosaccharyltransferase complex catalytic subunit B, an oligosaccharyltransferase complex. Moreover, GUSB-H351Q reshaped a more immunosuppressive microenvironment featuring increased infiltration of exhausted CD8+ T cells and remodeled tumor metabolism, characterized by increased activity of the purine metabolism pathways and pyruvic acid accumulation. This study provides a mechanism-driven approach to overcoming HNSCC progression and immune evasion and identifies novel druggable targets based on the presence of GUSB allosteric driver mutation.

Assessment of circulating proteins in thyroid cancer: Proteome-wide Mendelian randomization and colocalization analysis

The causality between circulating proteins and thyroid cancer (TC) remains unclear. We employed five large-scale circulating proteomic genome-wide association studies (GWASs) with up to 100,000 participants and a TC meta-GWAS (nCase = 3,418, nControl = 292,703) to conduct proteome-wide Mendelian randomization (MR) and Bayesian colocalization analysis. Protein and gene expressions were validated in thyroid tissue. Through MR analysis, we identified 26 circulating proteins with a putative causal relationship with TCs, among which NANS protein passed multiple corrections (P BH = 3.28e-5, 0.05/1,525). These proteins were involved in amino acids and organic acid synthesis pathways. Colocalization analysis further identified six proteins associated with TCs (VCAM1, LGMN, NPTX1, PLEKHA7, TNFAIP3, and BMP1). Tissue validation confirmed BMP1, LGMN, and PLEKHA7's differential expression between normal and TC tissues. We found limited evidence for linking circulating proteins and the risk of TCs. Our study highlighted the contribution of proteins, particularly those involved in amino acid metabolism, to TCs.

Decoding the molecular landscape: A novel prognostic signature for uveal melanoma unveiled through programmed cell death-associated genes

Uveal melanoma (UM) is a rare but aggressive malignant ocular tumor with a high metastatic potential and limited therapeutic options, currently lacking accurate prognostic predictors and effective individualized treatment strategies. Public databases were utilized to analyze the prognostic relevance of programmed cell death-related genes (PCDRGs) in UM transcriptomes and survival data. Consensus clustering and Lasso Cox regression analysis were performed for molecular subtyping and risk feature construction. The PCDRG-derived index (PCDI) was evaluated for its association with clinicopathological features, gene expression, drug sensitivity, and immune infiltration. A total of 369 prognostic PCDRGs were identified, which could cluster UM into 2 molecular subtypes with significant differences in prognosis and clinicopathological characteristics. Furthermore, a risk feature PCDI composed of 11 PCDRGs was constructed, capable of indicating prognosis in UM patients. Additionally, PCDI exhibited correlations with the sensitivity to 25 drugs and the infiltration of various immune cells. Enrichment analysis revealed that PCDI was associated with immune regulation-related biological processes and pathways. Finally, a nomogram for prognostic assessment of UM patients was developed based on PCDI and gender, demonstrating excellent performance. This study elucidated the potential value of PCDRGs in prognostic assessment for UM and developed a corresponding risk feature. However, further basic and clinical studies are warranted to validate the functions and mechanisms of PCDRGs in UM.

Tumoral acidosis promotes adipose tissue depletion by fostering adipocyte lipolysis

OBJECTIVE

Tumour progression drives profound alterations in host metabolism, such as adipose tissue depletion, an early event of cancer cachexia. As fatty acid consumption by cancer cells increases upon acidosis of the tumour microenvironment, we reasoned that fatty acids derived from distant adipose lipolysis may sustain tumour fatty acid craving, leading to the adipose tissue loss observed in cancer cachexia.

METHODS

To evaluate the pro-lipolytic capacities of acid-exposed cancer cells, primary mouse adipocytes from subcutaneous and visceral adipose tissue were exposed to pH-matched conditioned medium from human and murine acid-exposed cancer cells (pH 6.5), compared to naive cancer cells (pH 7.4). To further address the role of tumoral acidosis on adipose tissue loss, a pH-low insertion peptide was injected into tumour-bearing mice, and tumoral acidosis was neutralised with a sodium bicarbonate buffer. Prolipolytic mediators were identified by transcriptomic approaches and validated on murine and human adipocytes.

RESULTS

Here, we reveal that acid-exposed cancer cells promote lipolysis from subcutaneous and visceral adipocytes and that dampening acidosis in vivo inhibits adipose tissue depletion. We further found a set of well-known prolipolytic factors enhanced upon acidosis adaptation and unravelled a role for β-glucuronidase (GUSB) as a promising new actor in adipocyte lipolysis.

CONCLUSIONS

Tumoral acidosis promotes the mobilization of fatty acids derived from adipocytes via the release of soluble factors by cancer cells. Our work paves the way for therapeutic approaches aimed at tackling cachexia by targeting the tumour acidic compartment.

ARHGAP18 is Upregulated by Transcription Factor GATA1 Promotes the Proliferation and Invasion in Hepatocellular Carcinoma

Rho GTPase activating protein 18 (ARHGAP18), a member of the RhoGAP gene family that increases GTP hydrolysis and inhibits RhoGTPase, was recently discovered to play a role in the development of breast cancer. However, its exact biological role in hepatocellular carcinoma (HCC) remains unclear. In our present study, we comprehensively assessed ARHGAP18 expression and its correlation with the prognostic value of cancer patients in databases. Cell proliferation and colony formation assays were employed to monitor cell growth. Luciferase reporter assay, Chromatin immunoprecipitation qPCR (ChIP-qPCR), immunofluorescence were performed for mechanism research. The expression of genes and proteins was detected by real-time PCR and western blotting. According to the findings of this research, ARHGAP18 protein levels are increased in HCC tissues compared to adjacent nontumor tissues, and ARHGAP18 overexpression is associated with poor survival. The results of a gain- and loss-of-function experiment with HCC cells in vitro demonstrated that ARHGAP18 stimulated cell proliferation, migration, and invasion. Mechanistically, we found that the transcription factor GATA binding protein 1 (GATA1) could bind to the ARHGAP18 promoter and facilitate ARHGAP18 expression. Further studies revealed that the effects of ARHGAP18 silencing on HCCLM3 and Bel-7402 cells were blocked by GATA1 overexpression. In conclusion, GATA1-mediated ARHGAP18 up-regulation plays an important role in HCC tumorigenesis and might be a potential therapeutic target for HCC.

The current status and future of PD-L1 in liver cancer

The application of immunotherapy in tumor, especially immune checkpoint inhibitors (ICIs), has played an important role in the treatment of advanced unresectable liver cancer. However, the efficacy of ICIs varies greatly among different patients, which has aroused people's attention to the regulatory mechanism of programmed death ligand-1 (PD-L1) in the immune escape of liver cancer. PD-L1 is regulated by multiple levels and signaling pathways in hepatocellular carcinoma (HCC), including gene variation, epigenetic inheritance, transcriptional regulation, post-transcriptional regulation, and post-translational modification. More studies have also found that the high expression of PD-L1 may be the main factor affecting the immunotherapy of liver cancer. However, what is the difference of PD-L1 expressed by different types of cells in the microenvironment of HCC, and which type of cells expressed PD-L1 determines the effect of tumor immunotherapy remains unclear. Therefore, clarifying the regulatory mechanism of PD-L1 in liver cancer can provide more basis for liver cancer immunotherapy and combined immune treatment strategy. In addition to its well-known role in immune regulation, PD-L1 also plays a role in regulating cancer cell proliferation and promoting drug resistance of tumor cells, which will be reviewed in this paper. In addition, we also summarized the natural products and drugs that regulated the expression of PD-L1 in HCC.

Noncoding RNAs as an emerging resistance mechanism to immunotherapies in cancer: basic evidence and therapeutic implications

The increasing knowledge in the field of oncoimmunology has led to extensive research into tumor immune landscape and a plethora of clinical immunotherapy trials in cancer patients. Immunotherapy has become a clinically beneficial alternative to traditional treatments by enhancing the power of the host immune system against cancer. However, it only works for a minority of cancers. Drug resistance continues to be a major obstacle to the success of immunotherapy in cancer. A fundamental understanding of the detailed mechanisms underlying immunotherapy resistance in cancer patients will provide new potential directions for further investigations of cancer treatment. Noncoding RNAs (ncRNAs) are tightly linked with cancer initiation and development due to their critical roles in gene expression and epigenetic modulation. The clear appreciation of the role of ncRNAs in tumor immunity has opened new frontiers in cancer research and therapy. Furthermore, ncRNAs are increasingly acknowledged as a key factor influencing immunotherapeutic treatment outcomes. Here, we review the available evidence on the roles of ncRNAs in immunotherapy resistance, with an emphasis on the associated mechanisms behind ncRNA-mediated immune resistance. The clinical implications of immune-related ncRNAs are also discussed, shedding light on the potential ncRNA-based therapies to overcome the resistance to immunotherapy.

Clinical Significance of Non-Coding RNA Regulation of Programmed Cell Death in Hepatocellular Carcinoma

Hepatocellular carcinoma (HCC) is a widely prevalent and malignantly progressive tumor. Most patients are typically diagnosed with HCC at an advanced stage, posing significant challenges in the execution of curative surgical interventions. Non-coding RNAs (ncRNAs) represent a distinct category of RNA molecules not directly involved in protein synthesis. However, they possess the remarkable ability to regulate gene expression, thereby exerting significant regulatory control over cellular processes. Notably, ncRNAs have been implicated in the modulation of programmed cell death (PCD), a crucial mechanism that various therapeutic agents target in the fight against HCC. This review summarizes the clinical significance of ncRNA regulation of PCD in HCC, including patient diagnosis, prognosis, drug resistance, and side effects. The aim of this study is to provide new insights and directions for the diagnosis and drug treatment strategies of HCC.

Genetics of enzymatic dysfunctions in metabolic disorders and cancer

Inherited metabolic disorders arise from mutations in genes involved in the biogenesis, assembly, or activity of metabolic enzymes, leading to enzymatic deficiency and severe metabolic impairments. Metabolic enzymes are essential for the normal functioning of cells and are involved in the production of amino acids, fatty acids and nucleotides, which are essential for cell growth, division and survival. When the activity of metabolic enzymes is disrupted due to mutations or changes in expression levels, it can result in various metabolic disorders that have also been linked to cancer development. However, there remains much to learn regarding the relationship between the dysregulation of metabolic enzymes and metabolic adaptations in cancer cells. In this review, we explore how dysregulated metabolism due to the alteration or change of metabolic enzymes in cancer cells plays a crucial role in tumor development, progression, metastasis and drug resistance. In addition, these changes in metabolism provide cancer cells with a number of advantages, including increased proliferation, resistance to apoptosis and the ability to evade the immune system. The tumor microenvironment, genetic context, and different signaling pathways further influence this interplay between cancer and metabolism. This review aims to explore how the dysregulation of metabolic enzymes in specific pathways, including the urea cycle, glycogen storage, lysosome storage, fatty acid oxidation, and mitochondrial respiration, contributes to the development of metabolic disorders and cancer. Additionally, the review seeks to shed light on why these enzymes represent crucial potential therapeutic targets and biomarkers in various cancer types.

Immune checkpoint inhibitor resistance in hepatocellular carcinoma

The application of immune checkpoint inhibitors (ICIs) has markedly enhanced the treatment of hepatocellular carcinoma (HCC), and HCC patients who respond to ICIs have shown prolonged survival. However, only a subset of HCC patients benefit from ICIs, and those who initially respond to ICIs may develop resistance. ICI resistance is likely related to various factors, including the immunosuppressive tumor microenvironment (TME), the absence of antigen expression and impaired antigen presentation, tumor heterogeneity, and gut microbiota. Therefore, exploring the possible mechanisms of ICI resistance is crucial to improve the clinical benefit of ICIs further. Various combination therapies for HCC immunotherapy have prevented and reversed ICI resistance to a certain extent. In addition, many new combination therapies that can overcome resistance are being explored. This review seeks to characterize the complex TME in HCC, explore the possible mechanisms of immune resistance to ICIs in different resistance categories, and review the combination therapies currently being applied and those under investigation for immunotherapy.