Nuclear Coregulatory Complexes in Tregs as Targets to Promote Anticancer Immune Responses

T-regulatory cells require Sin3a for stable expression of Foxp3

Histone deacetylases 1 and 2 play a major role in the transcriptional regulation of T-regulatory (Treg) cells via interactions with a myriad of coregulatory factors. Sin3a has been well established as a Hdac1/2 cofactor, while its role within Tregs has not been established. In this study, the effects of conditional deletion of Sin3a within Foxp3+ Tregs were evaluated. Developmental deletion of Sin3a from Foxp3+ Tregs resulted in the rapid onset of fatal autoimmunity. Treg numbers were greatly reduced, while residual Tregs had impaired suppressive function. Mice also showed effector T-cell activation, autoantibody production, and widespread tissue injury. Mechanistically, Sin3a deletion resulted in decreased transcription of Foxp3 with a complete lack of CNS2 CpG demethylation. In addition, Foxp3 protein stability was impaired with an increased ex-Treg population. Thus, Sin3a plays a critical role in the maintenance of Treg identity and function and is essential for the expression and stability of Foxp3.

Differential Effects of HDAC6 Inhibition Versus Knockout During Hepatic Ischemia-reperfusion Injury Highlight Importance of HDAC6 C-terminal Zinc-finger Ubiquitin-binding Domain

BACKGROUND

Ischemia-reperfusion injury (IRI) causes significant morbidity in liver transplantation among other medical conditions. IRI following liver transplantation contributes to poor outcomes and early graft loss. Histone/protein deacetylases (HDACs) regulate diverse cellular processes, play a role in mediating tissue responses to IRI, and may represent a novel therapeutic target in preventing IRI in liver transplantation.

METHODS

Using a previously described standardized model of murine liver warm IRI, aspartate aminotransferase (AST) and alanine aminotransferase (ALT) levels were assessed at 24 and 48 h after reperfusion to determine the effect of different HDAC inhibitors.

RESULTS

Broad HDAC inhibition with trichostatin-A (TSA) was protective against hepatocellular damage (P < 0.01 for AST and P < 0.05 for ALT). Although HDAC class I inhibition with MS-275 provided statistically insignificant benefit, tubastatin-A (TubA), an HDAC6 inhibitor with additional activity against HDAC10, provided significant protection against liver IRI (P < 0.01 for AST and P < 0.001 for ALT). Surprisingly genetic deletion of HDAC6 or -10 did not replicate the protective effects of HDAC6 inhibition with TubA, whereas treatment with an HDAC6 BUZ-domain inhibitor, LakZnFD, eliminated the protective effect of TubA treatment in liver ischemia (P < 0.01 for AST and P < 0.01 for ALT).

CONCLUSIONS

Our findings suggest TubA, a class IIb HDAC inhibitor, can mitigate hepatic IRI in a manner distinct from previously described class I HDAC inhibition and requires the HDAC6 BUZ-domain activity. Our data corroborate previous findings that HDAC targets for therapeutic intervention of IRI may be tissue-specific, and identify HDAC6 inhibition as a possible target in the treatment of liver IRI.

Comprehensive pan-cancer analysis of role of GPRASP1, associated with clinical outcomes, immune microenvironment, and immunotherapeutic efficiency in pancreatic cancer

BACKGROUND

GPRASP1 (G-protein-coupled receptor-associated sorting protein 1) plays an important role in tumorigenesis. However, GPRASP1 specific role has not been clearly clarified in cancer, particularly in pancreatic cancer(PC).

METHODS

Firstly, we utilized pan-cancer analysis based on RNA sequencing data from TCGA (The Cancer Genome Atlas) to evaluate the expression pattern and immunological role of GPRASP1. Then, through multiple transcriptome datasets (TCGA and Gene Expression Omnibus (GEO)) and multi-omics (RNA-seq, DNA methylation, copy number variations (CNV), somatic mutation data) in-depth analysis, we comprehensively explore the relationship of GPRASP1 expression with clinicopathologic characteristics, clinical outcomes, CNV, and DNA methylation in pancreatic cancer. Additionally, we employed immunohistochemistry (IHC) to further confirm GPRASP1 expression pattern between PC tissues and paracancerous tissues. Lastly, we systematically associated the GPRASP1 with immunological properties from numerous perspectives, such as immune cell infiltration, immune-related pathways, immune checkpoint inhibitors, immunomodulators, immunogenicity, and immunotherapy.

RESULTS

Through pan-cancer analysis, we identified that GPRASP1 plays a critical role in the occurrence and prognosis of PC, and is closely related to immunological characteristics in PC. IHC analysis confirmed that GPRASP1 is significantly down-regulated in PC compared with normal tissues. The expression of GPRASP1 is significantly negatively correlated with clinical features (histologic grade, T stage, and TNM stage), and is an independent predictor of favorable prognosis, regardless of other clinicopathological features (HR: 0.69, 95% CI 0.54-0.92, p= 0.011). The etiological investigation found that the abnormal expression of GPRASP1 was related to DNA methylation and CNV frequency. Subsequently, the high expression of GPRASP1 was significantly correlated with immune cell infiltration (CD8 + T cell, tumor-infiltrating lymphocyte(TIL)), immune-related pathways(cytolytic activity, check-point, human leukocyte antigen (HLA)), immune checkpoint inhibitors (CTLA4, HAVCR2, LAG3, PDCD1 and TIGIT), immunomodulators ( CCR4/5/6, CXCL9, CXCR4/5), and immunogenicity(immune score, neoantigen, TMB(tumor mutation burden)). Finally, IPS (immunophenoscore) and TIDE (tumor immune dysfunction and exclusion) analysis demonstrated that GPRASP1 expression levels can accurately predict the immunotherapeutic response.

CONCLUSION

GPRASP1 is a promising candidate biomarker that plays a role in the occurrence, development, and prognosis of PC. Evaluating GPRASP1 expression will aid in the characterization of tumor microenvironment (TME) infiltration and orient more efficient immunotherapy strategies.

GPRASP1 is a candidate anti-oncogene and correlates with immune microenvironment and immunotherapeutic efficiency in head and neck cancer

BACKGROUND

G-protein-coupled receptor-associated sorting protein 1 (GPRASP1) plays an important role in tumorigenesis. However, GPRASP1 specific role has not been clarified in head and neck cancer (HNC).

METHODS

HNC RNA sequencing (RNA-seq) datasets, DNA methylation data, somatic mutation data, copy number variation (CNV) data, and corresponding clinicopathologic information were acquired from the Cancer Genome Atlas (TCGA) and Gene Expression Omnibus (GEO) databases. A comprehensive evaluation was performed to explore the relationship of GPRASP1 expression with clinicopathologic characteristics, CNV, and DNA methylation. Additionally, we employed HNC tissue microarray (TMA) to further confirm the relation between GPRASP1 expression and clinical features. Then, we systematically associated the GPRASP1 with immunological properties from numerous perspectives, such as immune cell infiltration, immune-related pathways, immune checkpoint inhibitors (ICIs), immunomodulators, immunogenicity, and immunotherapy.

RESULTS

Analyzing TCGA, GEO, and TMA datasets, GPRASP1 is significantly down-regulated in HNC compared to normal tissues. The expression of GPRASP1 is significantly negatively correlated with clinical features (perineural invasion, histologic grade, T stage, and TNM stage), and is an independent predictor of favorable prognosis, regardless of other clinicopathological features (HR: 0.42, 95% CI 0.20-0.91, p = 0.028). The etiological investigation found that the abnormal expression of GPRASP1 was related to DNA methylation, not CMV. Subsequently, the high expression of GPRASP1 was significantly correlated with immune cell infiltration (CD8⁺  T cell, tumor infiltrating lymphocyte), immune-related pathways (cytolytic activity, check-point, human leukocyte antigen), ICIs (CTLA4, HAVCR2, LAG3, PDCD1, and TIGIT), immunomodulators (CCR4/5, CXCL9, CXCR3/4/5), and immunogenicity (immune score, neoantigen, tumor mutation burden). Finally, immunophenoscore and tumor immune dysfunction and exclusion analysis demonstrated that GPRASP1 expression levels can accurately predict the immunotherapeutic response.

CONCLUSION

GPRASP1 is a promising candidate biomarker that plays a role in the occurrence, development, and prognosis of HNC. Evaluating GPRASP1 expression will aid in the characterization of tumor microenvironment infiltration and orient more efficient immunotherapy strategies.

HDAC inhibitors Panobinostat and Romidepsin enhance tax transcription in HTLV-1-infected cell lines and freshly isolated patients’ T-cells

The viral transactivator Tax plays a key role in HTLV-1 reactivation and de novo infection. Previous approaches focused on the histone deacetylase inhibitor (HDACi) Valproate as a latency-reversing agent to boost Tax expression and expose infected cells to the host’s immune response. However, following treatment with Valproate proviral load decreases in patients with HAM/TSP were only transient. Here, we hypothesize that other compounds, including more potent and selective HDACi, might prove superior to Valproate in manipulating Tax expression. Thus, a panel of HDACi (Vorinostat/SAHA/Zolinza, Panobinostat/LBH589/Farydak, Belinostat/PXD101/Beleodaq, Valproate, Entinostat/MS-275, Romidepsin/FK228/Istodax, and MC1568) was selected and tested for toxicity and potency in enhancing Tax expression. The impact of the compounds was evaluated in different model systems, including transiently transfected T-cells, chronically HTLV-1-infected T-cell lines, and freshly isolated PBMCs from HTLV-1 carriers ex vivo. We identified the pan-HDACi Panobinostat and class I HDACi Romidepsin as particularly potent agents at raising Tax expression. qRT-PCR analysis revealed that these inhibitors considerably boost tax and Tax-target gene transcription. However, despite this significant increase in tax transcription and histone acetylation, protein levels of Tax were only moderately enhanced. In conclusion, these data demonstrate the ability of Panobinostat and Romidepsin to manipulate Tax expression and provide a foundation for further research into eliminating latently infected cells. These findings also contribute to a better understanding of conditions limiting transcription and translation of viral gene products.