Dickkopf-1 drives tumor immune evasion by inducing PD-L1 expression in hepatocellular carcinoma

Dickkopf-1 (DKK1) drives growth and metastases in castration-resistant prostate cancer

Metastatic castration-resistant prostate cancer (mCRPC) is associated with a poor prognosis and remains an incurable fatal disease. Therefore, the identification of molecular markers involved in cancer progression is urgently needed to develop more-effective therapies. The present study investigated the role of the Wnt signaling modulator Dickkopf-1 (DKK1) in the growth and metastatic progression of mCRPC. DKK1 silencing through siRNA and deletion via CRISPR/Cas9 editing were performed in two different metastatic castration-resistant prostate cancer cell lines (PC3 and DU145). A xenograft tumor model was used to assess tumor growth and metastases. In in vitro experiments, both DKK1 silencing and deletion reduced cell growth and migration of both cell lines. DKK1 knockout clones (DKK1-KO) exhibited cell cycle arrest, tubulin reorganization, and modulation of tumor metastasis-associated genes. Furthermore, in DKK1-KO cells, E-cadherin re-expression and its membrane co-localization with β-catenin were observed, contributing to reduced migration; Cadherin-11, known to increase during epithelial-mesenchymal transition, was down-regulated in DKK1-KO cells. In the xenograft mouse model, DKK1 deletion not only reduced tumor growth but also inhibited the formation of lung metastases. In conclusion, our findings support the key role of DKK1 in the growth and metastatic dissemination of mCRPC, both in vitro and in vivo.

Dickkopf-1 is an immune infiltration-related prognostic biomarker of head and neck squamous cell carcinoma

Immunotherapy is currently one of the most viable therapies for head and neck squamous cell carcinoma (HNSCC), characterized by high immune cell infiltration. The Wnt-signaling inhibitor and immune activation mediator, Dickkopf-1 (DKK1), has a strong correlation with tumor growth, tumor microenvironment, and, consequently, disease prognosis. Nevertheless, it is still unclear how DKK1 expression, HNSCC prognosis, and tumor-infiltrating lymphocytes are related. To better understand these associations, we examined how DKK1 expression varies across different tumor and normal tissues. In our study, we investigated the association between DKK1 mRNA expression and clinical outcomes. Next, we assessed the link between DKK1 expression and tumor immune cell infiltration. Additionally, using immunohistochemistry, we evaluated the expression of DKK1 in 15 healthy head and neck tissue samples, and the expression of CD3, CD4, and DKK1 in 27 HNSCC samples. We also explored aberrant DKK1 expression during tumorigenesis. DKK1 expression was remarkably higher in HNSCC tissues than in healthy tissues, and was shown to be associated with tumor stage, grade, lymph node metastasis, histology, and a dismal clinical prognosis in HNSCC. DKK1 expression in HNSCC tissues was inversely correlated with CD3+ (P < 0.0001) and CD4+ (P < 0.0001) immune cell infiltration, while that in immune cells was inversely associated with HNSCC prognosis. These findings offer a bioinformatics perspective on the function of DKK1 in HNSCC immunotherapy and provide justification for clinical research on DKK1-targeted HNSCC treatments. DKK1 is a central target for improving the efficacy of HNSCC immunotherapy.

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.

Immunosensitivity mediated by downregulated AKT1-SKP2 induces anti-PD-1-associated thyroid immune injury

BACKGROUND

Immune checkpoint inhibitors evoke the immune system, which may cause immune-related adverse effects. The predictors and mechanisms of anti-PD-1-associated thyroid immune injury remain unclear.

METHODS

A retrospective analysis is conducted on 518 patients treated with anti PD-1/PD-L1. Firstly, the differences between anti PD-1 and anti PD-L1 are compared on the risk of thyroid immune injury. Then, the predictors of the risk and thyroid function for anti PD-1 related thyroid immune injury are analyzed. Furthermore, the in vitro mechanism of normal thyroid cells (NTHY) is studied. First, the effect of anti PD-1 on the cell viability and immune sensitivity of thyroid cells is observed. Cell viability includes cell proliferation, apoptosis, cell cycle, T4 secretion, while immune sensitivity includes molecular expression and CD8 + T cell aggregation and killing towards NTHY. Then the differentially expressed proteins (DEPs) are screened by protein mass spectrometry. Enrichment of KEGG pathway and annotation of GO function on DEPs are conducted. Human protein-protein interactions are obtained from STRING database. The network is constructed and analyzed using Cytoscape software. In vitro, key proteins and their pathways are validated through overexpression plasmids or inhibitors. The recovery experiment and the immuno-coprecipitation experiment are designed to support the results. In vivo, the key proteins are detected in the thyroid tissue of mice fed with anti PD-1, as well as in the thyroid tissue of patients with Hashimoto's thyroiditis.

RESULTS

Thyroid irAE is associated with female, IgG, FT4, TPOAb, TGAb, TSHI, TFQI, and TSH. Peripheral lymphocytes are associated with thyroid function. In vitro, the NIVO group shows prologed G1 phase, decreased FT4, downregulated PD-L1, upregulated IFN-γ, and more CD8 + T cell infiltration and cytotoxicity. AKT1-SKP2 is chosen as the key protein. AKT1 overexpression and SKP2 inhibitor replies to NIVO and AKT1 overexpression, respectively. Immunoprecipitation shows SKP2 and PD-L1 interaction.

CONCLUSION

Female, impaired thyroid hormone sensitivity and IgG4 contribute to the risk of thyroid irAE, while peripheral blood lymphocyte characteristics affect thyroid function. Anti-PD-1 induces thyroid irAE by downregulating AKT1-SKP2 to enhance thyroid immunosensitivity.