Upregulation of the B7/CD28 family member B7-H3 in bladder cancer

The inhibitory effects of nimotuzumab on CD276 expression and immune escape in head and neck squamous cell carcinoma: Insights into anticancer mechanisms

CD276 has been identified as a novel immune checkpoint, and its overexpression is associated with immune evasion and poor prognosis in various tumors, including head and neck squamous cell carcinoma (HNSCC). Nimotuzumab, a humanized anti-epidermal growth factor receptor (EGFR) monoclonal antibody, has been approved for various solid tumors. However, it remains unclear whether its anticancer efficacy involves a reduction in CD276 expression. The purpose of this study was to investigate the regulatory effects and potential mechanisms of nimotuzumab on CD276 expression both in vitro and in vivo. In a coculture system, nimotuzumab showed inhibitory effects on TGF-β-induced upregulation of CD276 at both the transcriptional and protein levels in HNSCC cell lines. Mechanistic studies revealed that nimotuzumab primarily suppressed TGF-β-induced CD276 upregulation by blocking EGFR/MEK/ERK, which was further validated by MEK and ERK inhibitors. In xenograft and mice HNSCC models, nimotuzumab exerted antitumor effects accompanied by significantly reduced CD276 expression during tumor progression. Analysis of tumor-infiltrating lymphocytes (TILs) profiles indicated that nimotuzumab orchestrated the tumor immune microenvironment (TIME) by notably increasing the frequency of T lymphocytes, including cytotoxic T lymphocytes and helper T lymphocytes, as well as macrophage cells. However, no significant changes were observed in the populations of NK cells, DC cells, and neutrophils. These findings offer new insights into the anticancer mechanisms of nimotuzumab and its underlying synergy in combined treatments with immunotherapy for HNSCC.

B7-H3 promotes nasopharyngeal carcinoma progression by regulating CD8+ T cell exhaustion

BACKGROUND

B7-H3 protein is an important regulator of the adaptive immune response in human tumorigenesis. 4-1BB is a co-stimulatory receptor expressed on activated CD8+ T cells, and regulates T cell immunity. Here, we investigated the role of B7-H3 in the growth and invasion of nasopharyngeal carcinoma (NPC) and the effect of its interaction with 4-1BB on tumor immunity.

METHODS

Short hairpin (sh) RNA was designed to knock down B7-H3 expression in NPC cells. NPC cells with stable knockdown of B7-H3 were established and injected into nude mice. The effects of B7-H3 on cell proliferation, apoptosis, and epithelial-to-mesenchymal transition (EMT) were detected by the CCK8 assay, flow cytometry, TUNEL assay, and western blot analysis. The migration and invasion abilities were determined using the Transwell assay and scratch assay. Co-immunoprecipitation (Co-IP) assays were performed to study the interaction between B7-H3 and 4-1BB. Anti-4-1BB antibody was used in a co-culture system and xenograft mice to study the effect of 4-1BB on NPC development.

RESULTS

NPC cells transfected with sh-B7-H3 showed a higher rate of apoptosis, slower growth rate, impaired migration, and less EMT in vitro. Xenograft mice with stable knockout of B7-H3 had lower tumor burdens, and the stripped tumors had lower rates of cell proliferation, higher rates of apoptosis, and less EMT in vivo. Additionally, decreased B7-H3 expression was positively correlated with interferon-γ, tumor necrosis factor-α, and 4-1BB+CD8+ tumor-infiltrating lymphocytes. Co-IP studies showed that B7-H3 interacts with 4-1BB. Also, the inhibitory effects of sh-B7-H3 on NPC tumor growth, invasion, and tumor immunity could be alleviated by the anti-4-1BB antibody both in vivo and in vitro.

CONCLUSION

Our findings suggest that B7-H3 may accelerate tumor growth, tumor cell invasion, and EMT, and interact with 4-1BB to produce CD8+ T cell exhaustion that inhibits tumor immunity. B7-H3 might serve as a novel target for treating NPC.

Elevated Expression of the Immune Checkpoint Ligand CD276 (B7-H3) in Urothelial Carcinoma Cell Lines Correlates Negatively with the Cell Proliferation

The cell surface molecule CD276 (B7-H3) is an immune checkpoint antigen. The elevated expression of CD276 on tumors contributes to the suppression of anti-tumor T-cell responses and correlates with poor prognosis.

METHODS

The expression of CD276 was explored in vitro on eight urothelial carcinoma cell lines (UM-UC) in comparison to eight normal urothelial cells (NUCs) by RT-qPCR, Western blotting, and flow cytometry. Cell proliferation was enumerated over consecutive passages. The expression of cancer stem cell markers CD24 and CD44, cytokeratins, and vimentin was investigated by immunofluorescence. The expression of CD276 in bladder tumor samples and metastases was explored by immunohistochemistry.

RESULTS

Expression of CD276 on cell surfaces was elevated on UM-UCs when compared to NUCs. In UM-UCs, CD276 transcripts correlated moderately positive with CD276 protein expression (ρ = 0.660) and strongly positive with CD276 surface-expression (ρ = 0.810). CD276 mRNA expression (ρ = -0.475) and CD276 protein expression (ρ = -0.417) had a significant negative correlation with proliferation, while a significant correlation between proliferation and cell surface expression was not observed in UM-UCs.

CONCLUSION

The expression of CD276 on UM-UC bladder tumor cell surfaces is elevated. Slow proliferating UM-UC cells express more CD276 mRNA and protein than fast proliferating cells. In patients, slow proliferating CD276high tumor (stem) cells may evade immune surveillance. However, cancer therapy targeting CD276 may be effective in the treatment of slow proliferating tumor cells.

B7-H3 Immune Checkpoint Protein in Human Cancer

B7-H3 belongs to the B7 family of immune checkpoint proteins, which are important regulators of the adaptive immune response and emerging key players in human cancer. B7-H3 is a transmembrane protein expressed on the surface of tumor cells, antigen presenting cells, natural killer cells, tumor endothelial cells, but can also be present in intra- and extracellular vesicles. Additionally, B7-H3 may be present as a circulating soluble isoform in serum and other body fluids. B7-H3 is overexpressed in a variety of tumor types, in correlation with poor prognosis. B7-H3 is a promising new immunotherapy target for anti-cancer immune response, as well as a potential biomarker. Besides its immunoregulatory role, B7-H3 has intrinsic pro-tumorigenic activities related to enhanced cell proliferation, migration, invasion, angiogenesis, metastatic capacity and anti-cancer drug resistance. B7-H3 has also been found to regulate key metabolic enzymes, promoting the high glycolytic capacity of cancer cells. B7-H3 receptors are still not identified, and little is known about the molecular mechanisms underlying B7-H3 functions. Here, we review the current knowledge on the involvement of B7-H3 in human cancer.

Checkpoint Genes at the Cancer Side of the Immunological Synapse in Bladder Cancer

Immune checkpoint inhibitors have revolutionized cancer therapy, but not all cancers respond to the currently available drugs, and even within cancers considered responsive to such modality, response rates range between 15 and 40%, depending on the cancer type, the line of treatment, and yet unknown clinical/molecular factors. Coordinated expression of checkpoint proteins was shown to occur on T cells, probably allowing fine-tuning of the signal transmitted to the cell. We performed a bioinformatic analysis of the expression of putative checkpoint mRNAs at the cancer side of the immunological synapse from the bladder cancer tumorgenome atlas (TCGA) database. Fifteen mRNAs, corresponding to both coinhibitory and costimulatory checkpoints, were shown to be expressed above a designated threshold. Of these, seven mRNAs were found to be coexpressed: CD277, PD-1L, CD48, CD86, galectin-9, TNFRSF14 (HVEM), and CD40. The expression of 2 of these mRNAs-BTN3A1 (CD277) and TNFRSF14 (HVEM)-was positively correlated with overall survival in the TCGA database. All these seven mRNA share putative binding sites of a few transcription factors (TFs). Of these, the expression of the TF BACH-2 was positively correlated with the expression of checkpoint mRNAs from the network. This suggests a joint transcriptional regulation on the expression of checkpoint mRNAs at the bladder tumor side of the immunological synapse.

Involvement of soluble B7-H3 in combination with the serum inflammatory cytokines interleukin-17, -8 and -6 in the diagnosis of hepatocellular carcinoma

Previous studies have demonstrated that B7-H3, and the inflammatory cytokines interleukin (IL)-17, IL-8 and IL-6, are involved in the development of a variety of tumors. The objectives of the present study were: i) To investigate the association between soluble B7-H3 (sB7-H3) and cytokine levels of IL-17, IL-8 and IL-6 in the serum of patients with hepatocellular carcinoma (HCC); and ii) to determine their potential value for use in HCC diagnosis. Serum sB7-H3, IL-17, IL-8 and IL-6 levels in the HCC patients and healthy control subjects were measured using ELISA. The accuracy of each of these biomarkers in HCC diagnosis was compared using a receiver operating characteristic curve and the area under the curve (AUC). A logistic regression model was used to investigate the accuracy of diagnosing HCC when evaluated using combined determinations of sB7-H3, IL-17, IL-8 and IL-6 levels. The data demonstrated that serum levels of sB7-H3, IL-17, IL-8 and IL-6 were significantly increased in HCC patients compared with those in the healthy control group. Serum sB7-H3 levels were positively associated with serum IL-17, whereas serum IL-8 levels were negatively correlated with serum IL-17 levels. The AUC values for sB7-H3, IL-17, IL-8 and IL-6 were 83.2, 65.7, 95.3 and 97.0%, respectively, and indicated that all four biomarkers exhibited a statistically significant capacity for diagnosing HCC. Using the logistic regression model, the AUC value, sensitivity and specificity, as determined for the combination of the four biomarkers, were 99.2, 96.67 and 97.14%, respectively. This was significantly greater than that achieved when any single biomarker was used alone in the logistic regression model to assess their accuracy in HCC diagnosis. The optimum cutoff value of the predicted probability obtained by the combination of sB7-H3, IL-17, IL-8 and IL-6 in the regression model was 0.5745. To conclude, the present study revealed that there exists a positive association between serum sB7-H3 and IL-17 levels in HCC patients. Determinations involving the combination of serum sB7-H3, IL-17, IL-8 and IL-6 levels demonstrate great potential for use in HCC diagnosis.

Immunotherapy for Patients with Advanced Urothelial Cancer: Current Evidence and Future Perspectives

In recent years, immunotherapy has produced encouraging results in a rapidly increasing number of solid tumors. The responsiveness of bladder cancer to immunotherapy was first established in nonmuscle invasive disease in 1976 with intravesical instillations of bacillus Calmette-Guérin (BCG). Very recently immune checkpoint inhibitors demonstrated good activity and significant efficacy in metastatic disease. In particular the best results were obtained with programmed death-ligand-1 (PD-L1) and programmed death-1 (PD-1) inhibitors, but many other immune checkpoint inhibitors, including anti-cytotoxic T-lymphocyte-associated protein-4 (CTLA-4) antibodies, are currently under investigation in several trials. Simultaneously other therapeutic strategies which recruit an adaptive immune response against tumoral antigens or employ externally manipulated tumor infiltrating lymphocytes might change the natural history of bladder cancer in the near future. This review describes the rationale for the use of immunotherapy in bladder cancer and discusses recent and ongoing clinical trials with checkpoint inhibitors and other novel immunotherapy agents.

The expanding repertoire of targets for immune checkpoint inhibition in bladder cancer: What lies beneath the tip of the iceberg, PD-L1

Over the last decade, a new understanding of tumor-immune system interplay has been ushered in, lead in large part by the discovery of immune checkpoints mediated through B7-CD28 family interactions. Therapeutic blockade of the PD-L1 immune checkpoint pathway has already shown great success as a cancer immunotherapy for advanced urothelial carcinoma, leading to durable clinical remissions in an otherwise incurable disease. There are newly described members of the B7-CD28 family including B7-H3, B7x, and HHLA2. These ligands are thought to play an essential role in suppressing T-cell response, leading to immune tolerance of tumors. This feature makes them attractive targets for novel immunotherapy treatment paradigms. Here, we review the literature of current strategies and future directions of immune checkpoint blockade therapy for bladder cancer.

B7-H3 Promotes the Migration and Invasion of Human Bladder Cancer Cells via the PI3K/Akt/STAT3 Signaling Pathway

Bladder cancer is one of most common malignant cancer. Although previous studies have found abnormal expression of B7-H3 in human bladder cancer tissues, the exact role and molecular mechanism of B7-H3 in bladder cancer remain unknown. In this study, we first detected the expression of B7-H3 in human bladder cancer samples and cell lines, and analyzed its correlations with clinicopathological pathological parameters. Next, siRNAs or overexpression plasmids of B7-H3 were transfected into T24 or 5637 cells, and cell proliferation, apoptosis, migration and invasion were analyzed via CCK-8, colony formation, flow cytometry and transwell assays, protein expression levels were determined by western blotting. The results presented here showed B7-H3 was upregulated in bladder cancer samples compared with normal tissues, and the expression level was correlated with local invasion status. B7-H3 did not affect cell proliferation and apoptosis, but cell migration and invasion were changed through the regulation of matrix metalloproteinase (MMP) 2/9. Knockdown of B7-H3 resulted in decreased activity of the STAT3 and PI3K/Akt pathways, and the Akt served as an upstream regulator of the STAT3. Our results suggest that the overexpression of B7-H3 promotes the migration and invasion of human bladder cancer cells through the PI3K/Akt/STAT3 signaling pathway.