The role of B7 family molecules in hematologic malignancy

The B7 family consists of structurally related, cell-surface proteins that regulate immune responses by delivering costimulatory or coinhibitory signals through their ligands. Eight family members have been identified to date including CD80 (B7-1), CD86 (B7-2), CD274 (programmed cell death-1 ligand [PD-L1]), CD273 (programmed cell death-2 ligand [PD-L2]), CD275 (inducible costimulator ligand [ICOS-L]), CD276 (B7-H3), B7-H4, and B7-H6. B7 ligands are expressed on both lymphoid and nonlymphoid tissues. The importance of the B7 family in regulating immune responses is clear from their demonstrated role in the development of immunodeficiency and autoimmune diseases. Manipulation of the signals delivered by B7 ligands shows great potential in the treatment of cancers including leukemias and lymphomas and in regulating allogeneic T-cell responses after stem cell transplantation.

Expression of VISTA correlated with immunosuppression and synergized with CD8 to predict survival in human oral squamous cell carcinoma

V-domain Ig suppressor of T cell activation (VISTA), a novel immune checkpoint regulatory molecule, suppresses T cell mediated immune responses. The aim of the present study was to profile the immunological expression, clinical significance and correlation of VISTA in human oral squamous cell carcinoma (OSCC). Human tissue microarrays, containing 165 primary OSCCs, 48 oral epithelial dysplasias and 43 normal oral mucosae, were applied to investigate the expression levels of VISTA, CD8, cytotoxic T lymphocyte-associated antigen 4 (CTLA-4), programmed death ligand 1 (PD-L1), PI3Kα p110, IL13Rα2, phospho-STAT3 at tyrosine 705 (p-STAT3) and myeloid-derived suppressor cell (MDSC) markers (CD11b and CD33) by immunohistochemistry and digital pathology analysis. The results demonstrated that the protein level of VISTA was significantly higher in human OSCC specimens, and that VISTA expression in primary OSCCs was correlated with lymph node status. VISTA expression did not serve as an independent predictor for poor prognosis, while patient subgroup with VISTA high and CD8 low expression (22/165) had significantly poorer overall survival compared with other subgroups based on the multivariate and Cox hazard analyses among the primary OSCC patients in the present cohort. Additionally, the expression of VISTA was significantly correlated with PD-L1, CTLA-4, IL13Rα2, PI3K, p-STAT3, CD11b and CD33 according to Pearson's correlation coefficient test. Taken together, the results indicated that the VISTA high and CD8 low group, as an immunosuppressive subgroup, might be associated with a poor prognosis in primary OSCC. These findings indicated that VISTA might be a potential immunotherapeutic target in OSCC treatment.

B7-H3 is expressed in human hepatocellular carcinoma and is associated with tumor aggressiveness and postoperative recurrence

B7-H3, a novel B7 family member, positively or negatively regulates T-cell responses. We investigated the clinical relevance and prognostic significance of B7-H3 in hepatocellular carcinoma (HCC). Western blotting showed B7-H3 upregulation in 17 of 24 (70.8 %) HCC tissues compared with nontumor liver tissues (p = 0.028). B7-H3 immunostaining on tissue microarrays containing 240 HCC patient samples indicated that 225 (93.8 %) tumors had aberrant B7-H3 expression, with strong intensity in 79 (32.9 %) cases, whereas B7-H3 expression in peritumor liver cells was weak in most cases (226; 94.2 %). Notably, patients with high/moderate tumor cell B7-H3 expression showed significantly poorer survival (p = 0.009) and increased recurrence (p = 0.002). After multivariable adjustment, high/moderate B7-H3 expression remained significant for an increased risk of recurrence (hazard ratio = 1.79; 95 % confidence interval = 1.19-2.70; p = 0.005). B7-H3 expression correlated with invasive phenotypes like vascular invasion and advanced tumor stage, and the metastatic potential of HCC cell lines. Flow cytometry showed that B7-H3 expression is inversely correlated with proliferation and interferon-γ production by infiltrating T cells. Interferon-γ stimulation significantly upregulated B7-H3 expression in HCC cells in vitro, implicating B7-H3 expression as a feedback mechanism to evade anti-tumor immunity. Importantly, the prognostic value of B7-H3 expression was validated in an independent cohort of 206 HCC patients. Collectively, our data suggest that B7-H3 was abundantly expressed in HCC and was associated with adverse clinicopathologic features and poor outcome. Thus, B7-H3 represents an attractive target for diagnostic and therapeutic manipulation in human HCC.

Lymphatics, lymph nodes and the immune system: barriers and gateways for cancer spread

Metastasis to the regional lymph node is the most important prognostic indicator for the outcomes of patients with sold cancer. In general, it is well recognized that cancer development is genetically determined with progression from the microenvironment of the primary tumor site, oftentimes via the SLN gateway, to the distant sites. In about 20 % of the time, the cancer cells may spread directly through the blood vascular system to the distant sites. Thus, in general, cancer progression is consistent with Hellman's spectrum theory in that development of nodal and systemic metastasis from a localized cancer growth is a progressive process. Cancer proliferation within the tumor microenvironment may give rise to increased tumor heterogeneity, which is further complicated by its continuous change through its evolution within the host in a Darwinian sense. It is crucial to understand the molecular process of lymphangiogenesis and hemangiogenesis in the tumor microenvironment with respect to the initial steps of cancer cells entering into the lymphatic and vascular systems so that rational therapy can be developed to curb the process of specific routes of metastasis. This chapter elucidates the role of lymphatics, nodal metastasis and antitumor immunity. We present novel immune targets in nodal metastases, the importance of the lymph node as a pre-metastatic niche, and immune-related proteins as biomarkers of metastasis.

CD276 and the gene signature composed of GATA3 and LGALS3 enable prognosis prediction of glioblastoma multiforme

Glioma is the most common type of primary brain tumor, accounting for 40% of malignant brain tumors. Although a single gene may not be a marker, an expression profiling and multivariate analyses for cancer immunotherapy must estimate survival of patients. In this study, we conducted expression profiling of immunotherapy-related genes, including those in Th1/2 helper T and regulatory T cells, and stimulatory and inhibitory checkpoint molecules associated with survival prediction in 571 patients with malignant and aggressive form of gliomas, glioblastoma multiforme (GBM). Expression profiling and Random forests analysis of 21 immunosuppressive genes and Kaplan-Meier analysis in 158 patients in the training data set suggested that CD276, also known as B7-H3, could be a single gene marker candidate. Furthermore, prognosis prediction formulas, composed of Th2 cell-related GATA transcription factor 3 (GATA3) and immunosuppressive galactose-specific lectin 3 (LGALS3), based on 67 immunotherapy-related genes showed poor survival with high scores in training data set, which was also validated in another 413 patients in the test data set. The CD276 expression helped distinguish survival curves in the test data set. In addition, inhibitory checkpoint genes, including T cell immunoreceptor with Ig and ITIM domains, V-set domain containing T cell activation inhibitor 1, T-cell immunoglobulin and mucin-domain containing 3, and tumor necrosis factor receptor superfamily 14, showed potential as secondary marker candidates. These results suggest that CD276 expression and the gene signature composed of GATA3 and LGALS3 are effective for prognosis in GBM and will help us understanding target pathways for immunotherapy in GBM.

Foreign body-type multinucleated giant cells induced by interleukin-4 express select lymphocyte co-stimulatory molecules and are phenotypically distinct from osteoclasts and dendritic cells

Foreign body-type multinucleated giant cells (FBGC), formed by macrophage fusion, are a prominent cell type on implanted biomaterials, although the roles they play at these and other sites of chronic inflammation are not understood. Why lymphocytes are present in this scenario and the effects of fusing macrophages/FBGC on subsequent lymphocyte responses are also unclear. To address the physiological significance of FBGC in this regard, we employed our in vitro system of interleukin (IL)-4-induced human monocyte-derived macrophage fusion/FBGC formation. Initially, we pursued the identities of lymphocyte co-stimulatory molecules on fusing macrophages/FBGC. In addition, we further compared the FBGC phenotype to that currently associated with osteoclasts and dendritic cells using recognized markers. Immunoblotting of cell lysates and immunochemistry of macrophages/FBGC in situ, revealed that IL-4-induced macrophages/FBGC strongly express HLA-DR, CD98, B7-2 (CD86), and B7-H1 (PD-L1), but not B7-1 (CD80) or B7-H2 (B7RP-1). Furthermore, molecules currently recognized to be expressed on osteoclasts (calcitonin receptor, tartrate-resistant acid phosphatase, RANK) or dendritic cells (CD1a, CD40, CD83, CD95/fas) are undetectable. In contrast, fusing macrophages/FBGC strongly express the macrophage markers αX integrin (CD11c), CD68, and dendritic cell-specific intercellular adhesion molecule-3-grabbing non-integrin (DC-SIGN), whereas CD14 is completely down-modulated with IL-4-induced macrophage fusion. These novel data demonstrate that IL-4-induction of macrophage multinucleation/FBGC formation features the acquisition of a CD14-negative phenotypic profile which is distinguishable from that of dendritic cells and osteoclasts, yet potentially exhibits multiple capacities for lymphocyte interactions with resultant lymphocyte down-modulation.

Immune checkpoint B7-H3 protein expression is associated with poor outcome and androgen receptor status in prostate cancer

BACKGROUND

Novel immune checkpoint-based immunotherapies may benefit specific groups of prostate cancer patients who are resistant to other treatments.

METHODS

We analyzed by immunohistochemistry the expression of B7-H3, PD-L1/B7-H1, and androgen receptor (AR) in tissue samples from 120 prostate adenocarcinoma patients treated with radical prostatectomy in Spain, and from 206 prostate adenocarcinoma patients treated with radical prostatectomy in Norway.

RESULTS

B7-H3 expression correlated positively with AR expression and was associated with biochemical recurrence in the Spanish cohort, but PD-L1 expression correlated with neither of them. Findings for B7-H3 were validated in the Norwegian cohort, where B7-H3 expression correlated positively with Gleason grade, surgical margins, seminal vesicle invasion, and CAPRA-S risk group, and was associated with clinical recurrence. High B7-H3 expression in the Norwegian cohort was also consistent with positive AR expression.

CONCLUSION

These results suggest distinct clinical relevance of the two immune checkpoint proteins PD-L1 and B7-H3 in prostate cancer. Our findings highlight B7-H3 as an actionable novel immune checkpoint protein in prostate cancer.

B7-H3 is spliced by SRSF3 in colorectal cancer

B7-H3, an important co-inhibitor, is abnormally highly expressed in a variety of malignancies. The antibodies targeting B7-H3 have exhibited beneficial therapeutic effects in clinical trials. Therefore, discovery of the regulatory factors in B7-H3 expression may provide new strategies for tumor therapy. Here, we investigated the splicing factors involved in the splicing of B7-H3. By individual knockdown of the splicing factors in colorectal cancer (CRC) cells, we found that B7-H3 expression was markedly inhibited by SRSF3 and SRSF8, especially SRSF3. Then we found that both SRSF3 and B7-H3 were highly expressed in CRC tissues. Moreover, high-expression of either SRSF3 or B7-H3 was significantly correlated with poor prognosis of patients. The expression of B7-H3 mRNA and protein were evidently reduced by SRSF3 silence, but were enhanced by overexpression of SRSF3 in both HCT-116 and HCT-8 cells. The results from the RNA immunoprecipitation (RIP) assays demonstrated that SRSF3 protein directly binds to B7-H3 mRNA. In addition, we constructed a minigene recombinant plasmid for expressing B7-H3 exons 3-6. We found that SRSF3 contributed to the retention of B7-H3 exon 4. These findings demonstrate that SRSF3 involves in the splicing of B7-H3 by directly binding to its exon 4 and/or 6. It may provide novel insights into the regulatory mechanisms of B7-H3 expression and potential strategies for the treatment of CRC.

Mifepristone inhibited the expression of B7-H2, B7-H3, B7-H4 and PD-L2 in adenomyosis

BACKGROUND

The immune mechanism was shown to be involved in the development of adenomyosis. The aim of the current study was to evaluate the expression of the immune checkpoints B7-H2, B7-H3, B7-H4 and PD-L2 in adenomyosis and to explore the effect of mifepristone on the expression of these immune checkpoints.

METHODS

The expression of B7-H2, B7-H3, B7-H4 and PD-L2 in normal endometria and adenomyosis patient samples treated with or without mifepristone was determined by immunohistochemistry analysis.

RESULTS

In adenomyosis patient samples, the expression of B7-H2, B7-H3 and B7-H4 was increased in the eutopic and ectopic endometria compared with normal endometria, both in the proliferative and secretory phases. Moreover, the expression of B7-H2 and B7-H3 was higher in adenomyotic lesions than in the corresponding eutopic endometria, both in the proliferative and secretory phases. The expression of PD-L2 was higher in adenomyotic lesions than in normal endometria in both the proliferative and secretory phases. In the secretory phase but not the proliferative phase, the expression of B7-H4 and PD-L2 in adenomyotic lesions was significantly higher than that in the corresponding eutopic endometria. In normal endometria and eutopic endometria, the expression of B7-H4 was elevated in the proliferative phase compared with that in the secretory phase, while in the ectopic endometria, B7-H4 expression was decreased in the proliferative phase compared with the secretory phase. In addition, the expression of B7-H2, B7-H3, B7-H4 and PD-L2 was significantly decreased in adenomyosis tissues after treatment with mifepristone.

CONCLUSIONS

The expression of the immune checkpoint proteins B7-H2, B7-H3, B7-H4 and PD-L2 is upregulated in adenomyosis tissues and is downregulated with mifepristone treatment. The data suggest that B7 immunomodulatory molecules are involved in the pathophysiology of adenomyosis.