Expression of C-X-C motif chemokine receptors 4 and 7 in salivary gland neoplasms

The development of potent, competitive CXCR4 antagonists for the prevention of cancer metastasis

Cancer metastasis is the cause of up to 90 % of cancer related mortality. The CXCR4 receptor and its cognate ligand, CXCL12, have major roles in enabling cancer metastasis and consequently, the CXCR4 receptor has become an attractive therapeutic target for the prevention of metastasis. Despite this, CXCR4 antagonists have had limited success in clinical trials due to cellular toxicity and poor stability and efficacy. In this study, we developed a novel, competitive CXCR4 antagonist (IS4) that through copper-catalysed-azide-alkyne-cycloaddition can be clicked to other chemical moieties such as fluorescent dyes (IS4-FAM) for CXCR4-based imaging. We determined that these CXCR4 antagonists were non-toxic and could be used to specifically label the CXCR4 receptor. Furthermore, IS4 and IS4-FAM inhibited CXCL12-stimulated cancer cell migration and Ca2+ release in both adherent and suspension cell lines with similar or improved potency as compared to two literature CXCR4 antagonists. Our results highlight the potential of IS4 and IS4-FAM as research tools and as potent CXCR4 antagonists for the prevention of metastasis.

Immunological and biological dissection of normal and tumoral salivary glands

Salivary glands naturally play central roles in oral immunity. The salivary glands microenvironment inevitable may be exposed to exogenous factors consequently triggering the initiation and formation of various malignant and benign tumors. Mesenchymal stem cells are recruited into salivary gland microenvironment, interact with tumor cells, and induce inhibitory cytokines as well as cells with immunosuppressive phenotypes such as myeloid-derived suppressor cells (MDSCs) and regulatory T cells (Tregs). The immune components and tumor immune responses in malignant and benign SGTs are still under investigation. Immune responses may directly play a limiting role in tumor growth and expansion, or may participate in formation of a rich milieu for tumor growth in cooperation with other cellular and regulatory molecules. Immune checkpoint molecules (e.g. PDLs, HLA-G and LAG3) are frequently expressed on tumor cells and/or tumor-infiltrating lymphocytes (TILs) in salivary gland microenvironment, and an increase in their expression is associated with T cell exhaustion, immune tolerance and tumor immune escape. Chemokines and chemokine receptors have influential roles on aggressive behaviors of SGTs, and thereby they could be candidate targets for cancer immunotherapy. To present a broad knowledge on salivary glands, this review first provides a brief description on immunological functions of normal salivary glands, and then describe the SGT's tumor microenvironment, by focusing on mesenchymal stem cells, immune cell subsets, immune checkpoint molecules, chemokines and chemokine receptors, and finally introduces immune checkpoint inhibitors as well as potential targets for cancer therapy.

High CXCR4 expression in adenoid cystic carcinoma of the head and neck is associated with increased risk of locoregional recurrence

AIM

Treatment options for head and neck adenoid cystic carcinoma (AdCC) are limited in advanced disease. Chemokine receptor type 4 (CXCR4) is present in various tumour types, including AdCC. Upregulation is associated with tumour recurrence and metastasis. New CXCR4-specific diagnostic and therapeutic target agents have recently been available. This study aimed to analyse CXCR4 expression in a cohort of primary head and neck AdCC.

METHODS

After histopathological revision, tumour tissues of 73 consecutive patients with AdCC over 1990-2016 were sampled on a tissue microarray. Slides were immunohistochemically stained for CXCR4 and semiquantitatively scored. Associations between protein expression and cliniopathological parameters were tested. HRs were calculated using a Cox proportional hazard model.

RESULTS

Sixty-six tumours could be analysed. CXCR4 expression was present in 81% of the tumours with a median of 29% (IQR 1-70) positive cells. Expression was univariately correlated to perineural growth (Spearman ρ .26, p=0.04) and bone invasion (Spearman ρ .32, p=0.01), but not with tumour grade.CXCR4 expression in the primary tumour was significantly higher in tumours that recurred as compared with those that did not recur (median 60%, IQR 33-72 vs 12%, IQR 1-70, Kruskal-Wallis p=0.01). After dichotomisation, >25% of CXCR4 expressions proved an independent prognosticator for a reduced recurrence-free survival (RFS) (HR 7.2, 95% CI 1.5 to 72.4, p=0.04).

CONCLUSION

CXCR4 is expressed in the majority of primary AdCCs and independently correlated to worse RFS, suggesting CXCR4 as a target for imaging and therapy purposes in patients with advanced AdCC.