CD200R signaling contributes to unfavorable tumor microenvironment through regulating production of chemokines by tumor-associated myeloid cells

Translation of Data from Animal Models of Cancer to Immunotherapy of Breast Cancer and Chronic Lymphocytic Leukemia

The field of clinical oncology has been revolutionized over the past decade with the introduction of many new immunotherapies the existence of which have depended to a large extent on experimentation with both in vitro analysis and the use of various animal models, including gene-modified mice. The discussion below will review my own laboratory's studies, along with those of others in the field, on cancer immunotherapy. Our own studies have predominantly dwelt on two models of malignancy, namely a solid tumor model (breast cancer) and lymphoma. The data from our own laboratory, and that of other scientists, highlights the novel information so obtained, and the evidence that application of such information has already had an impact on immunotherapy of human oncologic diseases.

CD200/CD200R: Bidirectional Role in Cancer Progression and Immunotherapy

As an immune checkpoint molecule, CD200 serves a foundational role in regulating immune homeostasis and promoting self-tolerance. While CD200 expression occurs in various immune cell subsets and normal tissues, its aberrant expression patterns in hematologic malignancies and solid tumors have been linked to immune evasion and cancer progression under pathological conditions, particularly through interactions with its cognate receptor, CD200R. Through this CD200/CD200R signaling pathway, CD200 exerts its immunosuppressive effects by inhibiting natural killer (NK) cell activation, cytotoxic T cell functions, and M1-polarized macrophage activity, while also facilitating expansion of myeloid-derived suppressor cells (MDSCs) and Tregs. Moreover, CD200/CD200R expression has been linked to epithelial-to-mesenchymal transition and distant metastasis, further illustrating its role in cancer progression. Conversely, CD200 has also been shown to exert anti-tumor effects in certain cancer types, such as breast carcinoma and melanoma, indicating that CD200 may exert bidirectional effects on cancer progression depending on the specific tumor microenvironment (TME). Regardless, modulating the CD200/CD200R axis has garnered clinical interest as a potential immunotherapeutic strategy for cancer therapy, as demonstrated by early-phase clinical trials. However, further research is necessary to fully understand the complex interactions of CD200 in the tumor microenvironment and to optimize its therapeutic potential in cancer immunotherapy.

Emerging Immune Checkpoint Molecules on Cancer Cells: CD24 and CD200

Cancer immunotherapy strategies are based on the utilization of immune checkpoint inhibitors to instigate an antitumor immune response. The efficacy of immune checkpoint blockade, directed at adaptive immune checkpoints, has been demonstrated in select cancer types. However, only a limited subset of patients has exhibited definitive outcomes characterized by a sustained response after discontinuation of therapy. Recent investigations have highlighted the significance of immune checkpoint molecules that are overexpressed in cancer cells and inhibit myeloid lineage immune cells within a tumor microenvironment. These checkpoints are identified as potential targets for anticancer immune responses. Notably, the immune checkpoint molecules CD24 and CD200 have garnered attention owing to their involvement in tumor immune evasion. CD24 and CD200 are overexpressed across diverse cancer types and serve as signaling checkpoints by engaging their respective receptors, Siglec-10 and CD200 receptor, which are expressed on tumor-associated myeloid cells. In this review, we summarized and discussed the latest advancements and insights into CD24 and CD200 as emergent immune checkpoint moieties, further delving into their therapeutic potentials for cancer treatment.

CD200-CD200R affects cisplatin and paclitaxel sensitivity by regulating cathepsin K-mediated p65 NF-κB signaling in cervical cancer

Background

CD200-CD200R plays a critical role in regulating the human tumor microenvironment, but its role in cervical cancer remains unclear.

Methods

A total of 62 paraffin blocks of tumor tissues were collected from cervical cancer patients. Expression of CD200 and cathepsin K (CTSK) in cancer tissues and para-cancerous tissues was analyzed by immunohistochemistry. Stably transfected CD200 cells were established in HeLa and SiHa cells. Human THP-1 monocytes were induced to differentiate into M2 macrophages. HeLa and SiHa cells were cultured in conditioned medium from M2 macrophages to observe the effects of CD200-CD200R on invasion, CTSK, p65NF-κB, and cisplatin or paclitaxel sensitivity in cervical cancer cells. HeLa cells were injected to induce xenograft tumors in mice, and a CTSK inhibitor, MK-0822, was used to confirm the regulation of CTSK and paclitaxel sensitivity by CD200-CD200R in vivo.

Results

A significant decrease in CD200 and CTSK expression was found in tumor cancer tissues compared with para-cancerous tissues. Only CD200 overexpression did not affect cervical cell invasion, but CD200-CD200R could enhance the cell invasion and resistance to cisplatin or paclitaxel. Meanwhile, expression of CTSK and p-p65NF-κB in cancer cells stably transfected with CD200 was obviously increased after culture in conditioned medium from M2 macrophages compared with transfection with the plasmid control. In vivo, CTSK inhibition significantly suppressed the effects of CD200-CD200R overexpression on the response to paclitaxel by suppressing the CTSK-mediated NF-κB pathway.

Conclusions

CD200-CD200R regulates CTSK-mediated NF-κB pathway to affect cisplatin or paclitaxel sensitivity in cervical cancer, which provides a possible immunotherapeutic target and combination strategy for advanced cervical cancer.