Mesenchymal stem cells induce PD-L1 expression through the secretion of CCL5 in breast cancer cells

Various factors in the tumor microenvironment (TME) regulate the expression of PD-L1 in cancer cells. In TME, mesenchymal stem cells (MSCs) play a crucial role in tumor progression, metastasis, and drug resistance. Emerging evidence suggests that MSCs can modulate the immune-suppression capacity of TME through the stimulation of PD-L1 expression in various cancers; nonetheless, their role in the induction of PD-L1 in breast cancer remained elusive. Here, we assessed the potential of MSCs in the stimulation of PD-L1 expression in a low PD-L1 breast cancer cell line and explored its associated cytokine. We assessed the expression of MSCs-related genes and their correlation with PD-L1 across 1826 breast cancer patients from the METABRIC cohort. After culturing an ER+/differentiated/low PD-L1 breast cancer cells with MSCs conditioned-medium (MSC-CM) in a microfluidic device, a variety of in-vitro assays was carried out to determine the role of MSC-CM in breast cancer cells' phenotype plasticity, invasion, and its effects on induction of PD-L1 expression. In-silico analysis showed a positive association between MSCs-related genes and PD-L1 expression in various types of breast cancer. Through functional assays, we revealed that MSC-CM not only prompts a phenotype switch but also stimulates PD-L1 expression at the protein level through secretion of various cytokines, especially CCL5. Treatment of MSCs with cytokine inhibitor pirfenidone showed a significant reduction in the secretion of CCL5 and consequently, expression of PD-L1 in breast cancer cells. We concluded that MSCs-derived CCL5 may act as a PD-L1 stimulator in breast cancer.

Phage display screening of therapeutic peptide for cancer targeting and therapy

Recently, phage display technology has been announced as the recipient of Nobel Prize in Chemistry 2018. Phage display technique allows high affinity target-binding peptides to be selected from a complex mixture pool of billions of displayed peptides on phage in a combinatorial library and could be further enriched through the biopanning process; proving to be a powerful technique in the screening of peptide with high affinity and selectivity. In this review, we will first discuss the modifications in phage display techniques used to isolate various cancer-specific ligands by in situ, in vitro, in vivo, and ex vivo screening methods. We will then discuss prominent examples of solid tumor targeting-peptides; namely peptide targeting tumor vasculature, tumor microenvironment (TME) and over-expressed receptors on cancer cells identified through phage display screening. We will also discuss the current challenges and future outlook for targeting peptide-based therapeutics in the clinics.

The role of tumour microenvironment: a new vision for cholangiocarcinoma

Cholangiocarcinoma (CCA) is a relatively rare malignant and lethal tumour derived from bile duct epithelium and the morbidity is now increasing worldwide. This disease is difficult to diagnose at its inchoate stage and has poor prognosis. Therefore, a clear understanding of pathogenesis and major influencing factors is the key to develop effective therapeutic methods for CCA. In previous studies, canonical correlation analysis has demonstrated that tumour microenvironment plays an intricate role in the progression of various types of cancers including CCA. CCA tumour microenvironment is a dynamic environment consisting of authoritative tumour stromal cells and extracellular matrix where tumour stromal cells and cancer cells can thrive. CCA stromal cells include immune and non‐immune cells, such as inflammatory cells, endothelial cells, fibroblasts, and macrophages. Likewise, CCA tumour microenvironment contains abundant proliferative factors and can significantly impact the behaviour of cancer cells. Through abominably intricate interactions with CCA cells, CCA tumour microenvironment plays an important role in promoting tumour proliferation, accelerating neovascularization, facilitating tumour invasion, and preventing tumour cells from organismal immune reactions and apoptosis. This review summarizes the recent research progress regarding the connection between tumour behaviours and tumour stromal cells in CCA, as well as the mechanism underlying the effect of tumour stromal cells on the growth of CCA. A thorough understanding of the relationship between CCA and tumour stromal cells can shed some light on the development of new therapeutic methods for treating CCA.

Macrophage-colony stimulating factor (CSF1) predicts breast cancer progression and mortality

BACKGROUND

Macrophage colony-stimulating factor (CSF1), also known as colony-stimulating factor-1 (CSF1), and its receptor CSF1R have been correlated with poor prognosis in many cancer types including breast cancer. Herein, we investigated the prognostic impact of CSF1 and CSF1R expression in tumor epithelial and stromal compartments in primary breast cancer and axillary lymph node metastases. In addition, the density of CD68+ tumor-associated macrophages (TAMs) and CD3+ T-lymphocytes was examined.

MATERIALS AND METHODS

Tumor tissue was obtained at the time of primary surgery from 68 prior treatment breast cancer patients, 38 with axillary lymph node metastases and 30 patients without metastases. Digital video analysis was performed on immunohistochemically stained slides.

RESULTS

The expression of CSF1, CSF1R and the density of TAMs and CD3+ T-lymphocytes were then correlated to metastases and disease-specific mortality. Metastasized primary cancers had higher tumor epithelial and stromal expressions of CSF1 (p<0.001 and p=0.002, respectively) and CSF1R (both p=0.03) compared to non-metastatic cancers. Similar findings were made for the density of CD68+ (p=0.003) and CD3+ cells in the tumor epithelium (p<0.001). In multivariate analysis, a high tumor epithelial expression of CSF1 in primary breast cancer predicted mortality (hazard ratio (HR)=8.6, p=0.039).

CONCLUSION

High expression of CSF1 and CSF1R and high density of TAMs and CD3+ T-lymphocytes were related to breast cancer progression. CSF1 expression in tumor epithelium predicted breast cancer mortality.

An immunohistochemical approach for monitoring effects of exercise on tumor stromal cells in old mice

Epidemiological evidence supports a protective effect of physical activity for breast cancer in older women, but the mechanisms are not well understood. We used 18-month-old BALB/c mice injected in the mammary fat pad with syngeneic 4T1 tumor cells as a model of invasive breast cancer. During the tumor progression phase, there was a significant decrease in labeling for F4/80, a marker for mouse macrophages, and CD34, a marker for vascular endothelial cells, in primary tumors from mice that ran higher average distances compared to mice that ran lower average distances (p≤0.05). These observations suggest that immunohistochemistry can be used to monitor stromal cell populations in tumors from old mice under exercise conditions.