Expression of YKL-40 by peritumoral macrophages in human small cell lung cancer
Introduction
YKL-40 is a secreted 40 kDa extra cellular matrix glycoprotein belonging to the “mammalian chitinase-like proteins” with chitin binding abilities but without chitinase activity [1], [2], [3]. The gene for YKL-40 is known (CHI3L1) and located on chromosome 1q31–q32 [4], [5]. The crystallographic three-dimensional structure of human and goat YKL-40 are described but the site and mode of binding to cell surface receptors are not yet described [2], [3], [6]. The function of YKL-40 is yet elusive but high expression is found during non-pathological processes such as mammary involution and in pathological conditions characterized by inflammation, tissue destruction and development of fibrosis suggesting a major role of YKL-40 in tissue remodeling [7], [8], [9], [10], [11], [12], [13]. Concordantly, YKL-40 stimulates proliferation of connective tissue cells, including fibroblasts, chondrocytes and synovial cells and modulates expression of chemokines and metalloproteases in inflammatory fibroblasts [14], [15], [16]. Furthermore, YKL-40 stimulates GAG synthesis in chondrocytes and exhibits strong binding to heparin [15], [17]. The porcine YKL-40 has been shown to stimulate endothelial cell migration and tube formation, as well as migration and adhesion of vascular smooth muscle cells suggesting an involvement in angiogenesis [18], [19].
Elevated serum concentrations of YKL-40 are found in a subgroup of patients with different types of solid tumors, including several types of adenocarcinomas (breast, colorectal and ovarian), small cell lung cancer (SCLC) and glioblastoma. Furthermore, elevated serum YKL-40 is notably correlated to poor prognosis and short survival [20], [21], [22], [23], [24], [25], [26], [27], [28]. No information exists as to which cells are responsible for the high YKL-40 level in serum in these patients nor has a function in cancer been clarified.
Macrophages, neutrophils, cultured chondrocytes, synovial cells and vascular smooth muscle cells produce YKL-40, whereas fibroblasts do not express YKL-40 [1], [4], [17], [18], [29], [30], [31], [32], [33], [34]. In vitro studies have shown YKL-40 production by cancer cells such as the osteosarcoma cell line MG-63, the myeloid leukemia cell lines THP-1 and HL-60 and glioblastoma cell line U87 (unpublished observation) [5], [30], [35]. Based on these observations it has been suggested that either the cancer cells, macrophages or both cell types might be responsible in part for the elevated YKL-40 in serum of cancer patients.
Since YKL-40 has been shown to be elevated in serum of patients with SCLC, we first investigated the expression of YKL-40 on mRNA and protein level in a panel of 20 human SCLC line cultures in vitro and in vivo grown as solid tumors on nude mice. Secondly, we evaluated whether YKL-40 was expressed by tumor cells and/or macrophages in biopsies from patients with SCLC.
Section snippets
Cell culture
Cell culture reagents were obtained from Invitrogen (UK) unless otherwise mentioned.
The origin and establishment of our 20 SCLC cancer cell lines from 16 patients are described elsewhere [36], [37], [38], [39], [40]. SCLC CPH 54A and CPH 54B were grown in Eagle's MEM. DMS cell lines were grown in Waymouth's medium, except DMS 79, which was grown in RPMI 1640. NCI-H69, NCI-N417, 24H and GLC cell lines were grown in RPMI 1640. All cells were cultured at 37 °C, 5% carbon dioxide and 95–98% humidity
YKL-40 is expressed by stromal cells and not by SCLC cells
A panel of 20 human SCLC cell lines was investigated for YKL-40 mRNA expression by RT-PCR. Hardly any expression was detectable (Fig. 1A). Only one cell line, DMS79, showed weak expression of YKL-40 mRNA. This observation was confirmed on the protein level, where no YKL-40 was detectable by ELISA in the conditioned cell culture media from any of the cell lines.
The same human SCLC cell lines were then propagated as solid tumors on nude mice in order to investigate if an altered microenvironment
Discussion
In previous work it has been reported that a subgroup of patients with SCLC is characterized by elevated serum concentrations of YKL-40 compared to healthy controls and that high serum YKL-40 was associated to short survival [26]. We here show strong evidence that the increased serum YKL-40 levels in SCLC patients are not caused by the cancer cells, which do not express YKL-40 either in vitro or in vivo. Instead, we find pronounced YKL-40 expression in tumor associated macrophages (TAMs) at the
Acknowledgements
Pia Knudsen is thanked for excellent technical assistance. Quidel provided YKL-40 ELISA kits. The study was supported by grants from The Danish Cancer Society and the Danish Medical Research council.
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2021, Annals of Vascular SurgeryCitation Excerpt :YKL-40 belongs to the mammalian chitinase-like protein family and is released from activated neutrophils, macrophages, vascular smooth muscle cells, and chondrocytes.9,10 YKL-40 shows a strong correlation with endothelial dysfunction, although it plays a role in extracellular matrix remodeling, macrophage-activated acute inflammation, and T cell activation.7,9 In addition, it is also known that YKL-40 expression plays a role in tumor growth via stimulation of angiogenesis.10,11
Angiogenic potential of YKL-40 in the dynamics of tumor niche
2018, Biomedicine and PharmacotherapyCitation Excerpt :In contrast to normal cells, YKL-40 is known to be observed in many solid tumors like kidney, breast, small cell lung carcinoma colon, etc. [11–19]. The participation of YKL-40 factor has been also evidenced during extracellular matrix remodeling, macrophage-induced inflammation, and T-cell activity [4,6]. In line with this statement, it has been previously demonstrated that serum samples pooled from patients with inflammatory diseases, diabetes, and cardiovascular diseases contain large amounts of YKL-40 [20].
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2016, Epilepsy ResearchCitation Excerpt :Numerous inflammatory conditions are associated with increased YKL-40 expression, and YKL-40 may represent a novel therapeutic target for inflammation, matrix remodeling, fibrosis and tumors. In the periphery, YKL-40 was highly expressed in differentiated macrophages (Junker et al., 2005; Michelsen et al., 2010), neutrophils (Letuve et al., 2008), synoviocytes (Huang and Wu, 2009) and smooth muscle cells (Chen et al., 2011). In the CNS, YKL-40 was expressed in astrocytes, which were associated with inflammatory diseases such as multiple sclerosis, Alzheimer’s disease and schizophrenia in autopsy tissues (Bonneh-Barkay et al., 2010a).