Chitinase-like proteins (CLPs) are lectins combining properties of cytokines and growth factors. Human CLPs include YKL-40, YKL-39 and SI-CLP that are secreted by cancer cells, macrophages, neutrophils, synoviocytes, chondrocytes and other cells. The best investigated CLP in cancer is YKL-40. Serum and plasma levels of YKL-40 correlate with poor prognosis in breast, lung, prostate, liver, bladder, colon and other types of cancers. In combination with other circulating factors YKL-40 can be used as a predictive biomarker of cancer outcome. In experimental models YKL-40 supports tumor initiation through binding to RAGE, and is able to induce cancer cell proliferation via ERK1/2-MAPK pathway. YKL-40 supports tumor angiogenesis by interaction with syndecan-1 on endothelial cells and metastatic spread by stimulating production of pro-inflammatory and pro-invasive factors MMP9, CCL2 and CXCL2. CLPs induce production of pro- and anti-inflammatory cytokines and chemokines, and are potential modulators of inflammatory tumor microenvironment. Targeting YKL-40 using neutralizing antibodies exerts anti-cancer effect in preclinical animal models. Multifunctional role of CLPs in regulation of inflammation and intratumoral processes makes them attractive candidates for tumor therapy and immunomodulation. In this review we comprehensively analyze recent data about expression pattern, and involvement of human CLPs in cancer.
Tumor associated macrophages (TAM) support tumor growth and metastasis in several animal models of breast cancer, and TAM amount is predictive for efficient tumor growth and metastatic spread via blood circulation. However, limited information is available about intratumoral TAM heterogeneity and functional role of TAM subpopulations in tumor progression. The aim of our study was to examine correlation of TAM presence in various morphological segments of human breast cancer with clinical parameters. Thirty six female patients with nonspecific invasive breast cancer T1-4N0-3M0 were included in the study. Morphological examination was performed using Carl Zeiss Axio Lab.A1 and MiraxMidiZeiss. Immunohistochemical and immunofluorescence/confocal microcopy analysis was used to detect CD68 and stabilin-1 in 5 different tumor segments: (1) areas with soft fibrous stroma; (2) areas with coarse fibrous stroma; (3) areas of maximum stromal-and-parenchymal relationship; (4) parenchymal elements; (5) gaps of ductal tumor structures. The highest expression of CD68 was in areas with soft fibrous stroma or areas of maximum stromal-and-parenchymal relationship (79%). The lowest expression of CD68 was in areas with coarse fiber stroma (23%). Inverse correlation of tumor size and expression of CD68 in gaps of tubular tumor structures was found (R=-0.67; p=0.02). In case of the lymph node metastases the average score of CD68 expression in ductal gaps tumor structures was lower (1.4±0.5) compared to negative lymph nodes case (3.1±1.0; F=10.9; p=0.007). Confocal microscopy identified 3 phenotypes of TAM: CD68/stabilin-1; CD68/stabilin-1 (over 50%); and CD68/stabilin-1. However, expression of stabilin-1 did not correlate with lymph node metastasis. We concluded, that increased amount of CD68+TAM in gaps of ductal tumor structures is protective against metastatic spread in regional lymph nodes.
Despite significant progress in cancer diagnostics and development of novel therapeutic regimens, successful treatment of advanced forms of cancer is still a challenge and may require personalized therapeutic approaches. In this review, we analyzed major mechanisms responsible for tumor cells chemoresistance and emphasized that intratumor heterogeneity is a critical factor that limits efficiency of cancer treatment. Intratumor heterogeneity is caused by genomic instability in cancer cells, resulting in the selection of resistant clones. Moreover, cancer cells in solid tumors are surrounded by cellular and molecular microenvironment that actively influences tumor cell behavior. Local tumor microenvironment (TME) consisting of immune cells with diverse phenotypes and functions strongly contributes to intratumor heterogeneity and modulates responses to treatment. Thus, targeting specific components of TME is a novel treatment strategy that can improve the outcome of conventional anti-cancer therapy. Here, we discuss modern immunotherapeutic approaches based on targeting tumorinfiltrating immune cells including neutrophils, dendritic cells, NK cells, T cells, B cells and macrophages. Among those, tumor-associated macrophages (TAM) that display a pronounced heterogeneity and phenotypic plasticity appear to be a major component in the TME of solid tumors, and emerge as perspective targets for cancer immunotherapy. TAM intratumor heterogeneity and the possible existence of patient-specific phenotype signature generate the basis for the development of individualized TAM-based therapeutic approaches.
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