CircSMARCC1 facilitates tumor progression by disrupting the crosstalk between prostate cancer cells and tumor-associated macrophages via miR-1322/CCL20/CCR6 signaling.

BACKGROUND: Circular RNAs (circRNAs) mediate the infiltration of tumor-associated macrophages (TAMs) to facilitate carcinogenesis and development of various types of cancers. However, the role of circRNAs in regulating macrophages in prostate cancer (PCa) remains uncertain. METHODS: Differentially expressed circRNAs in PCa were identified by RNA sequencing. The expression of circSMARCC1 was recognized and evaluated using fluorescence in situ hybridization and quantitative real-time PCR. The oncogenic role of circSMARCC1 in PCa tumor proliferation and metastasis was investigated through a series of in vitro and in vivo assays. Finally, Western blot, biotin-labeled RNA pulldown, luciferase assay, rescue experiments, and co-culture experiments with TAMs were conducted to reveal the mechanistic role of circSMARCC1. RESULTS: CircSMARCC1 was dramatically up-regulated in PCa cells, plasma and tissues. Overexpression of circSMARCC1 promotes tumor proliferation and metastasis both in vitro and in vivo, whereas knockdown of circSMARCC1 exerts the opposite effects. Mechanistically, circSMARCC1 regulates the expression of CC-chemokine ligand 20 (CCL20) via sponging miR-1322 and activate PI3K-Akt signaling pathway involved in the proliferation and epithelial mesenchymal transformation. More importantly, high expression of circSMARCC1 was positively associated with colonization of CD68+/CD163+/CD206+ TAMs in tumor microenvironment. In addition, overexpression of circSMARCC1 facilitates the expression of CD163 in macrophages through the CCL20-CCR6 axis, induces TAMs infiltration and M2 polarization, thereby leading to PCa progression. CONCLUSIONS: CircSMARCC1 up-regulates the chemokine CCL20 secretion by sponging miR-1322, which is involved in the crosstalk between tumor cells and TAMs by targeting CCL20/CCR6 signaling to promote progression of PCa.

Association of CCR6 functional polymorphisms with Primary Biliary Cholangitis.

The biliary epithelial cells release CC chemokine receptor 6 (CCR6) ligand 20 (CCL20), leading to recruitment of CCR6+ T cells and subsequent infiltration into the biliary epithelium in primary biliary cholangitis patients. Previous genome-wide multi-national meta-analysis, including our Han Chinese cohort, showed significant association of CCR6 and CCL20 single nucleotide polymorphisms (SNP) with PBC. We report here that significantly associated SNPs, identified in the CCR6 locus based on our Han Chinese genome-wide association study, can be separated into "protective" and "risk" groups, but only "risk" SNPs were confirmed using a separate Han Chinese PBC cohort. Only weak association of CCL20 SNPs was observed in Han Chinese PBC cohorts. Fine-mapping and logistical analysis identified a previously defined functional variant that, leads to increased CCR6 expression, which contributed to increased genetic susceptibility to PBC in Han Chinese cohort.

Expression of Membrane-Bound CC Chemokine Ligand 20 on Follicular T Helper Cells in T-B-Cell Conjugates.

The CC chemokine receptor 6 (CCR6) and its sole chemokine ligand CC chemokine ligand 20 (CCL20) display an emerging role in the coordination of humoral immune responses. Recent studies demonstrate a role of this chemokine axis in the migration of B cells to key immunological sites during an immune response, and facilitating the generation of high-quality antibodies. Very little, however, is known about CCL20 and its role in these functions. We undertook a preliminary investigation into the expression and function of CCL20 and demonstrate its well-noted upregulation in the spleen during immunization. Furthermore, we show that most follicular T helper (Tfh) cells can be CCR6+ and can produce CCL20. Surprisingly, CCL20 cannot only be found in the cytoplasm but also on the surface of these cells and their precursors. Analysis of T-B-cell conjugates revealed that mature Tfh cells, but not their precursors, are highly enriched in the conjugates. Further functional studies are needed to unravel the precise role of CCL20 in coordinating T and B cell interactions during the humoral immune response.

Production of CCL20 on nucleus pulposus cells recruits IL-17-producing cells to degenerated IVD tissues in rat models.

IL-17-producing cells play an important role in various autoimmune diseases. A higher level of IL-17-producing cells is observed in patients with intervertebral disc (IVD) degeneration. However, the mechanism of the accumulation of IL-17-producing cells remains to be elucidated. Our aim is to demonstrate whether the interaction of CC chemokine ligand (CCL) 20 and its specific receptor CCR6 is involved in the recruitment of IL-17-producing cells to degenerated disc tissues in rat models. The well-accepted needle puncture model and the autologous nucleus pulposus application model of rats were established. All of the animals were randomly divided into four groups: the sham surgery group, the needle puncture group (NP group), the sham surgery + autologous nucleus pulposus application group (sham-ANPA group) and the needle puncture + autologous nucleus pulposus application group (NP-ANPA group). Immunohistochemical staining, western blot and real-time PCR were used to evaluate the expression levels of CCL20, IL-17 and CCR6 in the IVD samples. Moreover, the IL-17 concentrations in the serum were detected by ELISA. Pearson correlations were performed to analyse the correlation among the expressions of CCL20, CCR6 and IL-17. The expressions of CCL20, IL17 and CCR6 were dramatically elevated in comparison with the control groups. The circulating IL-17 in the serum of the NP-ANPA group was elevated compared to the sham surgery group. In addition, there was a positive correlation among the expression levels of CCL20, CCR6 and IL-17. The results suggest a potential mechanism for the recruitment of IL-17-producing cells to degenerated intervertebral discs via a CCL20/CCR6 system in vivo.