Paracrine Activation of Chemokine Receptor CCR9 Enhances The Invasiveness of Pancreatic Cancer Cells

Abstract

Chemokine receptors mediate cancer progression and metastasis. We have previously examined chemokine receptor CCR9 expression in pancreatic cancer. Here, our objective was to evaluate pancreatic stellate cells (PSCs) as a source of CCL25, the CCR9 ligand, and as an activator of CCL25-CCR9 signaling in pancreatic cancer cells. CCL25 and CCR9 expression levels in human pancreatic cancer tissues and normal human pancreas were assessed by immunohistochemsitry. In vitro secretion of CCL25 in PSCs and PANC-1 cells was verified by enzyme-linked immunosorbent assay. Pancreatic cancer cell invasion was measured using a modified Boyden chamber assay with CCL25, PSC secreted proteins, and PANC-1 secreted proteins as the chemoattractant. There was immunostaining for CCR9 expression in human pancreatic tumor tissues, but not in normal pancreatic tissue. CCL25 expression was absent in the normal pancreatic tissue sample, but was observed in cancer cells and in the stromal cells surrounding the tumor. In vitro, both PANC-1 cells and PSCs secreted CCL25. In an invasion assay, exposure to CCL25, PSC-and PANC-1-conditioned media significantly increased the invasiveness of PANC-1 cells. Inclusion of a CCR9-neutralizing antibody in the invasion assay blocked the increase in invading cells elicited by the chemoattractants. Our studies show that pancreatic cancer invasiveness is enhanced by autocrine and paracrine stimulation of CCR9. PSCs in the tumor microenvironment appear to contribute to paracrine activation of CCR9. Investigations into CCR9 as a potential therapeutic target in pancreatic cancer must consider cancer cell autocrine signaling and also paracrine signaling from interactions in the tumor microenvironment.

CCR9–CCL25 interaction suppresses apoptosis of lung cancer cells by activating the PI3K/Akt pathway

“…Chemokines are small (8)(9)(10)(11)(12)(13)(14) proteins that play key roles in development and leukocyte trafficking through interactions with cognate cell surface seven-transmembrane G protein-coupled receptors (GPCRs) [6]. CC chemokine receptor-9 (CCR9) is a GPCR and plays an important role in T cell development and tissue-specific homing when binding to its specific ligand CCL25, which is also known as thymus-expressed chemokine (TECK) [7].…”

“…Chemokines are also important for solid tumor apoptosis. CCR9 is expressed in some carcinoma cells and may promote proliferation and suppress apoptosis of cancer cells by activating the PI3K/Akt pathway [8][9][10][11]. In addition, CCR9 could be a prognostic marker and therapeutic target in solid carcinoma [12,13].…”

Intracellular expression profile and clinical significance of the CCR9–CCL25 chemokine receptor complex in nasopharyngeal carcinoma

“…18 Abnormal chemokine and receptor expression and signalling has been reported in tumour cells. [29][30][31] For example, neutralisation of the CCL25-CCR9 interaction impaired the migration and invasion potential of the LNCaP and PC3 cell lines. [24][25][26][27][28] Further, CCR9 and its CCL25 ligand are overexpressed in prostate cancer cells of epithelial origin; the CCL25-CCR9 complex is important for prostate cancer invasion and metastasis.…”

CCR9‐mediated signaling through β‐catenin and identification of a novel CCR9 antagonist

“…The chemokine receptor–ligand axis CCR9/CCL25 is responsible for T‐cell development and chemotrafficking of thymocytes, macrophages, and dendritic cells in normal tissues of the thymus and small intestine (Vicari et al., 1997; Zaballos et al., 1999). There is now considerable evidence linking the CCR9/CCL25 axis to cancer progression and metastasis (Amersi et al., 2008; Heinrich et al., 2013; Singh et al., 2011; Zaballos et al., 1999). For example, CCR9 involvement in melanoma‐specific metastasis to the small intestine has been attributed to the invasion of CCR9‐expressing melanoma cells toward the specific chemoattractant CCL25 in the small intestine (Amersi et al., 2008).…”

“…For example, CCR9 involvement in melanoma‐specific metastasis to the small intestine has been attributed to the invasion of CCR9‐expressing melanoma cells toward the specific chemoattractant CCL25 in the small intestine (Amersi et al., 2008). Because we have previously demonstrated high expression of CCR9 in pancreatic cancer cells, we aim to further characterize CCR9‐mediated signaling and the potential role of CCR9 in the invasive phenotype of pancreatic cancer (Heinrich et al., 2013; Shen et al., 2009).…”