BackgroundColon cancer (CC) cells can exhibit stemness and expansion capabilities, which contribute to resistance to conventional chemotherapies. Aberrant expression of CBX8 has been identified in many types of cancer, but the cause of this aberrant CBX8 expression and whether CBX8 is associated with stemness properties in CC remain unknown.MethodsqRT-PCR and IHC were applied to examine CBX8 levels in normal and chemoresistant CC tissues. Cancer cell stemness and chemosensitivity were evaluated by spheroid formation, colony formation, Western blot and flow cytometry assays. RNA-seq combined with ChIP-seq was used to identify target genes, and ChIP, IP and dual luciferase reporter assays were applied to explore the underlying mechanisms.ResultsCBX8 was significantly overexpressed in chemoresistant CC tissues. In addition, CBX8 could promote stemness and suppress chemosensitivity through LGR5. Mechanistic studies revealed that CBX8 activate the transcription of LGR5 in a noncanonical manner with assistance of Pol II. CBX8 recruited KMT2b to the LGR5 promoter, which maintained H3K4me3 status to promote LGR5 expression. Moreover, m6A methylation participated in the upregulation of CBX8 by maintaining CBX8 mRNA stability.ConclusionsUpon m6A methylation-induced upregulation, CBX8 interacts with KMT2b and Pol II to promote LGR5 expression in a noncanonical manner, which contributes to increased cancer stemness and decreased chemosensitivity in CC. This study provides potential new therapeutic targets and valuable prognostic markers for CC.

CCL18 is a chemokine that is primarily expressed in monocytes, macrophages and immature dendritic cells and plays a crucial role in immune and inflammation responses. Recently, CCL18 was found to play pivotal roles in the development of several kinds of cancers, but its expression status and role during the tumorigenesis of pancreatic cancer remain unknown. In this study, we performed immunohistochemistry and enzyme-linked immunosorbent assay (ELISA) to evaluate the expression of CCL18 in human pancreatic ductal adenocarcinoma (PDAC) tissues and preoperative serum, respectively. The results showed that both cancer epithelial cells and mesenchymal macrophages in PDAC tissues positively expressed CCL18. Serum CCL18 levels were significantly higher in patients with PDAC in comparison to healthy controls. The expression of CCL18 in both cancer epithelial cells and mesenchymal cells was correlated with lymph node metastasis, histopathological grading and overall survival in 62 PDAC patients. In vitro assays showed that the gene and protein expression of CCL18 from U937 and THP-1 cell- derived macrophages were significantly higher than that from unstimulated U937 cells and THP-1 cells. In contrast, pancreatic cancer cell lines showed little to no CCL18 expression even after IL4 stimulation. Intriguingly, pancreatic cancer cell lines expressed the potential CCL18 receptors PITPNM3, CCR6 and GPR3. Furthermore, treatment with recombinant human CCL18 promoted the migration and invasion of pancreatic cancer cells, but had no effect on cell proliferation. Consistent with these results, CCL18 induced the expression of the epithelial-mesenchymal transition (EMT) related gene SNAIL1. Our findings suggest that the serum level of CCL18 is a potential biomarker for the diagnosis and prognosis of PDAC, and that the combined functions of CCL18 in mesenchymal and cancer cells might accelerate the progression of PDAC by promoting the epithelial-mesenchymal transition, invasion and migration of pancreatic cancer cells.

No abstract

In this study, the impact of pancreatic cancer cell interaction with macrophages on the differentiation and function of macrophages and the behaviors of pancreatic cancer cells in vitro is evaluated. The expression of immunocompetent cell-associated markers in 22 pancreatic cancer specimens was characterized by immunohistochemistry. The impact of pancreatic cancer cells (PANC-1 and BxPC-3) on the differentiation and migration of human U937 monocytes and the effect of U937-derived macrophages on the proliferation and invasion of PANC-1 and BxPC-3 were determined by transwell assays. The potential effect on U937-derived macrophages or on the behaviors of pancreatic cancer cells following coculture in a transwell system was analyzed by quantitative real-time polymerase chain reaction. The high levels of macrophage-related CD68 and CD163 expression were detected in the pancreatic cancer specimens. Pancreatic cancer cells promoted the differentiation of U937 cells and migration of U937-derived macrophages, but decreased the mRNA transcripts of macrophage polarization-related genes of interleukin (IL)-10, IL-12p40, inducible nitric oxide synthase (iNOS), and CD163, particularly for iNOS. Furthermore, U937-derived M2 macrophages inhibited the proliferation of pancreatic cancer cells, but promoted their invasion. Coculture of pancreatic cancer cells with U937-derived macrophages upregulated the mRNA expression of genes associated with the epithelialmesenchymal transition process, angiogenesis, and stemness of pancreatic cancer, but downregulated the expression of Ecadherin in pancreatic cancer cells. The interaction between pancreatic cancer cells and tumor-associated macrophages may play a pivotal role in the progression of pancreatic cancer.