Our previous study has indicated that cancer-associated fibroblasts (CAFs) play a crucial role in regulating gemcitabine resistance through transferring exosomal miRNA-106b to cancer cells. Tumor-associated macrophages (TAMs) are recently verified to facilitate gemcitabine resistance. However, the effect of CAFs in regulating TAMs function in pancreatic cancer (PCa) remains unclear. Here, primary CAFs were extracted from tumor tissues of PCa patients, and CAFs-derived exosomes (CAFs-Exo) were acquired and authenticated by transmission electron microscopy, qNano, and western blot analysis. The role of exosomal miRNA-320a in facilitating macrophage M2 polarization was investigated in vitro. We found that CAFs-derived conditioned medium (CM) possessed a higher potential to promote macrophage M2 polarization compared with normal fibroblasts (NFs) or PCa cell-derived CM. Furthermore, CAFs-Exo treatment polarized macrophage to M2 phenotype. miRNA-320a levels were remarkably increased in CAFs-Exo versus NFs-Exo. More important, miRNA-320a could be transferred from CAFs to macrophages through exosomes, and miRNA-320a overexpression in macrophages facilitated its M2 polarization. Functionally, miRNA-320a-overexpressed macrophages facilitated PCa cell proliferation and invasion. CAFs pretreated with miRNA-320a inhibitor reduced miRNA-320a expression in CAFs-Exo and led to decreased M2 macrophage polarization. Finally, we verified that miRNA-320a polarized macrophage to M2 phenotype by regulating PTEN/PI3Kγ signaling. Taken together, the current data demonstrated that CAFs-derived exosomal miRNA-320a facilitated macrophage M2 polarization to accelerate malignant behavior of PCa cells.

IntroductionCowden syndrome is a rare autosomal dominant genetic disease associated with PTEN mutation and is mainly shown as systemic multisystem lesions. The incidence of adenocarcinoma of the duodenum with Cowden syndrome in Asian males is rare. We hereby describe the diagnosis, treatment, and prognosis of a patient with duodenal carcinoma and Cowden syndrome.Case DescriptionA 40-year-old Chinese man was hospitalized because of gastrointestinal hemorrhage and anemia due to infiltrating adenocarcinoma of the descending part of the duodenum. He also had typical signs of Cowden syndrome, such as multiple polyps of the gastrointestinal tract, macrocephaly, papilloma of the tongue, soles hyperkeratosis, and melanosis spots. After the pancreaticoduodenectomy (classic Whipple), the lesions revealed the presence of hamartomatoid polyps, and some of them mutated into non-mucinous adenocarcinoma (80%) and mucinous adenocarcinoma (20%). Further investigation showed a lack of PTEN protein expression in the duodenal neoplasm, and genetic analysis showed the mutation of p.E242fs in PTEN. The patient was followed up for 1 year. There was no appearance of recurrence or distant metastasis.ConclusionIt is suggested that we should pay more attention to the differential diagnosis of duodenal carcinoma combined with gastrointestinal polyps. If multiple gastrointestinal polyps with gastrointestinal bleeding are encountered, Cowden syndrome should be considered, and timely diagnosis and treatment should be implemented.

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