Gastric cancer (GC) is one of the leading causes of cancer-related death in both men and women due to delayed diagnosis and high metastatic frequency. Extracellular vesicles (EVs) are membrane-bound nanovesicles which are released by cells into body fluids such as plasma, saliva, breast milk, cerebrospinal fluid, semen, urine, lymphatic fluid, amniotic fluid, sputum and synovial fluid. EVs deliver almost all types of biomolecules such as proteins, nucleic acids, metabolites, and even pharmacological compounds. These bioactive molecules can be delivered to recipient cells to influence their biological properties, modify surrounding microenvironment and distant targets. The extensive exploration of EVs enhances our comprehension of GC biology referring to tumor growth, metastasis, immune response and evasion, chemoresistance and treatment. In this review, we will sum up the effects of GC-derived EVs to the tumor microenvironment. Moreover, we will also summarize the function of microenvironment-derived EVs in GC and discuss how the bidirectional communication between tumor and microenvironment affect GC growth, metastatic behavior, immune response, and drug resistance. At last, we prospect the clinical application viewpoint of EVs in GC.

Therapeutic, III.

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BackgroundThis study was carried out to determine the prognostic significance of preoperative peripheral epithelial cell adhesion molecule- positive (EpCAM+) circulating tumor cell (CTC) and T regulatory (Treg) cell levels in hepatocellular carcinoma (HCC) patients for the prediction of postoperative recurrence following curative resection.MethodsA total of 49 patients about to undergo curative resection for HCC were recruited into the study. PCR and FACS were used to detect the preoperative levels of EpCAMmRNA+ CTCs and CD4+CD25+Foxp3+ Treg cells. The prognostic value of EpCAMmRNA+ CTCs, CD4+CD25+Foxp3+ Treg cells, and other clinicopathological factors were analyzed by applying the Kaplan–Meier method and the multivariate Cox proportional hazards model.ResultsThe number of EpCAMmRNA+ CTCs and Treg/CD4+ cells showed significant correlation as prognostic factors of postoperative HCC recurrence: EpCAMmRNA+ CTC ≥ 2.22 (P = 0.001) and Treg/CD4+ ≥ 5.07 (P = 0.045), with EpCAMmRNA+ CTC ≥ 2.22 (P = 0.003, HR = 6.668) being the most important indicator. Patients with high CTC/Treg levels showed a significantly higher risk of developing postoperative HCC recurrence than those with low CTC/Treg levels (66.7 % vs. 10.3 %, P < 0.001). The high CTC/low Treg group also presented higher 1-year recurrence rates compared with the low CTC/low Treg level group (50.0 % vs. 10.3 %, P = 0.004).ConclusionsElevated EpCAMmRNA+ CTC and Treg/CD4+ levels were associated with early recurrence of HCC, indicative of poor clinical outcome. The combined detection of EpCAMmRNA+ CTC and Treg/CD4+ may therefore provide a novel prognostic predictor for HCC patients.Electronic supplementary materialThe online version of this article (doi:10.1186/s12885-016-2526-4) contains supplementary material, which is available to authorized users.