Pancreatic cancer (PC) is a highly malignant tumor with increased morbidity and mortality, which is difficult to diagnose and cure in the clinic. Through secreting exosomes containing biological molecules, including diverse RNAs and proteins, bone marrow mesenchymal stem cells (BM‐MSCs) influence the immunity, inflammation, tumor environment, and cancer metastasis. In this study, low expression of miRNA‐1231 (miR‐1231) in exosomes derived from the peripheral blood was significantly correlated with the TNM stage of PC, suggesting the potential inhibitory effect of exosomal miR‐1231 on PC occurrence and development. The proliferation, migration, invasion, and adhesion to the matrix of PC cells BxPC‐3 and PANC‐1 were negatively regulated by exosomes derived from the supernatants of BM‐MSCs that transfected with miR‐1231 oligonucleotides. Simultaneously, tumor growth in vivo was seriously restrained in BALB/C nude mice by tail vein injection with exosomes originated from BM‐MSCs that transfected with miR‐1231 mimics. The exosomes extracted from BM‐MSCs with high level of miR‐1231 inhibit the activity of PC, providing the potential application for developing new and efficient medicine for cancer therapy, especially for PC treatment. The exosomal miR‐1231 of peripheral blood may also be a potential indicator for PC diagnosis in the future.

Worldwide, gastric cancer (GC) is one of the deadliest malignant tumors of the digestive system. Moreover, microRNAs (miRNAs) of exosomes harbored within cancer cells have been determined to induce inflammatory conditions that accelerate tumor growth and metastasis. Interestingly, the oncogenic role of bone marrow mesenchymal stem cells (BM-MSCs) in the modulation of immunosuppression, tumor invasion, and metastasis was discovered to be partly mediated through the secretion of exosomes. In this article, high expression of miRNA-221 (miR-221) in exosomes of the peripheral blood was determined to be positively correlated with the poor clinical prognosis of GC, especially with respect to tumor, node, and metastases stage. Therefore, the expression of miR-221 in exosomes of the peripheral blood may be an important detection index for GC. Proliferation, migration, invasion, and adhesion to the matrix of GC BGC-823 and SGC-7901 cells were significantly enhanced by exosomes that originated from BM-MSCs that were transfected with miR-221 mimics. In conclusion, extracted exosomes from BM-MSCs transfected with miR-221 oligonucleotides can act as high-efficiency nanocarriers, which can provide sufficient miR-221 oligonucleotides to influence the tumor microenvironment and tumor aggressiveness effectively. Notably, the use of a miR-221 inhibitor with an excellent restraining effect in exosomes provides therapeutic potential for GC in future clinical medicine.

Introduction: Primary gastric diffuse large B-cell lymphoma (GDLBCL) is a heterogeneous disease in clinicopathological features and prognosis. Programmed death ligand-1 (PD-L1) and microRNA-34a (miR-34a) play crucial roles in GDLBCL progress. The purpose of this research is to explore the clinical significance of PD-L1 and miR-34a expression in GDLBCL. Patients and Methods: The expressions of PD-L1 and miR-34a were examined by IHC and qRT-PCR in 109 patients who were diagnosed with GDLBCL and were treated with rituximab plus cyclophosphamide, doxorubicin, prednisone vincristine and prednisone chemotherapy (R-CHOP) from January 2010 to December 2018. Results: PD-L1 level was significantly higher in tumor tissues than adjacent non-tumor tissues (60.5%, P<0.001), while the miR-34a level was just reversed (50.5%, P<0.001), which was negatively correlated (r=−0.524, P<0.001). Notably, PD-L1-positive and miR-34a-negative expressions were significantly correlated with the advanced Lugano stage of IIE-IV stage (P<0.001 and P<0.01), elevated serumal LDH levels (P<0.001 and P<0.05), B symptoms present (P<0.001 and P<0.001), non-GCB subtype (P<0.001 and P<0.001) and negative Bcl-2 expression (P<0.05 and P<0.001). PD-L1 high and miR-34a low expression groups had more patients with IPI scores of 2 or greater (P<0.001 and P<0.05) and poor R-IPI (P<0.01 and P<0.01). The complete response rate was upregulated in patients with negative PD-L1 and positive miR-34a expression after R-CHOP treatment. Discussion: PD-L1 expression and miR-34a expression were significantly associated with clinicopathological characteristics and survival prognosis; they may serve as novel prognostic markers in GDLBCL patients who were treated with R-CHOP. Immunotherapies targeting PD-L1 and miR-34a pathway may have therapeutic potential in GDLBCL.

Gastric diffuse large B-cell lymphoma (GDLBCL) is a common disease with an increasing incidence. However, the regulatory effect of exosomal programmed death-ligand 1 (PD-L1) on the immune microenvironment in GDLBCL is unclear. In the present study, the protein expression levels of exosomal PD-L1 in the supernatants of cultured diffuse large B-cell lymphoma (DLBCL) cells and the plasma of patients with GDLBCL was assessed using immunoblotting. Exosomes derived from DLBCL cells were cocultured with T lymphocytes or injected into tumor xenograft mice by tail vein injection. The relationship between the protein expression level of exosomal PD-L1 in the plasma and the clinical characteristics and immune microenvironmental parameters of GDLBCL was evaluated using immunoblotting and immunohistochemistry. High levels of exosomal PD-L1 were found in the supernatants of cultured DLBCL cells. Exosomes with high levels of PD-L1 promoted growth of tumors formed by DLBCL cells in vivo and inhibited the proliferation of T lymphocytes. Notably, the protein expression level of PD-L1 in plasma exosomes derived from GDLBCL patients was significantly higher than that of healthy individuals. High levels of PD-L1 in plasma exosomes were significantly associated with international prognostic index score, pathological type and advanced Lugano stage, which might lead to the poor prognosis of GDLBCL. Moreover, a high level of PD-L1 in plasma exosomes was significantly associated with an immunosuppressive microenvironment in GDLBCL. Therefore, the results of the present study indicated that exosomal PD-L1 inhibited the proliferation of T lymphocytes and promoted the formation of an immunosuppressive microenvironment in GDLBCL. High expression of exosomal PD-L1 may suggest a poor prognosis of GDLBCL, and exosomal PD-L1 in plasma may be a new diagnostic indicator for GDLBCL.