Circulating miRNAs (cirmiRNAs) can be packaged into the exosomes, participating in intercellular communication, which affects the malignant progression and therapy resistance of triple‐negative breast cancer (TNBC). Currently, immune checkpoint inhibitors that regulate T‐cell function, especially antibodies against programmed cell death 1 (PD‐1) or its ligand PD‐L1, are emerging as new promising therapy for TNBC patients. However, only very limited patients showed complete or partial response to anti‐PD‐1 treatment. Dysfunction of CD8⁺ T cells is one of the key reasons for the immune escape of TNBC. The regulation of exosome‐derived cirmiRNAs on CD8⁺ T cells in TNBC deserves more investigation. Here, the cirmiR‐20a‐5p level was significantly upregulated in the plasma of TNBC patients and culture supernatant of TNBC cells. High abundance of cirmiR‐20a‐5p was correlated with a worse prognosis of TNBC. cirmiR‐20a‐5p was secreted in the form of exosomes by TNBC cells. Exosomal cirmiR‐20a‐5p was internalized into CD8⁺ T cells and resulted into the dysfunction of CD8⁺ T. A mechanism study uncovered that cirmiR‐20a‐5p targeted the nuclear protein ataxia‐telangiectasia (NPAT) and decreased NPAT expression in CD8⁺ T cells. An in vivo xenograft mouse model showed that cirmiR‐20a‐5p conferred TNBC to anti‐PD‐1 treatment resistance. Collectively, these findings indicated that cirmiR‐20a‐5p released by TNBC cells via exosome promotes cancer cell growth and leads to the immunosuppression by inducing CD8⁺ T cell dysfunction. This study suggests that targeting cirmiR‐20a‐5p might be a novel strategy for overcoming the resistance of TNBC to anti‐PD‐1 immunotherapy.

The problems of tuberculosis (TB) and its drug resistances are very severe in China. New therapeutic agents or regimens to treat multi‐drug‐resistant tuberculosis (MDR‐TB) are urgently needed. We studied the effects of Ag85A DNA vaccine alone or in combination with rifampin (RFP) or pyrazinamide (PZA) for the treatment of MDR‐TB in mice. Ag85A DNA vaccine significantly increased the production of IFN‐γ, but lowered the production of IL‐4. Seventy female BALB/c mice infected with Mycobacterium tuberculosis clinical isolate HB361, which was resistant to RFP and isoniazid but sensitive to PZA, were treated with plasmid pVAX1, RFP, PZA, M. vaccae vaccine, Ag85A DNA, Ag85A DNA combined with RFP or PZA, respectively. Ag85A DNA vaccine alone or in combination with RFP or PZA reduced the pulmonary and splenic bacterial loads by 1.03–1.38 logs, respectively. Ag85A DNA combined with conventional chemotherapy for the treatment of MDR‐TB might result in cure of MDR‐TB in developing countries.

Triple-negative breast cancer shows worse outcome compared with other subtypes of breast cancer. The discovery of dysregulated microRNAs and their roles in the progression of triple-negative breast cancer provide novel strategies for the treatment of patients with triple-negative breast cancer. In this study, we identified the significant reduction of miR-133 in triple-negative breast cancer tissues and cell lines. Ectopic overexpression of miR-133 suppressed the proliferation, colony formation, and upregulated the apoptosis of triple-negative breast cancer cells. Mechanism study revealed that the YES Proto-Oncogene 1 was a target of miR-133. miR-133 bound the 3′-untranslated region of YES Proto-Oncogene 1 and decreased the level of YES Proto-Oncogene 1 in triple-negative breast cancer cells. Consistent with miR-133 downregulation, YES1 was significantly increased in triple-negative breast cancer, which was inversely correlated with the level of miR-133. Restoration of YES Proto-Oncogene 1 attenuated the inhibitory effects of miR-133 on the proliferation and colony formation of triple-negative breast cancer cells. Consistent with the decreased expression of YES Proto-Oncogene 1, overexpression of miR-133 suppressed the phosphorylation of YAP1 in triple-negative breast cancer cells. Our results provided novel evidence for the role of miR-133/YES1 axis in the development of triple-negative breast cancer, which indicated miR-133 might be a potential therapeutic strategy for triple-negative breast cancer.

Background: Osteosarcoma (OS) is the leading cancer-associated mortality in childhood and adolescence. Increasing evidence has demonstrated the key function of microRNAs (miRNAs) in OS development and chemoresistance. Among them, miRNA-605-3p acted as an important tumor suppressor and was frequently down-regulated in multiple cancers. However, the function of miR-650-3p in OS has not been reported. Objective: The aim of this work is to explore the novel role of miR-605-3p in osteosarcoma and its possible involvement in OS chemotherapy resistance. Methods: The expression levels of miR-605-3p in OS tissues and cells were assessed by reverse transcription quantitative PCR (RT-qPCR). The relevance of miR-605-3p with the prognosis of OS patients was determined by the Kaplan-Meier analysis. Additionally, the influence of miR-605-3p on OS cell growth was analyzed using the cell counting kit-8, colony formation assay, and flow cytometry. The mRNA and protein expression of RAF1 were detected by RT-qPCR and western blot. The binding of miR-605-3p with the 3’-UTR of RAF1 was confirmed by dual-luciferase reporter assay. Results: Our results showed that miR-605-3p was markedly decreased in OS tissues and cells. A lower level of miR-605-3p was strongly correlated with lymph node metastasis and poor 5-year overall survival rate of OS patients. In vitro assay found that miR-605-3p suppressed OS cell proliferation and promoted cell apoptosis. Mechanistically, the proto-oncogene RAF1 was seen as a target of miR-605-3p and strongly suppressed by miR-605-3p in OS cells. Restoration of RAF1 markedly eliminated the inhibitory effect of miR-605-3p on OS progression, suggesting RAF1 as a key mediator of miR-605-3p. Consistent with the decreased level of RAF1, miR-605-3p suppressed the activation of both MEK and ERK in OS cells, which are the targets of RAF1. Moreover, lower levels of miR-605-3p were found in chemoresistant OS patients, and downregulated miR-605-3p increased the resistance of OS cells to therapeutic agents. Conclusion: Our data revealed that miR-605-3p serves as a tumor suppressor gene by regulating RAF1 and increasing the chemosensitivity of OS cells, which provided the novel working mechanism of miR-605-3p in OS. Engineering stable nanovesicles that could efficiently deliver miR-605-3p with therapeutic activity into tumors could be a promising therapeutic approach for the treatment of OS.

Triple negative breast cancer (TNBC) is an aggressive breast cancer subtype characterized with poor prognosis and high metastatic potential. Although traditional chemotherapy, radiation, and surgical resection remain the standard treatment options for TNBC, bispecific antibody-based immunotherapy is emerging as new strategy in TNBC treatment. Here, we found that the receptor tyrosine kinase-like Orphan Receptor 1 (ROR1) was highly expressed in TNBC but minimally expressed in normal tissue. A bispecific ROR1-targeted CD3 T cell engager (TCE) was designed in IgG-based format with extended half-life. The expression of ROR1 in TNBC was detected by RT-qPCR and immunohistology analysis. The killing of ROR1/CD3 antibody on TNBC cells was determined by the in vitro cytotoxicity assay and in vivo PBMC reconstituted mouse model. The activation of ROR1/CD3 on T cells was analyzed by the flow cytometry and ELISA assay. Pharmacokinetics study of ROR1/CD3 was performed in mouse. The ROR1/CD3 TCE triggered T cell activation and proliferation, which showed potent and specific killing to TNBC cells in ROR1-depedent manner. In vivo mouse model indicated that ROR1/CD3 TCE redirected the cytotoxic activity of T cells to lyse TNBC cells and induced significant tumor regression. Additionally, the ROR1/CD3 bispecific antibody exhibited an extended half-life in mouse, which may enable intermittent administration in clinic. Collectively, these results demonstrated that ROR1/CD3 TCE has a promising efficacy profile in preclinical studies, which suggested it as a possible option for the treatment of ROR1-expressing TNBC.