Background: Although gemcitabine-based chemotherapy has been established as a core multimodal therapy for non-small cell lung cancer (NSCLC) treatment, its clinical efficacy remains limited by the development of acquired resistance following tumor metastasis and relapse. In this study, we investigated how gemcitabine-resistant (GR) cells contribute to the development of NSCLC tumor malignancy via exosome-mediated transfer of microRNAs. Methods: We first studied the mechanism of exosome internalization via PKH-67 staining and an immunofluorescence assay, then confirmed our finding by transmission electron microscopy and western blot analysis. Candidate miRNAs were identified through microarray analysis. Thereafter, RT-PCR, MTS, Transwell and soft agar assays were performed to assess the role of exosomic miR-222-3p in vitro. A 3’ untranslated region reporter assay was applied to identify the target of miR-222-3p. A lung metastasis mouse model was constructed to evaluate tumor growth and metastasis in vivo. Finally, clinical samples were used for correlation analysis between exosomic miR-222-3p levels and patients’ response to gemcitabine. Results: A549-GR–derived exosomes were internalized by receipt cells via caveolin- and lipid raft-dependent endocytosis, which allowed the transfer of miR-222-3p. Exosomic miR-222-3p enhanced the proliferation, gemcitabine resistance, migration, invasion, and anti-anoikis of parental sensitive cells by directly targeting the promoter of SOCS3. In addition, a higher level of exosomic miR-222-3p in sera usually predicted worse prognosis in NSCLC patients. Conclusion: Our data demonstrate that exosomic-miR-222-3p functions as a principal regulator of gemcitabine resistance and malignant characteristics by targeting SOCS3. The exosomic miR-222-3p level in sera may be a potential prognostic biomarker for predicting gemcitabine sensitivity in NSCLC patients.

Ovarian cancer (OVCa) stem cells are associated with tumor growth, metastasis, and recurrence, which are driving forces behind a majority of the OVCa-related mortality. This subpopulation of cancer cells are characterized by uncontrolled proliferation, high invasiveness, and resistance against the current platinum-based therapy. Thus, targeting OVCa cancer stem cells has been focused in recent therapeutic development. Isolation and purification of cancer stem cells are, however, challenging for the lack of sensitive and specific markers. In this study, we demonstrated that miR-551b was upregulated in OVCa stem cells, by using a quantitative PCR array, correlating with the pathological grades of this malignancy. In vitro experiments indicated that miR-551b promoted the proliferation, invasion, and chemoresistance of OVCa cells and cancer stem cells. Further analysis suggested that miR-551b functioned through the suppression of Foxo3 and TRIM31, two important tumor suppressors. In support of this, our in vivo experiments using mouse xenograft models showed that inhibiting miR-551b significantly increased the susceptibility of OVCa cells to cisplatin and prolonged the survival of the host mice. In conclusion, our study suggested miR-551b as a potential biomarker for OVCa stem cells and explored its functional mechanism, providing a potential therapeutic target for future drug development.

Background: Radiation exerts direct antitumor effects and is widely used in clinics, but the efficacy is severely compromised by tumor resistance. Therefore uncovering the mechanism of radioresistance might promote the development of new strategies to overcome radioresistance by manipulating activity of the key molecules. Methods: Immunohistochemistry were used to find whether mTOR were over-activated in radioresistant patients’ biopsies. Then Western blot, real-time PCR and transfection were used to find whether radiotherapy regulates the expression and activity of mTOR by modulating its targeting microRNA in human pancreatic cancer cell lines PANC-1, Capan-2 and BxPC-3. Finally efficacy of radiation combined with mTOR dual inhibitor AZD8055 was assessed in vitro and in vivo. Results: Ionizing radiation promoted mTOR expression and activation in pancreatic cancer cells through reducing miR-99b expression, which negatively regulated mTOR. Novel mTOR inhibitor, AZD8055 (10 nM, 100 nM, 500 nM) synergistically promoted radiation (0–10 Gy) induced cell growth inhibition and apoptosis. In human pancreatic cancer xenografts, fractionated radiation combined with AZD8055 treatment further increased the anti-tumor effect, the tumor volume was shrinked to 278 mm³ after combination treatment for 3 weeks compared with single radiation (678 mm³) or AZD8055 (708 mm³) treatment (P < 0.01). Conclusions: Our data provide a rationale for overcoming radio-resistance by combined with mTOR inhibitor AZD8055 in pancreatic cancer therapy.

Although it is well known that exaggerated proliferation, metastasis and the mesenchymal subtype is related with worst prognoses in glioblastoma (GBM) and that transforming growth factor-β1 (TGF-β1) is a potent factor in regulating the proliferation, migration and epithelial-mesenchymal transition (EMT) phenotype of GBM, the detailed mechanisms are still far from elucidated. MicroRNAs (miRNAs) are small non-coding RNAs which play critical roles in various diseases by regulating target gene expression. We report that miR-10b, a molecule downstream of TGF-β1, is involved in TGF-β1-regulated GBM cell proliferation, migration and EMT. We found that exposure of GBM cells to TGF-β1 significantly upregulated miR-10b expression. Overexpression of miR-10b promotes GBM cell proliferation, migration and EMT, whereas depletion of miR-10b obtained reverse effects. Further studies uncovered that some tumor-associated genes including epithelial cadherin (E-cadherin), apoptotic protease activating factor 1 (Apaf-1) and phosphatase and tensin homolog (PTEN) are target genes of miR-10b. In human GBM xenografts, antagomiR directed against miR-10b markedly suppressed tumor growth, and the tumor volume shrunk from 1252.5±285 to 873.4±205 mm3 after antagomiR‑10b treatment for 3 weeks compared with the control group (P<0.01). Taken together, our data collectively demonstrate that the proliferation, migration and EMT features of GBM cells can be regulated by TGF-β1 stimulation through controlling miR-10b. Thus, our findings provide a rationale for targeting TGF-β1 or miR-10b for the treatment of GBM.

MiR-216a-5p has opposite effects on tumorigenesis and progression in the context of different tumors, acting as either a tumor suppressor or an oncogene. However, the expression and function of miR-216a-5p in pancreatic cancer (PC) is not well characterized.

The mammalian target of rapamycin (mTOR) is dysregulated in diverse cancers and contributes to tumor progression and drug resistance. The first generation of mTOR inhibitors have failed to show clinical efficiency in treating pancreatic cancers due in part to the feedback relief of the insulin-like growth factor-1 receptor (IGF-1R)-AKT signaling pathway. The second generation of mTOR inhibitors, such as AZD8055, could inhibit AKT activation upon mTOR complex 2 (mTORC2) inhibition. However, whether this generation of mTOR inhibitors can obtain satisfactory activities in pancreatic cancer therapy remains unclear. In this study, we found AZD8055 did not show great improvement compared with everolimus, AZD8055 induced a temporal inhibition of AKT kinase activities and AKT was then rephosphorylated. Additionally, we found that AZD8055-induced transient AKT inhibition increased the expression and activation of epidermal growth factor receptor (EGFR) by releasing its transcriptional factors Fork-head box O 1/3a (FoxO1/3a), which might contribute to cell resistance to AZD8055. The in vitro and in vivo experiments further indicated the combination of AZD8055 and erlotinib synergistically inhibited the mTORC1/C2 signaling pathway, EGFR/AKT feedback activation, and cell growth, as well as suppressed the progression of pancreatic cancer in a xenograft model. This study provides a rationale and strategy for overcoming AZD8055 resistance by a combined treatment with the EGFR inhibitor erlotinib in pancreatic cancer therapy.