Tingting Cai

Abstract Recent studies have shown that extracellular microRNAs are not only potential biomarkers but are also involved in cell interactions to regulate the intercommunication between cancer cells and their microenvironments in various types of malignancies. In this study, we isolated exosomes from nasopharyngeal carcinoma ( NPC ) cell lines and patient sera (T‐ EXOs ), or control NP69 cells and healthy donor sera ( HD‐EXOs ). We found that miR ‐24‐3p was markedly enriched in T‐ EXOs as compared with HD‐EXOs ; the serum exosomal miR ‐24‐3p level was correlated with worse disease‐free survival of patients ( p < 0.05). Knockdown of exosomal miR ‐24‐3p ( miR ‐24‐3p‐sponge‐T‐ EXOs ) by a sponge RNA targeting miR ‐24‐3p restored the T‐ EXO ‐mediated (control‐sponge‐T‐ EXO ) inhibition of T‐cell proliferation and Th1 and Th17 differentiation, and the induction of regulatory T cells (Tregs). Mechanistic analyses revealed that administration of exosomal miR ‐24‐3p increased P‐ ERK , P‐ STAT1 and P‐ STAT3 expression while decreasing P‐ STAT5 expression during T‐cell proliferation and differentiation. Moreover, by in vivo and in vitro assessments, we found FGF11 to be a direct target of miR ‐24‐3p. However, both miR ‐24‐3p‐sponge‐T‐ EXOs and T‐ EXOs (control‐sponge‐T‐ EXOs ) impeded proliferation and Th1 and Th17 differentiation, but induced Treg differentiation, of lenti‐ shFGF11 ‐transfected T cells. The levels of phosphorylated ERK and STAT proteins were different in lenti‐ ScshRNA ‐transfected T cells and lenti‐ shFGF11 ‐transfected T cells following administration of miR ‐24‐3p‐sponge‐T‐ EXO . Interestingly, tumour FGF11 expression was positively correlated with the number of CD4 + and CD8 + T cells in vivo , and predicted favourable patient DFS ( p < 0.05). Additionally, hypoxia increased cellular and exosomal miR ‐24‐3p levels and enhanced the inhibitory effect of T‐ EXO on T‐cell proliferation and differentiation. Collectively, our findings suggest that exosomal miR ‐24‐3p is involved in tumour pathogenesis by mediating T‐cell suppression via repression of FGF11 , and may serve as a potential prognostic biomarker in NPC . Copyright © 2016 Pathological Society of Great Britain and Ireland. Published by John Wiley & Sons, Ltd.

In addition to the role of programmed cell death ligand 1 (PD-L1) in facilitating tumour cells escape from immune surveillance, it is considered as a crucial effector in transducing intrinsic signals to promote tumour development. Our previous study has pointed out that PD-L1 promotes non-small cell lung cancer (NSCLC) cell proliferation, but the mechanism remains elusive. Here we first demonstrated that PD-L1 expression levels were positively correlated with p-MerTK levels in patient samples and NSCLC cell lines. In addition, PD-L1 knockdown led to the reduced phosphorylation level of MerTK in vitro. We next showed that PD-L1 regulated NSCLC cell proliferation via Gas6/MerTK signaling pathway in vitro and in vivo. To investigate the underlying mechanism, we unexpectedly found that PD-L1 translocated into the nucleus of cancer cells which was facilitated through the binding of Karyopherin β1 (KPNB1). Nuclear PD-L1 (nPD-L1), coupled with transcription factor Sp1, regulated the synthesis of Gas6 mRNA and promoted Gas6 secretion to activate MerTK signaling pathway. Taken together, our results shed light on the novel role of nPD-L1 in NSCLC cell proliferation and reveal a new molecular mechanism underlying nPD-L1-mediated Gas6/MerTK signaling activation. All above findings provide the possible combinational implications for PD-L1 targeted immunotherapy in the clinic.

BACKGROUND: Acquired epidermal growth factor receptor tyrosine kinase inhibitor (EGFR-TKI) resistance limits the long-term clinical efficacy of tyrosine kinase-targeting drugs. Although most of the mechanisms of acquired EGFR-TKI resistance have been revealed, the mechanism of ~ 15% of cases has not yet been elucidated. METHODS: Cell viability was analysed using the Cell Counting Kit-8 (CCK-8) assay. Proteome profiler array analysis was performed to find proteins contributing to acquired EGFR-TKI resistance. Secreted OPN was detected by ELISA. Immunohistochemical analysis was conducted to detect expression of integrin αV in NSCLC tissue. The effect of VS-6063 on apoptosis and proliferation of PC9 gefitinib-resistant cells was detected by fluorescence-activated cell sorting (FACS) and clonogenic assays. A mouse xenograft model was used to assess the effect of VS-6063 on the sensitivity of PC9 gefitinib-resistant cells to gefitinib. RESULTS: OPN was overexpressed in acquired EGFR-TKI-resistant NSCLCs. Secreted OPN contributed to acquired EGFR-TKI resistance by activating the integrin αVβ3/FAK pathway. Inhibition of FAK signalling increased sensitivity to EGFR-TKIs in PC9 gefitinib-resistant cells both in vitro and in vivo. CONCLUSIONS: OPN contributes to acquired EGFR-TKI resistance by up-regulating expression of integrin αVβ3, which activates the downstream FAK/AKT and ERK signalling pathways to promote cell proliferation in NSCLC.

BACKGROUND: Tetraspanins CD151, a transmembrane 4 superfamily protein, has been identified participating in the initiation of a variety of cancers. However, the precise function of CD151 in non-small cell lung cancer (NSCLC) remains unclear. Here, we addressed the pro-tumoral role of CD151 in NSCLC by targeting EGFR/ErbB2 which favors tumor proliferation, migration and invasion. METHODS: First, the mRNA expression levels of CD151 in NSCLC tissues and cell lines were measured by RT-PCR. Meanwhile, CD151 and its associated proteins were analyzed by western blotting. The expression levels of CD151 in NSCLC samples and its paired adjacent lung tissues were then verified by Immunohistochemistry. The protein interactions are evaluated by co-immunoprecipitation. Flow cytometry was applied to cell cycle analysis. CCK-8, EdU Incorporation, and clonogenic assays were used to analyze cell viability. Wound healing, transwell migration, and matrigel invasion assays were utilized to assess the motility of tumor cells. To investigate the role of CD151 in vivo, lung carcinoma xenograft mouse model was applied. RESULTS: High CD151 expression was identified in NSCLC tissues and cell lines, and its high expression was significantly associated with poor prognosis of NSCLC patients. Further, knockdown of CD151 in vitro inhibited tumor proliferation, migration, and invasion. Besides, inoculation of nude mice with CD151-overexpressing tumor cells exhibited substantial tumor proliferation compared to that in control mice which inoculated with vector-transfected tumor cells. Noteworthy, we found that overexpression of CD151 conferred cell migration and invasion by interacting with integrins. We next sought to demonstrate that CD151 regulated downstream signaling pathways via activation of EGFR/ErbB2 in NSCLC cells. Therefore, we infer that CD151 probably affects the sensitivity of NSCLC in response to anti-cancer drugs. CONCLUSIONS: Based on these results, we demonstrated a new mechanism of CD151-mediated tumor progression by targeting EGFR/ErbB2 signaling pathway, by which CD151 promotes NSCLC proliferation, migration, and invasion, which may considered as a potential target of NSCLC treatment.