Yunzhong Nie

Ovarian tumor-associated microRNA-20a decreases natural killer cell cytotoxicity by downregulating MICA/B expression

MicroRNAs (miRNAs) are a class of small non-coding regulatory RNAs, and changes in miRNAs are involved in tumor origin and progression. Studies have shown that miR-20a is overexpressed in human ovarian cancer tissues and that this miRNA enhances long-term cellular proliferation and invasion capabilities. In this study, a positive correlation between serum miR-20a expression and ovarian cancer stage was observed. We found that miR-20a binds directly to the 3′-untranslated region of MICA/B mRNA, resulting in its degradation and reducing its protein levels on the plasma membrane. Reduction of membrane-bound MICA/B proteins, which are ligands of the natural killer group 2 member D (NKG2D) receptor found on natural killer (NK) cells, γδ+ T cells and CD8+ T cells, allows tumor cells to evade immune-mediated killing. Notably, antagonizing miR-20a action enhanced the NKG2D-mediated killing of tumor cells in both in vitro and in vivo models of tumors. Taken together, our data indicate that increased levels of miR-20a in tumor cells may indirectly suppress NK cell cytotoxicity by downregulating MICA/B expression. These data provide a potential link between metastasis capability and immune escape of tumor cells from NK cells.

Increased frequencies of T helper type 17 cells in tuberculous pleural effusion.

Th17 cells have emerged as an important mediator in inflammatory and autoimmune diseases. Recent studies suggest a potential impact of Th17 cells on tuberculosis (TB) infection. This study was designed to investigate the possible involvement of Th17 cells in tuberculous pleural effusion. Compared with healthy volunteers, patients with TB had a higher proportion of Th17 cells in peripheral blood mononuclear cells (PBMCs). Moreover, the percentage of Th17 cells in pleural effusions of TB patients was obviously higher than that in PBMC from TB patients or healthy controls. Furthermore, the mRNA and protein expression levels of IL-17 and IL-6 were significantly increased in the patients with tuberculous pleural effusion, while expression level of TGF-β was decreased in the pleural effusion. Correlation analysis showed a significant correlation between IFN-γ concentrations and the frequencies of Th17 cells in tuberculous pleural effusion. These results indicate that Th17 cells may contribute to the immunopathogenesis of tuberculous pleural effusion.

ERβ-Mediated Estradiol Enhances Epithelial Mesenchymal Transition of Lung Adenocarcinoma through Increasing Transcription of Midkine

Epithelial-mesenchymal transition (EMT) plays a specific role in the migration of tumor cells. Both estrogen and midkine (MK) have been thought to be important factors in promoting the progression of non-small-cell lung cancer (NSCLC) and can enhance EMT. Some evidence indicated the correlation between estradiol (E2) and MK, but the precise mechanism on their interreaction is unknown. Here, we try to clarify whether and how E2 regulates MK expression to promote EMT. We found that E2 increased MK mRNA expression in lung adenocarcinoma cells LTEP-a2 and A549 in a time-dependent manner. E2-induced MK expression was inhibited by the estrogen receptor (ER) antagonist ICI 182,780 and tamoxifen but not by phosphoinositide-3 kinase and MAPK inhibitors, suggesting a genomic mechanism of E2 on the regulation of MK transcription. Moreover, luciferase reporter and chromatin immunoprecipitation assays exhibited that E2 induced ERβ recruitment to the estrogen response element in the MK promoter. Small interfering RNA to ERα and ERβ revealed that ERβ mainly mediated E2-induced MK transcription. Interestingly, E2 enhanced MK expression in accordance with increase of EMT, whereas knockdown of MK could block EMT under E2 stimulation. Importantly, through analyzing lung adenocarcinoma tissues, there was indeed a correlation among levels of E2, MK, and EMT-related protein expression. Taken together, we reported a previously unrecognized mechanism on E2 in the regulation of MK expression and proved that MK plays a pivotal role in progression of E2-regulated EMT.

Involvement of midkine expression in the inhibitory effects of low-frequency magnetic fields on cancer cells.

Effects of magnetic fields (MFs) on cancer cells may depend on cell type and exposure conditions. Gene expression levels are different among cancer cells. However, the effect of MFs on cancer cells with different gene expressions is still unclear. In this study, the cancer cell lines BGC-823, MKN-45, MKN-28, A549, SPC-A1, and LOVO were exposed to a low-frequency MF. Specific parameters of MFs were determined. Furthermore, the potential of the MF to influence cancer cell growth with midkine (MK) expression was evaluated. Cell proliferation and cell cycle were detected using the CCK-8 assay and flow cytometry. Cell ultrastructure was observed by transmission electron microscopy. BGC-823 cells with over-expression of MK (BGC-MK cells) and stanniocalcin-1 were generated by plasmid construction and transfection. Results showed that exposure to a 0.4-T, 7.5 Hz MF inhibited the proliferation of BGC-823, MKN-28, A549, and LOVO cells, but not MKN-45 and SPC-A1 cells. Moreover, the inhibitory effect of the MF on BGC-MK cells was lower (12.3%) than that of BGC-823 cells (20.3%). Analysis of the cell cycle showed that exposure to the MF led to a significant increase in the S phase in BGC-823 cells, but not in BGC-MK cells. In addition, organelle morphology was modified in BGC-823 cells exposed to the MF. These results suggest that exposure to a 0.4-T, 7.5 Hz MF could inhibit tumor cell proliferation and disturb the cell cycle. The alteration of MK expression in cancer cells may be related to the inhibitory effect of the MF on these cells.

Cellular reprogramming and hepatocellular carcinoma development

Hepatocellular carcinoma (HCC) is one of the most common cancers, and is also the leading cause of death worldwide. Studies have shown that cellular reprogramming contributes to chemotherapy and/or radiotherapy resistance and the recurrence of cancers. In this article, we summarize and discuss the latest findings in the area of cellular reprogramming in HCC. The aberrant expression of transcription factors OCT4, KLF4, SOX2, c-MYC, NANOG, and LIN28 have been also observed, and the expression of these transcription factors is associated with unfavorable clinical outcomes in HCC. Studies indicate that cellular reprogramming may play a critical role in the occurrence and recurrence of HCC. Recent reports have shown that DNA methylation, miRNAs, tumor microenvironment, and signaling pathways can induce the expression of stemness transcription factors, which leads to cellular reprogramming in HCC. Furthermore, studies indicate that therapies based on cellular reprogramming could revolutionize HCC treatment. Finally, a novel therapeutic concept is discussed: reprogramming control therapy. A potential reprogramming control therapy method could be developed based on the reprogramming demonstrated in HCC studies and applied at two opposing levels: differentiation and reprogramming. Our increasing understanding and control of cellular programming should facilitate the exploitation of this novel therapeutic concept and its application in clinical HCC treatment, which may represent a promising strategy in the future that is not restricted to liver cancer.

Estrogen upregulates MICA/B expression in human non-small cell lung cancer through the regulation of ADAM17

Estrogen is involved in promoting lung cancer cell division and metastasis. MICA and MICB function as ligands for NKG2D, an important immunoreceptor expressed on natural killer (NK) cells. However, whether estrogen regulates MICA/B expression and affects tumor immune escape remains unknown. In this study, we measured the mRNA levels of MICA, MICB and ADAM17in non-small cell lung cancer (NSCLC) cell lines treated with estrogen. Surface expression of MICA/B on LTEP-a2 and A549 was detected using flow cytometry. We demonstrate that both mRNA and secretory protein levels of MICA/B in lung adenocarcinoma cell lines were upregulated by estradiol. Estradiol enhanced the expression of ADAM17, which was associated with the secretion of MICA/B. This secretion of MICA/B downregulated the NKG2D receptor on the surface of NK92 cells and impaired the cytotoxic activity of NK cells. Estradiol enhanced the expression of ADAM17, which was associated with the secretion of MICA/B. Furthermore, a significant correlation between the concentration of estradiol and the expression of MICA was found in tumor tissues of NSCLC patients. Therefore, we conclude that estrogen can regulate the expression and secretion of MICA/B through ADAM17, which helps lung cancer cells escape NKG2D-mediated immune surveillance.

Mesenchymal stem cells-regulated Treg cells suppress colitis-associated colorectal cancer

IntroductionPrevious studies have produced controversial results regarding whether mesenchymal stem cells (MSCs) promote or inhibit tumor development. Given the dual role of MSCs in inflammation and cancer, in this study the colitis-associated colorectal cancer (CAC) model was used to examine whether umbilical cord tissue-derived MSCs could prevent neoplasm by inhibiting chronic inflammation.MethodsMSCs were obtained and identified using flow cytometry. Colitis-associated colorectal cancer model was induced using azoxymethane (AOM) and dextran sulfate sodium (DSS) and MSCs were injected intravenously twice. Levels of immune cells in mesenteric lymph node including regulatory T (Treg) cells were detected using flow cytometry. Naïve T cells and Jurkat cells were co-cultured with MSCs and the effect of MSCs on Treg cells differentiation was evaluated.ResultsAfter injection through tail vein, MSCs could migrate to colon and suppress colitis-related neoplasm. This tumor suppressive effect was characterized by longer colon length, decreased tumor numbers and decreased expression of Ki-67. Moreover, MSCs alleviated the pathology of inflammation in the colitis stage of CAC model and inhibited inflammation cytokines both in colon and serum. Furthermore, Treg cells were accumulated in mesenteric lymph node of MSCs-treated mice while the percentage of T helper cells 2 (Th2) and Th17 were not changed. Of note, MSCs secreted transforming growth factor-β (TGF-β) enhanced the induction of Treg cells from naïve T cells. The conditioned medium of MSCs also activated Smad2 signaling, which has been reported to regulate Treg cells.ConclusionsThese results proved that MSCs could migrate to colon tissues and induce the differentiation of Treg cells via Smad2 as so to inhibit the colitis and suppress the development of CAC.

SapC–DOPS Nanovesicles as Targeted Therapy for Lung Cancer

Lung cancer is the deadliest type of cancer for both men and women. In this study, we evaluate the in vitro and in vivo efficacy of a biotherapeutic agent composed of a lysosomal protein (Saposin C, SapC) and a phospholipid (dioleoylphosphatidylserine, DOPS), which can be assembled into nanovesicles (SapC–DOPS) with selective antitumor activity. SapC–DOPS targets phosphatidylserine, an anionic phospholipid preferentially exposed in the surface of cancer cells and tumor-associated vasculature. Because binding of SapC to phosphatidylserine is favored at acidic pHs, and the latter characterizes the milieu of many solid tumors, we tested the effect of pH on the binding capacity of SapC–DOPS to lung tumor cells. Results showed that SapC–DOPS binding to cancer cells was more pronounced at low pH. Viability assays on a panel of human lung tumor cells showed that SapC–DOPS cytotoxicity was positively correlated with cell surface phosphatidylserine levels, whereas mitochondrial membrane potential measurements were consistent with apoptosis-related cell death. Using a fluorescence tracking method in live mice, we show that SapC–DOPS specifically targets human lung cancer xenografts, and that systemic therapy with SapC–DOPS induces tumor apoptosis and significantly inhibits tumor growth. These results suggest that SapC–DOPS nanovesicles are a promising treatment option for lung cancer. Mol Cancer Ther; 14(2); 491–8. ©2015 AACR.

Midkine upregulates MICA/B expression in human gastric cancer cells and decreases natural killer cell cytotoxicity.

Midkine (MK) is a heparin-binding growth factor overexpressed in various human cancers. In the current study, a positive correlation was observed between MK expression and MICA/B serum levels of gastric cancer patients. In addition, MK transfection significantly increased MICA/B expression in gastric cancer cells. The soluble MICA/B expression was also elevated. Furthermore, MK transfection inhibited CD107a and Granzyme B expression, thereby suppressing the natural killer (NK) cell cytotoxicity in vitro. The phosphorylation of p38 MAPK and its promotion of CHOP expression were also observed after MK treatment and transfection. CHOP was indirectly bound to the MICA/B promoter region by interacting with AP-1, leading to MICA/B transcription. Overall, the current study shows that MK expression in tumor cells indirectly suppresses NK cytotoxicity by inducing MICA/B expression and suppressing NKG2D expression.

Low Frequency Magnetic Fields Enhance Antitumor Immune Response against Mouse H22 Hepatocellular Carcinoma

Objective Many studies have shown that magnetic fields (MF) inhibit tumor growth and influence the function of immune system. However, the effect of MF on mechanism of immunological function in tumor-bearing mice is still unclear. Methods In this study, tumor-bearing mice were prepared by subcutaneously inoculating Balb/c mice with hepatocarcinoma cell line H22. The mice were then exposed to a low frequency MF (0.4 T, 7.5 Hz) for 30 days. Survival rate, tumor growth and the innate and adaptive immune parameters were measured. Results MF treatment could prolong survival time (n = 28, p<0.05) and inhibit tumor growth (n = 9, p<0.01) in tumor-bearing mice. Moreover, this MF suppressed tumor-induced production of cytokines including interleukin-6 (IL-6), granulocyte colony- stimulating factor (G-CSF) and keratinocyte-derived chemokine (KC) (n = 9–10, p<0.05 or 0.01). Furthermore, MF exposure was associated with activation of macrophages and dendritic cells, enhanced profiles of CD4+ T and CD8+ T lymphocytes, the balance of Th17/Treg and reduced inhibitory function of Treg cells (n = 9–10, p<0.05 or 0.01) in the mice model. Conclusion The inhibitory effect of MF on tumor growth was related to the improvement of immune function in the tumor-bearing mice.