Zhiqian Zhang

Both miR-17-5p and miR-20a Alleviate Suppressive Potential of Myeloid-Derived Suppressor Cells by Modulating STAT3 Expression

Myeloid-derived suppressor cells (MDSCs) were one of the major components of the immune suppressive network. STAT3 has an important role in regulating the suppressive potential of MDSCs. In this study, we found that the expression of STAT3 could be modulated by both miR-17-5p and miR-20a. The transfection of miR-17-5p or miR-20a remarkably reduces the expression of reactive oxygen species and the production of H2O2, which are regulated by STAT3. MDSCs transfected with miR-17-5p or miR-20a are less able to suppress Ag-specific CD4 and CD8 T cells. Importantly, both miR-17-5p and miR-20a alleviate the suppressive function of MDSCs in vivo. The expression of miR-17-5p and miR-20a in tumor-associated MDSCs was found to be lower than in Gr1+CD11b+ cells isolated from the spleens of disease-free mice. Tumor-associated factor downregulates the expression of both miR-17-5p and miR-20a. The modulation of miR-17-5p and miR-20a expression may be important for the process by which patients with a tumor can overcome the immune tolerance mediated by MDSCs. Our results suggest that miR-17-5p and miR-20a could potentially be used for immunotherapy against diseases, especially cancer, by blocking STAT3 expression.

miR‐223 suppresses differentiation of tumor‐induced CD11b+Gr1+myeloid‐derived suppressor cells from bone marrow cells

Tumor‐associated factors are related to increased accumulation of CD11b+Gr1+myeloid‐derived suppressor cells (MDSCs). However, the exact mechanism of how genetic factors control the expansion of MDSCs in tumor‐bearing hosts remains elusive. Herein, we found that tumor‐associated MDSCs and their subsets, mononuclear MDSCs and polymorphonuclear MDSCs, have decreased expression of miR‐223 when compared to CD11b+Gr1+ cells from the spleen of disease‐free mice. With the differentiation of CD11b+Gr1+MDSCs from bone marrow cells (BMCs) upon exposure to tumor‐associated factors, the expression of both pri‐miR‐223 and mature miR‐223 was downregulated, indicating that the expression of miR‐223 could be regulated by tumor‐associated factors. Interestingly, miR‐223 remarkably inhibits differentiation of BMCs into CD11b+Gr1+MDSCs in the presence of tumor‐associated factors by targeting myocyte enhancer factor 2C (MEF2C). Using reconstituted s.c. tumor models, miR‐223 also suppresses accumulation of CD11b+Gr1+MDSCs, whereas its targeting molecule MEF2C increases the number of MDSCs. Tumor growth is slower in mice infused by miR223‐engineered BMCs than in mice infused with control transfected BMCs. As miR‐223 and its target molecule MEF2C are highly conserved between mice and humans, the modulation of miR‐223 in tumor‐induced CD11b+Gr1+MDSCs may exert an important role in controlling the increased accumulation of CD11b+Gr1+MDSCs in patients with tumor.

Interruption of KLF5 acetylation converts its function from tumor suppressor to tumor promoter in prostate cancer cells.

KLF5 possesses both tumor suppressing and tumor promoting activities, though the mechanism controlling these opposing functions is unknown. In cultured noncancerous epithelial cells, KLF5 converts from proproliferative to antiproliferative activity upon TGFβ‐induced acetylation, which sequentially alters the KLF5 transcriptional complex and the expression of genes such as p15 and MYC. In this study, we tested whether the acetylation status of KLF5 also determines its opposing functions in tumorigenesis using the PC‐3 and DU 145 prostate cancer cell lines, whose proliferation is inhibited by TGFβ. KLF5 inhibited the proliferation of these cancer cells, and the inhibition was dependent on KLF5 acetylation. MYC and p15 showed the same patterns of expression change found in noncancerous cells. In nude mice, KLF5 also suppressed tumor growth in an acetylation‐dependent manner. Furthermore, deacetylation switched KLF5 to tumor promoting activity, and blocking TGFβ signaling attenuated the tumor suppressor activity of KLF5. RNA sequencing and comprehensive data analysis suggest that multiple molecules, including RELA, p53, CREB1, MYC, JUN, ER, AR and SP1, mediate the opposing functions of AcKLF5 and unAcKLF5. These results provide novel insights into the mechanism by which KLF5 switches from antitumorigenic to protumorigenic function and also suggest the roles of AcKLF5 and unAcKLF5, respectively, in the tumor suppressing and tumor promoting functions of TGFβ.

Suppressor of Cytokine Signaling 3 Promotes Bone Marrow Cells to Differentiate into CD8+ T Lymphocytes in Lung Tissue via Up-Regulating Notch1 Expression

Suppressor of cytokine signaling 3 (SOCS3) expression in bone marrow cells (BMC) was up-regulated upon exposure to interleukin 6, lipopolysaccharide, or tumor-associated factors. But, how the up-regulated SOCS3 affects differentiation of BMCs is incompletely characterized. Here, we showed that SOCS3 promoted BMCs to intently differentiate into CD8 T cells. Importantly, lung can be as one athymus tissue for the BMCs to differentiate into CD8(+) T cells. Notch1 plays a critical role in the differentiation from SOCS3-transfected BMCs to CD8(+) T cells. We conclude that the up-regulated SOCS3 in some pathologic conditions, such as tumor and inflammation, might promote BMCs to differentiate into CD8(+) T lymphocytes in lung tissue via up-regulating Notch1 expression. This may represent a new mechanism against diseases such as tumor.

Chromosome 1 Open Reading Frame 190 Promotes Activation of NF-κB Canonical Pathway and Resistance of Dendritic Cells to Tumor-Associated Inhibition In Vitro

Tumor-associated dendritic cells (DCs) often induce T cell anergy or deletion and regulatory T cells instead of antitumor immunity. Although many tumor-associated Ags have been found, there is still no effective vaccine for cancer. Thus, novel rational strategies to enhance the immunogenicity of cancer-specific Ags are needed. Chromosome 1 open reading frame 190 (c1orf190), a gene that encodes a 239-aa hypothetical protein and contains multiple kinase phosphorylation sites, has a wide relationship with multiple signaling pathway molecules and can be regulated by multiple factors, such as TLR ligands. In this study, we demonstrate that c1orf190 can activate NF-κB, drive the production of cytokines, and promote the Ag-presenting function and the priming ability of DCs. Furthermore, c1orf190 can promote resistance of DCs to tumor-associated inhibition not only in the Ag-presenting function but also in the priming ability to induce Ag-specific T lymphocytes. Thus, c1orf190, an NF-κB activator, may be a candidate gene for regulating the function of DCs to resist tumor-associated factor-mediated dysfunction. We also found that c1orf190-mediated cytokine release is achieved by activating the canonical but not the noncanonical NF-κB pathway.

Expression of FABP4, adipsin and adiponectin in Paneth cells is modulated by gut Lactobacillus

We here found that intestinal epithelial Paneth cells secrete FABP4, adipsin and adiponectin in both mice and human. Deletion of Paneth cell results in the decrease of FABP4, adipsin and adiponectin not only in intestinal crypt cells but also in sera, suggesting that they may influence the state of the whole body. We also demonstrate that expression of FABP4, adipsin and adiponectin may be modulated by specific gut microbiota. In germ-free (GF) mice, the expression of FABP4, adipsin and adiponectin were lower or difficult to be detected. Feces transplantation promoted the expression of FABP4, adipsin and adiponectin in gut epithelial Paneth cells. We have found that Lactobacillus NK6 colony, which has the highest similarity with Lactobacillus taiwanensis strain BCRC 17755, may induce the expression of FABP4, adipsin and adiponectin through TRAF2 and TRAF6 ubiquitination mediated NF-κB signaling. Taken together, our findings set up a novel mechanism for FABP4, adipsin and adiponectin through gut microbiota mediating expression in gut Paneth cells.

Epigenetic Component p66a Modulates Myeloid-Derived Suppressor Cells by Modifying STAT3

STAT3 plays a critical role in myeloid-derived suppressor cell (MDSC) accumulation and activation. Most studies have probed underlying mechanisms of STAT3 activation. However, epigenetic events involved in STAT3 activation are poorly understood. In this study, we identified several epigenetic-associated proteins such as p66a (Gatad2a), a novel protein transcriptional repressor that might interact with STAT3 in functional MDSCs, by using immunoprecipitation and mass spectrometry. p66a could regulate the phosphorylation and ubiquitination of STAT3. Silencing p66a promoted not only phosphorylation but also K63 ubiquitination of STAT3 in the activated MDSCs. Interestingly, p66a expression was significantly suppressed by IL-6 both in vitro and in vivo during MDSC activation, suggesting that p66a is involved in IL-6–mediated differentiation of MDSCs. Indeed, silencing p66a could promote MDSC accumulation, differentiation, and activation. Tumors in mice injected with p66a small interfering RNA–transfected MDSCs also grew faster, whereas tumors in mice injected with p66a-transfected MDSCs were smaller as compared with the control. Thus, our data demonstrate that p66a may physically interact with STAT3 to suppress its activity through posttranslational modification, which reveals a novel regulatory mechanism controlling STAT3 activation during myeloid cell differentiation.

The miR‐203/SNAI2 axis regulates prostate tumor growth, migration, angiogenesis and stemness potentially by modulating GSK‐3β/β‐CATENIN signal pathway

Dysregulation of microRNA expression plays a pivotal role in the initiation and progression of a variety of human carcinomas including prostate cancer. Our previous studies have demonstrated that the silence of miR‐203 contributes to the invasiveness of malignant breast cancer cells by targeting SNAI2. However, the effects and underlying mechanisms of miR‐203/SNAI2 axis in prostate cancer have not been elucidated. The aim of this study is to explore the effects of miR‐203/SNAI2 axis on the biological characteristics of prostate carcinomas both in vitro and in vivo. We found that miR‐203 was significantly downregulated in prostate cancer cell lines compared with immortalized prostate epithelial cells using semi‐quantitative PCR and real‐time PCR, as well as in clinical prostate cancer tissues compared to normal tissues using TCGA analysis. Functionally, miR‐203 inhibited prostate cancer cell proliferation, migration, endothelial cell tube formation and cancer stemness in vitro. Meanwhile, overexpression of miR‐203 suppressed SNAI2 expression both in DU145 and PC3 cells. In addition, the in vivo study showed that miR‐203 suppressed tumorigenicity, metastasis and angiogenesis of DU145 cells. Ectopic expression of SNAI2 rescued the inhibitory effects of miR‐203 both in vitro and in vivo. Importantly, the EMT markers CDH1 and VIMENTIN were modulated by the miR‐203/SNAI2 axis. Furthermore, the GSK‐3β/β‐CATENIN signal pathway was suppressed by miR‐203 and could be reactivated by SNAI2. Taken together, this research unveiled the function of miR‐203/SNAI2 axis in tumorigenesis, angiogenesis, stemness, metastasis and GSK‐3β/β‐CATENIN signal pathway in prostate cancer and gave insights into miR‐203/SNAI2‐targeting therapy for prostate cancer patients.

Gut REG3γ-Associated Lactobacillus Induces Anti-inflammatory Macrophages to Maintain Adipose Tissue Homeostasis

Gut microbiota may not only affect composition of local immune cells but also affect systemic immune cells. However, it is not completely clear how gut microbiota modulate these immune systems. Here, we found that there exist expanded macrophage pools in huREG3γtgIEC mice. REG3γ-associated Lactobacillus, which is homology to Lactobacillus Taiwanese, could enlarge macrophage pools not only in the small intestinal lamina propria but also in the spleen and adipose tissues. STAT3-mediated signal(s) was a critical factor in the Lactobacillus-mediated anti-inflammatory macrophages. We also offered evidence for critical cellular links among REG3γ-associated Lactobacillus, tissue macrophages, and obesity diseases. Anti-inflammatory macrophages in the lamina propria, which are induced by REG3γ-associated Lactobacillus, may migrate into adipose tissues and are involved in resistance against high-fat diet-mediated obesity. Thus, REG3γ-associated Lactobacillus-induced anti-inflammatory macrophages in gut tissues may play a role in adipose tissue homeostasis.