Anliu Tang

MiR-126 suppresses colon cancer cell proliferation and invasion via inhibiting RhoA/ROCK signaling pathway

Recent data strongly suggests the profound role of miRNAs in cancer progression. Here, we showed miR-126 expression was much lower in HCT116, SW620 and HT-29 colon cancer cells with highly metastatic potential and miR-126 downregulation was more frequent in colorectal cancers with metastasis. Restored miR-126 expression inhibited HT-29 cell growth, cell-cycle progression and invasion. Mechanically, microarray results combined with bioinformatic and experimental analysis demonstrated miR-126 exerted cancer suppressor role via inhibiting RhoA/ROCK signaling pathway. These results suggest miR-126 function as a potential tumor suppressor in colon cancer progression and miR-126/RhoA/ROCK may be a novel candidate for developing rational therapeutic strategies.

The tumor suppressor miR-138-5p targets PD-L1 in colorectal cancer

microRNAs (miRNAs) play critical roles in cancer development and progression. This study investigated the effects of miR-138-5p in human colorectal cancer (CRC) development. miR-138-5p was frequently downregulated in CRC tissues and was associated with advanced clinical stage, lymph node metastasis and poor overall survival. We found that miR-138-5p decreased expression of programmed cell death ligand 1 (PD-L1) through interaction with its PD-L1 3′ untranslated region. miR-138-5p also dramatically suppressed CRC cell growth in vitro and inhibited tumorigenesis in vivo. PD-L1 and miR-138-5p levels were inversely correlated in human CRC tumors, and miR-138-5p inhibited PD-L1 expression in tumor models. These results suggest that miR-138-5p is a tumor suppressor in CRC, and its effects are exerted at least partially through PD-L1 downregulation. Low miR-138-5p and high PD-L1 levels correlated with shorter overall CRC patient survival, indicating that miR-138-5p and PD-L1 may serve as CRC biomarkers for risk group assignment, optimal therapy selection and clinical outcome prediction. Targeting PD-L1, possibly by administering miR-138-5p mimics, might be a clinically effective anti-CRC therapeutic strategy.

miR-124 and miR-506 inhibit colorectal cancer progression by targeting DNMT3B and DNMT1.

miR-124 and miR-506 are reportedly down-regulated and associated with tumor progression in many cancers, but little is known about their intrinsic regulatory mechanisms in colorectal cancer (CRC). In this study, we found that the miR-124 and miR-506 levels were significantly lower in human CRC tissues than in controls, as indicated by qRT-PCR and in situ hybridization histochemistry. We also found that the overexpression of miR-124 or miR-506 inhibited tumor cell progression and increased sensitivity to chemotherapy in vitro. Increased miR-124 or miR-506 expression also inhibited tumor cell proliferation and invasion in vivo. Luciferase reporter assays and western blotting were used to determine the association between miR-124, miR-506 and their target genes, DNMTs. We further identified that miR-124 and miR-506 directly targeted DNMT3B and indirectly targeted DNMT1. The overexpression of miR-124 and miR-506 reduced global DNA methylation and restored the expression of E-cadherin, MGMT and P16. In conclusion, our data showed that miR-124 and miR-506 inhibit progression and increase sensitivity to chemotherapy by targeting DNMT3B and DNMT1 in CRC. These findings may provide novel avenues for the development of targeted therapies.

miR-429 Identified by Dynamic Transcriptome Analysis Is a New Candidate Biomarker for Colorectal Cancer Prognosis

Colorectal cancer (CRC) is a common malignant gastrointestinal cancer. Efforts for preventive and personalized medicine have intensified in the last decade with attention to novel forms of biomarkers. In the present study, microRNA and genetic analyses were performed in tandem for differential transcriptome profiling between primary tumors with or without nodes or distant metastases. Serial Test Cluster (STC) analysis demonstrated that 20 genes and two microRNAs showed distinctive expression patterns associated with the tumor, node, and metastasis (TNM) stage. The selected target genes were characterized by GO and Pathway analysis. A microRNA-target gene network analysis showed that miR-429 resided in the center of the network, indicating that miR-429 might serve important roles in the development of CRC. Real-time PCR and tissue microarrays showed that miR-429 had a dynamic expression pattern during the CRC progression stage, and was significantly downregulated in stage II and stage III clinical progression. The low expression of miR-429 was correlated with poor prognosis for CRC. Taken together, miR-429 warrant further clinical translation research as a candidate biomarker for CRC prognosis. Additional downstream targets and attendant gene function also need to be discerned to design a sound critical path to personalized medicine for persons susceptible to, or diagnosed with CRC.

LY294002 and Rapamycin promote coxsackievirus-induced cytopathic effect and apoptosis via inhibition of PI3K/AKT/mTOR signaling pathway

Coxsackievirus B3 (CVB3) is a common human pathogen for acute myocarditis, pancreatitis, non-septic meningitis, and encephalitis; it induces a direct cytopathic effect (CPE) and apoptosis on infected cells. The Phosphatidylinositol 3-kinase (PI3K)/protein kinase B (AKT/PKB)/mammalian target of Rapamycin (mTOR) signaling pathway regulates several cellular processes and it is one of the most important pathways in human networks. However, the effect and mechanism of PI3K/AKT/mTOR signaling pathway in CVB3 infected cells are poorly understood. In this study, we demonstrate that inhibition of PI3K/AKT/mTOR signaling pathway increased CVB3-induced CPE and apoptosis in HeLa cells. The activity of downstream targets of PI3K and mTOR is attenuated after CVB3 infection and inhibitors of PI3K and mTOR made their activity to decrease more significantly. We further show that LY294002 and Rapamycin, the inhibitor of PI3K and mTOR respectively, promote CVB3-induced CPE and apoptosis. Taken together, these data illustrate a new and imperative role for PI3K/AKT/mTOR signaling in CVB3 infection in HeLa cells and suggest an useful approach for the therapy of CVB3 infection.

Jak-STAT3 pathway triggers DICER1 for proteasomal degradation by ubiquitin ligase complex of CUL4ADCAF1 to promote colon cancer development

Chronic intestinal inflammation is closely associated with colon cancer development and STAT3 seems to take center stage in bridging chronic inflammation to colon cancer progress. Here, we discovered that DICER1 was significantly downregulated in response to IL-6 or LPS stimulation and identified a novel mechanism for DICER1 downregulation via proteasomal degradation by ubiquitin ligase complex of CUL4A(DCAF1) in colon cancer cells. Meanwhile, PI3K-AKT signaling pathway phosphorylated DICER1 and contributed to its proteasomal degradation. The regulation of DICER1 by CUL4A(DCAF1) affected cell growth and apoptosis which is controlled by IL-6 activated Jak-STAT3 pathway. Intervention of CUL4A(DCAF1) ubiquitin ligase complex led to fluctuation in expression levels of DICER1 and microRNAs, and thus affected tumor growth in a mouse xenograft model. A panel of microRNAs that were downregulated by IL-6 stimulation was rescued by siRNA-CUL4A, and their predicated functions are involved in regulation of cell proliferation, apoptosis and motility. Furthermore, clinical specimen analysis revealed that decreased DICER1 expression was negatively correlated with STAT3 activation and cancer progression in human colon cancers. DICER1 and p-STAT3 expression levels correlated with 5-year overall survival of colon cancer patients. Consequently, this study proposes that inflammation-induced Jak-STAT3 signaling leads to colon cancer development through proteasomal degradation of DICER1 by ubiquitin ligase complex of CUL4A(DCAF1), which suggests a novel therapeutic opportunity for colon cancer.

Inflammation-induced S100A8 activates Id3 and promotes colorectal tumorigenesis

The aberrant expression of S100A8 and S100A9 is linked to nonresolving inflammation and ultimately to carcinogenesis, whereas the underlying mechanism that allows inflammation to progress to specific cancer types remains unknown. Here, we report that S100A8 was induced by inflammation and then promoted colorectal tumorigenesis downstream by activating Id3 (inhibitor of differentiation 3). Using gene expression profiling and immunohistochemistry, we found that both S100A8 and S100A9 were upregulated in the chemically‐induced colitis‐associated cancer mouse model and in human colorectal cancer specimens. Furthermore, we showed that S100A8 and S100A9 acted as chemoattractant proteins by recruiting macrophages, promoting the proliferation and invasion of colon cancer cell, as well as spurring the cycle that culminates in the acceleration of cancer metastasis in a nude mouse model. S100A8 regulated colon cancer cell cycle and proliferation by inducing Id3 expression while inhibiting p21. Id3 expression was regulated by Smad5, which was directly phosphorylated by Akt1. Our study revealed a novel mechanism in which inflammation‐induced S100A8 promoted colorectal tumorigenesis by acting upstream to activate the Akt1‐Smad5‐Id3 axis.

Lactoferrin Deficiency Promotes Colitis-Associated Colorectal Dysplasia in Mice

Nonresolving inflammatory processes affect all stages of carcinogenesis. Lactoferrin, a member of the transferrin family, is involved in the innate immune response and anti-inflammatory, anti-microbial, and anti-tumor activities. We previously found that lactoferrin is significantly down-regulated in specimens of nasopharyngeal carcinoma (NPC) and negatively associated with tumor progression, metastasis, and prognosis of patients with NPC. Additionally, lactoferrin expression levels are decreased in colorectal cancer as compared with normal tissue. Lactoferrin levels are also increased in the various phases of inflammation and dysplasia in an azoxymethane–dextran sulfate sodium (AOM-DSS) model of colitis-associated colon cancer (CAC). We thus hypothesized that the anti-inflammatory function of lactoferrin may contribute to its anti-tumor activity. Here we generated a new Lactoferrin knockout mouse model in which the mice are fertile, develop normally, and display no gross morphological abnormalities. We then challenged these mice with chemically induced intestinal inflammation to investigate the role of lactoferrin in inflammation and cancer development. Lactoferrin knockout mice demonstrated a great susceptibility to inflammation-induced colorectal dysplasia, and this characteristic may be related to inhibition of NF-κB and AKT/mTOR signaling as well as regulation of cell apoptosis and proliferation. Our results suggest that the protective roles of lactoferrin in colorectal mucosal immunity and inflammation-related malignant transformation, along with a deficiency in certain components of the innate immune system, may lead to serious consequences under conditions of inflammatory insult.

Tumor-Conditioned Mesenchymal Stem Cells Display Hematopoietic Differentiation and Diminished Influx of Ca2+

Mesenchymal stem cells (MSCs) that are present in many adult tissues can generate new cells either continuously or in response to injury/cancer. An increasing number of studies demonstrated that MSCs have the ability to differentiate into cells of mesodermal origin and transdifferentiate into cells such as hepatocytes, neural cells. There has been growing interest in the application of MSCs to cancer therapy. The relationship between MSCs and cancer cells remains highly controversial. In this study, we analyzed the interaction of bone marrow-derived MSCs and cancer cells by cell-cell contact and transwell culture system. The flow cytometry and real-time polymerase chain reaction showed that after coculture of MSCs and cancer cells, MSCs displayed the hematopoietic cell markers such as CD34, CD45, and CD11b. The CD68, MRCI, and CSF1R were dramatically upregulated after coculture. The cytokine array showed that MSCs after coculture secreted monokines and chemokines much more than that of intact MSCs. The MSCs under tumor conditions were responsive to stimulation with lipopolysaccharide by cytokines release. The tumor-conditioned MSCs showed phagocytic ability and enhanced release of nitric oxide, which are the characteristics of macrophages. Calcium ion is an important intracellular messenger responsible for differentiation and gene expression regulations. The influx of Ca(2+) into MSCs was obviously reduced after coculture. The blocking of calcium channel with verapamil obviously increased the expression of CD34, CD45, and CD11b, thus indicating that the diminished calcium ion influx is coupled with the hematopoietic differentiation of MSCs under tumor conditions. Taken together, in a cancer environment, MSCs could effectively differentiate into immune hematopoietic cells, precisely macrophages. Diminished transient influx of Ca(2+) may mediate the hematopoietic differentiation of MSCs.

Formation of zinc oxide nanoparticles by mechanochemical reaction

Abstract The synthesis of zinc oxide (ZnO) nanocrystallites by mechanochemical reaction of ZnCl2 and Na2CO3 with NaCl as diluent and following thermal treatment was investigated using X-ray diffraction (XRD) and transmission electron microscopy (TEM). Calcination of the as milled powder at 600°C in air and removal of NaCl through washing formed ZnO nanocrystallites with an average crystal size of ~ 21 nm, which increased with increasing thermal treatment temperature. Milling time and NaCl/ZnCl2 molar ratio exerted prominent effects on the crystal size of the ZnO nanoparticles. The mechanism of nanocrystallite growth is discussed.