Feiyan Ai

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.

Dynamic changes and functions of macrophages and M1/M2 subpopulations during ulcerative colitis-associated carcinogenesis in an AOM/DSS mouse model

The high risk of developing colorectal carcinoma (CRC), from ulcerative colitis (UC), is well known. Macrophages are widely distributed immune cells that have an indispensable role in UC, as well as in CRC. However, little is currently known about the dynamic changes that occur in macrophage and M1/M2 macrophage subpopulations, during UC-associated carcinogenesis. The aim of the present study was to investigate the alteration of colorectal macrophages and M1/M2 macrophage subpopulations during UC-associated carcinogenesis. Both expression level alterations and functional changes were determined during UC-associated carcinogenesis in an azoxymethane/dextran sodium sulfate-induced chemically colitis-associated carcinoma mouse model of Crj:CD-1 (ICR) mice. Notable evidence from immunohistochemistry, flow cytometry, cytokine detection, and gene expression analyses demonstrated that M2 macrophages have a critical role in CRC initiation, promotion, and metastasis. M2 macrophages are associated with unbalanced pro-inflammatory and anti-inflammatory axes and aberrant enhancement of migration/invasion-associated factors. Functional changes, similar to M2 polarized macrophages, were shown to occur in the M1 macrophages, without phenotypical changes, during the development of carcinoma and metastasis. The results of the present study suggest that M2 macrophages have a pro-tumor role during UC-associated carcinogenesis. Furthermore, similar functional changes occurred in the M1 macrophages, without polarization alterations, during carcinogenesis and metastasis.

Dynamic changes of peritoneal macrophages and subpopulations during ulcerative colitis to metastasis of colorectal carcinoma in a mouse model

Objective and designPatients with ulcerative colitis have increased risk of colorectal carcinoma, but little is known about how peritoneal macrophages are involved in ulcerative colitis-associated carcinogenesis. We investigated the alteration of peritoneal macrophages and M1/M2 subpopulations during ulcerative colitis-associated carcinogenesis.Materials and methodsExpression and functional changes in peritoneal macrophages and M1/M2 subpopulations were investigated by histopathology, flow cytometry, immunofluorescence, cytokines expression by ELISA and QRT-PCR in an azoxymethane (AOM)- and dextran sodium sulfate (DSS)-induced chemical colitis-associated carcinoma mouse model using male Crj:CD-1 (ICR) mice.ResultsStriking evidence observed in histopathology, flow cytometry, cytokine detection, and gene expression analysis all revealed that inflammation-associated cytokines (IL-1β, IL-10, IL-12, IL-6, TNF-α) and migration/invasion-associated factors (G-CSF, GM-CSF, CXCR4, VEGF, TGF-β, ICAM-1) induced by peritoneal M2 macrophages increased significantly during the progression from inflammatory hyperplasia to carcinoma and metastasis. Similar functional changes occurred during peritoneal metastasis in M1 macrophages without changed polarization.ConclusionsThese results suggested that peritoneal M2 macrophages played a critical role in ulcerative colitis-associated carcinogenesis, including unbalanced pro-inflammatory and anti-inflammatory axis and enhanced expression of migration/invasion-associated factors. Furthermore, functional changes of M1 macrophages occurred without changed polarization during carcinogenesis and metastasis.

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.

MicroRNA‑34a suppresses colorectal cancer metastasis by regulating Notch signaling

Dysregulation of microRNA (miRNA/miR) expression is causally associated with cancer initiation and progression. However, the precise mechanisms by which dysregulated miRNAs induce colorectal tumorigenesis remain unknown. In the present study, downregulation of miR-34a was identified in colorectal cancer cell lines and clinical specimens. Clinical studies revealed that miR-34a expression was negatively associated with distant metastasis, and positively associated with differentiation and survival of human colorectal cancer specimens. In vitro miRNA functional assays demonstrated that miR-34a bound to the putative 3′-untranslated regions of Notch1 and Jagged1 in SW480 cells, and thereby attenuated the migration and invasion of the colon cancer cells. It was additionally identified that miR-34a downregulated the expression of vimentin and fibronectin via Notch1 and Jagged1. Overall, these data indicate that miR-34a serves a key role in suppressing colorectal cancer metastasis by targeting and regulating Notch signaling.

Infliximab enhances the therapeutic effects of 5-fluorouracil resulting in tumor regression in colon cancer

Colon cancer (CC) is among the most common malignant diseases with a dismal survival. Tumor necrosis factor-alpha (TNF-α) has been identified as a therapeutic target in various cancers, and anti-TNF-α treatment has shown promising effects in different cancer models. However, if TNF-α can be targeted in CC, the therapeutic values of anti-TNF-α treatment in CC remain unknown. Our study indicated that TNF-α is highly expressed in CC cell lines and patient tumor samples. High expression of TNF-α is an independent adverse prognosticator of CC. Targeting the TNF-α by its antibody infliximab induced antibody-dependent cellular cytotoxicity and complement-dependent cytotoxicity and enhanced apoptosis leading to cell death. The combination of infliximab with 5-fluorouracil showed better responses in vitro and in vivo than 5-fluorouracil alone. In conclusion, this study identified TNF-α as a target of CC and anti-TNF-α treatment synergized with chemotherapy leading to a better outcome in preclinical models.

Suppression Colitis and Colitis-Associated Colon Cancer by Anti-S100a9 Antibody in Mice

The association between chronic inflammation and cancer has long been recognized. The inflammatory bowel disease ulcerative colitis frequently progresses to colon cancer; however, the underlying mechanism is still unclear. S100a9 has been emerged as an important pro-inflammatory mediator in acute and chronic inflammation, and the aberrant expression of S100a9 also contributes to tumorigenic processes such as cell proliferation, angiogenesis, metastasis, and immune evasion. We previously revealed that S100a8 and S100a9 are highly activated and play an important role in the process of colitis-associated carcinogenesis, which suggests an attractive therapeutic target for ulcerative colitis and related colon cancer. Here, we report that administration of a neutralizing anti-S100a9 antibody significantly ameliorated dextran sulfate sodium (DSS)-induced colitis and accompanied by diminished cellular infiltrate of innate immunity cells (macrophages, neutrophils, and dendritic cells) and production of pro-inflammatory cytokines (Tnfα, Il1β, Ifnγ, Il6, Il17a, Il23a, Il4, and Il12a). The protective effect of anti-S100a9 antibody treatment was also observed in azoxymethane (AOM)/DSS-induced colitis-associated cancer (CAC) mouse model. The inflammatory response, tumor cell proliferation, and immune cells infiltration in the colon tissues were suppressed by anti-S100a9 antibody. Gene expression profiling showed that key pathways known to be involved in CAC development, such as Wnt signaling pathway, PI3K–Akt signaling pathway, cytokine–cytokine receptor interaction, and ECM–receptor interaction pathway, were suppressed after treatment with anti-S100a9 antibody in CAC mice. In view of the protective effect of neutralizing anti-S100a9 antibody against DSS-induced colitis and AOM/DSS-induced CAC in mouse model, this study suggests that anti-S100a9 antibody may provide a novel therapeutic approach to treat ulcerative colitis and may decrease the risk for developing CAC.

miR-142-5p promotes development of colorectal cancer through targeting SDHB and facilitating generation of aerobic glycolysis

Aberrant expression of miRNAs contributes to the development of human malignancies. A recent study revealed that miR-142-5p is increased in the serum of colorectal cancer (CRC) patients compared to health people. Using starBase v2.0, we found that succinate dehydrogenase-B (SDHB) is a potential target of miR-142-5p, while SDHB is negatively correlated to cancer development through regulating energetic metabolism. Based on these information, this study further examined the expression profiles of miR-142-5p and SDHB in CRC tissues and cell lines using PCR and Western blotting. Transfection experiment and luciferase assay were performed to identify relationship between miR-142-5p and SDHB. Oxygen intake, glucose consumption and production of lactic acid were used to evaluate the influence on energetic metabolism. CRC growth and proliferation were assessed by in vitro and in vivo studies. Results showed that miR-142-5p was up-regulated in CRC, but SDHB was down-regulated. SDHB was confirmed as a target of miR-142-5p, and decreased SDHB in CRC was result from the abnormal up-regulation of miR-142-5p. Lose of SDHB by miR-142-5p inhibited oxygen intake by CRC cells, but increased glucose consumption and lactate production. These suggest miR-142-5p up-regulation in CRC probably facilitates generation of aerobic glycolysis by reducing SDHB. miR-142-5p promoted proliferation and colony formation of CRC, but inhibited apoptosis. SDHB overexpression abrogated these effect of miR-142-5p, which indicates that SDHB depletion mediates tumor-promoting actions of miR-142-5p. This study added novel insight into the CRC development regulated by miR-142-5p. It may be a promising therapy target in the future molecular therapy.