The Wnt Target Gene L1 in Colon Cancer Invasion and Metastasis

Wnt Signaling Pathway Is among the Drivers of Liver Metastasis

Liver metastasis, originating either from a primary liver or other cancer types, represent a large cancer-related burden. Therefore, studies that add to better understanding of its molecular basis are needed. Herein, the role of the Wnt signaling pathway in liver metastasis is outlined. Its role in hepatocellular carcinoma (HCC) epithelial-mesenchymal transition (EMT), motility, migration, metastasis formation, and other steps of the metastatic cascade are presented. Additionally, the roles of the Wnt signaling pathway in the liver metastasis formation of colorectal, breast, gastric, lung, melanoma, pancreatic, and prostate cancer are explored. The special emphasis is given to the role of the Wnt signaling pathway in the communication between the many of the components of the primary and secondary cancer microenvironment that contribute to the metastatic outgrowth in the liver. The data presented herein are a review of the most recent publications and advances in the field that add to the idea that the Wnt pathway is among the drivers of liver metastasis and that its targeting could potentially relieve liver metastasis–related complications.

miR‑483 promotes the development of colorectal cancer by inhibiting the expression level of EI24

MicroRNAs (miRs) serve an important role in cell differentiation, proliferation and apoptosis by negatively regulating gene expression at the transcriptional or post‑transcriptional level. EI24 autophagy associated transmembrane protein (EI24) is a tumor suppressor gene that serves an important role in the occurrence and development of digestive system tumors. However, little is known regarding the relationship between EI24 and the prognosis of patients with colorectal cancer (CRC). Our previous study confirmed EI24 as the target molecule of miR‑483, using reporter gene detection. Thus, the aim of the present study was to elucidate the effect of the abnormal expression of miR‑483 on the malignant phenotype of CRC through a series of cell function experiments and nude mice tumorigenicity experiments, and to determine the expression level of EI24, a downstream target gene of miR‑483, in CRC and its relationship with patient prognosis. In CRC tissues and cells, the expression level of miR‑483 was upregulated, while the expression level of EI24 was downregulated. Cell function tests such as MTT assay, cell cycle assay, colony formation assay, Migration and invasion assays and nude mice tumorigenicity experiments demonstrated that the overexpression of miR‑483 promoted the proliferation, invasion and metastasis of CRC. Moreover, the reverse transcription‑quantitative PCR results indicated that overexpression of miR‑483 inhibited the expression level of EI24. The relationship between the clinical data and immunohistochemical results from 183 patients with CRC and survival was examined. It was found that the expression level of EI24 was positively associated with the prognosis of patients. As a cancer‑promoting factor, miR‑483 enhances the proliferation, migration and invasion of CRC cells by reducing the expression level of EI24.

TGF-β acts as a dual regulator of COX-2/PGE2 tumor promotion depending of its cross-interaction with H-Ras and Wnt/β-catenin pathways in colorectal cancer cells

Transforming growth factor-β (TGF-β) plays a dual role acting as tumor promoter or suppressor. Along with cyclooxygenase-2 (COX-2) and oncogenic Ras, this multifunctional cytokine is deregulated in colorectal cancer. Despite their individual abilities to promote tumor growth and invasion, the mechanisms of cross regulation between these pathways is still unclear. Here, we investigate the effects of TGF-β, Ras oncogene and COX-2 in the colorectal cancer context. We used colon adenocarcinoma cell line HT-29 and Ras-transformed IEC-6 cells, both treated with prostaglandin E₂ (PGE₂ ), TGF-β or a combined treatment with these agents. We demonstrated that PGE₂ alters the subcellular localization of E-cadherin and β-catenin and enhanced the tumorigenic potential in HT-29 cells. This effect was inhibited by TGF-β, indicating a tumor suppressor role. Conversely, in Ras-transformed IEC-6 cells, TGF-β induced COX-2 expression and increased invasiveness, acting as a tumor promoter. In IEC-6 Ras-transformed cells, TGF-β increased nuclear β-catenin and Wnt/β-catenin activation, opposite to what was seen in the PGE₂ and TGF-β joint treatment in HT-29 cells. Together, our findings show that TGF-β increases COX-2 levels and induces invasiveness cooperating with Ras in a Wnt/β-catenin activation-dependent manner. This shows TGF-β dual regulation over COX-2/PGE₂ tumor promotion depending on the H-Ras and Wnt/β-catenin pathways activation status in intestinal cancer cells.

Biomarkers of tumor invasiveness in proteomics (Review)

Over the past two decades, quantitative proteomics has emerged as an important tool for deciphering the complex molecular events involved in cancers. The number of references involving studies on the cancer metastatic process has doubled since 2010, while the last 5 years have seen the development of novel technologies combining deep proteome coverage capabilities with quantitative consistency and accuracy. To highlight key findings within this huge amount of information, the present review identified a list of tumor invasive biomarkers based on both the literature and data collected on a biocollection of experimental cell lines, tumor models of increasing invasiveness and tumor samples from patients with colorectal or breast cancer. Crossing these different data sources led to 76 proteins of interest out of 1,245 mentioned in the literature. Information on these proteins can potentially be translated into clinical prospects, since they represent potential targets for the development and evaluation of innovative therapies, alone or in combination. Herein, a systematical review of the biology of each of these proteins, including their specific subcellular/extracellular or multiple localizations is presented. Finally, as an important advantage of quantitative proteomics is the ability to provide data on all these molecules simultaneously in cell pellets, body fluids or paraffin‑embedded sections of tumors/invaded tissues, the significance of some of their interconnections is discussed.

A study on the mechanism of Wnt inhibitory factor 1 in osteoarthritis

INTRODUCTION

In our study we aimed to investigate the mechanism of Wnt inhibitory factor 1 (WIF1) on regulating chondrocyte proliferation and apoptosis via reactive oxygen species (ROS) and the Wnt/βcatenin signaling pathway in osteoarthritis (OA).

MATERIAL AND METHODS

Osteoarthritis chondrocytes were treated with interleukin 1β (IL-1β) to simulate an inflammatory condition. Quantitative real-time polymerase chain reaction (qRT-PCR) and western blot were applied for detecting WIF1 expression in OA chondrocytes. MTT assay and flow cytometry were carried out to analyze the cell proliferation and apoptosis. Content of ROS was detected using flow cytometry, and activity of the Wnt/βcatenin signaling pathway was detected using immunofluorescence, western blot and luciferase reporter assay. Western blot and enzyme-linked immunosorbent assay (ELISA) were performed to detect the expression of apoptosis-related proteins and secretion of matrix metalloproteinases (MMPs).

RESULTS

WIF1 expression in OA chondrocytes was significantly lower than in normal chondrocytes. After WIF1 cDNA transfection, the aberrantly high ROS level in OA chondrocytes was down-regulated, which led to the increase of proliferation and reduction of apoptosis. The Wnt/βcatenin signaling pathway was suppressed by WIF1 overexpression and the secretion of MMPs was therefore reduced.

CONCLUSIONS

Up-regulation of WIF1 would promote proliferation and suppress apoptosis of OA chondrocytes through eliminating ROS production and reduce secretion of MMPs via blocking the Wnt/βcatenin signaling pathway.

Increased expression of cathepsin D is required for L1-mediated colon cancer progression

Hyperactivation of Wnt/β-catenin target genes is considered a key step in human colorectal cancer (CRC) development. We previously identified the immunoglobulin-like cell adhesion receptor L1 as a target gene of β-catenin/TCF transactivation that is localized at the invasive edge of CRC tissue. Using gene arrays, we discovered a number of downstream target genes and signaling pathways conferred by L1 overexpression during colon cancer progression. Here, we have used a proteomic approach to identify proteins in the secretome of L1-overexpressing CRC cells and studied the role of the increase in the aspartate protease cathepsin D (CTSD) in L1-mediated colon cancer development. We found that in addition to the increase in CTSD in the secretome, the RNA and protein levels of CTSD were also induced by L1 in CRC cells. CTSD overexpression resulted in elevated proliferation under stress and increased motility, tumorigenesis and liver metastasis, although to a lesser extent than after L1-transfection. The suppression of endogenous CTSD in L1-expressing cells blocked the increase in the proliferative, motile, tumorigenic and metastatic ability of CRC cells. Enhancing Wnt/β-catenin signaling by the inhibition of GSK3β resulted in increased endogenous CTSD levels, suggesting the involvement of the Wnt/β-catenin pathway in CTSD expression. In human CRC tissue, CTSD was detected in epithelial cells and in the stromal compartment at the more invasive areas of the tumor, but not in the normal mucosa, indicating that CTSD plays an essential role in CRC progression.

Effect of hMLH1, hMSH2, hMSH6, integrin β1, and Ki-67 expression on prognosis of colorectal cancer

AIM

To investigate the expression of hMLH1, hMSH2, hMSH6, integrin β1, and Ki-67 in colorectal cancer and to analyze their effect on the prognosis of this malignancy.

METHODS

One hundred and sixty-two tumor specimens of colorectal cancer patients treated in Jinhua Hospital of Jinhua University were collected, and immunohistochemical staining was used to determine the expression of hMLH1, hMSH2, hMSH6, integrin β1, and Ki-67 in the specimens. The results were analyzed statistically.

RESULTS

Among 162 specimens, 36 were found to have missing expression of hMLH1, hMSH2, and hMSH6, with a deletion rate of 22.22%. The expression of MMR protein was significantly associated with tumor diameter (P = 0.0005), Dukes stage (P = 0.0248), family history of tumor (P = 0.0042), and lymph node metastasis (P = 0.0014). The positive expression of integrin β1 was significantly associated with Dukes stage (P = 0.0002), and the positive expression of Ki-67 was significantly associated with Dukes stage (P = 0.0002) and lymph node metastasis (P = 0.0111). Loss of MMR protein expression and positive expression of integrin β1 and Ki-67 were significantly associated with Dukes stage (P = 0.006) and lymph node metastasis (P = 0.023). The 5-year survival rate was 88.89% in the deficient mismatch repair group and 59.52% in the proficient mismatch repair group, and the difference was statistically significant (P = 0.0010). The 5-year survival rate was significantly lower in the integrin β1 positive group than in the integrin β1 negative group (59.69% vs 90.91%, P = 0.0007). The 5-year survival rate was also significantly lower in the Ki-67 positive group than in the Ki-67 negative group (63.27% vs 93.33%, P = 0.0192).

CONCLUSION

The expression of MMR protein, integrin β1, and Ki-67 is statistically correlated with Dukes stage and lymph node metastasis in colorectal cancer, and all the three factors are related to the prognosis of patients: loss of MMR protein expression and negative expression of integrin β1 and Ki-67 are associated with better prognosis and higher 5-year survival rate.

The intestinal stem cell regulating gene ASCL2 is required for L1-mediated colon cancer progression

Aberrant Wnt/β-catenin signaling is a common event during human colorectal cancer (CRC) development. Previously, we characterized members of the L1 family of cell adhesion receptors as targets of β-catenin-LEF1/TCF transactivation that are expressed at the invasive CRC tissue edge. Overexpression of L1 in CRC cells confers enhanced motility, tumorigenesis and liver metastasis. We identified several downstream targets of L1-mediated signaling that are considered key intestinal stem cell signature genes. Here, we investigated the involvement of ASCL2, a Wnt target gene and key determinant of intestinal stem cell state, in L1-mediated CRC progression. In L1 overexpressing CRC cells we found an increase in ASCL2, a decrease in E-cadherin and accumulation of nuclear β-catenin, β-catenin-LEF1/TCF transactivation and target gene expression. The increase in ASCL2 by L1 overexpression enhanced ASCL2 target gene expression, conferred increased motility, tumorigenesis and metastasis, similar to L1 overexpression. Suppression of ASCL2 in cells expressing L1 blocked these tumorigenic properties. In human CRC tissue, ASCL2 was detected in the nuclei of cells at invasive areas of the tumor that also expressed L1. The results suggest that increased ASCL2 expression is a critical step in L1-mediated CRC progression.

SATB2/β-catenin/TCF-LEF pathway induces cellular transformation by generating cancer stem cells in colorectal cancer

Recent studies have demonstrated the involvement of colorectal cancer (CRC) stem cells (CSC) in transformation, cancer progression and metastasis. The main goal of this paper was to examine the molecular mechanisms by which SATB2 induced malignant transformation of colorectal epithelial cells. SATB2 induced malignant transformation and these transformed cells gained the characteristics of CSCs by expressing stem cell markers (CD44, CD133, LGR5 and DCLK1) and transcription factors (c-Myc, Nanog and Sox2). Overexpression of SATB2 in normal colorectal epithelial cells increased cell motility, migration and invasion, which were associated with an increase in N-cadherin and Zeb1, and decrease in E-cadherin expression. SATB2 overexpression also upregulated XIAP and cyclin D1, suggesting its role in cell survival and cell cycle. Furthermore, the expression of SATB2 was positively correlated with β-catenin expression in CRC. In contrary, depletion of SATB2 inhibited cell proliferation, colony formation, cell motility and expression of β-catenin, Snail, Slug, Zeb1 and N-cadherin, and upregulated E-cadherin. Furthermore, SATB2 silencing inhibited the expression of stem cell markers, pluripotency maintaining transcription factors, cell cycle and cell proliferation/survival genes and TCF/LEF targets. Finally, β-catenin/TCF-LEF pathway mediated the biological effects of SATB2 in CSCs. These studies support the role of SATB2/β-catenin/TCF-LEF pathway in transformation and carcinogenesis.

SATB2/β-catenin/TCF-LEF pathway induces cellular transformation by generating cancer stem cells in colorectal cancer

Recent studies have demonstrated the involvement of colorectal cancer (CRC) stem cells (CSC) in transformation, cancer progression and metastasis. The main goal of this paper was to examine the molecular mechanisms by which SATB2 induced malignant transformation of colorectal epithelial cells. SATB2 induced malignant transformation and these transformed cells gained the characteristics of CSCs by expressing stem cell markers (CD44, CD133, LGR5 and DCLK1) and transcription factors (c-Myc, Nanog and Sox2). Overexpression of SATB2 in normal colorectal epithelial cells increased cell motility, migration and invasion, which were associated with an increase in N-cadherin and Zeb1, and decrease in E-cadherin expression. SATB2 overexpression also upregulated XIAP and cyclin D1, suggesting its role in cell survival and cell cycle. Furthermore, the expression of SATB2 was positively correlated with β-catenin expression in CRC. In contrary, depletion of SATB2 inhibited cell proliferation, colony formation, cell motility and expression of β-catenin, Snail, Slug, Zeb1 and N-cadherin, and upregulated E-cadherin. Furthermore, SATB2 silencing inhibited the expression of stem cell markers, pluripotency maintaining transcription factors, cell cycle and cell proliferation/survival genes and TCF/LEF targets. Finally, β-catenin/TCF-LEF pathway mediated the biological effects of SATB2 in CSCs. These studies support the role of SATB2/β-catenin/TCF-LEF pathway in transformation and carcinogenesis.