The system of hepatocyte growth factor (HGF) and its receptor c-Met plays a critical role in tumor invasive growth and metastasis. The mortality rate of colorectal cancer (CRC), one of the most commonly diagnosed malignancies, is increased by it gradual development into metastasis, most frequently in the liver. Overexpression of c-Met, the protein tyrosine kinase receptor for the HCF/scatter factor, has been implicated in the progression and metastasis of human colorectal carcinoma. In this study, we aimed to investigate the role of c-Met in CRC liver metastasis and illustrate the clinical impact of regulating HGF/c-Met signaling in patients with CRC liver metastasis. We found that (I) higher levels of c-Met expression (mRNA and Protein) in CRC liver metastasis than primary CRC by assessing the patient tissue samples; (II) a positive correlation of c-Met expression with tumor stages of CRC liver metastasis, as well as c-Met expression in CRC, live metastasis concurred with regional lymph node metastasis; (III) the clinical impact of downregulation of HGF/c-Met signaling on the reduction of proliferation and invasion in CRC liver metastasis. Therefore, we demonstrate that the regulation of HGF/c-Met pathways may be a promising strategy in the treatment of patients with CRC liver metastasis.

Colorectal cancer (CRC) is the second most frequent and fatal cancer in Western countries. Understanding its biology with different incidence along the colon and rectum, genetic profile and how these factors contribute to local/distant progression, has been hampered by the lack of a suitable CRC model. We report a reproducible model, using human CRC cell lines (CL) (WiDr, LS1034, C2BBe1) injected (1 × 10⁷ cells/animal) in RNU rats (n = 55) which underwent cecostomy and descending colostomy with mucosal-cutaneous fistula of the sigmoid colon. CL were characterized by immunohistochemistry: CK20, CDX2, P53, vimentin, Ki67, CD44, CD133, E-cadherin, β-catenin and CEA; cancer stem cells-immune system interaction was studied and tumor progression was assessed with nuclear medicine imaging (^99mTc-MIBI). Animals developed locally invasive tumors and with WiDr neural invasion was registered. Cancer stem cells were detected in WiDr (CD44 positive). All the cell lines stimulated the immune system, being WiDr the most aggressive. Imaging studies demonstrated tumor uptake. With this CRC model we can study the microenvironment role and tumor-stroma interactions. All CL developed primary disease, but only the WiDR established neural invasion which may represent a metastatic pathway. This model can help unveiling the underlying metastatic mechanisms, and ultimately test better therapeutic approaches for CRC.

To make orthotopic colon cancer murine models a more clearly understood subject. The orthotopic tumor models have been found to be more relevant in replicating the human disease process as compared to heterotopic models, many techniques for making orthotopic colorectal murine models have been reported.

We evaluated the current literature for various reported orthotopic colon cancer models to understand their techniques, advantages and limitations. An extensive literature review was performed by searching the National Library of Medicine Database (PubMed) using MeSH terms animal model; colon cancer; orthotopic model; murine model. Twenty studies related to colon cancer orthotopic xenograft model were evaluated in detail and discussed here.

The detailed analysis of all relevant reports on orthotopic model showed tumor take rate between 42%-100%. While models using the enema technique and minimally invasive technique have reported development of tumor from mucosa with tumor take rate between 87%-100% with metastasis in 76%-90%.

Over the years, the increased understanding of the murine models of human colon cancer has resulted in the development of various models. Each reported model has some limitations. These latest models have opened up new doors for continuing cancer research for not only understanding the colon cancer pathogenesis but also aid in the development of newer chemotherapeutic drugs as they mimic the human disease closely.

The present study aims to identify differences between left and right colon adenocarcinoma arising from identical clonal cell and to find out if microenvironment has any influence on matrix metalloproteinase-2 (MMP2), p53 and β-catenin tumor expressions. MATERIAL AND METHODS. Rats (RNU) were submitted to cecostomy to obtain the orthotopic model of right colon tumor (n = 10), while for the left colon model (n = 10), a colon diversion and distal mucous fistula in the descending colon was used. Cultivated human colon adenocarcinoma cells (WiDr) were inoculated in stomas submucosa. Histopathological analysis, real-time reverse transcription-PCR for β-catenin, p53 and MMP2, as well as immunohistochemical analysis for p53 and β-catenin expression were conducted. Central tendency, variance analysis and the Livak delta-delta-CT method were used for statistical analysis, adopting a 5% significance level. RESULTS. All tumors from the left colon exhibited infiltrative ulceration, while in the right colon tumor growth was predominantly exophytic (67%). In the left colon, tumor growth was undifferentiated (100%), while it was moderately differentiated in the right colon (83%). In right colon tumors, MMP2, p53, and β-catenin gene expressions were higher than compared to left colon (p = 4.59354E-05, p = 0.0035179, p = 0.00093798, respectively, for MMP2, p53 and β-catenin). β-catenin and p53 results obtained by real-time polymerase chain reaction were confirmed by immunohistochemistry assay (p = 0.01 and p = 0.001, respectively, for β-catenin and p53). CONCLUSION. Left and right human colon adenocarcinomas developed in animal models have distinct phenotypes even when they have the same clonal origin. Microenvironment has influenced p53, β-catenin, and MMP2 expression in animal models of colon cancer.

The present a novel adenocarcinoma model in athymic mice.

Seven athymic mice were used. Colon diversion and distal fistula were made. Adenocarcinoma cells were inoculated in the submucosa of fistula. Tumor growth was monitored daily. Scintigraphy with 99mTc-MIBI was performed to identify the tumor.

The model of distal colon cancer is feasible. Tumor detection was possible by both, macroscopically and molecular imaging. All resections demonstrated poorly differentiated tumors. Colon obstruction occurred in one case, similarly to evolution in human tumors of distal colon.

The proposed model of distal colon cancer is feasible, allows for easy monitoring of tumoral growth by both, macroscopically and molecular imaging, and is suitable for studying the evolution of tumor with implementation of cytotoxic therapy in vivo.

The aim of this article is to study the inhibitory effects of baicalin on the growth and metastasis of orthotopic xenografts consisting of human HCT-116 colorectal cancer cells that are deficient in the mismatch repair gene hMLH1 in nude mice.

A fluorescent orthotopic transplantation model of HCT-116 cells was established. The treatment groups were administered baicalin 50 mg/kg (G2), 100 mg/kg (G3), and 200 mg/kg (G4), and the negative control group (G1) was administered 5 % NaHCO₃. The volume and vascular density of the primary tumors, body weights, survival conditions, and death rates of the mice were analyzed.

On the 14th, 21st, and 28th days, tumor volume in the treatment groups was significantly smaller than that in the control group, and the differences were statistically significant. At the end of the experiment, the survival rate of the experimental animals in the G3 was significantly higher than that in the G1 and G4 (P < 0.05). There were no significant differences in both the weights and surface vascular densities of the primary tumor and the metastatic tumor among all groups.

Baicalin had a significant inhibitory effect on the growth of nude mouse orthotopic xenografts consisting of human HCT-116 colorectal tumor cells that are deficient in the mismatch repair gene hMLH1.

Bioluminescence imaging (BLI) is an ideal tool for noninvasive, quantitative monitoring of tumor progression/regression in animal models. The effectiveness of different treatment strategies is displayed by an altered intensity of bioluminescence, demonstrating a change of the tumor burden. The aim of this study was to establish a reliable, reproducible colorectal hepatic metastases cancer animal model.

Cells of the human colon carcinoma cell line HCT-116 Luc(pos) expressing the firefly luciferase enzyme gene were used. HCT-116 Luc(pos) cells (2.5 × 10(6)) were injected through the portal vein into the liver of immunoincompetent nude mice. BLI was used to analyze intrahepatic tumor burden and growth kinetic.

HCT-116 Luc(pos) cells demonstrated a progressive and reproducible growth in the liver after intraportal injection. Four days after injection, the animals were analyzed for tumor growth by BLI, and mice without or too low bioluminescence signals were excluded (between 10% and 20% animals). HCT-116 Luc(pos) intrahepatic tumors responded successfully to different dosages (5 and 10 mg/kg) of 5-fluorouracil.

BLI is an important tool with many potential advantages for investigators. The measurement of intrahepatic tumor growth by imaging luciferase activity noninvasively provides valuable information on tumor burden and effectiveness of therapy. Thus, the presented intrahepatic metastases model based on the growth of HCT-116 Luc(pos) cells is suitable for in vivo testing of different cancer therapy strategies.

Colorectal cancer has become a major disease threatening human health. To establish animal models that exhibit the characteristics of human colorectal cancer will not only help to study the mechanisms underlying the genesis and development effectively, but also provide ideal carriers for the screening of medicines and examining their therapeutic effects. In this study, we established a stable, colon cancer nude mouse model highly expressing green fluorescent protein (GFP) for spontaneous metastasis after surgical orthotopic implantation (SOI). GFP- labeled colon cancer models for metastasis after SOI were successfully established in all of 15 nude mice and there were no surgery-related complications or deaths. In week 3, primary tumors expressing GFP were observed in all model animals under fluoroscopy and two metastatic tumors were monitored by fluorescent imaging at the same time. The tumor volumes progressively increased with time. Seven out of 15 tumor transplanted mice died and the major causes of death were intestinal obstruction and cachexia resulting from malignant tumor growth. Eight model animals survived at the end of the experiment, 6 of which had metastases (6 cases to mesenteric lymph nodes, 4 hepatic, 2 pancreatic and 1 mediastinal lymph node). Our results indicate that our GFP-labeled colon cancer orthotopic transplantation model is useful with a high success rate; the transplanted tumors exhibit similar biological properties to human colorectal cancer, and can be used for real-time, in vivo, non-invasive and dynamic observation and analysis of the growth and metastasis of tumor cells.

The work is aimed to develop a murine model of rectal cancer, which could be used to monitor lymph node metastasis development by magnetic resonance imaging (MRI) and optical imaging (OI) techniques.

Ht-29 cancer cells were directly injected into the submucosal layer of the rectum of athymic nude mice using trans-anal rectal cancer cell injection (TARCI). Thirty-six mice were inoculated with 10×10(5) cells and five mice were treated with sterile phosphate buffer solution. One to 4 weeks after cell injection, tumor growth was evaluated in vivo using T2-weighted MRI at 4.7T. A further group of animal (n=6) treated with ht-29_luc cells, with the same protocol, was monitored by optical imaging. In both groups, the presence of the primary tumor and of lymph nodes metastasis was confirmed by histology.

In all animals, primary tumors were detectable by MRI, 1 week from TARCI. After 4 weeks primary tumors showed a mean longitudinal diameter of about 2cm. All animals developed regional lymph node metastases. Others organs (e.g. lung or liver) were not affected. In fat-suppressed, T2-weighted MRI, lymph nodes appeared as small areas characterized by hyper-intense signal compared to muscle. OI permitted evaluation of the primary tumor growth in perineal region.

TARCI of ht-29 cells into the rectum of nude mice is a feasible way to obtain a easily reproducible model of regional lymph node metastases could be monitored by magnetic resonance and optical imaging techniques.

Oridonin is the active ingredient isolated from the Chinese herb Rabdosia rubescens. We used both in vivo and in vitro approaches to elucidate the underlying mechanism of the oridonin-mediated inhibition of colorectal cancer.

Two colorectal cell lines, Lovo and SW480, were treated with oridonin in solution. The effect of this treatment on the inhibition of the cell proliferation rate was determined by the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide method. The changes in gene expression that occurred in both cell lines in response to treatment with oridonin were determined via an illumine expression sensor. Additionally, a colorectal cancer colostomy implantation model was established. Animals were injected intraperitoneally with an oridonin solution.

The treatment of Lovo and SW480 cells with oridonin inhibited cell proliferation in a dose-dependent manner. Furthermore, the rate of inhibition increased with prolonged treatment. The growth rate of the colorectal cancer colostomy implantation model was significantly lower than control cells when treated with oridonin (P<0.001), which meant that oridonin treatment had a significant effect on the tumor growth rate. In the tumor model, activator protein-1 (AP-1) was the only gene found to be downregulated after oridonin treatment by the gene expression sensor. After 4 weeks of treatment, AP-1, nuclear factor-κB (NF-κB) and P38 were all found to be downregulated.

Our study confirmed the inhibitory effects of oridonin on colorectal cancer. These results indicate that the downregulation of AP-1 might be an initial response to treatment by oridonin. This regulation could, in turn, affect the expression of the NF-κB and mitogen-activated protein kinase pathways, thereby inhibiting tumor growth.

The orthotopic transplantation model of human tumor has been demonstrated to be more patient-like animal tumor model. However, observations of tumor progression and metastasis are limited by the deep location of the colon or limited deep penetration ability of fluorescence through tissue. The purpose of this study is to establish a superficial orthotopic model to allow easier real-time visualization and more sensitive monitoring of fluorescent orthotopic colon tumor. Human colon cancer HT-29 cells were transduced with a pLPCX expression retroviral vector containing green fluorescent protein and neomycin resistance genes. For superficial orthotopic transplantation model, the cecum was identified and pulled out of the peritoneal cavity, the space between the cecum and peritoneum was sutured, the cecum was pulled to subcutaneous tissue, and incision was made on the cecal serosa followed by the implantation of a 1-mm tumor tissue to the cecum. For comparison, a conventional orthotopic transplantation model was established in a separate group of mice simultaneously. When tumor sizes reached 5 mm in diameter, half the mice in each model received 5-FU treatment. Primary tumor and metastases were monitored by fluorescent imaging or caliber measurement. Tumor fluorescence was observed as early as 3 days (median time of 4.7 ± 1.3 days) post-transplantation in the superficial orthotopic transplantation model, which was much earlier than 21 days (median time of 26.2 ± 9.9 days) in conventional orthotopic transplantation model. Although tumor growth of 5-FU-treated mice in conventional orthotopic model was lower than those of the untreated mice, the difference was not significant. However, in superficial orthotopic model, tumor growth was significantly inhibited in 5-FU-treated mice relative to the untreated mice. Fluorescence imaging showed similar metastasis incidence between the superficial and conventional orthotopic transplantation models. The fluorescent superficial orthotopic transplantation colon model allows easier real-time visualization and more sensitive monitoring of tumor growth as well as convenient repeated sampling. It is a valuable orthotopic implantation model for study of colon cancer and evaluation of new anti-cancer therapy.