Natural Product Quercetin-3-methyl ether Promotes Colorectal Cancer Cell Apoptosis by Downregulating Intracellular Polyamine Signaling.

Dysregulation of cellular metabolism is a key marker of cancer, and it is suggested that metabolism should be considered as a targeted weakness of colorectal cancer. Increased polyamine metabolism is a common metabolic change in tumors. Thus, targeting polyamine metabolism for anticancer therapy, particularly polyamine blockade therapy, has gradually become a hot topic. Quercetin-3-methyl ether is a natural compound existed in various plants with diverse biological activities like antioxidant and antiaging. Here, we reported that Quercetin-3-methyl ether inhibits colorectal cancer cell viability, and promotes apoptosis in a dose-dependent and time-dependent manner. Intriguingly, the polyamine levels, including spermidine and spermine, in colorectal cancer cells were reduced upon treatment of Quercetin-3-methyl ether. This is likely resulted from the downregulation of SMOX, a key enzyme in polyamine metabolism that catalyzes the oxidation of spermine to spermidine. These findings suggest Quercetin-3-methyl ether decreases cellular polyamine level by suppressing SMOX expression, thereby inducing colorectal cancer cell apoptosis. Our results also reveal a correlation between the anti-tumor activity of Quercetin-3-methyl ether and the polyamine metabolism modulation, which may provide new insights into a better understanding of the pharmacological activity of Quercetin-3-methyl ether and how it reprograms cellular polyamine metabolism.

Gallic acid attenuates metastatic potential of human colorectal cancer cells through the miR-1247-3p-modulated integrin/FAK axis.

Colorectal cancer (CRC) exhibits highly metastatic potential even in the early stages of tumor progression. Gallic acid (GA), a common phenolic compound in plants, is known to possess potent antioxidant and anticancer activities, thereby inducing cell death or cell cycle arrest. However, whether GA reduces the invasiveness of CRC cells without inducing cell death remains unclear. Herein, we aimed to investigate the antimetastatic activity of low-dose GA on CRC cells and determine its underlying mechanism. Cell viability and tumorigenicity were analyzed by MTS, cell adhesion, and colony formation assay. Invasiveness was demonstrated using migration and invasion assays. Changes in protein phosphorylation and expression were assessed by Western blot. The involvement of microRNAs was validated by microarray analysis and anti-miR antagonist. Our findings showed that lower dose of GA (≤100 µM) did not affect cell viability but reduced the capabilities of colony formation, cell adhesion, and invasiveness in CRC cells. Cellularly, GA downregulated the cellular level of integrin αV/ß3, talin-1, and tensin and diminished the phosphorylated FAK, paxillin, Src, and AKT in DLD-1 cells. Microarray results revealed that GA increased miR-1247-3p expression, and pretreatment of anti-miR antagonist against miR-1247-3p restored the GA-reduced integrin αV/ß3 and the GA-inhibited paxillin activation in DLD-1 cells. Consistently, the in vivo xenograft model showed that GA administration inhibited tumor growth and liver metastasis derived from DLD-1 cells. Collectively, our findings indicated that GA inhibited the metastatic capabilities of CRC cells, which may result from the suppression of integrin/FAK axis mediated by miR1247-3p.

Five-FU@CuS/NH2 -UiO-66 as a drug delivery system for 5-fluorouracil to colorectal cancer cells.

In this study, copper sulfide nanoparticles (CuS-NPs), which can improve the antiproliferative properties of conventional anticancer drugs such as 5-fluorouracil (5-FU), were incorporated into the pores of amine-functionalized UiO-66 (CuS/NH2 -UiO-66). The introduced nano-drug delivery system was exerted to perform an in vitro treatment on CT-26 mouse colorectal cancer cells. The synthesized final product was labeled as 5-FU@CuS/NH2 -UiO-66 and characterized through conventional methods including X-ray diffraction (XRD), Fourier transformation infrared spectroscopy (FT-IR), Brunauer-Emmett-Teller (BET) analysis, Ultraviolet-Visible (UV-Vis) analysis, Inductively coupled plasma mass spectrometry (ICP-MS), and 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay. In contrast to 5-FU, the outcomes of the cytotoxicity assay lacked any comparable results for 5-FU@CuS/NH2 -UiO-66.

Design, Synthesis, and Biological Evaluation of N14-Amino Acid-Substituted Tetrandrine Derivatives as Potential Antitumor Agents against Human Colorectal Cancer.

As a typical dibenzylisoquinoline alkaloid, tetrandrine (TET) is clinically used for the treatment of silicosis, inflammatory pulmonary, and cardiovascular diseases in China. Recent investigations have demonstrated the outstanding anticancer activity of this structure, but its poor aqueous solubility severely restricts its further development. Herein, a series of its 14-N-amino acid-substituted derivatives with improved anticancer effects and aqueous solubility were designed and synthesized. Among them, compound 16 displayed the best antiproliferative activity against human colorectal cancer (HCT-15) cells, with an IC50 value of 0.57 µM. Compared with TET, 16 was markedly improved in terms of aqueous solubility (by 5-fold). Compound 16 significantly suppressed the colony formation, migration, and invasion of HCT-15 cells in a concentration-dependent manner, with it being more potent in this respect than TET. Additionally, compound 16 markedly impaired the morphology and motility of HCT-15 cells and induced the death of colorectal cancer cells in double-staining and flow cytometry assays. Western blot results revealed that 16 could induce the autophagy of HCT-15 cells by significantly decreasing the content of p62/SQSTM1 and enhancing the Beclin-1 level and the ratio of LC3-II to LC3-I. Further study showed that 16 effectively inhibited the proliferation, migration, and tube formation of umbilical vein endothelial cells, manifesting in a potent anti-angiogenesis effect. Overall, these results revealed the potential of 16 as a promising candidate for further preclinical studies.

Evaluation of the Anti-Cancer Potential of Rosa damascena Mill. Callus Extracts against the Human Colorectal Adenocarcinoma Cell Line.

Chemotherapy is an aggressive form of chemical drug therapy aiming to destroy cancer cells. Adjuvant therapy may reduce hazards of chemotherapy and help in destroying these cells when obtained from natural products, such as medical plants. In this study, the potential therapeutic effect of Rosa damascena callus crude extract produced in vitamin-enhanced media is investigated on colorectal cancer cell line Caco-2. Two elicitors, i.e., L-ascorbic acid and citric acid at a concentration of 0.5 g/L were added to the callus induction medium. Callus extraction and the GC-MS analysis of methanolic crude extracts were also determined. Cytotoxicity, clonogenicity, proliferation and migration of Caco-2 colorectal cancer cells were investigated using MTT cytotoxicity, colony-forming, Ki-67 flow cytometry proliferation and Migration Scratch assays, respectively. Our results indicated that L-ascorbic acid treatment enhanced callus growth parameters and improved secondary metabolite contents. It showed the least IC50 value of 137 ug/mL compared to 237 ug/mL and 180 ug/mL in the citric acid-treated and control group. We can conclude that R. damascena callus elicited by L-ascorbic acid improved growth and secondary metabolite contents as well as having an efficient antiproliferative, anti-clonogenic and anti-migratory effect on Caco-2 cancer cells, thus, can be used as an adjuvant anti-cancer therapy.

Synergetic Effect of Tumor Treating Fields and Zinc Oxide Nanoparticles on Cell Apoptosis and Genotoxicity of Three Different Human Cancer Cell Lines.

Cancer remains a leading cause of death worldwide, despite extraordinary progress. So, new cancer treatment modalities are needed. Tumor-treating fields (TTFs) use low-intensity, intermediate-frequency alternating electric fields with reported cancer anti-mitotic properties. Moreover, nanomedicine is a promising therapy option for cancer. Numerous cancer types have been treated with nanoparticles, but zinc oxide nanoparticles (ZnO NPs) exhibit biocompatibility. Here, we investigate the activity of TTFs, a sub-lethal dose of ZnO NPs, and their combination on hepatocellular carcinoma (HepG2), the colorectal cancer cell line (HT-29), and breast cancer cell lines (MCF-7). The lethal effect of different ZnO NPs concentrations was assessed by sulforhodamine B sodium salt assay (SRB). The cell death percent was determined by flow cytometer, the genotoxicity was evaluated by comet assay, and the total antioxidant capacity was chemically measured. Our results show that TTFs alone cause cell death of 14, 8, and 17% of HepG2, HT-29, and MCF-7, respectively; 10 µg/mL ZnO NPs was the sub-lethal dose according to SRB results. The combination between TTFs and sub-lethal ZnO NPs increased the cell death to 29, 20, and 33% for HepG2, HT-29, and MCF-7, respectively, without reactive oxygen species increase. Increasing NPs potency using TTFs can be a novel technique in many biomedical applications.

SERS Quantification of Galunisertib Delivery in Colorectal Cancer Cells by Plasmonic-Assisted Diatomite Nanoparticles.

The small molecule Galunisertib (LY2157299, LY) shows multiple anticancer activities blocking the transforming growth factor-ß1 receptor, responsible for the epithelial-to-mesenchymal transition (EMT) by which colorectal cancer (CRC) cells acquire migratory and metastatic capacities. However, frequent dosing of LY can produce highly toxic metabolites. Alternative strategies to reduce drug side effects can rely on nanoscale drug delivery systems that have led to a medical revolution in the treatment of cancer, improving drug efficacy and lowering drug toxicity. Here, a hybrid nanosystem (DNP-AuNPs-LY@Gel) made of a porous diatomite nanoparticle decorated with plasmonic gold nanoparticles, in which LY is retained by a gelatin shell, is proposed. The multifunctional capability of the nanosystem is demonstrated by investigating the efficient LY delivery, the enhanced EMT reversion in CRCs and the intracellular quantification of drug release with a sub-femtogram resolution by surface-enhanced Raman spectroscopy (SERS). The LY release trigger is the pH sensitivity of the gelatin shell to the CRC acidic microenvironment. The drug release is real-time monitored at single-cell level by analyzing the SERS signals of LY in CRC cells. The higher efficiency of LY delivered by the DNP-AuNPs-LY@Gel complex paves the way to an alternative strategy for lowering drug dosing and consequent side effects.

Simultaneous silencing Aurora-A and UHRF1 inhibits colorectal cancer cell growth through regulating expression of DNMT1 and STAT1.

Aurora-A has attracted a great deal of interest as a potential therapeutic target for patients with CRC. However, the outcomes of inhibitors targeting Aurora-A are not as favorable as expected, and the basis behind the ineffectiveness remains unknown. Here, we found that signal transducer and activator of transcription 1 (STAT1) was highly expressed in colorectal cancer (CRC) xenograft mouse models that were resistant to alisertib, an Aurora-A inhibitor. Unexpectedly, we found that alisertib disrupted Aurora-A binding with ubiquitin-like with plant homeodomain and ring finger domain 1 (UHRF1), leading to UHRF1 mediated ubiquitination and degradation of DNA methyltransferase 1 (DNMT1), which in turn resulted in demethylation of CpG islands of STAT1 promoter and STAT1 overexpression. Simultaneous silencing Aurora-A and UHRF1 prevented STAT1 overexpression and effectively inhibited CRC growth. Hence, concomitant targeting Aurora-A and UHRF1 can be a promising therapeutic strategy for CRC.

Synthesis, CYP24A1-Dependent Metabolism and Antiproliferative Potential against Colorectal Cancer Cells of 1,25-Dihydroxyvitamin D2 Derivatives Modified at the Side Chain and the A-Ring.

Experimental data indicate that low-calcemic vitamin D derivatives (VDDs) exhibit anticancer properties, both in vitro and in vivo. In our search for a vitamin D analog as potential anticancer agent, we investigated the influence of chirality in the side chain of the derivatives of 1,25-dihydroxyergocalciferol (1,25D2) on their activities. In this study, we synthesized modified analogs at the side chain and the A-ring, which differed from one another in their absolute configuration at C-24, namely (24S)- and (24R)-1,25-dihydroxy-19-nor-20a-homo-ergocalciferols (PRI-5105 and PRI-5106, respectively), and evaluated their activity. Unexpectedly, despite introducing double-point modifications, both analogs served as very good substrates for the vitamin D-hydroxylating enzyme. Irrespective of their absolute C-24 configuration, PRI-5105 and PRI-5106 showed relatively low resistance to CYP24A1-dependent metabolic deactivation. Additionally, both VDDs revealed a similar antiproliferative activity against HT-29 colorectal cancer cells which was higher than that of 1,25D3, the major biologically active metabolite of vitamin D. Furthermore, PRI-5105 and PRI-5106 significantly enhanced the cell growth-inhibitory activity of 5-fluorouracil on HT-29 cell line. In conclusion, although the two derivatives showed a relatively high anticancer potential, they exhibited undesired high metabolic conversion.

Loss of HACE1 promotes colorectal cancer cell migration via upregulation of YAP1.

Colorectal cancer (CRC) is the third-leading cause of cancer mortality worldwide. HACE1 function as a tumor-suppressor gene and is downregulated in several kinds of cancers. However, the distribution and clinical significance of HACE1 in CRC is still not clarified. In this study, we found that the HACE1 expression is greatly downregulated in CRC tissues and cell lines. Moreover, the HACE1 expression was significantly associated with inhibition of CRC cell proliferation, metastasis, and invasion. HACE1 inhibited epithelial-mesenchymal transition in CRC cells. Furthermore, we found that HACE1 altered the protein expression of the Hippo pathway by downregulation of YAP1. HACE1 suppresses the invasive ability of CRC cells by negatively regulating the YAP1 pathway. Our data indicates that HACE1 directly targets YAP1 and induces downregulation of YAP1, thereby increasing the activity of the Hippo pathway. In summary, these findings demonstrated that HACE1-YAP1 axis had an important part in the CRC development and progression.

Dynamics of oxygen level-driven regulators in modulating autophagy in colorectal cancer cells.

Colorectal cancer is a common cancer with metachronous distant metastases still threatening overall survival. Tumor oxygen level influences tumor radiosensitivity in relation to autophagy and apoptosis. The objective of this study is to evaluate the expression and interaction between multiple key regulators in different oxygen levels. Human colorectal adenocarcinoma HT-29 cells were cultured in 1% or 10% oxygen level and irradiated by 2 Gy with different incubation time. Autophagy key regulators, AMPK, HIFs and JNK were evaluated by Western blot. Sequential autophagy key regulator activation was observed in the order of AMPK, HIF-1α, HIF-2α and JNK. 10% oxygen level could promote autophagy with similar degree of autophagy activation as 1% oxygen level in 48-h while irradiation could slightly inhibit autophagy. The results of this study supported prior evaluation of oxygen level and autophagy regulators for improving treatment efficacy and indicated the possible directions in developing individualized radiotherapy by selective targeting of hypoxic regions.

Enhancement of hydrosolubility and in vitro antiproliferative properties of chalcones following encapsulation into ß-cyclodextrin/cellulose-nanocrystal complexes.

This paper describes the preparation of two chalcone/ß-cyclodextrin/cellulose-nanocrystals complexes and the study of their antiproliferative activities against two colorectal and two prostatic cancer cell lines. The aim of this work was to enhance hydrosolubility of chalcones thanks to the hydrophilic character of cellulose nanocrystals. These latter were linked, through ionic interactions, to a cationic derivative of ß-cyclodextrins whose lipophilic cavity allowed the encapsulation of hydrophobic chalcones: 3-hydroxy-3',4,4',5'-tetramethoxychalcone (1) and 3',4,4',5'-tetramethoxychalcone (2). First, we showed that encapsulation allowed hydrosolubilization of chalcones. Then, chalcone/ß-cyclodextrin/cellulose-nanocrystals complexes demonstrated enhanced in vitro antiproliferative activities, compared to the corresponding free-chalcones.

CXCR3 expression in colorectal cancer cells enhanced invasion through preventing CXCR4 internalization.

One of the major causes of death in colorectal cancer (CRC) is invasion and metastasis. Better understanding of the molecular mechanism of CRC invasion and metastasis is essential in developing effective cancer therapies. Cooperative effect of CXCR3 and CXCR4 plays a crucial role in regulating CRC invasion. In present study, we discovered that CRC cells expressing higher levels of CXCR3 and CXCR4 were more invasive. Additionally, CXCR3 formed heteromers with CXCR4 and retained CXCR4 on cell surface. CXCR3 knockdown reduced surface CXCR4 expression and partially inhibited CRC cell invasion. On the contrary, CXCR3 overexpression enhanced surface CXCR4 abundance and promoted CRC cell invasion. Further research indicated that CXCR3-A isoform was responsible for increased CXCR4 surface expression and CRC cell invasion. However, CXCR3-A overexpression without CXCR4 expression did not cause CRC cell invasion, which suggested that CXCR3-A indirectly affect cell invasion through regulating CXCR4. Taken together, CXCR3 enhanced CXCR4 function in CRC cell invasion through forming heteromers with CXCR4 on cell surface and prevent CXCR4 internalization. Therefore, targeting CXCR3 could be a promising strategy for clinical treatment of CRC cell invasion and metastasis.

Evaluation of selected commercial pharmacotherapeutic drugs as potential pancreatic lipase inhibitors and antiproliferative compounds.

In this study, 15 commercial acidic drugs have been evaluated for pancreatic lipase (PL) inhibitory activity using an in vitro spectrophotometric method. The acidity was the basis of selection, since most PL inhibitors exhibit acidic groups and high lipophilicity. Orlistat was the robust reference agent for potency and efficacy determinations. In comparison to the cisplatin, the evaluation of the antineoplastic activities of selected drugs in a panel of colorectal cancer cell lines (HT-29, HCT-116, SW620, CACO-2, and SW480) and normal periodontal ligament fibroblasts for safety examination was performed by using a sulforhodamine procuring ascorbic acid as a reference in diphenyl-2-picryl-hydrazyl assay of radical scavenging properties was performed. This research revealed three highly acidic pharmacological classes with reasonable PL inhibitory activity in comparison to orlistat out of 15 selected drugs, namely sulfonylureas, fluoroquinolones, and proton pump inhibitors. Docking studies supported the hypothesis of a selection based on acidity, since it showed that the sulfonamide acid group (glyburide) is a remarkably potent interacting group with the enzyme. Failing to fulfill other structure-activity relationship requirements (lipophilicity) led to weak activity. Since the drugs are of different chemical classes with unknown mechanisms, they showed diverse antiproliferative activity. Some drugs such as atorvastatin and gemifloxacin showed higher antiproliferative activity than cisplatin with high-safety profiles against SW620 and SW480 cell lines, respectively, whereas lansoprazole and clopidogrel revealed comparable activity to cisplatin against HCT-116 and SW480, respectively. Unfortunately, selected tested drugs exhibited negligible radical scavenging activity versus ascorbic acid. Hit, Lead & Candidate Discovery.

Nisin, a potent bacteriocin and anti-bacterial peptide, attenuates expression of metastatic genes in colorectal cancer cell lines.

Colorectal cancer is the third most common cause of cancer-related death in the world which genetic and environmental agents are responsible for cancer. When cells detach from the tumor and invade surrounding tissues, the tumor is malignant and may form secondary tumors at other locations in a process called metastasis. Probiotics are the largest group of inhabitation bacteria in the colon. Gut microbiota has a central role in prevented the risk colon cancer. Probiotics are beneficial microorganisms, like Lactic acid bacteria and Lactobacilli bacteria which are using in the dairy industry. Probiotics nisin are having the most important category of safe usage. In this study LS180, SW48, HT29 and Caco2 was cultured and treated with different dose of nisin. Cell proliferation was assayed with MTT. The expression of CEA, CEAM6 and MMP2F genes was analyzed with Real-time PCR. Protein expression of CEA was evacuated with ELISA. Our result was shown that the 40-50 IU/mL nisin could suppress proliferation of LS180. Cell proliferation of SW48, HT29, Caco2 cells was decreased in 250-350 IU/mL concentration of nisin. The gene expression of CEA, CEAM6, MMP2F was significantly down-regulated with nisin treatment (p < 0.001, p < 0.01). Also, after cells treated with nisin, CEA protein expression was down regulated (p < 0.01). In conclusion, nisin could suppressed metastatic process via down-regulation of CEA, CEAM6, MMP2F, MMP9F genes. We suggested the new treatment strategies beyond Probiotics, which play a role in the prevention local tumor invasion, metastasis and recurrence.

Multi-omics of 34 colorectal cancer cell lines - a resource for biomedical studies.

BACKGROUND: Colorectal cancer (CRC) cell lines are widely used pre-clinical model systems. Comprehensive insights into their molecular characteristics may improve model selection for biomedical studies. METHODS: We have performed DNA, RNA and protein profiling of 34 cell lines, including (i) targeted deep sequencing (n = 612 genes) to detect single nucleotide variants and insertions/deletions; (ii) high resolution DNA copy number profiling; (iii) gene expression profiling at exon resolution; (iv) small RNA expression profiling by deep sequencing; and (v) protein expression analysis (n = 297 proteins) by reverse phase protein microarrays. RESULTS: The cell lines were stratified according to the key molecular subtypes of CRC and data were integrated at two or more levels by computational analyses. We confirm that the frequencies and patterns of DNA aberrations are associated with genomic instability phenotypes and that the cell lines recapitulate the genomic profiles of primary carcinomas. Intrinsic expression subgroups are distinct from genomic subtypes, but consistent at the gene-, microRNA- and protein-level and dominated by two distinct clusters; colon-like cell lines characterized by expression of gastro-intestinal differentiation markers and undifferentiated cell lines showing upregulation of epithelial-mesenchymal transition and TGFß signatures. This sample split was concordant with the gene expression-based consensus molecular subtypes of primary tumors. Approximately » of the genes had consistent regulation at the DNA copy number and gene expression level, while expression of gene-protein pairs in general was strongly correlated. Consistent high-level DNA copy number amplification and outlier gene- and protein- expression was found for several oncogenes in individual cell lines, including MYC and ERBB2. CONCLUSIONS: This study expands the view of CRC cell lines as accurate molecular models of primary carcinomas, and we present integrated multi-level molecular data of 34 widely used cell lines in easily accessible formats, providing a resource for preclinical studies in CRC.

Design and multi-step synthesis of chalcone-polyamine conjugates as potent antiproliferative agents.

The aim of this study is to synthesize chalcone-polyamine conjugates in order to enhance bioavailability and selectivity of chalcone core towards cancer cells, using polyamine-based vectors. 3-hydroxy-3',4,4',5'-tetramethoxychalcone (1) and 3',4,4',5'-tetramethoxychalcone (2) were selected as parent chalcones since they were found to be efficient anti-proliferative agents on various cancer cells. A series of ten chalcone-polyamine conjugates was obtained by reacting carboxychalcones with different polyamine tails. Chalcones 1 and 2 showed a strong cytotoxic activity against two prostatic cancer (PC-3 and DU-145) and two colorectal cancer (HT-29 and HCT-116) cell lines. Then, chalcone-spermine conjugates 7d and 8d were shown to be the most active of the series and could be considered as promising compounds for colon and prostatic cancer adjuvant therapy.

miR-224 Controls Human Colorectal Cancer Cell Line HCT116 Proliferation by Targeting Smad4.

Background: Better understanding the molecular mechanisms responsible for the genesis and progression of colorectal cancer would help advance the novel therapeutics. miR-224 has been identified to be elevated in colorectal cancer and promote human colorectal cancer cell line SW480 proliferation and invasion. However, the effect of miRNAs on cancer cell proliferation could be significantly changeable among different cell lines. HCT116 is a commonly used cell line for colorectal cancer study and the target gene responsible for the function of miR-224 in its proliferation is unclear. Methods: miR-224 expression was determined by quantitative reverse transcription polymerase chain reactions (PCRs) in human colorectal cancer tissues compared with their corresponding matched peritumoral tissues. HCT116 cell viability and cell proliferation were determined by CCK-8, EdU incorporation assays and flow cytometry for cell cycle. Target gene of miR-224 was confirmed by Western blots and siRNA for Smad4. Results: miR-224 was significantly increased by 29.49 fold in colorectal cancer tissues compared with their corresponding matched peritumoral tissues based on 12 colorectal cancer patients. miR-224 mimic significantly increased HCT116 cell viability, EdU positive cells rate, and decreased G1 phase cell population and increased S phase cell population. miR-224 inhibitor had opposite effects. Smad4 could be negatively regulated by miR-224 in HCT116 cells and was responsible for its effects in proliferation. Conclusion: miR-224 mediates HCT116 cell proliferation by targeting Smad4.

ABCG2 is required for self-renewal and chemoresistance of CD133-positive human colorectal cancer cells.

There is increasing evidence supporting the cancer stem cell (CSC) hypothesis, which suggests that a population of tumor cells with stem cell characteristics is responsible for tumor growth, resistance, and recurrence as well as drug resistance. In colorectal cancer, the CD133 antigen defines distinct cell subpopulations that are rich in tumor-initiating cells; however, the drug resistance properties of these CD133-positive cells have not been well defined. The breast cancer resistance protein (BCRP)/ATP-binding cassette subfamily G member 2 (ABCG2) is present on the plasma membrane of many types of human cancer cells and contributes to multidrug resistance during chemotherapy. The results of the present study showed that ABCG2 is expressed in CD133-positive CSCs from human colorectal tumors. Furthermore, the downregulation of ABCG2 expression inhibited the self-renewal capacity of these cells, and significantly enhanced the efficacy of chemotherapy-induced apoptosis in LS174T colon adenocarcinoma cells and CD133-positive colorectal carcinoma cells. Together, these data show that ABCG2 expression correlates with the presence of CD133-positive cancer cells, and thus is a possible therapeutic target for colorectal cancer.

The chemokines CCR1 and CCRL2 have a role in colorectal cancer liver metastasis.

C-C chemokine receptor type 1 (CCR1) and chemokine C-C motif receptor-like 2 (CCRL2) have not yet been sufficiently investigated for their role in colorectal cancer (CRC). Here, we investigated their expression in rat and human CRC samples, their modulation of expression in a rat liver metastasis model, as well as the effects on cellular properties resulting from their knockdown. One rat and five human colorectal cancer cell lines were used. CC531 rat colorectal cells were injected via the portal vein into rats and re-isolated from rat livers after defined periods. Following mRNA isolation, the gene expression was investigated by microarray. In addition, all cell lines were screened for mRNA expression of CCR1 and CCRL2 by reverse transcription polymerase chain reaction (RT-PCR). Cell lines with detectable expression were used for knockdown experiments; and the respective influence was determined on the cells' proliferation, scratch closure, and colony formation. Finally, specimens from the primaries of 50 patients with CRC were monitored by quantitative RT-PCR for CCR1 and CCRL2 expression levels. The microarray studies showed peak increases of CCR1 and CCRL2 in the early phase of liver colonization. Knockdown was sufficient at mRNA but only moderate at protein levels and resulted in modest but significant inhibition of proliferation (p < 0.05), scratch closure, and colony formation (p < 0.05). All human CRC samples were positive for CCR1 and CCRL2 and showed a significant pairwise correlation (p < 0.0004), but there was no correlation with tumor stage or age of patients. In summary, the data point to an important role of CCR1 and CCRL2 under conditions of organ colonization and both chemokine receptors qualify as targets of treatment during early colorectal cancer liver metastasis.