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/β3, 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/β3 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.

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.

Anti-Tumor Efficacy of Oleuropein-Loaded ZnO/Au Mesoporous Silica Nanoparticle in 5-FU-Resistant Colorectal Cancer Cells

Purpose

5-fluorouracil (5-FU) is a first-line chemotherapeutic agent used to treat colorectal cancer (CRC). However, 5-FU induces drug resistance and activation of cancer stem cells (CSCs). In the present study, we designed a novel biocompatible nanomedicine system with high efficacy and biocompatibility by synthesizing mesoporous silica nanoparticle (MSN)-structured ZnO and gold ions. Oleuropein (OLP) is a phenolic compound derived from olive leaves that exerts anti-cancer effects. Therefore, we synthesized OLP-loaded ZnO/Au MSNs (ZnO/Au/OLP MSNs) and examined their anti-cancer effects on 5-FU-resistant CRC cells.

Methods

ZnO/Au MSNs were synthesized and functionalized, and their physical and chemical compositions were characterized using UV-visible spectroscopy, dynamic light scattering, and transmission electron microscopy (TEM). Their effects were assessed in terms of cellular proliferation capacity, migration and invasion ability, colony-forming ability, spheroid-forming ability, reactive oxygen species (ROS) production, and mitochondrial membrane depolarization.

Results

ZnO/Au MSNs were mostly composed of various ions containing ZnO and gold ions, had a spheroid phenotype, and exhibited no cytotoxicity. ZnO/Au/OLP MSNs reduced cell viability and CSC formation and induced apoptosis of 5-FU-resistant CRC cells via necrosis via ROS accumulation and DNA fragmentation.

Conclusion

ZnO/Au/OLP MSNs exhibited anti-cancer activity by upregulating necrosis. These results revealed that ZnO/Au/OLP MSNs are a novel drug delivery system for 5-FU CRC therapy.

KRAS-mutant colorectal cancer cell lines cause a prothrombotic state through the upregulation of thrombin: experimental study

Background

The KRAS genotype status is strongly associated with a prothrombotic state in colorectal cancer, and hypercoagulability and cancer-related thrombosis are among the significant events leading to poor prognosis. However, this correlation has not been confirmed at the cellular level. This study aimed to assess the maximum platelet aggregation rate and thrombin expression induced by colorectal cancer cells under different KRAS genotypes.

Materials and methods

Platelet aggregation rate assay and western blotting analysis were used to detect platelet aggregation and thrombin expression induced by four colorectal cancer cells with different KRAS genotypes, including RKO, HCT116, SW480, and SW620. FVIIa/tissue factor and thrombin inhibitors were added to explore changes in platelet aggregation rates induced by colorectal cancer cells and the association between KRAS genotype status and hypercoagulable state.

Results

KRAS-mutant cells were more likely to increase maximal platelet aggregation, with RKO, HCT116, SW480, and SW620 inducing 34.7%, 55.4%, 44.4%, and 63.8% of platelet aggregation, respectively. The maximum platelet aggregation rate was higher in the metastatic rectal cancer tumour strain SW620 than in the primary rectal cancer strain SW480. RKO cells had lower thrombin expression than the other three cells. Furthermore, the addition of thrombin inhibitors caused a more significant decrease in the platelet aggregation rate in KRAS-mutant cell lines compared to KRAS wild-type cell lines.

Conclusion

Compared to KRAS wild-type colorectal cancer cells, KRAS-mutant colorectal cancer cell lines were more likely to be hypercoagulable through the upregulation of thrombin expression, which was mainly achieved through the TF-thrombin pathway.

Lactobacillus plantarum-derived metabolites sensitize the tumor-suppressive effects of butyrate by regulating the functional expression of SMCT1 in 5-FU-resistant colorectal cancer cells

A critical obstacle to the successful treatment of colorectal cancer (CRC) is chemoresistance. Chemoresistant CRC cells contribute to treatment failure by providing a mechanism of drug lethargy and modifying chemoresistance-associated molecules. The gut microbiota provide prophylactic and therapeutic effects by targeting CRC through anticancer mechanisms. Among them, Lactobacillus plantarum contributes to the health of the host and is clinically effective in treating CRC. This study confirmed that 5-fluorouracil (5-FU)-resistant CRC HCT116 (HCT116/5FUR) cells acquired butyrate-insensitive properties. To date, the relationship between 5-FU-resistant CRC and butyrate resistance has not been elucidated. Here, we demonstrated that the acquisition of butyrate resistance in HCT116/5FUR cells was strongly correlated with the inhibition of the expression and function of SMCT1, a major transporter of butyrate in colonocytes. L. plantarum-cultured cell-free supernatant (LP) restored the functional expression of SMCT1 in HCT116/5FUR cells, leading to butyrate-induced antiproliferative effect and apoptosis. These results suggest that LP has a synergistic effect on the SMCT1/butyrate-mediated tumor suppressor function and is a potential chemosensitizer to overcome dual 5-FU and butyrate resistance in HCT116 cells.

Inhibition of CNOT2 Induces Apoptosis via MID1IP1 in Colorectal Cancer Cells by Activating p53

CCR4-NOT transcription complex subunit 2 (CNOT2), a subunit of the CCR4-NOT complex, has been described in cancer progression. The CNOT complex plays an important role in multiple cellular functions. Recent studies in our laboratory showed that CNOT2 promotes breast cancer cell proliferation and angiogenesis. In addition, CNOT2 signals are critically related to apoptosis induced by atorvastatin in lung cancer cells. Furthermore, depletion of CNOT2 was shown to enhance the antitumor effect of midline 1 interacting protein 1 (MID1IP1) depletion, thus inhibiting c-Myc expression in liver cancer cells. However, the molecular mechanisms related to its oncogenic role remain unclear. Herein, for the first time, we report that CNOT2 inhibition can induce apoptosis in colorectal cancer cells by activating p53. Inhibition of CNOT2 markedly induced apoptosis in various cancer cells like that of the wild-type p53. Furthermore, inhibition of CNOT2 elongated p53 s half-life. Previously, our laboratory demonstrated that MID1IP1 promoted colocalization with c-Myc mediated by CNOT2. Interestingly, inhibition of CNOT2 cannot induce p53 expression without MID1IP1 or apoptosis in cancer cells. In conclusion, our results demonstrate that CNOT2 inhibition induces apoptosis through MID1IP1 by activating p53.

Cabazitaxel suppresses colorectal cancer cell growth via enhancing the p53 antitumor pathway

There were approximately 1.93 million new cases and 940 000 deaths from colorectal cancer in 2020. The first‐line chemotherapeutic drugs for colorectal cancer are mainly based on 5‐fluorouracil, although the use of these drugs is limited by the development of drug resistance. Consequently, there is a need for novel chemotherapeutic drugs for the efficient treatment of colorectal cancer patients. In the present study, we screened 160 drugs approved by the Food and Drug Administration and identified that cabazitaxel (CBT), a microtube inhibitor, can suppress colony formation and cell migration of colorectal cancer cells in vitro. CBT also induces G2/M phase arrest and apoptosis of colorectal cancer cells. Most importantly, it inhibits the growth of colorectal cancer cell xenograft tumors in vivo. Transcriptome analysis by RNA‐sequencing revealed that Tub family genes are abnormally expressed in CBT‐treated colorectal cancer cells. The expression of several p53 downstream genes that are associated with cell cycle arrest, apoptosis, and inhibition of angiogenesis and metastasis is induced by CBT in colorectal cancer cells. Overall, our results suggests that CBT suppresses colorectal cancer by upregulating the p53 pathway, and thus CBT may have potential as an alternative chemotherapeutic drug for colorectal cancer.

Adenine Inhibits the Invasive Potential of DLD-1 Human Colorectal Cancer Cell via the AMPK/FAK Axis

Tumor metastasis is a major cause of death of patients with colorectal cancer (CRC). Our previous findings show that adenine has antiproliferation activity against tumor cells. However, whether adenine reduces the invasiveness of DLD-1 and SW480 CRC cells has not been thoroughly explored. In this study, we aimed to explore the effects of adenine on the invasion potential of DLD-1 cells. Our findings showed that adenine at concentrations of ≤200 μM did not influence the cell viability of DLD-1 and SW480 CRC cells. By contrast, adenine reduced the migratory potential of the CRC cells. Moreover, it decreased the invasion capacity of the CRC cells in a dose-dependent manner. We further observed that adenine downregulated the protein levels of tissue plasminogen activator, matrix metalloproteinase-9, Snail, TWIST, and vimentin, but upregulated the tissue inhibitor of metalloproteinase-1 expression in DLD-1 cells. Adenine decreased the integrin αV level and reduced the activation of integrin-associated signaling components, including focal adhesion kinase (FAK), paxillin, and Src in DLD-1 cells. Further observations showed that adenine induced AMP-activated protein kinase (AMPK) activation and inhibited mTOR phosphorylation in DLD-1 cells. The knockdown of AMPK restored the reduced integrin αV level and FAK/paxillin/Src signaling inhibited by adenine in DLD-1 cells. Collectively, these findings reveal that adenine reduces the invasion potential of DLD-1 cells through the AMPK/integrin/FAK axis, suggesting that adenine may have anti-metastatic potential in CRC cells.

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-β1 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.

Prion Protein of Extracellular Vesicle Regulates the Progression of Colorectal Cancer

Simple Summary

Cellular prion protein (PrP^C) are overexpressed in cancers and related to cancer proliferation, invasion, metastasis, and drug resistance. The aim of our study was to investigate the role of PrP^C-expressing exosomes regulating the colorectal cancer cells (CRC) behavior and tumor progression. We confirmed the increased sphere formation, expression of cancer initiating genes, motility, and tumor growth by hypoxic exosomes. Also, PrP^C-expressing exosomes induced the microenvironment of metastasis via increase of endothelial permeability and angiogenic cytokine secretion. The treatment of anti-PrP^C and 5-fluorouracil decreased the tumor progression. Targeting PrP^C is an effective therapeutic strategy in cancer therapy.

Abstract

Colorectal cancer (CRC) is one of the leading causes of cancer-related death due to its aggressive metastasis in later stages. Although there is a growing interest in the tumorigenic role of cellular prion protein (PrP^C) in the process of metastasis, the precise mechanism behind the cellular communication involving prion proteins remains poorly understood. This study found that hypoxic tumor microenvironment increased the PrP^C-expressing exosomes from CRC, and these exosomes regulate the CRC cell behavior and tumor progression depending on the expression of PrP^C. Hypoxic exosomes from CRC cells promoted sphere formation, the expression of tumor-inducing genes, migration, invasion, and tumor growth. Furthermore, these exosomes increased endothelial permeability, migration, invasion, and angiogenic cytokine secretion. These effects were associated with PrP^C expression. Application of anti-PrP^C antibody with 5-fluorouracil significantly suppressed the CRC progression in a murine xenograft model. Taken together, these findings indicate that PrP-expressing exosomes secreted by hypoxic CRC cells are a key factor in the tumorigenic CRC-to-CRC and CRC-to-endothelial cell communication. Significance: These findings suggest that inhibiting PrP^C in hypoxic exosomes during chemotherapy may be an effective therapeutic strategy in colorectal cancer.

Butyrate Suppresses Glucose Metabolism of Colorectal Cancer Cells via GPR109a-AKT Signaling Pathway and Enhances Chemotherapy

Glycolysis inhibitors are promising therapeutic drugs for tumor treatment, which target the uniquely elevated glucose metabolism of cancer cells. Butyrate is a critical product of beneficial microbes in the colon, which exerts extraordinary anti-cancer activities. In particular, butyrate shows biased inhibitory effects on the cell growth of cancerous colonocytes, whereas it is the major energy source for normal colonocytes. Besides its roles as the histone deacetylases (HDACs) inhibitor and the ligand for G-protein coupled receptor (GPR) 109a, the influence of butyrate on the glucose metabolism of cancerous colonocytes and the underlying molecular mechanism are not fully understood. Here, we show that butyrate markedly inhibited glucose transport and glycolysis of colorectal cancer cells, through reducing the abundance of membrane GLUT1 and cytoplasmic G6PD, which was regulated by the GPR109a-AKT signaling pathway. Moreover, butyrate significantly promoted the chemotherapeutical efficacy of 5-fluorouracil (5-FU) on cancerous colonocytes, with exacerbated impairment of DNA synthesis efficiency. Our findings provide useful information to better understand the molecular basis for the impact of butyrate on the glucose metabolism of colorectal cancer cells, which would promote the development of beneficial metabolites of gut microbiota as therapeutical or adjuvant anti-cancer drugs.

GABA-producing Lactobacillus plantarum inhibits metastatic properties and induces apoptosis of 5-FU-resistant colorectal cancer cells via GABAB receptor signaling

5-Fluorouracil (5-FU) is an essential drug in systemic chemotherapy treatments for colorectal cancer (CRC). Despite the development of several treatment strategies over the past decades, the patient benefits of 5-FU-based therapies have been compromised by the development of chemoresistance. Differences in treatment responses among CRC patients may be due to genetic and epigenetic factors unique to individuals. Therefore, important factors for realizing personalized medicine are to accurately understand the causes and mechanisms of drug resistance to 5-FU-based therapies and to identify and validate prognostic biomarkers. Gut microbes that interact directly with the host contribute to human health and cancer control. Lactobacillus plantarum, in particular, has the potential to be a therapeutic agent by producing bioactive compounds that may benefit the host. Here, we investigated the gamma-aminobutyric acid (GABA) and GABAB receptor (GABABR)-dependent signaling pathway as a treatment option for 5-FU-resistant HT-29 cells. GABA-producing L. plantarum activates anti-proliferative, anti-migration, and anti-invasion effects against 5-FU-resistant HT-29 cells. The inhibitory effects of GABA-producing L. plantarum are mediated via GABABR. Activated GABABR induces apoptosis through the inhibition of cAMP-dependent signaling pathways and cellular inhibitor of apoptosis protein 2 (cIAP2) expression. Thus, the GABAergic system has potential in 5-FU-resistant HT-29 cells as a predictive biomarker. In addition, GABA-producing L. plantarum is promising as an adjuvant treatment for 5-FU-resistant CRC, and its intervention in neurobiological signaling imply new possibilities for chemoprevention and the treatment of colon cancer-related diseases.

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.

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.

A novel RON splice variant lacking exon 2 activates the PI3K/AKT pathway via PTEN phosphorylation in colorectal carcinoma cells

Abnormal expression of the Recepteur d'Origine Nantais (RON) receptor tyrosine kinase is accompanied by the generation of multiple splice or truncated variants, which mediate many critical cellular functions that contribute to tumor progression and metastasis. Here, we report a new RON splice variant in the human colorectal cancer (CRC) cell line HT29. This variant is a 165 kda protein generated by alternative pre-mRNA splicing that eliminates exon 2, causing an in-frame deletion of 63 amino acids in the extracellular domain of the RON β chain. The deleted transcript was a single chain expressed in the intracellular compartment. Although it lacked tyrosine phosphorylation activity, the RONΔ165E2 variant could phosphorylate phosphatase and tensin homolog (PTEN), thereby activating the PI3K/AKT pathway. In addition, in vitro and in vivo experiments showed that the RONΔ165E2 promoted cell migration and tumor growth. Finally, in an investigation of 67 clinical CRC samples, the variant was highly expressed in about 58% of the samples, and was positively correlated with the invasive depth of the tumor (P < 0.05). These results demonstrate that the novel RONΔ165E2 variant promoted tumor progression while activating the PI3K/AKT pathway via PTEN phosphorylation.

Rosiglitazone diminishes the high-glucose-induced modulation of 5-fluorouracil cytotoxicity in colorectal cancer cells

Colorectal cancer (CRC) is the third most leading cause of morbidity and mortality throughout the world. 5-fluorouracil (5-FU), which is often administrated to disrupt carcinogenesis, was found to elevate blood glucose level among CRC patients. Thus, this study was conducted to evaluate the influence of rosiglitazone on antiproliferative effect of 5-FU using cellular model. Two human colonic carcinoma cell lines (HCT 116 and HT 29) were cultured in the presence of 5-FU, rosiglitazone or in combination under normal and high glucose concentration. The drug cytotoxicity was evaluated using the MTT assay whereas the assessment of cell cycle was carried out using the flow cytometry technique. Combination index (CI) method was used to determine the drug interaction between rosiglitazone and 5-FU. High glucose diminished the cytotoxic effect of 5-FU but at a high drug dosage, this effect could be overcome. Cell cycle analysis demonstrated that 5-FU and rosiglitazone caused G1-phase arrest and S-phase arrest, respectively. CI values indicated that rosiglitazone exerted synergistic effect on 5-FU regardless of glucose levels. This study is the first to demonstrate the influence of rosiglitazone on cytotoxicity of 5-FU under normal or high glucose level. Rosiglitazone may be a promising drug for enhancing the efficacy of 5-FU in the treatment of CRC associated with hyperglycemia.

Apigenin suppresses colorectal cancer cell proliferation, migration and invasion via inhibition of the Wnt/β-catenin signaling pathway

Abnormal activation of the Wnt/β-catenin signaling pathway has a significant role in human tumorigenesis. The search for potential anticancer drugs has included widespread screening of inhibitors of the Wnt signaling pathway. Recently, one of the most common flavonoids, apigenin, demonstrated potential anti-tumor effects on multiple human cancer cell lines, with low cytotoxicity and no mutagenic activity. However, the association between apigenin and the Wnt/β-catenin signaling pathway remains to be elucidated. The results of wound healing and Transwell invasion assays revealed that apigenin was able to significantly suppress colorectal cancer cell proliferation, migration and invasion in a dose-dependent manner. An organoid culture assay revealed that apigenin was also able to suppress the growth of intestinal organoids. Furthermore, apigenin inhibited β-catenin/T-cell factor/lymphoid enhancer factor signaling activation, which was induced by LiCl in a dose-dependent manner. This inhibited β-catenin nuclear entry, and therefore the expression of Wnt downstream target genes. In conclusion, apigenin significantly suppressed colorectal cancer cell proliferation, migration, invasion and organoid growth by inhibiting the Wnt/β-catenin signaling pathway.

Genistein induces activation of the mitochondrial apoptosis pathway by inhibiting phosphorylation of Akt in colorectal cancer cells

CONTEXT

Genistein inhibits the proliferation and induces apoptosis of colorectal cancer cells; however, the underling molecular mechanisms remain to be determined.

AIM

The aim of this study was to investigate whether genistein reduces cell viability by suppressing the phosphorylation of AKT and activating the mitochondrial apoptosis pathway in colorectal cancer cells.

MATERIALS AND METHODS

The anti-proliferative effects of genistein (0, 25, 50, and 100 μM) on HCT-116 and LoVo cells were assessed using MTT assay. Genistein-induced apoptosis was measured by Hoechst 33258 staining and flow cytometry. The mRNA level of Bax was detected by real-time PCR. The protein levels of Bax, total Akt, and phosphorylated Akt were assessed by western blot.

RESULTS

The IC50 values of genistein were 690, 135, and 61 μM in HCT-116 cells and 204, 135, and 93 μM in LoVo cells after treatment for 24, 48, and 72 h, respectively. After treatment with different concentrations of genistein (0, 25, 50, and 100 μM) for 48 h, the early apoptotic cells in HCT-116 increased from 1.99% ± 0.55% to 6.78% ± 2.12%, 23.16% ± 3.87%, and 36.99% ± 3.76%, respectively. The same concentrations of genistein increased the early apoptotic cells in LoVo from 2.56% ± 1.42% to 3.21% ± 1.52%, 18.22% ± 3.56%, and 23.56% ± 3.02%, respectively. Moreover, genistein increased the mRNA and protein levels of Bax, while it inhibited the phosphorylation of Akt in HCT-116 cells.

CONCLUSION

Genistein inhibited cell proliferation and induced apoptosis of colorectal cancer cells. Genistein induced the mitochondrial pathway of apoptosis in HCT-116 cells by inhibiting phosphorylation of Akt.

KITLG is a novel target of miR-34c that is associated with the inhibition of growth and invasion in colorectal cancer cells

MiR-34c is considered a potent tumour suppressor because of its negative regulation of multiple target mRNAs that are critically associated with tumorigenesis and metastasis. In the present study, we demonstrated a novel target of miR-34c, KITLG, which has been implicated in colorectal cancer (CRC). First, we found a significant negative relationship between miR-34c and KITLG mRNA expression levels in CRC cell lines, including HT-29, HCT-116, SW480 and SW620 CRC cell lines. In silico analysis predicted putative binding sites for miR-34c in the 3' untranslated region (3'UTR) of KITLG mRNA. A dual-luciferase reporter assay further confirmed that KITLG is a direct target of miR-34c. Then, the cell lines were infected with lentiviruses expressing miR-34c or a miR-34c specific inhibitor. Restoration of miR-34c dramatically reduced the expression of KITLG mRNA and protein, while silencing of endogenous miR-34c increased the expression of KITLG protein. The miR-34c-mediated down-regulation of KITLG was associated with the suppression on proliferation, cellular transformation, migration and invasion of CRC cells, as well as the promotion on apoptosis. Knockdown of KITLG by its specific siRNA confirmed a critical role of KITLG down-regulation for the tumour-suppressive effects of miR-34c in CRC cells. In conclusion, our results demonstrated that miR-34c might interfere with KITLG-related CRC and could be a novel molecular target for CRC patients.

Control of colon cancer development and progression by selected estrogen receptor modulators

Estrogens behave as protective agents on the development of colorectal cancer, and hormonal-replacement therapy is associated with an increased survival rate in women with this disease, indicating that estrogenic therapy correlates with a better prognosis. The protective effect of estrogens on Fcolorectal cancer development and progression is presumably related to the expression of estrogen receptors in colon mucosa, with the estrogen receptor-β isoform being the predominant one. This observation suggests that estrogen receptor-β could have an inhibitory effect on colorectal cancer cell proliferation and a regulatory effect on colonic mucosa cell growth, opening the discussion on a pharmacologic approach to colorectal cancer prevention and therapy based on estrogenic compounds.

Biological characterization of a chimeric mouse-human IgM antibody directed against the 17-1A antigen

A chimeric antibody was constructed in which the murine H- and L-chain variable regions of mAb 17-1A, raised against human colorectal cancer cells, were joined with the human constant mu and kappa regions. Transfection of these constructs into the murine myeloma Sp2/0 resulted in the expression and secretion of a pentameric Ig, designated chimeric 17-1A IgM. The chimeric 17-1A IgM was subsequently compared to a previously described chimeric 17-1A IgG1 for biological activities. Both chimeric mAbs were equally effective (weight basis) in competing against the binding of murine 125I-17-1A to cultures of HT-29 colon carcinoma cells. The calculated association constants for the chimeric 17-1A IgM and IgG1 were 1.63 x 10(8) l/mol and 3.41 x 10(7) l/mol, respectively. Unlike chimeric 17-1A IgG1, the chimeric 17-1A IgM was able to render colon carcinoma target cells susceptible to lysis by both xenogeneic (rabbit) and human complement. The extent of complement-mediated lysis dependent upon chimeric 17-1A IgM was correlated to 17-1A antigen expression on target cells. HT-29 colon carcinoma cells treated with chimeric 17-1A IgM did not directly result in antibody-dependent cellular cytotoxicity by human peripheral blood monocytes. However, chimeric 17-1A IgM greatly enhanced the deposition of C3 on complement-treated HT-29 cells, and concomitant incubation with monocytes resulted in heightened lysis of the tumor cells. The feasibility of enhancing host defense against gastrointestinal malignancies by the administration of this chimeric 17-1A IgM may have certain clinical advantages.

Antibody-dependent cell-mediated cytotoxicity using a murine monoclonal antibody against human colorectal cancer in cancer patients

Antibody-dependent cell-mediated cytotoxicity (ADCC) mediated by a murine monoclonal antibody against human colorectal carcinoma, antibody 19-9, with human effector cells was tested in 33 patients with various carcinomas, 16 patients with benign lesions, and 13 normal controls, using a 12-h 51Cr release assay using human colorectal cancer cells as targets. Peripheral blood mononuclear cells (PBM) from these groups of patients and normal controls achieved moderate levels of target cell lysis in the presence of the monoclonal antibody at the high effector to target cell ratio of 200:1. The ADCC activity of PBM in cancer patients was significantly higher than that in either normal persons or patients with benign lesions. Since the ADCC was shown to be mainly mediated by adherent monocytes in the PBM, ADCC activity of monocytes from cancer patients was compared to those from control groups at an effector to target cell ratio of 30:1. The results also showed that the lytic capacity of monocytes was significantly higher in cancer patients than that in the control populations.