Apoptosis In Colorectal Carcinoma Cells Research Articles

Attenuating Colorectal Cancer Using Nine Cultivars of Australian Lupin Seeds: Apoptosis Induction Triggered by Mitochondrial Reactive Oxygen Species Generation and Caspases-3/7 Activation.

As Australian lupin cultivars are rich sources of polyphenols, dietary fibers, high-quality proteins, and abundant bioactive compounds with significant antioxidant, antidiabetic, and anticancer activities, this research work is aimed at investigating the colon cancer alleviation activity of nine cultivars of lupin seeds on HCT116 and HT29 colon carcinoma cell lines through anti-proliferation assay, measurement of apoptosis, and identification of the mechanism of apoptosis. Nine cultivars were pre-screened for anti-proliferation of HCT116 and HT29 cells along with consideration of the impact of heat processing on cancer cell viability. Mandelup and Jurien showed significant inhibition of HCT116 cells, whereas the highest inhibition of HT29 cell proliferation was attained by Jurien and Mandelup. Processing decreased the anti-proliferation activity drastically. Lupin cultivars Mandelup, Barlock, and Jurien (dose: 300 μg/mL) induced early and late apoptosis of colon cancer cells in Annexin V-FITC assay. The mechanism of apoptosis was explored, which involves boosting of caspases-3/7 activation and intracellular reactive oxygen species (ROS) generation in HCT116 cells (Mandelup and Barlock) and HT29 cells (Jurien and Mandelup). Thus, the findings showed that lupin cultivars arrest cell cycles by inducing apoptosis of colorectal carcinoma cells triggered by elevated ROS generation and caspases-3/7 activation.

GPX2 acts as an oncogene and cudraflavone C has an anti-tumor effect by suppressing GPX2-dependent Wnt/β-catenin pathway in colorectal cancer cells.

Colorectal carcinoma (CRC) is a common cancer associated with poor prognosis, and cudraflavone C (Cud C) is a natural flavonol with reported anti-CRC capacity. However, the precise mechanisms underlying the anti-CRC effect require further demonstration. The aim of present study was to evaluate the impact of Cud C on the cell viability and apoptosis of CRC cells and to determine the underlying mechanisms. The Human Protein Atlas (THPA) and Gene Expression Profiling Interactive Analysis (GEPIA) databases were used to analyze the expression status of glutathione peroxidase 2 (GPX2) in CRC. Cell viability was examined using cell counting kit-8 (CCK-8) assay. Flow cytometry was utilized to evaluate apoptosis. The levels of gene transcription and protein expression of GPX2, caspase-3, cleaved caspase-3), β-catenin, and c-Myc were determined by RT-qPCR and Western blotting. Our results showed that GPX2 was overexpressed in CRC as compared to normal tissue and the extent of GPX2 overexpression is greatest in CRC when compared with other cancers according to GEPIA and THPA databases. GPX2 knockdown significantly suppressed the cell viability, induced apoptosis of CRC cell lines, and restrained the activity of Wnt/β-catenin pathway. Cud C treatment decreased cell viability, induced apoptosis in CRC cell lines, and diminished the expression level of GPX2-dependent activation of Wnt/β-catenin pathway, while such effects can be abolished by GPX2 overexpression. In conclusion, Cud C suppressed GPX2-dependent Wnt/β-catenin pathway to exert anti-CRC function.

Hsa_circ_0005100 regulates tumorigenicity of colorectal carcinoma via miR-145-5p/MACC1 axis.

BackgroundCircular RNAs (circRNAs) are a kind of RNA molecules involved in the regulation of cancer progression, including colorectal carcinoma (CRC); nevertheless, their regulation mode is blurry. In the present work, we attempted to reveal the characteristics of hsa_hsa_circ_0005100 in CRC.MethodsDifferential expressions of hsa_circ_0005100, FMN2 mRNA, microRNA‐145‐5p (miR‐145‐5p), and MACC1 were indicated by qRT‐PCR and Western blot. The capacities of cell growth and motility were validated by the MTT assay, flow cytometry assay, EdU assay, colony formation assay, and transwell assay. Moreover, the targeted relationship of miR‐145‐5p and hsa_circ_0005100 or MACC1 was distinguished by dual‐luciferase reporter assay. The animal experiment was implemented to confirm the influence of hsa_circ_0005100 on tumorigenesis in vivo.ResultsHsa_circ_0005100 and MACC1 expression levels were increased, but miR‐145‐5p expression level was diminished in CRC. Hsa_circ_0005100 knockdown repressed cell proliferation, cell cycle, migration, and invasion, while expedited cell apoptosis in CRC cells. Furthermore, miR‐145‐5p was disclosed to block CRC via overturning MACC1. Hsa_circ_0005100 targeted miR‐145‐5p to modulate MACC1. Additionally, hsa_circ_0005100 knockdown also attenuated tumorigenesis in vivo.ConclusionHsa_circ_0005100 was a vital regulator in the development of CRC by miR‐145‐5p/MACC1 axis, which deepened the understanding of CRC pathogenesis from circRNA insights.

A Novel Peptide Derived from Arca inflata Induces Apoptosis in Colorectal Cancer Cells through Mitochondria and the p38 MAPK Pathway.

Colorectal carcinoma (CRC) is one of the major causes of cancer-related incidence and deaths. Here, we identified a novel antitumor peptide, P6, with a molecular weight of 2794.8 Da from a marine Chinese medicine, Arca inflata Reeve. The full amino acid sequence and secondary structure of P6 were determined by tandem mass de novo sequencing and circular dichroism spectroscopy, respectively. P6 markedly inhibited cell proliferation and colony formation, and induced apoptosis in CRC cells. Mechanistically, transcriptomics analysis and a serial functional evaluation showed that P6 induced colon cancer cell apoptosis through the activation of the p38-MAPK signaling pathway. Moreover, it was demonstrated that P6 exhibited antitumor effects in a tumor xenograft model, and induced cell cycle arrest in CRC cells in a concentration-dependent mode. These findings provide the first line of indication that P6 could be a potential therapeutic agent for CRC treatment.

Polymorphism rs2682818 participates in the progression of colorectal carcinoma via miR-618-TIMP1 regulatory axis

Colorectal carcinoma (CRC) has a high morbidity and mortality. Current studies have confirmed a variety of microRNA polymorphisms were associated with tumor susceptibility, however, the mechanisms are still unknown. In this study, we were aimed to clarify how polymorphism rs2682818 participated in the progression of CRC. First of all, the differential expression of miR-618 was assessed by quantitative real-time polymerase chain reaction in CRC patients with different genotypes of polymorphism rs2682818, including homozygous (TT) genotype, homozygous (GG) genotype and heterozygous (TG) genotype. Secondly, plasmids carried miR-168 precursor sequences harboring rs2682818 (SNP type) or without rs2682818 (wild type) were transfected into 293T cells to verify that polymorphism rs2682818 affected miR-618 expression. Thirdly, CCK-8 assay, flow cytometry assay, transwell assay and mouse xenograft assay were performed to measure the biological functions of miR-618 in CRC. Fourthly, the candidate target genes of miR-618 which were predicted by bioinformatics tools were verified by luciferase reporter assay. Finally, in order to explain the potential molecular mechanisms, western blotting was performed to demonstrate the differential expression and phosphorylation of pathway related proteins. The results showed that miR-618 was down-regulated in colon cancer, especially in CRC patients with rs2682818 GG homozygous genotype. Higher expression of mature miR-618 occurred in patients with TT homozygous genotype, and these patients usually had a longer survival time. Moreover, miR-618 mimic obviously impaired the growth and invasion ability of CRC cells, and miR-618 mimic also remarkably promoted CRC cell apoptosis. Our luciferase experiments confirmed that TIMP1 was a target of miR-618 in CRC cells. Knockdown of TIMP1 also significantly inhibited the malignant cytological features of CRC, including malignant growth and invasion as well as apoptosis resistance. In summary, polymorphism rs2682818 participated in the progression of CRC via affecting the expression of mature miR-618 in CRC cells, and miR-618 inhibited the progression of CRC via targeting TIMP1expression.

Transglutaminase 2 promotes tumorigenicity of colon cancer cells by inactivation of the tumor suppressor p53

Despite a high clinical need for the treatment of colorectal carcinoma (CRC) as the second leading cause of cancer-related deaths, targeted therapies are still limited. The multifunctional enzyme Transglutaminase 2 (TGM2), which harbors transamidation and GTPase activity, has been implicated in the development and progression of different types of human cancers. However, the mechanism and role of TGM2 in colorectal cancer are poorly understood. Here, we present TGM2 as a promising drug target.In primary patient material of CRC patients, we detected an increased expression and enzymatic activity of TGM2 in colon cancer tissue in comparison to matched normal colon mucosa cells. The genetic ablation of TGM2 in CRC cell lines using shRNAs or CRISPR/Cas9 inhibited cell expansion and tumorsphere formation. In vivo, tumor initiation and growth were reduced upon genetic knockdown of TGM2 in xenotransplantations. TGM2 ablation led to the induction of Caspase-3-driven apoptosis in CRC cells. Functional rescue experiments with TGM2 variants revealed that the transamidation activity is critical for the pro-survival function of TGM2. Transcriptomic and protein–protein interaction analyses applying various methods including super-resolution and time-lapse microscopy showed that TGM2 directly binds to the tumor suppressor p53, leading to its inactivation and escape of apoptosis induction.We demonstrate here that TGM2 is an essential survival factor in CRC, highlighting the therapeutic potential of TGM2 inhibitors in CRC patients with high TGM2 expression. The inactivation of p53 by TGM2 binding indicates a general anti-apoptotic function, which may be relevant in cancers beyond CRC.

Long Non-coding RNA EBLN3P Regulates UHMK1 Expression by Sponging miR-323a-3p and Promotes Colorectal Cancer Progression.

Background: Growing studies have demonstrated that long non-coding RNA (lncRNA) can act as crucial roles during the progression of various tumors, including colorectal carcinoma (CRC). We aimed to determine lncRNA endogenous bornavirus-like nucleoprotein (EBLN3P) expression in CRC and examine its influence on tumor behaviors of CRC cells.Materials and Methods: Quantitative real-time polymerase chain reaction was used to determine the expression levels of EBLN3P and miR-323a-3p in CRC tissues and cell lines. Cell viability, migration, invasion, and apoptosis were assessed by Cell Counting Kit 8, colony formation, Transwell assay, wound healing assays, and flow cytometry. Bioinformatics and dual-luciferase assays were used to investigate the interaction between EBLN3P and miR-323a-3p, as well as between miR-323a-3p and U2AF homology motif kinase 1 (UHMK1). Western blot was applied for detecting the expressions of the related proteins.Results: EBLN3P was highly expressed in CRC, and its high expression was distinctly associated with increased tumor size, histology/differentiation and advanced TNM stage, and poor clinical outcome of CRC patients. EBLN3P silencing significantly inhibited the proliferation and metastasis and induced the apoptosis of CRC cells. Mechanistically, overexpression of EBLN3P exhibited tumorigenic effects through downregulating the inhibitory effects of miR-323a-3p on UHMK1 expression. The correlation analysis confirmed the positive or negative association among EBLN3P, miR-323a-3p, and UHMK1.Conclusion: EBLN3P promoted the development of CRC via targeting miR-323a-3p/UHMK1, which provided a new idea for treating CRC.

Long noncoding RNA LINC01296 plays an oncogenic role in colorectal cancer by suppressing p15 expression.

ObjectiveTo examine the role of the long noncoding RNA LINC01296 in colorectal carcinoma (CRC) and to explore the underlying mechanism.MethodsWe detected LINC01296 expression levels in a cohort of 51 paired CRC and normal tissues. We also assessed the effects of LINC01296 on cell proliferation and apoptosis in CRC cells in vitro, and measured its effect on tumor growth in an in vivo mouse model. We identified the potential downstream targets of LINC01296 and assessed its regulatory effects.ResultsExpression levels of LINC01296 were elevated in 37/51 CRC tissues compared with the corresponding normal tissues and were significantly associated with tumor stage, lymph node metastasis, and distant metastasis. Knockdown of LINC01296 using antisense oligonucleotides inhibited cell proliferation and promoted apoptosis of colon cancer cells in vitro and inhibited tumor growth in vivo. Knockdown of LINC01296 also significantly increased the gene expression of p15 in colon cancer cells. LINC01296-specific suppression of p15 was validated by the interaction between enhancer of zeste homolog 2 and LINC01296.ConclusionOverexpression of LINC01296 suppressed the expression of p15 leading to CRC carcinogenesis. These findings may provide the basis for novel future CRC-targeted therapies.

MiR-93/HMGB3 regulatory axis exerts tumor suppressive effects in colorectal carcinoma cells

ObjectiveMicroRNA (miR)-93 has been proven to mediate the initiation and progression of colorectal carcinoma (CRC); however, the mechanisms by which miR-93 mediates CRC development need deeper elucidation. The present study is designed to investigate the association between miR-93 and high mobility group box 3 (HMGB3), as well as the functions of miR-93, in CRC. MethodsmiR-93 expression was quantified by RT-qPCR. CRC cells were transfected or cotransfected with miR-93 mimic, miR-93 inhibitor, pcDNA3.1-HMGB3 and sh-HMGB3, and then the proliferative, migratory and invasive capacities were detected in addition to the apoptotic rate. Western blotting assessed the expression levels of HMGB3, PI3K, p-PI3K, AKT and p-AKT. The interaction between miR-93 and HMGB3 was identified. ResultsIn CRC tissues, miR-93 was downregulated and HMGB3 was upregulated. LOVO and SW480 cells transfected with miR-93 mimic exhibited reduced proliferation, invasion and migration as well as increased apoptosis. The ratios of p-PI3K/PI3K and p-AKT/AKT were declined after miR-93 mimic was introduced into the CRC cell lines. miR-93 negatively downregulated HMGB3, and introduction of pcDNA3,1-HMGB3 could counteract, in part, the inhibitory effects of miR-93 on the malignant properties of CRC cells as well as the ratios of p-PI3K/PI3K and p-AKT/AKT. ConclusionmiR-93 targeted HMGB3 to block the activation of the PI3K/AKT pathway and thus enhance CRC cell apoptosis.

The lncRNA DLGAP1-AS1/miR-149-5p/TGFB2 axis contributes to colorectal cancer progression and 5-FU resistance by regulating smad2 pathway

Colorectal carcinoma (CRC) ranks as the third most common malignancy. Long non-coding RNA DLGAP1-AS1 was reported to be dysregulated and to play a pivotal role in hepatocellular carcinoma (HCC). This work aims to analyze the functions and molecular basis of DLGAP1-AS1 in CRC progression and 5-fluorouracil resistance. Cell Counting Kit-8 (CCK-8) assay, Transwell assay, flow cytometry, and western blot were utilized to measure the CRC cell activity, invasiveness, and apoptosis. RNA immunoprecipitation (RIP) and dual-luciferase reporter gene assay were adopted to verify the direct mutual action between DLGAP1-AS1 and miR-149-5p. The effect of DLGAP1-AS1 knockdown on tumor growth and chemosensitivity of 5-fluorouracil (5-FU) were investigated in the mouse CRC xenograft models. Functional assays showed that silencing DLGAP1-AS1 expression remarkably inhibited cell proliferation and aggressiveness ability and enhanced apoptosis rate and cell chemosensitivity to 5-FU. In addition, miR-149-5p was identified as a tumor suppressor and a direct downstream target of DLGAP1-AS1 in CRC. Furthermore, miR-149-5p was confirmed to directly bind to TGFB2 and DLGAP1-AS1 could regulate the expression of TGFB2 signaling pathway via miR-149-5p in CRC. These new findings indicate that DLGAP1-AS1 knockdown inhibited the progression of CRC and enhanced the 5-FU sensitivity of CRC cells through miR-149-5p/TGFB2 regulatory axis, suggesting that DLGAP1-AS1 may be a promising therapeutic target for CRC.

Upregulation of Rab31 is associated with poor prognosis and promotes colorectal carcinoma proliferation via the mTOR/p70S6K/Cyclin D1 signalling pathway

AimsRab31, a Rab5 subfamily member, has emerged as a modulator of membrane trafficking. Our study serves to clarify the role and mechanism of Rab31 in colorectal carcinoma (CRC) pathogenesis. Materials and methodsThe differential expression of Rab31 was examined in paired normal and cancerous colonic tissues by quantitative PCR, western blot and immunochemistry. The prognostic significance of Rab31 was analysed by univariate and multivariate survival analyses. We also investigated the effects of Rab31 on tumour growth in vitro. Key findingsWe observed that Rab31, which is related to histological differentiation in CRC, was markedly overexpressed in CRC cells. Moreover, patients who showed higher Rab31 levels had a shortened survival period relative to those with low Rab31 levels. Rab31 knockdown significantly downregulated cyclin D1, p-mTOR, and p-p70S6K expression. Moreover, the expression of Rab31-induced p-p70S6K was almost inhibited by rapamycin, a well-established inhibitor of mTOR. Similarly, rapamycin also significantly decreased the stimulatory effect of Rab31 on the expression of cyclin D1. SignificanceThese findings suggested that Rab31 enhanced proliferation, promoted cell cycle progression, and inhibited apoptosis of colorectal carcinoma cells through the mTOR pathway.

Upregulated SET Promotes Cell Survival Through Activating Akt/NF-κB Signal in Colorectal Carcinoma.

PurposeSET has been proven to be an oncogene, which promotes the initiation and progression in several kinds of malignant carcinomas. However, the expression and its functional roles in colorectal carcinoma (CRC) remained unknown.Materials and MethodsCRC tissues samples, CRC cell lines and xenograft mouse tumors were used in this study. The mRNA and protein expressions were detected by quantitative real-time polymerase chain reaction (qRT-PCR), immunohistochemistry (IHC), and Western blot (WB), respectively. siRNAs were used to silence the gene expression. Cell viability, cell proliferation, colony formation, and apoptosis were measured by MTS assay, EdU incorporation assay, plated colony formation assay, and flow cytometry, respectively. Western blot was applied to evaluate the levels of Akt, p-Akt, c-Myc and cyclin D1. Xenograft mouse model was performed to observe the role of SET in vivo.ResultsOur results revealed that SET was up-regulated in CRC, and the expression of SET was increased with the development of CRC. SET knockdown in vitro attenuated cell proliferation activity, and increased cell apoptosis in CRC cells. Moreover, the knockdown of SET reduces tumorigenic potential in nude mice. For the mechanism, knockdown of SET promoted the dephosphorylation of Akt, followed by suppressing the translocation of NF-κB to nucleus. In addition, SET knockdown-mediated dephosphorylation of Akt downregulated the expression of c-Myc and Cyclin D1, which inhibited the cell survival in CRC.ConclusionOur results indicated that SET promoted cell survival via activating Akt/NF-κB signaling pathway in CRC, which strongly suggested that SET might be a potential therapeutic target in the colorectal carcinoma treatment.

The extract of the immature fruit of Poncirus trifoliata induces apoptosis in colorectal cancer cells via mitochondrial autophagy

The immature fruits of Poncirus trifoliate are used as a medicine for the treatment of gastrointestinal disorders, inflammation, and allergies in East Asia. However, their effect on colon cancer cells remains unclear. We investigated the effect of the immature fruit of P. trifoliate extract on colorectal adenocarcinoma. The extract of the immature fruit of P. trifoliata inhibited the proliferation of CT-26 cells compared with untreated cells and it induced autophagy and apoptosis through the protein kinase B/mammalian target of rapamycin and 5′-AMP-activated protein kinase pathways. The number of autophagic vacuoles and autophage markers increased in response to the extract. At later time-points, apoptosis increased dose/time-dependently. In CT-26 cells pre-treated a pan-caspase inhibitor prior to P. trifoliata immature fruit extract treatment, we did not find any change in pro-caspase 3 and pro-PARP levels. Additionally, in cells pre-treated autphage inhibitor, SQSTM1/p62 and LC3AB, pro-caspase 3 and pro-PARP levels did not change. Our results indicate the molecular mechanisms that the extract of the immature fruit of P. trifoliata induces apoptosis in colorectal carcinoma cells by inducing mitochondrial autophagy. In this study, we provided a draft for further investigate the use of MEPT for colorectal cancer inhibition.

Integrin Subunit Alpha 5 (ITGA5) Gene Circular RNA Sponges microRNA-107 in Colorectal Carcinoma Cells and Tissues and Regulates the Expression of the Forkhead Box J3 (FOXJ3) Gene.

BackgroundCircular RNAs (circRNAs) can function as sponges for microRNA (miRNA) in carcinogenesis. This study aimed to investigate the role of the circRNA of the integrin subunit alpha 5 (ITGA5) gene and microRNA-107 (miR-107) in human colorectal carcinoma (CRC) cells in vitro and tissue samples from patients with CRC and the expression of forkhead box J3 (FOXJ3) protein.Material/MethodsThirty paired CRC tissue samples and adjacent normal colon tissue samples were studied. Human CRC cell lines, including HT29, SW480, LoVo, and HIEC cells, were studied for cell proliferation using the cell counting kit-8 (CCK-8) assay. Cell migration was studied using a transwell assay, and cell apoptosis was determined using flow cytometry. The luciferase reporter assay was used to study the interactions between ITGA5 circRNA, FOXJ3, and miR-107 in human CRC cells. The expression of ITGA5 circRNA and miR-107 was determined using quantitative real-time polymerase chain reaction (qRT-PCR). The protein levels of FOXJ3 were measured by Western blot.ResultsThe expression of ITGA5 circRNA was significantly reduced in CRC tissues and CRC cell lines. High ITGA5 circRNA expression inhibited the proliferation and cell migration of CRC cells and promoted the apoptosis of CRC cells. The luciferase reporter assay confirmed that ITGA5 circRNA bound to miR-107, which directly targeted FOXJ3.ConclusionsITGA5 circRNA may act as a sponge for miR-107 to upregulate FOXJ3 expression and act as a tumor suppressor in CRC cells.

Design, synthesis and biological evaluation of a novel tubulin inhibitor SKLB0565 targeting the colchicine binding site.

A series of 3-(((9H-purin-6-yl) amino) methyl) pyridin-2(1H)-one derivatives were designed, synthesized and confirmed as tubulin polymerization inhibitors. All compounds were evaluated for their anti-proliferative activities on three colorectal carcinoma (CRC) cell lines. Among these compounds, SKLB0565 displayed noteworthy potency against eight CRC cell lines with IC50 values ranging from 0.012μM and 0.081μM. Besides, SKLB0565 inhibited tubulin polymerization, caused G2/M phase cell cycle arrest, depolarized mitochondria and induced cell apoptosis in CRC cells. Furthermore, SKLB0565 suppressed cell migration and disrupted the capillary tube formation of human umbilical vein endothelial cells (HUVECs). Our data clarified that SKLB0565 is a promising anti-tubulin agent for CRC therapy which is worthy of further evaluation.

Downregulation of RPS15A by miR-29a-3p attenuates cell proliferation in colorectal carcinoma.

miR-29a-3p has been reported to function as a tumor suppressor in several cancers. However, the biological function role of miR-29a-3p in colorectal carcinoma (CRC) has not been well investigated. In this study, we found that miR-29a-3p was at lower level expression in CRC tissues and cell lines. Experimental up-regulation miR-29a-3p with mimic could inhibit cell proliferation, but induced cell cycle arrest at G0/G1 phase and apoptosis in CRC cells. MiR-29a-3p overexpression significantly down-regulated the expression levels of CDK4, Cyclin D1, and Bax, but up-regulated the expression levels of p21 and Bcl-2 in DLD-1 cells. Moreover, ribosomal protein S15A (RPS15A) was predicted and confirmed as a direct target gene of miR-29a-3p. Furthermore, restoration of RPS15A could rescue the phenotypic changes caused by miR-29a-3p. The findings demonstrate miR-29a-3p inhibits CRC cell function possibly by targeting RPS15A, which might be exploited therapeutically in CRC.

Discovery of 3-(((9H-purin-6-yl)amino)methyl)-4,6-dimethylpyridin-2(1H)-one derivatives as novel tubulin polymerization inhibitors for treatment of cancer

A new series of 3-(((9H-purin-6-yl)amino)methyl)-4,6-dimethylpyridin-2(1H)-one derivatives were designed, synthesized and demonstrated to act as tubulin polymerization inhibitors. These new derivatives showed significant antitumor activities, among which SKLB0533 demonstrated to be the most potent compound, with IC50 values ranging from 44.5 to 135.5 nM against seven colorectal carcinoma (CRC) cell lines. Remarkably, SKLB0533 exhibited no activity against other potential targets, such as 420 kinases and EZH2. Besides, SKLB0533 inhibited tubulin polymerization, arrested the cell cycle at the G2/M phase and induced apoptosis in CRC cells. Furthermore, SKLB0533 suppressed tumour growth in the HCT116 xenograft model without inducing notable major organ-related toxicity, suggesting that SKLB0533 could be used as a promising lead compound for the development of new antitumor agents.

Activation and Expression of Peroxisome Proliferator-Activated Receptor Alpha Are Associated with Tumorigenesis in Colorectal Carcinoma.

Peroxisome proliferator-activated receptor alpha (PPAR-α) belongs to the PPAR family and plays a critical role in inhibiting cell proliferation and tumorigenesis in various tumors. However, the role of PPAR-α in colorectal tumorigenesis is unclear. In the present study, we found that fenofibrate, a PPAR-α agonist, significantly inhibited cell proliferation and induced apoptosis in colorectal carcinoma cells. In addition, PPAR-α was expressed in the nucleus of colorectal carcinoma cells, and the expression of nuclear PPAR-α increased in colorectal carcinoma tissue compared with that of normal epithelium tissue (P<0.01). The correlation between the expression of nuclear PPAR-α and clinicopathological factors was evaluated in human colorectal carcinoma tissues, and the nuclear expression of PPAR-α was significantly higher in well-to-moderately differentiated adenocarcinoma than in mucinous adenocarcinoma (P<0.05). These findings indicate that activation of PPAR-α may be involved in anticancer effects in colorectal carcinomas, and nuclear expression of PPAR-α may be a therapeutic target for colorectal adenocarcinoma treatment.

Mathematical Modeling Highlights the Complex Role of AKT in TRAIL-Induced Apoptosis of Colorectal Carcinoma Cells

SummaryProtein kinase B/AKT is a highly connected protein involved in a range of signaling pathways. Although it is known to regulate several proteins in the apoptotic pathway, its system-level effects remain poorly understood. We investigated the dynamic interactions between AKT and key apoptotic proteins and constructed a deterministic ordinary differential equation protein interaction model of extrinsic apoptosis. Incorporating AKT and its indirect inhibitor, phosphatase and tensin homolog (PTEN), this was used to generate predictions of system dynamics. Using eigen analysis, we identified AKT and cytochrome c as the protein species most sensitive to perturbations. Cell death assays in Type II HCT116 colorectal carcinoma cells revealed a tendency toward Type I cell death behavior in the XIAP−/− background, with cells displaying accelerated TRAIL-induced apoptosis. Finally, AKT inhibition experiments implicated AKT and not PTEN in influencing apoptotic proteins during early phases of TRAIL-induced apoptosis.

Tannic acid-stabilized gold nano-particles are superior to native tannic acid in inducing ROS-dependent mitochondrial apoptosis in colorectal carcinoma cells via the p53/AKT axis.

Gold nanoparticle formulated tannic acid (AuNP-TA) was synthesized, and its anticancer activity was compared to that of free tannic acid (TA). The half maximal inhibitory concentration (IC50) was reduced by half when cell lines were treated with AuNP-TA as compared to IC50 values upon free TA treatment. Both showed better cytotoxic activity in HCT116 cell line as compared to MCF7 and HepG2. AuNP-TA induced death of HCT116 cells was associated with characteristic apoptotic changes. At the same treatment dose, AuNP-TA generated more ROS, caused a more extensive DNA damage and promoted higher expression of p53 and p21 than TA. Treatment with AuNP-TA regulated generation of p53 and ROS bi-directionally. Binding studies showed that TA lowered the expression of Akt, which inhibited the survival of colon cancer cells. Also, cell cycle arrest at the G2/M phase, enhanced expression of caspase-3/9, Bak, and Bax, loss of mitochondrial membrane potential, and enhanced level of cytosolic cytochrome c were observed in AuNP-TA treated HCT116 cells. Thus, AuNP-TA is more efficient than TA in inducing apoptotic cell death of HCT116 cells via the ROS/P53/Akt axis.